Comparative effects between electronic and cigarette smoke in human keratinocytes and epithelial lung cells

Abstract

Information about the harmful effects of vaping is sparse and inconsistent, therefore, since the use of electronic cigarettes (e-CIGs) has become increasingly popular as a tool to limit tobacco smoking, it is urgent to establish the toxicity of the commercial e-CIGs. Skin (HaCaT) and lung (A549) cells, the main targets of cigarette smoke (CS), were exposed to e-CIG vapor and CS using an in vitro system. The cytotoxic effect of the exposure was analyzed in both cell types by ultrastructural morphology, Trypan Blue exclusion test and LDH assay. In addition, pro-inflammatory cytokines were measured by the Bio-Plex assay. The cytotoxic components of e-CIG were restrained to the flavoring compound and, to a lesser extent, to nicotine although their effects were less harmful to that of CS. Humectants alone exhibited no cytotoxicity but induced the release of cytokines and pro-inflammatory mediators. Based on our results, we can state that exposure to e-CIG vapors results in far less toxic than exposure to CS. In fact, besides the deleterious effect of flavor and nicotine, even the humectants alone are able to evocate cytokines release. This study will hopefully promote the development of safer e-CIGs to help people quit smoking.

Keywords: Cytokines release; Cytotoxicity; Skin and lung cells; Tobacco cigarette smoke; e-CIG vapor.

Figure 1

Cytotoxicity measured as LDH release in HaCaT cells after exposure to air (A), cigarette smoke (B), electronic cigarette with nicotine (C), electronic cigarette with flavor (D) and only vaping (E). Triton X represent 100% of LDH release. Data are expressed as percentage of control (averages of five different experiments), *p < 0.05).

Figure 2

Cytotoxicity measured as LDH release in A549 cells after exposure to air (A), cigarette smoke (B), electronic cigarette with nicotine (C), electronic cigarette with flavor (D) and only vaping (E). Triton X represent 100% of LDH release. Data are expressed as percentage of control (averages of five different experiments), *p < 0.05).

Figure 3

Cell viability in HaCaT cells after exposure to air (A), cigarette smoke (B), electronic cigarette with nicotine (C), electronic cigarette with flavor (D) and only vaping (E). Data are expressed as percentage of control (averages of five different experiments), *p < 0.05).

Figure 4

Cell viability in A549 cells after exposure to air (A), cigarette smoke (B), electronic cigarette with nicotine (C), electronic cigarette with flavor (D) and only vaping (E). Data are expressed as percentage of control (averages of five different experiments), *p < 0.05).

Figure 5

Ultrastructural study of A549 cells (left column) and HaCaT cells (right column) after exposure to different conditions at T0 (immediately after the exposure) and T24 (24 hr after the exposure. Bars = 2 μm.