Abstract
Purpose: :
Serratia marcescens is frequently isolated from contact lenses and lens cases, and is associated with contact lens related acute red eye (CLARE). In the current study, we used a murine model of S. marcescens to examine the role of TLRs in corneal inflammation.
Methods: :
The central corneal epithelium was abraded, and 1 x 10^7 S. marcescens was added. Corneal thickness and haze were examined using the ConfoScan3 microscope system, neutrophil infiltration was enumerated after immunohistochemistry, and viable bacteria were quantified by CFU. Bone marrow macrophages were stimulated with tobramycin-killed S. marcescens, and cytokine production in supernatants was measured by ELISA.
Results: :
ATCC and clinical strains of S. marcescens induced time and dose dependent neutrophil recruitment to the corneal stroma and increased corneal haze and thickness in C57BL/6 mice. In vivo, these parameters were significantly lower in MyD88-/- TLR4/5-/- IL-1R-/- mice, but not in MD-2-/-, , TLR5-/-, TIRAP -/-, or TRIF-/- mice. Similarly, killed S. marcescens induced TNF-α, CXCL1 and CXCL2 production C57BL/6 macrophages in a dose dependent manner. Cytokine production was significantly lower in MyD88-/-. TLR4/5-/-, IL-1R-/-, and also in MD-2-/-, TIRAP-/- and TRIF-/- macrophages.
Conclusions: :
S. marcescens - induced corneal inflammation is activated by TLR4/MD-2/MyD88 and TRIF, and by the TLR5MyD88 and IL-1R1/MyD88 - dependent pathways. These findings indicate potential therapeutic targets for S. marcescens - induced CLARE.
Keywords: cornea: basic science • keratitis • inflammation