Irisin attenuates type 1 diabetic cardiomyopathy by anti-ferroptosis via SIRT1-mediated deacetylation of p53.

BACKGROUND: Diabetic cardiomyopathy (DCM) is a serious complication in patients with type 1 diabetes mellitus (T1DM), which still lacks adequate therapy. Irisin, a cleavage peptide off fibronectin type III domain-containing 5, has been shown to preserve cardiac function in cardiac ischemia-reperfusion injury. Whether or not irisin plays a cardioprotective role in DCM is not known. METHODS AND RESULTS: T1DM was induced by multiple low-dose intraperitoneal injections of streptozotocin (STZ). Our current study showed that irisin expression/level was lower in the heart and serum of mice with STZ-induced TIDM. Irisin supplementation by intraperitoneal injection improved the impaired cardiac function in mice with DCM, which was ascribed to the inhibition of ferroptosis, because the increased ferroptosis, associated with increased cardiac malondialdehyde (MDA), decreased reduced glutathione (GSH) and protein expressions of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4), was ameliorated by irisin. In the presence of erastin, a ferroptosis inducer, the irisin-mediated protective effects were blocked. Mechanistically, irisin treatment increased Sirtuin 1 (SIRT1) and decreased p53 K382 acetylation, which decreased p53 protein expression by increasing its degradation, consequently upregulated SLC7A11 and GPX4 expressions. Thus, irisin-mediated reduction in p53 decreases ferroptosis and protects cardiomyocytes against injury due to high glucose. CONCLUSION: This study demonstrated that irisin could improve cardiac function by suppressing ferroptosis in T1DM via the SIRT1-p53-SLC7A11/GPX4 pathway. Irisin may be a therapeutic approach in the management of T1DM-induced cardiomyopathy.

Deep Reinforcement Learning-Based Resource Allocation for Cellular Vehicular Network Mode 3 with Underlay Approach.

Vehicle-to-vehicle (V2V) communication has attracted increasing attention since it can improve road safety and traffic efficiency. In the underlay approach of mode 3, the V2V links need to reuse the spectrum resources preoccupied with vehicle-to-infrastructure (V2I) links, which will interfere with the V2I links. Therefore, how to allocate wireless resources flexibly and improve the throughput of the V2I links while meeting the low latency requirements of the V2V links needs to be determined. This paper proposes a V2V resource allocation framework based on deep reinforcement learning. The base station (BS) uses a double deep Q network to allocate resources intelligently. In particular, to reduce the signaling overhead for the BS to acquire channel state information (CSI) in mode 3, the BS optimizes the resource allocation strategy based on partial CSI in the framework of this article. The simulation results indicate that the proposed scheme can meet the low latency requirements of V2V links while increasing the capacity of the V2I links compared with the other methods. In addition, the proposed partial CSI design has comparable performance to complete CSI.

Gastrin exerts a protective effect against myocardial infarction via promoting angiogenesis.

BACKGROUND: It is known that increased gastrin concentration is negatively correlated with cardiovascular mortality, and plasma gastrin levels are increased in patients after myocardial infarction (MI). However, whether gastrin can play a protective role in MI remains unknown. METHODS: Adult C57BL/6 mice were subjected to ligation of the left anterior descending coronary artery (LAD) and subcutaneous infusion of gastrin (120 µg/Kg body weight/day, 100 µL in the pump) for 28 days after MI. Plasma gastrin concentrations were measured through an ELISA detection kit. Mice were analyzed by echocardiography after surgery. CD31 and VEGF expression were quantified using immunofluorescence staining or/and western blot to assess the angiogenesis in peri-infarct myocardium. Capillary-like tube formation and cell migration assays were performed to detect gastrin-induced angiogenesis. RESULTS: We found that gastrin administration significantly ameliorated MI-induced cardiac dysfunction and reduced fibrosis at 28 days in post-MI hearts. Additionally, gastrin treatment significantly decreased cardiomyocyte apoptosis and increased angiogenesis in the infarct border zone without influencing cardiomyocyte proliferation. In vitro results revealed that gastrin up-regulated the PI3K/Akt/vascular endothelial growth factor (VEGF) signaling pathway and promoted migration and tube formation of human coronary artery endothelial cells (HCAECs). Cholecystokinin 2 receptor (CCK2R) mediated the protective effect of gastrin since the CCK2R blocker CI988 attenuated the gastrin-mediated angiogenesis and cardiac function protection. CONCLUSION: Our data revealed that gastrin promoted angiogenesis and improved cardiac function in post-MI mice, highlighting its potential as a therapeutic target candidate.

Tirofiban induces vasorelaxation of the coronary artery via an endothelium-dependent NO-cGMP signaling by activating the PI3K/Akt/eNOS pathway.

Tirofiban, a glycoprotein IIb/IIIa inhibitor, is an antiplatelet drug extensively used in patients with acute coronary syndrome (ACS) and exerts an therapeutic effect on no-reflow phenomenon during percutaneous coronary intervention (PCI). Previous studies elucidated the vasodilation caused by tirofiban in the peripheral artery. However, whether tirofiban exerts a vasodilator effect on the coronary artery is unclear. Our present study found that tirofiban induced endothelium-dependent vasodilation in a concentration- and time-dependent manner in the isolated rat coronary artery pre-constricted by 5-hydroxytryptamine (5-HT). Further study showed that incubation of human umbilical venous endothelial cells (HUVECs) with tirofiban increased NO production, which was ascribed to the increased eNOS phosphorylation. This was confirmed by the loss of the vasorelaxant effect of tirofiban in the presence of l-NAME (eNOS inhibitor) and L-NMMA (NOS inhibitor) but not SMT (iNOS inhibitor) on isolated rat coronary arteries. The vasorelaxation was also blocked by the PI3K inhibitors, wortmannin and LY294002, as well as the Akt inhibitor SH-5, indicating the role of PI3K and Akt in tirofiban-mediated vasodilation. Moreover, further study showed that soluble guanylyl cyclase (sGC) inhibitor ODQ, or blockers of potassium channel (big-conductance calcium-activated potassium channel) blocked tirofiban-induced vasodilation of the coronary artery. These findings suggest that tirofiban induces vasorelaxation via an endothelium-dependent NO-cGMP signaling through the activation of the Akt/eNOS/sGC pathway.

Impaired dopamine D1 receptor-mediated vasorelaxation of mesenteric arteries in obese Zucker rats.

BACKGROUND: Obesity plays an important role in the pathogenesis of hypertension. Renal dopamine D1-like receptor-mediated diuresis and natriuresis are impaired in the obese Zucker rat, an obesity-related hypertensive rat model. The role of arterial D1 receptors in the hypertension of obese Zucker rats is not clear. METHODS: Plasma glucose and insulin concentrations and blood pressure were measured. The vasodilatory response of isolated mesenteric arteries was evaluated using a small vessel myograph. The expression and phosphorylation of D1 receptors were quantified by co-immunoprecipitation and immunoblotting To determine the effect of hyperinsulinemia and hyperglycemia on the function of the arterial D1 receptor, we studied obese Zucker rats (six to eight-weeks old) fed (6 weeks) vehicle or rosiglitazone, an insulin sensitizer (10 mg/kg per day) and lean Zucker rats (eight to ten-weeks old), fed high-fat diet to induce hyperinsulinemia or injected intraperitoneally with streptomycin (STZ) to induce hyperglycemia. RESULTS: In obese Zucker rats, the vasorelaxant effect of D1-like receptors was impaired that could be ascribed to decreased arterial D1 receptor expression and increased D1 receptor phosphorylation. In these obese rats, rosiglitazone normalized the arterial D1 receptor expression and phosphorylation and improved the D1-like receptor-mediated vasorelaxation. We also found that D1 receptor-dependent vasorelaxation was decreased in lean Zucker rats with hyperinsulinemia or hyperglycemia but the D1 receptor dysfunction was greater in the former than in the latter group. The ability of insulin and glucose to decrease D1 receptor expression and increase its phosphorylation were confirmed in studies of rat aortic smooth muscle cells. CONCLUSIONS: Both hyperinsulinemia and hyperglycemia caused D1 receptor dysfunction by decreasing arterial D1 receptor expression and increasing D1 receptor phosphorylation. Impaired D1 receptor-mediated vasorelaxation is involved in the pathogenesis of obesity-related hypertension.

Dopamine d(1)-like receptors suppress proliferation of vascular smooth muscle cell induced by insulin-like growth factor-1.

OBJECTIVE: Proliferation of vascular smooth muscle cells (VSMCs) participates in the pathogenesis and development of cardiovascular diseases, including essential hypertension and atherosclerosis. Our previous study found that stimulation of D1-like dopamine receptors inhibited insulin-induced proliferation of VSMCs. Insulin-like growth factor-1 (IGF-1) and insulin share similar structure and biological effect. However, whether or not there is any effect of D1-like receptors on IGF-1-induced proliferation of VSMCs is not known. Therefore, we investigated the inhibitory effect of D1-like dopamine receptors on the IGF-1-induced VSMCs proliferation in this study. METHOD: VSMC proliferation was determined by [(3)H]-thymidine incorporation, the uptake of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and cell number. Phosphorylated/non-phosphorylated IGF-1 receptor, Akt, mTOR and p70S6K expressions were determined by immunoblotting. The oligodeoxynucleotides were transfected to A10 cells to identify the effect of D1 and D5 receptors, respectively. RESULTS: IGF-1 increased the proliferation of VSMCs, while in the presence of fenoldopam, IGF-1-mediated stimulatory effect was reduced. Use of either antisense for D1 or D5 receptor partially inhibited the fenoldopam-induced antiproliferation effect of VSMCs. Use of both D1 and D5 receptor antisenses completely blocked the inhibitory effect of fenoldopam. In the presence of PI3k and mTOR inhibitors, the IGF-1-mediated proliferation of VSMCs was blocked. Moreover, IGF-1 increased the phosphorylation of PI3k and mTOR. The inhibitory effect of fenoldopam on VSMC proliferation might be due to the inhibition of IGF-1 receptor expression and IGF-1 phosphorylation, because in the presence of fenoldopam, the stimulatory effect of IGF-1 on phosphorylation of IGF-1 receptor, PI3k and mTOR is reduced, the IGF-1 receptor expression was reduced in A10 cells. CONCLUSION: Activation of the D1-like receptors suppressed the proliferative effect of IGF-1 in A10 cells via the inhibition of the IGF-1R/Akt/mTOR/p70S6K pathway and downregulated the expression of IGF-1 receptor.

The Emerging Role of Irisin in Cardiovascular Diseases.

Irisin, a novel hormone like polypeptide, is cleaved and secreted by an unknown protease from a membrane-spanning protein, FNDC5 (fibronectin type III domain-containing protein 5). The current knowledge on the biological functions of irisin includes browning white adipose tissue, regulating insulin use, and anti-inflammatory and antioxidative properties. Dysfunction of irisin has shown to be involved in cardiovascular diseases such as hypertension, coronary artery disease, myocardial infarction, and myocardial ischemia-reperfusion injury. Moreover, irisin gene variants are also associated with cardiovascular diseases. In this review, we discuss the current knowledge on irisin-mediated regulatory mechanisms and their roles in the pathogenesis of cardiovascular diseases.

Increased AT1 receptor expression mediates vasoconstriction leading to hypertension in Snx1-/- mice.

Angiotensin II type 1 receptor (AT1R) is a vital therapeutic target for hypertension. Sorting nexin 1 (SNX1) participates in the sorting and trafficking of the renal dopamine D5 receptor, while angiotensin and dopamine are counterregulatory factors in the regulation of blood pressure. The effect of SNX1 on AT1R is not known. We hypothesized that SNX1, through arterial AT1R sorting and trafficking, is involved in blood pressure regulation. CRISPR/Cas9 system-generated SNX1-/- mice showed dramatic elevations in blood pressure compared to their wild-type littermates. The angiotensin II-mediated contractile reactivity of the mesenteric arteries and AT1R expression in the aortas were also increased. Moreover, immunofluorescence and immunoprecipitation analyses revealed that SNX1 and AT1R were colocalized and interacted in the aortas of wild-type mice. In vitro studies revealed that AT1R protein levels and downstream calcium signaling were upregulated in A10 cells treated with SNX1 siRNA. This may have resulted from decreased AT1R protein degradation since the AT1R mRNA levels showed no changes. AT1R protein was less degraded when SNX1 was downregulated, as reflected by a cycloheximide chase assay. Furthermore, proteasomal rather than lysosomal inhibition increased AT1R protein content, and this effect was accompanied by decayed binding of ubiquitin and AT1R after SNX1 knockdown. Confocal microscopy revealed that AT1R colocalized with PSMD6, a proteasomal marker, and the colocalization was reduced after SNX1 knockdown. These findings suggest that SNX1 sorts AT1R for proteasomal degradation and that SNX1 impairment increases arterial AT1R expression, leading to increased vasoconstriction and blood pressure.

Irisin Lowers Blood Pressure by Improvement of Endothelial Dysfunction via AMPK-Akt-eNOS-NO Pathway in the Spontaneously Hypertensive Rat.

BACKGROUND: Exercise is a major nonpharmacological treatment for hypertension, but its underlying mechanisms are still not completely elucidated. Irisin, a polypeptide containing 112 amino acids, which is secreted mainly by skeletal muscle cells during exercise, exerts a protective role in metabolic diseases, such as diabetes mellitus and obesity. Because of the close relationship between irisin and metabolic diseases, we hypothesized that irisin may play a role in the regulation of blood pressure. METHODS AND RESULTS: Blood pressures of male Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were monitored through the carotid artery. Our study found that acute intravenous injection of irisin reduced blood pressure in SHRs, but not WKY rats. Irisin, by itself, had no direct vasorelaxing effect in phenylephrine-preconstricted mesenteric arteries from SHRs. However, irisin augmented the acetylcholine-induced vasorelaxation in mesenteric arteries from SHRs that could be reversed by Nω-nitro-l-arginine-methyl ester (L-NAME; 100 µmol/L), indicating a role of nitric oxide (NO) in this action. Indeed, irisin increased NO production and phosphorylation of endothelial nirtic oxide synthase (eNOS) in endothelial cells. 5'-AMP-activated protein kinase (AMPK) was involved in the vasorelaxing effect of irisin because compound C (20 µmol/L), an AMPK inhibitor, blocked the irisin-mediated increase in phosphorylation of eNOS and protein kinase B (Akt) in endothelial cells and vasodilation in mesenteric arteries. CONCLUSIONS: We conclude that acute administration of irisin lowers blood pressure of SHRs by amelioration of endothelial dysfunction of the mesenteric artery through the AMPK-Akt-eNOS-NO signaling pathway.

Targeting HO-1 by Epigallocatechin-3-Gallate Reduces Contrast-Induced Renal Injury via Anti-Oxidative Stress and Anti-Inflammation Pathways.

Both oxidative stress and inflammation are involved in the pathogenesis of contrast-induced nephropathy (CIN). Epigallocatechin-3-gallate (EGCG), a purified catechin from green tea, has antioxidant and anti-inflammatory effects. However, it is unknown whether or not EGCG is effective in treating CIN. Our present study found that intravenous administration of EGCG, either before or just after the establishment of CIN, had a protective effect, determined by normalization of serum creatinine and blood urea nitrogen levels, improvement in renal histopathological scoring and alleviation of apoptosis, accompanied by decreased oxidative stress and inflammation. Because EGCG is a potent inducer of the antioxidant heme oxygenase-1 (HO-1), we studied HO-1 signaling in CIN. HO-1 levels were increased in CIN; treatment with EGCG further increased HO-1 levels, accompanied by an increase in Nrf2, a regulator of antioxidant proteins. Interestingly, blockade of HO-1 with protoporphyrin IX zinc(II) (ZnPP) prevented the protective effect of EGCG on CIN. ZnPP also blocked the ability of EGCG to increase the activity of an antioxidant (superoxide dismutase), and decrease markers of oxidative stress (myeloperoxidase and malondialdehyde) and inflammation (myeloperoxidase and IL-1ß), indicating that HO-1 is the upstream molecule that regulates the EGCG-mediated protection. To determine further the role of HO-1 on the EGCG-mediated inhibition of inflammation, we studied the effect of EGCG on the NLRP3 inflammasome, an upstream signaling of IL-1ß. EGCG down-regulated NLRP3 expression, which was blocked by ZnPP, indicating that HO-1 links EGCG with NLRP3. Therefore, EGCG, via up-regulation of HO-1, protects against CIN by amelioration of oxidative stress and inflammation.

Circulating 'lncRNA OTTHUMT00000387022' from monocytes as a novel biomarker for coronary artery disease.

AIMS: Long non-coding RNAs (lncRNAs) have been found to be involved in the pathogenesis of coronary artery disease (CAD). However, it remains to be established whether or not circulating lncRNAs can serve as biomarkers of CAD. METHODS AND RESULTS: Using a microarray-based lncRNA expression profiling, we found 86 lncRNAs that were differentially expressed in circulating peripheral blood monocytes and plasma from 15 CAD patients and 15 control subjects. After choosing a consistent criterion (average normalized intensity ≥7 with significance <0.005) and confirmed by quantitative PCR, only three lncRNAs (CoroMarker, BAT5, and IL21R-AS1) remained as candidate CAD biomarkers. Using the analysis of area under the curve (AUC) of the receiver-operating characteristic in another pilot group and another larger cohort, CoroMarker was found to be the best candidate biomarker for CAD with an AUC of 0.920 and 95% confidence interval of 0.892-0.947. CoroMarker was independent from known CAD risk factors and other cardiovascular diseases. In a prospective study, we found that the sensitivity and specificity of CoroMarker were 76 and 92.5%, respectively. Functional enrichment analysis showed CoroMarker to be clustered with genes positively associated with signal transduction, transmembrane transport, synaptic transmission, and innate immunity and negatively associated with inflammation. These findings were validated in THP-1 cells; CoroMarker siRNA treatment decreased the concentrations of proinflammatory cytokines [interleukin (IL)-1ß, IL-6, and tumour necrosis factor α] in the culture medium. CONCLUSION: The present study suggests that CoroMarker is a novel and specific biomarker of CAD.

Prenatal lipopolysaccharide exposure causes mesenteric vascular dysfunction through the nitric oxide and cyclic guanosine monophosphate pathway in offspring.

Cardiovascular diseases, such as hypertension, could be programmed in fetal life. Prenatal lipopolysaccharide (LPS) exposure in utero results in increased blood pressure in offspring, but the vascular mechanisms involved are unclear. Pregnant Sprague-Dawley rats were intraperitoneally injected with LPS (0.79mg/kg) or saline (0.5ml) on gestation days 8, 10, and 12. The offspring of LPS-treated dams had higher blood pressure and decreased acetylcholine (ACh)-induced relaxation and increased phenylephrine (PE)-induced contraction in endothelium-intact mesenteric arteries. Endothelium removal significantly enhanced the PE-induced contraction in offspring of control but not LPS-treated dams. The arteries pretreated with l-NAME to inhibit nitric oxide synthase (eNOS) in the endothelium or ODQ to inhibit cGMP production in the vascular smooth muscle had attenuated ACh-induced relaxation but augmented PE-induced contraction to a larger extent in arteries from offspring of control than those from LPS-treated dams. In addition, the endothelium-independent relaxation caused by sodium nitroprusside was also decreased in arteries from offspring of LPS-treated dams. The functional results were accompanied by a reduction in the expressions of eNOS and soluble guanylate cyclase (sGC) and production of NO and cGMP in arteries from offspring of LPS-treated dams. Furthermore, LPS-treated dam's offspring arteries had increased oxidative stress and decreased antioxidant capacity. Three-week treatment with TEMPOL, a reactive oxygen species (ROS) scavenger, normalized the alterations in the levels of ROS, eNOS, and sGC, as well as in the production of NO and cGMP and vascular function in the arteries of the offspring of LPS-treated dams. In conclusion, prenatal LPS exposure programs vascular dysfunction of mesenteric arteries through increased oxidative stress and impaired NO-cGMP signaling pathway.

Stimulation of Dopamine D3 Receptor Attenuates Renal Ischemia-Reperfusion Injury via Increased Linkage With Gα12.

BACKGROUND: Renal ischemia-reperfusion (I/R) injury causes renal tubular necrosis, apoptosis, and inflammation leading to acute renal dysfunction. Recent studies have revealed that deletion of Gα12 mitigates the renal damage due to I/R injury. Our previous study showed that activation of dopamine D3 receptor (D3R) increased its linkage with Gα12, and hampered Gα12-mediated stimulation of renal sodium transport. In the present study, we used an in-vivo rat model and an in vitro study of the renal epithelial cell line (NRK52E) to investigate whether or not an increased linkage between D3R and Gα12 contributes to the protective effect of D3R on renal I/R injury. METHODS: For in vivo studies, I/R injury was induced in a rat renal unilateral clamping model. For in vitro studies, hypoxia/reoxygenation and cold storage/rewarming injuries were performed in NRK52E cells. PD128907, a D3R agonist, or vehicle, was administered 15 minutes before clamping (or hypoxia) in both the in vivo or in vitro studies. RESULTS: In the rat renal unilateral clamping model, pretreatment with PD128907 (0.2 mg/kg, intravenous) protected against renal I/R injury and increased survival rate during a long-term follow-up after 7 days. A decrease in the generation of reactive oxygen species, apoptosis, and inflammation may be involved in the D3R-mediated protection because pretreatment with PD128907 increased renal glutathione and superoxide dismutase levels and decreased malondialdehyde levels in the I/R group. The increase in cytokines (TNF-α, IL-1ß, and IL-10) and myeloperoxidase in I/R injured kidney was also prevented with a simultaneous decrease in the apoptosis of the epithelial cells and expression of apoptosis biomarkers in kidney harvested 1 day after I/R injury. The increase in the coimmunoprecipitation between D3R and Gα12 with D3R stimulation paralleled the observed renal protection from I/R injury. Moreover, in vitro studies showed that transient overexpression of Gα12 in the NRK52E cells attenuated the protective effect of PD128907 on hypoxia/reoxygenation injury. The protective effect of PD128907 might be of significance to renal transplantation because cold storage/rewarming induced injury increased lactate dehydrogenase release and decreased cell viability in NRK52E cells. Conversely, in the presence of PD128907, the increased lactate dehydrogenase release and decreased cell viability were reversed. CONCLUSIONS: These results suggest that activation of D3R, by decreasing Gα12-induced renal damage, may exert a protective effect from I/R injury.

Protective effects of aliskiren on ischemia-reperfusion-induced renal injury in rats.

The protective effect of aliskiren on ischemia-reperfusion (I/R) injury in the heart and brain has been reported. Whether or not this protective effect extends into the alleviation of renal I/R injury is not known. Therefore, we investigated the protective effect of aliskiren in the kidney in this study. Sprague-Dawley rats were randomly divided into four groups: sham control group; sham control with aliskiren pretreatment; I/R group and I/R with aliskiren pretreatment. Aliskiren (3mg/kg) or vehicle was administrated intravenously via vena cava. Blood samples and the left kidneys were then collected to check for renal function, angiotensin II (Ang II), apoptosis and oxidative stress levels. Compared with the sham rats, serum creatinine (SCR) and blood urea nitrogen (BUN) were significantly increased in the I/R rats, accompanied by histopathological damage to the kidney, which included tubular cell swelling, desquamation, and cast formation. There were also more apoptotic cells and leukocyte infiltration in the I/R rats than in the sham rats. Pretreatment with aliskiren ameliorated I/R induced renal injury, i.e. reduced SCR and BUN levels, ameliorated renal histopathological changes, and decreased the apoptosis of cells and leukocyte infiltration in kidney. I/R injury also decreased superoxide dismutase (SOD) and glutathione (GSH-reduced form) levels, which were blocked with the aliskiren pretreatment. Aliskiren pretreatment exerts a protective effect on ischemia/reperfusion injury in the kidney, via amelioration of oxidative stress, and reduction in leukocyte infiltration and cellular apoptosis.