Expression of inflammatory cytokines in a mouse model of keratomycosis

Abstract

To investigate the expression, contribution and regulation of predominant inflammatory cytokines in the inflammation process of in a mouse model of keratomycosis. It was an experimental study. Two hundred forty inbred BALB/c mice were randomly divided into four groups (injury control group, F. solani infected group, A. fumigatus infected group and C. albicans infected group) and establishment fungal keratitis was performed. At 1, 3, 5, and 7 days after infection, the photographs of their corneas were taken using the slit lamp and the digital camera system. The presence of inflammatory cells and fungal hyphae were observed by HE and PAS staining. Four inflammatory cytokines in infectious corneas, including MIP-2, KC, IL-1β, and IL-6, were detected respectively for expression of mRNA and protein levels, using RT-PCR and ELISA. One-way ANOVA was used to test the comparisons of the clinical scoring, RT-PCR, and ELISA, and LSD was used to test multiple comparisons. The course and inflammatory reaction of corneal tissue in all infected group increased at day 3 and 5 and gradually decreased after day 7 with time. The RT-PCR results showed, the mRNA expression levels of MIP-2 and IL-1β were the highest in A. fumigatus infected group, and the expression levels of KC was the highest in C. albicans infected group. Additionally, the expression levels of IL-6 were found to be the highest in F. solani infected group. The mRNA expression levels of IL-1β and KC in each experimental group were higher than those of IL-6 and MIP-2. The peak expression levels of MIP-2, KC, and IL-1β occurred at day 5, day 1, and day 3 in F. solani infected group, A. fumigatus infected group and C. albicans infected group, respectively. However, the peak expression level of IL-6 occurred at day 1 and 7, day 1 and 7, and day 1 and 5 in the F. solani, A. fumigatus, and C. albicans groups, respectively. The difference of mRNA expression of each cytokine had statistically significant between each groups (MIP-2: F = 1675.339, P < 0.01; KC: F = 730.267, P < 0.01; IL-1β: F = 297.106, P < 0.01; IL-6: F = 174.513, P < 0.01). The protein expression levels of the four cytokines in the infected groups from high to low in turn were IL-1β, MIP-2, KC and IL-6. The trend of protein expression of the four cytokines at each time point was the same as the cytokine mRNA expression in different experimental groups as well as within the same group. The difference of protein expression of each cytokine had statistically significant between each groups (MIP-2: F = 2871.736, P < 0.01; KC:F = 886.598, P < 0.01; IL-1β: F = 3595.488, P < 0.01; IL-6: F = 89.225, P < 0.01). The expression levels of MIP-2, KC and IL-1β are closely related to the performance of the disease severity and inflammatory reaction of FK. The expression of MIP-2 and IL-1β may play important role in the pathogenesis of FK.