Phagocytosis and Inflammation: Exploring the effects of the components of E-cigarette vapor on macrophages

Abstract

E‐cigarettes are perceived as harmless; however, evidence of their safety is lacking. New data suggests E‐cigarettes discharge a range of compounds capable of physiological damage to users. We previously established that cigarette smoke caused defective alveolar macrophage phagocytosis. The present study compared the effect E‐cigarette of components; E‐liquid flavors, nicotine, vegetable glycerine, and propylene glycol on phagocytosis, proinflammatory cytokine secretion, and phagocytic recognition molecule expression using differentiated THP‐1 macrophages. Similar to CSE, phagocytosis of NTHi bacteria was significantly decreased by E‐liquid flavoring (11.65–15.75%) versus control (27.01%). Nicotine also decreased phagocytosis (15.26%). E‐liquid, nicotine, and E‐liquid+ nicotine reduced phagocytic recognition molecules; SR‐A1 and TLR‐2. IL‐8 secretion increased with flavor and nicotine, while TNF α, IL‐1β, IL‐6, MIP‐1α, MIP‐1β, and MCP‐1 decreased after exposure to most flavors and nicotine. PG, VG, or PG:VG mix also induced a decrease in MIP‐1α and MIP‐1β. We conclude that E‐cigarettes can cause macrophage phagocytic dysfunction, expression of phagocytic recognition receptors and cytokine secretion pathways. As such, E‐cigarettes should be treated with caution by users, especially those who are nonsmokers.

E-cigarettes: Effects in phagocytosis and cytokines response against Mycobacterium tuberculosis

“…The results found in literature, regarding the cytotoxicity of e-vapor extract flavored are contradictory; some studies have shown a cytotoxic effect when tobacco, cherry, cinnamon and coffee flavors were tested [32,[40][41][42]. However, in agreement with our results, Ween et al observed that cytotoxicity in THP-1 macrophages was not related with the e-cig flavor [26]. It has been suggested that cell line used, nicotine, flavors, PG/PV ratio, voltage and potency of the device can influence in the toxicity effects of e-vapor [43].…”

“…Coffee flavor was chosen because of the toxic effect observed in fibroblasts [32]. 60 mL of evapor was extracted for 3 sec, after which a 30 sec break followed; the process was repeated 40 times (average of puffs found in literature), in 10 mL of RPMI medium or 7H9-tween [21,26]. The e-vapor extract was also sterilized using a 0.22 μm filter.…”

“…The e-vapor extract was also sterilized using a 0.22 μm filter. Like for CS extract, fresh extract was used and added to cultures within 30 min of preparation at 100% concentration according to literature [21,26].…”

“…We evaluated if the concentrations found in literature: 10% CS extract and 100% e-vapor extract were nontoxic in THP-1 macrophages [21,26]. The macrophages were exposed to evapor or CS extracts for 6 days and the cell viability was assessed using the formazan-based cell proliferation assay EZ4U at days 0, 3 and 6.…”

“…Although the percentage of toxic compounds found in e-cig vapor (e-vapor) are lower than cigarette smoke [17], some studies have shown a toxic effect on cells like alveolar macrophages [18], lung epithelial cells [19][20][21][22] and monocytic cells [23] as well as proteomic changes in the cells of the lower airways [24] and pro-inflammatory response [19,21,23,25]. Moreover, function damage in macrophages has been observed and therefore an enhancement of infections caused by microorganisms such as Haemophilus influenzae [26], Escherichia coli [18], Staphylococcus aureus [18,21] and Streptococcus pneumoniae [27]. In addition, it has been shown that e-cigs promote influenza A virus infection in mice [27].…”