Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice

Acute myocardial infarction is a common cardiovascular disease with high mortality. Myocardial reperfusion injury can counteract the beneficial effects of ...

Huazhong University of Science and Technology

Although the etiology of Alzheimer's disease (AD) is not fully understood, multiple lines of evidence suggests the importance of amyloid-β (Aβ) in the initiation/progression of the disease. Aβ has been shown to induce neuronal apoptosis via the sphingomyelin/ceramide pathway. This study was designed to elucidate whether the sphingosine kinase-1 (SPK1), a critical regulator of the ceramide/sphingosine 1-phosphate rheostat, plays a pivotal role in the regulation of death and survival of differentiated neuro-2a cells in response to beta-amyloid peptide fragment 25-35 (Aβ25-35). These results show that the expression of SPK1 was markedly decreased in Aβ25-35-induced neurotoxicity, as evidenced by the decreased cell viability and the increased apoptotic rate. Overexpression of SPK1 significantly attenuated Aβ25-35-induced neurotoxicity, whereas silencing the expression of SPK1 exacerbated it. Moreover, overexpression of SPK1 can significantly attenuate Aβ25-35-induced upregulation of Bax and rehabilitate the level of Bcl-2; concomitantly, it can ameliorate mitochondrial ultrastructure. These studies demonstrate that overexpression of SPK1 may moderate Aβ25-35-induced neurotoxicity by regulating the Bcl-2/Bax ratio and improving mitochondrial ultrastructure. Based on these findings, SPK1 is a potential therapeutic target for AD.

Sphingosine kinase-1 protects differentiated N2a cells against beta-amyloid25-35-induced neurotoxicity via the mitochondrial pathway.

Recently, interleukin (IL)-9 was found to be involved in the pathogenesis of many inflammatory diseases. Here, we tested whether IL-9 was related to atherosclerosis and investigated the underlying mechanisms.

IL-9 aggravates the development of atherosclerosis in ApoE-/- mice.

CD4 T cells are abnormally activated in patients with dilated cardiomyopathy (DCM) and might be associated with the immunopathogenesis of the disease. However, the underlying mechanisms of CD4 T cell activation remain largely undefined. Our aim was to investigate whether the dysregulation of microRNAs (miRNAs) was associated with CD4 T cell activation in DCM. CD4 T cells from DCM patients showed increased expression levels of CD25 and CD69 and enhanced proliferation in response to anti-CD3/28, indicating an activated state. miRNA profiling analysis of magnetically sorted CD4 T cells revealed a distinct pattern of miRNA expression in CD4 T cells from DCM patients compared with controls. The level of miRNA-451a (miR-451a) was significantly decreased in the CD4 T cells of DCM patients compared with that of the controls. The transfection of T cells with an miR-451a mimic inhibited their activation and proliferation, whereas an miR-451a inhibitor produced the opposite effects. Myc was directly inhibited by miR-451a via interaction with its 3'-UTR, thus identifying it as an miR-451a target in T cells. The knockdown of Myc suppressed the activation and proliferation of T cells, and the expression of Myc was significantly up-regulated at the mRNA level in CD4 T cells from patients with DCM. A strong inverse correlation was observed between the Myc mRNA expression and miR-451a transcription level. Our data suggest that the down-regulation of miR-451a contributes to the activation and proliferation of CD4 T cells by targeting the transcription factor Myc in DCM patients and may contribute to the immunopathogenesis of DCM.

Down-regulation of microRNA-451a facilitates the activation and proliferation of CD4 T cells by targeting Myc in patients with dilated cardiomyopathy.

The immune system plays an important role in driving the acute inflammatory response following myocardial ischaemia/reperfusion injury (MIRI). IL-21 is a pleiotropic cytokine with multiple immunomodulatory effects, but its role in MIRI is not known.

IL-21 promotes myocardial ischaemia/reperfusion injury through the modulation of neutrophil infiltration.

Objective- Inflammation occurs during the progression of abdominal aortic aneurysm (AAA). IL (interleukin)-33 is a pleiotropic cytokine with multiple immunomodulatory effects, yet its role in AAA remains unknown. Approach and Results- Immunoblot, immunohistochemistry, and immunofluorescent staining revealed increased IL-33 expression in adventitia fibroblasts from mouse AAA lesions. Daily intraperitoneal administration of recombinant IL-33 or transgenic IL-33 expression ameliorated periaorta CaPO injury- and aortic elastase exposure-induced AAA in mice, as demonstrated by blunted aortic expansion, reduced aortic wall elastica fragmentation, enhanced AAA lesion collagen deposition, attenuated T-cell and macrophage infiltration, reduced inflammatory cytokine production, skewed M2 macrophage polarization, and reduced lesion MMP (matrix metalloproteinase) expression and cell apoptosis. Flow cytometry analysis, immunostaining, and immunoblot analysis showed that exogenous IL-33 increased CD4Foxp3 regulatory T cells in spleens, blood, and aortas in periaorta CaPO-treated mice. Yet, ST2 deficiency muted these IL-33 activities. Regulatory T cells from IL-33-treated mice also showed significantly stronger activities in suppressing smooth muscle cell inflammatory cytokine and chemokine expression, macrophage MMP expression, and in increasing M2 macrophage polarization than those from vehicle-treated mice. In contrast, IL-33 failed to prevent AAA and lost its beneficial activities in CaPO-treated mice after selective depletion of regulatory T cells. Conclusions- Together, this study established a role of IL-33 in protecting mice from AAA formation by enhancing ST2-dependent aortic and systemic regulatory T-cell expansion and their immunosuppressive activities.

IL (Interleukin)-33 Suppresses Abdominal Aortic Aneurysm by Enhancing Regulatory T-Cell Expansion and Activity.

Myocardial ischemia-reperfusion injury (MIRI) is common clinical complication, which represents significant challenge in the treatment of acute myocardial infarction (AMI) diseases. Interleukin 35 (IL-35) exhibits anti-inflammatory properties via the engagement of the gp130, IL-12Rβ2 and IL-27Rα receptors. However, whether IL-35 plays a beneficial role in the treatment of MIRI and potential underling mechanism are unclear. We showed that IL-35 conferred protection from MIRI as demonstrated by reduced infarct size and cardiac troponin T, improved cardiac function and decreased cardiomyocyte apoptosis in a mouse model. Despite activation of both STAT3 and STAT5 phosphorylation in the heart by IL-35, signal transducers and activators of transcription 3 (STAT3) was essential for mediating the IL-35-mediated protective effect on MIRI using cardiomyocyte-specific STAT3 deficient mice. Furthermore, gp130 was required for the STAT3 activation and cardio-protection induced by IL-35. Interestingly, IL-35 induced gp130 homodimer and gp130/IL-12Rβ2 heterodimers in cardiomyocyte. Our results indicate that IL-35 can execute a protective role against MIRI through a novel signaling pathway, IL-35-gp130-STAT3 pathway, in cardiomyocytes, which may be beneficial for the development of novel and effective therapeutic approaches to treat the MIRI.

Interleukin 35 ameliorates myocardial ischemia-reperfusion injury by activating the gp130-STAT3 axis.

Regulatory T cells (Tregs), traditionally recognized as potent suppressors of immune response, are increasingly attracting attention because of a second major function: residing in parenchymal tissues and maintaining local homeostasis. However, the existence, unique phenotype, and function of so-called tissue Tregs in the heart remain unclear.

A Unique Population of Regulatory T Cells in Heart Potentiates Cardiac Protection From Myocardial Infarction.

Fibrotic scarring is tightly linked to the development of heart failure in patients with post-myocardial infarction (MI). Atypical chemokine receptor 4 (ACKR4) can eliminate chemokines, such as C-C chemokine ligand 21 (CCL21), which is independently associated with heart failure mortality. However, the role of ACKR4 in the heart during MI is unrevealed. This study aimed to determine whether ACKR4 modulates cardiac remodeling following MI and to illuminate the potential molecular mechanisms. The expression of ACKR4 was upregulated in the border/infarct area, and ACKR4 was predominantly expressed in cardiac fibroblasts (CFs). Knockout of ACKR4 protected against adverse ventricular remodeling in mice post-MI. These protective effects of ACKR4 deficiency were independent of dendritic cell immune response but could be attributed to downregulated CF-derived IL-6, affecting CF proliferation and endothelial cell (EC) functions, which consequently inhibited cardiac fibrosis. ACKR4 promoted IL-6 generation and proliferation of CFs. Besides, ACKR4 induced endothelial-to-mesenchymal transition (EndMT) in ECs through IL-6 paracrine effect. The p38 MAPK/NF-κB signaling pathway was involved in ACKR4 facilitated IL-6 generation. Moreover, ACKR4 overexpression in vivo via AAV9 carrying a periostin promoter aggravated heart functional impairment post-MI, which was abolished by IL-6 neutralizing antibody. Therefore, our study established a novel link between ACKR4 and IL-6 post-MI, indicating that ACKR4 may be a novel therapeutic target to ameliorate cardiac remodeling.

Inhibition of fibroblast IL-6 production by ACKR4 deletion alleviates cardiac remodeling after myocardial infarction.

Overactivated inflammatory responses contribute to adverse ventricular remodeling after myocardial infarction (MI). Regulatory B cells (Bregs) are a newly discovered subset of B cells with immunomodulatory roles in many immune and inflammation-related diseases. Our study aims to determine whether the expansion of Bregs exerts a beneficial effect on ventricular remodeling and explore the mechanisms involved. Here, we showed that adoptive transfer of Bregs ameliorated ventricular remodeling in a murine MI model, as demonstrated by improved cardiac function, decreased scar size and attenuated interstitial fibrosis without changing the survival rate. Reduced Ly6C monocyte infiltration was found in the hearts of the Breg-transferred mice, while the infiltration of Ly6C monocytes was not affected. In addition, the replenishment of Bregs had no effect on the myocardial accumulation of T cells or neutrophils. Mechanistically, Bregs reduced the expression of C-C motif chemokine receptor 2 (CCR2) in monocytes, which inhibited proinflammatory monocyte recruitment to the heart from the peripheral blood and mobilization from the bone marrow. Breg-mediated protection against MI was abrogated by treatment with an interleukin 10 (IL-10) antibody. Finally, IL-10 neutralization reversed the effect of Bregs on monocyte migration and CCR2 expression. The present study suggests a therapeutic value of Bregs in limiting ventricular remodeling after MI through decreasing CCR2-mediated monocyte recruitment and mobilization.

Bingjie Lv

Department of Cardiology,
Union Hospital,
Tongji Medical College,
Department of Cardiology, Union Hospital, Tongji Medical College

Huazhong University of Science and Technology

Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice

Bingjie Lv

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Cardiology,Union Hospital,Tongji Medical College,Department of Cardiology, Union Hospital, Tongji Medical College

Huazhong University of Science and Technology

Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice

Department of Cardiology,
Union Hospital,
Tongji Medical College,
Department of Cardiology, Union Hospital, Tongji Medical College