Aim: To investigate the co-regulation of dendritic cell-associated C-type lectin-1 (Dectin-1), Toll-like receptor 2 (TLR2), and relative chemotactic factors in the Telomease-immortalized human corneal epithelial (THCE) cells after exposure to Aspergillus fumigatus (Af) hyphae.
Methods: The normal THCE cells were investigated as control. After cultured in vitro with Af hyphae, with or without laminarin and anti-TLR2 antibody for 4, 8, 16 and 24h, THCE cells were harvested. The expression of Dectin-1, TLR2, CXCL1 and CXCL8 mRNA were measured by real-time quantitative polymerase chain reaction at the stimulation of 4, 8 and 16h separately. The protein expression of Dectin-1 and TLR2 were analyzed at 8, 16, and 24h by Western blot.
Results: The mRNA expression of CXCL1 and CXCL8 increased in THCE cells after stimulated by Af hyphae. The stimulatory effects on these inflammatory chemokines were shown in a dose-dependent manner and reached the peak at 8h. Af hyphae significantly stimulated the production of Dectin-1 and TLR2 in THCE cells at both mRNA and protein levels. The protein of Dectin-1 and TLR2 gradually increased till 16h. While pretreated with laminarin (a Dectin-1 inhibitor), the expression of TLR2, CXCL1 and CXCL8 all decreased dramatically at the peak point. Interestingly, when pretreated with TLR2 neutralizing antibody, the expression of Dectin-1, CXCL1 and CXCL8 also decreased dramatically at the peak point.
Conclusion: These findings suggest that Dectin-1 and TLR2 co-regulated with each other after treated with inactive Af hyphae in the THCE cells, and they contribute together to the inflammatory responses by induction of chemokines CXCL1 and CXCL8.
Keywords: Corneal epithelial cell; Toll-like receptor 2; chemokines; dendritic cell-associated C-type lectin-1.