116 results found
Lou H, Wojciak-Stothard B, Ruseva MM, et al., 2020, Autoantibody-dependent amplification of inflammation in SLE, Cell Death and Disease, Vol: 11, ISSN: 2041-4889
Anti-double stranded DNA antibodies (anti-dsDNA) are a hallmark of SLE but their role in disease pathogenesis is not fully resolved. Anti-dsDNA in serum are highly heterogeneous therefore in this study, we aimed to dissect the functional specificities of anti-dsDNA using a panel of human monoclonal antibodies (humAbs) generated from patients with active lupus nephritis. A total of 46 ANA reactive humAbs were isolated and divided into four broad classes based on their reactivity to histones, DNA and Crithidia. Functional analysis indicated that one subclass of antibodies bound strongly to decondensed DNA areas in neutrophil extracellular traps (NETs) and protected NETs from nuclease digestion, similar to the sera from active SLE patients. In addition, these anti-dsDNA antibodies could stimulate type I interferon responses in mononuclear phagocytic cells, or NF-kB activity in endothelial cells, by uptake of NETs-anti-NETs immune complexes and subsequently trigging inflammatory responses in an Fc-gamma receptor (Fcg-R)-dependant manner. Together our data suggest that only a subset of anti-dsDNA antibodies is capable to amplify inflammatory responses by deposit in the nephritic kidney in vivo, protecting NETs digestion as well as uptake of NETs immune complexes into Fcg-R-expressing cells in vitro.
Clarke C, Prendecki M, Dhutia A, et al., 2020, High prevalence of asymptomatic COVID-19 infection in hemodialysis patients detected using serologic screening., Journal of the American Society of Nephrology, Vol: 31, Pages: 1-8, ISSN: 1046-6673
BACKGROUND: Strategies to minimize the risk of transmission and acquisition of COVID-19 infection in patients with ESKD receiving in-center hemodialysis have been rapidly implemented across the globe. Despite these interventions, confirmed COVID-19 infection rates have been high in the United Kingdom. Prevalence of asymptomatic disease in an adult hemodialysis population has not been reported. Also, to our knowledge, the development of humoral response to SARS-CoV-2 has not been previously reported in this population. Although serologic testing does not provide information on the infectivity of patients, seroprevalence studies may enable investigation of exposure within dialysis units and hence, assessment of current screening strategies. METHODS: To investigate the seroprevalence of SARS-CoV-2 antibodies in a hemodialysis population, we used the Abbott IgG assay with the Architect system to test serum samples from 356 patients receiving in-center hemodialysis for SARS-CoV-2 antibodies. RESULTS: Of 356 patients, 121 had been symptomatic when screened before a dialysis session and received an RT-PCR test; 79 (22.2% of the total study population) tested positive for COVID-19. Serologic testing of all 356 patients found 129 (36.2%) who tested positive for SARS-CoV-2 antibodies. Only two patients with PCR-confirmed infection did not seroconvert. Of the 129 patients with SARS-CoV-2 antibodies, 52 (40.3%) had asymptomatic disease or undetected disease by PCR testing alone. CONCLUSIONS: We found a high seroprevalence of SARS-CoV-2 antibodies in patients receiving in-center hemodialysis. Serologic evidence of previous infection in asymptomatic or PCR-negative patients suggests that current diagnostic screening strategies may be limited in their ability to detect acute infection.
Merle NS, Leon J, Poillerat V, et al., 2020, Circulating FH Protects Kidneys From Tubular Injury During Systemic Hemolysis, FRONTIERS IN IMMUNOLOGY, Vol: 11, ISSN: 1664-3224
Laskowski J, Renner B, Pickering MC, et al., 2020, Complement factor H-deficient mice develop spontaneous hepatic tumors., J Clin Invest, Vol: 130, Pages: 4039-4054
Hepatocellular carcinoma (HCC) is difficult to detect, carries a poor prognosis, and is one of few cancers with an increasing yearly incidence. Molecular defects in complement factor H (CFH), a critical regulatory protein of the complement alternative pathway (AP), are typically associated with inflammatory diseases of the eye and kidney. Little is known regarding the role of CFH in controlling complement activation within the liver. While studying aging CFH-deficient (fH-/-) mice, we observed spontaneous hepatic tumor formation in more than 50% of aged fH-/- males. Examination of fH-/- livers (3-24 months) for evidence of complement-mediated inflammation revealed widespread deposition of complement-activation fragments throughout the sinusoids, elevated transaminase levels, increased hepatic CD8+ and F4/80+ cells, overexpression of hepatic mRNA associated with inflammatory signaling pathways, steatosis, and increased collagen deposition. Immunostaining of human HCC biopsies revealed extensive deposition of complement fragments within the tumors. Investigating the Cancer Genome Atlas also revealed that increased CFH mRNA expression is associated with improved survival in patients with HCC, whereas mutations are associated with worse survival. These results indicate that CFH is critical for controlling complement activation in the liver, and in its absence, AP activation leads to chronic inflammation and promotes hepatic carcinogenesis.
Nayagam JS, McGrath S, Montasser M, et al., 2020, Successful simultaneous liver-kidney transplantation for renal failure associated with hereditary complement C3 deficiency., American Journal of Transplantation, Vol: 20, Pages: 2260-2263, ISSN: 1600-6135
Hereditary complement C3 deficiency is associated with recurrent bacterial infections and proliferative glomerulonephritis. We describe a case of an adult with complete deficiency of complement C3 due to homozygous mutations in C3 gene: c.1811delT (Val604Glyfs*2), recurrent bacterial infections, crescentic glomerulonephritis and end-stage renal failure. Following isolated kidney transplantation he would remain C3 deficient with a similar, or increased, risk of infections and glomerulonephritis. As C3 is predominantly synthesised in the liver, with a small proportion of C3 monocyte-derived and kidney-derived, he proceeded to simultaneous liver-kidney transplantation. The procedure has been successful with restoration of his circulating C3 levels, normal liver and kidney function at 26 months of follow up. Simultaneous liver-kidney transplant is a viable option to be considered in this rare setting.
Kasanmoentalib ES, Seron MV, Engelen-Lee JY, et al., 2019, Complement factor H contributes to mortality in humans and mice with bacterial meningitis, Journal of Neuroinflammation, Vol: 16, Pages: 1-14, ISSN: 1742-2094
BackgroundThe complement system is a vital component of the inflammatory response occurring during bacterial meningitis. Blocking the complement system was shown to improve the outcome of experimental pneumococcal meningitis. Complement factor H (FH) is a complement regulatory protein inhibiting alternative pathway activation but is also exploited by the pneumococcus to prevent complement activation on its surface conferring serum resistance.MethodsIn a nationwide prospective cohort study of 1009 episodes with community-acquired bacterial meningitis, we analyzed whether genetic variations in CFH influenced FH cerebrospinal fluid levels and/or disease severity. Subsequently, we analyzed the role of FH in our pneumococcal meningitis mouse model using FH knock-out (Cfh−/−) mice and wild-type (wt) mice. Finally, we tested whether adjuvant treatment with human FH (hFH) improved outcome in a randomized investigator blinded trial in a pneumococcal meningitis mouse model.ResultsWe found the major allele (G) of single nucleotide polymorphism in CFH (rs6677604) to be associated with low FH cerebrospinal fluid concentration and increased mortality. In patients and mice with bacterial meningitis, FH concentrations were elevated during disease and Cfh−/− mice with pneumococcal meningitis had increased mortality compared to wild-type mice due to C3 depletion. Adjuvant treatment of wild-type mice with purified human FH led to complement inhibition but also increased bacterial outgrowth which resulted in similar disease outcomes.ConclusionLow FH levels contribute to mortality in pneumococcal meningitis but adjuvant treatment with FH at a clinically relevant time point is not beneficial.
Malik TH, Lavin D, Gitterman DP, et al., 2019, THE FIRST MODEL OF FHR-ASSOCIATED C3 GLOMERULOPATHY DEMONSTRATES THE DIRECT PATHOGENICITY OF MUTANT FHR5 PROTEINS, 17th European Meeting on Complement in Human Disease (EMCHD), Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 449-450, ISSN: 0161-5890
Vyas FS, Yang Y, Pappworth IY, et al., 2019, A MOUSE HOMODIMERIC MINI-FH CONSTRUCT PROVIDES LONG TERM PROTECTION FROM KIDNEY DISEASE IN A MOUSE MODEL OF C3G, 17th European Meeting on Complement in Human Disease (EMCHD), Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 452-453, ISSN: 0161-5890
IgA nephropathy (IgAN) is common and often progresses to end stage renal disease. IgAN encompasses a wide range of histology and clinical features. 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. Recent identification of specific complement pathways and proteins in severe IgAN cases had advanced our understanding of complement in IgAN pathogenesis. In particular, a growing body of evidence implicates the complement factor H related proteins 1 and 5 and lectin pathway as pathogenic in a subset of patients with severe disease. These data suggest complement deregulation and activity may be dominant drivers of renal injury in IgAN. Thereby, markers of complement activation may identify IgAN patients likely to progress to significant renal impairment and complement inhibition may emerge as an effective method of preventing and reducing glomerular injury in IgAN.
Medjeral-Thomas NR, Moffitt H, Lomax-Browne HJ, et al., 2019, Glomerular complement factor H–related protein 5 (FHR5) is highly Prevalent in C3 glomerulopathy and associated with renal impairment, Kidney International Reports, Vol: 4, Pages: 1387-1400, ISSN: 2468-0249
IntroductionTherapeutic agents that target complement are increasingly available for glomerular diseases. However, the mechanisms linking glomerular complement deposition with inflammation and damage are incompletely understood. Complement factor H–related protein 5 (FHR5) interacts with complement C3 and is considered to promote activation. Circulating and glomerular FHR5 associates with IgA nephropathy and abnormal FHR5 associates with familial C3 glomerulopathy (C3G). We characterized glomerular FHR5 staining in C3G and assessed its relationships with histological features of glomerular injury and clinical outcome.MethodsWe developed FHR5 staining protocols for formalin-fixed paraffin-embedded (FFPE) renal tissue and applied them to surplus biopsy sections from a C3G cohort.ResultsGlomerular FHR5 was highly prevalent in native and transplant C3G and correlated with glomerular C3 and C5b-9 staining. Glomerular FHR5 staining correlated negatively with estimated glomerular filtration rate (eGFR) (P = 0.04, difference of medians 19.7 ml/min per 1.73 m2; 95% confidence interval [CI] 1.1–43.0) and positively with a membranoproliferative glomerulonephritis pattern at diagnostic biopsy (odds ratio 18; 95% CI 1.6–201; P = 0.049). Glomerular FHR5 staining intensity positively correlated with glomerular complement C3b/iC3b/C3c (Pearson’s correlation coefficient [R] = 0.59; P = 0.0008), C3dg (R = 0.47; P = 0.02) and C5b9 (R = 0.44, P = 0.02).ConclusionsGlomerular FHR5 is highly prevalent in C3G, interacts with glomerular C3, and is associated with markers of disease severity. Glomerular FHR5 likely exacerbates complement-mediated glomerular damage in C3G and its interaction with glomerular complement might be exploited to target complement therapeutic agents.
Kiss MG, Ozsvar-Kozma M, Porsch F, et al., 2019, Complement Factor H Modulates Splenic B Cell Development and Limits Autoantibody Production, FRONTIERS IN IMMUNOLOGY, Vol: 10, ISSN: 1664-3224
Foschi V, Bortolotti D, Doyle AF, et al., 2019, Analysis of HLA-G expression in renal tissue in lupus nephritis: a pilot study, Lupus, Vol: 28, Pages: 1091-1100, ISSN: 1477-0962
BACKGROUND: The study aimed to investigate whether HLA-G antigen is expressed in the kidneys of patients affected by lupus nephritis (LN) and whether its detection in renal biopsies could be adopted as a marker of treatment response and prognosis. METHODS: Thirty renal biopsies from patients with LN were selected and analyzed through immunohistochemistry. Laboratory and clinical data were retrospectively collected at baseline, 6 and 12 months and at the latest clinical appointment. A number of patients (63.3%) were treated with rituximab (RTX) +/- methylprednisolone in the induction phase. The expression of HLA-G in glomeruli, tubules and infiltrating cells was examined and compared between lupus patients who achieved either complete or partial renal response and those who did not respond to treatment. RESULTS: HLA-G staining was observed in the glomeruli of 20 of 30 samples from patients with LN. The expression of the antigen was detected in podocytes, along glomerular capillary walls, on parietal glomerular epithelial cells and within the juxtaglomerular apparatus. Seventy per cent of patients whose glomeruli expressed HLA-G achieved partial or complete response at 6 months and 75% at the latest available follow up compared with 30% and 40%, respectively, of those who did not show any expression. The pattern of staining in tubules and infiltrating cells was highly variable precluding any clinical correlation. CONCLUSION: This study demonstrates that HLA-G is expressed in renal tissue in LN. Our retrospective data suggest that its expression could correlate with response to treatment.
Smith RJH, Appel GB, Blom AM, et al., 2019, C3 glomerulopathy - understanding a rare complement-driven renal disease, NATURE REVIEWS NEPHROLOGY, Vol: 15, Pages: 129-143, ISSN: 1759-5061
Smith-Jackson K, Yang Y, Denton H, et al., 2019, Hyperfunctional complement C3 promotes C5-dependent atypical hemolytic uremic syndrome in mice, Journal of Clinical Investigation, Vol: 129, Pages: 1061-1075, ISSN: 0021-9738
Atypical hemolytic uremic syndrome (aHUS) is frequently associated in humans with loss-of-function mutations in complement-regulating proteins or gain-of-function mutations in complement-activating proteins. Thus, aHUS provides an archetypal complement-mediated disease with which to model new therapeutic strategies and treatments. Herein, we show that, when transferred to mice, an aHUS-associated gain-of-function change (D1115N) to the complement-activation protein C3 results in aHUS. Homozygous C3 p.D1115N (C3KI) mice developed spontaneous chronic thrombotic microangiopathy together with hematuria, thrombocytopenia, elevated creatinine, and evidence of hemolysis. Mice with active disease had reduced plasma C3 with C3 fragment and C9 deposition within the kidney. Therapeutic blockade or genetic deletion of C5, a protein downstream of C3 in the complement cascade, protected homozygous C3KI mice from thrombotic microangiopathy and aHUS. Thus, our data provide in vivo modeling evidence that gain-of-function changes in complement C3 drive aHUS. They also show that long-term C5 deficiency is not accompanied by development of other renal complications (such as C3 glomerulopathy) despite sustained dysregulation of C3. Our results suggest that this preclinical model will allow testing of novel complement inhibitors with the aim of developing precisely targeted therapeutics that could have application in many complement-mediated diseases.
Floege J, Barbour SJ, Cattran DC, et al., 2019, Management and treatment of glomerular diseases (part 1): conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference, Publisher: ELSEVIER SCIENCE INC, Pages: 268-280, ISSN: 0085-2538
Rovin BH, Caster DJ, Cattran DC, et al., 2019, Management and treatment of glomerular diseases (part 2): conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference, Publisher: ELSEVIER SCIENCE INC, Pages: 281-295, ISSN: 0085-2538
Wilson HR, Medjeral-Thomas NR, Gilmore AC, et al., 2019, Glomerular membrane attack complex is not a reliable marker of ongoing C5 activation in lupus nephritis, Kidney International, Vol: 95, Pages: 655-665, ISSN: 0085-2538
Complement plays an important role in the pathogenesis of lupus nephritis (LN). With the emergence of therapeutic complement inhibition, there is a need to identify patients in whom complement-driven inflammation is a major cause of kidney injury in LN. Clinical and histopathological data were obtained retrospectively from 57 biopsies with class III, IV, and V LN. Biopsies were stained for complement components C9, C5b-9, C3c, and C3d and for the macrophage marker CD68. C9 and C5b-9 staining were highly correlated (r = 0.92 in the capillary wall). C5b-9 staining was detected in the mesangium and/or capillary wall of both active and chronic proliferative LN in all but one biopsy and in the capillary wall of class V LN in all biopsies. C5b-9 staining intensity in the tubular basement membrane correlated with markers of tubulointerstitial damage, and more intense capillary wall C5b-9 staining was significantly associated with nonresponse to conventional treatment. Glomerular C5b-9 staining intensity did not differ between active and chronic disease; in contrast, C3c and CD68 staining were associated with active disease. Evaluation of serial biopsies and comparison of staining in active and chronic LN demonstrated that C5b-9 staining persisted for months to years. These results suggest that C5b-9 staining is almost always present in LN, resolves slowly, and is not a reliable marker of ongoing glomerular C5 activation. This limits the utility of C5b-9 staining to identify patients who are most likely to benefit from C5 inhibition.
Zhu L, Guo W-Y, Shi S-F, et al., 2018, Circulating complement factor H-related protein 5 levels contribute to development and progression of IgA nephropathy, KIDNEY INTERNATIONAL, Vol: 94, Pages: 150-158, ISSN: 0085-2538
Koskinen AR, Cheng Z-Z, Pickering MC, et al., 2018, Distribution of exogenous complement factor H in mice invivo, Scandinavian Journal of Immunology, Vol: 88, ISSN: 0300-9475
Factor H is an important regulator of complement activation in plasma and on cell surfaces in both humans and mice. If FH function is compromised, inappropriate complement activation on self‐surfaces can have disastrous effects as seen in the kidney diseases atypical haemolytic uremic syndrome (aHUS) and C3 glomerulopathy. As FH constructs have been proposed to be used in treatment for these diseases, we studied the distribution of exogenous FH fragments in mice. Full‐length mFH, mFH1‐5 and mFH18‐20 fragments were radiolabelled, and their distribution was examined in WT, FH−/− and FH−/−C3−/− mice in vivo. Whole body scintigraphy revealed accumulation of radioactivity in the abdominal part of the mice, but also to the thyroid gland and urinary bladder. At organ level in WT mice, some full‐length FH accumulated in internal organs, but most of it remained in the circulation. Both of the mFH fragments accumulated in the kidneys and were excreted in urine. For mFH1‐5, urinary secretion is the likely cause for the accumulation. Concentration of mFH18‐20 to kidneys was slower, and at tissue level, mFH18‐20 was localized at the proximal tubuli in WT and FH−/−C3−/− mice. No C3‐independent binding to glomeruli was detected. In conclusion, these results show that glomerular glycosaminoglycans and sialic acids alone do not collect FH in kidneys. Deposition of C3 fragments is also needed, which implies that in aHUS, the problem is in simultaneous recognition of C3 fragments and glycosaminoglycans or sialic acids by FH, not just the inability of FH to recognize glomerular endothelium as such.
Yang Y, Denton H, Davies OR, et al., 2018, An Engineered Complement Factor H Construct for Treatment of C3 Glomerulopathy, JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY, Vol: 29, Pages: 1649-1661, ISSN: 1046-6673
Saja M, Cook HT, Ruseva M, et al., 2018, A triglyceride-rich lipoprotein environment exacerbates renal injury in the accelerated nephrotoxic nephritis model, Clinical and Experimental Immunology, Vol: 192, Pages: 337-347, ISSN: 1365-2249
Hyperlipidaemia accompanies chronic renal disease either as a consequence of the renal dysfunction or as part of generalized metabolic derangements. Under both situations, the lipid profile is characterized by accumulation of triglyceride‐rich lipoproteins (TGRLs). This lipid profile is recognized as a risk factor for cardiovascular complications. Whether it may pose a risk for renal injury as well remains unclear. A hyper‐TGRL state was generated in C57BL/6 mice using poloxamer‐407 (P‐407) and immune complex‐mediated renal injury was triggered using the accelerated nephrotoxic nephritis (ANTN) model. The hyper‐TGRL animals were hypersensitive to ANTN demonstrated by greater haematuria and glomerular cellularity. These changes were accompanied by increased glomerular accumulation of CD68+ macrophages. The hypersensitive response to ANTN was not seen in low‐density lipoprotein receptor knock‐out mice fed with a high fat diet, where triglyceride levels were lower but cholesterol levels comparable to those obtained using P‐407. These data indicate that a hyper‐TGRL state might be more detrimental to the kidneys than low‐density lipoprotein‐driven hypercholesterolaemia during immune complex‐mediated nephritis. We speculate that the hyper‐TGRL environment primes the kidney to exacerbated renal damage following an inflammatory insult with increased accumulation of macrophages that may play a key role in mediating the injurious effects.
Medjeral-Thomas NR, Troldborg A, Constantinou N, et al., 2018, Progressive IgA Nephropathy Is Associated With Low Circulating Mannan-Binding Lectin-Associated Serine Protease-3 (MASP-3) and Increased Glomerular Factor H-Related Protein-5 (FHR5) Deposition, KIDNEY INTERNATIONAL REPORTS, Vol: 3, Pages: 426-438, ISSN: 2468-0249
IntroductionIgA nephropathy (IgAN) is characterized by glomerular deposition of galactose-deficient IgA1 and complement proteins and leads to renal impairment. Complement deposition through the alternative and lectin activation pathways is associated with renal injury.MethodsTo elucidate the contribution of the lectin pathway to IgAN, we measured the 11 plasma lectin pathway components in a well-characterized cohort of patients with IgAN.ResultsM-ficolin, L-ficolin, mannan-binding lectin (MBL)–associated serine protease (MASP)-1 and MBL-associated protein (MAp) 19 were increased, whereas plasma MASP-3 levels were decreased in patients with IgAN compared with healthy controls. Progressive disease was associated with low plasma MASP-3 levels and increased glomerular staining for C3b/iC3b/C3c, C3d, C4d, C5b-9, and factor H–related protein 5 (FHR5). Glomerular FHR5 deposition positively correlated with glomerular C3b/iC3b/C3c, C3d, and C5b-9 deposition, but not with glomerular C4d. These observations, together with the finding that glomerular factor H (fH) deposition was reduced in progressive disease, are consistent with a role for fH deregulation by FHR5 in renal injury in IgAN.ConclusionOur data indicate that circulating MASP-3 levels could be used as a biomarker of disease severity in IgAN and that glomerular staining for FHR5 could both indicate alternative complement pathway activation and be a tissue marker of disease severity.
Cook HT, Pickering MC, 2017, Clusters not classifications: making sense of complement-mediated kidney injury, Journal of the American Society of Nephrology, Vol: 29, Pages: 9-12, ISSN: 1046-6673
Kane SJ, Farley TK, Gordon EO, et al., 2017, Complement regulatory protein factor H is a soluble prion receptor that potentiates peripheral prion pathogenesis, Journal of Immunology, Vol: 199, Pages: 3821-3827, ISSN: 1550-6606
Several complement proteins exacerbate prion disease, including C3, C1q, and CD21/35. These proteins of the complement cascade likely increase uptake, trafficking, and retention of prions in the lymphoreticular system, hallmark sites of early prion propagation. Complement regulatory protein factor H (fH) binds modified host proteins and lipids to prevent C3b deposition and, thus, autoimmune cell lysis. Previous reports show that fH binds various conformations of the cellular prion protein, leading us to question the role of fH in prion disease. In this article, we report that transgenic mice lacking Cfh alleles exhibit delayed peripheral prion accumulation, replication, and pathogenesis and onset of terminal disease in a gene-dose manner. We also report a biophysical interaction between purified fH and prion rods enriched from prion-diseased brain. fH also influences prion deposition in brains of infected mice. We conclude from these data and previous findings that the interplay between complement and prions likely involves a complex balance of prion sequestration and destruction via local tissue macrophages, prion trafficking by B and dendritic cells within the lymphoreticular system, intranodal prion replication by B and follicular dendritic cells, and potential prion strain selection by CD21/35 and fH. These findings reveal a novel role for complement-regulatory proteins in prion disease.
Medjeral-Thomas NR, Lomax-Browne HJ, Beckwith H, et al., 2017, Circulating complement factor H-related proteins 1 and 5 correlate with disease activity in IgA nephropathy, Kidney International, Vol: 92, Pages: 942-952, ISSN: 0085-2538
IgA nephropathy (IgAN) is a common cause of chronic kidney disease and end-stage renal failure, especially in young people. Due to a wide range of clinical outcomes and difficulty in predicting response to immunosuppression, we need to understand why and identify which patients with IgAN will develop progressive renal impairment. A deletion polymorphism affecting the genes encoding the complement factor H-related protein (FHR)-1 and FHR-3 is robustly associated with protection against IgAN. Some FHR proteins, including FHR-1 and FHR-5, antagonize the ability of complement factor H (fH), the major negative regulator of the complement alternative pathway, to inhibit complement activation on surfaces, a process termed fH deregulation. From a large cohort of patients, we demonstrated that plasma FHR-1 and the FHR-1/fH ratio were elevated in IgAN and associated with progressive disease. Plasma FHR-1 negatively correlated with eGFR but remained elevated in patients with IgAN with normal eGFR. Serum FHR5 was slightly elevated in IgAN but did not correlate with eGFR. Neither FHR5 levels nor the FHR-5/fH ratio was associated with progressive disease. However, higher serum FHR-5 levels were associated with a lack of response to immunosuppression, the presence of endocapillary hypercellularity, and histology scores of disease severity (the Oxford Classification MEST score). Thus, FHR-1 and FHR-5 have a role in IgAN disease progression.
Stratigou V, Doyle, Carlucci F, et al., 2017, Altered expression of signalling lymphocyte activation molecule (SLAM) receptors in T cells from lupus nephritis patients - a potential biomarker of disease activity., Rheumatology, Vol: 56, Pages: 1206-1216, ISSN: 1462-0332
Objectives. The aim was to investigate whether the signalling lymphocyte activation molecule (SLAM) signalling pathways contribute to LN and whether SLAM receptors could be valuable biomarkers of disease activity.Methods. Peripheral blood mononuclear cells from 30National Research Ethics Service SLE patients with biopsy-proven LN were analysed by flow cytometry. Clinical measures of disease activity were assessed. The expression of the SLAM family receptors on T-cell subpopulations [CD4, CD8 and double negative (DN) T cells] was measured and compared between lupus patients with active renal disease and those in remission.Results. The frequency of CD8 T cells expressing SLAMF3, SLAMF5 and SLAMF7 was significantly lower in LN patients who were in remission. In contrast, these subsets were similar in patients with active renal disease and in healthy individuals. Patients with active nephritis had an increased percentage of circulating monocytes, consistent with a potential role played by these cells in glomerular inflammation. Changes in the frequency of DN T cells positive for SLAMF2, SLAMF4 and SLAMF7 were observed in lupus patients irrespective of the disease activity. We detected alterations in the cellular expression of the SLAM family receptors, but these changes were less obvious and did not reveal any specific pattern. The percentage of DN T cells expressing SLAMF6 could predict the clinical response to B-cell depletion in patients with LN.Conclusion. Our study demonstrates altered expression of the SLAM family receptors in SLE T lymphocytes. This is consistent with the importance of the SLAM-associated pathways in lupus pathogenesis.
Calippe B, Augustin S, Beguier F, et al., 2017, Complement factor H inhibits CD47-mediated resolution of inflammation, IMMUNITY, Vol: 46, Pages: 261-272, ISSN: 1074-7613
Variants of the CFH gene, encoding complement factor H (CFH), show strong association with age-related macular degeneration (AMD), a major cause of blindness. Here, we used murine models of AMD to examine the contribution of CFH to disease etiology. Cfh deletion protected the mice from the pathogenic subretinal accumulation of mononuclear phagocytes (MP) that characterize AMD and showed accelerated resolution of inflammation. MP persistence arose secondary to binding of CFH to CD11b, which obstructed the homeostatic elimination of MPs from the subretinal space mediated by thrombospsondin-1 (TSP-1) activation of CD47. The AMD-associated CFH(H402) variant markedly increased this inhibitory effect on microglial cells, supporting a causal link to disease etiology. This mechanism is not restricted to the eye, as similar results were observed in a model of acute sterile peritonitis. Pharmacological activation of CD47 accelerated resolution of both subretinal and peritoneal inflammation, with implications for the treatment of chronic inflammatory disease.
Goodship THJ, Cook HT, Fakhouri F, et al., 2016, Atypical hemolytic uremic syndrome and C3 glomerulopathy: conclusions from a "Kidney Disease: Improving Global Outcomes" (KDIGO) Controversies Conference, Kidney International, Vol: 91, Pages: 539-551, ISSN: 0085-2538
In both atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) complement plays a primary role in disease pathogenesis. Herein we report the outcome of a 2015 Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference where key issues in the management of these 2 diseases were considered by a global panel of experts. Areas addressed included renal pathology, clinical phenotype and assessment, genetic drivers of disease, acquired drivers of disease, and treatment strategies. In order to help guide clinicians who are caring for such patients, recommendations for best treatment strategies were discussed at length, providing the evidence base underpinning current treatment options. Knowledge gaps were identified and a prioritized research agenda was proposed to resolve outstanding controversial issues.
IgA Nephropathy (IgAN) is the most common form of primary glomerulonephritis and an important cause of kidney failure. Characteristically, IgAN patients have increased serum levels of under-galactosylated IgA1 (gd-IgA1). We assessed the degree to which serum gd-IgA1 levels are genetically determined in healthy individuals. Serum IgA and gd-IgA1 level were determined by ELISA in a sample of 148 healthy female twins including 27 monozygotic and 47 dizygotic pairs. Using the classical twin model, the heritability of serum gd-IgA1 and IgA levels were 80% (95% CI: 66-89%) and 46% (95% CI: 15-69%) respectively. These data indicate that serum gd-IgA1 levels are highly heritable. Elucidating the genetic basis of this heritability will be important in understanding the pathogenesis of IgAN.
Mulloy B, Wu N, Gyapon-Quast F, et al., 2016, Abnormally high content of free glucosamine residues identified in a preparation of commercially available porcine intestinal heparan sulfate, Analytical Chemistry, Vol: 88, Pages: 6648-6652, ISSN: 1520-6882
Heparan sulfate (HS) polysaccharides are ubiquitous in animal tissues as components of proteoglycans, and they participate in many important biological processes. HS carbohydrate chains are complex and can contain rare structural components such as N-unsubstituted glucosamine (GlcN). Commercially available HS preparations have been invaluable in many types of research activities. In the course of preparing microarrays to include probes derived from HS oligosaccharides, we found an unusually high content of GlcN residue in a recently purchased batch of porcine intestinal mucosal HS. Composition and sequence analysis by mass spectrometry of the oligosaccharides obtained after heparin lyase III digestion of the polysaccharide indicated two and three GlcN in the tetrasaccharide and hexasaccharide fractions, respectively. 1H NMR of the intact polysaccharide showed that this unusual batch differed strikingly from other HS preparations obtained from bovine kidney and porcine intestine. The very high content of GlcN (30%) and low content of GlcNAc (4.2%) determined by disaccharide composition analysis indicated that N-deacetylation and/or N-desulfation may have taken place. HS is widely used by the scientific community to investigate HS structures and activities. Great care has to be taken in drawing conclusions from investigations of structural features of HS and specificities of HS interaction with proteins when commercial HS is used without further analysis. Pending the availability of a validated commercial HS reference preparation, our data may be useful to members of the scientific community who have used the present preparation in their studies.
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