MC4R modulates autophagy and pyroptosis regulated by UCP1 in experimental autoimmune uveitis.

OBJECTIVE: To explore melanocortin-4 receptor (MC4R) and uncoupling protein 1 (UCP1) expression and function in autoimmune uveitis (AU) and their regulation of retinal pigment epithelium (RPE) autophagy/pyroptosis, for therapies. METHODS: EAU was induced in female C57BL/6 J mice; eyeballs underwent transcriptome sequencing. Bioinformatics and protein-protein interaction (PPI) network screened differentially expressed genes (DEGs) and core targets. Retinal damage was assessed by hematoxylin and eosin (H&E); cytokines and autophagy/pyroptosis markers by enzyme-linked immunosorbent assay (ELISA), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunofluorescence. In vitro, ARPE-19 cells were lipopolysaccharide (LPS)-stimulated to establish an inflammatory model; cell death/autophagy were evaluated by flow cytometry and monodansylcadaverine (MDC). RNA immunoprecipitation (RIP), co-immunoprecipitation (Co-IP), actinomycin D assays verified the interaction between MC4R and UCP1 and their effect on mRNA stability; small interfering RNA (siRNA) rescue experiments in vivo, in vitro confirmed that UCP1 mediates AU pathology via MC4R. RESULTS: A total of 161 DEGs were identified, with MC4R and UCP1 hub genes aberrantly expressed in EAU tissues and LPS-treated cells. MC4R knockdown reduced clinical scores and inflammatory cell infiltration, and inhibited RPE autophagy/pyroptosis. UCP1 did not directly bind MC4R but indirectly regulated MC4R mRNA stability, downregulating MC4R protein expression. UCP1 knockdown exacerbated pathological retinal damage and RPE autophagy/pyroptosis, reversed by MC4R knockdown. CONCLUSION: Systemic MC4R modulation attenuates retinal inflammatory and histopathological damage in AU, associated with RPE autophagy-pyroptosis activation. UCP1 downregulates MC4R via indirect post-transcriptional regulation of mRNA stability, reversing these processes, offering new insights into the immunometabolic regulatory mechanisms underlying ocular autoimmune diseases.