TLR4 and lung disorder: In both upper airway and acellular bronchoalveolar lavage samples from participants without known pulmonary diseases, Segal et al. observed that enriched Veillonella and Prevotella were associated with the enhanced expression of Th-17 lymphocyte–derived inflammatory cytokines, and conversely, a blunted alveolar macrophage TLR4 response (Segal et al., 2016).