Methanogenic archaea bolster mucosal homeostasis and protect from colitis

The intestinal microbiota profoundly shapes host homeostasis and disease, yet the role of Archaea, which comprise ∼10% of the anaerobic gut microbiota, is poorly understood. Here, we find that colonization of germ-free or conventional mice with the human methanogens <i>Methanobrevibacter smithii</i> (MSm) or <i>Methanosphaera stadtmanae</i> (MSt) enhances epithelial regeneration, mucus production, and regulatory T cell accumulation. These methanogens protect against chemically induced colitis, demonstrating a direct and beneficial role for Archaea in maintaining colonic health.