Effect of PM2.5 on circulating inflammatory cells and microRNA expression in acute coronary syndrome

Background Air pollutants increase the risk of myocardial infarction. Air pollution-induced atherosclerotic plaque destabilization may be related to inflammation, but the specific inflammatory alterations remain unclear. Purpose The aim of this prospective study was to assess the inflammatory changes in circulating immune cells and microRNAs in patients with acute coronary syndrome related to short-term exposure to PM2.5. Methods We prospectively included all consecutive patients admitted between March 2017 and July 2018 with the diagnosis of acute coronary syndrome (STEMI, NSTEMI, unstable angina) and coronary angiography in the acute phase of the disease. We also included a control group of patients with stable angina. For each patient we collected air concentrations of PM2.5 from the closest meteorological station to the patient residence obtaining the previous 24-hour average before hospital admission. All patients underwent systematic circulating inflammatory cell analysis. A selection of patients underwent miRNAs analysis. Results A total of 261 patients were included. According to PM2.5 exposure, 31 patients were selected for miRNA analyses. STEMI patients exposed to PM2.5 showed a reduction of CD4+ regulatory T (Treg) cells (Figure 1A). In the microRNA assessment, PM2.5 exposure was associated with higher circulating levels of let-7f-5p, miR-223-3p, miR-423-3p, miR-197-3p, miR-335–5, miR-376c-3p and miR-501-3p. Regarding clinical presentation, PM2.5 exposure in STEMI and NSTEMI patients was associated with an increase of miR-let-7f-5p, whereas miR-423-3p and miR-146a-5p were increased only in STEMI patients (Figure 1B). Conclusions STEMI related to PM2.5 short-term exposure is associated to specific changes involving CD4+CD25+Foxp3+ Treg cells and miR-146a-5p. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Ministerio de Ciencia e Innovaciόn; Fundaciόn BBVA Equipos de Investigaciόn Científica 2018 and from Caixa Banking Foundation; Sociedad Espanola de Cardiologia; Ministerio de Ciencia, Innovaciόn y Universidades, Carlos III Institute of Health-Fondo de Investigaciόn Sanitaria; Comunidad de Madrid; Fondo Europeo de Desarrollo Regional