IgM Autoantibodies to Complement Factor H in Atypical Hemolytic Uremic Syndrome

2021 ◽  
pp. ASN.2020081224
Author(s):  
Massimo Cugno ◽  
Silvia Berra ◽  
Federica Depetri ◽  
Silvana Tedeschi ◽  
Samantha Griffini ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Hemolytic Uremic Syndrome ◽  
Bone Marrow Transplant ◽  
Thrombotic Microangiopathy ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Marrow Transplant ◽  
Factor H ◽  
Complement Factor ◽  
Uremic Syndrome ◽  
Factor H Autoantibodies

BackgroundAtypical hemolytic uremic syndrome (aHUS), a severe thrombotic microangiopathy, is often related to complement dysregulation, but the pathomechanisms remain unknown in at least 30% of patients. Researchers have described autoantibodies to complement factor H of the IgG class in 10% of patients with aHUS but have not reported anti-factor H autoantibodies of the IgM class.MethodsIn 186 patients with thrombotic microangiopathy clinically presented as aHUS, we searched for anti-factor H autoantibodies of the IgM class and those of the IgG and IgA classes. We used immunochromatography to purify anti-factor H IgM autoantibodies and immunoenzymatic methods and a competition assay with mapping mAbs to characterize interaction with the target protein.ResultsWe detected anti-factor H autoantibodies of the IgM class in seven of 186 (3.8%) patients with thrombotic microangiopathy presented as aHUS. No association was observed between anti-factor H IgM and homozygous deletions involving CFHR3-CFHR1. A significantly higher proportion of patients with bone marrow transplant–related thrombotic microangiopathy had anti-factor H IgM autoantibodies versus other patients with aHUS: three of 20 (15%) versus four of 166 (2.4%), respectively. The identified IgM autoantibodies recognize the SCR domain 19 of factor H molecule in all patients and interact with the factor H molecule, inhibiting its binding to C3b.ConclusionsDetectable autoantibodies to factor H of the IgM class may be present in patients with aHUS, and their frequency is six-fold higher in thrombotic microangiopathy forms associated with bone marrow transplant. The autoantibody interaction with factor H’s active site may support an autoimmune mechanism in some cases previously considered to be of unknown origin.

scholarly journals Thrombotic Microangiopathy with Complement Factor H Gene Mutations Unassociated with Atypical Hemolytic Uremic Syndrome

2015 ◽  
Vol 32 (3) ◽  
pp. 275-276
Author(s):  
Yesim Oymak ◽  
Tuba Hilkay Karapınar ◽  
Yılmaz Ay ◽  
Esin Özcan ◽  
Neryal Müminoğlu ◽  
...  
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Thrombotic Microangiopathy ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Gene Mutations ◽  
Factor H ◽  
Complement Factor H ◽  
Complement Factor ◽  
H Gene ◽  
Uremic Syndrome

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.

Use of eculizumab in pregnancy-associated atypical hemolytic uremic syndrome

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Meenal Misal ◽  
Megha Gupta ◽  
Lawrence D. Platt ◽  
Neil S. Silverman ◽  
Christina S. Han
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Clinical Evaluation ◽  
Thrombotic Microangiopathy ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Factor H ◽  
Complement Factor ◽  
Complement Inhibitor ◽  
Complement Pathway ◽  
Uremic Syndrome ◽  
Terminal Complement

Abstract Pregnancy-associated atypical hemolytic uremic syndrome (p-aHUS) is a rare disorder, with an estimated incidence of 1 in 25,000 pregnancies [Fakhouri F, Roumenina L, Provot F, Sallee M, Caillard S, Couzi L, et al. Pregnancy-associated hemolytic uremic syndrome revisited in the era of complement gene mutations. J Am Soc Nephrol. 2010;21:859–67.]. Unlike classic hemolytic uremic syndrome (HUS), aHUS is not related to Escherichia coli 0157:H7 infections. Rather, it arises from uncontrolled alternative complement pathway activation leading to diffuse endothelial damage. The formation of the resulting fibrin and platelet microthrombi in the vasculature leads to hemolysis, thrombocytopenia and ischemic end-organ damage in the form of acute kidney injury [Noris M, Remuzzi G. Atypical hemolytic-uremic syndrome. N Engl J Med. 2009;361:1676–87; Legendre CM, Licht C, Muus P, Greenbaum LA, Babu S, Bedrosian C, et al. Terminal complement inhibitor eculizumab in atypical hemolytic-uremic syndrome. N Engl J Med. 2013;368:2169–81; Loirat C, Fremeaux-Bacchi V. Atypical hemolytic uremic syndrome. Orphanet J Rare Dis. 2011;6:60; Shen YM. Clinical evaluation of thrombotic microangiopathy: identification of patients with suspected atypical hemolytic uremic syndrome. Thromb J. 2016;14(Suppl 1):19.]. Triggers for hyperactivation of the complement pathway include infection, inflammation, malignancy, endothelium-affecting drugs, maternal-fetal hemorrhage and pre-eclampsia [Shen YM. Clinical evaluation of thrombotic microangiopathy: identification of patients with suspected atypical hemolytic uremic syndrome. Thromb J. 2016;14(Suppl 1):19.]. Thirty percent of individuals with aHUS are found to have mutations in the genes encoding complement regulatory proteins, such as protein factor H, complement factor I and complement 3 [Noris M, Remuzzi G. Atypical hemolytic-uremic syndrome. N Engl J Med. 2009;361:1676–87; Loirat C, Fremeaux-Bacchi V. Atypical hemolytic uremic syndrome. Orphanet J Rare Dis. 2011;6:60.]. Outcomes of an untreated aHUS are poor: up to 50% of patients with aHUS progress to end-stage renal disease within a year and 25% die during the acute phase [Loirat C, Fremeaux-Bacchi V. Atypical hemolytic uremic syndrome. Orphanet J Rare Dis. 2011;6:60; Laurence J, Haller H, Mannucci PM, Nangaku M, Praga M, Rodriguez de Cordoba S. Atypical hemolytic uremic syndrome (aHUS): essential aspects of an accurate diagnosis. Clin Adv Hematol Oncol. 2016;14(Suppl 11):2–15.]. We present an unusual case of a 37-year-old primigravida who developed p-aHUS in the setting of hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome. She was successfully treated with a relatively novel medication; eculizumab, a terminal complement inhibitor. In contrast to previous reports of long-term treatment, she received a total of six doses of eculizumab and remained in remission at 12 months postpartum.

scholarly journals Association of factor H autoantibodies with deletions of CFHR1, CFHR3, CFHR4, and with mutations in CFH, CFI, CD46, and C3 in patients with atypical hemolytic uremic syndrome

Blood ◽  
2010 ◽  
Vol 115 (2) ◽  
pp. 379-387 ◽  
Author(s):  
Iain Moore ◽  
Lisa Strain ◽  
Isabel Pappworth ◽  
David Kavanagh ◽  
Paul N. Barlow ◽  
...  
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Atypical Hemolytic Uremic Syndrome ◽  
Factor H ◽  
Complement Factor ◽  
Disease Manifestation ◽  
Genes Encoding ◽  
Uremic Syndrome ◽  
Complement Regulator ◽  
Related Proteins ◽  
Factor H Autoantibodies

Abstract Factor H autoantibodies have been reported in approximately 10% of patients with atypical hemolytic uremic syndrome (aHUS) and are associated with deficiency of factor H–related proteins 1 and 3. In this study we examined the prevalence of factor H autoantibodies in the Newcastle cohort of aHUS patients, determined whether the presence of such autoantibodies is always associated with deficiency of factor H–related proteins 1 and 3, and examined whether such patients have additional susceptibility factors and/or mutations in the genes encoding complement regulator/activators. We screened 142 patients with aHUS and found factor H autoantibodies in 13 individuals (age 1-11 years). The presence of the autoantibodies was confirmed by Western blotting. By using multiplex ligation-dependent probe amplification we measured complement factor H–related (CFHR)1 and CFHR3 copy number. In 10 of the 13 patients there were 0 copies of CFHR1, and in 3 patients there were 2. In 3 of the patients with 0 copies of CFHR1 there was 1 copy of CFHR3, and these individuals exhibited a novel deletion incorporating CFHR1 and CFHR4. In 5 patients mutations were identified: 1 in CFH, 1 in CFI, 1 in CD46, and 2 in C3. The latter observation emphasizes that multiple concurrent factors may be necessary in individual patients for disease manifestation.

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