title: Proteinase 3, the autoantigen in granulomatosis with polyangiitis, associates with calreticulin on apoptotic neutrophils, impairs macrophage phagocytosis, and promotes inflammation.
abstract: Proteinase 3 (PR3) is the target of anti-neutrophil cytoplasm Abs in granulomatosis with polyangiitis, a form of systemic vasculitis. Upon neutrophil apoptosis, PR3 is coexternalized with phosphatidylserine and impaired macrophage phagocytosis. Calreticulin (CRT), a protein involved in apoptotic cell recognition, was found to be a new PR3 partner coexpressed with PR3 on the neutrophil plasma membrane during apoptosis, but not after degranulation. The association between PR3 and CRT was demonstrated in neutrophils by confocal microscopy and coimmunoprecipitation. Evidence for a direct interaction between PR3 and the globular domain of CRT, but not with its P domain, was provided by surface plasmon resonance spectroscopy. Phagocytosis of apoptotic neutrophils from healthy donors was decreased after blocking lipoprotein receptor-related protein (LRP), a CRT receptor on macrophages. In contrast, neutrophils from patients with granulomatosis with polyangiitis expressing high membrane PR3 levels showed a lower rate of phagocytosis than those from healthy controls not affected by anti-LRP, suggesting that the LRP-CRT pathway was disturbed by PR3-CRT association. Moreover, phagocytosis of apoptotic PR3-expressing cells potentiated proinflammatory cytokine in vitro by human monocyte-derived macrophages and in vivo by resident murine peritoneal macrophages, and diverted the anti-inflammatory response triggered by the phagocytosis of apoptotic cells after LPS challenge in thioglycolate-elicited murine macrophages. Therefore, membrane PR3 expressed on apoptotic neutrophils might amplify inflammation and promote autoimmunity by affecting the anti-inflammatory "reprogramming" of macrophages.
authors: INSERM U1016, Paris 75014, France.
authors: Julie
authors: J
authors: Gabillet
authors: Arnaud
authors: A
authors: Millet
authors: Magali
authors: M
authors: Pederzoli-Ribeil
authors: Pascale
authors: P
authors: Tacnet-Delorme
authors: Loïc
authors: L
authors: Guillevin
authors: Luc
authors: L
authors: Mouthon
authors: Philippe
authors: P
authors: Frachet
authors: Véronique
authors: V
authors: Witko-Sarsat
mesh_terms: D000276:Adjuvants, Immunologic / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001324:Autoantigens / Q000378:metabolism*; D037282:Calreticulin / Q000378:metabolism*; D014890:Granulomatosis with Polyangiitis / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D008264:Macrophages / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D055953:Microscopic Polyangiitis / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D053146:Myeloblastin / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D051381:Rats
chemical_list: D000276:Adjuvants, Immunologic; D001324:Autoantigens; D037282:Calreticulin; D008565:Membrane Proteins; D053146:Myeloblastin