ABSTRACT
Objective Our previous study demonstrated that toll-like receptor 2(TLR2) can distinguish extraneous antigen and prevent the immunological response. This study was designed to detect the expression of toll-like receptor 2 (TLR2) mRNA in cornea and investigate the effect of steroid on TLR2 expression in rats cornea following allograft penetrating keratoplasty. Methods The penetrating keratoplasty models were established in SPF rats with the 108 SD rats as receiptors and 36 SPF Wistar rats as donors, and other 6 SPF SD rats worked as normal controls. The receiptor rats were divided randomly into autograft group, allograft group and steriod group. The clarity and neovascularization of corneas of experiment rats were examined under the slit-lamp microscope and the rejection index was calculated based on Holland criteria. Corneal histopathological examination was carried out by hemotoxylin and eosin staining under the light microscope, and real time-PCR was employed for the detect of TLR2 mRNA in the corneas at the fifth, seventh and ninth day after operation. The experimental animals were obtained from the Animal Experimental Center of Southern Medical University and the procedure followed the Statement of Association for Research in Vision and Ophthalmology. Results The rejection occurred in 7 days after operation in allograft group, and only mild edema, opacity and neovascularization of corneas were found at different degrees in 9 days after operation in autograft group and steriod group. Severe corneal edema, a lots of inflammatory cells infiltration and new vessels in stroma were seen in allograft group, and mild inflammatory response was found in autograft group and steriod group. Normal comeal structure was exhibited in normal control group under the light microscope. The fold differences of TLR2 mRNA expression in cornea after amplification was significantly different among three groups and different time points (F_(group) = 39. 46, P = 0. 00; F_(time) =35. 38, P = 0. 00 ; F_(interaction) = 45. 66, P =0. 00), and the evident enhance of TLR2 mRNA expression was revealed in allograft group compared with autograft group (P ＜ 0. 05) and declined in steriod group (P ＜ 0. 05). Conclusion Steriod may restrain the acute allograft rejection by down-regulating the expression of TLR2 in corneas and its signals transaction. This result suggests that steriod offer a protection from rejection of cornea after penetrating keratoplasty.