CD4+ T-Cell Endogenous Cystathionine γ Lyase-Hydrogen Sulfide Attenuates Hypertension by Sulfhydrating Liver Kinase B1 to Promote T Regulatory Cell Differentiation and Proliferation.

BACKGROUND: Hydrogen sulfide (H2S) has antihypertension and anti-inflammatory effects, and its endogenous-generation key enzyme cystathionine γ lyase (CSE) is expressed in CD4+ T cells. However, the role of CD4+ T-cell endogenous CSE/H2S in the development of hypertension is unclear. METHODS: Peripheral blood lymphocytes were isolated from hypertensive patients or spontaneously hypertensive rats, then H2S production and expression of its generation enzymes, cystathionine ß synthase and CSE, were measured to determine the major H2S generation system changes in hypertension. Mice with CSE-specific knockout in T cells (conditional knockout, by CD4cre mice hybridization) and CD4 null mice were generated for investigating the pathophysiological relevance of the CSE/H2S system. RESULTS: In lymphocytes, H2S from CSE, but not cystathionine ß synthase, responded to blood pressure changes, supported by lymphocyte CSE protein changes and a negative correlation between H2S production with systolic blood pressure and diastolic blood pressure, but positive correlation with the serum level of interleukin 10 (an anti-inflammatory cytokine). Deletion of CSE in T cells elevated BP (5-8 mm Hg) under the physiological condition and exacerbated angiotensin II-induced hypertension. In keeping with hypertension, mesenteric artery dilation impaired association with arterial inflammation, an effect attributed to reduced immunoinhibitory T regulatory cell (Treg) numbers in the blood and kidney, thus causing excess CD4+ and CD8+ T cell infiltration in perivascular adipose tissues and kidney. CSE knockout CD4+ T cell transfer into CD4 null mice, also showed the similar phenotypes' confirming the role of endogenous CSE/H2S action. Adoptive transfer of Tregs (to conditional knockout mice) reversed hypertension, vascular relaxation impairment, and immunocyte infiltration, which confirmed that conditional knockout-induced hypertension was attributable, in part, to the reduced Treg numbers. Mechanistically, endogenous CSE/H2S promoted Treg differentiation and proliferation by activating AMP-activated protein kinase. In part, it depended on activation of its upstream kinase, liver kinase B1, by sulfhydration to facilitate its substrate binding and phosphorylation. CONCLUSION: The constitutive sulfhydration of liver kinase B1 by CSE-derived H2S activates its target kinase, AMP-activated protein kinase, and promotes Treg differentiation and proliferation, which attenuates the vascular and renal immune-inflammation, thereby preventing hypertension.

Interaction among Hydrogen Sulfide and Other Gasotransmitters in Mammalian Physiology and Pathophysiology.

Hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO2) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H2S and SO2 are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H2S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO2 production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H2S and other gasotransmitters has been gradually explored. H2S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO2 pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H2S and other gasotransmitters (NO, CO, and SO2) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.

Macrophage-derived sulfur dioxide is a novel inflammation regulator.

Macrophage-mediated inflammation is a key pathophysiological component of cardiovascular diseases, but the underlying mechanisms by which the macrophage regulates inflammation have been unclear. In our study, we, for the first time, showed an endogenous sulfur dioxide (SO2) production in RAW267.4 macrophages by using HPLC and SO2-specific fluorescent probe assays. Moreover, the endogenous SO2 generating enzyme aspartate aminotransferase (AAT) was found to be expressed by the macrophages. Furthermore, we showed that AAT2 knockdown triggered spontaneous macrophage-mediated inflammation, as represented by the increased TNF-α and IL-6 levels and the enhanced macrophage chemotaxis; these effects could be reversed by the treatment with a SO2 donor. Mechanistically, AAT2 knockdown activated the NF-κB signaling pathway in macrophages, while SO2 successfully rescued NF-κB activation. In contrast, forced AAT2 expression reversed AngII-induced NF-κB activation and subsequent macrophage inflammation. Moreover, treatment with a SO2 donor also alleviated macrophage infiltration in AngII-treated mouse hearts. Collectively, our data suggest that macrophage-derived SO2 is an important regulator of macrophage activation and it acts as an endogenous "on-off switch" in the control of macrophage activation. This knowledge might enable a new therapeutic strategy for cardiovascular diseases.

Negative auto-regulation of sulfur dioxide generation in vascular endothelial cells: AAT1 S-sulfenylation.

Recently, endogenous sulfur dioxide (SO2) has been found to exert an important function in the cardiovascular system. However, the regulatory mechanism for SO2 generation has not been entirely clarified. Hence, we aimed to explore the possible auto-regulation of endogenous SO2 generation and its mechanisms in vascular endothelial cells. We showed that SO2 did not affect the protein expression of aspartate aminotransferase 1 (AAT1), a major SO2 synthesis enzyme, but significantly inhibited AAT activity in primary human umbilical vein endothelial cells (HUVECs) and porcine purified AAT1 protein. An AAT1 enzymatic kinetic study showed that SO2 reduced the Vmax (1.89 ± 0.10 vs 2.55 ± 0.12, µmol/mg/min, P < 0.05) and increased the Km (35.97 ± 9.54 vs 19.33 ± 1.76 µmol/L, P < 0.05) values. Furthermore, SO2 induced S-sulfenylation of AAT1 in primary HUVECs and purified AAT1 protein. LC-MS/MS analysis indicated that SO2 sulfenylated AAT1 at Cys192. Mechanistically, thiol reductant DTT treatment or C192S mutation prevented SO2-induced AAT1 sulfenylation and the subsequent inhibition of AAT activity in purified AAT1 protein and primary HUVECs. Our findings reveal, for the first time, a mechanism of auto-regulation of SO2 generation through sulfenylation of AAT1 at Cys192 to suppress AAT activity in vascular endothelial cells. These findings will greatly deepen the understanding of regulatory mechanisms in the cardiovascular homeostasis.

Intermedin alleviates pathological cardiac remodeling by upregulating klotho.

Cardiac remodeling is accompanied by cardiac hypertrophy, fibrosis, dysfunction, and eventually leading to heart failure. Intermedin (IMD), as a paracrine/autocrine peptide, has a protective effect in cardiovascular diseases. In this study, we elucidated the role and the underlying mechanism of IMD in pathological remodeling. Pathological remodeling mouse models were induced by abdominal aorta constriction for 4 weeks or angiotensin II (Ang II) infusion for 2 weeks in wildtype, IMD-overexpression, IMD-knockout and klotho-knockdown mice. Western blot, real-time PCR, histological staining, echocardiography and hemodynamics were used to detect the role of IMD in cardiac remodeling. Cardiac hypertrophy, fibrosis and dysfunction were significantly aggravated in IMD-knockout mice versus wildtype mice, and the expression of klotho was downregulated. Conversely, cardiac remodeling was alleviated in IMD-overexpression mice, and the expression of klotho was upregulated. Hypertension induced by Ang II infusion rather than abdominal aorta constriction was mitigated by IMD. However, the cardioprotective effect of IMD was blocked in klotho-knockdown mice. Similar results were found in cultured neonatal rat cardiomyocytes, which was pretreated with IMD before Ang II stimulation. Mechanistically, IMD inhibited the phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and the activity of calcineurin to protect against cardiac hypertrophy through upregulating klotho in vivo and in vitro. Furthermore, peroxisome proliferator-activated receptor γ (PPARγ) might mediate IMD upregulating klotho. In conclusion, pathological remodeling may be alleviated by endogenous IMD, which inhibits the expression of calcineurin and p-CaMKII by upregulating klotho via the PPARγ pathway. It suggested that IMD might be a therapeutic target for heart disease.

Sulfur Dioxide: An Endogenous Protector Against Myocardial Injury.

Sulfur dioxide (SO2) was previously known as a harmful gas in air pollution. Recently, it was reported that SO2 can be endogenously generated in cardiovascular tissues. Many studies have revealed that endogenous SO2 has important physiological and pathophysiological significance and pharmacological potential. As a novel gasotransmitter, SO2 has important regulatory effects on the heart. It has a dose-dependent negative inotropic effect on cardiac function, in which L-type calcium channels are involved. SO2 can also attenuate myocardial injury caused by various harmful stimuli and play an important role in myocardial ischemia-reperfusion injury and myocardial hypertrophy. These effects are thought to be linked to its ability to reduce inflammation and as an antioxidant. In addition, SO2 regulates cardiomyocyte apoptosis and autophagy. Therefore, endogenous SO2 plays an important role in maintaining cardiovascular system homeostasis. In the present review, the literature concerning the metabolism of endogenous SO2, its cardiac toxicological effects and physiological regulatory effects, mechanisms for SO2-mediated myocardial protection and its pharmacological applications are summarized and discussed.

Irisin ameliorates angiotensin II-induced cardiomyocyte apoptosis through autophagy.

Cardiac hypertrophy is the main cause of heart failure and sudden death in patients. But the pathogenesis is unclear. Angiotensin II may contribute to cardiac hypertrophy in response to pressure overload. In angiotensin II-treated cardiomyocytes, there is a larger cross-sectional area, more apoptosis cells, and a reduction of irisin expression. An increase in P62, an autophagy flux index, as well as LC3II, were observed in cardiomyocytes after angiotensin II-induced injury. Surprisely, irisin supplementation increased LC3II expression and decreased P62 expression, consisted of results of RFP-GFP-LC3B adenovirus transfection, and reduced cardiomyocyte apoptosis, meanwhile, the protection of irisin was reversed by the autophagy inhibitor 3-methyladenine. In animal experiments, overexpression of irisin reduced cardiomyocyte apoptosis and alleviated myocardial hypertrophy caused by pressure overload. The above results indicate that irisin-induced protective autophagy and alleviated the apoptosis signaling pathway in cardiomyocytes, consequently reducing cardiomyocyte apoptosis after angiotensin II-induced injury. Hence, increasing irisin expression may be a new way to improve cardiac function and quality of life in patients with cardiac hypertrophy.

Angiotensin II downregulates vascular endothelial cell hydrogen sulfide production by enhancing cystathionine γ-lyase degradation through ROS-activated ubiquitination pathway.

The interactions between vasoactive peptides and gasotransmitters have attracted considerable attention from scientists. However, the impact of angiotensin II (AngII) on the endogenous hydrogen sulfide/cystathionine γ-lyase (H2S/CSE) pathway in vascular endothelial cells remains unclear. In this study, we found, for the first time, that AngII downregulated the endogenous H2S/CSE pathway in a time-dependent manner. Mechanistically, AngII accelerated the degradation of the CSE protein and shortened its half-life in endothelial cells. AngII significantly induced Lys48 (K48)-linked CSE ubiquitination and subsequent CSE degradation but did not affect Lys63 (K63)-linked CSE ubiquitination in vascular endothelial cells. Treatment with the proteasome inhibitor MG132 and mutation of Lys48 to Arg in ubiquitin successfully blunted the inhibitory effects of AngII on the endogenous H2S/CSE pathway in vascular endothelial cells. Furthermore, we found that superoxide anion levels were significantly increased in AngII-treated endothelial cells compared with controls and that the ROS scavenger N-acetyl-l-cysteine (NAC) significantly abolished CSE ubiquitination. Taken together, our data suggested that AngII inhibited endogenous H2S generation through ubiquitination-mediated CSE degradation via the ROS pathway in vascular endothelial cells.

Acceleration Index Predicts Efficacy of Orthostatic Training on Vasovagal Syncope in Children.

OBJECTIVE: To explore the value of the acceleration index as a predictor of therapeutic response to orthostatic training in children with vasovagal syncope (VVS). STUDY DESIGN: Thirty-three children with VVS were recruited and treated with orthostatic training. The therapeutic response of each patient was evaluated after 3 months of treatment. A Pearson correlation was calculated between the acceleration index and the severity of VVS. The value of the acceleration index in predicting the therapeutic response to orthostatic training was assessed by analysis of the receiver operating characteristic curve. RESULTS: Among the 33 children with VVS, 20 were found to be responders and the remaining were nonresponders. The mean acceleration index was significantly lower in responders compared with nonresponders (21.10 ± 6.61 vs 31.36 ± 9.00; P = .001) and it was negatively correlated with positive response time in the head-up tilt test, with systolic blood pressure and with diastolic blood pressure at positive response time in the head-up tilt test (P < .05). The receiver operating characteristic curve for the predictive value of the acceleration index showed that the area under the curve was 0.827 (95% CI, 0.676-0.978; P = .002), and a cutoff value of the acceleration index of 26.77 yielded a sensitivity of 85.0% and a specificity of 69.2%. CONCLUSIONS: The acceleration index may be useful for predicting the efficacy of orthostatic training on VVS in children.

Endogenous hydrogen sulfide sulfhydrates IKKß at cysteine 179 to control pulmonary artery endothelial cell inflammation.

BACKGROUND: Pulmonary artery endothelial cell (PAEC) inflammation is a critical event in the development of pulmonary arterial hypertension (PAH). However, the pathogenesis of PAEC inflammation remains unclear. METHODS: Purified recombinant human inhibitor of κB kinase subunit ß (IKKß) protein, human PAECs and monocrotaline-induced pulmonary hypertensive rats were employed in the study. Site-directed mutagenesis, gene knockdown or overexpression were conducted to manipulate the expression or activity of a target protein. RESULTS: We showed that hydrogen sulfide (H2S) inhibited IKKß activation in the cell model of human PAEC inflammation induced by monocrotaline pyrrole-stimulation or knockdown of cystathionine γ-lyase (CSE), an H2S generating enzyme. Mechanistically, H2S was proved to inhibit IKKß activity directly via sulfhydrating IKKß at cysteinyl residue 179 (C179) in purified recombinant IKKß protein in vitro, whereas thiol reductant dithiothreitol (DTT) reversed H2S-induced IKKß inactivation. Furthermore, to demonstrate the significance of IKKß sulfhydration by H2S in the development of PAEC inflammation, we mutated C179 to serine (C179S) in IKKß. In purified IKKß protein, C179S mutation of IKKß abolished H2S-induced IKKß sulfhydration and the subsequent IKKß inactivation. In human PAECs, C179S mutation of IKKß blocked H2S-inhibited IKKß activation and PAEC inflammatory response. In pulmonary hypertensive rats, C179S mutation of IKKß abolished the inhibitory effect of H2S on IKKß activation and pulmonary vascular inflammation and remodeling. CONCLUSION: Collectively, our in vivo and in vitro findings demonstrated, for the first time, that endogenous H2S directly inactivated IKKß via sulfhydrating IKKß at Cys179 to inhibit nuclear factor-κB (NF-κB) pathway activation and thereby control PAEC inflammation in PAH.

Association of Circulating Neuregulin-4 with Presence and Severity of Coronary Artery Disease.

Neuregulin-4 (Nrg4) is a newly discovered adipokine that is synthesized in many tissues and plays an important role in modulating systemic energy metabolism and in the development of metabolic disorders. However, little is known about the relationship between Nrg4 and coronary artery disease (CAD). In this study, we investigated the association between Nrg4 and the presence and severity of CAD.We enrolled 73 patients diagnosed by coronary angiography (CAG) as having CAD and 32 controls. The CAD group was divided into two subgroups according to their SYNTAX score. Plasma levels of Nrg4 were measured in all participants and compared among different groups. The relationship between Nrg4 and CAD was analyzed. Receiver operating characteristic (ROC) analysis was conducted to evaluate the usefulness Nrg4 in assessing the presence and severity of CAD.Nrg4 levels were negatively associated with the SYNTAX score (r = -0.401, P = 0.000). The patients with a higher SYNTAX score had significantly lower Nrg4 levels as compared with the low SYNTAX score subgroup and the controls (P < 0.05). The Nrg4 levels of the low SYNTAX score subgroup were much lower than controls (P < 0.05). Furthermore, an association between Nrg4 and CAD (odds ratio, 0.279; 95% confidence interval, 0.088-0.882) was observed. Nrg4 had 43.8% sensitivity and 96.9% specificity for identifying CAD, and 73.1% sensitivity and 87.3% specificity for identifying patients who had severe coronary artery lesions.Nrg4 levels were found to be inversely associated with the presence and severity of CAD.

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.

Head-up tilt test provokes dynamic alterations in total peripheral resistance and cardiac output in children with vasovagal syncope.

AIM: This study examined the total peripheral vascular resistance (TPVR) and cardiac output changes due to the head-up tilt test (HUTT) in children with vasovagal syncope (VVS). METHODS: From December 2013 to January 2016, we recruited 77 children diagnosed with VVS group at Peking University First Hospital, China, and 28 children without VVS provided the control group. Heart rate, blood pressure, TPVR, cardiac output and baroreflex sensitivity were monitored during the HUTT. RESULTS: In the supine position, TPVR and baroreflex sensitivity were higher in the patients with VVS than the controls, but cardiac output did not differ between the two groups. There were obvious increases in the VVS patients from TPVR in the supine position to the prepositive response period (p < 0.05), then the positive response period (p < 0.01). However, we noted the opposite trend in cardiac output, from the supine position to the prepositive response period (p < 0.01) then the positive response period (p < 0.01). CONCLUSION: During HUTT, children with VVS demonstrated increases in TPVR but decreases in cardiac output, during the transition from the supine position to the positive response. This response might be involved in the pathogenesis of VVS.

Left Ventricular Ejection Fraction and Fractional Shortening are Useful for the Prediction of the Therapeutic Response to Metoprolol in Children with Vasovagal Syncope.

The objective of this manuscript was to explore if left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) could predict the efficacy of metoprolol therapy on vasovagal syncope (VVS) in children. Forty-nine children, including 30 with VVS and 19 gender- and age-matched healthy controls, were included in the study. Metoprolol was prescribed to the VVS subjects. The clinical data were obtained during follow-up at 2 and 6 months. The results showed that LVEF and LVFS of responders were significantly higher than those of non-responders both at the 2-month follow-up (LVEF: 72.5 ± 3.2% vs. 64.6 ± 3.4%; LVFS: 40.9 ± 2.3% vs. 34.9 ± 2.9%), and at the 6-month follow-up (LVEF: 72.8 ± 2.8% vs. 65.5 ± 4.6%; LVFS: 41.1 ± 1.9% vs. 35.8 ± 3.6%). The receiver operating characteristic curve (ROC) analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 80% and a specificity of 100% in predicting the therapeutic effectiveness of metoprolol at 2 months. For baseline LVFS, 38.5% as a cutoff value yielded a sensitivity of 90% and a specificity of 90%. At the 6-month follow-up, the ROC analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 81.3% and a specificity of 88.9% in the prediction of metoprolol efficacy. For baseline LVFS, 37.5% as a cutoff value yielded a sensitivity of 93.8% and a specificity of 66.7%. In conclusion, baseline LVEF and LVFS might be useful predictors of the efficacy of ß-blocker therapy on VVS in children.

Cystathionine γ lyase-hydrogen sulfide increases peroxisome proliferator-activated receptor γ activity by sulfhydration at C139 site thereby promoting glucose uptake and lipid storage in adipocytes.

Adipocytes express the cystathionine γ lyase (CSE)-hydrogen sulfide (H2S) system. CSE-H2S promotes adipogenesis but ameliorates adipocyte insulin resistance. We investigated the mechanism of how CSE-H2S induces these paradoxical effects. First, we confirmed that an H2S donor or CSE overexpression promoted adipocyte differentiation. Second, we found that H2S donor inhibited but CSE inhibition increased phosphodiesterase (PDE) activity. H2S replacing isobutylmethylxanthine in the differentiation program induced adipocyte differentiation in part. Inhibiting PDE activity by H2S induced peroxisome proliferator activated receptor γ (PPARγ) protein and mRNA expression. Of note, H2S directly sulfhydrated PPARγ protein. Sulfhydrated PPARγ increased its nuclear accumulation, DNA binding activity and adipogenesis gene expression, thereby increasing glucose uptake and lipid storage, which were blocked by the desulfhydration reagent DTT. H2S induced PPARγ sulfhydration, which was blocked by mutation of the C139 site of PPARγ. In mice fed a high-fat diet (HFD) for 4 weeks, the CSE inhibitor decreased but H2S donor increased adipocyte numbers. In obese mice fed an HFD for 13 weeks, H2S treatment increased PPARγ sulfhydration in adipose tissues and attenuated insulin resistance but did not increase obesity. In conclusion, CSE-H2S increased PPARγ activity by direct sulfhydration at the C139 site, thereby changing glucose into triglyceride storage in adipocytes. CSE-H2S-mediated PPARγ activation might be a new therapeutic target for diabetes associated with obesity.

H2S inhibits pulmonary arterial endothelial cell inflammation in rats with monocrotaline-induced pulmonary hypertension.

This study aimed to determine whether hydrogen sulfide (H2S) inhibits pulmonary arterial endothelial inflammation in rats with monocrotaline (MCT)-induced pulmonary hypertension and its possible mechanisms. Twenty-four male Wistar rats were divided randomly into control, MCT, and MCT+H2S treatment groups. Human pulmonary arterial endothelial cells (HPAEC) were cultured and divided into four groups: control, MCT, MCT+H2S, and H2S. Pulmonary artery pressure was determined using a right cardiac catheterization procedure 3 weeks after MCT administration. Pulmonary vascular morphological changes and inflammatory infiltration were measured. Endogenous H2S levels, cystathionine-γ-lyase (CSE) expression, and inflammatory cytokines were determined both in vivo and in vitro. In addition, phosphorylation of NF-κB p65 and IκBα was detected by western blotting, and NF-κB p65 nuclear translocation, as well as its DNA-binding activity, was determined. Pulmonary hypertension and vascular remolding developed 3 wks after MCT administration, with elevated lung tissue inflammatory infiltration and cytokine level associated with activation of the NF-κB pathway, both in vivo and in vitro. However, the endogenous H2S/CSE pathway was downregulated in MCT rats. By contrast, an H2S donor markedly reduced pulmonary artery pressure, pulmonary vascular structural remolding, and increased lung inflammatory infiltration and cytokine levels of MCT-treated rats. Meanwhile, H2S reversed the activation of the NF-κB pathway successfully. The downregulated pulmonary arterial endothelial H2S/CSE pathway is involved in the pulmonary inflammatory response in MCT-treated pulmonary hypertensive rats. H2S attenuated endothelial inflammation by inhibiting the NF-κB pathway.

Sulphur dioxide suppresses inflammatory response by sulphenylating NF-κB p65 at Cys38 in a rat model of acute lung injury.

The present study was designed to investigate whether endogenous sulphur dioxide (SO2) controlled pulmonary inflammation in a rat model of oleic acid (OA)-induced acute lung injury (ALI). In this model, adenovirus expressing aspartate aminotransferase (AAT) 1 was delivered to the lungs, and the levels of SO2 and proinflammatory cytokines in rat lung tissues were measured. In the human alveolar epithelial cell line A549, the nuclear translocation and DNA binding activities of wild-type (wt) and C38S (cysteine-to-serine mutation at p65 Cys38) NF-κB p65 were detected. GFP-tagged C38S p65 was purified from HEK 293 cells and the sulphenylation of NF-κB p65 was studied. OA caused a reduction in SO2/AAT pathway activity but increased pulmonary inflammation and ALI. However, either the presence of SO2 donor, a combination of Na2SO3 and NaHSO3, or AAT1 overexpression in vivo successfully blocked OA-induced pulmonary NF-κB p65 phosphorylation and consequent inflammation and ALI. Either treatment with an SO2 donor or overexpression of AAT1 down-regulated OA-induced p65 activity, but AAT1 knockdown in alveolar epithelial cells mimicked OA-induced p65 phosphorylation and inflammation in vitro Mechanistically, OA promoted NF-κB nuclear translocation, DNA binding activity, recruitment to the intercellular cell adhesion molecule (ICAM)-1 promoter, and consequent inflammation in epithelial cells; these activities were reduced in the presence of an SO2 donor. Furthermore, SO2 induced sulphenylation of p65, which was blocked by the C38S mutation on p65 in epithelial cells. Hence, down-regulation of SO2/AAT is involved in pulmonary inflammation during ALI. Furthermore, SO2 suppressed inflammation by sulphenylating NF-κB p65 at Cys38.

Intermedin1-53 Attenuates Abdominal Aortic Aneurysm by Inhibiting Oxidative Stress.

OBJECTIVE: Oxidative stress plays a critical role in the development of abdominal aortic aneurysm (AAA). Intermedin (IMD) is a regulator of oxidative stress. Here, we investigated whether IMD reduces AAA by inhibiting oxidative stress. APPROACH AND RESULTS: In angiotensin II-induced ApoE-/- mouse and CaCl2-induced C57BL/6J mouse model of AAA, IMD1-53 significantly reduced the incidence of AAA and maximal aortic diameter. Ultrasonography, hematoxylin, and eosin staining and Verhoeff-van Gieson staining showed that IMD1-53 significantly decreased the enlarged aortas and elastic lamina degradation induced by angiotensin II or CaCl2. Mechanistically, IMD1-53 attenuated oxidative stress, inflammation, vascular smooth muscle cell apoptosis, and matrix metalloproteinase activation. IMD1-53 inhibited the activation of redox-sensitive signaling pathways, decreased the mRNA and protein expression of nicotinamide adenine dinucleotide phosphate oxidase subunits, and reduced the activity of nicotinamide adenine dinucleotide phosphate oxidase in AAA mice. Expression of Nox4 was upregulated in human AAA segments and in angiotensin II-treated mouse aortas and was markedly decreased by IMD1-53. In vitro, vascular smooth muscle cells with small-interfering RNA knockdown of IMD showed significantly increased angiotensin II-induced reactive oxygen species, and small-interfering RNA knockdown of Nox4 markedly inhibited the reactive oxygen species. IMD knockdown further increased the apoptosis of vascular smooth muscle cells and inflammation, which was reversed by Nox4 knockdown. Preincubation with IMD17-47 and protein kinase A inhibitor H89 inhibited the effect of IMD1-53, reducing Nox4 protein levels. CONCLUSIONS: IMD1-53 could have a protective effect on AAA by inhibiting oxidative stress.

Expressions of irisin and urotensin II and their relationships with blood pressure in patients with preeclampsia.

The aims of this study are to observe irisin and urotensin II (UII) levels in serum and placenta in normal pregnant and preeclamptic women and investigate the relationship between expressions irisin and UII, and their association with blood pressure. A total of 67 pregnant subjects were recruited, including 31 healthy and 36 preeclamptic pregnant women. Serum irisin and UII concentrations were measured. Expressions of fibronectin type III domain-containing protein 5 (FNDC5) (irisin precursor) and UII in placenta specimens were performed. There was no significant difference of serum irisin levels between severe preeclamptic (SPE)) patients, mild preeclamptic (MPE) patients and normal controls, while serum UII was significantly higher in preeclamptic women than normal pregnancy. There was no relationship between serum UII and irisin levels. In patients with preeclampsia, serum irisin was negatively associated with systolic and diastolic blood pressure(r = -0.350, P = 0.004, r = -0.307, P = 0.011), while serum UII was positively associated with systolic blood pressure (r = 0.291, P = 0.031). Serum irisin, UII, urinary protein level, BMI and serum creatinine were the independent determinants of blood pressure in preeclampsia by multiple regression analysis. Protein expression of FNDC5 and UII was upregulated in placenta of patients with SPE and positively correlated with systolic blood pressure and urinary protein level. We firstly verify that serum irisin and placental irisin precursor expressions have differently correlated with blood pressure. Expressions of irisin and urotensin II have relationships with blood pressure in patients with preeclampsia.

Serum Resistin Negatively Correlates with Clinical Severity of Postural Tachycardia Syndrome in Children.

This study was designed to analyse the serum resistin level in children with postural tachycardia syndrome (POTS) and its clinical significance. Twenty-one children with POTS and 31 healthy children as controls participated in the study. Clinical characteristics, heart rate and blood pressure in the supine and upright positions were monitored and collected during an upright test, and the symptom scoring of POTS patients was recorded. The serum resistin levels of patients in both groups were determined by enzyme-linked immunosorbent assay. The change in serum resistin levels in the POTS group before and after standing, as well as its correlation with symptom scores and change in heart rate after standing, was analysed. Compared with the control group, the serum resistin levels in the POTS group were significantly increased (P < 0.01). The serum resistin levels in the POTS group before and after standing did not differ (P > 0.05). There was a negative correlation between the serum resistin levels and a change in heart rate from the supine to upright position (correlation coefficient = -0.615, P < 0.01). Moreover, serum resistin levels were negatively correlated with symptom scores (correlation coefficient = -0.493, P < 0.05). Serum resistin levels in children with POTS were significantly higher than those in healthy children and negatively correlated with a change in heart rate from the supine to upright position and symptom scores. These results suggest a protective role of increased resistin in the pathogenesis of POTS.