Toll-like receptors (TLRs) are key components of the innate immune system that detect microbial infection and trigger antimicrobial host responses. To determine the role of TLR2 in the expression of pro- and anti-inflammatory cytokines in corneal fibroblasts challenged by fungi, we used siRNA specific for TLR2 to knockdown TLR2 expression in telomerase-immortalized human stroma fibroblasts (THSF). TLR2 expression was assessed by immunocytochemistry, reverse transcription (RT)-PCR and western blotting analyses, and we found that THSF transfected with TLR2-siRNA plasmid exhibited a reduced level of TLR2 when compared with the control cells transfected with empty plasmid. Then the transfected and control cells were stimulated by hyphae or conidia of Fusarium solu and mRNA levels of IL-1beta and IL-10 were measured by real-time RT-PCR. We observed that stimulation of control cells with F. solu resulted in elevation of IL-1beta and IL-10 mRNA with hyphae being more stimulatory than conidia. In contrast, F. solu-stimulated IL-10 production by transfected THSF was severely impaired (with a decrease of approximately 82% in hyphae and 70% in conidia stimulation), while IL-1beta production was partially inhibited (with a reduction of 60 and 54% in hyphae and conidia stimulations). Our results suggested that TLR2 is a major pattern recognition receptor able to detect F. solu in vitro and may play the anti-inflammatory role through the induction of IL-10. This may lead to a better understanding of the pathogenesis of cornea fungal infections and immune evading.
Animals Cell Line, Transformed