AS is a persistent inflammatory condition that is started by the deposition as well as accumulation of low-density lipoproteins in the artery wall. In spite of excellent advances in both basic and scientific study, is still among the leading reasons for death in the world . In this study, we explored the molecular mechanism of Myr on ox-LDL-induced damage of HUVECs, revealing the crucial role of lncRNA GAS5 in this event. Our results suggested that Myr regulates HUVECs cell viability, apoptosis, inflammation, and EndMT through the GAS5/miR-29a-3p/TLR4/NF-κB pathway, clarifying a new mechanism of Myr on protecting against AS.
Ox-LDL has been shown to induce an enhanced generation of ROS, which play critical role in the progression of AS. Substantial evidence suggests that increased oxidative stress plays a prominent role in the pathogenesis of vascular endothelial dysfunction along with endothelial cell EndMT, inflammation, and apoptosis. We used ox-LDL stimulated HUVECs to simulate the occurrence of early atherosclerosis and the inflammatory response and EndMT of HUVECs was increased, and Myr significantly inhibited inflammatory response and EndMT to HUVECs stimulated with ox-LDL. Myr is known to exert antioxidative cytoprotective effects in various cells, including a HUVEC cell line . A previous study found that Myr exhibited pro-proliferative and anti-apoptotic effects in LPS-induced cardiomyocytes H9c2 cells injury . In this research study, we checked out the result of Myr on ox-LDL-induced atherosclerotic cell version. Our results suggested that 5 µM Myr pretreatment can considerably turn around the ox-LDL-induced downregulation of cell viability in HUVECs. Our results demonstrated that ox-LDL therapy could advertise the inflammation and EndMT of HUVECs through regulating CD31, SM22a, and inflammatory cytokines (IL-6, MCP-1, VCAM-1), which can be reversed by Myr pretreatment. A number of elements established that inflammation and EndMT accompanies atherosclerosis . A previous study found inhibition of the expression of VCAM-1 and ICAM-1 has been recognized as an important strategy against atherosclerosis. Moreover, vaccarin suppressed ox-LDL induced endothelial EndMT through downregulating endothelial marker CD31 and upregulating mesenchymal marker SM22α . Our findings are in substantial agreement with these researches.
The expression of GAS5 was highly expressed in both human and animal models [26, 27]. In this study, we found that GAS5 was upregulated and miR-29a-3p was downregulated in ox-LDL-induced HUVEC injury. Myr treatment can reverse these effects. A previous study showed that Myr inhibited the HMGB1, TLR4, and MyD88 expressions in the neurons, and it restored neuronal damage and inflammation caused by activation of NF-κB and MAPK signal pathways . In this study, up-regulation of lncRNA GAS5 and down-regulation of miR-29a-3p led to a decrease of cell apoptosis, inflammation, and EndMT, as well as reduction of activity of TLR4/NF-κB signaling pathway. According to our findings, Myr reduces the level of p-p65, p-IkBa, and TLR4 in HUVECs by regulating GAS5/miR-29a-3p, thus attenuating the inflammatory response and EndMT in ox-LDL-induced HUVEC injury.
Finally, our research study exposed that Myr is capable of ameliorating cell apoptosis, cell inflammation, and EndMT via GAS5/miR-29a-3p/TLR4/NF-κB pathway(Figure 8), suggesting Myr as a potential therapeutic agent for AS. In addition, GAS5 was proposed to be a promising target molecule involving in the pathophysiological processes of AS.