RP105 alleviates myocardial ischemia reperfusion injury via inhibiting TLR4/TRIF signaling pathways

Link between sterile inflammation and cardiovascular diseases: Focus on cGAS-STING pathway in the pathogenesis and therapeutic prospect

Sterile inflammation characterized by unresolved chronic inflammation is well established to promote the progression of multiple autoimmune diseases, metabolic disorders, neurodegenerative diseases, and cardiovascular diseases, collectively termed as sterile inflammatory diseases. In recent years, substantial evidence has revealed that the inflammatory response is closely related to cardiovascular diseases. Cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway which is activated by cytoplasmic DNA promotes the activation of interferon regulatory factor 3 (IRF3) or nuclear factor-κB (NF-κB), thus leading to upregulation of the levels of inflammatory factors and interferons (IFNs). Therefore, studying the role of inflammation caused by cGAS-STING pathway in cardiovascular diseases could provide a new therapeutic target for cardiovascular diseases. This review focuses on that cGAS-STING-mediated inflammatory response in the progression of cardiovascular diseases and the prospects of cGAS or STING inhibitors for treatment of cardiovascular diseases.

The Intriguing Role of TLR Accessory Molecules in Cardiovascular Health and Disease

Activation of Toll like receptors (TLR) plays an important role in cardiovascular disease development, progression and outcomes. Complex TLR mediated signaling affects vascular and cardiac function including tissue remodeling and repair. Being central components of both innate and adaptive arms of the immune system, TLRs interact as pattern recognition receptors with a series of exogenous ligands and endogenous molecules or so-called danger associated molecular patterns (DAMPs) that are released upon tissue injury and cellular stress. Besides immune cells, a number of structural cells within the cardiovascular system, including endothelial cells, smooth muscle cells, fibroblasts and cardiac myocytes express TLRs and are able to release or sense DAMPs. Local activation of TLR-mediated signaling cascade induces cardiovascular tissue repair but in a presence of constant stimuli can overshoot and cause chronic inflammation and tissue damage. TLR accessory molecules are essential in guiding and dampening these responses toward an adequate reaction. Furthermore, accessory molecules assure specific and exclusive TLR-mediated signal transduction for distinct cells and pathways involved in the pathogenesis of cardiovascular diseases. Although much has been learned about TLRs activation in cardiovascular remodeling, the exact role of TLR accessory molecules is not entirely understood. Deeper understanding of the role of TLR accessory molecules in cardiovascular system may open therapeutic avenues aiming at manipulation of inflammatory response in cardiovascular disease. The present review outlines accessory molecules for membrane TLRs that are involved in cardiovascular disease progression. We first summarize the up-to-date knowledge on TLR signaling focusing on membrane TLRs and their ligands that play a key role in cardiovascular system. We then survey the current evidence of the contribution of TLRs accessory molecules in vascular and cardiac remodeling including myocardial infarction, heart failure, stroke, atherosclerosis, vein graft disease and arterio-venous fistula failure.

PHLDA3 inhibition attenuates endoplasmic reticulum stress-induced apoptosis in myocardial hypoxia/reoxygenation injury by activating the PI3K/AKT signaling pathway

Endoplasmic reticulum stress (ERS)-induced apoptosis serves a crucial role in the pathogenesis of myocardial ischemia/reperfusion injury (MIRI). Previous studies have confirmed that pleckstrin homology-like domain family A member 3 (PHLDA3) is an important mediator in ERS-associated apoptosis. The aim of the current study focused on whether PHLDA3 served protective effects on hypoxia/reoxygenation (H/R)-injured cardiomyocytes by inhibiting ERS-induced apoptosis. Furthermore, the molecular mechanisms associated with the PI3K/AKT signaling pathway were investigated. Primary neonatal rat cardiomyocytes were isolated and randomized into four groups: i) Control + adenovirus encoding scrambled short hairpin RNA (AdshRNA); ii) control + adenoviral vectors encoding PHLDA3 shRNA (AdshPHLDA3); iii) H/R+ AdshRNA and iv) H/R+AdshPHLDA3. AdshPHLDA3 was used to knock down PHLDA3. An H/R injury model was constructed by treatment with hypoxia for 4 h followed by reoxygenation for 6 h. A PI3K/AKT inhibitor, LY294002, was supplemented in mechanistic studies. Cell viability and LDH/CK releases were detected to evaluate myocardial damage. Flow cytometry assays were used to assess apoptotic response. Western blotting assays were used to detect protein expression. The results demonstrated that H/R induced myocardial damage and increased PHLDA3 expression. ERS-induced apoptosis was significantly increased following H/R injury, as indicated by increased apoptotic rates and ERS-associated protein expression, including those of CHOP, 78 kDa glucose-regulated protein and caspase-12. However, PHLDA3 inhibition following AdshPHLDA3 transfection reversed cell damage and ERS-associated apoptosis on H/R injury. Studies for molecular mechanisms concluded that the apoptosis-inhibition effects and cardioprotective roles of PHLDA3 inhibition were induced partly by the activation of the PI3K/AKT pathway, which was verified by LY294002 treatment. In conclusion, in the process of H/R injury, PHLDA3 inhibition reduced ERS-induced apoptosis and H/R injury by activating the PI3K/AKT pathway. PHLDA3 may be a therapeutic target for the treatment of MIRI.

Study of the Mechanism of Action of Guanxin Shutong Capsules in the Treatment of Coronary Heart Disease Based on Metabolomics

Background: Guan-Xin-Shu-Tong capsule (GXSTC) is a traditional Chinese medicine (TCM) that has been used to treat coronary heart disease (CHD) for many years in China. However, the holistic mechanism of GXSTC against CHD is still unclear. Therefore, the purpose of this paper was to systematically explore the mechanism of action GXSTC in the treatment of CHD rats using a metabolomics strategy.

Methods: A CHD model was induced by ligation of the left anterior descending coronary artery (LAD). In each group, echocardiography was performed; the contents of creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate transaminase (AST) in serum were determined; and the myocardial infarct size was measured. The metabolites in plasma were analyzed by UHPLC-MS/MS-based untargeted metabolomics. Then, multivariate statistical analysis was performed to screen potential biomarkers associated with the GXSTC treatment in the LAD-induced rat CHD model. Finally, the MetaboAnalyst 4.0 platform was used for metabolic pathway enrichment analysis.

Results: GXSTC was able to regulate the contents of CK, LDH and AST; restore impaired cardiac function; and significantly reduce the myocardial infarction area in model rats. Twenty-two biomarkers and nine metabolic pathways of GXSTC in the treatment of CHD were identified through UHPLC-MS/MS-based untargeted metabolomics analysis.

Conclusion: GXSTC regulates metabolic disorders of endogenous components in LAD-induced CHD rats. The anti-CHD mechanism of GXSTC is mainly related to the regulation of amino acid, lipid and hormonal metabolism. This study provides an overall view of the mechanism underlying the action of GXSTC against CHD.

Key Player in Cardiac Hypertrophy, Emphasizing the Role of Toll-Like Receptor 4

Toll-like receptor 4 (TLR4), a key pattern recognition receptor, initiates the innate immune response and leads to chronic and acute inflammation. In the past decades, accumulating evidence has implicated TLR4-mediated inflammatory response in regulation of myocardium hypertrophic remodeling, indicating that regulation of the TLR4 signaling pathway may be an effective strategy for managing cardiac hypertrophy's pathophysiology. Given TLR4's significance, it is imperative to review the molecular mechanisms and roles underlying TLR4 signaling in cardiac hypertrophy. Here, we comprehensively review the current knowledge of TLR4-mediated inflammatory response and its interaction ligands and co-receptors, as well as activation of various intracellular signaling. We also describe the associated roles in promoting immune cell infiltration and inflammatory mediator secretion, that ultimately cause cardiac hypertrophy. Finally, we provide examples of some of the most promising drugs and new technologies that have the potential to attenuate TLR4-mediated inflammatory response and prevent or reverse the ominous cardiac hypertrophy outcomes.

Protective Effect of Pravastatin on Myocardial Ischemia Reperfusion Injury by Regulation of the miR-93/Nrf2/ARE Signal Pathway

Purpose

This research intended to study the mechanism of pravastatin in myocardial ischemia reperfusion (I/R) injury.

Patients and Methods

Altogether 70 male rats were selected and grouped into Sham operation group (Sham group), ischemia reperfusion group (I/R group), pravastatin pretreatment group (I/R+P group), I/R+miR-93-mimics, I/R+P+miR-93-mimics, I/R+Nrf2 siRNA, and I/R+P+Nrf2 siRNA group. The myocardial function of each group was detected.

Results

Myocardial I/R injury could lead to abnormal myocardial enzyme activity, inflammatory reaction and oxidative stress. However, pravastatin could significantly inhibit the activity of myocardial enzymes, alleviate inflammatory reaction and inhibit oxidative stress reaction, thus playing a protective role. Furthermore, cell experiments showed that pravastatin can alleviate the injury of H9C2 myocardial cells caused by I/R, inhibit the apoptosis of myocardial cells, and lead to a significant reduction in pro-apoptotic genes Bax, caspase-3 and caspase-9 transcription levels, an obvious increase in anti-apoptotic gene Bcl-2, and an increase in cell activity. After I/R induced injury, miR-93 level was significantly up-regulated and Nrf2 level was down-regulated. Over-expression of miR-93 or inhibition of Nrf2 expression would lead to further aggravation of I/R myocardial injury, increase the apoptosis rate of cells and decrease the activity of myocardial cells. Pravastatin administration could inhibit miR-93, activate and promote Nrf2 in myocardial tissue, and promote protein expression of downstream regulatory genes HO-1 and NQO1. In the I/R model, pravastatin was given. Over-expression of miR-93 or silencing Nrf2 could reverse the therapeutic effect of pravastatin on I/R.

Conclusion

Pravastatin acts as a protector on myocardial ischemia reperfusion injury by regulating miR-93/Nrf2/ARE signaling pathway.

RP105 plays a cardioprotective role in myocardial ischemia reperfusion injury by regulating the Toll‑like receptor 2/4 signaling pathways

The revascularization of blood vessels after myocardial infarction can lead to serious myocardial damage. Previous studies showed that radioprotective 105 kDa protein (RP105) is a specific negative regulator of myocardial ischemia reperfusion injury (MIRI). RP105 can modulate the Toll-like receptor (TLR)2/TLR4 signaling pathways. However, the synergistic effect of TLR2/4 regulated by RP105 during MIRI requires further investigation. To determine this effect, a MIRI model was established in rats in the present study. The expression of RP105 was depleted by transfecting RP105-siRNA and then detected using western blotting. Furthermore, the myocardium tissue was stained with the hematoxylin and eosin staining. Knockdown of RP105 promoted the activity of serum myocardial enzymes during MIRI and increased myocardial infarction. The present results indicated that knockdown of RP105 activated the TLR2/4 signaling pathway by modulating the myeloid differentiation primary response 88 and NF-κB signaling pathways. Furthermore, decreased expression of RP105 promoted myocardial cell apoptosis, which induced the damage of myocardial ischemic reperfusion. The present results suggested both TLR2 and TLR4 as key targets of RP105, thus RP105 may be a promising candidate to facilitate the development of novel therapeutic strategies for MIRI.

Gene therapy for cardiovascular diseases in China: basic research

Cardiovascular disease has become a major disease affecting health in the whole world. Gene therapy, delivering foreign normal genes into target cells to repair damages caused by defects and abnormal genes, shows broad prospects in treating different kinds of cardiovascular diseases. China has achieved great progress of basic gene therapy researches and pathogenesis of cardiovascular diseases in recent years. This review will summarize the latest research about gene therapy of proteins, epigenetics, including noncoding RNAs and genome-editing technology in myocardial infarction, cardiac ischemia-reperfusion injury, atherosclerosis, muscle atrophy, and so on in China. We wish to highlight some important findings about the essential roles of basic gene therapy in this field, which might be helpful for searching potential therapeutic targets for cardiovascular disease.

Salvianolic acid B protects against myocardial ischaemia-reperfusion injury in rats via inhibiting high mobility group box 1 protein expression through the PI3K/Akt signalling pathway

Salvianolic acid B (Sal B) has a significant protective effect on myocardial ischaemia-reperfusion (I/R) injury. Therefore, the aims of this study were to determine the effects of Sal B on myocardial ischaemic-reperfusion (I/R) injury in rats and to explore whether its underlying mechanism of cardioprotection occurs through activating the expression of the phosphoinositide 3-kinase/protein, kinase B (PI3K/Akt) and inhibiting the expression of high mobility group protein 1 (HMGB1). Ninety Sprague-Dawley rats were randomized into five groups: group 1 (sham-operated), group 2 (myocardial I/R), group 3 (low dose of Sal B+I/R), group 4 (high dose of Sal B+I/R), and group 5 (high dose of Sal B+I/R+LY294002, which is a specific PI3k inhibitor). All I/R rats received 30 min myocardial ischaemia followed by 24-h reperfusion. Cardiac function, infarct size, myocardial injury marker levels, inflammatory response and cardiomyocyte apoptosis as well as Bcl-2, Bax, P-Akt, HMGB1 and TLR4 expression were measured. In the current study, Sal B significantly ameliorated myocardial I/R injury in a dose-dependent manner, ameliorated cardiac function, reduced myocardial infarction size, decreased myocardial injury marker expression, decreased inflammatory responses, reduced apoptosis, activated PI3K/Akt expression and inhibited HMGB1 expression. However, all effects of Sal B were significantly reversed by LY294002. Overall, the present study indicated that Sal B attenuated myocardial I/R injury by activating PI3K/Akt and inhibiting the release of HMGB1 in rats.

Shuxuening injection protects against myocardial ischemia-reperfusion injury through reducing oxidative stress, inflammation and thrombosis

Background

Shuxuening injection (SXNI) has a good effect on cardiovascular and cerebrovascular diseases. Here, our study aims to investigate whether SXNI have the protective effect on myocardial ischemia-reperfusion injury (MIRI) and elucidate the mechanism of SXNI's cardiac protection.

Methods

In this experiment, the coronary arteries of Sprague-Dawley (SD) rats were ligated for the induction of a MIRI model. TTC staining and haematoxylin-eosin (HE), as well as troponin I (TnI), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK) and CK-MB levels, were used to detect the protective effect of SXNI. In rat cardiac tissue, superoxide dismutase, catalase, glutathione and malondialdehyde (MDA) activities and glucose-regulated protein 78 (GRP78), calreticulin (CRT), CCAAT/enhancer binding protein homologous protein (CHOP) and caspase-12 expression levels were detected. In rat serum, the levels of inflammatory factors, including high-sensitivity C-reactive protein, monocyte chemoattractant protein-1, tumour necrosis factor-α, interleukin-6 (IL-6) and IL-1β, were measured by Elisa. In the rat arterial tissue, Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) expression was measured by western blot. In the rat plasma, ELISA was used to assay the levels of coagulation and plasmin system indicators, including platelet activating factor, endothelin, tissue factor (TF), plasminogen inhibitor, thromboxane B2, plasma fibrinogen.

Results

The results showed that SXNI can reduce the infarct size of myocardial tissue, decrease the myocardial enzyme and TnI levels and decrease the degree of myocardial damage compared with the model group. Additionally, SXNI can increase the activity of antioxidant enzymes, reduce the MDA level and decrease the GRP78, CRT, CHOP and caspase-12 expression levels. SXNI also decreased the levels of inflammatory cytokines in rat serum, lowered the level of procoagulant molecules in plasma and reduced the TLR4/NF-κB expression.

Conclusions

SXNI has protective effect on MIRI mainly by inhibiting oxidative stress and endoplasmic reticulum stress (ERS), thereby regulating TLR4/NF-κB pathway to reduce inflammation, and lowing procoagulant-related factors levels to reduce the risk of thrombosis.

Inhibition of microRNA-141-3p Reduces Hypoxia-Induced Apoptosis in H9c2 Rat Cardiomyocytes by Activating the RP105-Dependent PI3K/AKT Signaling Pathway

BACKGROUND Oxidative stress in myocardial ischemia results in cardiomyocyte apoptosis. The expression of microRNA-141-3p (miR-141-3p) and the 105 kD toll-like receptor protein (TLR), RP105, have been identified in cardiomyocytes in vitro. This study aimed to investigate the effects of hypoxia in H9c2 rat cardiomyoblasts with and without the inhibition of miR-141-3p and to investigate the expression of RP105 and the PI3K/AKT signaling pathway. MATERIAL AND METHODS H9c2 rat cardiomyoblasts were cultured in conditions of hypoxia and treated with a specific miR-141-3p-inhibitor. RP105 short-interfering RNA (siRNA) was constructed, and LY294002 was used to inhibit the PI3KA/AKT pathway. The fluorescent probe, dihydroethidium (DHE), was used to detect reactive oxygen species (ROS). Flow cytometry evaluated ROS and apoptosis. Quantitative real-time polymerase chain reaction (RT-qPCR) and Western blot studied the expression of the PI3K/AKT pathway genes and proteins. Bioinformatics and dual-luciferase reporter assays were used to identify the targets for miR-141-3p. RESULTS A predictive TargetScan algorithm showed that the RP105 gene was a potential target of miR-141-3p. Expression of miR-141-3p was significantly increased in hypoxic H9c2 cells, and inhibition of miR-141-3p increased cell viability and reduced apoptosis. Also, miR-141-3p was shown to target 3'-UTR of RP105. Down-regulation of RP105 associated with hypoxia and its downstream PI3K/AKT pathway were significantly increased following miR-141-3p inhibition. The protective effect of miR-141-3p inhibition in hypoxic H9c2 cells was abolished by the absence of RP105 and inhibition of PI3K/AKT. CONCLUSIONS Inhibition of miR-141-3p reduced hypoxia-induced apoptosis in H9c2 cardiomyocytes in vitro by activating the RP105-dependent PI3K/AKT signaling pathway.

Pathogenesis of Important Virulence Factors of Porphyromonas gingivalis via Toll-Like Receptors

Periodontitis is a common intraoral infection and is inextricably linked to systemic diseases. Recently, the regulation between host immunologic response and periodontal pathogens has become a hotspot to explain the mechanism of periodontitis and related systemic diseases. Since Porphyromonas gingivalis (P. gingivalis) was proved as critical periodontal pathogen above all, researches focusing on the mechanism of its virulence factors have received extensive attention. Studies have shown that in the development of periodontitis, in addition to the direct release of virulent factors by periodontal pathogens to destroy periodontal tissues, over-low or over-high intrinsic immune and inflammatory response mediated by Toll-like receptors (TLRs) can lead to more lasting destruction of periodontal tissues. It is very necessary to sort out how various cytopathic factors of P. gingivalis mediate inflammation and immune responses between the host through TLRs so as to help precisely prevent, diagnose, and treat periodontitis in clinic. This review summarizes the role of three most widely studied pathogenic factors produced by P. gingivalis (lipopolysaccharide, gingipains, pili) and their interactions with TLRs at the cellular and molecular level in the progress of periodontitis.