Hydrogen Sulfide Inhibits Bronchial Epithelial Cell Epithelial Mesenchymal Transition Through Regulating Endoplasm Reticulum Stress

Epithelial mesenchymal transition (EMT) is a contributing factor in remodeling events of chronic obstructive pulmonary disease (COPD). Hydrogen sulfide (H₂S) has been implicated in the pathogenesis of COPD, but the effect of H₂S in regulating EMT and the underlying mechanisms is not clear. In this study, we assessed endoplasmic reticulum (ER) stress markers, EMT markers and associated signal molecules in rat lungs, bronchial epithelial cells, and human peripheral lung tissues to investigate the effect of H₂S in regulating EMT and the underlying mechanisms. We found that EMT and ER stress occurred in lung epithelial cells, especially in the bronchial epithelial cells of smokers and COPD patients. In cigarette smoke (CS)-exposed rats, intraperitoneal injection of NaHS significantly alleviated CS-induced lung tissue damage, small airway fibrosis, ER stress, and EMT, while intraperitoneal injection of propargylglycine (cystathionine-gamma-lyase inhibitor) aggravated these effects induced by CS. In the nicotine-exposed 16HBE cells, an appropriate concentration of H₂S donor not only inhibited nicotine-induced ER stress, but also inhibited nicotine-induced enhancement of cell migration ability and EMT. ER stress nonspecific inhibitors taurine and 4-phenyl butyric acid also inhibited nicotine-induced enhancement of cell migration ability and EMT. Both H2S and inositol-requiring enzyme 1 (IRE1) activation inhibitor 4μ8C inhibited nicotine-induced activation of IRE1, Smad2/3 and EMT. These results suggest that H₂S inhibits CS- or nicotine-induced ER stress and EMT in bronchial epithelial cells and alleviates CS-induced lung tissue damage and small airway fibrosis. The IRE1 signal pathway and Smad2/3 may be responsible for the inhibitory effect of H₂S.

[Chlamydia psittaci pneumonia complicated with rhabdomyolysis: a case report and literature review]

Objective: To analyze the clinical characteristics and the diagnosis and treatment of Chlamydia psittaci pneumonia complicated with rhabdomyolysis. Methods: We reported a case of Chlamydia psittaci pneumonia complicated with rhabdomyolysis. We did a literature review on the published reports between January 1978 and May 2020 by searching with the key words of "psittacosis" or "Chlamydia psittaci" and "rhabdomyolysis" in the PubMed database (time frame: January 1, 1967 to May 30, 2020). Results: Our patient was a 64-year-old male presenting with high-grade fever, fatigue, myalgia and dyspnea. A computed tomographic scan of the chest revealed bilateral pneumonia, which was further complicated with rhabdomyolysis during disease progression. This prompted the metagenomic next-generation sequencing, revealing the sequences of Chlamydia psittaci in both the bronchoalveolar lavage fluid and blood. Of the 11 cases in the 3 literature reports that we retrieved, 5 had concomitant rhabdomyolysis (two of which did not have complete clinical information), and the other 6 cases had myositis complicated with an elevated level of creatine phosphokinase. This yielded 3 cases with complete clinical information for our analysis. We had further incorporated their information with the single case managed within our study site. Two were males and the other 2 were females. The patients were aged 66, 46, 44 and 64 years, respectively. All cases had fever and 3 had a contact history with live poultry. Two cases had myalgia and progressed rapidly into having respiratory failure, and the other 2 cases did not develop myalgia and improved significantly after a timely treatment. All 4 cases were cured and discharged after treatment with appropriate antibiotics. No adverse outcomes were observed. Conclusions: The prognosis of Chlamydia psittaci pneumonia complicated with rhabdomyolysis was poor in case of a delayed treatment. Early diagnosis would help reduce the mortality.

Deficiency of peroxisome proliferator-activated receptor α attenuates apoptosis and promotes migration of vascular smooth muscle cells

Peroxisome proliferator-activated receptor (PPAR) α is widely expressed in the vasculature and has pleiotropic and lipid-lowering independent effects, but its role in the growth and function of vascular smooth muscle cells (VSMCs) during vascular pathophysiology is still unclear. Herein, VSMC-specific PPARα-deficient mice (Ppara ^ΔSMC) were generated by Cre-LoxP site-specific recombinase technology and VSMCs were isolated from mice aorta. PPARα deficiency attenuated VSMC apoptosis induced by angiotensin (Ang) II and hydrogen peroxide, and increased the migration of Ang II-challenged cells.

Ghrelin inhibited pressure overload-induced cardiac hypertrophy by promoting autophagy via CaMKK/AMPK signaling pathway

Ghrelin, a novel gut hormone, has been shown to exert protective effects on cardiac dysfunction and remodeling. However, the underlying mechanisms of its protective effects remain unclear. Here, we investigated the effects of ghrelin on cardiac hypertrophy and explored the mechanisms involved. Ghrelin (30 μg.kg^-1. day^-1) was systemically administered to rats with cardiac hypertrophy induced by abdominal aortic constriction (AAC) by a mini-osmotic pump the next day after surgery continuously for 4 weeks. The AAC treated rats without ghrelin infusion showed decreased ghrelin content and expression of its receptors in the hearts. Exogenous ghrelin greatly attenuated cardiac hypertrophy as shown by heart weight to tibial length (HW/TL), hemodynamics, echocardiography, histological analyses, and expression of hypertrophic markers induced by AAC. This corresponded with decreased cardiac fibrosis and inflammation in the hearts of AAC rats treated with ghrelin. Moreover, ghrelin significantly increased the myocardial expression of autophagy markers, which was further confirmed in cultured cardiomyocytes. Concurrently, cardiomyocyte apoptosis in vivo and in vitro was ameliorated by ghrelin, which was reversed by inhibition of autophagy. The enhancement of autophagy and inhibition of apoptosis by ghrelin were eliminated on pretreatment with compound C, an AMP-activated protein kinase (AMPK) inhibitor. Furthermore, inhibition of Ca²⁺/Calmodulin-dependent protein kinase kinase (CaMKK), an upstream kinase of AMPK, made ghrelin fail to activate AMPK and simultaneously reversed ghrelin's promotion of autophagy. In conclusion, ghrelin could exert its cardioprotective effects on cardiac hypertrophy by promoting autophagy, possibly via CaMKK/AMPK signaling pathway.

Hydrogen Sulfide Attenuates Particulate Matter-Induced Emphysema and Airway Inflammation Through Nrf2-Dependent Manner

Purpose

To investigate whether hydrogen sulfide provide protective effects on atmosphere particulate matter (PM)-induced emphysema and airway inflammation and its mechanism.

Methods

Wild type C57BL/6 and Nrf2 knockout mice were exposed to PM (200 µg per mouse). Hydrogen sulfide or propargylglycine were administered by intraperitoneal injection respectively 30 min before PM exposure, mice were anesthetized 29th day after administration. Mice emphysema, airway inflammation, and oxidative stress were evaluated, the expression of NLRP3, active caspase-1, and active caspase-3 were detected. Alveolar epithelial A549 cells line were transfected with control small interfering RNA (siRNA) or Nrf2 siRNA and then incubated with or without hydrogen sulfide for 30 min before exposed to fine particulate matter for 24 h, cell viability, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling (TUNEL) assay, the secretion of interleukin (IL)-1β, ASC speck formation, the expression level of NLRP3, active caspase-1, and active caspase-3 were measured.

Results

PM significantly increased mice emphysema and airway inflammation measured by mean linear intercept, alveolar destroy index and total cell, neutrophil counts, cytokines IL-6, tumor necrosis factor (TNF)-α, CXCL1, IL-1β in bronchoalveolar lavage fluid. PM-induced mice emphysema and airway inflammation was greatly attenuated by hydrogen sulfide, while propargylglycine aggravated that. PM-induced oxidative stress was reduced by hydrogen sulfide as evaluated by 8-OHdG concentrations in lung tissues. The expression of NLRP3, active caspase-1, and active caspase-3 enhanced by PM were also downregulated by hydrogen sulfide in mice lung. The protective effect of hydrogen sulfide on emphysema, airway inflammation, inhibiting oxidative stress, NLRP3 inflammasome formation, and anti-apoptosis was inhibited by Nrf2 knockout in mice. Similarly, hydrogen sulfide attenuated the secretion of IL-1β, NLRP3 expression, caspase-1 activation, ASC speck formation, and apoptosis caused by fine particulate matter exposure in A549 cells but not in Nrf2 silenced cells.

Conclusion

Hydrogen sulfide played a protect role in PM-induced mice emphysema and airway inflammation by inhibiting NLRP3 inflammasome formation and apoptosis via Nrf2-dependent pathway.

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.

A potentially functional variant of ARID1B interacts with physical activity in association with risk of hepatocellular carcinoma

The tumor suppressor role of AT-rich interactive domain containing protein 1B (ARID1B) has drawn much attention in area of cancer etiology. However, it had remained unknown whether or not genetic variants of ARID1B involved in development of hepatocellular carcinoma (HCC). In this study, three putatively functional variants in ARID1B (rs73013281C>T, rs167007A>G, and rs9397984C>T) were selected using bioinformatics tools, and a case-control study of 611 cases and 614 controls was conducted to investigate genetic associations with HCC risk in a Southern Chinese population. Two-dimensional gene-environment interactions were also explored using both multiplicative and additive scales. A dominant effect of the rs73013281 was found for HCC risk, with an adjusted odds ratio (OR) of 1.70 [95% confidence interval (CI) = 1.03-2.80] for the CT/TT genotypes compared to the CC genotype. In stratified analysis, the detrimental effect of the T allele on elevated HCC risk was attenuated by physical activity, with an adjusted OR of 2.75 (95% CI = 1.39-5.41) among inactive individuals against that of 0.89 (95% CI = 0.42-1.91) in those who exercised regularly. Expectably, the rs73013281 showed both multiplicative and additive interactions with physical activity (P = 0.037 and 0.006, respectively). In conclusion, these results highlighted the significant genetic contribution of the ARID1B variant, rs73013281, to susceptibility for HCC, especially in interaction with physical activity.

[Downregulation of large conductance calcium-activated potassium channels in paraventricular nucleus contributes to sympathoexcitation in rats with chronic heart failure]

Objective: To elucidate the association between large conductance calcium-activated potassium channels (BK_Ca) in the paraventricular hypothalamic nucleus (PVN) and sympathetic outflow in rats with chronic heart failure (CHF) . Methods: Male Wistar rats (6-7 weeks old) were randomized to sham operated group and CHF group (coronary artery ligation) . Two weeks after operation, BK_Ca inhibitor Iberiotoxin (IBTX) was infused into PVN by osmotic minipumps, rats were divided into following groups: sham+aCSF, CHF+aCSF, sham+low dose IBTX (0.125 nmol/nl) , CHF+low dose IBTX, sham+moderate dose IBTX (1.25 nmol/nl) , CHF+moderate dose IBTX, sham+ high dose IBTX (12.5 nmol/nl) , and CHF+high dose IBTX (n=6 each) . Additional rats were grouped as follows: sham+vehicle, sham+KCNMB4 knockdown (by rAAV2-KCNMB4 shRNA virus injection in PVN) , CHF+vehicle, CHF+ KCNMB4 knockdown group (n=6 each) . The cardiac function was determined by echocardiography, left ventricular hemodynamics were measured invasively, renal sympathetic nerve activity (RSNA) was recorded at 6 weeks after coronary artery ligation or sham operation. The contents of norepinephrine (NE) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in plasma were determined by enzyme-linked immunosorbent assay. The protein and mRNA expression of KCNMB4 in PVN were measured by immunofluorescence staining, Western blot, and real-time PCR, mRNA expression of BK_Ca in PVN was detected by real-time PCR. Results: Compared with the sham operation group, the cardiac function of the heart failure group was significantly reduced (P<0.05) , and the plasma NE and the serum NT-proBNP were significantly elevated (P<0.05) . The protein and mRNA expression of KCNMB4 in PVN were obviously down-regulated in CHF rats (P<0.05) . After perfusion of IBTX or KCNMB4 knockdown by microinjection of rAAV2-KCNMB4 shRNA virus,right ventricular weight/body weight and lung weight/body weight ratio as well as left ventricular end-diastolic diameter were increased and left ventricular ejection fraction was decreased (all P<0.05) , the sympathetic driving indexes was increased in sham rats, changes of these parameters further aggravated in CHF rats (P<0.05) . KCNMB4 knockdown further downregulated protein expression in PVN of CHF rats. Conclusion: Downregulation and blunted function of BK_Ca in PVN may contribute to sympathoexcitation and deterioration of cardiac function in rats with chronic heart failure.

Intermedin1-53 Protects Cardiac Fibroblasts by Inhibiting NLRP3 Inflammasome Activation During Sepsis

Sepsis is a disease that occurs as a result of systemic inflammatory response syndrome (SIRS) in response to an infection, contributing to multiple organ dysfunction and a high mortality rate. Interleukin-lβ (IL-1β) is a cytokine that plays critical roles in inflammation and cardiac dysfunction during severe sepsis. Intermedin_1-53 (IMD_1-53) has been recently discovered to possess potential endogenous anti-inflammatory and strong cardiovascular protective effects. To investigate whether IMD_1-53 can inhibit the NLRP3/caspase-1/IL-1β pathway to alleviate cardiac injury and rescue heart function, sepsis was induced in vivo by caecal ligation and puncture (CLP) surgery, and lipopolysaccharides were used as septic stressors for cardiac fibroblasts (CFs) in vitro. The expressions of IMD_1-53 receptors in sepsis rat heart were increased. After IMD_1-53 treatment, inflammation caused by sepsis in vivo was greatly reduced, as shown by the downregulation of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), nucleotide-binding domain and leucine-rich repeat containing family, pyrin containing 3 (NLRP3), pro-IL-1β, caspase 1, and nuclear translocation of nuclear factor-κB (NF-kB) protein levels. In addition, cardiac function was significantly improved and mean arterial blood pressure (MABP) increased by 34.8% (P < 0.05) which almost back to normal. Surprisingly, IMD_1-53 inhibited cell apoptosis, as caspase 3 activity and Bax expression was significantly reduced in the heart upon IMD_1-53 treatment. IMD_1-53 abolished the upregulation of ASC, NLRP3, and caspase 1 protein levels in CFs induced by lipopolysaccharide (LPS). IMD_1-53 increased cell survival rates and inhibited IL-1β production in the cell culture medium. IMD_1-53 can protect against inflammation and heart injury during sepsis via attenuating the NLRP3/caspase-1/IL-1β pathway.

Hydrogen Sulfide Inhibits Cigarette Smoke-Induced Endoplasmic Reticulum Stress and Apoptosis in Bronchial Epithelial Cells

Background: Apoptosis of lung structural cells contributes to the process of lung damage and remodeling in chronic obstructive pulmonary disease (COPD). Our previous studies demonstrated that exogenous hydrogen sulfide (H₂S) can reduce the lung tissue pathology score, anti-inflammation and anti-oxidation effects in COPD, but the effect of H₂S in regulating cigarette smoke (CS) induced bronchial epithelial cell apoptosis and the underlying mechanisms are not clear.

Objectives: To investigate the effect of H₂S on CS induced endoplasmic reticulum stress (ERS) and bronchial epithelial cell apoptosis.

Methods: Male Sprague–Dawley rats randomly divided into four groups for treatment: control, CS, NaHS + CS, and propargylglycine (PPG) + CS. The rats in the CS group were exposed to CS generated from 20 commercial unfiltered cigarettes for 4 h/day, 7 days/week for 4 months. Since the beginning of the third month, freshly prepared NaHS (14 μmol/kg) and PPG (37.5 mg/kg) were intraperitoneally administered 30 min before CS-exposure in the NaHS and PPG groups. 16HBE cells were pretreated with Taurine (10 mM), 5 mmol/L 4-phenylbutyric acid (4-PBA) or NaHS (100, 200, and 400 μM) for 30 min, and then cells were exposed to 40 μmol/L nicotine for 72 h. ERS markers (GRP94, GRP78) and ERS-mediated apoptosis markers 4-C/EBP homologous protein (CHOP), caspase-3 and caspase-12 were assessed in rat lung tissues and human bronchial epithelial cells. The apoptotic bronchial epithelial cells were detected by Hoechst staining in vitro and TUNEL staining in vivo.

Results: In CS exposed rats, peritoneal injection of NaHS significantly inhibited CS induced overexpression ERS-mediated apoptosis markers and upregulation of apoptotic rate in rat lungs, and inhibiting the endogenous H2S production by peritoneal injection of PPG exacerbated these effects. In the nicotine-exposed bronchial epithelial cells, appropriate concentration of NaHS and ERS inhibitors taurine and 4-PBA inhibited nicotine-induced upregulation of apoptotic rate and overexpression of ERS-mediated apoptosis markers.

Conclusion: H₂S inhibited lung tissue damage by attenuating CS induced ERS in rat lung and exogenous H₂S attenuated nicotine induced ERS-mediated apoptosis in bronchial epithelial cells.

Combined Assessment of Relaxin and B-Type Natriuretic Peptide Improves Diagnostic Value in Patients With Congestive Heart Failure

BACKGROUND

To improve the poor prognosis of congestive heart failure (CHF), early and accurate diagnosis is necessary. Relaxin is an endogenous cardiovascular peptide, and its plasma level is usually increased in patients with CHF. In this pilot study, we aimed to determine the diagnostic value of relaxin and B-type natriuretic peptide (BNP) in patients with and without CHF.

MATERIALS AND METHODS

The plasma level of relaxin was measured by enzyme-linked immunosorbent assay and plasma level of BNP by fluorescence immunoassay. The area under the receiver operating characteristic curve was used to assess the diagnostic value of relaxin and BNP.

RESULTS

We included 81 patients with decompenstated CHF and 36 controls. Plasma levels of relaxin and BNP were both higher in CHF patients than in controls. The correlation between plasma levels of relaxin and BNP and between relaxin or BNP and cardiac function was nonlinear. Relaxin had medium diagnostic value, and BNP had higher value for cardiac function and CHF. At a cutoff of 39.76pg/mL relaxin, sensitivity was 82.7%, specificity 55.6%, sum of the highest positive predictive value 80.5% and negative predictive value 58.8%. Although the diagnostic value was not better for relaxin than BNP, their combined assessment improved the sensitivity and specificity of diagnosis for CHF as compared with BNP alone.

CONCLUSIONS

Combined assessment of relaxin and BNP may improve the diagnosis of decompensated CHF, which may have potential application in the clinic.

[Role and mechanism of hydrogen sulfide in cigarette smoke induced chronic obstructive pulmonary disease related pulmonary vascular remodeling in rats]

Objective: To investigate the role and mechanism of hydrogen sulfide (H2S) in rats with chronic obstructive pulmonary disease (COPD) related pulmonary vascular remodeling. Methods: Twenty four healthy male Sprague-Dawley rats were randomly divided into 4 groups: control group, cigarette smoke (CS) group, CS+ Sodium hydrosulfide (NaHS) group and CS+ DL-propargylglycine (PPG) group. Rats in control group were fed normally and breathed clear air, and for the rest groups, passive cigarette smoke inhalation method were adopted to establish COPD model. After 8 weeks, the rats in corresponding groups were treated by NaHS or PPG. After 16 weeks, the markers of pulmonary vascular remodeling in all groups were measured. Proliferation marker proliferative cell nuclear antigen (PCNA) and oxidative stress marker 3-neurotrophin (3-NT) in all groups were measured by immunohistochemistry (IHC). Results: Compared with control group, the airway resistance was increased (0.859±0.283 vs 0.578±0.088, P<0.05) and the pathological scores was much higher in CS group, which suggested that the COPD model was successful. The degree of small resistance pulmonary artery medial wall thickness and full vascular muscularization of CS group were much higher (0.54±0.20 vs 0.37±0.12, 0.39±0.08; 0.61±0.16 vs 0.20±0.12, 0.34±0.13, all P<0.01)than control group and CS+ NaHS group, there was no significant difference between CS+ PPG group and CS group. In accordance with the results of morphometric analysis, the proliferation marker PCNA was more in CS group when compared with control group and CS+ NaHS group (0.27±0.08 vs 0.12±0.06, 0.14±0.06, both P<0.05), there was no significant difference between CS+ PPG group and CS group. Furthermore, the IHC also showed that 3-NT significantly increased in CS group compared with control group and CS+ NaHS group (0.26±0.08 vs 0.18±0.04, 0.19±0.06, both P<0.01), there was no significant difference between CS+ PPG group and CS group as well. In addition, the small resistance pulmonary artery medial wall thickness had strong correlation with the expression level of oxidative stress marker 3-NT (r=0.906, P<0.001). Conclusion: H2S significantly attenuates cigarette smoke induced COPD related pulmonary vascular remodeling, which could be related to its ability to decrease oxidative stress.

Prognostic Value of Plasma Intermedin Level in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome

Intermedin (IMD), an autocrine/paracrine biologically active peptide, plays a critical role in maintaining vascular homeostasis. Recent research has shown that high plasma levels of IMD are associated with poor outcomes for patients with ST-segment elevation acute myocardial infarction. However, the prognostic utility of IMD levels in non-ST-segment elevation acute coronary syndrome (NSTE-ACS) has not yet been investigated. We hypothesized that the level of plasma IMD would have prognostic value in patients with NSTE-ACS. Plasma IMD was determined by radioimmunoassay in 132 NSTE-ACS patients on admission to hospital and 132 sex- and age-matched healthy-control subjects. Major adverse cardiovascular events (MACEs), including death, heart failure, hospitalization, and acute myocardial infarction, were noted during follow-up. In total, 23 patients suffered MACEs during the follow-up period (mean 227 ± 118 days, range 2-421 days). Median IMD levels were higher in NSTE-ACS patients than control [320.0 (250.9/384.6) vs. 227.2 (179.7/286.9) pg/mL, P <0.001]. The area under the receiver-operating characteristic curve for IMD and N-terminal pro-B-type brain natriuretic peptide (NT-proBNP) did not significantly differ (0.73 and 0.79, both P <0.001, respectively; P = 0.946). ROC curve analysis revealed a cut-off value for IMD at 340.7 pg/mL. Cox regression analysis with cardiovascular risk variables and NT-proBNP showed that the risk of MACEs increased by a factor of 12.96 (95% CI, 3.26-49.42; P <0.001) with high IMD levels (at the cut-off value). IMD has potential as a prognostic biomarker for predicting MACEs in patients with NSTE-ACS.

Endogenous Sulfur Dioxide Inhibits Vascular Calcification in Association with the TGF-β/Smad Signaling Pathway

The study was designed to investigate whether endogenous sulfur dioxide (SO₂) plays a role in vascular calcification (VC) in rats and its possible mechanisms. In vivo medial vascular calcification was induced in rats by vitamin D3 and nicotine for four weeks. In vitro calcification of cultured A7r5 vascular smooth muscle cells (VSMCs) was induced by calcifying media containing 5 mmol/L CaCl₂. Aortic smooth muscle (SM) α-actin, runt-related transcription factor 2 (Runx2), transforming growth factor-β (TGF-β) and Smad expression was measured. VC rats showed dispersed calcified nodules among the elastic fibers in calcified aorta with increased aortic calcium content and alkaline phosphatase (ALP) activity. SM α-actin was markedly decreased, but the osteochondrogenic marker Runx2 concomitantly increased and TGF-β/Smad signaling was activated, in association with the downregulated SO₂/aspartate aminotransferase (AAT) pathway. However, SO₂ supplementation successfully ameliorated vascular calcification, and increased SM α-actin expression, but inhibited Runx2 and TGF-β/Smad expression. In calcified A7r5 VSMCs, the endogenous SO₂/AAT pathway was significantly downregulated. SO₂ treatment reduced the calcium deposits, calcium content, ALP activity and Runx2 expression and downregulated the TGF-β/Smad pathway in A7r5 cells but increased SM α-actin expression. In brief, SO₂ significantly ameliorated vascular calcification in association with downregulation of the TGF-β/Smad pathway.

[Hydrogen sulfide attenuates bronchial epithelial cell apoptosis by inhibiting endoplasmic reticulum stress]

OBJECTIVE

To explore the effects of hydrogen sulfide on nicotine-induced bronchial epithelial cell endoplasmic reticulum (ER) stress and apoptosis.

METHODS

Nicotine was used to establish the apoptotic model in human bronchial epithelial cell line (16HBE) for mimicing the effect of cigarette smoke on apoptosis. The 16HBE cells were grouped by the concentration gradients of 0 (control), 5, 10, 20, 40, 80 µmol/L nicotine dosing. All groups were treated for 72 h. And 16HBE cells were grouped by the time gradients of 0 (control), 24, 48, 72 h of nicotine dosing. For control group, the nicotine concentration was 40 µmol/L. Then the protein expression level of CCAAT/enhancer binding protein homologous protein (CHOP) was measured by Western blot to define the effect of various concentrations of nicotine and different dosing periods of nicotine on the protein expression level of CHOP. For observing the role of hydrogen sulfide in ER stress-mediated apoptosis, 16HBE cells were divided into 6 groups of control, 40 µmol/L nicotine, 100 µmol/L sodium hydrosulfide (NaHS) + 40 µmol/L nicotine, 200 µmol/L NaHS + 40 µmol/L nicotine, 400 µmol/L NaHS + 40 µmol/L nicotine and 10 mmol/L taurine + 40 µmol/L nicotine. NaHS or taurine was pretreated for 30 min and then nicotine dosed for 72 h. The protein expression levels of GRP78 and ER stress-mediated apoptosis markers, such as cleaved caspase-12 and CHOP, were measured by Western blot. And chromatin dye Hoechst 33258 was used to detect the morphological changes of apoptotic 16HBE cells and apoptotic index calculated.

RESULTS

Nicotine could concentration and time-dependently improve the expression of CHOP in 16HBE cells. The ratio of CHOP to average absorbance of glyceraldehyde phosphate dehydrogenase (GAPDH) was significantly higher in 40 µmol/L nicotine group than that in control group (1.04 ± 0.32 vs 0.30 ± 0.17, P < 0.05). The ratio of GRP78 to average absorbance of β-actin (0.59 ± 0.19 vs 1.00 ± 0.08), cleaved caspase-12 to average absorbance of procaspase-12 (0.06 (0.01, 6.06) vs 20.30(12.79, 23.78)) and CHOP to average absorbance of β-actin (0.18 ± 0.10 vs 0.53 ± 0.09) in 200 µmol/L NaHS + 40 µmol/L nicotine group were all significantly lower than those in 40 µmol/L nicotine group (all P < 0.05). The apoptotic index in 200 µmol/L NaHS + 40 µmol/L nicotine group (3.04 ± 1.83 vs 16.60 ± 3.32) and apoptotic index in 10 mmol/L taurine + 40 µmol/L nicotine group (4.08 ± 2.04 vs 16.60 ± 3.32) were significantly lower than those in 40 µmol/L nicotine group (all P < 0.01).

CONCLUSIONS

NaHS exerts its protection against nicotine-induced bronchial epithelial cell apoptosis through suppressing ER stress. And the underlying mechanism may be through a down-regulation of ER stress-mediated apoptosis markers of cleaved caspase-12 and CHOP.

[Role of cortistain alternation in rats with chronic obstructive pulmonary disease]

OBJECTIVE

To explore the role of cortistatin (CST) in rats with chronic obstructive pulmonary disease (COPD).

METHODS

A total of 16 healthy male Sprague-Dawley rats were randomly divided into control and COPD model groups (n=8 each). The COPD model group received an inhalation of passive smoking while the control group was treated normally. After 4 months, pulmonary function was measured. The differential cell counts of bronchoalveolar lavage fluid (BALF) were detected. Morphology and pathology of lungs were studied via hematoxylin and eosin staining. The levels of CST in lung tissue, serum and BALF were detected by radioimmunoassay.

RESULTS

Compared with the control group, the COPD group had obviously higher airway resistance and neutrophil ratio in BALF [(0.584 ± 0.021) vs (0.653 ± 0.062) mmHg·ml⁻¹·s⁻¹, 1.49% vs 0.41%, both P<0.05]. And there were significantly serious inflammation and emphysema in lung tissues. Moreover, the levels of CST increased in serum, BALF and lung tissues [(526 ± 76) vs (453 ± 41)pg/ml, (819 ± 100) vs (619 ± 101)pg/ml, (41 ± 10) vs (20 ± 7)pg/mg, all P<0.05] respectively as compared with the controls.

CONCLUSION

An elevated level of CST may compensate to exert anti-inflammation effects in COPD rats.

Impaired regulator of G protein signaling 2 transcription facilitates vascular remodeling in injured rat aorta

BACKGROUND

The activation of Gq-protein-coupled receptors induces proliferation of vascular smooth muscle cells (VSMCs) proliferation and is involved in vascular remodeling. The regulator of G protein signaling 2 (RGS2), which accelerates the termination of Gq protein signaling, may play a role in vascular remodeling. However, this role remains unclear.

METHODS

Aortic balloon injury or sham operation was produced in male Wistar rats. Histological examination and gene expression analysis were performed after surgery. In cultured VSMCs after modulation of RGS2 expression, cell proliferation was also evaluated.

RESULTS

At day 3 after injury, RGS2 transcription was reduced by 52.8% (P <0.05 vs. sham group) with vascular remodeling. In cultured VSMCs stimulated by endothelin-1, phenylephrine or angiotensin II, the proliferation of RGS2 overexpressed cells was significantly inhibited; the proliferation of RGS2 downregulated cells was significantly promoted, compared with that of RGS2 normal cells. Moreover, after incubation with angiotensin II of high concentration (>10 μmol/l) or long term (>8 h), the RGS2 expression was clearly downregulated in cultured VSMCs. Administration of an angiotensin receptor blocker, valsartan (20 mg/kg per day) starting from 1 week preballoon injury to 3 days after injury, restored aortic RGS2 transcription and improved vascular remodeling.

CONCLUSION

These results suggested that the inhibiting effect of RGS2 on VSMC proliferation is downregulated in vascular remodeling of injured rat aorta, and this effect is likely to be mediated by angiotensin II signaling.

Akt2 is involved in loss of epithelial cells and renal fibrosis following unilateral ureteral obstruction

Obstructive nephropathy is an aggressive form of chronic kidney disease (CKD), which is characterized by an epithelial-to-mesenchymal transition (EMT) and interstitial fibrosis. However, the molecular mechanisms of EMT and fibrosis are complex and not fully understood. In this study, we investigated the contribution of Akt2 to experimental renal EMT and fibrosis using the well-established model of unilateral ureteral obstruction (UUO). We found that Akt2 and phosphor (p)-Akt protein levels were increased in the obstructed kidneys. UUO induced activation of transforming growth factor-β1 (TGF-β1) signaling. Importantly, knockout of Akt2 suppressed UUO-induced EMT, kidney fibrosis, increased GSK3β activity, and decreased expression of Snail and β-catenin. Inhibition of GSK3β with LiCl (the inhibitor of GSK3β) increased the expression of Snail and β-catenin in cultured kidney epithelial cells. Our findings suggest that Akt2 partially contributes to interstitial fibrosis following UUO and that inhibition of this signaling pathway may provide a novel approach of prevent progression of renal fibrosis.

Akt2 mediates TGF-β1-induced epithelial to mesenchymal transition by deactivating GSK3β/snail signaling pathway in renal tubular epithelial cells

BACKGROUND

The epithelial-mesenchymal transition (EMT) induced by growth factors or cytokines, particularly transforming growth factor-β (TGF-β1), plays an important role in kidney tubulointerstitial injury. However, signaling pathways mediating TGF-β1-induced EMT are not precisely known. In this study, we examined the role of Akt2 on EMT.

METHODS

HK-2 cells were exposed to 10 ng/ml TGF-β1 to establish a model of EMT. The expression of proteins were detected by western blot assay and Immunofluorescence. The levels of genes were tested by RT-PCR.

RESULTS

We found that treatment of HK-2 cells, a human proximal tubular cell line, with 10 ng/ml TGF-β1 resulted in activation of phosphatidylinositol 3-kinase (PI3K)/Akt2 signaling as evidenced by increased p-PI3K, Akt2 and p-Akt (Ser 473) expression. Importantly, TGF-β1 treatment decreased zona occludins 1 (ZO-1) and E-cadherin (epithelial markers) expression, increased fibronectin and vimentin (mesenchymal makers) expression, which were prevented by Ly294002 (the inhibitor of PI3K) or small interfering RNA (siAkt2), suggesting that Akt2 mediated TGF-β1-induced EMT. Meanwhile, RNA and protein levels of Snail1, the key inducer of EMT, were significantly elevated in TGF-β1-treated HK-2 cells. TGF-β1 also induced inactivation of glycogen synthase kinase-3β (GSK3β), an endogenous inhibitor of Snail. Knockdown of Akt2 using siRNAs or the PI3K inhibitor Ly294002 inhibited TGF-β1-induced phosphorylation of GSK3β and expression of Snail1.

CONCLUSION

These findings revealed that knockdown of Akt2 antagonized TGF-β1-induced EMT by inhibiting GSK3β/Snail signaling pathway.

Metformin protects the myocardium against isoproterenol-induced injury in rats through alleviating endoplasmic reticulum stress

Clinical studies have suggested that metformin, a widely used antidiabetic agent, exerts a direct cardioprotective effect on cardiovascular disease in addition to its blood glucose-lowering activity. This study was designed to identify the role of metformin in rats with isoproterenol (ISO)-induced myocardial injury and to investigate its underlying mechanism. A rat model of myocardial ischemic injury was established by the subcutaneous injection of a high dose of ISO, a beta-adrenergic agonist. The results showed that pretreatment of metformin significantly reduced rat mortality induced by ISO, attenuated the increased plasma lactate dehydrogenase activity and myocardium malondialdehyde level, alleviated the hemodynamic disturbance, inhibited the upregulated gene expression of myocardial probrain natriuretic peptide and alleviated the myocardial morphological injury and apoptosis induced by ISO. Furthermore, western blot analysis showed that metformin suppressed the overexpression of the endoplasmic reticulum stress (ERS) markers cleaved caspase-12 and CEBP-homologous protein induced by ISO and increased the phosphorylation of AMP-activated protein kinase (AMPK). In conclusion, these data suggest that metformin might protect the myocardium against acute ischemic injury in rats at least partially by activating AMPK and alleviating aberrant ERS. These findings might provide further experimental evidence for treating patients at risk of ischemic heart disease with metformin.

Adrenomedullin and adrenotensin increase the transcription of regulator of G‑protein signaling 2 in vascular smooth muscle cells via the cAMP‑dependent and PKC pathways

The regulator of G‑protein signaling 2 (RGS2) has been shown to be crucial in the regulation of vascular tone and blood pressure. The vascular activities of adrenomedullin (ADM) and adrenotension (ADT), two natural peptides, are dependent upon the modulation of RGS2 expression. However, the effects and pathways involved in their modulation remain unknown. This study aimed to observe the changes of RGS2 expression in response to ADM and ADT in cultured vascular smooth muscle cells and to clarify the potential signaling pathways in vitro. In the present study, vascular smooth muscle cells (VSMCs) were cultured with ADM and ADT of various concentrations for different time periods, and the gene expression of RGS2 was analyzed by PCR. ADM significantly increased the gene expression at 0.5 h to ~35‑fold of that at baseline, whereas ADT marginally increased the expression after 1‑2 h. SQ22,536 and chelerythrine were used to block the protein kinase A (PKA) and PKC pathways activated by incubation with ADM. The gene expression of RGS2 was reduced by SQ22,536 only. Furthermore, when SQ22,536 and chelerythrine were added to the cells incubated with ADT, the gene expression was markedly reduced by both SQ22,536 and chelerythrine. In conclusion, ADM immediately showed a marked increase in the gene expression of RGS2 in cultured VSMCs via a cAMP‑dependent pathway and ADT gradually showed a marginal increase in the gene expression via a cAMP‑dependent pathway and a PKC pathway.

Treadmill exercise promotes interleukin 15 expression in skeletal muscle and interleukin 15 receptor alpha expression in adipose tissue of high-fat diet rats

Interleukin 15 (IL-15) has recently been proposed as a myokine involved in regulating lipid metabolism. We investigated the effect of exercise training on IL-15 content in skeletal muscle and expression of IL-15 receptor (IL-15R) in adipose tissue of obese rats. After 12 weeks of a high-fat diet, obese rats underwent treadmill running at 26 m/min (60 min each, 5 days/week for 8 weeks). High-fat diet induced obesity, with increased body weight, body fat, and lipid profile. The level of IL-15 immunoreactivity (IL-15-ir) in plasma and gastrocnemius muscle was lower in obese than control rats, and the mRNA level of IL-15 in gastrocnemius muscle was markedly decreased. The mRNA and protein levels of IL-15R in adipose tissue were markedly lower in obese rats. Compared with sedentary obese rats, treadmill running showed decreased body weight and elevated mRNA expression of IL-15 in muscle and elevated IL-15-ir level in plasma and muscle. The mRNA and protein level of IL-15R were increased in adipose tissue in treadmill running obese rats. Our results showed that exercise training improve obesity and reversed the downregulation of the IL-15 in muscle and IL-15R in adipose tissue induced by high-fat diet.

Reciprocal interaction between macrophages and T cells stimulates IFN-γ and MCP-1 production in Ang II-induced cardiac inflammation and fibrosis

Background

The inflammatory response plays a critical role in hypertension-induced cardiac remodeling. We aimed to study how interaction among inflammatory cells causes inflammatory responses in the process of hypertensive cardiac fibrosis.

Methodology/Principal Findings

Infusion of angiotensin II (Ang II, 1500 ng/kg/min) in mice rapidly induced the expression of interferon γ (IFN-γ) and leukocytes infiltration into the heart. To determine the role of IFN-γ on cardiac inflammation and remodeling, both wild-type (WT) and IFN-γ-knockout (KO) mice were infused Ang II for 7 days, and were found an equal blood pressure increase. However, knockout of IFN-γ prevented Ang II-induced: 1) infiltration of macrophages and T cells into cardiac tissue; 2) expression of tumor necrosis factor α and monocyte chemoattractant protein 1 (MCP-1), and 3) cardiac fibrosis, including the expression of α-smooth muscle actin and collagen I (all p<0.05). Cultured T cells or macrophages alone expressed very low level of IFN-γ, however, co-culture of T cells and macrophages increased IFN-γ expression by 19.8±0.95 folds (vs. WT macrophage, p<0.001) and 20.9 ± 2.09 folds (vs. WT T cells, p<0.001). In vitro co-culture studies using T cells and macrophages from WT or IFN-γ KO mice demonstrated that T cells were primary source for IFN-γ production. Co-culture of WT macrophages with WT T cells, but not with IFN-γ-knockout T cells, increased IFN-γ production (p<0.01). Moreover, IFN-γ produced by T cells amplified MCP-1 expression in macrophages and stimulated macrophage migration.

Conclusions/Significance

Reciprocal interaction between macrophages and T cells in heart stimulates IFN-γ expression, leading to increased MCP-1 expression in macrophages, which results a forward-feed recruitment of macrophages, thus contributing to Ang II-induced cardiac inflammation and fibrosis.

Cathepsin S deficiency results in abnormal accumulation of autophagosomes in macrophages and enhances Ang II-induced cardiac inflammation

BACKGROUND

Cathepsin S (Cat S) is overexpressed in human atherosclerotic and aneurysmal tissues and may contributes to degradation of extracellular matrix, especially elastin, in inflammatory diseases. We aimed to define the role of Cat S in cardiac inflammation and fibrosis induced by angiotensin II (Ang II) in mice.

METHODS AND RESULTS

Cat S-knockout (Cat S(-/-)) and littermate wild-type (WT) C57BL/6J mice were infused continuously with Ang II (750 ng/kg/min) or saline for 7 days. Cat S(-/-) mice showed severe cardiac fibrosis, including elevated expression of collagen I and α-smooth muscle actin (α-SMA), as compared with WT mice. Moreover, macrophage infiltration and expression of inflammatory cytokines (tumor necrosis factor α, transforming growth factor β and interleukin 1β) were significantly greater in Cat S(-/-) than WT hearts. These Ang II-induced effects in Cat S(-/-) mouse hearts was associated with abnormal accumulation of autophagosomes and reduced clearance of damaged mitochondria, which led to increased levels of reactive oxygen species (ROS) and activation of nuclear factor-kappa B (NF-κB) in macrophages.

CONCLUSION

Cat S in lysosomes is essential for mitophagy processing in macrophages, deficiency in Cat S can increase damaged mitochondria and elevate ROS levels and NF-κB activity in hypertensive mice, so it regulates cardiac inflammation and fibrosis.

Insulin resistance induces medial artery calcification in fructose-fed rats

Osteogenic differentiation of vascular smooth muscle cells (VSMCs) results in medial artery calcification, which is common in diabetes, but the pathogenesis is poorly understood. We aimed to explore the pathophysiological roles of insulin resistance (IR) on medial artery calcification in rats with 10% fructose in drinking water. After 12 weeks of fructose feeding, rats showed severe IR, with increased levels of fasting blood glucose, serum insulin and oral glucose tolerance test (OGTT). Fructose-fed rats showed aortic calcification, increased aortic calcium deposition and irregular elastic fibers in the medial layer of the vessel wall. Moreover, plasma phosphorus concentration, calcium × phosphorus product and alkaline phosphatase (ALP) activity, and aortic calcium content and ALP activity were significantly increased. Fructose feeding increased mRNA levels of osteopontin, type III sodium-dependent phosphate co-transporter, bone morphogenetic protein-2 and the key transcription factor core binding factor alpha 1 in aortic tissue and downregulated mRNA levels of osteoprotegerin and matrix γ-carboxyglutamic acid protein. Fructose feeding decreased protein levels of smooth-muscle lineage markers and induced severe lipid peroxidation injury. IR induced by high fructose feeding could evoke osteogenic transdifferentiation of VSMCs and promote vascular calcification.

Ghrelin and cardiovascular diseases

Ghrelin, a newly discovered bioactive peptide, is a natural endogenous ligand of the growth hormone (GH) secretagogue receptor and initially identified as a strong stimulant for the release of GH. Subsequent research has shown that ghrelin and its various receptors are ubiquitous in many other organs and tissues. Moreover, they participate in the regulation of appetite, energy, bodyweight, metabolism of glucose and fat, as well as modulation of gastrointestinal, cardiovascular, pulmonary, immune functions and cell proliferation/apoptosis. Increasing evidence has demonstrated that ghrelin has a close relationship with cardiovascular system. Ghrelin and its receptors are widely distributed in cardiovascular tissues, and there is no doubt that the effects of ghrelin in the cardiovascular system are mediated not only via its growth-hormone-releasing effect but also by its direct effects on the heart. Exogenous administration of ghrelin can dilate peripheral blood vessels, constrict coronary artery, improve endothelial function, as well as inhibit myocardial cell apoptosis. So, ghrelin may have cardiovascular protective effect, including lowering of blood pressure, regulation of atherosclerosis, and protection from ischemia/reperfusion injury as well as improving the prognosis of myocardial infarction and heart failure. Some of these new functions of ghrelin may provide new potential therapeutic opportunities for ghrelin in cardiovascular medicine. In this paper, we will review the existing evidence for cardiovascular effects of ghrelin, including the cardiovascular function, the variations in ghrelin plasma levels in pathophysiologicalogical conditions, the possible protective mechanisms of ghrelin, as well as its future potential therapeutic roles.

Cartilage Oligomeric Matrix Protein Inhibits Vascular Smooth Muscle Calcification by Interacting With Bone Morphogenetic Protein-2

Rationale:

Vascular calcification is a significant contributor to cardiovascular morbidity and mortality. We recently reported that cartilage oligomeric matrix protein (COMP) is pivotal for maintaining the homeostasis of vascular smooth muscle cells (VSMCs). Whether COMP affects the process of vascular calcification is unknown.

Objective:

We aimed to test whether COMP modulates vascular calcification.

Methods and Results:

VSMC calcification in vitro was induced by calcifying media containing high inorganic phosphate or calcium. In vivo medial vessel calcification was induced in rats by 5/6 nephrectomy with a high-phosphate diet or by periadventitial application of CaCl 2 to the abdominal aorta. COMP protein level was markedly reduced in both calcified VSMCs and arteries. COMP deficiency remarkably exacerbated VSMC calcification, whereas ectopic expression of COMP greatly reduced calcification. Furthermore, COMP knockdown facilitated osteogenic markers expression by VSMCs even in the absence of calcifying media. By contrast, COMP overexpression significantly inhibited high phosphate– or high calcium–induced VSMC osteochondrogenic transition. Induction of osteogenic marker expression by COMP silencing was reversed by a soluble form of bone morphogenetic protein (BMP)-2 receptor IA, which suggests a BMP-2–dependent mechanism. Our data revealed that COMP bound directly to BMP-2 through the C terminus, inhibited BMP-2 receptor binding, and blocked BMP-2 osteogenic signaling, indicating COMP inhibits osteochondrogenic transition of VSMCs at least partially through inhibiting BMP-2.

Conclusions:

Our data strongly suggest that COMP is a novel inhibitor of vascular calcification. The imbalance between the effects of COMP and BMP-2 may provide new insights into the pathophysiology of vascular calcification.

MCP-induced protein 1 suppresses TNFalpha-induced VCAM-1 expression in human endothelial cells

Endothelial inflammation plays a critical role in the development and progression of cardiovascular disease, albeit the mechanisms need to be fully elucidated. We here report that treatment of human umbilical vein endothelial cells (HUVECs) with tumor necrosis factor (TNF) alpha substantially increased the expression of MCP-induced protein 1 (MCPIP1). Overexpression of MCPIP1 protected ECs against TNFalpha-induced endothelial activation, as characterized by the attenuation in the expression of the adhesion molecule VCAM-1 and monocyte adherence to ECs. Conversely, small interfering RNA-mediated knock down of MCPIP1 increased the expression of VCAM-1 and monocytic adherence to ECs. These studies identified MCPIP1 as a feedback control of cytokines-induced endothelial inflammation.

Hydrogen sulfide attenuates the pathogenesis of pulmonary fibrosis induced by bleomycin in rats

The present study investigated the role of the endogenous cystathionine gamma-lyase (CSE) / hydrogen sulfide pathway in the pathogenesis of pulmonary fibrosis. Rats treated with intratracheal bleomycin were exposed either to the H2S donor NaHS or to saline. The results on day 7 showed that plasma H2S concentration and pulmonary CSE activity (H2S production rate) were significantly lower in rats treated with bleomycin and saline (fibrosis-alone) than in controls, whereas on day 28 plasma H2S concentration was higher and pulmonary CSE activity was the same as that of controls. The relative CSE mRNA level in the lungs of rats treated with bleomycin was significantly higher than control values on days 7 and 28. After exposure to NaHS, the total lung hydroxyproline content and the malondialdehyde (MDA) content were both significantly lower, with no difference observed between NaHS high-dose and low-dose treatments. Further, MDA formation stimulated by the free radical-generating system (FRGS) in vitro was lower in lung tissue incubated with NaHS than it was in tissue incubated with FRGS alone. These results suggest that NaHS administration ameliorated the pulmonary fibrosis induced by bleomycin in rats and that this protective effect of H2S may be mediated by its antioxidative action.

[Effect of age on vascular calcification induced by vitamin D3 and nicotine]

OBJECTIVE

To explore the effect of age on vascular calcification induced by vitamin D3 and nicotine.

METHODS

Vascular calcification in rats was induced by administration of vitamin D3 plus nicotine (VDN treatment). After six weeks, Von Kossa staining, calcium content, alkaline phosphatase activity, phosphorus and calcium content in plasma were assayed. Carotid blood pressure, cardiac function and the relative amounts of osteopontin (OPN), osteoprotegerin (OPG), matrix Gla protein (MGP), bone morphogenetic protein-2 (BMP2) mRNA level and smooth muscle actin-alpha (alpha-SMA)protein level were measured.

RESULTS

Compared with control group, the systolic blood pressure(SBP)of the rats of 2,8 and 16 months with vascular calcification respectively increased by 20.7%, 29.4% and 22.2% (P<0.05); the left ventricular systolic pressure (LVSP) respectively increased by 13.6%, 21.1% and 16.2% (P<0.05); + LVdP/dtmax respectively increased by 49.1% (P<0.01), 21.4% and 13.1% (P<0.05); -LVdP/dtmax respectively increased by 56.3% (P<0.01), 24.4% and 11.3% (P<0.05). Aortic calcium contents of the 2-, 8- and 16-month calcified rats were respectively 2.62-fold (P<0.05), 24.87-fold (P<0.01) and 10.01-fold (P<0.05) of the age-matched control group. As compared with the aortic calcium contents of calcified groups at different ages, the calcification group of 8 months had higher aortic calcium content than those of 2 and 16 months, which were respectively, 5.28-fold and 2.63-fold (P<0.05). Compared with the control groups, alkaline phosphatases activity (ALP) of calcification groups increased respectively by 126.6%, 115.2% and 227.9% (P<0.01) in the 2-, 8- and 16-month rats. As compared with the ALP activity of calcified groups at different ages, ALP activity of aortic calcification group of the 8-month-old rats was higher than that of the 2-month-old and 16-month-old rats, which increased by 176% and 75% respectively (all P<0.01). Von kossa staining for calcification showed positive staining as black/brown areas within the main, large, nodular structures as shown in extracellular matrix and cytoplasma in VDN groups at different ages, especially in the 8-month-old VDN group, with the most dispersed calcific nodules deposited and a few of the elastic fibers of the medial layer collapse. The mRNA expressions of OPN, OPG, MGP, BMP2 were up-regulated (P<0.01 or P<0.05) and protein levels of alpha-SMA were down-regulated in different calcification groups(P<0.05). The mRNA levels of OPN in 8-month-old calcification group increased by 3.41-fold (P<0.01) and 1.34-fold (P<0.05) respectively compared with the 2-month-old and 16-month-old calcification groups. And the alpha-SMA protein expression levels were lower at calcification groups in different ages, which were respectively equivalent to 17.6% of the 2-month-old control group (P<0.01), 11% of the 8-month-old control group (P<0.05) and 41.7% of 16-month-old control group (P<0.01).

CONCLUSION

SD rats of 2, 8 and 16 months can all be used to duplicate vascular calcification model induced by vitamin D3 plus nicotine and the 8-month-old rat has the most sensitivity to the calcification treatment, which means that the 8-month-old rat may be the most appropriate age for the study of vascular calcification.

RNA-destabilizing factor tristetraprolin negatively regulates NF-kappaB signaling

Tristetraprolin (TTP) is a CCCH zinc finger-containing protein that destabilizes mRNA by binding to an AU-rich element. Mice deficient in TTP develop a severe inflammatory syndrome mainly because of overproduction of tumor necrosis factor alpha. We report here that TTP also negatively regulates NF-kappaB signaling at the transcriptional corepressor level, by which it may repress inflammatory gene transcription. TTP expression inhibited NF-kappaB-dependent transcription. However, overexpression of TTP did not affect reporter mRNA stability. Instead, TTP functioned as a corepressor of p65/NF-kappaB. In support of this concept, we found that TTP physically interacted with the p65 subunit of NF-kappaB and was also associated with HDAC1, -3, and -7 in vivo. Treatment with histone deacetylase inhibitors or small interfering RNA induced HDAC1 or HDAC3 knockdown completely or partly abolished the inhibitory activity of TTP on NF-kappaB reporter activation. Consistently, chromatin immunoprecipitation showed decreased recruitment of HDAC1 and increased recruitment of CREB-binding protein on the Mcp-1 promoter in TTP(-/-) cells compared with wild-type cells. Moreover, overexpression of TTP blocked CREB-binding protein-induced acetylation of p65/NF-kappaB. Taken together, these data suggest that TTP may also function in vivo as a modulator in suppressing the transcriptional activity of NF-kappaB.

[Cardiovascular effects of intermedin1-53 and its mechanism]

AIM

The present study was designed to determined the cardiovascular effects of IMD1-53 in rats and its possible mechanism.

METHODS

Isolated rat hearts were perfused by Iangendorff mode, and ventricular function was measured after IMD1-53 perfusion. Meanwhere, we investigated the effects of IMDI) on arterial pressure after intravenous administration of IMD. And cAMP content was detected in rat ventricular and aortic tissues.

RESULTS

The results showed that perfusion with IMD significantly enhanced cardiac function and resulted in higher LVSP, +dp/dt(max) and -dp/dt(max) by 45%, 51% and 37%, respectively, compared with control and increased coronary infusion flow. The effects of IMD1-53 on cardiac function were antagonized by H-89, an inhibitor of PKA. The content of cAMP in the ventricular tissues after IMD perfusion was 131% higher than control. In addition, intravenous administration of IMD induced a potent decrease in arterial pressureand heart rate, and in aortic tissues, IMD incubation resulted in a 236% increase in cAMP content compared with control group.

CONCLUSION

The study reveals that IMD can increase cardiac function and decrease arterial pressure in rat and the effects may be related to cAMP pathway.

Endoplasmic reticulum stress-mediated apoptosis is activated in vascular calcification

Apoptosis of vascular smooth muscle cells plays an important role in vascular calcification (VC). However, the potential mechanism remains poorly understood. Previous studies showed that apoptosis mediated by endoplasmic reticulum stress (ERS) participates in several diseases with VC. We prepared two rat models of calcification, vitamin D(3) plus nicotine (VDN) and rapid calcification (RC), to investigate whether ERS-mediated apoptosis is activated in VC. TUNEL staining and cleaved caspase 3 protein levels illustrated enhanced apoptosis in calcification groups. Western blot analysis revealed the ERS hallmarks GRP78 and GRP94 increased by 43.9% and 91.7%, respectively, in the VDN group and GRP78 elevated by 84.0% in the RC group (all P<0.05) as compared with controls. Moreover, two molecules of ERS-induced apoptosis, caspase 12 and C/EBP homologous protein, were up-regulated nearly 3-fold (P<0.05) in the VDN group and 10-fold (P<0.01) in the RC group. Our results indicated that ERS-induced apoptosis may be involved in VC, and amelioration of ERS could be a novel strategy to prevent and treat the related diseases.

[Role of adiponectin and its receptors in anti-atherosclerotic effects of pioglitazone on ApoE knocked out mice]

OBJECTIVE

To study the effects of pioglitazone on atherosclerosis on ApoE-/- mice, and to investigate the roles of adiponectin and its receptors.

METHODS

ApoE-/- mice were fed with high-fat chow for the induction of atherosclerosis and were divided into three subgroups: placebo(n=10), low-dose[10 mg/( kg.d), n=10] pioglitazone therapy, and high-dose[20 mg/( kg.d), n=10] pioglitazone therapy. C57BL/6J wild type mice (n=9) were used as control. Aortic atherosclerosis and intimajmedia thickness (intima-media thickness , IMT) of abdominal aorta were monitored, and plasma adiponectin was also measured. Expression levels of the adiponectin receptor 1(AdipoR1)and adiponectin receptor 2 (AdipoR2) in vessels were analyzed(RT-PCR).

RESULTS

(1) Aortic atherosclerotic lesions were observed in ApoE-/- mice but not in wild type mice. Interestingly, these lesions were significantly prevented by high-dose pioglitazone therapy. Compared with wild type mice, ApoE-/- mice had increased IMT of abdominal aorta [(0.290+/-0.063 vs 0.178+/-0.012) cm, P<0.01] that was significantly reversed by high-dose pioglitazone therapy [(0.208+/-0.012 vs 0.290+/-0.063) cm, P<0.05]. (2) The level of plasma adiponectin was significantly lower in ApoE-/- mice [(12.41+/-3.84 vs 18.96+/-4.89) microg/L, P<0.05), which could be increased by low-and high-dose pioglitazone therapy (18.78+/-7.24 microg/L vs 12.41+/-3.84 microg/L, P<0.05; and 24.00+/-4.71 microg/L vs 12.41+/-3.84 microg/L, P<0.05). (3) Compared with wild type mice, ApoE-/- mice had reduced AdipoR1 mRNA level(0.789+/-0.167 vs 0.950+/-0.071, P<0.05) and reduced the ratio of AdipoR1/AdipoR2 (0.940+/-0.102 vs 1.039+/-0.062, P<0.05); high dose pioglitazone therapy could upregulate AdipoR1, AdipoR2 mRNA expression and increase the ratio of AdipoR1/AdipoR2 (1.063+/-0.051 vs 0.940+/-0.102,P<0.01).

CONCLUSION

Pioglitazone inhibits aortic atherosclerosis in ApoE-/- mice, and these effects are correlated with increased plasma adiponectin level and the expression of AdipoR1 mRNA in vessels.

Primary malignant fibrous histiocytoma of the thyroid

AIMS AND METHODS

To study the clinical features, diagnosis, and treatment of primary malignant fibrous histiocytoma of the thyroid (MFH-T). Treatment and outcome were analyzed retrospectively in a consecutive series of 12 patients with primary MFH-T treated at the Cancer Hospital of the Chinese Academy of Medical Sciences from 1987 to 2007.

RESULTS

All 12 patients underwent surgery; surgery alone was used in four patients. Five patients were given post-operative radiotherapy, and one patient was given pre-operative radiotherapy. Two patients were given post-operative chemotherapy. Five patients had locoregional recurrence, and five had distant metastases in follow-up. Median survival was 9 months. One patient is alive, and has no evidence of disease. Six patients died six months after treatment, and the other four patients died in 10, 14, 18, and 24 months after treatment, respectively. Nine patients died of the disease, and one patient died of cerebral hemorrhage after treatment.

CONCLUSION

Primary MFH-T is very rare and has a poor prognosis. Although surgical resection of MFH-T is the treatment of choice in MFH-T, the results are unsatisfactory.

[The protective effects of intermedin 1-53 on oleic acid induced acute lung injury in rats]

OBJECTIVE

To investigate the effects of intermedin 1-53 on oleic acid induced acute lung injury (ALI) in rats and its possible mechanisms.

METHODS

Twenty-four male Wistar rats, weighting 280-300 g, were randomly divided into three groups (n = 8). In the oleic acid group, ALI was induced by injecting oleic acid (0.2 ml/kg) intravenously. In the intervention group, the rats received oleic acid as above, but intraperitoneal injection of intermedin 1-53 (2 nmol/kg in l ml saline) was given 1 h before and 2 h after oleic acid infusion, respectively. The control group was given normal saline (0.2 ml/kg). The animals were observed for 6 h after intravenous infusion. The histopathological changes of lung tissue were studied. The arterial blood gases, lung wet/dry weight ratio (W/D), leukocyte count and neutrophil differentials in bronchoalveolar lavage fluid (BALF) were measured. Contents of intermedin 1-53 in the plasma were detected with radioimmunoassay, myeloperoxidase activity, and malondialdehyde (MDA) and conjugated diene (C-diene) level of lung tissue were also measured.

RESULTS

The PaO(2) was higher and lung wet/dry weight ratio, leukocyte count and neutrophil counts in BALF were significantly lower in the intermedin group [(81.7 +/- 4.6) mm Hg (1 mm Hg = 0.133 kPa), 5.49 +/- 0.63, (57.9 +/- 7.4) x 10(4)/ml, 0.718 +/- 0.085, respectively] as compared to the oleic acid group [(60.8 +/- 3.2) mm Hg, 6.18 +/- 0.34, (122.0 +/- 16.6) x 10(4)/ml, 0.878 +/- 0.026], q value was 16.74, 3.43, 17.23, 6.32, respectively, all P < 0.05 or 0.01).

CONCLUSIONS

Intermedin 1 - 53 treatment significantly attenuated oleic acid-induced lung injury in rats. Intermedin 1-53 exerts pulmo-protective effects by inhibiting formation of lipid oxide products.

[Alterations of intermedin and its receptor system in oleic acid-induced acute lung injury of rats]

OBJECTIVE

To investigate the changes of pulmonary IMD and its receptor system-calcitonin receptor-like receptor (CL) and receptor activity modifying proteins (RAMPs) mRNA in acute lung injury(ALI) induced by oleic acid of rats.

METHODS

Contents of IMD in plasma and lung homogenates were measured by radioimmunoassay(RIA). The lung mRNA of IMD, CL and RAMPs was determined by semi-quantitative RT-PCR.

RESULTS

Compared with control group, in ALI group, the contents of IMD1-53 in plasma and lung homogenates were decreased by 20.8% and 74.5% (all P < 0.05) , respectively. Furthermore , it was found that the levels of IMD, CL, RAMP1 and RAMP2 mRNA in lung were decreased by 30%, 38%, 26% and 37.9% (all P < 0. 05) , respectively. The levels of CL , RAMP1 or RAMP2 mRNA were positively correlated with down-regulations of IMD mRNA in ALI. However, compared with control group, the maximum binding capacity of IMD1-53 to plasma membranes was significantly increased in ALI group, and the affinity of IMD1-53 for its receptor almost had no change.

CONCLUSION

The amount of IMD 1-53 is down-regulated and IMD receptor system also down-regulated in Oliec acid induced ALI of rats. These changes suggest that IMD and its receptor system probably are involved in the development of ALI.

[Effect of hydrogen sulfide on Bleomycin-induced pulmonary fibrosis in rats]

OBJECTIVE

To explore the change of endogenous hydrogen sulfide and the effect of exogenously applied H(2)S on Bleomycin-induced pulmonary fibrosis in rats.

METHODS

(1) Forty-eight male Wistar rats were randomly divided into control group, fibrosis group, fibrosis+NaHS-low group (1.4 micromol/kg, bid intraperitoneally) and fibrosis+NaHS-high group (7.0 micromol/kg, bid intraperitoneally). Pulmonary fibrosis was induced by intratracheal instillation of bleomycin. The control group and pulmonary fibrosis group were injected with the same volume of normal saline. Pulmonary pathology changes were observed, the plasma H(2)S concentration,the activity of CSE in lung tissue and the contents of MDA, hydroxyproline were detected on the 7th and 28th days respectively after bleomycin administration. CSE mRNA was also measured using quantitative RT-PCR. (2) Isolated lung tissues were exposed to Fe(2+)/H(2)O(2) without or with different concentrations of NaHS (10(-5), 5 x 10(-5), 10(-4), 10(-3) mmol/L) at 37 degree Celsius for 10 minutes, and the MDA content was assayed by biochemical method.

RESULTS

(1) Compared with rats in control group, the concentration of plasma H(2)S and the activity of CSE in lung tissues in fibrosis group decreased on day 7 (all P<0.01); On the 28th day, the level of plasma H(2)S increased clearly (P<0.01) and the activity of CSE was ascendant without significant difference compared with that of control group. Relative CSE mRNA amounts in lung tissues increased 34%, 144%, respectively (all P<0.01) in rats of fibrosis group compared with those of control group. The contents of MDA and hydroxyproline increased significantly in fibrosis group compared with those of control group on days 7, 28 (all P<0.01). In NaHS-low group and NaHS-high group, the contents of MDA and hydroxyproline decreased markedly (all P<0.01). (2) The contents of MDA in incubation of lung tissues at different concentrations of NaHS were all decreased as compared with those in incubation with Fe(2+)/H(2)O(2) alone (all P<0.01). When NaHS was at 10(-4) mol/L, the MDA content reversed to the lowest value, which had the highest value at 10(-3) mol/L of NaHS.

CONCLUSION

Endogenous CSE/H(2)S pathway was involved in the pathogenesis of rat pulmonary fibrosis. Exogenously applied H(2)S could attenuate the process of pulmonary fibrosis possibly because of reducing oxidative stress.

Hydrogen sulfide ameliorates vascular calcification induced by vitamin D3 plus nicotine in rats

AIM

To investigate the role of the endogenous cystathionine gamma-synthase (CSE)/hydrogen sulfide (H2S) pathway in vascular calcification in vivo.

METHODS

A rat vascular calcification model was established by administration of vitamin D3 plus nicotine (VDN). The amount of CSE and osteopontin (OPN) mRNA was determined by using semi-quantitative reverse-transcription polymerase chain reaction. The calcium content, 45Ca2+ accumulation and alkaline phosphatase (ALP) activity were measured. H2S production and CSE activity were measured.

RESULTS

von Kossa staining produced strong positive black/brown staining in areas among the elastic fibers of the medial layer in the calcified aorta. The calcium content, 45Ca2+ accumulation and ALP activity in calcified arteries increased by 6.77-, 1.42-, and 1.87-fold, respectively, compared with controls. The expression of the OPN gene was upregulated (P<0.01). Expression of the CSE gene was downregulated. However, calcium content, 45Ca2+ uptake and ALP activity in the VDN plus NaHS group was lower than that in the VDN group. The content of calcium and 45Ca2+ accumulation and activity of ALP in the aorta were 34.8%, 40.75% and 63.5% lower in the low-dosage NaHS group than in the VDN group, respectively (P<0.01), and the calcium content and deposition of 45Ca2+ and activity of ALP was 83.9%, 37.8 % and 46.2% lower in the aorta in the high-dosage NaHS group than in the VDN group, respectively (P<0.01). The expression of the OPN gene was downregulated.

CONCLUSION

The production of H2S, and CSE activity were decreased and CSE gene expression was downregulated in rats with vascular calcification. H2S can ameliorate vascular calcification, suggesting that the H2S/CSE pathway plays a regulatory role in the pathogenesis of vascular calcification.

[Preparation of vascular calcification in vivo and vascular smooth muscle cell calcification in vitro of rats]

OBJECTIVE

To investigate simple, economical, stable and efficient methods of in vivo and in vitro cardiovascular calcification models in rats.

METHODS

Rats received Vitamin D(3) (300 000 U/kg, i.m.) and nicotine (25 mg/kg, 5 mL/kg in peanut oil, p.o.) at 8 a.m. on day 1. The nicotine administration was repeated at 6 p.m. Rats in control group received an injection of normal saline (i.m.) and two gavages of medium oil. All of the rats were then allowed to recover for 4 weeks and given standard rodent chow. After the measurement of cardiac function the rats were sacrificed and the calcium content in myocardium and aorta were measured. Von Kossa staining was used to detect the deposit of calcium in myocardium and aorta. Cultured smooth muscle cell(SMC) derived from rat thoracic aorta was treated with beta-glycerophosphate for 14 days, then the calcium content and deposit were measured.

RESULTS

Compared with control group, the rats with cardiovascular calcification showed a lower body weight, The ratio of left heart to body weight, myocardial and aortic calcium content were increased respectively. Alkaline phosphatases activity in calcified myocardium and aorta were increased respectively, compared with the control. The values of animal mean blood pressure (MBP), heart rate (HR) and left ventricle end-distolic pressure (LVEDP) showed no significant alteration (P>0.05) in vitamin D3 plus nicotine (VDN) group. The values of +LV dp/dt(max) and -LV dp/dtmax were significantly lower in VDN group (P<0.05 and P<0.01, respectively). In calcified vascular smooth muscle cells(VSMCs), von Kossa staining for calcification, showed positive staining as black/brown areas within the main, large, nodular structures as shown in extracellular matrix and cytoplasma. The content of calcium, (45)Ca(2+) uptake and alkaline phosphatase (ALP) activity in calcified VSMCs were increased (all P<0.01), respectively, compared with that of the control.

CONCLUSION

These methods can be used to produce calcification models in vivo and in vitro, which save money and time and are easy to manipulate.

Endogenous hydrogen sulfide regulation of myocardial injury induced by isoproterenol

Previous work has shown that the endogenous cystathionine gamma-synthase (CSE)/hydrogen sulfide (H(2)S) pathway participates in the regulation of cardiac contraction. We hypothesized that the pathway might participate in the pathophysiological regulation of ischemic heart disease. Isoproterenol injection of rat hearts induced a myocardial ischemic injury model, with reduced myocardial and plasma H(2)S levels, decreased CSE activity, and upregulated CSE gene expression. Exogenous administration of the H(2)S donor NaHS reduced the mortality rate; increased left-ventricular pressure development and left-ventricular-end systolic pressure; and decreased left-ventricular-end diastolic pressure (LVEDP) and subendocardial necrosis, capillary dilatation, leukocytic infiltration, fibroblast swelling, and fibroblastic hyperplasia. As well, production of lipid peroxidation, including myocardial malondialdehyde (MDA), and plasma MDA and conjugated diene, was reduced. Oxidative stress injury is an important mechanism of isoproterenol-induced myocardial injury. In vitro experiments revealed that NaHS might antagonize myocyte MDA production by oxygen-free radicals and that NaHS directly scavenged hydrogen peroxide and superoxide anions. Our results suggest that the endogenous CSE/H(2)S pathway contributes to the pathogenesis of isoproterenol-induced myocardial injury. Administration of exogenous H(2)S effectively protects myocytes and contractile activity, at least by its direct scavenging of oxygen-free radicals and reducing the accumulation of lipid peroxidations.

[Alterations of adrenomedullin and its receptor system in calcified myocardium and aorta of rats]

OBJECTIVE

To explore the production of ADM, changes and significance of adrenomedullin (ADM) mRNA and ADM receptor system-calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) mRNA in calcified myocardium and aorta of rats.

METHODS

Contents of ADM in plasma, myocardium and vessel were measured by radioimmunoassay (RIA). The amount of ADM, CRLR and RAMPs mRNA was determined by semi-quantitative RT-PCR.

RESULTS

The contents of calcium in calcified myocardium and aorta were increased by 342% and 606% (all P<0.01), respectively, and alkaline phosphatase activities in calcified myocardium and vessel were increased by 66.5% and 82.7% (all P<0.01), respectively, compared with the control. Contents of ADM in plasma, myocardium and aorta were increased by 58 % (P<0.01), 14.3%(P<0.01) and 27.8%(P<0.05). Furthermore, it was found that the levels of ADM, CRLR and RAMP2 mRNA in calcified myocardium were elevated by 90.6% 157.5% and 119.6%(all P<0.01), respectively, but RAMP3 mRNA was decreased by 14.1 %(P<0.01). The levels of ADM, CRLR, RAMP2 and RAMP3 mRNA in calcified aorta were elevated by 37.7%(P<0.01), 41.4%(P<0.01),60.1%(P<0.05) and 13%(P<0.01) respectively, compared with the control. The elevated levels of CRLR, RAMP2 or RAMP3 mRNA were positively correlated with up regulations of ADM mRNA in calcified myocardium and aorta.

CONCLUSION

Calcified myocardium and aorta may generate an increased amount of ADM, different alterations of gene expressions of ADM and its receptor system. These RESULTS suggest that ADM and its receptor system might participate in the regulation of calcification in heart and vessel.

The role of adrenomedullin and its receptor system in cardiovascular calcification of rat induced by Vitamin D(3) plus nicotine

Adrenomedullin (ADM) is a potent vasodilatory peptide which regulates blood pressure, cell growth and bone formation. Our work was aimed to explore the production of ADM, changes and pathophysiological significance of ADM mRNA and ADM receptor components--calcitonin receptor like receptor (CRLR) and receptor activity modifying proteins (RAMPs) mRNA in calcified myocardium and aorta of rats induced by Vitamin D3 plus nicotine. Contents of ADM in plasma, myocardium and aorta were measured by radioimmunoassay (RIA). The amount of ADM, CRLR and RAMPs mRNA was determined by semi-quantitative RT-PCR. The calcium content and alkaline phosphatase activity in myocardium and aorta of rats were measured. The results showed that the contents of calcium in calcified myocardium and aorta were increased by 3.5- and 6-fold (all P < 0.01), respectively, and alkaline phosphatases activity in calcified myocardium and aorta were increased by 66.5 and 82.7% (all P < 0.01 ), respectively, compared with control. Contents of ADM in plasma, myocardium and aorta were increased by 58% (P < 0.01), 14.3% (P < 0.01) and 27.8% P < 0.05). Furthermore, it was found that the amount of ADM, CRLR and RAMP2 mRNA in calcified myocardium was elevated by 90.6, 157.5 and 119.6% (all P < 0.01), RAMP3 mRNA was decreased by 14.1% (P < 0.01), respectively, compared with control. The amount of ADM, CRLR, RAMP2 and RAMP3 mRNA in calcified aorta was elevated by 37.7% (P < 0.01), 41.4% (P < 0.01), 60.1% (P < 0.05) and 13% P < 0.01), respectively, compared with control. The elevated level of CRLR and RAMP2 mRNA were in positive correlation with that of ADM mRNA (r = 0.992 and 0.882, respectively, P < 0.01) in calcified myocardium. The elevated level of CRLR and RAMP3 mRNA were also in positive correlation with that of ADM mRNA (r = 0.727, P < 0.05 and 0.816, P < 0.01, respectively) in calcified aorta. These results demonstrated that calcified myocardium and aorta generated an increased amount of ADM, up-regulated gene expressions of ADM, CRLR and RAMP2 mRNA. While the alteration of RAMP3 mRNA in calcified myocardium and aorta was different. These suggested that ADM and its receptor system might involve in the regulation of calcification in heart and aorta.

Taurine antagonized oxidative stress injury induced by homocysteine in rat vascular smooth muscle cells

AIM

To observe protective effects of taurine on reactive oxygen species generation induced by homocysteine in rat vascular smooth muscle cells (VSMC).

METHODS

Rat VSMC was incubated with various concentrations of homocysteine and taurine. The lactate dehydrogenase (LDH) activity which released into culture medium was elevated as an indicator for VSMC injury. The reactive oxygen species (ROS)--hydrogen peroxide (H2O2) and superoxide anion (O2(-*)) were measured with luminol or lucigenin chemiluminescence method, and the mitochondria Mn-superoxide dismutase (Mn-SOD) and catalase (CAT) were also measured in treated VSMC.

RESULTS

LDH leakage from cultured VSMC treated with homocysteine, was increased (P<0.01 vs control), and it was markedly inhibited when co-incubated with taurine (P<0.01). Homocysteine induced H2O2 generation from VSMC in a concentration dependent manner (P<0.01 vs control). However, taurine (5, 10, and 20 mmol/L) significantly antagonized 0.5 mmol/L homocysteine-induced H2O2 generation in VSMC in a concentration dependent manner (P<0.01 vs homocysteine alone group), although taurine itself did not alter the H2O2 generation in VSMC (P>0.05 vs control). In this study, the superoxide anion in VSMC was not detectable by chemiluminescence method. In addition, treatment of VSMC with taurine increased mitochondria Mn-SOD and CAT activity in a concentration dependent manner (P<0.05), but homocysteine decreased mitochondria Mn-SOD and CAT activity (P<0.01 vs control). In addition, co-administration of taurine markedly ameliorated homocysteine-induced inhibition of Mn-SOD and CAT activity in VSMC (P<0.01 vs homocysteine alone group).

CONCLUSION

Taurine antagonized the effects of homocysteine on ROS generation and anti-oxidant enzyme activities in rat VSMC in vitro.

H2S generated by heart in rat and its effects on cardiac function

Hydrogen sulfide (H2S), which was considered as a novel gasotransmitter, is produced endogenously from L-cysteine in mammalian brain and vessels, and might be a physiological function regulator to these organs. Here, we showed that mRNA for H2S producing enzyme, cystathionine gamma-lyase, was expressed in myocardial tissues and H2S could endogenously be produced in myocardial tissues. Negative inotropic effect of H2S was proved in present study in vitro and in vivo experiments, and the effect could partly be blocked by glibenclamide, a KATP channel blocker. An intravenous bolus injection of NaHS provoked a decrease in central venous pressure. The present findings suggested that H2S could be endogenously produced by heart tissues, as a physiological cardiac function regulator, mediated by KATP channel pathway.

[Involvement of endothelin in the proliferative effect of lysophosphatidic acid on vascular smooth muscle cells in rats]

OBJECTIVE

To observe the effects of lysophosphatidic acid (LPA) on production of endothelin (ET) in rat aorta vascular smooth muscle cells (VSMCs).

METHODS

Cultured VSMCs were used in the study. DNA synthesis of VSMCs was measured by 3H-TdR incorporation. The amount of ET mRNA of VSMCs was determined by competitive quantitative RT-PCR. The levels of synthesis and release of ET in VSMCs were determined by radioimmunoassay (RIA).

RESULTS

5-20 mumol.L-1 of LPA promoted VSMCs 3H-TdR incorporation in a concentration dependent manner. The amount of ET mRNA in VSMCs treated by 5-20 mumol.L-1 of LPA was increased by 16%, 21%, and 23%, respectively, compared with the control. After 8 hours of incubation, 5-20 mumol.L-1 of LPA elevated the ET production in a concentration dependent manner. After 8 hours of VSMCs incubated with LPA (5-20 mumol.L-1), the content of ET in medium was increased by 140%-200%, respectively, compared with the control. In addition, it was found that BQ123, a non-selective ET receptor antagonist, greatly decreased the VSMCs DNA synthesis induced by LPA.

CONCLUSION

LPA stimulated the ET mRNA expression and ET production in VSMCs. The effects of LPA on VSMCs DNA synthesis were partly mediated by ET/ETA receptor pathway. It suggests that LPA and ET interact and exert biological effects as endogenous active peptides.