Oxidative and pro-inflammatory impact of regular and denicotinized cigarettes on blood brain barrier endothelial cells: is smoking reduced or nicotine-free products really safe?

Abstract

BackgroundBoth active and passive tobacco smoke (TS) potentially impair the vascular endothelial function in a causative and dose-dependent manner, largely related to the content of reactive oxygen species (ROS), nicotine, and pro-inflammatory activity. Together these factors can compromise the restrictive properties of the blood–brain barrier (BBB) and trigger the pathogenesis/progression of several neurological disorders including silent cerebral infarction, stroke, multiple sclerosis and Alzheimer’s disease. Based on these premises, we analyzed and assessed the toxic impact of smoke extract from a range of tobacco products (with varying levels of nicotine) on brain microvascular endothelial cell line (hCMEC/D3), a well characterized human BBB model.ResultsInitial profiling of TS showed a significant release of reactive oxygen (ROS) and reactive nitrogen species (RNS) in full flavor, nicotine-free (NF, “reduced-exposure” brand) and ultralow nicotine products. This release correlated with increased oxidative cell damage. In parallel, membrane expression of endothelial tight junction proteins ZO-1 and occludin were significantly down-regulated suggesting the impairment of barrier function. Expression of VE-cadherin and claudin-5 were also increased by the ultralow or nicotine free tobacco smoke extract. TS extract from these cigarettes also induced an inflammatory response in BBB ECs as demonstrated by increased IL-6 and MMP-2 levels and up-regulation of vascular adhesion molecules, such as VCAM-1 and PECAM-1.ConclusionsIn summary, our results indicate that NF and ultralow nicotine cigarettes are potentially more harmful to the BBB endothelium than regular tobacco products. In addition, this study demonstrates that the TS-induced toxicity at BBB ECs is strongly correlated to the TAR and NO levels in the cigarettes rather than the nicotine content.

Drugs of abuse and blood-brain barrier endothelial dysfunction: A focus on the role of oxidative stress

“…21 For example, using static or flow-based in vitro BBB models, we previously demonstrated a marked increase in intracellular ROS/RNS and secretory profile of various pro-inflammatory markers accompanied by alterations in BBB TJ protein expression and re-distribution following TS exposure. 43,114 In addition, DNA microarray-based global transcriptome profiling indicated a rapid and transient up-regulation of Nrf2 and its downstream anti-oxidant molecular networks in response to prolonged TS exposure in brain microvascular endothelial cultures. 115 Interestingly, anti-oxidant supplementation toned down TS-induced oxidative stress thus preventing BBB damage.…”

“…[37][38][39] Brain microvascular endothelial cells are highly sensitive to imbalance in redox homeostasis [40][41][42] and increased endothelial oxidative stress significantly compromises the stringency of BBB with marked reduction in the immunological privilege of CNS. 28,[43][44][45] To this end, compelling evidence suggests that psychostimulants as well as tobacco smoking could have profound pro-oxidant effects and significantly activate endothelial oxidative stress responses, thus, leading to a compromised BBB integrity.…”

“…Interestingly, our data revealed a potential oxidative/inflammatory stress response at the BBB endothelium (affecting the Nrf2 antioxidant response system 115 ) by low-nicotine and high tar-containing cigarettes higher than or comparable to conventional cigarettes. 43 Therefore, rigorous analysis of the safety (or toxicity) profiles of various tobacco products on cerebrovascular function in experimental and clinical studies is critically needed for the regulatory control of these new smoking alternatives.…”

The correlation between pH and flow rate of salivary smokers related to nicotine levels labelled on cigarettes

“…6 Nicotine in cigarette smoke will be absorbed through the lungs and mucous membranes, then circulated through the bloodstream, and distributed to the brain and tissue in all organs of the body. 7 Nicotine circulating to the bloodstream can affect the blood vascularization to the salivary glands, resulting in decreased function and morphology of glandula. 8 Nicotine even reaches the brain within 10-20 seconds.…”

Crosstalk Between Co-cultured A549 Cells and THP1 Cells Exposed to Cigarette Smoke

“…Cells were kept in co-culture in cigarette smoke-free medium for 24 h *p < 0.05; **p < 0.01 for comparisons with the corresponding control cells ## p < 0.01 for comparisons with the CS-treated cells ++ p < 0.01 for comparisons with A549 + THP1 group^p < 0.01 for comparisons with A549 CS + THP1 group depending on experimental systems and smoke exposure, but it has been reported that CS extract dose-dependently decreases glutathione concentration, increases 4-hydroxy-2-nonenal levels, and induces necrosis in A549 cells (Kode et al 2006). In our experimental model, cell exposure to CS was rather extensive and nitrate/ nitrite levels in smoke-conditioned media were relatively high comparing to other models (Naik et al 2014). Nonetheless, our smoke-conditioned medium was not toxic to the monocyte cell line, which apparently is more resistant to noxious compounds of CS.…”