Nicotine promotes atherosclerosis development in apolipoprotein E-deficient mice through α1-nAChR.

α1 Nicotinic acetylcholine receptor (α1nAChR) is an important nicotine receptor that is widely distributed in vascular smooth muscle cells, macrophages, and endothelial cells. However, the role of α1nAChR in nicotine-mediated atherosclerosis remains unclear. The administration of nicotine for 12 weeks increased the area of the atherosclerotic lesion, the number of macrophages infiltrating the plaques, and the circulating levels of inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-α, in apolipoprotein E-deficient (ApoE-/- ) mice fed a high-fat diet. Nicotine also increased α1nAChR, calpain-1, matrix metalloproteinase-2 (MMP-2), and MMP-9 expression in the aortic tissue. Silencing of α1nAChR with an adenoassociated virus decreased the atherosclerotic size, lesion macrophage content, and circulating levels of inflammatory cytokines and suppressed α1nAChR, calpain-1, MMP-2, and MMP-9 expression in the nicotine group. In vitro, nicotine-induced α1nAChR, calpain-1, MMP-2, and MMP-9 expression in mouse vascular smooth muscle cells (MOVAS) and macrophages (RAW264.7), and enhanced the migration and proliferation of these cells. The silencing of α1nAChR inhibited these effects of nicotine MOVAS and RAW264.7 cells. Thus, we concluded that nicotine promoted the development of atherosclerosis partially by inducing the migration and proliferation of vascular smooth muscle cells and macrophages and inducing an inflammatory reaction. The effect of nicotine on atherogenesis may be mediated by α1nAChR-induced activation of the calpain-1/MMP-2/MMP-9 signaling pathway.

Stimulation of Alpha7 Nicotinic Acetylcholine Receptor Attenuates Nicotine-Induced Upregulation of MMP, MCP-1, and RANTES through Modulating ERK1/2/AP-1 Signaling Pathway in RAW264.7 and MOVAS Cells.

Vagus nerve stimulation through alpha7 nicotine acetylcholine receptors (α7-nAChR) signaling had been demonstrated attenuation of inflammation. This study aimed to determine whether PNU-282987, a selective α7-nAChR agonist, affected activities of matrix metalloproteinase (MMP) and inflammatory cytokines in nicotine-treatment RAW264.7 and MOVAS cells and to assess the underlying molecular mechanisms. RAW264.7 and MOVAS cells were treated with nicotine at different concentrations (0, 1, 10, and 100 ng/ml) for 0-120 min. Nicotine markedly stimulated the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and c-Jun in RAW264.7 cells. Pretreatment with U0126 significantly suppressed phosphorylation of ERK1/2 and further attenuated nicotine-induced activation of c-Jun and upregulation of MMP-2, MMP-9, monocyte chemotactic protein- (MCP-) 1, and regulated upon activation normal T cell expressed and secreted (RANTES). Similarly, nicotine treatment also increased phosphorylation of c-Jun and expressions of MMP-2, MMP-9, MCP-1, and RANTES in MOVAS cells. When cells were pretreated with PNU-282987, nicotine-induced activations of ERK1/2 and c-Jun in RAW264.7 cells and c-Jun in MOVAS cells were effectively inhibited. Furthermore, nicotine-induced secretions of MMP-2, MMP-9, MCP-1, and RANTES were remarkably downregulated. Treatment with α7-nAChR agonist inhibits nicotine-induced upregulation of MMP and inflammatory cytokines through modulating ERK1/2/AP-1 signaling in RAW264.7 cells and AP-1 in MOVAS cells, providing a new therapeutic for abdominal aortic aneurysm.

SP600125 Attenuates Nicotine-Related Aortic Aneurysm Formation by Inhibiting Matrix Metalloproteinase Production and CC Chemokine-Mediated Macrophage Migration.

Nicotine, a major chemical component of cigarettes, plays a pivotal role in the development of abdominal aortic aneurysm (AAA). c-Jun N-terminal kinase (JNK) has been demonstrated to participate in elastase-induced AAA. This study aimed to elucidate whether the JNK inhibitor SP600125 can attenuate nicotine plus angiotensin II- (AngII-) induced AAA formation and to assess the underlying molecular mechanisms. SP600125 significantly attenuated nicotine plus AngII-induced AAA formation. The expression of matrix metalloproteinase- (MMP-) 2, MMP-9, monocyte chemoattractant protein- (MCP-) 1, and regulated-on-activation, normal T-cells expressed and secreted (RANTES) was significantly upregulated in aortic aneurysm lesions but inhibited by SP600125. In vitro, nicotine induced the expression of MCP-1 and RANTES in both RAW264.7 (mouse macrophage) and MOVAS (mouse vascular smooth muscle) cells in a dose-dependent manner; expression was upregulated by 0.5 ng/mL nicotine but strongly downregulated by 500 ng/mL nicotine. SP600125 attenuated the upregulation of MCP-1 and RANTES expression and subsequent macrophage migration. In conclusion, SP600125 attenuates nicotine plus AngII-induced AAA formation likely by inhibiting MMP-2, MMP-9, MCP-1, and RANTES. The expression of chemokines in MOVAS cells induced by nicotine has an effect on RAW264.7 migration, which is likely to contribute to the development of nicotine-related AAA.

Continuous Positive Airway Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension: A Meta-Analysis of Randomized Controlled Trials.

This study aimed to analyze the effect of continuous positive airway pressure (CPAP) on blood pressure (BP) in patients with obstructive sleep apnea (OSA) and resistant hypertension. Randomized controlled trials (RCTs) that evaluated the effect of CPAP on BP in patients with OSA and resistant hypertension, indexed in MEDLINE, Embase, and the Cochrane Library from inception until March 20, 2015, were included in the meta-analysis. A total of five RCTs were identified to meet the inclusion criteria. The pooled changes after CPAP treatment for 24-hour ambulatory systolic BP and diastolic BP (DBP) were -4.78 mm Hg (95% confidence interval [CI], -7.95 to -1.61) and -2.95 mm Hg (95% CI, -5.37 to -0.53) in favor of the CPAP group. CPAP was also associated with reduction in nocturnal DBP (mean difference, -1.53 mm Hg, 95% CI, -3.07 to 0). The results indicated a favorable reduction in BP with CPAP treatment in patients with OSA and resistant hypertension.

Nicotine-induced upregulation of VCAM-1, MMP-2, and MMP-9 through the α7-nAChR-JNK pathway in RAW264.7 and MOVAS cells.

The ability of nicotine to induce aortic aneurysms has been shown in animal models; however, its underlying mechanisms remain elusive. In the present experiment, both the RAW264.7 and MOVAS cell lines were employed to examine the nicotine-induced modulation of VCAM-1, MMP-2, and MMP-9 expressions in macrophages and vascular smooth muscle cells. Our results showed that nicotine concentrations of both 0.5 and 5 ng/ml induced VCAM-1, MMP-2, and MMP-9 upregulation, while a concentration of 50 ng/ml had a slight inhibitory effect and a concentration of 500 ng/ml showed a significant inhibitory effect. When cells were pretreated with either SP600125 (JNK inhibitor) or PNU-282987 (α7-nAChR agonist) prior to nicotine exposure, the nicotine-induced upregulation of VCAM-1, MMP-2, MMP-9, and p-JNK was suppressed, with a joint treatment producing a more significant inhibitory effect. Moreover, PNU-282987 had a comparable inhibitory effect on VCAM-1, MMP-2, and MMP-9 expressions and JNK activation via phosphorylation as did SP600125. In conclusion, nicotine-induced VCAM-1, MMP-2, and MMP-9 expressions occur in a dose-dependent fashion in both of the cell lines tested. Furthermore, the nicotine exposure equivalent to plasma levels found in regular smokers can augment VCAM-1, MMP-2, and MMP-9 expressions through the α7-nAChR-JNK pathway.

Inhibition of leptin-induced vascular extracellular matrix remodelling by adiponectin.

Vascular extracellular matrix (ECM) remodelling, which is the result of disruption in the balance of ECM synthesis and degradation, induces vessel fibrosis and thereby leads to hypertension. Leptin is known to promote tissue fibrosis, while adiponectin has recently been demonstrated to be anti-fibrogenic in tissue fibrosis. In this study, we aimed to evaluate the leptin-antagonist function of adiponectin and to further elucidate the mechanisms through which adiponectin dampens leptin signalling in vascular smooth muscle cells, thus preventing excess ECM production, in our already established 3D co-culture vessel models. Our 3D co-culture vessel model, which mimics true blood vessels, is composed of vascular endothelial cells, vascular smooth muscle cells and collagen type I. We validated the profibrogenic effects of leptin and analysed matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase 1 (TIMP1) and collagen types II/IV secretion in 3D vessel models. The protective/inhibitory effects of adiponectin were re-analysed by inhibiting adiponectin receptor 1 (AdipoR) and AdipoR2 expression in endothelial cells using RNAi technology. In the 3D vessel models, adiponectin blocked the leptin-stimulated secretion of collagen types II/IV and TIMP1 while significantly increasing MMP2/9 activity. In endothelial cells, adiponectin induced phosphorylation of AMPK, thereby suppressing leptin-mediated STAT3 phosphorylation through induction of SOCS3 in smooth muscle cells. Our findings indicate that adiponectin disrupted the leptin-induced vascular ECM remodelling via AdipoR1 and enhanced AMPK signalling in endothelial cells, which, in turn, promoted SOCS3 up-regulation in smooth muscle cells to repress leptin-stimulated phosphorylation of STAT3.