Poon J, et al. - Given that lung injury and airway hypersensitivity were enhanced by subduing leukemia inhibitory factor (LIF) signaling in a murine model that demonstrated increased LIF expression in the lungs during respiratory syncytial virus (RSV) infection, and frequent detection of RSV in the respiratory tract of chronic obstructive pulmonary disease (COPD) patients during an exacerbation, researchers focused on the influence of disease status and cigarette smoke exposure on LIF expression in COPD patients. Both smokers and COPD patients showed significantly attenuated LIF protein in bronchoalveolar lavage fluid, compared to healthy never smokers. During RSV infection or poly (i:c) stimulation, less LIF was produced by human bronchial epithelial cells isolated from COPD patients vs never smokers. In lungs, attenuated levels of LIF and its corresponding receptor, LIFR, were detected in animals exposed to cigarette smoke. LIF expression in the lungs was significantly modulated by cigarette smoke. A possible contribution of loss of LIF expression in COPD to a higher degree of lung injury during virus-related exacerbations was suggested in this study.