| First Author | Fleischmann M | Year | 2023 |
| Journal | Am J Physiol Lung Cell Mol Physiol | Volume | 324 |
| Issue | 3 | Pages | L373-L384 |
| PubMed ID | 36719079 | Mgi Jnum | J:336313 |
| Mgi Id | MGI:7439726 | Doi | 10.1152/ajplung.00268.2022 |
| Citation | Fleischmann M, et al. (2023) Cigarette smoke depletes alveolar macrophages and delays clearance of Legionella pneumophila. Am J Physiol Lung Cell Mol Physiol |
| abstractText | Legionella pneumophila is the main aetiological agent of Legionnaires' Disease, a severe bacterial pneumonia. L. pneumophila are initially engulfed by alveolar macrophages (AM) and subvert normal cellular functions to establish a replicative vacuole. Cigarette smokers are particularly susceptible to developing Legionnaires' Disease and other pulmonary infections, however, little is known about the cellular mechanisms underlying this susceptibility. To investigate this, we used a mouse model of acute cigarette smoke exposure to examine the immune response to cigarette smoke and subsequent L. pneumophila infection. Contrary to previous reports, we show that cigarette smoke exposure alone causes a significant depletion of AM using enzymatic digestion to extract cells, or via imaging intact lung lobes by light-sheet microscopy. Further, treatment of mice deficient in specific types of cell death with smoke suggests that NLRP3-driven pyroptosis is a contributor to smoke-induced death of AM. After infection, smoke-exposed mice displayed increased pulmonary L. pneumophila loads and developed more severe disease compared to air-exposed controls. We tested if depletion of AM was related to this phenotype by directly depleting them with clodronate liposomes, and found that this also resulted in increased L. pneumophila loads. In summary, our results showed that cigarette smoke depleted AM from the lung and that this likely contributed to more severe Legionnaires' Disease. Further, the role of AM in L. pneumophila infection is more nuanced than simply providing a replicative niche, and our studies suggest they play a major role in bacterial clearance. |
