Furthermore, when injected intravenously into immunoglobulin-free mice, they deposited in the glomeruli, accompanied by murine complement C3. The kidneys showed mesangial proliferation and matrix expansion, thus reproducing pathologic changes characteristic of the human disease. These results support the multi-hit hypothesis wherein Gd-IgA1, the key autoantigen in IgA nephropathy, is produced as a result of dysregulation of multiple enzymes in IgA1-producing cells and

forms nephritogenic immune complexes Nivolumab with anti-glycan autoantibodies. These findings provide insight into the mechanisms of disease in IgA nephropathy and offer clues for future development of disease-specific therapy and biomarkers. SUZUKI YUSUKE, SUZUKI HITOSHI, MUTO MASAHIRO, OKAZAKI KEIKO, NAKATA JUNICHIRO, TOMINO YASUHIKO Juntendo University Faculty of Medicine, Japan Impaired immune regulation along the “mucosa-bone marrow axis” has been postulated

to play an important role in the pathogenesis of IgA nephropathy (IgAN) (1). Accumulating evidence from experimental approaches with animal models suggests that there is dysregulation of innate immunity in IgAN resulting in changes in the mucosal immune system (2, 3). Our recent experimental studies with IgAN prone mice revealed that mucosal activation of Toll like receptors (TLR) in B cells and dendritic cells are involved in the production of nephritogenic IgA and IgA immune complex (IC) (4–6). On the other hand, the nephritogenic roles of galactose-deficient Erlotinib ic50 IgA1 (Gd-IgA1) and Gd-IgA1 bound with anti-glycan IgG in IC (IgA/IgG-IC) have been L-gulonolactone oxidase discussed in human IgAN (7). Although many clinical studies indeed show serum elevation of GdIgA1 and IgA/IgG IC in IgAN patients and association between these serum levels and the disease activity (8), their production sites and relevant

cell types remain unclear. Our recent clinical studies indicate that the tonsils may be one of major sites for the production of GdIgA1 and tonsillar TLR9 activation may contribute to the extent of glomerular injury via the GdIgA1 production (5, 9). Moreover, we also recently found that aberrant overexpression of B cell related cytokines such as a proliferation-inducing ligand (APRIL) and its receptors are involved in the IgA/IgG IC formation. In this symposium, we would like to discuss the pathological roles of palatine tonsils and underlying molecular mechanisms in IgAN. 1. Suzuki Y, Tomino Y. The mucosa-bone-marrow axis in IgA nephropathy. Contrib Nephrol. 2007;157:70–79. 2. Suzuki Y, Tomino Y. Potential immunopathogenic role of the mucosa-bone marrow axis in IgA nephropathy: insights from animal models. Semin Nephrol. 2008;28:66–77. 3. Suzuki Y, Suzuki H, Sato D et al. Reevaluation of the mucosa-bone marrow axis in IgA nephropathy with animal models. Adv Otorhinolaryngol. 2011; 72:64–67. 4. Suzuki H, Suzuki Y, Narita I, et al.