Bacteroides-derived endocannabinoid-like commendamide attenuates skeletal muscle ferroptosis in vitro: implications for Duchenne muscular dystrophy

The gut microbiota regulates skeletal muscle physiology, with an increasingly recognised role in Duchenne muscular dystrophy (DMD), the most severe X-linked myopathy. Unlike previous studies, we focussed on the genus Bacteroides and its metabolites, assessing their abundance in DMD mice and patients to clarify their potential contribution to the disease. The relative abundance of Bacteroides species was analysed in fecal samples from dystrophic mdx mice and DMD patients, compared with age-matched healthy controls, using PCR-based tecniques. Synthetic and analitical chemistry approaches followed by cell-based assays, in silico and bioinformatic analyses, were employed to identify an unknown mechanism of action of the Bacteroides- derived metabolites. DMD patients and mdx mice exhibited a significant reduction in commensal Bacteroides species, including Bacteroides vulgatus , known producers of SCFAs and commendamide, an endocannabinoid-like molecule with largely uncharacterized biological functions. In skeletal muscles of mdx mice, we observed biochemical features consistent with increased susceptibility to ferroptosis. In murine C2C12 cells and primary human myotubes exposed to the ferroptosis inducer erastin, commendamide conferred significant protective effects, which were further enhanced in the presence of SCFAs. Additionally, we discovered that commendamide acts as an endogenous activator of PPARα and PPARγ, with PPARα preferentially promoting the transcription of the antioxidant genes Gpx4 and Nrf2 . These findings provide new insights into the gut–muscle axis in DMD, suggesting that the depletion of Bacteroides vulgatus and its metabolites may contribute to skeletal muscle degeneration. In vitro evidence demonstrates that commendamide, through PPARα signaling; and SCFAs, enhances antioxidant mechanisms. Overall, these results support further investigation of microbiota-derived metabolites as postbiotic candidates for DMD therapy.