Short chain fatty acids inhibit endotoxin-induced uveitis and inflammatory responses of retinal astrocytes.

Short chain fatty acids (SCFAs) are produced by gut microbiota as fermentation products of digestion-resistant oligosaccharides and fibers. Their primary roles are functioning as major energy sources for colon cells and assisting in gut homeostasis by immunomodulation. Recent evidence suggests that they affect various organs both at cellular and molecular levels, and regulate functions in distance sites including gene expression, cell proliferation, cell differentiation, apoptosis and inflammation. In this study, we examined whether SCFAs are present in the mouse eye and whether SCFAs affect inflammatory responses of the eye and retinal astrocytes (RACs). We observed that intra-peritoneal injected SCFAs were detected in the eye and reduced intraocular inflammation induced by lipopolysaccharide (LPS). Moreover, SCFAs displayed two disparate effects on LPS-stimulated RACs - namely, cytokine and chemokine production was reduced, but the ability to activate T cells was enhanced. Our results support the existence of gut-eye cross talk and suggest that SCFAs can cross the blood-eye-barrier via the systemic circulation. If applied at high concentrations, SCFAs may reduce inflammation and impact cellular functions in the intraocular milieu.