Macrophage polarization is involved in liver fibrosis induced by ß 1-adrenoceptor autoantibody.

Accumulating evidence suggests that liver injury can be induced by the over-expression of ß 1-adrenergic receptors (ß 1-ARs). High titers of autoantibodies specific to ß 1-adrenergic receptors (ß 1-AA) are detected in the sera of heart failure patients, potentially playing agonist-like roles. However, the role of ß 1-AA in liver function has not been characterized. In this study, we collect the sera of primary biliary cholangitis (PBC) patients, a condition which easily develops into liver fibrosis, and analyze the relationship between PBC and ß 1-AA. A passive immunization model is established to assess the effect of ß 1-AA on the liver. Subsequently, the effect of ß 1-AA on macrophages is investigated in vitro. Results show that PBC patients have a high titer and ratio of ß 1-AA, compared to controls. Liver injury and fibrosis are induced by ß 1-AA. In vitro experiments with ROS probe demonstrate that ß 1-AA induces macrophages to produce ROS and secrete TNFα. These effects can be partially reversed by metoprolol, a blocker for ß 1-AR. Results from the transwell and phagocytosis assays show that ß 1-AA promotes macrophage migration and phagocytosis. FCM tests suggest that ß 1-AA induces the alteration of M1 rather than M2 markers in macrophages. Finally, the Annexin V/PI assay indicates that macrophage culture supernatants stimulated by ß 1-AA cause hepatocyte apoptosis. Overall, these results suggest that ß 1-AA is involved in PBC. The ß 1-AA-induced activation, phagocytosis and phenotypic modification of macrophages may play an important role in the development of hepatic fibrosis and injury.

Autoantibodies Against ß1-Adrenoceptor Exaggerated Ventricular Remodeling by Inhibiting CTRP9 Expression.

Background Autoantibodies against the second extracellular loop of the ß1-adrenoceptor (ß1- AA ) act similarly to agonist of ß1-adrenergic receptor, which plays an important role in the pathophysiological characteristics of ventricular remodeling. Recently, considerable lines of evidence have suggested that CTRP9 (C1q tumor necrosis factor-related protein 9) is a potent cardioprotective cardiokine and protects the heart from ventricular remodeling. The aim of this study was to determine the role of CTRP 9 in ventricular remodeling induced by ß1- AA . Methods and Results Blood samples were collected from 131 patients with coronary heart disease and 131 healthy subjects. The serum levels of ß1- AA and CTRP 9 were detected using ELISA . The results revealed that CTRP 9 levels in ß1- AA -positive patients were lower than those in ß1- AA -negative patients, and serum CTRP 9 concentrations were inversely correlated with ß1- AA . ß1- AA monoclonal antibodies (ß1- AA mAbs) were administered in mice with and without rAAV 9- cTnT -Full Ctrp9- FLAG virus for 8 weeks. Reverse transcription-polymerase chain reaction/Western analysis showed that cardiomyocyte CTRP 9 expression was significantly reduced in ß1- AA mAb-treated mice. Moreover, compared with the ß1- AA mAb alone group, cardiac-specific CTRP 9 overexpression improved cardiac function, attenuated adverse remodeling, and ameliorated cardiomyocyte apoptosis and fibrosis. Mechanistic studies demonstrated that CTRP 9 overexpression decreased the levels of G-protein-coupled receptor kinase 2 and promoted the activation of AMP-dependent kinase pathway. However, cardiac-specific overexpression of CTRP 9 had no effect on the levels of  cAMP and protein kinase A activity elevated by ß1-AAmAb. Conclusions This study provides the first evidence that the long-term existence of ß1- AA mAb suppresses cardiac CTRP 9 expression and exaggerates cardiac remodeling, suggesting that CTRP 9 may be a novel therapeutic target against pathologic remodeling in ß1- AA -positive patients with coronary heart disease.

Activation of T Lymphocytes as a Novel Mechanism in Beta1-Adrenergic Receptor Autoantibody-Induced Cardiac Remodeling.

BACKGROUND: Numerous studies have reported significantly elevated titers of serum autoantibody against the second extracellular loop of ß1-adrenoceptor (ß1-AA), a catecholamine-like substance with ß1-adrenergic activity, in patients with heart failure. Although evidence demonstrates that this autoantibody may alter T cell proliferation and secretion, the role of T lymphocytes in heart failure induced by ß1-AA remains unclear. The current study was designed to determine whether T cell disorder contributes to heart failure induced by ß1-AA. METHODS AND RESULTS: ß1-AA monoclonal antibodies (ß1-AAmAb) produced using the hybridoma technique were administered in wild-type mice or T lymphocyte deficiency nudes for 12 weeks. T lymphocytes from heart failure patients and neonatal cardiomyocytes were utilized in vitro. Mouse protein antibody array analysis was employed to detect the cytokines responsible for ß1-AAmAb-induced heart failure. Compared to wild-type mice, T lymphocyte deficiency mice prevented cardiac function from getting worse, attenuated adverse remodeling, and ameliorated cardiomyocyte apoptosis and fibrosis. As shown by protein array, the serum level of interleukin (IL)-6 was significantly lower in the nude group as compared to wild-type after ß1-AAmAb treatment. Mechanistic studies in vitro demonstrated that T lymphocyte culture supernatants stimulated by ß1-AAmAb caused direct damage in the cardiomyocytes, and ß1-AAmAb promoted proliferation of T lymphocytes isolated from patients with heart failure and increased IL-6 release. IL-6-specific siRNA virtually abolished cardiomyocyte apoptosis, suggesting that IL-6 may be a key cytokine released by T lymphocytes and responsible for ß1-AAmAb-induced cardiac remodeling. CONCLUSIONS: Collectively, we demonstrate that ß1-AAmAb-induced cardiac remodeling via mediating T lymphocyte disorder and releasing a variety of IL-6.

Cyclic peptide RD808 reduces myocardial injury induced by ß1-adrenoreceptor autoantibodies.

Autoantibodies against the second extracellular loop of ß1-adrenergic receptor (ß1-AA) have been shown to be involved in the development of cardiovascular diseases. Recently, there has been considerable interest in strategies to remove these autoantibodies, particularly therapeutic peptides to neutralize ß1-AA. Researchers are investigating the roles of cyclic peptides that mimic the structure of relevant epitopes on the ß1-AR-ECII in a number of immune-mediated diseases. Here, we used a cyclic peptide, namely, RD808, to neutralize ß1-AA, consequently alleviating ß1-AA-induced myocardial injury. We investigated the protective effects of RD808 on the myocardium both in vitro and in vivo. RD808 was found to increase the survival rate of cardiomyocytes; furthermore, it decreased myocardial necrosis and apoptosis and improved the cardiac function of BalB/c mice in a ß1-AA transfer model. In vitro and in vivo experiments showed that myocardial autophagy was increased in the presence of RD808, which might contribute to its cardioprotective effects. Our findings indicate that RD808 reduced myocardial injury induced by ß1-AA.

[Angiotensin II type 1 receptor autoantibody induces myocardial fibrosis by activating cardiac fibroblasts].

Myocardial fibrosis (MF) is an important pathological process of cardiac remodeling in patients with heart failure; however its etiology has not been clear. It has been known that the angiotensin II type 1 receptor autoantibody (AT1-AA) is present in patients with heart failure, but it is unclear whether this antibody directly causes MF. In this study, we investigated the role of AT1-AA in MF and its effects on cardiac fibroblasts (CFs). The AT1-AA positive rat model was established by active immunization method, and the measurement of indexes were made in the 8th week after active immunity. The results of heart echocardiography showed that the cardiac systolic and diastolic functions of AT1-AA positive rats were impaired with reduced left ventricular wall thickness and enlarged heart chambers. HE staining results showed that the myocardial fibers were disorganized and ruptured, and Masson staining revealed that the area of collagen fibers around the myocardium and coronary arteries was significantly increased in AT1-AA positive group compared with that of the control group (P < 0.05). Moreover, primary CFs isolated from neonatal rats were cultured and treated with AT1-AA for 48 h. CCK-8 and immunofluorescence staining results showed that AT1-AA enhanced proliferation rate of CFs (P < 0.001), and Western blot results showed that AT1-AA significantly increased expressions of collagen I (Col I), Col III, matrix metalloproteinase-2 (MMP-2) and MMP-9 in CFs (all P < 0.05). Taken together, these results suggest that AT1-AA may induce MF and cardiac dysfunction via activating CFs.

[Research advances in the regulation of cardiovascular metabolic disorders and its related risk factors by C1q/TNF related proteins].

The complement C1q/TNF related protein (CTRP) family is rapidly growing and currently comprises 15 members. Although CTRP proteins share a common structure composed of four distinct domains: a signal peptide at the N terminus, a short variable region, a collagenous domain, and a C-terminal globular domain, which is homologous to adiponectin, each CTRP has a unique tissue expression profile and varied function. In this review we focus on the biochemistry and pleiotropic functions of CTRPs as new molecular mediators regulating cardiovascular metabolic disorders and its related risk factors diseases.