The role of Dectin-1/Raf-1 signal cascade in innate immune of human corneal epithelial cells against Aspergillus fumigatus infection

AIM: To investigate the expression of the v -raf -1 murine leukemia viral oncogene homolog 1 (Raf-1) and its role in the innate immune response of human corneal epithelial cells (HCECs) infected by Aspergillus fumigatus. METHODS: HCECs were cultured in vitro. They were randomly divided into 4 groups, including control group, Aspergillus fumigatus group, GW5074 (an inhibitor of Raf -1) group and Laminarin [an inhibitor of Dendriti - cell-associated C-type lectin 1 (Dectin -1)] group. The protein expression level of total Raf-1 and p-Raf-1 was measured by Western blot. The expression of IL-6 and IL -8 mRNA in each group was detected by real -time polymerase chain reaction. RESULTS: In Aspergillus fumigatus group, total Raf-1 protein levels in HCECs remained unchanged at 5, 15, 30 and 45min after infection, while p-Raf-1 expression was significantly enhanced at 30min after infection compared with control group. However, the expression of p-Raf-1 was apparently declined after treated with GW5074 or Laminarin compared with Aspergillus fumigates group. The expression levels of IL-6, IL -8 mRNA were significantly increased after stimulation with fumigatus compared with control group. Pre-treated with GW5074 significantly inhibited Aspergillus fumigatus-induced upregulation of IL -8 and IL-6. CONCLUSION: Aspergillus fumigatus stimulation can elevate the expression of p -Raf -1 in HCECs in vitro Dectin -1/Raf -1 signal pathway may play a role on regulating the expression of inflammatory cytokines, including IL-6 and IL-8.