Evaluation of Cytotoxic, Oxidative, and Pro-Inflammatory Effects of Aqueous Cigarette Smoke Extract on Human Monocytes: A Potential Model System for Assessment of Next-Generation Tobacco and Nicotine Products

Abstract

Tobacco smoking is a risk factor for the development of atherosclerosis. One strategy to reduce the harmful side effects of tobacco smoking is the development of next-generation tobacco and nicotine products. A crucial step in the development of atherosclerosis is the activation and adhesion of monocytes. Remarkably, little is known about the direct effects of cigarette smoking on monocytes. In this study, we developed methods to determine the detrimental effects of aqueous cigarette smoke extract (CSEaq) from 3R4F reference cigarettes on human monocytes in vitro. First, we tested the cytotoxic effects of CSEaq on human peripheral blood monocyte cell line derived from an acute monocytic leukemia patient (THP-1) and primary monocytes. Treatment of THP-1 cells with CSEaq reduced cell viability at dosages ‡40% in a dose-dependent manner. Cell viability of primary monocytes was reduced by CSEaq at dosages ‡10%. CSEaq activated the antioxidative NRF2 system and its target gene NAD(P)H dehydrogenase, quinone 1 in a dose-dependent manner in both cell types. Expression of target gene HMOX1 was increased only in THP-1 cells. In addition, we showed an increased expression of NADPH oxidase subunit NOX2 in response to CSEaq in THP-1 cells, but not in primary monocytes. Furthermore, CSEaq strongly induced adhesion molecule intercellular adhesion molecule 1 in THP-1 cells, but not in primary monocytes. Pro-inflammatory markers CCL2 and CD31 showed a strong induction in response to CSEaq in THP-1 cells, but they remained unchanged in primary monocytes. In conclusion, we have developed in vitro test systems allowing the evaluation of cytotoxic, oxidative, and pro-inflammatory effects of CSEaq on monocytes. These test systems can be considered potential model systems for assessment of next-generation tobacco and nicotine products. Although THP-1 cells were more susceptible to changes of gene expression, primary monocytes showed a stronger reduction of cell viability in response to CSEaq.

Comparative study of the effects of cigarette smoke versus next-generation tobacco and nicotine product extracts on inflammatory biomarkers of human monocytes

“…Several studies indicated an atherosclerosis-related gene expression profile of endothelial cells as well as of monocytes in the presence of the main behavioural risk factor smoking [ 3 , 34 , 41 , 73 , 77 ]. Independent stimulation with aqueous smoke extract (AqE) of conventional reference cigarettes (3R4F) revealed cytotoxic, oxidative, and pro-inflammatory effects on monocytes, shown in an own previous study [ 9 ].…”

Detection of Vascular Inflammation and Oxidative Stress by Cotinine in Smokers: Measured Through Interleukin-6 and Superoxide Dismutase

“…These factors were related to oxidative stress and inflammation mechanisms, especially cigarette smoke, which plays a significant role in CVD development. 3–6 …”

“…These factors were related to oxidative stress and inflammation mechanisms, especially cigarette smoke, which plays a significant role in CVD development. [3][4][5][6] Smoking behaviour is a common habit in many countries. Indonesia is ranked third with the highest number of smokers in the world (9.91 million), after China (26.5 million) and India (19.8 million).…”

In vitro biological assessment of the stability of cigarette smoke aqueous aerosol extracts

“…A cigarette smoke aqueous test matrix consists of one or more cigarettes smoked into a specified volume of solution and the resulting aqueous soluble fraction of the cigarette smoke (AqE) is diluted and applied to the cell surface. Studies have used multiple methods not fully described to allow replication [ 7 , 10 , 12 , 13 ]. For instance, the puffing regime is not always specified, the capture solutions (e.g.…”

“…Smoke-induced oxidative stress has been linked to chronic obstructive pulmonary disease [ 13 , 17 , 23 ] associated with impaired antioxidant defences and characterised by an accumulation of oxidised glutathione in the lungs of smokers. In this study, the effects of pro-oxidant smoke-derived chemicals in cigarette smoke (partitioned between the particulate and vapour phase) were investigated by use of AqE.…”