Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activation of the cAMP/PKA signaling pathway.

BACKGROUND AND AIMS: Vascular calcification (VC) is regarded as an independent risk factor for cardiovascular events in type 2 diabetic patients. Glucose transporter 1 (GLUT1) involves VC. Intermedin/Adrenomedullin-2 (IMD/ADM2) is a cardiovascular protective peptide that can inhibit multiple disease-associated VC. However, the role and mechanism of IMD in diabetic VC remain unclear. Here, we investigated whether IMD inhibits diabetic VC by inhibiting GLUT1. METHODS AND RESULTS: It was found that plasma IMD concentration was significantly decreased in type 2 diabetic patients and in fructose-induced diabetic rats compared with that in controls. Plasma IMD content was inversely correlated with fasting blood glucose level and VC severity. IMD alleviated VC in fructose-induced diabetic rats. Deficiency of Adm2 aggravated and Adm2 overexpression attenuated VC in high-fat diet-induced diabetic mice. In vitro, IMD mitigated high glucose-induced calcification of vascular smooth muscle cells (VSMCs). Mechanistically, IMD reduced advanced glycation end products (AGEs) content and the level of receptor for AGEs (RAGE). IMD decreased glucose transporter 1 (GLUT1) levels. The inhibitory effect of IMD on RAGE protein level was blocked by GLUT1 knockdown. GLUT1 knockdown abolished the effect of IMD on alleviating VSMC calcification. IMD receptor antagonist IMD17-47 and cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) inhibitor H89 abolished the inhibitory effects of IMD on GLUT1 and VSMC calcification. CONCLUSIONS: These findings revealed that IMD exerted its anti-calcification effect by inhibiting GLUT1, providing a novel therapeutic target for diabetic VC.

Intermedin1-53 Inhibits NLRP3 Inflammasome Activation by Targeting IRE1α in Cardiac Fibrosis.

Intermedin (IMD), a paracrine/autocrine peptide, protects against cardiac fibrosis. However, the underlying mechanism remains poorly understood. Previous study reports that activation of nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome contributes to cardiac fibrosis. In this study, we aimed to investigate whether IMD mitigated cardiac fibrosis by inhibiting NLRP3. Cardiac fibrosis was induced by angiotensin II (Ang II) infusion for 2 weeks in rats. Western blot, real-time PCR, histological staining, immunofluorescence assay, RNA sequencing, echocardiography, and hemodynamics were used to detect the role and the mechanism of IMD in cardiac fibrosis. Ang II infusion resulted in rat cardiac fibrosis, shown as over-deposition of myocardial interstitial collagen and cardiac dysfunction. Importantly, NLRP3 activation and endoplasmic reticulum stress (ERS) were found in Ang II-treated rat myocardium. Ang II infusion decreased the expression of IMD and increased the expression of the receptor system of IMD in the fibrotic rat myocardium. IMD treatment attenuated the cardiac fibrosis and improved cardiac function. In addition, IMD inhibited the upregulation of NLRP3 markers and ERS markers induced by Ang II. In vitro, IMD knockdown by small interfering RNA significantly promoted the Ang II-induced cardiac fibroblast and NLRP3 activation. Moreover, silencing of inositol requiring enzyme 1 α (IRE1α) blocked the effects of IMD inhibiting fibroblast and NLRP3 activation. Pre-incubation with PKA pathway inhibitor H89 blocked the effects of IMD on the anti-ERS, anti-NLRP3, and anti-fibrotic response. In conclusion, IMD alleviated cardiac fibrosis by inhibiting NLRP3 inflammasome activation through suppressing IRE1α via the cAMP/PKA pathway.

Effects of Incretin-based Therapies on Weight-related Indicators among Patients with Type 2 Diabetes: A Network Meta-analysis.

OBJECTIVE: To evaluate the effects of incretin-based therapies on body weight as the primary outcome, as well as on body mass index (BMI) and waist circumference (WC) as secondary outcomes. METHODS: Databases including Medline, Embase, the Cochrane Library, and clinicaltrials.gov (www.clinicaltrials.gov) were searched for randomized controlled trials (RCTs). Standard pairwise meta-analysis and network meta-analysis (NMA) were both carried out. The risk of bias (ROB) tool recommended by the Cochrane handbook was used to assess the quality of studies. Subgroup analysis, sensitivity analysis, meta-regression, and quality evaluation based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) were also performed. RESULTS: A total of 292 trials were included in this study. Compared with placebo, dipeptidyl-peptidase IV inhibitors (DPP-4Is) increased weight slightly by 0.31 kg [95% confidence interval ( CI): 0.05, 0.58] and had negligible effects on BMI and WC. Compared with placebo, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) lowered weight, BMI, and WC by -1.34 kg (95% CI: -1.60, -1.09), -1.10 kg/m 2 (95% CI: -1.42, -0.78), and -1.28 cm (95% CI: -1.69, -0.86), respectively. CONCLUSION: GLP-1 RAs were more effective than DPP-4Is in lowering the three indicators. Overall, the effects of GLP-1 RAs on weight, BMI, and WC were favorable.

Intermedin1-53 Ameliorates Homocysteine-Promoted Atherosclerotic Calcification by Inhibiting Endoplasmic Reticulum Stress.

AIM: Vascular calcification (VC) is thought to be an independent predictor of cardiovascular morbidity and mortality. Intermedin1-53 (IMD) is a cardiovascular protective peptide and can inhibit vascular medial calcification in rats. In this study, we investigated the effect of IMD on atherosclerotic calcification induced by a high-fat diet plus homocysteine (Hcy) and the potential mechanisms. METHODS: ApoE-/- mice were fed a high-fat diet with Hcy in drinking water to induce atherosclerotic calcification. RESULTS: As compared to the high-fat diet alone, Hcy treatment significantly increased atherosclerotic lesion areas and the number of calcified nodules in aortic roots and was reduced by IMD infusion or 4-phenylbutyric acid (PBA) treatment. In vitro, as compared to calcifying medium alone, Hcy treatment further increased alkaline phosphatase activity, calcium content, and calcium nodule number in human aorta vascular smooth muscle cells (HA-VSMCs), all blocked by IMD or PBA pretreatment. Mechanistically, IMD or PBA significantly alleviated endoplasmic reticulum stress (ERS) activation compared with Hcy treatment. In parallel, IMD or PBA attenuated the messenger RNA levels of osteogenic markers and inflammatory cytokines in aortas and their protein levels in lesions of aortic roots. In vitro, Hcy treatment significantly increased the protein levels of osteoblast-like cell markers in primary rat VSMCs and inflammation markers in mouse peritoneal macrophages, all decreased with IMD or PBA pretreatment. Intermedin1-53 pretreatment also markedly reduced the protein levels of ERS markers in rat VSMCs and mouse peritoneal macrophages. CONCLUSIONS: Intermedin1-53 protects against Hcy-promoted atherosclerotic calcification in ApoE-/- mice by inhibiting ERS.

Leptin and coronary heart disease: a systematic review and meta-analysis.

INTRODUCTION: Leptin, an adipose tissue-derived hormone, plays a central role in regulating human energy homeostasis. The role of leptin in regulating blood pressure, activating the sympathetic nervous system, insulin resistance, platelet aggregation, arterial thrombosis, angiogenesis, and inflammatory vascular responses suggests that leptin may have a close relationship with the development of coronary heart disease (CHD). However, no conclusive data are available to determine the association between leptin and CHD. METHODS: The PubMed, EMBASE and Cochrane databases were surveyed for original studies describing the association between leptin and CHD outcome from the date of publication of each database through March 2013. The data were extracted by two investigators independently. RESULTS: The meta-analysis reported here was comprised of eight original articles with a total of 21,064 participants (10,842 men, 10,222 women) and 2053 CHD events. The odds ratio for the sociodemographic-adjusted study reported here was 1.57 (95% confidence interval, 1.14-2.16) and 1.72 (95% confidence internal, 1.03-2.87) in males and females, respectively. Further adjustment for additional cardiovascular risk factors resulted in an odds ratio of 1.36 (95% confidence interval, 0.98-1.88) in males and 1.50 (95% confidence interval, 0.93-2.42) in females. Sensitivity analysis restricted to sociodemographics-adjusted studies with high methodological quality indicated an estimate of 1.47 (95% confidence internal, 1.06-2.04) in males and 1.85 (95% confidence internal, 0.61-5.63) in females. Sensitivity analysis restricted to cardiovascular risk factor-adjusted studies showed no significant differences in both males and females. CONCLUSION: The results of the meta-analysis represents the most precise and accurate estimate of the relationship between leptin and CHD. Although the associations of leptin and CHD were not statistically significant both in male and female overall, males with high levels of leptin should be paid more attention to. Our findings highlight the need for additional well-designed and gender-specific prospective studies to evaluate the role of leptin on the development of CHD.

[Research advances on leptin and respiratory diseases].

Leptin is a product of the obese (ob) gene and acts through its receptor Ob-R. Leptin is primarily known for its role as a hypothalamic modulator of food, especially in intake, energy balance, fat stores and body weight. Recent studies have shown that leptin may be involved in the development of respiratory diseases such as pulmonary artery hypertension, chronic obstructive pulmonary disease, lung neoplasms and asthma. Therefore, further studies are needed to elucidate the mechanisms accounting for the association between leptin and respiratory diseases, which may lead to the development of novel approaches to the prevention and treatment of these diseases. Here we give an overview of the distribution and physiological function of leptin and ob-R, and summarize the recent progress in the relationship between leptin and respiratory diseases.

Increased plasma levels of endothelin-1 and urotensin-II in patients with coronary heart disease.

Research has identified the vasoconstrictors endothelin-1 (ET-1) and urotensin-II (U-II) as having a role in the development of atherosclerotic cardiovascular disease. We aimed to observe alterations in plasma levels of both ET-1 and U-II in patients with coronary heart disease (CHD) undergoing percutaneous transluminal coronary angioplasty (PTCA) and stent therapy from November 2006 through May 2007. We examined plasma levels of ET-1 and U-II in 40 patients with CHD and 40 age-matched healthy subjects by radioimmunoassay (RIA). Chi-square test, Student's t-test, and one-way analysis of variance were used for statistical analyses. Correlations between variables were tested by simple linear regression analysis. Coronary heart disease patients had significantly higher ET-1 and UII levels than healthy controls (20.05 +/- 4.65 vs 8.16 +/- 3.38 and 71.90 +/- 11.61 vs 20.89 +/- 7.00 pg/ml, respectively, all P < 0.01). Importantly, plasma levels of U-II and ET-1 were correlated in patients with CHD (r = 0.64, P = 0.01). On day 1 after PTCA and stent therapy, plasma levels of ET-1 and U-II were significantly higher, by 99% and 25%, respectively, than those before therapy (all P < 0.01). On day 3 after therapy, ET-1 levels were higher by 25% (P < 0.01) than before therapy, and U-II levels decreased rapidly and were close to baseline levels (P > 0.05). On day 7 after therapy, CHD patients had significantly lower ET-1 and U-II levels than before therapy (all P < 0.01). Since ET-1 and U-II levels may be increased in plasma of patients with CHD, their activation might have clinical significance in terms of early intervention in patients with CHD, especially after PTCA and stent therapy.

Plasma levels of copeptin in patients with coronary heart disease.

The present study was undertaken to investigate alteration in plasma levels of copeptin, a stable fragment derived from provasopressin, in patients with coronary heart disease. We measured plasma level of copeptin in 21 patients with coronary heart disease (CHD) and 12 age-matched healthy subjects by radioimmunoassay (RIA). Chi-square test, Student's t-test and one-way analysis of variance were used for statistical analyses. Correlations between variables were tested by simple linear regression analysis. The plasma level of copeptin was significantly increased in patients (43.07 +/- 17.08 vs 11.13 +/- 5.73 pmol/l in controls, P < 0.01) and was further increased, by 60%, to 68.71 +/- 16.81 pmol/l on day 1 after therapy with percutaneous transluminal coronary angioplasty (PTCA) and stent (P < 0.05). On days 3 and 7 after therapy, the levels were greatly decreased, to 38.82 +/- 19.00 and 32.10 +/- 14.00 pmol/l, respectively, from that before therapy (all P < 0.05) but were higher, by 249% and 188%, respectively, than that of controls (all P < 0.01). The results suggest that the vasopressin system is activated in patients with CHD as indicated by changes in copeptin level, especially after PTCA and stent therapy. As a potential risk factor for CHD, plasma copeptin activation might have important clinical significance in terms of early intervention in patients with CHD.

Plasma level of mitochondrial coupling factor 6 increases in patients with coronary heart disease.

BACKGROUND: The aim of the present study was to investigate alterations in the plasma level of coupling factor 6 (CF6), a novel endogenous inhibitor of prostacyclin, in patients with coronary heart disease. METHODS AND RESULTS: In total, 35 patients with coronary heart disease and 20 age-matched healthy subjects were examined. Plasma levels of CF6 and 6-keto-prostaglandin (PG)F(1a) (a stable metabolite of prostacyclin) were measured using radioimmunoassay. The plasma level of CF6 was significantly increased in patients (254.1+/-29.8 pg/ml vs 219.4 +/-36.7 pg/ml in controls, p<0.0001), whereas that of 6-keto-PGF(1a) was significantly decreased (23.4 +/-2.3 pg/ml vs 26.1+/-4.5 pg/ml in controls, p=0.001). Moreover, after percutaneous transluminal coronary angioplasty (PTCA) and stent therapy, the level of CF6 was further increased by 30% to 330.4+/-26.0 pg/ml, and that of 6-keto-PGF (1a) was decreased by 42% to 13.5+/-2.0 pg/ml, compared with baseline (all p<0.01). Univariate analysis showed a significant result that the plasma level of CF6 was inversely correlated with that of 6-keto-PGF(1a) in the patients. The plasma ratio of CF6 to 6-keto-PGF(1a) was 8.4 in the control group and that in patients with coronary heart disease was increased to 24.4 after the therapy from 10.9 before therapy. CONCLUSIONS: The results suggest that an increased CF6 level may be responsible in part for the decreased prostacyclin level observed in patients with coronary heart disease, in particular after PTCA and stent therapy. As a potential risk factor for coronary heart disease, CF6 might have important clinical significance.

[Change of mitogen-activated protein kinase phosphatase-1 in heart and aorta of SHR and its effect on proliferation of vascular smooth muscle cells stimulated by angiotensin II].

AIM AND METHODS: To investigate the role of mitogen-activated protein kinase phosphatase-1 (MKP-1) in the regulation of cells proliferation, the expression of MKP-1 and extracellular signal-regulated kinase-1 (ERK-1) in heart and aorta of spontaneous hypertensive rat (SHR) and WKY were studied. We also investigated the effect of MKP-1 genes,which were transfected into vascular smooth muscle cells (VSMC) using the classical calcium phosphate coprecipitation technique, on the incorporation of 3H-TdR in VSMC stimulated by angiotensin II (Ang II). RESULTS: (1) Compared with that of WKY, MKP-1 expression in heart and aorta were significantly decreased by 53% (P < 0.01) and 45% (P < 0.01) in SHR, respectively. While the expression of ERK-1 in heart and aorta of SHR were higher than that of WKY (P < 0.01). The ratio of ERK-1/MKP-1 in heart and aorta of SHR were significantly higher than that of WKY. (2) 3H-TdR incorporation in VSMC stimulated by Ang II (10(-7) mol/L) was increased by 207% (P < 0.01), compared with control group. In the transfected cells with wild MKP-1 gene, Ang II-induced incorporation of 3H-TdR lowered 63%, compared with untransfected cells (P < 0.05). There were no marked inhibitive role between mutant MKP-1-transfected cells and blank vector-transfected cells in response to Ang II, compared with Ang II group (P > 0.05). CONCLUSION: These results showed that the expression of ERK-1 in heart and aorta isolated from SHR, which stimulated proliferation and hypertrophy of cells, is higher than that of MKP-1 which dephosphorylates and inactivated ERK-1. In addition, MKP-1 significantly inhibits Ang II-stimulated proliferation of VSMC.