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 New functional and structural insights from updated mutational databases for complement factor H, Factor I, membrane cofactor protein and C3

2014 ◽  
Vol 34 (5) ◽  
Author(s):  
Elizabeth Rodriguez ◽  
Pavithra M. Rallapalli ◽  
Amy J. Osborne ◽  
Stephen J. Perkins
Keyword(s):  
Alternative Pathway ◽  
Factor H ◽  
Complement Factor H ◽  
Complement C3 ◽  
Complement Factor ◽  
Membrane Cofactor Protein ◽  
Complement Alternative Pathway ◽  
Factor I ◽  
Mutational Hotspots ◽  
Structural Insights

A new compilation of 324 mutations in four major proteins from the complement alternative pathway reveals mutational hotspots in factor H and complement C3, and less so in factor I and membrane cofactor protein. Their associations with function are discussed.

Complement alternative pathway activation associated with pulmonary hypertension in lupus nephritis patients

Lupus ◽  
2019 ◽  
Vol 28 (9) ◽  
pp. 1051-1061
Author(s):  
Q Li ◽  
H Li ◽  
J Shi ◽  
B He ◽  
F Yu
Keyword(s):  
Pulmonary Hypertension ◽  
Lupus Nephritis ◽  
Lupus Erythematosus ◽  
Alternative Pathway ◽  
Factor H ◽  
Renal Outcome ◽  
Complement Alternative Pathway ◽  
Complement Components ◽  
Pathway Activation ◽  
Excessive Activation

Pulmonary hypertension occurs in systemic lupus erythematosus (SLE) for several reasons, such as vasculopathy. Previous studies have indicated that the excessive activation of the complement alternative pathway might be involved in the pathogenesis of lupus nephritis, especially in the absence of factor H or its functional impairment. However, the clinical and pathological significance of the alternative complement activation in lupus nephritis patients with pulmonary hypertension remains elusive. The data on patients with pulmonary hypertension and non-pulmonary hypertension lupus nephritis were retrospectively analyzed in our centre. Major plasma levels of complement components were evaluated. The depositions of Bb, C3d and C5b-9 in the lung specimens of pulmonary hypertension combined with SLE patients were detected by immunofluorescence staining. Among 352 lupus nephritis cases, 24 were diagnosed with pulmonary hypertension and 328 with non-pulmonary hypertension. Higher levels of Bb and lower levels of factor H were detected in the pulmonary hypertension group in comparison with the negative group ( P = 0.049, P = 0.024, respectively). Pulmonary hypertension was a risk factor for renal outcome as deduced by the log-rank and Cox test for survival analysis. C3d, C5b-9 and Bb were found to be positive in lung specimens of lupus nephritis patients with pulmonary hypertension. We concluded that activation of the complement alternative pathway may be involved in the pathogenesis of pulmonary hypertension in lupus nephritis.

scholarly journals COVID-19: a trigger for severe thrombotic microangiopathy in a patient with complement gene variant

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Larisa Pinte ◽  
Bogdan Marian Sorohan ◽  
Zoltán Prohászka ◽  
Mihaela Gherghiceanu ◽  
Cristian Băicuş
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Thrombotic Microangiopathy ◽  
Alternative Pathway ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Factor H ◽  
Complement C3 ◽  
Uncontrolled Hypertension ◽  
Complement Factor ◽  
Uremic Syndrome ◽  
Complement Gene

Abstract The evidence regarding thrombotic microangiopathy (TMA) related to Coronavirus Infectious Disease 2019 (COVID-19) in patients with complement gene mutations as a cause of acute kidney injury (AKI) are limited. We presented a case of a 23-year-old male patient admitted with an asymptomatic form of COVID-19, but with uncontrolled hypertension and AKI. Kidney biopsy showed severe lesions of TMA. In evolution patient had persistent microangiopathic hemolytic anemia, decreased level of haptoglobin and increased LDH level. Decreased complement C3 level and the presence of schistocytes were found for the first time after biopsy. Kidney function progressively decreased and the patient remained hemodialysis dependent. Complement work-up showed a heterozygous variant with unknown significance in complement factor I (CFI) c.-13G>A, affecting the 5' UTR region of the gene. In addition, the patient was found to be heterozygous for the complement factor H (CFH) H3 haplotype (involving the rare alleles of c.-331C>T, Q672Q and E936D polymorphisms) reported as a risk factor of atypical hemolytic uremic syndrome. This case of AKI associated with severe TMA and secondary hemolytic uremic syndrome highlights the importance of genetic risk modifiers in the alternative pathway dysregulation of the complement in the setting of COVID-19, even in asymptomatic forms.

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 Clinicopathological Characteristics and Outcomes of Chinese Patients with Scanty Immune Deposits Lupus Nephritis: A Large Cohort Study from a Single Center

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Qiuyu Li ◽  
Di Song ◽  
Fengmei Wang ◽  
Ying Tan ◽  
Feng Yu ◽  
...  
Keyword(s):  
Lupus Nephritis ◽  
Immune Complex ◽  
Alternative Pathway ◽  
Clinicopathological Characteristics ◽  
Factor H ◽  
Chinese Patients ◽  
Complement Alternative Pathway ◽  
Complement Components ◽  
Immune Deposits ◽  
Large Cohort Study

Objective. To assess clinicopathological characteristics of lupus nephritis patients with scanty immune deposits.Methods. The data of patients with scanty immune deposits lupus nephritis were retrospectively analyzed. Plasma ANCA and complement components were detected.Results. Among 316 cases with renal biopsy-proven lupus nephritis, 40 cases were diagnosed as scanty immune deposits. There were significantly higher value of serum creatinine (P=0.002) and lower hemoglobin level (P=0.009) and higher score of cellular crescents (P=0.015) in scanty immune deposits group compared with immune complex deposits group. The frequency of positive plasma ANCA was significantly higher in scanty immune deposits group than that in immune complex deposits group (52.5% versus 10.1%,P<0.001). As for comparisons of plasma complement components, there were significantly higher levels of C1q (P=0.005) and Bb (P=0.02) and lower level of factor H (P=0.003) in scanty immune deposits group. The ratio of treatment failure was significantly higher in scanty immune deposits group than that in immune deposits group (42.5% versus 19.20%,P=0.001). The renal outcomes were similar between the two groups.Conclusions. Patients with scanty immune deposits lupus nephritis had more severe kidney damage. ANCA and activation of complement alternative pathway might be involved in the pathogenesis of the disease.

scholarly journals Heterogeneity in Rhesus Macaque Complement Factor H Binding to Meningococcal Factor H Binding Protein (FHbp) Informs Selection of Primates To Assess Immunogenicity of FHbp-Based Vaccines

2014 ◽  
Vol 21 (11) ◽  
pp. 1505-1511 ◽  
Author(s):  
Peter T. Beernink ◽  
Jutamas Shaughnessy ◽  
Heather Stefek ◽  
Sanjay Ram ◽  
Dan M. Granoff
Keyword(s):  
Binding Protein ◽  
Rhesus Macaques ◽  
Alternative Pathway ◽  
Factor H ◽  
Complement Factor ◽  
Primate Model ◽  
Complement Alternative Pathway ◽  
Content Type ◽  
Bacterial Surface ◽  
Short Consensus Repeats

ABSTRACTNeisseria meningitidiscauses disease only in humans. An important mechanism underlying this host specificity is the ability of the organism to resist complement by recruiting the complement downregulator factor H (FH) to the bacterial surface. In previous studies, binding of FH to one of the major meningococcal FH ligands, factor H binding protein (FHbp), was reported to be specific for human FH. Here we report that sera from 23 of 73 rhesus macaques (32%) tested had high FH binding to FHbp. Similar to human FH, binding of macaque FH to the meningococcal cell surface inhibited the complement alternative pathway by decreasing deposition of C3b. FH contains 20 domains (or short consensus repeats), with domains 6 and 7 being responsible for binding of human FH to FHbp. DNA sequence analyses of FH domains 6 and 7 from macaques with high or low FH binding showed a polymorphism at residue 352 in domain 6, with Tyr being associated with high binding and His with low binding. A recombinant macaque FH 6,7/Fc fragment with Tyr352 showed higher binding to FHbp than the corresponding fragment with His352. In previous studies in human FH transgenic mice, binding of FH to FHbp vaccines decreased protective antibody responses, and mutant FHbp vaccines with decreased FH binding elicited serum antibodies with greater protective activity. Thus, macaques with high FH binding to FHbp represent an attractive nonhuman primate model to investigate further the effects of FH binding on the immunogenicity of FHbp vaccines.

scholarly journals Functional Characterization of Rare Genetic Variants in the N-Terminus of Complement Factor H in aHUS, C3G, and AMD

2021 ◽  
Vol 11 ◽  
Author(s):  
Edwin K. S. Wong ◽  
Thomas M. Hallam ◽  
Vicky Brocklebank ◽  
Patrick R. Walsh ◽  
Kate Smith-Jackson ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Alternative Pathway ◽  
Significant Proportion ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Size Exclusion ◽  
Complement Factor ◽  
Atypical Haemolytic Uraemic Syndrome ◽  
Rare Genetic Variants ◽  
Biochemical Assessment

Membranoproliferative glomerulonephritis (MPGN), C3 glomerulopathy (C3G), atypical haemolytic uraemic syndrome (aHUS) and age-related macular degeneration (AMD) have all been strongly linked with dysfunction of the alternative pathway (AP) of complement. A significant proportion of individuals with MPGN, C3G, aHUS and AMD carry rare genetic variants in the CFH gene that cause functional or quantitative deficiencies in the factor H (FH) protein, an important regulator of the AP. In silico analysis of the deleteriousness of rare genetic variants in CFH is not reliable and careful biochemical assessment remains the gold standard. Six N-terminal variants of uncertain significance in CFH were identified in patients with these diseases of the AP and selected for analysis. The variants were produced in Pichia Pastoris in the setting of FH CCPs 1–4, purified by nickel affinity chromatography and size exclusion and characterized by surface plasmon resonance and haemolytic assays as well as by cofactor assays in the fluid phase. A single variant, Q81P demonstrated a profound loss of binding to C3b with consequent loss of cofactor and decay accelerating activity. A further 2 variants, G69E and D130N, demonstrated only subtle defects which could conceivably over time lead to disease progression of more chronic AP diseases such as C3G and AMD. In the variants S159N, A161S, and M162V any functional defect was below the capacity of the experimental assays to reliably detect. This study further underlines the importance of careful biochemical assessment when assigning functional consequences to rare genetic variants that may alter clinical decisions for patients.

scholarly journals Activation of final complement components after kidney transplantation as a marker of delayed graft function severity

2020 ◽  
Author(s):  
Carlos E Arias-Cabrales ◽  
Marta Riera ◽  
María José Pérez-Sáez ◽  
Javier Gimeno ◽  
David Benito ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Graft Function ◽  
Basal Membrane ◽  
Factor H ◽  
Delayed Graft Function ◽  
Control Group ◽  
Complement Factor ◽  
Tubular Epithelial Cells ◽  
Complement Components ◽  
Protocol Biopsies

Abstract Background Ischaemia–reperfusion (I/R) damage is a relevant cause of delayed graft function (DGF). Complement activation is involved in experimental I/R injury, but few data are available from kidney transplant (KT) patients. We studied the dynamics of membrane attack complex (C5b-9) as a soluble fraction (SC5b-9) and the histological deposit pattern of C3b, complement Factor H (FH) and C5b-9 in DGF patients. Methods We evaluated SC5b-9 levels in 59 recipients: 38 with immediate graft function and 21 with DGF. The SC5b-9 was measured at admission for KT and 7 days after KT. DGF-kidney biopsies (n = 12) and a control group of 1-year protocol biopsies without tissue damage (n = 4) were stained for C5b-9, C3b and FH. Results SC5b-9 increased significantly in DGF patients (Day 0: 6621 ± 2202 mAU/L versus Day 7: 9626 ± 4142  mAU/L; P = 0.006), while it remained stable in non-DGF patients. Days 0–7 increase &gt;5% was the better cut-off associated with DGF versus non-DGF patient discrimination (sensitivity = 81%). In addition, SC5b-9 increase was related to DGF duration and worse graft function, and independently associated with DGF occurrence. SC5b-9, C3b and FH stains were observed in tubular epithelial cells basal membrane. DGF-kidney biopsies showed a more frequently high-intensity stain, a higher number of tubules with positive stain and larger perimeter of tubules with positive stains for SC5b-9, C3b and FH than control patients. Conclusions Both SC5b-9 levels and SC5b-9, C3b and FH deposits in tubular epithelial cells basal membrane are highly expressed in patients experiencing DGF. SC5b-9 levels increase could be useful as a marker of DGF severity.

scholarly journals Functional Mapping of YadA- and Ail-Mediated Binding of Human Factor H to Yersinia enterocolitica Serotype O:3

2008 ◽  
Vol 76 (11) ◽  
pp. 5016-5027 ◽  
Author(s):  
Marta Biedzka-Sarek ◽  
Saara Salmenlinna ◽  
Markus Gruber ◽  
Andrei N. Lupas ◽  
Seppo Meri ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Alternative Pathway ◽  
Outer Membrane Proteins ◽  
Factor H ◽  
Complement Alternative Pathway ◽  
Human Host ◽  
Serotype O ◽  
Complement Resistance ◽  
Sense And Respond ◽  
Active Complement

ABSTRACT Yersinia enterocolitica is an enteric pathogen that exploits diverse means to survive in the human host. Upon Y. enterocolitica entry into the human host, bacteria sense and respond to variety of signals, one of which is the temperature. Temperature in particular has a profound impact on Y. enterocolitica gene expression, as most of its virulence factors are expressed exclusively at 37°C. These include two outer membrane proteins, YadA and Ail, that function as adhesins and complement resistance (CR) factors. Both YadA and Ail bind the functionally active complement alternative pathway regulator factor H (FH). In this study, we characterized regions on both proteins involved in CR and the interaction with FH. Twenty-eight mutants having short (7 to 41 amino acids) internal deletions within the neck and stalk of YadA and two complement-sensitive site-directed Ail mutants were constructed to map the CR and FH binding regions of YadA and Ail. Functional analysis of the YadA mutants revealed that the stalk of YadA is required for both CR and FH binding and that FH appears to target several conformational and discontinuous sites of the YadA stalk. On the other hand, the complement-sensitive Ail mutants were not affected in FH binding. Our results also suggested that Ail- and YadA-mediated CR does not depend solely on FH binding.

scholarly journals De Novo Atypical Haemolytic Uremic Syndrome after Kidney Transplantation

2018 ◽  
Vol 2018 ◽  
pp. 1-4
Author(s):  
Arnaud Devresse ◽  
Martine de Meyer ◽  
Selda Aydin ◽  
Karin Dahan ◽  
Nada Kanaan
Keyword(s):  
Kidney Transplantation ◽  
De Novo ◽  
Alternative Pathway ◽  
Factor H ◽  
Complement Factor ◽  
Haemolytic Uremic Syndrome ◽  
Hinman Syndrome ◽  
Uremic Syndrome ◽  
Stage Renal Disease ◽  
End Stage

De novo thrombotic microangiopathy (TMA) can occur after kidney transplantation. An abnormality of the alternative pathway of complement must be suspected and searched for, even in presence of a secondary cause. We report the case of a 23-year-old female patient who was transplanted with a kidney from her mother for end-stage renal disease secondary to Hinman syndrome. Early after transplantation, she presented with 2 episodes of severe pyelonephritis, associated with acute kidney dysfunction and biological and histological features of TMA. Investigations of the alternative pathway of the complement system revealed atypical haemolytic uremic syndrome secondary to complement factor I mutation, associated with mutations in CD46 and complement factor H related protein genes. Plasma exchanges followed by eculizumab injections allowed improvement of kidney function without, however, normalization of creatinine.

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