TRPV2 channel as a possible drug target for the treatment of heart failure

Lower urinary dysfunction as a long-term effect of childhood vincristine treatment, with potential influences by sex and dose

Vincristine (VCR) is one of the most widely used chemotherapy agents in treating pediatric cancer. Nonetheless, it is known to cause dose-dependent neurotoxicity which can impact virtually every organ system. Despite its widespread use, the precise impact of VCR on the lower urinary tract (LUT) remains inadequately elucidated. Our initial clinical and translational investigations suggest a sex-specific influence of childhood VCR exposure on LUT function. Thus, the current study aimed to investigate the late effects of systemic VCR exposure on LUT physiology and the underlying mechanisms, focusing on dosage and male-sex, employing juvenile CD-1 mice as a model. Male mice subjected to VCR exhibited augmented functional bladder capacity accompanied by frequent non-void contractions during awake cystometry, alongside mast cell accumulation within the bladder, compared to the saline-treated control group. Noteworthy functional changes were observed in bladder strips from the VCR group, including decreased nerve-mediated contraction, heightened contractile responses to cholinergic and purinergic agonists, enhanced responsiveness to histamine-primarily via histamine receptor 1 (Hrh1)-and an augmented relaxation effect with compound 48/80 (a mast cell degranulator), relative to the control group. Significant changes in gene expression levels associated with neuroinflammation and nociception were observed in both the bladder and lumbosacral dorsal root ganglia (Ls-DRG) of the VCR group. These findings suggest that VCR exposure during childhood, particularly in males, triggers neuroimmune responses in the bladder and Ls-DRG, amplifying responsiveness to neurotransmitters in the bladder, thereby contributing to LUT dysfunction characterized by a mixed bladder phenotype as a late effect during survivorship.

Tetrandrine downregulates TRPV2 expression to ameliorate myocardial ischemia/reperfusion injury in rats via regulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function

Our previous study has indicated that tetrandrine (TET) can target miR-202-5p to repress the activation of transient receptor potential vanilloid type 2 (TRPV2), eventually ameliorating the progression of myocardial ischemia/reperfusion injury (MI/RI). This study is aimed to further ascertain the detailed mechanisms between TET and TRPV2 in MI/RI pathogenesis. Here, a myocardial I/R injury rat model and a hypoxia-reoxygenation (H/R) model in rat myocardial cell line (H9C2 cells) were established. We reported that pronounced upregulation of TRPV2 was observed in I/R rats and H/R-induced H9C2 cells. Silencing of TRPV2 could improve cardiac function and myocardial injury, reduced infarction size, and promoted cardiomyocyte proliferation in I/R rats. In I/R rats or H/R-induced H9C2 cells, cardiomyocyte apoptosis was inhibited by knocking-down TRPV2. Meanwhile, the silenced TRPV2 or TET treatment ameliorated the damaged mitochondrial structure, mitigated ROS generation, restored the impaired ΔΨM, inhibited mPTP opening and alleviated Ca2+ overload in H/R-induced H9C2 cells. The results obtained from the overexpression of TRPV2 were contrary to those depicted above. Moreover, TET could downregulate TRPV2 expression, while the overexpression of TRPV2 could reverse the above protective effects of TET in H/R-induced H9C2 cells. The results indicated that TET may function as a TRPV2 blocking agent, thereby attenuating the progression of MI/RI through modulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function. These findings offer a theoretical foundation for potential clinical application of TET therapy in patients with MI/RI.

Role of TRP Channels in Metabolism-Related Diseases

Metabolic syndrome (MetS), with its high prevalence and significant impact on cardiovascular disease, poses a substantial threat to human health. The early identification of pathological abnormalities related to MetS and prevention of the risk of associated diseases is of paramount importance. Transient Receptor Potential (TRP) channels, a type of nonselective cation channel, are expressed in a variety of tissues and have been implicated in the onset and progression of numerous metabolism-related diseases. This study aims to review and discuss the expression and function of TRP channels in metabolism-related tissues and blood vessels, and to elucidate the interactions and mechanisms between TRP channels and metabolism-related diseases. A comprehensive literature search was conducted using keywords such as TRP channels, metabolic syndrome, pancreas, liver, oxidative stress, diabetes, hypertension, and atherosclerosis across various academic databases including PubMed, Google Scholar, Elsevier, Web of Science, and CNKI. Our review of the current research suggests that TRP channels may be involved in the development of metabolism-related diseases by regulating insulin secretion and release, lipid metabolism, vascular functional activity, oxidative stress, and inflammatory response. TRP channels, as nonselective cation channels, play pivotal roles in sensing various intra- and extracellular stimuli and regulating ion homeostasis by osmosis. They present potential new targets for the diagnosis or treatment of metabolism-related diseases.

TRPV2 inhibitor tranilast prevents atrial fibrillation in rat models of pulmonary hypertension

Atrial fibrillation (AF) is common in pulmonary hypertension (PH), whereas the mechanisms and treatments remain to be explored. TRPV2 regulates the structure and function of the cardiovascular system; however, little attention has been given to its role in AF. This study was to determine whether TRPV2 was involved in PH-induced AF and the effects of TRPV2 inhibitor tranilast on AF in rat models of PH. Monocrotaline (MCT) and SU5416/hypoxia (SuHx)-induced PH models were performed to detect atrial electrophysiological parameters. Daily tranilast (a TRPV2 inhibitor) or saline was given starting 1 day before PH establishment. PH increased the susceptibility to AF, with TRPV2 up-regulated in the right atria. Compared to PH rats, tranilast reduced AF inducibility and the prolongations of ERP and APD; mitigated cardiopulmonary remodeling and the increases in P-wave duration and P-R interval; partially reversed the down-regulation of ion channels such as Cav1.2, Nav1.5, Kv4.3, Kv4.2, Kv1.5, Kir2.1, Kir3.1, Kir3.4 as well as connexin (Cx) 40 and Cx43; improved right atrial (RA) fibrosis, enlargement, and myocardial hypertrophy; decreased the accumulation of inflammatory cells; down-regulated inflammatory indicators such as TNF-α, IL-1β, CXCL1, and CXCL2; and inhibited the activation of the PI3K-AKT-NF-κB signaling pathway. Our results reveal that TRPV2 participates in PH-induced AF, and TRPV2 inhibitor tranilast prevents PH-induced RA remodeling. TRPV2 might be a promising target for PH-induced AF.

Evidence for the involvement of TRPV2 channels in the modulation of vascular tone in the mouse aorta

AIMS

Transient receptor potential vanilloid 2 (TRPV2) channels are expressed in both smooth muscle and endothelial cells and participate in vascular mechanotransduction and sensing of high temperatures and lipids. Nevertheless, the impact of TRPV2 channel activation by agonists on the coordinated and cell-type specific modulation of vasoreactivity is unknown.

MAIN METHODS

Aorta from 2- to 4-months-old male Oncins France 1 mice was dissected and mounted in tissue baths for isometric tension measurements. TRPV2 channel expression was assessed by immunofluorescence and western blot in mice aortas and in cultured A7r5 rat aortic smooth muscle cells.

KEY FINDINGS

TRPV2 channels were expressed in all three mouse aorta layers. Activation of TRPV2 channels with probenecid evoked endothelium-dependent relaxations through a mechanism that involved activation of smooth muscle Kir and Kv channels. In addition, TRPV2 channel inhibition with tranilast increased endothelium-independent relaxations to probenecid and this effect was abrogated by the KATP channel blocker glibenclamide, revealing that smooth muscle TRPV2 channels induce negative feedback on probenecid relaxations mediated via KATP channel inhibition. Exposure to the NO donor sodium nitroprusside increased TRPV2 channel translocation to the plasma membrane in cultured smooth muscle cells and enhanced negative feedback on probenecid relaxations.

SIGNIFICANCE

In conclusion, we present the first evidence that TRPV2 channels may modulate vascular tone through a balance of opposed inputs from the endothelium and the smooth muscle leading to net vasodilation. The fact that TRPV2 channel-induced activity can be amplified by NO emphasizes the pathophysiological relevance of these findings.

Pharmacological inhibition of TRPV2 attenuates phagocytosis and lipopolysaccharide-induced migration of primary macrophages

BACKGROUND AND PURPOSE

In macrophages, transient receptor potential vanilloid 2 (TRPV2) channel contributes to various cellular processes such as cytokine production, differentiation, phagocytosis and migration. Due to a lack of selective pharmacological tools, its function in immunological processes is not well understood and the identification of novel and selective TRPV2 modulators is highly desirable.

EXPERIMENTAL APPROACH

Novel and selective TRPV2 modulators were identified by screening a compound library using Ca2+ influx assays with human embryonic kidney 293 (HEK293) cells heterologously expressing rat TRPV2. Hits were further characterized and validated with Ca2+ influx and electrophysiological assays. Phagocytosis and migration of macrophages were analysed and the contribution of TRPV2 to the generation of Ca2+ microdomains was studied by total internal reflection fluorescence microscopy (TIRFM).

KEY RESULTS

The compound IV2-1, a dithiolane derivative (1,3-dithiolan-2-ylidene)-4-methyl-5-phenylpentan-2-one), is a potent inhibitor of heterologously expressed TRPV2 channels (IC50  = 6.3 ± 0.7 μM) but does not modify TRPV1, TRPV3 or TRPV4 channels. IV2-1 also inhibits TRPV2-mediated Ca2+ influx in macrophages. IV2-1 inhibits macrophage phagocytosis along with valdecoxib and after siRNA-mediated knockdown. Moreover, TRPV2 inhibition inhibits lipopolysaccharide-induced migration of macrophages whereas TRPV2 activation promotes migration. After activation, TRPV2 shapes Ca2+ microdomains predominantly at the margin of macrophages, which are important cellular regions to promote phagocytosis and migration.

CONCLUSIONS AND IMPLICATIONS

IV2-1 is a novel TRPV2-selective blocker and underline the role of TRPV2 in macrophage-mediated phagocytosis and migration. Furthermore, we provide evidence that TRPV2 activation generates Ca2+ microdomains, which may be involved in phagocytosis and migration of macrophages.

Cyclical Stretching Induces Excess Intracellular Ca2+ Influx in Human Keloid-Derived Fibroblasts In Vitro

BACKGROUND

The incidence of keloids is higher in the case of darker skin. It is more common in the parts exposed to stretching (thorax, abdomen, and joints). Cyclical stretching reportedly induced each Ca2+ spike through differential mechanosensitive channels in human synovial and dermal fibroblasts. Therefore, the authors hypothesized that cyclical stretching also induces a specific Ca2+ spike in keloid-derived fibroblasts.

METHODS

This in vitro study compared the intracellular calcium dynamics induced by cyclical stretching between control (human dermal fibroblasts) and keloid (human keloid-derived fibroblasts) groups. Each group was exposed to two-dimensional stretch using an originally developed stretch microdevice. Intracellular Ca2+ was observed for 5 minutes, including 30 seconds of baseline, under a fluorescent confocal laser microscope. The intracellular Ca2+ concentration was evaluated every 0.5 second using the fluorescence intensity ratio. A positive cellular response was defined as a rise of the ratio by greater than or equal to 20%. The normal response cutoff value was determined by receiver operating characteristic analysis.

RESULTS

The keloid groups were significantly more responsive than the control groups (15.7% versus 8.2%; P = 0.029). In the cellular response-positive cells, the keloid groups reached significantly higher intracellular Ca2+ concentration peaks than the control groups (2.20 versus 1.26; P = 0.0022). The cutoff value was 1.77, and 10.4% of the keloid-derived fibroblasts exhibited a hyper-Ca2+ spike above the normal range.

CONCLUSIONS

Keloid-derived fibroblasts with a hyper-Ca2+ spike might constitute a keloid-specific subpopulation. Hereafter, the authors will study whether the normalization of excessive intracellular Ca2+ concentration leads to keloid treatment in vivo.

CLINICAL RELEVANCE STATEMENT

This study result provided a clue to the onset mechanism of keloids, which the authors hope will lead to the development of new therapy in the future.

Progress on role of ion channels of cardiac fibroblasts in fibrosis

Cardiac fibrosis is defined as excessive deposition of extracellular matrix (ECM) in pathological conditions. Cardiac fibroblasts (CFs) activated by injury or inflammation differentiate into myofibroblasts (MFs) with secretory and contractile functions. In the fibrotic heart, MFs produce ECM which is composed mainly of collagen and is initially involved in maintaining tissue integrity. However, persistent fibrosis disrupts the coordination of excitatory contractile coupling, leading to systolic and diastolic dysfunction, and ultimately heart failure. Numerous studies have demonstrated that both voltage- and non-voltage-gated ion channels alter intracellular ion levels and cellular activity, contributing to myofibroblast proliferation, contraction, and secretory function. However, an effective treatment strategy for myocardial fibrosis has not been established. Therefore, this review describes the progress made in research related to transient receptor potential (TRP) channels, Piezo1, Ca²⁺ release-activated Ca²⁺ (CRAC) channels, voltage-gated Ca²⁺ channels (VGCCs), sodium channels, and potassium channels in myocardial fibroblasts with the aim of providing new ideas for treating myocardial fibrosis.

Frontiers and hotspots evolution in anti-inflammatory studies for coronary heart disease: A bibliometric analysis of 1990-2022

Background

Coronary heart disease (CHD) is characterized by forming of arterial plaques composed mainly of lipids, calcium, and inflammatory cells. These plaques narrow the lumen of the coronary artery, leading to episodic or persistent angina. Atherosclerosis is not just a lipid deposition disease but an inflammatory process with a high-specificity cellular and molecular response. Anti-inflammatory treatment for CHD is a promising therapy; several recent clinical studies (CANTOS, COCOLT, and LoDoCo2) provide therapeutic directions. However, bibliometric analysis data on anti-inflammatory conditions in CHD are lacking. This study aims to provide a comprehensive visual perspective on the anti-inflammatory research in CHD and will contribute to further research.

Materials and methods

All the data were collected from the Web of Science Core Collection (WoSCC) database. We used the Web of Science's systematic tool to analyze the year of countries/regions, organizations, publications, authors, and citations. CiteSpace and VOSviewer were used to construct visual bibliometric networks to reveal the current status and emerging hotspot trends for anti-inflammatory intervention in CHD.

Results

5,818 papers published from 1990 to 2022 were included. The number of publications has been on the rise since 2003. Libby Peter is the most prolific author in the field. "Circulation" was ranked first in the number of journals. The United States has contributed the most to the number of publications. The Harvard University System is the most published organization. The top 5 clusters of keywords co-occurrence are inflammation, C-reactive protein, coronary heart disease, nonsteroidal anti-inflammatory, and myocardial infarction. The top 5 literature citation topics are chronic inflammatory diseases, cardiovascular risk; systematic review, statin therapy; high-density lipoprotein. In the past 2 years, the strongest keyword reference burst is "Nlrp3 inflammasome," and the strongest citation burst is "Ridker PM, 2017 (95.12)."

Conclusion

This study analyzes the research hotspots, frontiers, and development trends of anti-inflammatory applications in CHD, which is of great significance for future studies.

Integrated analysis of WGCNA and machine learning identified diagnostic biomarkers in dilated cardiomyopathy with heart failure

The etiologies and pathogenesis of dilated cardiomyopathy (DCM) with heart failure (HF) remain to be defined. Thus, exploring specific diagnosis biomarkers and mechanisms is urgently needed to improve this situation. In this study, three gene expression profiling datasets (GSE29819, GSE21610, GSE17800) and one single-cell RNA sequencing dataset (GSE95140) were obtained from the Gene Expression Omnibus (GEO) database. GSE29819 and GSE21610 were combined into the training group, while GSE17800 was the test group. We used the weighted gene co-expression network analysis (WGCNA) and identified fifteen driver genes highly associated with DCM with HF in the module. We performed the least absolute shrinkage and selection operator (LASSO) on the driver genes and then constructed five machine learning classifiers (random forest, gradient boosting machine, neural network, eXtreme gradient boosting, and support vector machine). Random forest was the best-performing classifier established on five Lasso-selected genes, which was utilized to select out NPPA, OMD, and PRELP for diagnosing DCM with HF. Moreover, we observed the up-regulation mRNA levels and robust diagnostic accuracies of NPPA, OMD, and PRELP in the training group and test group. Single-cell RNA-seq analysis further demonstrated their stable up-regulation expression patterns in various cardiomyocytes of DCM patients. Besides, through gene set enrichment analysis (GSEA), we found TGF-β signaling pathway, correlated with NPPA, OMD, and PRELP, was the underlying mechanism of DCM with HF. Overall, our study revealed NPPA, OMD, and PRELP serving as diagnostic biomarkers for DCM with HF, deepening the understanding of its pathogenesis.

Multi-target tracheloside and doxorubicin combined treatment of lung adenocarcinoma

Chemotherapy is one of the main methods for malignant lung cancer treatment. However, the side effects of chemotherapy drugs are serious and it is prone to drug resistance. Therefore, multi-drug combination chemotherapy is popular in lung cancer treatment. This study found that tracheloside (TCS) was a novel inhibitor of TMEM16A which was specific high expressed in lung cancer tissues. TCS concentration dependently inhibited TMEM16A with an IC₅₀ of 3.09 ± 0.21 μM. It inhibited lung cancer cells proliferation, migration, and induced cells apoptosis targeting TMEM16A. In addition, molecular docking combined with site-directed mutagenesis confirmed that the binding sites of TCS to TMEM16A were S387, E623, E624. Subsequently, multi-target combined drug administration was conducted based on the different drug targets of TCS and doxorubicin (DOX). Both in vitro and in vivo experiments indicated that the combined administration of low concentration of TCS and DOX achieved satisfactory anticancer effect, and it offset the side effects caused by high concentration of DOX. Therefore, TCS is a safe and efficient anticancer lead compound which can enhance the effect of DOX.

Tyrosine phosphorylation tunes chemical and thermal sensitivity of TRPV2 ion channel

Transient receptor potential vanilloid 2 (TRPV2) is a multimodal ion channel implicated in diverse physiopathological processes. Its important involvement in immune responses has been suggested such as in the macrophages’ phagocytosis process. However, the endogenous signaling cascades controlling the gating of TRPV2 remain to be understood. Here, we report that enhancing tyrosine phosphorylation remarkably alters the chemical and thermal sensitivities of TRPV2 endogenously expressed in rat bone marrow-derived macrophages and dorsal root ganglia (DRG) neurons. We identify that the protein tyrosine kinase JAK1 mediates TRPV2 phosphorylation at the molecular sites Tyr(335), Tyr(471), and Tyr(525). JAK1 phosphorylation is required for maintaining TRPV2 activity and the phagocytic ability of macrophages. We further show that TRPV2 phosphorylation is dynamically balanced by protein tyrosine phosphatase non-receptor type 1 (PTPN1). PTPN1 inhibition increases TRPV2 phosphorylation, further reducing the activation temperature threshold. Our data thus unveil an intrinsic mechanism where the phosphorylation/dephosphorylation dynamic balance sets the basal chemical and thermal sensitivity of TRPV2. Targeting this pathway will aid therapeutic interventions in physiopathological contexts.

All the cells in our body have a membrane that separates their interior from the outside environment. However, studded across this barrier are numerous ion channels which allow the cell to sense and react to changes in its surroundings. This includes the ion channel TRPV2, which opens in response to mechanical pressure, certain chemical signals, or rising temperature levels.

Many types of cell express TRPV2, including cells in the nervous system, muscle, and the immune system. However, despite being extensively studied, it is still not clear how TRPV2 opens and closes upon encountering high temperatures. In particular, previous work suggested that TRPV2 only responds when a cell’s surroundings reach around 52°C, which is a much higher temperature than cells inside our body normally encounter, even during a fever.

To help resolve this mystery, Mo, Pang et al. studied TRPV2 in neurons responsible for sending sensory information and in immune cells called macrophages which had been extracted from rodents and grown in the laboratory. They found that when the cells were bathed in solutions containing magnesium ions, their TRPV2 channels were more sensitive to a number of different cues, including temperature.

Further biochemical experiments showed that magnesium ions do not directly affect TRPV2, but increase the activity of another protein called JAK1. The magnesium ions caused JAK1 to attach specialized structures called phosphorylation tags to TRPV2. This modification (known as phosphorylation) made the channel more sensitive, allowing it to open in response to temperatures as low as 40°C.

Mo, Pang et al. found that inhibiting JAK1 reduced the activity of TRPV2. Conversely, inhibiting the enzyme that removes the phosphorylation tags, called PTPN1, increased the channel’s activity. They also discovered that when JAK1 was blocked, macrophages were less able to ‘eat up’ bacteria, which is one of their main roles in the immune system.

Taken together these experiments advance our understanding of how TRPV2 becomes active. The balance between the phosphorylation by JAK1 and the dephosphorylation by PTPN1 controls the temperature at which TRPV2 opens. Since TRPV2 contributes to several biological functions, including the development of the nervous system, the maintenance of heart muscles, and inflammation, these findings will be important to scientists in a broad range of fields.

Oxidative Stress-Induced TRPV2 Expression Increase Is Involved in Diabetic Cataracts and Apoptosis of Lens Epithelial Cells in a High-Glucose Environment

Cataracts are a serious complication of diabetes. In long-term hyperglycemia, intracellular Ca²⁺ concentration ([Ca²⁺]_i) and reactive oxygen species (ROS) are increased. The apoptosis of lens epithelial cells plays a key role in the development of cataract. We investigated a potential role for transient receptor potential vanilloid 2 (TRPV2) in the development of diabetic cataracts. Immunohistochemical and Western blotting analyses showed that TRPV2 expression levels were significantly increased in the lens epithelial cells of patients with diabetic cataracts as compared with senile cataract, as well as in both a human lens epithelial cell line (HLEpiC) and primary rat lens epithelial cells (RLEpiCs) cultured under high-glucose conditions. The [Ca²⁺]_i increase evoked by a TRPV2 channel agonist was significantly enhanced in both HLEpiCs and RLEpiCs cultured in high-glucose media. This enhancement was blocked by the TRPV2 nonspecific inhibitor ruthenium red and by TRPV2-specific small interfering (si)RNA transfection. Culturing HLEpiCs or RLEpiCs for seven days in high glucose significantly increased apoptosis, which was inhibited by TRPV2-specific siRNA transfection. In addition, ROS inhibitor significantly suppressed the ROS-induced increase of TRPV2-mediated Ca²⁺ signal and apoptosis under high-glucose conditions. These findings suggest a mechanism underlying high-glucose–induced apoptosis of lens epithelial cells, and offer a potential target for developing new therapeutic options for diabetes-related cataracts.

Role of Known Transient Receptor Potential Vanilloid Channels in Modulating Cardiac Mechanobiology

The transient receptor potential (TRP) channels have been described in almost every mammalian cell type. Several members of the Vanilloid (TRPV) subtype have been found to play important roles in modulating cardiac structure and function through Ca²⁺ handling in response to systemic and local mechanobiological cues. In this review, we will consider the most studied TRPV channels in the cardiovascular field; transient receptor potential vanilloid 1 as a modulator of cardiac hypertrophy; transient receptor potential vanilloid 2 as a structural and functional protein; transient receptor potential vanilloid 3 in the development of hypertrophy and myocardial fibrosis; and transient receptor potential vanilloid 4 in its roles modulating the fibrotic and functional responses of the heart to pressure overload. Lastly, we will also review the potential overlapping roles of these channels with other TRP proteins as well as the advances in translational and clinical arenas associated with TRPV channels.

A possible follow-up method for diabetic heart failure patients

INTRODUCTION

Plasma osmolarity is maintained through various mechanisms. The osmolarity of the aqueous humor around the crystalline lens is correlated with plasma osmolarity. A vacuole can be formed in the lens upon changes in osmolarity. The sodium-glucose cotransporter 2 inhibitors (SGLT2i) are new in the treatment of heart failure. They can cause osmotic diuresis but do not affect plasma osmolarity.

OBJECTIVE

It is unclear if the presence or absence of lens vacuole changes can monitor diabetic heart failure and SGLT2i treatment efficacy.

METHODS

Web of Science, PubMed and Scopus databases were searched for relevant articles about osmolarity, diabetes, transient receptor potential vanilloid channel, diabetic heart failure, lens vacuoles up to May 2021.

MAIN MESSAGE

The effect of SGLT2i on osmosis underlies its benefit to heart failure, but this in turn affects many other mechanisms. Failure to experience osmolarity changes will reduce the negative changes in terms of heart failure affected by osmolarity. A practical observable method is needed.

CONCLUSIONS

There is a possibility of using lens vacuoles in the follow-up of diabetic heart failure patients.

Tetrandrine Ameliorates Myocardial Ischemia Reperfusion Injury through miR-202-5p/TRPV2

Objective

This study is aimed at investigating the therapeutic effects of tetrandrine (Tet) on myocardial ischemia reperfusion (I/R) injury and probe into underlying molecular mechanism.

Methods

H9C2 cells were divided into hypoxia/oxygenation (H/R) group, H/R+Tet group, H/R+Tet+negative control (NC) group, and H/R+Tet+miR-202-5p inhibitor group. RT-qPCR was utilized to monitor miR-202-5p and TRPV2 expression, and TRPV2 protein expression was detected via western blot and immunohistochemistry in H9C2 cells. Cardiomyocyte apoptosis was evaluated through detection of apoptosis-related markers and flow cytometry. Furthermore, myocardial enzyme levels were detected by ELISA. Rats were randomly separated into sham operation group, I/R group, I/R+Tet group (50 mg/kg), I/R+Tet+NC group, and I/R+Tet+miR-202-5p inhibitor group. miR-202-5p and TRPV2 mRNA expression was assessed by RT-qPCR. TRPV2 protein expression was detected through western blot and immunohistochemistry in myocardial tissues. Apoptotic levels were assessed via apoptosis-related proteins and TUNEL. Pathological changes were observed by H&E staining. Myocardial infarction size was examined by Evans blue-TCC staining.

Results

Abnormally expressed miR-202-5p as well as TRPV2 was found in H/R H9C2 cells and myocardial tissues of I/R rats, which was ameliorated following Tet treatment. Tet treatment significantly suppressed H/R- or I/R-induced cardiomyocyte apoptosis. ELISA results showed that CK-MB and LDH levels were lowered by Tet treatment in H/R H9C2 cells and serum of I/R rats. H&E staining indicated that Tet reduced myocardial injury in I/R rats. Also, myocardial infarction size was lowered by Tet treatment. The treatment effects of Tet were altered following cotreatment with miR-202-5p inhibitor.

Conclusion

Our findings revealed that Tet may ameliorate myocardial I/R damage via targeting the miR-202-5p/TRPV2 axis.