Abstract
Background The endothelium is the first line of defence against harmful microenvironment risks, and microRNAs (miRNAs) involved in vascular inflammation may be promising therapeutic targets to modulate atherosclerosis progression. In this study, we aimed to investigate the mechanism by which microRNA-216a (miR-216a) modulated inflammation activation of endothelial cells. Methods. A replicative senescence model of human umbilical vein endothelial cells (HUVECs) was established, and population-doubling levels (PDLs) were defined during passages. PDL8 HUVECs were transfected with miR-216a mimics/inhibitor or small interfering RNA (siRNA) of SMAD family member 7 (Smad7). Real-time PCR and Western blot assays were performed to detect the regulatory role of miR-216a on Smad7 and NF-κB inhibitor alpha (IκBα) expression. The effect of miR-216a on adhesive capability of HUVECs to THP-1 cells was examined. MiR-216a and Smad7 expression in vivo were measured using human carotid atherosclerotic plaques of the patients who underwent carotid endarterectomy (n = 41). Results Luciferase assays showed that Smad7 was a direct target of miR-216a. Smad7 mRNA expression, negatively correlated with miR-216a during endothelial aging, was downregulated in senescent PDL44 cells, compared with young PDL8 HUVECs. MiR-216a markedly increased endothelial inflammation and adhesive capability to monocytes in PDL8 cells by promoting the phosphorylation and degradation of IκBα and then activating NF-κB signalling pathway. The effect of miR-216a on endothelial cells was consistent with that blocked Smad7 by siRNAs. When inhibiting endogenous miR-216a, the Smad7/IκBα expression was rescued, which led to decreased endothelial inflammation and monocytes recruitment. In human carotid atherosclerotic plaques, Smad7 level was remarkably decreased in high miR-216a group compared with low miR-216a group. Moreover, miR-216a was negatively correlated with Smad7 and IκBα levels and positively correlated with interleukin 1 beta (IL1β) expression in vivo. Conclusion In summary, our findings suggest a new mechanism of vascular endothelial inflammation involving Smad7/IκBα signalling pathway in atherosclerosis.
Highlights
Atherosclerosis, a chronical inflammatory disorder, is a critical pathogenesis underlying cardiovascular diseases
Compared with that expression in young PDL8 human umbilical vein endothelial cells (HUVECs), SMAD family member 7 (Smad7) messenger RNAs (mRNAs) was found to be downregulated by 47% (P = 0:03) in senescent PDL44 cells, which was negatively correlated with the miR216a expression during endothelial aging (Figure 1(a))
The computational miRNA target analysis by TargetScan Release 7.1 from miRNA databases indicated that Smad7 was a potential target gene of miR-216a, containing a candidate miR-216a binding site between 1,230 and 1,236 bps in the 3′UTR (Figure 1(b))
Summary
Atherosclerosis, a chronical inflammatory disorder, is a critical pathogenesis underlying cardiovascular diseases. Endothelial inflammation and dysfunction play a pivotal role in various stages of atherosclerosis, which can be induced by conventional risk factors such as aging, obesity, smoking, hypertension, hyperglycaemia, and hyperlipidemia [1] Except for these risk factors, a growing body of evidence indicates that microRNAs (miRNAs) are potentially epigenetic factors in regulating the progression of vascular endothelial senescence, inflammatory response, and atherosclerosis [2, 3]. Smad mRNA expression, negatively correlated with miR-216a during endothelial aging, was downregulated in senescent PDL44 cells, compared with young PDL8 HUVECs. MiR-216a markedly increased endothelial inflammation and adhesive capability to monocytes in PDL8 cells by promoting the phosphorylation and degradation of IκBα and activating NF-κB signalling pathway. Our findings suggest a new mechanism of vascular endothelial inflammation involving Smad7/IκBα signalling pathway in atherosclerosis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
