Intracellular and Extracellular Cytokines in A549 Cells and THP1 Cells Exposed to Cigarette Smoke

Cigarette smoke (CS) activates inflammatory cells and increases cytokine levels producing local and systemic inflammation. To assess changes in intracellular and extracellular cytokine levels we used human epithelial (A549 cells) and monocyte (THP-1) cell lines grown for 24 h in cigarette smoke-conditioned media. Cytokines were assessed using immunostaining/flow cytometry and ELISA assay. In THP1cells, grown in CS-conditioned media, the intracellular interleukins IL-1β, IL-6, and IL-10 increased by more than tenfold, while less significant increases were found in A549 cells. IL-1α and IL-1β, but not IL-6 or IL-10, were increased in the culture media, while IL-2 was raised by about fivefold only in the culture medium of A549 cells. IL-4, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor alpha were undetectable, while only a slight increase was observed in extracellular IL-17A (by about 60 %) in the medium of A549 cells and by about 115 % in the medium of THP1 cells. The interferon gamma (IFNγ) was increased by about eightfold, but only in the medium of THP1 cells grown with CS. We conclude that IL-1 and INFγ are the key cytokines responsible for pro-inflammatory signaling in epithelial cells and monocytes, respectively, exposed to cigarette smoke.