Evaluation of butyric acid as a potential supportive treatment in anterior uveitis

Background: The aim of the study was to evaluate the anti-inflammatory effect of topically administered aqueous sodium butyrate solution in an endotoxin-induced uveitis rat model and compare the results with corticosteroid treatment. Material and methods: Forty female Lewis rats were randomly divided into five groups. Uveitis was induced by a single lipopolysaccharide (LPS) injection into each footpad of each LPS+ rat. Group I (naive) received saline injected into the footpad of each rat at a dose of 0.1 mL/each footpad; Group II (LPS+) received saline solution topically. Group III (LPS+ Dex) — an aqueous dexamethasone sodium phosphate solution topically; Group IV (LPS+ But 0.5 mM) — 0.5 mM aqueous sodium butyrate solution topically, Group V (LPS+ But 1 mM) — 1.0 mM aqueous sodium butyrate solution topically. Clinical scoring of inflammation in rat eyes was evaluated before LPS injection and after 24 hours. The iris involvement, posterior synechiae presence, and insight into the eye fundus were clinicallyassessed. A histopathological examination was also performed. The rats were euthanatized 24 hours after LPS injection, and aqueous humor (AqH) was collected from the eyes by anterior chamber puncture. Levels of inflammatory cytokines and chemokines in the AqH were determined with commercially available Luminex assays. Results: Development of iris hyperemia associated with miosis and poor visibility of fundus details occurred 24 hours after LPS injection. Compared to the LPS+ group, the clinical scores were strongly suppressed in rats treated with Dexamethasone and moderately diminished in LPS+ But 0.5 mM. These clinical features were not observed in the controls (Group 1 — naive). Data from inflammatory cytokines evaluation indicates no significant differences between the LPS+ group (Group 2) and the LPS+ But groups (Groups 4 and 5). Histopathological examinations suggest that hyperemia, corneal stratification, and lesions were less common in the group of animals treated with BA in a lower concentration. Conclusion: Topical administration of sodium butyrate as a therapeutic agent might alleviate the severity of intraocular inflammation in eyes with uveitis. The effect of sodium butyrate was slight but clinically significant in 0.5 mM dose, so other doses of topically administered sodium butyrate should be considered and evaluated in further research