1
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Yu G, Zhao J, Wang M, Chen Y, Feng S, Li B, Wang C, Wang Y, Jiang H, Chen J. Urinary C4d and progression of kidney disease in IgA vasculitis. Nephrol Dial Transplant 2024; 39:1642-1648. [PMID: 38373839 DOI: 10.1093/ndt/gfae045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Indexed: 02/21/2024] Open
Abstract
BACKGROUND Immunoglobulin A (IgA) vasculitis nephritis (IgAVN) is the most common secondary IgA nephropathy (IgAN). Urinary C4d have been identified associated with the development and progression in primary IgAN; however, its role in kidney disease progression of IgAVN is still unclear. METHODS This study enrolled 139 patients with IgAVN, 18 healthy subjects, 23 focal segmental glomerulosclerosis patients and 38 IgAN patients. Urinary C4d levels at kidney biopsy were measured using enzyme-linked immunosorbent assay. The association between urinary C4d/creatinine and kidney disease progression event, defined as 40% estimated glomerular filtration rate decline or end-stage kidney disease, was assessed using Cox proportional hazards models and restricted cubic splines. RESULTS The levels of urinary C4d/creatinine (Cr) in IgAVN and IgAN patients were higher than in healthy controls. Higher levels of urinary C4d/Cr were associated with higher proteinuria and severe Oxford C lesions, and glomerular C4d deposition. After a median follow-up of 52.79 months, 18 (12.95%) participants reached composite kidney disease progression event. The risk of kidney disease progression event was higher with higher levels of Ln(urinary C4d/Cr). After adjustment for clinical data, higher levels of urinary C4d/Cr were associated with kidney disease progression in IgAVN [per Ln-transformed urinary C4d/Cr, hazard ratio 1.573, 95% confidence interval (CI) 1.101-2.245; P = .013]. Compared with the lower C4d/Cr group, the hazard ratio was 5.539 (95% CI 1.135-27.035; P = .034) for the higher levels group. CONCLUSIONS Higher levels of urinary C4d/Cr were associated with kidney disease progression event in patients with IgAVN.
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Affiliation(s)
- Guizhen Yu
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Jie Zhao
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Meifang Wang
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Yang Chen
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Shi Feng
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Bingjue Li
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Cuili Wang
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Yucheng Wang
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Hong Jiang
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
| | - Jianghua Chen
- Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University; Key Laboratory of Kidney Disease Prevention and Control Technology, Zhejiang Province; Institute of Nephrology, Zhejiang University; Zhejiang Clinical Research Center of Kidney and Urinary System Disease, Hangzhou, China
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2
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Zagorec N, Horvatić I, Kasumović D, Osmani B, Sović S, Nikić J, Horaček M, Šenjug P, Galešić K, Galešić Ljubanović D. C4d Is an Independent Predictor of the Kidney Failure in Primary IgA Nephropathy. J Clin Med 2024; 13:5338. [PMID: 39274551 PMCID: PMC11395978 DOI: 10.3390/jcm13175338] [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: 08/03/2024] [Revised: 08/30/2024] [Accepted: 09/05/2024] [Indexed: 09/16/2024] Open
Abstract
Background: C4d deposits are present in a substantial proportion of patients with IgA nephropathy (IgAN), indicating the activation of the lectin pathway (LP) of the complement system. It seems that patients with activated LP have worse renal prognosis. The aim of this study was to investigate the prevalence and prognostic significance of C4d in our cohort of patients with primary IgA nephropathy (pIgAN). Methods: Patients with pIgAN were recruited from a hospital register of kidney biopsies of the Department of Nephrology and Dialysis, Dubrava University Hospital, Zagreb. Additional immunohistochemistry staining for C4d was performed on paraffin-embedded kidney tissue, and patients were stratified into being C4d positive or C4d negative. The clinical and histologic features of patients were analyzed and compared regarding C4d positivity. The primary outcome was defined as kidney failure (KF), and predictor variables of KF and renal survival were analyzed. Results: Of a total of 95 patients with pIgAN included in the study, C4d was present in 43 (45.3%). C4d-positive patients had a higher value of systolic (p = 0.039) and diastolic (p = 0.006) blood pressure at diagnosis as well as higher 24 h proteinuria (p = 0.018), serum urate (p = 0.033), and lower eGFR (p < 0.001). C4d-positive patients had worse renal survival (p < 0.001), higher rates of disease progression to KF (p < 0.001), and higher proteinuria (p < 0.001) and lower eGFR (p < 0.001) at the last follow-up. Glomerular C4d was an independent predictor of disease progression to KF (HR = 5.87 [0.95 CI 1.06-32.44], p = 0.032). Conclusions: C4d is an independent predictor of disease progression in patients with pIgAN. C4d may be used as an additional marker of progressive disease course in IgAN. The therapeutic implications of C4d status in IgAN, particularly in terms of complement inhibitors application, are not yet known.
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Affiliation(s)
- Nikola Zagorec
- Department of Nephrology and Dialysis, Dubrava University Hospital, 10000 Zagreb, Croatia
- Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Ivica Horvatić
- Department of Nephrology and Dialysis, Dubrava University Hospital, 10000 Zagreb, Croatia
- Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Dino Kasumović
- Department of Nephrology and Dialysis, Dubrava University Hospital, 10000 Zagreb, Croatia
- Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
| | - Besa Osmani
- Department of Nephrology and Dialysis, Dubrava University Hospital, 10000 Zagreb, Croatia
| | - Slavica Sović
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
- Department of Medical Statistics, Epidemiology and Medical Informatics, School of Public Health "Andrija Štampar", 10000 Zagreb, Croatia
| | - Jagoda Nikić
- Nursing School Mlinarska, University of Applied Health Sciences, 10000 Zagreb, Croatia
| | - Matija Horaček
- Department of Pathology, School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Petar Šenjug
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
- Division of Nephropathology and Electron Microscopy, Department of Pathology and Cytology, Dubrava University Hospital, 10000 Zagreb, Croatia
| | - Krešimir Galešić
- Department of Nephrology and Dialysis, Dubrava University Hospital, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
| | - Danica Galešić Ljubanović
- Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
- School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
- Department of Pathology, School of Medicine, University of Zagreb, 10000 Zagreb, Croatia
- Division of Nephropathology and Electron Microscopy, Department of Pathology and Cytology, Dubrava University Hospital, 10000 Zagreb, Croatia
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3
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Vivarelli M, Barratt J, Beck LH, Fakhouri F, Gale DP, Goicoechea de Jorge E, Mosca M, Noris M, Pickering MC, Susztak K, Thurman JM, Cheung M, King JM, Jadoul M, Winkelmayer WC, Smith RJH. The role of complement in kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney Int 2024; 106:369-391. [PMID: 38844295 DOI: 10.1016/j.kint.2024.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/25/2024] [Accepted: 05/22/2024] [Indexed: 06/22/2024]
Abstract
Uncontrolled complement activation can cause or contribute to glomerular injury in multiple kidney diseases. Although complement activation plays a causal role in atypical hemolytic uremic syndrome and C3 glomerulopathy, over the past decade, a rapidly accumulating body of evidence has shown a role for complement activation in multiple other kidney diseases, including diabetic nephropathy and several glomerulonephritides. The number of available complement inhibitor therapies has also increased during the same period. In 2022, Kidney Diseases: Improving Global Outcomes (KDIGO) convened a Controversies Conference, "The Role of Complement in Kidney Disease," to address the expanding role of complement dysregulation in the pathophysiology, diagnosis, and management of various glomerular diseases, diabetic nephropathy, and other forms of hemolytic uremic syndrome. Conference participants reviewed the evidence for complement playing a primary causal or secondary role in progression for several disease states and considered how evidence of complement involvement might inform management. Participating patients with various complement-mediated diseases and caregivers described concerns related to life planning, implications surrounding genetic testing, and the need for inclusive implementation of effective novel therapies into clinical practice. The value of biomarkers in monitoring disease course and the role of the glomerular microenvironment in complement response were examined, and key gaps in knowledge and research priorities were identified.
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Affiliation(s)
- Marina Vivarelli
- Laboratory of Nephrology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
| | - Jonathan Barratt
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Laurence H Beck
- Section of Nephrology, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Fadi Fakhouri
- Department of Nephrology, Centre Hospitalier Universitaire, Nantes, France; INSERM UMR S1064, Nantes, France
| | - Daniel P Gale
- Centre for Kidney and Bladder Health, University College London, UK
| | - Elena Goicoechea de Jorge
- Department of Immunology, Ophthalmology and ORL, Complutense University, Madrid, Spain; Area of Chronic Diseases and Transplantation, Research Institute Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Marta Mosca
- Department of Clinical and Experimental Medicine-Rheumatology Unit, University of Pisa, Pisa, Italy
| | - Marina Noris
- Clinical Research Center for Rare Diseases Aldo e Cele Daccò, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Ranica, Italy
| | - Matthew C Pickering
- Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College, Hammersmith Campus, London, UK
| | - Katalin Susztak
- Division of Nephrology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joshua M Thurman
- Division of Nephrology and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | | | - Michel Jadoul
- Cliniques Universitaires Saint Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Wolfgang C Winkelmayer
- Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Richard J H Smith
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; Department of Internal Medicine, Division of Nephrology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; Department of Pediatrics, Division of Nephrology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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4
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Haas M. IgA nephropathy: Correlation between pathologic findings and complement activation. Nephrology (Carlton) 2024; 29 Suppl 2:60-62. [PMID: 39327748 DOI: 10.1111/nep.14342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/01/2024] [Accepted: 06/25/2024] [Indexed: 09/28/2024]
Abstract
Summary at a glanceComplement plays a vital role in the pathogenesis of IgA nephropathy. Kidney biopsies with IgA nephropathy show glomerular immune complex deposits with evidence of complement activation by the alternative pathway and in a subset of cases the mannose binding lectin pathway. The recent development of specific drugs targeting these complement pathways represent a potentially important new approach to treating IgA nephropathy.
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Affiliation(s)
- Mark Haas
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
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5
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Tringali E, Vetrano D, Tondolo F, Maritati F, Fabbrizio B, Pasquinelli G, Provenzano M, La Manna G, Baraldi O. Role of serum complement C3 and C4 on kidney outcomes in IgA nephropathy. Sci Rep 2024; 14:16224. [PMID: 39003309 PMCID: PMC11246413 DOI: 10.1038/s41598-024-65857-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/25/2024] [Indexed: 07/15/2024] Open
Abstract
IgA Nephropathy (IgAN) is the most prevalent glomerular disease worldwide. Complement system activation is crucial in its pathogenesis. Few studies correlated serum C3 and C4 with disease activity and prognosis. This retrospective study investigated the prognostic value of serum complement at the time of diagnosis in patients with IgAN. Specifically we evaluated whether adding serum C3 and C4 levels to established predictive models-one based on variables related to chronic kidney disease (CKD) progression and another incorporating variables from the International IgA Prediction Tool (IntIgAPT)-enhances the accuracy of outcome prediction. A composite renal outcome was defined as 50% decline in eGFR or onset of kidney failure. 101 patients were stratified according to baseline C3 levels in three groups (Low, Medium and High). During a median follow-up of 54 months, the Low group exhibited higher incidence of primary outcome (16.3 events vs 2.9 and 1.7 events × 100 pts/year, p = 0.0026). Model-1 (M1), consisting of CKD progression variables, and Model-3 (M3), comprising IntIgANPT variables, were implemented with baseline C3 and C4 to create Model-2 (M2) and Model-4 (M4), respectively. M2 demonstrated better predictive performance over M1, showing higher discrimination (lower AIC and BIC, higher C-index and NR2). Similarly, M4 outperformed M3, showing enhanced outcome prediction when C3 and C4 levels were added. Implementation of serum C3 and C4 can enhance prediction accuracy of already-validated prognostic models in IgAN. Lower C3 and higher C4 levels were associated with poorer prognosis, highlighting a more 'Complement-Pathic' subset of patients.
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Affiliation(s)
- Edoardo Tringali
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Daniele Vetrano
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Francesco Tondolo
- Nephrology, Dialysis and Kidney Transplant Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Federica Maritati
- Nephrology, Dialysis and Kidney Transplant Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Benedetta Fabbrizio
- Pathology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Gianandrea Pasquinelli
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy
- Pathology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Michele Provenzano
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, CS, Italy.
| | - Gaetano La Manna
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy.
- Nephrology, Dialysis and Kidney Transplant Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy.
| | - Olga Baraldi
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy
- Nephrology and Dialysis Unit, Santa Maria delle Croci Hospital-Ravenna, AUSL Della Romagna, Ravenna, Italy
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6
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Wang Y, Shang S, Jiang S, Zou G, Gao H, Li W. Complement C3a/C3aR and C5a/C5aR deposits accelerate the progression of advanced IgA nephropathy to end-stage renal disease. Clin Exp Med 2024; 24:139. [PMID: 38951265 PMCID: PMC11217045 DOI: 10.1007/s10238-024-01410-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Accepted: 06/19/2024] [Indexed: 07/03/2024]
Abstract
IgA nephropathy (IgAN) is still one of the leading causes of end-stage kidney disease (ESRD), and complement system activation is a key to the pathogenesis of IgAN. The role of complement C3a/C3aR and C5a/C5aR in late stage of IgAN remains unknown. Renal specimens of 75 IgAN patients at the stage 4 CKD were stained using immunofluorescence and immunohistochemistry. The primary outcome was a composite of end-stage renal disease (ESRD) and death. Associations of complement components with baseline clinicopathological characteristics and outcomes were assessed using multivariable Cox regression and Spearman analyses. During a median follow-up of 15.0 months, 27 patients progressed to ESRD and none died. Lower eGFR [hazards ratio (HR), 0.827, 95% confidence interval (CI), 0.732-0.935; P = 0.002] and glomerular C3 deposition (HR, 3.179, 95% CI, 1.079-9.363; P = 0.036) were predictive of time to ESRD in stage 4 CKD IgAN. Higher expression of C3a (P = 0.010), C3aR (P = 0.005), C5a (P = 0.015), and C5aR (P < 0.001) was identified in ESRD group than in non-ESRD group. Glomerular C3a/C3aR and C5a/C5aR deposits were both correlated with a lower baseline eGFR, higher baseline 24 h-urinary protein (24 h-UP) and faster decline of eGFR. Besides, C3a and C5a deposits were found in patients with high S (S1) and T (T1/2) scores, respectively. Complement C3a/C3aR and C5a/C5aR in IgAN patients with stage 4 CKD may portend a faster deterioration of kidney function.
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Affiliation(s)
- Ying Wang
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China
| | - Shunlai Shang
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China.
| | - Shimin Jiang
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China
| | - Guming Zou
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China
| | - Hongmei Gao
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China
| | - Wenge Li
- Department of Nephrology, China-Japan Friendship Hospital, No. 2 East Yinghuayuan Street, Chaoyang District, Beijing, 100029, China.
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7
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Stea ED, D'Ettorre G, Mitrotti A, Gesualdo L. The complement system in the pathogenesis and progression of kidney diseases: What doesn't kill you makes you older. Eur J Intern Med 2024; 124:22-31. [PMID: 38461065 DOI: 10.1016/j.ejim.2024.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 01/31/2024] [Accepted: 02/09/2024] [Indexed: 03/11/2024]
Abstract
The Complement System is an evolutionarily conserved component of immunity that plays a key role in host defense against infections and tissue homeostasis. However, the dysfunction of the Complement System can result in tissue damage and inflammation, thereby contributing to the development and progression of various renal diseases, ranging from atypical Hemolytic Uremic Syndrome to glomerulonephritis. Therapeutic interventions targeting the complement system have demonstrated promising results in both preclinical and clinical studies. Currently, several complement inhibitors are being developed for the treatment of complement-mediated renal diseases. This review aims to summarize the most recent insights into complement activation and therapeutic inhibition in renal diseases. Furthermore, it offers potential directions for the future rational use of complement inhibitor drugs in the context of renal diseases.
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Affiliation(s)
- Emma Diletta Stea
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), Nephrology and Urology Units, University of Bari Aldo Moro, Bari, Italy
| | | | - Adele Mitrotti
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), Nephrology and Urology Units, University of Bari Aldo Moro, Bari, Italy
| | - Loreto Gesualdo
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePre-J), Nephrology and Urology Units, University of Bari Aldo Moro, Bari, Italy.
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8
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Pradeep I, Srinivas BH. Utility of C4d Immunohistochemistry as an Adjunct Stain in Diagnostic Renal Pathology of Glomerular Diseases. Int J Surg Pathol 2024; 32:21-26. [PMID: 37143311 DOI: 10.1177/10668969231167505] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
C4d is a byproduct of the activation of the classic and lectin complement pathways. Being routinely used as a marker for antibody-mediated rejection, the significance of C4d in native kidney disease is currently being widely studied. We evaluated glomerular and extraglomerular C4d staining in 82 biopsies of proliferative and nonproliferative glomerulonephritis diagnosed in our institution. The staining pattern of C4d was tabulated in various glomerular diseases. All biopsies of membranous nephropathy including membranous lupus nephritis (Class V) and immune complex-mediated membranoproliferative glomerulonephritis (MPGN) consistently showed C4d deposits along glomerular basement membrane mirroring the location of immunoglobulin and complement in these conditions. Conversely, other glomerular diseases like IgA nephropathy, postinfectious glomerulonephritis, focal segmental glomerulosclerosis, minimal change disease, and diabetic nephropathy showed variable mesangial and capillary wall C4d deposits. To summarize, the consistent pattern of C4d staining in membranous nephropathy (primary and secondary)and immune complex-mediated MPGN can be used as a valuable adjunct tool in establishing the diagnosis, especially when immunofluorescence findings are limited by inadequate sampling.C4d reactivity in other glomerular diseases are variable and may not aid as a diagnostic tool in renal biopsy evaluation.
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Affiliation(s)
- Immanuel Pradeep
- Department of Pathology and Laboratory Medicine, All India Institute of Medical Sciences, Bibinagar, Hyderabad, India
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9
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Caravaca-Fontán F, Gutiérrez E, Sevillano ÁM, Praga M. Targeting complement in IgA nephropathy. Clin Kidney J 2023; 16:ii28-ii39. [PMID: 38053977 PMCID: PMC10695513 DOI: 10.1093/ckj/sfad198] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 12/07/2023] Open
Abstract
Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Recent years have witnessed significant improvements in the understanding of the pathogenesis of IgAN and particularly, the pathogenic role of complement activation. The alternative complement pathway is the major complement cascade activator in IgAN, and glomerular C3 deposition has been shown to correlate with disease progression. In addition, several studies have provided insight into the pathogenic role of factor H-related proteins -1 and -5 in IgAN, as independent players in complement dysregulation. The lectin pathway has also been shown to be associated with the severity of IgAN. Glomerular deposition of C4d has been associated with increased histologic disease activity, faster decline in estimated glomerular filtration rate and higher risk of kidney failure. On the other hand, although overlooked in the Oxford classification, numerous studies have shown that the coexistence of thrombotic microangiopathy in IgAN is a significant indicator of a poorer prognosis. All the breakthroughs in the understanding of the contributing role of complement in IgAN have paved the way for the development of new complement-targeted therapies in this disease. Several ongoing trials are evaluating the efficacy of new agents against factor B (iptacopan, Ionis-FB-LRX), C3 (pegcetacoplan), factor D (vemircopan, pelecopan), C5 (ravulizumab, cemdisiran) and C5a receptor 1 (avacopan). In this study, we provide a comprehensive review of the role of complement in IgAN, including the emerging mechanisms of complement activation and the promising potential of complement inhibitors as a viable treatment option for IgAN.
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Affiliation(s)
- Fernando Caravaca-Fontán
- Department of Nephrology, Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
| | - Eduardo Gutiérrez
- Department of Nephrology, Hospital Universitario 12 de Octubre (imas12), Madrid, Spain
| | - Ángel M Sevillano
- Department of Nephrology, Hospital Universitario 12 de Octubre (imas12), Madrid, Spain
| | - Manuel Praga
- Department of Nephrology, Instituto de Investigación Hospital 12 de Octubre (imas12), Madrid, Spain
- Department of Medicine, Complutense University, Madrid, Spain
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10
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Cattran DC, Floege J, Coppo R. Evaluating Progression Risk in Patients With Immunoglobulin A Nephropathy. Kidney Int Rep 2023; 8:2515-2528. [PMID: 38106572 PMCID: PMC10719597 DOI: 10.1016/j.ekir.2023.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 12/19/2023] Open
Abstract
The highly variable rate of decline in kidney function in patients with immunoglobulin A nephropathy (IgAN) provides a major clinical challenge. Predicting which patients will progress to kidney failure, and how quickly, is difficult. Multiple novel therapies are likely to be approved in the short-term, but clinicians lack the tools to identify patients most likely to benefit from specific treatments at the right time. Noninvasive and validated markers for selecting at-risk patients and longitudinal monitoring are urgently needed. This review summarizes what is known about demographic, clinical, and histopathologic prognostic markers in the clinician's toolkit, including the International IgAN Prediction Tool. We also briefly review what is known on these topics in children and adolescents with IgAN. Although helpful, currently used markers leave clinicians heavily reliant on histologic features from the diagnostic kidney biopsy and standard clinical data to guide treatment choice, and very few noninvasive markers reflect treatment efficacy over time. Novel prognostic and predictive markers are under clinical investigation, with considerable progress being made in markers of complement activation. Other areas of research are the interplay between gut microbiota and galactose-deficient IgA1 expression; microRNAs; imaging; artificial intelligence; and markers of fibrosis. Given the rate of therapeutic advancement, the remaining gaps in biomarker research need to be addressed. We finish by describing our route to clinical utility of predictive and prognostic markers in IgAN. This route will provide us with the chance to improve IgAN prognosis by using robust, clinically practical markers to inform patient care.
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Affiliation(s)
| | - Jürgen Floege
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | - Rosanna Coppo
- Fondazione Ricerca Molinette, Regina Margherita Hospital, Turin, Italy
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11
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Stamellou E, Seikrit C, Tang SCW, Boor P, Tesař V, Floege J, Barratt J, Kramann R. IgA nephropathy. Nat Rev Dis Primers 2023; 9:67. [PMID: 38036542 DOI: 10.1038/s41572-023-00476-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/26/2023] [Indexed: 12/02/2023]
Abstract
IgA nephropathy (IgAN), the most prevalent primary glomerulonephritis worldwide, carries a considerable lifetime risk of kidney failure. Clinical manifestations of IgAN vary from asymptomatic with microscopic or intermittent macroscopic haematuria and stable kidney function to rapidly progressive glomerulonephritis. IgAN has been proposed to develop through a 'four-hit' process, commencing with overproduction and increased systemic presence of poorly O-glycosylated galactose-deficient IgA1 (Gd-IgA1), followed by recognition of Gd-IgA1 by antiglycan autoantibodies, aggregation of Gd-IgA1 and formation of polymeric IgA1 immune complexes and, lastly, deposition of these immune complexes in the glomerular mesangium, leading to kidney inflammation and scarring. IgAN can only be diagnosed by kidney biopsy. Extensive, optimized supportive care is the mainstay of therapy for patients with IgAN. For those at high risk of disease progression, the 2021 KDIGO Clinical Practice Guideline suggests considering a 6-month course of systemic corticosteroid therapy; however, the efficacy of systemic steroid treatment is under debate and serious adverse effects are common. Advances in understanding the pathophysiology of IgAN have led to clinical trials of novel targeted therapies with acceptable safety profiles, including SGLT2 inhibitors, endothelin receptor blockers, targeted-release budesonide, B cell proliferation and differentiation inhibitors, as well as blockade of complement components.
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Affiliation(s)
- Eleni Stamellou
- Department of Nephrology, School of Medicine, University of Ioannina, Ioannina, Greece
- Department of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Claudia Seikrit
- Department of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Sydney C W Tang
- Division of Nephrology, Department of Medicine, University of Hong Kong, Hong Kong, China
| | - Peter Boor
- Department of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany
- Department of Pathology, RWTH Aachen University, Aachen, Germany
| | - Vladimir Tesař
- Department of Nephrology, 1st Faculty of Medicine and General University Hospital, Charles University, Prague, Czech Republic
| | - Jürgen Floege
- Department of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jonathan Barratt
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Rafael Kramann
- Department of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany.
- Department of Internal Medicine, Nephrology and Transplantation, Erasmus Medical Center, Rotterdam, Netherlands.
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12
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Tesař V, Radhakrishnan J, Charu V, Barratt J. Challenges in IgA Nephropathy Management: An Era of Complement Inhibition. Kidney Int Rep 2023; 8:1730-1740. [PMID: 37705895 PMCID: PMC10496078 DOI: 10.1016/j.ekir.2023.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/01/2023] [Accepted: 06/12/2023] [Indexed: 09/15/2023] Open
Abstract
IgA nephropathy (IgAN) is the most common glomerular disease worldwide, with an estimated annual incidence of 25 per million adults. Despite optimized supportive care, some patients fail to achieve disease control and suffer progressive deterioration of kidney function. In this subpopulation of patients, the Kidney Disease: Improving Global Outcomes 2021 guidelines recommend consideration of corticosteroids; however, their use is associated with significant side effects. Ongoing clinical trials are expected to identify corticosteroid-sparing therapies to help improve treatment and prognosis for patients with IgAN. It has been well-documented that the complement system plays a significant role in IgAN pathogenesis, and several complement inhibitors are now entering late-stage clinical development. This review evaluates what we know about the role of complement in the pathophysiology of IgAN and considers how the availability of targeted complement inhibitors may impact future clinical practice. Key knowledge gaps are evaluated, and research opportunities are recommended to help guide clinical decision-making and optimize patient outcomes. Such gaps include evaluating the relative contribution of the alternative and lectin pathways to disease pathogenesis, and the importance of determining the dominant pathway driving IgAN progression. Continued research into the staining of complement proteins in kidney biopsies and identifying targeted biomarkers to assess disease progression and treatment responses will also be needed to support the implementation of newer therapies in clinical practice. Considering the future horizons for enhancing the care of patients with IgAN, tackling the outstanding challenges now will help prepare for the best possible future outcomes.
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Affiliation(s)
- Vladimir Tesař
- Department of Nephrology, Charles University, Prague, Czech Republic
| | | | - Vivek Charu
- Department of Pathology, Stanford University, Palo Alto, California, USA
| | - Jonathan Barratt
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
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13
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Barratt J, Lafayette RA, Zhang H, Tesar V, Rovin BH, Tumlin JA, Reich HN, Floege J. IgA Nephropathy: the Lectin Pathway and Implications for Targeted Therapy. Kidney Int 2023:S0085-2538(23)00395-2. [PMID: 37263354 DOI: 10.1016/j.kint.2023.04.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/30/2023] [Accepted: 04/14/2023] [Indexed: 06/03/2023]
Abstract
Many patients with IgA nephropathy (IgAN) progress to end-stage kidney disease even with optimal supportive care. An improved understanding of the pathophysiology of IgAN in recent years has led to the investigation of targeted therapies with acceptable tolerability that may address the underlying causes of IgAN or the pathogenesis of kidney injury. The complement system - particularly the lectin and alternative pathways of complement - have emerged as key mediators of kidney injury in IgAN and possible targets for investigational therapy. This review will focus on the lectin pathway. Examination of kidney biopsies has consistently shown glomerular deposition of mannan-binding lectin (one of six pattern-recognition molecules that activate the lectin pathway) together with IgA1 in up to 50% of patients with IgAN. Glomerular deposition of pattern-recognition molecules for the lectin pathway is associated with more severe glomerular damage and more severe proteinuria and hematuria. Emerging research suggests that the lectin pathway may also contribute to tubulointerstitial fibrosis in IgAN, and that collectin-11 is a key mediator of this association. This review summarizes the growing scientific and clinical evidence supporting the role of the lectin pathway in IgAN and examines the possible therapeutic role of lectin pathway inhibition for these patients.
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Affiliation(s)
| | | | - Hong Zhang
- Peking University Institute of Nephrology, Beijing, China
| | - Vladimir Tesar
- Charles University and General University Hospital, Prague, Czech Republic
| | - Brad H Rovin
- The Ohio State University Wexner Medical Center, Columbus OH, USA
| | | | - Heather N Reich
- University of Toronto and University Health Network, Toronto ON, Canada
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14
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Zhou W, Wang H, Sun S, Shen Y, Liu X, Zhen J, Zhang H, Duan F, Pan Y, Dong L. Association between glomerular C4d deposition, proteinuria, and disease severity in children with IgA nephropathy. Pediatr Nephrol 2023; 38:1147-1157. [PMID: 36102962 DOI: 10.1007/s00467-022-05725-9] [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] [Received: 04/26/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND C4d may be used as a marker to evaluate the condition and prognosis of adults with IgA nephropathy, but there have been few studies of children with IgA nephropathy. METHODS C4d immunohistochemical staining was performed on samples from children with IgA nephropathy with C1q-negative immunofluorescence. The clinical and pathological treatment and prognostic characteristics of children in the C4d-positive and -negative groups were compared. RESULTS A total of sixty-five children with IgA nephropathy were included in the study and were followed up for an average of 37 months. C4d was mainly deposited along the capillary loops. The urinary protein-to-creatinine ratio (UPCR) in the C4d-positive group was significantly higher than that in the C4d-negative group (3.97 vs. 0.81, P < 0.001), and the average integrated optical density value of each child was positively correlated with the UPCR (r = 0.441, P < 0.001). There was a significant difference in the proportions of children with mesangial hypercellularity (M1) (68.97% vs. 44.44%, P = 0.048) and segmental glomerulosclerosis (S1) (65.52% vs. 33.33%, P = 0.010) between the C4d-positive group and the C4d-negative group. The proportion of children who received immunosuppressants in the C4d-positive group was higher than that in the C4d-negative group (86.21% vs. 36.11%, P < 0.001). There was no significant difference in the proportion of children developing kidney failure between the two groups. CONCLUSION C4d was found to be associated with proteinuria, segmental lesions, and immunosuppressant treatment. Activation of the lectin pathway may reflect the severity of clinical and pathological manifestations of IgA nephropathy in children. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Weiran Zhou
- Department of Pediatric Nephrology, Rheumatology and Immunology, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital, Jinan, Shandong Province, China
| | - Hui Wang
- Department 2 of Nephrology, Beijing Children's Hospital Affiliated to Capital Medical University, National Center for Children's Health, Key Laboratory of Major Diseases in Children's Ministry of Education, Beijing Key Laboratory of Pediatric Chronic Kidney Diseases and Blood Purification, Beijing, China.
| | - Shuzhen Sun
- Department of Pediatric Nephrology, Rheumatology and Immunology, Shandong Provincial Hospital, Shandong University, Jinan, China
| | - Ying Shen
- Department 2 of Nephrology, Beijing Children's Hospital Affiliated to Capital Medical University, National Center for Children's Health, Key Laboratory of Major Diseases in Children's Ministry of Education, Beijing Key Laboratory of Pediatric Chronic Kidney Diseases and Blood Purification, Beijing, China
| | - Xuemei Liu
- Department of Pediatric Nephrology, Rheumatology and Immunology, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital, Jinan, Shandong Province, China
| | - Junhui Zhen
- Department of Pathology, Shandong University, Jinan, China
| | - Hongxia Zhang
- Department of Pediatric Nephrology, Rheumatology and Immunology, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital, Jinan, Shandong Province, China
| | - Fan Duan
- Department 2 of Nephrology, Beijing Children's Hospital Affiliated to Capital Medical University, National Center for Children's Health, Key Laboratory of Major Diseases in Children's Ministry of Education, Beijing Key Laboratory of Pediatric Chronic Kidney Diseases and Blood Purification, Beijing, China
| | - Yanyan Pan
- Department of Pediatric Nephrology, Rheumatology and Immunology, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital, Jinan, Shandong Province, China
| | - Linlin Dong
- Department of Pediatric Nephrology, Rheumatology and Immunology, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital, Jinan, Shandong Province, China
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15
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Tasar GE, Uzerk Kibar M, Dag O, Erdem Y, Ertoy Baydar D, Saglam A. Cytoplasmic WT1 in IgA nephropathy, an indicator of poor prognosis associated with mesangial/peri-mesangial C4d. Int Urol Nephrol 2023; 55:661-669. [PMID: 36036855 DOI: 10.1007/s11255-022-03357-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 08/21/2022] [Indexed: 01/10/2023]
Abstract
BACKGROUND We aimed to investigate the immuno-histochemical expression of C4d, ADAM10 and WT1 in kidney biopsies of immunoglobulin A nephropathy (IgAN) patients and correlate the findings with clinical, laboratory and histopathologic features in the hope of defining new parameters to better understand the pathogenesis of the disease, and predict prognosis. MATERIALS AND METHODS Paraffin-embedded kidney biopsy samples of 128 IgAN patients were immuno-histochemically treated with C4d and ADAM10/WT1 dual stain. Results were evaluated according to Oxford classification parameters, epidemiologic features, laboratory findings at presentation and clinical follow-up. RESULTS We observed C4d positivity in 40.6% of our patients, 25% of which was mesangial/peri-mesangial (m/pm) staining. Only m/pmC4d positivity statistically correlated with progression to end-stage renal disease (ESRD). M/pmC4d positive patients had statistically significantly higher baseline proteinuria levels, presence of crescents and > 25% segmental sclerosis of glomeruli. There was cytoplasmic staining of WT1 in 11.2% of cases. Presence of cWT1 correlated with m/pmC4d positivity and progression to ESRD. There was no glomerular ADAM10 detected and tubular expression of this protein did not relate to amount of tubular damage or other parameters. CONCLUSION This study is the first to show that cWT1is involved in IgAN and appears as an independent variable for worse prognosis.
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Affiliation(s)
- Gozde Elif Tasar
- Department of Pathology, Hacettepe University School of Medicine, Ankara, Turkey
| | - Muge Uzerk Kibar
- Department of Nephrology, Hacettepe University School of Medicine, Hacettepe University, Ankara, Turkey
| | - Osman Dag
- Department of Biostatistics, Hacettepe University School of Medicine, Ankara, Turkey
| | - Yunus Erdem
- Department of Nephrology, Hacettepe University School of Medicine, Hacettepe University, Ankara, Turkey
| | - Dilek Ertoy Baydar
- Department of Pathology, Hacettepe University School of Medicine, Ankara, Turkey
| | - Arzu Saglam
- Department of Pathology, Hacettepe University School of Medicine, Ankara, Turkey.
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16
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Maillard N, Mariat C. Urinary C4d in crescentic IgA nephropathy: expectancy and hope for a non-invasive lectin pathway biomarker. Nephrol Dial Transplant 2022; 37:2042-2043. [PMID: 35524692 DOI: 10.1093/ndt/gfac168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Nicolas Maillard
- Service de Néphrologie, Dialyse et Transplantation Rénale, Hôpital NORD, CHU de Saint-Etienne, France.,Groupe sur l'Immunité des Muqueuses et Agents Pathogènes, INSERM U1111, CIRI.,Université Jean Monnet, Saint-Etienne, Comue Universite De Lyon, France
| | - Christophe Mariat
- Service de Néphrologie, Dialyse et Transplantation Rénale, Hôpital NORD, CHU de Saint-Etienne, France.,Groupe sur l'Immunité des Muqueuses et Agents Pathogènes, INSERM U1111, CIRI.,Université Jean Monnet, Saint-Etienne, Comue Universite De Lyon, France
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17
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Yang X, Yuan Y, Shao X, Pang H, Che X, Cao L, Zhang M, Xu Y, Ni Z, Qi C, Wang Q, Mou S. C4d as a Screening Tool and an Independent Predictor of Clinical Outcomes in Lupus Nephritis and IgA Nephropathy. Front Med (Lausanne) 2022; 9:832998. [PMID: 35174193 PMCID: PMC8841560 DOI: 10.3389/fmed.2022.832998] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/03/2022] [Indexed: 01/10/2023] Open
Abstract
Background As an indispensable marker of complement cascades activation, C4d was confirmed of its crucial role in the pathogenesis of both lupus nephritis (LN) and IgA nephropathy (IgAN). While the studies directly comparing the diagnostic value, and outcomes predicting function of C4d between LN and IgAN are still absent. Methods A cohort of 120 LN patients, 120 IgAN patients who were diagnosed by renal biopsy between January 2015 and December 2017 and 24 healthy age matched controls were prospectively analyzed. The patients were followed till December 2020. The outcomes were adverse disease treatment response (disease relapse) and kidney disease progression event (decline of estimated glomerular filtration rate by more than 20% or end-stage kidney disease). The renal C4d deposition proportion and pattern were compared between IgAN and LN patients. In addition, the relationship between renal C4d deposition and disease subtypes, disease relapse as well as disease progression for LN and IgAN patients were also analyzed. Results The LN, IgAN patients and healthy controls were well matched in ages. The follow-up period was 38.5 (30.3–60.8) months for LN patients and 45.0 (30.5–57.0) months for IgAN patients. 78 patients (65.0%) with LN had renal C4d deposition, compared with only 39 IgAN patients (32.5%) with C4d deposition in renal tissues (P < 0.001). The LN patients shared different renal C4d distribution patterns with IgAN patients. Compared with IgAN patients, the C4d deposition in LN patients was significantly more in renal glomerulus (P < 0.001) and less in renal tubules (P = 0.003). For disease subtypes, renal C4d deposition was especially strong in class V membranous LN and IgAN with tubulointerstitial fibrosis (T1/T2) lesions. Renal C4d deposition was independently correlated with the disease relapse of LN patients (HR = 1.007, P = 0.040), and acted as an independent predictor of disease progression during the follow-up period for IgAN patients (HR = 1.821, P = 0.040). Conclusions Renal C4d distribution proportion and pattern differed between LN and IgAN patients. The presence of C4d in renal tissue acted as an independent predictor of relapse for LN patients and disease progression for IgAN patients.
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18
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Bruchfeld A, Magin H, Nachman P, Parikh S, Lafayette R, Potarca A, Miao S, Bekker P. C5a Receptor Inhibitor Avacopan in IgA Nephropathy – An Open-Label Pilot Study. Clin Kidney J 2022; 15:922-928. [PMID: 35498891 PMCID: PMC9050557 DOI: 10.1093/ckj/sfab294] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Indexed: 12/04/2022] Open
Abstract
Background Improvement of proteinuria as a marker for disease activity is associated with a better renal outcome in immunoglobulin A nephropathy (IgAN). Complement is an effector pathway in IgA-mediated kidney injury. Avacopan, a selective C5a receptor inhibitor, has previously shown efficacy in anti-neutrophil cytoplasmic antibody–associated vasculitis. The aim of this study was to evaluate the safety and efficacy of avacopan in patients with IgAN with persistent proteinuria despite a maximally tolerated dose of renin–angiotensin–aldosterone system blockade. The efficacy evaluation was based on the change in proteinuria. Methods This open-label pilot trial enrolled adult patients with biopsy-proven IgAN, urinary protein:creatinine ratio (UPCR) >1 g/g creatinine and an estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m2 or >45 mL/min/1.73 m2 if eGFR has not declined >10 mL/min/1.73 m2 over the previous 24 weeks. If the UPCR remained at >1 g/g creatinine after an 8-week run-in period, patients started avacopan 30 mg twice daily. The primary efficacy endpoint was the change in the slope of the UPCR from the 8-week run-in period to the slope in the 12-week avacopan dosing period. Results A total of 10 of 15 screened patients entered the run-in period. Seven patients with a UPCR >1 g/g creatinine received avacopan. Six of seven patients had numerical improvement in the UPCR during the avacopan treatment period, three of whom had a numerical improvement of ∼50% at week 12. At week 24, five of seven patients still showed numerical improvement in the UPCR compared with baseline. The urinary monocyte chemoattractant protein-1:creatinine ratio decreased numerically 30% by week 8, possibly reflecting the anti-inflammatory activity of avacopan. Avacopan was well tolerated. There was one serious adverse event of unstable angina, which was deemed to be unrelated to avacopan. Conclusions This short-term pilot study showed an improvement in the slope of the UPCR, with ∼50% improvement in three of seven patients with IgAN. Longer avacopan treatment duration may be indicated for maximal benefit.
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Affiliation(s)
- Annette Bruchfeld
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
- Department of Renal Medicine, Karolinska University Hospital and CLINTEC Karolinska Institutet, Stockholm, Sweden
| | - Hasan Magin
- Department of Renal Medicine, Karolinska University Hospital and CLINTEC Karolinska Institutet, Stockholm, Sweden
| | - Patrick Nachman
- Division of Renal Diseases and Hypertension, Minneapolis, University of Minnesota, USA
| | - Samir Parikh
- Ohio State Univ Wexner Medical Center, Nephrology, Columbus, OH, USA
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19
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Wang Z, Jiang Y, Chen P, Wang J, Zhang X, Huang B, Zhou X, Shi S, Liu L, Lv J, Zhang H. OUP accepted manuscript. Nephrol Dial Transplant 2022; 37:2119-2127. [PMID: 35104893 DOI: 10.1093/ndt/gfac024] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Zi Wang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Yuanyuan Jiang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
- Department of Nephrology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Pei Chen
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Jinwei Wang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Xue Zhang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Bo Huang
- Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xujie Zhou
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Sufang Shi
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Lijun Liu
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Jicheng Lv
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Hong Zhang
- Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- Research Units of Diagnosis and Treatment of Immune-Mediated Kidney Diseases, Chinese Academy of Medical Sciences, Beijing, China
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20
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Jiang Y, Zan J, Shi S, Hou W, Zhao W, Zhong X, Zhou X, Lv J, Zhang H. Glomerular C4d Deposition and Kidney Disease Progression in IgA Nephropathy: A Systematic Review and Meta-analysis. Kidney Med 2021; 3:1014-1021. [PMID: 34939010 PMCID: PMC8664744 DOI: 10.1016/j.xkme.2021.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background Glomerular deposition of C4d is a widely used biomarker for activation of the lectin pathway in the complement system and is reported to be associated with kidney progression in immunoglobulin A nephropathy (IgAN). The aim of this study was to evaluate whether glomerular C4d deposition, as a new biomarker, improves the prediction of kidney prognosis in IgAN. Study Design Systematic review and meta-analysis. Setting & Population Patients with biopsy-proven primary IgAN without age limitations. Selection Criteria for Studies: Cross-sectional or cohort studies reporting the prevalence of glomerular C4d deposition or evaluating its association with IgAN progression. Predictor Glomerular C4d deposition. Outcome Composite progression event of a >30% decline in estimated glomerular filtration rate or end-stage kidney disease. Results 12 studies with 1,251 patients were included. The prevalence of glomerular C4d deposition was 34% (95% CI, 27%-41%), with large heterogeneity (I2 = 86%; P < 0.001). Patients with C4d deposition had lower estimated glomerular filtration rates (mean difference [MD], −11.48; 95% CI, −18.27 to −4.70; P < 0.001) as well as higher urinary protein-creatinine ratios (MD, 0.87; 95% CI, 0.53-1.21; P < 0.001) or 24-hour urinary protein excretion (MD, 0.99; 95% CI, 0.50-1.47; P < 0.001) and higher risk for hypertension (relative risk [RR], 1.45; 95% CI, 1.06-1.99; P = 0.02) than patients without C4d deposition. Glomerular C4d deposition was associated with a high Oxford classification score, including M1, E1, S1, and T1/2 lesions (all P ≤ 0.006). Patients with C4d deposition had higher rates of use of renin-angiotensin system blockers and immunosuppressants. Glomerular C4d was found to be a risk factor for the composite kidney event (RR, 3.17; 95% CI, 2.29-4.40; P < 0.001; adjusted HR, 2.05; 95% CI, 1.53-2.76; P < 0.001) and end-stage kidney disease (RR, 4.37; 95% CI, 3.15-6.07; P < 0.001) without evidence of heterogeneity. Limitations The definition of positive C4d was not uniform and not all studies provided data about kidney outcomes. Conclusions Glomerular C4d deposition is associated with an adverse prognosis and may be a useful biomarker of disease prediction in IgAN.
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Affiliation(s)
- Yuanyuan Jiang
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China.,Department of Nephrology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Jincan Zan
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Sufang Shi
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Wanyin Hou
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Wenjing Zhao
- Department of Nephrology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Xuhui Zhong
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Xujie Zhou
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Jicheng Lv
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Hong Zhang
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
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21
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Freiwald T, Afzali B. Renal diseases and the role of complement: Linking complement to immune effector pathways and therapeutics. Adv Immunol 2021; 152:1-81. [PMID: 34844708 PMCID: PMC8905641 DOI: 10.1016/bs.ai.2021.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complement system is an ancient and phylogenetically conserved key danger sensing system that is critical for host defense against pathogens. Activation of the complement system is a vital component of innate immunity required for the detection and removal of pathogens. It is also a central orchestrator of adaptive immune responses and a constituent of normal tissue homeostasis. Once complement activation occurs, this system deposits indiscriminately on any cell surface in the vicinity and has the potential to cause unwanted and excessive tissue injury. Deposition of complement components is recognized as a hallmark of a variety of kidney diseases, where it is indeed associated with damage to the self. The provenance and the pathophysiological role(s) played by complement in each kidney disease is not fully understood. However, in recent years there has been a renaissance in the study of complement, with greater appreciation of its intracellular roles as a cell-intrinsic system and its interplay with immune effector pathways. This has been paired with a profusion of novel therapeutic agents antagonizing complement components, including approved inhibitors against complement components (C)1, C3, C5 and C5aR1. A number of clinical trials have investigated the use of these more targeted approaches for the management of kidney diseases. In this review we present and summarize the evidence for the roles of complement in kidney diseases and discuss the available clinical evidence for complement inhibition.
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Affiliation(s)
- Tilo Freiwald
- Immunoregulation Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Bethesda, MD, United States; Department of Nephrology, University Hospital Frankfurt, Goethe-University, Frankfurt am Main, Germany
| | - Behdad Afzali
- Department of Nephrology, University Hospital Frankfurt, Goethe-University, Frankfurt am Main, Germany.
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22
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Poppelaars F, Faria B, Schwaeble W, Daha MR. The Contribution of Complement to the Pathogenesis of IgA Nephropathy: Are Complement-Targeted Therapies Moving from Rare Disorders to More Common Diseases? J Clin Med 2021; 10:4715. [PMID: 34682837 PMCID: PMC8539100 DOI: 10.3390/jcm10204715] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 12/29/2022] Open
Abstract
Primary IgA nephropathy (IgAN) is a leading cause of chronic kidney disease and kidney failure for which there is no disease-specific treatment. However, this could change, since novel therapeutic approaches are currently being assessed in clinical trials, including complement-targeting therapies. An improved understanding of the role of the lectin and the alternative pathway of complement in the pathophysiology of IgAN has led to the development of these treatment strategies. Recently, in a phase 2 trial, treatment with a blocking antibody against mannose-binding protein-associated serine protease 2 (MASP-2, a crucial enzyme of the lectin pathway) was suggested to have a potential benefit for IgAN. Now in a phase 3 study, this MASP-2 inhibitor for the treatment of IgAN could mark the start of a new era of complement therapeutics where common diseases can be treated with these drugs. The clinical development of complement inhibitors requires a better understanding by physicians of the biology of complement, the pathogenic role of complement in IgAN, and complement-targeted therapies. The purpose of this review is to provide an overview of the role of complement in IgAN, including the recent discovery of new mechanisms of complement activation and opportunities for complement inhibitors as the treatment of IgAN.
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Affiliation(s)
- Felix Poppelaars
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen, University of Groningen, 9700 AD Groningen, The Netherlands; (B.F.); (M.R.D.)
| | - Bernardo Faria
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen, University of Groningen, 9700 AD Groningen, The Netherlands; (B.F.); (M.R.D.)
- Nephrology and Infectious Disease R&D Group, INEB, Institute of Investigation and Innovation in Health (i3S), University of Porto, 4200-135 Porto, Portugal
| | - Wilhelm Schwaeble
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK;
| | - Mohamed R. Daha
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen, University of Groningen, 9700 AD Groningen, The Netherlands; (B.F.); (M.R.D.)
- Department of Nephrology, Leiden University Medical Center, University of Leiden, 2300 RC Leiden, The Netherlands
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23
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Is complement the main accomplice in IgA nephropathy? From initial observations to potential complement-targeted therapies. Mol Immunol 2021; 140:1-11. [PMID: 34601376 DOI: 10.1016/j.molimm.2021.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/01/2021] [Accepted: 09/17/2021] [Indexed: 12/22/2022]
Abstract
IgA Nephropathy (IgAN) is the main cause of primary glomerulonephritis, globally. This disease is associated with a wide range of clinical presentations, variable prognosis and a spectrum of histological findings. More than fifty years after its first description, this heterogeneity continues to complicate efforts to understand the pathogenesis. Nevertheless, involvement of the complement system in IgAN was identified early on. Dysfunction of the immunoglobulin A (IgA) system, the principal offender in this disease, including modification of isoforms and glycoforms of IgA1, the nature of immune complexes and autoantibodies to galactose deficient IgA1 might all be responsible for complement activation in IgAN. However, the specific mechanisms engaging complement are still under examination. Research in this domain should allow for identification of patients that may benefit from complement-targeted therapy, in the foreseeable future.
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24
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Medjeral-Thomas NR, Cook HT, Pickering MC. Complement activation in IgA nephropathy. Semin Immunopathol 2021; 43:679-690. [PMID: 34379175 PMCID: PMC8551128 DOI: 10.1007/s00281-021-00882-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 07/23/2021] [Indexed: 11/25/2022]
Abstract
IgA nephropathy pathogenesis is incompletely understood, and this limits the development of disease-specific biomarkers and effective therapies. Evidence of complement activity in IgA nephropathy is well established. However, a growing body of research indicates complement activity is an important contributor to IgA nephropathy pathology. In particular, multiple associations have been identified between complement alternative, lectin and terminal pathway proteins and IgA nephropathy severity. Recently, we have also gained insight into possible mechanisms that could link glomerular IgA deposition, complement activity, glomerular inflammation and disease severity. Ongoing clinical trials of therapeutic complement inhibitors will provide insight into the importance of complement activity to IgA nephropathy pathogenesis. Further research into mechanisms of complement activity is essential to improving our understanding and management of patients with IgA nephropathy.
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Affiliation(s)
- Nicholas R Medjeral-Thomas
- Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College London, London, W12 0NN, UK.
| | - H Terence Cook
- Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College London, London, W12 0NN, UK
| | - Matthew C Pickering
- Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College London, London, W12 0NN, UK
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25
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Trimarchi H, Coppo R. Glomerular endothelial activation, C4d deposits and microangiopathy in immunoglobulin A nephropathy. Nephrol Dial Transplant 2021; 36:581-586. [PMID: 31755918 DOI: 10.1093/ndt/gfz241] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Indexed: 11/14/2022] Open
Abstract
Immunoglobulin A nephropathy (IgAN) is considered as mesangiopathy since it initiates in the mesangium; however, other glomerular components are involved and the glomerular capillary wall offers the first contact to circulating macromolecular IgA1. Acute and active forms of IgAN are associated with endocapillary hypercellularity and vascular damage of various degrees, in severe cases with microangiopathy (MA) without or with thrombosis [thrombotic microangiopathy (TMA)]. Vascular damage activates complement and coagulation cascades. A defective complement regulation has recently been detected in active and progressive cases of IgAN. C4d deposits in renal biopsies have been found to be an early risk factor. These observations have raised interest in manifestation of MA and TMA in progressive cases of IgAN. MA-TMA lesions have been found in various percentages (2-53%) of patients with IgAN according to patients' selection and pathology definition of TMA. The association with hypertension (HTN) was so strong that it led to the hypothesis that MA/TMA in IgAN was a mere consequence of severe HTN. Old and new clinical and experimental data indicate that in IgAN the interaction of the glomerular capillary wall with immune reactants and complement uncontrolled activation leading to C4b deposits favours the development of MA-TMA, which plays a role in progression and renal function decline. The central role of complement activation is relevant also for the new therapeutic interventions offered by the pharma.
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Affiliation(s)
- Hernán Trimarchi
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Rosanna Coppo
- Fondazione Ricerca Molinette, Regina Margherita Hospital, Turin, Italy
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26
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Worawichawong S, Plumworasawat S, Liwlompaisan W, Sumethkul V, Phakdeekitcharoen B, Udomsubpayakul U, Chalermsanyakorn P, Kitiyakara C. Distribution pattern of mesangial C4d deposits as predictor of kidney failure in IgA nephropathy. PLoS One 2021; 16:e0252638. [PMID: 34081719 PMCID: PMC8174712 DOI: 10.1371/journal.pone.0252638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 05/20/2021] [Indexed: 02/05/2023] Open
Abstract
Mesangial C4d deposits have been associated with worse outcomes in Western patients with IgA nephropathy (IgAN), but there is limited data in Asians. Previously, a high proportion of stained glomeruli was often required for the classification of C4d positive (C4d+ve). Positive staining in lower proportion of staining would be classified as C4d-ve. This retrospective study evaluated the prognostic value of C4d+ve using a less stringent definition (one C4d+ve glomerulus) in Thai patients with IgAN (n = 120). Baseline findings and outcomes were compared between those with more extensive C4d staining patterns and those with more restricted staining. Clinico-pathologic parameters and risk for kidney outcomes (kidney failure or decline GFR50%) were compared between C4d+ve versus C4d-ve, and between different patterns: Focal (< 50%) versus Diffuse (≥ 50% of glomeruli); or Global (≥ 50) versus Segmental (< 50% of mesangial area). The hazard ratios were estimated using Cox proportional hazard models for Model 1 (Oxford score+ C4d) and Model 2 (Model 1+ clinical factors). C4d+ve (n = 81) had lower eGFR, more global sclerosis, and interstitial fibrosis than C4d-ve at baseline. The 5-year kidney survival for C4d+ve was lower (53.7%) than C4d-ve (89.7%); P = 0.0255. By univariate analysis, T1, T2, C4d+ve, eGFR<60, proteinuria were predictors of kidney outcome. By multivariate analysis, proteinuria, T1, T2 and C4d+ve were independent predictors (Model 2 HR (95% CI) C4d+ve: 3.24 (1.09-9.58), p = 0.034). Segmental had lower eGFR, higher tubulointerstitial fibrosis, and segmental sclerosis compared to Global pattern. Clinicopathological parameters were not different between Focal and Diffuse patterns. Outcomes were similar between staining patterns. In conclusion, C4d staining may be a valuable marker of poor prognosis in Asian patients with IgAN. Less stringent criteria for C4d+ve should be considered as no differences in outcomes were observed between more extensive staining with less extensive patterns. More studies are needed to identify the optimum criteria for C4d+ve.
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Affiliation(s)
- Suchin Worawichawong
- Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sirithep Plumworasawat
- Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wisit Liwlompaisan
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Vasant Sumethkul
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Bunyong Phakdeekitcharoen
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Umaporn Udomsubpayakul
- Section for Clinical Epidemiology and Biostatistics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Panus Chalermsanyakorn
- Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Chagriya Kitiyakara
- Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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27
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Shima Y, Nakanishi K, Mukaiyama H, Tanaka Y, Wada T, Tanaka R, Kaito H, Nozu K, Sako M, Iijima K, Yoshikawa N. Clinicopathological significance of glomerular capillary IgA deposition in childhood IgA nephropathy. Pediatr Nephrol 2021; 36:899-908. [PMID: 33011820 DOI: 10.1007/s00467-020-04772-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/26/2020] [Accepted: 09/09/2020] [Indexed: 12/29/2022]
Abstract
BACKGROUND IgA nephropathy (IgAN) is characterized by predominant mesangial IgA deposition. Some patients with IgAN demonstrate IgA deposition in glomerular peripheral capillaries (cap-IgA). The clinicopathological significance of cap-IgA remains incompletely investigated in children. METHODS We retrospectively analyzed 503 consecutive cases of biopsy-proven childhood IgAN between July 1976 and June 2013 to compare clinical and pathological features between IgAN patients with and without cap-IgA. RESULTS Among the 503 patients, 30 (6.0%) had cap-IgA. We found significant differences in proteinuria (2.0 vs. 0.5 g/day/m2, p < 0.0001), time from onset to kidney biopsy (2.2 vs. 8.3 months, p < 0.0001), and rate of proteinuria remission after treatment (23.3% vs. 48.0%, p = 0.007) between both groups. Pathological analysis revealed significant differences in M1 (83.3% vs. 56.0%, p = 0.002), ratio of subendothelial electron dense deposits (EDDs, 58.6% vs. 16.5%, p < 0.0001) and subepithelial EDDs (48.3% vs. 16.5%, p = 0.0001), and glomerular basement membrane (GBM) lysis (58.6% vs. 27.1%, p = 0.0006) between both groups. More than half of cap-IgA patients (17/30, 56.7%), whereas only 26.2% of non-cap-IgA patients (124/473), were treated with immunosuppressive treatments. Six of 30 cases (20%) with cap-IgA reached glomerular filtration rate (GFR) categories G3a-G5 (estimated GFR < 60 ml/min/1.73 m2) at most recent observation (mean observation period: 7.0 ± 4.0 years). According to Kaplan-Meier analysis, patients with cap-IgA had significantly lower kidney survival curves than non-cap-IgA patients (72.8% vs. 97.2% at 10 years, p < 0.0001). CONCLUSIONS Cap-IgA is associated with acute inflammation with GBM changes, resulting in refractory heavier proteinuria. Cap-IgA may represent a poor prognostic factor.
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Affiliation(s)
- Yuko Shima
- Department of Pediatrics, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Koichi Nakanishi
- Department of Pediatrics, Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, 207 Uehara Nishihara-cho, Nakagami-gun, Okinawa, 903-0125, Japan.
| | - Hironobu Mukaiyama
- Department of Pediatrics, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Yu Tanaka
- Department of Pediatrics, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Takuzo Wada
- Department of Pediatrics, Wakayama Medical University, Wakayama City, Wakayama, Japan
| | - Ryojiro Tanaka
- Department of Nephrology, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan
| | - Hiroshi Kaito
- Department of Nephrology, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Mayumi Sako
- Division for Clinical Trials, Clinical Research Center, National Center for Child Health and Development, Tokyo, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Norishige Yoshikawa
- Clinical Research Center, Takatsuki General Hospital, Takatsuki City, Osaka, Japan
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28
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Wu D, Li X, Yao X, Zhang N, Lei L, Zhang H, Tang M, Ni J, Ling C, Chen Z, Chen X, Liu X. Mesangial C3 deposition and serum C3 levels predict renal outcome in IgA nephropathy. Clin Exp Nephrol 2021; 25:641-651. [PMID: 33620604 DOI: 10.1007/s10157-021-02034-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 02/12/2021] [Indexed: 12/26/2022]
Abstract
BACKGROUND Complement activation plays an important role in the pathogenesis of IgA nephropathy (IgAN). We aimed to evaluate the relationship between mesangial C3 deposition and histologic lesions and to investigate the role of mesangial C3 deposition and serum C3 reduction in predicting renal outcome in IgAN children. METHODS We performed a retrospective cohort study in children with biopsy-proven IgAN. Mesangial C3 deposition (< 2+ vs. ≥ 2+) was detected by the immunofluorescence. Histopathologic kidney grades were determined by the Oxford classification. A decreased serum C3 concentration (hypoC3) was defined when C3 < 90 mg/dl. The endpoint was composite kidney outcome with either a 30% decline in glomerular filtration rates from baseline or kidney failure during the follow-up period. RESULTS A total of 98 children were analyzed. Mesangial hypercellularity (M) was an independent factor associated with mesangial C3 deposition (HR 3.267; 95% CI 1.028-10.389; P = 0.045). After a median follow-up period of 25 months (interquartile range 18-36 months), 6 (6.1%) children reached the endpoint. Compared with other children, a significantly higher proportion of children with composite kidney outcomes had mesangial C3 deposition ≥ 2+ and hypoC3 (3.4% versus 27.3%, P = 0.002). After adjustment for clinicopathologic risk factors, mesangial C3 deposition ≥ 2+ and hypoC3 were associated with renal outcome (HR 9.772; 95% CI 1.264-75.518; P = 0.029). CONCLUSION Mesangial C3 deposition was associated with M in IgAN. Mesangial C3 deposition and hypoC3 were risk factors for renal outcome in children with IgAN.
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Affiliation(s)
- Dan Wu
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Xueqian Li
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Xingfeng Yao
- Department of Pathology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Nan Zhang
- Department of Pathology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Lei Lei
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Hejia Zhang
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Mengmeng Tang
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Jie Ni
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Chen Ling
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Zhi Chen
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Xiangmei Chen
- Department of Nephrology, State Key Laboratory of Kidney Diseases, Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, National Clinical Research Center for Kidney Diseases, 28th Fuxing Road, Beijing, 100853, China
| | - Xiaorong Liu
- Department of Nephrology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China.
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29
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Medrano AS, Muijsemberg A, Wimbury D, Martin M, Jatem E, González J, Colás-Campás L, García-Carrasco A, Martínez C, Barratt J. Relationship between IgA1 lectin-binding specificities, mesangial C4d deposits and clinical phenotypes in IgA nephropathy. Nephrol Dial Transplant 2020; 37:318-325. [PMID: 33315098 DOI: 10.1093/ndt/gfaa356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND AND OBJECTIVES The reason why mesangial C4d deposits are detected in only certain biopsies of IgA nephropathy remains unclear. We analyse the association between IgA glycosylation patterns, mesangial C4 deposition and clinical phenotypes in IgA nephropathy.Design, setting, participants and measurements: This cross-sectional study included 145 patients with idiopathic IgA nephropathy. We measured the serum levels of three different IgA1 lectin-binding specificities, using enzyme-linked-immunosorbent assays with and without treatment with neuraminidase, and we analysed the relationship between these glycoforms, C4d mesangial deposits and clinical phenotypes. RESULTS C4d-positive vs Cd4-negative patients had higher proteinuria (median: 3.1 g/g [0.9-4.2] vs. 1.8 g/g [1-2.2]; p = 0.000), hematuria (223 cel/µL [32-278] vs 99 cel/µL [25-186], p = 0.000), and higher levels of IgA binding to neuraminidase untreated Helix Aspersa (HA IgA1 neu-) (150.6 ± 52 U vs 96.2 ± 64.1 U, p = 0.000), neuraminidase untreated Helix Pomatia (HPA IgA1 neu-) (0.34 ± 0.15 vs 0.27 ± 0.13p = 0.04), Triticum vulgaris (TV IgA1) (85.1 ± 31.7 vs42.2 ± 26.9p = 0.000), and Canavalia ensiformis (ConA IgA1) (32.5 ± 18 U vs 16.7 ± 9.38 U, p = 0.000). The levels of HA IgA1 neu-, HPA IgA1 neu-, TV IgA1 and ConA IgA1 were all associated with the mesangial deposition of C4d, extracapillary proliferation and acute kidney injury. In ROC curves, HA IgA1 neu-, HPA IgA1 neu-, TV IgA1 and ConA IgA1 significantly discriminated between C4d positive ad C4d-negative biopsies. In logistic models, TVIgA1 and ConAIgA1 were the only independent predictors of mesangial C4d deposits. CONCLUSIONS In IgA nephropathy, the severity of the disease is associated with the level of IgA exposing N-Acetyl-D-Galactosamine, N-Acetyl-D-Glucosamine or mannose whereas C4d deposits are only associated with elevated levels of IgA1 glycoforms exhibiting glycan residues with specificity for mannose and N-Acetyl-D-Glucosamine binding lectins.
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Affiliation(s)
- Alfons Segarra Medrano
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain
| | - Andrea Muijsemberg
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain.,Universitat Autònoma de Barcelona, Spain
| | - David Wimbury
- The Mayer IgA Nephropathy Laboratories, University of Leicester, UK
| | - Marisa Martin
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain
| | - Elias Jatem
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain
| | - Jorge González
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain
| | - Laura Colás-Campás
- Grupo de Neurociencias Clínicas, Institut de Recerca Biomèdica de Lleida (IRBLleida). Universitat de Lleida (UdL), Lleida, Spain
| | - Alicia García-Carrasco
- Vascular and Renal Translational Research Group, Institut de Recerca Biomèdica de Lleida (IRBLleida). Universitat de Lleida (UdL), Lleida, Spain
| | - Cristina Martínez
- Servicio de Nefrología. Hospital Arnau de Vilanova, Lleida, Spain.,Institut de Recerca Biomèdica, Lleida, Spain.,Vascular and Renal Translational Research Group, Institut de Recerca Biomèdica de Lleida (IRBLleida). Universitat de Lleida (UdL), Lleida, Spain
| | - Jonathan Barratt
- The Mayer IgA Nephropathy Laboratories, University of Leicester, UK
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Glomerular C4d in Post-Transplant IgA Nephropathy is associated with decreased allograft survival. J Nephrol 2020; 34:839-849. [PMID: 33306182 PMCID: PMC8192385 DOI: 10.1007/s40620-020-00914-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/11/2020] [Indexed: 11/23/2022]
Abstract
Background Glomerulonephritis (GN), including post-transplant IgAN (post-Tx IgAN) is an important contributor to decreased long-term allograft survival. The immunopathological detection of the complement degradation product C4d in glomeruli (C4dG) has been recently described as a risk factor in native kidney IgAN, however little is known about C4dG deposition in post-Tx IgAN. We hypothesized that glomerular C4d may indicate a more aggressive disease course and worse allograft survival in patients with post-Tx IgAN. Methods In this retrospective study we assessed the presence and clinical relevance of C4dG in patients with post-transplant IgAN. We analyzed 885 renal allograft recipients, including 84 patients with post-transplant GN. All patients were transplanted between January 1999 and April 2006 and underwent at least one biopsy for differnt causes. The primary endpoint was death-censored graft survival, with a median follow-up of 9.6 (IQR 3.8–13.2) years. Results The prevalence of post-Tx GN was 9.5%. Twenty-seven patients with post-Tx IgAN were included. C4dG positive patients (N = 18, 66.7%) had significantly worse allograft survival compared to C4dG negative post-Tx IgAN patients and patients without post-Tx IgAN [C4dG positive: 27.8% vs. 55.6% and 66.0%; log-rank: p = 0.01]. C4dG remained a significant risk factor (HR 2.22, 95% CI 1.27–3.87) for allograft loss even after adjustment for T cell mediated rejection (TCMR) and antibody mediated rejection. Conclusion Glomerular C4d deposition is an independent risk factor for worse graft-survival in patients with post-Tx IgAN, even after adjusting for other risk factors such as antibody mediated rejection. Assessment of glomerular C4d deposition may provide a valuable prognostic risk assessment tool to identify high risk patients in post-Tx IgAN. Graphic abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s40620-020-00914-x) contains supplementary material, which is available to authorized users.
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Complement-mediated kidney diseases. Mol Immunol 2020; 128:175-187. [DOI: 10.1016/j.molimm.2020.10.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/16/2020] [Accepted: 10/19/2020] [Indexed: 12/19/2022]
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Neves PDMDM, Souza RA, Torres FM, Reis FA, Pinheiro RB, Dias CB, Yu L, Woronik V, Furukawa LS, Cavalcante LB, de Almeida Araújo S, Wanderley DC, Malheiros DM, Jorge LB. Evidences of histologic thrombotic microangiopathy and the impact in renal outcomes of patients with IgA nephropathy. PLoS One 2020; 15:e0233199. [PMID: 33147224 PMCID: PMC7641451 DOI: 10.1371/journal.pone.0233199] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 09/30/2020] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION IgA nephropathy (IgAN) is the most common primary glomerulopathy worldwide. According to the Oxford Classification, changes in the kidney vascular compartment are not related with worse outcomes. This paper aims to assess the impact of thrombotic microangiopathy (TMA) in the outcomes of Brazilian patients with IgAN. MATERIALS AND METHODS Analysis of clinical data and kidney biopsy findings from patients with IgAN to assess the impact of TMA on renal outcomes. RESULTS The majority of the 118 patients included were females (54.3%); mean age of 33 years (25;43); hypertension and hematuria were observed in 67.8% and 89.8%, respectively. Median creatinine: 1.45mg/dL; eGFR: 48.8ml/min/1.73m2; 24-hour proteinuria: 2.01g; low serum C3: 12.5%. Regarding to Oxford Classification: M1: 76.3%; E1: 35.6%; S1: 70.3%; T1/T2: 38.3%; C1/C2: 28.8%. Average follow-up: 65 months. Histologic evidence of TMA were detected in 21 (17.8%) patients and those ones presented more frequently hypertension (100% vs. 61%, p <0.0001), hematuria (100% vs 87.6%, p = 0.0001), worse creatinine levels (3.8 vs. 1.38 mg/dL, p = 0.0001), eGFR (18 vs. 60 ml/min/1.73m2), p = 0.0001), low serum C3 (28.5% vs. 10.4%, p = 0.003), lower hemoglobin levels (10.6 vs. 12.7g/dL, p<0.001) and platelet counts (207,000 vs. 267,000, p = 0.001). Biopsy findings of individuals with TMA revealed only greater proportions of E1 (68% vs. 32%, p = 0.002). Individuals with TMA were followed for less time (7 vs. 65 months, p<0.0001) since they progressed more frequently to chronic kidney disease (CKD) requiring kidney replacement therapy (KRT) (71.4% vs. 21,6%, p<0.0001). Male sex, T1/T2, and TMA were independently associated with progression to CKD-KRT. CONCLUSIONS In this study patients with TMA had worse clinical manifestations and outcomes. In terms of histologic evidence, E1 distinguished patients with TMA from other patients. Further studies are necessary to analyze the impact of vascular lesions on IgAN prognosis.
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Affiliation(s)
| | - Rafael A. Souza
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Fábio M. Torres
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Fábio A. Reis
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Rafaela B. Pinheiro
- Pathology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Cristiane B. Dias
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Luis Yu
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Viktoria Woronik
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Luzia S. Furukawa
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Lívia B. Cavalcante
- Pathology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Stanley de Almeida Araújo
- Nephropathology Institute, Belo Horizonte, MG, Brazil
- Pathology Division, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - David Campos Wanderley
- Nephropathology Institute, Belo Horizonte, MG, Brazil
- Pathology Division, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Denise M. Malheiros
- Pathology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
| | - Lectícia B. Jorge
- Nephrology Division, University of São Paulo, School of Medicine, São Paulo, SP, Brazil
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Gutiérrez E, Carvaca-Fontán F, Luzardo L, Morales E, Alonso M, Praga M. A Personalized Update on IgA Nephropathy: A New Vision and New Future Challenges. Nephron Clin Pract 2020; 144:555-571. [PMID: 32818944 DOI: 10.1159/000509997] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 07/08/2020] [Indexed: 11/19/2022] Open
Abstract
IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world among patients undergoing renal biopsy. Approximately 30% of patients with IgAN develop end-stage kidney disease 20 years after renal biopsy. It is a glomerulopathy with a very broad clinical presentation, making it difficult to stratify and treat. IgAN is characterized by dysregulation of the immune system, which causes an abnormal synthesis of IgA1 that is deglycosylated causing its mesangial deposition. IgAN pathogenesis is incompletely understood; the current multi-hit hypothesis of IgAN pathogenesis does not explain the range of glomerular inflammation and renal injury associated with mesangial IgA deposition. Although associations between IgAN and glomerular and circulating markers of complement activation are established, the mechanism of complement activation and contribution to glomerular inflammation and injury are not defined. On the other hand, the renal-gut connection can also play an important role in the pathogenesis of IgAN with possible therapeutic implications. In order to standardize the histological findings, the Oxford Classification has allowed clarifying renal lesions that confer potential risk of progression. Currently, except for the blockade of the renin-angiotensin-aldosterone system, no other therapies are available in clinical setting for the treatment of IgAN, although the range of new drugs under investigation is extensive. The incorporation in the next trials of clinical parameters such as the amount of hematuria and histological lesions may allow more personalized therapeutic approaches. To summarize, in recent years, several important efforts have taken place in the understanding of IgAN, but still, further studies are warranted to elucidate the best therapeutic strategies according to the risk to improve the prognosis of this entity.
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Affiliation(s)
- Eduardo Gutiérrez
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain, .,Department of Nephrology, Hospital Universitario 12 de Octubre, Madrid, Spain,
| | - Fernando Carvaca-Fontán
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Leonella Luzardo
- Department of Nephrology and Pathophysiology, School of Medicine, Universidad de la República, Montevideo, Uruguay
| | - Enrique Morales
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Marina Alonso
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Pathological Anatomy, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Manuel Praga
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Medicine, Universidad Complutense de Madrid, Madrid, Spain
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Faria B, Canão P, Cai Q, Henriques C, Matos AC, Poppelaars F, Gaya da Costa M, Daha MR, Silva R, Pestana M, Seelen MA. Arteriolar C4d in IgA Nephropathy: A Cohort Study. Am J Kidney Dis 2020; 76:669-678. [PMID: 32439421 DOI: 10.1053/j.ajkd.2020.03.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/10/2020] [Indexed: 12/20/2022]
Abstract
RATIONALE & OBJECTIVE Glomerular C4d (C4dG) as an indicator of the lectin pathway of complement activation in immunoglobulin A nephropathy (IgAN) has been associated with more severe kidney damage. Recent studies have suggested that vascular lesions in IgAN biopsy specimens with complement deposition are also associated with disease progression. We aimed to study the clinical significance of arteriolar C4d (C4dA) in IgAN kidney biopsy tissue. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS Kidney biopsy specimens from 126 adults with IgAN diagnosed by Oxford classification criteria were stained using immunohistochemistry and classified according to C4dG and C4dA deposition. Additionally, vascular lesions including acute and chronic microangiopathy, arteriolar hyalinosis, and arterial intima fibrosis were characterized. PREDICTOR C4dA. OUTCOME Progressive kidney disease, defined as a decline in estimated glomerular filtration rate by≥50% or occurrence of kidney failure. ANALYTICAL APPROACH The association of C4dA and C4dG with baseline clinical and histologic characteristics, as well as progressive kidney disease, were assessed with survival analysis using multivariable Cox regression analysis. RESULTS C4dA was identified in 21 (17%) patients and was associated with mean arterial pressure, arterial intima fibrosis, and chronic microangiopathy. C4dA was also significantly associated with C4dG and both were associated with progressive kidney disease. In regression analysis, C4dA remained significantly associated with progressive kidney disease after adjusting for other significant predictors, including baseline estimated glomerular filtration rate, mean arterial pressure, and the presence of crescents. LIMITATIONS Findings based on the retrospective evaluation of a single center's experience, limited number of events, a small number of patients with a broad range of kidney disease stages, and use of immunohistochemistry rather than immunofluorescence to detect C4d. CONCLUSIONS C4dA is a potential biomarker for disease progression in IgAN. It should be further investigated in larger cohorts to determine the value of C4dA in improving prediction of IgAN disease progression.
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Affiliation(s)
- Bernardo Faria
- Nephrology and Infectious Disease R&D Group, INEB, Institute of Investigation and Innovation in Health (i3S), University of Porto, Porto, Portugal; Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
| | - Pedro Canão
- Department of Anatomic Pathology, Centro Hospitalar Universitário São João, Porto
| | - Qingqing Cai
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Carla Henriques
- School of Technology and Management, Polytechnic Institute of Viseu, Viseu; Centre for Mathematics, University of Coimbra (CMUC), Coimbra
| | - Ana Cristina Matos
- School of Technology and Management, Polytechnic Institute of Viseu, Viseu; Centre for Research in Digital Services and CISeD, Viseu, Portugal
| | - Felix Poppelaars
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Mariana Gaya da Costa
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Mohamed R Daha
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Department of Nephrology, University of Leiden, Leiden University Medical Center, Leiden, the Netherlands
| | - Roberto Silva
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Manuel Pestana
- Nephrology and Infectious Disease R&D Group, INEB, Institute of Investigation and Innovation in Health (i3S), University of Porto, Porto, Portugal; Division of Nephrology, Centro Hospitalar Universitário São João and Department of Medicine, Faculty of Medicine of Porto University, Porto, Portugal
| | - Marc A Seelen
- Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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Complement activation is associated with crescent formation in IgA nephropathy. Virchows Arch 2020; 477:565-572. [PMID: 32300880 DOI: 10.1007/s00428-020-02800-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/11/2020] [Accepted: 03/18/2020] [Indexed: 12/21/2022]
Abstract
IgA nephropathy (IgAN) is common chronic glomerulonephritis with variable prognosis, ranging from minor urinary abnormalities to end-stage renal disease. The revised Oxford classification of IgAN explains that cellular/fibrocellular crescents are associated with poor renal prognosis, proposing an extension to the MEST-C score. C3 immunofluorescent staining follows a distribution similar to IgA staining. Therefore, complement activation was reported to play a pivotal role in IgAN pathogenesis. This study included 132 IgAN patients diagnosed by renal biopsies. The clinical parameters at the time of the biopsies were obtained from patient data records. We classified the patients into C ≥ 1 and C0 groups, and compared clinical, light microscopic, and immunofluorescent features. In the C ≥ 1 group, 2 (1.5%) and 31 (23.5%) patients were assigned to C2 and C1, respectively. The remaining 99 patients (75%) were classified as C0. The C ≥ 1 group had lower average age and rate of hypertension, and higher score of urinary occult blood and E score. The C ≥ 1 group had significantly higher average immunofluorescence scores for IgA, C5b-9, mannose-associated serine protease (MASP) 1/3, MASP2, properdin, factor B, and kappa. The steroid use rate was significantly higher in the C ≥ 1 group. During the follow-up period of 2.90 years on average, the rate of renal dysfunction was not significantly different between groups. Crescent formation in IgAN was associated with activation of the lectin and alternative pathways. The C ≥ 1 group had significantly increased use of steroids, which probably caused comparable renal function during the follow-up period.
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Predictive value of mesangial C3 and C4d deposition in IgA nephropathy. Clin Immunol 2019; 211:108331. [PMID: 31899330 DOI: 10.1016/j.clim.2019.108331] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 12/24/2019] [Accepted: 12/30/2019] [Indexed: 12/22/2022]
Abstract
We aimed to determine the relative contribution of each complement (C3 and C4d) deposition to the progression of IgA nephropathy (IgAN). We enrolled a total of 380 patients with biopsy-confirmed IgAN. Mesangial deposition of C3(<2+ vs. ≥2+) and C4d(positive vs. negative) was evaluated by immunofluorescence staining and immunohistochemistry, respectively. Study endpoint was the composite of a 30% decline in eGFR or ESRD. The risk of reaching the primary outcome was significantly higher in patients having C3 ≥ 2+ and C4d(+) than in corresponding counterparts. Adding C3 deposition to clinical data acquired at kidney biopsy modestly increased the area under the receiver-operating characteristic curve, net reclassification improvement, and integrated discrimination improvement (IDI); adding C4d increased IDI only. In conclusion, mesangial C3 and C4d deposition was an independent risk factor for progression of IgAN. C3 showed better predictability than C4d, suggesting that lectin pathway alone has limited clinical prognostic value.
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Drachenberg CB, Papadimitriou JC, Chandra P, Haririan A, Mendley S, Weir MR, Rubin MF. Epidemiology and Pathophysiology of Glomerular C4d Staining in Native Kidney Biopsies. Kidney Int Rep 2019; 4:1555-1567. [PMID: 31890997 PMCID: PMC6933466 DOI: 10.1016/j.ekir.2019.07.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/22/2022] Open
Abstract
Introduction Routine C4d staining in renal transplantation has stimulated its use in kidney biopsies with glomerulonephritis (GN). Methodical description on staining patterns in the native kidney is not available. Methods We retrospectively evaluated C4d staining in formalin-fixed paraffin-embedded sections from 519 native kidney biopsies (bx) with and without glomerular disease. Results Strong C4d staining was consistently present in immune-complex GN, including lupus nephritis (LN) (n = 68), membranous GN (n = 24), membranoproliferative glomerulonephritis (MPGN) pattern (n = 22), fibrillary GN (n = 3), and proliferative GN with monoclonal IgG (n = 3). C4d stained all cases of postinfectious GN (n = 7) amyloidosis (n = 20) and C1q GN (n = 3). In contrast, IgA nephropathy (IgAN) (n = 34), was negative in 62% of bx, with the rest staining variably. The E1 Oxford classification score correlated with capillary wall C4d staining (P = 0.05). C4d marked the glomerular and arteriolar lesions in thrombotic microangiopathy (TMA; n = 16), the glomerular sclerotic segments in focal segmental glomerulosclerosis (FSGS; n = 77), and marked areas of necrosis in crescentic GN (n = 21). In diabetic glomerulopathy (n = 70), C4d marked advanced insudative lesions but was negative otherwise. C4d weakly stained the mesangium, or was negative in normal biopsies (n = 13), minimal change disease (MCD; n = 21), thin basement membrane disease (n = 20), Alport (n = 3), IgM nephropathy (n = 2), C3 glomerulopathy (n = 5), acute interstitial nephritis (n = 12), acute tubular necrosis (n = 22), ischemic glomerulopathy/nephrosclerosis (n = 23), and other miscellaneous processes (n = 14). Staining in tubular basement membranes and peritubular capillaries was most common in lupus. Conclusion Based on reliable staining in lupus and membranous GN, C4d staining is potentially useful as a screening and diagnostic tool, if only paraffin-embedded tissue is available. Knowledge of C4d staining patterns in normal and pathological tissues enhances its diagnostic value.
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Affiliation(s)
- Cinthia B. Drachenberg
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Correspondence: Cinthia B. Drachenberg, Department of Pathology, Electron Microscopy Laboratory, University of Maryland Hospital, 22 South Greene Street, NBW49, Baltimore, Maryland 21201, USA.
| | - John C. Papadimitriou
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Preeti Chandra
- Department of Medicine, Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Abdolreza Haririan
- Department of Medicine, Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Susan Mendley
- Department of Pediatrics, Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew R. Weir
- Department of Medicine, Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Mario F. Rubin
- Department of Medicine, Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Complement-mediated microangiopathy in IgA nephropathy and IgA vasculitis with nephritis. Mod Pathol 2019; 32:1147-1157. [PMID: 30936425 DOI: 10.1038/s41379-019-0259-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 02/18/2019] [Accepted: 02/18/2019] [Indexed: 12/20/2022]
Abstract
Complement factor C4d was recently observed in renal biopsies from patients who had IgA nephropathy and a poor prognosis. We previously reported that C4d is a common denominator in microangiopathies. In this retrospective cohort study, we investigated whether C4d is a marker of microangiopathy in both IgA nephropathy and IgA vasculitis with nephritis, and whether patients with C4d and microangiopathy have poor renal outcome. We examined 128 renal biopsies from adult and pediatric patients, including normotensive and hypertensive patients, who presented with IgA nephropathy or IgA vasculitis with nephritis. Biopsies were re-evaluated in accordance with the Oxford classification, scored for additional lesions, and stained for complement proteins using immunohistochemistry, including C4d and C5b-9. Clinical data were collected with a mean (±SD) follow-up period of 51 ± 39 months. Changes in estimated glomerular filtration rate over time were compared using linear mixed-effects models. Renal survival was analyzed using multivariable Cox regression. Microangiopathic lesions were present in 20% of all biopsies (23% and 9% of patients with IgA nephropathy and IgA vasculitis with nephritis, respectively). Microangiopathy was associated with C4d and C5b-9 deposits, a higher number of chronic lesions, and hypertension (all p < 0.05). Patients with C4d and microangiopathic lesions had significantly poorer renal survival than patients without these findings, corrected for hypertension (p < 0.01). In conclusion, patients with IgA nephropathy or IgA vasculitis with nephritis with a combination of C4d positivity and microangiopathy comprise a clinical subgroup with an increased number of chronic lesions, lower estimated glomerular filtration rate, and poorer renal survival, even when corrected for hypertension. These data suggest that complement activation is involved in the development of microangiopathy in patients with IgA nephropathy and IgA vasculitis with nephritis, and that complement-mediated microangiopathy contributes to disease progression.
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Moran SM, Cattran DC. Recent advances in risk prediction, therapeutics and pathogenesis of IgA nephropathy. Minerva Med 2019; 110:439-449. [PMID: 31142099 DOI: 10.23736/s0026-4806.19.06165-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Immunoglobulin A nephropathy (IgAN) is the world's commonest primary glomerular disease with variable clinical presentation and progression rates that are dependent on clinical-pathologic phenotype and duration of follow-up. Overall 4-40% of patients progress to end-stage kidney disease (ESKD) by 10 years. Treatment decisions remain a challenge due to these variations. The ultimate goal of management is to prevent progression to ESKD and of vital importance is the potential reversible early detection of active glomerular inflammation prior to scarring. IgAN is globally, is the most common biopsy proven glomerulonephritis and a leading cause of ESKD. The Oxford pathological classification was devised by a collaborative pathology and nephrology network to provide an evidence-based scoring system with reproducible independent pathology features of predictive value. Clinical variables that alter prognosis include male sex, increasing age, increased body weight, smoking, Pacific Asian ethnicity, hypertension, proteinuria, and complement deficiency. Excellent conservative therapy is the cornerstone of therapy with tight blood control, renin-angiotensin system inhibition, and statin therapy. The role of immunosuppressive therapy including corticosteroids in IgAN remains open with ongoing clinical trials of low dose oral corticosteroids and enteric coated budesonide. Complement activation contributes to the pathogenic process of IgAN with evidence from genetic, serological, histological and in-vitro studies. This knowledge has translated to clinical trials of investigational agents directly targeting the alternative pathway.
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Affiliation(s)
- Sarah M Moran
- The Toronto Glomerulonephritis Registry and Division of Nephrology, University Health Network, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada.,Trinity Health Kidney Center, Trinity College, Dublin, Ireland
| | - Daniel C Cattran
- The Toronto Glomerulonephritis Registry and Division of Nephrology, University Health Network, Toronto, ON, Canada - .,Department of Medicine, University of Toronto, Toronto, ON, Canada
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Heybeli C, Oktan MA, Yıldız S, Ünlü M, Celik A, Sarıoglu S. Mesangial C4d deposition is independently associated with poor renal survival in patients with primary focal segmental glomerulosclerosis. Clin Exp Nephrol 2019; 23:650-660. [PMID: 30617839 DOI: 10.1007/s10157-018-01688-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 12/29/2018] [Indexed: 01/14/2023]
Abstract
BACKGROUND C4d deposition is defined as the footprint of immune injury and it is associated with unfavorable renal outcomes in patients with IgA nephropathy. We searched whether mesangial C4d deposition is associated with poor renal survival in patients with primary focal segmental glomerulosclerosis (FSGS). METHODS Biopsy specimens were stained with anti-C4d antibody. Patients were classified based on mesangial C4d deposition as C4d-negative and C4d-positive. Groups were compared according to baseline and follow-up clinical variables. Factors that predict renal progression and treatment failure were determined using Cox-regression and multivariate logistic regression models, respectively. RESULTS Forty-one FSGS patients were followed for a mean of 67.7 ± 40.8 months. C4d-positive group included 18 patients while remaining 23 patients were C4d-negative. Urinary protein excretion and serum creatinine levels at baseline were comparable between groups. Fifteen patients reached the composite primary endpoint which included serum creatinine increasing > 30% from the baseline and reaching > 1.5 mg/dl, and/or evolution to end-stage renal disease (36.6%). In multivariate regression analysis, baseline eGFR (OR 0.71, 95% CI 0.53-0.94; p = 0.016) and mesangial C4d deposition (OR 10.5, 95% CI 1.51-73.18; p = 0.018) were independently associated with treatment failure rates. Mesangial C4d deposition was independently associated with the progression to the primary endpoint (HR 6.54, 95% CI 1.49-28.7, p = 0.013). CONCLUSION We showed for the first time that mesangial C4d deposition is an independent predictor of disease progression and treatment failure in patients with primary FSGS.
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Affiliation(s)
- Cihan Heybeli
- School of Medicine, Department of Internal Medicine, Division of Nephrology, Dokuz Eylul University, Balcova, Izmir, Turkey.
| | - Mehmet Asi Oktan
- School of Medicine, Department of Internal Medicine, Division of Nephrology, Dokuz Eylul University, Balcova, Izmir, Turkey
| | - Serkan Yıldız
- School of Medicine, Department of Internal Medicine, Division of Nephrology, Dokuz Eylul University, Balcova, Izmir, Turkey
| | - Mehtat Ünlü
- Department of Pathology, Dokuz Eylul University, Izmir, Turkey
| | - Ali Celik
- School of Medicine, Department of Internal Medicine, Division of Nephrology, Dokuz Eylul University, Balcova, Izmir, Turkey
| | - Sülen Sarıoglu
- Department of Pathology, Dokuz Eylul University, Izmir, Turkey
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Abstract
IgA nephropathy, the most common primary glomerulonephritis in the world and a frequent cause of end-stage renal disease, is characterized by typical mesangial deposits of IgA1, as described by Berger and Hinglaise in 1968. Since then, it has been discovered that aberrant IgA1 O-glycosylation is involved in disease pathogenesis. Progress in glycomic, genomic, clinical, analytical, and biochemical studies has shown autoimmune features of IgA nephropathy. The autoimmune character of the disease is explained by a multihit pathogenesis model, wherein overproduction of aberrantly glycosylated IgA1, galactose-deficient in some O-glycans, by IgA1-secreting cells leads to increased levels of circulatory galactose-deficient IgA1. These glycoforms induce production of autoantibodies that subsequently bind hinge-region of galactose-deficient IgA1 molecules, resulting in the formation of nephritogenic immune complexes. Some of these complexes deposit in the kidney, activate mesangial cells, and incite glomerular injury. Thus, galactose-deficient IgA1 is central to the disease process. In this article, we review studies concerning IgA1 O-glycosylation that have contributed to the current understanding of the role of IgA1 in the pathogenesis of IgA nephropathy.
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Affiliation(s)
- Jan Novak
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL..
| | - Jonathan Barratt
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Bruce A Julian
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL.; Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Matthew B Renfrow
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL
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