Activation of ETAR and ETBR in myocardial tissue characterizes heart failure induced by experimental autoimmune myocarditis.

BACKGROUND: Endothelial dysfunction is characterized by an imbalance between endothelium-derived vasodilatory and vasoconstrictive effects and may play an important role in the development of heart failure. An increasing number of studies have shown that endothelial-derived NO-mediated vasodilation is attenuated in heart failure patients. However, the role of endothelin-1 (ET-1) in heart failure remains controversial due to its different receptors including ET-1 receptor type A (ETAR) and ET-1 receptor type B (ETBR). The aim of this study was to determine whether ET-1 and its receptors are activated and to explore the role of ETAR and ETBR in heart failure induced by myocarditis. METHODS: We constructed an animal model of experimental autoimmune myocarditis (EAM) with porcine cardiac myosin. Twenty rats were randomized to the control group (3 weeks, n = 5), the extended control group (8 weeks, n = 5), the EAM group (3 weeks, n = 5), the extended EAM group (8 weeks, n = 5). HE staining was used to detect myocardial inflammatory infiltration and the myocarditis score, Masson's trichrome staining was used to assess myocardial fibrosis, echocardiography was used to evaluate cardiac function, ELISA was used to detect serum NT-proBNP and ET-1 concentrations, and immunohistochemistry and western blotting were used to detect ETAR and ETBR expression in myocardial tissue of EAM-induced heart failure. Subsequently, a model of myocardial inflammatory injury in vitro was constructed to explore the role of ETAR and ETBR in EAM-induced heart failure. RESULTS: EAM rats tended to reach peak inflammation after 3 weeks of immunization and developed stable chronic heart failure at 8 weeks after immunization. LVEDd and LVEDs were significantly increased in the EAM group compared to the control group at 3 weeks and 8 weeks after immunization while EF and FS were significantly reduced. Serum NT-proBNP concentrations in EAM (both 3 weeks and 8 weeks) were elevated. Therefore, EAM can induce acute and chronic heart failure due to myocardial inflammatory injury. Serum ET-1 concentration and myocardial ETAR and ETBR protein were significantly increased in EAM-induced heart failure in vivo. Consistent with the results of the experiments in vivo, ETAR and ETBR protein expression levels were significantly increased in the myocardial inflammatory injury model in vitro. Moreover, ETAR gene silencing inhibited inflammatory cytokine TNF-α and IL-1ß levels, while ETBR gene silencing improved TNF-α and IL-1ß levels. CONCLUSIONS: ET-1, ETAR, and ETBR were activated in both EAM-induced acute heart failure and chronic heart failure. ETAR may positively regulate EAM-induced heart failure by promoting myocardial inflammatory injury, whereas ETBR negatively regulates EAM-induced heart failure by alleviating myocardial inflammatory injury.

ET-1 receptor type B (ETBR) overexpression associated with ICAM-1 downregulation leads to inflammatory attenuation in experimental autoimmune myocarditis.

Background: An experimental autoimmune myocarditis rat model was established by subcutaneous injection of porcine myocardial myosin (PCM). The effect of ET-1 receptor type B (ETBR) overexpression on autoimmune myocarditis was observed via tail vein injection of ETBR overexpression lentivirus in rats. We further investigated the mechanisms involved in the regulation of autoimmune myocarditis by ETBR overexpression. Methods: Six rats were randomly selected from 24 male Lewis rats as the NC group, and the remaining 18 rats were injected with PCM on Day 0 and Day 7, to establish the experimental autoimmune myocarditis (EAM) rat model. The 18 rats initially immunized were randomly divided into three groups: the EAM group, ETBR-oe group, and GFP group. On Day 21 after the initial immunization of rats, cardiac echocardiography and serum brain natriuretic peptide (BNP) analysis were performed to evaluate cardiac function, myocardial tissue HE staining was performed to assess myocardial tissue inflammatory infiltration and the myocarditis score, and mRNA expression of IFN-γ, IL-12, and IL-17 was detected by qRT-PCR. Subsequently, immunohistochemical analysis was performed to detect the localization and expression of the ETBR and ICAM-1 proteins, and the expression of ETBR and ICAM-1 was verified by qRT-PCR and western blotting methods. Results: On Day 21 after initial immunization, left ventricular end-diastolic diameter (LVEDd), left ventricular end-systolic diameter (LVEDs), and serum BNP concentrations increased in the hearts of rats in the EAM group compared with the NC group (P < 0.01), and ejection fraction (EF) and fractional shortening (FS) decreased compared with those of the normal control (NC) group (P < 0.01). LVEDd, LVEDs, and serum BNP concentrations decreased in the ETBR-oe group compared with the EAM group, while EF and FS increased significantly (P < 0.01). HE staining showed that a large number of inflammatory cell infiltrates, mainly lymphocytes, were observed in the EAM group, and the myocarditis score was significantly higher than that of the NC group (P < 0.01). Compared with that of the EAM group, myocardial tissue inflammatory cell infiltration was significantly reduced in the ETBR-oe group, and the myocarditis scores were significantly lower (P < 0.01). The mRNAs of the inflammatory factors IFN-γ, IL-12 and IL-17 in myocardial tissue of rats in the EAM group exhibited elevated levels compared with those of the NC group (P < 0.01) while the mRNAs of IFN-γ, IL-12 and IL-17 were significantly decreased in the ETBR-oe group compared with the EAM group (P < 0.01). Immunohistochemistry showed that the staining depth of ETBR protein in myocardial tissue was greater in the EAM group than in the NC group, and significantly greater in the ETBR-oe group than in the EAM group, while the staining depth of ICAM-1 was significantly greater in the EAM group than in the NC group, and significantly lower in the ETBR-oe group than in the EAM group. The ICAM-1 expression level was significantly higher in the EAM group than in the NC group (P < 0.01), and was significantly lower in the ETBR-oe groupthan in the EAM group (P < 0.01).

Tetramethylpyrazine Showed Therapeutic Effects on Sepsis-Induced Acute Lung Injury in Rats by Inhibiting Endoplasmic Reticulum Stress Protein Kinase RNA-Like Endoplasmic Reticulum Kinase (PERK) Signaling-Induced Apoptosis of Pulmonary Microvascular Endothelial Cells.

BACKGROUND Acute lung injury (ALI) is a life-threatening complication of sepsis. Tetramethylpyrazine (TMP) has been used in the clinical treatment of vascular diseases. The aim of this study was to investigate the therapeutic effects and possible involved mechanisms on ALI. MATERIAL AND METHODS Cecal ligation and puncture (CLP) was used to establish a sepsis model in rats. TMP at various dosages were administrated to rats using a intragastric method. Animal survival rate was calculated. The lung functions were evaluated by lung weight/dry weight ratio (W/D), PaO2, dynamic compliance (DC), and airway resistance index (ARI). Pulmonary microvascular endothelial cells (PMVECs) were isolated from lungs harvested from rats with sepsis. TUNEL assay was used to detect apoptosis. Protein expression and phosphorylation levels were assessed by western blotting. RESULTS TMP administration increased the survival rate of septic rats. TMP also decreased W/D and DC, but increased PaO2 and ARI in septic rats. Moreover, PMVECs apoptosis was inhibited in septic rats that received TMP treatment. The expression levels of GRP78, ATF4, caspase-12, active caspase-3, as well as the phosphorylation levels of PERK and eIF2α were suppressed in PMVECs isolated from TMP-treated septic rats. CONCLUSIONS TMP alleviated sepsis-induced ALI by suppressing PMVECs apoptosis via PERK/eIF2α/ATF4/CHOP apoptotic signaling in endoplasmic reticulum stress.

Anti-Inflammatory Effects of Monoammonium Glycyrrhizinate on Lipopolysaccharide-Induced Acute Lung Injury in Mice through Regulating Nuclear Factor-Kappa B Signaling Pathway.

The present study aimed to investigate the therapeutic effect of monoammonium glycyrrhizinate (MAG) on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and possible mechanism. Acute lung injury was induced in BALB/c mice by intratracheal instillation of LPS, and MAG was injected intraperitoneally 1 h prior to LPS administration. After ALI, the histopathology of lungs, lung wet/dry weight ratio, protein concentration, and inflammatory cells in the bronchoalveolar lavage fluid (BALF) were determined. The levels of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) in the BALF were measured by ELISA. The activation of NF-κB p65 and IκB-α of lung homogenate was detected by Western blot. Pretreatment with MAG attenuated lung histopathological damage induced by LPS and decreased lung wet/dry weight ratio and the concentrations of protein in BALF. At the same time, MAG reduced the number of inflammatory cells in lung and inhibited the production of TNF-α and IL-1ß in BALF. Furthermore, we demonstrated that MAG suppressed activation of NF-κB signaling pathway induced by LPS in lung. The results suggested that the therapeutic mechanism of MAG on ALI may be attributed to the inhibition of NF-κB signaling pathway. Monoammonium glycyrrhizinate may be a potential therapeutic reagent for ALI.

[The role of hydrogen sulfide and cystathionine-gamma-lyase in allergic rhinitis guinea pigs].

OBJECTIVE: To study the change of endogenous hydrogen sulfide (hydrogen sulfide, H2S) and its rate-limiting enzyme Cystathionine-gamma-lyase (CSE) in allergic rhinitis through guinea pigs with intervention treatment. METHOD: Twenty-four guinea pigs were divide into 4 groups at random, one group were models of allergic rhinitis (AR) which were established by using ovalbumin, the second group were treated with NaHS after sensitized, the third group were treated with Propargylglycine (PPG) which was suppression of CSE after sensitized, and the last group were treated with saline for control. The concentration of eotaxin of nasal lavage and H2S in plasma were recorded, and then the expression of CSE in nasal mucosa was determined by real-time fluorescence RT-PCR. RESULT: The concentration of eotaxin in nasal lavage of sensitized group were higher than those of control (P < 0.01), and concentration of H2S in plasma and expression of CSE in nasal mucosa were lower than control (P < 0.05). The concentration of eotaxin decreased when treated with NaHS and increased when treated with PGG (P < 0.05). Level of H2S in plasma and expression of CSE increased when treated with NaHS and decreased when treated with PGG (P < 0.05), and the level of H2S was positive linear correlate with the expression of CSE. CONCLUSION: Endogenous H2S perhaps plays a significant role in the pathogenesis of allergic rhinitis, and it was mainly regulated by CSE.