Ricerc@Sapienza

Smoking severely impacts the health of worldwide subjects regardless age and race with significant consequences on all National Health Systems. Tobacco incontrovertibly influences heart disease (Robertson JO et al. 2014). The Word Heart Federation¿s report has listed smoking as one of the most important variable to determine the risk of stroke and coronary heart disease by 100% and the risk of death from undiagnosed coronary heart disease by 300% (www.wordl-heartfederation.org). Thus, it is evident that tobacco is also responsible of impaired vascular function and physiological endothelial alterations in smoking subjects.
Tobacco contains huge amounts of harmful and chemical substances exerting a wide array of biological effects on the vasculature. Individuals are differently affected by smoking depending on genetic background, epigenetic asset and additional exogenous environmental factors, which may synergize. So far, the control and the targeting of all biological and physiopathological mechanisms altered by smoking have not been efficiently achieved yet. Thus, the only gold standard solution is still represented by quitting tobacco, meaning that novel strategies are urgently required to stop the long-term consequences especially on the vascular system. To date, biological and molecular targets including reliable biomarkers to detect early changes in the vasculature before developing chronic clinical effects due to smoke, are still to be fully elucidated.
In our preliminary we show for the first time that smoking one single cigarette is sufficient to induce a rapid release of miR-155 in the bloodstream of healthy individuals. We also observed that oxidative stress, which usually increases during cigarette smoking, promotes the release of miR-155 from endothelial cells. In addition, our functional analyses revealed that miR-155 impairs cell viability and angiogenesis, and promotes inflammation in endothelial cells, likely through a reduction of VEGF activity and NO metabolism.
Our data extend previous evidence demonstrating the contribution of miR-155 in vascular pathophysiology, also suggesting a detrimental feedback loop in the endothelium. In this regard, it has been shown that inflammation and oxidative stress increase endothelial miR-155 expression, leading to endothelial dysfunction (Su HX et al. 2012; Liu Y et al. 2015). Inhibition of miR-155 ameliorates endothelium-dependent relaxation (Su HX et al. 2012). Remarkably, eNOS has been demonstrated to be a direct target of miR-155 (Su HX 2012) whereas VEGF to be inversely correlated with miR-155 expression (Liu Q et al. 2015). In addition, data obtained in pre-clinical and clinical studies reported a close association between miR-155 plasma level and the development of CVDs (Weltens et al. 2016; Cao R et al. 2016). For example, circulating miR-155 was suggested to have a prognostic value in patients with myocardial infarction and heart failure (Matsumoto S et al. 2012; Xie W et al. 2014; Ikitimur B et al. 2015; Marques FZ et al. 2016). Nevertheless, conflicting results about miR-155 as a candidate biomarker have been reported in patients affected by coronary artery diseases (Zhu J et al. 2012; Zhu GF et al. 2014).
Previous works attempted to address the impact of cigarette smoking on circulating miRNAs (Banerjee A et al. 2015; Shi B et al. 2016; Takahashi K et al. 2013). These studies demonstrated that smoking exposure induces a significant dysregulation in miRNAs plasma profile either in smokers or in former smokers. Interestingly, most of the deregulated miRNAs have been shown to be associated with smoke related pathologies. Based on the observed detrimental effects of miR-155 on human endothelial cells, we speculate that miR-155 increase after smoking one tobacco cigarette may be a significant acute insult on endothelial cells, supporting a detrimental feedback loop and contributing in the long-term to the development of inflammation and endothelial dysfunction. Future studies are warranted to test this hypothesis. However, the evidence that miR-155 level is associated with the development of CVDs fully supports this view. It will also be interesting to test whether miR-155 could also represent a valid biomarker for the risk stratification of smoker subjects. Thus, our proposal could represent a valid and robust background to evaluate if the release of miR-155 in the bloodstream is chronically correlated with vascular damage in smoker subjects. More importantly, the proposed project will allow the identification of putative miRNA-mediated molecular mechanisms responsible for the early effects of cigarette smoking on the endothelial dysfunction observed after acute cigarette smoke exposure, by also validating the role of circulating miRNA such as miR-155 to act as early biomarker after vascular stress. This will increase knowledge and allow the prediction of molecular damages induced by tobacco smoking in the short term to the vascular system.