Expression of a chemokine by ciliary body epithelium in horses with naturally occurring recurrent uveitis and in cultured ciliary body epithelial cells.

OBJECTIVE

To determine whether a chemokine (RANTES)-like protein expressed by ciliary epithelium plays a role in uveitis.

SAMPLE POPULATION: 3 clinically normal horses intradermal, 5 eyes from 5 horses with recurrent uveitis, and 10 normal eyes from 5 age- and sex-matched horses.

PROCEDURE: Cross-reactivity and sensitivity of recombinant human (rh)-regulated upon activation, normal T-cell expressed and secreted (RANTES) protein were evaluated in horses by use of intradermal hypersensitivity reactions and a chemotaxis assay. Aqueous humor and ciliary body of eyes from clinically normal horses and horses with uveitis were examined for RANTES expression by use of an ELISA and reverse transcription-polymerase chain reaction (RT-PCR). Expression of RANTES mRNA and protein content of primary cultures of equine ciliary pigmented epithelial cells (RT-PCR) and culture supernatant (ELISA) were measured 6 or 24 hours, respectively, after cultures were stimulated with interleukin-1beta and tumor necrosis factor-alpha.

RESULTS

Strong reactions to intradermal hypersensitivity testing and significant chemotaxis of equine leukocytes to rh-RANTES wereas observed. Aqueous humor of eyes from horses with uveitis contained increased concentrations of rh-RANTES-like protein (mean +/- SD, 45.9+/-31.7 pg/ml), compared with aqueous humor from clinically normal horses (0 pg/ml). Ciliary body from horses with uveitis expressed RANTES mRNA, whereas ciliary body from clinically normal horses had low mRNA expression. Stimulated ciliary pigmented epithelial cells expressed increased amounts of rh-RANTES-like protein (506.1+/-298.3 pg/ml) and mRNA, compared with unstimulated samples.

CONCLUSIONS AND CLINICAL RELEVANCE: Ciliary epithelium may play a role in recruitment and activation of leukocytes through expression of RANTES.