Abstract
Abstract: :
Purpose: Bacterial endotoxin, lipopolysaccharide (LPS), is a potent stimulator of inflammatory response, and contributes to microbial keratitis and to the pathogenesis of sterile corneal ulcers. Previous studies using this mouse model showed that LPS-induced stromal abnormalities are due to neutrophil infiltration to the cornea and require Toll-like receptor (TLR)-4 signaling. In this study, we determined the relative contributions of IL-1α, which signals through the same intracellular pathway as TLR4, and of another pro-inflammatory cytokine TNF-α, in development of endotoxin-induced keratitis. Methods: Corneas of LPS responsive C3H/HeN mice and congenic C3H/HeJ mice were abraded. 10 ug of Pseudomonas aeruginosa endotoxin was applied to the corneal surface. Antibody to TNF-α or IL-1α was injected into the subconjunctival space, and stromal thickness and stromal haze were measured after 24h using Confocal Microscopy Through Focusing. Neutrophil infiltration was determined by immunohistochemistry. Results: Stromal thickness and haze were significantly elevated in endotoxin treated C3H/HeN mice compared with corneas exposed to water, and compared with endotoxin-treated C3H/HeJ mice (which have a mutation in TLR4). Stromal thickness and stromal haze in endotoxin treated C3H/HeN mice given either anti-TNF-α or anti-IL-1α was significantly reduced compared with control mice injected with normal rat IgG. Neutrophil infiltration to the corneal stroma was also significantly reduced in anti-TNF-α and anti-IL-1α treated mice. Conclusion: In addition to TLR4, IL-1α and TNF-α are essential for development of endotoxin-induced keratitis.
Keywords: 449 keratitis • 380 cytokines/chemokines • 469 microbial pathogenesis: experimental studies