Celastrol inhibits LL37-induced rosacea by inhibiting Ca²⁺/CaMKII-mTOR-NF-κB activation

Rosacea is a common chronic facial inflammatory disease that affects millions of people worldwide. Due to the unclear etiology of rosacea, effective treatments are limited. Celastrol, a plant-derived triterpene, has been reported to alleviate inflammation in various diseases. However, whether celastrol exerts protective effects in rosacea remains to be elucidated. In this study, weighted gene co-expression network analyses (WGCNA) were performed. Hub modules closely related to rosacea clinical characteristics were identified and found to be involved in inflammation- and angiogenesis-related signaling pathways. Then, the pharmacological targets of celastrol were predicted using the TargetNet and Swiss Target Prediction databases. A GO analysis indicated that the biological process regulated by celastrol highly overlapped with the pathogenic biological processes in rosacea. Next, we showed that celastrol ameliorated erythema, skin thickness and inflammatory cell infiltration in the dermis of LL37-treated mice. Celastrol suppressed the expression of rosacea-related inflammatory cytokines and inhibited the Th17 immune response and cutaneous angiogenesis in LL37-induced rosacea-like mice. We further demonstrated that celastrol attenuated LL37-induced inflammation by inhibiting intracellular-free calcium ([Ca²⁺]_i)-mediated mTOR signaling in keratinocytes. Chelating intracellular Ca²⁺ with BAPTA/AM potentiated celastrol-induced repression of LL37-induced p-S6 elevation. The mTOR agonist MHY1485 dramatically reinforced LL37-induced rosacea-like characteristics, while celastrol attenuated these outcomes. Moreover, celastrol inhibited LL37-activated NF-κB in a mTOR signaling-dependent manner. In conclusion, our findings underscore that celastrol may be a rosacea protective agent by inhibiting the LL37-activated Ca²⁺/CaMKII-mTOR-NF-κB pathway associated with skin inflammation disorders.