Irisin attenuates vascular remodeling in hypertensive mice induced by Ang II by suppressing Ca2+-dependent endoplasmic reticulum stress in VSMCs.

Vascular remodeling plays a vital role in hypertensive diseases and is an important target for hypertension treatment. Irisin, a newly discovered myokine and adipokine, has been found to have beneficial effects on various cardiovascular diseases. However, the pharmacological effect of irisin in antagonizing hypertension-induced vascular remodeling is not well understood. In the present study, we investigated the protection and mechanisms of irisin against hypertension and vascular remodeling induced by angiotensin II (Ang II). Adult male mice of wild-type, FNDC5 (irisin-precursor) knockout, and FNDC5 overexpression were used to develop hypertension by challenging them with Ang II subcutaneously in the back using a microosmotic pump for 4 weeks. Similar to the attenuation of irisin on Ang II-induced VSMCs remodeling, endogenous FNDC5 ablation exacerbated, and exogenous FNDC5 overexpression alleviated Ang II-induced hypertension and vascular remodeling. Aortic RNA sequencing showed that irisin deficiency exacerbated intracellular calcium imbalance and increased vasoconstriction, which was parallel to the deterioration in both ER calcium dysmetabolism and ER stress. FNDC5 overexpression/exogenous irisin supplementation protected VSMCs from Ang II-induced remodeling by improving endoplasmic reticulum (ER) homeostasis. This improvement includes inhibiting Ca2+ release from the ER and promoting the re-absorption of Ca2+ into the ER, thus relieving Ca2+-dependent ER stress. Furthermore, irisin was confirmed to bind to its receptors, αV/ß5 integrins, to further activate the AMPK pathway and inhibit the p38 pathway, leading to vasoprotection in Ang II-insulted VSMCs. These results indicate that irisin protects against hypertension and vascular remodeling in Ang II-challenged mice by restoring calcium homeostasis and attenuating ER stress in VSMCs via activating AMPK and suppressing p38 signaling.

Prim-O-glucosycimifugin attenuates liver injury in septic mice by inhibiting NLRP3 inflammasome/caspase-1 signaling cascades in macrophages.

BACKGROUND: Liver dysfunction and liver failure are serious complications of sepsis, directly leading to septic progression and death. Now, there is no specific therapeutics available for sepsis-related liver dysfunction. Prim-O-glucosylcimifugin (POG), a chromone richest in the roots of Saposhnikovia divaricata (Turcz.) Schischk, is usually used to treat headache, rheumatoid arthritis and tetanus. While, the underlying mechanisms of POG against sepsis-induced liver damage and dysfunction are still not clear. PURPOSE: To study the anti-sepsis effect of POG, and its pharmacological mechanism to protect liver injury by weakening the function of macrophages in septic livers through inhibiting NOD-like receptor protein 3 (NLRP3) inflammasome pathway. METHOD: In vivo experiments, septic mouse model was induced by cecal ligation and puncture (CLP), and then the mortality was detected, liver inflammatory damages and plasma biomarkers of liver injury were evaluated by histopathological staining and biochemical assays, respectively. In vitro experiments, mouse primary peritoneal macrophages were treated with lipopolysaccharide (LPS) and ATP, and then the activated-inflammasomes, macrophage migration and polarization were detected by ASC immunofluorescence staining, transwell and flow cytometry assays, respectively. NLRP3 inflammasome components NLRP3, caspase-1, IL-1ß and IL-18 protein expressions were detected using western blot assays, and the contents of IL-1ß and IL-18 were measured by ELISA assays. RESULTS: POG treatment significantly decreased the mortality, liver inflammatory damages, hepatocyte apoptosis and plasma biomarkers of liver injury in CLP-challenged male WT mice, which were comparable to those in ibuprofen (a putative anti-inflammatory drug)-supplemented septic male WT mice and septic NLRP3 deficient-male mice. POG supplementation significantly suppressed NLRP3 inflammasome activation in septic liver tissues and cultured macrophages, by significantly reducing NLRP3, cleaved-caspase-1, IL-1ß and IL-18 levels, the activated-inflammasome ASC specks, and macrophage infiltration and migration, as well as M1-like polarization, but significantly increasing M2-like polarization. These findings were similar to the pharmacological effects of ibuprofen, NLRP3 deficiency, and a special NLRP3 inhibitor, MCC950. CONCLUSION: POG protected against sepsis by inhibiting NLRP3 inflammasome-mediated macrophage activation in septic liver and attenuating liver inflammatory injury, indicating that it may be a potential anti-sepsis drug candidate.

Mogrol suppresses lung cancer cell growth by activating AMPK-dependent autophagic death and inducing p53-dependent cell cycle arrest and apoptosis.

Lung carcinoma is the leading cause of cancer-related death worldwide. Chemotherapy remains the cornerstone of lung cancer treatment. Unfortunately, most types of cancer will develop resistance to chemotherapies over the time. One of the efforts to prevent the chemotherapy resistance is to find alternative chemotherapy drugs. Mogrol has been found to have antitumor activity. However, little is known about the pharmacological mechanisms underlying the suppression of mogrol on lung cancers. In this study, we observed that mogrol exposure significantly reduced the tumor volume and weight in tumor-bearing nude mice without obvious effect on body weight and cardiac function. Mogrol also significantly inhibited the proliferation and migration of lung cancer cells, including non-small-cell lung carcinoma cells, A549, H1299, H1975 and SK-MES-1 cells, with no obvious effect on control human bronchial epithelial cells (HBE). Further studies revealed that mogrol stirred excessive autophagy and autophagic flux, and finally, autophagic cell death, in lung cancer cells, which could be attenuated by autophagy inhibitors, 3-MA and chloroquine. Furthermore, mogrol significantly activated AMPK to induce autophagy and autophagic cell death, which could be abrogated by Compound C, an AMPK inhibitor. In addition, mogrol induced a significant increase in p53 activity in lung cancer cells, accompanied with cell cycle arrest and apoptosis, which could be weakened by p53 silence. Our results indicated that mogrol effectively suppressed lung cancer cells in vivo and in vitro by inducing the excessive autophagy and autophagic cell death via activating AMPK signaling pathway, as well as cell cycle arrest and apoptosis via activating p53 pathway.

5-Lipoxagenase deficiency attenuates L-NAME-induced hypertension and vascular remodeling.

BACKGROUND: Abnormalities of the L-arginine-nitric oxide pathway induce hypertension. 5-Lipoxygenase (5-LO) is the key enzyme involved in synthesis of leukotrienes (LTs). However, whether nitricoxide synthase dysfunction induces hypertensive vascular remodeling by regulating 5-LO activity and its downstream inflammatory metabolites remains unknown. METHODS AND RESULTS: Six-week L-NAME treatment significantly induced hypertension and vascular remodeling in both wild-type (WT) and 5-LO-knockout (5-LO-KO) mice, and blood pressure in caudal and carotid arteries was lower in 5-LO-KO than WT mice with L-NAME exposure. On histology, L-NAME induced less media thickness, media-to-lumen ratio, and collagen deposition and fewer Ki-67-positive vascular smooth muscle cells (VSMCs) but more elastin expression in thoracic and mesenteric aortas of 5-LO-KO than L-NAME-treated WT mice. L-NAME significantly increased LT content, including LTB4 and cysteinyl LT (CysLTs), in plasma and neutrophil culture supernatants from WT mice. On immunohistochemistry, L-NAME promoted the colocalization of 5-LO and 5-LO-activating protein on the nuclear envelope of cultured neutrophils, which was accompanied by elevated LT content in culture supernatants. In addition, LTs significantly promoted BrdU incorporation, migration and phenotypic modulation in VSMCs. CONCLUSION: L-NAME may activate the 5-LO/LT pathway in immune cells, such as neutrophils, and promote the products of 5-LO metabolites, including LTB4 and CysLTs, which aggravate vascular remodeling in hypertension. 5-LO deficiency may protect against hypertension and vascular remodeling by reducing levels of 5-LO downstream inflammatory metabolites.

Irisin alleviates pressure overload-induced cardiac hypertrophy by inducing protective autophagy via mTOR-independent activation of the AMPK-ULK1 pathway.

In hypertrophic hearts, autophagic flux insufficiency is recognized as a key pathology leading to maladaptive cardiac remodeling and heart failure. This study aimed to illuminate the cardioprotective role and mechanisms of a new myokine and adipokine, irisin, in cardiac hypertrophy and remodeling. Adult male wild-type, mouse-FNDC5 (irisin-precursor)-knockout and FNDC5 transgenic mice received 4 weeks of transverse aortic constriction (TAC) alone or combined with intraperitoneal injection of chloroquine diphosphate (CQ). Endogenous FNDC5 ablation aggravated and exogenous FNDC5 overexpression attenuated the TAC-induced hypertrophic damage in the heart, which was comparable to the protection of irisin against cardiomyocyte hypertrophy induced by angiotensin II (Ang II) or phenylephrine (PE). Accumulated autophagosome and impaired autophagy flux occurred in the TAC-treated myocardium and Ang II- or PE-insulted cardiomyocytes. Irisin deficiency caused reduced autophagy and aggravated autophagy flux failure, whereas irisin overexpression or supplementation induced protective autophagy and improved autophagy flux, which were reversed by autophagy inhibitors Atg5 siRNA, 3-MA and CQ. Irisin boosted the activity of only AMPK but not Akt and MAPK family members in hypertrophic hearts and cultured cardiomyocytes and further activated ULK1 at Ser555 but not Ser757 and did not affect the mTOR-S6K axis. Blockage of AMPK and ULK1 with compund C and SBI-0206965, respectively, both abrogated irisin's protection against cardiomyocyte hypertrophic injury and reversed its induction of both autophagy and autophagy flux. Our results suggest that irisin protects against pressure overload-induced cardiac hypertrophy by inducing protective autophagy and autophagy flux via activating AMPK-ULK1 signaling.

SIRT6 protects cardiomyocytes against ischemia/reperfusion injury by augmenting FoxO3α-dependent antioxidant defense mechanisms.

SIRT6, a member of the NAD(+)-dependent class III deacetylase sirtuin family, has been revealed to play important roles in promoting cellular resistance against oxidative stress. The formation of reactive oxygen species (ROS) and oxidative stress are the crucial mechanisms underlying cellular damage and dysfunction in cardiac ischemia/reperfusion (I/R) injury, but the role of SIRT6 in I/R-induced ROS and oxidative stress is poorly understood. In this study, by using heterozygous SIRT6 knockout (SIRT6(+/-)) mice and cultured neonatal cardiomyocyte models, we investigated how SIRT6 mediates oxidative stress and myocardial injury during I/R. Partial knockout (KO) of SIRT6 aggravated myocardial damage, ventricular remodeling, and oxidative stress in mice subjected to myocardial I/R, whereas restoration of SIRT6 expression by direct cardiac injection of adenoviral constructs encoding SIRT6 reversed these deleterious effects of SIRT6 KO in the ischemic heart. In addition, partial deletion of the SIRT6 gene decreased myocardial functional recovery following I/R in a Langendorff perfusion model. Similarly, the protective effects of SIRT6 were also observed in cultured cardiomyocytes following hypoxia/reoxygenation. Intriguingly, SIRT6 was noticed to up-regulate AMP/ATP and then activate the adenosine 5'-monophosphate-activated protein kinase (AMPK)-forkhead box O3α (FoxO3α) axis and further initiated the downstream antioxidant-encoding gene expression (manganese superoxide dismutase and catalase), thereby decreasing cellular levels of oxidative stress and mediating cardioprotection in the ischemic heart. These results suggest that SIRT6 protects the heart from I/R injury through FoxO3α activation in the ischemic heart in an AMP/ATP-induced AMPK-dependent way, thus upregulating antioxidants and suppressing oxidative stress.

Ghrelin inhibits doxorubicin cardiotoxicity by inhibiting excessive autophagy through AMPK and p38-MAPK.

Doxorubicin (DOX) is a wide spectrum antitumor drug, but its clinical application is limited by the cardiotoxicity. Ghrelin, a multi-functional peptide hormone with metabolic regulation in energy homeostasis, plays important roles in cardiovascular protection. Now, the underlying mechanisms of ghrelin against DOX-induced cardiomyocyte apoptosis and atrophy are still not clear. In the present study, we revealed an autophagy-dependent mechanism involved in ghrelin's protection against DOX-induced cardiomyocyte death and size decrease. We observed that DOX insult induced remarkable mortality and cardiac dysfunction in mice, and increase in LDH leakage, cardiomyocyte apoptosis and decrease in cell viability and size in mouse hearts and H9c2 cell cultures, which were effectively improved by ghrelin supplement. We further observed that the strong autophagy stirred by DOX exposure was paralleling with the serious apoptosis and size decrease in cardiomyocytes. Ghrelin, like an autophagy inhibitor, 3-MA, inhibited the DOX-induced autophagy and attenuated cardiomyocyte apoptosis and size decrease. Furthermore, ghrelin significantly reduced the intercellular oxidative stress level, a strong autophagy trigger, partly by augmenting the expression and activities of the endogenous anti-oxidative enzymes. After the further investigation in the post signaling pathways of ghrelin receptors in H9c2 cells, including ERK, p38/MAPK, JNK, AMPK and Akt, we observed that ghrelin supplement only reduced the DOX-activated AMPK and augmented the DOX-down regulated p38-MAPK and mTOR phosphorylation. Our results indicated that ghrelin effectively improved the cardiomyocyte survival and size maintenance by suppressing the excessive autophagy through both ROS inhibition and mTOR induction through suppressing AMPK activity and stimulating p38-MAPK activity.

Salidroside improves doxorubicin-induced cardiac dysfunction by suppression of excessive oxidative stress and cardiomyocyte apoptosis.

Doxorubicin (DOX) is a potent available antitumor drug; however, its clinical use is limited by the cardiotoxicity. Salidroside (SLD), with strong antioxidative and cytoprotective actions, is of particular interest in the development of antioxidative therapies for oxidative injury in cardiac diseases. Now, the protection and underlying mechanisms of SLD against DOX-induced cardiotoxicity are still unknown. In the present study, we revealed both antioxidative mechanism and Bcl2-dependent survival signaling involved in SLD's protection. We observed that DOX exposure induced mortality elevation, body weight loss, and cardiac dysfunction in mice, increased lactate dehydrogenase leakage and cardiomyocyte apoptosis, but decreased cell viability and size in cardiac tissues and cultured H9c2 cells, respectively, which were effectively antagonized by SLD supplement. We further observed that SLD significantly reduced the intercellular oxidative stress level, partly by inhibiting NOX1 expression and augmenting the expression and activities of the endogenous antioxidative enzymes, catalase, and manganese superoxide dismutase. In addition, SLD treatment upregulated the antiapoptotic Bcl2 and downregulated the proapoptotic Bax and inhibited a downstream pathway of Bcl2/Bax and caspase-3 activity. Our results indicated that SLD effectively protected the cardiomyocytes against DOX-induced cardiotoxicity by suppressing the excessive oxidative stress and activating a Bcl2-mediated survival signaling pathway.

[Relationship between polymorphisms of DNA repair gene XRCC1 and susceptibility to radiation injury].

OBJECTIVE: To explore the relationship between polymorphisms of DNA repair gene XRCC1 and susceptibility to radiation injury. METHODS: In 1:1 case-control study, 113 abnormal chromosome workers exposed to ionizing radiation were selected as cases and 113 normal chromosome as controls who matched with case for sex, age (+/- 5 years), nation, type of work, the same or more but in 2 years work length and the same similar levels of the cumulative exposure radiation dose. Genotypes were analysed using PCR based restriction fragment length polymorphism techniques. RESULTS: The frequency of XRCC1 26304TT allele in case group (18.58%) was significantly higher than that in control group (7.08%), with OR for radiation damage being 3.47 (95% CI 1.43 - 8.44, P < 0.05). No association was observed between XRCC1 G27466A and G28152A and susceptibility to radiation injury. CONCLUSION: The mutation of XRCC1 C26304T is related with the susceptibility to radiation injury. The polymorphisms of XRCC1 G27466A and G28152A are not found to have association with abnormal chromosomes.