Increased pro-inflammatory activity and impairment of human monocyte differentiation induced by in vitro exposure to cigarette smoke.

Cigarette smoking (CS) is associated with a variety of human pathologies including cardiovascular disease and cancer. Human monocytes are prevalent in oral and respiratory mucosa and may be affected by exposure to CS, which induces oxidative stress. As a result, up-regulation of nuclear factor-kappaB (NF-kappaB) may occur. Our aims were to analyze a possible regulatory effect of CS on NF-kappaB activity in human monocytes. Human monocyte cell lines were exposed to CS in vitro. Our findings show that in vitro exposure to CS did not affect viability of human monocytes and was associated with increased production and secretion of IL-8 and up-regulation of certain C-C chemokines. Inhibition of NF-kappaB with curcumin or parthenolide resulted in a decrease of IL-8 secretion. CS also impaired the differentiation of monocytes. However, induced secretion of IL-8 from differentiated monocytes was not impaired. Our results indicate that exposure to CS stimulates pro-inflammatory activity of human monocytes through the activation of NF-kappaB pathway and also interferes with monocyte differentiation, which could play a role in the carcinogenic effects of cigarette smoking.