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Hinrichs GR, Jensen BL. Optimizing diuretic treatment of patients with edema and nephrotic syndrome. Acta Physiol (Oxf) 2024:e14195. [PMID: 38924287 DOI: 10.1111/apha.14195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024]
Affiliation(s)
- Gitte R Hinrichs
- Department of Molecular Medicine, Cardiovascular and Renal Research Unit, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - Boye L Jensen
- Department of Molecular Medicine, Cardiovascular and Renal Research Unit, University of Southern Denmark, Odense, Denmark
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2
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Ray EC, Nickerson A, Sheng S, Carrisoza-Gaytan R, Lam T, Marciszyn A, Zhang L, Jordahl A, Bi C, Winfrey A, Kou Z, Gingras S, Kirabo A, Satlin LM, Kleyman TR. Influence of proteolytic cleavage of ENaC's γ subunit upon Na + and K + handling. Am J Physiol Renal Physiol 2024; 326:F1066-F1077. [PMID: 38634134 DOI: 10.1152/ajprenal.00027.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/27/2024] [Accepted: 04/09/2024] [Indexed: 04/19/2024] Open
Abstract
The epithelial Na+ channel (ENaC) γ subunit is essential for homeostasis of Na+, K+, and body fluid. Dual γ subunit cleavage before and after a short inhibitory tract allows dissociation of this tract, increasing channel open probability (PO), in vitro. Cleavage proximal to the tract occurs at a furin recognition sequence (143RKRR146, in the mouse γ subunit). Loss of furin-mediated cleavage prevents in vitro activation of the channel by proteolysis at distal sites. We hypothesized that 143RKRR146 mutation to 143QQQQ146 (γQ4) in 129/Sv mice would reduce ENaC PO, impair flow-stimulated flux of Na+ (JNa) and K+ (JK) in perfused collecting ducts, reduce colonic amiloride-sensitive short-circuit current (ISC), and impair Na+, K+, and body fluid homeostasis. Immunoblot of γQ4/Q4 mouse kidney lysates confirmed loss of a band consistent in size with the furin-cleaved proteolytic fragment. However, γQ4/Q4 male mice on a low Na+ diet did not exhibit altered ENaC PO or flow-induced JNa, though flow-induced JK modestly decreased. Colonic amiloride-sensitive ISC in γQ4/Q4 mice was not altered. γQ4/Q4 males, but not females, exhibited mildly impaired fluid volume conservation when challenged with a low Na+ diet. Blood Na+ and K+ were unchanged on a regular, low Na+, or high K+ diet. These findings suggest that biochemical evidence of γ subunit cleavage should not be used in isolation to evaluate ENaC activity. Furthermore, factors independent of γ subunit cleavage modulate channel PO and the influence of ENaC on Na+, K+, and fluid volume homeostasis in 129/Sv mice, in vivo.NEW & NOTEWORTHY The epithelial Na+ channel (ENaC) is activated in vitro by post-translational proteolysis. In vivo, low Na+ or high K+ diets enhance ENaC proteolysis, and proteolysis is hypothesized to contribute to channel activation in these settings. Using a mouse expressing ENaC with disruption of a key proteolytic cleavage site, this study demonstrates that impaired proteolytic activation of ENaC's γ subunit has little impact upon channel open probability or the ability of mice to adapt to low Na+ or high K+ diets.
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Affiliation(s)
- Evan C Ray
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Andrew Nickerson
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Shaohu Sheng
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Rolando Carrisoza-Gaytan
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York City, New York, United States
| | - Tracey Lam
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Allison Marciszyn
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Lei Zhang
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Alexa Jordahl
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Chunming Bi
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Aaliyah Winfrey
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Zhaohui Kou
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Sebastien Gingras
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University, Nashville, Tennessee, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York City, New York, United States
| | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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3
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Schork A, Vogel E, Bohnert BN, Essigke D, Wörn M, Fischer I, Heyne N, Birkenfeld AL, Artunc F. Amiloride versus furosemide for the treatment of edema in patients with nephrotic syndrome: A pilot study (AMILOR). Acta Physiol (Oxf) 2024:e14183. [PMID: 38822593 DOI: 10.1111/apha.14183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 05/14/2024] [Accepted: 05/18/2024] [Indexed: 06/03/2024]
Abstract
AIM In rodent models of nephrotic syndrome (NS), edema formation was prevented by blockade of the epithelial sodium channel ENaC with amiloride. However, apart from case reports, there is no evidence favoring ENaC blockade in patients with NS. METHODS The monocentric randomized controlled AMILOR study investigated the antiedematous effect of amiloride (starting dose 5 mg/day, max. 15 mg/day) in comparison to standard therapy with the loop diuretic furosemide (40 mg/day, max. 120 mg/day) over 16 days. Overhydration (OH) was measured by bioimpedance spectroscopy (BCM, Fresenius). Depending on the OH response, diuretic dose was adjusted on days 2, 5, 8 and 12, and if necessary, hydrochlorothiazide (HCT) was added from d8 (12.5 mg/day, max. 25 mg/day). The primary endpoint was the decrease in OH on d8. The study was terminated prematurely due to insufficient recruitment and a low statistical power due to a low actual effect size. RESULTS Median baseline OH was +26.4 (interquartile range 15.5-35.1)% extracellular water (ECW) in the amiloride arm and + 27.9 (24.1-29.4)% ECW in the furosemide arm and decreased by 1.95 (0.80-6.40) and 5.15 (0.90-8.30)% ECW after 8 days, respectively, and by 10.10 (1.30-14.40) and 7.40 (2.80-10.10)% ECW after 16 days, respectively. OH decrease on d8 and d16 was not significantly different between both arms. CONCLUSION The AMILOR study is the first randomized controlled pilot study suggesting a similar antiedematous effect as furosemide. Further studies are required to better define the role of amiloride in NS (EudraCT 2019-002607-18).
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Affiliation(s)
- Anja Schork
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Elisabeth Vogel
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Bernhard N Bohnert
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Daniel Essigke
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Matthias Wörn
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Imma Fischer
- Institute for Clinical Epidemiology and Applied Biometry, University Hospital Tübingen, Tübingen, Germany
| | - Nils Heyne
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Andreas L Birkenfeld
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Ferruh Artunc
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
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Huang N, Wang Q, Bernard RB, Chen CY, Hu JM, Wang JK, Chan KS, Johnson MD, Lin CY. SPINT2 mutations in the Kunitz domain 2 found in SCSD patients inactivate HAI-2 as prostasin inhibitor via abnormal protein folding and N-glycosylation. Hum Mol Genet 2024; 33:752-767. [PMID: 38271183 PMCID: PMC11031362 DOI: 10.1093/hmg/ddae005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 11/30/2023] [Accepted: 01/05/2024] [Indexed: 01/27/2024] Open
Abstract
Mutations in the Kunitz-type serine protease inhibitor HAI-2, encoded by SPINT2, are responsible for the pathogenesis of syndromic congenital sodium diarrhea (SCSD), an intractable secretory diarrhea of infancy. Some of the mutations cause defects in the functionally required Kunitz domain 1 and/or subcellular targeting signals. Almost all SCSD patients, however, harbor SPINT2 missense mutations that affect the functionally less important Kunitz domain 2. How theses single amino acid substitutions inactivate HAI-2 was, here, investigated by the doxycycline-inducible expression of three of these mutants in HAI-2-knockout Caco-2 human colorectal adenocarcinoma cells. Examining protein expressed from these HAI-2 mutants reveals that roughly 50% of the protein is synthesized as disulfide-linked oligomers that lose protease inhibitory activity due to the distortion of the Kunitz domains by disarrayed disulfide bonding. Although the remaining protein is synthesized as monomers, its glycosylation status suggests that the HAI-2 monomer remains in the immature, lightly glycosylated form, and is not converted to the heavily glycosylated mature form. Heavily glycosylated HAI-2 possesses full anti-protease activity and appropriate subcellular targeting signals, including the one embedded in the complex-type N-glycan. As predicted, these HAI-2 mutants cannot suppress the excessive prostasin proteolysis caused by HAI-2 deletion. The oligomerization and glycosylation defects have also been observed in a colorectal adenocarcinoma line that harbors one of these SPINT2 missense mutations. Our study reveals that the abnormal protein folding and N-glycosylation can cause widespread HAI-2 inactivation in SCSD patents.
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Affiliation(s)
- Nanxi Huang
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, 3970 Reservoir Road NW W422 New Research Building, Washington DC 20057, United States
| | - Qiaochu Wang
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, 3970 Reservoir Road NW W422 New Research Building, Washington DC 20057, United States
| | - Robert B Bernard
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, 3970 Reservoir Road NW W422 New Research Building, Washington DC 20057, United States
| | - Chao-Yang Chen
- School of Medicine, National Defense Medical Center, No. 161, sec. 6, Minquan E. Road, Neihu Dist. Taipei City 11490, Taiwan, ROC
- Division of Colorectal Surgery, Department of Surgery, Tri-Service General Hospital, No. 325, Sec. 2, Chenggon Road, Neihu Dist. Taipei City 114202, Taiwan, ROC
| | - Je-Ming Hu
- School of Medicine, National Defense Medical Center, No. 161, sec. 6, Minquan E. Road, Neihu Dist. Taipei City 11490, Taiwan, ROC
- Division of Colorectal Surgery, Department of Surgery, Tri-Service General Hospital, No. 325, Sec. 2, Chenggon Road, Neihu Dist. Taipei City 114202, Taiwan, ROC
- Graduate Institute of Medical Sciences, National Defense Medical Center, No. 161, sec. 6, Minquan E. Neihu Dist. Taipei City 11490, Taiwan, ROC
| | - Jehng-Kang Wang
- Department of Biochemistry, National Defense Medical Center, No. 161, sec. 6, Minquan E. Road, Taipei City, 11490, Taiwan, ROC
| | - Khee-Siang Chan
- Department of Intensive Care Medicine, Chi Mei Medical Center, No. 901, Zhonghua Road, Yongkang Dist., Tainan City, 71004, Taiwan, ROC
| | - Michael D Johnson
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, 3970 Reservoir Road NW W422 New Research Building, Washington DC 20057, United States
| | - Chen-Yong Lin
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, 3970 Reservoir Road NW W422 New Research Building, Washington DC 20057, United States
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Sure F, Einsiedel J, Gmeiner P, Duchstein P, Zahn D, Korbmacher C, Ilyaskin AV. The small molecule activator S3969 stimulates the epithelial sodium channel by interacting with a specific binding pocket in the channel's β-subunit. J Biol Chem 2024; 300:105785. [PMID: 38401845 PMCID: PMC11065748 DOI: 10.1016/j.jbc.2024.105785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/13/2024] [Accepted: 02/19/2024] [Indexed: 02/26/2024] Open
Abstract
The epithelial sodium channel (ENaC) is essential for mediating sodium absorption in several epithelia. Its impaired function leads to severe disorders, including pseudohypoaldosteronism type 1 and respiratory distress. Therefore, pharmacological ENaC activators have potential therapeutic implications. Previously, a small molecule ENaC activator (S3969) was developed. So far, little is known about molecular mechanisms involved in S3969-mediated ENaC stimulation. Here, we identified an S3969-binding site in human ENaC by combining structure-based simulations with molecular biological methods and electrophysiological measurements of ENaC heterologously expressed in Xenopus laevis oocytes. We confirmed a previous observation that the extracellular loop of β-ENaC is essential for ENaC stimulation by S3969. Molecular dynamics simulations predicted critical residues in the thumb domain of β-ENaC (Arg388, Phe391, and Tyr406) that coordinate S3969 within a binding site localized at the β-γ-subunit interface. Importantly, mutating each of these residues reduced (R388H; R388A) or nearly abolished (F391G; Y406A) the S3969-mediated ENaC activation. Molecular dynamics simulations also suggested that S3969-mediated ENaC stimulation involved a movement of the α5 helix of the thumb domain of β-ENaC away from the palm domain of γ-ENaC. Consistent with this, the introduction of two cysteine residues (βR437C - γS298C) to form a disulfide bridge connecting these two domains prevented ENaC stimulation by S3969 unless the disulfide bond was reduced by DTT. Finally, we demonstrated that S3969 stimulated ENaC endogenously expressed in cultured human airway epithelial cells (H441). These new findings may lead to novel (patho-)physiological and therapeutic concepts for disorders associated with altered ENaC function.
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Affiliation(s)
- Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jürgen Einsiedel
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Patrick Duchstein
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dirk Zahn
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
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Rickman OJ, Guignard E, Chabanon T, Bertoldi G, Auberson M, Hummler E. Tmprss2 maintains epithelial barrier integrity and transepithelial sodium transport. Life Sci Alliance 2024; 7:e202302304. [PMID: 38171596 PMCID: PMC10765116 DOI: 10.26508/lsa.202302304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024] Open
Abstract
The mouse cortical collecting duct cell line presents a tight epithelium with regulated ion and water transport. The epithelial sodium channel (ENaC) is localized in the apical membrane and constitutes the rate-limiting step for sodium entry, thereby enabling transepithelial transport of sodium ions. The membrane-bound serine protease Tmprss2 is co-expressed with the alpha subunit of ENaC. αENaC gene expression followed the Tmprss2 expression, and the absence of Tmprss2 resulted not only in down-regulation of αENaC gene and protein expression but also in abolished transepithelial sodium transport. In addition, RNA-sequencing analyses unveiled drastic down-regulation of the membrane-bound protease CAP3/St14, the epithelial adhesion molecule EpCAM, and the tight junction proteins claudin-7 and claudin-3 as also confirmed by immunohistochemistry. In summary, our data clearly demonstrate a dual role of Tmprss2 in maintaining not only ENaC-mediated transepithelial but also EpCAM/claudin-7-mediated paracellular barrier; the tight epithelium of the mouse renal mCCD cells becomes leaky. Our working model proposes that Tmprss2 acts via CAP3/St14 on EpCAM/claudin-7 tight junction complexes and through regulating transcription of αENaC on ENaC-mediated sodium transport.
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Affiliation(s)
- Olivia J Rickman
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Emma Guignard
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Thomas Chabanon
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Giovanni Bertoldi
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Muriel Auberson
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- https://ror.org/019whta54 Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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7
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Ray EC, Nickerson A, Sheng S, Carrisoza-Gaytan R, Lam T, Marciszyn A, Zhang L, Jordahl A, Bi C, Winfrey A, Kou Z, Gingras S, Kirabo A, Satlin LM, Kleyman TR. Proteolytic Cleavage of the ENaC γ Subunit - Impact Upon Na + and K + Handling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.12.579964. [PMID: 38405735 PMCID: PMC10888851 DOI: 10.1101/2024.02.12.579964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The ENaC gamma subunit is essential for homeostasis of Na + , K + , and body fluid. Dual subunit cleavage before and after a short inhibitory tract allows dissociation of this tract, increasing channel open probability (P O ), in vitro . Cleavage proximal to the tract occurs at a furin recognition sequence ( 143 RKRR 146 in mouse). Loss of furin-mediated cleavage prevents in vitro activation of the channel by proteolysis at distal sites. We hypothesized that 143 RKRR 146 mutation to 143 QQQQ 146 ( Q4 ) in 129/Sv mice would reduce ENaC P O , impair flow-stimulated flux of Na + (J Na ) and K + (J K ) in perfused collecting ducts, reduce colonic amiloride-sensitive short circuit current (I SC ), and impair Na + , K + , and body fluid homeostasis. Immunoblot of Q4/Q4 mouse kidney lysates confirmed loss of a band consistent in size with the furin-cleaved proteolytic fragment. However, Q4/Q4 male mice on a low Na + diet did not exhibit altered ENaC P O or flow-induced J Na , though flow-induced J K modestly decreased. Colonic amiloride-sensitive I SC in Q4/Q4 mice was not altered. Q4/Q4 males, but not females, exhibited mildly impaired fluid volume conservation when challenged with a low Na + diet. Blood Na + and K + were unchanged on a regular, low Na + , or high K + diet. These findings suggest that biochemical evidence of gamma subunit cleavage should not be used in isolation to evaluate ENaC activity. Further, factors independent of gamma subunit cleavage modulate channel P O and the influence of ENaC on Na + , K + , and fluid volume homeostasis in 129/Sv mice, in vivo .
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8
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Ortmann LA, Nandi S, Li YL, Zheng H, Patel KP. Activation of renal epithelial Na + channels (ENaC) in infants with congenital heart disease. Front Pediatr 2024; 12:1338672. [PMID: 38379911 PMCID: PMC10876900 DOI: 10.3389/fped.2024.1338672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 01/25/2024] [Indexed: 02/22/2024] Open
Abstract
Introduction This study was designed to measure the concentration and activity of urinary proteases that activate renal epithelial sodium channel (ENaC) mediated Na+ transport in infants with congenital heart disease, a potential mechanism for fluid retention. Methods Urine samples from infants undergoing cardiac surgery were collected at three time points: T1) pre-operatively, T2) 6-8 h after surgery, and T3) 24 h after diuretics. Urine was collected from five heathy infant controls. The urine was tested for four proteases and whole-cell patch-clamp testing was conducted in renal collecting duct M-1 cells to test whether patient urine increased Na+ currents consistent with ENaC activation. Results Heavy chain of plasminogen, furin, and prostasin were significantly higher in cardiac patients prior to surgery compared to controls. There was no difference in most proteases before and after surgery. Urine from cardiac patients produced a significantly greater increase in Na+ inward currents compared to healthy controls. Conclusion Urine from infants with congenital heart disease is richer in proteases and has the potential to increase activation of ENaC in the nephron to enhance Na+ reabsorption, which may lead to fluid retention in this population.
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Affiliation(s)
- Laura A. Ortmann
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE, United States
| | - Shyam Nandi
- Department of Integrative and Cellular Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Yu-long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Hong Zheng
- Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Kaushik P. Patel
- Department of Integrative and Cellular Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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9
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Nickerson AJ, Mutchler SM, Sheng S, Cox NA, Ray EC, Kashlan OB, Carattino MD, Marciszyn AL, Winfrey A, Gingras S, Kirabo A, Hughey RP, Kleyman TR. Mice lacking γENaC palmitoylation sites maintain benzamil-sensitive Na+ transport despite reduced channel activity. JCI Insight 2023; 8:e172051. [PMID: 37707951 PMCID: PMC10721255 DOI: 10.1172/jci.insight.172051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/12/2023] [Indexed: 09/16/2023] Open
Abstract
Epithelial Na+ channels (ENaCs) control extracellular fluid volume by facilitating Na+ absorption across transporting epithelia. In vitro studies showed that Cys-palmitoylation of the γENaC subunit is a major regulator of channel activity. We tested whether γ subunit palmitoylation sites are necessary for channel function in vivo by generating mice lacking the palmitoylated cysteines (γC33A,C41A) using CRISPR/Cas9 technology. ENaCs in dissected kidney tubules from γC33A,C41A mice had reduced open probability compared with wild-type (WT) littermates maintained on either standard or Na+-deficient diets. Male mutant mice also had higher aldosterone levels than WT littermates following Na+ restriction. However, γC33A,C41A mice did not have reduced amiloride-sensitive Na+ currents in the distal colon or benzamil-induced natriuresis compared to WT mice. We identified a second, larger conductance cation channel in the distal nephron with biophysical properties distinct from ENaC. The activity of this channel was higher in Na+-restricted γC33A,C41A versus WT mice and was blocked by benzamil, providing a possible compensatory mechanism for reduced prototypic ENaC function. We conclude that γ subunit palmitoylation sites are required for prototypic ENaC activity in vivo but are not necessary for amiloride/benzamil-sensitive Na+ transport in the distal nephron or colon.
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Affiliation(s)
| | | | | | | | | | - Ossama B. Kashlan
- Department of Medicine
- Department of Computational and Systems Biology
| | | | | | | | - Sebastien Gingras
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | | | - Thomas R. Kleyman
- Department of Medicine
- Department of Cell Biology, and
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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10
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Iwata Y, Deng Q, Kakizoe Y, Nakagawa T, Miyasato Y, Nakagawa M, Nishiguchi K, Nagayoshi Y, Narita Y, Izumi Y, Kuwabara T, Adachi M, Mukoyama M. A Serine Protease Inhibitor, Camostat Mesilate, Suppresses Urinary Plasmin Activity and Alleviates Hypertension and Podocyte Injury in Dahl Salt-Sensitive Rats. Int J Mol Sci 2023; 24:15743. [PMID: 37958726 PMCID: PMC10650472 DOI: 10.3390/ijms242115743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 10/25/2023] [Accepted: 10/28/2023] [Indexed: 11/15/2023] Open
Abstract
In proteinuric renal diseases, the serine protease (SP) plasmin activates the epithelial sodium channel (ENaC) by cleaving its γ subunit. We previously demonstrated that a high-salt (HS) diet provoked hypertension and proteinuria in Dahl salt-sensitive (DS) rats, accompanied by γENaC activation, which were attenuated by camostat mesilate (CM), an SP inhibitor. However, the effects of CM on plasmin activity in DS rats remain unclear. In this study, we investigated the effects of CM on plasmin activity, ENaC activation, and podocyte injury in DS rats. The DS rats were divided into the control diet, HS diet (8.0% NaCl), and HS+CM diet (0.1% CM) groups. After weekly blood pressure measurement and 24-h urine collection, the rats were sacrificed at 5 weeks. The HS group exhibited hypertension, massive proteinuria, increased urinary plasmin, and γENaC activation; CM treatment suppressed these changes. CM prevented plasmin(ogen) attachment to podocytes and mitigated podocyte injury by reducing the number of apoptotic glomerular cells, inhibiting protease-activated receptor-1 activation, and suppressing inflammatory and fibrotic cytokine expression. Our findings highlight the detrimental role of urinary plasmin in the pathogenesis of salt-sensitive hypertension and glomerular injury. Targeting plasmin with SP inhibitors, such as CM, may be a promising therapeutic approach for these conditions.
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Affiliation(s)
- Yasunobu Iwata
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Qinyuan Deng
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yutaka Kakizoe
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
- Comprehensive Clinical Education, Training and Development Center, Kumamoto University Hospital, Kumamoto 860-8556, Japan
| | - Terumasa Nakagawa
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yoshikazu Miyasato
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Miyuki Nakagawa
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Kayo Nishiguchi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yu Nagayoshi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yuki Narita
- Department of Pharmacy, Kumamoto University Hospital, Kumamoto 860-8556, Japan
| | - Yuichiro Izumi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Takashige Kuwabara
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Masataka Adachi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
- Comprehensive Clinical Education, Training and Development Center, Kumamoto University Hospital, Kumamoto 860-8556, Japan
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11
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Hinrichs GR, Nielsen JR, Birn H, Bistrup C, Jensen BL. Amiloride evokes significant natriuresis and weight loss in kidney transplant recipients with and without albuminuria. Am J Physiol Renal Physiol 2023; 325:F426-F435. [PMID: 37560772 DOI: 10.1152/ajprenal.00108.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/14/2023] [Accepted: 08/03/2023] [Indexed: 08/11/2023] Open
Abstract
Albuminuria in kidney transplant recipients (KTRs) is associated with hypertension and aberrant glomerular filtration of serine proteases that may proteolytically activate the epithelial Na+ channel (ENaC). The present nonrandomized, pharmacodynamic intervention study aimed to investigate if inhibition of ENaC increases Na+ excretion and reduces extracellular volume in KTRs dependent on the presence of albuminuria. KTRs with and without albuminuria (albumin-to-creatinine ratio > 300 mg/g, n = 7, and <30 mg/g, n = 7, respectively) were included and ingested a diet with fixed Na+ content (150 mmol/day) for 5 days. On the last day, amiloride at 10 mg was administered twice. Body weight, 24-h urine electrolyte excretion, body water content, and ambulatory blood pressure as well as plasma renin, angiotensin II, and aldosterone concentrations were determined before and after amiloride. Amiloride led to a significant decrease in body weight, increase in 24-h urinary Na+ excretion, and decrease in 24-h urinary K+ excretion in both groups. Urine output increased in the nonalbuminuric group only. There was no change in plasma renin, aldosterone, and angiotensin II concentrations after amiloride, whereas a significant decrease in nocturnal systolic blood pressure and increase in 24-h urine aldosterone excretion was observed in albuminuric KTRs only. There was a significant correlation between 24-h urinary albumin excretion and amiloride-induced 24-h urinary Na+ excretion. In conclusion, ENaC activity contributes to Na+ and water retention in KTRs with and without albuminuria. ENaC is a relevant pharmacological target in KTRs; however, larger and long-term studies are needed to evaluate whether the magnitude of this effect depends on the presence of albuminuria.NEW & NOTEWORTHY Amiloride has a significant natriuretic effect in kidney transplant recipients (KTRs) that relates to urinary albumin excretion. The epithelial Na+ channel may be a relevant direct pharmacological target to counter Na+ retention and hypertension in KTRs. Epithelial Na+ channel blockers should be further investigated as a mean to mitigate Na+ and water retention and to potentially obtain optimal blood pressure control in KTRs.
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Affiliation(s)
- Gitte Rye Hinrichs
- Department of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
- Department of Nephrology, University Hospital of Southern Denmark, Esbjerg, Denmark
| | | | - Henrik Birn
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Claus Bistrup
- Department of Nephrology, Odense University Hospital, Odense, Denmark
- Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Boye Lagerbon Jensen
- Department of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
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12
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Ehret E, Stroh S, Auberson M, Ino F, Jäger Y, Maillard M, Szabo R, Bugge TH, Frateschi S, Hummler E. Kidney-Specific Membrane-Bound Serine Proteases CAP1/Prss8 and CAP3/St14 Affect ENaC Subunit Abundances but Not Its Activity. Cells 2023; 12:2342. [PMID: 37830556 PMCID: PMC10572026 DOI: 10.3390/cells12192342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/06/2023] [Accepted: 09/12/2023] [Indexed: 10/14/2023] Open
Abstract
The serine proteases CAP1/Prss8 and CAP3/St14 are identified as ENaC channel-activating proteases in vitro, highly suggesting that they are required for proteolytic activation of ENaC in vivo. The present study tested whether CAP3/St14 is relevant for renal proteolytic ENaC activation and affects ENaC-mediated Na+ absorption following Na+ deprivation conditions. CAP3/St14 knockout mice exhibit a significant decrease in CAP1/Prss8 protein expression with altered ENaC subunit and decreased pNCC protein abundances but overall maintain sodium balance. RNAscope-based analyses reveal co-expression of CAP3/St14 and CAP1/Prss8 with alpha ENaC in distal tubules of the cortex from wild-type mice. Double CAP1/Prss8; CAP3/St14-deficiency maintained Na+ and K+ balance on a Na+-deprived diet, restored ENaC subunit protein abundances but showed reduced NCC activity under Na+ deprivation. Overall, our data clearly show that CAP3/St14 is not required for direct proteolytic activation of ENaC but for its protein abundance. Our study reveals a complex regulation of ENaC by these serine proteases on the expression level rather than on its proteolytic activation.
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Affiliation(s)
- Elodie Ehret
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
- National Center of Competence in Research “Kidney.CH”, 1011 Lausanne, Switzerland
| | - Sévan Stroh
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
| | - Muriel Auberson
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
| | - Frédérique Ino
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
- Department of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Yannick Jäger
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Marc Maillard
- Service of Nephrology, Department of Medicine, Lausanne University Hospital (CHUV), 1005 Lausanne, Switzerland
| | - Roman Szabo
- National Institutes of Health/NIDCR, Bethesda, MD 20892, USA
| | - Thomas H. Bugge
- National Institutes of Health/NIDCR, Bethesda, MD 20892, USA
| | - Simona Frateschi
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
| | - Edith Hummler
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland; (E.E.)
- National Center of Competence in Research “Kidney.CH”, 1011 Lausanne, Switzerland
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13
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Guo L, Fu B, Liu Y, Hao N, Ji Y, Yang H. Diuretic resistance in patients with kidney disease: Challenges and opportunities. Biomed Pharmacother 2023; 157:114058. [PMID: 36473405 DOI: 10.1016/j.biopha.2022.114058] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/15/2022] [Accepted: 11/27/2022] [Indexed: 12/10/2022] Open
Abstract
Edema caused by kidney disease is called renal edema. Edema is a common symptom of many human kidney diseases. Patients with renal edema often need to take diuretics.However, After taking diuretics, patients with kidney diseases are prone to kidney congestion, decreased renal perfusion, decreased diuretics secreted by renal tubules, neuroendocrine system abnormalities, abnormal ion transporter transport, drug interaction, electrolyte disorder, and hypoproteinemia, which lead to ineffective or weakened diuretic use and increase readmission rate and mortality. The main causes and coping strategies of diuretic resistance in patients with kidney diseases were described in detail in this report. The common causes of DR included poor diet (electrolyte disturbance and hypoproteinemia due to patients' failure to limit diet according to correct sodium, chlorine, potassium, and protein level) and poor drug compliance (the patient did not take adequate doses of diuretics. true resistance occurs only if the patient takes adequate doses of diuretics, but they are not effective), changes in pharmacokinetics and pharmacodynamics, electrolyte disorders, changes in renal adaptation, functional nephron reduction, and decreased renal blood flow. Common treatment measures include increasing in the diuretic dose and/or frequency, sequential nephron blockade,using new diuretics, ultrafiltration treatment, etc. In clinical work, measures should be taken to prevent or delay the occurrence and development of DR in patients with kidney diseases according to the actual situation of patients and the mechanism of various causes. Currently, there are many studies on DR in patients with heart diseases. Although the phenomenon of DR in patients with kidney diseases is common, there is a relatively little overview of the mechanism and treatment strategy of DR in patients with kidney diseases. Therefore, this paper hopes to show the information on DR in patients with kidney diseases to clinicians and researchers and broaden the research direction and ideas to a certain extent.
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Affiliation(s)
- Luxuan Guo
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Baohui Fu
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Yang Liu
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Na Hao
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Yue Ji
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Hongtao Yang
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China; National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin 300193, China; Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China.
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14
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Novel Insights in the Physiopathology and Management of Obesity-Related Kidney Disease. Nutrients 2022; 14:nu14193937. [PMID: 36235590 PMCID: PMC9572176 DOI: 10.3390/nu14193937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/18/2022] [Accepted: 09/19/2022] [Indexed: 11/30/2022] Open
Abstract
Obesity is recognized as an independent risk factor for the development of kidney disease, which has led to the designation of obesity-related glomerulopathy (ORG). Common renal features observed in this condition include glomerular hypertrophy, glomerulosclerosis, haemodynamic changes and glomerular filtration barrier defects. Additionally, and although less studied, obesity-related kidney disease also involves alterations in renal tubules, including tubule hypertrophy, lipid deposition and tubulointerstitial fibrosis. Although not completely understood, the harmful effects of obesity on the kidney may be mediated by different mechanisms, with alterations in adipose tissue probably playing an important role. An increase in visceral adipose tissue has classically been associated with the development of kidney damage, however, recent studies point to adipose tissue surrounding the kidney, and specifically to the fat within the renal sinus, as potentially involved in the development of ORG. In addition, new strategies for the treatment of patients with obesity-related kidney disease are focusing on the management of obesity. In this regard, some non-invasive options, such as glucagon-like peptide-1 (GLP-1) receptor agonists or sodium–glucose cotransporter-2 (SGLT2) inhibitors, are being considered for application in the clinic, not only for patients with diabetic kidney disease but as a novel pharmacological strategy for patients with ORG. In addition, bariatric surgery stands as one of the most effective options, not only for weight loss but also for the improvement of kidney outcomes in obese patients with chronic kidney disease.
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15
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Maaliki D, Itani MM, Itani HA. Pathophysiology and genetics of salt-sensitive hypertension. Front Physiol 2022; 13:1001434. [PMID: 36176775 PMCID: PMC9513236 DOI: 10.3389/fphys.2022.1001434] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Most hypertensive cases are primary and heavily associated with modifiable risk factors like salt intake. Evidence suggests that even small reductions in salt consumption reduce blood pressure in all age groups. In that regard, the ACC/AHA described a distinct set of individuals who exhibit salt-sensitivity, regardless of their hypertensive status. Data has shown that salt-sensitivity is an independent risk factor for cardiovascular events and mortality. However, despite extensive research, the pathogenesis of salt-sensitive hypertension is still unclear and tremendously challenged by its multifactorial etiology, complicated genetic influences, and the unavailability of a diagnostic tool. So far, the important roles of the renin-angiotensin-aldosterone system, sympathetic nervous system, and immune system in the pathogenesis of salt-sensitive hypertension have been studied. In the first part of this review, we focus on how the systems mentioned above are aberrantly regulated in salt-sensitive hypertension. We follow this with an emphasis on genetic variants in those systems that are associated with and/or increase predisposition to salt-sensitivity in humans.
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Affiliation(s)
- Dina Maaliki
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Maha M. Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hana A. Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
- *Correspondence: Hana A. Itani,
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16
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Zhao C, Tang J, Li X, Yan Z, Zhao L, Lang W, Yuan C, Zhou C. Beneficial effects of procyanidin B2 on adriamycin-induced nephrotic syndrome mice: the multi-action mechanism for ameliorating glomerular permselectivity injury. Food Funct 2022; 13:8436-8464. [PMID: 35861207 DOI: 10.1039/d1fo03616e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite considerable advances in prevention, diagnosis, and therapy, nephrotic syndrome (NS) remains a significant cause of high morbidity and mortality globally. As a result, there is an urgent need to identify novel effective preventative and therapeutic agents for NS. NS is implicated in glomerular permselectivity injury, which can be attributed to oxidative distress, inflammation, lipid nephrotoxicity, podocyte apoptosis, autophagy dysfunction, and slit diaphragm (SLD) dysfunction. In addition to its well-documented antioxidant potency, procyanidin B2 (PB2) may exhibit pleiotropic effects by targeting various canonical signaling events, such as NF-κB, PPARs, PI3K/Akt, mTOR, and the caspase family. As a result, PB2 may be a promising therapeutic target against NS. To test this hypothesis, we established an Adriamycin (ADR)-induced NS mouse model to evaluate the pleiotropic renoprotective effects of PB2 on NS. Here, we demonstrated that PB2 improves podocyte injury via inhibition of NOX4/ROS and Hsp90/NF-κB to exhibit antioxidant and anti-inflammatory potency, respectively. We also show that PB2 indirectly activates the PI3K/Akt axis by regulating SLD protein levels, resulting in normalized podocyte apoptosis and autophagy function. Further, loss of albumin (ALB) induces lipid nephrotoxicity, which we found to be alleviated by PB2 via activation of PPARα/β-mediated lipid homeostasis and the cholesterol efflux axis. Interestingly, our results also suggested that PB2 reduces electrolyte abnormalities and edema. In addition, PB2 may contribute protective effects against trace element dys-homeostasis, which, through alleviating serum ALB loss, leads to a protective effect on glomerular permselectivity injury. Taken together, our results reveal that the identified mechanisms of PB2 on NS are multifactorial and involve inhibition of oxidative distress and inflammatory responses, as well as improvements in podocyte apoptosis and autophagy dysfunction, amelioration of lipid nephrotoxicity, and modulation of electrolyte abnormalities and edema. Thus, we provide a theoretical basis for the clinical application of PB2 against NS.
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Affiliation(s)
- Chuanping Zhao
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Institute of Life Science and Green Development, Hebei University, 180 WuSi Road, Lianchi District, Baoding, 071002, China.
| | - Jiamei Tang
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Institute of Life Science and Green Development, Hebei University, 180 WuSi Road, Lianchi District, Baoding, 071002, China.
| | - Xiaoya Li
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Institute of Life Science and Green Development, Hebei University, 180 WuSi Road, Lianchi District, Baoding, 071002, China.
| | - Zihan Yan
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Institute of Life Science and Green Development, Hebei University, 180 WuSi Road, Lianchi District, Baoding, 071002, China.
| | - Liangliang Zhao
- Department of Monitoring and Analysis, Baoding Environmental Monitoring Center of Hebei Province, 224 Dongfeng Road, Lianchi District, Baoding, 071000, China
| | - Wenbo Lang
- Department of Monitoring and Analysis, Baoding Environmental Monitoring Center of Hebei Province, 224 Dongfeng Road, Lianchi District, Baoding, 071000, China
| | - Chunmao Yuan
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China
| | - Chengyan Zhou
- Key Laboratory of Pharmaceutical Quality Control of Hebei Province, College of Pharmaceutical Sciences, Institute of Life Science and Green Development, Hebei University, 180 WuSi Road, Lianchi District, Baoding, 071002, China.
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17
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Yang M, Ni L, Wang Y, Xuan Z, Wu H, Zhan W, Wan X, Wang J, Xu F. Screening bioactive compounds from Danggui-shaoyao-san for treating sodium retention in nephrotic syndrome using bio-affinity ultrafiltration. JOURNAL OF ETHNOPHARMACOLOGY 2022; 292:115171. [PMID: 35259444 DOI: 10.1016/j.jep.2022.115171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 02/26/2022] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Danggui-shaoyao-san (DSS), a representative formula of Traditional Chinese Medicine (TCM) for promoting blood circulation and diuresis (Huo-Xue-Li-Shui) therapy, has been used to clinically nephrotic syndrome (NS) and relieve nephrotic edema. AIM OF THE STUDY To explore the effects and mechanisms of DSS in improving sodium retention and to identify the bioactive compounds from DSS. MATERIALS AND METHODS DSS prescriptions were disassembled into Yangxue-Huoxue (YXHX) and Jianpi-Lishui (JPLS). A nephrotic rat model was induced with puromycin aminonucleoside (PAN), and the effects on urinary sodium excretion, urinary plasmin(gen) content, and plasmin activity of DSS, YXHX, and JPLS extracts were assessed. The inhibitory effects on urokinase-type plasminogen activator (uPA) and plasmin activity of extracts were evaluated in vitro. Bio-affinity ultrafiltration and high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (BAU-UPLC-Q/TOF-MS) were used to rapidly screen and qualitatively analyze the uPA/plasmin affinity compounds from DSS extract. Additionally, uPA/plasmin inhibition assays and molecular docking were used to verify the activity and affinity mechanisms of the potential bioactive compounds. RESULTS In vivo, DSS, YXHX, and JPLS prevented sodium retention in nephrotic rats. DSS and YXHX treatment decreased urinary plasmin activity but did not alter urinary plasmin(ogen) concentration, and their extracts showed strong uPA and plasmin inhibitory activity in vitro. These results suggested that uPA and plasmin are direct targets of DSS and YXHX in intervening NS sodium retention. Using BAU-UPLC-Q/TOF-MS, gallic acids, methyl gallate, albiflorin, and 1,2,3,4,6-O-pentagalloylglucose (PGG) were screened as uPA or plasmin affinity compounds. Among them, PGG was found to be a uPA and plasmin dual inhibitor, with an IC50 of 6.861 μM against uPA and an IC50 of 149.0 μM against plasmin. The molecular docking results of PGG with uPA and plasmin were consistent with the verification results. CONCLUSION Intervening in sodium retention by inhibiting uPA-mediated plasmin generation and plasmin activity in the kidneys could be possible mechanisms for DSS, as indicated by the results in PAN-induced nephrotic rats. We conclude that PGG is a potential bioactive compound responsible for the effect of DSS on natriuresis.
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Affiliation(s)
- Mo Yang
- Scientific Research & Technology Center, Anhui University of Chinese Medicine, Hefei, 230038, PR China; Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, 230038, PR China.
| | - Lianghou Ni
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China.
| | - Yunlai Wang
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, PR China.
| | - Zihua Xuan
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China.
| | - Huan Wu
- Scientific Research & Technology Center, Anhui University of Chinese Medicine, Hefei, 230038, PR China; Key Laboratory of Xin'an Medicine, Ministry of Education, Anhui University of Chinese Medicine, Hefei, 230038, PR China; Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, PR China.
| | - Wenjing Zhan
- School of Pharmacy, Anhui Medical University, Hefei, 230032, PR China.
| | - Xinyu Wan
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, PR China.
| | - Jinghui Wang
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, 230012, PR China.
| | - Fan Xu
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Anhui Province Key Laboratory of Chinese Medicinal Formula, Hefei, 230012, PR China.
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Kidney-Specific CAP1/Prss8-Deficient Mice Maintain ENaC-Mediated Sodium Balance through an Aldosterone Independent Pathway. Int J Mol Sci 2022; 23:ijms23126745. [PMID: 35743186 PMCID: PMC9224322 DOI: 10.3390/ijms23126745] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/10/2022] [Accepted: 06/15/2022] [Indexed: 12/14/2022] Open
Abstract
The serine protease prostasin (CAP1/Prss8, channel-activating protease-1) is a confirmed in vitro and in vivo activator of the epithelial sodium channel ENaC. To test whether proteolytic activity or CAP1/Prss8 abundance itself are required for ENaC activation in the kidney, we studied animals either hetero- or homozygous mutant at serine 238 (S238A; Prss8cat/+ and Prss8cat/cat), and renal tubule-specific CAP1/Prss8 knockout (Prss8PaxLC1) mice. When exposed to varying Na+-containing diets, no changes in Na+ and K+ handling and only minor changes in the expression of Na+ and K+ transporting protein were found in both models. Similarly, the α- or γENaC subunit cleavage pattern did not differ from control mice. On standard and low Na+ diet, Prss8cat/+ and Prss8cat/cat mice exhibited standard plasma aldosterone levels and unchanged amiloride-sensitive rectal potential difference indicating adapted ENaC activity. Upon Na+ deprivation, mice lacking the renal CAP1/Prss8 expression (Prss8PaxLC1) exhibit significantly decreased plasma aldosterone and lower K+ levels but compensate by showing significantly higher plasma renin activity. Our data clearly demonstrated that the catalytic activity of CAP1/Prss8 is dispensable for proteolytic ENaC activation. CAP1/Prss8-deficiency uncoupled ENaC activation from its aldosterone dependence, but Na+ homeostasis is maintained through alternative pathways.
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19
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Xiao M, Bohnert BN, Grahammer F, Artunc F. Rodent models to study sodium retention in experimental nephrotic syndrome. Acta Physiol (Oxf) 2022; 235:e13844. [PMID: 35569011 DOI: 10.1111/apha.13844] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 05/02/2022] [Accepted: 05/10/2022] [Indexed: 12/12/2022]
Abstract
Sodium retention and edema are hallmarks of nephrotic syndrome (NS). Different experimental rodent models have been established for simulating NS, however, not all of them feature sodium retention which requires proteinuria to exceed a certain threshold. In rats, puromycin aminonucleoside nephrosis (PAN) is a classic NS model introduced in 1955 that was adopted as doxorubicin-induced nephropathy (DIN) in 129S1/SvImJ mice. In recent years, mice with inducible podocin deletion (Nphs2Δipod ) or podocyte apoptosis (POD-ATTAC) have been developed. In these models, sodium retention is thought to be caused by activation of the epithelial sodium channel (ENaC) in the distal nephron through aberrantly filtered serine proteases or proteasuria. Strikingly, rodent NS models follow an identical chronological time course after the development of proteinuria featuring sodium retention within days and spontaneous reversal thereafter. In DIN and Nphs2Δipod mice, inhibition of ENaC by amiloride or urinary serine protease activity by aprotinin prevents sodium retention, opening up new and promising therapeutic approaches that could be translated into the treatment of nephrotic patients. However, the essential serine protease(s) responsible for ENaC activation is (are) still unknown. With the use of nephrotic rodent models, there is the possibility that this (these) will be identified in the future. This review summarizes the various rodent models used to study experimental nephrotic syndrome and the insights gained from these models with regard to the pathophysiology of sodium retention.
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Affiliation(s)
- Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
| | - Bernhard N. Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
| | - Florian Grahammer
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
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20
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Anand D, Hummler E, Rickman OJ. ENaC activation by proteases. Acta Physiol (Oxf) 2022; 235:e13811. [PMID: 35276025 PMCID: PMC9540061 DOI: 10.1111/apha.13811] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/04/2022] [Accepted: 03/08/2022] [Indexed: 12/13/2022]
Abstract
Proteases are fundamental for a plethora of biological processes, including signalling and tissue remodelling, and dysregulated proteolytic activity can result in pathogenesis. In this review, we focus on a subclass of membrane‐bound and soluble proteases that are defined as channel‐activating proteases (CAPs), since they induce Na+ ion transport through an autocrine mechanism when co‐expressed with the highly amiloride‐sensitive epithelial sodium channel (ENaC) in Xenopus oocytes. These experiments first identified CAP1 (channel‐activating protease 1, prostasin) followed by CAP2 (channel‐activating protease 2, TMPRSS4) and CAP3 (channel‐activating protease 3, matriptase) as in vitro mediators of ENaC current. Since then, more serine‐, cysteine‐ and metalloproteases were confirmed as in vitro CAPs that potentially cleave and regulate ENaC, and thus this nomenclature was not further followed, but is accepted as functional term or alias. The precise mechanism of ENaC modulation by proteases has not been fully elucidated. Studies in organ‐specific protease knockout models revealed evidence for their role in increasing ENaC activity, although the proteases responsible for ENaC activation are yet to be identified. We summarize recent findings in animal models of these CAPs with respect to their implication in ENaC activation. We discuss the consequences of dysregulated CAPs underlying epithelial phenotypes in pathophysiological conditions, and the role of selected protease inhibitors. We believe that these proteases may present interesting therapeutic targets for diseases with aberrant sodium homoeostasis.
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Affiliation(s)
- Deepika Anand
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
| | - Edith Hummler
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
| | - Olivia J. Rickman
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
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21
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Sure F, Bertog M, Afonso S, Diakov A, Rinke R, Madej MG, Wittmann S, Gramberg T, Korbmacher C, Ilyaskin AV. Transmembrane serine protease 2 (TMPRSS2) proteolytically activates the epithelial sodium channel (ENaC) by cleaving the channel's γ-subunit. J Biol Chem 2022; 298:102004. [PMID: 35504352 PMCID: PMC9163703 DOI: 10.1016/j.jbc.2022.102004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/21/2022] [Accepted: 04/27/2022] [Indexed: 01/09/2023] Open
Abstract
The epithelial sodium channel (ENaC) is a heterotrimer consisting of α-, β-, and γ-subunits. Channel activation requires proteolytic release of inhibitory tracts from the extracellular domains of α-ENaC and γ-ENaC; however, the proteases involved in the removal of the γ-inhibitory tract remain unclear. In several epithelial tissues, ENaC is coexpressed with the transmembrane serine protease 2 (TMPRSS2). Here, we explored the effect of human TMPRSS2 on human αβγ-ENaC heterologously expressed in Xenopus laevis oocytes. We found that coexpression of TMPRSS2 stimulated ENaC-mediated whole-cell currents by approximately threefold, likely because of an increase in average channel open probability. Furthermore, TMPRSS2-dependent ENaC stimulation was not observed using a catalytically inactive TMPRSS2 mutant and was associated with fully cleaved γ-ENaC in the intracellular and cell surface protein fractions. This stimulatory effect of TMPRSS2 on ENaC was partially preserved when inhibiting its proteolytic activity at the cell surface using aprotinin but was abolished when the γ-inhibitory tract remained attached to its binding site following introduction of two cysteine residues (S155C–Q426C) to form a disulfide bridge. In addition, computer simulations and site-directed mutagenesis experiments indicated that TMPRSS2 can cleave γ-ENaC at sites both proximal and distal to the γ-inhibitory tract. This suggests a dual role of TMPRSS2 in the proteolytic release of the γ-inhibitory tract. Finally, we demonstrated that TMPRSS2 knockdown in cultured human airway epithelial cells (H441) reduced baseline proteolytic activation of endogenously expressed ENaC. Thus, we conclude that TMPRSS2 is likely to contribute to proteolytic ENaC activation in epithelial tissues in vivo.
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Affiliation(s)
- Florian Sure
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Marko Bertog
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Sara Afonso
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Alexei Diakov
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Ralf Rinke
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - M Gregor Madej
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
| | - Sabine Wittmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Thomas Gramberg
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Christoph Korbmacher
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany.
| | - Alexandr V Ilyaskin
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
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22
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Essigke D, Bohnert BN, Janessa A, Wörn M, Omage K, Kalbacher H, Birkenfeld AL, Bugge TH, Szabo R, Artunc F. Sodium retention in nephrotic syndrome is independent of the activation of the membrane-anchored serine protease prostasin (CAP1/PRSS8) and its enzymatic activity. Pflugers Arch 2022; 474:613-624. [PMID: 35312839 PMCID: PMC9117342 DOI: 10.1007/s00424-022-02682-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/25/2022] [Accepted: 03/04/2022] [Indexed: 12/11/2022]
Abstract
Experimental nephrotic syndrome leads to activation of the epithelial sodium channel (ENaC) by proteolysis and promotes renal sodium retention. The membrane-anchored serine protease prostasin (CAP1/PRSS8) is expressed in the distal nephron and participates in proteolytic ENaC regulation by serving as a scaffold for other serine proteases. However, it is unknown whether prostasin is also involved in ENaC-mediated sodium retention of experimental nephrotic syndrome. In this study, we used genetically modified knock-in mice with Prss8 mutations abolishing its proteolytic activity (Prss8-S238A) or prostasin activation (Prss8-R44Q) to investigate the development of sodium retention in doxorubicin-induced nephrotic syndrome. Healthy Prss8-S238A and Prss8-R44Q mice had normal ENaC activity as reflected by the natriuretic response to the ENaC blocker triamterene. After doxorubicin injection, all genotypes developed similar proteinuria. In all genotypes, urinary prostasin excretion increased while renal expression was not altered. In nephrotic mice of all genotypes, triamterene response was similarly increased, consistent with ENaC activation. As a consequence, urinary sodium excretion dropped in all genotypes and mice similarly gained body weight by + 25 ± 3% in Prss8-wt, + 20 ± 2% in Prss8-S238A and + 28 ± 3% in Prss8-R44Q mice (p = 0.16). In Western blots, expression of fully cleaved α- and γ-ENaC was similarly increased in nephrotic mice of all genotypes. In conclusion, proteolytic ENaC activation and sodium retention in experimental nephrotic syndrome are independent of the activation of prostasin and its enzymatic activity and are consistent with the action of aberrantly filtered serine proteases or proteasuria.
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Affiliation(s)
- Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Andrea Janessa
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | | | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Thomas H Bugge
- Proteases and Tissue Remodeling Section, NIDCR, National Institutes of Health, Bethesda, MD, USA
| | - Roman Szabo
- Proteases and Tissue Remodeling Section, NIDCR, National Institutes of Health, Bethesda, MD, USA
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany.
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany.
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany.
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23
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Pearce D, Manis AD, Nesterov V, Korbmacher C. Regulation of distal tubule sodium transport: mechanisms and roles in homeostasis and pathophysiology. Pflugers Arch 2022; 474:869-884. [PMID: 35895103 PMCID: PMC9338908 DOI: 10.1007/s00424-022-02732-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 02/03/2023]
Abstract
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
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Affiliation(s)
- David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Anna D. Manis
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
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24
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Wörner S, Bohnert BN, Wörn M, Xiao M, Janessa A, Birkenfeld AL, Amann K, Daniel C, Artunc F. Renal effects of the serine protease inhibitor aprotinin in healthy conscious mice. Acta Pharmacol Sin 2022; 43:111-120. [PMID: 33758357 PMCID: PMC8724274 DOI: 10.1038/s41401-021-00628-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/12/2021] [Indexed: 12/31/2022] Open
Abstract
Treatment with aprotinin, a broad-spectrum serine protease inhibitor with a molecular weight of 6512 Da, was associated with acute kidney injury, which was one of the reasons for withdrawal from the market in 2007. Inhibition of renal serine proteases regulating the epithelial sodium channel ENaC could be a possible mechanism. Herein, we studied the effect of aprotinin in wild-type 129S1/SvImJ mice on sodium handling, tubular function, and integrity under a control and low-salt diet. Mice were studied in metabolic cages, and aprotinin was delivered by subcutaneously implanted sustained release pellets (2 mg/day over 10 days). Mean urinary aprotinin concentration ranged between 642 ± 135 (day 2) and 127 ± 16 (day 8) µg/mL . Aprotinin caused impaired sodium preservation under a low-salt diet while stimulating excessive hyperaldosteronism and unexpectedly, proteolytic activation of ENaC. Aprotinin inhibited proximal tubular function leading to glucosuria and proteinuria. Plasma urea and cystatin C concentration increased significantly under aprotinin treatment. Kidney tissues from aprotinin-treated mice showed accumulation of intracellular aprotinin and expression of the kidney injury molecule 1 (KIM-1). In electron microscopy, electron-dense deposits were observed. There was no evidence for kidney injury in mice treated with a lower aprotinin dose (0.5 mg/day). In conclusion, high doses of aprotinin exert nephrotoxic effects by accumulation in the tubular system of healthy mice, leading to inhibition of proximal tubular function and counterregulatory stimulation of ENaC-mediated sodium transport.
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25
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Artunc F, Bohnert BN, Schneider JC, Staudner T, Sure F, Ilyaskin AV, Wörn M, Essigke D, Janessa A, Nielsen NV, Birkenfeld AL, Etscheid M, Haerteis S, Korbmacher C, Kanse SM. Proteolytic activation of the epithelial sodium channel (ENaC) by factor VII activating protease (FSAP) and its relevance for sodium retention in nephrotic mice. Pflugers Arch 2021; 474:217-229. [PMID: 34870751 PMCID: PMC8766372 DOI: 10.1007/s00424-021-02639-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/05/2021] [Accepted: 10/18/2021] [Indexed: 12/18/2022]
Abstract
Proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases is thought to contribute to renal sodium retention in nephrotic syndrome. However, the identity of the responsible proteases remains elusive. This study evaluated factor VII activating protease (FSAP) as a candidate in this context. We analyzed FSAP in the urine of patients with nephrotic syndrome and nephrotic mice and investigated its ability to activate human ENaC expressed in Xenopus laevis oocytes. Moreover, we studied sodium retention in FSAP-deficient mice (Habp2−/−) with experimental nephrotic syndrome induced by doxorubicin. In urine samples from nephrotic humans, high concentrations of FSAP were detected both as zymogen and in its active state. Recombinant serine protease domain of FSAP stimulated ENaC-mediated whole-cell currents in a time- and concentration-dependent manner. Mutating the putative prostasin cleavage site in γ-ENaC (γRKRK178AAAA) prevented channel stimulation by the serine protease domain of FSAP. In a mouse model for nephrotic syndrome, active FSAP was present in nephrotic urine of Habp2+/+ but not of Habp2−/− mice. However, Habp2−/− mice were not protected from sodium retention compared to nephrotic Habp2+/+ mice. Western blot analysis revealed that in nephrotic Habp2−/− mice, proteolytic cleavage of α- and γ-ENaC was similar to that in nephrotic Habp2+/+ animals. In conclusion, active FSAP is excreted in the urine of nephrotic patients and mice and activates ENaC in vitro involving the putative prostasin cleavage site of γ-ENaC. However, endogenous FSAP is not essential for sodium retention in nephrotic mice.
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Affiliation(s)
- Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany. .,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany. .,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany.
| | - Bernhard N Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Jonas C Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Tobias Staudner
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Wörn
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Daniel Essigke
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Nis V Nielsen
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | | | - Silke Haerteis
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.,Institute of Anatomy, University of Regensburg, Regensburg, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Sandip M Kanse
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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26
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van de Wouw J, Joles JA. Albumin is an interface between blood plasma and cell membrane, and not just a sponge. Clin Kidney J 2021; 15:624-634. [PMID: 35371452 PMCID: PMC8967674 DOI: 10.1093/ckj/sfab194] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 12/16/2022] Open
Abstract
Albumin is the most abundant protein in blood plasma and acts as a carrier for many circulating molecules. Hypoalbuminaemia, mostly caused by either renal or liver disease or malnutrition, can perturb vascular homeostasis and is involved in the development of multiple diseases. Here we review four functions of albumin and the consequences of hypoalbuminaemia on vascular homeostasis. (i) Albumin is the main determinant of plasma colloid osmotic pressure. Hypoalbuminaemia was therefore thought to be the main mechanism for oedema in nephrotic syndrome (NS), however, experimental studies showed that intrarenal mechanisms rather than hypoalbuminaemia determine formation and, in particular, maintenance of oedema. (ii) Albumin functions as an interface between lysophosphatidylcholine (LPC) and circulating factors (lipoproteins and erythrocytes) and the endothelium. Consequently, hypoalbuminaemia results in higher LPC levels in lipoproteins and erythrocyte membrane, thereby increasing atherosclerotic properties of low-density lipoprotein and blood viscosity, respectively. Furthermore, albumin dose-dependently restores LPC-induced inhibition of vasodilation. (iii) Hypoalbuminaemia impacts on vascular nitric oxide (NO) signalling by directly increasing NO production in endothelial cells, leading to reduced NO sensitivity of vascular smooth muscle cells. (iv) Lastly, albumin binds free fatty acids (FFAs). FFAs can induce vascular smooth muscle cell apoptosis, uncouple endothelial NO synthase and decrease endothelium-dependent vasodilation. Unbound FFAs can increase the formation of reactive oxygen species by mitochondrial uncoupling in multiple cell types and induce hypertriglyceridemia in NS. In conclusion, albumin acts as an interface in the circulation and hypoalbuminaemia impairs multiple aspects of vascular function that may underlie the association of hypoalbuminaemia with adverse outcomes. However, hypoalbuminaemia is not a key to oedema in NS. These insights have therapeutic implications.
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Affiliation(s)
| | - Jaap A Joles
- Department of Nephrology and Hypertension, University Medical Center, Utrecht, the Netherlands
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27
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Bohnert BN, Essigke D, Janessa A, Schneider JC, Wörn M, Kalo MZ, Xiao M, Kong L, Omage K, Hennenlotter J, Amend B, Birkenfeld AL, Artunc F. Experimental nephrotic syndrome leads to proteolytic activation of the epithelial Na + channel in the mouse kidney. Am J Physiol Renal Physiol 2021; 321:F480-F493. [PMID: 34423678 DOI: 10.1152/ajprenal.00199.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteolytic activation of the renal epithelial Na+ channel (ENaC) involves cleavage events in its α- and γ-subunits and is thought to mediate Na+ retention in nephrotic syndrome (NS). However, the detection of proteolytically processed ENaC in kidney tissue from nephrotic mice has been elusive so far. We used a refined Western blot technique to reliably discriminate full-length α-ENaC and γ-ENaC and their cleavage products after proteolysis at their proximal and distal cleavage sites (designated from the NH2-terminus), respectively. Proteolytic ENaC activation was investigated in kidneys from mice with experimental NS induced by doxorubicin or inducible podocin deficiency with or without treatment with the serine protease inhibitor aprotinin. Nephrotic mice developed Na+ retention and increased expression of fragments of α-ENaC and γ-ENaC cleaved at both the proximal cleavage site and, more prominently, the distal cleavage site, respectively. Treatment with aprotinin but not with the mineralocorticoid receptor antagonist canrenoate prevented Na+ retention and upregulation of the cleavage products in nephrotic mice. Increased expression of cleavage products of α-ENaC and γ-ENaC was similarly found in healthy mice treated with a low-salt diet, sensitive to mineralocorticoid receptor blockade. In human nephrectomy specimens, γ-ENaC was found in the full-length form and predominantly cleaved at its distal cleavage site. In conclusion, murine experimental NS leads to aprotinin-sensitive proteolytic activation of ENaC at both proximal and, more prominently, distal cleavage sites of its α- and γ-subunit, most likely by urinary serine protease activity or proteasuria.NEW & NOTEWORTHY This study demonstrates that murine experimental nephrotic syndrome leads to aprotinin-sensitive proteolytic activation of the epithelial Na+ channel at both the α- and γ-subunit, most likely by urinary serine protease activity or proteasuria.
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Affiliation(s)
- Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
| | - Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Andrea Janessa
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jonas C Schneider
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - M Zaher Kalo
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lingsi Kong
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jörg Hennenlotter
- Department of Urology, University Hospital Tübingen, Tübingen, Germany
| | - Bastian Amend
- Department of Urology, University Hospital Tübingen, Tübingen, Germany
| | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
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28
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Bissinger R, Nemkov T, D'Alessandro A, Grau M, Dietz T, Bohnert BN, Essigke D, Wörn M, Schaefer L, Xiao M, Beirne JM, Kalo MZ, Schork A, Bakchoul T, Omage K, Kong L, Gonzalez-Menendez I, Quintanilla-Martinez L, Fehrenbacher B, Schaller M, Dhariwal A, Birkenfeld AL, Grahammer F, Qadri SM, Artunc F. Proteinuric chronic kidney disease is associated with altered red blood cell lifespan, deformability and metabolism. Kidney Int 2021; 100:1227-1239. [PMID: 34537228 DOI: 10.1016/j.kint.2021.08.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 08/05/2021] [Accepted: 08/13/2021] [Indexed: 12/14/2022]
Abstract
Anemia is a common complication of chronic kidney disease, affecting the quality of life of patients. Among various factors, such as iron and erythropoietin deficiency, reduced red blood cell (RBC) lifespan has been implicated in the pathogenesis of anemia. However, mechanistic data on in vivo RBC dysfunction in kidney disease are lacking. Herein, we describe the development of chronic kidney disease-associated anemia in mice with proteinuric kidney disease resulting from either administration of doxorubicin or an inducible podocin deficiency. In both experimental models, anemia manifested at day 10 and progressed at day 30 despite increased circulating erythropoietin levels and erythropoiesis in the bone marrow and spleen. Circulating RBCs in both mouse models displayed altered morphology and diminished osmotic-sensitive deformability together with increased phosphatidylserine externalization on the outer plasma membrane, a hallmark of RBC death. Fluorescence-labelling of RBCs at day 20 of mice with doxorubicin-induced kidney disease revealed premature clearance from the circulation. Metabolomic analyses of RBCs from both mouse models demonstrated temporal changes in redox recycling pathways and Lands' cycle, a membrane lipid remodeling process. Anemic patients with proteinuric kidney disease had an increased proportion of circulating phosphatidylserine-positive RBCs. Thus, our observations suggest that reduced RBC lifespan, mediated by altered RBC metabolism, reduced RBC deformability, and enhanced cell death contribute to the development of anemia in proteinuric kidney disease.
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Affiliation(s)
- Rosi Bissinger
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA; Division of Hematology, University of Colorado Denver, Aurora, Colorado, USA
| | - Marijke Grau
- Institute of Molecular and Cellular Sports Medicine, German Sport University of Cologne, Köln, Germany
| | - Thomas Dietz
- Institute of Molecular and Cellular Sports Medicine, German Sport University of Cologne, Köln, Germany
| | - Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lina Schaefer
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jonathan M Beirne
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - M Zaher Kalo
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Anja Schork
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Tamam Bakchoul
- Center for Clinical Transfusion Medicine, University Hospital of Tübingen, Tübingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lingsi Kong
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | | | | | - Birgit Fehrenbacher
- Department of Dermatology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Martin Schaller
- Department of Dermatology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Achal Dhariwal
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Florian Grahammer
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Syed M Qadri
- Faculty of Health Sciences, Ontario Tech University, Oshawa, Ontario, Canada
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany.
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29
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Bohnert BN, Gonzalez-Menendez I, Dörffel T, Schneider JC, Xiao M, Janessa A, Kalo MZ, Fehrenbacher B, Schaller M, Casadei N, Amann K, Daniel C, Birkenfeld AL, Grahammer F, Izem L, Plow EF, Quintanilla-Martinez L, Artunc F. Essential role of DNA-PKcs and plasminogen for the development of doxorubicin-induced glomerular injury in mice. Dis Model Mech 2021; 14:271906. [PMID: 34423816 PMCID: PMC8461821 DOI: 10.1242/dmm.049038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/02/2021] [Indexed: 12/11/2022] Open
Abstract
Susceptibility to doxorubicin-induced nephropathy (DIN), a toxic model for the induction of proteinuria in mice, is related to the single-nucleotide polymorphism (SNP) C6418T of the Prkdc gene encoding for the DNA-repair enzyme DNA-PKcs. In addition, plasminogen (Plg) has been reported to play a role in glomerular damage. Here, we investigated the interdependence of both factors for the development of DIN. Genotyping confirmed the SNP of the Prkdc gene in C57BL/6 (PrkdcC6418/C6418) and 129S1/SvImJ (PrkdcT6418/T6418) mice. Intercross of heterozygous 129SB6F1 mice led to 129SB6F2 hybrids with Mendelian inheritance of the SNP. After doxorubicin injection, only homozygous F2 mice with PrkdcT6418/T6418 developed proteinuria. Genetic deficiency of Plg (Plg−/−) in otherwise susceptible 129S1/SvImJ mice led to resistance to DIN. Immunohistochemistry revealed glomerular binding of Plg in Plg+/+ mice after doxorubicin injection involving histone H2B as Plg receptor. In doxorubicin-resistant C57BL/6 mice, Plg binding was absent. In conclusion, susceptibility to DIN in 129S1/SvImJ mice is determined by a hierarchical two-hit process requiring the C6418T SNP in the Prkdc gene and subsequent glomerular binding of Plg. This article has an associated First Person interview with the first author of the paper. Summary: Susceptibility to doxorubicin-induced nephropathy in 129S1/SvImJ mice is determined by a hierarchical two-hit process requiring the C6418T single-nucleotide polymorphism in the Prkdc gene and subsequent glomerular binding of plasminogen.
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Affiliation(s)
- Bernhard N Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
| | - Irene Gonzalez-Menendez
- Institute of Pathology and Neuropathology, Department of Pathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Thomas Dörffel
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Jonas C Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Mengyun Xiao
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - M Zaher Kalo
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Birgit Fehrenbacher
- Department of Dermatology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Martin Schaller
- Department of Dermatology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Nicolas Casadei
- Institute of Genetics, University Hospital Tübingen, 72076 Tübingen, Germany.,NGS Competence Center Tübingen, University Tübingen, Tübingen 72076, Germany
| | - Kerstin Amann
- Institute of Pathology, Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Christoph Daniel
- Institute of Pathology, Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
| | - Florian Grahammer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lahoucine Izem
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Edward F Plow
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Leticia Quintanilla-Martinez
- Institute of Pathology and Neuropathology, Department of Pathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
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30
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Elijovich F, Kleyman TR, Laffer CL, Kirabo A. Immune Mechanisms of Dietary Salt-Induced Hypertension and Kidney Disease: Harry Goldblatt Award for Early Career Investigators 2020. Hypertension 2021; 78:252-260. [PMID: 34232678 DOI: 10.1161/hypertensionaha.121.16495] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Salt sensitivity of blood pressure is an independent risk factor for cardiovascular mortality not only in hypertensive but also in normotensive adults. The diagnosis of salt sensitivity of blood pressure is not feasible in the clinic due to lack of a simple diagnostic test, making it difficult to investigate therapeutic strategies. Most research efforts to understand the mechanisms of salt sensitivity of blood pressure have focused on renal regulation of sodium. However, salt retention or plasma volume expansion is not different between salt-sensitive and salt-resistant individuals. In addition, over 70% of extracellular fluid is interstitial and, therefore, not directly controlled by renal salt and water excretion. We discuss in this review how the seminal work by Harry Goldblatt paved the way for our attempts at understanding the mechanisms that underlie immune activation by salt in hypertension. We describe our findings that sodium, entering antigen-presenting cells via an epithelial sodium channel, triggers a PKC (protein kinase C)- and SGK1 (serum/glucocorticoid kinase 1)-stimulated activation of nicotinamide adenine dinucleotide phosphate oxidase, which, in turn, enhances lipid oxidation with generation of highly reactive isolevuglandins. Isolevuglandins adduct to proteins, with the potential to generate degraded peptide neoantigens. Activated antigen-presenting cells increase production of the TH17 polarizing cytokines, IL (interleukin)-6, IL-1β, and IL-23, which leads to differentiation and proliferation of IL-17A producing T cells. Our laboratory and others have shown that this cytokine contributes to hypertension. We also discuss where this sodium activation of antigen-presenting cells may occur in vivo and describe the multiple experiments, with pharmacological antagonists and knockout mice that we used to unravel this sequence of events in rodents. Finally, we describe experiments in mononuclear cells obtained from normotensive or hypertensive volunteers, which confirm that analogous processes of salt-induced immunity take place in humans.
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Affiliation(s)
- Fernando Elijovich
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (F.E., C.L.L., A.K.)
| | - Thomas R Kleyman
- Departments of Medicine, Cell Biology, Pharmacology, and Chemical Biology, University of Pittsburgh, PA (T.R.K.)
| | - Cheryl L Laffer
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (F.E., C.L.L., A.K.)
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN (F.E., C.L.L., A.K.)
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31
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Abstract
The Epithelial Na+ Channel, ENaC, comprised of 3 subunits (αβγ, or sometimes δβγENaC), plays a critical role in regulating salt and fluid homeostasis in the body. It regulates fluid reabsorption into the blood stream from the kidney to control blood volume and pressure, fluid absorption in the lung to control alveolar fluid clearance at birth and maintenance of normal airway surface liquid throughout life, and fluid absorption in the distal colon and other epithelial tissues. Moreover, recent studies have also revealed a role for sodium movement via ENaC in nonepithelial cells/tissues, such as endothelial cells in blood vessels and neurons. Over the past 25 years, major advances have been made in our understanding of ENaC structure, function, regulation, and role in human disease. These include the recently solved three-dimensional structure of ENaC, ENaC function in various tissues, and mutations in ENaC that cause a hereditary form of hypertension (Liddle syndrome), salt-wasting hypotension (PHA1), or polymorphism in ENaC that contributes to other diseases (such as cystic fibrosis). Moreover, great strides have been made in deciphering the regulation of ENaC by hormones (e.g., the mineralocorticoid aldosterone, glucocorticoids, vasopressin), ions (e.g., Na+ ), proteins (e.g., the ubiquitin-protein ligase NEDD4-2, the kinases SGK1, AKT, AMPK, WNKs & mTORC2, and proteases), and posttranslational modifications [e.g., (de)ubiquitylation, glycosylation, phosphorylation, acetylation, palmitoylation]. Characterization of ENaC structure, function, regulation, and role in human disease, including using animal models, are described in this article, with a special emphasis on recent advances in the field. © 2021 American Physiological Society. Compr Physiol 11:1-29, 2021.
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Affiliation(s)
- Daniela Rotin
- The Hospital for Sick Children, and The University of Toronto, Toronto, Canada
| | - Olivier Staub
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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32
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Alhamoud I, Legan SK, Gattineni J, Baum M. Sex differences in prenatal programming of hypertension by dexamethasone. Exp Biol Med (Maywood) 2021; 246:1554-1562. [PMID: 33794700 DOI: 10.1177/15353702211003294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Prenatal dexamethasone has been shown to increase blood pressure in male offspring but the mechanism for the increase in blood pressure is unclear. The present study examined if prenatal programming by maternal injection of dexamethasone on days 15 and 16 of gestation affected the blood pressure comparably in female and male offspring. Our hypothesis was that males would be affected by prenatal dexamethasone to a greater extent than females and that either an increase in renal tubular transporter abundance or an increase in renin or aldosterone system would be associated with hypertension with prenatal programming. Prenatal dexamethasone increased blood pressure at two months and six months of age and resulted in proteinuria and albuminuria at six months in male but not female rat offspring. There was no effect of prenatal dexamethasone on blood pressure and proteinuria at one month in male and in female offspring. While prenatal dexamethasone increased male renal thick ascending limb sodium potassium two chloride cotransporter protein abundance at two months, prenatal dexamethasone on days 15 and 16 of gestation did not affect transporter abundance in males at other ages, nor did it affect proximal tubule sodium/hydrogen exchanger or distal convoluted tubule sodium chloride cotransporter protein abundance at any age. There was no difference in systemic renin or aldosterone in the prenatal dexamethasone group compared to same sex controls. In conclusion, male but not female offspring have an increase in blood pressure and urinary protein excretion with prenatal dexamethasone. The increase in blood pressure with prenatal programming was not associated with a consistent increase in renal tubular transporter protein abundance, nor plasma renin activity and serum aldosterone.
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Affiliation(s)
- Issa Alhamoud
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9063, USA
| | - Susan K Legan
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9063, USA
| | - Jyothsna Gattineni
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9063, USA
| | - Michel Baum
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9063, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9063, USA
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33
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Sandino J, Luzardo L, Morales E, Praga M. Which Patients with Obesity Are at Risk for Renal Disease? Nephron Clin Pract 2021; 145:595-603. [PMID: 33677441 DOI: 10.1159/000513868] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 12/16/2020] [Indexed: 11/19/2022] Open
Abstract
Obesity-related glomerulopathy (ORG) is an increasingly recognized cause of end-stage kidney disease. The most common clinical presentation is a slowly increasing nonnephrotic proteinuria that is followed by a progressive decline of kidney function. Key histological findings are glomerulomegaly and lesions of focal and segmental glomerulosclerosis. A central pathogenic mechanism is the increased sodium reabsorption by proximal tubules that typically accompanies obesity. This causes a decrease in the offer of sodium to the macula densa in the distal nephron, which results in a vasodilation of afferent glomerular arterioles and glomerular hyperfiltration. From a clinical point of view, it is essential to differentiate focal segmental glomerulosclerosis secondary to obesity from primary glomerular processes, which requires a careful differential diagnosis. Diet-induced weight loss, bariatric surgery, and renin-angiotensin blockers are the fundamental therapeutic measures in ORG. The recently developed sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide 1 agonist represent a significant advance in renal protection and will probably improve clinical kidney outcomes in ORG.
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Affiliation(s)
- Justo Sandino
- Department of Nephrology, University Hospital "12 de Octubre", Madrid, Spain
| | - Leonella Luzardo
- Nephrology Center, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay
| | - Enrique Morales
- Department of Nephrology, University Hospital "12 de Octubre", Madrid, Spain, .,Research Institute of University Hospital "12 de Octubre" (imas12), Madrid, Spain, .,Department of Medicine, Complutense University of Madrid, Madrid, Spain,
| | - Manuel Praga
- Department of Nephrology, University Hospital "12 de Octubre", Madrid, Spain.,Research Institute of University Hospital "12 de Octubre" (imas12), Madrid, Spain.,Department of Medicine, Complutense University of Madrid, Madrid, Spain
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34
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Xiao M, Bohnert BN, Aypek H, Kretz O, Grahammer F, Aukschun U, Wörn M, Janessa A, Essigke D, Daniel C, Amann K, Huber TB, Plow EF, Birkenfeld AL, Artunc F. Plasminogen deficiency does not prevent sodium retention in a genetic mouse model of experimental nephrotic syndrome. Acta Physiol (Oxf) 2021; 231:e13512. [PMID: 32455507 DOI: 10.1111/apha.13512] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/19/2022]
Abstract
AIM Sodium retention is the hallmark of nephrotic syndrome (NS) and mediated by the proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases. Plasmin is highly abundant in nephrotic urine and has been proposed to be the principal serine protease responsible for ENaC activation in NS. However, a proof of the essential role of plasmin in experimental NS is lacking. METHODS We used a genetic mouse model of NS based on an inducible podocin knockout (Bl6-Nphs2tm3.1Antc *Tg(Nphs1-rtTA*3G)8Jhm *Tg(tetO-cre)1Jaw or nphs2Δipod ). These mice were crossed with plasminogen deficient mice (Bl6-Plgtm1Jld or plg-/- ) to generate double knockout mice (nphs2Δipod *plg-/- ). NS was induced after oral doxycycline treatment for 14 days and mice were followed for subsequent 14 days. RESULTS Uninduced nphs2Δipod *plg-/- mice had normal kidney function and sodium handling. After induction, proteinuria increased similarly in both nphs2Δipod *plg+/+ and nphs2Δipod *plg-/- mice. Western blot revealed the urinary excretion of plasminogen and plasmin in nphs2Δipod *plg+/+ mice which were absent in nphs2Δipod *plg-/- mice. After the onset of proteinuria, amiloride-sensitive natriuresis was increased compared to the uninduced state in both genotypes. Subsequently, urinary sodium excretion dropped in both genotypes leading to an increase in body weight and development of ascites. Treatment with the serine protease inhibitor aprotinin prevented sodium retention in both genotypes. CONCLUSIONS This study shows that mice lacking urinary plasminogen are not protected from ENaC-mediated sodium retention in experimental NS. This points to an essential role of other urinary serine proteases in the absence of plasminogen.
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Affiliation(s)
- Mengyun Xiao
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
| | - Bernhard N. Bohnert
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
| | - Hande Aypek
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Oliver Kretz
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Florian Grahammer
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Ute Aukschun
- IV. Department of Medicine, Faculty and University Medical Center Freiburg Freiburg Germany
| | - Matthias Wörn
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
| | - Andrea Janessa
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
| | - Daniel Essigke
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
| | - Christoph Daniel
- Institute of Nephropathology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Kerstin Amann
- Institute of Nephropathology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Tobias B. Huber
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Edward F. Plow
- Lerner Research InstituteCleveland Clinic Cleveland OH USA
| | - Andreas L. Birkenfeld
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
| | - Ferruh Artunc
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
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35
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Artunc F. Kidney-derived PCSK9-a new driver of hyperlipidemia in nephrotic syndrome? Kidney Int 2020; 98:1393-1395. [PMID: 33276863 DOI: 10.1016/j.kint.2020.07.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 12/27/2022]
Abstract
Increased plasma concentrations of proprotein convertase subtilisin/kexin type 9 or PCSK9, which reduces hepatic uptake of low-density lipoprotein by downregulation of the low-density lipoprotein receptor, have been reported in nephrotic patients and might contribute to hyperlipidemia in nephrotic syndrome. The results of the study by Molina-Jijon et al. found that renal PCSK9 expression was upregulated in the collecting duct of nephrotic patients and animals, suggesting that the kidney might be a major source for plasma PCSK9 in nephrotic syndrome.
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Affiliation(s)
- Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany.
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Schork A, Bohnert BN, Heyne N, Birkenfeld AL, Artunc F. Overhydration Measured by Bioimpedance Spectroscopy and Urinary Serine Protease Activity Are Risk Factors for Progression of Chronic Kidney Disease. Kidney Blood Press Res 2020; 45:955-968. [PMID: 33264776 DOI: 10.1159/000510649] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 08/04/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Overhydration (OH) is common in chronic kidney disease (CKD) and might be related to the excretion of urinary serine proteases. Progression of CKD is associated with proteinuria; however, the interrelations of urinary serine proteases, OH, and progression of CKD remain unclear. METHODS In n = 179 patients with stable nondialysis-dependent CKD of all stages, OH was measured using bioimpedance spectroscopy (Body Composition Monitor; Fresenius), and urinary serine protease activity was determined using the peptide substrate S-2302. After a median follow-up of 5.9 (IQR: 3.9-6.5) years, progression to end-stage renal disease (ESRD) was analyzed retrospectively. RESULTS OH correlated with baseline MDRD-eGFR, urinary albumin creatinine ratio (ACR), and urinary aprotinin-sensitive serine protease activity. Progression to ESRD occurred in n = 33 patients (19%) and correlated with OH and urinary serine protease activity as well as MDRD-eGFR and ACR. Patients were divided into 2 groups determined by cutoff values from receiver operating characteristics for MDRD-eGFR (32 mL/min/1.73 m2), ACR (43 mg/g creatinine), urinary serine protease activity (0.9 RU/g creatinine), and OH (1 L/1.73 m2). Across these cutoff values, Kaplan-Meier curves for renal survival showed significant separations of the groups. In Cox regression adjusted for MDRD-eGFR, ACR, P-NT-pro-BNP, systolic blood pressure, and diabetes mellitus, patients with OH >1 L/1.73 m2 had a 3.32 (95% CI: 1.26-8.76)-fold higher risk for progression to ESRD. CONCLUSIONS Our results corroborate that OH detected by bioimpedance spectroscopy in CKD patients is an independent risk factor for progression to ESRD in addition to GFR and albuminuria. Urinary serine protease activity is associated with OH and progression of CKD and provides a possible underlying mechanism.
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Affiliation(s)
- Anja Schork
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Tübingen, Germany, .,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany, .,German Center for Diabetes Research (DZD), Tübingen, Germany,
| | - Bernhard N Bohnert
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Nils Heyne
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Andreas L Birkenfeld
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Ferruh Artunc
- Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
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Bovée DM, Cuevas CA, Zietse R, Danser AHJ, Mirabito Colafella KM, Hoorn EJ. Salt-sensitive hypertension in chronic kidney disease: distal tubular mechanisms. Am J Physiol Renal Physiol 2020; 319:F729-F745. [DOI: 10.1152/ajprenal.00407.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chronic kidney disease (CKD) causes salt-sensitive hypertension that is often resistant to treatment and contributes to the progression of kidney injury and cardiovascular disease. A better understanding of the mechanisms contributing to salt-sensitive hypertension in CKD is essential to improve these outcomes. This review critically explores these mechanisms by focusing on how CKD affects distal nephron Na+ reabsorption. CKD causes glomerulotubular imbalance with reduced proximal Na+ reabsorption and increased distal Na+ delivery and reabsorption. Aldosterone secretion further contributes to distal Na+ reabsorption in CKD and is not only mediated by renin and K+ but also by metabolic acidosis, endothelin-1, and vasopressin. CKD also activates the intrarenal renin-angiotensin system, generating intratubular angiotensin II to promote distal Na+ reabsorption. High dietary Na+ intake in CKD contributes to Na+ retention by aldosterone-independent activation of the mineralocorticoid receptor mediated through Rac1. High dietary Na+ also produces an inflammatory response mediated by T helper 17 cells and cytokines increasing distal Na+ transport. CKD is often accompanied by proteinuria, which contains plasmin capable of activating the epithelial Na+ channel. Thus, CKD causes both local and systemic changes that together promote distal nephron Na+ reabsorption and salt-sensitive hypertension. Future studies should address remaining knowledge gaps, including the relative contribution of each mechanism, the influence of sex, differences between stages and etiologies of CKD, and the clinical relevance of experimentally identified mechanisms. Several pathways offer opportunities for intervention, including with dietary Na+ reduction, distal diuretics, renin-angiotensin system inhibitors, mineralocorticoid receptor antagonists, and K+ or H+ binders.
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Affiliation(s)
- Dominique M. Bovée
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
- Division of Vascular Medicine, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Catharina A. Cuevas
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Robert Zietse
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - A. H. Jan Danser
- Division of Vascular Medicine, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Katrina M. Mirabito Colafella
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Ewout J. Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
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38
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Wang Y, Fan S, Yang M, Shi G, Hu S, Yin D, Zhang Y, Xu F. Evaluation of the mechanism of Danggui-Shaoyao-San in regulating the metabolome of nephrotic syndrome based on urinary metabonomics and bioinformatics approaches. JOURNAL OF ETHNOPHARMACOLOGY 2020; 261:113020. [PMID: 32592886 DOI: 10.1016/j.jep.2020.113020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 05/22/2020] [Accepted: 05/24/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Danggui-Shaoyao-San (DSS), a well-known classic Traditional Chinese medicine (TCM) formula for enhancing Qi (vital energy and spirit), invigorating blood circulation and promoting diuresis, has been widely used in the treatment of nephrotic syndrome (NS). Previously, we have reported some protective effects of DSS against NS, but the in-depth mechanisms remain unclear. AIM OF THE STUDY In this study, an ultra performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-Q/TOF-MS)-based urinary metabonomics coupled with bioinformatics method was employed to evaluate the mechanisms of DSS in treating NS from the perspective of metabolism. MATERIALS AND METHODS The rat models of NS were established using adriamycin injection. The regulative effects of DSS on NS in rats were first assessed by non-targeted metabonomics, which was based on UPLC-Q/TOF-MS. A series of target prediction models were used to predict the target of components identified in DSS and potential metabolites in NS, combined with the experimental results of metabonomics, to construct the biological network. RESULTS A total of 16 potential metabolites were screened in NS, of which 13 were significantly regulated by DSS. Metabolic pathway analysis showed that the therapeutic effect of DSS on NS was mainly involved in regulating the amino acid metabolism and energy metabolism. The component-target-metabolites-pathway network revealed 29 targets associated with metabolites that were linked to 27 components of DSS. Bioinformatics analysis showed that the potential targets have various molecular functions (especially serine-type endopeptidase inhibitor activity) and biological process (such as positive regulation of peptidyl-tyrosine phosphorylation or autophosphorylation). CONCLUSIONS The regulation of disrupted metabolic pathways and the relative targets may be the mechanism for DSS in the treatment of NS. Notably, metabonomics coupled with bioinformatics would be useful to explore the mechanism of DSS against NS and provide better insights on DSS for clinical use.
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Affiliation(s)
- Yunlai Wang
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
| | - Shengnan Fan
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
| | - Mo Yang
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
| | - Gaoxiang Shi
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
| | - Siyao Hu
- The Chinese University of Hong Kong (Shenzhen), Shenzhen, 518172, PR China.
| | - Dengke Yin
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
| | - Yazhong Zhang
- Anhui Institute for Food and Drug Control, Hefei, 230051, PR China.
| | - Fan Xu
- School of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, PR China; Key Laboratory of Chinese Medicine Formula of Anhui Province, Hefei, 230012, PR China.
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39
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Proteasuria in nephrotic syndrome-quantification and proteomic profiling. J Proteomics 2020; 230:103981. [PMID: 32927112 DOI: 10.1016/j.jprot.2020.103981] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 08/24/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023]
Abstract
Nephrotic syndrome is characterized by urinary excretion of plasma proteases or proteasuria. There is a lack of data on the quantity, activity status and identity of these aberrantly filtered proteases. We established a fluorescence-based substrate assay to quantify protease activity in urine samples from healthy and nephrotic humans and mice. Protease class activity was determined after addition of specific inhibitors. Individual proteases were identified by tandem mass spectrometry (MS/MS). In spot urine samples from 10 patients with acute nephrotic syndrome of various etiology, urinary protease activity was significantly increased compared to that of healthy persons (753 ± 178 vs. 244 ± 65 relative units, p < 0.05). The corresponding proteases were highly sensitive to inhibition by the serine protease inhibitors AEBSF (reduction by 85 ± 6% and 72 ± 8%, respectively) and aprotinin (83 ± 9% vs. 25 ± 6%, p < 0.05). MS/MS of all urinary proteins or after AEBSF purification showed that most of them were active serine proteases from the coagulation and complement cascade. These findings were recapitulated in mice, pointing to a similar pathophysiology. In conclusion, nephrotic syndrome leads to increased urinary excretion of active plasma proteases which can be termed proteasuria. Serine proteases account for the vast majority of urinary protease activity in health and nephrotic syndrome. SIGNIFICANCE STATEMENT: In this study, we found that nephrotic urine samples of humans and mice have a significantly increased protease activity compared to healthy urine samples, using a universal pentapeptide substrate library. This was driven by increased excretion of aprotinin-sensitive serine proteases. With tandem mass spectrometry, we provide a comprehensive and systematic overview of all urinary proteases or the "urine proteasome". We identified renally expressed proteases in health and addition of proteases from the coagulation and complement cascade in the nephrotic state. These results set the basis to study the role of urinary proteases at both health and nephrotic syndrome to find diagnostic markers of renal disease as well as possible therapeutic targets.
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40
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Abstract
Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.
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Current Perspectives in Management of Edema in Nephrotic Syndrome. Indian J Pediatr 2020; 87:633-640. [PMID: 32232733 DOI: 10.1007/s12098-020-03252-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 02/19/2020] [Indexed: 12/25/2022]
Abstract
Idiopathic nephrotic syndrome is the most common glomerulopathy in childhood characterised by heavy proteinuria, hypoalbuminemia and edema. Most of the patients have mild and transient edema but those with difficult to treat nephrotic syndrome can develop severe edema which may have serious consequences such as immobility, cellulitis and peritonitis. Understanding of the pathophysiology of edema is still evolving with recent research elucidating newer mechanism of sodium retention through plasmin mediated epithelial sodium channel activation in collecting duct. Patients with mild edema do not require specific diuretic therapy as it improves with steroid induced diuresis. In this review, the authors describe the current perspective in management of moderate to severe edema in childhood nephrotic syndrome including various parameters to assess intravascular volume status which is important for planning overall treatment strategy. Then they briefly discuss about various classes of diuretics, aquaretics and evidence based use of furosemide albumin combination therapy for treatment of edema. Management strategy for a small proportion of patients, who are unresponsive to furosemide therapy, includes diuretic synergism, intravenous furosemide albumin combination therapy and continuous intravenous furosemide infusion.
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Sera From Patients With Minimal Change Disease Increase Endothelial Permeability to Sodium. Kidney Int Rep 2020; 5:1071-1075. [PMID: 32647766 PMCID: PMC7335967 DOI: 10.1016/j.ekir.2020.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 04/04/2020] [Accepted: 04/10/2020] [Indexed: 11/01/2022] Open
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43
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Membrane-anchored serine proteases as regulators of epithelial function. Biochem Soc Trans 2020; 48:517-528. [PMID: 32196551 PMCID: PMC9869603 DOI: 10.1042/bst20190675] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/28/2020] [Accepted: 03/04/2020] [Indexed: 02/07/2023]
Abstract
Cleavage of proteins in the extracellular milieu, including hormones, growth factors and their receptors, ion channels, and various cell adhesion and extracellular matrix molecules, plays a key role in the regulation of cell behavior. Among more than 500 proteolytic enzymes encoded by mammalian genomes, membrane-anchored serine proteases (MASPs), which are expressed on the surface of epithelial cells of all major organs, are excellently suited to mediate signal transduction across the epithelia and are increasingly being recognized as important regulators of epithelial development, function, and disease [ 1-3]. In this minireview, we summarize current knowledge of the in vivo roles of MASPs in acquisition and maintenance of some of the defining functions of epithelial tissues, such as barrier formation, ion transport, and sensory perception.
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44
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Bohnert BN, Kanse S, Haerteis S, Korbmacher C, Artunc F. Rebuttal to editorial: Sodium retention by uPA in nephrotic syndrome? Acta Physiol (Oxf) 2020; 228:e13427. [PMID: 31794131 DOI: 10.1111/apha.13427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 12/02/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Bernhard N. Bohnert
- Department of Internal Medicine Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Germany
| | - Sandip Kanse
- Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Silke Haerteis
- Institute of Anatomy University of Regensburg Regensburg Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Ferruh Artunc
- Department of Internal Medicine Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Germany
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45
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Hinrichs GR, Weyer K, Friis UG, Svenningsen P, Lund IK, Nielsen R, Mollet G, Antignac C, Bistrup C, Jensen BL, Birn H. Sodium retention by uPA-plasmin-ENaC in nephrotic syndrome-Authors reply. Acta Physiol (Oxf) 2020; 228:e13432. [PMID: 31845496 DOI: 10.1111/apha.13432] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/06/2019] [Accepted: 12/11/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Gitte R. Hinrichs
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Kathrin Weyer
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Ulla G. Friis
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Per Svenningsen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Ida Katrine Lund
- The Finsen Laboratory Biotech Research & Innovation Centre (BRIC) University of Copenhagen Copenhagen Denmark
| | - Rikke Nielsen
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Géraldine Mollet
- Laboratory of Hereditary Kidney Diseases Paris Descartes‐Sorbonne Paris Cité University Paris France
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases Paris Descartes‐Sorbonne Paris Cité University Paris France
- Department of Genetics Necker HospitalAssistance Publique‐Hôpitaux de Paris Paris France
| | - Claus Bistrup
- Department of Nephrology Odense University Hospital Odense Denmark
- Department of Clinical Research University of Southern Denmark Odense Denmark
| | - Boye L. Jensen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Henrik Birn
- Department of Biomedicine Aarhus University Aarhus Denmark
- Department of Renal Medicine Aarhus University Hospital Aarhus Denmark
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47
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Recent insights into sodium and potassium handling by the aldosterone-sensitive distal nephron: implications on pathophysiology and drug discovery. J Nephrol 2020; 33:447-466. [DOI: 10.1007/s40620-020-00700-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 01/02/2020] [Indexed: 12/31/2022]
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48
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Ehmke H. Sodium retention by uPA in nephrotic syndrome? Acta Physiol (Oxf) 2020; 228:e13393. [PMID: 31559686 DOI: 10.1111/apha.13393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 09/20/2019] [Indexed: 01/11/2023]
Affiliation(s)
- Heimo Ehmke
- Cellular and Integrative Physiology University Medical Center Hamburg‐Eppendorf Hamburg Germany
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49
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Dizin E, Olivier V, Maire C, Komarynets O, Sassi A, Roth I, Loffing J, de Seigneux S, Maillard M, Rutkowski JM, Edwards A, Feraille E. Time-course of sodium transport along the nephron in nephrotic syndrome: The role of potassium. FASEB J 2019; 34:2408-2424. [PMID: 31908015 DOI: 10.1096/fj.201901345r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/21/2019] [Accepted: 11/30/2019] [Indexed: 11/11/2022]
Abstract
The mechanism of sodium retention and its location in kidney tubules may vary with time in nephrotic syndrome (NS). We studied the mechanisms of sodium retention in transgenic POD-ATTAC mice, which display an inducible podocyte-specific apoptosis. At day 2 after the induction of NS, the increased abundance of NHE3 and phosphorylated NCC in nephrotic mice compared with controls suggest that early sodium retention occurs mainly in the proximal and distal tubules. At day 3, the abundance of NHE3 normalized, phosphorylated NCC levels decreased, and cleavage and apical localization of γ-ENaC increased in nephrotic mice. These findings indicate that sodium retention shifted from the proximal and distal tubules to the collecting system. Increased cleavage and apical localization of γ-ENaC persisted at day 5 in nephrotic mice when hypovolemia resolved and steady-state was reached. Sodium retention and γ-ENaC cleavage were independent of the increased plasma levels of aldosterone. Nephrotic mice displayed decreased glomerular filtration rate and urinary potassium excretion associated with hyperkaliemia at day 3. Feeding nephrotic mice with a low potassium diet prevented hyperkaliemia, γ-ENaC cleavage, and led to persistent increased phosphorylation of NCC. These results suggest that potassium homeostasis is a major determinant of the tubular site of sodium retention in nephrotic mice.
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Affiliation(s)
- Eva Dizin
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Charline Maire
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Olga Komarynets
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland
| | - Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Johannes Loffing
- National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland.,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Sophie de Seigneux
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Marc Maillard
- Service of Nephrology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Joseph M Rutkowski
- Department of Medical Physiology, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Aurélie Edwards
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
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50
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Bohnert BN, Daiminger S, Wörn M, Sure F, Staudner T, Ilyaskin AV, Batbouta F, Janessa A, Schneider JC, Essigke D, Kanse S, Haerteis S, Korbmacher C, Artunc F. Urokinase-type plasminogen activator (uPA) is not essential for epithelial sodium channel (ENaC)-mediated sodium retention in experimental nephrotic syndrome. Acta Physiol (Oxf) 2019; 227:e13286. [PMID: 31006168 DOI: 10.1111/apha.13286] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 12/17/2022]
Abstract
AIM In nephrotic syndrome, aberrantly filtered plasminogen (plg) is converted to active plasmin by tubular urokinase-type plasminogen activator (uPA) and thought to lead to sodium retention by proteolytic activation of the epithelial sodium channel (ENaC). This concept predicts that uPA is an important factor for sodium retention and that inhibition of uPA might be protective in nephrotic syndrome. METHODS Activation of amiloride-sensitive currents by uPA and plg were studied in Xenopus laevis oocytes expressing murine ENaC. In doxorubicin-induced nephrotic mice, uPA was inhibited pharmacologically by amiloride and genetically by the use of uPA-deficient mice (uPA-/- ). RESULTS Experiments in Xenopus laevis oocytes expressing murine ENaC confirmed proteolytic ENaC activation by a combination of plg and uPA which stimulated amiloride-sensitive currents with concomitant cleavage of the ENaC γ-subunit at the cell surface. Treatment of nephrotic wild-type mice with amiloride inhibited urinary uPA activity, prevented urinary plasmin formation and sodium retention. In nephrotic mice lacking uPA (uPA-/- ), urinary plasmin formation from plg was suppressed and urinary uPA activity absent. However, in nephrotic uPA-/- mice, sodium retention was not reduced compared to nephrotic uPA+/+ mice. Amiloride prevented sodium retention in nephrotic uPA-/- mice which confirmed the critical role of ENaC in sodium retention. CONCLUSION uPA is responsible for the conversion of aberrantly filtered plasminogen to plasmin in the tubular lumen in vivo. However, uPA-dependent plasmin generation is not essential for ENaC-mediated sodium retention in experimental nephrotic syndrome.
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Affiliation(s)
- Bernhard N. Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
| | - Sophie Daiminger
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Matthias Wörn
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Florian Sure
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Bayern Germany
| | - Tobias Staudner
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Bayern Germany
| | - Alexandr V. Ilyaskin
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Bayern Germany
| | - Firas Batbouta
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Jonas C. Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Daniel Essigke
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
| | - Sandip Kanse
- Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Silke Haerteis
- Institute of Anatomy University of Regensburg Regensburg Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Bayern Germany
| | - Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
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