Pauci-immune glomerulonephritis: does negativity of anti-neutrophilic cytoplasmic antibodies matters?

A significant proportion of pauci-immune glomerulonephritis (PIGN) patients are reported to have absence of anti-neutrophilic cytoplasmic antibodies (ANCA). However, studies are controversial regarding their significance and there is limited data after the new prognostic classification of PIGN. Renal biopsy-proven cases of PIGN were included and their clinical details, ANCA status by immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA), Birmingham Vasculitis Activity Score (BVAS) and treatment outcomes at 6 months were noted. The renal biopsies were classified according to the proposed histopathological classification. Scoring was done from 0-3 for interstitial edema, interstitial fibrosis and tubular atrophy (IFTA), interstitial inflammation and arteriosclerosis. The percentage of glomeruli with sclerosis, cellular and fibrous crescents, and percentage of subjects with glomerulitis, tuft necrosis, interstitial granuloma and vasculitis were noted. Out of the 84 subjects included in the study, 33 (39.3%) were negative for ANCA by both IIF and ELISA. These subjects had significantly higher renal involvement, less extra-renal manifestations and lower BVAS. On histology, they had significantly higher proportion of crescentic class (66.7% vs. 41.2%, P = 0.039), higher number of cellular crescents (66.12% vs. 53.3%, P = 0.00008), higher IFTA (1.53 vs. 1.02, P = 0.009) and less interstitial edema (1.44 vs. 1.96, P = 0.003). The treatment outcomes were worse in ANCA-negative PIGN subjects, with significantly less improvement (37.2% vs. 62.8%, P = 0.02), more deterioration (40.7% vs. 14%, P = 0.006), and reduced probability of becoming dialysis free (31.6% vs. 69.6% P = 0.009). A negative ANCA in PIGN is associated with crescentic class, more IFTA and poor treatment outcomes.

Sharma A ，Nada R ，Naidu GS ，Minz RW ，Kohli HS ，Sakhuja V ，Gupta KL ，Rathi M ... -  《-》

A historical study of American patients with anti-neutrophil cytoplasmic antibody negative pauci-immune glomerulonephritis.

Shah S ，Havill J ，Rahman MH ，Geetha D ... -  《-》

Antineutrophil cytoplasmic antibody negative pauci-immune extracapillary glomerulonephritis.

Pauci-immune extracapillary glomerulonephritis (PEGN) is one of the most common causes of rapidly progressive glomerulonephritis and is usually associated with circulating anti-neutrophil cytoplasmic antibodies (ANCAs). However, a significant number of individuals with PEGN test negative for ANCA and this study aimed to analyze the characteristics of this subgroup of patients. Patients from two centres who were diagnosed with PEGN between 1997 and 2014 were studied retrospectively. Clinicopathological characteristics and renal outcome were compared between patients presenting with pauci-immune necrotizing extracapillary glomerulonephritis associated or not with the presence of circulating ANCA. Among the 114 patients with PEGN, 29 (25.4%) were ANCA negative. Compared with the 85 ANCA-positive patients, ANCA-negative patients were younger at the onset (54.8 ± 17.2 vs. 62 ± 14.0 years; P < 0.05). The median level of urinary protein excretion was significantly higher among ANCA-negative patients (3.1 vs. 1 g/24 h; P < 0.001), whereas no differences were found in renal function and need for dialysis between ANCA-negative and positive groups. Extrarenal involvement was present independently of ANCA status. Histological analysis showed that ANCA-negative patients were more likely to have mesangial proliferation (P < 0.05). Renal and global survival were similar between ANCA-negative and positive patients, and treatment response and relapse rates were comparable in both groups. ANCA-negative pauci-immune extracapillary glomerulonephritis is not a rare condition and is part of a systemic vasculitis disease. Although ANCA-negative patients have renal and histological characteristics that differ from ANCA-positive patients, renal survival and treatment response in PEGN are independent of ANCA status.

Villacorta J ，Diaz-Crespo F ，Acevedo M ，Guerrero C ，Mollejo M ，Fernandez-Juarez G ... -  《-》

Comparative Histological Subtyping of Immune Cell Infiltrates in MPO-ANCA and PR3-ANCA Glomerulonephritis.

Acute kidney injury (AKI) is a common and severe complication of anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), potentially leading to chronic kidney disease (CKD), end-stage renal disease (ESRD), or death. Pathogenic ANCAs, in particular proteinase 3 (PR3) and myeloperoxidase (MPO), trigger a deleterious immune response with intrarenal immune cell infiltration resulting in a pauci-immune necrotizing and crescentic glomerulonephritis (GN). However, a systematic analysis of intrarenal immune cell subtypes concerning neutrophils, eosinophils, plasma cells, and mononuclear cell infiltrates (macrophages, lymphocytes) in ANCA GN remains elusive. Therefore, we aimed to compare distinct immune cell infiltrates in association with clinicopathological findings in ANCA GN. A total of 53 kidney biopsies with ANCA GN at the University Medical Center Göttingen were retrospectively analyzed. Histological infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the total area of inflammation. Neutrophilic infiltrates were associated with glomerular necrosis and severe kidney injury in ANCA GN. Among tubulointerstitial lesions, intrarenal neutrophils correlated with interstitial inflammation, tubulitis, and inflammation in areas of interstitial fibrosis/tubular atrophy (IFTA), representing active inflammatory lesions. Concerning eosinophils, infiltrates were associated with severe kidney injury, interstitial inflammation, and cellular casts independent of glomerular lesions, implicating a distinct role in inflammation and damage in ANCA GN. Plasma cell infiltrates correlated with tubulitis and interstitial fibrosis and were associated with renal replacement therapy during the short-term disease course. Finally, mononuclear cell infiltrates correlated with severe kidney injury and active histopathological lesions (glomerular crescents, interstitial inflammation, tubulitis, inflammation, and tubulitis in areas of IFTA) besides chronic lesions (interstitial fibrosis and tubular atrophy) in ANCA GN. Interestingly, intrarenal subtypes of immune cell infiltrates differed in MPO-ANCA versus PR3-ANCA GN and were associated with distinct glomerular and tubulointerstitial lesions, implicating different pathogenic mechanisms of kidney injury in ANCA subtypes. Our observations imply distinct pathomechanisms contributing to inflammation and renal injury in MPO vs. PR3-associated ANCA GN and potentially contribute to new therapeutic targets in specific ANCA subtypes.

Hakroush S ，Tampe D ，Ströbel P ，Korsten P ，Tampe B ... -  《Frontiers in Immunology》

Histopathological classification of pauci-immune glomerulonephritis and its impact on outcome.

Naidu GS ，Sharma A ，Nada R ，Kohli HS ，Jha V ，Gupta KL ，Sakhuja V ，Rathi M ... -  《-》