Roles of Autophagy in Ischemic Heart Diseases and the Modulatory Effects of Chinese Herbal Medicine

Autophagy of naïve CD4+ T cells in aging - the role of body adiposity and physical fitness

Life expectancy has increased exponentially in the last century accompanied by disability, poor quality of life, and all-cause mortality in older age due to the high prevalence of obesity and physical inactivity in older people. Biologically, the aging process reduces the cell's metabolic and functional efficiency, and disrupts the cell's anabolic and catabolic homeostasis, predisposing older people to many dysfunctional conditions such as cardiovascular disease, neurodegenerative disorders, cancer, and diabetes. In the immune system, aging also alters cells' metabolic and functional efficiency, a process known as 'immunosenescence', where cells become more broadly inflammatory and their functionality is altered. Notably, autophagy, the conserved and important cellular process that maintains the cell's efficiency and functional homeostasis may protect the immune system from age-associated dysfunctional changes by regulating cell death in activated CD4+ T cells. This regulatory process increases the delivery of the dysfunctional cytoplasmic material to lysosomal degradation while increasing cytokine production, proliferation, and differentiation of CD4+ T cell-mediated immune responses. Poor proliferation and diminished responsiveness to cytokines appear to be ubiquitous features of aged T cells and may explain the delayed peak in T cell expansion and cytotoxic activity commonly observed in the 'immunosenescence' phenotype in the elderly. On the other hand, physical exercise stimulates the expression of crucial nutrient sensors and inhibits the mechanistic target of the rapamycin (mTOR) signaling cascade which increases autophagic activity in cells. Therefore, in this perspective review, we will first contextualize the overall view of the autophagy process and then, we will discuss how body adiposity and physical fitness may counteract autophagy in naïve CD4+ T cells in aging.

Chinese Herbal Medicine as an Adjunctive Therapy Improves the Survival Rate of Patients with Ischemic Heart Disease: A Nationwide Population-Based Cohort Study

Background

Ischemic heart disease (IHD) related to cardiovascular or cerebrovascular disease is the leading cause of mortality and an important issue of public health worldwide. The cost of long-term healthcare for IHD patients may result in a huge financial burden.

Objectives

To analyze the medical expenditure incurred for and survival of IHD patients treated with Chinese herbal medicine (CHM) and Western medicine.

Methods

Subjects were randomly selected from the National Health Insurance Research Database in Taiwan. The Cox proportional hazards regression model, Kaplan–Meier estimator, logrank test, chi-square test, and analysis of variance were applied. Landmark analysis was used to assess the cumulative incidence of death in IHD patients.

Results

We identified 11,527 users of CHM combined with Western medicine and 11,527 non-CHM users. CHM users incurred a higher medical expenditure for outpatient care within 1 (24,529 NTD versus 18,464 NTD, P value <0.0001) and 5 years (95,345 NTD versus 60,367 NTD, P value <0.0001). However, CHM users had shorter hospitalizations and lower inpatient medical expenditure (7 days/43,394 NTD in 1 year; 11 days/83,141 NTD in 5 years) than non-CHM users (11 days/72,939 NTD in 1 year; 14 days/107,436 NTD in 5 years). The CHM group's adjusted hazard ratio for mortality was 0.41 lower than that of the non-CHM group by Cox proportional hazard models with time-dependent exposure covariates. Danshen, Huang qi, Niu xi, Da huang, and Fu zi were the most commonly prescribed Chinese single herbs; Zhi-Gan-Cao-Tang, Xue-Fu-Zhu-Yu-Tang, Tian-Wang-Bu-Xin-Dan, Sheng-Mai-San, and Yang-Xin-Tang were the five most frequently prescribed herbal formulas in Taiwan.

Conclusions

Combining Chinese and Western medicine can reduce hospital expenditure and improve survival for IHD patients.

Pharmacodynamic Mechanism of Kuanxiong Aerosol for Vasodilation and Improvement of Myocardial Ischemia

OBJECTIVE

To explore the effect of Kuanxiong Aerosol (KXA) on isoproterenol (ISO)-induced myocardial injury in rat models.

METHODS

Totally 24 rats were radomly divided into control, ISO, KXA low-dose and high-dose groups according to the randomized block design method, and were administered by intragastric administration for 10 consecutive days, and on the 9th and 10th days, rats were injected with ISO for 2 consecutive days to construct an acute myocardial ischemia model to evaluate the improvement of myocardial ischemia by KXA. In addition, the diastolic effect of KXA on rat thoracic aorta and its regulation of ion channels were tested by in vitro vascular tension test. The influence of KXA on the expression of calcium-CaM-dependent protein kinase II (CaMK II)/extracellular regulated protein kinases (ERK) signaling pathway has also been tested.

RESULTS

KXA significantly reduced the ISO-induced increase in ST-segment, interventricular septal thickness, cardiac mass index and cardiac tissue pathological changes in rats. Moreover, the relaxation of isolated thoracic arterial rings that had been precontracted using norepinephrine (NE) or potassium chloride (KCl) was increased after KXA treatment in an endothelium-independent manner, and was attenuated by preincubation with verapamil, but not with tetraethylammonium chloride, 4-aminopyridine, glibenclamide, or barium chloride. KXA pretreatment attenuated vasoconstriction induced by CaCl2 in Ca2+-free solutions containing K+ or NE. In addition, KXA pretreatment inhibited accumulation of Ca2+ in A7r5 cells mediated by KCl and NE and significantly decreased p-CaMK II and p-ERK levels.

CONCLUSION

KXA may inhibit influx and release of calcium and activate the CaMK II/ERK signaling pathway to produce vasodilatory effects, thereby improving myocardial injury.

Ferroptosis-Specific Inhibitor Ferrostatin-1 Relieves H2O2-Induced Redox Imbalance in Primary Cardiomyocytes through the Nrf2/ARE Pathway

Objective

Ischemic heart disease (IHD) has always been the focus of attention of many researchers in cardiovascular disease, and its pathogenesis is also very complicated. Ferroptosis may be involved in the occurrence and development of IHD.

Methods

First, primary cardiomyocytes were treated with H₂O₂ to simulate the IHD in vitro model. After pretreatment with different concentrations of ferrostatin-1, cell survival rate was detected by MTT method, cell apoptosis was detected by TUNEL staining and flow cytometry, and the expression of oxidative stress, ferroptosis, and related molecules of Nrf2/ARE pathway was detected by Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The mortality of primary cardiomyocytes in the H₂O₂ group was obviously increased. Ferrostatin-1 treatment can effectively inhibit cell death, improve antioxidant enzyme activity, inhibit the expression of ferroptosis-related molecules, and activate Nrf2/ARE pathway expression.

Conclusion

Ferroptosis-specific inhibitor ferrostatin-1 relieves H₂O₂-induced redox imbalance in primary cardiomyocytes through the Nrf2/ARE pathway, inhibits ferroptosis, and thereby slows cardiomyocyte death.

Chinese Herbal Medicine Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating Endoplasmic Reticulum Stress

Myocardial ischemia/reperfusion injury is the main cause of increased mortality and disability in cardiovascular diseases. The injury involves many pathological processes, such as oxidative stress, calcium homeostasis imbalance, inflammation, and energy metabolism disorders, and these pathological stimuli can activate endoplasmic reticulum stress. In the early stage of ischemia, endoplasmic reticulum stress alleviates the injury as an adaptive survival response, but the long-term stress on endoplasmic reticulum amplifies oxidative stress, inflammation, and calcium overload to accelerate cell damage and apoptosis. Therefore, regulation of endoplasmic reticulum stress may be a mechanism to improve ischemia/reperfusion injury. Chinese herbal medicine has a long history of clinical application and unique advantages in the treatment of ischemic heart diseases. This review focuses on the effect of Chinese herbal medicine on myocardial ischemia/reperfusion injury from the perspective of regulation of endoplasmic reticulum stress.

Dingxin Recipe IV attenuates atherosclerosis by regulating lipid metabolism through LXR-α/SREBP1 pathway and modulating the gut microbiota in ApoE-/- mice fed with HFD

ETHNOPHARMACOLOGICAL RELEVANCE

Dingxin Recipe (DXR) is a traditional Chinese medicine formula that has been reported to be effective and safe treatment for cardiovascular diseases, such as arrhythmias, coronary heart disease. Dingxin Recipe IV (DXR IV) was further improved from the DXR according to the traditional use. However, the mechanism of DXR IV in atherosclerosis is unclear.

AIM OF THE STUDY

This study aimed to illustrate whether DXR IV improve atherosclerosis through modulating the lipid metabolism and gut microbiota in atherosclerosis mice.

MATERIALS AND METHODS

40 male ApoE^-/- mice were fed on HFD for 12 weeks and were then treated with DXR IV (1.8, 0.9, or 0.45 g/kg/d) for another 12 weeks. The decroation of DXR IV contains four traditional Chinese medicines: the dried rhizome of Coptis chinensis Franch. (15.09%), the root of Salvia miltiorrhiza Bunge (28.30%), the seed of Ziziphus jujuba Mill. (37.74%) and the fruiting body of Ganoderma lucidum (Leyss.ex Fr.) Karst. (18.87%). 8 male c57BL/6 mice fed a normal diet served as control group. The atherosclerotic plaque was quantified by oil-red O staining and masson trichrome staining. Mice feces were collected. The gut micobiota were detected by 16S rRNA gene sequencing and fecal metabolites were analyzed by ¹H NMR spectroscopy. The effect of DXR IV on blood lipids (TG, TC, LDL-C, HDL-C) was investigated. The lipid metabolism related genes were determined by RT-qPCR and western blotting respectively.

RESULTS

DXR IV exerted the anti-atherosclerosis effect by inhibiting the excessive cholesterol deposition in aorta and regulating the level of TG, TC, LDL-C and HDL-C. The composition of gut microbiota was changed. Interestingly, the relative abundance of Muribaculaceae and Ruminococcaceae increased after DXR IV administration, whereas the abundance of Erysipelotrichaceae decreased, which have been beneficial to lipid metabolism. Nine potential metabolic biomarkers, including acetate, butyrate, propionate, alanine, succinate, valerate, xylose, choline, glutamate, were identified, which were related to fatty acid metabolism. Further, the pathway of fatty acid was detected by the RT-qPCR and western blotting. Compared with model group, the level of LXR-α and SREBP1 decreased significantly in DXR IV group while LXR-β, SREBP2 showed no statistical significance. It indicated that DXR IV modulated lipid metabolism by LXR-α/SREBP1 but not LXRβ and SREBP2.

CONCLUSIONS

DXR IV exhibits potential anti-atherosclerosis effect, which is closely related to lipid metabolism and the gut microbiota. This study may provide novel insights into the mechanism of DXR IV on atherosclerosis and a basis for promising clinical usage.

Paeonol Protects Against Myocardial Ischemia/Reperfusion-Induced Injury by Mediating Apoptosis and Autophagy Crosstalk

Many studies have shown that crosstalk exists between apoptosis and autophagy, despite differences in mechanisms between these processes. Paeonol, a major phenolic compound isolated from Moutan Cortex Radicis, the root bark of Paeonia × suffruticosa Andrews (Paeoniaceae), is widely used in traditional Chinese medicine as an antipyretic, analgesic and anti-inflammatory agent. In this study, we investigated the detailed molecular mechanisms of the crosstalk between apoptosis and autophagy underlying the cardioprotective effects of paeonol in rats subjected to myocardial ischemia/reperfusion (I/R) injury. Myocardial I/R injury was induced by occlusion of the left anterior descending coronary artery (LAD) for 1 h followed by 3 h of reperfusion. Paeonol was intravenously administered 15 min before LAD ligation. We found that paeonol significantly improved cardiac function after myocardial I/R injury and significantly decreased myocardial I/R-induced arrhythmia and mortality. Paeonol also significantly decreased myocardial infarction and plasma LDH activity and Troponin-I levels in carotid blood after I/R. Compared with vehicle treatment, paeonol significantly upregulated Bcl-2 protein expression and significantly downregulated the cleaved forms of caspase-8, caspase-9, caspase-3 and PARP protein expression in the I/R injured myocardium. Myocardial I/R-induced autophagy, including the increase of Beclin-1, p62, LC3-I, and LC3-II protein expression in the myocardium was significantly reversed by paeonol treatment. Paeonol also significantly increased the Bcl-2/Bax and Bcl-2/Beclin-1 ratios in the myocardium after I/R injury. The cardioprotective role of paeonol during I/R injury may be due to its mediation of crosstalk between apoptotic and autophagic signaling pathways, which inhibits apoptosis and autophagic cell death.

A novel danshensu/tetramethypyrazine derivative attenuates oxidative stress-induced autophagy injury via the AMPK-mTOR-Ulk1 signaling pathway in cardiomyocytes

Myocardial ischemia/reperfusion injury (MIRI) is an inevitable and unsolved clinical problem in the treatment of ischemic heart diseases. Compound DT-010 is a novel danshensu/tetramethylpyrazine derivative and was examined as a candidate for treating MIRI. In the present study, MTT, lactate dehydrogenase assay and Hoechst staining data indicated that DT-010 attenuated tert-butylhydroperoxide (t-BHP)-induced oxidative damage by increasing cell survival, reducing cell damage and decreasing apoptosis in H9c2 cardiomyocytes. Autophagy was assessed by western blotting for microtubule-associated protein 1A/1B-light chain 3 (LC3-II and LC3-I) expression, acridine orange and monodansylcadaverine staining for autophagosome formation and the monomeric red fluorescent protein-green fluorescent protein-LC3 assay for autophagic flow. t-BHP-induced cell damage was aggravated by the autophagy agonist rapamycin and alleviated by the autophagy blocker hydroxy-chloroquine, suggesting that autophagy was involved in t-BHP-induced cardiomyocyte injury. DT-010 pretreatment significantly prevented t-BHP-induced cell damage, which was partially but significantly abolished by rapamycin and significantly improved by hydroxy-chloroquine treatment. DT-010 treatment inhibited t-BHP-induced autophagy in H9c2 cells, reduced phosphorylation of 5'-AMP-activated protein kinase (AMPK) and promoted the phosphorylation of mTOR and unc-51 like autophagy activating kinase 1 (Ulk1). To conclude, DT-010 can serve as a potential candidate for myocardial ischemia-reperfusion injury therapy. The cardioprotective effects of DT-010 could be partially attributed to its inhibition of autophagy via the AMPK-mTOR-Ulk1 signaling pathway.

Interplay between Exosomes and Autophagy in Cardiovascular Diseases: Novel Promising Target for Diagnostic and Therapeutic Application

Exosome, is identified as a nature nanocarrier and intercellular messenger that regulates cell to cell communication. Autophagy is critical in maintenance of protein homeostasis by degradation of damaged proteins and organelles. Autophagy and exosomes take pivotal roles in cellular homeostasis and cardiovascular disease. Currently, the coordinated mechanisms for exosomes and autophagy in the maintenance of cellular fitness are now garnering much attention. In the present review, we discussed the interplay of exosomes and autophagy in the context of physiology and pathology of the heart, which might provide novel insights for diagnostic and therapeutic application of cardiovascular diseases.

The role of traditional Chinese medicine in the treatment of atherosclerosis through the regulation of macrophage activity

Atherosclerosis (AS) is the main cause of ischemic cardiovascular, cerebrovascular and peripheral vascular diseases. Macrophage activity has been proven to play a critical role during the AS pathological process, which involves the adhesion, aggregation of mononuclear-macrophages, cell differentiation of M1/M2 macrophages as part of complex mechanisms occurring during lipid metabolism, apoptosis, autophagy, inflammation and immune reaction. Therefore, the development of effective AS treatments is likely to target macrophage activity. Certain herbal extracts (such as Salvia miltiorrhiza) have exhibited enormous potential for AS treatment in the past. Here, we aim to provide a summary on the current understanding of the type of action and the underlying target/pathway in macrophage regulation of certain herbal extracts used in Traditional Chinese Medicine for treatment of AS.

Ginkgo Biloba Leaf Extract Attenuates Atherosclerosis in Streptozotocin-Induced Diabetic ApoE-/- Mice by Inhibiting Endoplasmic Reticulum Stress via Restoration of Autophagy through the mTOR Signaling Pathway

Background

There is a crosstalk between endoplasmic reticulum stress (ERS) and autophagy, and autophagy could attenuate endoplasmic reticulum stress-mediated apoptosis. Ginkgo biloba leaf extract (GBE) exerts vascular protection functions. The purpose of the present study is to investigate the role of autophagy in diabetic atherosclerosis (AS) and the effect of GBE on autophagy and ERS.

Methods

Network pharmacology was utilized to predict the targets and pathways of the active chemical compounds of Gingko biloba leaf to attenuate AS. ApoE^−/− mice were rendered diabetic by intraperitoneal ingestion with streptozotocin combined with a high-fat diet. The diabetic mice were divided into five groups: model group, atorvastatin group, rapamycin group, and low- and high-dose GBE groups. Serum and tissue markers of autophagy or ERS markers, including the protein expression, were examined.

Results

The mammalian target of rapamycin (mTOR) and NF-κB signaling pathways were targeted by the active chemical compounds of GBE to attenuate AS predicted by network pharmacology. GBE reduced the plaque area/lumen area and the plaque lipid deposition area/intimal area and inhibited the expressions of CD68, MMP2, and MMP9. Rapamycin and GBE inhibited the expression of mTOR and SQSTM1/p62 which increased in the aorta of diabetic mice. In addition, GBE reduced the expression of ERS markers in diabetic mice. GBE reduced the serum lipid metabolism levels, blood glucose, and inflammatory cytokines.

Conclusion

Impaired autophagy and overactive endoplasmic reticulum stress contributed to diabetic atherosclerosis. mTOR inhibitor rapamycin and GBE attenuated diabetic atherosclerosis by inhibiting ERS via restoration of autophagy through inhibition of mTOR.

Targeting autophagy in cardiac ischemia/reperfusion injury: A novel therapeutic strategy

Acute myocardial infarction (AMI) is one of the leading causes of morbidity worldwide. Myocardial reperfusion is known as an effective therapeutic choice against AMI. However, reperfusion of blood flow induces ischemia/reperfusion (I/R) injury through different complex processes including ion accumulation, disruption of mitochondrial membrane potential, the formation of reactive oxygen species, and so forth. One of the processes that gets activated in response to I/R injury is autophagy. Indeed, autophagy acts as a "double-edged sword" in the pathology of myocardial I/R injury and there is a controversy about autophagy being beneficial or detrimental. On the basis of the autophagy effect and regulation on myocardial I/R injury, many studies targeted it as a therapeutic strategy. In this review, we discuss the role of autophagy in I/R injury and its targeting as a therapeutic strategy.

Autophagy in Alzheimer's disease and promising modulatory effects of herbal medicine

Alzheimer's disease (AD) is a progressive and unremitting neurodegenerative disorder characterized by memory loss and cognitive impairment. It affects the quality of life of victims severely. The prevalence of AD has been increasing in recent years. Therefore, it is of great importance to elucidate the pathogenesis of AD and find out effective therapeutic approaches. Autophagy, a primary intracellular way of degrading aggregated proteins and damaged organelles, has been discovered to be involved in the pathological changes of AD. In the last few years, much progress has been made in finding autophagy regulators from natural products, providing new insights to develop treatment strategy for AD by targeting autophagy. In the present review, we provided an overview of the recent research progress regarding the function role of autophagy in AD, the regulation mechanisms of autophagy-lysosomal pathway as well as therapeutic potential of herbal medicine on AD by targeting autophagy.

The relationship between autophagy and the immune system and its applications for tumor immunotherapy

Autophagy is a genetically well-controlled cellular process that is tightly controlled by a set of core genes, including the family of autophagy-related genes (ATG). Autophagy is a “double-edged sword” in tumors. It can promote or suppress tumor development, which depends on the cell and tissue types and the stages of tumor. At present, tumor immunotherapy is a promising treatment strategy against tumors. Recent studies have shown that autophagy significantly controls immune responses by modulating the functions of immune cells and the production of cytokines. Conversely, some cytokines and immune cells have a great effect on the function of autophagy. Therapies aiming at autophagy to enhance the immune responses and anti-tumor effects of immunotherapy have become the prospective strategy, with enhanced antigen presentation and higher sensitivity to CTLs. However, the induction of autophagy may also benefit tumor cells escape from immune surveillance and result in intrinsic resistance against anti-tumor immunotherapy. Increasing studies have proven the optimal use of either ATG inducers or inhibitors can restrain tumor growth and progression by enhancing anti-tumor immune responses and overcoming the anti-tumor immune resistance in combination with several immunotherapeutic strategies, indicating that induction or inhibition of autophagy might show us a prospective therapeutic strategy when combined with immunotherapy. In this article, the possible mechanisms of autophagy regulating immune system, and the potential applications of autophagy in tumor immunotherapy will be discussed.

Herbal Extracts and Natural Products in Alleviating Non-alcoholic Fatty Liver Disease via Activating Autophagy

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease world-wide, and currently therapeutic options for NAFLD are limited. Herbal medicine (HM) may offer an attractive alternative for the treatment of NAFLD. Recent years have witnessed a growing interest in the autophagy-inducing agents, and autophagy activation has been recognized as an efficient strategy in managing NAFLD and related complications. Pharmacological studies have demonstrated certain potential of HM extracts and natural products in inducing autophagy, which might contribute to the efficacy of HM in preventing and treating NAFLD. This review aims to summarize current understanding of mechanisms of HM extracts and natural products in preventing and treating NAFLD. Specially, we focused on mechanisms by which autophagy can target the main pathogenesis events associated with NAFLD, including hepatic steatosis, inflammation, oxidative stress, and apoptosis. It is hoped that this brief review can provide a general understanding of HM extracts and natural products in treating NAFLD, and raise awareness of potential clinical application of HM in general.