TREM-1 expression in rat corneal epithelium with Aspergillus fumigatus infection.

AIM: To investigate the expression of triggering receptor expressed on myeloid cells-1 (TREM-1) in the aberrant inflammation within the corneal epithelium at early period of fungal infection.
METHODS: A total of 65 Wistar rats were randomly divided into control group, sham group and fungal keratitis (FK) group, in which the cornea was infected by Aspergillus fumigatus (A. fumigatus). After executed randomly at 8, 16, 24, 48 and 72h after experimental model being established, the severity of keratomycosis in rats was scored visually with the aid of a dissecting microscope and slit lamp. Then corneas in three groups were collected to assess the expression of TREM-1 through quantitative reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence technique and Western blot analysis. The correlation between FK inflammation and expression of TREM-1 was also analyzed.
RESULTS: Corneal inflammation scores increased with time after fungal infection (F=49.74, P=0.000). The inflammation scores in FK group were obviously higher than those in sham group on the whole (F=137.78, P=0.000). Levels of TREM-1 in the infected rat corneal epithelium had elevated at 8h and peaked at 48h (P<0.001, compared with control group). Western blot analysis also showed an obviously elevated TREM-1 level in rat corneal epithelium at 24h and 48h after fungal infection. Immunofluorescence technique showed that TREM-1 mainly existed in corneal epithelium and infected corneal stoma of rat. TREM-1 protein expression was enhanced after fungal infection. Moreover, severity of FK inflammation was significantly related to TREM-1 expression in FK (r=0.942, P=0.000).
CONCLUSION: TREM-1 may contribute to amplify the inflammation in the cornea infected with A. fumigatus and play critical roles in the battle against A. fumigatus in the innate immune responses.