Relationship between microRNA-155, CD4+ regulatory T cells and unstable coronary plaque in patients with coronary artery disease

Objective To investigate the relationship between microRNA-155 (miR-155) and CD4+ regulatory T cells (Treg) and unstable coronary plaque in patients with coronary artery disease. Methods A total of 120 CAD patients with CAD who were hospitalized in the department of cardiology in Guangzhou First People's Hospital from January 2016 to January 2018 were enrolled. All patients underwent coronary angiography and intravascular ultrasound (IVUS) examination. IVUS-virtual histology technique was applied to detect the unstable plague (UP) in patients and direct immunofluorescence method was used to measure the percentage of CD4+ CD25+ Foxp3+ Treg cells in CD4+ Treg cells by flow cytometry. Plasma miR-155 of patients were measured by the methods of quantitative realtime fluorescent Polymerase Chain Reaction (qRT-PCR). Results The levels of plasma miR-155 and CD4+ CD25+ Foxp3+ Treg cells in patients of UP group were significantly lower than patients in stable plague group and control group (0.57±0.10 vs. 0.71±0.09 and 0.83±0.11, P<0.05; 5.92±1.34 vs. 8.05±1.39 and 12.68±1.56, P<0.01). The levels of plasma miR-155 were positively correlated with CD4+ CD25+ Foxp3+ Treg cells in patients of UP group (r=0.476, P=0.013). Multivariate logistic regression analysis showed that plasma miR-155 and CD4+ CD25+ Foxp3+ Treg cells both were strong protective factors for coronary plague in CAD patients (OR=0.662, 95%CI: 0.472-0.819, P=0.011; OR=0.502, 95%CI: 0.376-0.765, P=0.019). Conclusions MiR-155 regulated the expression and function of the CD4+ Treg cells, which may be one important mechanisms in affecting the coronary plaque stability. Key words: MicroRNAs; T-lymphocytes, regulatory; Atherosclerosis; Coronary artery disease