142 results found
Nester C, Appel GB, Bomback AS, et al., 2022, Clinical Outcomes of Patients with C3G or IC-MPGN Treated with the Factor D Inhibitor Danicopan: Final Results from Two Phase 2 Studies., Am J Nephrol, Pages: 1-14
INTRODUCTION: C3 glomerulopathy (C3G) is an ultrarare, chronic and progressive nephropathy mediated by dysregulation of the alternative pathway of complement (AP), with poor prognosis and limited treatment options. Targeted inhibition of proximal AP through factor D (FD) blockade represents a rational treatment approach. We present two phase 2 proof-of-concept clinical studies of the orally active FD inhibitor danicopan in patients with C3G and immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) (NCT03369236 and NCT03459443). METHODS: A double-blind, placebo-controlled study in patients with C3G and a single-arm, open-label study in patients with C3G or IC-MPGN treated with danicopan are reported. The studies evaluated pharmacokinetic/pharmacodynamic (PK/PD), efficacy, and safety outcomes. The co-primary endpoints were change from baseline in composite biopsy score and the proportion of patients with a 30% reduction in proteinuria relative to baseline at 6 or 12 months. RESULTS: Optimal systemic concentrations of danicopan were not achieved for complete and sustained inhibition of AP, although there was evidence that blockade of FD reduced AP activity shortly after drug administration. Consequently, limited clinical response was observed in key efficacy endpoints. While stable disease or improvement from baseline was seen in some patients, response was not consistent. The data confirmed the favorable safety profile of danicopan. CONCLUSION: While demonstrating a favorable safety profile, danicopan resulted in incomplete and inadequately sustained inhibition of AP, probably due to limitations in its PK/PD profile in C3G, leading to lack of efficacy. Complete and sustained AP inhibition is required for a clinical response in patients with C3G.
Podos SD, Trachtman H, Appel GB, et al., 2022, Baseline Clinical Characteristics and Complement Biomarkers of Patients with C3 Glomerulopathy Enrolled in Two Phase 2 Studies Investigating the Factor D Inhibitor Danicopan., Am J Nephrol, Pages: 1-12
INTRODUCTION: C3 glomerulopathy (C3G) is a rare, progressive kidney disease resulting from dysregulation of the alternative pathway (AP) of complement. Biomarkers at baseline were investigated in patients with C3G who participated in two phase 2 studies with the factor D (FD) inhibitor, danicopan. METHODS: Patients with biopsy-confirmed C3G, proteinuria ≥500 mg/day, and estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2 were enrolled into two studies (NCT03369236 and NCT03459443). Biomarker analysis was performed for patients with C3G confirmed by central pathology laboratory re-evaluation. Complement and clinical biomarkers, biopsy composite score, and activity and chronicity indices were assessed at baseline and analyzed by pairwise Spearman correlation analysis. RESULTS: Twenty-nine patients were included in the analysis (median [interquartile range] age: 24.0 [10.0] years). Systemic complement AP activation was evident by reduced median concentrations of C3 and C5, elevated sC5b-9, and normal C4, relative to reference ranges. C3 showed strong pairwise correlations with C5 and sC5b-9 (r = 0.80 and -0.73, respectively; p < 0.0001). Baseline Ba and FD concentrations were inversely correlated with eGFR (r = -0.83 and -0.87, respectively; p < 0.0001). Urinary concentrations of sC5b-9 were correlated with both plasma sC5b-9 and proteinuria (r = 0.69 and r = 0.83, respectively; p < 0.0001). Biopsy activity indices correlated strongly with biomarkers of systemic AP activation, including C3 (r = -0.76, p < 0.0001), whereas chronicity indices aligned more closely with eGFR (r = -0.57, p = 0.0021). CONCLUSION: Associations among complement biomarkers, kidney function, and kidney histology may add to the current understanding of C3G and assist with the characterization of patients with this heterogenous disease.
Lomax-Browne HJ, Medjeral-Thomas NR, Barbour SJ, et al., 2022, Association of Histologic Parameters with Outcome in C3 Glomerulopathy and Idiopathic Immunoglobulin-Associated Membranoproliferative Glomerulonephritis, CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY, Vol: 17, Pages: 994-1007, ISSN: 1555-9041
Medjeral-Thomas N, Barbour S, Gisby J, et al., 2022, Histological predictors of outcome in C3 glomerulopathy and idiopathic immunoglobulin-associated membranoproliferative glomerulonephritis, Clinical Journal of the American Society of Nephrology, ISSN: 1555-9041
Background and objectivesC3 glomerulopathy and idiopathic immunoglobulin-associated membranoproliferative glomerulonephritis (Ig-MPGN) are kidney diseases characterised by abnormal glomerular complement C3 deposition. These conditions are heterogeneous in outcome, but approximately 50% of patients reach end stage kidney disease within 10 years. Design, setting, participants and measurementsTo improve identification of patients with poor prognosis we performed a detailed analysis of percutaneous kidney biopsies in a large cohort of patients. Using a validated histological scoring system, we analysed 156 native diagnostic kidney biopsies from a retrospective cohort of 123 patients with C3 glomerulopathy and 33 patients with Ig-MPGN. We used linear regression, survival analysis and Cox proportional hazards models to assess the relationship between histological and clinical parameters with outcome. ResultsFrequent biopsy features were mesangial expansion and hypercellularity, glomerular basement membrane (GBM) double contours and endocapillary hypercellularity. Multivariable analysis showed negative associations between estimated glomerular filtration rate (eGFR) and crescents, interstitial inflammation, and interstitial fibrosis and tubular atrophy (IFTA). Proteinuria positively associated with endocapillary hypercellularity and GBM double contours. Analysis of second native biopsies did not demonstrate associations between immunosuppression treatment and improvement in histology. Using a composite outcome, risk of progression to kidney failure associated with eGFR and proteinuria at time of biopsy, and cellular/fibrocellular crescents, segmental sclerosis and IFTA scores. ConclusionsOur detailed assessment of kidney biopsy data indicated that cellular/fibrocellular crescents and IFTA scores were significant determinants of deterioration in kidney function.
Marquez-Tirado B, Gutierrez-Tenorio J, Tortajada A, et al., 2022, Factor H-Related Protein 1 Drives Disease Susceptibility and Prognosis in C3 Glomerulopathy, JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY, Vol: 33, Pages: 1137-1153, ISSN: 1046-6673
Bomback AS, Appel GB, Gipson DS, et al., 2022, Improving Clinical Trials for Anticomplement Therapies in Complement-Mediated Glomerulopathies: Report of a Scientific orkshop Sponsored by the National Kidney Foundation, AMERICAN JOURNAL OF KIDNEY DISEASES, Vol: 79, Pages: 570-581, ISSN: 0272-6386
Ahmad A, Mandwie M, O'Sullivan KM, et al., 2022, Conversion of the liver into a biofactory for DNaseI using adeno-associated virus vector gene transfer reduces neutrophil extracellular traps in a model of Systemic Lupus Erythematosus., Hum Gene Ther
Adeno-associated virus (AAV) vectors are proving to be clinically transformative tools in the treatment of monogenic genetic disease. Rapid ongoing development of this technology promises to not only increase the number of monogenic disorders amenable to this approach, but also to bring diseases with complex multigenic and non-genetic aetiologies within therapeutic reach. Here we explore the broader paradigm of converting the liver into a biofactory for systemic output of therapeutic molecules using AAV-mediated delivery of DNaseI as an exemplar. DNaseI can clear neutrophil extracellular traps (NETs), which are nuclear-protein structures possessing anti-microbial action that are also involved in the pathophysiology of clinically troubling immune-mediated diseases. However, a translational challenge is short half-life of the enzyme in vivo (<5 hours). The current study demonstrates that AAV-mediated liver-targeted gene transfer stably induces serum DNaseI activity to >190-fold above physiological levels. In lupus-prone mice (NZBWF1) activity was maintained for longer than 6 months, the latest time point tested, and resulted in a clear functional effect with reduced renal presence of neutrophils, NETs, IgG and complement C3. However, treatment in this complex disease model did not extend life-span, improve serological endpoints or preserve renal function indicating there are elements of pathophysiology not accessible to DNaseI in the NZBWF1 model. We conclude that a translational solution to the challenge of short half-life of DNaseI is AAV-mediated gene delivery and that this may be efficacious in treating disease where NETs are a dominant pathological mechanism.
Gilmore A, Wilson H, Cairns T, et al., 2022, Immune gene expression and functional networks in distinct lupus nephritis classes, Lupus Science & Medicine, Vol: 9, ISSN: 2053-8790
Objective: To explore the utility of the NanoString platform in elucidating kidney immune transcripts for class III, IV and V lupus nephritis (LN) using a retrospective cohort of formalin-fixed paraffin-embedded (FFPE) kidney biopsy tissue.Methods: Immune gene transcript analysis was performed using the NanoString nCounter platform on RNA from LN (n=55), thin basement membrane disease (TBM, n=14) and membranous nephropathy (MN, n=9) FFPE kidney biopsy tissue. LN samples consisted of single class III (n=11), IV (n=23) and V (n=21) biopsies with no mixed lesions. Differential gene expression was performed with NanoString nSolver, with visualisations of volcano plots and heatmaps generated in R. Significant transcripts were interrogated to identify functional networks using STRING and Gene ontogeny terms. Results: In comparison to TBM, we identified 52 significantly differentially expressed genes common to all three LN classes. Pathway analysis showed enrichment for type I interferon (IFN) signalling, complement and MHC II pathways, with most showing the highest expression in class IV LN. Our class IV LN biopsies also showed significant upregulation of NF-κB signalling and immunological enrichment in comparison to class V LN biopsies. Transcripts from the type I IFN pathway distinguished class V LN from MN. Conclusion: Our whole kidney section transcriptomic analysis provided insights into the molecular profile of class III, IV and V LN. The data highlighted important pathways common to all three classes and pathways enriched in our class IV LN biopsies. The ability to reveal molecular pathways in LN using FFPE whole biopsy sections could have clinical utility in treatment selection for LN.
Kamala O, Malik TH, Hallam TM, et al., 2021, Homodimeric Minimal Factor H: In Vivo Tracking and Extended Dosing Studies in Factor H Deficient Mice, FRONTIERS IN IMMUNOLOGY, Vol: 12, ISSN: 1664-3224
Wong EKS, Marchbank KJ, Lomax-Browne H, et al., 2021, C3 Glomerulopathy and Related Disorders in Children: Etiology-Phenotype Correlation and Outcomes, CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY, Vol: 16, Pages: 1639-1651, ISSN: 1555-9041
Dixon BP, Fakhouri F, Pickering MC, et al., 2021, PHASE 3, RANDOMIZED, MULTICENTER STUDY TO EVALUATE THE EFFICACY AND SAFETY OF PEGCETACOPLAN IN TREATMENT OF C3G OR IC-MPGN, Publisher: SPRINGER, Pages: 3399-3400, ISSN: 0931-041X
Dotz V, Visconti A, Lomax-Browne HJ, et al., 2021, O- and N-glycosylation of serum immunoglobulin A is associated with IgA nephropathy and glomerular function., Journal of the American Society of Nephrology, Vol: 32, Pages: 1-12, ISSN: 1046-6673
BACKGROUND: IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and is a leading cause of renal failure. The disease mechanisms are not completely understood, but a higher abundance of galactose-deficient IgA is recognized to play a crucial role in IgAN pathogenesis. Although both types of human IgA (IgA1 and IgA2) have several N-glycans as post-translational modification, only IgA1 features extensive hinge-region O-glycosylation. IgA1 galactose deficiency on the O-glycans is commonly detected by a lectin-based method. To date, limited detail is known about IgA O- and N-glycosylation in IgAN. METHODS: To gain insights into the complex O- and N-glycosylation of serum IgA1 and IgA2 in IgAN, we used liquid chromatography-mass spectrometry (LC-MS) for the analysis of tryptic glycopeptides of serum IgA from 83 patients with IgAN and 244 age- and sex-matched healthy controls. RESULTS: Multiple structural features of N-glycosylation of IgA1 and IgA2 were associated with IgAN and glomerular function in our cross-sectional study. These features included differences in galactosylation, sialylation, bisection, fucosylation, and N-glycan complexity. Moreover, IgA1 O-glycan sialylation was associated with both the disease and glomerular function. Finally, glycopeptides were a better predictor of IgAN and glomerular function than galactose-deficient IgA1 levels measured by lectin-based ELISA. CONCLUSIONS: Our high-resolution data suggest that IgA O- and N-glycopeptides are promising targets for future investigations on the pathophysiology of IgAN and as potential noninvasive biomarkers for disease prediction and deteriorating kidney function.
Medjeral-Thomas NR, Cook HT, Pickering MC, 2021, Complement activation in IgA nephropathy, Springer Seminars in Immunopathology, Vol: 43, Pages: 679-690, ISSN: 1863-2297
IgA nephropathy pathogenesis is incompletely understood, and this limits the development of disease-specific biomarkers and effective therapies. Evidence of complement activity in IgA nephropathy is well established. However, a growing body of research indicates complement activity is an important contributor to IgA nephropathy pathology. In particular, multiple associations have been identified between complement alternative, lectin and terminal pathway proteins and IgA nephropathy severity. Recently, we have also gained insight into possible mechanisms that could link glomerular IgA deposition, complement activity, glomerular inflammation and disease severity. Ongoing clinical trials of therapeutic complement inhibitors will provide insight into the importance of complement activity to IgA nephropathy pathogenesis. Further research into mechanisms of complement activity is essential to improving our understanding and management of patients with IgA nephropathy.
Daugan MV, Revel M, Thouenon R, et al., 2021, Intracellular Factor H Drives Tumor Progression Independently of the Complement Cascade, CANCER IMMUNOLOGY RESEARCH, Vol: 9, Pages: 909-925, ISSN: 2326-6066
Gyapon-Quast F, Goicoechea de Jorge E, Malik T, et al., 2021, Defining the glycosaminoglycan interactions of complement factor H-related protein 5, Journal of Immunology, Vol: 207, Pages: 534-541, ISSN: 0022-1767
Complement activation is an important mediator of kidney injury in glomerulonephritis. Complement factor H (FH) and FH-related protein 5 (FHR-5) influence complement activation in C3 glomerulopathy and IgA nephropathy by differentially regulating glomerular complement. FH is a negative regulator of complement C3 activation. Conversely, FHR-5 in vitro promotes C3 activation either directly or by competing with FH for binding to complement C3b. The FH-C3b interaction is enhanced by surface glycosaminoglycans (GAGs) and the FH-GAG interaction is well-characterized. In contrast, the contributions of carbohydrates to the interaction of FHR-5 and C3b are unknown. Using plate-based and microarray technologies we demonstrate that FHR-5 interacts with sulfated GAGs and that this interaction is influenced by the pattern and degree of GAG sulfation. The FHR-5-GAG interaction that we identified has functional relevance as we could show that the ability of FHR-5 to prevent binding of FH to surface C3b is enhanced by surface kidney heparan sulfate. Our findings are important in understanding the molecular basis of the binding of FHR-5 to glomerular complement and the role of FHR-5 in complement-mediated glomerular disease.
Ahmad A, Mandwie M, Dreismann AK, et al., 2021, Adeno-associated virus vector gene delivery elevates Factor I levels and down-regulates the complement alternative pathway in vivo., Human Gene Therapy, Vol: 32, Pages: 1370-1381, ISSN: 1043-0342
The complement system is a key component of innate immunity but impaired regulation influences disease susceptibility, including age-related macular degeneration (AMD) and some kidney diseases. Whilst complete complement inhibition has been used successfully to treat acute kidney disease, key unresolved challenges include strategies to modulate rather than completely inhibit the system and to deliver therapy potentially over decades. Elevating concentrations of complement regulator factor I (CFI) restricts complement activation in vitro and this approach was extended in the current study to modulate complement activation in vivo. Sustained increases in CFI levels were achieved using an adeno-associated virus (AAV) vector to target the liver, inducing a 4- to 5-fold increase in circulating CFI levels. This led to decreased activity of the alternative pathway as demonstrated by a reduction in the rate of iC3b deposition and more rapid formation of C3 degradation products. In addition, vector application in a mouse model of systemic lupus erythematosus (NZBWF1), where tissue injury is in part complement dependent, resulted in reduced complement C3 and IgG renal deposition. Collectively, these data demonstrate that sustained elevation of CFI reduces complement activation in vivo providing proof-of-principle support for the therapeutic application of AAV gene delivery to modulate complement activation.
Medjeral-Thomas N, Troldborg A, Hansen A, et al., 2021, Protease inhibitor plasma concentrations associate with COVID-19 infection, Oxford Open Immunology, Vol: 2, ISSN: 2633-6960
Protease inhibitors influence a range of innate immunity and inflammatory pathways. We quantified plasma concentrations of key anti-inflammatory protease inhibitors in chronic haemodialysis patients with COVID-19. The samples were collected early in the disease course to determine whether plasma protease inhibitor levels associated with the presence and severity of COVID-19. We used antibody-based immunoassays to measure plasma concentrations of C1 esterase inhibitor (C1-INH), alpha2-macroglobulin (α2M), antithrombin, and inter-alpha-inhibitor heavy chain 4 (ITIH4) in 100 serial samples from 27 haemodialysis patients with COVID-19. ITIH4 was tested in two assays, one measuring intact ITIH4 and another also detecting any fragmented ITIH4 (total ITIH4). Control cohorts were 32 haemodialysis patients without COVID-19 and 32 healthy controls. We compared protease inhibitor concentration based on current and future COVID-19 severity and with CRP. Results were adjusted for repeated measures and multiple comparisons. Analysis of all available samples demonstrated lower plasma C1-INH and α2M and higher total ITIH4 in COVID-19 compared to dialysis controls. These differences were also seen in the first sample collected after COVID-19 diagnosis, a median of four days from diagnostic swab. Plasma ITIH4 levels were higher in severe than non-severe COVID-19. Serum CRP correlated positively with plasma levels of antithrombin, intact ITIH4, and total ITIH4. In conclusion, plasma protease inhibitor concentrations are altered in COVID-19.
Kerr H, Herbert AP, Makou E, et al., 2021, Murine factor H Co-produced in yeast with protein disulfide isomerase ameliorated C3 dysregulation in factor H-deficient mice, Frontiers in Immunology, Vol: 12, Pages: 1-17, ISSN: 1664-3224
Recombinant human factor H (hFH) has potential for treating diseases linked to aberrant complement regulation including C3 glomerulopathy (C3G) and dry age-related macular degeneration. Murine FH (mFH), produced in the same host, is useful for pre-clinical investigations in mouse models of disease. An abundance of FH in plasma suggests high doses, and hence microbial production, will be needed. Previously, Pichia pastoris produced useful but modest quantities of hFH. Herein, a similar strategy yielded miniscule quantities of mFH. Since FH has 40 disulfide bonds, we created a P. pastoris strain containing a methanol-inducible codon-modified gene for protein-disulfide isomerase (PDI) and transformed this with codon-modified DNA encoding mFH under the same promoter. What had been barely detectable yields of mFH became multiple 10s of mg/L. Our PDI-overexpressing strain also boosted hFH overproduction, by about tenfold. These enhancements exceeded PDI-related production gains reported for other proteins, all of which contain fewer disulfide-stabilized domains. We optimized fermentation conditions, purified recombinant mFH, enzymatically trimmed down its (non-human) N-glycans, characterised its functions in vitro and administered it to mice. In FH-knockout mice, our de-glycosylated recombinant mFH had a shorter half-life and induced more anti-mFH antibodies than mouse serum-derived, natively glycosylated, mFH. Even sequential daily injections of recombinant mFH failed to restore wild-type levels of FH and C3 in mouse plasma beyond 24 hours after the first injection. Nevertheless, mFH functionality appeared to persist in the glomerular basement membrane because C3-fragment deposition here, a hallmark of C3G, remained significantly reduced throughout and beyond the ten-day dosing regimen.
Medjeral-Thomas NR, Pickering MC, Cook HT, 2021, Complement and kidney disease, new insights., Curr Opin Nephrol Hypertens, Vol: 30, Pages: 310-316
PURPOSE OF REVIEW: In this review, we discuss recent studies showing the importance of the complement pathway in kidney disease. RECENT FINDINGS: Recent findings in C3 glomerulopathy (C3G) include: acute postinfectious glomerulonephritis is characterised by the presence of antifactor B antibodies; human leukocyte antigen type, but not rare complement gene variation, is associated with primary immunoglobulin-associated membranoproliferative GN and C3G. Immunohistochemistry in C3G shows that factor H related protein 5 (FHR5) is the most prevalent complement protein and correlates with kidney function. A multicentre study supported the use of mycophenolate mofetil (MMF) in C3G even after a propensity matching analysis. In immunoglobulin A nephropathy (IgAN) several studies have emphasised the importance of complement. Imbalances of circulating FH and FHR1 and FHR5, which interfere with the regulatory functions of FH, associate with IgAN. Immunohistochemistry has shown associations between glomerular FHR5 deposition and C3 activation; glomerular FHR5 associated with clinical markers of IgAN severity. Data also suggest the lectin complement pathway contributes to IgAN severity. We also discuss complement activation in thrombotic microangiopathy and other kidney diseases. SUMMARY: Complement activity can be detected in a wide range of kidney diseases and this provides pathogenic insight and potential for therapy with the ongoing development of several drugs directed at complement activation.
Medjeral-Thomas N, Troldborg A, Hansen A, et al., 2021, Plasma lectin pathway complement proteins in patients with COVID-19 and renal disease, Frontiers in Immunology, Vol: 12, ISSN: 1664-3224
We do not understand why non-white ethnicity and chronic kidney disease increase susceptibility to COVID-19. The lectin pathway of complement activation is a key contributor to innate immunity and inflammation. Concentrations of plasma lectin pathway proteins influence pathway activity and vary with ethnicity. We measured circulating lectin proteins in a multi-ethnic cohort of chronic kidney disease patients with and without COVID19 infection to determine if lectin pathway activation was contributing to COVID19 severity.We measured 11 lectin proteins in serial samples from a cohort of 33 patients with chronic kidney impairment and COVID19. Controls were single plasma samples from 32 patients on dialysis and 32 healthy individuals. We demonstrated multiple associations between recognition molecules and associated proteases of the lectin pathway and COVID-19, including COVID-19 severity. Some of these associations were unique to patients of Asian and White ethnicity. Our novel findings demonstrate that COVID19 infection alters the concentration of plasma lectin proteins and some of these changes were linked to ethnicity. This suggests a role for the lectin pathway in the host response to COVID-19 and suggest that variability within this pathway may contribute to ethnicity-associated differences in susceptibility to severe COVID-19.
Botto M, Buang N, Tapeng L, et al., 2021, Type I interferons affect the metabolic fitness of CD8+ T cells from patients with systemic lupus erythematosus, Nature Communications, Vol: 12, Pages: 1-15, ISSN: 2041-1723
The majority of patients with systemic lupus erythematosus (SLE) have high expression of type I IFN-stimulated genes. Mitochondrial abnormalities have also been reported, but the contribution of type I IFN exposure to these changes is unknown. Here, we show downregulation of mitochondria-derived genes and mitochondria-associated metabolic pathways in IFN-High patients from transcriptomic analysis of CD4+ and CD8+ T cells. CD8+ T cells from these patients have enlarged mitochondria and lower spare respiratory capacity associated with increased cell death upon rechallenge with TCR stimulation. These mitochondrial abnormalities can be phenocopied by exposing CD8+ T cells from healthy volunteers to type I IFN and TCR stimulation. Mechanistically these ‘SLE-like’ conditions increase CD8+ T cell NAD+ consumption resulting in impaired mitochondrial respiration and reduced cell viability, both of which can be rectified by NAD+ supplementation. Our data suggest that type I IFN exposure contributes to SLE pathogenesis by promoting CD8+ T cell death via metabolic rewiring.
Malik TH, Gitterman DP, Lavin DP, et al., 2021, Gain-of-function factor H–related 5 protein impairs glomerular complement regulation resulting in kidney damage, Proceedings of the National Academy of Sciences, Vol: 118, Pages: 1-9, ISSN: 0027-8424
Genetic variation within the factor H–related (FHR) genes is associated with the complement-mediated kidney disease, C3 glomerulopathy (C3G). There is no definitive treatment for C3G, and a significant proportion of patients develop end-stage renal disease. The prototypical example is CFHR5 nephropathy, through which an internal duplication within a single CFHR5 gene generates a mutant FHR5 protein (FHR5mut) that leads to accumulation of complement C3 within glomeruli. To elucidate how abnormal FHR proteins cause C3G, we modeled CFHR5 nephropathy in mice. Animals lacking the murine factor H (FH) and FHR proteins, but coexpressing human FH and FHR5mut (hFH-FHR5mut), developed glomerular C3 deposition, whereas mice coexpressing human FH with the normal FHR5 protein (hFH-FHR5) did not. Like in patients, the FHR5mut had a dominant gain-of-function effect, and when administered in hFH-FHR5 mice, it triggered C3 deposition. Importantly, adeno-associated virus vector-delivered homodimeric mini-FH, a molecule with superior surface C3 binding compared to FH, reduced glomerular C3 deposition in the presence of the FHR5mut. Our data demonstrate that FHR5mut causes C3G by disrupting the homeostatic regulation of complement within the kidney and is directly pathogenic in C3G. These results support the use of FH-derived molecules with enhanced C3 binding for treating C3G associated with abnormal FHR proteins. They also suggest that targeting FHR5 represents a way to treat complement-mediated kidney injury.
Gilmore AC, Zhang Y, Cook HT, et al., 2021, Complement activity is regulated in C3 glomerulopathy by IgG-factor H fusion proteins with and without properdin targeting domains, Kidney International, Vol: 99, Pages: 396-404, ISSN: 0085-2538
C3 glomerulopathy is characterized by accumulation of complement C3 within glomeruli. Causes include, but are not limited to, abnormalities in factor H, the major negative regulator of the complement alternative pathway. Factor H-deficient (Cfh-/-) mice develop C3 glomerulopathy together with a reduction in plasma C3 levels. Using this model, we assessed the efficacy of two fusion proteins containing the factor H alternative pathway regulatory domains (FH1-5) linked to either a non-targeting mouse immunoglobulin (IgG-FH1-5) or to an anti-mouse properdin antibody (Anti-P-FH1-5). Both proteins increased plasma C3 and reduced glomerular C3 deposition to an equivalent extent, suggesting that properdin-targeting was not required for FH1-5 to alter C3 activation in either plasma or glomeruli. Following IgG-FH1-5 administration, plasma C3 levels temporally correlated with changes in factor B levels whereas plasma C5 levels correlated with changes in plasma properdin levels. Notably, the increases in plasma C5 and properdin levels persisted for longer than the increases in C3 and factor B. In Cfh-/- mice IgG-FH1-5 reduced kidney injury during accelerated serum nephrotoxic nephritis. Thus, our data demonstrate that IgG-FH1-5 restored circulating alternative pathway activity and reduced glomerular C3 deposition in Cfh-/- mice and that plasma properdin levels are a sensitive marker of C5 convertase activity in factor H deficiency. The immunoglobulin conjugated FH1-5 protein, through its comparatively long plasma half-life, may be a potential therapy for C3 glomerulopathy.
Rovin BH, Caster DJ, Cattran DC, et al., 2021, Management and treatment of glomerular diseases (part 2): Conclusions from a kidney disease: Improving global outcomes (kdigo) controversies conference, Nephrology (Saint-Petersburg), Vol: 25, Pages: 96-119, ISSN: 1561-6274
In November 2017, the Kidney Disease: Improving Global Outcomes (KDIGO) initiative brought a diverse panel of experts in glomerular diseases together to discuss the 2012 KDIGO glomerulonephritis guideline in the context of new developments and insights that had occurred over the years since its publication. During this KDIGO Controversies Conference on Glomerular Diseases, the group examined data on disease pathogenesis, biomarkers, and treatments to identify areas of consensus and areas of controversy. This report summarizes the discussions on primary podocytopathies, lupus nephritis, anti-neutrophil cytoplasmic antibody-associated nephritis, complement mediated kidney diseases, and monoclonal gammopathies of renal significance.
Prendecki M, Clarke C, McKinnon T, et al., 2021, SARS-CoV-2 antibody point-of-care testing in dialysis and kidney transplant patients with COVID-19., Kidney Medicine, Vol: 3, Pages: 54-59.e1, ISSN: 2590-0595
Rationale & Objective: A number of serologic tests for immunoglobulin G (IgG) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are now commercially available, including multiple lateral flow immunoassays (LFIAs), which have the advantage of being inexpensive and easy to use, without the reliance on laboratory facilities. However, data on the development of humoral immunity to SARS-CoV-2 in patients with kidney disease is limited, and the utility of an LFIA to test for antibodies in these patients has not been assessed. Study Design: Observational study. Setting & Participants: 60 patients (40 hemodialysis and 20 kidney transplant recipients) with SARS-CoV-2 infection confirmed by viral reverse transcriptase-polymerase chain reaction (RT-PCR) testing and 88 historic negative-control samples (collected before September 2019). Test: A commercially available LFIA to test for SARS-CoV-2 IgG in patients with infection confirmed by viral RT-PCR testing. Outcomes: Sensitivity and specificity of the LFIA to detect SARS-CoV-2 IgG in dialysis patients and transplant recipients. Results: 56/58 (96.6%) patients (38/39 hemodialysis and 18/19 transplant recipients) tested positive for SARS-CoV-2 IgG. 5/7 (71.4%) patients who were negative on preliminary testing had detectable IgG when retested more than 21 days postdiagnosis. Median times to first and second tests after diagnosis were 17 (interquartile range, 15-20) and 35 (interquartile range, 30-39) days, respectively. Calculation of test characteristics gave sensitivity of 96.6% (95% CI, 88.3%-99.4%) and specificity of 97.7% (95% CI, 92.0-99.6%). Limitations: Possible exposure to other beta-coronaviruses that may cross-react with the antigen used in the LFIA cannot be excluded. Conclusions: Symptomatic dialysis patients and transplant recipients commonly develop an immune response against SARS-CoV-2 infection that can be detected using an LFIA. Used diligently, an LFIA could be used to help scre
Gisby J, Clarke C, Medjeral-Thomas N, et al., 2020, Longitudinal proteomic profiling of high-risk patients with COVID-19 reveals markers of severity and predictors of fatal disease, eLife, Vol: 10, Pages: 1-30, ISSN: 2050-084X
End-stage kidney disease (ESKD) patients are at high risk of severe COVID-19. We performed dense serial blood sampling in hospitalised and non-hospitalised ESKD patients with COVID-19 (n=256 samples from 55 patients) and used Olink immunoassays to measure 436 circulating proteins. Comparison to 51 non-infected ESKD patients revealed 221 proteins differentially expressed in COVID-19, of which 69.7% replicated in an independent cohort of 46 COVID-19 patients. 203 proteins were associated with clinical severity scores, including IL6, markers of monocyte recruitment (e.g. CCL2, CCL7), neutrophil activation (e.g proteinase-3) and epithelial injury (e.g. KRT19). Random Forests machine learning identified predictors of current or future severity such as KRT19, PARP1, PADI2, CCL7, and IL1RL1 (ST2). Survival analysis with joint models revealed 69 predictors of death including IL22RA1, CCL28, and the neutrophil-derived chemotaxin AZU1 (Azurocidin). Finally, longitudinal modelling with linear mixed models uncovered 32 proteins that display different temporal profiles in severe versus non-severe disease, including integrins and adhesion molecules. Our findings point to aberrant innate immune activation and leucocyte-endothelial interactions as central to the pathology of severe COVID-19. The data from this unique cohort of high-risk individuals provide a valuable resource for identifying drug targets in COVID-19.
Prendecki M, Clarke C, Medjeral-Thomas N, et al., 2020, Temporal changes in complement activation in haemodialysis patients with COVID-19 as a predictor of disease progression, Clinical Kidney Journal, Vol: 13, Pages: 889-896, ISSN: 2048-8505
Background: Complement activation may play a pathogenic role in patients with severe coronavirus disease 2019 (COVID-19) by contributing to tissue inflammation and microvascular thrombosis. Methods: Serial samples were collected from patients receiving maintenance haemodialysis (HD). Thirty-nine patients had confirmed COVID-19 and 10 patients had no evidence of COVID-19. Plasma C5a and C3a levels were measured using enzyme-linked immunosorbent assay. Results: We identified elevated levels of plasma C3a and C5a in HD patients with severe COVID-19 compared with controls. Serial sampling identified that C5a levels were elevated prior to clinical deterioration in patients who developed severe disease. C3a more closely mirrored both clinical and biochemical disease severity. Conclusions: Our findings suggest that activation of complement plays a role in the pathogenesis of COVID-19, leading to endothelial injury and lung damage. C5a may be an earlier biomarker of disease severity than conventional parameters such as C-reactive protein and this warrants further investigation in dedicated biomarker studies. Our data support the testing of complement inhibition as a therapeutic strategy for patients with severe COVID-19.
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: 1969-1975, 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, Pages: 1-13, ISSN: 1664-3224
Intravascular hemolysis of any cause can induce acute kidney injury (AKI). Hemolysis-derived product heme activates the innate immune complement system and contributes to renal damage. Therefore, we explored the role of the master complement regulator Factor H (FH) in the kidney's resistance to hemolysis-mediated AKI. Acute systemic hemolysis was induced in mice lacking liver expression of FH (hepatoFH−/−, ~20% residual FH) and in WT controls, by phenylhydrazine injection. The impaired complement regulation in hepatoFH−/− mice resulted in a delayed but aggravated phenotype of hemolysis-related kidney injuries. Plasma urea as well as markers for tubular (NGAL, Kim-1) and vascular aggression peaked at day 1 in WT mice and normalized at day 2, while they increased more in hepatoFH−/− compared to the WT and still persisted at day 4. These were accompanied by exacerbated tubular dilatation and the appearance of tubular casts in the kidneys of hemolytic hepatoFH−/− mice. Complement activation in hemolytic mice occurred in the circulation and C3b/iC3b was deposited in glomeruli in both strains. Both genotypes presented with positive staining of FH in the glomeruli, but hepatoFH−/− mice had reduced staining in the tubular compartment. Despite the clear phenotype of tubular injury, no complement activation was detected in the tubulointerstitium of the phenylhydrazin-injected mice irrespective of the genotype. Nevertheless, phenylhydrazin triggered overexpression of C5aR1 in tubules, predominantly in hepatoFH−/− mice. Moreover, C5b-9 was deposited only in the glomeruli of the hemolytic hepatoFH−/− mice. Therefore, we hypothesize that C5a, generated in the glomeruli, could be filtered into the tubulointerstitium to activate C5aR1 expressed by tubular cells injured by hemolysis-derived products and will aggravate the tissue injury. Plasma-derived FH is critical for the tubular protection, since
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