Anti-glomerular Basement Membrane Glomerulonephritis: A Study in Real Life

Anti-Glomerular Basement Membrane Disease: Recent Updates

Anti-glomerular basement membrane disease is a small-vessel vasculitis involving the kidneys (∼90%) and the lungs (∼60%). Antibodies against the glomerular basement membrane are directly pathogenic in anti-glomerular basement membrane disease; however, recent research has highlighted the critical role of T cells. Novel autoantigens within the glomerular basement membrane are also now recognized. Atypical forms of the disease are reported along with preceding triggers, such as immune checkpoint inhibitors, immunomodulatory drugs, and vaccines. Kidney outcomes in anti-glomerular basement membrane disease remain poor despite significant improvement in patient survival in the last 2 to 3 decades. Treatment typically relies on combined plasmapheresis with intensive immunosuppression. Dialysis dependency at presentation is a dominant predictor of kidney outcome. Histologically, a low (<10%) percentage of normal glomeruli, 100% crescents, together with dialysis dependency at presentation, is associated with poor kidney outcomes. In such cases, an individualized approach weighing the risks and benefits of treatment is recommended. There is a need for better ways to stop the toxic inflammatory activity associated with this disease. In this narrative review, we discuss recent updates on the pathogenesis and management of anti-glomerular basement membrane disease relevant to patients of all ages.

Systemic vasculitis involving the kidney: the nephropathologist's point of view

Kidneys are often targets of systemic vasculitis (SVs), being affected in many different forms and representing a possible sentinel of an underlying multi-organ condition. Renal biopsy still remains the gold standard for the identification, characterization and classification of these diseases, solving complex differential diagnosis thanks to the combined application of light microscopy (LM), immunofluorescence (IF) and electron microscopy (EM). Due to the progressively increasing complexity of renal vasculitis classification systems (e.g. pauci-immune vs immune complex related forms), a clinico-pathological approach is mandatory and adequate technical and interpretative expertise in nephropathology is required to ensure the best standard of care for our patients. In this complex background, the present review aims at summarising the current knowledge and challenges in the world of renal vasculitis, unveiling the potential role of the introduction of digital pathology in this setting, from the creation of hub-spoke networks to the future application of artificial intelligence (AI) tools to aid in the diagnostic and scoring/classification process.

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.

Epidemiology and clinical characteristics of biopsy-confirmed adult-onset IgA vasculitis in southern Sweden

OBJECTIVE

Immunoglobulin A vasculitis (IgAV) is the most prevalent primary childhood vasculitis in Sweden, but is considerably rarer in adults. This study aims to describe the epidemiology, clinical characteristics and renal outcome of adult-onset IgAV in Skåne, Sweden.

METHODS

The study area consisted of Skåne, the southernmost region of Sweden, with a population ≥18 years of 990 464 on 31 December 2010. Adult patients assigned the International Classification of Diseases-10 code for IgAV (D69.0) from 2000 through 2019 were retrospectively identified in a population-based database. Medical records were reviewed to validate the diagnosis of IgAV and extract data. Only patients with clinical manifestations of IgAV and biopsy-confirmed disease were included. The annual incidence and point prevalence of biopsy-confirmed IgAV were estimated.

RESULTS

Fifty-nine patients (19 women) were classified as having adult-onset IgAV. The incidence was 3 per 1 000 000 and was higher among men than women (4 vs 2/1 000 000, p=0.004). Ninety-seven per cent of patients presented with non-thrombocytopenic purpura, 78% with renal involvement, 59% with arthritis/arthralgia and 39% with gastrointestinal symptoms. Fifteen per cent developed chronic kidney disease stage ≥G3 a and one patient progressed to end-stage kidney disease during follow-up.

CONCLUSION

Adult-onset IgAV is rare in southern Sweden with the incidence higher in men than in women. IgAV frequently affects the kidneys and leads to chronic kidney disease in adults, although the long-term renal outcome appears favourable compared with other small-vessel vasculitides affecting the kidneys.

Age- and time-dependent increases in incident anti-glomerular basement membrane disease: a nationwide cohort study

Background

Epidemiologic assessments of anti-glomerular basement membrane (GBM) disease have been challenging due to its rare occurrence. We examined changes in the incidence and outcomes from 1998 to 2018 using nationwide healthcare registries.

Methods

All patients with incident anti-GBM disease were identified using the International Classification of Diseases, 10th Revision code DM31.0A. Controls were matched 4:1 on birthyear and sex using exposure density sampling. Log link regression adjusted for time, age and sex was applied to model survival.

Results

We identified 97 patients with incident anti-GBM disease, corresponding to an incidence of 0.91 cases/million/year [standard deviation (SD) 0.6]. The incidence increased over time [1998-2004: 0.50 (SD 0.2), 2005-2011: 0.80 (SD 0.4), 2012-2018: 1.4 (SD 0.5); P = .02] and with age [0.76 (SD 0.4), 1.5 (SD 1.04) and 4.9 (SD 2.6) for patients <45, 45-75 and >75 years]. The median age was 56 years (interquartile range 46) and 51.6% were female. Dialysis was required in 58.4%, 61.9% and 62.9% of patients at day 30, 180 and 360, respectively. The 1-year kidney survival probability was 0.38 (SD 0.05) and exhibited time-dependent changes [1998-2004: 0.47 (SD 0.13), 2005-2011: 0.16 (SD 0.07), 2012-2018: 0.46 (SD 0.07); P = .035]. The 5-year mortality was 26.8% and mortality remained stable over time (P = .228). The risk of death was greater than that of the matched background population {absolute risk ratio [ARR] 5.27 [confidence interval (CI) 2.45-11.3], P < .001}, however, it was comparable to that of patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) requiring renal dialysis at presentation [ARR 0.82 (CI 0.48-1.41), P = .50].

Conclusion

The incidence of anti-GBM disease increased over time, possibly related to temporal demographic changes. Mortality remained high and was comparable with an age- and sex-matched cohort of dialysis-dependent AAV patients.

Using imlifidase to elucidate the characteristics and importance of anti-GBM antibodies produced after start of treatment

BACKGROUND

Autoantibodies are common in glomerulonephritis, but the clinical benefit of rapid elimination has not been determined, even in anti-glomerular basement membrane (GBM) disease. Even less is known about the importance of autoantibody characteristics, including epitope specificity and immunoglobulin G (IgG) subclass distribution. We aimed to address this by characterizing the autoantibody profile in anti-GBM patients: we utilized samples from the GOOD-IDES-01 (treating GOODpasture's disease with Imunoglobulin G Degrading Enzyme of Streptococcus pyogenous) (ClinicalTrials.gov identifier: NCT03157037) trial , where imlifidase, which cleaves all IgG in vivo within hours, was given to 15 anti-GBM patients.

METHODS

In the GOOD-IDES-01 trial, plasmapheresis was (re)started if anti-GBM antibodies rebounded. Serum samples were collected prospectively for 6 months and analyzed for anti-GBM epitope specificity using recombinant constructs of the EA and EB epitopes, IgG subclass using monoclonal antibodies, and anti-neutrophil cytoplasmic antibodies (ANCA). The results were correlated with clinical data.

RESULTS

Patients with a rebound (n = 10) tended to have lower eGFR at 6 months (11 vs 34 mL/min/1.73 m2, P = .055), and patients with dialysis at 6 months had a higher EB/EA ratio at rebound (0.8 vs 0.5, P = .047). Moreover, two patients demonstrated increasing epitope restriction and several patients displayed a shift in subclass distribution at rebound. Six patients were double positive for ANCA. ANCA rebound was seen in 50% of patients; only one patient remained ANCA positive at 6 months.

CONCLUSIONS

In this study, rebound of anti-GBM antibodies, especially if directed against the EB epitope, was associated with a worse outcome. This supports the notion that all means should be used to eliminate anti-GBM antibodies. In this study ANCA was removed early and long-term by imlifidase and cyclophosphamide.

Immunity in the balance: Fatal disseminated adenovirus infection in a patient undergoing plasma exchange and immunosuppressive chemotherapy for anti-glomerular basement membrane disease

Anti-glomerular basement membrane (anti-GBM) disease (formerly known as Goodpasture's syndrome) is a rare autoinflammatory condition that affects the renal and/or pulmonary capillaries. The standard therapeutic regimen for anti-GBM disease involves therapeutic plasma exchange (TPE), cyclophosphamide, and corticosteroids to rapidly remove and inhibit autoantibody production and reduce organ inflammation. Herein we report an 82-year-old female who developed anti-GBM disease but expired despite therapy, secondary to multi-organ failure in the setting of disseminated adenovirus disease. We discuss the utility and potential adverse effect of daily TPE for a protracted course (ie, 10-14 days), the recommended TPE intensity in the 2023 American Society for Apheresis guidelines, updated from every-other-day TPE in the 2019 guidelines, despite no new data. We also highlight the potential for unusual infections to occur in these patients due to the profound immunosuppression, and discuss the importance of balancing immunosuppression to treat the disease with close surveillance of any potential opportunistic infections.

Prognostic value of complement serum C3 level and glomerular C3 deposits in anti-glomerular basement membrane disease

Background and objectives

Activation of the complement system is involved in the pathogenesis of anti-glomerular basement membrane (anti-GBM) disease. Glomerular deposits of complement 3 (C3) are often detected on kidney biopsies. The primary objective of this study was to analyze the prognostic value of the serum C3 level and the presence of C3 glomerular deposits in patients with anti-GBM disease.

Methods

We conducted a retrospective cohort study of 150 single-positive patients with anti-GBM disease diagnosed between 1997 and 2017. Patients were categorized according to the serum C3 level (forming a low C3 (C3<1.23 g/L) and a high C3 (C3≥1.23 g/L) groups) and positivity for C3 glomerular staining (forming the C3+ and C3- groups). The main outcomes were kidney survival and patient survival.

Results

Of the 150 patients included, 89 (65%) were men. The median [interquartile range (IQR)] age was 45 [26-64]. At diagnosis, kidney involvement was characterized by a median [IQR] peak serum creatinine (SCr) level of 578 [298-977] µmol/L, and 106 (71%) patients required dialysis. Patients in the low C3 group (72 patients) had more severe kidney disease at presentation, as characterized by higher prevalences of oligoanuria, peak SCr ≥500 µmol/L (69%, vs. 53% in the high C3 group; p=0.03), nephrotic syndrome (42%, vs. 24%, respectively; p=0.02) and fibrous forms on the kidney biopsy (21%, vs. 8%, respectively; p=0.04). Similarly, we observed a negative association between the presence of C3 glomerular deposits (in 52 (41%) patients) and the prevalence of cellular forms (83%, vs. 58% in the C3- group; p=0.003) and acute tubulo-interstitial lesions (60%, vs. 36% in the C3- group; p=0.007). When considering patients not on dialysis at diagnosis, the kidney survival rate at 12 months was poorer in the C3+ group (50% [25-76], vs. 91% [78-100] in the C3- group; p=0.01), with a hazard ratio [95% confidence interval] of 5.71 [1.13-28.85] (p=0.04, after adjusting for SCr).

Conclusion

In patients with anti-GBM disease, a low serum C3 level and the presence of C3 glomerular deposits were associated with more severe disease and histological kidney involvement at diagnosis. In patients not on dialysis at diagnosis, the presence of C3 deposits was associated with worse kidney survival.

The Role of Heme Oxygenase-1 as an Immunomodulator in Kidney Disease

The protein heme oxygenase (HO)-1 has been implicated in the regulations of multiple immunological processes. It is well known that kidney injury is affected by immune mechanisms and that various kidney-disease forms may be a result of autoimmune disease. The current study describes in detail the role of HO-1 in kidney disease and provides the most recent observations of the effect of HO-1 on immune pathways and responses both in animal models of immune-mediated disease forms and in patient studies.