The roles of surfactant protein D during Aspergillus fumigatus infection in human corneal epithelial cells.

Abstract

To investigate roles of surfactant protein D (SP-D) and relative cytokines in human corneal epithelial(HCE) cells exposed to aspergillus fumigatus (AF) antigens. HCE cells cultured in vitro with AF antigens and sampled at 0, 0.5, 1 hour, 2, 4, 6 and 8 hours. The expression of SP-D mRNA was evaluated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR).The expression of SP-D protein was shown by ELISA and immunocytochemistry SP methods. The expression of NF-κB and relative downstream cytokines such as TNF-α, IL-1β, IL-8 and IL-10 in supernatant fluid were measured by ELISA. SP-D mRNA and protein were detected in untreated HCE cells. The expression of SP-D and the relative downstream cytokines rose after being stimulated with AF antigens. SP-D mRNA began to rise at 0.5 hour and the most significantly peak was in 2 hours. The protein of SP-D in supernatant fluid had the same trend with mRNA. Immunocytochemistry of SP-D showed positive expression and gradually increased to 6 hours, and then the expression began to decline. NF-κB was activated after treated by AF antigens and the changes had correlation with SP-D. TNF-α, IL-1β, IL-8 and IL-10 began to rise after given AF antigens 1 hour and were 1.82, 1.43, 1.12 and 1.28 times higher than the untreated HCE cells separately. The expression of TNF-α and IL-1β reached the peak at 2 hours, separately 2.80 and 2.86 times than the untreated. The expression of IL-8 and IL-10 gradually increased with a time-dependent manner. HCE cells exists SP-D and it may play a significant role in pathogenesis of keratomycosis. AF may induce human corneal epithelial cells to express inflammatory cytokines via SP-D and NF-κB pathway. SP-D possibly mediates the recognition to AF mycelium.