Glycyrrhizic acid ameliorates myocardial ischemia-reperfusion injury in rats through inhibiting endoplasmic reticulum stress

Pentacyclic triterpenes, potential novel therapeutic approaches for cardiovascular diseases

Cardiovascular diseases (CVDs) involve dysfunction of the heart and blood vessels and have become major health concerns worldwide. Multiple mechanisms may be involved in the occurrence and development of CVDs. Although therapies for CVDs are constantly being developed and applied, the incidence and mortality of CVDs remain high. The roles of natural compounds in CVD treatment are being explored, providing new approaches for the treatment of CVD. Pentacyclic triterpenes are natural compounds with a basic nucleus of 30 carbon atoms, and they have been widely studied for their potential applications in the treatment of CVDs, to which various pharmacological activities contribute, including anti-inflammatory, antioxidant, and antitumor effects. This review introduces the roles of triterpenoids in the prevention and treatment of CVDs, summarizes their potential underlying mechanisms, and provides a comprehensive overview of the therapeutic potential of triterpenoids in the management of CVDs.

Ecliptasaponin A protects heart against acute ischemia-induced myocardial injury by inhibition of the HMGB1/TLR4/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Eclipta prostrata (Linn.) is a traditional medicinal Chinese herb that displays multiple biological activities, such as encompassing immunomodulatory, anti-inflammatory, anti-tumor, liver-protective, antioxidant, and lipid-lowering effects. Ecliptasaponin A (ESA), a pentacyclic triterpenoid saponin isolated from Eclipta prostrata (Linn.), has been demonstrated to exert superior anti-inflammatory activity against many inflammatory disorders.

AIM OF THE STUDY

Inflammation plays a critical role in acute myocardial infarction (AMI). This study aims to explore the treatment effects of ESA in AMI, as well as the underlying mechanism.

METHODS

An AMI mouse model was established in mice via left anterior descending coronary artery (LAD) ligation. After surgery, ESA was injected at doses of 0.5, 1.25, and 2.5 mg/kg, respectively. Myocardial infarction size, cardiomyocyte apoptosis and cardiac echocardiography were studied. The potential mechanism of action of ESA was investigated by RNA-seq, Western blot, surface plasmon resonance (SPR), molecular docking, and immunofluorescence staining.

RESULTS

ESA treatment not only significantly reduced myocardial infarct size, decreased myocardial cell apoptosis, and inhibited inflammatory cell infiltration, but also facilitated to improve cardiac function. RNA-seq and Western blot analysis proved that ESA treatment-induced differential expression genes mainly enriched in HMGB1/TLR4/NF-κB pathway. Consistently, ESA treatment resulted into the down-regulation of IL-1β, IL-6, and TNF-α levels after AMI. Furthermore, SPR and molecular docking results showed that ESA could bind directly to HMGB1, thereby impeding the activation of the downstream TLR4/NF-κB pathway. The immunofluorescence staining and Western blot results at the cellular level also demonstrated that ESA inhibited the activation of the HMGB1/TLR4/NF-κB pathway in H9C2 cells.

CONCLUSION

Our study was the first to demonstrate a cardiac protective role of ESA in AMI. Mechanism study indicated that the treatment effects of ESA are mainly attributed to its anti-inflammatory activity that was mediated by the HMGB1/TLR4/NF-κB pathway.

The pathological mechanisms and potential therapeutic drugs for myocardial ischemia reperfusion injury

BACKGROUND

Cardiovascular disease is the main cause of death and disability, with myocardial ischemia being the predominant type that poses a significant threat to humans. Reperfusion, an essential therapeutic approach, promptly reinstates blood circulation to the ischemic myocardium and stands as the most efficacious clinical method for myocardial preservation. Nevertheless, the restoration of blood flow associated with this process can potentially induce myocardial ischemia-reperfusion injury (MIRI), thereby diminishing the effectiveness of reperfusion and impacting patient prognosis. Therefore, it is of great significance to prevent and treat MIRI.

PURPOSE

MIRI is an important factor affecting the prognosis of patients, and there is no specific in-clinic treatment plan. In this review, we have endeavored to summarize its pathological mechanisms and therapeutic drugs to provide more powerful evidence for clinical application.

METHODS

A comprehensive literature review was conducted using PubMed, Web of Science, Embase, Medline and Google Scholar with a core focus on the pathological mechanisms and potential therapeutic drugs of MIRI.

RESULTS

Accumulated evidence revealed that oxidative stress, calcium overload, mitochondrial dysfunction, energy metabolism disorder, ferroptosis, inflammatory reaction, endoplasmic reticulum stress, pyroptosis and autophagy regulation have been shown to participate in the process, and that the occurrence and development of MIRI are related to plenty of signaling pathways. Currently, a range of chemical drugs, natural products, and traditional Chinese medicine (TCM) preparations have demonstrated the ability to mitigate MIRI by targeting various mechanisms.

CONCLUSIONS

At present, most of the research focuses on animal and cell experiments, and the regulatory mechanisms of each signaling pathway are still unclear. The translation of experimental findings into clinical practice remains incomplete, necessitating further exploration through large-scale, multi-center randomized controlled trials. Given the absence of a specific drug for MIRI, the identification of therapeutic agents to reduce myocardial ischemia is of utmost significance. For the future, it is imperative to enhance our understanding of the pathological mechanism underlying MIRI, continuously investigate and develop novel pharmaceutical agents, expedite the clinical translation of these drugs, and foster innovative approaches that integrate TCM with Western medicine. These efforts will facilitate the emergence of fresh perspectives for the clinical management of MIRI.

Glycyrrhizic acid alleviated MI/R-induced injuries by inhibiting Hippo/YAP signaling pathways

BACKGROUND

Previous research has demonstrated that glycyrrhizic acid (GA) exhibits antioxidant, anti-inflammatory, and antiapoptotic characteristics. Using myocardial ischemia/reperfusion injury as a case study, this study aims to clarify the functional significance of GA and to elucidate the mechanisms involved.

MATERIALS AND METHODS

In this study, an MI/R injury model was established both in vivo and in vitro to investigate the impact of GA on MI/R injury. The viability of H9c2 cells was evaluated using the Cell Counting Kit-8. Myocardial damage was assessed through the measurement of creatine kinase myocardial band (CK-MB) levels and lactate dehydrogenase (LDH), HE staining, and MASSON staining. Inflammatory cytokine levels (IL-6, IL-1β, IL-10, and TNF-α) were measured to determine the presence of inflammation. Cellular oxidative stress was evaluated by measuring ROS and MMP levels, while cardiac function was assessed using cardiac color Doppler ultrasound. Immunofluorescence staining to determine the nuclear translocation of YAP, TUNEL to determine apoptosis, and western blotting to determine gene expression.

RESULTS

GA treatment effectively alleviated myocardial injury induced by MI/R, as evidenced by reduced levels of inflammatory cytokines (IL-1β, IL-6, IL-10, and TNF-α) and cardiac biomarkers (CK-MB, LDH) in MI/R rats. Moreover, There was a significant increase in cell viability in vitro after GA treatment and inhibited reactive oxygen species (ROS) during oxidative stress, while also increasing mitochondrial membrane potential (MMP) in vitro. The Western blot findings indicate that GA treatment effectively suppressed apoptosis in both in vivo and in vitro settings. Additionally, GA demonstrated inhibitory effects on the activation of the Hippo/YAP signaling pathway triggered by MI/R and facilitated YAP nuclear translocation both in vitro and in vivo. It has been found, however, in vitro, that silencing the YAP gene negates GA's protective effect against hypoxia/reoxygenation-induced myocardial injury.

CONCLUSION

This study suggests that GA regulates YAP nuclear translocation by inhibiting the Hippo/YAP signaling pathway, which protects ists against MI/R injury. This finding may present a novel therapeutic approach for the treatment of MI/R.

Tannic acid through ROS/TNF-α/TNFR 1 antagonizes atrazine induced apoptosis, programmed necrosis and immune dysfunction of grass carp hepatocytes

Atrazine (ATR) is a commonly used triazine herbicide, which will remain in the water source, soil and biological muscle tissue for a long time, threatening the survival of related organisms and future generations. Tannic acid (TAN), a glucosyl compound found in gallnuts, has previously been shown to antagonize heavy metal toxicity, antioxidant activity, and inflammation. However, it is unclear whether TAN can antagonize ATR-induced Grass carp hepatocytes (L8824 cells) cytotoxicity. Therefore, we treated L8824 cells with 3 μg mL^-1 ATR for 24 h to establish a toxic group model. The experimental data of flow cytometry and AO/EB staining together showed that the ratio of apoptosis and necrosis in L8824 cells after ATR exposure was significantly higher than that in the control group. Furthermore, RT-qPCR showed that inflammatory factors (TNF-α, IL-1β, IL-6, INF-γ) were up-regulated and antimicrobial peptides (hepcidin, β-defensin and LEAP2) were induced down-regulated in L8824 cells, leading to immune dysfunction. The measurement results of oxidative stress-related indicators showed that the levels of ROS and MDA increased after ATR exposure, the overall anti-oxidative system was down-regulated. Western blotting confirmed that TNF-α/TNFR 1-related genes were also up-regulated. This indicates that ATR stimulates oxidative stress in L8824 cells, which in turn promotes the binding of TNF-α to TNFR 1. In addition, TRADD, FADD, Caspase-3, P53, RIP1, RIP3 and MLKL were found to be significantly up-regulated by Western blotting and RT-qPCR. Conditioned after ATR exposure compared to controls. It indicates that ATR activates apoptosis and necrosis of TNF-α/TNFR 1 pathway by inducing oxidative stress in L8824 cells. Furthermore, the use of TAN (5 μM) significantly alleviated the toxic effects of ATR on L8824 cells mentioned above. In conclusion, TAN restrains ATR-induced apoptosis, programmed necrosis and immune dysfunction through the ROS/TNF-α/TNFR 1 pathway.

Effect of Diammonium Glycyrrhizinate in Improving Focal Cerebral Ischemia-Reperfusion Injury in Rats Through Multiple Mechanisms

OBJECTIVE

Acute ischemic stroke is a current major disabling and killer disease worldwide. We aimed to investigate the protective effect and mechanism of diammonium glycyrrhizinate in alleviating acute ischemic stroke.

METHODS

Ninety male Sprague Dawley (SD) rats (weighing 250-300 g) were randomly allocated into three groups: sham operation group (sham group), diammonium glycyrrhizinate group (DG group) and model group (model group) each with 30 individuals. A rat model of focal CIR injury was established by reversible middle cerebral artery occlusion.

RESULTS

Zea-Longa scores for the rats in the DG group and model group were 7-fold and 8-fold higher than those of the sham group 2 h post-surgery (2.90 ± 0.99 vs. 0.30 ± 0.53, P < .05; 2.80 ± 0.61 vs. 0.30 ± 0.53, P < .05, respectively). Three days after model establishment, the scores of DG group were 26.92% lower compared with those of the model group (1.90 ± 0.76 vs. 2.60 ± 0.62, P < .05). In addition, compared with the sham group, the number of Nissl bodies and Akt-positive cells in were 27.35% and 30.42% lower in the hippocampus of the DG group (Nissl bodies: 83.40 ± 7.01 vs. 115.60 ± 11.97, p < 0.05; Akt-positive cells: 94.70 ± 8.23 vs. 136.10 ± 10.37, P < .05) and 58.65% and 57.31% lower in the model group (Nissl bodies: 47.80 ± 4.91 vs. 115.60 ± 11.97, P < .05; Akt-positive cells: 58.10 ± 4.98 vs. 136.10 ± 10.37, P < 0.05), respectively. However, the number of Nissl bodies and Akt-positive cells in the hippocampus of DG group were 74.48% and 62.9% higher compared with the model group, respectively (Nissl bodies: 83.40 ± 7.01 vs. 47.80 ± 4, P < 0.05; Akt-positive cells: 94.70 ± 8.23 vs. 58.10 ± 4.98, P < .05). In addition, compared with the sham group, the number of caspase-3-positive cells, the expression level of p38 mitogen-activated protein kinase (MAPK) and the expression of matrix metallopeptidase 9 (MMP-9) were 2-fold, 34.38%, 64.78% higher in the DG group (caspase-3-positive cells: 78.70 ± 6.52 vs. 27.10 ±3.00, P < .05; p-38MAPK: 0.43 ± 0.15 vs. 0.32 ± 0.10, P < .05; MMP-9: 14.83 ± 1.18 vs. 9.00 ± 2.05, P < .05, respectively), and more than 3-fold, 1-fold and 1-fold higher in model group (caspase-3-positive cells: 121.10 ± 11.04 vs. 27.10 ± 3.00, P < .05; p-38MAPK: 0.70 ± 0.12 vs. 0.32 ± 0.10, P < .05; MMP-9: 19.00 ± 1.90 vs. 9.00 ± 2.05, P < .05), respectively. However, the number of caspase-3-positive cells and the expression levels of p-38MAPK and MMP-9 were 35.01%, 38.57% and 28.12% lower in DG group compared with the model group (caspase-3-positive cells: 78.70 ± 6.52 vs. 121.10 ± 11.04, P < .05; p-38MAPK: 0.43 ± 0.15 vs. 0.70 ± 0.12, P < .05; MMP-9: 14.83 ± 1.18 vs. 19.00 ± 1.90, P < .05).

CONCLUSIONS

Our study showed that diammonium glycyrrhizinate at 20 mg/kg/day had a protective effect on cerebral ischemia-reperfusion injury in rats by promoting formation of Nissl bodies and increasing protein expression of Akt while decreasing that of caspase-3, p38 MAPK and MMP-9, either directly or indirectly, by inhibiting apoptosis and reducing neuroinflammation. All these mechanisms resulted in improved overall neurological function.

Inhibition of Myocardial Cell Apoptosis Is Important Mechanism for Ginsenoside in the Limitation of Myocardial Ischemia/Reperfusion Injury

Ischemic heart disease has a high mortality, and the recommended therapy is reperfusion. Nevertheless, the restoration of blood flow to ischemic tissue leads to further damage, namely, myocardial ischemia/reperfusion injury (MIRI). Apoptosis is an essential pathogenic factor in MIRI, and ginsenosides are effective in inhibiting apoptosis and alleviating MIRI. Here, we reviewed published studies on the anti-apoptotic effects of ginsenosides and their mechanisms of action in improving MIRI. Each ginsenoside can regulate multiple pathways to protect the myocardium. Overall, the involved apoptotic pathways include the death receptor signaling pathway, mitochondria signaling pathway, PI3K/Akt signaling pathway, NF-κB signaling pathway, and MAPK signaling pathway. Ginsenosides, with diverse chemical structures, regulate different apoptotic pathways to relieve MIRI. Summarizing the effects and mechanisms of ginsenosides contributes to further mechanism research studies and structure–function relationship research studies, which can help the development of new drugs. Therefore, we expect that this review will highlight the importance of ginsenosides in improving MIRI via anti-apoptosis and provide references and suggestions for further research in this field.

Exosomal miR-455-3p from BMMSCs prevents cardiac ischemia-reperfusion injury

OBJECTIVE

Bone marrow mesenchymal stem cells (BMMSCs) exert protective effects against myocardial infarction (MI). Here, we focused on the function and mechanism of miR-455-3p from BMMSCs-derived exosomes (BMMSCs-Exo) in myocardial infarction.

MATERIALS AND METHODS

BMMSCs were isolated from rat bone marrow, and the exosomes from the culture medium of BMMSCs were separated, and administered to H9C2 cells under hypoxia-reperfusion (H/R) stimulation. MTT and TUNEL staining analyzed cell viability and apoptosis, respectively. RT-qPCR determined miR-455-3p expression. Apoptosis-related proteins, autophagy-associated proteins, and the MEKK1-MKK4-JNK signaling pathway were detected. The interaction between miR-455-3p and MEKK1 was confirmed through dual luciferase activity and RIP assay. An in vivo ischemia reperfusion (I/R) model was established in rats. 2, 3, 5 triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining, Masson staining, and TUNEL staining evaluated the infarct volume and histopathological changes.

RESULTS

miR-455-3p's expression was down-regulated in BMMSCs-derived exosomes, I/R myocardial tissues, and H/R myocardial cells. miR-455-3p enriched by BMMSC exosomes reduced H/R-mediated cardiomyocyte damage and death-related autophagy. miR-455-3p upregulation suppressed MEKK1-MKK4-JNK. MEKK1 overexpression notably mitigated cell apoptosis, cramped cell viability, suppressed autophagy expansion, and attenuated Exo-miR-455-3p's protection on H/R myocardial cells. In-vivo trials reflected that BMMSC exosomes enriched with miR-455-3p repressed ischemia reperfusion-induced myocardial damage and myocardial cell function.

CONCLUSION

miR-455-3p, shuttled by exosomes from MSCs, targets the MEKK1-MKK4-JNK signaling pathway to guard against myocardial ischemia-reperfusion damage.