Rothia mucilaginosa is an anti-inflammatory bacterium in the respiratory tract of patients with chronic lung disease

Chronic airway inflammation is the main driver of pathogenesis in respiratory diseases, such as severe asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), and bronchiectasis. While the role of common pathogens in airway inflammation is widely recognized, the influence of other microbiota members is still poorly understood. Here, we show that , a common resident of the oral cavity that is also often detectable in the lower airways in chronic disease, has an inhibitory effect on pathogen- and LPS-induced pro-inflammatory responses, both (3-D cell culture model) and (mouse model). Furthermore, in a cohort of adults with bronchiectasis, the abundance of spp. was negatively correlated with pro-inflammatory markers (IL-8, IL-1β) and matrix metalloproteinases (MMP-1, MMP-8 and MMP-9) in sputum. Mechanistic studies revealed that inhibits NF-κB pathway activation by reducing the phosphorylation of IκB-α and consequently the expression of NF-κB target genes. These findings indicate that the presence of in the lower airways potentially mitigates inflammation, which could in turn influence severity and progression of chronic respiratory disorders.