polyA+ RNA sequencing on FACS sorted alveolar macrophages (CD45+SiglecF+CD11c+) from air and cigarette-smoke exposed wild type and miR-155 KO mice

Chronic obstructive pulmonary disease (COPD) is a highly prevalent respiratory disease characterized by airflow limitation and chronic inflammation. MiR-155 is described as an ancient regulator of the immune system. Our objective was to establish a role for miR-155 in cigarette smoke (CS)-induced inflammation and COPD. We demonstrate increased miR-155 expression by RT-qPCR in lung tissue of smokers without airflow limitation and patients with COPD compared to never smokers and in lung tissue and alveolar macrophages of CS-exposed mice compared to air-exposed mice. In addition, we exposed wild type and miR-155 deficient mice to CS and show an attenuated inflammatory profile in the latter. Alveolar macrophages were sorted by FACS from the different experimental groups and their gene expression profile was analyzed by RNA sequencing. This analysis revealed increased expression of miR-155 targets (including the NF-κB inhibitor rassf6) and an attenuation of the CS-induced increase in inflammation-related genes in miR-155 deficient mice. Finally, intranasal instillation of a specific miR-155 inhibitor significantly attenuated the CS-induced pulmonary inflammation in mice. In conclusion, we highlight a role for miR-155 in CS-induced inflammation and the pathogenesis of COPD, implicating miR-155 as a new therapeutic target in COPD. poly-A+ RNA sequencing was performed on 5 mice per group (4 groups: air_wild-type, air_miR-155-KO, CS_wild-type, CS_miR-155-KO)