The therapeutic effect of doxycycline on tear deficiency dry eye in rats and the expressions of IL-6 and TNF-α in corneal tissue

Objective To observe the therapeutic effect of doxycyline on tear deficiency dry eye in rats and the expressions of IL-6 and TNF-α as anti-inflammatory mediators in dry eye.Methods Forty-eight adult healthy SD rats with main lacrimal gland removed were selected as the model of dry eye.These rats were equally divided into 3 groups,1 g/L doxycycline eye drops group,10 g/L carboxymethyl cellulose eye drops group and normal saline eye drops group,administered with eye drops four times daily respectively.1,2,5 weeks after drug administration,corneal shape,Schirmer Ⅰ experiment(SIt),break-up time(BUT) and fluorescent staining score were observed under slit lamp.Expressions of corneal epithelial IL-6 and TNF-α were detected by immunohistochemistry.Results Compared with those in saline group at fifth week,corneal surface moisture degree increased in doxy group rats,SIt filter paper wet long was(9.56±0.94)mm/5 min,BUT was(9.53±1.06)s,and fluorescence staining score was 3.37±2.94(P0.05).In doxycycline group,IL-6 and TNF-α positive cell counts were(78.67±25.29)/1 000 cells and(5.18±28.93)/1 000 cells;the number of cells with positive IL-6 and TNF-α expressions was significantly reduced(P0.05) compared with that in carboxymethyl cellulose group and the saline group at the same time point.Conclusion Doxycycline eye drop has an obvious therapeutic effect on rat dry eye,which may be related to its lessening inflammatory reaction by inhibiting the expressions of inflammatory factors IL-6 and TNF-α of rat eye surface.