Strain-related cytokine profiles on the murine ocular surface in response to desiccating stress

Purpose: To evaluate the effects of desiccating ocular surface stress on levels of inflammatory cytokines in the corneal epithelium, conjunctiva, and tear fluid of BALB/c and C57BL/6 mice. Methods: Experimental dry eye (EDE) was created in BALB/c and C57BL/6 mice by cholinergic blockade and exposure to a desiccating environment. Real-time polymerase chain reaction was performed to measure levels of cytokine transcripts. A multiplex immunobead assay was used to measure concentrations of these cytokines in tears. Results: Experimental dryness significantly increased the expression of interleukin (IL)-1 alpha, IL-6, and tumor necrosis factor (TNF)-alpha transcripts in the corneal epithelium and conjunctiva of C57BL/6 mice. Strain-specific changes in tear cytokine profiles were observed. C57BL/6 mice had significantly greater tear concentrations of IL-1 alpha and TNF-alpha and the Th-1 cytokines IL-2, IL-12, and interferon-gamma in response to desiccating stress than BALB/c mice. The Th-2 cytokines IL-4 and IL-10 were significantly greater in BALB/c tears. Conclusions: This study indicates that desiccating stress increases levels of certain cytokines in the corneal epithelium and conjunctiva in a strain-dependent fashion and that C57BL/6 mice had greater levels of Th-1 cytokines in their tears, whereas BALB/c mice had a greater increase in Th-2 cytokines.