Protective Effects of L-Malate against Myocardial Ischemia/Reperfusion Injury in Rats

Nrf2 Signaling Pathway: Focus on Oxidative Stress in Spinal Cord Injury

Spinal cord injury (SCI) is a serious, disabling injury to the central nervous system that can lead to motor, sensory, and autonomic dysfunction below the injury plane. SCI can be divided into primary injury and secondary injury according to its pathophysiological process. Primary injury is irreversible in most cases, while secondary injury is a dynamic regulatory process. Secondary injury involves a series of pathological events, such as ischemia, oxidative stress, inflammatory events, apoptotic pathways, and motor dysfunction. Among them, oxidative stress is an important pathological event of secondary injury. Oxidative stress causes a series of destructive events such as lipid peroxidation, DNA damage, inflammation, and cell death, which further worsens the microenvironment of the injured site and leads to neurological dysfunction. The nuclear factor erythrocyte 2-associated factor 2 (Nrf2) is considered to be a key pathway of antioxidative stress and is closely related to the pathological process of SCI. Activation of this pathway can effectively inhibit the oxidative stress process and promote the recovery of nerve function after SCI. Therefore, the Nrf2 pathway may be a potential therapeutic target for SCI. This review deeply analyzed the generation of oxidative stress in SCI, the role and mechanism of Nrf2 as the main regulator of antioxidant stress in SCI, and the influence of cross-talk between Nrf2 and related pathways that may be involved in the pathological regulation of SCI on oxidative stress, and summarized the drugs and other treatment methods based on Nrf2 pathway regulation. The objective of this paper is to provide evidence for the role of Nrf2 activation in SCI and to highlight the important role of Nrf2 in alleviating SCI by elucidating the mechanism, so as to provide a theoretical basis for targeting Nrf2 pathway as a therapy for SCI.

Nrf2 for a key member of redox regulation: A novel insight against myocardial ischemia and reperfusion injuries

Nuclear factor erythroid-2 related factor 2 (Nrf2), a nuclear transcription factor, modulates genes responsible for antioxidant responses against toxic and oxidative stress to maintain redox homeostasis and participates in varieties of cellular processes such as metabolism and inflammation during myocardial ischemia and reperfusion injuries (MIRI). The accumulation of reactive oxygen species (ROS) from damaged mitochondria, xanthine oxidase, NADPH oxidases, and inflammation contributes to depraved myocardial ischemia and reperfusion injuries. Considering that Nrf2 played crucial roles in antagonizing oxidative stress, it is reasonable to delve into the up or down-regulated molecular mechanisms of Nrf2 in the progression of MIRI to provide the possibility of new therapeutic medicine targeting Nrf2 in cardiovascular diseases. This review systematically describes the generation of ROS, the regulatory metabolisms of Nrf2 as well as several natural or synthetic compounds activating Nrf2 during MIRI, which might provide novel insights for the anti-oxidative stress and original ideas targeting Nrf2 for the prevention and treatment in cardiovascular diseases.

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

Quiescence preconditioned nucleus pulposus stem cells alleviate intervertebral disc degeneration by enhancing cell survival via adaptive metabolism pattern in rats

Quiescence is a cellular state of reversible growth arrest required to maintain homeostasis and self-renewal. Entering quiescence allows the cells to remain in the non-dividing stage for an extended period of time and enact mechanisms to protect themselves from damage. Due to the extreme nutrient-deficient microenvironment in the intervertebral disc (IVD), the therapeutic effect of cell transplantation is limited. In this study, nucleus pulposus stem cells (NPSCs) were preconditioned into quiescence through serum starvation in vitro and transplanted to repair intervertebral disc degeneration (IDD). In vitro, we investigated apoptosis and survival of quiescent NPSCs in a glucose-free medium without fetal bovine serum. Non-preconditioned proliferating NPSCs served as controls. In vivo, the cells were transplanted into a rat model of IDD induced by acupuncture, and the intervertebral disc height, histological changes, and extracellular matrix synthesis were observed. Finally, to elucidate the mechanisms underlying the quiescent state of NPSCs, the metabolic patterns of the cells were investigated through metabolomics. The results revealed that quiescent NPSCs decreased apoptosis and increased cell survival when compared to proliferating NPSCs both in vitro and in vivo, as well as maintained the disc height and histological structure significantly better than that by proliferating NPSCs. Furthermore, quiescent NPSCs have generally downregulated metabolism and reduced energy requirements in response to a switch to a nutrient-deficient environment. These findings support that quiescence preconditioning maintains the proliferation and biological function potential of NPSCs, increases cell survival under the extreme environment of IVD, and further alleviates IDD via adaptive metabolic patterns.

Integrated Gut-Heart Axis and Network Pharmacology to Reveal the Mechanisms of the Huoxue Wentong Formula Against Myocardial Ischemia

Background

Myocardial ischemia (MI) is a major public health problem with high mortality and morbidity worldwide. Huoxue Wentong formula (HX), a traditional Chinese medicine (TCM) formula, exhibits unambiguous effects on treating MI and preventing cardiovascular diseases. However, the molecular mechanism of the therapeutic effects of HX on MI remains largely unknown.

Objective

This study combined microbiology, metabolomics, and network pharmacology to explore the relationship between the gut microbiota and its metabolites in MI rats and the efficacy of HX.

Methods

First, the MI rat model was established by ligation of left anterior descending. Echocardiography, Masson's staining, and hematoxylin and eosin staining were used to evaluate the effect of HX on MI. Then, fecal metabolomics and 16S rRNA sequencing were used to obtain the microbial and metabolic characteristics of HX on MI. After that, network pharmacology was used to predict the target and action pathway of HX in treating MI. Finally, the relationship between fecal metabolites and target was explored through bioinformatics.

Results

HX can improve the cardiac function and ameliorated myocardial fibrosis in MI rats. Moreover, HX can affect the gut microbiota community and metabolites of MI rats, especially Bacteroides, Deferribacteres, Ruminococcus_sp._zagget7, Acidobacteria, daidzein, L-lactic acid, and malate. Network pharmacology found that HX can function through tumor necrosis factor (TNF), tumor protein p53 (TP53), interleukin 6 (IL6), vascular endothelial growth factor A (VEGFA), fos proto-oncogene (FOS), bcl2-associated X (BAX), myeloperoxidase (MPO), PI3K-Akt signaling pathways, and HIF-1 signaling pathway. The mechanism study showed that the anti-MI effect of HX was related to valine, leucine, and isoleucine biosynthesis, fatty acid biosynthesis, and arachidonic acid metabolism.

Conclusion

This study demonstrates that HX treated MI rats in a multitarget and multipathway manner. Its mechanism is related to the change of gut microbiota and the regulation of valine, leucine and isoleucine biosynthesis, fatty acid biosynthesis, and arachidonic acid metabolism.

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.

CTRP3 alleviates cardiac ischemia/reperfusion injury via LAMP1/JIP2/JNK signaling pathway

Background: C1q/tumor necrosis factor-related protein 3 (CTRP3) has been reported to be a crucial regulator in myocardial infarction. Nevertheless, the potential molecular mechanism of CTRP3 in ischemia/reperfusion (I/R) injury remains largely unclear.

Methods: The cell model of myocardial I/R injury was established by oxygen-glucose deprivation/reoxygenation (OGD/R) of rat cardiomyocyte H9C2. Expression of CTRP3 and lysosomal-associated membrane protein 1 (LAMP1) was detected in H9C2 cells treated with oxygen-glucose deprivation/reoxygenation (OGD/R). H9C2 cells were transfected with overexpression plasmids of CTRP3 (pcDNA-CTRP3) and LAMP1 (pcDNA-LAMP1), or CTRP3 small interfering RNA (si-CTRP3) or/and pcDNA-LAMP1, and cell proliferation, apoptosis and oxidative stress were testified. Co-IP assay was performed to validate the relationship among CTRP3, LAMP1 and JIP2. The role of CTRP3 and LAMP1 in JIP2/JNK pathway was evaluated with Western blot assay. Furthermore, in vivo myocardial I/R injury model was constructed to investigate the effect of CTRP3.

Results: Overexpression of CTRP3 and LAMP1 both significantly promoted cell proliferation, inhibited apoptosis and the production of reactive oxygen species (ROS), malondialdehyde (MAD) and cardiac troponin (cTn-I), while silencing CTRP3 exerted the opposite effects, and LAMP1 overexpression reversed the effect of silencing CTRP3 on the aspects above. CTRP3 interacted with LAMP1, and both CTRP3 and LAMP1 bound with JIP2. SP600125 (JNK inhibitor) could restore the effects of CTRP3 or LAMP1 overexpression on the expression of JIP2 and phosphorylated-JNK (p-JNK), proliferation and apoptosis. Moreover, overexpression of CTRP3 improved cardiac I/R injury in vivo.

Conclusion: CTRP3 alleviates cardiac I/R injury by elevating LAMP1 and activating JIP2/JNK signaling pathway, which may serve as a potential therapeutic target for I/R injury.

Genetic variation in the promoter of an R2R3-MYB transcription factor determines fruit malate content in apple (Malus domestica Borkh.)

Deciphering the mechanism of malate accumulation in apple (Malus domestica Borkh.) fruits can help to improve their flavor quality and enhance their benefits for human health. Here, we analyzed malate content as a quantitative trait that is determined mainly by genetic effects. In a previous study, we identified an R2R3-MYB transcription factor named MdMYB44 that was a candidate gene in qtl08.1 (quantitative trait locus mapped to chromosome 8) of fruit malate content. In the present study, we established that MdMYB44 negatively regulates fruit malate accumulation by repressing the promoter activity of the malate-associated genes Ma1 (Al-Activated Malate Transporter 9), Ma10 (P-type ATPase 10), MdVHA-A3 (V-type ATPase A3), and MdVHA-D2 (V-type ATPase D2). Two single-nucleotide polymorphisms (SNPs) in the MdMYB44 promoter, SNP A/G and SNP T/-, were experimentally shown to associate with fruit malate content. The TATA-box in the MdMYB44 promoter in the presence of SNP A enhances the basal activity of the MdMYB44 promoter. The binding of a basic-helix-loop-helix transcription factor MdbHLH49 to the MdMYB44 promoter was enhanced by the presence of SNP T, leading to increased MdMYB44 transcript levels and reduced malate accumulation. Furthermore, MdbHLH49 interacts with MdMYB44 and enhances MdMYB44 activity. The two SNPs could be used in combination to select for sour or non-sour apples, providing a valuable tool for the selection of fruit acidity by the apple breeding industry. This research is important for understanding the complex molecular mechanisms of fruit malate accumulation and accelerating the development of germplasm innovation in apple species and cultivars.

Emerging Therapeutic Applications for Fumarates

Fumarates are successfully used for the treatment of psoriasis and multiple sclerosis. Their antioxidative, immunomodulatory, and neuroprotective properties make fumarates attractive therapeutic candidates for other pathologies. The exact working mechanisms of fumarates are, however, not fully understood. Further elucidation of the mechanisms is required if these drugs are to be successfully repurposed for other diseases. Towards this, administration route, dosage, and treatment timing, frequency, and duration are important parameters to consider and optimize with clinical paradigms in mind. Here, we summarize the rapidly expanding literature on the pharmacokinetics and pharmacodynamics of fumarates, including a discussion on two recently FDA-approved fumarates VumerityTM and BafiertamTM. We review emerging applications of fumarates, focusing on neurological and cardiovascular diseases.

Dan Hong Injection Protects Against Cardiomyocytes Apoptosis by Maintaining Mitochondrial Integrity Through Keap1/Nuclear Factor Erythroid 2-Related Factor 2/JNK Pathway

Danhong injection (DHI) is used widely against cardiovascular disease in China. Recent studies have demonstrated its mitochondria-protection effect as being pivotal in treatment of myocardial ischemia/reperfusion (I/R) injury, but the underlying mechanism of action is incompletely understood. We aimed to identify the effect and mechanism of action of DHI on mitochondrial integrity and cardiomyocyte apoptosis after I/R. An I/R rat model was induced to detect the effect of DHI on myocardial repair by infarct size, apoptosis and oxidative stress. In vitro, H9C2 cells or H9C2 cells with nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown were injured under hypoxia-reoxygenation (H/R). The effects of DHI on apoptosis, antioxidant capacity and mitochondrial integrity were evaluated by mitochondrial morphology, apoptosis rate, reactive oxygen species (ROS) generation, ATP levels, mitochondrial membrane potential, and oxygen consumption in H9C2 cells treated with H/R. The underlying mechanism of action of DHI in maintenance of mitochondrial integrity and anti-apoptosis was detected in H9C2 cells with or without Nrf2 knockdown. DHI treatment significantly decreased the infarct size, inhibited apoptosis and suppressed oxidative stress in the hearts of I/R rats. Also, DHI promoted cell survival by: an anti-apoptosis action; inhibiting ROS generation; maintaining mitochondrial morphology with increased mitochondrial length; alleviating mitochondrial dysfunction with a decreased mitochondrial membrane potential; increasing ATP levels and the oxygen-consumption rate. Moreover, the Keap1/Nrf2/JNK pathway was found to be involved in DHI reducing oxidative stress and maintaining mitochondrial integrity. We revealed a novel mechanism by which DHI protected H9C2 cells against H/R injury via the Keap1/Nrf2/JNK pathway and provided a mitochondrial protectant for the treatment of myocardial I/R injury.

Role of Nrf2 and Its Activators in Cardiocerebral Vascular Disease

Cardiocerebral vascular disease (CCVD) is a common disease with high morbidity, disability, and mortality. Oxidative stress (OS) is closely related to the progression of CCVD. Abnormal redox regulation leads to OS and overproduction of reactive oxygen species (ROS), which can cause biomolecular and cellular damage. The Nrf2/antioxidant response element (ARE) signaling pathway is one of the most important defense systems against exogenous and endogenous OS injury, and Nrf2 is regarded as a vital pharmacological target. The complexity of the CCVD pathological process and the current difficulties in conducting clinical trials have hindered the development of therapeutic drugs. Furthermore, little is known about the role of the Nrf2/ARE signaling pathway in CCVD. Clarifying the role of the Nrf2/ARE signaling pathway in CCVD can provide new ideas for drug design. This review details the recent advancements in the regulation of the Nrf2/ARE system and its role and activators in common CCVD development.

Phikud Navakot Modulates the Level of Pro-Inflammatory Mediators and the Protein Expression of SOD1 and 2 and the Nrf2/HO-1 Signaling Pathway in Rats with Acute Myocardial Infarction

Phikud Navakot (PN) is nine major herbs in a famous traditional Thai recipe namely “Yahom Navakot” used to treat cardiovascular disorders. This study investigated the cardioprotective effects of PN formula on isoproterenol-induced myocardial infarction (IMI) in Sprague-Dawley rats. Forty-five rats were randomly divided into nine groups (n = 5 per group): the control, the IMI, the IMI + propranolol, the control or the IMI + PN formula (PN ethanolic extract at doses of 64, 127, or 255 mg/kg) by oroesophageal gavage for 28 days. The ST segment and serum troponin T levels were significantly increased in IMI rats. PN did not eliminate tissue necrosis, infiltration of inflammatory cells, or interstitial edema in IMI rats. All doses of PN decreased (p < 0.001) serum TNF-α and IL-6 levels. PN (127 and 255 mg/kg) up-regulated (p < 0.05) heme oxygenase (HO)-1 expression, whereas PN (255 mg/kg) significantly increased superoxide dismutase (SOD) 1 and 2 expression, compared with IMI rats. Nuclear factor erythroid 2-related factor 2 (Nrf2) and HO-1 expression significantly increased in IMI rats and IMI rats that received PN. PN formula possesses potential anti-inflammatory and antioxidant properties by modulating the levels of TNF-α, IL-6 and antioxidant enzymes. Our study reveals a novel cardioprotective effect of PN in IMI rats through the Nrf2/HO-1 signaling.

Hydrogen-rich saline alleviates inflammation and apoptosis in myocardial I/R injury via PINK-mediated autophagy

Ischemia/reperfusion (I/R)-induced inflammatory reaction is one of the most important elements in myocardial I/R injury. In addition, autophagy serves an important role in normal cardiac homeostasis, and obstructions to the autophagy process lead to severe consequences for the heart. Hydrogen exerts an effective therapeutic role in numerous diseases associated with I/R injury via its anti-inflammation, anti-apoptosis and anti-oxidative properties. Therefore, the present study investigated the effect of hydrogen on the myocardial inflammation response and apoptosis in myocardial ischemic/reperfusion (MI/R) injury, and further explored the mechanism of PTEN-induced kinase 1 (PINK1)/Parkin-induced mitophagy in the protection of hydrogen on MI/R injury. MI/R injury was performed by surgical ligation of the left coronary artery in vivo and H9C2 cell injury was performed by hypoxia/reoxygenation (H/R) in vitro. Hydrogen-rich saline was administered twice through intraperitoneal injection at a daily dose of 10 ml/kg following the operation in the in vivo model, and hydrogen-rich medium culture was used for cells instead of normal medium in vitro. The infarction size of hearts, the levels of creati-nine kinase-muscle/brain (CK-MB) and cardiac troponin I (cTnI), cardiac function, cell viability and lactate dehydrogenase (LDH) release, levels of cytokines, apoptosis and the expression of autophagy-associated proteins were detected in the different treatment groups in vivo and in vitro. The results demonstrated that treatment with hydrogen improved the myocardial infarction size of hearts, cardiac function, apoptosis and cytokine release following MI/R in rats. In vitro, hydrogen improved cell viability and LDH release following hypoxia/reoxygenation in myocardial cells. In addition, it was demonstrated that hydrogen exerted an anti-inflammatory and anti-apoptotic effect in myocardial cells induced by H/R via PINK1/Parkin mediated autophagy. These results suggested that hydrogen-rich saline alleviated the inflammation response and apoptosis induced by MI/R or H/R in vivo or in vitro, and that hydrogen-rich saline contributed to the increased expression of proteins associated with autophagy. In summary, the present study indicated that treatment with hydrogen-rich saline improved the inflammatory response and apoptosis in MI/R via PINK1/Parkin-mediated mitophagy.

Acetaminophen Mitigates Myocardial Injury Induced by Lower Extremity Ischemia-Reperfusion in Rat Model

OBJECTIVE

The injury-reducing effect of acetaminophen, an effective analgesic and antipyretic on ischemia-reperfusion continues to attract great attention. This study analyzed the protective effect of acetaminophen on myocardial injury induced by ischemia-reperfusion in an experimental animal model from lower extremity ischemia-reperfusion.

METHODS

Twenty-four Sprague-Dawley female rats were randomized into three groups (n=8) as (i) control group (only laparotomy), (ii) aortic ischemia-reperfusion group (60 min of ischemia and 120 min of reperfusion) and (iii) ischemia-reperfusion + acetaminophen group (15 mg/kg/h intravenous acetaminophen infusion starting 15 minutes before the end of the ischemic period and lasting till the end of the reperfusion period). Sternotomy was performed in all groups at the end of the reperfusion period and the heart was removed for histopathological examination. The removed hearts were histopathologically investigated for myocytolysis, polymorphonuclear leukocyte (PMNL) infiltration, myofibrillar edema and focal hemorrhage.

RESULTS

The results of histopathological examination showed that acetaminophen was detected to particularly diminish focal hemorrhage and myofibrillar edema in the ischemia-reperfusion + acetaminophen group (P<0.001, P=0.011), while there were no effects on myocytolysis and PMNL infiltration between the groups (P=1.000, P=0.124).

CONCLUSION

Acetaminophen is considered to have cardioprotective effect in rats, by reducing myocardial injury induced by abdominal aortic ischemia-reperfusion.

Evaluation of expression levels and mechanism of complement activation

The present study aimed to reveal the expression changes of complement system activation and complement activation product C3a receptor during acute myocardial infarction. Blood samples were collected from healthy individuals and from patients with coronary artery stenosis or acute myocardial infarction. The subjects received physical examination in hospital between January and July 2015 (n=5). Cytometric bead array was performed to measure the levels of complement system activation product anaphylatoxin C3a, C4a and C5a. Immunohistochemical investigations were performed in tissues of patients who underwent coronary artery bypass grafting between January and July 2015 to detect the expression of C3a receptor. The results of cytometric bead array showed that the content of complement activation products C3a, C4a and C5a in the plasma of patients with coronary artery stenosis and acute myocardial infarction were significantly higher than those of the control group (P<0.01). The results of immunoblotting suggested that the protein expression of C3a receptor in infarct tissues of patients with acute myocardial infarction was significantly higher than that of normal tissues adjacent to the infarcted area (P<0.05). There is complement system activation in patients with acute myocardial infarction. Additionally, the increase in the expression of complement C3a receptor in tissues of infarct area suggested that C3a-C3a receptor signaling pathway may be involved in the development of myocardial infarction.