The Dry Eye Zone

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Abstract: How dryness changes corneal tissue

Desiccating Stress Promotes Th17 Differentiation by Ocular Surface Tissues through a Dendritic Cell-Mediated Pathway.
Invest Ophthalmol Vis Sci. 2010 Feb 3. [Epub ahead of print]
Zheng X, de Paiva CS, Li DQ, Farley WJ, Pflugfelder SC.

Ophthalmology, Baylor College of Medicine, Houston, United States.
Purpose. To explore a phenomenon that corneal and conjunctival tissues subjected to desiccating stress promote Th17 differentiation by stimulated production of Th17 inducing cytokines through a dendritic cell (DC) mediated pathway.

Methods. Experimental dry eye was created by subjecting C57BL/6 mice to desiccating environmental stress. Corneal and conjunctival explants from dry eye or control mice were co-cultured with DCs for 24 hours, prior to adding CD4+ T cells for an additional 4 7 days. Expression of Th-17 associated genes in the cornea, conjunctiva, DCs and CD4+ T cells was evaluated by real-time PCR. Cytokine concentrations in co-culture supernatants were measured by Luminex immunobead assay. IL-17 producing T cells were identified by ELISPOT bioassay.

Results. Higher levels of IL-17A, TGF-beta1, -beta2, IL-6, IL-23 and IL-1beta mRNA transcripts and TGF-beta1, IL-6 and IL-1beta protein were observed in corneal epithelium and conjunctiva from dry eye mice. DCs co-cultured with the epithelial explants from dry eye mice for 2 days produced higher levels of TGF-beta1, IL-6, IL-23 and IL-1beta mRNA transcripts and TGF-beta1, IL-6 and IL-1beta protein. CD4+ T cells co-cultured with DCs and epithelial explants from dry eye mice, expressed increased levels of IL-17A, IL-17F, IL-22, CCL-20 and retinoic-acid-receptor-related orphan receptor-gammat (RORgammat) mRNA transcripts and increased IL-17A protein and number of IL-17-producing T cells (Th17 cells).

Conclusions. These findings demonstrate that desiccating stress creates an environment on the ocular surface that stimulates production of Th-17 inducing cytokines by corneal and conjunctival epithelia that promote Th17 differentiation through a dendritic cell mediated pathway.
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