IgG anti-Pentraxin 3 antibodies are a novel biomarker of ANCA-associated vasculitis and better identify patients with eosinophilic granulomatosis with polyangiitis.

Roberto Padoan, Mariele Gatto, Anna Ghirardello, Marta Tonello, Chiara Franco, Mara Felicetti, Franco Schiavon, Andrea Doria

Journal of autoimmunity 2021 Nov

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To investigate prevalence of anti-Pentraxin 3 (PTX3) antibodies in sera of anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients. Anti-PTX3 and PTX3 levels were analysed by enzyme-linked immunosorbent assays in sera from unselected patients with AAV and compared with patients with systemic lupus erythematosus (SLE, n = 130), other connective tissue diseases (CTDs, n = 97) and matched healthy controls (n = 97). Optical density (OD) cut-off for positive anti-PTX3 antibodies was determined by ROC curve analysis and set as 0.234. Indirect immunofluorescence (IIF) on fixed human granulocytes was used to analyze the fluorescence pattern of anti-PTX3 antibodies. Liquid-phase inhibition tests were conducted to assess potential interferences. We included 101 AAV patients (females 58%, median age 60[51-69] years) affected either with granulomatosis with polyangiitis (GPA, n = 51), microscopic polyangiitis (MPA, n = 12) or eosinophilic granulomatosis with polyangiitis (EGPA, n = 38). Anti-PTX3 antibodies were detected in 29.7% AAV patients, being significantly higher than in healthy controls (p < 0.001) and CTDs (p = 0.030) but lower than in SLE (p = 0.004). Anti-PTX3 antibody prevalence was 44.7% in EGPA, 25% in MPA and 19% in GPA (p = 0.034). Among ANCA negative patients, 35.7% displayed positive anti-PTX3 antibodies. Anti-PTX3 were associated with a lower prevalence of systemic (p = 0.002), ear-nose-throat (p = 0.006) and renal manifestations (p = 0.016). Anti-PTX3 antibodies were characterized by a specific IIF pattern on fixed granulocytes. PTX3 serum levels resulted lower in AAV than healthy controls (p < 0.001). PTX3 inhibited anti-PTX3 binding in a dose-dependent manner. Anti-PTX3 autoantibodies appear a promising novel biomarker of AAV, especially EGPA. Copyright © 2021 Elsevier Ltd. All rights reserved.

Citation

Roberto Padoan, Mariele Gatto, Anna Ghirardello, Marta Tonello, Chiara Franco, Mara Felicetti, Franco Schiavon, Andrea Doria. IgG anti-Pentraxin 3 antibodies are a novel biomarker of ANCA-associated vasculitis and better identify patients with eosinophilic granulomatosis with polyangiitis. Journal of autoimmunity. 2021 Nov;124:102725