The role of cytokines in experimental herpes simplex keratitis

Experimental corneal infection with herpes simplex virus 1 (HSV-1) resulted in 11-21 days in herpes simplex keratitis (HSK) in C.A1-20 but not C.B-17 strain of BALB/c Igh-1-disparate mice. Formation of mRNAs of various pro-inflammatory cytokines was analyzed in corneas and draining lymph nodes (LNs) of HSK-susceptible C.A1-20 and HSK-resistant C.B-17 mice following HSV-1 corneal inoculation by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis. Transcripts for interleukin (IL)-2 and interferon (IFN)-gamma were expressed in LNs of susceptible but not resistant mice. The level of IL-6 expression in the cornea correlated with the severity of keratitis in susceptible mice, being evident at days 4 and 14 after virus inoculation and thus showing a biphasic response. Resistant mice did not develop HSK and did not express IL-6. The IL-1beta and IL-4 gene transcription began early (day 7) in the corneas of resistant mice and then ceased, while in the corneas of susceptible mice, it began later (day 11). Taken together, these results indicate that IL-1beta, IL-4, IL-6, and IL-7 participate in the local inflammatory response in HSK.