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Xiao M, Chi X, Zhu X, Xu Z, Zou Y, Peng Y, Luan S, Dong J, Dai Y, Yin L. Proteomic analysis of laser captured tubular tissues reveals complement activation and mitochondrial dysfunction in autoimmune related kidney diseases. Sci Rep 2024; 14:19311. [PMID: 39164435 PMCID: PMC11336080 DOI: 10.1038/s41598-024-70209-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Accepted: 08/13/2024] [Indexed: 08/22/2024] Open
Abstract
Autoimmune related kidney diseases (ARKDs), including minimal change nephropathy (MCN), membranous nephropathy (MN), IgA nephropathy (IgAN), and lupus nephritis (LN), significantly affect renal function. These diseases are characterized by the formation of local immune complexes and the subsequent activation of the complement system, leading to kidney damage and proteinuria. Despite the known patterns of glomerular injury, the specific molecular mechanisms that contribute to renal tubular damage across ARKDs remain underexplored. Laser capture microdissection and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to conduct a comparative proteomic analysis of renal tubular tissues from formalin-fixed paraffin-embedded samples. The cohort comprised of 10 normal controls (NC), 5 MCN, 4 MN, 17 IgAN, and 21 LN patients. Clinical parameters and histopathological assessments were integrated with proteomic findings to comprehensively investigate underlying pathogenic processes. Clinical evaluation indicated significant glomerular damage, as reflected by elevated urinary protein levels and reduced plasma albumin levels in patients with ARKD. Histological analyses confirmed varying degrees of tubular damage and deposition of immune complexes. Proteomic analyses identified significant changes in protein expression, particularly in complement components (C3, C4A, C4B, C8G, CFB, and SERPINA1) and mitochondrial proteins (ATP5F1E and ATP5PD), highlighting the common alterations in the complement system and mitochondrial proteins across ARKDs. These alterations suggest a novel complement-mitochondrial-epithelial-mesenchymal transition (EMT) pathway axis that contributes to tubular damage in ARKDs. Notably, significant alterations in CFB in tubular ARKD patients were revealed, implicating it as a therapeutic target. This study underscores the importance of complement activation and mitochondrial dysfunction in the pathogenesis of ARKDs, and proposes CFB as a potential therapeutic target to inhibit complement activation and mitigate tubular damage. Future research should validate the complement-mitochondrial-EMT pathway axis and explore the effects and mechanisms of CFB inhibitors in alleviating ARKD progression.
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Affiliation(s)
- Mengyun Xiao
- Institute of Nephrology and Blood Purification, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Xianggeng Chi
- Institute of Nephrology and Blood Purification, The First Affiliated Hospital of Jinan University, Guangzhou, China
- Department of Nephrology, Xiaolan People's Hospital of Zhongshan, Zhongshan, China
| | - Xiaohui Zhu
- Institute of Nephrology and Blood Purification, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Zigan Xu
- Department of Nephrology, Shenzhen Longhua District Central Hospital, Shenzhen, China
| | - Yaoshuang Zou
- Department of Organ Transplantation, 924 Hospital, Guilin, China
| | - Yue Peng
- Institute of Nephrology and Blood Purification, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Shaodong Luan
- Department of Nephrology, Shenzhen Longhua District Central Hospital, Shenzhen, China
| | - Jingjing Dong
- Department of General Medicine, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, China.
| | - Yong Dai
- School of Medicine, The First Affiliated Hospital, Anhui University of Science and Technology, Huainan, China.
| | - Lianghong Yin
- Institute of Nephrology and Blood Purification, The First Affiliated Hospital of Jinan University, Guangzhou, China.
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Wooden B, Nester CM, Bomback AS. Update on C3 Glomerulopathy. ADVANCES IN KIDNEY DISEASE AND HEALTH 2024; 31:223-233. [PMID: 39004462 DOI: 10.1053/j.akdh.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 05/13/2024] [Accepted: 05/20/2024] [Indexed: 07/16/2024]
Abstract
C3 glomerulopathy (C3G) is a rare disorder marked by deposition of C3 in the glomerulus, resulting in damage to the glomerular filtration unit and presenting with features of the nephritic and nephrotic syndromes. Fundamentally, C3G is caused by dysregulation of the alternative pathway of the complement cascade, either due to genetic variants or acquired humoral factors. Despite significant advances in recent years in the understanding of the underlying mechanisms and culprit lesions that result in the development of C3G, treatment options remain severely limited, and the prognosis is often poor. Fortunately, a number of anticomplement therapies are emerging from the drug development pipeline, with several in late-stage testing in patients with C3G, and there is hope that we will soon have more targeted options for managing patients with this devastating disease. In this review, we provide an overview of C3G, as well as summarizing the evidence for current treatments and detailing the clinical trials that are currently underway.
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Affiliation(s)
- Benjamin Wooden
- Division of Nephrology, Department of Medicine, Columbia University, New York, NY.
| | - Carla M Nester
- Division of Nephrology, Department of Medicine, University of Iowa, Iowa City, IA
| | - Andrew S Bomback
- Division of Nephrology, Department of Medicine, Columbia University, New York, NY
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Andeen NK, Hou J. Diagnostic Challenges and Emerging Pathogeneses of Selected Glomerulopathies. Pediatr Dev Pathol 2024:10935266241237656. [PMID: 38576387 DOI: 10.1177/10935266241237656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Recent progress in glomerular immune complex and complement-mediated diseases have refined diagnostic categories and informed mechanistic understanding of disease development in pediatric patients. Herein, we discuss selected advances in 3 categories. First, membranous nephropathy antigens are increasingly utilized to characterize disease in pediatric patients and include phospholipase A2 receptor (PLA2R), Semaphorin 3B (Sema3B), neural epidermal growth factor-like 1 (NELL1), and protocadherin FAT1, as well as the lupus membranous-associated antigens exostosin 1/2 (EXT1/2), neural cell adhesion molecule 1 (NCAM1), and transforming growth factor beta receptor 3 (TGFBR3). Second, we examine advances in techniques for paraffin and light chain immunofluorescence (IF), including the former's function as a salvage technique and their necessity for diagnosis in adolescent cases of membranous-like glomerulopathy with masked IgG kappa deposits (MGMID) and proliferative glomerulonephritis with monotypic Ig deposits (PGNMID), respectively. Finally, progress in understanding the roles of complement in pediatric glomerular disease is reviewed, with specific attention to overlapping clinical, histologic, and genetic or functional alternative complement pathway (AP) abnormalities among C3 glomerulopathy (C3G), infection-related and post-infectious GN, "atypical" post-infectious GN, immune complex mediated membranoproliferative glomerulonephritis (IC-MPGN), and atypical hemolytic uremic syndrome (aHUS).
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Affiliation(s)
- Nicole K Andeen
- Oregon Health & Science University, Department of Pathology and Laboratory Medicine, Portland, OR, USA
| | - Jean Hou
- Cedars-Sinai Medical Center, Department of Pathology, Los Angeles, CA, USA
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Vivarelli M, Bomback AS, Meier M, Wang Y, Webb NJ, Veldandi UK, Smith RJ, Kavanagh D. Iptacopan in Idiopathic Immune Complex-Mediated Membranoproliferative Glomerulonephritis: Protocol of the APPARENT Multicenter, Randomized Phase 3 Study. Kidney Int Rep 2024; 9:64-72. [PMID: 38312795 PMCID: PMC10831369 DOI: 10.1016/j.ekir.2023.10.022] [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: 06/06/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 02/06/2024] Open
Abstract
Introduction Immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) is an ultra-rare, fast-progressing kidney disease that may be idiopathic (primary) or secondary to chronic infection, autoimmune disorders, or monoclonal gammopathies. Dysregulation of the alternative complement pathway is implicated in the pathophysiology of IC-MPGN; and currently, there are no approved targeted treatments. Iptacopan is an oral, highly potent proximal complement inhibitor that specifically binds to factor B and inhibits the alternative pathway (AP). Methods This randomized, double-blind, placebo-controlled phase 3 study (APPARENT; NCT05755386) will evaluate the efficacy and safety of iptacopan in patients with idiopathic (primary) IC-MPGN, enrolling up to 68 patients (minimum of 10 adolescents) aged 12 to 60 years with biopsy-confirmed IC-MPGN, proteinuria ≥1 g/g, and estimated glomerular filtration rate (eGFR) ≥30 ml/min per 1.73 m2. All patients will receive maximally tolerated angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and vaccination against encapsulated bacteria. Patients with any organ transplant, progressive crescentic glomerulonephritis, or kidney biopsy with >50% interstitial fibrosis/tubular atrophy, will be excluded. Patients will be randomized 1:1 to receive either iptacopan 200 mg twice daily (bid) or placebo for 6 months, followed by open-label treatment with iptacopan 200 mg bid for all patients for 6 months. The primary objective of the study is to evaluate the efficacy of iptacopan versus placebo in proteinuria reduction measured as urine protein-to-creatinine ratio (UPCR) (24-h urine) at 6 months. Key secondary end points will assess kidney function measured by eGFR, patients who achieve a proteinuria-eGFR composite end point, and patient-reported fatigue. Conclusion This study will provide evidence toward the efficacy and safety of iptacopan in idiopathic (primary) IC-MPGN.
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Affiliation(s)
- Marina Vivarelli
- Division of Nephrology, Laboratory of Nephrology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Andrew S. Bomback
- Division of Nephrology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Matthias Meier
- Global Drug Development, Novartis Pharma AG, Basel, Switzerland
| | - Yaqin Wang
- Global Drug Development, Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, USA
| | | | | | - Richard J.H. Smith
- Molecular Otolaryngology and Renal Research Laboratories and the Departments of Internal Medicine and Pediatrics (Divisions of Nephrology), Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - David Kavanagh
- National Renal Complement Therapeutics Centre, Newcastle upon Tyne Hospitals, National Health Service Foundation Trust, Newcastle upon Tyne, UK
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Rydberg V, Aradottir SS, Kristoffersson AC, Svitacheva N, Karpman D. Genetic investigation of Nordic patients with complement-mediated kidney diseases. Front Immunol 2023; 14:1254759. [PMID: 37744338 PMCID: PMC10513385 DOI: 10.3389/fimmu.2023.1254759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 08/21/2023] [Indexed: 09/26/2023] Open
Abstract
Background Complement activation in atypical hemolytic uremic syndrome (aHUS), C3 glomerulonephropathy (C3G) and immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) may be associated with rare genetic variants. Here we describe gene variants in the Swedish and Norwegian populations. Methods Patients with these diagnoses (N=141) were referred for genetic screening. Sanger or next-generation sequencing were performed to identify genetic variants in 16 genes associated with these conditions. Nonsynonymous genetic variants are described when they have a minor allele frequency of <1% or were previously reported as being disease-associated. Results In patients with aHUS (n=94, one also had IC-MPGN) 68 different genetic variants or deletions were identified in 60 patients, of which 18 were novel. Thirty-two patients had more than one genetic variant. In patients with C3G (n=40) 29 genetic variants, deletions or duplications were identified in 15 patients, of which 9 were novel. Eight patients had more than one variant. In patients with IC-MPGN (n=7) five genetic variants were identified in five patients. Factor H variants were the most frequent in aHUS and C3 variants in C3G. Seventeen variants occurred in more than one condition. Conclusion Genetic screening of patients with aHUS, C3G and IC-MPGN is of paramount importance for diagnostics and treatment. In this study, we describe genetic assessment of Nordic patients in which 26 novel variants were found.
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Affiliation(s)
| | | | | | | | - Diana Karpman
- Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden
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