Pathogenesis of Pulmonary Manifestations in ANCA-Associated Vasculitis and Goodpasture Syndrome.

Pulmonary manifestations of vasculitis are associated with significant morbidity and mortality in affected individuals. They result from a complex interplay between immune dysregulation, which leads to vascular inflammation and tissue damage. This review explored the underlying pathogenesis of pulmonary involvement in vasculitis, encompassing various forms such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and anti-GBM disease. Mechanisms involving ANCA and anti-GBM autoantibodies, neutrophil activation, and neutrophil extracellular trap (NETs) formation are discussed, along with the role of the complement system in inducing pulmonary injury. Furthermore, the impact of genetic predisposition and environmental factors on disease susceptibility and severity was considered, and the current treatment options were presented. Understanding the mechanisms involved in the pathogenesis of pulmonary vasculitis is crucial for developing targeted therapies and improving clinical outcomes in affected individuals.

Crescentic glomerulonephritis due to linear IgA anti-glomerular basement membrane disease: report of a rare case.

Anti-glomerular basement membrane (GBM) disease is a rare and severe vasculitis that affects the glomerular and pulmonary capillaries and has an incidence of less than 2 cases per million individuals per year. Anti-GBM disease is mediated by autoantibodies against the α3 chain of type IV collagen. In the majority of cases, the autoantibodies are of the immunoglobulin G (IgG) class, with rare cases being mediated by immunoglobulin M (IgM) or immunoglobulin A (IgA); there are less than 15 IgA-mediated cases reported in the literature worldwide. The classic form of this disease manifests with rapidly progressive glomerulonephritis (RPGN), with or without pulmonary hemorrhage, and the diagnosis consists of identifying high titers of autoantibodies in the serum and/or deposited in the tissues. IgA antibodies are not identified in routine immunoassay tests, and renal biopsy with immunofluorescence is essential for diagnosis. We present a case of RPGN due to anti-GBM disease with linear IgA deposition, whose diagnosis was made exclusively by renal biopsy and with an unfavorable prognosis.

Atypical anti-glomerular basement membrane disease with membranous hyperplasia: diagnostic challenges and treatment variability.

This case report presents a detailed analysis of a 31-year-old male patient who presented with a complex array of clinical symptoms, including proteinuria, hematuria, edema, and kidney insufficiency. Despite undergoing multiple tests, the results for anti-glomerular basement membrane antibodies yielded negative findings. Subsequently, kidney biopsy pathology revealed a distinct diagnosis of atypical anti-glomerular basement membrane (anti-GBM) disease with membrane hyperplasia. Treatment was initiated with a comprehensive approach involving high doses of corticosteroids therapy and cyclophosphamide (CTX). However, contrary to expectations, the patient's kidney function exhibited rapid deterioration following this therapeutic regimen. The culmination of these complications necessitated a pivotal transition to maintenance hemodialysis. This case underscores the intricate challenges associated with diagnosing and managing rare and atypical presentations of kidney disorders. The negative anti-GBM antibody results and subsequent identification of atypical anti-GBM nephropathy highlight the need for tailored diagnostic strategies to discern subtle nuances within complex clinical scenarios. Additionally, the unexpected response to the treatment regimen emphasizes the potential variability in individual patient responses, underlining the necessity for vigilant monitoring and adaptable treatment strategies. This case report contributes to the evolving understanding of atypical kidney pathologies and the complexities involved in their management.

Anti-GBM disease in pregnancy.

We present the case of a pregnant woman in her 20s who presented in her second trimester with severe pulmonary haemorrhage and dialysis-dependent acute kidney failure due to antiglomerular basement membrane (GBM) disease. Responding to therapy, she recovered kidney function and delivered a baby. During her pregnancy, she developed cytomegalovirus viraemia, gestational diabetes and pre-eclampsia. Here, we report the first combined use of cyclophosphamide, rituximab and intensified plasma exchange in anti-GBM disease in pregnancy, allowing minimal exposure to cytotoxic medication, resulting in live birth and dialysis independence.

Coexistence of anti-glomerular basement membrane disease and IgA nephropathy: an illustrative case and comprehensive literature review.

Anti-glomerular basement membrane (GBM) disease is a rare autoimmune condition characterized by the presence of positive anti-GBM autoantibodies, linear deposition of immunoglobulin G (IgG) along the GBM and severe kidney injury. In a limited number of cases, the association of anti-GBM disease with other glomerulonephritis has been reported. Herein, we present the case of a 66-year-old female patient with progressive worsen kidney function and decreased urine output. A renal biopsy revealed crescent glomerulonephritis with lineal IgG deposition along the GBM and mesangial IgA deposition, which supported the diagnosis of concurrent anti-GBM disease and IgA nephropathy (IgAN). In an extensive literature review, we identified a total of thirty-nine patients were reported anti-GBM disease combined with IgAN. The clinical characteristics of these patients demonstrate that the anti-GBM disease combined with IgAN tends to be milder with a more indolent course and a better prognosis than the classic anti-GBM disease, and its potential pathogenesis deserves to be further explored.

Clinical phenotype of AAV, anti-GBM disease and double-positive patients after SARS-CoV-2 vaccination.

The number of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV), anti-glomerular basement membrane (GBM) disease and double-positive patients (DPPs) following the coronavirus disease 2019 (COVID-19) vaccine reported in the literature is increasing, we reviewed the reported cases of AAV, anti-GBM disease and DPPs subsequent to COVID-19 vaccination, and compared the disparities in DPPs who received the COVID-19 vaccination and those who did not. We did not observe any differences in clinical phenotype of AAV, anti-GBM disease and DPPs before and after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination.

Epidemiology, clinical features, risk factors, and outcomes in anti-glomerular basement membrane disease: A systematic review and meta-analysis.

Anti-glomerular basement membrane (GBM) disease is a small-vessel vasculitis that represents the most aggressive form of autoimmune glomerulonephritis. The study aimed to investigate the prevalence, clinical characteristics, risk factors, and outcomes of anti-GBM disease through a systematic review and meta-analysis involving 47 studies with 2830 patients. The overall incidence of anti-GBM disease ranged from 0.60 to 1.79 per million population per annum. In rapidly progressive glomerulonephritis and crescentic glomerulonephritis, the pooled incidence rates were 8.0% and 12.8%, respectively. The pooled prevalence rates of anti-GBM antibodies, antineutrophil cytoplasmic antibodies (ANCA), and lung hemorrhage were 88.8%, 27.4%, and 32.6%, respectively. Patients with combined ANCA positivity demonstrated a prognosis comparable to those patients with only anti-GBM antibodies, though with differing clinical features. The pooled one-year patient and kidney survival rates were 76.2% and 30.2%, respectively. Kidney function on diagnosis and normal glomeruli percentage were identified as strong prognostic factors. This study represents the first comprehensive meta-analysis on anti-GBM disease, providing insights into its management. However, caution is warranted in interpreting some results due to the observational nature of the included studies and high heterogeneity.

Atypical Anti-Glomerular Basement Membrane Nephritis: A Case Series From the French Nephropathology Group.

RATIONALE & OBJECTIVE: Atypical anti-glomerular basement membrane (GBM) nephritis is characterized by a bright linear immunoglobulin staining along the GBM by immunofluorescence without a diffuse crescentic glomerulonephritis nor serum anti-GBM antibodies by conventional enzyme-linked immunosorbent assay (ELISA). We characterized a series of patients with atypical anti-GBM disease. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: Patients identified by the French Nephropathology Group as having atypical anti-GBM nephritis between 2003 and 2022. FINDINGS: Among 38 potential cases, 25 were included, of whom 14 (56%) were female and 23 (92%) had hematuria. The median serum creatinine at diagnosis was 150 (IQR, 102-203) µmol/L and median urine protein-creatinine ratio (UPCR) was 2.4 (IQR, 1.3-5.2) g/g. Nine patients (36%) had endocapillary proliferative glomerulonephritis (GN), 4 (16%) had mesangial proliferative GN, 4 (16%) had membranoproliferative GN, 2 (8%) had pure and focal crescentic GN, 1 (4%) had focal segmental glomerulosclerosis, and 5 had glomeruli that were unremarkable on histopathology. Nine patients (36%) had crescents, involving a median of 9% of glomeruli. Bright linear staining for IgG was seen in 22 cases (88%) and for IgA in 3 cases (12%). The 9 patients (38%) who had a monotypic staining pattern tended to be older with less proteinuria and rarely had crescents. Kidney survival rate at 1 year was 83% and did not appear to be associated with the light chain restriction. LIMITATIONS: Retrospective case series with a limited number of biopsies including electron microscopy. CONCLUSIONS: Compared with typical anti-GBM disease, atypical anti-GBM nephritis frequently presents with an endocapillary or mesangial proliferative glomerulonephritis pattern and appears to have a slower disease progression. Further studies are needed to fully characterize its pathophysiology and associated clinical outcomes. PLAIN-LANGUAGE SUMMARY: Atypical anti-glomerular basement membrane (GBM) nephritis is characterized histologically by bright linear immunoglobulin staining along the GBM without diffuse crescentic glomerulonephritis or circulating anti-GBM antibodies. We report a case series of 25 atypical cases of anti-GBM nephritis in collaboration with the French Nephropathology Group. Compared with typical anti-GBM disease, we observed a slower disease progression. Patients frequently presented with heavy proteinuria and commonly had evidence of endocapillary or mesangial proliferative glomerulonephritis. About half of the patients displayed a monotypic immune staining pattern; they tended to be older, with less proteinuria, and commonly without glomerular crescents in biopsy specimens. No concomitant circulating monoclonal gammopathy was detected. Further studies are needed to fully characterize its pathophysiology and associated clinical outcomes.

Goodpasture syndrome: a rare case presenting with recurrent haemoptysis.

Goodpasture syndrome is a rare autoimmune disease which affects young adults with a male preponderance and can be triggered at any point in life with a classical clinical triad of rapidly progressive glomerulonephritis, diffuse pulmonary haemorrhage and circulating anti-glomerular basement membrane antibody (anti-GBM antibody). Here we are presenting a case of a young man with hypertension in his early 20s who presented with fatigue, recurrent haemoptysis, breathlessness and decreased urine output without features of infection. He was diagnosed at an early stage of the disease with the help of clinical, serological and radiological findings. An early diagnosis with effective treatment using plasma exchange, intravenous high-dose methylprednisolone, and cyclophosphamide showed a rapid improvement in the patient's condition with an immediate decrease in anti-GBM titres and proteinuria.

Short-chain fatty acids ameliorate experimental anti-glomerular basement membrane disease.

BACKGROUND: Short-chain fatty acids (SCFAs), as the link between gut microbiota and the immune system, had been reported to be protective in many autoimmune diseases by the modulation of T cell differentiation. The pathogenic role of autoreactive Th1 and Th17 cells and the protective role of Treg cells in the pathogenesis of anti-GBM disease have been fully demonstrated. Thus, the present study aimed to investigate the therapeutic effects of SCFAs in a rat model of anti-GBM disease. MATERIALS AND METHODS: Experimental anti-GBM disease was constructed by immunizing Wistar Kyoto rats with a nephrogenic T cell epitope α3127-148, and intervened by sodium acetate, sodium propionate, or sodium butyrate, 150 mM in the drinking water from day 0 to 42. Kidney injury was accessed by the biochemical analyzer, immunofluorescence, and immunohistochemistry. Antibody response was detected by ELISA. T cell clustering and proliferation were detected by flow cytometry. Human kidney 2 (HK2) cells were stimulated in vitro and cytokines were assessed by quantitative real-time PCR. RESULTS: Treatment with sodium acetate, sodium propionate, or sodium butyrate ameliorated the severity of kidney impairment in rats with anti-GBM glomerulonephritis. In the sodium butyrate-treated rats, the urinary protein, serum creatinine, and blood urea nitrogen levels were significantly lower; the percentage of crescent formation in glomeruli was significantly reduced; and the kidneys showed reduced IgG deposition, complement activation, T cell, and macrophage infiltration as well as the level of circulating antibodies against anti-α3(IV)NC1. The treatment of sodium butyrate reduced the α3127-148-specific T cell activation and increased the Treg cells differentiation and the intestinal beneficial bacteria flora. It also alleviated the damage of HK2 cells treated with inflammatory factors and complement. CONCLUSION: Treatment with SCFAs, especially butyrate, alleviated anti-GBM nephritis in rat model, indicating its potential therapeutic effects in clinical usage.

The protease inhibitor E64d might attenuate the development of experimental anti-glomerular basement membrane disease through regulating the activation of Th1 cells.

BACKGROUND: Cathepsins have been recently identified as a regulator in the activation of Th1 and Th17 cells, which play an important role in the pathogenesis of anti-glomerular basement membrane (GBM) disease. Whether cathepsins contribute to the development of anti-GBM disease through regulating the activation of CD4+ T cell is still unclear. METHODS: Rats with experimental anti-GBM disease was established by immunization with the nephritogenic T cell epitope α3127-148. E64d, a cysteine cathepsin inhibitor, was administered in vitro and vivo to evaluate the effect of cathepsins on regulating the activation of antigen specific T cells and the development of anti-GBM disease. RESULTS: In rats with experimental anti-GBM diseases, E64d treatment not only reduced the levels of proteinuria, serum creatinine and anti-GBM antibody, but also ameliorated the kidney injury with less glomerular IgG deposition, a lower percentage of crescents and less infiltration of CD4+ T cells, CD8+ T cells and macrophages, as well as a lower percentage of splenic Th1 cells. In vitro, E64d treatment could significantly reduce the production of IFN-γ in the supernatant which might be produced by the activation of Th1 cells after being recalled with the autoantigen α3127-148. We also found the CD4+ T cells of rats with anti-GBM disease had an increased expression of cathepsin L (Cts-L), and the percentage of CD4+ T cells with extracellular expression of Cts-L was obviously higher, indicating it as a potential key regulator. CONCLUSIONS: E64d might attenuate the development of anti-GBM disease by participating in the activation of Th1 cells, indicating it as a potential drug for anti-GBM disease in the future.

Clinical characteristics of anti-GBM disease with thrombotic microangiopathy: a case report and literature review.

The coexistence of anti-glomerular basement membrane (anti-GBM) disease with thrombotic microangiopathy (TMA) is rarely encountered, and the clinical characteristics of this phenomenon are not well known.A 76-year-old Japanese woman with a history of idiopathic pulmonary disease was diagnosed with anti-GBM disease due to rapidly progressive glomerulonephritis and a positive anti-GBM antibody test result. We treated the patient with hemodialysis, glucocorticoids, and plasmapheresis. During treatment, the patient suddenly became comatose. TMA was then diagnosed because of thrombocytopenia and microangiopathic hemolytic anemia. The activity of a disintegrin-like and metalloproteinase with thrombospondin type 1 motif 13 (ADAMTS-13) was retained at 48%. Although we continued the treatment, the patient died of respiratory failure. An autopsy revealed the cause of respiratory failure to be an acute exacerbation of interstitial pneumonia. The clinical findings of the renal specimen indicated anti-GBM disease; however, there were no lesions suggestive of TMA. A genetic test did not reveal an apparent genetic mutation of the atypical hemolytic uremic syndrome.We conducted a literature review of past case reports of anti-GBM disease with TMA. The following clinical characteristics were obtained. First, 75% of the cases were reported in Asia. Second, TMA tended to appear during the treatment course for anti-GBM disease and usually resolved within 12 weeks. Third, ADAMTS-13 activity was retained above 10% in 90% of the cases. Fourth, central nervous system manifestations occurred in more than half of the patients. Fifth, the renal outcome was very poor. Further studies are required to understand the pathophysiology of this phenomenon.

An Unusual Case of Anti-Glomerular Basement Membrane Disease and Phospholipase A2 Receptor-Associated Membranous Nephropathy After Exposure to Hydrocarbons.

We present a rare case of a patient with toluene exposure manifesting as anti-glomerular basement membrane (GBM) disease on a background of phospholipase A2 receptor (PLA2R)-associated membranous nephropathy. A 23-year-old man presented to the emergency department with hypertension, headache, hemoptysis, anemia, acute kidney injury, glomerular hematuria, and proteinuria. He endorsed repeated exposure to toluene-containing products while repairing dirt bikes. Serologies were positive for anti-GBM antibodies. Kidney biopsy showed crescentic glomerulonephritis with linear immunoglobulin G and granular PLA2R staining by immunofluorescence. He was initially treated with high-dose steroids, plasmapheresis, and hemodialysis for pulmonary-renal syndrome followed by oral cyclophosphamide and prednisone, which were discontinued after 3 months when follow-up biopsies confirmed little chance for renal recovery. He remained on dialysis 1 year later. This case exhibits a unique presentation of anti-GBM syndrome and underlying membranous nephropathy following repeated hydrocarbon exposure. Inhaled toxins promote recurrent localized inflammation, unmasking previously hidden epitopes. Early diagnosis and appropriate use of immunosuppressive and extracorporeal therapies are necessary to prevent morbidity and to improve survival in this rare condition.

The Immunobiological Agents for Treatment of Antiglomerular Basement Membrane Disease.

Combination therapy with glucocorticoids, cyclophosphamide, and plasmapheresis is recommended as the standard treatment for anti-glomerular basement membrane (anti-GBM) disease, but the prognosis of this disease remains poor. Several immunobiological agents have been administered or are expected to be useful for anti-GBM disease in light of refractory disease or the standard treatments' tolerability. Many data regarding the use of biologic agents for anti-GBM disease have accumulated, verifying the effectiveness and potential of biologic agents as a new treatment option for anti-GBM disease. Tumor necrosis factor (TNF) inhibitors were shown to be useful in animal studies, but these agents have no clinical use and were even shown to induce anti-GBM disease in several cases. Although the efficacy of the TNF-receptor antagonist has been observed in animal models, there are no published case reports of its clinical use. There are also no published reports of animal or clinical studies of anti-B-cell-activating factor, which is a member of the TNF family of agents. Anti-interleukin (IL)-6 antibodies have been demonstrated to have no effect on or to exacerbate nephritis in animal models. Anti-C5 inhibitor was observed to be useful in a few anti-GBM disease cases. Among the several immunobiological agents, only rituximab has been demonstrated to be useful in refractory or poor-tolerance patients or small uncontrolled studies. Rituximab is usually used in combination with steroids and plasma exchange and is used primarily as an alternative to cyclophosphamide, but there is insufficient evidence regarding the efficacy of rituximab for anti-GBM disease, and thus, randomized controlled studies are required.

Antiglomerular basement membrane antibody type rapidly progressive glomerulonephritis with seizures: Two cases and literature review.

BACKGROUND: Rapidly progressive glomerulonephritis (RPGN) is clinically manifestations as a rapidly progressive renal failure and pathologically as crescentic and necrotizing lesions with infiltration of inflammatory cells in the glomeruli. Uremic encephalopathy (UE) usually develops in patients who are suffering from acute or chronic renal failure. OBJECTIVE: The purpose of this article is to provide reference for clinical diagnosis and treatment of renal disease complicated with seizures. Patients Two cases of anti-glomerular basement membrane type rapidly progressive glomerulonephritis complicated with seizures were reported. MATERIALS & METHODS: In case 1, a 40-year-old woman was hospitalized for the treatment of nausea, anorexia, and fever. On admission, she presented with elevated serum inflammatory indicators, moderate anemia, and advanced acute kidney injury requiring hemodialysis. Her anti-glomerular basement membrane (GBM) antibody in serum and renal tissues was found to be extremely high. She was finally diagnosed with anti-GBM disease. She was treated with a combination of corticosteroid pulse therapy, oral cyclophosphamide and prednisolone, and plasma exchange, while continued to require maintenance hemodialysis for end-stage kidney disease. During treatment, she suddenly suffered blindness, seizure, and consciousness disturbance. She was diagnosed as posterior reversible leukoencephalopathy syndrome by magnetic resonance imaging (MRI). The posterior reversible leukoencephalopathy syndrome subsided quickly after control of her hypertension and reinforcement of immunosuppressive treatment. In case 2, the patient also developed epileptic symptoms on the basis of GBM disease, and was given treatment similar to that of Case 1, so that the epileptic symptoms were controlled. RESULT: Reversible posterior leukoencephalopathy syndrome, especially when accompanied by cerebral hemorrhage, may lead to irreversible and lethal neurological abnormalities, and nephrologists should, therefore, be aware of the potential risk of reversible posterior leukoencephalopathy syndrome in patients with anti-GBM disease. We can discuss the current two cases in the light of the previous literature.