The 223A>G polymorphism of the leptin receptor gene is associated with macroangiopathy in type 2 diabetes mellitus.

To determine whether leptin receptor (LEPR) 223A>G polymorphism has an effect on the plasma leptin levels and the macroangiopathic complications in type 2 diabetes mellitus (T2DM). The genotypes and allelic frequencies of the LEPR 223A>G were examined with polymerase chain reaction and restriction fragment length polymorphism in 301 patients with T2DM and 172 unrelated healthy subjects. The plasma concentrations of leptin were determined in all subjects. The mean plasma leptin levels in the T2DM group were significantly higher than that of controls and the plasma levels of leptin were higher in diabetic patients with macroangiopathy than in patients without macroangiopathy (P < 0.05). The genotype (GG, AG and AA) distribution of 223A>G polymorphism was 58.3, 32.5, and 9.2% in diabetic patients with macroangiopathy, 75.3, 22.1, and 2.6% in patients without macroangiopathy, and 70.3, 27.5, 2.2% in controls respectively, a significant difference was found between diabetic patients with and without macroangiopathy (P < 0.05). The frequency of the allele A was higher in patients with macroangiopathy than in patients without macroangiopathy (25.6 vs. 16.3%; P < 0.05). Moreover, the plasma leptin levels were markedly higher in patients with AA genotype than those with AG or GG genotype in patients with macroangiopathy (P < 0.05). The LEPR 223A>G gene polymorphism associated with a predisposition to increased plasma leptin levels could constitute a useful predictive marker for diabetic macroangiopathy.

Effects of high thoracic epidural anesthesia on atrial electrophysiological characteristics and sympathetic nerve sprouting in a canine model of atrial fibrillation.

High thoracic epidural anesthesia (HTEA) blocks the afferent and efferent cardiac sympathetic nerve fibers and may affect atrial electrophysiological characteristics and nerve sprouting in patients with atrial fibrillation (AF). In this study, 18 dogs were randomly divided into a control group (n = 6), in which dogs were atrially paced at 400 beats/min for 6 weeks; an HTEA group (n = 6), in which dogs underwent atrial pacing and HTEA for 6 weeks; and a sham-operated group (n = 6), in which dogs underwent the operation but did not receive atrial pacing or HTEA. Electrophysiological examinations were performed in all groups. Cardiac nerves were immunocytochemically stained with anti-growth-associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. The protein expressions of nerve growth factor (NGF), GAP43 and TH in atrial myocardium were also studied by western blot. In addition, the plasma levels of C-reactive protein (CRP) and norepinephrine, as well as atrial production of superoxide anion (O(2)(·-)) and malondialdehyde, were measured. In the HTEA group, atrial effective refractory period increased (P < 0.05) and AF maintenance decreased (P < 0.01) significantly compared with the control group. The densities of GAP43-positive nerves and TH-positive nerves were significantly lower in the HTEA group compared with the control group. The protein levels of NGF, GAP43 and TH were also lower in the HTEA group compared with the control group. A significant positive correlation between the expressions of NGF and GAP43 (P < 0.01) was observed. A similar correlation was demonstrated for NGF and TH (P < 0.01) in our study. Furthermore, the plasma levels of CRP and norepinephrine, as well as the amount of O(2)(·-) and malondialdehyde produced from myocardium, decreased in the HTEA group compared with the control group. In conclusion, HTEA inhibited electrical and nerve remodeling and reduced the maintenance of AF in a canine AF model, in which process HTEA exhibited anti-inflammatory and antioxidant effects, indicating that, in addition to the efferent cardiac sympathetic nerve, afferent fibers also play an important role in the initiation and/or maintenance of AF.

Rapamycin protects heart from ischemia/reperfusion injury independent of autophagy by activating PI3 kinase-Akt pathway and mitochondria K(ATP) channel.

OBJECTIVES: The purpose of this study was to investigate potential roles of rapamycin, a macrocytic lactone produced by Streptomyces hygroscopicus, in myocardial ischemia/reperfusion (I/R) injury. METHODS: Male Wistar rats were pretreated with three different doses of rapamycin (0.25, 2, and 5 mg/kg). Then, isolated rat hearts were exposed to 40 min of global ischemia followed by 120 min of reperfusion using a Langendorff apparatus. Western blot analysis was used to examine changes in the expression levels of ERK1/2 and Akt kinases and LC3 -II/I (a marker of autophagy). The area of myocardial infarction and cardiac function were evaluated. RESULTS: Our results demonstrated that rapamycin mediates cardioprotection in a dose-dependent manner in isolated rat hearts during myocardial I/R injury. Significant a autophagy was induced by rapamycin during I/R. Both, the mitochondrial K(ATP)-channel blocker 5-hydroxydecanoate (5-HD) and the PI3K inhibitor LY294002 (LY) abolished the protection afforded by rapamycin completely, while the inhibitors alone did not influence the infarct size in control hearts. However, the ERK1/2 inhibitor PD98059(PD) and the blocker of autophagy 3-methyladenine (3-MA) had no effect on rapamycin-mediated cardioprtection. CONCLUSIONS: Cardioprotection afforded by rapamycin involves the PI3K pathway and the activation of mitochondrial K(ATP)-channels, but is independent of rapamycin-induced autophagy. This study may have significant impact on clinical practice.

[Atorvastatin use and coronary flow reserve in patients with coronary slow flow].

OBJECTIVE: To investigate the impact of statin use on coronary flow reserve (CFR) in patients with slow coronary flow. METHODS: A total of 91 patients with chest pain and coronary slow flow but normal coronary angiography were included in this study, patients were divided into statin group (atorvastatin 20 mg/d for 8 weeks, n = 51) and non-statin group (n = 40), 26 healthy subjects with normal angiography and negative exercise ECG test served as normal controls. Blood cholesterol was measured. Doppler coronary flow velocity and Doppler reserve measurement of distal left anterior descending were recorded at rest and adenosine infusion (140 microgxkg(-1)xmin(-1)) induced hyperemia state, CFR was calculated by the ratio of maximal hyperemia and baseline peak diastolic coronary flow velocity (hCFV and bCFV) before and after atorvastatin treatment. RESULTS: (1) Eight weeks later, total cholesterol and LDL-C levels were significantly lower in statin group than in non-statin group and control group [TC (3.83 +/- 0.80) mmol/L vs. (5.30 +/- 1.18) mmol/L vs. (5.32 +/- 1.17) mmol/L, P < 0.05; LDL-C (2.26 +/- 0.64) mmol/L vs. (3.28 +/- 0.85) mmol/L vs. (3.30 +/- 0.82) mmol/L, P < 0.05]. (2)Baseline CFR levels were significantly lower in statin group and non-statin group than that in control group (2.32 +/- 0.30 vs. 2.25 +/- 0.33 vs. 3.15 +/- 0.34, P < 0.05). Compared with non-statin group and statin group before treatment, 8 weeks statin treatment was associated with reduced bCFV [(26.06 +/- 3.22) cm/s vs. (29.02 +/- 3.36) cm/s and (26.06 +/- 3.22) cm/s vs. (28.43 +/- 3.40) cm/s, P < 0.05], increased hCFV [(77.63 +/- 8.96) cm/s vs. (65.17 +/- 7.22) cm/s and (77.63 +/- 8.96) cm/s vs. (64.58 +/- 6.26) cm/s, P < 0.05] and increased CFR (3.07 +/- 0.29 vs. 2.28 +/- 0.35 and 3.07 +/- 0.29 vs. 2.32 +/- 0.30, P < 0.05). bCFV, hCFV and CFR of statin group post treatment were similar to those of controls (P > 0.05). CONCLUSION: Patients with coronary slow flow were associated with lower CFR which could be significantly improved by statin therapy.

[Effect of beta3-adrenoceptor antagonist on the cardiac function and expression of endothelial nitric oxide synthase in a rat model of heart failure].

OBJECTIVE: To investigate the effect of beta(3)-adrenoceptor (beta(3)-AR) antagonist (SR59230A) on the cardiac function and left ventricular remodeling in a rat model of heart failure induced by isoproterenol (ISO), and to probe into its mechanism. METHODS: Eight rats were randomly selected to serve as controls from 85 male adult Wistar rats. After a heart failure model was reproduced, twenty remain rats were randomly divided into ISO group (n = 10) and SR59230A group (SR group, n = 10). ISO group received intraperitoneal injection of 1 ml saline twice a day; SR group received intraperitoneal injection of 85 nmol SR59230A in 1 ml saline twice a day; control group received no treatment. The parameters determined included echocardiogram, the expression of nitric oxide synthase (eNOS) of left ventricle by the technique of reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, cyclic guanosine monophosphate (cGMP) level by enzyme linked immunosorbent assay (ELISA), the ratio of left ventricular weight and body weight (LVW/BW), and the ratio of lung weight and body weight (PW/BW). RESULTS: Compared with control group, the left ventricular end systolic pressure (LVESP), the maximum and minimum first derivative of left ventricular pressure (+/-dp/dtmax) were significantly decreased (all P<0.01), while heart rate (HR) and left ventricular end-diastolic pressure (LVEDP) were significantly increased (both P<0.01) in ISO group. Compared with ISO group, LVESP, +/-dp/dtmax were markedly higher (P<0.05 or P<0.01) respectively, whereas HR and LVEDP were markedly lower (P<0.05 and P<0.01) in SR group, and there was no difference in HR between SR group and control group (P>0.05), while LVEDP was higher in RS group than control group (P<0.01). The levels of eNOS mRNA, protein and cGMP were significantly lower in SR group compared with ISO group (all P<0.01). In addition, when compared with ISO group, LVW/BW ratio and PW/BW ratio in SR group were also decreased (both P<0.05). CONCLUSION: beta(3)-AR antagonist SR59230A can block the beta(3)-AR-NOS-cGMP pathway and improve cardiac function in heart failure in rat when if is administered for a long term. SR59230A can also improve left ventricular remodeling in a certain degree.

[The effects of combined beta(1) adrenergic receptor antagonist and beta(2) adrenergic receptor agonist therapy on cardiac function and myocardial apoptosis in heart failure rats].

OBJECTIVE: To observe the effects of combined beta(1) adrenergic receptor (AR) antagonist with beta(2)AR agonist therapy on cardiac function and cardiomyocyte apoptosis in heart failure rats. METHODS: Heart failure was induced by isoproterenol and rats were randomly divided into metoprolol group (50 mg/kg twice daily/gavage, n = 11), combined treatment group (fenoterol 125 microg/kg and metoprolol 50 mg/kg twice daily/gavage, n = 11) and placebo group (saline, n = 10), another normal 9 male Wistar rats served as control group. After 8 weeks' treatment, cardiac function, apoptosis index (AI), Caspase-3 activity, expression levels of bcl-2 and bax protein, organ weight/body weight and collagen volume fraction (CVF) were evaluated. RESULTS: (1) Left ventricular end diastolic dimension, left ventricular end systolic dimension and E/A ratio were significantly increased and fractional shortening, ejection fraction significantly reduced post isoproterenol (all P < 0.05 vs. control) and these changes were significantly attenuated by metoprolol alone (all P < 0.05 vs. placebo) and further attenuated by the metoprolol and fenoterol combination therapy (all P < 0.05 vs. placebo and metoprolol). (2) Left ventricular weight to body weight ratio, lung weight to body weight ratio and CVF were also significantly reduced in metoprolol and combined treatment group than those in placebo group (all P < 0.01). (3) Compared with placebo group, AI and Caspase-3 activity were significantly lower in metoprolol group (all P < 0.01 vs. placebo) and further reduced in combined treatment group (all P < 0.01 vs. metoprolol). (4) The expression level of bax protein was significantly lower in metoprolol group while bcl-2/bax significantly higher than those in placebo group. These changes were more significant in combined treatment group (all P < 0.01 vs. metoprolol). CONCLUSIONS: beta(1)AR antagonist in combination with beta(2)AR agonist further improved the cardiac function and prevented cardiac remodeling compared with using beta(1)AR antagonist alone in heart failure rats. Downregulated bax and upregulated bcl-2/bax expressions might contribute to the observed beneficial therapy effects by reducing cardiomyocyte apoptosis in these animals.

Chronic blocking of beta 3-adrenoceptor ameliorates cardiac function in rat model of heart failure.

BACKGROUND: Stimulation of the heart beta 3-adrenoceptor (AR) may result in a negative inotropic effect. Being up-regulated, beta 3-AR plays a more important role in the regulation of cardiac function during heart failure. However, the effect of chronic blocking of beta 3-AR on heart failure has not been fully elucidated. In this study, we used a selective beta 3-AR antagonist SR59230A to treat a well defined heart failure rat model chronically, then evaluated its effect on cardiac function and investigated the mechanism. METHODS: Male Wistar rats were chosen randomly as controls (n = 8). Isoproterenol induced heart failure rats were randomly divided into ISO group (n = 10) and SR group (n = 10). The ISO group received intraperitoneal injection of 1 ml saline twice a day; the SR group received intraperitoneal injection of SR59230A 85 nmol in 1 ml saline twice a day; and the control group received no treatment. The treatment was started 24 hours after the last isoproterenol injection and continued for 7 weeks. Then we measured the following indexes: the ratio of heart weight to body weight (HW/BW) and the ratio of left ventricular weight to body weight (LVW/BW), collagen volume fraction (CVF), left ventricular end diastolic dimension (LVEDd), left ventricular end systolic dimension (LVESd), ejection fraction (EF), fractional shortening (FS) and the ratio of E wave to A wave (E/A), the mRNA and protein expression of beta 3-AR and eNOS, and cGMP level in the heart. RESULTS: The ratios HW/BW and LVW/BW were significantly increased in the ISO group compared with the control group (P < 0.01), but they were limited in the SR group (P < 0.05 compared with the ISO group). CVF increased in the ISO group and the SR group (P < 0.01), but it was significantly attenuated in the SR group (P < 0.01). LVEDd, LVESd and E/A ratio were significantly increased in the ISO group compared with the control group (P < 0.01), while EF and FS were significantly decreased (P < 0.01). Compared with the ISO group, the SR group showed that LVEDd, LVESd and E/A ratio were significantly decreased (P < 0.01), whereas EF and FS were significantly increased (P < 0.01). beta(3)-AR and eNOS mRNA and protein in the ISO group were significantly increased when compared with the control group (P < 0.01). These increases were all attenuated in the SR group compared with the ISO group (P < 0.01). The level of cGMP in myocardial tissue was significantly increased in the ISO group compared with the control group (P < 0.01), whereas SR59230A treatment normalized this increment (P < 0.01). CONCLUSIONS: Chronic blocking of beta 3-AR could ameliorate cardiac function in heart failure rats and its mechanism involves inhibition of the negative inotropic effect and attenuation of cardiac remodeling.

[IL-10 gene modification on immature dendritic cells induces antigen-specific tolerance in experimental autoimmune myocarditis].

OBJECTIVE: To investigate whether IL-10 gene modification on immature dendritic cells (iDC) could induce autoimmune tolerance in rat experimental autoimmune myocarditis (EAM). METHODS: EAM was induced by cardiac myosin immunization on day 0 and day 7 in rats. A total of 2 x 10(6) mature DC (mDC), iDC, pcDNA3 transfected iDC, pcDNA3-IL-10 transfected iDC or PBS were injected intravenously at 5th immunization day. Three weeks later, echocardiography and HE staining were performed to observe the cardiac function and myocardial inflammation. Th1/Th2 cytokines were detected by ELISA and MHC-II molecules, costimulatory molecules were identified by flow cytometry. In vitro T lymphocyte proliferation assay and adoptive transfer of DCs were performed to determine the antigen specific tolerance induced by IL-10 gene modification on iDCs. RESULTS: EAM rats treated with pcDNA3-IL-10 transfected iDC showed improved cardiac function and reduced inflammatory cells infiltration into myocardium. Moreover, lower Th1 and higher Th2-type response was induced, MHC-II and costimulatory molecules down-regulated and antigen specific immunological responses towards cardiac myosin inhibited in pcDNA3-IL-10-iDC treated EAM rats. CONCLUSION: Treatment with IL-10 gene modified iDCs could ameliorates EAM by inducing Th2 polarization and down-regulation of MHC-II molecules and costimulatory molecule expressions.

Association of HLA class II DRB1, DPA1 and DPB1 polymorphism with genetic susceptibility to idiopathic dilated cardiomyopathy in Chinese Han nationality.

Although the aetiology of idiopathic dilated cardiomyopathy (IDC) remains unclear, many immunological abnormalities involving changes in cell-mediated and humoral immunity may be associated with cardiac impairment in IDC. Autoimmune mechanisms are likely to participate in the pathogenesis of at least a subgroup of IDC and components of the major histocompatibility complex may serve as markers for the propensity to develop immune-mediated myocardial damage. Human leukocyte antigen (HLA) class II genes, which are highly polymorphic, play an important role in the activating of immune responses and thus control the predisposition for or protection from IDC. This study explores the possible contribution of HLA-DRB and DP polymorphisms to IDC susceptibility. DNA genotyping for HLA-DRB1, DPA1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 198 IDC patients and 136 random selected healthy Han ethnic individuals living in Northern China. IDC patients were, sub-grouped into asymptomatics (subgroup A), with arrhythmia (subgroup B) and with overt congestive heart failure (subgroup C) according to the clinical manifestations and electrocardiogram or echocardiographic characteristics. ADP/ATP autoantibody was detected in IDC group by immunoblot analysis. The results revealed that HLA-DR15, -DPB*0601 frequencies were significantly elevated in IDC group compared with normal control. The DPB1*0601 allele in homozygous form or in combination with allele DPB1*2301 or *3901, was found present more often in IDC patients. The predominance of HLA-DR4 allele was observed in subgroup B after stratification. However, the frequency of DPB1*0101 allele increased in the control than in the IDC group. The frequency of HLA-DPB1*0601 allele was significantly higher in IDC patients with positive autoantibody against ADP/ATP carrier of myocardial mitochondria in contrast to those with negative autoantibody. We conclude that HLA-DR4, -DR15, -DPB1*0601 alleles confers susceptibility to, while DPB1*0101 allele confers protection from IDC among individuals of northern Chinese Han nationality. The glutamate at position 69 in the second exon of DPB1*0601, as a key residue for special conformation of HLA-DP, may confer predisposition to IDC. HLA-DR and -DP alleles polymorphisms may serve as genetic markers for IDC and be involved in the regulation of the immune specific response to auto or exterior anti-myocardium antibodies.

Antigen-specific tolerance induced by IL-10 gene modified immature dendritic cells in experimental autoimmune myocarditis in rats.

BACKGROUND: Experimental autoimmune myocarditis (EAM) in rats is a T-cell-mediated disorder. The initiation and maintenance of autoimmune responses in EAM depend on the maturation state of dendritic cells. IL-10 is a pleiotrophic immunomodulatory cytokine that functions at different levels of the immune response, so it has emerged as a promising therapeutic factor for the treatment of autoimmune/inflammatory diseases. This study was designed to test the hypothesis that IL-10 gene modified bone marrow-derived immature dendritic cells (iDCs) ameliorate EAM and to explore the underlying mechanisms. METHODS: EAM was induced using the methods of cardiac myosin immunization on day 0 and day 7. Immature and mature bone marrow-derived dendritic cells (BMDCs) were generated without or with the stimulation by lipopolysaccharide (LPS) and the phenotype was analyzed by flow cytometry. Some of the iDCs were transfected by pcDNA3-IL-10 plasmid. 2 x 10(6)/per rat mature DC (mDC), immature DC (iDC), pcDNA3 transfected iDC, pcDNA3-IL-10 transfected iDC or phosphate buffered saline (PBS) were injected intravenously for treatment 5 days after the first immunization. On day 21, HE staining was performed to detect the myocardial inflammation and T lymphocyte proliferation assay was used to determine the effects of IL-10 gene transfected iDC on autoreactive T cell proliferation. Expression of IkappaB, the inhibitor of NF-kappaB pathway, was determined by Western blot. RESULTS: BMDCs generated in a medium supplemented with granulocyte-macrophage-colony-stimulating factor (GM-CSF) were relatively immature, as determined by flow cytometry. However, stimulation with LPS induced these cells to become mature (m) DCs with higher levels of surface major histocompatibility complex (MHC)-II and costimulatory molecules. Intravenous administration of iDCs, especially pcDNA3-IL-10 transfected iDC, ameliorated the histopathological severity of the myosin induced-EAM, and the effect was lost after the DCs underwent maturation induced by in vitro exposure to LPS. IL-10 gene modified iDC inhibited the antigen specific T cell responses towards cardiac myosin. IkappaB protein was up-regulated significantly in the IL-10 gene modified iDC group. CONCLUSIONS: IL-10 gene modified iDC induced antigen-specific tolerance in EAM. The underlying mechanisms may be related to costimulatory molecules down-regulation and NF-kappaB pathway inhibition.

[The experimental study on changes of endothelial nitric oxide synthase and plasminogen activator inhibitor-1 protein in the canine atrial fibrillation model].

OBJECTIVE: To evaluate the changes in the expressions of endothelial nitric oxide synthase (eNOS) and plasminogen activator inhibitor-1 (PAI-1) and the alterations of nitric oxide (NO) concentration in atrial endocardium in atrial fibrillation (AF) in order to investigate the mechanisms that contribute to thrombosis. METHODS: In canine AF was produced with rapid atrial pacing at 400 bpm for 6 weeks, whereas the controls had no atrial pacing. NO production was measured by NO-specific microelectrode. The expression of endocardial eNOS and PAI-1 protein were determined by Western blot analysis and immunohistochemical Staining. Plasma levels of PAI-1 were analysed by Enzyme-linked immunoadsorbent assay. RESULTS: Left atrial NO concentration was decreased in AF than that in controls [(23.4 +/- 5.8)nmol/L vs (63.8 +/- 16.1)nmol/L, P < 0.01]. Endocardial eNOS expression was also significantly decreased (855 +/- 217 vs 2320 +/- 694, P < 0.05), whereas the expression of the PAI-1 was increased (3164 +/- 827 vs 1371 +/- 352, P < 0.01). Neither NO concentration, nor PAI-1, eNOS expression were altered in the right atria at the same time. A significant increase for plasma levels of PAI-1 was also detected in AF group. No correlation was found between eNOS and PAI-1 protein expression (r = 0.217, P > 0.05). CONCLUSION: In the canine model AF was associated with a marked decrease in endocardial NOS expression and NO concentration and with an increase in PAI-1 expression in the left atrium, which may contribute to the thrombosis in AF.