The Effect of TLR4 on the Survival of MHC Mismatched Corneal Allograft

Abstract

Purpose: : To investigate the role of TLR4 on the MHC mismatched allograft rejection in corneal transplantation

Methods: : Twenty C57BL/6 wild-type mice and Twelve C57BL/6 TLR4 knock-out(KO) mice were divided into 3 groups for corneal transplantation. Corneal grafts from C3H/HeN mice were transplanted to B6 mice(n=10) or to TLR4-KO mice(n=12). Autografts were transplanted from B6 to B6 mice(n=10). Survival was analyzed based on total graft edema(n=23), and the mice were sacrificed after full rejection. Nine mice were sacrificed in three groups(each n=3) at postoperative 10 days and cervical lymph nodes were collected. CD11c, CD80, CD86, CD4, CD44, CD69, CD25, and FoxP3 were evaluated using flow cytometer(Becton & Dickinson, USA).

Results: : Median survival time(MST) of corneal grafts from C3H mice to TLR4-KO were shortened than MST of the others. At 10days, the expression of CD11c and CD80/86 were 2.2% and 27.7% in autograft, 1.88% and 17% in allograft of wild type, and 2.38% and 43.3% in allograft of TLR4 KO. The expression of CD44/CD69 increased to 8.1% in TLR4 KO recipients compared with those of autograft(3.69%) or allograft(5.53%) in B6. The expression of CD25/Foxp3 doubled in TLR4 KO mice compared with those of the other groups. The expression of CD80/86 and CD44/69 were still higher in TLR4 KO mice than in the other groups after full rejection.

Conclusions: : TLR4 may have an immune modulatory role on maturation of dendritic cells in ocular surfaces which have gram positive commensals, affecting the survival of MHC mismatched allograft.

Keywords: immune tolerance/privilege • cornea: basic science