The microbiome and a frontline innate antimicrobial sensor, Toll-like receptor 5 (TLR5), play an essential role in the development of idiopathic pulmonary fibrosis (IPF). A scientific collaboration led by researchers at the National Institute of Environmental Health Sciences has revealed how TLR5 protects against fibrosis through its ability to modulate the lung microbiome. Their study also shows that activating TLR5 protects against fibrosis and corrects pulmonary dysbiosis.