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?
1 Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, School of Pharmacy, 1300 S. Coulter Street, Amarillo TX 79106, USA
2 Center for Blood Brain Barrier Research, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
3 Department of Biomedical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
4 Weill Cornell Medical College, New York, NY, USA
5 Inserm, U1016, Institut Cochin, Paris, France
6 CNRS, UMR8104, Paris, France
7 Université Paris Descartes, Sorbonne Paris Cité, Paris, France
8 Department of Life, Health and Chemical Sciences, Open University, Milton Keynes, UK
BMC Neuroscience 2014, 15:51 doi:10.1186/1471-2202-15-51Published: 23 April 2014
Both 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.
Initial 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.
In 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.