Atypical haemolytic uremic syndrome with refractory multiorgan involvement and heterozygous CFHR1/CFHR3 gene deletion.

BACKGROUND: We present this challenging case report of Atypical Haemolytic Uremic Syndrome (aHUS) presenting with multi-organ involvement in a patient and heterozygous CFHR1/CFHR3 gene variant, which was refractory to initial eculizumab therapy. CASE PRESENTATION: A forty-three year old female presented with aHUS and had heterozygous disease-associated deletions in the complement genes CFHR1/CFHR3. She had progressive kidney failure and severe extra-renal manifestations including cardiomyopathy and haemorrhagic cystitis; as well as pulmonary, gastrointestinal and neurological involvement. The initial kidney biopsy revealed thrombotic microangiopathy (TMA) changes involving all glomeruli. Clinical improvement was initially seen during eculizumab initiation with suppressed CH50 level, but a new rhinovirus/enterovirus upper respiratory tract infection triggered further severe multi-organ disease activity. The extra-renal manifestations stabilised, then ultimately improved after a period of eculizumab dose intensification. However, the impact on dose intensification on this improvement is unclear. Despite the extra-renal clinical improvement, she ultimately progressed to end-stage kidney disease (ESKD), commencing peritoneal dialysis for three years before undergoing a successful uncomplicated cadaveric kidney transplant without prophylactic eculizumab. Two years after transplant, she has excellent transplant graft function without any further disease recurrence. CONCLUSIONS: This case highlights the concept of extra-renal manifestations in aHUS initially resistant to eculizumab, which potentially responded to dose intensification. Whilst organ injuries are potentially reversible with timely targeted treatment, it appears that the kidneys are most vulnerable to injury.

Thrombotic microangiopathy associated with arboviral infection: Report of 3 cases.

Dengue fever and chikungunya are viral diseases that have spread rapidly throughout the world in recent decades. The occurrence of complications is well known, including prerenal acute kidney injury (AKI), which is usually thought to be caused by dehydration and fluid loss. Thrombotic microangiopathy (TMA) is an uncommon aggravation of dengue fever and chikungunya, with only a few cases described in the medical literature. The aim of this study is to present 3 cases of TMA associated with arboviral infection. Three patients with clinical history, laboratory test, and kidney biopsy results compatible with TMA were selected for the study, 2 of whom had a serological diagnosis of dengue fever and 1 of chikungunya. The 3 patients were followed up at the Federal University of Maranhão Hospital's Nephrology Service in 2018. A targeted gene panel sequencing (TGPS) plus multiple to atypical hemolytic uremic syndrome (aHUS) multiplex ligation-dependent probe amplification (MLPA) was performed in 2 of the patients and revealed in the patient 1 a heterozygous pathogenic variant in the gene THBD, as well as heterozygous deletions in CFH, CFHR1, and CFHR3. In the patient 2, there were heterozygous pathogenic variant in the genes CFI and CFB, in addition to heterozygous deletions in the genes CFHR1 and CFHR3. Both received treatment with eculizumab and undergone recovery of renal function. The third patient had TMA not classified as either aHUS or thrombotic thrombocytopenic purpura (TTP); he abandoned the treatment and returned to the service after 2 years for a dialysis emergency. Patients with arboviral infectious disease and changes that suggest TMA should have appropriate support to establish early diagnosis and useful treatment.

Tuning the Functionality by Splicing: Factor H and Its Alternative Splice Variant FHL-1 Share a Gene but Not All Functions.

The alternative pathway regulator Factor H-like protein 1 (FHL-1) is composed of the first 7 N-terminal complement control protein domains of Factor H (FH) and protects host surfaces from uncontrolled complement attack. Although FHL-1 shares the N-terminal regulatory domains with FH, it was thought to be a weaker regulator. Recently, the regulatory activity of FHL-1 was shown to be comparable to FH. Nonetheless, the question remained whether FHL-1 is an indispensable, unique regulator. The discovery that FHL-1 is the predominant regulator on Bruch's membrane, a critical site for the onset and progression of age-related-macular degeneration (AMD), showed that FHL-1 is essential for complement regulation. A common single nucleotide polymorphism in FH/FHL-1 that predisposes for AMD underlines the important role of FHL-1 in this context. Reports that some cancer tissues specifically upregulate FHL-1 expression, thereby evading immune surveillance, suggests a pronounced regulatory activity of the splice variant. Several microorganisms specifically recruit FHL-1 to evade complement attack. From a phylogenetic point of view, FHL-1 appears much later than other complement regulators, which could imply a specific role that is possibly not systemic but rather tissue specific. This review focuses on the current knowledge of FHL-1 and its physiological and pathophysiological roles.

CFHR1 is a potentially downregulated gene in lung adenocarcinoma.

There is increasing evidence that human complement factor H­related protein 1 (CFHR1) plays a crucial role in the development of malignant diseases. However, few studies have identified the roles of CFHR1 in the occurrence and prognosis of lung adenocarcinoma (LADC). In the present study, comprehensive bioinformatic analyses of data obtained from the Oncomine platform, UALCAN and Gene Expression Profiling Interactive Analysis (GEPIA) demonstrated that CFHR1 expression is significantly reduced in both LADC tissues and cancer cells. The patients presenting with downregulation of CFHR1 had significantly lower overall survival (OS) and post progression survival (PPS) times. Through analysis of the datasets from Gene Expression Omnibus database, we found that the compound actinomycin D promoted CFHR1 expression, further displaying the cytotoxic effect in the LADC cell line A549. In addition, the expression level of CFHR1 in the cisplatin­resistant LADC cell line CDDP­R (derived from H460) was also significantly reduced. Our research demonstrated that low levels of CFHR1 are specifically found in LADC samples, and CFHR1 could serve as a potential therapeutic target for this subset of lung cancers. Determination of the detailed roles of CFHR1 in LADC biology could provide insightful information for further investigations.

Evaluation of serum sphingolipids and the influence of genetic risk factors in age-related macular degeneration.

Sphingolipids are bioactive molecules associated with oxidative stress, inflammation, and neurodegenerative diseases, but poorly studied in the context of age-related macular degeneration (AMD), a prevalent sight-threatening disease of the ageing retina. Here, we found higher serum levels of hexosylceramide (HexCer) d18:1/16:0 in patients with choroidal neovascularization (CNV) and geographic atrophy (GA), two manifestations of late stage AMD, and higher ceramide (Cer) d18:1/16:0 levels in GA patients. A sensitivity analysis of genetic variants known to be associated with late stage AMD showed that rs1061170 (p.Y402H) in the complement factor H (CFH) gene influences the association of Cer d18:1/16:0 with GA. To understand the possible influence of this genetic variant on ceramide levels, we established a cell-based assay to test the modulation of genes in the ceramide metabolism by factor H-like protein 1 (FHL-1), an alternative splicing variant of CFH that also harbors the 402 residue. We first showed that malondialdehyde-acetaldehyde adducts, an oxidation product commonly found in AMD retinas, induces an increase in ceramide levels in WERI-Rb1 cells in accordance with an increased expression of ceramide synthesis genes. Then, we observed that cells exposed to the non-risk FHL-1:Y402, but not the risk associated variant FHL-1:H402 or full-length CFH, downregulated ceramide synthase 2 and ceramide glucosyltransferase gene expression. Together, our findings show that serum ceramide and hexosylceramide species are altered in AMD patients and that ceramide levels may be influenced by AMD associated risk variants.

The complement factor H (CFH) and its related protein 2 (CFHR2) mediating immune response in large yellow croaker Larimichthys crocea.

Complement is a complex innate immune surveillance system, playing a key role in host homeostasis, inflammation, and in the defense against pathogens. Complement regulators are crucial to prevent the injudicious production of these mediators and potential injury to self tissues. Here, we identified the complement factor H (CFH) and its related gene 2 (CFHR2) homologs from large yellow croaker (Larimichthys crocea), named LcCfh and LcCfhr2, respectively. The deduced LcCfh and LcCfhr2 proteins shared significant structural similarities and identified codes for a polypeptide consisting of various numbers of highly conserved SCR domains. LcCfh, LcCfhr1 and LcCfhr2 genes were detected in all examined tissues with predominantly expressions in liver, spleen and kidney, and their expressions all increased upon Vibrio alginolyticus challenge. In vitro assays showed that recombinant LcCfh was likely to act as a cofactor of CFI and played a negative regulation role in complement system, when recombinant LcCfhr2 seemed to play mechanisms independent of the activity of CFH. Both recombinant LcCfh and LcCfhr2 took participate in inflammatory reaction despite of the inequal ability to mediate pro-inflammation response. These data provide a new insight into the functional activities of teleost complement system.

Atypical presentation of atypical haemolytic uraemic syndrome.

A 17-year-old girl presented with fever, myalgia, vomiting for 1 month and oliguria and dyspnoea for 4 days. She was tachycardic,hypertensive, with pedal oedema and decreased breath sounds. She had high serum creatinine (3 mg/dL), anaemia, thrombocytopenia, leucocytosis and eosinophilia with schistocytes. Lactate dehydrogenase, transaminases were high , with low haptoglobin and high ferritin (5269 ng/mL). Complement C3/C4 and fibrinogen were normal. Urinalysis showed large blood and protein and stool studies were negative. Her ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) was normal. Kidney biopsy showed acute interstitial nephritis (AIN) in addition to thrombotic angiopathy. The differentials - haemolytic uraemic syndrome (HUS), thrombotic thrombocytopenia (TTP) and haemophagocytic lymphohistiocytosis (HLH) were ruled out. Her genetic testing was abnormal for large CFHR1-CFHR3 homozygous deletion and heterozygous missense variant in exon 2 of DGKE making the diagnosis of atypical HUS. She received eculizumab and was discharged on oral steroids for AIN and biweekly eculizumab infusions with excellent recovery.

A Heterozygous CFHR3-CFHR1 Gene Deletion in a Pediatric Patient With Transplant-associated Thrombotic Microangiopathy Who was Treated With Eculizumab.

Complement system dysregulation, such as complement Factor H (CFH) autoantibodies and deletions in CFH-related (CFHR) genes 3 and 1, might cause transplant-associated thrombotic microangiopathy (TA-TMA). The use of eculizumab, a terminal complement inhibitor, could be a targeted therapy for TA-TMA. We report a 1-year-old girl who developed TA-TMA, just after autologous peripheral blood stem cell transplantation in neuroblastoma therapy. Eculizumab improved TA-TMA. Investigation for the complement alternative pathway showed a heterozygous CFHR3-CFHR1 gene deletion, which is involved in complement activation. The patient might develop TA-TMA as a result of complement regulatory gene mutation.

Deletion Variants of CFHR1 and CFHR3 Associate with Mesangial Immune Deposits but Not with Progression of IgA Nephropathy.

Activation of complement through the alternative pathway has a key role in the pathogenesis of IgA nephropathy (IgAN). Large, international, genome-wide association studies have shown that deletion of complement factor H-related genes 1 and 3 (CFHR3,1Δ) is associated with a reduced risk of developing IgAN, although the prognostic value of these deletions in IgAN remains unknown. Here, we compared the renal outcomes of patients with IgAN according to their CFHR3,1Δ genotype. This retrospective, monocentric cohort study included 639 white patients with biopsy-proven IgAN since 1979 (mean age at diagnosis, 40.1 years; median follow-up, 132 months). We determined the number of CFHR3 and CFHR1 gene copies by quantitative PCR and collected clinical and biologic data by reviewing the patients' medical records. In all, 30.5% of the patients were heterozygous and 4% were homozygous for CFHR3,1Δ We did not detect an association between CFHR3,1Δ and age, eGFR, urinary protein excretion rate, or the presence of hypertension or hematuria at the time of diagnosis. The mean intensities of immune IgA, IgG, and C3 deposits were lower in the group with heterozygous or homozygous gene deletions than in those with no deletion. However, CFHR3,1Δ did not associate with progression to stage 3 CKD or renal death. In conclusion, the CFHR3,1Δ genotype did not associate with progression toward CKD stages 3 and 5 in our white population of patients with IgAN, although it did associate with a reduced level of glomerular immune deposits.

Complement-Regulatory Proteins CFHR1 and CFHR3 and Patient Response to Anti-CD20 Monoclonal Antibody Therapy.

Purpose: Anti-CD20 mAb therapies, including rituximab and obinutuzumab (GA101), are common treatments for follicular lymphoma. In an effort to better understand the role of complement in mAb action, we recently performed germline SNP profiling on 142 follicular lymphoma patients and found rs3766404 genotype correlated with patient response to rituximab. To assess the role of three SNP-associated complement-regulatory proteins (CFH, CFHR1, and CFHR3) in clinical response to anti-CD20 mAb, we studied two cohorts of patients treated with anti-CD20 mAb.Experimental Design: Cohorts included the Iowa/Mayo Lymphoma SPORE observational cohort of subjects with a new diagnosis of follicular lymphoma treated with rituximab and the GAUSS prospective randomized trial cohort of follicular lymphoma subjects randomized to receive single-agent rituximab or obinutuzumab. Circulating protein expression was measured for CFH, CFHR1, and CFHR3 and correlated to clinical outcome.Results: rs3766404 genotype correlated with expression of the related downstream genes CFHR1 and CFHR3 Loss of CFHR1 expression correlated with inferior patient outcome in the observational cohort, but not in the GAUSS cohort. Loss of CFHR3 correlated with superior event-free survival in GAUSS subjects treated with obinutuzumab, but not rituximab.Conclusions: We conclude that the relationship between complement-regulatory proteins CFHR1 and CFHR3 and response to anti-CD20 mAb therapy varies based on the specific anti-CD20 mAb used. We propose that CFHR3 is a candidate biomarker for obinutuzumab response. Further studies are needed to validate these findings and to better understand how complement pathways and complement-regulatory proteins impact on the efficacy of anti-CD20 mAb therapy. Clin Cancer Res; 23(4); 954-61. ©2016 AACR.

CFHR1-Modified Neural Stem Cells Ameliorated Brain Injury in a Mouse Model of Neuromyelitis Optica Spectrum Disorders.

A major hurdle for effective stem cell therapy is ongoing inflammation in the target organ. Reconditioning the lesion microenvironment may be an effective way to promote stem cell therapy. In this study, we showed that engineered neural stem cells (NSCs) with complement factor H-related protein 1, a complement inhibitor protein, can attenuate inflammatory infiltration and immune-mediated damage of astrocytes, an important pathogenic progress in patients with neuromyelitis optica spectrum disorders. Furthermore, we demonstrated that transplantation of the complement factor H-related protein 1-modified NSCs effectively blocked the complement activation cascade and inhibited formation of the membrane attack complex, thus contributing to the protection of endogenous and transplanted NSC-differentiated astrocytes. Therefore, manipulation of the lesion microenvironment contributes to a more effective cell replacement therapeutic strategy for autoimmune diseases of the CNS.

CD55, CD59, factor H and factor H-like 1 gene expression analysis in tumors of the ovary and corpus uteri origin.

The expression level of complement regulators in ovarian and corpus uteri tumors was not fully established so far. In current manuscript we performed gene expression analysis by the real-time PCR approach to investigate both membrane bound - CD55 and CD59 and fluid phase - factor H and factor H-like 1 complement regulators. We found increased CD55 expression in corpus uteri tumors when compared to control tissues, whereas in ovarian cancer CD55 expression was lower than in control sections. Additionally we found CD59 expression to be more prominent in ovarian cancer than in corpus uteri tumor samples. We observed also the strong positive correlation between the level of expression of the whole group of regulators, which was particularly significant between the expression of factor H and factor H- like 1. In conclusion we present novel results which implicates different role of particular complement inhibitors in the regulation of the complement system in two cancer types examined. Strong positive correlation between examined proteins implicates similar pattern of the regulation which should be taken into consideration with regards to the possible immunotherapy applied as adjuvant therapeutic approach in these two indications. The inhibition of complement regulation may serve as a strategy to potentiate the efficacy of such treatment.

Kidney Disease Caused by Dysregulation of the Complement Alternative Pathway: An Etiologic Approach.

Kidney diseases caused by genetic or acquired dysregulation of the complement alternative pathway (AP) are traditionally classified on the basis of clinical presentation (atypical hemolytic uremic syndrome as thrombotic microangiopathy), biopsy appearance (dense deposit disease and C3 GN), or clinical course (atypical postinfectious GN). Each is characterized by an inappropriate activation of the AP, eventuating in renal damage. The clinical diversity of these disorders highlights important differences in the triggers, the sites and intensity of involvement, and the outcome of the AP dysregulation. Nevertheless, we contend that these diseases should be grouped as disorders of the AP and classified on an etiologic basis. In this review, we define different pathophysiologic categories of AP dysfunction. The precise identification of the underlying abnormality is the key to predict the response to immune suppression, plasma infusion, and complement-inhibitory drugs and the outcome after transplantation. In a patient with presumed dysregulation of the AP, the collaboration of the clinician, the renal pathologist, and the biochemical and genetic laboratory is very much encouraged, because this enables the elucidation of both the underlying pathogenesis and the optimal therapeutic approach.

Favorable four-yr outcome after renal transplantation in a patient with complement factor H antibody and CFHR1/CFHR3 gene mutation-associated HUS.

UNLABELLED: aHUS is a clinical challenge for successful renal transplantation. CASE REPORT: A 14-yr-old girl lost her kidneys at the age of 7, due to CFH antibodies and CFH-related protein (CFHR1/CFHR3) homozygous deletion-associated aHUS. CFH, CFI, and MCP gene mutations were excluded. The patient was a candidate for renal transplantation despite persistent presence of CFH antibodies (up to 539 AU/mL). Treatment with MMF, IVIG, and repeated PF (n = 8) was introduced while being placed on urgent waiting list. Three years after aHUS onset, the patient underwent the deceased donor renal transplantation "under cover" of PF, as PF was performed directly prior to surgery and, then, PFs were repeated up to overall 14 sessions. Quadruple immunosuppression (basiliximab + tacrolimus + MMF + prednisolone) was used. Moderate symptoms of aHUS (hemolysis, low platelets, and low C3) were present within first seven days post-transplant and then normalized with PF therapy. The patient remained stable during four yr of further follow-up after transplantation. CONCLUSION: Specific pre- and post-transplant management allowed successful renal transplantation in a CFH antibody-positive patient.

The role of complement in C3 glomerulopathy.

C3 glomerulopathy describes a spectrum of disorders with glomerular pathology associated with C3 cleavage product deposition and with defective complement action and regulation (Fakhouri et al., 2010; Sethi et al., 2012b). Kidney biopsies from these patients show glomerular accumulation or deposition of C3 cleavage fragments, but no or minor deposition of immunoglobulins (Appel et al., 2005; D'Agati and Bomback, 2012; Servais et al., 2007; Sethi and Fervenza, 2011). At present the current situation asks for a better definition of the underlining disease mechanisms, for precise biomarkers, and for a treatment for this disease. The complement system is a self activating and propelling enzymatic cascade type system in which inactive, soluble plasma components are activated spontaneously and lead into an amplification loop (Zipfel and Skerka, 2009). Activation of the alternative pathway is spontaneous, occurs by default, and cascade progression leads to amplification by complement activators. The system however is self-controlled by multiple regulators and inhibitors, like Factor H that control cascade progression in fluid phase and on surfaces. The activated complement system generates a series of potent effector components and activation products, which damage foreign-, as well as modified self cells, recruit innate immune cells to the site of action, coordinate inflammation and the response of the adaptive immune system in form of B cells and T lymphocytes (Kohl, 2006; Medzhitov and Janeway, 2002; Ogden and Elkon, 2006; Carroll, 2004; Kemper and Atkinson, 2007; Morgan, 1999; Muller-Eberhard, 1986; Ricklin et al., 2010). Complement controls homeostasis and multiple reactions in the vertebrate organism including defense against microbial infections (Diaz-Guillen et al., 1999; Mastellos and Lambris, 2002; Nordahl et al., 2004; Ricklin et al., 2010). In consequence defective control of the spontaneous self amplifying cascade or regulation is associated with numerous human disorders (Ricklin and Lambris, 2007; Skerka and Zipfel, 2008; Zipfel et al., 2006). Understanding the exact action and regulation of this sophisticated homeotic cascade system is relevant to understand disease pathology of various complement associated human disorders. Furthermore this knowledge is relevant for a better diagnosis and appropriate therapy. At present diagnosis of C3 glomerulopathy is primarily based on the kidney biopsy, and histological, immmunohistological and electron microscopical evaluation (D'Agati and Bomback, 2012; Fakhouri et al., 2010; Medjeral-Thomas et al., 2014a,b; Sethi et al., 2012b). The challenge is to define the actual cause of the diverse glomerular changes or damages, to define how C3 deposition results in the reported glomerular changes, the location of the cell damage and the formation of deposits.

Atypical aHUS: State of the art.

Tremendous advances in our understanding of the thrombotic microangiopathies (TMAs) have revealed distinct disease mechanisms within this heterogeneous group of diseases. As a direct result of this knowledge, both children and adults with complement-mediated TMA now enjoy higher expectations for long-term health. In this update on atypical hemolytic uremic syndrome, we review the clinical characteristics; the genetic and acquired drivers of disease; the broad spectrum of environmental triggers; and current diagnosis and treatment options. Many questions remain to be addressed if additional improvements in patient care and outcome are to be achieved in the coming decade.

Localization of complement factor H gene expression and protein distribution in the mouse outer retina.

PURPOSE: To determine the localization of complement factor H (Cfh) mRNA and its protein in the mouse outer retina. METHODS: Quantitative real-time PCR (qPCR) was used to determine the expression of Cfh and Cfh-related (Cfhr) transcripts in the RPE/choroid. In situ hybridization (ISH) was performed using the novel RNAscope 2.0 FFPE assay to localize the expression of Cfh mRNA in the mouse outer retina. Immunohistochemistry (IHC) was used to localize Cfh protein expression, and western blots were used to characterize CFH antibodies used for IHC. RESULTS: Cfh and Cfhr2 transcripts were detected in the mouse RPE/choroid using qPCR, while Cfhr1, Cfhr3, and Cfhrc (Gm4788) were not detected. ISH showed abundant Cfh mRNA in the RPE of all mouse strains (C57BL/6, BALB/c, 129/Sv) tested, with the exception of the Cfh(-/-) eye. Surprisingly, the Cfh protein was detected by immunohistochemistry in photoreceptors rather than in RPE cells. The specificity of the CFH antibodies was tested by western blotting. Our CFH antibodies recognized purified mouse Cfh protein, serum Cfh protein in wild-type C57BL/6, BALB/c, and 129/Sv, and showed an absence of the Cfh protein in the serum of Cfh(-/-) mice. Greatly reduced Cfh protein immunohistological signals in the Cfh(-/-) eyes also supported the specificity of the Cfh protein distribution results. CONCLUSIONS: Only Cfh and Cfhr2 genes are expressed in the mouse outer retina. Only Cfh mRNA was detected in the RPE, but no protein. We hypothesize that the steady-state concentration of Cfh protein is low in the cells due to secretion, and therefore is below the detection level for IHC.

Growth of geographic atrophy on fundus autofluorescence and polymorphisms of CFH, CFB, C3, FHR1-3, and ARMS2 in age-related macular degeneration.

IMPORTANCE: Identification of the genetic risk factors that contribute to geographic atrophy (GA) could lead to advancements in interventional trials and/or therapeutic approaches for combating vision loss. OBJECTIVE: To investigate whether single-nucleotide polymorphisms (SNPs) are associated with the presence and progression of established GA in age-related macular degeneration (AMD). DESIGN, SETTING, AND PARTICIPANTS: Prospective, controlled, multicenter study of 154 patients with GA/AMD and 141 age-matched control participants at 8 Spanish hospitals. MAIN OUTCOMES AND MEASURES: Samples of DNA were collected to analyze SNPs within AMD-related genes (CFH, CFB, C3, FHR1-3, and ARMS2). Fundus autofluorescence imaging was used to evaluate GA progression during a 2-year period in 73 patients with GA/AMD. Finally, logistic regression was used to analyze the associations of SNPs, age, body mass index, and cigarette smoking with the rate of progression and relative growth of GA. RESULTS: This case-control analysis revealed a significant (P < .05) association between the presence of GA and SNPs within CFH, ARMS2, and FHR1-3. Moreover, logistic regression analysis identified significant associations of the rate of progression with genetic polymorphisms (CFH-402His [P = .04] and CFH-62Ile [P = .04]) and demographic factors (sex [P = .02] and age [P = .02]), whereas relative growth was associated with 1 polymorphism (CFB-32Gln [P = .04]).Conclusions and Relevance Taken together, our findings confirm that genetic risk factors related to the presence of GA are not identical to those associated with GA progression. In fact, we demonstrate that gene variants of CFH and CFB, as well as demographic risk factors, confer significant risk for GA progression (both rate of progression and relative growth) within a Spanish population.