Role of Toll-like receptor 2 in mediating the production of cytokines and human beta-defensins in oral mucosal epithelial cell response to Leptospiral infection.

BACKGROUND: Pathogenic Leptospira spp. is the causative agent of leptospirosis. Oral mucosal cavity is one of portal entry for this bacterium. Oral mucosal epithelium provides a physical barrier and secretes cytokines, chemokines and antimicrobial peptides (AMPs) in response to microbial infection. Human β-defensins (hBDs); hBD1, hBD2, and hBD3 are predominantly AMPs expressed in the oral cavity. Toll-like receptors (TLRs) have been reported in hBD regulation. TLR2 recognizes leptospiral lipopolysaccharide, and plays a key role in the early control of leptospirosis.

OBJECTIVE: The aim of this study is to investigate the role of TLR2 in mediating the production of cytokines and hBDs in oral mucosal epithelial cell response to leptospiral infection.

METHODS: Cultivated oral mucosal epithelial cells were prepared, characterized, and compared with oral mucosal tissues. The TLR1-10 and hBD mRNA expressions were examined. Pro-inflammatory cytokine and hBD1-3 expressions in response to leptospires were determined by quantitative (q) RT-PCR.

RESULTS: The cultivated oral epithelium expressed TLR2 and hBD1-3. The induction of IL-βIL-8, TNF-α, and hBD2 were increased in response to Leptospira via TLR2 recognition.

CONCLUSION: The characteristics of primary epithelial cells and tissue were similar in terms of TLR expression. All primary epithelial cells expressed TLR2 and hBD1-3. We used primary epithelial cells to study response to L. interrogans. Our results yielded the first evidence that human TLR2 regulates hBD2 expression in oral mucosa epithelial responded to L. interrogans. Expression of hBD2 may act to neutralize the virulence or prevent the invasion of L. interrogans at the portal of entry.