Persistence of Emphysema Following Cessation of Cigarette Smoke Exposure Requires a Susceptibility Factor

Am J Physiol Lung Cell Mol Physiol. 2024 Feb 13. doi: 10.1152/ajplung.00342.2023. Online ahead of print.ABSTRACTChronic obstructive pulmonary disease (COPD) is caused by cigarette smoke (CS) exposure but can be often progressive even in former smokers. Exposure of mice to CS for 22 weeks causes emphysema, but whether emphysema persists after cessation of CS exposure is not clear. The purpose of this study was to determine whether emphysema persists in mice following a recovery period of 22 wks and whether a susceptibility factor, such as deficiency in the Bcl-2-interacting killer (Bik), is required for this persistence. Therefore, bik+/+ and bik-/- mice at 6-10 wk of age were exposed to 250 mg/m3 total particulate matter of CS or filtered air (FA) for 3 or 22 wks and were kept in FA for an additional 22 wks. Lungs were lavaged to quantify inflammatory cells and sections stained with hematoxylin and eosin to assess severity of emphysema. Exposure to CS for 3 wks increased the number of inflammatory cells in bik-/- compared with bik+/+ mice but not at 22 wks of exposure. At 22 wks of CS exposure, extent of emphysema was similar in bik+/+ and bik-/- mice. However, when mice were exposed to CS over the first 22 wks and were kept in FA for an additional 22 wks, emphysema remained similar in bik+/+ but was enhanced in bik-/- mice. These findings link increased inflammation with persistent emphysematous changes even after smoking cessation and demonstrate that a pre-existing suscept...
Source: American Journal of Physiology. Lung Cellular and Molecular Physiology - Category: Cytology Authors: Source Type: research