Vitamin D Down-regulates The Pro-inflammatory Cytokine Response To Aspergillus Fumigatus Through Prrs While Expressing Protective Cathelicidin In Corneal Epithelium

Objective: In the study, we wanted to observe the expression of vitamin D receptor(VDR) in human corneal epithelial cells. What’s more, we would like to study on the pathway of VDR expression. Meanwhile, we wanted to discover the role of 1,25(OH)2D3, the active form of vitamin D, in innate immunity when challenged with Aspergillus fumigatus(AF) antigen.Methods: SYBR Realtime quantitive PCR and Immunohistochemistry was taken to examine the VDR expression in corneal epithelium. Also, Realtime quantitive PCR was performed to observe the m RNA change of VDR expression when immortalized human corneal epithelial cells(HCECs) were challenged with AF antigen in vitro. Then we used the TLR2 monoclonal antibody and Dectin-1 inhibitor laminarin to block the TLR2/1 and Dectin-1 pathway to detect the change of VDR m RNA expression. When pretreated with 1,25(OH)2D3 for 12 hours before the AF stimulation on HCECs, the TLR2, TLR4, Dectin-1 and cathelicidin antimicrobial peptide(CAMP) expression was detected by both PCR and western blot. The expression of pro-inflammatory cytokines IL-1β å'Œ IL-6 were detected at both m RNA and protein levels.Results: We conformed that the VDR was expressed in human corneal epithelium. The VDR m RNA expression increased when stimulated with AF antigen, and the TLR2 monoclonal antibody could inhibit the expression significantly(P<0.01), while the laminarin couldn’t inhibit. When pretreated HCECs with 1,25(OH)2D3 before AF stimulation, the TLR2, TLR4 and Dectin-1 expression were decreased apparently(P<0.01) while the expression of protection factor CAMP was risen significantly(P<0.01). The expression of pro-inflammatory cytokines IL-1β å'Œ IL-6 were both down-regulated by 1,25(OH)2D3.Conclusion: VDR exists in human corneal epithelium and the expression can be increased via TLR2/1-VDR pathway when stimulated with AF antigen. 1,25(OH)2D3 can inhibit the expression of TLR2, TLR4 and Dectin-1 while increasing CAMP production. The effects can reduce the damage caused by pro-inflammatory cytokines and enhance the antibacterial effects by CAMP.