ABSTRACT
Background & objectives: angiotensin II receptor type 1 (AaT1) is known to be involved in the pathogenesis of hypertension. tThis study was undertaken to explore the effect of active immunization against AaT1 receptor on blood pressure and small artery remodelling in spontaneously hypertensive rat (SHR). Methods: Male SHR and Wistar rats aged two months were actively immunized with different peptides (AaTR12185、AaTR10014 and AaTR12181) corresponding to particular sequences of rat receptor, while another SHR group was given losartan (10 mg/kg/day) orally once a day. Aanti-AaT1 receptor antibodies were detected by ELISAa and blood pressure was measured. The effect of the antibodies on the artery and vascular smooth muscle cells (VSMCs) proliferation was studied. Results: all immunized animals produced antibodies against the particular peptides. The systolic blood pressure was decreased in the SHR immunized with peptide-AaTR12181 compared with the control. However, no changes were observed in the SHR immunized with other two peptides. The Wistar rats immunized with the three peptides did not show any changes in blood pressure. The media/lumen area ratio of the mesenteric artery was reduced in SHR immunized with and similar to that of the SHR treated with losartan. The antibody from SHR immunized with AaTR12181 had no effect on the proliferation of VSMC. But it could inhibit the proliferation caused by angiotensin II and its effect at the titre of 1:40 was similar to that of 1μmol/l losartan. Interpretation & conclusions: Our findings demonstrated that the antibody from SHR immunized with AaTR12181 had the effect of reducing blood pressure and target organ protection similar to losartan. Aactive immunization against AaT1 receptor may be a promising strategy in future for the treatment of hypertension.
ABSTRACT
Microthrombosis may be involved in the pathogenesis of cardiac microangiopathy due to diabetes. Recent studies have shown that fibrinogen-like protein 2 (fgl2) plays a pivotal role in microthrombosis in viral hepatitis, acute vascular xenograft rejection and cytokine-induced fetal loss syndrome. The current study was designed to examine the expression of fgl2 in microvascular endothelial cells and investigate the effects of microthrombi due to fgl2 on cardiac function and structure in rats with type 2 diabetes. Following induction of type 2 diabetes, 24 rats were observed dynamically. Fgl2 expression and related cardiac microthrombosis were examined. Local or circulating TNF-a was measured. Coronary flow (CF) per min was calculated as an index of cardiac microcirculation. Cardiac function and morphology were evaluated. It was found that Fgl2 was highly expressed in cardiac microvascular endothelial cells of rats with type 2 diabetes, which was promoted by local or circulating TNF-α. The Fgl2 expression was associated with cardiac hyaline microthrombosis. In parallel with the fgl2 expression, CF per min, cardiac diastolic or systolic function and cardiac morphology were aggravated to some extent. It was concluded that in rats with type 2 diabetes, microthrombosis due to fgl2 contributes to the impairment of cardiac diastolic or systolic function and morphological changes.
ABSTRACT
Autoimmune is involved in the pathogenesis of ventricular remodeling in acute myocardial infarction (AMI). In the present study, we investigated the effect of anti-cardiac myosin heavy chain antibodies (AMHCA) from patients with AMI on rat cardiomyocyte apoptosis. Cardiomyocyte apoptosis was observed and measured by DNA end labeling and Annexin- V/PI double-staining assay.The expression of apoptosis related p53 and Bcl-2 protein and the second messenger calcium were detected respectively by Western blotting, patch clamp and confocal calcium imaging. The results showed that AMHCA was able to induce cardiomyocyte apoptosis in a dose dependent manner.Apoptosis-accelerating nucleoprotein p53 was up-regulated, while apoptosis-inhibiting cytoplasmic protein Bcl-2 was down-regulated. In parallel, cytoplasmic calcium concentration was elevated.There was no effect on L-type calcium currents. It is concluded that AMHCA in patients with AMI as a novel triggering factor can induce cardiomyocyte apoptosis, which contributes to ventricular remodeling.
ABSTRACT
The aim of our study was to gain insight into the molecular and cellular mechanisms of post-angioplasty restenosis using balloon catheter-induced injury model in the rat carotid artery. SD rats were subjected balloon catheterization at one side carotid artery as study group and another side as control group. Six rats were killed on the 6 h, and 3rd, 7th, 14th, 28th day after balloon-induced injury respectively. The intimal thickness and the expression of NF-кB and I-кB were detected by HE-staining, gel electrophoretic mobility shift assay (EMSA) and Western-blot methods. The results showed that: (1) The thickening of intima was observed on the 3rd day after balloon-induced injury,and it became more significant on the 7th, 14th and 28th day. The area ratio of intima/media was in-creased significantly (P＜0.05); (2) The expression of NF-кB was not detectable in the control group,however, in study group, the expression of NF-кB was detected on the 6th h after balloon-induced injury, reached the peak on the 14th day, and on 28th day, strong expression of NF-кB was observed;(3) The expression of I-кB protein was reduced after balloon-induced injury, and there were signifi-cant differences between the study group and the control group (P＜0.05). It was concluded that the alteration of NF-кB/I-кB system might play an important role in aberrant proliferation within the in-tima and vascular remodeling following vascular injury. To block NF-кB activation and its role in ar-terial restenosis initiation may potentially provide a novel therapeutic tool for the treatment and pre- vention of arterial restenosis.
ABSTRACT
The purpose of the study was to observe the effect of rapamycin (RAPA) on the differentiation and maturation of rat bone marrow-derived dendritic cells (BMDCs) in vitro. BMDCs from Wistar rats were cultured with granulocyte-macrophage colony-stimulating factor plus interleukin-4in the presence or absence of RAPA (20 ng/mL), and stimulated with lipopolysaccharide (LPS) for 24h before cells and supernatants were collected. Surface phenotype of BMDCs was flow-cytometrically detected to determine the expression of maturation markers, MHC class Ⅱ and CD86. Supematants were analyzed for the production of IL-12 and IFN-γ cytokines by using ELISA.BMDCs were co-cultured with T cells from Lewis rats and mixed lymphocyte reaction was assessed by MTT method. The morphology of BMDCs stimulated with LPS remained immature after RAPA pretreatment. RAPA significantly decreased the CD86 expression, impaired the IL-12 and IFN-γproduction of BMDCs stimulated with LPS, and inhibited the proliferation of allogeneic T cells. In conclusion, RAPA can inhibit the maturation of BMDCs stimulated with LPS in terms of the morphology, surface phenotype, cytokine production, and ability of BMDCs to stimulate the proliferation of allogeneic T cells in vitro.
ABSTRACT
In ischemic hypertrophic myocardium, contractile dysfunction can be attributed to the decreased calcium induced calcium release (CICR) in cytoplasm. This study aimed to investigate the electrophysiological properties and the expression of L calcium channel subunits in post-MI myocardium. The ischemic heart remodeling model was established in SD rats. The expressions of calcium channel subunits were determined by realtime RT-PCR. Whole cell patch clamp was used to record the electrophysiological properties of L calcium channel. The results showed that the L calcium channel agonist Bayk 8644 induced the significantly decreased CICR in the rat cardiomyocyte 6weeks after myocardial infarction (MI). In the post-MI cardiomyocytes, the amplitude of ICaL decreased dramatically and the inactivation curve of the current shifted to more negative potential. At mRNA level, the expression of the calcium channel alphalc, beta2c subunits decreased dramatically in the ventricle of post-MI rats. The expression of alpha2/delta subunit, however, remained constant.It is concluded that the abnormal expression of the L calcium channel subunits in post-MI cardiomyocytes contributes to the ICaL decrease at early stage of the ischemic remodeling in cardiomyocytes,which leads to the decreased CICR in the cell and contractile dysfunction of myocardium.
ABSTRACT
The cytokine repertoire of ADP/ATP carrier-specific humoral immune responses and the cytokine-dependent anti-ADP/ATP carrier antibody IgG subclasses were examined in a cohort of ADP/ATP carrier-immunized BALB/c mice treated with anti-CD4 monoclonal antibody. Eighteen male BALB/c mice (6-8 weeks old) were randomized into 3 groups: dilated cardiomyopathy (DCM)group, DCM-tolerance (Tol) group and control group. The mice in DCM group were immunized with the peptides derived from human ADP/ATP carrier protein for 6 months and mice in the control group were sham-immunized, while the mice in DCM-Tol group were immunized with ADP/ATP carrier protein and anti-CD4 McAb simultaneously. Serum autoantibody against ADP/ATP carrier and IgG subclasses were measured by ELISA, intracellular cytokines IFN-γ and IL-4 of Th cells were monitored with flow cytometry, and splenic T cell cytokines IFN-γ, IL-2, IL-4 and IL-6 were detected by using real-time fluorescent quantitative PCR. The results showed that the autoantibody against ADP/ATP carrier was found in all mice in DCM group, and the antibody level, serum IgG1 and IgG2a subclasses, cytokines in T cells and Th cells were all elevated in DCM group, as compared with those in control group (P＜0.01). On the other hand, in DCM-Tol group, the autoantibody level and contents of all the cytokines were significantly different from those in DCM group (P＜0.01), and were close to those in control group. And the levels of IgG1, IgG2a, IgG2b and IgG3 were influenced,to varying degrees, by anti-CD4 McAb as compared with those in DCM group. All these four types of IgG subclasses were substantially decreased in DCM-Tol group as compared with DCM group. It is concluded that the treatment with anti-CD4 McAb could prevent the activation of T cells, reverse the abnormal secretion of cytokines and the imbalance between Th1/Th2 cell subsets and abnormal production of autoantibody against ADP/ATP carrier, and eventually avoid myocardial injuries.