Gut microbiota mediates the anti-inflammatory effects of supplemental infrared irradiation in mice.

In recent years, studies have shown that low-dose supplemental infrared (IR) irradiation exhibits systemic anti-inflammatory effects. The gut microbiota is increasingly recognized as a potential mediator of these effects due to its role in regulating host metabolism and inflammatory responses. To investigate the role of gut microbiota diversity and metabolite changes in the mechanism of light-emitting diodes (LED) infrared's anti-inflammatory action, we conducted IR irradiation on mice. Serum inflammatory cytokines were measured using ELISA, and fecal samples were subjected to metagenomic, untargeted, and targeted metabolomic analyses. Our results demonstrated a significant increase in the anti-inflammatory cytokine IL-10 in the IR group, accompanied by a declining trend in pro-inflammatory cytokines. Gut microbiome analysis revealed distinct alterations in composition and functional genes between the groups, including the enrichment of beneficial bacteria like various species of Parabacteroides and Akkermansia muciniphila in the IR group. Notably, the IR group exhibited enrichment in carbohydrate metabolism pathways and a reduction in DNA damage and repair pathways. Furthermore, targeted metabolomic analysis highlighted a notable increase in short-chain fatty acids (SCFAs), including butyric acid and isobutyric acid, which positively correlated with the abundance of several beneficial bacteria. These findings suggest a potential interplay between gut microbiota-derived SCFAs and the anti-inflammatory response. In conclusion, our study provides comprehensive insights into the changes in gut microbiota species and functions associated with IR irradiation. Moreover, we emphasize the significance of altered SCFAs levels in the IR group, which may contribute to the observed anti-inflammatory effects. Our findings contribute valuable evidence supporting the role of low-dose infrared light irradiation as an anti-inflammatory therapy.