Cardiac macrophages undergo dynamic changes after coxsackievirus B3 infection and promote the progression of myocarditis.

Although most patients with acute viral myocarditis recover spontaneously, some patients progress to heart failure. Perturbations in innate immunity may partially explain the heterogeneity of clinical outcomes. As the most abundant immune cells in the heart, cardiac macrophages have heterogeneous origins, including embryonic-derived resident macrophages (ResMϕs) and monocyte-derived macrophages (MoMFs). However, the time course change and role of cardiac macrophage subsets has not been fully explored. In the present study, we found that BALB/c mice had prolonged MoMF accumulation and low proportions of ResMϕs that could not be restored to normal levels. MoMFs of BALB/c mice generally exhibit an M1-dominant functional phenotype. Moreover, the preferential depletion of MoMF by a C-C chemokine receptor type 2 (CCR2) inhibitor resulted in improved acute myocarditis and chronic fibrosis, as well as the recovery of ResMϕs number and reduced CD4+ T cell expansion. Hence, immunomodulatory therapy that targets the balance among cardiac macrophages and modulates their function is expected to prevent the progression of cardiac injury to overt heart failure and improve adverse outcomes.

Are activated B cells involved in the process of myocardial fibrosis after acute myocardial infarction? An in vivo experiment.

BACKGROUND: Inflammatory cells infiltrate into the ischemic and hypoxic myocardial tissue after myocardial infarction. B cells gather at the site of myocardial injury and secrete cytokines to regulate immune inflammation and fiber repair processes. METHODS: The animal experiment used ligation of the left anterior descending (LAD) artery of C57BL/6 mice to establish a mouse acute myocardial infarction (AMI) model to observe changes in activated B cells and cytokines at different time points. Twelve-week-old C57BL/6 male mice were randomly divided into the Sham group (24 mice) (thread under the LAD artery without ligation) and the AMI group (64 mice). In addition, C57BL/6 B-cell knockout (BKO) mice and C57BL/6 wild-type (WT) mice were used to establish AMI models to observe the expression levels of cardiomyocyte cytokines, such as TNF-α IL-1ß, IL-6, TGF-ß1, COL1-A1, COL3-AIII, TIMP, and MMP9. Moreover, pathological and collagen changes in the myocardium were analysed. One-way ANOVA and LSD method was used for comparisons of multiple and pairwise groups respectively. P < 0.05 indicated significant differences. RESULTS: An AMI model of C57BL/6 mice was established successfully. The ratio of activated B cells and the expression of TNF-α, IL-1ß, IL-6, TGF-ß1, and B cell activating factor (BAFF) in the 5-day subgroup were the highest in the myocardium, spleen and peripheral blood with the most obvious myocardial inflammatory cell infiltration. The cytokines mRNA expression levels in the 5-day subgroup of the BKO group were decreased compared with those in the WT group (P < 0.05). Among the 2-week subgroups of the Sham, WT and BKO groups, the the LVEDd and LVESd of the BKO group were lower than those of the WT group (P < 0.05), and the left ventricular ejection fraction was higher than that of the WT group (P < 0.05). CONCLUSION: Activated B cells participate in the sustained state of myocardial inflammation and immune system activation after AMI, and may affect the metabolism of myocardial collagen after AMI by secreting cytokines. Moreover, B cells promote the expression of myocardial collagen Type I and Type III and damage the left ventricular ejection function.

MicroRNA-21 and -146b are involved in the pathogenesis of murine viral myocarditis by regulating TH-17 differentiation.

Viral myocarditis (VMC) is a common cardiovascular disease, and microRNAs (miRNAs) have been postulated to be involved in its pathology. Using microarrays, we observed that miRNA-21 and -146b were upregulated in a murine model of VMC. We also found that miRNA-451 was downregulated. In vivo silencing of miRNA-21 and -146b resulted in less-severe VMC. Overexpression of miRNA-451 did not ameliorate the severity of VMC. Further work revealed that inhibition of miRNA-21 and -146b decreased the expression levels of Th17 and RORγt . Overexpression of miRNA-451 had no effect on IL-17 and RORγt expression. Inhibition of miRNA-21 and -146b might ameliorate myocardium inflammation by mediating downregulation of RORγt expression, indicating that these miRNAs are involved in the pathogenesis of murine VMC.

Increased expressions of IL-22 and Th22 cells in the coxsackievirus B3-Induced mice acute viral myocarditis.

BACKGROUND: Recently, a new subset of T helper (Th) cell that predominantly secret cytokine interleukin-22 (IL-22) is identified, termed Th22 cells. The Th22 subset has been demonstrated to be involved in immunity and tissue inflammation. However, the existence of Th22 cells and role of IL-22 in acute viral myocarditis (AVMC) remain unknown. METHODS: BALB/c mice were intraperitoneally (i.p) infected with CVB3 for establishing AVMC models. Control mice were treated with phosphate-buffered saline (PBS) i.p. On day 14 post injection, frequencies of splenic Th22 cells were determined, productions of IL-22 and expressions of IL-22R (IL-22 receptor) were measured. To further investigate the effects of IL-22, AVMC mice treated with Anti-IL-22 neutralizing antibody were explored. The severity of AVMC were monitored; the frequencies of Th22 cells, the expressions of IL-22 and IL-22R were investigated; in addition to IFN-γ, inflammatory cytokines IL-17, TNF-α, IL-6 as well as IL-1ß, were evaluated. Cardiac viral replication were detected. RESULTS: Compared with control group, significant elevations of circulating Th22 cells and IL-22, cardiac protein and mRNA of IL-22, and IL-22R1 were demonstrated in AVMC group. Treatment of AVMC mice with Anti-IL-22 Ab exacerbated the severity of viral myocarditis, verified by lower survival rate, higher HW/BW ratios and cardiac pathological scores. Anti-IL-22 Ab decreased the frequencies of Th22 cells and the levels of IL-22, and increased the expressions of cardiac IL-22R1. Up-regulations of IL-17, IL-6 and TNF-α, down-regulations of IFN-γ proteins and gene expressions in the plasma and myocardium, were observed in Anti-IL-22 Ab group. Furthermore, neutralization of IL-22 significantly promoted cardiac viral replication. CONCLUSIONS: Our data indicate that the increased frequencies of IL-22-producing Th22 cells may play an important role in the pathogenesis of CVB3-induced mice AVMC, IL-22 may act as an myocardium-protective cytokine via the IL-22-IL-22R pathway, and suggest that targeting the Th22 cell and IL-22-IL-22R pathway could provide new therapeutic modalities for the treatment of CVB3-induced AVMC.

Expression of IL-23/Th17 pathway in a murine model of Coxsackie virus B3-induced viral myocarditis.

BACKGROUND: The IL-23/Th17 pathway is implicated in the pathogenesis of a number of chronic inflammatory and autoimmune diseases. Whether it regulates the viral myocarditis (VMC) is unknown. RESULTS: To examine the pathogenesis role of IL-23/Th17 axis in VMC, we used male BALB/c mice to induced VMC by Coxsackie virus B3 (CVB3) peritoneal injection. IL-23, IL-17, and signal transducer and activator of transcription 3 (STAT3) mRNA in the myocardium of VMC mice were assessed by semi-quantitative RT-PCR. IL-23 and IL-17 protein from blood serum were evaluated by ELISA. Phosphorylated-STAT3 (p-STAT3) protein expression in the myocardium was evaluated by immunohistochemical staining. Flow cytometric analysis was used to evaluate the frequencies of Th17 subsets. Isolated CD4+ T cells from VMC mice were cultured with recombinant IL-23(rIL-23) in vitro. In addition, a STAT3-specific inhibitor (S3I-201) was used to test whether regulation of STAT3 could be partly responsible for Th17 diminution. Results showed that expression of IL-23, IL-17, STAT3 mRNA and protein increased in VMC mice. When purified CD4+ T cells derived from VMC mice were cultured in vitro with rIL-23, the frequency of Th17 cells was dramatically increased, accompanied by significantly enhanced production of IL-17 in the supernatants of cultured CD4+ T cells. S3I-201 significantly restrained Th17 cell proliferation. CONCLUSIONS: The IL-23/Th17 pathway axis is strongly expressed in murine VMC, identifying a novel pathway of potential significance in viral myocarditis.

[Alteration of interleukin-17/interferon-γ double positive cells in mice with Coxsackie virus induced myocarditis].

OBJECTIVE: To observe the alteration of interleukin-17 and interferon-γ double positive cells (IL-17(+)/IFN-γ(+) cells) in mice with coxsackie virus B3 (CVB3) induced acute viral myocarditis (VMC). METHODS: VMC was induced in male Balb/c mice by peritoneal injection of CVB3. Control mice received PBS injection. At 0, 1, 2, 3, 4 and 6 weeks after injection, pathological scores were determined on hematoxylin-eosin stained heart sections and flow cytometric analysis was performed to evaluate the percent of IL-17(+)/IFN-γ(+) cells among CD4(+) T cells. RESULTS: Compared to control mice, the pathological scores of VMC mice were higher on CVB3 infection week 1 (1.8 ± 0.5), peaked on week 2 (2.8 ± 0.5) and declined thereafter. However, the proportion of IL-17(+)/IFN-γ(+) cells remained steadily at a low level throughout the observation period and was similar between VMC and control mice. CONCLUSIONS: Our data shows that IL-17(+)/IFN-γ(+) cells might not be involved in the inflammation process of CVB3 induced VMC mice model.

Effect and safety of antithrombotic therapies for secondary prevention after acute coronary syndrome: a network meta-analysis.

BACKGROUND: Dual antiplatelet therapy is a standard protocol for secondary prevention after acute coronary syndrome, but despite a variety of new dual antithrombotic strategies, there is a dearth of studies evaluating the effects and safety of some popular therapies. This study used a network meta-analysis to compare the efficacy and safety of all available antithrombotic therapies. METHODS: PubMed, MEDLINE, and Cochrane library databases were searched for randomized controlled trials, published up to July 1, 2017, that evaluated the efficacy of antithrombotic therapy in acute coronary syndrome treatment. The primary endpoints were clinically significant bleeding and major bleeding and secondary endpoints were major cardiovascular events, all-cause deaths, cardiac deaths, and myocardial infarction. RESULTS: Compared with treatment with aspirin + new P2Y12 inhibitor, treatment with aspirin + new P2Y12 inhibitor converted to clopidogrel clinically reduced the risk of major cardiovascular events or significant bleeding (OR: 0.30, 95% credibility interval: 0.12-0.75). Both myocardial infarction risk (OR: 0.82, 95% credibility interval: 0.62-1.09) and major bleeding risk (OR: 0.18, 95% credibility interval: 0.01-1.68) were not significantly different between treatment regimens. There were no significant differences in major cardiovascular events, all-cause deaths, cardiac deaths, myocardial infarction, clinically significant bleeding, and major bleeding risk with rivaroxaban + new P2Y12 inhibitor therapy when compared with aspirin + new P2Y12 inhibitor. Compared with aspirin + clopidogrel, the conversion therapy further reduced the risk of myocardial infarction (OR: 1.81, 95%, credibility interval: 1.01-1.34) without an increased clinical risk of significant bleeding (OR: 0.41, 95%, credibility interval: 0.15-1.07). Treatment with aspirin + new P2Y12 inhibitors reduced all-cause deaths (OR: 0.91, 95% credibility interval: 0.84-0.98) and cardiac death risk (OR: 0.86, 95% credibility interval: 0.79-0.93). CONCLUSION: We concluded the following from our study: 1) an aspirin + new P2Y12 inhibitor/ clopidogrel conversion treatment strategy was not inferior to aspirin + new P2Y12 inhibitor; 2) compared with aspirin + clopidogrel, the conversion strategy may further reduce the risk of myocardial infarction without increasing the risk of bleeding; and 3) compared with aspirin + clopidogrel, treatment with aspirin + new P2Y12 inhibitors may result in reduced risk of death.