6-Shogaol Alleviates Endotoxin-Induced Uveitis via Activation of HIF-1α to Regulate Inflammatory Responses and Endoplasmic Reticulum Stress.

PURPOSE: 6-Shogaol (6-S) has demonstrated anti-inflammatory effects in various disease models; however, its effects in uveitis have not been investigated. This research intends to investigate the therapeutic mechanisms of 6-S in acute uveitis. METHODS: An endotoxin-induced uveitis (EIU) mouse model was developed to assess the therapeutic potential of 6-S for uveitis. Disease severity was evaluated through anterior segment evaluation, clinical scoring, and pathology staining. RNA sequencing (RNA-seq) and network pharmacology explored the potential molecular mechanisms. In vitro, BV2 cells were stimulated by lipopolysaccharide. The mRNA and protein levels of pro-inflammatory cytokines, endoplasmic reticulum (ER) stress markers, and hypoxia-inducible factor 1-alpha (HIF-1α) in eyeballs and cells were detected. Transmission electron microscopy and Ca2+ levels were used to evaluate ER damage. The targeting effect of 6-S on HIF-1α was tested by HIF-1α siRNA. RESULTS: 6-S alleviated EIU in mice. RNA-seq indicated that inflammatory pathways are potential mechanisms of 6-S treatment. Further results showed that 6-S inhibited the expression of pro-inflammatory cytokines in vivo and in vitro. Network pharmacology revealed that the effect of 6-S may related to the ER. 6-S downregulated GRP78, ATF4, and CHOP expression; suppressed PERK and IRE1α phosphorylation; and mitigated ER swelling and cellular Ca2+ overload. Moreover, 6-S upregulated the expression of HIF-1α in vivo and in vitro. Inhibiting HIF-1α largely eliminated the anti-inflammatory and relieving ER stress properties of 6-S. CONCLUSIONS: 6-S alleviates ER stress and inflammatory responses by modulating the expression of HIF-1α, thereby improving the prognosis of EIU.