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Fukuda A, Sato Y, Shibata H, Fujimoto S, Wiggins RC. Urinary podocyte markers of disease activity, therapeutic efficacy, and long-term outcomes in acute and chronic kidney diseases. Clin Exp Nephrol 2024; 28:496-504. [PMID: 38402504 PMCID: PMC11116200 DOI: 10.1007/s10157-024-02465-y] [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: 12/18/2023] [Accepted: 01/14/2024] [Indexed: 02/26/2024]
Abstract
A critical degree of podocyte depletion causes glomerulosclerosis, and persistent podocyte loss in glomerular diseases drives the progression to end-stage kidney disease. The extent of podocyte injury at a point in time can be histologically assessed by measuring podocyte number, size, and density ("Biopsy podometrics"). However, repeated invasive renal biopsies are associated with increased risk and cost. A noninvasive method for assessing podocyte injury and depletion is required. Albuminuria and proteinuria do not always correlate with disease activity. Podocytes are located on the urinary space side of the glomerular basement membrane, and as they undergo stress or detach, their products can be identified in urine. This raises the possibility that urinary podocyte products can serve as clinically useful markers for monitoring glomerular disease activity and progression ("Urinary podometrics"). We previously reported that urinary sediment podocyte mRNA reflects disease activity in both animal models and human glomerular diseases. This includes diabetes and hypertension which together account for 60% of new-onset dialysis induction patients. Improving approaches to preventing progression is an urgent priority for the renal community. Sufficient evidence now exists to indicate that monitoring urinary podocyte markers could serve as a useful adjunctive strategy for determining the level of current disease activity and response to therapy in progressive glomerular diseases.
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Affiliation(s)
- Akihiro Fukuda
- Department of Endocrinology, Metabolism, Rheumatology and Nephrology, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-Machi, Yufu City, Oita, 879-5593, Japan.
| | - Yuji Sato
- Division of Nephrology, Department of Internal Medicine, National Health Insurance Takachiho Town Hospital, Takachiho, Miyazaki, Japan
| | - Hirotaka Shibata
- Department of Endocrinology, Metabolism, Rheumatology and Nephrology, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama-Machi, Yufu City, Oita, 879-5593, Japan
| | - Shouichi Fujimoto
- Department of Medical Environment Innovation, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Roger C Wiggins
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
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Barsotti GC, Luciano R, Kumar A, Meliambro K, Kakade V, Tokita J, Naik A, Fu J, Peck E, Pell J, Reghuvaran A, Tanvir E, Patel P, Zhang W, Li F, Moeckel G, Perincheri S, Cantley L, Moledina DG, Wilson FP, He JC, Menon MC. Rationale and Design of a Phase 2, Double-blind, Placebo-Controlled, Randomized Trial Evaluating AMP Kinase-Activation by Metformin in Focal Segmental Glomerulosclerosis. Kidney Int Rep 2024; 9:1354-1368. [PMID: 38707807 PMCID: PMC11068976 DOI: 10.1016/j.ekir.2024.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 01/30/2024] [Accepted: 02/05/2024] [Indexed: 05/07/2024] Open
Abstract
Introduction Focal segmental glomerulosclerosis (FSGS), the most common primary glomerular disease leading to end-stage kidney disease (ESKD), is characterized by podocyte injury and depletion, whereas minimal change disease (MCD) has better outcomes despite podocyte injury. Identifying mechanisms capable of preventing podocytopenia during injury could transform FSGS to an "MCD-like" state. Preclinical data have reported conversion of an MCD-like injury to one with podocytopenia and FSGS by inhibition of AMP-kinase (AMPK) in podocytes. Conversely, in FSGS, AMPK-activation using metformin (MF) mitigated podocytopenia and azotemia. Observational studies also support beneficial effects of MF on proteinuria and chronic kidney disease (CKD) outcomes in diabetes. A randomized controlled trial (RCT) to test MF in podocyte injury with FSGS has not yet been conducted. Methods We report the rationale and design of phase 2, double-blind, placebo-controlled RCT evaluating the efficacy and safety of MF as adjunctive therapy in FSGS. By randomizing 30 patients with biopsy-confirmed FSGS to MF or placebo (along with standard immunosuppression), we will study mechanistic biomarkers that correlate with podocyte injury or depletion and evaluate outcomes after 6 months. We specifically integrate novel urine, blood, and tissue markers as surrogates for FSGS progression along with unbiased profiling strategies. Results and Conclusion Our phase 2 trial will provide insight into the potential efficacy and safety of MF as adjunctive therapy in FSGS-a crucial step to developing a larger phase 3 study. The mechanistic assays here will guide the design of other FSGS trials and contribute to understanding AMPK activation as a potential therapeutic target in FSGS. By repurposing an inexpensive agent, our results will have implications for FSGS treatment in resource-poor settings.
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Affiliation(s)
- Gabriel C. Barsotti
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Randy Luciano
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Ashwani Kumar
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kristin Meliambro
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Vijayakumar Kakade
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Joji Tokita
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Abhijit Naik
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Jia Fu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Elizabeth Peck
- Clinical Research Coordinator, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John Pell
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Anand Reghuvaran
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - E.M. Tanvir
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Prashant Patel
- Investigational Drug Service, Department of Pharmacy Services, Yale New Haven Hospital, Connecticut, USA
| | - Weijia Zhang
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Fan Li
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, USA
| | - Gilbert Moeckel
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Sudhir Perincheri
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Lloyd Cantley
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Dennis G. Moledina
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - F. Perry Wilson
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - John C. He
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Madhav C. Menon
- Section of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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Okabe M, Koike K, Yamamoto I, Tsuboi N, Matsusaka T, Yokoo T. Early growth response 1 as a podocyte injury marker in human glomerular diseases. Clin Kidney J 2024; 17:sfad289. [PMID: 38186896 PMCID: PMC10768762 DOI: 10.1093/ckj/sfad289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Indexed: 01/09/2024] Open
Abstract
Background In human glomerular diseases, visualizing podocyte injury is desirable since podocytes do not regenerate and podocyte injury leads to podocyte loss. Herein, we investigated the utility of immunostaining for early growth response 1 (EGR1), which is expressed in injured podocytes from the early stages of injury in animal experiments, as a podocyte injury marker in human glomerular diseases. Methods This study included 102 patients with biopsy-proven glomerular diseases between 2018 and 2021. The proportion of EGR1 expression in podocytes (%EGR1pod) was analyzed in relation to clinical and histopathological features, including glomerular and urinary podocyte-specific markers. Results %EGR1pod correlated significantly with the urinary protein:creatinine ratio, urinary nephrin and podocin mRNA levels, and glomerular podocin staining (rho = 0.361, 0.514, 0.487 and -0.417, respectively; adjusted P = .002, <.001, <.001 and <.001, respectively). Additionally, %EGR1pod correlated with cellular/fibrocellular crescents (rho = 0.479, adjusted P <.001). %EGR1pod was high in patients with glomerulonephritis, such as immunoglobulin A nephropathy (IgAN), lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis, and in those with podocytopathies, such as membranous nephropathy and primary focal segmental glomerulosclerosis, while %EGR1pod was low in patients with minimal change disease. In a subgroup analysis of IgAN, %EGR1pod was higher in Oxford C1 patients than in C0 patients. However, unexpectedly, patients with higher %EGR1pod were more prone to attain proteinuria remission, suggesting that EGR1 in the context of IgAN reflects reversible early injury. Conclusions Our findings indicate that EGR1 is a promising potential marker for identifying active early podocyte injury in human glomerular diseases.
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Affiliation(s)
- Masahiro Okabe
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Kentaro Koike
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Izumi Yamamoto
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Nobuo Tsuboi
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Taiji Matsusaka
- Departments of Basic Medicine, Tokai University School of Medicine, Isehara, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
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Luo Q, Liang W, Zhang Z, Zhu Z, Chen Z, Hu J, Yang K, Chi Q, Ding G. Compromised glycolysis contributes to foot process fusion of podocytes in diabetic kidney disease: Role of ornithine catabolism. Metabolism 2022; 134:155245. [PMID: 35780908 DOI: 10.1016/j.metabol.2022.155245] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/16/2022] [Accepted: 06/22/2022] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Compromised glycolysis in podocytes contributes to the initiation of diabetic kidney disease (DKD). Podocyte injury is characterized by cytoskeletal remodeling and foot process fusion. Compromised glycolysis in diabetes likely leads to switch of energy supply in podocyte. However, the underlying mechanism by which disturbed energy supply in podocytes affects the cytoskeletal structure of podocytes remains unclear. METHODS Metabolomic and transcriptomic analyses were performed on the glomeruli of db/db mice to examine the catabolism of glucose, fatty, and amino acids. Ornithine catabolism was targeted in db/db and podocyte-specific pyruvate kinase M2 knockout (PKM2-podoKO) mice. In vitro, expression of ornithine decarboxylase (ODC1) was modulated to investigate the effect of ornithine catabolism on mammalian target of rapamycin (mTOR) signaling and cytoskeletal remodeling in cultured podocytes. RESULTS Multi-omic analyses of the glomeruli revealed that ornithine metabolism was enhanced in db/db mice compared with that in db/m mice under compromised glycolytic conditions. Additionally, ornithine catabolism was exaggerated in podocytes of diabetic PKM2-podoKO mice compared with that in diabetic PKM2flox/flox mice. In vivo, difluoromethylornithine (DFMO, inhibitor of ODC1) administration reduced urinary albumin excretion and alleviated podocyte foot process fusion in db/db mice. In vitro, 2-deoxy-d-glucose (2-DG) exposure induced mTOR signaling activation and cytoskeletal remodeling in podocytes, which was alleviated by ODC1-knockdown. Mechanistically, a small GTPase Ras homolog enriched in the brain (Rheb), a sensor of mTOR signaling, was activated by exposure to putrescine, a metabolic product of ornithine catabolism. CONCLUSION These findings demonstrate that compromised glycolysis in podocytes under diabetic conditions enhances ornithine catabolism. The metabolites of ornithine catabolism contribute to mTOR signaling activation via Rheb and cytoskeletal remodeling in podocytes in DKD.
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Affiliation(s)
- Qiang Luo
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Wei Liang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China.
| | - Zongwei Zhang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zijing Zhu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Zhaowei Chen
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Jijia Hu
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Keju Yang
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China
| | - Qingjia Chi
- Department of Mechanics and Engineering Structure, Wuhan University of Technology, China
| | - Guohua Ding
- Division of Nephrology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China; Nephrology and Urology Research Institute of Wuhan University, Wuhan, Hubei, China.
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