Myocardial ischemia reperfusion injury is alleviated by curcumin-peptide hydrogel via upregulating autophagy and protecting mitochondrial function

Protective effects of tetramethylpyrazine on myocardial ischemia/reperfusion injury involve NLRP3 inflammasome suppression by autophagy activation

Tetramethylpyrazine (TMP) belongs to the active ingredients of the traditional Chinese medicine Chuanxiong, which has a certain protective effect in myocardial ischemia-reperfusion (I/R) injury. It can improve postoperative cardiac function and alleviate ventricular remodeling in acute myocardial infarction patients. However, its specific protective mechanism is still unclear. In this study, a certain concentration of TMP was introduced into I/R mice or H9C2 cells after oxygen-glucose deprivation/reoxygenation (OGD/R) treatment to observe the effects of TMP on cardiomyocyte activity, cytotoxicity, apoptosis, autophagy, pyroptosis, and NLRP3 inflammasome activation. The results displayed that TMP intervention could reduce OGD/R and I/R-induced cardiomyocyte apoptosis, accelerate cellular activity and autophagy levels, and ameliorate myocardial tissue necrosis in I/R mice in a dose-dependent manner. Further, TMP prevented the formation of NLRP3 inflammasomes to suppress pyroptosis by increasing the level of cardiomyocyte autophagy after I/R and OGD/R modelling, the introduction of chloroquine to suppress autophagic activity in vivo and in vitro was further analyzed to confirm whether TMP inhibits NLRP3 inflammasome activation and pyroptosis by increasing autophagy, and we found the inhibitory effect of TMP on NLRP3 inflammasomes and its protective effect against myocardial injury were blocked when autophagy was inhibited with chloroquine. In conclusion, this experiment demonstrated that TMP unusually attenuated I/R injury in mice, and this protective effect was achieved by inhibiting the activation of NLRP3 inflammasomes through enhancing autophagic activity.

Intramyocardial delivery of injectable hydrogel with arctigenin alleviated myocardial ischemia-reperfusion injury in rats

Arctigenin belongs to a major bioactive component of Fructus arctii and has been found with cardioprotective effects on rats with ischemia‒reperfusion (I/R) injury. The application of arctigenin is limited due to poor water solubility and low bioavailability. Hydrogel drug delivery systems can improve the efficacy and safety of drugs, increase drug utilization, and reduce side effects. We hypothesized that hydrogels containing arctigenin would facilitate the effect of arctigenin and alleviate I/R injury in the rat heart. Presently, adult Sprague-Dawley (SD) rats were subjected to 1 h of I/R injury, then hydrogels comprising arctigenin were implanted into the myocardium of rats. Triphenyl tetrazolium chloride staining, hematoxylin-eosin staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining and Western blot were performed for evaluating the infarct size, histopathological, and vital protein alterations of hearts. It was discovered that the hydrogel combined with arctigenin abated apoptosis and reduced infarct size. In addition, the results of echocardiography and Masson staining suggested that the hydrogel with arctigenin improved cardiac function, restrained myocardial fibrosis, and activated AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). Collectively, the injectable hydrogel delivery system enhances the effect of arctigenin, which may play a protective role in I/R injury by activating AMPK and SIRT1.

Dexmedetomidine alleviates Hypoxia/reoxygenation-induced mitochondrial dysfunction in cardiomyocytes via activation of Sirt3/Prdx3 pathway

BACKGROUND

Myocardial ischemia/reperfusion injury (MIRI) seriously threatens the health of people. The mitochondrial dysfunction in cardiomyocytes can promote the progression of MIRI. Dexmedetomidine (Dex) could alleviate the myocardial injury, which was known to reverse mitochondrial dysfunction in lung injury. However, the function of Dex in mitochondrial dysfunction during MIRI remains unclear.

OBJECTIVE

To assess the function of Dex in mitochondrial dysfunction during MIRI.

METHODS

To investigate the function of Dex in MIRI, H9C2 cells were placed in condition of hypoxia/reoxygenation (H/R). CCK8 assay was performed to test the cell viability, and the mitochondrial membrane potential was evaluated by JC-1 staining. In addition, the binding relationship between Sirt3 and Prdx3 was explored by Co-IP assay. Furthermore, the protein expressions were examined using western blot.

RESULTS

Dex could abolish H/R-induced mitochondrial dysfunction in H9C2 cells. In addition, H/R treatment significantly inhibited the expression of Sirt3, while Dex partially restored this phenomenon. Knockdown of Sirt3 or Prdx3 obviously reduced the protective effect of Dex on H/R-induced mitochondrial injury. Meanwhile, Sirt3 could enhance the function of Prdx3 via deacetylation of Prdx3.

CONCLUSION

Dex was found to attenuate H/R-induced mitochondrial dysfunction in cardiomyocytes via activation of Sirt3/Prdx3 pathway. Thus, this study might shed new lights on exploring new strategies for the treatment of MIRI.

Peptide Supramolecular Self-Assembly: Regulatory Mechanism, Functional Properties, and Its Application in Foods

Peptide self-assembly, due to its diverse supramolecular nanostructures, excellent biocompatibility, and bright application prospects, has received wide interest from researchers in the fields of biomedicine and green life technology and the food industry. Driven by thermodynamics and regulated by dynamics, peptides spontaneously assemble into supramolecular structures with different functional properties. According to the functional properties derived from peptide self-assembly, applications and development directions in foods can be found and explored. Therefore, in this review, the regulatory mechanism is elucidated from the perspective of self-assembly thermodynamics and dynamics, and the functional properties and application progress of peptide self-assembly in foods are summarized, with a view to more adaptive application scenarios of peptide self-assembly in the food industry.

Maintenance of cathepsin D-dependent autophagy-lysosomal function protects against cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion(I/R) induced-cardiac vascular endothelial injury is an important pathological process that appears in the early stage of cardiac I/R injury. The autophagy-lysosomal pathway is essential for the maintenance of cellular homeostasis. However, in cardiac I/R injury, the role of the autophagy-lysosomal pathway is controversial. The present study aimed to use oxygen-glucose deprivation/oxygen-glucose resupply(OGD/OGR) in human coronary artery endothelial cells(HCAECs) with I/R injury to assess the role of the autophagy-lysosomal pathway in I/R-induced endothelial injury. The results revealed lysosomal dysfunction and impaired autophagic flux in endothelial cells exposed to OGD/OGR. Meanwhile, our data showed that the levels of cathepsin D(CTSD) decreased time-dependently. Knockdown of CTSD caused lysosomal dysfunction and impaired autophagic flux. Conversely, restoration of CTSD levels protected HCAECs against OGD/OGR induced-defects in autophagy-lysosomal function and cellular damage. Our findings indicated that I/R induced-impaired autophagic flux, rather than excessive autophagic initiation, mediates endothelial cells injury. The maintenance of autophagy-lysosomal function is critical to protect endothelial cells against I/R injury, and CTSD is a key regulator. Thus, strategies focused on restoring CTSD function are potentially novel treatments for cardiac reperfusion injury.

Protective effects of curcumin on ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

CREB1 and PPAR-α/γ Pathways in Hepatic Ischemia/Reperfusion: Route for Curcumin to Hepatoprotection

Background

Hepatic ischemia/reperfusion injury is a major problem that can exacerbate complications, particularly in liver transplantations.

Objectives

This study aimed to investigate the cellular mechanisms of ischemia/reperfusion injury and hepatoprotection by curcumin.

Methods

Wistar albino rats were divided into four groups as Control, Sham, I/R, and Cur+I/R. Hepatic ischemia/reperfusion was induced in I/R and Cur+I/R animals, the latter of which was also given 50 mg/kg/day of curcumin for 14 days. Liver aminotransferases and the transcription regulators of inflammation (RelA, IκB, PPAR-α, PPAR-γ, CREB1) were examined along with the histological examination.

Results

Hepatic ischemia/reperfusion was found to disrupt hepatic microstructure and downregulate PPAR-α, PPAR-γ, and CREB1 transcripts. Curcumin supplementation in hepatic ischemia/reperfusion recovered the structural organization and promoted the hepatocyte regeneration while increasing expressions of PPARs and CREB1. RelA and IκB were found unaltered, possibly due to the crosstalk between targeted transcripts by ischemia/reperfusion and curcumin.

Conclusions

In sum, PPAR-α/γ and CREB1 were involved in hepatic ischemia/reperfusion and, moreover, were detected to be stimulated by curcumin. PPAR and CREB pathways were found to provide a route to hepatoprotection for curcumin supplementation as evidenced by the microstructural improvement.

Improvement of Myocardial Cell Injury by miR-199a-3p/mTOR Axis through Regulating Cell Apoptosis and Autophagy

Background

Myocardial ischemia-reperfusion injury (MIRI) is characterized by its high incidence rate and mortality. miR-199a-3p is thought to be strongly linked with the development of some myocardial diseases, but the influence of miR-199a-3p in MIRI remains unclear.

Methods

AC16 cells were used. The concentrations of mammalian target of rapamycin (mTOR), light chain 3 II/light chain 3 I, and Beclin-1 were detected with western blotting and qRT-PCR. The binding site between mTOR and miR-199a-3p was evaluated via luciferase report assay. Cell apoptosis was evaluated through flow cytometry.

Results

Knockdown of miR-199a-3p accelerated the myocardial cell injury after L-oxygen treatment. Increased expression of mTOR and suppressed autophagy were observed after knockdown of miR-199a-3p. Knockdown of miR-199a-3p or overexpression of mTOR greatly aggravated cell injury through inhibiting autophagy. Conclusions. This study might be helpful for the therapeutic method of MIRI through by regulating miR-199a-3p/mTOR.

Antioxidant Cardioprotection against Reperfusion Injury: Potential Therapeutic Roles of Resveratrol and Quercetin

Ischemia-reperfusion myocardial damage is a paradoxical tissue injury occurring during percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI) patients. Although this damage could account for up to 50% of the final infarct size, there has been no available pharmacological treatment until now. Oxidative stress contributes to the underlying production mechanism, exerting the most marked injury during the early onset of reperfusion. So far, antioxidants have been shown to protect the AMI patients undergoing PCI to mitigate these detrimental effects; however, no clinical trials to date have shown any significant infarct size reduction. Therefore, it is worthwhile to consider multitarget antioxidant therapies targeting multifactorial AMI. Indeed, this clinical setting involves injurious effects derived from oxygen deprivation, intracellular pH changes and increased concentration of cytosolic Ca²⁺ and reactive oxygen species, among others. Thus, we will review a brief overview of the pathological cascades involved in ischemia-reperfusion injury and the potential therapeutic effects based on preclinical studies involving a combination of antioxidants, with particular reference to resveratrol and quercetin, which could contribute to cardioprotection against ischemia-reperfusion injury in myocardial tissue. We will also highlight the upcoming perspectives of these antioxidants for designing future studies.

Research on natural products from traditional Chinese medicine in the treatment of myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a complicated pathologic process that involves multiple factors including oxidative stress (free radical damage), inflammatory response, calcium overloading, and apoptosis in cardiomyocytes. According to Traditional Chinese Medicine (TCM), MIRI belongs to the categories of "chest numbness", "palpitations" and "angina pectoris". Present data indicate that the application of TCM in myocardial ischemia-reperfusion injury is promising and continues to attract research attention. While the efficacy of Chinese herbal medicine has been well-proven, the underlying molecular mechanisms remain elusive. The common proven mechanisms of Chinese herbal medicine in the treatment of MIRI include regulating lipid metabolism, protecting mitochondria, and improving energy metabolism, attenuating calcium (Ca²⁺) overload, scavenging oxygen free radicals, inhibiting apoptosis, and reducing autophagy. Others are the regulation of inflammatory cytokine expressions and healing of inflammatory lesions, modulation of cell signaling pathways, improvement of endothelial cell function, and protection of myocardial cells. In this review, we highlight recent studies that focus on elucidating these molecular mechanisms and the therapeutic effects of natural compounds deriving from TCM in MIRI, to ascertain the research progress made and the prospects in this field.

Protective Effects of Curcumin in Cardiovascular Diseases—Impact on Oxidative Stress and Mitochondria

Cardiovascular diseases (CVDs) contribute to a large part of worldwide mortality. Similarly, two of the major risk factors for these diseases, aging and obesity, are also global problems. Aging, the gradual decline of body functions, is non-modifiable. Obesity, a modifiable risk factor for CVDs, also predisposes to type 2 diabetes mellitus (T2DM). Moreover, it affects not only the vasculature and the heart but also specific fat depots, which themselves have a major impact on the development and progression of CVDs. Common denominators of aging, obesity, and T2DM include oxidative stress, mitochondrial dysfunction, metabolic abnormalities such as altered lipid profiles and glucose metabolism, and inflammation. Several plant substances such as curcumin, the major active compound in turmeric root, have been used for a long time in traditional medicine and for the treatment of CVDs. Newer mechanistic, animal, and human studies provide evidence that curcumin has pleiotropic effects and attenuates numerous parameters which contribute to an increased risk for CVDs in aging as well as in obesity. Thus, curcumin as a nutraceutical could hold promise in the prevention of CVDs, but more standardized clinical trials are required to fully unravel its potential.

Ferulic Acid Alleviates Myocardial Ischemia Reperfusion Injury Via Upregulating AMPKα2 Expression-Mediated Ferroptosis Depression

ABSTRACT

Ferroptosis, a recently discovered form of regulated cell death that is characterized by iron accumulation and excessive reactive oxygen species generation, has been favored by most researchers. Increasing evidence suggest that ferulic acid (FA) could exert marked effects to myocardial ischemia reperfusion (I/R) injury, although the understanding of its molecular mechanism is still limited. In our study, the myocardial I/R injury model was established to explore the relationship between I/R injury and ferroptosis. First, we successfully constructed myocardial I/R injury model with changes in ST segment, increased creatine phosphokinase, lactate dehydrogenase activities, and N-Terminal Pro Brain Natriuretic Peptide content, and a significantly larger infarct size. Then, the increased levels of the Ptgs2 mRNA, Fe2+ accumulation, and a decreased reduced glutathione/oxidized glutathione disulfide ratio were detected in ischemia-reperfusion-injured heart, which is highly consistent with ferroptosis. However, these effects were significantly improved after FA treatment. Based on these results, FA increased the activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase, decreased the malondialdehyde level, ameliorated the production of reactive oxygen species, and promoted the generation of adenosine triphosphate. These effects of FA are similar to those of the ferroptosis inhibitor ferrostatin-1. Upregulation of AMPKα2 and Glutathione Peroxidase 4 expression were also observed in the FA group. Compound C, a specific Adenosine 5'-monophosphate (AMP)-activated protein kinase inhibitor, significantly blocked the protective effect of FA. These findings underlined that FA inhibits ferroptosis by upregulating the expression of AMPKα2 and serves as a cardioprotective strategy.

Combating Ischemia-Reperfusion Injury with Micronutrients and Natural Compounds during Solid Organ Transplantation: Data of Clinical Trials and Lessons of Preclinical Findings

Although extended donor criteria grafts bear a higher risk of complications such as graft dysfunction, the exceeding demand requires to extent the pool of potential donors. The risk of complications is highly associated with ischemia-reperfusion injury, a condition characterized by high loads of oxidative stress exceeding antioxidative defense mechanisms. The antioxidative properties, along with other beneficial effects like anti-inflammatory, antiapoptotic or antiarrhythmic effects of several micronutrients and natural compounds, have recently emerged increasing research interest resulting in various preclinical and clinical studies. Preclinical studies reported about ameliorated oxidative stress and inflammatory status, resulting in improved graft survival. Although the majority of clinical studies confirmed these results, reporting about improved recovery and superior organ function, others failed to do so. Yet, only a limited number of micronutrients and natural compounds have been investigated in a (large) clinical trial. Despite some ambiguous clinical results and modest clinical data availability, the vast majority of convincing animal and in vitro data, along with low cost and easy availability, encourage the conductance of future clinical trials. These should implement insights gained from animal data.