Sethi, Sanjeev

Abstract C3 glomerulopathy (C3G) is a clinicopathologic entity characterized by glomerular inflammation with dominant staining for C3 on immunofluorescence microscopy. Electron microscopy is used to determine the location and type of deposits, which further divides C3G into C3 glomerulonephritis (C3GN) and dense deposit disease (DDD) based on ultrastructural findings. Both entities are progressive, with about 60% of patients progressing to end-stage kidney disease (ESKD) within 10 years. Recurrence after kidney transplantation occurs in up to 60% of C3G cases. New knowledge about the pathophysiology—different patterns of injury, histopathological scoring, apolipoprotein E staining, dysregulation of the alternative complement pathway (including both autoantibodies to and mutations in complement regulatory factors), as well as proteomic analyses—has allowed a better understanding of different pathophysiological profiles and clinical presentations, enabling individualized treatment. The role of nephroprotection is well established in C3G, as it is for other glomerular diseases. Non-specific treatment with corticosteroids and immunosuppression is associated with a variable response rate. However, more recently, results from clinical trials with proximal complement inhibitors have shown significant improvement in proteinuria and attenuation of the decline in estimated glomerular filtration rate (eGFR). Based on the results of these trials involving drugs that specifically target the upstream complement pathways, including the alternative pathway, new treatment options have recently become available for patients with C3G.

ABSTRACT C3 glomerulonephritis (C3GN) is a rare kidney disease driven by dysregulation of the alternative complement pathway. We report two challenging cases of patients with C3GN in whom various immunosuppressant therapies have failed to achieve complete remission, prompting treatment with eculizumab, an anti-C5 humanized monoclonal antibody that inhibits the terminal complement pathway. Although transient improvement in kidney function was observed, both patients eventually experienced worsening renal parameters, with increasing proteinuria and hematuria, culminating in progression to end-stage kidney disease. Repeated kidney biopsies following eculizumab therapy demonstrated persistent, granular mesangial and capillary wall C3 (3+) staining on immunofluorescence studies, indicating ongoing complement activation upstream of the C5 blockade and the perpetuation of C3 deposits in the glomeruli. These cases underscore the limited efficacy of terminal complement inhibition in halting disease progression in C3GN.

ABSTRACT Background The impact of sex in the clinical presentation and outcomes of patients with anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) with glomerulonephritis (AAV-GN) has not been studied, particularly in patients with severe kidney involvement at presentation (eGFR < 15 ml/min/1.73 m2). Methods A retrospective cohort study on MPO- or PR3-ANCA positive patients with AAV (MPA or GPA) and eGFR<15 ml/min/1.73 m2 or end-stage kidney disease (ESKD) at presentation. Clinical presentation and renal outcomes were analyzed according to sex. Results We analyzed 166 patients with biopsy-proven active AAV-GN and eGFR < 15 ml/min/1.7 3m2 at the time of diagnosis: 78 (47%) were females and 88 (53%) were males. Hypertension was more frequently present in males (85.2% vs 70.5%, P = .022). Median serum creatinine (SCr) was higher in males when compared with females [5.2 (IQR 4.2–7.4) vs 3.6 (IQR 2.8–5.1) mg/dl, P < .001]. Males started dialysis within 4 weeks more frequently than female (p = .003) although the median percentage of crescents was similar between groups (35.7% in males versus 36.4% in females, P = .0873). However, the rate of dialysis initiation or progression to ESKD in the first 12 months was not different between males (15, 62.5%) versus females (29, 61.7%) at 12 months. By multivariable logistic regression, factors related with dialysis initiation within the first 4 weeks in our cohort were SCr, alveolar hemorrhage, and PR3-ANCA adjusted for sex. Conclusion In our cohort, male patients presented with higher serum creatinine (SCr), and dialysis was started within the first 4 weeks more frequently (53.4% vs 30.7%). There were no differences in outcomes of kidney recovery, overall dialysis rates, and progression to ESKD within 12 months in patients with AAV-GN and eGFR < 15 ml/min/1.73 m2 between groups.

ABSTRACT Background Membranous nephropathy (MN) is a leading cause of nephrotic syndrome (NS). Since the identification of anti–phospholipase A2 receptor (anti-PLA2R) antibodies in 2009, the use of laser microdissection and tandem mass spectrometry (LMD/MS) has allowed the discovery of several target antigens in MN. Methods In this retrospective cohort study, adult patients evaluated at the Division of Nephrology at Brotzu Hospital (Cagliari, Italy) with biopsy-proven MN and a negative serological test for anti-PLA2R antibody underwent LMD/MS, performed at the Department of Laboratory Medicine and Pathology of Mayo Clinic (Rochester, MN, USA). Results Twenty-four cases of biopsy-proven MN were available for antigen detection by LMD/MS studies. High total spectral counts of PLA2R were detected in 12 out of 24 (50%) cases. In addition, high spectral counts of THSD7A and NELL1 were detected in two cases each, and EXT1/EXT2 and NCAM1 in one case each. Five putative antigens have been detected: SULF1, PGLYRP, HYAL1, THBS and SEZ6L2. Conclusions Our study highlights at least two interesting considerations. First, the determination of PLA2R on renal tissue in the diagnosis of PLA2R-associated MN is emphasized since 50% of our cases were falsely diagnosed with PLA2R-negative MN based on the serum anti-PLA2R antibodies determination. Second, our study shows six patients with MN likely associated with putative antigens, two of them showing new antigens never described before in literature (HYAL1 and THBS1). This high prevalence of putative antigens in our cohort is not easily explainable and paves the way for evaluating specific factors in the Sardinian population that could explain this evidence.

Abstract Objective ANCA-negative granulomatosis with polyangiitis (GPA) remains a diagnosis of exclusion. Clinical differences between patients with ANCA-negative vs ANCA-positive GPA have not been analysed in sizable case-control studies, and the effects of ANCA-seroconversion from negative to positive are not well documented. Methods A single-centre, sex and age matched case-control study evaluated ANCA-negative vs ANCA-positive GPA from 1 January 1996 to 31 December 2015. Patients who experienced seroconversion were the subject of a case-crossover study. Clinical data and outcomes were retrieved from electronic medical records. Results ANCA-negative GPA was identified in 110 patients; 65% were female; median age was 55 (IQR 39–65) years at time of diagnosis. Disease severity was milder in ANCA-negative GPA (BVAS/WG = 2 vs 6, P < 0.001). Mucous membranous/eye manifestations were more frequent in ANCA-negative GPA. General symptoms, pulmonary and renal involvement were more frequent in ANCA-positive GPA. Patients with ANCA-positive GPA relapsed more over 60 months (21.8% vs. 9.1%, P = 0.009) compared with ANCA-negative GPA and had shorter time to event (P = 0.043). Patients with general manifestations, BMI > 30kg/m2 and necrotizing granulomatous inflammation were more likely to relapse. The 16 patients who seroconverted into ANCA-positive during follow-up had higher mean BVAS/WG at time of diagnosis (P < 0.001) and increased incidence of relapses (P = 0.004) after seroconversion. Necrotizing granulomatous inflammation on biopsy in ANCA-negative GPA patients was identified as a risk factor for subsequent seroconversion to ANCA-positivity. Conclusion Patients with ANCA-negative GPA have milder disease and a lower frequency of relapse than those with ANCA-positive GPA. ANCA appearance portended higher disease severity and an increased frequency of relapses.

ABSTRACT Membranous nephropathy (MN) is characterized by deposition of immune complexes leading to thickening of glomerular basement membranes. Over time, the understanding of MN has evolved, with the identification of specific autoantibodies against novel podocyte antigens and the unraveling of intricate pathogenic pathways. Although the anti-CD20 monoclonal antibody rituximab is favored as part of the initial therapy in MN, a subgroup of MN patients may be resistant to rituximab necessitating the use of alternative agents such as cytotoxic therapies. In addition, newer agents such as novel anti-CD20 monoclonal antibodies, therapies targeting the CD38-positive plasma cells and anti-complement therapy are being studied in patients who are resistant to traditional treatment strategies. This manuscript furnishes a review of the novel developments in the pathophysiology of MN including the identification of target antigens and current treatment standards for MN, concentrating on evidenced-based interventions designed to attain remission and to prevent disease progression.

ABSTRACTThe risk of progression to end-stage kidney disease (ESKD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and glomerulonephritis (AAV-GN) remains high. At 5 years of follow-up, 14–25% of patients will evolve to ESKD, suggesting that kidney survival is not optimized in patients with AAV. The addition of plasma exchange (PLEX) to standard remission induction has been the standard of care, particularly in patients with severe renal disease. However, there is still some debate regarding which patients benefit from PLEX.A recently published meta-analysis concluded that the addition of PLEX to standard remission induction in AAV probably reduced the risk of ESKD at 12 months and that PLEX was associated with an estimated absolute risk reduction for ESKD at 12 months of 16.0% for those at high risk or with a serum creatinine >5.7 mg/dl (high certainty of important effects). These findings were interpreted as supportive of offering PLEX to patients with AAV and a high risk of progression to ESKD or requiring dialysis and are making their way into societies recommendations.However, the results of the analysis can be debated. We provide an overview on the meta-analysis as an attempt to guide the audience through how the data were generated, to comment on our interpretation of the results and to explain why we feel uncertainty remains. In addition, we would like to provide insights in two questions that we believe are very relevant to consider when addressing the role of PLEX: the role of kidney biopsy findings in the decision making of whom might benefit from PLEX and the impact of novel treatments (i.e. complement factor 5a inhibitors) in avoiding progression to ESKD at 12 months. The treatment of patients with severe AAV-GN is complex and further studies that include only patients at high risk of progression to ESKD are needed.

Background and objectives C3 glomerulopathy and idiopathic Ig-associated membranoproliferative GN are kidney diseases characterized by abnormal glomerular complement C3 deposition. These conditions are heterogeneous in outcome, but approximately 50% of patients develop kidney failure within 10 years. Design, setting, participants, & measurements To 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 histologic scoring system, we analyzed 156 native diagnostic kidney biopsies from a retrospective cohort of 123 patients with C3 glomerulopathy and 33 patients with Ig-associated membranoproliferative GN. We used linear regression, survival analysis, and Cox proportional hazards models to assess the relationship between histologic and clinical parameters with outcome. Results Frequent biopsy features were mesangial expansion and hypercellularity, glomerular basement membrane double contours, and endocapillary hypercellularity. Multivariable analysis showed negative associations between eGFR and crescents, interstitial inflammation, and interstitial fibrosis/tubular atrophy. Proteinuria positively associated with endocapillary hypercellularity and glomerular basement membrane 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 the time of biopsy, cellular/fibrocellular crescents, segmental sclerosis, and interstitial fibrosis/tubular atrophy scores. Conclusions Our detailed assessment of kidney biopsy data indicated that cellular/fibrocellular crescents and interstitial fibrosis/tubular atrophy scores were significant determinants of deterioration in kidney function.

Background Membranous nephropathy (MN) is a common cause of proteinuria in patients receiving a hematopoietic stem cell transplant (HSCT). The target antigen in HSCT-associated MN is unknown. Methods We performed laser microdissection and tandem mass spectrometry (MS/MS) of glomeruli from 250 patients with PLA2R-negative MN to detect novel antigens in MN. This was followed by immunohistochemical (IHC)/immunofluorescence (IF) microscopy studies to localize the novel antigen. Western blot analyses using serum and IgG eluted from frozen biopsy specimen to detect binding of IgG to new 'antigen'. Results MS/MS detected a novel protein, protocadherin FAT1 (FAT1), in nine patients with PLA2R-negative MN. In all nine patients, MN developed after allogeneic HSCT (Mayo Clinic discovery cohort). Next, we performed MS/MS in five patients known to have allogeneic HSCT-associated MN (Cedar Sinai validation cohort). FAT1 was detected in all five patients by MS/MS. The total spectral counts for FAT1 ranged from 8 to 39 (mean±SD, 20.9±10.1). All 14 patients were negative for known antigens of MN, including PLA2R, THSD7A, NELL1, PCDH7, NCAM1, SEMA3B, and HTRA1. Kidney biopsy specimens showed IgG (2 to 3+) with mild C3 (0 to 1+) along the GBM; IgG4 was the dominant IgG subclass. IHC after protease digestion and confocal IF confirmed granular FAT1 deposits along the GBM. Lastly, Western blot analyses detected anti-FAT1 IgG and IgG4 in the eluate obtained from pooled frozen kidney biopsy tissue and in the serum of those with FAT1-asssociated MN, but not from those with PLA2R-associated MN. Conclusions FAT1-associated MN appears to be a unique type of MN associated with HSCT. FAT1-associated MN represents a majority of MN associated with HSCT.

Background and objectives Kidney biopsy is the current gold standard to diagnose membranous nephropathy. Approximately 70%–80% of patients with primary membranous nephropathy have circulating anti-phospholipase A2 receptor antibodies. We previously demonstrated that in proteinuric patients with preserved eGFR and absence of associated conditions ( e.g., autoimmunity, malignancy, infection, drugs, and paraproteinemia), a positive anti-phospholipase A2 receptor antibody test by ELISA and immunofluorescence assay confirms the diagnosis of membranous nephropathy noninvasively. These data have not been externally validated. Design, setting, participants, & measurements The clinical and pathologic characteristics of patients with a positive anti-phospholipase A2 receptor antibody test at the Mayo Clinic, the University Hospital Vall D’Hebron (Barcelona), and the Columbia University Medical Center (New York) were retrospectively reviewed. Biopsy findings and presence or absence of a potential associated condition were assessed. Results From a total of 276 patients with positive anti-phospholipase A2 receptor serology, previously reported patients ( n =33), kidney transplant recipients ( n =9), pediatric patients ( n =2), and patients without kidney biopsy ( n =69) were excluded. Among the 163 remaining patients, associated conditions were identified in 47 patients, and 15 patients had diabetes mellitus. All 101 patients of the final cohort had a primary diagnosis of membranous nephropathy on kidney biopsy. In the 79 patients with eGFR≥60 ml/min per 1.73 m 2 , none of the biopsy findings altered diagnosis or management. Among the 22 patients with decreased eGFR, additional findings included superimposed acute interstitial nephritis ( n =1). Conclusions In patients with preserved eGFR and absence of associated conditions or diabetes, a positive anti-phospholipase A2 receptor test by either ELISA >20 RU/ml or a positive immunofluorescence assay confirms the diagnosis of membranous nephropathy, precluding the requirement for a kidney biopsy.