Honokiol post-treatment ameliorates myocardial ischemia/reperfusion injury by enhancing autophagic flux and reducing intracellular ROS production

Lactate Contributes to Remote Ischemic Preconditioning-Mediated Protection Against Myocardial Ischemia Reperfusion Injury by Facilitating Autophagy via the AMPK-Mammalian Target of Rapamycin-Transcription Factor EB-Connexin 43 Axis

Remote ischemic preconditioning (RIPC) exerts a protective role on myocardial ischemia/reperfusion (I/R) injury by the release of various humoral factors. Lactate is a common metabolite in ischemic tissues. Nevertheless, little is known about the role lactate plays in myocardial I/R injury and its underlying mechanism. This investigation revealed that RIPC elevated the level of lactate in blood and myocardium. Furthermore, AZD3965, a selective monocarboxylate transporter 1 inhibitor, and 2-deoxy-d-glucose, a glycolysis inhibitor, mitigated the effects of RIPC-induced elevated lactate in the myocardium and prevented RIPC against myocardial I/R injury. In an in vitro hypoxia/reoxygenation model, lactate markedly mitigated hypoxia/reoxygenation-induced cell damage in H9c2 cells. Meanwhile, further studies suggested that lactate contributed to RIPC, rescuing I/R-induced autophagy deficiency by promoting transcription factor EB (TFEB) translocation to the nucleus through activating the AMPK-mammalian target of rapamycin (mTOR) pathway without influencing the phosphatidylinositol 3-kinase-Akt pathway, thus reducing cardiomyocyte damage. Interestingly, we also found that lactate up-regulated the mRNA and protein expression of connexin 43 (CX43) by facilitating the binding of TFEB to CX43 promoter in the myocardium. Functionally, silencing of TFEB attenuated the protective effect of lactate on cell damage, which was reversed by overexpression of CX43. Further mechanistic studies suggested lactate facilitated CX43-regulated autophagy via the AMPK-mTOR-TFEB signaling pathway. Collectively, our research demonstrates that RIPC protects against myocardial I/R injury through lactate-mediated myocardial autophagy via the AMPK-mTOR-TFEB-CX43 axis.

Silver Nanoparticles Loaded With Oleuropein Alleviates LPS-Induced Acute Lung Injury by Modulating the TLR4/P2X7 Receptor-Mediated Inflammation and Apoptosis in Rats

Toll-like receptor 4 (TLR-4) ligands were initially shown to be the source of lipopolysaccharide (LPS), a gram-negative bacterium's cell wall immunostimulatory component. Oxidative stress, apoptosis, and inflammation are all potential effects of LPS treatment on the lungs. By triggering oxidative stress and inflammation, these negative effects could be avoided. Robust flavonoid oleuropein (OLE) exhibits anti-inflammatory, antiproliferative, and antioxidative properties. A nanodelivery system could improve its low bioavailability, making it more effective and useful in treating chronic human ailments. This study evaluates the effects of AgNP-loaded OLE on LPS-induced lung injury in rats in terms of TLR4/P2X7 receptor-mediated inflammation and apoptosis. Forty-eight male albino rats were randomly divided into eight groups. Drugs were administered to the groups in the doses specified as follows: Control, LPS (8 mg/kg ip), OLE (50 mg/kg) AgNPs (100 mg/kg), OLE + AgNPs (50 mg/kg), LPS + OLE (oleuropein 50 mg/kg ig + LPS 8 mg/kg ip), LPS + AgNPs (AgNPs 100 mg/kg ig + LPS 8 mg/kg ip), and LPS + OLE + AgNPs (OLE + AgNPs 50 mg/kg + LPS 8 mg/kg ip). After the applications, the rats were decapitated under appropriate conditions, and lung tissues were obtained. Oxidative stress (SOD, MDA, and GSH), and inflammation (IL-6, IL-1β, TNF-α, Nrf2, P2X7R, AKT, and TLR4) parameters were evaluated in the obtained lung tissues. Additionally, histopathology studies were performed on lung tissue samples. The data obtained were evaluated by comparison between groups. Both OLE and OLE + AgNPs showed potential in reducing oxidative stress, inflammation, and apoptosis (p < 0.05). These findings were supported by histopathological analysis, which revealed that tissue damage was reduced in OLE and OLE + AgNPs-treated groups. According to the results, LPS-induced lung injury can be reduced by using nanotechnology and producing OLE + AgNP.

Queen bee acid pretreatment attenuates myocardial ischemia/reperfusion injury by enhancing autophagic flux

Queen bee acid (QBA), which is exclusively found in royal jelly, has anti-inflammatory, antihypercholesterolemic, and antiangiogenic effects. A recent study demonstrated that QBA enhances autophagic flux in the heart. Considering the significant role of autophagy in the development of myocardial ischemia/reperfusion (I/R) injury, we investigated the effect of pretreatment with QBA on myocardial damage. In an in vivo model, left coronary artery blockage for 30 min and reperfusion for 2 h were used to induce myocardial I/R. In an in vitro model, neonatal rat cardiomyocytes (NRCs) were exposed to 3 h of hypoxia and 3 h of reoxygenation (H/R). Our results showed that pretreatment with QBA increased the cell viability of cardiomyocytes exposed to H/R in a dose-dependent manner, and the best protective concentration of QBA was 100 μM. Next, we noted that QBA pretreatment (24h before H/R) enhanced autophagic flux and attenuated mitochondrial damage, cardiac oxidative stress and apoptosis in NRCs exposed to H/R injury, and these effects were weakened by cotreatment with the autophagy inhibitor bafilomycin A1 (Baf). In addition, similar results were observed when QBA (10 mg/kg) was injected intraperitoneally into I/R mice 30 min before ischemia. Compared to mice subjected to I/R alone, those treated with QBA had decreased myocardial infarct area and increased cardiac function, whereas, these effects were partly reversed by Baf. Notably, in NRCs exposed to H/R, tandem fluorescent mRFP-GFP-LC3 assays indicated increased autophagosome degradation due to the increase in autophagic flux upon QBA treatment, but coinjection of Baf blocked autophagic flux. In this investigation, no notable adverse effects of QBA were detected in either cellular or animal models. Our findings suggest that QBA pretreatment mitigates myocardial I/R injury by eliminating dysfunctional mitochondria and reducing reactive oxygen species via promoting autophagic flux.

Pharmacological features, health benefits and clinical implications of honokiol

Honokiol (HNK) is a natural polyphenolic compound extracted from the bark and leaves of Magnolia grandiflora. It has been traditionally used as a medicinal compound to treat inflammatory diseases. HNK possesses numerous health benefits with a minimal level of toxicity. It can cross the blood-brain barrier and blood-cerebrospinal fluid, thus having significant bioavailability in the neurological tissues. HNK is a promising bioactive compound possesses neuroprotective, antimicrobial, anti-tumorigenic, anti-spasmodic, antidepressant, analgesic, and antithrombotic features . HNK can prevent the growth of several cancer types and haematological malignancies. Recent studies suggested its role in COVID-19 therapy. It binds effectively with several molecular targets, including apoptotic factors, chemokines, transcription factors, cell surface adhesion molecules, and kinases. HNK has excellent pharmacological features and a wide range of chemotherapeutic effects, and thus, researchers have increased interest in improving the therapeutic implications of HNK to the clinic as a novel agent. This review focused on the therapeutic implications of HNK, highlighting clinical and pharmacological features and the underlying mechanism of action.Communicated by Ramaswamy H. Sarma.

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.

Honokiol attenuates mitochondrial fission and cell apoptosis by activating Sirt3 in intracerebral hemorrhage

BACKGROUND

Sirtuin-3 (Sirt3) has been documented to protect against mitochondrial dysfunction and apoptosis. Honokiol (HKL) is a Sirt3 pharmacological activator with reported neuroprotective effects in multiple neurological disorders. The present study aimed to explore the neuroprotective effects of HKL and the role of Sirt3 following intracerebral hemorrhage (ICH).

METHODS

An in vivo ICH model in rats was established by injecting autologous blood into the right basal ganglia. PC12 cells were stimulated with hemin. For the in vivo investigation, the modified Neurological Severity Scores and the Morris water maze test were performed to assess neurological deficits. Hematoxylin-Eosin and Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining were employed to evaluate the histopathology and apoptosis. Immunohistochemical staining was used to investigate the expression of Sirt3. Adenosine triphosphate (ATP) levels were quantified to assess mitochondrial dysfunction. Cell counting kit-8, lactate dehydrogenase assay, and flow cytometry were used to analyze cell vitality and apoptosis in vitro. Immunofluorescence staining was performed to observe mitochondrial morphology and dynamin-related protein 1 (Drp1) localization to mitochondria. Western blot was applied to quantify the expression of Sirt3, Bax, Bcl-2, cleaved-caspase-3, Drp1, phosphorylation of Drp1 at serine-616, and phosphorylation of Drp1 at serine-637 in vivo and in vitro.

RESULTS

HKL treatment alleviated neurological deficits, attenuated the histopathological damage and cell apoptosis, and restored the decreased ATP levels in ICH rats. HKL improved cell survival rate, reduced cell apoptosis, and inhibited mitochondrial fission in PC12 cells. Moreover, both in vivo and in vitro models showed increased phosphorylation of Drp1 at Ser616, and reduced phosphorylation of Drp1 at Ser637. Meanwhile, immunofluorescence co-localization analysis revealed that hemin increased the overlap of Drp1 and mitochondria in PC12 cells. The phosphorylation and mitochondrial translocation of Drp1 were effectively reversed by HKL treatment. Importantly, the selective Sirt3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine suppressed these effects.

CONCLUSION

Our findings demonstrated that HKL ameliorated ICH-induced apoptosis and mitochondrial fission by Sirt3, suggesting that HKL has immense prospects for the treatment of ICH.

Remote ischemic preconditioning protects against spinal cord ischemia-reperfusion injury in mice by activating NMDAR/AMPK/PGC-1α/SIRT3 signaling

BACKGROUND

To study the protective effects of delayed remote ischemic preconditioning (RIPC) against spinal cord ischemia-reperfusion injury (SCIRI) in mice and determine whether SIRT3 is involved in this protection and portrayed its upstream regulatory mechanisms.

METHODS

In vivo, WT or SIRT3 global knockout (KO) mice were exposed to right upper and lower limbs RIPC or sham ischemia. After 24 h, the abdominal aorta was clamped for 20 min, then re-perfused for 3 days. The motor function of mice, number of Nissl bodies, apoptotic rate of neurons, and related indexes of oxidative stress in the spinal cord were measured to evaluate for neuroprotective effects. The expression and correlation of SIRT3 and NMDAR were detected by WB and immunofluorescence. In vitro, primary neurons were exacted and OGD/R was performed to simulate SCIRI in vivo. Neuronal damage was assessed by observing neuron morphology, detecting LDH release ratio, and flow cytometry to analyze the apoptosis. MnSOD and CAT enzyme activities, GSH and ROS level were also measured to assess neuronal antioxidant capacity. NMDAR-AMPK-PGC-1α signaling was detected by WB to portray upstream regulatory mechanisms of RIPC regulating SIRT3.

RESULTS

Compared to the SCIRI mice without RIPC, mice with RIPC displayed improved motor function recovery, a reduced neuronal loss, and enhanced antioxidant capacity. To the contrary, the KO mice did not exhibit any effect of RIPC-induced neuroprotection. Similar results were observed in vitro. Further analyses with spinal cord tissues or primary neurons detected enhanced MnSOD and CAT activities, as well as increased GSH level but decreased MDA or ROS production in the RIPC + I/R mice or NMDA + OGD/R neurons. However, these changes were completely inhibited by the absence of SIRT3. Additionally, NMDAR-AMPK-PGC-1α signaling was activated to upregulate SIRT3 levels, which is essential for RIPC-mediated neuroprotection.

CONCLUSIONS

RIPC enhances spinal cord ischemia tolerance in a SIRT3-dependent manner, and its induced elevated SIRT3 levels are mediated by the NMDAR-AMPK-PGC-1α signaling pathway. Combined therapy targeting SIRT3 is a promising direction for treating SCIRI.

Targeting ferroptosis: a novel insight against myocardial infarction and ischemia-reperfusion injuries

Ferroptosis, a newly discovered form of regulated cell death dependent on iron and reactive oxygen species, is mainly characterized by mitochondrial shrinkage, increased density of bilayer membranes and the accumulation of lipid peroxidation, causing membrane lipid peroxidation and eventually cell death. Similar with the most forms of regulated cell death, ferroptosis also participated in the pathological metabolism of myocardial infarction and myocardial ischemia/reperfusion injuries, which are still the leading causes of death worldwide. Given the crucial roles ferroptosis played in cardiovascular diseases, such as myocardial infarction and myocardial ischemia/reperfusion injuries, it is considerable to delve into the molecular mechanisms of ferroptosis contributing to the progress of cardiovascular diseases, which might offer the potential role of ferroptosis as a targeted treatment for a wide range of cardiovascular diseases. This review systematically summarizes the process and regulatory metabolisms of ferroptosis, discusses the relationship between ferroptosis and myocardial infarction as well as myocardial ischemia/reperfusion injuries, which might potentially provide novel insights for the pathological metabolism and original ideas for the prevention as well as treatment targeting ferroptosis of cardiovascular diseases such as myocardial infarction and myocardial ischemia/reperfusion injuries.

Advances in research on the protective mechanisms of traditional Chinese medicine (TCM) in myocardial ischaemia-reperfusion injury

CONTEXT

Developing effective drugs to treat myocardial ischaemia-reperfusion (MI/R) injury is imperative. Traditional Chinese medicines (TCMs) have had considerable success in the treatment of cardiovascular diseases. Elucidating the mechanisms by which TCMs improve MI/R injury can supplement the literature on MI/R prevention and treatment.

OBJECTIVE

To summarise TCMs and their main protective mechanisms against MI/R injury reported over the past 40 years.

METHODS

Relevant literature published between 1980 and 2020 in Chinese and English was retrieved from the Web of Science, PubMed, SpringerLink, PubMed Central, Scopus, and Chinese National Knowledge Infrastructure (CNKI) databases. Search terms included 'medicinal plants', 'myocardial ischaemia reperfusion injury', 'Chinese medicine prescriptions', 'mechanisms', 'prevention', 'treatment' and 'protection'. For inclusion in the analysis, medicinal plants had to be searchable in the China Medical Information Platform and Plant Database.

RESULTS

We found 71 medicinal species (from 40 families) that have been used to prevent MI/R injury, of which Compositae species (8 species) and Leguminosae species (7 species) made up the majority. Most of the effects associated with these plants are described as antioxidant and anti-inflammatory. Furthermore, we summarised 18 kinds of Chinese compound prescriptions, including the compound Danshen tablet and Baoxin pill, which mainly reduce oxidative stress and regulate mitochondrial energy metabolism.

DISCUSSION AND CONCLUSIONS

We summarised TCMs that protect against MI/R injury and their pharmacological mechanisms. This in-depth explanation of the roles of TCMs in MI/R injury protection provides a theoretical basis for the research and development of TCM-based treatment drugs.

Dual Specific Phosphatase 7 Exacerbates Dilated Cardiomyopathy, Heart Failure, and Cardiac Death by Inactivating the ERK1/2 Signaling Pathway

Heart failure is one of the most common but complicated end-stage syndromes in clinical practice. Dilated cardiomyopathy is a myocardial structural abnormality that is associated with heart failure. Dual-specificity phosphatases (DUSPs) are a group of protein phosphatases that regulate signaling pathways in numerous diseases; however, their physiological and pathological impact on cardiovascular disease remains unknown. In the present study, we generated two transgenic mouse models, a DUSP7 knockout and a cardiac-specific DUSP7 overexpressor. Mice overexpressing DUSP7 showed an exacerbated disease phenotype, including severe dilated cardiomyopathy, heart failure, and cardiac death. We further demonstrated that high levels of DUSP7 inhibited ERK1/2 phosphorylation and influenced downstream c-MYC, c-FOS, and c-JUN gene expression but did not affect upstream activators. Taken together, our study reveals a novel molecular mechanism for DUSP7 and provides a new therapeutic target and clinical path to alleviate dilated cardiomyopathy and improve cardiac function.

Plants and their Bioactive Compounds as a Possible Treatment for Traumatic Brain Injury-Induced Multi-Organ Dysfunction Syndrome

BACKGROUND & OBJECTIVE

Traumatic brain injury is an outcome of the physical or mechanical impact of external forces on the brain. Thus, the silent epidemic has complex pathophysiology affecting the brain along with extracranial or systemic complications in more than one organ system, including the heart, lungs, liver, kidney, gastrointestinal and endocrine system. which is referred to as Multi-Organ Dysfunction Syndrome. It is driven by three interconnected mechanisms such as systemic hyperinflammation, paroxysmal sympathetic hyperactivity, and immunosuppression-induced sepsis. These multifaceted pathologies accelerate the risk of mortality in clinical settings by interfering with the functions of distant organs through hypertension, cardiac arrhythmias, acute lung injury, neurogenic pulmonary edema, reduced gastrointestinal motility, Cushing ulcers, acute liver failure, acute kidney injury, coagulopathy, endocrine dysfunction, and many other impairments. The pharmaceutical treatment approach for this is highly specific in its mode of action and linked to a variety of side effects, including hallucinations, seizures, anaphylaxis, teeth, bone staining, etc. Therefore, alternative natural medicine treatments are widely accepted due to their broad complementary or synergistic effects on the physiological system with minor side effects.

CONCLUSION

This review is a compilation of the possible mechanisms behind the occurrence of multiorgan dysfunction and reported medicinal plants with organoprotective activity that have not been yet explored against traumatic brain injury and thereby, highlighting the marked possibilities of their effectiveness in the management of multiorgan dysfunction. As a result, we attempted to respond to the hypothesis against the usage of medicinal plants to treat neurodegenerative diseases.

A novel function of ATF3 in suppression of ferroptosis in mouse heart suffered ischemia/reperfusion

INTRODUCTION

Ferroptosis, a newly identified type of programmed cell death type, has been proven to contribute to the progression of myocardial ischemia/reperfusion (I/R) injury. However, little is known about ferroptosis regulation in I/R injury.

OBJECTIVES

We identified activating transcription factor 3 (ATF3) as a vital regulator of I/R induced ferroptosis and investigated the effects and potential mechanism of ATF3 in cardiac ferroptosis.

METHODS

In this study, the dynamic RNA-sequencing (RNA-seq) analysis were performed on mouse hearts exposed to different I/R schedules to identify that ATF3 represents an important modulatory molecule in myocardial I/R injury. Then knockout, rescue and overexpression methods were used in mice and neonatal mouse cells (NMCs) to illustrate the effect of ATF3 on myocardial I/R injury. Loss/gain of function techniques were used both in vivo and in vitro to explore the effects of ATF3 on ferroptosis in I/R injury. Furthermore, chromatin immunoprecipitation sequence (ChIP-seq) analysis was performed in the AC16 human cardiomyocyte cell line to investigate potential genes regulated by ATF3.

RESULTS

ATF3 expression reached highest level at early stage of reperfusion, knockout of ATF3 significantly aggravated I/R injury, which could be rescued by ATF3 re-expression. Knockout and the re-expression of ATF3 changed the transcription levels of multiple ferroptosis genes. In addition, results showed that overexpression of ATF3 inhibits cardiomyocyte ferroptosis triggered by erastin and RSL3. Lastly, ChIP-seq and dual luciferase activity analysis revealed ATF3 could bind to the transcription start site of Fanconi anaemia complementation group D2 (FANCD2) and increased the FANCD2 promoter activity. Furthermore, we first demonstrated that overexpression of FANCD2 exerts significant anti-ferroptosis and cardioprotective effect on AC16 cell H/R injury.

CONCLUSION

ATF3 inhibits cardiomyocyte ferroptotic death in I/R injury, which might be related with regulating FANCD2. Our study provides new insight into the molecular target for the therapy of myocardial I/R injury.

Honokiol Ameliorates Post-Myocardial Infarction Heart Failure Through Ucp3-Mediated Reactive Oxygen Species Inhibition

Post-myocardial infarction heart failure (post-MI HF) is one of the leading global causes of death, and current prevention and treatment methods still cannot avoid the increasing incidence. Honokiol (HK) has previously been reported to improve myocardial ischemia/reperfusion injury and reverse myocardial hypertrophy by activating Sirt1 and Sirt3. We suspect that HK may also have a therapeutic effect on post-MI HF. In this study, we aimed to investigate the efficacy and mechanism of HK in the treatment of post-MI HF. We found that HK inhibited myocardial reactive oxygen species (ROS) production, reduced myocardial fibrosis, and improved cardiac function in mice after MI. HK also reduced the abnormality of mitochondrial membrane potential (MMP) and apoptosis of cardiomyocytes caused by peroxide in neonatal cardiomyocytes. RNAseq results revealed that HK restored the transcriptome changes to a certain extent and significantly enhanced the expression of mitochondrial inner membrane uncoupling protein isoform 3 (Ucp3), a protein that inhibits the production of mitochondrial ROS, protects cardiomyocytes, and relieves heart failure after myocardial infarction (MI). In cardiomyocytes with impaired Ucp3 expression, HK cannot protect against the damage caused by peroxide. More importantly, in Ucp3 knockout mice, HK did not change the increase in the ROS level and cardiac function damage after MI. Taken together, our results suggest that HK can increase the expression of the cardioprotective protein Ucp3 and maintain MMP, thereby inhibiting the production of ROS after MI and ameliorating heart failure.

Promising Therapeutic Candidate for Myocardial Ischemia/Reperfusion Injury: What Are the Possible Mechanisms and Roles of Phytochemicals?

Percutaneous coronary intervention (PCI) is one of the most effective reperfusion strategies for acute myocardial infarction (AMI) despite myocardial ischemia/reperfusion (I/R) injury, causing one of the causes of most cardiomyocyte injuries and deaths. The pathological processes of myocardial I/R injury include apoptosis, autophagy, and irreversible cell death caused by calcium overload, oxidative stress, and inflammation. Eventually, myocardial I/R injury causes a spike of further cardiomyocyte injury that contributes to final infarct size (IS) and bound with hospitalization of heart failure as well as all-cause mortality within the following 12 months. Therefore, the addition of adjuvant intervention to improve myocardial salvage and cardiac function calls for further investigation. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in Chinese herbal medicine. Great effort has been put into phytochemicals because they are often in line with the expectations to improve myocardial I/R injury without compromising the clinical efficacy or to even produce synergy. We summarized the previous efforts, briefly outlined the mechanism of myocardial I/R injury, and focused on exploring the cardioprotective effects and potential mechanisms of all phytochemical types that have been investigated under myocardial I/R injury. Phytochemicals deserve to be utilized as promising therapeutic candidates for further development and research on combating myocardial I/R injury. Nevertheless, more studies are needed to provide a better understanding of the mechanism of myocardial I/R injury treatment using phytochemicals and possible side effects associated with this approach.

The modulation of SIRT1 and SIRT3 by natural compounds as a therapeutic target in doxorubicin-induced cardiotoxicity: A review

Doxorubicin (DOX) is a potent antitumor agent with a broad spectrum of activity; however, irreversible cardiotoxicity resulting from DOX treatment is a major issue that limits its therapeutic use. Sirtuins (SIRTs) play an essential role in several physiological and pathological processes including oxidative stress, apoptosis, and inflammation. It has been reported that SIRT1 and SIRT3 can act as a protective molecular against DOX-induced myocardial injury through targeting numerous signaling pathways. Several natural compounds (NCs), such as resveratrol, sesamin, and berberine, with antioxidative, anti-inflammation, and antiapoptotic effects were evaluated for their potential to suppress the cardiotoxicity induced by DOX via targeting SIRT1 and SIRT3. Numerous NCs exerted their therapeutic effects on DOX-mediated cardiac damage via targeting different signaling pathways, including SIRT1/LKB1/AMPK, SIRT1/PGC-1α, SIRT1/NLRP3, and SIRT3/FoxO. SIRT3 also ameliorates cardiotoxicity by enhancing mitochondrial fusion.

Inhibition of HMGB1 alleviates myocardial ischemia/reperfusion injury in diabetic mice via suppressing autophagy

BACKGROUND

Diabetes aggravates myocardial ischemia/reperfusion (I/R) injury (MI/RI). The association between high mobility group box 1 protein (HMGB1) and autophagy in diabetic MI/RI remains unknown. Therefore, we investigated whether inhibiting HMGB1 can regulate autophagy in diabetic mice (DM) after I/R injury.

METHODS

I/R models of C57BL/KsJ mice and db/db mice were established. Histological changes, infarct size (IS), HMGB1 protein, and autophagy-related proteins were detected after 24h of reperfusion. In DM treatment groups, anti-HMGB1 antibody (H-Ig) was injected via tail vein after reperfusion for 15min, and the above-mentioned experimental methods were performed at the end of reperfusion.

RESULTS

Compared with the I/R group, the pathological myocardial damage and IS were significantly increased in the I/R (DM) group. Additionally, the levels of HMGB1, Beclin1, and LC3II/LC3I ratio were remarkably higher in the I/R (DM) group than those in the I/R group, while p62 level was lower. In the H-Ig (DM) group, injection of H-Ig significantly reduced the IS, as well as alleviated pathological myocardial damage. Moreover, Beclin1, LC3II/LC3I ratio, and p62 levels were notably reversed after this treatment.

CONCLUSIONS

I/R-induced myocardium was aggravated by diabetes, which may be related to increased release of HMGB1 and activated autophagy. Inhibition of HMGB1 alleviates diabetic MIRI which was associated with reduced autophagy.

Honokiol regulates endoplasmic reticulum stress by promoting the activation of the sirtuin 1-mediated protein kinase B pathway and ameliorates high glucose/high fat-induced dysfunction in human umbilical vein endothelial cells

Honokiol plays an important role in anti-oxidation, but its role in diabetic vascular complications is unclear. In this study, the effects of honokiol in high glucose/high fat (HG/HF)-induced human umbilical vein endothelial cells (HUVECs) were explored. After pre-treatment with honokiol, the cells were transferred to an HG/HF medium, and cell viability and apoptosis were respectively measured by methyl tetrazolium and flow cytometry. Moreover, the contents of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured. The expressions of C/EBP homologous protein (CHOP), glucose-regulated protein 78 (GRP78), phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase (p-PERK), phosphorylated-inositol requiring enzyme-1α (p-IRE1α), cleaved caspase-3 and SIRT1 were determined by Western blot or quantitative reverse transcription PCR, respectively. Finally, the viability, apoptosis, and the contents of ROS, MDA, and SOD, as well as the expressions of CHOP, GRP78, p-PERK, p-IRE1α, cleaved caspase-3, Akt, p-Akt, and SIRT1 in the cells transfected with small interfering RNA SIRT1 (siSIRT1) were detected by the previously mentioned methods. Honokiol reversed the effect of HG/HF on promoting cell apoptosis, ROS and MDA contents, and the expressions of CHOP, GRP78, p-PERK, p-IRE1α and cleaved caspase-3, and also reversed the inhibitory effect of HG/HF on cell viability, SOD content and SIRT1 expression. However, siSIRT1 reversed the above effects caused by honokiol. Honokiol activated SIRT1 promoter. SIRT1 interacted with Akt, consequently promoting the activity of Akt. Therefore, honokiol activates the Akt pathway by regulating SIRT1 expression to regulate endoplasmic reticulum stress, promotes cell viability and inhibits the apoptosis of HG/HF-induced HUVECs.

Anastatin Derivatives Alleviate Myocardial Ischemia-Reperfusion Injury via Antioxidative Properties

(±)-Anastatins A and B are flavonoids isolated from Anastatica hierochuntica. In a previous study, twenty-four di- and tri-substituted novel derivatives of anastatins were designed and their preliminary antioxidant activities were evaluated. In the present study, the protective effect of myocardial ischemia-reperfusion (I/R) and the systematic antioxidant capacity of 24 derivatives were further studied. Compound 13 was the most potent among all the compounds studied, which increased the survival of H9c2 cells to 80.82%. The antioxidant capability of compound 13 was evaluated in ferric reducing antioxidant power, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging, and 2,2-diphenyl-1-picrylhydrazyl assays. It was observed that compound 13 significantly reduced infarcted areas and improved histopathological and electrocardiogram changes in rats with myocardial I/R injury. Moreover, compound 13 decreased the leakage rates of serum lactate dehydrogenase, creatine kinase, and malonyldialdehyde from rat myocardial tissues and increased the level of glutathione and superoxide dismutase activities following myocardial I/R injury in rats. Taken together, we concluded that compound 13 had potent cardioprotective effects against myocardial I/R injury both in vitro and in vivo owing to its extensive antioxidant activities.

Inflammation suppression in doxorubicin-induced cardiotoxicity: natural compounds as therapeutic options

Doxorubicin (DOX) is a potent chemotherapeutic agent; however, the accompanying cardiotoxicity is a significant complication of the usefulness of treatment with DOX. Multiple mechanisms have been suggested for this often fatal side effect, one of which is inflammation. Several pathways with different targets have been reported to result in DOX-induced heart inflammation. Some natural occurring compounds (NCs) have been reported to interact with the DOX-induced cardiotoxicity through targeting one or more of several pathways, including the Nrf2/NF-kB, TLR-4/NF-kB, MAPK/NF-kB, and NLRP3 inflammasome pathways. This article reviews several of these pathways and the potential protective effect of some NCs against the cardiac inflammation induced by DOX.

Natural products as geroprotectors: An autophagy perspective

Over the past decade, significant attention has been given to repurposing Food and Drug Administration approved drugs to treat age-related diseases. In contrast, less consideration has been given to natural bioactive compounds. Consequently, there have been limited attempts to translate these compounds. Autophagy is a fundamental biological pathway linked to aging, and numerous strategies to enhance autophagy have been shown to extend lifespan. Interestingly, there are a number of natural products that are reported to modulate autophagy, and here we describe a number of them that activate autophagy through diverse molecular and cellular mechanisms. Among these, Urolithin A, Spermidine, Resveratrol, Fatty Acids and Phospholipids, Trehalose and Lithium are featured in detail. Finally, we outline possible strategies to optimise and increase the translatability of natural products, with the overall aim of delaying the ageing process and improving human healthspan.

Design of novel enzyme biocatalysts for industrial bioprocess: Harnessing the power of protein engineering, high throughput screening and synthetic biology

Biocatalysts have wider applications in various industries. Biocatalysts are generating bigger attention among researchers due to their unique catalytic properties like activity, specificity and stability. However the industrial use of many enzymes is hindered by low catalytic efficiency and stability during industrial processes. Properties of enzymes can be altered by protein engineering. Protein engineers are increasingly study the structure-function characteristics, engineering attributes, design of computational tools for enzyme engineering, and functional screening processes to improve the design and applications of enzymes. The potent and innovative techniques of enzyme engineering deliver outstanding opportunities for tailoring industrially important enzymes for the versatile production of biochemicals. An overview of the current trends in enzyme engineering is explored with important representative examples.

[miR-133b inhibits myocardial ischemia-reperfusion-induced cardiomyocyte apoptosis and accumulation of reactive oxygen species in rats by targeting YES1]

OBJECTIVE

To investigate the effect of miR-133b on cardiomyocyte apoptosis induced by myocardial ischemia-reperfusion (I/R) and explore the mechanism.

METHODS

Thirty-six adult SD rats were randomized into sham-operated group, I/R group, AdmiR-NC group and AdmiR-133b group, and rat models of myocardial I/R were established in the latter 3 groups with myocardial injections of saline or recombinant adenoviruses in the left ventricle. The expression of MiR-133b was detected using RT-qPCR, and cardiac function of the rats was determined using FDP 1 HRV and BRS analysis system. Serum CK-MB and cTnI levels were determined by ELISA, myocardial injury was evaluated with HE staining, cardiomocyte apoptosis was detected by flow cytometry, and ROS content was determined using a DCFH-DA probe. In the in vitro experiment, H9C2 myocardial cells with hypoxia/reoxygenation (H/R) treatment were transfected with Mir-NC or MiR-133b mimic, and the cellular expression of MiR-133b, cell apoptosis, and ROS content were determined. Dual luciferase reporter assay was performed to verify the targeting relationship between miR-133b and YES1. The effects of pc-YES1 or miR-133b mimic transfection on YES1 expression, apoptosis, and ROS content in H9C2 cells were evaluated.

RESULTS

Compared with those in I/R group, miR-133b expression was obviously up-regulated, LVEDP, cTnI and CK-MB levels were significantly decreased, and LVSP, +dp/dt, -dp/dt, HR and CF levels were increased in admiR-133b group (P < 0.01). The rats in admiR-133b group showed obviously reduced pathological damage, cell apoptosis and ROS content compared with those in I/ R group (P < 0.01). In H9C2 cells exposed to H/R, transfection with miR-133b mimic significantly up-regulated miR-133b expression and decreased cell apoptosis and ROS content (P < 0.01). The results of dual luciferase reporter assay suggested a direct targeting relationship between miR-133b and YES1, and MiR-133b mimic transfection significantly down-regulated YES1 protein expression in cells with H/R exposure (P < 0.01). Co-transfection with pc-YES1 reversed the effect of miR-133b overexpression on myocardial cell apoptosis and ROS accumulation.

CONCLUSIONS

miR-133b can inhibit I/R-induced myocardial cell apoptosis and ROS accumulation by targeting YES1 to reduce myocardial I/R injury in rats.

Visnagin ameliorates myocardial ischemia/reperfusion injury through the promotion of autophagy and the inhibition of apoptosis

Visnagin is a furanochromone and one of the main compounds of Ammi visnaga L. that had been used to treat nephrolithiasis in Ancient Egypt. Nowadays, visnagin was widely used to treat angina pectoris, urolithiasis and hypertriglyceridemia. The potential mechanisms of visnagin involved in inflammation and cardiovascular disease were also identified. But the protective effect of visnagin on myocardial ischemia/reperfusion injury has not been confirmed. Our aim was, for the first time, to investigate the potential protective effect of visnagin on cardiac function after myocardial ischemia-reperfusion injury in a rat model, and to identify its underlying mechanism involving the inhibition of apoptosis and induction of autophagy. Thirty SD rats were randomly divided into sham group, ischemia/reperfusion group (IR), ischemia/reperfusion with visnagin (IR + visnagin) group. Myocardial ischemia/Reperfusion injury model was established. Hemodynamic measurements and echocardiography were used to analyze cardiac function, TUNEL staining and caspase activity, LC3 dots were detected with immunofluorescence staining, LC3 expression was evaluated by western blot analysis, transmission electron microscopy (TEM) was used to detect autophagosomes. Compared with the sham group and visnagin group, the cardiac dysfunction, LC3II, autophagy flow in the IR+ visnagin group increased significantly (P<0.01), but the activity of caspase-3 and caspase-9 and the apoptotic in the IR + visnagin group decreased significantly (P<0.01). In conclusion, visnagin may play a protective role in ischemia/reperfusion injury by inducing autophagy and reducing apoptosis.

Remedying the Mitochondria to Cure Human Diseases by Natural Products

Mitochondria are the ‘engine' of cells. Mitochondrial dysfunction is an important mechanism in many human diseases. Many natural products could remedy the mitochondria to alleviate mitochondria-involved diseases. In this review, we summarized the current knowledge of the relationship between the mitochondria and human diseases and the regulation of natural products to the mitochondria. We proposed that the development of mitochondrial regulators/nutrients from natural products to remedy mitochondrial dysfunction represents an attractive strategy for a mitochondria-involved disorder therapy. Moreover, investigating the mitochondrial regulation of natural products can potentiate the in-depth comprehension of the mechanism of action of natural products.

Attenuation of Lipopolysaccharide-Induced Acute Lung Injury by Hispolon in Mice, Through Regulating the TLR4/PI3K/Akt/mTOR and Keap1/Nrf2/HO-1 Pathways, and Suppressing Oxidative Stress-Mediated ER Stress-Induced Apoptosis and Autophagy

The anti-inflammatory effect of hispolon has identified it as one of the most important compounds from Sanghuangporus sanghuang. The research objectives were to study this compound using an animal model by lipopolysaccharide (LPS)-induced acute lung injury. Hispolon treatment reduced the production of the pro-inflammatory mediator NO, TNF-α, IL-1β, and IL-6 induced by LPS challenge in the lung tissues, as well as decreasing their histological alterations and protein content. Total cell number was also reduced in the bronchoalveolar lavage fluid (BALF). Moreover, hispolon inhibited iNOS, COX-2 and IκB-α and phosphorylated IKK and MAPK, while increasing catalase, SOD, GPx, TLR4, AKT, HO-1, Nrf-2, Keap1 and PPARγ expression, after LPS challenge. It also regulated apoptosis, ER stress and the autophagy signal transduction pathway. The results of this study show that hispolon regulates LPS-induced ER stress (increasing CHOP, PERK, IRE1, ATF6 and GRP78 protein expression), apoptosis (decreasing caspase-3 and Bax and increasing Bcl-2 expression) and autophagy (reducing LC3 I/II and Beclin-1 expression). This in vivo experimental study suggests that hispolon suppresses the LPS-induced activation of inflammatory pathways, oxidative injury, ER stress, apoptosis and autophagy and has the potential to be used therapeutically in major anterior segment lung diseases.

Sodium Selenate Ameliorates Cardiac Injury Developed from High-Fat Diet in Mice through Regulation of Autophagy Activity

Obesity is often accompanied by dyslipidemia, high blood glucose, hypertension, atherosclerosis, and myocardial dysfunction. Selenate is a vital antioxidant in the cardiovascular system. The beneficial effects of selenate on obesity-associated cardiac dysfunction and potential molecular mechanism were identified in both H9C2 cells and C57BL/6J mice hearts. The cardiac histological preformation in C57BL/6J mice were evaluated by cross-sectional area (CSA) of cardiomyocytes and percent area of fibrosis in the left ventricles. The cardiac autophagy flux in H9C2 cells and C57BL/6J mice hearts was analyzed by Western blots and the number of autophagosomes and autolysosome in H9C2 cells. In the present study, we found that lipid overload caused increases in serum lipid, CSA, and percent area of fibrosis. We further found that lipid-induced accumulation of autophagosomes  was due to depressed autophagy degradation, which was not restored in the pretreatment with 3-methyladenine and chloroquine, whereas, it was improved by rapamycin. Moreover, we demonstrated that increased levels of serum lipid, CSA, percent area of fibrosis and mRNA expression related to cardiomyocytes hypertrophy and fibrosis were significantly reduced after selenate treatments of mice. We also found selenate treatment significantly down-regulated activity of the Akt pathway, which was activated in response to lipid-overload. Furthermore, selenate dramatically improved cardiac autophagic degradation which was suppressed after exposure to lipid-overload in both H9C2 cells and C57BL/6J mice hearts. Taken together, selenate offers therapeutic intervention in lipid-related metabolic disorders, and protection against cardiac remodeling, likely through regulation of the activity of autophagic degradation and Akt pathway.

Honokiol antagonizes doxorubicin‑induced cardiomyocyte senescence by inhibiting TXNIP‑mediated NLRP3 inflammasome activation

Senescence of cardiomyocytes is considered a key factor for the occurrence of doxorubicin (Dox)‑associated cardiomyopathy. The NOD‑like receptor family pyrin domain‑containing 3 (NLRP3) inflammasome is reported to be involved in the process of cellular senescence. Furthermore, thioredoxin‑interactive protein (TXNIP) is required for NLRP3 inflammasome activation and is considered to be a key component in the regulation of the pathogenesis of senescence. Studies have demonstrated that pretreatment with honokiol (Hnk) can alleviate Dox‑induced cardiotoxicity. However, the impact of Hnk on cardiomyocyte senescence elicited by Dox and the underlying mechanisms remain unclear. The present study demonstrated that Hnk was able to prevent Dox‑induced senescence of H9c2 cardiomyocytes, indicated by decreased senescence‑associated β‑galactosidase (SA‑β‑gal) staining, as well as decreased expression of p16INK4A and p21. Hnk also inhibited TXNIP expression and NLRP3 inflammasome activation in Dox‑stimulated H9c2 cardiomyocytes. When TXNIP expression was enforced by adenovirus‑mediated gene overexpression, the NLRP3 inflammasome was activated, which led to inhibition of the anti‑inflammation and anti‑senescence effects of Hnk on H9c2 cardiomyocytes under Dox treatment. Furthermore, adenovirus‑mediated TXNIP‑silencing inhibited the NLRP3 inflammasome. Consistently, TXNIP knockdown enhanced the anti‑inflammation and anti‑senescence effects of Hnk on H9c2 cardiomyocytes under Dox stimulation. In summary, Hnk was found to be effective in protecting cardiomyocytes against Dox‑stimulated senescence. This protective effect was mediated via the inhibition of TXNIP expression and the subsequent suppression of the NLRP3 inflammasome. These results demonstrated that Hnk may be of value as a cardioprotective drug by inhibiting cardiomyocyte senescence.