JAK2/STAT3 activation by melatonin attenuates the mitochondrial oxidative damage induced by myocardial ischemia/reperfusion injury

Programmed death of cardiomyocytes in cardiovascular disease and new therapeutic approaches

Cardiovascular diseases (CVDs) have a complex pathogenesis and pose a major threat to human health. Cardiomyocytes have a low regenerative capacity, and their death is a key factor in the morbidity and mortality of many CVDs. Cardiomyocyte death can be regulated by specific signaling pathways known as programmed cell death (PCD), including apoptosis, necroptosis, autophagy, pyroptosis, and ferroptosis, etc. Abnormalities in PCD can lead to the development of a variety of cardiovascular diseases, and there are also molecular-level interconnections between different PCD pathways under the same cardiovascular disease model. Currently, the link between programmed cell death in cardiomyocytes and cardiovascular disease is not fully understood. This review describes the molecular mechanisms of programmed death and the impact of cardiomyocyte death on cardiovascular disease development. Emphasis is placed on a summary of drugs and potential therapeutic approaches that can be used to treat cardiovascular disease by targeting and blocking programmed cell death in cardiomyocytes.

Significance of Melatonin in the Regulation of Circadian Rhythms and Disease Management

Melatonin, the 'hormone of darkness' is a neuronal hormone secreted by the pineal gland and other extra pineal sites. Responsible for the circadian rhythm and seasonal behaviour of vertebrates and mammals, melatonin is responsible for regulating various physiological conditions and the maintenance of sleep, body weight and the neuronal activities of the ocular sites. With its unique amphiphilic structure, melatonin can cross the cellular barriers and elucidate its activities in the subcellular components, including mitochondria. Melatonin is a potential scavenger of oxygen and nitrogen-reactive species and can directly obliterate the ROS and RNS by a receptor-independent mechanism. It can also regulate the pro- and anti-inflammatory cytokines in various pathological conditions and exhibit therapeutic activities against neurodegenerative, psychiatric disorders and cancer. Melatonin is also found to show its effects on major organs, particularly the brain, liver and heart, and also imparts a role in the modulation of the immune system. Thus, melatonin is a multifaceted candidate with immense therapeutic potential and is still considered an effective supplement on various therapies. This is primarily due to rectification of aberrant circadian rhythm by improvement of sleep quality associated with risk development of neurodegenerative, cognitive, cardiovascular and other metabolic disorders, thereby enhancing the quality of life.

Insight into the cardioprotective effects of melatonin: shining a spotlight on intercellular Sirt signaling communication

Cardiovascular diseases (CVDs) are the leading causes of death and illness worldwide. While there have been advancements in the treatment of CVDs using medication and medical procedures, these conventional methods have limited effectiveness in halting the progression of heart diseases to complete heart failure. However, in recent years, the hormone melatonin has shown promise as a protective agent for the heart. Melatonin, which is secreted by the pineal gland and regulates our sleep-wake cycle, plays a role in various biological processes including oxidative stress, mitochondrial function, and cell death. The Sirtuin (Sirt) family of proteins has gained attention for their involvement in many cellular functions related to heart health. It has been well established that melatonin activates the Sirt signaling pathways, leading to several beneficial effects on the heart. These include preserving mitochondrial function, reducing oxidative stress, decreasing inflammation, preventing cell death, and regulating autophagy in cardiac cells. Therefore, melatonin could play crucial roles in ameliorating various cardiovascular pathologies, such as sepsis, drug toxicity-induced myocardial injury, myocardial ischemia-reperfusion injury, hypertension, heart failure, and diabetic cardiomyopathy. These effects may be partly attributed to the modulation of different Sirt family members by melatonin. This review summarizes the existing body of literature highlighting the cardioprotective effects of melatonin, specifically the ones including modulation of Sirt signaling pathways. Also, we discuss the potential use of melatonin-Sirt interactions as a forthcoming therapeutic target for managing and preventing CVDs.

L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice

BACKGROUND

L-theanine is a unique non-protein amino acid in tea that is widely used as a safe food additive. We investigated the cardioprotective effects and mechanisms of L-theanine in myocardial ischemia-reperfusion injury (MIRI).

METHODS

The cardioprotective effects and mechanisms of L-theanine and the role of Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling were investigated in MIRI mice using measures of cardiac function, oxidative stress, and apoptosis.

RESULTS

Administration of L-theanine (10 mg/kg, once daily) suppressed the MIRI-induced increase in infarct size and serum creatine kinase and lactate dehydrogenase levels, as well as MIRI-induced cardiac apoptosis, as evidenced by an increase in Bcl-2 expression and a decrease in Bax/caspase-3 expression. Administration of L-theanine also decreased the levels of parameters reflecting oxidative stress, such as dihydroethidium, malondialdehyde, and nitric oxide, and increased the levels of parameters reflecting anti-oxidation, such as total antioxidant capacity (T-AOC), glutathione (GSH), and superoxide dismutase (SOD) in ischemic heart tissue. Further analysis showed that L-theanine administration suppressed the MIRI-induced decrease of phospho-JAK2 and phospho-STAT3 in ischemic heart tissue. Inhibition of JAK2 by AG490 (5 mg/kg, once daily) abolished the cardioprotective effect of L-theanine, suggesting that the JAK2/STAT3 signaling pathway may play an essential role in mediating the anti-I/R effect of L-theanine.

CONCLUSIONS

L-theanine administration suppresses cellular apoptosis and oxidative stress in part via the JAK2/STAT3 signaling pathway, thereby attenuating MIRI-induced cardiac injury. L-theanine could be developed as a potential drug to alleviate cardiac damage in MIRI.

Protective role of pretreatment with Anisodamine against sepsis-induced diaphragm atrophy via inhibiting JAK2/STAT3 pathway

There is an increasing tendency for sepsis patients to suffer from diaphragm atrophy as well as mortality. Therefore, reducing diaphragm atrophy could benefit sepsis patients' prognoses. Studies have shown that Anisodamine (Anis) can exert antioxidant effects when blows occur. However, the role of Anisodamine in diaphragm atrophy in sepsis patients has not been reported. Therefore, this study investigated the antioxidant effect of Anisodamine in sepsis-induced diaphragm atrophy and its mechanism. We used cecal ligation aspiration (CLP) to establish a mouse septic mode and stimulated the C2C12 myotube model with lipopolysaccharide (LPS). After treatment with Anisodamine, we measured the mice's bodyweight, diaphragm weight, fiber cross-sectional area and the diameter of C2C12 myotubes. The malondialdehyde (MDA) levels in the diaphragm were detected using the oxidative stress kit. The expression of MuRF1, Atrogin1 and JAK2/STAT3 signaling pathway components in the diaphragm and C2C12 myotubes was measured by RT-qPCR and Western blot. The mean fluorescence intensity of ROS in C2C12 myotubes was measured by flow cytometry. Meanwhile, we also measured the levels of Drp1 and Cytochrome C (Cyt-C) in vivo and in vitro by Western blot. Our study revealed that Anisodamine alleviated the reduction in diaphragmatic mass and the loss of diaphragmatic fiber cross-sectional area and attenuated the atrophy of the C2C12 myotubes by inhibiting the expression of E3 ubiquitin ligases. In addition, we observed that Anisodamine inhibited the JAK2/STAT3 signaling pathway and protects mitochondrial function. In conclusion, Anisodamine alleviates sepsis-induced diaphragm atrophy, and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway.

Stellate Ganglion Block Attenuates LPS-Induced Acute Lung Injury by Activating Sirt3 Regulation of Oxidative Stress and Inflammation

Stellate ganglion blocks (SGBs) has been applied in clinics to alleviate pain-related syndromes for almost a century. In recent years, it has been reported that SGB can attenuate acute lung injury (ALI) in animals. However, the details of these molecular mechanisms remain complex and unclear. In this study, rats were randomly divided into four groups: group C (receiving no treatment), group NS (receiving the intratracheal instillation of normal saline), group L (receiving the intratracheal instillation of LPS) and group LS (receiving SGB after the intratracheal instillation of LPS). The pathological damage of lung tissue, arterial blood gases, the differentiation of alveolar macrophages (AMs) and inflammatory cytokines (IL-1β, IL-6, IL-10) were detected. Furthermore, the oxidative stress indexes (ROS, CYP-D, T-SOD, Mn-SOD and CAT) in serum and the levels of Sirt3 signaling-associated proteins (JAK2/STAT3, NF-κb p65, CIRP and NLRP3) in the lungs were measured. The results revealed that SGB could attenuate lung tissue damage, improve pulmonary oxygenation, promote the differentiation of AMs to the M2 phenotype, decrease the secretion of IL-1β and IL-6, and increase the secretion of IL-10. Meanwhile, SGB was found to inhibit the production of ROS and CYP-D, and enhance the activities of T-SOD, Mn-SOD and CAT. Furthermore, SGB upregulated Sirt3 and downregulated JAK2/STAT3 and NF-κb p65 phosphorylation, CIRP and NLRP3. Our work revealed that SGB could attenuate LPS-induced ALI by activating the Sirt3-mediated regulation of oxidative stress and pulmonary inflammation; this may shed new light upon the protection of SGB and provide a novel prophylactic strategy for LPS-induced ALI.

Exploring unconventional targets in myofibroblast transdifferentiation outside classical TGF-β signaling in renal fibrosis

We propose that the key initiators of renal fibrosis are myofibroblasts which originate from four predominant sources-fibroblasts, pericytes, endothelial cells and macrophages. Increased accumulation of renal interstitial myofibroblasts correlates with an increase in collagen, fibrillar proteins, and fibrosis severity. The canonical TGF-β pathway, signaling via Smad proteins, is the central molecular hub that initiates these cellular transformations. However, directly targeting these classical pathway molecules has proven challenging due their integral roles in metabolic process, and/or non-sustainable effects involving compensatory cross-talk with TGF-β. This review explores recently discovered alternative molecular targets that drive transdifferentiation into myofibroblasts. Discovering targets outside of the classical TGF-β/Smad pathway is crucial for advancing antifibrotic therapies, and strategically targeting the development of myofibroblasts offers a promising approach to control excessive extracellular matrix deposition and impede fibrosis progression.

Clerodendrum Glandulosum Lindl.: A Review of Ethnopharmacology, Pharmacological Potentials, and their Mechanism of Action

Clerodendrum glandulosum Lindl. is popularly known for its traditional herbal remedies and therapeutic properties among the people of Northeast Indian communities, as well as Chinese traditional medicine. For the myriad pharmacological properties, viz., anti-hypertensive, hypolipidemic, hepatoprotective, anti-inflammatory, and neuroprotective, planting this species in kitchen gardens is a common practice to treat various ailments, especially hypertension, diabetes, and other metabolic complications. Different phytochemicals, representing the diverse classes of secondary metabolites comprising physiological and phytopharmaceutical significance, have been reported from C. glandulosum. Compounds with terpenoids, steroids, and phenolics are in demand in the pharmaceutical industry. An overview of the mechanism of action of the prominent compounds has also been collated for future research on C. glandulosum-based therapeutics. Current information focuses on this important medicinal plant's ethnomedicinal use, phytochemistry, pharmacology, associated mechanisms, and toxicology. This review will help explore this potential medicinal plant, which can pave the path for its application in the pharmaceutical industry.

Heart Transplant and Donors After Circulatory Death: A Clinical-Preclinical Systematic Review

INTRODUCTION

Heart transplantation is the treatment of choice for end-stage heart failure. There is a mismatch between the number of donor hearts available and the number of patients awaiting transplantation. Expanding the donor pool is critically important. The use of hearts donated following circulatory death is one approach to increasing the number of available donor hearts.

MATERIALS AND METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines utilizing Pubmed/MEDLINE and Embase. Articles including adult human studies and preclinical animal studies of heart transplantation following donation after circulatory death were included. Studies of pediatric populations or including organs other than heart were excluded.

RESULTS

Clinical experience and preclinical studies are reviewed. Clinical experience with direct procurement, normothermic regional perfusion, and machine perfusion are included. Preclinical studies addressing organ function assessment and enhancement of performance of marginal organs through preischemic, procurement, preservation, and reperfusion maneuvers are included. Articles addressing the ethical considerations of thoracic transplantation following circulatory death are also reviewed.

CONCLUSIONS

Heart transplantation utilizing organs procured following circulatory death is a promising method to increase the donor pool and offer life-saving transplantation to patients on the waitlist living with end-stage heart failure. There is robust ongoing preclinical and clinical research to optimize this technique and improve organ yield. There are also ongoing ethical considerations that must be addressed by consensus before wide adoption of this approach.

Bakuchiol, a natural constituent and its pharmacological benefits

Background and aims

Natural compounds extracted from medicinal plants have recently gained attention in therapeutics as they are considered to have lower Toxicity and higher tolerability relative to chemically synthesized compounds. Bakuchiol from Psoralea corylifolia L. is one such compound; it is a type of meroterpene derived from the leaves and seeds of Psoralea corylifolia plants. Natural sources of bakuchiol have been used in traditional Chinese and Indian medicine for centuries due to its preventive benefits against tumors and inflammation. It plays a strong potential role as an antioxidant with impressive abilities to remove Reactive Oxygen Species (ROS). This review has focused on bakuchiol's extraction, therapeutic applications, and pharmacological benefits.

Methods

A search strategy has been followed to retrieve the relevant newly published literature on the pharmacological benefits of bakuchiol. After an extensive study of the retrieved articles and maintaining the inclusion and exclusion criteria, 110 articles were finally selected for this review.

Results

Strong support of primary research on the protective effects via antitumorigenic, anti-inflammatory, antioxidative, antimicrobial, and antiviral activities are delineated.

Conclusions

From ancient to modern life, medicinal plants have always been drawing the attention of human beings to alleviate ailments for a healthy and balanced lifestyle. This review is a comprehensive approach to highlighting bona fide essential pharmacological benefits and mechanisms underlying their therapeutic applications.

Melatonin attenuates cellular senescence and apoptosis in diabetic nephropathy by regulating STAT3 phosphorylation

AIMS

Melatonin is an endogenous hormone related to the regulation of biorhythm. Previous researchers have found that melatonin can ameliorate diabetic nephropathy (DN), but the mechanism remains to be elucidated. To discover the possible mechanism by which melatonin prevents DN, we investigated the potential effects of melatonin on signal transducer and activator of transcription 3 (STAT3) on the progression of cellular senescence and apoptosis.

MAIN METHODS

Cellular senescence, apoptosis and the underlying mechanism of melatonin were investigated both in vivo and in vitro. C57BL/6 mice were intraperitoneally injected with streptozotocin (STZ) to establish DN. For an in vitro model of DN, human renal cortex proximal epithelial tubule (HK-2) cells were exposed to high glucose conditions.

KEY FINDINGS

Melatonin inhibited the phosphorylation of STAT3, decreased the expression of senescence proteins p53, p21 and p16INK4A. Melatonin also downregulated the expression of apoptotic proteins, including cleaved PARP1, cleaved caspase-9 and -3. Melatonin treatment decreased the positive area of senescence-associated galactosidase (SA-β-gal) staining and the number of TUNEL-positive cells in kidneys of DN mice. In vitro, melatonin inhibited STAT3 phosphorylation and lowered cellular senescence and apoptosis markers, in a manner similar to the STAT3 inhibitor S3I-201. In addition, the inhibition effect of melatonin on cellular senescence and apoptosis in HK-2 cells was reversed by the usage of recombinant IL-6 (rIL-6), which can induce STAT3 phosphorylation.

SIGNIFICANCE

We, for the first time, demonstrate that melatonin inhibits STAT3 phosphorylation, which is involved in alleviating the cellular senescence and apoptosis in DN.

Bisphenol S dysregulates thyroid hormone homeostasis; Testicular survival, redox and metabolic status: Ameliorative actions of melatonin

Bisphenol S (BPS) is an incipient threat for reproductive health augmenting societal burden of infertility worldwide. In the present study, we investigated the mechanism of BPS induced testicular dysfunctions and protective actions of melatonin in mice. BPS (150 mg/kg BW) treatment reduced serum T3/T4, testosterone and elevated insulin levels along with adverse effect on thyroid and testicular histoarchitecture. Further, BPS treatment compromised sperm quality, reduced mRNA expression of steroidogenic (StAR/CYP11A1) markers, elevated oxidative load and disrupts metabolic status. However, melatonin (5 mg/kg BW) administration to BPS treated mice showed improved hormonal/histological parameters, enhanced thyroid hormone (TR-α/Dio-2)/melatonin (MT-1) receptor expressions. Further, melatonin treatment modulated the expression of testicular survival/redox (SIRT1/PGC-1α/FOXO-1, Nrf2/HO-1, p-JAK2/p-STAT3), proliferative (PCNA) and metabolic (IR/pAKT/GLUT-1) markers. Furthermore, melatonin treatment enhanced testicular antioxidant status and reduced caspase-3 expression. In conclusion, our results showed that BPS induces endocrine/oxidative and metabolic anomalies while melatonin improved male reproductive health.

The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells

It is widely accepted that oxidative stress (OS) coming from a wide variety of causes has detrimental effects on male fertility. Antioxidants could have a significant role in the treatment of male infertility, and the current systematic review on the role of melatonin to ameliorate OS clearly shows that improvement of semen parameters follows melatonin supplementation. Although melatonin has considerable promise, further studies are needed to clarify its ability to preserve or restore semen quality under stress conditions in varied species. The present review examines the actions of melatonin via receptor subtypes and its function in the context of OS across male vertebrates.

Melatonin Restores Autophagic Flux by Activating the Sirt3/TFEB Signaling Pathway to Attenuate Doxorubicin-Induced Cardiomyopathy

Doxorubicin (DOX) chemotherapy in cancer patients increases the risk of the occurrence of cardiac dysfunction and even results in congestive heart failure. Despite the great progress of pathology in DOX-induced cardiomyopathy, the underlying molecular mechanisms remain elusive. Here, we investigate the protective effects and the underlying mechanisms of melatonin in DOX-induced cardiomyopathy. Our results clearly show that oral administration of melatonin prevented the deterioration of cardiac function caused by DOX treatment, which was evaluated by left ventricular ejection fraction and fractional shortening as well as cardiac fibrosis. The ejection fraction and fractional shortening in the DOX group were 49.48% and 25.5%, respectively, while melatonin treatment increased the ejection fraction and fractional shortening to 60.33 and 31.39 in wild-type mice. Cardiac fibrosis in the DOX group was 3.97%, while melatonin reduced cardiac fibrosis to 1.95% in wild-type mice. Sirt3 is a mitochondrial deacetylase and shows protective effects in diverse cardiovascular diseases. Therefore, to test whether Sirt3 is a key factor in protection, Sirt3 knockout mice were used, and it was found that the protective effects of melatonin in DOX-induced cardiomyopathy were partly abolished. Further analysis revealed that Sirt3 and its downstream molecule TFEB were downregulated in response to DOX treatment, while melatonin administration was able to significantly enhance the expressions of Sirt3 and TFEB. Our in vitro study demonstrated that melatonin enhanced lysosomal function by increasing the Sirt3-mediated increase at the TFEB level, and the accumulation of autolysosomes induced by DOX treatment was attenuated. Thus, autophagic flux disrupted by DOX treatment was restored by melatonin supplementation. In summary, our results demonstrate that melatonin protects the heart against DOX injury by the restoration of autophagic flux via the activation of the Sirt3/TFEB signaling pathway.

A novel signaling transduction pathway of melatonin on lactose synthesis in cows via melatonin receptor 1 (MT1) and prolactin receptor (PRLR)

In the current study, we explored the relationship between melatonin and lactose synthesis in in vivo and in vitro conditions. We found that long-term melatonin feeding to the dairy cows significantly reduced the milk lactose content in a dose dependent manner. This lactose reduction was not associated with a negative energy balance, since melatonin treatment did not alter the fat, glucose, or protein metabolisms of the cows. To identify the potential molecular mechanisms, the cow's mammary epithelial cells were cultured for gene expression analysis. The results showed that the effect of melatonin on lactose reduction was mediated by its receptor MT1. MT1 activation downregulated the mRNA expression of the prolactin receptor gene (PRLR), which then suppressed the gene expression of SLC35B1. SLC35B1 is a galactose transporter and is responsible for the transportation of galactose to Golgi apparatus for lactose synthesis. Its suppression reduced the lactose synthesis and the milk lactose content. The discovery of this signal transduction pathway of melatonin on lactose synthesis provides a novel aspect of melatonin's effect on carbohydrate metabolism in cows and maybe also in other mammals, including humans.

Mitochondria-targeted melatonin photorelease supports the presence of melatonin MT1 receptors in mitochondria inhibiting respiration

The presence of signaling-competent G protein-coupled receptors in intracellular compartments is increasingly recognized. Recently, the presence of Gi/o protein-coupled melatonin MT1 receptors in mitochondria has been revealed, in addition to the plasma membrane. Melatonin is highly cell permeant, activating plasma membrane and mitochondrial receptors equally. Here, we present MCS-1145, a melatonin derivative bearing a triphenylphosphonium cation for specific mitochondrial targeting and a photocleavable o-nitrobenzyl group releasing melatonin upon illumination. MCS-1145 displayed low affinity for MT1 and MT2 but spontaneously accumulated in mitochondria, where it was resistant to washout. Uncaged MCS-1145 and exogenous melatonin recruited β-arrestin 2 to MT1 in mitochondria and inhibited oxygen consumption in mitochondria isolated from HEK293 cells only when expressing MT1 and from mouse cerebellum of WT mice but not from MT1-knockout mice. Overall, we developed the first mitochondria-targeted photoactivatable melatonin ligand and demonstrate that melatonin inhibits mitochondrial respiration through mitochondrial MT1 receptors.

Therapeutic Benefit of Melatonin in Choroidal Neovascularization During Aging Through the Regulation of Senescent Macrophage/Microglia Polarization

Purpose

This study aimed to investigate the age-dependent anti-angiogenic capability of melatonin in choroidal neovascularization (CNV) and to explore the underlying molecular mechanisms.

Methods

In the present study, a laser-induced CNV model was established in both young (three months of age) and old (18 months of age) mice, and the size of CNV lesions and vascular leakage was detected by morphological and imaging examination. Next, Western blot and immunostaining were used to observe the levels of M2 markers, senescence-related markers, and molecules involved in IL-10/STAT3 pathway. Additionally, colivelin was used to study the effect of IL-10/STAT3 pathway activation on the expression of M2 markers and senescence-related markers by Western blot and immunostaining. Finally, the effects of colivelin on melatonin-induced reduction of CNV size and vascular leakage in mice at different ages were assessed using morphological and imaging examination.

Results

Our results revealed that aging promoted M2 macrophage/microglia polarization, and aggravated CNV and vascular leakage. Melatonin significantly inhibited the M2 polarization of senescent macrophage/microglia and reduced the CNV area and vascular leakage. Moreover, melatonin markedly suppressed IL-10/STAT3 pathway activation in the macrophage/microglia of old mice, and STAT3 activator colivelin reversed the suppressive effect of melatonin on M2 polarization of senescent macrophage/microglia and laser-induced CNV in old mice.

Conclusions

Our data demonstrated that melatonin significantly prevented the M2 polarization of senescent macrophage/microglia by inhibiting the IL-10/STAT3 pathway, and eventually attenuated senescence-associated CNV. These findings suggested that melatonin could serve as a promising therapeutic agent to treat CNV and other age-related ocular diseases.

Melatonin Preserves Fluidity in Cell and Mitochondrial Membranes against Hepatic Ischemia-Reperfusion

We evaluated the in vivo effects of melatonin treatment on oxidative damage in the liver in an experimental model of ischemia-reperfusion. A total of 37 male Sprague-Dawley rats were randomly divided into four groups: control, ischemia, ischemia + reperfusion, and ischemia + reperfusion + melatonin. Hepatic ischemia was maintained for 20 min, and the clamp was removed to initiate vascular reperfusion for 30 min. Melatonin (50 mg/kg body weight) was intraperitoneally administered. Fluidity was measured by polarization changes in 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene-p-toluene sulfonate). After 20 min of ischemia, no significant changes were observed in cell and mitochondrial membrane fluidity levels, lipid peroxidation, and protein carbonylation. However, after 30 min of reperfusion, membrane fluidity decreased compared to controls. Increases in lipid and protein oxidation were also seen in hepatic homogenates of animals exposed to reperfusion. Melatonin injected 30 min before ischemia and reperfusion fully prevented membrane rigidity and both lipid and protein oxidation. Livers from ischemia-reperfusion showed histopathological alterations and positive labeling with antibodies to oxidized lipids and proteins. Melatonin reduced the severity of these morphological changes and protected against in vivo ischemia-reperfusion-induced toxicity in the liver. Therefore, melatonin might be a candidate for co-treatment for patients with hepatic vascular occlusion followed by reperfusion.

PPARγ Regulates Macrophage Polarization by Inhibiting the JAK/STAT Pathway and Attenuates Myocardial Ischemia/Reperfusion Injury In Vivo

This study aimed to investigate the role of PPARγ and underlying mechanisms in myocardial ischemia/reperfusion injury (IRI). IRI was surgically induced in mice and neonatal rat cardiomyocytes (NRCM) were exposed to oxygen-glucose deprivation and reoxygenation (OGD/R). Quantitative genetic analysis and western blotting were performed to assess mRNA and protein levels, respectively, of PPARγ, as well as of different inflammatory, fibrosis, and apoptosis markers in cells and tissues. PPARγ was overexpressed in the heart of mice and NRCMs by viral transfection. Apoptosis and fibrosis were detected by TUNEL and Masson's trichrome staining, respectively. Enzyme-linked immunosorbent assay was performed to detect M1 and M2 macrophage-related inflammatory factors present in mouse sera. PPARγ overexpression significantly inhibited OGD/R- and IRI-induced cardiomyocyte apoptosis and fibrosis in vitro and in vivo. Moreover, PPARγ overexpression inhibited IRI-induced secretion of M1-related proinflammatory factors, whereas it supported the secretion of M2-related anti-inflammatory factors. Notably, these events were found to be mediated by the JAK/STAT pathway. In conclusion, PPARγ regulates macrophage polarization upon IRI via the JAK/STAT pathway, which will in turn prevent myocardial apoptosis and fibrosis. Hence, PPARγ may represent a valuable target for myocardial IRI treatment.

Cardioprotective effects of curcumin against myocardial I/R injury: A systematic review and meta-analysis of preclinical and clinical studies

Objective: Myocardial ischemia-reperfusion (I/R) injury is a complex clinical problem that often leads to further myocardial injury. Curcumin is the main component of turmeric, which has been proved to have many cardioprotective effects. However, the cardioprotective potential of curcumin remains unclear. The present systematic review and meta-analysis aimed to evaluate the clinical and preclinical (animal model) evidence regarding the effect of curcumin on myocardial I/R injury.

Methods: Eight databases and three register systems were searched from inception to 1 November 2022. Data extraction, study quality assessment, data analyses were carried out strictly. Then a fixed or random-effects model was applied to analyze the outcomes. SYRCLE’s-RoB tool and RoB-2 tool was used to assess the methodological quality of the included studies. RevMan 5.4 software and stata 15.1 software were used for statistical analysis.

Results: 24 animal studies, with a total of 503 animals, and four human studies, with a total of 435 patients, were included in this study. The meta-analysis of animal studies demonstrated that compared with the control group, curcumin significantly reduced myocardial infarction size (p < 0.00001), and improved the cardiac function indexes (LVEF, LVFS, LVEDd, and LVESd) (p < 0.01). In addition, the indexes of myocardial injury markers, myocardial oxidation, myocardial apoptosis, inflammation, and other mechanism indicators also showed the beneficial effect of curcumin (p < 0.05). In terms of clinical studies, curcumin reduced the incidence of cardiac dysfunction, myocardial infarction in the hospital and MACE in the short term, which might be related to its anti-inflammatory and anti-oxidative property. Dose-response meta-analysis predicted, 200 mg/kg/d bodyweight was the optimal dose of curcumin in the range of 10–200 mg/kg/d, which was safe and non-toxic according to the existing publications.

Conclusion: Our study is the first meta-analysis that includes both preclinical and clinical researches. We suggested that curcumin might play a cardioprotective role in acute myocardial infarction in animal studies, mainly through anti-oxidative, anti-inflammatory, anti-apoptosis, and anti-fibrosis effects. In addition, from the clinical studies, we found that curcumin might need a longer course of treatment and a larger dose to protect the myocardium, and its efficacy is mainly reflected on reducing the incidence of myocardial infarction and MACE. Our finding provides some meaningful advice for the further research.

Melatonin ameliorates osteoarthritis rat cartilage injury by inhibiting matrix metalloproteinases and JAK2/STAT3 signaling pathway

OBJECTIVE

To observe the effect of melatonin intervention on rat knee osteoarthritis (KOA) model and explore its mechanism.

METHODS

A total of 81 Sprague-Dawley (SD) rats were employed. Haematoxylin and eosin (H&E) staining and safranin o-solid green staining were used to observe the changes of pathology in KOA, and inflammation factors in serum were detected by enzyme-linked immunosorbent assay (ELISA), type II collagen (Col-II) was detected by immunohistochemistry, chondrocyte apoptosis was detected by TdT-mediated dUTP nick-end labeling (TUNEL). The expression of matrix metalloproteinases (MMPs) and JAK2/STAT3 signaling were detected by western blot.

RESULTS

Melatonin treatment ameliorated the histomorphology of knee joint in rats compared to the model group. The contents of TNF-α, IL-6, and IL-1β in serum were decreased after melatonin treatment. In addition, compared to the model group, the positive expression of Col-II increased, the chondrocyte apoptosis decreased after melatonin treatment. Interestingly, the expression levels of MMP3, MMP9, MMP13, p-JAK2 and p-STAT3 decreased (p < 0.05). Importantly, melatonin combined with AG490 is significantly ameliorates histomorphology of knee joint, reduced cartilage loss compared with melatonin treatment alone.

CONCLUSIONS

Melatonin treatment can effectively diminish the cartilage injury. Its mechanism may be related to protect the articular cartilage by reducing the release of inflammatory factors, inhibit the expression of MMPs and JAK2/STAT3 signaling.

LincRNA00612 inhibits apoptosis and inflammation in LPS-induced BEAS-2B cells via enhancing interaction between p-STAT3 and A2M promoter

Long non-coding RNAs (lncRNAs) have been reported as key regulators of chronic obstructive pulmonary disease (COPD). This study aimed to figure out the regulatory mechanism as well as the effects of lncRNA00612 (LINC00612) in lipopolysaccharide (LPS)-induced inflammation and apoptosis in BEAS-2B cells. LINC00612 and its co-expressed gene alpha-2-macroglobulin (A2M) were strikingly downregulated in the peripheral venous blood of COPD patients. Overexpressed LINC00612 enhances BEAS-2B cells against apoptosis and inflammatory reactions mediated by LPS, however, an A2M knockdown can attenuate the degree of the enhancement. Bioinformatics analysis revealed putative binding sites between LINC00612, signal transducer and activator of transcription 3 (STAT3) and the A2M promoter, while RNA antisense purification and Chromatin immunoprecipitation were performed to confirm the prediction. Knockdown of LINC00612 impaired the binding of p-STAT3 to the promoter of A2M, which meant that LINC00612 was critical for the binding of STAT3 with the A2M promoter. Therefore, it can be concluded that LINC00612 ameliorates LPS-induced cell apoptosis and inflammation via recruiting STAT3 to bind to A2M. This conclusion will serve as a theoretical foundation for the treatment of COPD.

Patchouli alcohol protects against myocardial ischaemia-reperfusion injury by regulating the Notch1/Hes1 pathway

CONTEXT

Patchouli alcohol (PA) has protective effects on cerebral ischaemia/reperfusion (I/R) injury, but its efficacy on myocardial ischaemia-reperfusion (MI/R) has yet to be addressed.

OBJECTIVE

To examine the therapeutic effect of PA on myocardial ischaemia-reperfusion (I/R) injury.

MATERIALS AND METHODS

C57BL/6 male mice were randomly divided into sham, MI/R, MI/R + PA-10, MI/R + PA-20 and MI/R + PA-40 groups. In vivo MI/R model was established by ligating the anterior descending coronary artery of the heart. In vitro stimulated IR cell model was constructed by using the rat cardiomyocyte H9C2 cell line. Mice in the treatment groups were intraperitoneally injected with PA (10, 20, 40 mg/kg) for 30 days then subjected to surgery, and cells in the experimental group were pre-treated with PA (1, 10 or 100 μmol/L). After treatment, mouse heart function, myocardial injury markers, myocardial infarction and Notch1/Hes1 expression, endoplasmic reticulum stress markers, and apoptosis-related proteins were determined.

RESULTS

In vivo, PA treatment improved hemodynamic parameter changes and myocardial enzymes, increased the left ventricular ejection fraction and left ventricular fractional shortening, reduced the left ventricular end-systolic diameter and inhibited CK-MB, cTnI and cTnT levels. In addition, PA attenuated myocardial tissue damage and apoptosis. PA treatment elevated Notch1, NICD and Hes1 levels and suppressed the levels of ATF4, p-PERK/PERK, and cleaved caspase-3/caspase-3 in vitro and in vivo.

DISCUSSION AND CONCLUSION

PA protects against MI/R, possibly by modulating ER stress, apoptosis and the Notch1/Hes1 signalling pathways. These findings indicate that PA may be a promising candidate for treating ischaemic heart diseases.

Ac2-26 attenuates hepatic ischemia-reperfusion injury in mice via regulating IL-22/IL-22R1/STAT3 signaling

Hepatic ischemia-reperfusion injury (HIRI) is one of the major sources of mortality and morbidity associated with hepatic surgery. Ac2-26, a short peptide of Annexin A1 protein, has been proved to have a protective effect against IRI. However, whether it exerts a protective effect on HIRI has not been reported. The HIRI mice model and the oxidative damage model of H₂O₂-induced AML12 cells were established to investigate whether Ac2-26 could alleviate HIRI by regulating the activation of IL-22/IL-22R1/STAT3 signaling. The protective effect of Ac2-26 was measured by various biochemical parameters related to liver function, apoptosis, inflammatory reaction, mitochondrial function and the expressions of IL-22, IL-22R1, p-STAT3^Tyr705. We discovered that Ac2-26 reduced the Suzuki score and cell death rate, and increased the cell viability after HIRI. Moreover, we unraveled that Ac2-26 significantly decreased the number of apoptotic hepatocytes, and the expressions of cleaved-caspase-3 and Bax/Bcl-2 ratio. Furthermore, HIRI increased the contents of malondialdehyde (MDA), NADP⁺/NADPH ratio and reactive oxygen species (ROS), whereas Ac2-26 decreased them significantly. Additionally, Ac2-26 remarkably alleviated mitochondria dysfunction, which was represented by an increase in the adenosine triphosphate (ATP) content and mitochondrial membrane potential, a decrease in mitochondrial DNA (mtDNA) damage. Finally, we revealed that Ac2-26 pretreatment could significantly inhibit the activation of IL-22/IL22R1/STAT3 signaling. In conclusion, this work demonstrated that Ac2-26 ameliorated HIRI by reducing oxidative stress and inhibiting the mitochondrial apoptosis pathway, which might be closely related to the inhibition of the IL-22/IL22R1/STAT3 signaling pathway.

Lycorine and organ protection: Review of its potential effects and molecular mechanisms

BACKGROUND

Multiorgan dysfunction, especially sepsis-related multiorgan damage, remains a major cause of high mortality in the late stages of infection and a great clinical challenge. In recent years, natural drugs have received widespread attention because of their low cost, wide sources, high efficacy, low toxicity, and limited side effects. Lycorine, a natural compound extracted from Amaryllidaceae, exhibits multiple pharmacological activities, including in the regulation of autophagy and the induction of cancer cell apoptosis, and has anti-inflammatory, antifungal, antiviral, antimalarial, and antitumor activities. However, studies on lycorine have mainly focused on its antitumor properties, and research on its use for organ protection, especially in sepsis-related organ injury, is relatively limited.

PURPOSE

To review and discuss the effects and mechanisms of lycorine in the treatment of multi-organ dysfunction, especially sepsis.

METHODS

Literature searches in electronic databases, such as Web of Science, Science Direct, PubMed, Google Scholar, and Scopus, were performed using 'Lycorine', 'Amaryllidaceae', 'Pharmacology', 'Pharmacokinetics', 'Anti-inflammation', 'Autophagy', 'Apoptosis', 'Anti-microbial and anti-parasitic', 'Antitumor', 'Organ protection', and 'Sepsis' as keywords, the correlated literature was extracted and conducted from the databases mentioned above.

RESULTS

By summarizing the progress made in existing research, we found that the general effects of lycorine involve the regulation of autophagy and the induction of cancer cell apoptosis, and anti-inflammatory, antifungal, antiviral, antimalarial, and antitumor effects; through these pathways, the compound can ameliorate organ damage. In addition, lycorine was found to have an important effect on organ damage in sepsis.

CONCLUSION

Lycorine is a promising natural organ protective agent. This review will provide a new theoretical basis for the treatment of organ protection, especially in sepsis.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia–reperfusion (I–R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I–R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Melatonin Improves Ischemia-Induced Circulation Recovery Impairment in Mice with Streptozotocin-Induced Diabetes by Improving the Endothelial Progenitor Cells Functioning

Patients with diabetes mellitus tend to develop ischemia-related complications and have compromised endothelial progenitor cell (EPC) function. Melatonin protects against ischemic injury, possibly via EPC modulation. We investigated whether melatonin pretreatment could restore EPC function impairment and improve circulation recovery in a diabetic critical limb ischemia mouse model. Under 25 mM high-glucose medium in vitro, EPC proliferation, nitric oxide production, tube formation, and endothelial nitric oxide synthase (eNOS) phosphorylation were significantly suppressed. Hyperglycemia promoted EPC senescence and apoptosis as well as increased reactive oxygen species (ROS) production. Melatonin treatment reversed the harmful effects of hyperglycemia on EPC through adenosine monophosphate–activated protein kinase-related mechanisms to increase eNOS phosphorylation and heme oxygenase-1 expression. In an in-vivo study, after a 4-week surgical induction of hindlimb ischemia, mice with streptozotocin (STZ)-induced diabetes showed significant reductions in new vessel formation, tissue reperfusion, and EPC mobilization in ischemic hindlimbs compared to non-diabetic mice. Mice with STZ-induced diabetes that received melatonin treatment (10 mg/kg/day, intraperitoneal) had significantly improved blood perfusion ratios of ischemic to non-ischemic limb, EPC mobilization, and densities of capillaries. In addition, a murine bone marrow transplantation model to support these findings demonstrated that melatonin stimulated bone marrow-originated EPCs to differentiate into vascular endothelial cells in femoral ligation-induced ischemic muscles. In summary, this study suggests that melatonin treatment augments EPC function along with neovascularization in response to ischemia in diabetic mice. We illustrated the protective effects of melatonin on EPC H2O2 production, senescence, and migration through melatonin receptors and modulating eNOS, AMPK, and HO-1 activities at the cellular level. Thus, melatonin might be used to treat the impairment of EPC mobilization and circulation recuperation in response to ischemic injury caused by chronic hyperglycemia. Additional studies are needed to elucidate the applicability of the results in humans.

Cytoplasmic sequestration of p53 by lncRNA-CIRPILalleviates myocardial ischemia/reperfusion injury

Myocardial ischemia/reperfusion (MI/R) injury is a pathological process that seriously affects the health of patients with coronary artery disease. Long non-coding RNAs (lncRNAs) represents a new class of regulators of diverse biological processes and disease conditions, the study aims to discover the pivotal lncRNA in MI/R injury. The microarray screening identifies a down-regulated heart-enriched lncRNA-CIRPIL (Cardiac ischemia reperfusion associated p53 interacting lncRNA, lncCIRPIL) from the hearts of I/R mice. LncCIRPIL inhibits apoptosis of cultured cardiomyocytes exposed to anoxia/reoxygenation (A/R). Cardiac-specific transgenic overexpression of lncCIRPIL alleviates I/R injury in mice, while knockout of lncCIRPIL exacerbates cardiac I/R injury. LncCIRPIL locates in the cytoplasm and physically interacts with p53, which leads to the cytoplasmic sequestration and the acceleration of ubiquitin-mediated degradation of p53 triggered by E3 ligases CHIP, COP1 and MDM2. p53 overexpression abrogates the protective effects of lncCIRPIL. Notably, the human fragment of conserved lncCIRPIL mimics the protective effects of the full-length lncCIRPIL on cultured human AC16 cells. Collectively, lncCIRPIL exerts its cardioprotective action via sequestering p53 in the cytoplasm and facilitating its ubiquitin-mediated degradation. The study highlights a unique mechanism in p53 signal pathway and broadens our understanding of the molecular mechanisms of MI/R injury.

Melatonin Receptors: A Key Mediator in Animal Reproduction

Melatonin, a hormone produced by the mammalian pineal gland, influences various physiological activities, many of which are related to animal reproduction, including neuroendocrine function, rhythm regulation, seasonal behavior, gonadogenesis, gamete development and maturation, sexual maturation, and thermoregulation. Melatonin exerts beneficial actions mainly via binding with G-protein-coupled receptors (GPCR), termed MT1 and MT2. Melatonin receptors are crucial for mediating animal reproduction. This paper reviews the characteristics of melatonin receptors including MT1 and MT2, as well as their roles in mediating signal transduction and biological effects, with a focus on their function in animal reproduction. In addition, we briefly summarize the developments in pharmacological research regarding melatonin receptors as drug targets. It is expected that this review will provide a reference for further exploration and unveiling of melatonin receptor function in reproductive regulation.

Evidence for the Benefits of Melatonin in Cardiovascular Disease

The pineal gland is a neuroendocrine gland which produces melatonin, a neuroendocrine hormone with critical physiological roles in the circadian rhythm and sleep-wake cycle. Melatonin has been shown to possess anti-oxidant activity and neuroprotective properties. Numerous studies have shown that melatonin has significant functions in cardiovascular disease, and may have anti-aging properties. The ability of melatonin to decrease primary hypertension needs to be more extensively evaluated. Melatonin has shown significant benefits in reducing cardiac pathology, and preventing the death of cardiac muscle in response to ischemia-reperfusion in rodent species. Moreover, melatonin may also prevent the hypertrophy of the heart muscle under some circumstances, which in turn would lessen the development of heart failure. Several currently used conventional drugs show cardiotoxicity as an adverse effect. Recent rodent studies have shown that melatonin acts as an anti-oxidant and is effective in suppressing heart damage mediated by pharmacologic drugs. Therefore, melatonin has been shown to have cardioprotective activity in multiple animal and human studies. Herein, we summarize the most established benefits of melatonin in the cardiovascular system with a focus on the molecular mechanisms of action.

Ozone preconditioning protects rabbit heart against global ischemia-reperfusion injury in vitro by up-regulating HIF-1α

Myocardial ischemia-reperfusion injury (MIRI) is a major factor that leads to cardiac dysfunction in cardiovascular surgery during extracorporeal circulation. Recent studies have found that ozone (O₃) has protective effect on MIRI caused by the anterior descending branch of the ligated left coronary artery. However, whether O₃ preconditioning has the same protective effect on global MIRI and the mechanism underlying this clinical treatment remains elusive. Here, we hypothesized that O₃ preconditioning (O₃P) could protect rabbit heart against global MIRI in vitro by up-regulating HIF-1α. Rabbits were treated intraperitoneally with O₂/O₃ mixture with different concentrations and then injected with YC-1 (inhibitor of HIF-1α) before the establishment of the global MIRI model using the Langendorff isolated heart perfusion apparatus. We investigated the effects of O₃ preconditioning on cardiac systolic function, myocardial infarction, inflammatory response, mitochondrial function, myocardial pathological changes and arrhythmias. We found that the heart with O₃ preconditioning significantly increased HR, LVDP and IL-10 expression, and decreased IL-6 expression, CK-MB, cTnT and cTnI concentration, myocardial infarction area, myocardial pathological injury and the occurrence of ventricular tachycardia and ventricular fibrillation. Meanwhile, the level of HIF-1α was significantly increased. However, after treatment of specific inhibitor of HIF-1α, the protective effect of O₃ preconditioning was reversed completely. Our data indicates that O₃ preconditioning has protective effect on MIRI and this protective effect is positively associated with dosage of O₃. Energy metabolism disorder is the initial stage of MIRI and up-regulation of HIF-1α plays an important role in reducing mitochondrial dysfunction.

SOCS6 Promotes Mitochondrial Fission and Cardiomyocyte Apoptosis and Is Negatively Regulated by Quaking-Mediated miR-19b

Background. Mitochondrial dysfunction and abnormal mitochondrial fission have been implicated in the complications associated with I/R injury as cardiomyocytes are abundant in mitochondria. SOCS6 is known to participate in mitochondrial fragmentation, but its exact involvement and the pathways associated are uncertain. Methods and Results. The expression of SOCS6 was analyzed by western blot in cardiomyocytes under a hypoxia and reoxygenation (H/R) model. A dual-luciferase reporter assay was used to confirm the direct interaction between miR-19b and the 3 ${}^{\prime }$ -UTR of Socs6. In the present study, we found that Socs6 inhibition by RNA interference attenuated H/R-induced mitochondrial fission and apoptosis in cardiomyocytes. A luciferase assay indicated that Socs6 is a direct target of miR-19b. The overexpression of miR-19b decreased mitochondrial fission and apoptosis in vitro. Moreover, the presence of miR-19b reduced the level of SOCS6 and the injury caused by I/R in vivo. There were less apoptotic cells in the myocardium of mice injected with miR-19b. In addition, we found that the RNA-binding protein, Quaking (QK), participates in the regulation of miR-19b expression. Conclusions. Our results indicate that the inhibition of mitochondrial fission through downregulating Socs6 via the QK/miR-19b/Socs6 pathway attenuated the damage sustained by I/R. The QK/miR-19b/Socs6 axis plays a vital role in regulation of mitochondrial fission and cardiomyocyte apoptosis and could form the basis of future research in the development of therapies for the management of cardiac diseases.

New insights into the role of melatonin in diabetic cardiomyopathy

Diabetic cardiovascular complications and impaired cardiac function are considered to be the main causes of death in diabetic patients worldwide, especially patients with type 2 diabetes mellitus (T2DM). An increasing number of studies have shown that melatonin, as the main product secreted by the pineal gland, plays a vital role in the occurrence and development of diabetes. Melatonin improves myocardial cell metabolism, reduces vascular endothelial cell death, reverses microcirculation disorders, reduces myocardial fibrosis, reduces oxidative and endoplasmic reticulum stress, regulates cell autophagy and apoptosis, and improves mitochondrial function, all of which are the characteristics of diabetic cardiomyopathy (DCM). This review focuses on the role of melatonin in DCM. We also discuss new molecular findings that might facilitate a better understanding of the underlying mechanism. Finally, we propose potential new therapeutic strategies for patients with T2DM.

Dexmedetomidine protects cardiomyocytes against hypoxia/reoxygenation injury via multiple mechanisms

Background

Myocardial infarction (MI) is a serious cardiovascular disease associated with myocardial ischemia/reperfusion (I/R) injury. Dexmedetomidine (Dex), an α2‐adrenoceptor agonist, has been reported to protect against I/R injury. We examined the cardioprotective effects of Dex on cardiomyocytes under hypoxia/reoxygenation (H/R) conditions and explored the underlying mechanisms.

Materials and methods

A H/R model was established to mimic the MI injury. The CCK‐8 assay was performed to measure cell viability. Cellular apoptosis was measured using the Annexin V fluorescein isothiocyanate (FITC)‐propidium iodide (PI) staining. The levels of interleukin (IL)‐1α and tumor necrosis factor (TNF)‐α, and the activity of lactate dehydrogenase (LDH) were measured using a commercial enzyme‐linked immunosorbent assay (ELISA) kit. Reactive oxygen species (ROS) were measured using the 2'‐7’ dichlorofluorescein diacetate (DCFH‐DA) staining assay. In addition, the levels of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD), catalase (CAT), and caspase‐3 were measured using a commercial kit. siRNA was used to silence Bcl‐2, catalase, or STAT3. Western blotting was used to measure the change in the levels of proteins.

Results

Dex improved the cell viability and inhibited the inflammatory response in H9c2 cells exposed to H/R treatment. In addition, Dex inhibited apoptosis and alleviated the endoplasmic reticulum (ER) stress and oxidative stress in H9c2 cells under the H/R treatment. Mechanism investigation showed that Dex inhibited the intrinsic pathway of apoptosis. Moreover, Dex enhanced the activation of the JAK2/STAT3 signaling pathway in H/R‐treated H9c2 cells.

Conclusion

Altogether, our findings suggested Dex as a promising therapeutic agent for myocardial I/R.

Melatonin Ameliorates Axonal Hypomyelination of Periventricular White Matter by Transforming A1 to A2 Astrocyte via JAK2/STAT3 Pathway in Septic Neonatal Rats

Background

Astrocyte A1/A2 phenotypes may play differential role in the pathogenesis of periventricular white matter (PWM) damage in septic postnatal rats. This study aimed to determine whether melatonin (MEL) would improve the axonal hypomyelination through shifting A1 astrocytes towards A2.

Methods

One-day-old Sprague-Dawley rats were divided into control, LPS, and LPS+MEL groups. Immunofluorescence was performed to detect C1q, IL-1α, TNF-α, IBA1, GFAP, MAG, C3 and S100A10 immunoreactivity in the PWM of neonatal rats. Electron microscopy was conducted to observe alterations of axonal myelin sheath in the PWM; moreover, myelin protein expression was assessed using in situ hybridization. The effects of MEL on neurological function were evaluated by behavioral tests. In vitro, A1 astrocytes were induced by IL-1α, C1q and TNF-α, and following which the effect of MEL on C3 and S100A10 expression was determined by Western blot and immunofluorescence.

Results

At 1 and 3 days after LPS injection, IBA1⁺ microglia in the PWM were significantly increased in cell numbers which generated excess amounts of IL-1α, TNF-α, and C1q. The number of A1 astrocytes was significantly increased at 7-28d after LPS injection. In rats given MEL treatment, the number of A1 astrocytes was significantly decreased, but that of A2 astrocytes, PLP⁺, MBP⁺ and MAG⁺ cells was increased. By electron microscopy, ultrastructural features of axonal hypomyelination were attenuated by MEL. Furthermore, MEL improved neurological dysfunction as evaluated by different neurological tests. In vitro, MEL decreased the C3 significantly, and upregulated expression of S100A10 in primary astrocytes subjected to IL-1α, TNF-α and C1q treatment. Importantly, JAK2/STAT3 signaling pathway was found to be involved in modulation of A1/A2 phenotype transformation.

Conclusion

MEL effectively alleviates PWMD of septic neonatal rats, which is most likely through modulating astrocyte phenotypic transformation from A1 to A2 via the MT1/JAK2/STAT3 pathway.

Melatonin Reduces Oxidative Stress in the Right Ventricle of Newborn Sheep Gestated under Chronic Hypoxia

Pulmonary arterial hypertension of newborns (PAHN) constitutes a critical condition involving both severe cardiac remodeling and right ventricle dysfunction. One main cause of this condition is perinatal hypoxia and oxidative stress. Thus, it is a public health concern for populations living above 2500 m and in cases of intrauterine chronic hypoxia in lowlands. Still, pulmonary and cardiac impairments in PAHN lack effective treatments. Previously we have shown the beneficial effects of neonatal melatonin treatment on pulmonary circulation. However, the cardiac effects of this treatment are unknown. In this study, we assessed whether melatonin improves cardiac function and modulates right ventricle (RV) oxidative stress. Ten lambs were gestated, born, and raised at 3600 m. Lambs were divided in two groups. One received daily vehicle as control, and another received daily melatonin (1 mg·kg^-1·d^-1) for 21 days. Daily cardiovascular measurements were recorded and, at 29 days old, cardiac tissue was collected. Melatonin decreased pulmonary arterial pressure at the end of the experimental period. In addition, melatonin enhanced manganese superoxide dismutase and catalase (CAT) expression, while increasing CAT activity in RV. This was associated with a decrease in superoxide anion generation at the mitochondria and NADPH oxidases in RV. Finally, these effects were associated with a marked decrease of oxidative stress markers in RV. These findings support the cardioprotective effects of an oral administration of melatonin in newborns that suffer from developmental chronic hypoxia.

MiR-133b regulates oxidative stress injury of trophoblasts in preeclampsia by mediating the JAK2/STAT3 signaling pathway

Preeclampsia (PE) is a pregnancy-related syndrome. Aberrant placental microRNAs (miRNAs) expression might associate with PE, including miR-133b. However, its role in the pathogenesis of preeclampsia remains elusive. Therefore, this study explored the role of miR-133b in oxidative stress injury of trophoblasts in preeclampsia (PE) by mediating the JAK2/STAT3 signaling pathway. Placental tissues were collected from PE patients to detect the expression of miR-133b and JAK2/STAT3. Then, in vitro experiments were performed on human extravillous trophoblast-derived HTR-8/SVneo cells, which were divided into Normal, hypoxia/reoxygenation (H/R), H/R + miR-NC, H/R + miR-133b inhibitor, H/R + JAK2 siRNA and H/R + miR-133b inhibitor + JAK2 siRNA groups. Cell invasion and migration abilities were detected by Transwell and wound healing assays, while apoptosis was detected by flow cytometry. The intracellular oxidative stress levels were also measured. Furthermore, the expression of miR-133b and the JAK2/STAT3 pathway was determined by qRT-PCR and Western blotting. We found that miR-133b was up-regulated, with decreases in JAK2 and p-STAT3/STAT3 in placental tissues of PE patients. Additionally, HTR8/SVneo cells in the H/R group had decreased invasion and migration abilities with increased apoptotic rates and oxidative stress levels. Moreover, the expression of miR-133b was up-regulated with decreases in p-JAK2 and p-STAT3 in H/R-treated HTR8/SVneo cells. These indicators in the H/R + miR-133b inhibitor group were ameliorated in comparison with those in the H/R group but deteriorated in the H/R + JAK2 siRNA group. Moreover, JAK2 siRNA reversed the positive effect of the miR-133b inhibitor on the invasion and migration abilities of trophoblasts. In summary, inhibiting miR-133b may improve oxidative stress injury to promote the migration and invasion of trophoblasts and suppress apoptosis by activating the JAK2/STAT3 pathway.

A novel melatonin-regulated lncRNA suppresses TPA-induced oral cancer cell motility through replenishing PRUNE2 expression

The inhibitory effect of melatonin on cancer cell dissemination is well established, yet the functional involvement of lncRNAs in melatonin signaling remains poorly understood. In this study, we identified a melatonin-attenuated lncRNA acting as a potential melatonin-regulated oral cancer stimulator (MROS-1). Downregulation of MROS-1 by melatonin suppressed TPA-induced oral cancer migration through replenishing the protein expression of prune homolog 2 (PRUNE2), which functioned as a tumor suppressor in oral cancer. Melatonin-mediated MROS-1/PRUNE2 expression and cell motility in oral cancer were regulated largely through the activation of JAK-STAT pathway. In addition, MROS-1, preferentially localized in the nuclei, promoted oral cancer migration in an epigenetic mechanism in which it modulates PRUNE2 expression by interacting with a member of the DNA methylation machinery, DNA methyltransferase 3A (DNMT3A). Higher methylation levels of PRUNE2 promoter were associated with nodal metastases and inversely correlated with PRUNE2 expression in head and neck cancer. Collectively, these findings suggest that MROS-1, serving as a functional mediator of melatonin signaling, could predispose patients with oral cancer to metastasize and may be implicated as a potential target for antimetastatic therapies.

Adiponectin alleviated renal cell apoptosis and inflammation via inactivation of JAK2/STAT3 signal pathway in an acute pyelonephritis mouse model

Background

Acute pyelonephritis (APN), an acute and severe kidney infection, is usually treated with antibiotics. However, APN treatment has become increasingly challenging because of bacterial resistance. Adiponectin, an adipokine, has recently been reported to exhibit profound anti-inflammatory and anti-apoptotic effects. However, the effect of adiponectin on the outcomes of APN treatment remains unclear. In this study, we aimed to investigate the effects of adiponectin on APN and the mechanisms underlying these effects.

Methods

Wild-type C57 mice and adiponectin-knockout (KO) mice were divided into 6 groups: the wild-type control group, the wild-type model group, the wild-type adiponectin intervention group, the KO control group, the KO model group, and the adiponectin-KO intervention group. We measured white blood cell (WBC) and neutrophil counts (NC) using a multispecies hematology analyzer; tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) using enzyme-linked immunosorbent assay (ELISA); blood urea nitrogen (BUN) and serum creatinine (SCr) levels using colorimetry; and the protein levels of JAK2, STAT3, p-JAK2, p-STAT3, Bcl-2, and Bax in renal tissues using western blot analysis. Apoptotic cells were detected using the transferase-mediated dUTP nick end labelling (TUNEL) assay.

Results

Compared to the wild-type mice, the KO mice showed a more severe inflammatory response and kidney damage after Escherichia coli infection. After treatment with exogenous adiponectin injection, the inflammatory response, oxidative stress, and kidney damage were partly alleviated. Adiponectin KO led to JAK2/STAT3 signaling activation, and exogenous adiponectin administration inactivated JAK2/STAT3 signaling in the APN model. APN can lead to an increase in the level of the protein Bax and a decrease in the level of the bcl-2 protein, thereby increasing apoptosis; this effect was inhibited by adiponectin.

Conclusions

Through use of a pyelonephritis mouse model, we demonstrated that adiponectin might alleviate renal cell apoptosis and inflammatory response by inactivating the JAK2/STAT3 signaling pathway.

Melatonin Enhances the Mitochondrial Functionality of Brown Adipose Tissue in Obese-Diabetic Rats

Developing novel drugs/targets remains a major effort toward controlling obesity-related type 2 diabetes (diabesity). Melatonin controls obesity and improves glucose homeostasis in rodents, mainly via the thermogenic effects of increasing the amount of brown adipose tissue (BAT) and increases in mitochondrial mass, amount of UCP1 protein, and thermogenic capacity. Importantly, mitochondria are widely known as a therapeutic target of melatonin; however, direct evidence of melatonin on the function of mitochondria from BAT and the mechanistic pathways underlying these effects remains lacking. This study investigated the effects of melatonin on mitochondrial functions in BAT of Zücker diabetic fatty (ZDF) rats, which are considered a model of obesity-related type 2 diabetes mellitus (T2DM). At five weeks of age, Zücker lean (ZL) and ZDF rats were subdivided into two groups, consisting of control and treated with oral melatonin for six weeks. Mitochondria were isolated from BAT of animals from both groups, using subcellular fractionation techniques, followed by measurement of several mitochondrial parameters, including respiratory control ratio (RCR), phosphorylation coefficient (ADP/O ratio), ATP production, level of mitochondrial nitrites, superoxide dismutase activity, and alteration in the mitochondrial permeability transition pore (mPTP). Interestingly, melatonin increased RCR in mitochondria from brown fat of both ZL and ZDF rats through the reduction of the proton leak component of respiration (state 4). In addition, melatonin improved the ADP/O ratio in obese rats and augmented ATP production in lean rats. Further, melatonin reduced mitochondrial nitrosative and oxidative status by decreasing nitrite levels and increasing superoxide dismutase activity in both groups, as well as inhibited mPTP in mitochondria isolated from brown fat. Taken together, the present data revealed that chronic oral administration of melatonin improved mitochondrial respiration in brown adipocytes, while decreasing oxidative and nitrosative stress and susceptibility of adipocytes to apoptosis in ZDF rats, suggesting a beneficial use in the treatment of diabesity. Further research regarding the molecular mechanisms underlying the effects of melatonin on diabesity is warranted.

MicroRNA-29b reduces myocardial ischemia-reperfusion injury in rats via down-regulating PTEN and activating the Akt/eNOS signaling pathway

Reperfusion may cause injuries to the myocardium in ischemia situation, which is called ischemia/reperfusion (I/R) injury. The study aimed to explore the roles of microRNA-29b (miR-29b) in myocardial I/R injury. Myocardial I/R injury rat model was established. Differentially expressed miRNAs between the model rats and the sham-operated rats were analyzed. miR-29b expression in myocardial tissues was measured. Gain-of-function of miR-29b was performed, and then the morphological changes, infarct size, myocardial function, oxidative stress, and the cell apoptosis in myocardial tissues were detected. The target relation between miR-29b and PTEN was detected through bio-information prediction and dual luciferase reporter gene assay. Activation of Akt/eNOS signaling was detected. H9C2 cells were subjected to hypoxia/reoxygenation treatment to perform in vitro experiments. I/R rats presented severe inflammatory infiltration, increased infarct size and cell apoptosis, increased oxidative stress and decreased myocardial function. miR-29b was downregulated in I/R rats, and up-regulation of miR-29b reversed the above changes. miR-29b directly bound to PTEN, and overexpression of miR-29b reduced PTEN expression level and increased the protein levels of p-Akt/Akt and p-eNOS/eNOS. In vivo results were confirmed in in vitro experiments. This study provided evidence that miR-29b could alleviate the myocardial I/R injury in vivo and in vitro by inhibiting PTEN expression and activating the Akt/eNOS signaling pathway.

Effects of Aspirin on Myocardial Ischemia-Reperfusion Injury in Rats through STAT3 Signaling Pathway

OBJECTIVE

To investigate the role and mechanism of aspirin in myocardial injury induced by myocardial ischemia-reperfusion in rats through STAT3 signaling pathway.

METHODS

Sixty rats were randomly divided into three groups: the sham operation group, MI/R group, and MI/R+aspirin group (aspirin group). The rats in the sham operation group did not ligate the LAD coronary artery, while the aspirin group ligated the LAD coronary artery, which caused the suture to be loosened after 30 minutes ischemia, and 60 mg/kg aspirin was injected into the tail vein 10 minutes before reperfusion. After three hours of reperfusion, the ultrasound system was used to collect hemodynamic parameters, including ejection fraction (EF%), shortening fraction (FS%), and left ventricular end-systolic pressure (LVESP%) and left ventricular end-diastolic pressure (LVEDP%). Finally, the rats were euthanized; then, blood samples were taken for biochemical examination, myocardial tissue was collected, and the left ventricle was used for subsequent experiments. The gene expression levels of Bax and Bcl-2 were detected by PCR. The protein expression levels of Bcl-2, Bax, p-JAK2, total JAK2, p-STAT3, and total STAT3 were detected by Western blot.

RESULTS

Compared with the sham operation group and the aspirin group, the area of myocardial infarction in the MI/R was significantly increased (p < 0.05). In terms of hemodynamic parameters, LVEDP was significantly elevated in the MI/R group. The results of PCR showed that compared with the MI/R group, the mRNA expression of Bax in the aspirin group was significantly decreased, while that of Bcl-2 was significantly increased (p < 0.05). Western blot analysis showed that compared with the MI/R group, aspirin pretreatment significantly increased the expression levels of p-STAT3 and p-JAK2 (p < 0.05).

CONCLUSION

The mechanism of aspirin preconditioning to protect the heart from MI/R injury appears to be related to JAK2/STAT3 and related to the activation of the signaling pathway.

Piceatannol protects against sepsis-induced myocardial dysfunction via direct inhibition of JAK2

Sepsis-induced myocardial dysfunction (SIMD) represents one of the serious complications secondary to sepsis, which is a leading cause of the high mortality rate among septic cases. Subsequent cardiomyocyte apoptosis, together with the uncontrolled inflammatory response, has been suggested to be closely related to SIMD. Piceatannol (PIC) is verified with potent anti-apoptotic and anti-inflammatory effects, but its function and molecular mechanism in SIMD remain unknown so far. This study aimed to explore the potential role and mechanism of action of PIC in resisting SIMD. The interaction of PIC with JAK2 proteins was evaluated by molecular docking, molecular dynamics (MD) simulation and surface plasmon resonance imaging (SPRi). The cecal ligation and puncture-induced septicemia mice and the LPS-stimulated H9C2 cardiomyocytes were prepared as the models in vivo and in vitro, separately. Molecular docking showed that JAK2-PIC complex had the -8.279 kcal/mol binding energy. MD simulations showed that JAK2-PIC binding was stable. SPRi analysis also showed that PIC has a strong binding affinity to JAK2. PIC treatment significantly ameliorated the cardiac function, attenuated the sepsis-induced myocardial loss, and suppressed the myocardial inflammatory responses both in vivo and in vitro. Further detection revealed that PIC inhibited the activation of the JAK2/STAT3 signaling, which was tightly associated with apoptosis and inflammation. Importantly, pre-incubation with a JAK2 inhibitor (AG490) partially blocked the cardioprotective effects of PIC. Collectively, the findings demonstrated that PIC restored the impaired cardiac function by attenuating the sepsis-induced apoptosis and inflammation via suppressing the JAK2/STAT3 pathway both in septic mice and H9C2 cardiomyocytes.

Mitochondrial Oxidative Phosphorylation Function and Mitophagy in Ischaemic/Reperfused Hearts from Control and High-Fat Diet Rats: Effects of Long-Term Melatonin Treatment

PURPOSE

Oxidative stress causes mitochondrial dysfunction in myocardial ischaemia/reperfusion (I/R) as well as in obesity. Mitochondrial depolarization triggers mitophagy to degrade damaged mitochondria, a process important for quality control. The aims of this study were to evaluate (i) the effect of I/R on mitochondrial oxidative phosphorylation and its temporal relationship with mitophagy in hearts from obese rats and their age-matched controls, and (ii) the role of oxidative stress in these processes using melatonin, a free radical scavenger.

METHODS

Male Wistar rats were divided into 4 groups: control (normal diet ± melatonin) and high-fat sucrose diet (HFSD ± melatonin). Rats received melatonin orally (10 mg/kg/day). After 16 weeks, hearts were removed and subjected to 40-min stabilization, and 25-min global ischaemia/10-min reperfusion for preparation of mitochondria. Mitochondrial oxidative phosphorylation was measured polarographically. Western blotting was used for evaluation of PINK1, Parkin, p62/SQSTM1 (p62) and TOM 70. Infarct size was measured using tetrazolium staining.

RESULTS

Ischaemia and reperfusion respectively reduced and increased mitochondrial QO2 (state 3) and the ox-phos rate in both control and HFSD mitochondria, showing no major changes between the groups, while melatonin pretreatment had little effect. p62 as indicator of mitophagic flux showed up- and downregulation of mitophagy by ischaemia and reperfusion respectively, with melatonin having no significant effect. Melatonin treatment caused a significant reduction in infarct size in hearts from both control and diet groups.

CONCLUSIONS

The results suggest that I/R (i) affects mitochondria from control and HFSD hearts similarly and (ii) melatonin-induced cardioprotection is not associated with reversal of mitochondrial dysfunction or changes in the PINK1/Parkin pathway.

Naringenin alleviates myocardial ischemia reperfusion injury by enhancing the myocardial miR-126-PI3K/AKT axis in streptozotocin-induced diabetic rats

Ischemic heart disease (IHD) is a leading cause of death in patients with type 1 diabetes. The key to treating IHD is to restore blood supply to the ischemic myocardium, which inevitably causes myocardial ischemia reperfusion (MI/R) injury. Although naringenin (Nar) prevents MI/R injury, the role of Nar in diabetic MI/R (D-MI/R) injury remains to be elucidated. The PI3K/AKT signaling pathway and microRNA (miR)-126 have previously been shown to serve anti-MI/R injury roles. The present study aimed to investigate the protection of Nar against D-MI/R injury and the role of the miR-126-PI3K/AKT axis. Diabetic rats were treated distilled water or Nar (25 or 50 mg/kg, orally) for 30 days and then exposed to MI/R. The present results revealed that Nar alleviated MI/R injury in streptozotocin (STZ)-induced diabetic rats, as shown below: the reduction myocardial enzymes levels was measured using spectrophotometry, the increase of cardiac viability was detected by MTT assay, the inhibition of myocardial oxidative stress was measured using spectrophotometry and the enhancement of cardiac function were recorded using a hemodynamic monitoring system. Furthermore, Nar upregulated the myocardial miR-126-PI3K/AKT axis in D-MI/R rats. These results indicated that Nar alleviated MI/R injury through upregulating the myocardial miR-126-PI3K/AKT axis in STZ-induced diabetic rats. The current findings revealed that Nar, as an effective agent against D-MI/R injury, may provide an effective approach in the management of diabetic IHD.

Insights into the Effects of Dietary Omega-6/Omega-3 Polyunsaturated Fatty Acid (PUFA) Ratio on Oxidative Metabolic Pathways of Oncological Bone Disease and Global Health

Various nutrients have been designated as antioxidants, with a possible effect on diseases like cancer. This is partly due to their effect on prostaglandins, thereby affecting local pathological metabolic acidosis. This paper aims to summarize the culprit pathophysiological mechanisms involved, with a focus on the bone microenvironment. The omega- 6/omega-3 PUFA ratio is particularly investigated for its antioxidative effects, countering these pathways to fight the disease. This feature is looked at concerning its impact on health in general, with a particular focus on malignant bone metastasis.

Activation of Paraventricular Melatonin Receptor 2 Mediates Melatonin-Conferred Cardioprotection Against Myocardial Ischemia/Reperfusion Injury

Previous studies have shown that melatonin (Mel) can effectively ameliorate myocardial ischemia/reperfusion (MI/R) injury, but the mechanism is yet to be fully elucidated. Mel receptors are expressed in the paraventricular nucleus (PVN), which is also involved in regulating cardiac sympathetic nerve activity. The aim of this study was to examine whether Mel receptors in the PVN are involved in the protective effects of Mel against MI/R injury. The results of quantitative polymerase chain reaction, western blot, and immunofluorescence assays indicated that Mel receptor 2 (MT2) expression in the PVN was upregulated after MI/R. Intraperitoneal administration of Mel significantly improved post-MI/R cardiac function and reduced the infarct size, whereas shRNA silencing of MT2 in the PVN partially blocked this effect. Intraperitoneal administration of Mel reduced sympathetic nerve overexcitation caused by MI/R, whereas shRNA silencing of MT2 in the PVN partially diminished this effect. Furthermore, enzyme-linked immunosorbent assay and western blot results indicated that intraperitoneal administration of Mel lowered the levels of inflammatory cytokines in the PVN after MI/R injury, whereas the application of sh-MT2 in the PVN reduced this effect of Mel. Mel significantly reduced the levels of NF-κB after astrocyte oxygen and glucose deprivation/reoxygenation injury, and this effect was offset when MT2 was silenced. The above experimental results suggest that MT2 in the PVN partially mediated the protective effects of Mel against MI/R injury, and its underlying mechanisms may be related to postactivation amelioration of PVN inflammation and reduction of cardiac sympathetic nerve overexcitation.

Klotho overexpression suppresses apoptosis by regulating the Hsp70/Akt/Bad pathway in H9c2(2-1) cells

Early reperfusion is the most effective and important treatment for acute myocardial infarction. However, reperfusion therapy often leads to a certain degree of myocardial damage. The aim of the present study was to identify the role of klotho, and the molecular mechanism underlying its effects, in myocardial damage using a model of myocardial hypoxia injury. Hypoxia/reoxygenation (H/R) was used to mimic ischemia/reperfusion (I/R) injury in vitro. The expression and distribution of klotho in H9c2(2-1) cells was observed by fluorogenic scanning, and the apoptotic rate was determined by Annexin V-FITC/propidium iodide dual staining. Cell viability was determined by MTT assay, and caspase-3, cleaved caspase-3, Bcl-2, Bax, heat shock protein (Hsp) 70 and Akt levels were assessed by western blotting. A lactate dehydrogenase test was performed to determine the degree of H9c2(2-1) cell damage. The results revealed that klotho was primarily located in the cytoplasm of H9c2(2-1) cells. Klotho overexpression markedly suppressed H/R-induced H9c2(2-1) cell apoptosis. Furthermore, cell viability increased, and injury decreased in response to klotho. Klotho also suppressed the activation of caspase-3, upregulated Bcl2 and decreased Bax levels following H/R injury, as well as alleviating H/R injury by upregulating the expression of Hsp70 and increasing the levels of phosphorylated (p-)Akt and Bad. In conclusion, these results indicate that klotho suppressed H/R-induced H9c2(2-1) cell apoptosis by regulating the levels of Hsp70, p-Akt and p-Bad, which suggest that klotho could be a novel agent for the treatment of coronary disease.

Exercise-induced peptide EIP-22 protect myocardial from ischaemia/reperfusion injury via activating JAK2/STAT3 signalling pathway

Recent studies have revealed that exercise has myocardial protective effects, but the exact mechanism remains unclear. Studies have increasingly found that peptides play a protective role in myocardial ischaemia‐reperfusion (I/R) injury. However, little is known about the role of exercise‐induced peptides in myocardial I/R injury. To elucidate the effect of exercise‐induced peptide EIP‐22 in myocardial I/R injury, we first determined the effect of EIP‐22 on hypoxia/reperfusion (H/R)‐ or H₂O₂‐induced injury via assessing cell viability and lactate dehydrogenase (LDH) level. In addition, reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) was assessed by fluorescence microscope. Meanwhile, Western blot and TUNEL methods were used to detect apoptosis level. Then, we conducted mice I/R injury model and verified the effect of EIP‐22 by measuring cardiac function, evaluating heart pathology and detecting serum LDH, CK‐MB and cTnI level. Finally, the main signalling pathway was analysed by RNA‐seq. In vitro, EIP‐22 treatment significantly improved cells viabilities and MMP and attenuated the LDH, ROS and apoptosis level. In vivo, EIP‐22 distinctly improved cardiac function, ameliorated myocardial infarction area and fibrosis and decreased serum LDH, CK‐MB and cTnI level. Mechanistically, JAK/STAT signalling pathway was focussed by RNA‐seq and we confirmed that EIP‐22 up‐regulated the expression of p‐JAK2 and p‐STAT3. Moreover, AG490, a selective inhibitor of JAK2/STAT3, eliminated the protective roles of EIP‐22. The results uncovered that exercise‐induced peptide EIP‐22 protected cardiomyocytes from myocardial I/R injury via activating JAK2/STAT3 signalling pathway and might be a new candidate molecule for the treatment of myocardial I/R injury.