Interaction of Antibodies to Proteinase 3 (Classic Anti-Neutrophil Cytoplasmic Antibody) with Human Renal Tubular Epithelial Cells: Impact on Signaling Events and Inflammatory Mediator Generation~1

摘要

Among the anti-neutrophil cytoplasmic Abs (ANCA), those targeting proteinase 3 (PR3) have a high sensitivity and specificity for Wegener's granulomatosis (WG), A pathogenetic role for these autoantibodies has been proposed due to gheir capacity of activating neutrophils in vitro. Recently, PR3 was also detected in human renal tubular epithelial cells (TEC). In the present study, the effect of murine monoclonal anti-PR3 Abs (anti-PR3) and purified c-ANCA targetign PR3 from WG serum on isolated human renal tubular cell signaling and inflammatory mediator release wad characterized. Priming of TEC-#alpha# resulted in surface expression of PR3, as quantified in immunofluorescence studies and by flow cytometry. Moreover, PR3 was immunoprecipitated hydrolysis, resulting in a remarkable accumulation of insotiolphosphates, control IgG was entirely ineffective, whereas PR3-ANCA reproduced the phosphoinositide response. The signaling response was accompanied by a pronounced release of superoxidanion into the cell supernatant. Moreover, large amounts of PGE_2 and, to a lesser extent, of thromboxane B_2, the stable metabolite of TxA_2, were secreted from anti-PR3 Abs directly target renal TECs, thereby provoking pronounced activation fo the phosphinositide-related signal transduction pathway. Associated metabolic events such as the release of reactive oxygen species and lipid mediators may directly contribute to the development of renal lesions and loss of kidney function in WG.