Effects of ocular inflammation on tear proteins. I. Thiol protease inhibitors

Concentrations of protease inhibitors found in tears have been observed to vary during ocular inflammation. Possible stimuli for these variations were tested for by studying thiol protease inhibitor concentrations in models of ocular inflammation. Inflammatory responses were elicited either by topical application of arachidonic acid (AA), or compound 48/80. For each model, four rabbits were treated in one eye with the inflammatory stimulant and tear samples were collected before and up to five hours following treatment. Control animals were treated with buffer. When compared to pretreatment values, tears from AA-treated eyes showed decreased inhibitor at one and two hours and an increased inhibitor concentration at three hours. In the 48/80 model, inhibitory activity and protein levels were elevated when compared over time to the control group (p greater than or equal to 0.02, p greater than or equal to 0.0001 respectively). When compared to pretreatment values, inhibitor values were elevated at all times after treatment and protein values were elevated at one and three hours in this model. Serum proteins were also increased in the tears of rabbits treated with 48/80. The results suggest that one or more of the mediators released by basophil or mast cell degranulation stimulate increased tear protease inhibitory activity and tear serum proteins.