Dysbiotic microbiomes in IL-17-deficient mice induced hyperacute GVHD, and antibiotic-mediated bacterial depletion prevented lethal aGVHD by inhibiting MHCII expression upregulation on intestinal epithelial cells [33]. Graft-versus-host disease-mediated tissue damage, including Paneth cell destruction, further propagates pathogenic bacterial expansion, accelerating GVHD [33]. The gene discussed is IL17A; the disease is graft versus host disease.