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Clinical and Developmental Immunology
Volume 2011, Article ID 819646, 10 pages
http://dx.doi.org/10.1155/2011/819646
Research Article

Different Pathological Roles of Toll-Like Receptor 9 on Mucosal B Cells and Dendritic Cells in Murine IgA Nephropathy

Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Juntendo University, Tokyo 113-8421, Japan

Received 22 December 2010; Accepted 2 May 2011

Academic Editor: K. Blaser

Copyright © 2011 Tadahiro Kajiyama et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Although pathogenesis of IgA nephropathy (IgAN) is still obscure, pathological contribution of mucosal immunity including production of nephritogenic IgA and IgA immune complex (IC) has been discussed. We have reported that mucosal toll-like receptor (TLR)-9 is involved in the pathogenesis of human and murine IgAN. However, cell-type expressing TLR9 in mucosa remains unclear. To address this, we nasally challenged cell-specific CpG DNA ((i): dendritic cell: (DC), (ii): B cell, (iii): both), known as ligand for TLR9, to IgAN prone mice and analyzed disease phenotype of each group. After 8 times of the weekly administration, every group showed deterioration of glomerular damage. However, CpG-A-group showed clear extension of mesangial proliferative lesions with increase of serum IgA-IgG2a IC and its glomerular depositions, while CpG-B-group showed extent of glomerular sclerotic lesions with increase of serum and glomerular IgA and M2 macrophage infiltration. Present results indicate that mucosal TLR9 on B cells and DC may differently contribute to the progression of this disease via induction of nephritogenic IgA or IgA-IgG IC, respectively. This picture is suggestive for the pathological difference between child and adult IgAN.