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Yin R, Hu Z. U-shaped association between hemoglobin levels and albuminuria in US adults: a cross-sectional study. Int Urol Nephrol 2024:10.1007/s11255-024-04200-8. [PMID: 39244708 DOI: 10.1007/s11255-024-04200-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Accepted: 09/02/2024] [Indexed: 09/10/2024]
Abstract
PURPOSE This study aimed to explore the correlation between hemoglobin levels and albuminuria in US adults. METHODS This cross-sectional investigation analyzed the National Health and Nutrition Examination Survey (NHANES) information from 2011 to 2020. Data on hemoglobin, albuminuria, and other variables were collected from all participants. The logistic-regression analyses and smoothed curves were used to substantiate the research objectives. RESULTS The average age of the 8,868 participants was 49.5 ± 17.3 years, and 49.3% were men. The prevalence of albuminuria was 12.1%. After adjusting for potential variables in the logistic-regression analysis models, hemoglobin (per 1 g/dL increase) was inversely associated with the presence of albuminuria (odds ratio [OR], 0.92; 95% confidence interval [95%CI], 0.87-0.97). Compared with participants in quartile 3 (Q3, 14.1-15.0 g/dL) for hemoglobin levels, those in the lowest quartile 1 (Q1, 6.1-13.0 g/dL) and highest quartile 4 (Q4, 15.1-19.6 g/dL) had adjusted ORs for albuminuria of 1.48 (95% CI, 1.19-1.85) and 1.11 (95% CI, 0.9-1.38), respectively. Our observations indicated a U-shaped association between hemoglobin levels and albuminuria, with a point of inflection at approximately 15.5 g/dL. The effect sizes and CIs below and above this point were 0.853 (95% CI, 0.798-0.912) and 1.377 (95% CI, 1.055-1.797), respectively. CONCLUSION This study indicates that the presence of albuminuria is linked to both low and high hemoglobin levels in US adults. The management of hemoglobin may benefit kidney health.
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Affiliation(s)
- Rong Yin
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
- Department of Nephrology, Hospital of Chengdu Office of People's Government of Tibet Autonomous Region, Chengdu, Sichuan, China
| | - Zhangxue Hu
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China.
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Randle RK, Amara VR, Popik W. IFI16 Is Indispensable for Promoting HIF-1α-Mediated APOL1 Expression in Human Podocytes under Hypoxic Conditions. Int J Mol Sci 2024; 25:3324. [PMID: 38542298 PMCID: PMC10970439 DOI: 10.3390/ijms25063324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/28/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024] Open
Abstract
Genetic variants in the protein-coding regions of APOL1 are associated with an increased risk and progression of chronic kidney disease (CKD) in African Americans. Hypoxia exacerbates CKD progression by stabilizing HIF-1α, which induces APOL1 transcription in kidney podocytes. However, the contribution of additional mediators to regulating APOL1 expression under hypoxia in podocytes is unknown. Here, we report that a transient accumulation of HIF-1α in hypoxia is sufficient to upregulate APOL1 expression in podocytes through a cGAS/STING/IRF3-independent pathway. Notably, IFI16 ablation impedes hypoxia-driven APOL1 expression despite the nuclear accumulation of HIF-1α. Co-immunoprecipitation assays indicate no direct interaction between IFI16 and HIF-1α. Our studies identify hypoxia response elements (HREs) in the APOL1 gene enhancer/promoter region, showing increased HIF-1α binding to HREs located in the APOL1 gene enhancer. Luciferase reporter assays confirm the role of these HREs in transcriptional activation. Chromatin immunoprecipitation (ChIP)-qPCR assays demonstrate that IFI16 is not recruited to HREs, and IFI16 deletion reduces HIF-1α binding to APOL1 HREs. RT-qPCR analysis indicates that IFI16 selectively affects APOL1 expression, with a negligible impact on other hypoxia-responsive genes in podocytes. These findings highlight the unique contribution of IFI16 to hypoxia-driven APOL1 gene expression and suggest alternative IFI16-dependent mechanisms regulating APOL1 gene expression under hypoxic conditions.
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Affiliation(s)
- Richaundra K. Randle
- Department of Biomedical Sciences, School of Graduate Studies, Meharry Medical College, Nashville, TN 37208, USA;
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, TN 37208, USA;
| | - Venkateswara Rao Amara
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, TN 37208, USA;
- Department of Regulatory Toxicology, National Institute of Pharmaceutical Education and Research, Hajipur 844102, Bihar, India
| | - Waldemar Popik
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, TN 37208, USA;
- Department of Internal Medicine, School of Medicine, Meharry Medical College, Nashville, TN 37208, USA
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Schult L, Halbgebauer R, Karasu E, Huber-Lang M. Glomerular injury after trauma, burn, and sepsis. J Nephrol 2023; 36:2417-2429. [PMID: 37542608 PMCID: PMC10703988 DOI: 10.1007/s40620-023-01718-5] [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: 03/24/2023] [Accepted: 06/23/2023] [Indexed: 08/07/2023]
Abstract
Acute kidney injury development after trauma, burn, or sepsis occurs frequently but remains a scientific and clinical challenge. Whereas the pathophysiological focus has mainly been on hemodynamics and the downstream renal tubular system, little is known about alterations upstream within the glomerulus post trauma or during sepsis. Particularly for the glomerular endothelial cells, mesangial cells, basal membrane, and podocytes, all of which form the glomerular filter, there are numerous in vitro studies on the molecular and functional consequences upon exposure of single cell types to specific damage- or microbial-associated molecular patterns. By contrast, a lack of knowledge exists in the real world regarding the orchestrated inflammatory response of the glomerulus post trauma or burn or during sepsis. Therefore, we aim to provide an overview on the glomerulus as an immune target but also as a perpetrator of the danger response to traumatic and septic conditions, and present major players involved in the context of critical illness. Finally, we highlight research gaps of this rather neglected but worthwhile area to define future molecular targets and therapeutic strategies to prevent or improve the course of AKI after trauma, burn, or sepsis.
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Affiliation(s)
- Lorena Schult
- Institute of Clinical and Experimental Trauma Immunology, University Hospital Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
| | - Rebecca Halbgebauer
- Institute of Clinical and Experimental Trauma Immunology, University Hospital Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
| | - Ebru Karasu
- Institute of Clinical and Experimental Trauma Immunology, University Hospital Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany
| | - Markus Huber-Lang
- Institute of Clinical and Experimental Trauma Immunology, University Hospital Ulm, Helmholtzstr. 8/1, 89081, Ulm, Germany.
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Hypoxia-Inducible Factors and Diabetic Kidney Disease—How Deep Can We Go? Int J Mol Sci 2022; 23:ijms231810413. [PMID: 36142323 PMCID: PMC9499602 DOI: 10.3390/ijms231810413] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/17/2022] Open
Abstract
Diabetes is one of the leading causes of chronic kidney disease (CKD), and multiple underlying mechanisms involved in pathogenesis of diabetic nephropathy (DN) have been described. Although various treatments and diagnosis applications are available, DN remains a clinical and economic burden, considering that about 40% of type 2 diabetes patients will develop nephropathy. In the past years, some research found that hypoxia response and hypoxia-inducible factors (HIFs) play critical roles in the pathogenesis of DN. Hypoxia-inducible factors (HIFs) HIF-1, HIF-2, and HIF-3 are the main mediators of metabolic responses to the state of hypoxia, which seems to be the one of the earliest events in the occurrence and progression of diabetic kidney disease (DKD). The abnormal activity of HIFs seems to be of crucial importance in the pathogenesis of diseases, including nephropathies. Studies using transcriptome analysis confirmed by metabolome analysis revealed that HIF stabilizers (HIF-prolyl hydroxylase inhibitors) are novel therapeutic agents used to treat anemia in CKD patients that not only increase endogenous erythropoietin production, but also could act by counteracting the metabolic alterations in incipient diabetic kidney disease and relieve oxidative stress in the renal tissue. In this review, we present the newest data regarding hypoxia response and HIF involvement in the pathogenesis of diabetic nephropathy and new therapeutic insights, starting from improving kidney oxygen homeostasis.
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Ren Z, Potenza DM, Ma Y, Ajalbert G, Hoogewijs D, Ming XF, Yang Z. Role of Arginase-II in Podocyte Injury under Hypoxic Conditions. Biomolecules 2022; 12:biom12091213. [PMID: 36139052 PMCID: PMC9496188 DOI: 10.3390/biom12091213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Hypoxia plays a crucial role in acute and chronic renal injury, which is attributable to renal tubular and glomerular cell damage. Some studies provide evidence that hypoxia-dependent upregulation of the mitochondrial enzyme arginase type-II (Arg-II) in tubular cells promotes renal tubular injury. It is, however, not known whether Arg-II is also expressed in glomerular cells, particularly podocytes under hypoxic conditions, contributing to hypoxia-induced podocyte injury. The effects of hypoxia on human podocyte cells (AB8/13) in cultures and on isolated kidneys from wild-type (wt) and arg-ii gene-deficient (arg-ii−/−) mice ex vivo, as well as on mice of the two genotypes in vivo, were investigated, respectively. We found that the Arg-II levels were enhanced in cultured podocytes in a time-dependent manner over 48 h, which was dependent on the stabilization of hypoxia-inducible factor 1α (HIF1α). Moreover, a hypoxia-induced derangement of cellular actin cytoskeletal fibers, a decrease in podocin, and an increase in mitochondrial ROS (mtROS) generation—as measured by MitoSOX—were inhibited by adenoviral-mediated arg-ii gene silencing. These effects of hypoxia on podocyte injury were mimicked by the HIFα stabilizing drug DMOG, which inhibits prolyl hydroxylases (PHD), the enzymes involved in HIFα degradation. The silencing of arg-ii prevented the detrimental effects of DMOG on podocytes. Furthermore, the inhibition of mtROS generation by rotenone—the inhibitor of respiration chain complex-I—recapitulated the protective effects of arg-ii silencing on podocytes under hypoxic conditions. Moreover, the ex vivo experiments with isolated kidney tissues and the in vivo experiments with mice exposed to hypoxic conditions showed increased Arg-II levels in podocytes and decreased podocyte markers regarding synaptopodin in wt mice but not in arg-ii−/− mice. While age-associated albuminuria was reduced in the arg-ii−/− mice, the hypoxia-induced increase in albuminuria was, however, not significantly affected in the arg-ii−/−. Our study demonstrates that Arg-II in podocytes promotes cell injury. Arg-ii ablation seems insufficient to protect mice in vivo against a hypoxia-induced increase in albuminuria, but it does reduce albuminuria in aging.
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Affiliation(s)
- Zhilong Ren
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Department of Nephrology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Duilio Michele Potenza
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Yiqiong Ma
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Department of Nephrology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Guillaume Ajalbert
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - David Hoogewijs
- Integrative Oxygen Physiology, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Xiu-Fen Ming
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Correspondence: (X.-F.M.); (Z.Y.); Tel.: +41-26-300-85-93 (Z.Y.)
| | - Zhihong Yang
- Cardiovascular & Aging Research, Department of Endocrinology, Metabolism, Cardiovascular System, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
- Correspondence: (X.-F.M.); (Z.Y.); Tel.: +41-26-300-85-93 (Z.Y.)
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Kallash M, Mahan JD. Mechanisms and management of edema in pediatric nephrotic syndrome. Pediatr Nephrol 2021; 36:1719-1730. [PMID: 33216218 DOI: 10.1007/s00467-020-04779-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/18/2020] [Accepted: 09/11/2020] [Indexed: 10/23/2022]
Abstract
Edema is the abnormal accumulation of fluid in the interstitial compartment of tissues within the body. In nephrotic syndrome, edema is often seen in dependent areas such as the legs, but it can progress to cause significant accumulation in other areas leading to pulmonary edema, ascites, and/or anasarca. In this review, we focus on mechanisms and management of edema in children with nephrotic syndrome. We review the common mechanisms of edema, its burden in pediatric patients, and then present our approach and algorithm for management of edema in pediatric patients. The extensive body of experience accumulated over the last 5 decades means that there are many options, and clinicians may choose among these options based on their experience and careful monitoring of responses in individual patients.
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Affiliation(s)
- Mahmoud Kallash
- Division of Pediatric Nephrology, Nationwide Children's Hospital, 700 Children's Dr., Columbus, OH, 43205, USA. .,The Ohio State University College of Medicine, Columbus, OH, USA.
| | - John D Mahan
- Division of Pediatric Nephrology, Nationwide Children's Hospital, 700 Children's Dr., Columbus, OH, 43205, USA.,The Ohio State University College of Medicine, Columbus, OH, USA
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Singh AK, Kolligundla LP, Francis J, Pasupulati AK. Detrimental effects of hypoxia on glomerular podocytes. J Physiol Biochem 2021; 77:193-203. [PMID: 33835424 DOI: 10.1007/s13105-021-00788-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 01/11/2021] [Indexed: 12/19/2022]
Abstract
Hypoxia-inducible factor1 (HIF1) plays a pivotal role in ensuring cells adapt to low-oxygen conditions. Depletion of oxygen, a co-substrate during hydroxylation of prolyl (P402 and P564) residues of HIF1⍺, evades HIF1⍺ ubiquitination and enables its dimerization with HIF1β to mediate global transcriptional response to hypoxia. Though HIF1 is largely considered eliciting a protective role during physiological or pathological hypoxia or ischemia, elevated HIF1 during chronic hypoxia contributes to glomerular diseases' pathology and proteinuria. The glomerulus is responsible for renal permselectivity and excretion of ultra-filtrated urine. Podocytes are the glomerulus' major cell types and are instrumental for glomerular filtration, permselectivity, and glomerular basement membrane maintenance. Podocyte injury is expected to impair the efficiency of glomerular filtration and manifestation of glomerulosclerosis and proteinuria. Accumulated evidence suggests that podocytes are susceptible to various insults during chronic hypoxia, including podocyte EMT, slit-diaphragm dysfunction, foot process effacement, and cytoskeletal derangement due to accumulation of HIF1. This review discusses how hypoxia/HIF1 signaling regulates various features and function of podocytes during exposure to chronic hypoxia or inducing HIF1 by various chemical modulators.
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Affiliation(s)
- Ashish K Singh
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Lakshmi P Kolligundla
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Justus Francis
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Anil K Pasupulati
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
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Sugimoto K, Miyazawa T, Enya T, Miyazaki K, Okada M, Takemura T. Cyclosporine A induced histological changes of Cathepsin L and CD2AP expression in renal glomeruli and tubules. Clin Exp Nephrol 2016; 21:83-91. [PMID: 26975192 DOI: 10.1007/s10157-016-1257-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/03/2016] [Indexed: 01/09/2023]
Abstract
BACKGROUND Cyclosporine A (CsA) is used globally as an immunosuppressant for the treatment of immune-mediated nephrotic syndrome (NS). However, its long-term use causes nephrotoxicity characterized by tubulointerstitial injury and glomerulosclerosis. The present study aimed to investigate the associations between histomorphological findings and immunohistological expression of Cathepsin L (CatL) and CD2-associated protein (CD2AP) in patients with NS mediated with CsA. METHODS A total of 18 patients with child-onset NS were divided into two groups after treatment with CsA for 2 years (group A; n = 10) and more than 4 years (group B; n = 8), respectively. Analyses of relationships between tubulointerstitial disorders and expression of CatL and CD2AP proteins were performed using immunohistochemistry of paired renal specimens. RESULTS Glomeruli with arteriole hyalinization were significantly increased in both groups depending on dosage periods, although degrees of tubule and interstitial injury did not differ between groups. CD2AP expression was significantly greater in podocytes (P = 0.046) and was significantly less in proximal tubule cells (P = 0.014) in patients of group B compared with those of group A. Moreover, CD2AP expression was significantly increased in lateral tubule cells in both groups (group A, P = 0.02; group B, P = 0.001), and CatL expression in glomeruli and tubule cells did not change with the duration of CsA treatment in either patient group. CONCLUSIONS CD2AP expression in renal tubules may histologically associate with tissue hypoxia and reflected recovery from CsA-mediated renal injury in patients, even with mild histological features of tubulointerstitial disorder.
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Affiliation(s)
- Keisuke Sugimoto
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan.
| | - Tomoki Miyazawa
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan
| | - Takuji Enya
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan
| | - Kouhei Miyazaki
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan
| | - Mitsuru Okada
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan
| | - Tsukasa Takemura
- Department of Pediatrics, Kinki University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-sayama, Osaka, 589-8511, Japan
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Harvey TW, Engel JE, Chade AR. Vascular Endothelial Growth Factor and Podocyte Protection in Chronic Hypoxia: Effects of Endothelin-A Receptor Antagonism. Am J Nephrol 2016; 43:74-84. [PMID: 26930122 DOI: 10.1159/000444719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/12/2016] [Indexed: 12/14/2022]
Abstract
BACKGROUND Podocytes are major components of the filtration barrier and a renal source of vascular endothelial growth factor (VEGF). Chronic renovascular disease (RVD) progressively degrades the renal function, accompanied by podocyte damage and a progressive reduction in VEGF. We showed that the endothelin (ET) pathway contributes to this pathological process and ET-A (but not ET-B) receptor antagonism protects the kidney in RVD. We hypothesize that ET-A-induced renoprotection is largely driven by the protection of podocyte integrity and function. METHODS To mimic the renal environment of chronic RVD, human podocytes were incubated under chronic hypoxia for 96 h and divided in untreated or treated with an ET-A or ET-B receptor antagonist. Cells were quantified after 96 h. Cell homogenates and media were obtained after 1, 24 and 96 h to quantify production of VEGF, anti-VEGF soluble receptor s-Flt1, and the expression of apoptotic mediators. A separate set of similar experiments was performed after addition of a VEGF-neutralizing antibody (VEGF-NA). RESULTS Hypoxia decreased podocyte number, which was exacerbated by ET-B but improved after ET-A antagonism. Production of VEGF was preserved by ET-A antagonism, whereas s-Flt1 increased in hypoxic cells after ET-B antagonism only, accompanied by a greater expression of pro-apoptotic mediators. On the other hand, treatment with VEGF-NA diminished ET-A-induced protection of podocytes. CONCLUSION ET-A antagonism preserves podocyte viability and integrity under chronic hypoxia, whereas ET-B antagonism exacerbates podocyte dysfunction and death. Enhanced bioavailability of VEGF after ET-A antagonism could be a pivotal mechanism of podocyte protection that significantly contributes to ET-A receptor blockade-induced renal recovery in chronic RVD.
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Affiliation(s)
- Taylor W Harvey
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Miss., USA
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Narita I, Shimada M, Yamabe H, Kinjo T, Tanno T, Nishizaki K, Kawai M, Nakamura M, Murakami R, Nakamura N, Tomita H, Saleem MA, Mathieson PW, Okumura K. NF-κB-dependent increase in tissue factor expression is responsible for hypoxic podocyte injury. Clin Exp Nephrol 2015; 20:679-688. [PMID: 26715508 DOI: 10.1007/s10157-015-1214-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 12/09/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Fibrin deposition within glomeruli is commonly seen in kidney biopsy specimens, suggesting enhanced coagulant activity. Tissue factor (TF) is a coagulation factor which is also related to various biological effects, and TF is upregulated by hypoxia in cancer cells. Recently, hypoxic podocyte injury has been proposed, therefore, we investigated TF expression in hypoxia. METHODS Conditionally immortalized human podocytes were differentiated and treated under hypoxic or normoxic conditions. mRNA expressions of TF and tissue factor pathway inhibitor (TFPI) were analyzed by quantitative RT-PCR. Protein levels of TF and TFPI were tested by enzyme-linked immunosorbent assay. We employed small interfering RNA (siRNA) to temporary knockdown early growth response protein 1 (Egr-1), hypoxia-inducible factor-1α (HIF-1α) and TF. The expression of CD2-associated protein (CD2AP) mRNA and phalloidin staining was examined to assess podocyte injury. RESULTS Hypoxia increased mRNA expression of TF (6 h: 2.3 ± 0.05 fold, p < 0.001, 24 h: 5.6 ± 2.4 fold, p < 0.05) and suppressed TFPI (6 h: 0.54 ± 0.04 fold, p < 0.05, 24 h: 0.24 ± 0.06 fold, p < 0.001) compared with normoxia. Similarly, protein levels of TF were increased and TFPI were decreased. Egr-1 siRNA did not change TF mRNA expression. Pyrrolidine dithiocarbamate (PDTC), a nuclear factor kappa B (NF-κB) inhibitor, significantly reduced hypoxia induced TF expression, and HIF-1α knockdown further increased TF. Hypoxia resulted in decreased CD2AP and actin reorganization in podocytes, and these changes were attenuated by TF siRNA. CONCLUSION Hypoxia increased the expression of TF in human podocytes NF-κB dependently. TF may have a critical role in the hypoxic podocyte injury.
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Affiliation(s)
- Ikuyo Narita
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Michiko Shimada
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan.
| | - Hideaki Yamabe
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Takahiko Kinjo
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Tomohiro Tanno
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Kimitaka Nishizaki
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Misato Kawai
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Masayuki Nakamura
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Reiichi Murakami
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Norio Nakamura
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Hirofumi Tomita
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
| | - Moin A Saleem
- Bristol Renal, University of Bristol, Dorothy Hodgkin Building, Bristol, UK
| | | | - Ken Okumura
- Department of Cardiology and Nephrology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562, Japan
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Hirose Y, Johnson ZI, Schoepflin ZR, Markova DZ, Chiba K, Toyama Y, Shapiro IM, Risbud MV. FIH-1-Mint3 axis does not control HIF-1 transcriptional activity in nucleus pulposus cells. J Biol Chem 2015; 289:20594-605. [PMID: 24867948 DOI: 10.1074/jbc.m114.565101] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The objective of this study was to determine the role of FIH-1 in regulating HIF-1 activity in the nucleus pulposus (NP) cells and the control of this regulation by binding and sequestration of FIH-1 by Mint3. FIH-1 and Mint3 were both expressed in the NP and were shown to strongly co-localize within the cell nucleus. Although both mRNA and protein expression of FIH-1 decreased in hypoxia, only Mint3 protein levels were hypoxiasensitive. Overexpression of FIH-1 was able to reduce HIF-1 function, as seen by changes in activities of hypoxia response element-luciferase reporter and HIF-1-C-TAD and HIF-2-TAD. Moreover, co-transfection of either full-length Mint3 or the N terminus of Mint3 abrogated FIH-1-dependent reduction in HIF-1 activity under both normoxia and hypoxia. Nuclear levels of FIH-1 and Mint3 decreased in hypoxia, and the use of specific nuclear import and export inhibitors clearly showed that cellular compartmentalization of overexpressed FIH-1 was critical for its regulation of HIF-1 activity in NP cells. Interestingly, microarray results after stable silencing of FIH-1 showed no significant changes in transcripts of classical HIF-1 target genes. However, expression of several other transcripts, including those of the Notch pathway, changed in FIH-1-silenced cells. Moreover, co-transfection of Notch-ICD could restore suppression of HIF-1-TAD activity by exogenous FIH-1. Taken together, these results suggest that, possibly due to low endogenous levels and/or preferential association with substrates such as Notch, FIH-1 activity does not represent a major mechanism by which NP cells control HIF-1-dependent transcription, a testament to their adaptation to a unique hypoxic niche.
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Skimmin, a Coumarin from Hydrangea paniculata, Slows down the Progression of Membranous Glomerulonephritis by Anti-Inflammatory Effects and Inhibiting Immune Complex Deposition. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:819296. [PMID: 23990847 PMCID: PMC3748779 DOI: 10.1155/2013/819296] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/08/2013] [Accepted: 07/08/2013] [Indexed: 11/18/2022]
Abstract
Skimmin is one of the major pharmacologically active molecules present in Hydrangea paniculata, a medical herb used in the traditional Chinese medicine as an anti-inflammatory agent. In the current study, we attempted to investigate its renoprotective activity and underlying mechanisms in a rat model of membranous glomerulonephritis induced by cationic bovine serum albumin (c-BSA). Sprague-Dawley (SD) rats were divided into five groups, including normal control, model control, Mycophenolate Mofetil-treated group, and two skimming-treated groups (15 mg/kg and 30 mg/kg). Our research showed that treatment with skimmin significantly reduced the levels of blood urea nitrogen (BUN), urinary albumin excretion (UAE), and serum creatinine (Scr) as compared with model control after experimental induction of membranous glomerulonephritis (P < 0.01). Moreover, glomerular hypercellularity, tubulointerstitial injury, and glomerular deposition of IgG were less intense after skimmin treatment. By immunochemistry analysis, we demonstrated that skimmin could significantly inhibit interleukin-1 β (IL1 β ) and IL-6 expression (P < 0.05), reduce the loss of nephrin and podocin, and suppress the infiltration of renal interstitium by CD3-positive T cell and CD20-positive B cell. These results suggest that treatment with skimmin can significantly improve renal function and suppress the IgG deposition as well as the development of glomerular lesions in a rat model of membranous glomerulonephritis.
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