Monocyte CD40 expression in young healthy female smokers and/or oral contraceptives users without additional risk factors for atherosclerosis

MiR-145-5p regulates hypoxia-induced inflammatory response and apoptosis in cardiomyocytes by targeting CD40

An increasing body of evidence indicates that inflammation and apoptosis are involved in the development of acute myocardial infarction (AMI). In this study, we sought to investigate the specific role and the underlying regulatory mechanism of miR-145-5p in myocardial ischemic injury. H9c2 cardiac cells were exposed to hypoxia to establish a model of myocardial hypoxic/ischemic injury. We found that miR-145-5p was notably down-regulated, while CD40 expression was highly elevated in H9c2 cells following exposure to acute hypoxia. Additionally, hypoxia markedly enhanced the inflammatory response, as reflected by an increase in the secretion of the cytokines IL-1β, TNF-α, and IL-6, whereas the introduction of miR-145-5p effectively suppressed inflammatory factor production triggered by hypoxia. Furthermore, we observed hypoxia stimulation significantly augmented apoptosis accompanied by a decrease in the expression of Bcl-2 and an increase in the expression of Bax, Caspase-3, and Caspase-9. However, augmentation of miR-145-5p led to a dramatic prevention of hypoxia-induced apoptosis. Importantly, we identified CD40 as a direct target of miR-145-5p. Interestingly, the depletion of CD40 with small interfering RNAs (siRNAs) apparently repressed the production of inflammatory cytokines and apoptosis in the setting of acute hypoxic treated. Taken together, these data demonstrated that miR-145-5p may function as a cardiac-protective molecule in myocardial ischemic injury by ameliorating inflammation and apoptosis via negative regulation of CD40. The study gives evidence that miR-145-5p provides an interesting strategy for protecting cardiomyocytes from hypoxia-induced inflammatory response and apoptosis.

miRNA-145 inhibits VSMC proliferation by targeting CD40

Recent studies have demonstrated functions of miR-145 in vascular smooth muscle cells (VSMCs) phenotypes and vascular diseases. In this study, we aim to determine whether CD40 is involved in miR-145 mediated switch of VSMC phenotypes. In cultured VSMCs, the effects of miR-145 and CD40 on TNF-α, TGF-β, and Homocysteine (Hcy) induced cell proliferation were evaluated by over-expression of miR-145 or by siRNA-mediated knockdown of CD40. We also used ultrasound imaging to explore the effect of miR-145 on carotid artery intima-media thickness (CIMT) in atherosclerotic cerebral infarction (ACI) patients. The results showed 50 ng/mL TNF-α, 5 ng/mL TGF-β, and 500 μmol/L Hcy significantly increased the expression of CD40, both at mRNA and protein levels, and also induced the proliferation of VSMCs. We found that over-expression of miR-145 significantly inhibited the expression of CD40 and the differentiation of VSMCs, and over-expression of miR-145 decreased IL-6 levels in VSMC supernatants. In ACI patients, the lower expression of miR-145 was associated with thicker CIMT and higher levels of plasma IL-6. Our results suggest that the miR-145/CD40 pathway is involved in regulating VSMC phenotypes in TNF-α, TGF-β, and Hcy induced VSMCs proliferation model. Targeting miR-145/CD40 might be a useful strategy for treating atherosclerosis.