Free access
Issue
Vet. Res.
Volume 37, Number 6, November-December 2006
Page(s) 791 - 812
DOI http://dx.doi.org/10.1051/vetres:2006036
Published online 15 September 2006
How to cite this article Vet. Res. (2006) 791-812
Vet. Res. 37 (2006) 791-812
DOI: 10.1051/vetres:2006036

Toll-like receptor 2 and 9 are expressed and functional in gut-associated lymphoid tissues of presuckling newborn swine

Masanori Tohnoa, b, Takeshi Shimosatoa, Masayuki Mouea, Hisashi Asoc, Kouichi Watanabec, Yasushi Kawaia, Takahiro Yamaguchic, Tadao Saitoa and Haruki Kitazawaa

a  Laboratory of Animal Products Chemistry, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai, 981-8555, Japan
b  JSPS Research Fellow, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai, 981-8555, Japan
c  Laboratory of Functional Morphology, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai, 981-8555, Japan

(Received 8 March 2006; accepted 10 May 2006; published online 15 September 2006)

Abstract - To clarify the crucial role of Toll-like receptor (TLR) 2 and TLR9 in immature gut-associated lymphoid tissues (GALT), we focused on the expression of TLR2 and TLR9 and the immune responses induced by their ligands in the GALT of presuckling newborn swine. Quantitative real-time PCR revealed that TLR2 and TLR9 mRNA were expressed at detectable levels in all tested tissues (heart, thymus, lung, spleen, liver, kidney, skeletal muscle, duodenum, jejunum, ileum, ileal Peyer patches (Pps), and mesenteric lymph nodes (MLN)). In particular, in immature intestinal tissues and GALT, TLR2 and TLR9 mRNA were expressed at higher levels in ileal Pps and MLN than in the duodenum, jejunum, and ileum. We confirmed that the TLR2 and TLR9 proteins were also highly expressed and that their ligands were preferentially recognized by TLR2- or TLR9-expressing cells in the MLN and ileal Pps. Zymosan, CpG2006, and lactic acid bacteria could promote mitogenesis and production of multiple cytokines by the MLN and ileal Pps. In addition, double immunostaining for cytokeratin 18 and either TLR2 or TLR9 revealed that both TLR2 and TLR9 are strongly expressed in the columnar membranous (M) cells. Interestingly, while the apical membrane of the columnar M cells strongly expressed TLR2 protein and preferentially recognized zymosan, both "TLR2 expression on the apical membrane" and "TLR2-mediated zymosan binding" were negligible in neighboring enterocytes. These results indicate that TLR2 and TLR9 allow MLN and ileal Pps to respond to a variety of bacterial components immediately after birth, thereby providing newborns with a host defense system.


Key words: Toll-like receptor 2 / Toll-like receptor 9 / membranous cells / gut-associated lymphoid tissues  / newborn swine

Corresponding author: haruki@bios.tohoku.ac.jp

© INRA, EDP Sciences 2006