Abstract Rationale Former smokers with or without chronic obstructive pulmonary disease (COPD) now outnumber current smokers in many developed countries due to public health efforts to reduce tobacco use. While smoking cessation alleviates respiratory symptoms and slows lung function decline, it does not fully reverse lung inflammation and tissue damage in COPD patients. The mechanisms underlying the persistent damaging effects of prior tobacco smoke exposure remain unclear. The goal of our study was to determine whether prior smoking induces metabolic memory, increasing lung susceptibility to viral (e.g., influenza A virus IAV) infection. Specifically, we hypothesized that prior smoking increases the release of IL-33 from human lung epithelial cells, resulting in glycolytic reprogramming and impaired host defense against viruses. Methods Human tracheobronchial epithelial cells (HTBEs) from former smokers, current smokers, and healthy non-smokers were cultured and infected with IAV with or without IL33 decoy receptor soluble ST2 or the LDHA inhibitor GSK2837808A to measure IL-33 release, lactate dehydrogenase A (LDHA), lactate, and viral load. To examine how prior smoking affects airway epithelial cells and lung tissue responses to IAV, smoking cessation models were generated by exposing precision-cut lung slices (PCLS) and HTBEs from healthy non-smokers to cigarette smoke extract (CSE) for 6 consecutive days, followed by 10 days of recovery period before IAV infection. Lung tissues from healthy and COPD donors with a history of prior smoking were used to investigate IL33/lactate pathway changes. Results HTBEs from former smokers showed higher IL-33 release at baseline and after IAV infection. Viral load was higher compared with healthy non-smokers but not compared to current smokers. Similarly, LDHA and lactate were elevated in former smokers’ cells at baseline and after IAV infection. Inhibition of IL-33 signaling by soluble ST2 reduced LDHA expression, lactate levels, and reduced viral load. Likewise, glycolytic inhibition by GSK2837808A reduced lactate production and viral load in former-smoker HTBEs. These findings were reproduced in PCLS and HTBE smoking cessation models. COPD lung tissue with a history of prior smoking showed higher IL-33 and LDHA levels than those of healthy donors. Conclusion Prior smoking promotes epithelial release of IL-33, leading to glycolytic reprogramming and increased susceptibility to viral infection. Targeting the IL-33-lactate signaling pathway in COPD patients who quit smoking may enhance antiviral defense to reduce the severity of viral exacerbations (Figure 1). Acknowledgments: The authors thank BioRender for the figure template and Novogene Corporation for RNA-seq support. ChatGPT was used to improve language and readability. This abstract is funded by: This work was supported by the NIH grants R01 HL144396 and U19AI125357.
Agraval et al. (Fri,) studied this question.