Role of CC-chemokine receptor 5 on myocardial ischemia-reperfusion injury in rats

Monocyte chemokine receptors as therapeutic targets in cardiovascular diseases

Chemokine receptors are fundamental in many processes related to cardiovascular diseases, such as monocyte migration to vessel walls, cell adhesion, and angiogenesis, among others. Even though many experimental studies have shown the utility of blocking these receptors or their ligands in the treatment of atherosclerosis, the findings in clinical research are still poor. Thus, in the current review we aimed to describe some promising results concerning the blockade of chemokine receptors as therapeutic targets in the treatment of cardiovascular diseases and also to discuss some challenges that need to be overcome before using these strategies in clinical practice.

Association between high immune activity and worse prognosis in uveal melanoma and low-grade glioma in TCGA transcriptomic data

BACKGROUND

Immune status in the tumor microenvironment is an important determinant of cancer progression and patient prognosis. Although a higher immune activity is often associated with a better prognosis, this trend is not absolute and differs across cancer types. We aimed to give insights into why some cancers do not show better survival despite higher immunity by assessing the relationship between different biological factors, including cytotoxicity, and patient prognosis in various cancer types using RNA-seq data collected by The Cancer Genome Atlas.

RESULTS

Results showed that a higher immune activity was associated with worse overall survival in patients with uveal melanoma and low-grade glioma, which are cancers of immune-privileged sites. In these cancers, epithelial or endothelial mesenchymal transition and inflammatory state as well as immune activation had a notable negative correlation with patient survival. Further analysis using additional single-cell data of uveal melanoma and glioma revealed that epithelial or endothelial mesenchymal transition was mainly induced in retinal pigment cells or endothelial cells that comprise the blood-retinal and blood-brain barriers, which are unique structures of the eye and central nervous system, respectively. Inflammation was mainly promoted by macrophages, and their infiltration increased significantly in response to immune activation. Furthermore, we found the expression of inflammatory chemokines, particularly CCL5, was strongly correlated with immune activity and associated with poor survival, particularly in these cancers, suggesting that these inflammatory mediators are potential molecular targets for therapeutics.

CONCLUSIONS

In uveal melanoma and low-grade glioma, inflammation from macrophages and epithelial or endothelial mesenchymal transition are particularly associated with a poor prognosis. This implies that they loosen the structures of the blood barrier and impair homeostasis and further recruit immune cells, which could result in a feedback loop of additional inflammatory effects leading to runaway conditions.

NR4A2 alleviates cardiomyocyte loss and myocardial injury in rats by transcriptionally suppressing CCR5 and inducing M2 polarization of macrophages

BACKGROUND

CC chemokine receptor 5 (CCR5) has been demonstrated to be correlated to activation of pro-inflammatory immune cells and tissue injury. This study focused on the role of CCR5 in myocardial injury in rats with diabetic cardiomyopathy (DCM) and the mechanism of action.

METHODS

A rat model of DCM was induced by streptozotocin (STZ). CCR5 was knocked down in rats to determine its role in myocardial injury and immune cell infiltration. The upstream regulators of CCR5 were bioinformatically predicted and the binding between nuclear receptor subfamily 4 group A member 2 (NR4A2) and CCR5 was validated. The portion of M1 and M2 macrophages in tissues was determined by flow cytometry or double-labeling immunofluorescence. Rat bone marrow mononuclear cells (BMMCs) were treated with granulocyte/macrophage colony stimulating factor (GM-CSF/M-CSF) and co-cultured with H9C2 cells for in vitro experiments.

RESULTS

STZ-treated rats had impaired cardiac function and increased levels of creatine kinase-MB, cardiac troponin I and lactate dehydrogenase. CCR5 inhibition significantly alleviated myocardial injury in rats and reduced the portion of M1 macrophages in rat cardiac tissues. NR4A2, which could suppress CCR5 transcription, was poorly expressed in rats with DCM. NR4A2 overexpression played a similar myocardium-protective role in rats. In vitro, overexpression of NR4A2 induced M2 polarization of macrophages, which protected the co-cultured H9C2 cells from high glucose-induced damage, but the protective role was blocked after CCR5 overexpression.

CONCLUSION

This study demonstrated that NR4A2 suppresses CCR5 expression and promotes M2 polarization of macrophages to alleviate cardiomyocyte loss and myocardial injury.

Chemokines in Myocardial Infarction

In the infarcted myocardium, cardiomyocyte necrosis triggers an intense inflammatory reaction that not only is critical for cardiac repair, but also contributes to adverse remodeling and to the pathogenesis of heart failure. Both CC and CXC chemokines are markedly induced in the infarcted heart, bind to endothelial glycosaminoglycans, and regulate leukocyte trafficking and function. ELR+ CXC chemokines (such as CXCL8) control neutrophil infiltration, whereas CC chemokines (such as CCL2) mediate recruitment of mononuclear cells. Moreover, some members of the chemokine family (such as CXCL10 and CXCL12) may mediate leukocyte-independent actions, directly modulating fibroblast and vascular cell function. This review manuscript discusses our understanding of the role of the chemokines in regulation of injury, repair, and remodeling following myocardial infarction. Although several chemokines may be promising therapeutic targets in patients with myocardial infarction, clinical implementation of chemokine-based therapeutics is hampered by the broad effects of the chemokines in both injury and repair.

Chemokine Receptor 5, a Double-Edged Sword in Metabolic Syndrome and Cardiovascular Disease

The key characteristic of cardiovascular disease (CVD) is endothelial dysfunction, which is likely the consequence of inflammation. It is well demonstrated that chemokines and their receptors play a crucial role in regulating inflammatory responses, and recently, much attention has been paid to chemokine receptor 5 (CCR5) and its ligands. For example, CCR5 aggravates the inflammatory response in adipose tissue by regulating macrophage recruitment and M1/M2 phenotype switch, thus causing insulin resistance and obesity. Inhibition of CCR5 expression reduces the aggregation of pro-atherogenic cytokines to the site of arterial injury. However, targeting CCR5 is not always effective, and emerging evidence has shown that CCR5 facilitates progenitor cell recruitment and promotes vascular endothelial cell repair. In this paper, we provide recent insights into the role of CCR5 and its ligands in metabolic syndrome as related to cardiovascular disease and the opportunities and roadblocks in targeting CCR5 and its ligands.

The cystathionine γ-lyase/hydrogen sulfide pathway mediates the trimetazidine-induced protection of H9c2 cells against hypoxia/reoxygenation-induced apoptosis and oxidative stress

Objective:

Trimetazidine is a piperazine-derived metabolic agent. It exerts cardioprotective effects against myocardial ischemia/reperfusion (I/R) injury. In addition, studies confirm that the cystathionine γ-lyase (CSE)/hydrogen sulfide (H₂S) pathway serves a beneficent role in attenuating myocardial I/R injury. However, the underlying role of the CSE/H₂S pathway in the trimetazidine-induced protection against myocardial I/R injury remains elusive. Therefore, this study investigated whether trimetazidine ameliorates hypoxia/reoxygenation (H/R)-induced H9c2 cardiomyocyte injuries in an in vitro cell model of myocardial I/R injury, by enhancing the CSE/H₂S pathway.

Methods:

The H9c2 cell viability was determined with a cell counting Kit-8.

Results:

Trimetazidine significantly increased the cell viability and decreased lactate dehydrogenase (LDH) release in H/R-treated H9c2 cells. Additionally, trimetazidine increased the H₂S levels and the CSE mRNA and protein levels, promoting the CSE/H₂S pathway under H/R conditions. The inhibition of the CSE/H₂S pathway, induced by transfection with specific siRNA against human CSE (si-CSE), eliminated the trimetazidine-induced upregulation of cell viability, downregulation of LDH release, increase of caspase-3 activity and apoptosis regulator BAX expression, and the decrease of apoptosis regulator Bcl-2 expression, which suggests involvement of the CSE/H₂S pathway in trimetazidine-induced cardioprotection. Furthermore, trimetazidine mitigated the H/R-induced increase in reactive oxygen species production and NADPH oxidase 2 expression, and decrease in superoxide dismutase activity and glutathione level, in H9c2 cells. These effects were also reversed by si-CSE.

Conclusion:

This study revealed that the CSE/H₂S pathway mediates the trimetazidine-induced protection of H9c2 cardiomyocytes against H/R-induced damage by inhibiting apoptosis and oxidative stress.

Total Flavonoids from Carya cathayensis Sarg. Leaves Alleviate H9c2 Cells Hypoxia/Reoxygenation Injury via Effects on miR-21 Expression, PTEN/Akt, and the Bcl-2/Bax Pathway

This study aimed to investigate whether the total flavonoids (TFs) from Carya cathayensis Sarg. leaves alleviate hypoxia/reoxygenation (H/R) injury in H9c2 cardiomyocytes and to explore potential mechanisms. H9c2 cells pretreated with TFs for 24h were exposed to H/R treatment. The results indicated that TFs significantly alleviate H/R injury, which include inhibiting apoptosis and enhancing antioxidant capacity. The protective effects of TFs resulted in higher expression of miR-21 in H/R-induced H9c2 cells than that of controls, which in turn upregulated Akt signaling activity via suppressing the expression of PTEN together with decreasing the ratio of Bax/Bcl-2, caspase3, and cleaved-caspase3 expression in H/R-induced H9c2 cells. Conversely, blocking miR-21 expression with miR-21 inhibitor effectively suppressed the protective effects of TFs against H/R-induced injury. Our study suggests that TFs can decrease cell apoptosis, which may be mediated by altering the expression of miR-21, PTEN/Akt, and Bcl/Bax.

Trimetazidine protects against cardiac ischemia/reperfusion injury via effects on cardiac miRNA‑21 expression, Akt and the Bcl‑2/Bax pathway

Trimetazidine is a piperazine-derived metabolic agent, which exerts cell protective effects and has been reported to be efficient in the treatment of chronic stable angina pectoris. In addition, it has been shown to exert protection against acute myocardial infarction. The present study aimed to investigate whether trimetazidine protects against cardiac ischemia/reperfusion (I/R) injury, and to determine whether its curative effects are associated with microRNA (miRNA)-21 expression, Akt, and the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) pathway. Cardiac I/R injury was induced by ligating the left anterior descending coronary artery in adult rats. Subsequently, cardiac function was evaluated, and the expression levels of miRNA-21, Bcl-2, Bax and phosphorylated-Akt were detected using quantitative polymerase chain reaction and western blotting. The results indicated that trimetazidine was able to significantly protect cardiac function and reduce infarct size in rats following cardiac I/R injury. Furthermore, trimetazidine significantly promoted miRNA-21 expression and phosphorylated-Akt protein expression, and reduced the Bcl-2/Bax ratio in rats following cardiac I/R injury. Knockdown of miRNA-21 using anti-miR-21 plasmids was able to reverse the protective effects of trimetazidine against cardiac I/R injury. These results indicated that miRNA-21 serves a protective role in cardiac I/R injury via Akt and the Bcl-2/Bax pathway. In addition, trimetazidine exerts protective effects against cardiac I/R injury through cardiac miRNA-21 expression, Akt, and the Bcl-2/Bax pathway. Therefore, the present study provided evidence regarding the protective effects of miRNA-21 on cardiac I/R injury following treatment with trimetazidine in vivo.

Fatigue-induced Orosomucoid 1 Acts on C-C Chemokine Receptor Type 5 to Enhance Muscle Endurance

Understanding and managing fatigue is a significant challenge in clinic and society. In attempting to explore how the body responds to and regulates fatigue, we found in rodent fatigue models that orosomucoid 1 (ORM1) was significantly increased in multiple tissues, including blood and muscle. Interestingly, administration of exogenous ORM1 increased muscle glycogen and enhanced muscle endurance, whereas ORM1 deficiency resulted in a significant decrease of muscle endurance both in vivo and in vitro, which could largely be restored by exogenous ORM1. Further studies demonstrated that ORM1 can bind to C-C chemokine receptor type 5 (CCR5) on muscle cells and deletion of the receptor abolished the effect of ORM1. Thus, fatigue upregulates the level of ORM1, which in turn functions as an anti-fatigue protein to enhance muscle endurance via the CCR5 pathway. Modulation of the level of ORM1 and CCR5 signaling could be a novel strategy for the management of fatigue.