Molecular basis of complement-mediated renal disease

2015 ◽  
Author(s):  
Nicholas Medjeral-Thomas ◽  
Anna Richards ◽  
Matthew C. Pickering
Keyword(s):  
Haemolytic Uraemic Syndrome ◽  
Alternative Pathway ◽  
Protein Family ◽  
Factor H ◽  
Complement Factor ◽  
C3 Glomerulopathy ◽  
Ongoing Research ◽  
Dense Deposit ◽  
Atypical Haemolytic Uraemic Syndrome ◽  
Glomerular Lesions

Abnormal regulation of complement is intimately associated with C3 glomerulopathy and atypical haemolytic uraemic syndrome. Atypical haemolytic uraemic syndrome is characterized by renal thrombotic microangiopathy due to an inability to regulate complement activation along the renal endothelium. The development of thrombosis is critically dependent on the ability to activate C5. Eculizumab, a monoclonal anti-C5 antibody, is an effective therapy for this condition. C3 glomerulopathy refers to glomerular lesions characterized by accumulation of C3 in the absence of immunoglobulin. The prototypic example is dense deposit disease. This condition is associated with impaired regulation of the alternative pathway in plasma. In other subtypes of C3 glomerulopathy, familial studies have identified mutations within the complement factor H-related protein family. Polymorphic variation within this protein family also influences susceptibility to IgA nephropathy. The mechanism underlying these associations remains unknown and is the subject of ongoing research efforts.

scholarly journals An Engineered Complement Factor H Construct for Treatment of C3 Glomerulopathy

2018 ◽  
Vol 29 (6) ◽  
pp. 1649-1661 ◽  
Author(s):  
Yi Yang ◽  
Harriet Denton ◽  
Owen R. Davies ◽  
Kate Smith-Jackson ◽  
Heather Kerr ◽  
...  
Keyword(s):  
Chinese Hamster Ovary Cells ◽  
Alternative Pathway ◽  
Treatment Options ◽  
Chinese Hamster ◽  
Factor H ◽  
Complement Factor H ◽  
Complement Factor ◽  
C3 Glomerulopathy

Background C3 glomerulopathy (C3G) is associated with dysregulation of the alternative pathway of complement activation, and treatment options for C3G remain limited. Complement factor H (FH) is a potent regulator of the alternative pathway and might offer a solution, but the mass and complexity of FH makes generation of full-length FH far from trivial. We previously generated a mini-FH construct, with FH short consensus repeats 1–5 linked to repeats 18–20 (FH1–5^18–20), that was effective in experimental C3G. However, the serum t1/2 of FH1–5^18–20 was significantly shorter than that of serum-purified FH.Methods We introduced the oligomerization domain of human FH-related protein 1 (denoted by R1–2) at the carboxy or amino terminus of human FH1–5^18–20 to generate two homodimeric mini-FH constructs (FHR1–2^1–5^18–20 and FH1–5^18–20^R1–2, respectively) in Chinese hamster ovary cells and tested these constructs using binding, fluid-phase, and erythrocyte lysis assays, followed by experiments in FH-deficient Cfh−/− mice.Results FHR1–2^1–5^18–20 and FH1–5^18–20^R1–2 homodimerized in solution and displayed avid binding profiles on clustered C3b surfaces, particularly FHR1–2^1–5^18–20. Each construct was >10-fold more effective than FH at inhibiting cell surface complement activity in vitro and restricted glomerular basement membrane C3 deposition in vivo significantly better than FH or FH1–5^18–20. FH1–5^18–20^R1–2 had a C3 breakdown fragment binding profile similar to that of FH, a >5-fold increase in serum t1/2 compared with that of FH1–5^18–20, and significantly better retention in the kidney than FH or FH1–5^18–20.Conclusions FH1–5^18–20^R1–2 may have utility as a treatment option for C3G or other complement-mediated diseases.

scholarly journals CFHR5 Genetic Variations and Serum Levels in Patients with Immune-Complex-Mediated Membranoproliferative Glomerulonephritis and C3-Glomerulopathy

2020 ◽  
Author(s):  
Nóra Garam ◽  
Marcell Cserhalmi ◽  
Zoltán Prohászka ◽  
Ágnes Szilágyi ◽  
Nóra Veszeli ◽  
...  
Keyword(s):  
Immune Complex ◽  
Membranoproliferative Glomerulonephritis ◽  
Kidney Diseases ◽  
Alternative Pathway ◽  
Serum Levels ◽  
Genetic Alterations ◽  
Factor H ◽  
Complement Factor ◽  
C3 Glomerulopathy

Abstract Background: Factor H-related-5 (FHR-5) is a member of the complement Factor H protein family. Due to the homology to Factor H, the main complement regulator of the alternative pathway, it may also be implicated in pathomechanism of kidney diseases where Factor H and alternative pathway dysregulation play a role. Here, we report the first observational study on CFHR5 variations along with serum FHR-5 levels in immune-complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) and C3 glomerulopathy (C3G) patients together with the clinical, genetic, complement and follow-up data.Results: 120 patients with a histologically-proven diagnosis of IC-MPGN/C3G were enrolled in the study. FHR-5 serum levels were measured in ELISA, the CFHR5 gene was analyzed by Sanger-sequencing, and selected mutants were studied as recombinant proteins in ELISA and SPR.Eight relevant CFHR5 variations in 14 patients (11.7%) were observed, 5 of them identified as pathogenic for C3G. The FHR-5G278S and FHR-5R356H mutations altered the interaction of FHR-5 with C3b, when compared to the FHR-5WT. Serum FHR-5 levels were lower in patients compared to controls. Low serum FHR-5 concentration at presentation associated with better renal survival during the follow-up period, furthermore, it showed clear association with signs of hypocomplementemia and clinically meaningful clusters.Conclusions: Our observations support the hypothesis that FHR-5 protein and its genetic alterations play a role in the pathogenesis of IC-MPGN/C3G.

scholarly journals Humanized C3 Mouse: A Novel Accelerated Model of C3 Glomerulopathy

2020 ◽  
Vol 32 (1) ◽  
pp. 99-114
Author(s):  
Kishor Devalaraja-Narashimha ◽  
Karoline Meagher ◽  
Yifan Luo ◽  
Cong Huang ◽  
Theodore Kaplan ◽  
...  
Keyword(s):  
Alternative Pathway ◽  
Gene Mutations ◽  
Factor H ◽  
Complement Factor ◽  
C3 Glomerulopathy ◽  
Wild Type ◽  
Therapeutic Approaches ◽  
Pathologic Features ◽  
Complement Gene ◽  
Extended Survival

BackgroundC3 glomerulopathy (C3G) is characterized by the alternative-pathway (AP) hyperactivation induced by nephritic factors or complement gene mutations. Mice deficient in complement factor H (CFH) are a classic C3G model, with kidney disease that requires several months to progress to renal failure. Novel C3G models can further contribute to understanding the mechanism behind this disease and developing therapeutic approaches.MethodsA novel, rapidly progressing, severe, murine model of C3G was developed by replacing the mouse C3 gene with the human C3 homolog using VelociGene technology. Functional, histologic, molecular, and pharmacologic assays characterize the presentation of renal disease and enable useful pharmacologic interventions in the humanized C3 (C3hu/hu) mice.ResultsThe C3hu/hu mice exhibit increased morbidity early in life and die by about 5–6 months of age. The C3hu/hu mice display elevated biomarkers of kidney dysfunction, glomerulosclerosis, C3/C5b-9 deposition, and reduced circulating C3 compared with wild-type mice. Administration of a C5-blocking mAb improved survival rate and offered functional and histopathologic benefits. Blockade of AP activation by anti-C3b or CFB mAbs also extended survival and preserved kidney function.ConclusionsThe C3hu/hu mice are a useful model for C3G because they share many pathologic features consistent with the human disease. The C3G phenotype in C3hu/hu mice may originate from a dysregulated interaction of human C3 protein with multiple mouse complement proteins, leading to unregulated C3 activation via AP. The accelerated disease course in C3hu/hu mice may further enable preclinical studies to assess and validate new therapeutics for C3G.

scholarly journals Novel complement factor H gene mutation causing atypical haemolytic uraemic syndrome: early Eculizumab prevents acute dialysis

2017 ◽  
Vol 10 (2) ◽  
pp. 263-265
Author(s):  
James Collett ◽  
Amali Mallawaarachchi ◽  
Eddy Fischer ◽  
Muralikrishna Gangadharan Komala ◽  
Kamal Sud ◽  
...  
Keyword(s):  
Gene Mutation ◽  
Haemolytic Uraemic Syndrome ◽  
Factor H ◽  
Complement Factor H ◽  
Complement Factor ◽  
Acute Dialysis ◽  
Atypical Haemolytic Uraemic Syndrome ◽  
H Gene

Association between thrombotic microangiopathy and activated alternative complement pathway in malignant nephrosclerosis

2020 ◽  
Author(s):  
Ying Zhang ◽  
Chaona Yang ◽  
Xinjin Zhou ◽  
Ruimin Hu ◽  
Songxia Quan ◽  
...  
Keyword(s):  
Thrombotic Microangiopathy ◽  
Alternative Pathway ◽  
Factor H ◽  
Complement Factor ◽  
Complement Alternative Pathway ◽  
Complement Components ◽  
Atypical Haemolytic Uraemic Syndrome ◽  
Urinary Levels ◽  
Normal Controls ◽  
Malignant Nephrosclerosis

Abstract Background Malignant nephrosclerosis, defined as renal microangiopathy in the setting of severe hypertension, remains a critical renal emergency leading to end-stage renal disease despite aggressive anti-hypertensive treatment. Recently, activation of the complement alternative pathway (AP) has been reported to play a prominent role in the pathogenesis of malignant nephrosclerosis. However, subsequent study failed to recapitulate the findings of genetic complement abnormalities in the disease. This study aimed to determine the presence of AP activation and genetic complement defects and establish their correlations to renal microangiopathy lesions, clinical features and prognosis in patients with malignant nephrosclerosis. Methods Fifty patients with malignant hypertension and concomitant thrombotic microangiopathy (TMA) proven by renal biopsy were investigated; 25 cases of kidney donors who received zero-hour allograft biopsies were used as normal controls. Various renal TMA lesions in patients with malignant nephrosclerosis were reviewed and evaluated using a semi-quantitative scoring system. Deposition of C5b-9, C3a, C5a, C4d and mannose-binding lectin was assessed by immunohistochemistry. Co-localization of C5b-9 and CD34 was detected by confocal microscopy. Complement factor B (FB), factor P (FP; properdin), factor D (FD), factor H (FH), C3a and C5a levels were quantified by enzyme-linked immonosorbent assay in plasma and urine samples of patients with malignant nephrosclerosis and controls. Genetic abnormalities of complement components were analysed by whole-exome sequencing. Results Renal biopsies of malignant nephrosclerosis showed identical histopathological and ultrastructural features to atypical haemolytic uraemic syndrome. C5b-9, C3a and C5a deposits were found along the walls of arteries/arterioles and glomerular capillaries and localized in the endothelial cells. Elevated plasma and urinary levels of FB, FP, FD, C3a and C5a as well as decreased FH levels were observed in patients with malignant nephrosclerosis compared with normal controls. The urinary levels of complement AP components, but not the plasma levels, were correlated with renal functions, prognosis and active TMA lesions except for arteriolar thrombi. Finally, mutations of the MCP, CFB, CFH and CFHR5 genes were identified in 8 of 20 patients with malignant nephrosclerosis. Conclusions Aberrant complement AP dysregulation was demonstrated and associated with the activity, severity and renal outcomes of malignant nephrosclerosis. This observation warrants screening for complement defects in patients with malignant nephrosclerosis for the potential use of complement regulators and also highlights the need for further investigation of the precise role of AP in the pathogenesis of the disease.

scholarly journals COMPLEMENT FACTOR H FUNCTIONAL ASSAY MAY HELP TO MONITOR ATYPICAL HAEMOLYTIC URAEMIC SYNDROME: A PILOT STUDY

2013 ◽  
Vol 68 (1) ◽  
pp. 9-14 ◽  
Author(s):  
A Massart ◽  
S Golmarvi ◽  
S Hachimi-Idrissi ◽  
E Broeders ◽  
Y Tournay ◽  
...  
Keyword(s):  
Pilot Study ◽  
Haemolytic Uraemic Syndrome ◽  
Factor H ◽  
Complement Factor H ◽  
Functional Assay ◽  
Complement Factor ◽  
Atypical Haemolytic Uraemic Syndrome

scholarly journals FHR-5 Serum Levels and CFHR5 Genetic Variations in Patients With Immune Complex-Mediated Membranoproliferative Glomerulonephritis and C3-Glomerulopathy

2021 ◽  
Vol 12 ◽  
Author(s):  
Nóra Garam ◽  
Marcell Cserhalmi ◽  
Zoltán Prohászka ◽  
Ágnes Szilágyi ◽  
Nóra Veszeli ◽  
...  
Keyword(s):  
Immune Complex ◽  
Membranoproliferative Glomerulonephritis ◽  
Kidney Diseases ◽  
Alternative Pathway ◽  
Serum Levels ◽  
Factor H ◽  
Fine Tuning ◽  
Complement Factor ◽  
C3 Glomerulopathy

BackgroundFactor H-related protein 5 (FHR-5) is a member of the complement Factor H protein family. Due to the homology to Factor H, the main complement regulator of the alternative pathway, it may also be implicated in the pathomechanism of kidney diseases where Factor H and alternative pathway dysregulation play a role. Here, we report the first observational study on CFHR5 variations along with serum FHR-5 levels in immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) and C3 glomerulopathy (C3G) patients together with the clinical, genetic, complement, and follow-up data.MethodsA total of 120 patients with a histologically proven diagnosis of IC-MPGN/C3G were enrolled in the study. FHR-5 serum levels were measured in ELISA, the CFHR5 gene was analyzed by Sanger sequencing, and selected variants were studied as recombinant proteins in ELISA and surface plasmon resonance (SPR).ResultsEight exonic CFHR5 variations in 14 patients (12.6%) were observed. Serum FHR-5 levels were lower in patients compared to controls. Low serum FHR-5 concentration at presentation associated with better renal survival during the follow-up period; furthermore, it showed clear association with signs of complement overactivation and clinically meaningful clusters.ConclusionsOur observations raise the possibility that the FHR-5 protein plays a fine-tuning role in the pathogenesis of IC-MPGN/C3G.

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