Purpose: Electronic cigarettes (e-cigs) are relatively new devices that allow the user to inhale a heated and aerosolized solution. At present, little is known about their health effects in the human lung, particularly in the small airways (<2 mm in diameter), a key site of airway obstruction and destruction in chronic obstructive pulmonary disease and other acute and chronic lung conditions. The aim of this study was to investigate the effect of e-cigarettes on human distal airway inflammation and remodeling. Methods: We isolated primary small airway epithelial cells from donor lungs without known lung disease. Small airway epithelial cells were cultured at air-liquid interface and exposed to 15 puffs vapor obtained by heating a commercially available e-cigarette solution (e-vapor) with or without nicotine. After 24 hrs of e-vapor exposure, basolateral and apical media as well as cell lysates were collected to measure the pleiotropic cytokine interleukin 6 (IL6) and MUC5AC, one of the major components in mucus. Results: Unlike the nicotine-containing e-vapor, nicotine-free e-vapor significantly increased the amount of IL6, which was coupled with increased levels of intracellular MUC5AC protein. Importantly, a neutralizing IL6 antibody (vs an IgG isotype control) significantly inhibited the production of MUC5AC induced by nicotine-free e-vapor. Conclusion:Our results suggest that human small airway epithelial cells exposed to nicotine-free e-vapor increase the inflammatory response and mucin production, which may contribute to distal lung airflow limitation and airway obstruction.

Rationale Cyclic AMP is generated by adenylyl cyclase to initiate intracellular signaling leading to diverse cellular and tissue responses. Compartmentalization of the cAMP signal within the cellular environment is critical to maintain signaling specificity; however, cAMP is also released into the surrounding extracellular space. Many cell types release extracellular vesicles that encapsulate a variety of functional proteins and RNAs/miRNAs; however, little is known about whether they encapsulate signaling molecules, such as cyclic adenosine monophosphate (cAMP), which could contribute to the extracellular cAMP pool. Methods To test the hypothesis that endothelial cells release extracellular vesicles containing cAMP, media was collected from unstimulated aortic and pulmonary endothelial cells and subject to low‐speed and subsequently high‐speed centrifugation. To determine whether cAMP in these extracellular vesicles increased upon cell stimulation, pulmonary microvascular endothelial cells (PMVEC) were stimulated over time to increase cellular cAMP and extracellular vesicles analyzed for cAMP levels. Finally, isoproterenol and rolipram was perfused through the isolated rat lung to determine whether extracellular vesicles isolated from the intact organ also contain cAMP. Results While cAMP was detected in extracellular vesicles derived from various endothelial cell types, cAMP was higher in PMVECs compared to systemic endothelial cells (aorta) or endothelial cells from pulmonary conduit vessels, pulmonary artery endothelial cells. Further, stimulation of PMVECs with agents that increase near membrane cAMP (isoproterenol or forskolin) in the presence of the phosphodiesterase inhibitor, rolipram, led to an increase in cAMP in extracellular vesicles over time (upto 60 minutes). In PMVECs, cell lysates showed a maximum increase in cAMP 15 minutes after treatment, while the maximum increase in extracellular vesicle‐cAMP was not observed until 60 minutes after treatment. Extracellular vesicles from the perfusate of isoproterenol and rolipram stimulated isolated lungs contained elevated cAMP compared to unstimulated controls. Conclusion Extracellular vesicles released from both the systemic as well as pulmonary vasculature contain cAMP, and cAMP within extracellular vesicles can be increased upon cell stimulation. While cAMP is rapidly packaged into extracellular vesicles within 5‐minute of cell stimulation, the maximal increase is delayed. Isolated lungs can also be stimulated to release extracellular vesicles with increased cAMP. Thus, extracellular cAMP while already accepted to be free in the cytosol is also encapsulated within extracellular vesicles. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A better understanding of the pathogenesis of distinct chronic obstructive pulmonary disease (COPD) phenotypes will improve diagnostic and therapeutic options for this common disease. We present evidence that sphingolipids such as ceramides are involved in the emphysema pathogenesis. Whereas distinct ceramide species cause cell death by apoptosis and necroptosis, cell adaptation leads to accumulation of other sphingolipid metabolites that extend cell survival by triggering autophagy. Cigarette smoke-released sphingolipids have been involved in both the initiation and persistence of lung injury via intracellular signaling and paracrine effects mediated via exosomes and plasma membrane-bound microparticles. Strategies to control sphingolipid metabolite production may promote cellular repair and maintenance to treat COPD.

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