Cigarette smoke condensate attenuates phorbol ester-mediated neutrophil extracellular trap formation

Abstract

BackgroundNeutrophil extracellular traps (NETs) constitute a network of chromatin fibres containing histone and antimicrobial peptides that are released by activated neutrophils. NETs protect the host against infection by trapping and facilitating phagocytosis of potentially harmful pathogens.ObjectivesThe aim of the current study was to investigate the effects of cigarette smoke condensate (CSC) on phorbol-ester (PMA)-mediated NETosis in vitro.MethodsIsolated human blood neutrophils were exposed to PMA (6.25 ng/ml) in the presence or absence of CSC (40–80 µg/ml) for 90 min at 37oC. NET formation was measured using a spectrofluorimetric procedure to detect extracellular DNA and fluorescence microscopy was used to visualize nets. Oxygen consumption by PMA-activated neutrophils was measured using an oxygen sensitive electrode.ResultsActivation of neutrophils with PMA was associated with induction of NETosis that was significantly attenuated in the presence of CSC (40 and 80 µg/ml), with mean fluorescence intensities of 65% and 66% of that observed with untreated cells, respectively, and confirmed by fluorescence microscopy. The rate and magnitude of oxygen consumption by activated neutrophils pre-treated with CSC (80 µg/ml) was significantly less than that observed with untreated cells (73% of the control system), indicative of decreased production of reactive oxidants in the presence of CSC.ConclusionThe inhibition of NETosis observed in the presence of CSC correlated with attenuation of oxygen consumption by PMA-activated neutrophils suggesting a mechanistic relationship between these events. If operative in vivo, smoking-related attenuation of NETosis may impair host immune responses and increase the risk of respiratory infections.

Impact of Cigarette Smoking on the Gastrointestinal Tract Inflammation: Opposing Effects in Crohn’s Disease and Ulcerative Colitis

“…In the presence of CSC, neutrophils showed an inhibition of NETosis that correlated with an attenuation of oxygen consumption, suggesting a mechanistic relationship between these events. If operative in vivo , attenuation of NETosis due to cigarette smoke may impair host immune responses and increase the risk of respiratory tract infections ( 66 ). These impairments in the innate immune response can in turn cause an ineffective adaptive immune response.…”

A perspective on NETosis in diabetes and periodontal diseases

“…With cigarette smoke condensate (CSC), there was a dose-dependent reduction in the formation of NETs in peripheral blood from smokers. [ 21 ] It may be due to the inhibition of NADPH activation by CSC. Although it is said that nicotine is a potent inducer of NET formation,[ 22 ] CSC and cigarette smoke contain various components other than nicotine which may have an adverse effect in NET production.…”

Editorial: Sexuality, mother-child health and infectious diseases

“…One is on factors associated with tobacco smoking behavior among long distance drivers in Lagos, 31 while the other reports that cigarette smoke condensate attenuates phobol ester-mediated neutrophil extracellular trap formation. 32 …”