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Wang L, Song Y, Zhang P, Chen W, Xiao F, Zhou P, Yang X, Dai H. Hypoxia-inducible factor prolyl hydroxylase inhibitor alleviates heatstroke-induced acute kidney injury by activating BNIP3-mediated mitophagy. FASEB J 2024; 38:e23723. [PMID: 38865198 DOI: 10.1096/fj.202400047r] [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: 01/08/2024] [Revised: 03/28/2024] [Accepted: 04/08/2024] [Indexed: 06/14/2024]
Abstract
Hypoxia-induced inflammation and apoptosis are important pathophysiological features of heat stroke-induced acute kidney injury (HS-AKI). Hypoxia-inducible factor (HIF) is a key protein that regulates cell adaptation to hypoxia. HIF-prolyl hydroxylase inhibitor (HIF-PHI) stabilizes HIF to increase cell adaptation to hypoxia. Herein, we reported that HIF-PHI pretreatment significantly improved renal function, enhanced thermotolerance, and increased the survival rate of mice in the context of HS. Moreover, HIF-PHI could alleviate HS-induced mitochondrial damage, inflammation, and apoptosis in renal tubular epithelial cells (RTECs) by enhancing mitophagy in vitro and in vivo. By contrast, mitophagy inhibitors Mdivi-1, 3-MA, and Baf-A1 reversed the renoprotective effects of HIF-PHI. Mechanistically, HIF-PHI protects RTECs from inflammation and apoptosis by enhancing Bcl-2 adenovirus E18 19-kDa-interacting protein 3 (BNIP3)-mediated mitophagy, while genetic ablation of BNIP3 attenuated HIF-PHI-induced mitophagy and abolished HIF-PHI-mediated renal protection. Thus, our results indicated that HIF-PHI protects renal function by upregulating BNIP3-mediated mitophagy to improve HS-induced inflammation and apoptosis of RTECs, suggesting HIF-PHI as a promising therapeutic agent to treat HS-AKI.
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Affiliation(s)
- Ling Wang
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
| | - Yongwei Song
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
| | - Pan Zhang
- Department of Tropical Medicine, Army Medical University, Chongqing, China
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China
| | - Wenting Chen
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
| | - Fei Xiao
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
| | - Ping Zhou
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
| | - Xuesen Yang
- Department of Tropical Medicine, Army Medical University, Chongqing, China
- Key Laboratory of Extreme Environmental Medicine, Ministry of Education of China, Army Medical University, Chongqing, China
| | - Huanzi Dai
- Department of Rheumatology and Clinical Immunology, Daping Hospital, Army Medical University, Chongqing, China
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2
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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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3
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Robinson S, Nag A, Peticca B, Prudencio T, Di Carlo A, Karhadkar S. Renal Cell Carcinoma in End-Stage Kidney Disease and the Role of Transplantation. Cancers (Basel) 2023; 16:3. [PMID: 38201432 PMCID: PMC10777936 DOI: 10.3390/cancers16010003] [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: 10/20/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024] Open
Abstract
Kidney transplant patients have a higher risk of renal cell carcinoma (RCC) compared to non-transplanted end-stage kidney disease (ESKD) patients. This increased risk has largely been associated with the use of immunosuppression; however, recent genetic research highlights the significance of tissue specificity in cancer driver genes. The implication of tissue specificity becomes more obscure when addressing transplant patients, as two distinct metabolic environments are present within one individual. The oncogenic potential of donor renal tissue is largely unknown but assumed to pose minimal risk to the kidney transplant recipient (KTR). Our review challenges this notion by examining how donor and recipient microenvironments impact a transplant recipient's associated risk of renal cell carcinoma. In doing so, we attempt to encapsulate how ESKD-RCC and KTR-RCC differ in their incidence, pathogenesis, outcome, and approach to management.
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Affiliation(s)
- Samuel Robinson
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (S.R.); (B.P.); (T.P.); (A.D.C.)
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
| | - Alena Nag
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
| | - Benjamin Peticca
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (S.R.); (B.P.); (T.P.); (A.D.C.)
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
| | - Tomas Prudencio
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (S.R.); (B.P.); (T.P.); (A.D.C.)
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
| | - Antonio Di Carlo
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (S.R.); (B.P.); (T.P.); (A.D.C.)
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
| | - Sunil Karhadkar
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (S.R.); (B.P.); (T.P.); (A.D.C.)
- Department of Surgery, Temple University Hospital, Philadelphia, PA 19140, USA;
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4
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Nørgård MØ, Svenningsen P. Acute Kidney Injury by Ischemia/Reperfusion and Extracellular Vesicles. Int J Mol Sci 2023; 24:15312. [PMID: 37894994 PMCID: PMC10607034 DOI: 10.3390/ijms242015312] [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: 09/26/2023] [Revised: 10/12/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
Acute kidney injury (AKI) is often caused by ischemia-reperfusion injury (IRI). IRI significantly affects kidney metabolism, which elicits pro-inflammatory responses and kidney injury. The ischemia/reperfusion of the kidney is associated with transient high mitochondrial-derived reactive oxygen species (ROS) production rates. Excessive mitochondrial-derived ROS damages cellular components and, together with other pathogenic mechanisms, elicits a range of acute injury mechanisms that impair kidney function. Mitochondrial-derived ROS production also stimulates epithelial cell secretion of extracellular vesicles (EVs) containing RNAs, lipids, and proteins, suggesting that EVs are involved in AKI pathogenesis. This literature review focuses on how EV secretion is stimulated during ischemia/reperfusion and how cell-specific EVs and their molecular cargo may modify the IRI process. Moreover, critical pitfalls in the analysis of kidney epithelial-derived EVs are described. In particular, we will focus on how the release of kidney epithelial EVs is affected during tissue analyses and how this may confound data on cell-to-cell signaling. By increasing awareness of methodological pitfalls in renal EV research, the risk of false negatives can be mitigated. This will improve future EV data interpretation regarding EVs contribution to AKI pathogenesis and their potential as biomarkers or treatments for AKI.
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Affiliation(s)
| | - Per Svenningsen
- Department of Molecular Medicine, University of Southern Denmark, DK-5000 Odense, Denmark;
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5
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Carter AW, Engoren M. Factors associated with occurrence and severity of acute kidney injury in patients with Sepsis - A retrospective database study. J Crit Care 2022; 72:154150. [PMID: 36244255 DOI: 10.1016/j.jcrc.2022.154150] [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: 05/06/2022] [Revised: 07/12/2022] [Accepted: 09/04/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE Sepsis remains the most common cause of acute kidney injury (AKI) and is associated with a high mortality. This study aims to identify laboratory, clinical and demographic factors that are associated with the different stages of AKI in sepsis. METHODS We studied patients >18 years who met Sepsis-3 criteria between July 10, 2009 and September 7, 2019 using ordinal logistic regression to determine the factors associated with different stages of AKI. Sensitivity analyses for development of any stage vs no AKI and, separately, the factors associated with receipt of kidney replacement therapy were also done. RESULTS Of 31,228 patients meeting Sepsis-3 criteria, 4684 (15%) developed AKI. Of the AKI patients, 53% were KDIGO stage 1, 9% stage 2, and 37% stage 3, with 27% of AKI patients receiving kidney replacement therapy (Stage 3b). Several comorbidities, mechanical ventilation, and pre-sepsis creatinine levels were associated with AKI occurrence and severity. Positive blood culture was associated with a higher risk (OR 1.10 [1.06, 1.15], p < 0.001), while positive respiratory, urine, and wound cultures were associated with lower risks of developing AKI and with lower severity. CONCLUSION Presepsis creatinine levels, mechanical ventilation, comorbidities, and positive blood cultures were associated with AKI.
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Affiliation(s)
- Adam W Carter
- Department of Anesthesiology, University of Michigan, 1500 E Medical Center Drive, Ann Arbor, MI 48109, United States.
| | - Milo Engoren
- Department of Anesthesiology, University of Michigan, 1500 E Medical Center Drive, Ann Arbor, MI 48109, United States.
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6
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Liu H, Li Y, Xiong J. The Role of Hypoxia-Inducible Factor-1 Alpha in Renal Disease. Molecules 2022; 27:molecules27217318. [PMID: 36364144 PMCID: PMC9657345 DOI: 10.3390/molecules27217318] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/23/2022] [Accepted: 10/24/2022] [Indexed: 11/24/2022] Open
Abstract
Partial pressure of oxygen (pO2) in the kidney is maintained at a relatively stable level by a unique and complex functional interplay between renal blood flow, glomerular filtration rate (GFR), oxygen consumption, and arteriovenous oxygen shunting. The vulnerability of this interaction renders the kidney vulnerable to hypoxic injury, leading to different renal diseases. Hypoxia has long been recognized as an important factor in the pathogenesis of acute kidney injury (AKI), especially renal ischemia/reperfusion injury. Accumulating evidence suggests that hypoxia also plays an important role in the pathogenesis and progression of chronic kidney disease (CKD) and CKD-related complications, such as anemia, cardiovascular events, and sarcopenia. In addition, renal cancer is linked to the deregulation of hypoxia pathways. Renal cancer utilizes various molecular pathways to respond and adapt to changes in renal oxygenation. Particularly, hypoxia-inducible factor (HIF) (including HIF-1, 2, 3) has been shown to be activated in renal disease and plays a major role in the protective response to hypoxia. HIF-1 is a heterodimer that is composed of an oxygen-regulated HIF-1α subunit and a constitutively expressed HIF-1β subunit. In renal diseases, the critical characteristic of HIF-1α is protective, but it also has a negative effect, such as in sarcopenia. This review summarizes the mechanisms of HIF-1α regulation in renal disease.
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Affiliation(s)
| | | | - Jing Xiong
- Correspondence: ; Tel.: +86-027-8572-6713
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7
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Hansen S, Wood DK. Simultaneous quantification of blood rheology and oxygen saturation to evaluate affinity-modifying therapies in sickle cell disease. LAB ON A CHIP 2022; 22:4141-4150. [PMID: 36134535 PMCID: PMC10165883 DOI: 10.1039/d2lc00623e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Sickle cell blood demonstrates oxygen-dependent flow behavior as a result of HbS polymerization during hypoxia, and these rheological changes provide a biophysical metric that can be used to quantify the pathological behavior of the blood. Relating these rheological changes directly to hemoglobin oxygen saturation would improve our understanding of SCD pathogenesis and the potential effects of therapeutic drugs. Towards this end, we have developed a microfluidic platform capable of spectrophotometric quantification of Hb-O2 saturation and simultaneous evaluation of the accompanying rheological changes in SCD blood flow. We demonstrated the ability to measure changes in Hb-O2 affinity and a restoration of oxygen-independent blood flow behavior after incubation with voxelotor, an oxygen affinity modifying drug approved for use in SCD. We also identified regimes in Hb-O2 saturation where the effects of HbS polymerization begin to take effect in contributing to pathological flow behavior, independent of voxelotor treatment. In contrast, incubation with voxelotor recovered oxygen-dependent blood flow over a range of PO2, providing a framework for understanding voxelotor's therapeutic effect in lowering the PO2 at which the requisite Hb-O2 saturation is reached to observe pathological blood flow. These results help explain the mechanistic effects of voxelotor and show the potential of this platform to identify affinity-modifying compounds and evaluate their therapeutic effect on blood flow.
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Affiliation(s)
- Scott Hansen
- Department of Biomedical Engineering, University of Minnesota, Minneapolis 55409, USA.
| | - David K Wood
- Department of Biomedical Engineering, University of Minnesota, Minneapolis 55409, USA.
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8
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Hu Y, Lu H, Li H, Ge J. Molecular basis and clinical implications of HIFs in cardiovascular diseases. Trends Mol Med 2022; 28:916-938. [PMID: 36208988 DOI: 10.1016/j.molmed.2022.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/18/2022]
Abstract
Oxygen maintains the homeostasis of an organism in a delicate balance in different tissues and organs. Under hypoxic conditions, hypoxia-inducible factors (HIFs) are specific and dominant factors in the spatiotemporal regulation of oxygen homeostasis. As the most basic functional unit of the heart at the cellular level, the cardiomyocyte relies on oxygen and nutrients delivered by the microvasculature to keep the heart functioning properly. Under hypoxic stress, HIFs are involved in acute and chronic myocardial pathology because of their spatiotemporal specificity, thus granting them therapeutic potential. Most adult animals lack the ability to regenerate their myocardium entirely following injury, and complete regeneration has long been a goal of clinical treatment for heart failure. The precise manipulation of HIFs (considering their dynamic balance and transformation) and the development of HIF-targeted drugs is therefore an extremely attractive cardioprotective therapy for protecting against myocardial ischemic and hypoxic injury, avoiding myocardial remodeling and heart failure, and promoting recovery of cardiac function.
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Affiliation(s)
- Yiqing Hu
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, China
| | - Hao Lu
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, China; National Clinical Research Center for Interventional Medicine, Shanghai, China; Shanghai Clinical Research Center for Interventional Medicine, Shanghai, China
| | - Hua Li
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, China.
| | - Junbo Ge
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, China; National Clinical Research Center for Interventional Medicine, Shanghai, China; Shanghai Clinical Research Center for Interventional Medicine, Shanghai, China; Key Laboratory of Viral Heart Diseases, National Health Commission, Shanghai, China; Key Laboratory of Viral Heart Diseases, Chinese Academy of Medical Sciences, Shanghai, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
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9
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Della Rocca Y, Fonticoli L, Rajan TS, Trubiani O, Caputi S, Diomede F, Pizzicannella J, Marconi GD. Hypoxia: molecular pathophysiological mechanisms in human diseases. J Physiol Biochem 2022; 78:739-752. [PMID: 35870078 PMCID: PMC9684243 DOI: 10.1007/s13105-022-00912-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 07/14/2022] [Indexed: 12/01/2022]
Abstract
Abstract
Hypoxia, a low O2 tension, is a fundamental feature that occurs in physiological events as well as pathophysiological conditions, especially mentioned for its role in the mechanism of angiogenesis, glucose metabolism, and cell proliferation/survival. The hypoxic state through the activation of specific mechanisms is an aggravating circumstance commonly noticed in multiple sclerosis, cancer, heart disease, kidney disease, liver disease, lung disease, and in inflammatory bowel disease. On the other hand, hypoxia could play a key role in tissue regeneration and repair of damaged tissues, especially by acting on specific tissue stem cells, but their features may result as a disadvantage when it is concerned for neoplastic stem cells. Furthermore, hypoxia could also have a potential role in tissue engineering and regenerative medicine due to its capacity to improve the performance of biomaterials. The current review aims to highlight the hypoxic molecular mechanisms reported in different pathological conditions to provide an overview of hypoxia as a therapeutic agent in regenerative and molecular therapy.
Graphical abstract
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Affiliation(s)
- Ylenia Della Rocca
- Department of Innovative Technologies in Medicine & Dentistry, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | - Luigia Fonticoli
- Department of Innovative Technologies in Medicine & Dentistry, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | | | - Oriana Trubiani
- Department of Innovative Technologies in Medicine & Dentistry, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | - Sergio Caputi
- Department of Innovative Technologies in Medicine & Dentistry, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | - Francesca Diomede
- Department of Innovative Technologies in Medicine & Dentistry, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy.
| | - Jacopo Pizzicannella
- Cardiology Intensive Care Unit, "Ss. Annunziata" Hospital, ASL02 Lanciano-Vasto-Chieti, Chieti, Italy
| | - Guya Diletta Marconi
- Department of Medical, Oral and Biotechnological Sciences, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
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10
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Guan N, Kobayashi H, Ishii K, Davidoff O, Sha F, Ikizler TA, Hao CM, Chandel NS, Haase VH. Disruption of mitochondrial complex III in cap mesenchyme but not in ureteric progenitors results in defective nephrogenesis associated with amino acid deficiency. Kidney Int 2022; 102:108-120. [PMID: 35341793 PMCID: PMC9232975 DOI: 10.1016/j.kint.2022.02.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 01/14/2022] [Accepted: 02/16/2022] [Indexed: 11/21/2022]
Abstract
Oxidative metabolism in mitochondria regulates cellular differentiation and gene expression through intermediary metabolites and reactive oxygen species. Its role in kidney development and pathogenesis is not completely understood. Here we inactivated ubiquinone-binding protein QPC, a subunit of mitochondrial complex III, in two types of kidney progenitor cells to investigate the role of mitochondrial electron transport in kidney homeostasis. Inactivation of QPC in sine oculis-related homeobox 2 (SIX2)-expressing cap mesenchyme progenitors, which give rise to podocytes and all nephron segments except collecting ducts, resulted in perinatal death from severe kidney dysplasia. This was characterized by decreased proliferation of SIX2 progenitors and their failure to differentiate into kidney epithelium. QPC inactivation in cap mesenchyme progenitors induced activating transcription factor 4-mediated nutritional stress responses and was associated with a reduction in kidney tricarboxylic acid cycle metabolites and amino acid levels, which negatively impacted purine and pyrimidine synthesis. In contrast, QPC inactivation in ureteric tree epithelial cells, which give rise to the kidney collecting system, did not inhibit ureteric differentiation, and resulted in the development of functional kidneys that were smaller in size. Thus, our data demonstrate that mitochondrial oxidative metabolism is critical for the formation of cap mesenchyme-derived nephron segments but dispensable for formation of the kidney collecting system. Hence, our studies reveal compartment-specific needs for metabolic reprogramming during kidney development.
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Affiliation(s)
- Nan Guan
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Nephrology, Huashan Hospital and Nephrology Research Institute, Fudan University, Shanghai, China; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Hanako Kobayashi
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Ken Ishii
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Olena Davidoff
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Feng Sha
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Talat A Ikizler
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Chuan-Ming Hao
- Division of Nephrology, Huashan Hospital and Nephrology Research Institute, Fudan University, Shanghai, China
| | - Navdeep S Chandel
- Department of Medicine, Feinberg School of Medicine, Northwestern University Chicago, Illinois, USA
| | - Volker H Haase
- Department of Medicine, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tennessee, USA; The Vanderbilt O'Brien Kidney Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Section of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
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11
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Keppner A, Maric D, Orlando IMC, Falquet L, Hummler E, Hoogewijs D. Analysis of the Hypoxic Response in a Mouse Cortical Collecting Duct-Derived Cell Line Suggests That Esrra Is Partially Involved in Hif1α-Mediated Hypoxia-Inducible Gene Expression in mCCD cl1 Cells. Int J Mol Sci 2022; 23:7262. [PMID: 35806266 PMCID: PMC9267015 DOI: 10.3390/ijms23137262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
The kidney is strongly dependent on a continuous oxygen supply, and is conversely highly sensitive to hypoxia. Controlled oxygen gradients are essential for renal control of solutes and urine-concentrating mechanisms, which also depend on various hormones including aldosterone. The cortical collecting duct (CCD) is part of the aldosterone-sensitive distal nephron and possesses a key function in fine-tuned distal salt handling. It is well known that aldosterone is consistently decreased upon hypoxia. Furthermore, a recent study reported a hypoxia-dependent down-regulation of sodium currents within CCD cells. We thus investigated the possibility that cells from the cortical collecting duct are responsive to hypoxia, using the mouse cortical collecting duct cell line mCCDcl1 as a model. By analyzing the hypoxia-dependent transcriptome of mCCDcl1 cells, we found a large number of differentially-expressed genes (3086 in total logFC< −1 or >1) following 24 h of hypoxic conditions (0.2% O2). A gene ontology analysis of the differentially-regulated pathways revealed a strong decrease in oxygen-linked processes such as ATP metabolic functions, oxidative phosphorylation, and cellular and aerobic respiration, while pathways associated with hypoxic responses were robustly increased. The most pronounced regulated genes were confirmed by RT-qPCR. The low expression levels of Epas1 under both normoxic and hypoxic conditions suggest that Hif-1α, rather than Hif-2α, mediates the hypoxic response in mCCDcl1 cells. Accordingly, we generated shRNA-mediated Hif-1α knockdown cells and found Hif-1α to be responsible for the hypoxic induction of established hypoxically-induced genes. Interestingly, we could show that following shRNA-mediated knockdown of Esrra, Hif-1α protein levels were unaffected, but the gene expression levels of Egln3 and Serpine1 were significantly reduced, indicating that Esrra might contribute to the hypoxia-mediated expression of these and possibly other genes. Collectively, mCCDcl1 cells display a broad response to hypoxia and represent an adequate cellular model to study additional factors regulating the response to hypoxia.
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Affiliation(s)
- Anna Keppner
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
| | - Darko Maric
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
| | - Ilaria Maria Christina Orlando
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
| | - Laurent Falquet
- Section of Science, Department of Biology, Faculty of Science and Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland;
| | - Edith Hummler
- Department of Biomedical Sciences, University of Lausanne, CH-1011 Lausanne, Switzerland;
| | - David Hoogewijs
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System (EMC), Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland; (A.K.); (D.M.); (I.M.C.O.)
- National Center of Competence in Research Kidney Control of Homeostasis (NCCR Kidney.CH), University of Zurich, CH-8006 Zürich, Switzerland
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12
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Tiwari R, Kapitsinou PP. Role of Endothelial Prolyl-4-Hydroxylase Domain Protein/Hypoxia-Inducible Factor Axis in Acute Kidney Injury. Nephron Clin Pract 2022; 146:243-248. [PMID: 34515168 PMCID: PMC8885783 DOI: 10.1159/000518632] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/21/2021] [Indexed: 01/03/2023] Open
Abstract
Ischemia reperfusion injury (IRI) results from a cessation or restriction of blood supply to an organ followed by reestablishment of perfusion and reoxygenation. In the kidney, IRI due to transplantation, cardiac surgery with cardiopulmonary bypass, and other major vascular surgeries contributes to acute kidney injury (AKI), a clinical condition associated with significant morbidity and mortality in hospitalized patients. In the postischemic kidney, endothelial damage promotes inflammatory responses and leads to persistent hypoxia of the renal tubular epithelium. Like other cell types, endothelial cells respond to low oxygen tension by multiple hypoxic signaling mechanisms. Key mediators of adaptation to hypoxia are hypoxia-inducible factors (HIF)-1 and -2, transcription factors whose activity is negatively regulated by prolyl-hydroxylase domain proteins 1 to 3 (PHD1 to PHD3). The PHD/HIF axis controls several processes determining injury outcome, including ATP generation, cell survival, proliferation, and angiogenesis. Here, we discuss recent advances in our understanding of the endothelial-derived PHD/HIF signaling and its effects on postischemic AKI.
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Affiliation(s)
- Ratnakar Tiwari
- Department of Medicine and Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Pinelopi P. Kapitsinou
- Department of Medicine and Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL.,Address correspondence and Lead contact: Dr. Pinelopi P. Kapitsinou, Division of Nephrology and Feinberg Cardiovascular and Renal Research Institute, Feinberg School of Medicine, Northwestern University, 303 East Superior Street, SQBRC 8-408, Chicago, IL 60611.
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13
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Dizin E, Olivier V, Roth I, Sassi A, Arnoux G, Ramakrishnan S, Morel S, Kwak BR, Loffing J, Hummler E, Wenger RH, Frew IJ, Feraille E. Activation of the Hypoxia-Inducible Factor Pathway Inhibits Epithelial Sodium Channel-Mediated Sodium Transport in Collecting Duct Principal Cells. J Am Soc Nephrol 2021; 32:3130-3145. [PMID: 34615708 PMCID: PMC8638392 DOI: 10.1681/asn.2021010046] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 08/18/2021] [Accepted: 09/05/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Active sodium reabsorption is the major factor influencing renal oxygen consumption and production of reactive oxygen species (ROS). Increased sodium reabsorption uses more oxygen, which may worsen medullary hypoxia and produce more ROS via enhanced mitochondrial ATP synthesis. Both mechanisms may activate the hypoxia-inducible factor (HIF) pathway. Because the collecting duct is exposed to low oxygen pressure and variations of active sodium transport, we assessed whether the HIF pathway controls epithelial sodium channel (ENaC)-dependent sodium transport. METHODS We investigated HIF's effect on ENaC expression in mpkCCD cl4 cells (a model of collecting duct principal cells) using real-time PCR and western blot and ENaC activity by measuring amiloride-sensitive current. We also assessed the effect of hypoxia and sodium intake on abundance of kidney sodium transporters in wild-type and inducible kidney tubule-specific Hif1α knockout mice. RESULTS In cultured cells, activation of the HIF pathway by dimethyloxalylglycine or hypoxia inhibited sodium transport and decreased expression of β ENaC and γ ENaC, as well as of Na,K-ATPase. HIF1 α silencing increased β ENaC and γ ENaC expression and stimulated sodium transport. A constitutively active mutant of HIF1 α produced the opposite effect. Aldosterone and inhibition of the mitochondrial respiratory chain slowly activated the HIF pathway, suggesting that ROS may also activate HIF. Decreased γ ENaC abundance induced by hypoxia in normal mice was abolished in Hif1α knockout mice. Similarly, Hif1α knockout led to increased γ ENaC abundance under high sodium intake. CONCLUSIONS This study reveals that γ ENaC expression and activity are physiologically controlled by the HIF pathway, which may represent a negative feedback mechanism to preserve oxygenation and/or prevent excessive ROS generation under increased sodium transport.
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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”, Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Grégoire Arnoux
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Suresh Ramakrishnan
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Sandrine Morel
- Department of Pathology and Immunology, University of Geneva, CMU, Geneva, Switzerland
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, CMU, Geneva, Switzerland
| | - Johannes Loffing
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Edith Hummler
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Roland H. Wenger
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Ian J. Frew
- Department of Internal Medicine I, Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine, Medical Centre - University of Freiburg, Freiburg, Germany
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
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14
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Kidney Cancer and Chronic Kidney Disease: Too Close for Comfort. Biomedicines 2021; 9:biomedicines9121761. [PMID: 34944574 PMCID: PMC8699019 DOI: 10.3390/biomedicines9121761] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/18/2021] [Accepted: 11/21/2021] [Indexed: 12/11/2022] Open
Abstract
Kidney cancer and chronic kidney disease are two renal pathologies with very different clinical management strategies and therapeutical options. Nonetheless, the cellular and molecular mechanisms underlying both conditions are closely related. Renal physiology is adapted to operate with a limited oxygen supply, making the kidney remarkably equipped to respond to hypoxia. This tightly regulated response mechanism is at the heart of kidney cancer, leading to the onset of malignant cellular phenotypes. Although elusive, the role of hypoxia in chronic kidney diseases is emerging as related to fibrosis, a pivotal factor in decaying renal function. The present review offers a perspective on the common biological traits shared between kidney cancer and chronic kidney disease and the available and prospective therapies for both conditions.
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15
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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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16
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Mismatch between Tissue Partial Oxygen Pressure and Near-Infrared Spectroscopy Neuromonitoring of Tissue Respiration in Acute Brain Trauma: The Rationale for Implementing a Multimodal Monitoring Strategy. Int J Mol Sci 2021; 22:ijms22031122. [PMID: 33498736 PMCID: PMC7865258 DOI: 10.3390/ijms22031122] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 12/21/2022] Open
Abstract
The brain tissue partial oxygen pressure (PbtO2) and near-infrared spectroscopy (NIRS) neuromonitoring are frequently compared in the management of acute moderate and severe traumatic brain injury patients; however, the relationship between their respective output parameters flows from the complex pathogenesis of tissue respiration after brain trauma. NIRS neuromonitoring overcomes certain limitations related to the heterogeneity of the pathology across the brain that cannot be adequately addressed by local-sample invasive neuromonitoring (e.g., PbtO2 neuromonitoring, microdialysis), and it allows clinicians to assess parameters that cannot otherwise be scanned. The anatomical co-registration of an NIRS signal with axial imaging (e.g., computerized tomography scan) enhances the optical signal, which can be changed by the anatomy of the lesions and the significance of the radiological assessment. These arguments led us to conclude that rather than aiming to substitute PbtO2 with tissue saturation, multiple types of NIRS should be included via multimodal systemic- and neuro-monitoring, whose values then are incorporated into biosignatures linked to patient status and prognosis. Discussion on the abnormalities in tissue respiration due to brain trauma and how they affect the PbtO2 and NIRS neuromonitoring is given.
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17
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Cantow K, Evans RG, Grosenick D, Gladytz T, Niendorf T, Flemming B, Seeliger E. Quantitative Assessment of Renal Perfusion and Oxygenation by Invasive Probes: Basic Concepts. Methods Mol Biol 2021; 2216:89-107. [PMID: 33475996 PMCID: PMC9703258 DOI: 10.1007/978-1-0716-0978-1_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe basic principles of methodology to quantify renal hemodynamics and tissue oxygenation by means of invasive probes in experimental animals. Advantages and disadvantages of the various methods are discussed in the context of the heterogeneity of renal tissue perfusion and oxygenation.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by a separate chapter describing the experimental procedure and data analysis.
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Affiliation(s)
- Kathleen Cantow
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Dirk Grosenick
- Physikalisch-Technische Bundesanstalt (German Federal Metrologic Institute), Berlin, Germany
| | - Thomas Gladytz
- Physikalisch-Technische Bundesanstalt (German Federal Metrologic Institute), Berlin, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association, Berlin, Germany
| | - Bert Flemming
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Erdmann Seeliger
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany.
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18
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Cantow K, Ladwig-Wiegard M, Flemming B, Fekete A, Hosszu A, Seeliger E. Reversible (Patho)Physiologically Relevant Test Interventions: Rationale and Examples. Methods Mol Biol 2021; 2216:57-73. [PMID: 33475994 DOI: 10.1007/978-1-0716-0978-1_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe test interventions that are used to study the control of renal hemodynamics and oxygenation in experimental animals in the context of kidney-specific control of hemodynamics and oxygenation. The rationale behind the use of the individual tests, the physiological responses of renal hemodynamics and oxygenation, the use in preclinical studies, and the possible application in humans are discussed.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.
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Affiliation(s)
- Kathleen Cantow
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Mechthild Ladwig-Wiegard
- Institute of Animal Welfare, Animal Behavior and Laboratory Animal Science, Free University Berlin, Berlin, Germany
| | - Bert Flemming
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Andrea Fekete
- 1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Adam Hosszu
- 1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Erdmann Seeliger
- Working Group Integrative Kidney Physiology, Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany.
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19
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Pan SY, Chiang WC, Chen YM. The journey from erythropoietin to 2019 Nobel Prize: Focus on hypoxia-inducible factors in the kidney. J Formos Med Assoc 2021; 120:60-67. [DOI: 10.1016/j.jfma.2020.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/02/2020] [Accepted: 06/04/2020] [Indexed: 12/19/2022] Open
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20
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Chin K, Cazorla-Bak MP, Liu E, Nghiem L, Zhang Y, Yu J, Wilson DF, Vinogradov SA, Gilbert RE, Connelly KA, Evans RG, Baker AJ, David Mazer C, Hare GMT. Renal microvascular oxygen tension during hyperoxia and acute hemodilution assessed by phosphorescence quenching and excitation with blue and red light. Can J Anaesth 2020; 68:214-225. [PMID: 33174162 DOI: 10.1007/s12630-020-01848-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/05/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The kidney plays a central physiologic role as an oxygen sensor. Nevertheless, the direct mechanism by which this occurs is incompletely understood. We measured renal microvascular partial pressure of oxygen (PkO2) to determine the impact of clinically relevant conditions that acutely change PkO2 including hyperoxia and hemodilution. METHODS We utilized two-wavelength excitation (red and blue spectrum) of the intravascular phosphorescent oxygen sensitive probe Oxyphor PdG4 to measure renal tissue PO2 in anesthetized rats (2% isoflurane, n = 6) under two conditions of altered arterial blood oxygen content (CaO2): 1) hyperoxia (fractional inspired oxygen 21%, 30%, and 50%) and 2) acute hemodilutional anemia (baseline, 25% and 50% acute hemodilution). The mean arterial blood pressure (MAP), rectal temperature, arterial blood gases (ABGs), and chemistry (radiometer) were measured under each condition. Blue and red light enabled measurement of PkO2 in the superficial renal cortex and deeper cortical and medullary tissue, respectively. RESULTS PkO2 was higher in the superficial renal cortex (~ 60 mmHg, blue light) relative to the deeper renal cortex and outer medulla (~ 45 mmHg, red light). Hyperoxia resulted in a proportional increase in PkO2 values while hemodilution decreased microvascular PkO2 in a linear manner in both superficial and deeper regions of the kidney. In both cases (blue and red light), PkO2 correlated with CaO2 but not with MAP. CONCLUSION The observed linear relationship between CaO2 and PkO2 shows the biological function of the kidney as a quantitative sensor of anemic hypoxia and hyperoxia. A better understanding of the impact of changes in PkO2 may inform clinical practices to improve renal oxygen delivery and prevent acute kidney injury.
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Affiliation(s)
- Kyle Chin
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Melina P Cazorla-Bak
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Elaine Liu
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Linda Nghiem
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Yanling Zhang
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Julie Yu
- Deaprtment of Anesthesia and Perioperative Medicine, Western University, London, ON, Canada
| | - David F Wilson
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Richard E Gilbert
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Division of Endocrinology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Kim A Connelly
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Division of Cardiology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Andrew J Baker
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - C David Mazer
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Gregory M T Hare
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada. .,Department of Physiology, University of Toronto, Toronto, ON, Canada. .,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.
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21
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Zou J, Yang J, Zhu X, Zhong J, Elshaer A, Matsusaka T, Pastan I, Haase VH, Yang HC, Fogo AB. Stabilization of hypoxia-inducible factor ameliorates glomerular injury sensitization after tubulointerstitial injury. Kidney Int 2020; 99:620-631. [PMID: 33137336 DOI: 10.1016/j.kint.2020.09.031] [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: 09/04/2019] [Revised: 09/14/2020] [Accepted: 09/17/2020] [Indexed: 12/24/2022]
Abstract
Previously, we found that mild tubulointerstitial injury sensitizes glomeruli to subsequent injury. Here, we evaluated whether stabilization of hypoxia-inducible factor-α (HIF-α), a key regulator of tissue response to hypoxia, ameliorates tubulointerstitial injury and impact on subsequent glomerular injury. Nep25 mice, which express the human CD25 receptor on podocytes under control of the nephrin promotor and develop glomerulosclerosis when a specific toxin is administered were used. Tubulointerstitial injury, evident by week two, was induced by folic acid, and mice were treated with an HIF stabilizer, dimethyloxalylglycine or vehicle from week three to six. Uninephrectomy at week six assessed tubulointerstitial fibrosis. Glomerular injury was induced by podocyte toxin at week seven, and mice were sacrificed ten days later. At week six tubular injury markers normalized but with patchy collagen I and interstitial fibrosis. Pimonidazole staining, a hypoxia marker, was increased by folic acid treatment compared to vehicle while dimethyloxalylglycine stimulated HIF-2α expression and attenuated tubulointerstitial hypoxia. The hematocrit was increased by dimethyloxalylglycine along with downstream effectors of HIF. Tubular epithelial cell injury, inflammation and interstitial fibrosis were improved after dimethyloxalylglycine, with further reduced mortality, interstitial fibrosis, and glomerulosclerosis induced by specific podocyte injury. Thus, our findings indicate that hypoxia contributes to tubular injury and consequent sensitization of glomeruli to injury. Hence, restoring HIFs may blunt this adverse crosstalk of tubules to glomeruli.
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Affiliation(s)
- Jun Zou
- Division of Nephrology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jaewon Yang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Nephrology, Yonsei University Wonju College of Medicine, Wonju, Gangwon, South Korea
| | - Xiaoye Zhu
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Nephrology, Huashan Hospital, Wudan University, Shanghai, China
| | - Jianyong Zhong
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ahmed Elshaer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Taiji Matsusaka
- Institute of Medical Science, Tokai University, Isehara, Japan
| | - Ira Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Volker H Haase
- Departments of Medicine, Cancer Biology, and Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Medicine and Research Services, Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
| | - Hai-Chun Yang
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Agnes B Fogo
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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22
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Abstract
A gradually developing reduction in renal blood flow from atherosclerotic renovascular disease results in loss of kidney volume and a decrease in glomerular filtration rate that eventually becomes irreversible. Whether this process fundamentally reflects tissue hypoxia has been difficult to establish. Studies of human renovascular disease have indicated that reductions in blood flow of up to 30% to 40% can be tolerated with preservation of normal oxygenation and structural integrity. These observations are consistent with remarkable stability of poststenotic kidney function during sustained medical antihypertensive drug therapy in moderate renovascular disease. With more severe and sustained reductions, however, cortical oxygenation decreases and the magnitude of medullary hypoxia expands. These changes are associated with increasing renal venous levels of inflammatory cytokines, angiogenic markers, and infiltration of inflammatory cells, including tissue macrophages and T cells. Although restoring large-vessel blood flow can improve oxygenation, some of these processes reflect microvascular rarefication, remain activated, and do not depend on hemodynamic factors alone. Elucidation of tissue injury pathways associated with hypoxia opens the possibility of adjunctive therapeutic measures beyond renal revascularization. These include cell-based regeneration, mitochondrial protection, and/or angiogenic cytokine therapy to restore or preserve renal function in ischemic nephropathy.
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Affiliation(s)
- Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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23
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Monitoring with In Vivo Electrochemical Sensors: Navigating the Complexities of Blood and Tissue Reactivity. SENSORS 2020; 20:s20113149. [PMID: 32498360 PMCID: PMC7308849 DOI: 10.3390/s20113149] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 12/18/2022]
Abstract
The disruptive action of an acute or critical illness is frequently manifest through rapid biochemical changes that may require continuous monitoring. Within these changes, resides trend information of predictive value, including responsiveness to therapy. In contrast to physical variables, biochemical parameters monitored on a continuous basis are a largely untapped resource because of the lack of clinically usable monitoring systems. This is despite the huge testing repertoire opening up in recent years in relation to discrete biochemical measurements. Electrochemical sensors offer one of the few routes to obtaining continuous readout and, moreover, as implantable devices information referable to specific tissue locations. This review focuses on new biological insights that have been secured through in vivo electrochemical sensors. In addition, the challenges of operating in a reactive, biological, sample matrix are highlighted. Specific attention is given to the choreographed host rejection response, as evidenced in blood and tissue, and how this limits both sensor life time and reliability of operation. Examples will be based around ion, O2, glucose, and lactate sensors, because of the fundamental importance of this group to acute health care.
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24
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Gnahoré GT, Kelly JL, O'Riordan SL, Bolger FB, Doran MM, Sands M, Lowry JP. Development and validation of a real-time microelectrochemical sensor for clinical monitoring of tissue oxygenation/perfusion. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:2453-2459. [PMID: 32930234 DOI: 10.1039/d0ay00206b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Oxygen is of critical importance to tissue viability and there is increasing demand for its reliable real-time clinical monitoring in order to prevent, diagnose, and treat several pathological disorders, including hypoxia, stroke and reperfusion injury. Herein we report the development and characterisation of a prototype clinical O2 sensor, and its validation in vivo, including proof-of-concept monitoring in patients undergoing surgery for carpal tunnel release. An integrated platinum-based microelectrochemical device was custom designed and controlled using a miniaturised telemetry-operated single channel clinical potentiostat. The in vitro performance of different sensor configurations is presented, with the best sensor design (S2) displaying appropriate linearity (R2 = 0.994) and sensitivity (0.569 ± 0.022 nA μM-1). Pre-clinical validation of S2 was performed in the hind limb muscle of anaesthetised rats; tourniquet application resulted in a significant rapid decrease in signal (90 ± 27%, [ΔO2] ca. 140 ± 18 μM), with a return to baseline within a period of ca. 3 min following tourniquet release. Similar trends were observed in the clinical study; an immediate decrease in signal (39 ± 3%, [ΔO2] ca. 30 ± 20 μM), with basal levels re-established within 2 min of tourniquet release. These results confirm that continuous real-time monitoring of dynamic changes in tissue O2 can serve as an indicator of reperfusion status in patients undergoing carpal tunnel surgery, and suggests the potential usefulness of the developed microelectrochemical sensor for other medical conditions where clinical monitoring of O2 and perfusion is important.
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Affiliation(s)
- Gama Theophile Gnahoré
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
| | - Jack L Kelly
- Department of Plastic and Reconstructive Surgery, Galway University Hospitals, Galway, Ireland
| | - Saidhbhe L O'Riordan
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
| | - Fiachra B Bolger
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
| | - Michelle M Doran
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
| | - Michelle Sands
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
| | - John P Lowry
- Maynooth University Department of Chemistry, The Kathleen Lonsdale Institute for Human Health Research, Maynooth, Co. Kildare, Ireland.
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25
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Abrahamson JR, Read A, Chin K, Mistry N, Joo H, Desjardins JF, Liu E, Thai K, Wilson DF, Vinogradov SA, Maynes JT, Gilbert RE, Connelly KA, Baker AJ, Mazer CD, Hare GMT. Renal tissue Po2sensing during acute hemodilution is dependent on the diluent. Am J Physiol Regul Integr Comp Physiol 2020; 318:R799-R812. [DOI: 10.1152/ajpregu.00323.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Sensing changes in blood oxygen content ([Formula: see text]) is an important physiological role of the kidney; however, the mechanism(s) by which the kidneys sense and respond to changes in [Formula: see text] are incompletely understood. Accurate measurements of kidney tissue oxygen tension ([Formula: see text]) may increase our understanding of renal oxygen-sensing mechanisms and could inform decisions regarding the optimal fluid for intravascular volume resuscitation to maintain renal perfusion. In some clinical settings, starch solution may be nephrotoxic, possibly due to inadequacy of tissue oxygen delivery. We hypothesized that hemodilution with starch colloid solutions would reduce [Formula: see text] to a more severe degree than other diluents. Anesthetized Sprague-Dawley rats ( n = 77) were randomized to undergo hemodilution with either colloid (6% hydroxyethyl starch or 5% albumin), crystalloid (0.9% saline), or a sham procedure (control) ( n = 13–18 rats/group). Data were analyzed by ANOVA with significance assigned at P < 0.05. After hemodilution, mean arterial pressure (MAP) decreased marginally in all groups, while hemoglobin (Hb) and [Formula: see text] decreased in proportion to the degree of hemodilution. Cardiac output was maintained in all groups after hemodilution. [Formula: see text] decreased in proportion to the reduction in Hb in all treatment groups. At comparably reduced Hb, and maintained arterial oxygen values, hemodilution with starch resulted in larger decreases in [Formula: see text] relative to animals hemodiluted with albumin or saline ( P < 0.008). Renal medullary erythropoietin (EPO) mRNA levels increased more prominently, relative to other hypoxia-regulated molecules (GLUT-1, GAPDH, and VEGF). Our data demonstrate that the kidney acts as a biosensor of reduced [Formula: see text] following hemodilution and that [Formula: see text] may provide a quantitative signal for renal cellular responsiveness to acute anemia. Evidence of a more severe reduction in [Formula: see text] following hemodilution with starch colloid solution suggests that tissue hypoxia may contribute to starch induced renal toxicity.
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Affiliation(s)
- Jessica R. Abrahamson
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Austin Read
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Kyle Chin
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Nikhil Mistry
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Ontario, Canada
| | - Hannah Joo
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Jean-Francois Desjardins
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Elaine Liu
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Kerri Thai
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - David F. Wilson
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sergei A. Vinogradov
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason T. Maynes
- Department of Anesthesia and Pain Medicine, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Richard E. Gilbert
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Department of Medicine, Division of Endocrinology, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Kim A. Connelly
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Department of Medicine, Division of Cardiology, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Andrew J. Baker
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Ontario, Canada
| | - C. David Mazer
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Ontario, Canada
| | - Gregory M. T. Hare
- Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
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Lamby P, Krüger-Genge A, Franke RP, Mrowietz C, Falter J, Graf S, Schellenberg EL, Jung F, Prantl L. Effect of iodinated contrast media on the oxygen tension in the renal cortico-medullary region of pigs. Clin Hemorheol Microcirc 2020; 73:261-270. [PMID: 31322554 DOI: 10.3233/ch-199009] [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] [Indexed: 11/15/2022]
Abstract
Repeated injections of iodinated contrast media (CM) can lead to a deterioration of the renal blood flow, can redistribute blood from the renal cortex to other parts of the kidney and can cause small decreases of the blood flow in cortical capillaries, a significant reduction in blood flow in peritubular capillaries and a significant reduction in blood flow in the vasa recta. Therefore, a study in pigs was designed, to show whether the repeated injection of CM boli, alone, can cause a reduction of oxygenation in the cortico-medullar renal tissue - the region with the highest oxygen demand in the kidney - of pigs.While the mean pO2-value had only decreased by 0.3 mmHg from 29.9±4.3 mmHg to 29.6±4.3 mmHg (p = 0.8799) after the tenth Iodixanol bolus, it decreased by 5.9 mmHg from 34.0±4.3 mmHg to 28.1±4.3 mmHg after the tenth Iopromide bolus (p = 0.044). This revealed a remarkable difference in the influence of these CM on the oxygen partial pressure in the kidney.Repeated applications of CM had a significant influence on the renal oxygen partial pressure. In line with earlier studies showing a redistribution of blood from the cortex to other renal areas, this study revealed that Iodixanol - in contrast to Iopromide - induced no changes in the pO2 in the cortico-medullar region which confirms that Iodixanol did not hinder the flow of blood through the renal micro-vessels. These results are in favor of a hypothesis from Brezis that a microcirculatory disorder might be the basis for the development of CI-AKI.
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Affiliation(s)
- P Lamby
- Department of Plastic and Hand Surgery, University Hospital Regensburg, Germany
| | - A Krüger-Genge
- Department of Anaesthesia, Pain Management and Perioperative Medicine, Faculty of Medicine, Dalhousie University, Halifax, Canada
| | - R P Franke
- Central Institute for Biomedical Engineering, Department of Biomaterials, University of Ulm, Ulm, Germany
| | - C Mrowietz
- Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour and Virtual Center for Replacement - Complementary Methods to Animal Testing, University of Veterinary Medicine Hannover, Hannover, Germany
| | - J Falter
- Department of Plastic and Hand Surgery, University Hospital Regensburg, Germany
| | - S Graf
- Department of Plastic and Hand Surgery, University Hospital Regensburg, Germany
| | - E L Schellenberg
- Department of Anesthesiology, University Hospital Regensburg, Germany
| | - F Jung
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany
| | - L Prantl
- Department of Plastic and Hand Surgery, University Hospital Regensburg, Germany
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27
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Yu PK, An D, Balaratnasingam C, Cringle SJ, Yu DY. Topographic Distribution of Contractile Protein in the Human Macular Microvasculature. Invest Ophthalmol Vis Sci 2020; 60:4574-4582. [PMID: 31675074 DOI: 10.1167/iovs.19-26986] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We studied the topographic distribution of contractile protein in different orders of the human macular microvasculature to further understanding of the sites for capillary blood flow regulation. Methods Nine donor eyes from eight donors were cannulated at the central retinal artery and perfusion labeled for alpha smooth muscle actin (αSMA) and filamentous actin (F-actin). Confocal images were collected from the macula region, viewed, projected, and converted to a 255 grayscale for measurements. The mean intensity was measured for macular arterioles, venules, and capillary segments. The diameter of each vessel segment measured was recorded. The normalized mean intensity values from all images were ranked according to vessel types and size with a total of nine categories. Results F-actin was present throughout the macular microvasculature whereas αSMA labeling showed variations. Overall, αSMA has a more prominent presence in the macular arterioles than in the macular capillaries and venules, and αSMA strongly labeled the smaller macular arterioles. Some capillaries also labeled positive for αSMA, including some of the capillaries in the innermost capillary ring surrounding the foveola. It was weakly present in the capillaries on the venous side and larger venules. In the larger macular arterioles closer to 100 μm in diameter, αSMA labeling was weakly present and not as ubiquitous as in the smaller arterioles. Conclusions Nonuniform distribution of contractile proteins in the different types, orders, and sizes of macular microvasculature indicates that these vessels may have different contractile capability and roles in macular flow regulation.
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Affiliation(s)
- Paula K Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.,Lions Eye Institute, the University of Western Australia, Perth, Australia
| | - Dong An
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.,Lions Eye Institute, the University of Western Australia, Perth, Australia
| | - Chandrakumar Balaratnasingam
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.,Lions Eye Institute, the University of Western Australia, Perth, Australia
| | - Stephen J Cringle
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.,Lions Eye Institute, the University of Western Australia, Perth, Australia
| | - Dao-Yi Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Australia.,Lions Eye Institute, the University of Western Australia, Perth, Australia
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28
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Edwards A, Palm F, Layton AT. A model of mitochondrial O 2 consumption and ATP generation in rat proximal tubule cells. Am J Physiol Renal Physiol 2020; 318:F248-F259. [PMID: 31790302 PMCID: PMC6985826 DOI: 10.1152/ajprenal.00330.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/18/2019] [Accepted: 11/25/2019] [Indexed: 11/22/2022] Open
Abstract
Oxygen tension in the kidney is mostly determined by O2 consumption (Qo2), which is, in turn, closely linked to tubular Na+ reabsorption. The objective of the present study was to develop a model of mitochondrial function in the proximal tubule (PT) cells of the rat renal cortex to gain more insight into the coupling between Qo2, ATP formation (GATP), ATP hydrolysis (QATP), and Na+ transport in the PT. The present model correctly predicts in vitro and in vivo measurements of Qo2, GATP, and ATP and Pi concentrations in PT cells. Our simulations suggest that O2 levels are not rate limiting in the proximal convoluted tubule, absent large metabolic perturbations. The model predicts that the rate of ATP hydrolysis and cytoplasmic pH each substantially regulate the GATP-to-Qo2 ratio, a key determinant of the number of Na+ moles actively reabsorbed per mole of O2 consumed. An isolated increase in QATP or in cytoplasmic pH raises the GATP-to-Qo2 ratio. Thus, variations in Na+ reabsorption and pH along the PT may, per se, generate axial heterogeneities in the efficiency of mitochondrial metabolism and Na+ transport. Our results also indicate that the GATP-to-Qo2 ratio is strongly impacted not only by H+ leak permeability, which reflects mitochondrial uncoupling, but also by K+ leak pathways. Simulations suggest that the negative impact of increased uncoupling in the diabetic kidney on mitochondrial metabolic efficiency is partly counterbalanced by increased rates of Na+ transport and ATP consumption. This model provides a framework to investigate the role of mitochondrial dysfunction in acute and chronic renal diseases.
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Affiliation(s)
- Aurélie Edwards
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Anita T Layton
- Departments of Mathematics, Biomedical Engineering, and Medicine, Duke University, Durham, North Carolina
- Departments of Applied Mathematics and Biology, School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
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29
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Aubert V, Kaminski J, Guillaud F, Hauet T, Hannaert P. A Computer Model of Oxygen Dynamics in the Cortex of the Rat Kidney at the Cell-Tissue Level. Int J Mol Sci 2019; 20:E6246. [PMID: 31835730 PMCID: PMC6941061 DOI: 10.3390/ijms20246246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 02/06/2023] Open
Abstract
The renal cortex drives renal function. Hypoxia/reoxygenation are primary factors in ischemia-reperfusion (IR) injuries, but renal oxygenation per se is complex and awaits full elucidation. Few mathematical models address this issue: none captures cortical tissue heterogeneity. Using agent-based modeling, we develop the first model of cortical oxygenation at the cell-tissue level (RCM), based on first principles and careful bibliographical analysis. Entirely parameterized with Rat data, RCM is a morphometrically equivalent 2D-slice of cortical tissue, featuring peritubular capillaries (PTC), tubules and interstitium. It implements hemoglobin/O2 binding-release, oxygen diffusion, and consumption, as well as capillary and tubular flows. Inputs are renal blood flow RBF and PO2 feeds; output is average tissue PO2 (tPO2). After verification and sensitivity analysis, RCM was validated at steady-state (tPO2 37.7 ± 2.2 vs. 36.9 ± 6 mmHg) and under transients (ischemic oxygen half-time: 4.5 ± 2.5 vs. 2.3 ± 0.5 s in situ). Simulations confirm that PO2 is largely independent of RBF, except at low values. They suggest that, at least in the proximal tubule, the luminal flow dominantly contributes to oxygen delivery, while the contribution of capillaries increases under partial ischemia. Before addressing IR-induced injuries, upcoming developments include ATP production, adaptation to minutes-hours scale, and segmental and regional specification.
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Affiliation(s)
| | | | | | | | - Patrick Hannaert
- INSERM U1082-IRTOMIT, 86000 Poitiers, France; (V.A.); (J.K.); (F.G.); (T.H.)
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30
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Abstract
Contrast nephropathy (CN) is acute kidney injury (AKI) that occurs within 24 to 72 hours of iodinated contrast medium (ICM) administration. Mechanisms of CN include hyperviscosity, free radical formation, and renal medullary oxygen supply/demand mismatch. Although risk factors for CN have been identified, it remains uncertain whether ICM causes or is simply associated with AKI. The cornerstones of CN prevention are using low-osmolal ICM, intravenous hydration, and statins, especially in patients with chronic kidney disease. With appropriate CN risk mitigation, coronary angiography and intervention should not be routinely withheld from patients with acute coronary syndromes.
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Affiliation(s)
- James E Novak
- Division of Nephrology, Henry Ford Hospital, Wayne State University, CFP-505, 2799 West Grand Boulevard, Detroit, MI 48202, USA.
| | - Richa Handa
- Division of Nephrology, Henry Ford Hospital, CFP-506, 2799 West Grand Boulevard, Detroit, MI 48202, USA
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31
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Abumoawad A, Saad A, Ferguson CM, Eirin A, Woollard JR, Herrmann SM, Hickson LJ, Bendel EC, Misra S, Glockner J, Lerman LO, Textor SC. Tissue hypoxia, inflammation, and loss of glomerular filtration rate in human atherosclerotic renovascular disease. Kidney Int 2019; 95:948-957. [PMID: 30904069 PMCID: PMC6738340 DOI: 10.1016/j.kint.2018.11.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/15/2018] [Accepted: 11/29/2018] [Indexed: 12/18/2022]
Abstract
The relationships between renal blood flow (RBF), tissue oxygenation, and inflammatory injury in atherosclerotic renovascular disease (ARVD) are poorly understood. We sought to correlate RBF and tissue hypoxia with glomerular filtration rate (GFR) in 48 kidneys from patients with ARVD stratified by single kidney iothalamate GFR (sGFR). Oxygenation was assessed by blood oxygenation level dependent magnetic resonance imaging (BOLD MRI), which provides an index for the levels of deoxyhemoglobin within a defined volume of tissue (R2*). sGFR correlated with RBF and with the severity of vascular stenosis as estimated by duplex velocities. Higher cortical R2* and fractional hypoxia and higher levels of renal vein neutrophil-gelatinase-associated-lipocalin (NGAL) and monocyte-chemoattractant protein-1 (MCP-1) were observed at lower GFR, with an abrupt inflection below 20 ml/min. Renal vein MCP-1 levels correlated with cortical R2* and with fractional hypoxia. Correlations between cortical R2* and RBF in the highest sGFR stratum (mean sGFR 51 ± 12 ml/min; R = -0.8) were degraded in the lowest sGFR stratum (mean sGFR 8 ± 3 ml/min; R = -0.1). Changes in fractional hypoxia after furosemide were also absent in the lowest sGFR stratum. These data demonstrate relative stability of renal oxygenation with moderate reductions in RBF and GFR but identify a transition to overt hypoxia and inflammatory cytokine release with severely reduced GFR. Tissue oxygenation and RBF were less correlated in the setting of reduced sGFR, consistent with variable oxygen consumption or a shift to alternative mechanisms of tissue injury. Identifying transitions in tissue oxygenation may facilitate targeted therapy in ARVD.
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Affiliation(s)
| | - Ahmed Saad
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA; Department of Family Medicine, Creighton University, Omaha, Nebraska, USA
| | | | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - John R Woollard
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - LaTonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Emily C Bendel
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sanjay Misra
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - James Glockner
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.
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32
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Retinal capillary perfusion: Spatial and temporal heterogeneity. Prog Retin Eye Res 2019; 70:23-54. [PMID: 30769149 DOI: 10.1016/j.preteyeres.2019.01.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/18/2019] [Accepted: 01/19/2019] [Indexed: 01/17/2023]
Abstract
The central role of the cardiovascular system is to maintain adequate capillary perfusion. The spatially and temporally heterogeneous nature of capillary perfusion has been reported in some organs. However, such heterogeneous perfusion properties have not been sufficiently explored in the retina. Arguably, spatial and temporal heterogeneity of capillary perfusion could be more predominant in the retina than that in other organs. This is because the retina is one of the highest metabolic demand neural tissues yet it has a limited blood supply due to optical requirements. In addition, the unique heterogeneous distribution of retinal neural cells within different layers and regions, and the significant heterogeneity of intraretinal oxygen distribution and consumption add to the complexity. Retinal blood flow distribution must match consumption of nutrients such as oxygen and glucose within the retina at the cellular level in order to effectively maintain cell survival and function. Sophisticated local blood flow control in the microcirculation is likely required to control the retinal capillary perfusion to supply local retinal tissue and accommodate temporal and spatial variations in metabolic supply and demand. The authors would like to update the knowledge of the retinal microvessel and capillary network and retinal oxidative metabolism from their own studies and the work of others. The coupling between blood supply and energy demands in the retina is particularly interesting. We will mostly describe information regarding the retinal microvessel network and retinal oxidative metabolism relevant to the spatial and temporal heterogeneity of capillary perfusion. We believe that there is significant and necessary spatial and temporal heterogeneity and active regulation of retinal blood flow in the retina, particularly in the macular region. Recently, retinal optical coherence tomography angiography (OCTA) has been widely used in ophthalmology, both experimentally and clinically. OCTA could be a valuable tool for examining retinal microvessel and capillary network structurally and has potential for determining retinal capillary perfusion and its control. We have demonstrated spatial and temporal heterogeneity of capillary perfusion in the retina both experimentally and clinically. We have also found close relationships between the smallest arterioles and capillaries within paired arterioles and venules and determined the distribution of smooth muscle cell contraction proteins in these vessels. Spatial and temporal heterogeneity of retinal capillary perfusion could be a useful parameter to determine retinal microvessel regulatory capability as an early assay for retinal vascular diseases. This topic will be of great interest, not only for the eye but also other organs. The retina could be the best model for such investigations. Unlike cerebral vessels, retinal vessels can be seen even at the capillary level. The purpose of this manuscript is to share our current understanding with the readers and encourage more researchers and clinicians to investigate this field. We begin by reviewing the general principles of microcirculation properties and the spatial and temporal heterogeneity of the capillary perfusion in other organs, before considering the special requirements of the retina. The local heterogeneity of oxygen supply and demand in the retina and the need to have a limited and well-regulated retinal circulation to preserve the transparency of the retina is discussed. We then consider how such a delicate balance of metabolic supply and consumption is achieved. Finally we discuss how new imaging methodologies such as optical coherence tomography angiography may be able to detect the presence of spatial and temporal heterogeneity of capillary perfusion in a clinical setting. We also provide some new information of the control role of very small arterioles in the modulation of retinal capillary perfusion which could be an interesting topic for further investigation.
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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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34
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Vio CP, Salas D, Cespedes C, Diaz-Elizondo J, Mendez N, Alcayaga J, Iturriaga R. Imbalance in Renal Vasoactive Enzymes Induced by Mild Hypoxia: Angiotensin-Converting Enzyme Increases While Neutral Endopeptidase Decreases. Front Physiol 2018; 9:1791. [PMID: 30618804 PMCID: PMC6297360 DOI: 10.3389/fphys.2018.01791] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/28/2018] [Indexed: 12/17/2022] Open
Abstract
Chronic hypoxia has been postulated as one of the mechanisms involved in salt-sensitive hypertension and chronic kidney disease (CKD). Kidneys have a critical role in the regulation of arterial blood pressure through vasoactive systems, such as the renin-angiotensin and the kallikrein-kinin systems, with the angiotensin-converting enzyme (ACE) and kallikrein being two of the main enzymes that produce angiotensin II and bradykinin, respectively. Neutral endopeptidase 24.11 or neprilysin is another enzyme that among its functions degrade vasoactive peptides including angiotensin II and bradykinin, and generate angiotensin 1-7. On the other hand, the kidneys are vulnerable to hypoxic injury due to the active electrolyte transportation that requires a high oxygen consumption; however, the oxygen supply is limited in the medullary regions for anatomical reasons. With the hypothesis that the chronic reduction of oxygen under normobaric conditions would impact renal vasoactive enzyme components and, therefore; alter the normal balance of the vasoactive systems, we exposed male Sprague-Dawley rats to normobaric hypoxia (10% O2) for 2 weeks. We then processed renal tissue to identify the expression and distribution of kallikrein, ACE and neutral endopeptidase 24.11 as well as markers of kidney damage. We found that chronic hypoxia produced focal damage in the kidney, mainly in the cortico-medullary region, and increased the expression of osteopontin. Moreover, we observed an increase of ACE protein in the brush border of proximal tubules at the outer medullary region, with increased mRNA levels. Kallikrein abundance did not change significantly with hypoxia, but a tendency toward reduction was observed at protein and mRNA levels. Neutral endopeptidase 24.11 was localized in proximal tubules, and was abundantly expressed under normoxic conditions, which markedly decreased both at protein and mRNA levels with chronic hypoxia. Taken together, our results suggest that chronic hypoxia produces focal kidney damage along with an imbalance of key components of the renal vasoactive system, which could be the initial steps for a long-term contribution to salt-sensitive hypertension and CKD.
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Affiliation(s)
- Carlos P Vio
- Department of Physiology, Center for Aging and Regeneration CARE UC, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
| | - Daniela Salas
- Department of Physiology, Center for Aging and Regeneration CARE UC, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Cespedes
- Department of Physiology, Center for Aging and Regeneration CARE UC, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jessica Diaz-Elizondo
- Department of Physiology, Center for Aging and Regeneration CARE UC, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Natalia Mendez
- Department of Physiology, Center for Aging and Regeneration CARE UC, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Institute of Anatomy, Histology, and Pathology, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Department of Physiology, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Abstract
Tubular injury sensitizes glomeruli to injury. We review potential mechanisms of this tubuloglomerular cross talk. In the same nephron, tubular injury can cause stenosis of the glomerulotubular junction and finally result in atubular glomeruli. Tubular injury also affects glomerular filtration function through tubuloglomerular feedback. Progenitor cells, that is, parietal epithelial cells and renin positive cells, can be involved in repair of injured glomeruli and also may be modulated by tubular injury. Loss of nephrons induces additional workload and stress on remaining nephrons. Hypoxia and activation of the renin-angiotensin-aldosterone system induced by tubular injury also modulate tubuloglomerular cross talk. Therefore, effective therapies in chronic kidney disease may need to aim to interrupt this deleterious tubuloglomerular cross talk.
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Affiliation(s)
- Jiayi Wang
- 1 Division of Nephrology, Second Xiangya Hospital, Central South University, Changsha, China.,2 Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jianyong Zhong
- 2 Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,3 Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hai-Chun Yang
- 2 Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,3 Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Agnes B Fogo
- 2 Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,3 Division of Pediatric Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Ow CPC, Ngo JP, Ullah MM, Barsha G, Meex RC, Watt MJ, Hilliard LM, Koeners MP, Evans RG. Absence of renal hypoxia in the subacute phase of severe renal ischemia-reperfusion injury. Am J Physiol Renal Physiol 2018; 315:F1358-F1369. [PMID: 30110566 PMCID: PMC6293301 DOI: 10.1152/ajprenal.00249.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Tissue hypoxia has been proposed as an important event in renal ischemia-reperfusion injury (IRI), particularly during the period of ischemia and in the immediate hours following reperfusion. However, little is known about renal oxygenation during the subacute phase of IRI. We employed four different methods to assess the temporal and spatial changes in tissue oxygenation during the subacute phase (24 h and 5 days after reperfusion) of a severe form of renal IRI in rats. We hypothesized that the kidney is hypoxic 24 h and 5 days after an hour of bilateral renal ischemia, driven by a disturbed balance between renal oxygen delivery (Do2) and oxygen consumption (V̇o2). Renal Do2 was not significantly reduced in the subacute phase of IRI. In contrast, renal V̇o2 was 55% less 24 h after reperfusion and 49% less 5 days after reperfusion than after sham ischemia. Inner medullary tissue Po2, measured by radiotelemetry, was 25 ± 12% (mean ± SE) greater 24 h after ischemia than after sham ischemia. By 5 days after reperfusion, tissue Po2 was similar to that in rats subjected to sham ischemia. Tissue Po2 measured by Clark electrode was consistently greater 24 h, but not 5 days, after ischemia than after sham ischemia. Cellular hypoxia, assessed by pimonidazole adduct immunohistochemistry, was largely absent at both time points, and tissue levels of hypoxia-inducible factors were downregulated following renal ischemia. Thus, in this model of severe IRI, tissue hypoxia does not appear to be an obligatory event during the subacute phase, likely because of the markedly reduced oxygen consumption.
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Affiliation(s)
- Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Jennifer P Ngo
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Md Mahbub Ullah
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Giannie Barsha
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Ruth C Meex
- Department of Human Biology, NUTRIM School of Nutritional and Translational Research in Metabolism, Maastricht University Medical Centre , Maastricht , The Netherlands
| | - Matthew J Watt
- Metabolism, Diabetes and Obesity Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Lucinda M Hilliard
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Maarten P Koeners
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol , Bristol , United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School , Exeter , United Kingdom
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
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Haase VH. Oxygen sensors as therapeutic targets in kidney disease. Nephrol Ther 2018; 13 Suppl 1:S29-S34. [PMID: 28577740 DOI: 10.1016/j.nephro.2017.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 01/20/2017] [Indexed: 01/03/2023]
Abstract
Hypoxia is a common clinical problem that has profound effects on renal homeostasis. Prolyl-4-hydroxylases PHD1, 2 and 3 function as oxygen sensors and control the activity of hypoxia-inducible factor (HIF), an oxygen-sensitive transcription factor that regulates a multitude of hypoxia responses, which help cells and tissues to adapt to low oxygen environments. This review provides an overview of the molecular mechanisms that govern these hypoxia responses and discusses clinical experience with compounds that inhibit prolyl-4-hydroxylases to harness HIF responses for therapy in nephrology.
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Affiliation(s)
- Volker H Haase
- Department of medicine, Vanderbilt university medical center, Nashville, TN, USA; Departments of cancer biology and molecular physiology and biophysics, Vanderbilt university school of medicine, Nashville, TN, USA; Medical and research services, department of veterans affairs hospital, Tennessee Valley healthcare system, Nashville, TN, USA.
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Hall ME, Jordan JH, Juncos LA, Hundley WG, Hall JE. BOLD magnetic resonance imaging in nephrology. Int J Nephrol Renovasc Dis 2018; 11:103-112. [PMID: 29559807 PMCID: PMC5856054 DOI: 10.2147/ijnrd.s112299] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Magnetic resonance (MR) imaging, a non-invasive modality that provides anatomic and physiologic information, is increasingly used for diagnosis of pathophysiologic conditions and for understanding renal physiology in humans. Although functional MR imaging methods were pioneered to investigate the brain, they also offer powerful techniques for investigation of other organ systems such as the kidneys. However, imaging the kidneys provides unique challenges due to potential complications from contrast agents. Therefore, development of non-contrast techniques to study kidney anatomy and physiology is important. Blood oxygen level-dependent (BOLD) MR is a non-contrast imaging technique that provides functional information related to renal tissue oxygenation in various pathophysiologic conditions. Here we discuss technical considerations, clinical uses and future directions for use of BOLD MR as well as complementary MR techniques to better understand renal pathophysiology. Our intent is to summarize kidney BOLD MR applications for the clinician rather than focusing on the complex physical challenges that functional MR imaging encompasses; however, we briefly discuss some of those issues.
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Affiliation(s)
- Michael E Hall
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jennifer H Jordan
- Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Luis A Juncos
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - W Gregory Hundley
- Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - John E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
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Shi H, Jia J, Li D, Wei L, Shang W, Zheng Z. Blood oxygen level dependent magnetic resonance imaging for detecting pathological patterns in lupus nephritis patients: a preliminary study using a decision tree model. BMC Nephrol 2018; 19:33. [PMID: 29426280 PMCID: PMC5806290 DOI: 10.1186/s12882-017-0787-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/11/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Precise renal histopathological diagnosis will guide therapy strategy in patients with lupus nephritis. Blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) has been applicable noninvasive technique in renal disease. This current study was performed to explore whether BOLD MRI could contribute to diagnose renal pathological pattern. METHODS Adult patients with lupus nephritis renal pathological diagnosis were recruited for this study. Renal biopsy tissues were assessed based on the lupus nephritis ISN/RPS 2003 classification. The Blood oxygen level dependent magnetic resonance imaging (BOLD-MRI) was used to obtain functional magnetic resonance parameter, R2* values. Several functions of R2* values were calculated and used to construct algorithmic models for renal pathological patterns. In addition, the algorithmic models were compared as to their diagnostic capability. RESULTS Both Histopathology and BOLD MRI were used to examine a total of twelve patients. Renal pathological patterns included five classes III (including 3 as class III + V) and seven classes IV (including 4 as class IV + V). Three algorithmic models, including decision tree, line discriminant, and logistic regression, were constructed to distinguish the renal pathological pattern of class III and class IV. The sensitivity of the decision tree model was better than that of the line discriminant model (71.87% vs 59.48%, P < 0.001) and inferior to that of the Logistic regression model (71.87% vs 78.71%, P < 0.001). The specificity of decision tree model was equivalent to that of the line discriminant model (63.87% vs 63.73%, P = 0.939) and higher than that of the logistic regression model (63.87% vs 38.0%, P < 0.001). The Area under the ROC curve (AUROCC) of the decision tree model was greater than that of the line discriminant model (0.765 vs 0.629, P < 0.001) and logistic regression model (0.765 vs 0.662, P < 0.001). CONCLUSIONS BOLD MRI is a useful non-invasive imaging technique for the evaluation of lupus nephritis. Decision tree models constructed using functions of R2* values may facilitate the prediction of renal pathological patterns.
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Affiliation(s)
- Huilan Shi
- Department of Radiology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China
| | - Junya Jia
- Department of Nephrology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China
| | - Dong Li
- Department of Nephrology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China
| | - Li Wei
- Department of Nephrology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China
| | - Wenya Shang
- Department of Nephrology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China
| | - Zhenfeng Zheng
- Department of Nephrology, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, People's Republic of China.
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Abstract
The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.
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Affiliation(s)
- Ivo Torres Filho
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas, USA
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Yu ASL. Paracellular transport as a strategy for energy conservation by multicellular organisms? Tissue Barriers 2017; 5:e1301852. [PMID: 28452575 DOI: 10.1080/21688370.2017.1301852] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Paracellular transport of solutes and water accompanies transcellular transport across epithelial barriers and together they serve to maintain internal body composition. However, whether paracellular transport is necessary and why it evolved is unknown. In this commentary I discuss our recent studies to address this question in the proximal tubule of the kidney. Paracellular reabsorption of sodium occurs in the proximal tubule and is mediated by claudin-2. However, deletion of claudin-2 in mice does not affect whole kidney sodium excretion because it can be completely compensated by downtream transcellular transport mechanisms. This occurs at the expense of increased oxygen consumption, tissue hypoxia and increased susceptibility to ischemic injury. It is concluded that paracellular transport acts as an energy saving mechanism to increase transport without consuming additional oxygen. It is speculated that this might be why paracellular transport evolved in leaky epithelia with high transport needs.
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Affiliation(s)
- Alan S L Yu
- a Division of Nephrology and Hypertension, Department of Internal Medicine , University of Kansas Medical Center , Kansas City , KS , USA.,b Division of Infectious Diseases, Department of Internal Medicine , University of Kansas Medical Center , Kansas City , KS , USA
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Kalfadis S, Nalbanti V, Ioannidis O, Porfiriou G, Botsios D, Tsalis K. Variations of renal tissue oxygenation during abdominal compartment syndrome and sepsis. Adv Med Sci 2017; 62:177-185. [PMID: 28282605 DOI: 10.1016/j.advms.2016.08.004] [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: 01/19/2016] [Revised: 07/07/2016] [Accepted: 08/24/2016] [Indexed: 10/20/2022]
Abstract
PURPOSE This experimental study was designed to evaluate the renal tissue oxygenation under the coexistence of abdominal compartment syndrome and sepsis. MATERIAL AND METHODS Fourteen non-breed dogs were divided into two groups: the control group (8) and the study group (6). Sepsis was established with intravenous endotoxin infusion at 100μg/kg for over 30min. Insufflation of CO2 in the peritoneal cavity was used for the increase in intra-abdominal pressure (IAP). A special catheter placed and fixed in the renal cortex at a depth of 3mm from the renal capsule was used for the measurement of renal tissue oxygenation. RESULTS Study parameters were recorded at the starting phase, at IAP of 15mmHg and 30mmHg and after decompression of the abdomen in the control group, and at the same intervals plus the induction of sepsis, prior to increasing abdominal pressure, in the study group. With the elevation of the IAP a reduction of renal tissue oxygenation presents itself, which is more pronounced in the presence of sepsis, especially for IAP over 15mmHg. Like other parameters, after abdominal decompression the renal tissue oxygenation returns to the initial levels, independently of sepsis. CONCLUSIONS The afferent arterioles vasoconstriction, which takes place during sepsis, and the intra-renal shunt, which occurs and leads to blood diversion to the medulla from the renal cortex due to the combination of intra-abdominal hypertension (IAH) and sepsis, seem to explain this finding.
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Affiliation(s)
- Stavros Kalfadis
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Vaia Nalbanti
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Orestis Ioannidis
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - George Porfiriou
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Dimitrios Botsios
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Konstantinos Tsalis
- Fourth Surgical Department, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Thacker JM, Li LP, Li W, Zhou Y, Sprague SM, Prasad PV. Renal Blood Oxygenation Level-Dependent Magnetic Resonance Imaging: A Sensitive and Objective Analysis. Invest Radiol 2016; 50:821-7. [PMID: 26193455 DOI: 10.1097/rli.0000000000000190] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES The aim of this study was to determine a robust (sensitive and objective) method for analyzing renal blood oxygenation level-dependent magnetic resonance imaging data. MATERIALS AND METHODS Forty-seven subjects (30 with chronic kidney disease [CKD] and 17 controls) were imaged at baseline and after furosemide with a multiecho gradient recalled echo sequence. Conventional analysis consisted of regional segmentation (small cortex, large cortex, and medulla), followed by computing the mean of each region. In addition, we segmented the entire parenchyma and computed the mean (μ1) plus higher moments (μ2, μ3, and μ4). Two raters performed each of the segmentation steps, and agreement was assessed with intraclass correlation coefficients (ICCs). We used a measure of effect size (Cohen's d value), in addition to the usual measure of statistical significance, P values, for determining significant results. RESULTS The mean of the renal parenchyma showed the highest agreement between raters (ICC, 0.99), and the higher parenchyma moments were on par with large cortical region of interest (ROI) ICC. The renal parenchymal mean also exhibited significant sensitivity to changes after furosemide administration in healthy subjects (P = 0.002, d = 0.84), in agreement with medullary ROIs (P = 0.002, d = 1.59). When comparing controls and subjects with CKD at baseline, cortical ROI showed a significant difference (P = 0.015, d = -0.69), whereas the parenchyma ROI did not (P = 0.152, d = 0.39). Post-furosemide data in all regions resulted in a significant difference (large cortex: P = 0.026, d = -0.51; medulla: P = 0.019, d = -0.61) with the renal parenchyma ROI resulting in the largest effect size (P = 0.003, d = -0.75). Higher moments of the renal parenchyma showed similar significant differences as well. CONCLUSIONS Overall, our data support the use of the entire parenchyma to evaluate changes in the medulla after administration of furosemide, a widely used pharmacological maneuver. Changes in higher moments indicate that there is more than just a shift in the mean renal R2* and may provide clinically relevant information without the need for subjective regional segmentation. For evaluating differences between controls and subjects with CKD at baseline; large cortical ROI provided the highest sensitivity and objectivity. A combination of renal parenchyma assessment and large cortical ROI may provide the most robust method of evaluating renal blood oxygenation level-dependent magnetic resonance imaging data.
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Affiliation(s)
- Jon M Thacker
- From the *Department of Biomedical Engineering, Northwestern University; †Department of Radiology/Center for Advanced Imaging, NorthShore University Healthsystem, Evanston; ‡Department of Medicine, University of Chicago Pritzker School of Medicine, Chicago; §Center for Biomedical and Research Informatics, and ║Department of Medicine, NorthShore University Healthsystem, Evanston, IL
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Thacker J, Zhang JL, Franklin T, Prasad P. BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats. Magn Reson Med 2016; 78:297-302. [PMID: 27501515 DOI: 10.1002/mrm.26367] [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: 04/28/2016] [Revised: 06/22/2016] [Accepted: 07/12/2016] [Indexed: 11/06/2022]
Abstract
PURPOSE Blood oxygen level-dependent (BOLD) MRI has been effectively used to monitor changes in renal oxygenation. However, R2* (or T2*) is not specific to blood oxygenation and is dependent on other factors. This study investigates the use of a statistical model that takes these factors into account and maps BOLD MRI measurements to blood pO2. METHODS Spin echo and gradient echo images were obtained in six Sprague-Dawley rats and R2 and R2* maps were computed. Measurements were made at baseline, post-nitric oxide synthase inhibitor (L-NAME), and post-furosemide administration. A simulation of each region was performed to map R2' (computed as R2*-R2) to blood pO2. RESULTS At baseline, blood pO2 in the outer medulla was 30.5 ± 1.2 mmHg and 51.9 ± 5.2 mmHg in the cortex, in agreement with previous invasive studies. Blood pO2 was found to decrease within the outer medulla following L-NAME (P < 0.05) and increase after furosemide (P < 0.05). Blood pO2 in the cortex increased following furosemide (P < 0.05). CONCLUSIONS Model-derived blood pO2 is sensitive to pharmacological challenges, and baseline pO2 is comparable to literature values. Reporting pO2 instead of R2* could lead to a greater clinical impact of renal BOLD MRI and facilitate the identification of hypoxic regions. Magn Reson Med 78:297-302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jon Thacker
- Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
| | - Jeff L Zhang
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA
| | - Tammy Franklin
- Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - Pottumarthi Prasad
- Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA.,Department of Radiology, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
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Maringer K, Sims-Lucas S. The multifaceted role of the renal microvasculature during acute kidney injury. Pediatr Nephrol 2016; 31:1231-40. [PMID: 26493067 PMCID: PMC4841763 DOI: 10.1007/s00467-015-3231-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 12/20/2022]
Abstract
Pediatric acute kidney injury (AKI) represents a complex disease process for clinicians as it is multifactorial in cause and only limited treatment or preventatives are available. The renal microvasculature has recently been implicated in AKI as a strong therapeutic candidate involved in both injury and recovery. Significant progress has been made in the ability to study the renal microvasculature following ischemic AKI and its role in repair. Advances have also been made in elucidating cell-cell interactions and the molecular mechanisms involved in these interactions. The ability of the kidney to repair post AKI is closely linked to alterations in hypoxia, and these studies are elucidated in this review. Injury to the microvasculature following AKI plays an integral role in mediating the inflammatory response, thereby complicating potential therapeutics. However, recent work with experimental animal models suggests that the endothelium and its cellular and molecular interactions are attractive targets to prevent injury or hasten repair following AKI. Here, we review the cellular and molecular mechanisms of the renal endothelium in AKI, as well as repair and recovery, and potential therapeutics to prevent or ameliorate injury and hasten repair.
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Affiliation(s)
- Katherine Maringer
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
- Division of Nephrology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sunder Sims-Lucas
- Rangos Research Center, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA.
- Division of Nephrology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA.
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Abstract
OBJECTIVES The objectives of this review are to discuss the technology and clinical interpretation of near infrared spectroscopy oximetry and its clinical application in patients with congenital heart disease. DATA SOURCE MEDLINE and PubMed. CONCLUSION Near infrared spectroscopy provides a continuous noninvasive assessment of tissue oxygenation. Over 20 years ago, near infrared spectroscopy was introduced into clinical practice for monitoring cerebral oxygenation during cardiopulmonary bypass in adults. Since that time, the utilization of near infrared spectroscopy has extended into the realm of pediatric cardiac surgery and is increasingly being used in the cardiac ICU to monitor tissue oxygenation perioperatively.
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Pei L, Solis G, Nguyen MTX, Kamat N, Magenheimer L, Zhuo M, Li J, Curry J, McDonough AA, Fields TA, Welch WJ, Yu ASL. Paracellular epithelial sodium transport maximizes energy efficiency in the kidney. J Clin Invest 2016; 126:2509-18. [PMID: 27214555 DOI: 10.1172/jci83942] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 04/05/2016] [Indexed: 12/12/2022] Open
Abstract
Efficient oxygen utilization in the kidney may be supported by paracellular epithelial transport, a form of passive diffusion that is driven by preexisting transepithelial electrochemical gradients. Claudins are tight-junction transmembrane proteins that act as paracellular ion channels in epithelial cells. In the proximal tubule (PT) of the kidney, claudin-2 mediates paracellular sodium reabsorption. Here, we used murine models to investigate the role of claudin-2 in maintaining energy efficiency in the kidney. We found that claudin-2-null mice conserve sodium to the same extent as WT mice, even during profound dietary sodium depletion, as a result of the upregulation of transcellular Na-K-2Cl transport activity in the thick ascending limb of Henle. We hypothesized that shifting sodium transport to transcellular pathways would lead to increased whole-kidney oxygen consumption. Indeed, compared with control animals, oxygen consumption in the kidneys of claudin-2-null mice was markedly increased, resulting in medullary hypoxia. Furthermore, tubular injury in kidneys subjected to bilateral renal ischemia-reperfusion injury was more severe in the absence of claudin-2. Our results indicate that paracellular transport in the PT is required for efficient utilization of oxygen in the service of sodium transport. We speculate that paracellular permeability may have evolved as a general strategy in epithelial tissues to maximize energy efficiency.
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Kobayashi H, Liu Q, Binns TC, Urrutia AA, Davidoff O, Kapitsinou PP, Pfaff AS, Olauson H, Wernerson A, Fogo AB, Fong GH, Gross KW, Haase VH. Distinct subpopulations of FOXD1 stroma-derived cells regulate renal erythropoietin. J Clin Invest 2016; 126:1926-38. [PMID: 27088801 DOI: 10.1172/jci83551] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 03/01/2016] [Indexed: 12/11/2022] Open
Abstract
Renal peritubular interstitial fibroblast-like cells are critical for adult erythropoiesis, as they are the main source of erythropoietin (EPO). Hypoxia-inducible factor 2 (HIF-2) controls EPO synthesis in the kidney and liver and is regulated by prolyl-4-hydroxylase domain (PHD) dioxygenases PHD1, PHD2, and PHD3, which function as cellular oxygen sensors. Renal interstitial cells with EPO-producing capacity are poorly characterized, and the role of the PHD/HIF-2 axis in renal EPO-producing cell (REPC) plasticity is unclear. Here we targeted the PHD/HIF-2/EPO axis in FOXD1 stroma-derived renal interstitial cells and examined the role of individual PHDs in REPC pool size regulation and renal EPO output. Renal interstitial cells with EPO-producing capacity were entirely derived from FOXD1-expressing stroma, and Phd2 inactivation alone induced renal Epo in a limited number of renal interstitial cells. EPO induction was submaximal, as hypoxia or pharmacologic PHD inhibition further increased the REPC fraction among Phd2-/- renal interstitial cells. Moreover, Phd1 and Phd3 were differentially expressed in renal interstitium, and heterozygous deficiency for Phd1 and Phd3 increased REPC numbers in Phd2-/- mice. We propose that FOXD1 lineage renal interstitial cells consist of distinct subpopulations that differ in their responsiveness to Phd2 inactivation and thus regulation of HIF-2 activity and EPO production under hypoxia or conditions of pharmacologic or genetic PHD inactivation.
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Fu Q, Colgan SP, Shelley CS. Hypoxia: The Force that Drives Chronic Kidney Disease. Clin Med Res 2016; 14:15-39. [PMID: 26847481 PMCID: PMC4851450 DOI: 10.3121/cmr.2015.1282] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 09/30/2015] [Indexed: 12/15/2022]
Abstract
In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy.
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Affiliation(s)
- Qiangwei Fu
- Kabara Cancer Research Institute, La Crosse, WI
| | - Sean P Colgan
- Mucosal Inflammation Program and University of Colorado School of Medicine, Aurora, CO
| | - Carl Simon Shelley
- University of Wisconsin School of Medicine and Public Health, Madison, WI
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