From membranoproliferative glomerulonephritis to a final diagnosis: Hypocomplementemic urticarial vasculitis syndrome

Membranoproliferative glomerulonephritis describes a glomerular-injury pattern common to a heterogeneous group of diseases. Evaluation based on clinical and laboratory presentation and immunofluorescence staining on kidney biopsy allows identification of underlying pathophysiological processes and may facilitate proper diagnosis and treatment. Hypocomplementemic urticarial vasculitis syndrome is a rare autoimmune disease of multi-organ involvement. The diagnosis is based on well-defined clinical and laboratory criteria. The pathophysiology is not completely understood but the presence of anti-C1q antibody seems to be involved. Renal involvement occurs in up to 50% of cases. It can be heterogeneous and can be indistinguishable from lupus nephritis. Serological findings and skin involvement distinguish these two entities. We report the case of a 40-year-old female who presented with urticarial skin lesions, hypocomplementemia and nephrotic syndrome. Kidney biopsy showed membranoproliferative glomerulonephritis with full house immune complex deposits. The diagnosis of hypocomplementemic urticarial vasculitis syndrome was made and the patient was successfully treated with prednisolone and mycophenolate mofetil.

Thrombotic microangiopathy and smoldering multiple myeloma after kidney transplant in a patient with MCP mutation

The most frequent cause of atypical hemolytic uremic syndrome (aHUS) is defective regulation of complement activation because of genetic anomalies. We present the case of 53-year-old man with a kidney transplant and stabilized kidney function (creatinine 2.5 mg/dL; proteinuria 0.4 g/24 h) with mycophenolate/tacrolimus/prednisone who was diagnosed of Thrombotic Microangiopathy (TMA). This diagnosis was associated with creatinine and proteinuria rise (3 mg/dL; 2.4 g/24 h) and a new monoclonal IgA/lambda component. Renal biopsy showed membranoproliferative glomerulonephritis; a pathogenic variant in the Membrane cofactor protein (MCP) gene with a polymorphism ggaac, typically associated to secondary aHUS, was identified. We suspected that immunoglobulin could be acting as a trigger for TMA in a genetically susceptible patient, so “clone-directed” therapy with bortezomib and dexamethasone was initiated.

KM55 in the evaluation of IgA containing glomerular diseases

Introduction: Mucosal derived galactose deficient IgA is central to the pathogenesis of primary IgA nephropathy. Recent reports suggest similar pathogenesis in Henoch Schonlein purpura and secondary IgA nephropathy. Its role in other IgA containing glomerular diseases is still under investigation. It can be detected in glomeruli with the recently described antibody, KM55. We aimed to evaluate the role of KM55 by immunostaining a wide spectrum of IgA containing glomerular diseases. Methods: After standardization and co localization in a case of IgA nephropathy, a spectrum of 60 cases including IgA nephropathy, Henoch Schonlein purpura, chronic liver disease related IgA nephropathy, other secondary IgA Nephropathy, IgA dominant/co dominant membranoproliferative glomerulonephritis and lupus nephritis were subjected to immunofluorescence with KM55. KM55 was used to resolve diagnostic dilemma in cases of IgA deposition with confounding histology. Results: The group of primary IgA Nephropathy (17 cases), Henoch Schonlein purpura (4 cases) and secondary IgA nephropathy (19 cases) including chronic liver disease showed 2 -3+ granular staining with KM55 suggesting mucosal derived IgA. In contrast, cases of IgA dominant/co dominant membranoproliferative glomerulonephritis (8 cases) and lupus nephritis (12 cases) were negative for KM55, suggesting systemic derivation of IgA. In cases of IgA deposition with confounding histology such as membranoproliferative or diffuse endocapillary proliferative pattern, KM55 helped to resolve the diagnosis. Discussion/Conclusion: This cross-sectional study concludes that KM55 is useful in the evaluation of IgA containing glomerular diseases from a pathogenetic perspective, and is a practical tool in resolving differential diagnosis in cases with overlapping histopathologic features.

Chronic hepatitis B virus (HBV) infection presenting as crescentic membranoproliferative glomerulonephritis: A distinctly rare occurrence

Hepatitis B virus (HBV) is a highly prevalent infection worldwide. It primarily infects liver and presents with features of chronic liver disease. Rarely, it presents with extra-hepatic manifestations. Kidney involvement in HBV infection is not uncommon. However, presentation with rapidly progressive glomerulonephritis is distinctly rare. A 40-year-old man with undiscovered HBV infection presented with fever-triggered body swelling for one month. Serum creatinine was 2.3 mg/dl on admission, which increased during hospitalization to 4.5 mg/dl. Renal biopsy demonstrated crescentic membranoproliferative glomerulonephritis, immune complex-mediated. Clinical, laboratory and imaging studies revealed mild chronic liver damage. Complete renal, hepatic and virological remission was achieved with steroids, plasmapheresis and antiviral therapy. This case emphasizes on early diagnosis and institution of multimodal therapy for better outcomes.

Membranoproliferative glomerulonephritis: no longer the same disease and may need very different treatment

Membranoproliferative glomerulonephritis (MPGN) is a pattern of glomerular injury that may be primary or secondary to infections, autoimmune diseases and haematological disorders. Primary C3G and IC-MPGN are rare and the prognosis is unfavourable. Based on immunofluorescence findings, MPGN has been classified into complement-mediated C3 glomerulopathy (C3G), and immune complex-mediated MPGN (IC-MPGN). However, this classification leaves a number of issues unresolved. The finding of genetic and acquired complement abnormalities in both C3G and IC-MPGN indicates that they represent a heterogeneous spectrum rather than distinct diseases. An unsupervised hierarchical clustering in a cohort of patients with primary C3G and IC-MPGN identified 4 distinct pathogenetic patterns, characterised by specific histologic and clinical features and genetic and acquired complement abnormalities. These results provide the groundwork for a more accurate diagnosis and the development of targeted therapies. The drugs that are currently used, such as corticosteroids and immunosuppressants, are frequently ineffective in primary C3G and IC-MPGN. Eculizumab, an anti-C5 monoclonal antibody, has been used occasionally in single cases or small series. However, only a few patients have achieved remission. This heterogeneous response could be related to the extent of terminal complement activation, which may vary substantially from patient to patient. Several drugs that target the complement system at different levels are under investigation for C3G and IC-MPGN. However, clinical trials to test new therapeutics will be challenging and heavily influenced by the heterogeneity of these diseases. This creates the need to characterise each patient to match the specific complement abnormality with the type of intervention.

Demographic, clinical characteristics and treatment outcomes of immune-complex membranoproliferative glomerulonephritis and C3 glomerulonephritis in Japan: A retrospective analysis of data from the Japan Renal Biopsy Registry

The reclassification of membranoproliferative glomerulonephritis (MPGN) into immune-complex MPGN (IC-MPGN) and C3 glomerulopathy (C3G) based on immunofluorescence findings in kidney biopsies has provided insights into these two distinct diseases. C3G is further classified into dense deposit disease and C3 glomerulonephritis (C3GN) based on electron micrographic findings. Although these diseases have poor outcomes, limited Japanese literature confined to small, single-center cohorts exist on these diseases. We retrospectively analyzed 81 patients with MPGN type I and III from 15 hospitals in the Japan Renal Biopsy Registry to compare demographic, clinical characteristics and treatment outcomes of patients with IC-MPGN to those with C3GN. Of the 81 patients reviewed by immunofluorescence findings in kidney biopsies, 67 patients had IC-MPGN and 14 patients had C3GN. Age at diagnosis and systolic and diastolic pressure were higher and proteinuria and impaired renal function were significantly more prevalent in patients with IC-MPGN than those with C3GN. About 80% of the patients in both groups were treated with immunosuppressive therapy. At last follow-up (median 4.8 years), complete remission rate of proteinuria was significantly higher in patients with C3GN (64.3%) than in those with IC-MPGN (29.9%; P = 0.015). The renal survival rate was lower in patients with IC-MPGN when compared to C3GN (73.1% vs. 100%; log-rank, P = 0.031). Systolic blood pressure and renal function at baseline were independent predictors of progression to end-stage kidney disease. The overall prognosis of patients with C3GN is more favorable than for patients with IC-MPGN.

FHR-5 Serum Levels and CFHR5 Genetic Variations in Patients With Immune Complex-Mediated Membranoproliferative Glomerulonephritis and C3-Glomerulopathy

BackgroundFactor H-related protein 5 (FHR-5) is a member of the complement Factor H protein family. Due to the homology to Factor H, the main complement regulator of the alternative pathway, it may also be implicated in the pathomechanism of kidney diseases where Factor H and alternative pathway dysregulation play a role. Here, we report the first observational study on CFHR5 variations along with serum FHR-5 levels in immune complex-mediated membranoproliferative glomerulonephritis (IC-MPGN) and C3 glomerulopathy (C3G) patients together with the clinical, genetic, complement, and follow-up data.MethodsA total of 120 patients with a histologically proven diagnosis of IC-MPGN/C3G were enrolled in the study. FHR-5 serum levels were measured in ELISA, the CFHR5 gene was analyzed by Sanger sequencing, and selected variants were studied as recombinant proteins in ELISA and surface plasmon resonance (SPR).ResultsEight exonic CFHR5 variations in 14 patients (12.6%) were observed. Serum FHR-5 levels were lower in patients compared to controls. Low serum FHR-5 concentration at presentation associated with better renal survival during the follow-up period; furthermore, it showed clear association with signs of complement overactivation and clinically meaningful clusters.ConclusionsOur observations raise the possibility that the FHR-5 protein plays a fine-tuning role in the pathogenesis of IC-MPGN/C3G.