Urinary myeloid IgA Fc alpha receptor (CD89) and transglutaminase-2 as new biomarkers for active IgA nephropathy and henoch-Schönlein purpura nephritis

Abstract Background IgA nephropathy (IgAN) and Henoch-Schonlein purpura nephritis (HSPN) are glomerular diseases that share a common and central pathogenic mechanism. The formation of immune complexes containing IgA1, myeloid IgA Fc alpha receptor (FcαRI/CD89) and transglutaminase-2 (TG2) is observed in both conditions. Therefore, urinary CD89 and TG2 could be potential biomarkers to identify active IgAN/HSPN. Methods In this multicenter study, 160 patients with IgAN or HSPN were enrolled. Urinary concentrations of CD89 and TG2, as well as some other biochemical parameters, were measured. Results Urinary CD89 and TG2 were lower in patients with active IgAN/HSPN compared to IgAN/HSPN patients in complete remission ( P from inactive IgAN/HSPN in both situations : CD89xTG2/proteinuria ratio (AUC: 0.84, P and CD89xTG2/urinary creatinine ratio (AUC: 0.82, P P P P Conclusions Determination of CD89 and TG2 in urine samples can be useful to identify patients with active IgAN/HSPN.