This study confirms that the pathogenesis of ANCA-associated vasculitis has a genetic component, shows genetic distinctions between granulomatosis with polyangiitis and microscopic polyangiitis that are associated with ANCA specificity, and suggests that the response against the autoantigen proteinase 3 is a central pathogenic feature of proteinase 3 ANCA-associated vasculitis.
Interestingly, the parenchymal cells (pneumocytes type I and II) and macrophages, and not the neutrophils, express PR-3 most strongly and may contribute to lung damage in patients with WG via direct interaction with antineutrophil cytoplasmic antobodies (ANCA).
Proteinase 3 (PR3), a serine proteinase contained in neutrophil azurophilic granules, is considered a risk factor for vasculitides and rheumatoid arthritis when expressed on the outer leaflet of neutrophil plasma membrane and is the preferred target of antineutrophil cytoplasm autoantibodies (ANCA) in Wegener granulomatosis.
We observed significantly increased level of IL-17 in serum as well in culture supernatants of PBMCs after PR3 stimulation along with ROR-γt gene expression in active disease state of GPA as compared to HC.
Anti-neutrophil cytoplasmic autoantibodies (ANCA) targeting proteinase 3 (PR3) and myeloperoxidase expressed by innate immune cells (neutrophils and monocytes) are salient diagnostic and pathogenic features of small vessel vasculitis, comprising granulomatosis with polyangiitis (GPA), microscopic polyangiitis, and eosinophilic GPA.
Earlier studies have shown that circulating leucocytes from patients with Wegener's granulomatosis show elevated proteinase 3 surface expression and mRNA levels.
Elevated levels of PR3 expression have been observed in WG patients and high levels of PR3 expression corresponded to increased risk of disease relapses.
Proteinase 3 (P3), a serine protease expressed by myeloid cells, localized within azurophil granules, and also expressed on the cellular membrane of polymorphonuclear neutrophils (PMN), is the target of autoimmunity in granulomatosis with polyangiitis.
These data may be relevant in view of the observed relation between membrane expression of PR3 on nonprimed neutrophils of patients with WG and their susceptibility for relapses.
Neutrophil mPR3 expression was studied in 35 patients with WG, 15 patients with other inflammatory diseases, 125 healthy volunteers, and 27 (15 monozygotic and 12 dizygotic) pairs of twins.
We found no significant difference in the degree of maturation of PMNs from GPA patients (n = 8) and healthy controls (n = 11) as determined from cell surface expression of the neutrophil maturation marker CD16 and gene expression profile of FCGR3B.
Anti-neutrophil cytoplasmic autoantibodies (ANCA) targeting proteinase 3 (PR3) and myeloperoxidase expressed by innate immune cells (neutrophils and monocytes) are salient diagnostic and pathogenic features of small vessel vasculitis, comprising granulomatosis with polyangiitis (GPA), microscopic polyangiitis, and eosinophilic GPA.
In addition, both IL-10 mRNA and IL-10 protein levels of activated PBMCs from localized WG were elevated when compared with generalized disease (574 vs. 154 pg/ml, p<0.05) or healthy controls (574 vs. 246 pg/ml, p<0.05).