Acute Exercise-Induced Mitochondrial Stress Triggers an Inflammatory Response in the Myocardium via NLRP3 Inflammasome Activation with Mitophagy

Acute aerobic exercise regulation of myocardial calcium homeostasis involves CASQ1, CASQ2, and TRDN

Exercise maintains cardiac calcium homeostasis and promotes cardiovascular health. This study explored temporal changes of calcium-related myocardial transcriptome changes during the recovery phase following a single bout of moderate-intensity aerobic exercise. Healthy male Sprague-Dawley rats were anesthetized with sodium pentobarbital after moderate-intensity aerobic exercise at four time points (0, 12, 24, and 72 h postexercise). The hearts were removed and RNA-seq and bioinformatics analyses were used to examine temporal transcriptional changes in the myocardium. Casq1, Casq2, and Trdn were identified as key genes in the regulation of calcium homeostasis during myocardial recovery. The highest expression of Casq1, Casq2, and Trdn genes and the proteins they encode occurred 24 h after exercise. An in vitro calcium overload heart model using the Langendorff heart perfusion method was used to examine myocardial calcium buffering capacity. Calcium overload caused the least changes in left ventricular developed pressure, infarct area, Lactate dehydrogenase release, and extent of morphological damage to myocardial cells, with the highest protein expressions of CASQ1, CASQ2, and TRDN at 24 h after acute exercise. This study indicates that maximal myocardial Ca2+ buffering capacity occurs 24 h postexercise in rats. Our study provides insights into exercise-mediated improvements in cardiovascular function and exercise preconditioning.NEW & NOTEWORTHY Acute aerobic exercise upregulates myocardial Casq1, Casq2, and Trdn genes and the proteins they encode in rats. Higher protein levels of CASQ1, CASQ2, and TRDN conferred an improved ability of the myocardium to resist calcium overload. Furthermore, 24 h postexercise is the time point with optimal myocardial calcium buffer capacity.

The role of mitochondria-associated membranes mediated ROS on NLRP3 inflammasome in cardiovascular diseases

Reactive oxygen species (ROS) metabolism is essential for the homeostasis of cells. Appropriate production of ROS is an important signaling molecule, but excessive ROS production can damage cells. ROS and ROS-associated proteins can act as damage associated molecular pattern molecules (DAMPs) to activate the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in cardiovascular diseases. Previous studies have shown that there are connected sites, termed mitochondria-associated membranes (MAMs), between mitochondria and the endoplasmic reticulum. In cardiovascular disease progression, MAMs play multiple roles, the most important of which is the ability to mediate ROS generation, which further activates the NLPR3 inflammasome, exacerbating the progression of disease. In this review, the following topics will be covered: 1. Molecular structures on MAMs that can mediate ROS generation; 2. Specific mechanisms of molecule-mediated ROS generation and the molecules' roles in cardiovascular disease, 3. The effects of MAMs-mediated ROS on the NLRP3 inflammasome in cardiovascular disease. The purpose of this review is to provide a basis for subsequent clinical treatment development.

Augmenter of liver regeneration reduces mitochondria-derived ROS and NLRP3 inflammasome activation through PINK1/Parkin-mediated mitophagy in ischemia-reperfusion-induced renal tubular injury

Ischemia-reperfusion (IR) injury is one of the main causes of acute kidney disease (AKI). Several studies have shown that mitochondrial damage, which leads to increased production of reactive oxygen species (ROS), plays a vital role in the pathogenesis of IR-induced AKI. Increased ROS production can cause oxidative damage and activate the inflammasome in renal tubular cells, ultimately resulting in apoptosis or necrosis. Mitophagy is a type of selective autophagy that plays a protective role in AKI by regulating the quality of mitochondria and reducing the production of ROS. We previously reported that the augmenter of liver regeneration (ALR) exhibits antiapoptotic and antioxidant functions, although the precise mechanisms of action need to be studied further. In the current study, ALR was overexpressed and an in vitro model of IR injury was constructed. The overexpression of ALR reduced the production of mitochondria-derived ROS (mtROS), the activation of the NLRP3 inflammasome, and the rate of apoptosis. Moreover, this suppression of mtROS production and inflammasome activation was mediated through the PTEN-induced kinase 1 (PINK1)/Parkin pathway of mitophagy. These results suggest that ALR can alleviate IR-induced apoptosis via the PINK1/Parkin mitophagy pathway to reduce the production of mtROS and limit the activation of the NLRP3 inflammasome.

Ameliorative effects of high intensity interval training and Lactobacillus rhamnosus GG Protect against tetracycline-induced fatty liver in rats: a gene expression profiling comparative study

Exercise training and probiotics have been suggested as a treatment for the prevention of chronic liver damage such as non-alcoholic fatty liver disease (NAFLD). Lactobacillus rhamnosus Gorbach - Goldin (LGG) is one of the most widely used probiotic strains that decreases liver damage. Thus, this study aims to consider the ameliorative effects of high intensity interval training (HIIT) and LGG against tetracycline-induced fatty liver in rats. Eighty male Wistar rats were randomly divided into 8 groups of (n=10 each group): control, LGG, HIIT, LGG+HIIT, NAFLD, NAFLD+LGG, NAFLD+HIIT, and NAFLD+LGG+HIIT. The rats are treated by intraperitoneal injection with 140 mg/kg^-1 tetracycline, an antibiotic previously known to induce steatosis. The exercise training groups performed HIIT 5 days/week for 5 weeks. 10⁷ colony-forming units (cfu) of LGG were gavaged for LGG groups 5 days/week for 5 weeks. Probiotic supplementation in combination with interval training significantly decreased tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) mRNA and matrix metalloproteinase-2 (MMP-2) mRNA in the liver (p<0.05), while the levels of lysosomal acid lipase (LIPA) mRNA was significantly increased compared to NAFLD group. Also, compared with NAFLD group, NAFLD+LGG, NAFLD+HIIT and NAFLD+LGG+HIIT groups showed a significant decrease in hepatic monocyte chemoattractant protein-1 (MCP-1). Compared to LGG and LGG+HIIT groups, all NAFLD groups showed a significant decrease in apolipoprotein C3 (apoc3) in liver tissue (p<0.05). The results suggested that interval exercise with LGG supplementation minimizes cell destruction and inflammation in liver tissue due to NAFLD by improving gene expression profiles.

Role of Mitophagy in neurodegenerative Diseases and potential tagarts for Therapy

Mitochondria dysfunction has been defined as one of the hallmarks of aging-related diseases as is characterized by the destroyed integrity, abnormal distribution and size, insufficient ATP supply, increased ROS production, and subsequently damage and oxidize the proteins, lipids and nucleic acid. Mitophagy, an efficient way of removing damaged or defective mitochondria by autophagy, plays a pivotal role in maintaining the mitochondrial quantity and quality control enabling the degradation of unwanted mitochondria, and thus rescues cellular homeostasis in response to stress. Accumulating evidence demonstrates that impaired mitophagy has been associated with many neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD), amyotrophic lateral sclerosis (ALS) in a variety of patients and disease models with neural death, oxidative stress and disturbed metabolism, either as the cause or consequence. These findings suggest that modulation of mitophagy may be considered as a valid therapeutic strategy in neurodegenerative diseases. In this review, we summarize recent findings on the mechanisms of mitophagy and its role in neurodegenerative diseases, with a particular focus on mitochondrial proteins acting as receptors that mediate mitophagy in these diseases.

Extracellular Inflammasome Particles Are Released After Marathon Running and Induce Proinflammatory Effects in Endothelial Cells

Objectives: The intracellular NLRP3 inflammasome is an important regulator of sterile inflammation. Recent data suggest that inflammasome particles can be released into circulation. The effects of exercise on circulating extracellular apoptosis-associated speck-like protein (ASC) particles and their effects on endothelial cells are not known.

Methods: We established a flow cytometric method to quantitate extracellular ASC specks in human serum. ASC specks were quantitated in 52 marathon runners 24–72 h before, immediately after, and again 24–58 h after the run. For mechanistic characterization, NLRP3 inflammasome particles were isolated from a stable mutant NLRP3 (p.D303N)-YFP HEK cell line and used to treat primary human coronary artery endothelial cells.

Results: Athletes showed a significant increase in serum concentration of circulating ASC specks immediately after the marathon (+52% compared with the baseline, p < 0.05) and a decrease during the follow-up after 24–58 h (12% reduction compared with immediately after the run, p < 0.01). Confocal microscopy revealed that human endothelial cells can internalize extracellular NLRP3 inflammasome particles. After internalization, endothelial cells showed an inflammatory response with a higher expression of the cell adhesion molecule ICAM1 (6.9-fold, p < 0.05) and increased adhesion of monocytes (1.5-fold, p < 0.05).

Conclusion: These findings identify extracellular inflammasome particles as novel systemic mediators of cell–cell communication that are transiently increased after acute extensive exercise with a high mechanical muscular load.

Compositions and Functions of Mitochondria-Associated Endoplasmic Reticulum Membranes and Their Contribution to Cardioprotection by Exercise Preconditioning

Mitochondria-associated endoplasmic reticulum membranes (MAMs) are important components of intracellular signaling and contribute to the regulation of intracellular Ca²⁺/lipid homeostasis, mitochondrial dynamics, autophagy/mitophagy, apoptosis, and inflammation. Multiple studies have shown that proteins located on MAMs mediate cardioprotection. Exercise preconditioning (EP) has been shown to protect the myocardium from adverse stimuli, but these mechanisms are still being explored. Recently, a growing body of evidence points to MAMs, suggesting that exercise or EP may be involved in cardioprotection by modulating proteins on MAMs and subsequently affecting MAMs. In this review, we summarize the latest findings on MAMs, analyzing the structure and function of MAMs and the role of MAM-related proteins in cardioprotection. We focused on the possible mechanisms by which exercise or EP can modulate the involvement of MAMs in cardioprotection. We found that EP may affect MAMs by regulating changes in MFN2, MFN1, AMPK, FUNDC1, BECN1, VDAC1, GRP75, IP3R, CYPD, GSK3β, AKT, NLRP3, GRP78, and LC3, thus playing a cardioprotective role. We also provided direction for future studies that may be of interest so that more in-depth studies can be conducted to elucidate the relationship between EP and cardioprotection.

Inflammation: A New Look at an Old Problem

Pro-inflammatory stress is inherent in any cells that are subject to damage or threat of damage. It is defined by a number of universal components, including oxidative stress, cellular response to DNA damage, unfolded protein response to mitochondrial and endoplasmic reticulum stress, changes in autophagy, inflammasome formation, non-coding RNA response, formation of an inducible network of signaling pathways, and epigenetic changes. The presence of an inducible receptor and secretory phenotype in many cells is the cause of tissue pro-inflammatory stress. The key phenomenon determining the occurrence of a classical inflammatory focus is the microvascular inflammatory response (exudation, leukocyte migration to the alteration zone). This same reaction at the systemic level leads to the development of life-critical systemic inflammation. From this standpoint, we can characterize the common mechanisms of pathologies that differ in their clinical appearance. The division of inflammation into alternative variants has deep evolutionary roots. Evolutionary aspects of inflammation are also described in the review. The aim of the review is to provide theoretical arguments for the need for an up-to-date theory of the relationship between key human pathological processes based on the integrative role of the molecular mechanisms of cellular and tissue pro-inflammatory stress.

Regulation of Mitochondrial Dynamics by Aerobic Exercise in Cardiovascular Diseases

Mitochondrial dynamics, including continuous biogenesis, fusion, fission, and autophagy, are crucial to maintain mitochondrial integrity, distribution, size, and function, and play an important role in cardiovascular homeostasis. Cardiovascular health improves with aerobic exercise, a well-recognized non-pharmaceutical intervention for both healthy and ill individuals that reduces overall cardiovascular disease (CVD) mortality. Increasing evidence shows that aerobic exercise can effectively regulate the coordinated circulation of mitochondrial dynamics, thus inhibiting CVD development. This review aims to illustrate the benefits of aerobic exercise in prevention and treatment of cardiovascular disease by modulating mitochondrial function.

NLRP3 Inflammasome in Diabetic Cardiomyopathy and Exercise Intervention

Diabetic cardiomyopathy (DCM), as a common complication of diabetes, is characterized by chronic low-grade inflammation. The NLRP3 inflammasome is a key sensor mediating innate immune and inflammatory responses. However, the mechanisms initiating and promoting NLRP3 inflammasome activation in DCM is largely unexplored. The aim of the present review is to describe the link between NLRP3 inflammasome and DCM, and to provide evidence highlighting the importance of exercise training in DCM intervention. Collectively, this evidence suggests that DCM is an inflammatory disease aggravated by NLRP3 inflammasome-mediated release of IL-1β and IL-18. In addition, chronic exercise intervention is an effective preventive and therapeutic method to alleviate DCM via modulating the NLRP3 inflammasome.

Oxidative Stress, Mitochondrial Function and Adaptation to Exercise: New Perspectives in Nutrition

Cells have the ability to adapt to stressful environments as a part of their evolution. Physical exercise induces an increase of a demand for energy that must be met by mitochondria as the main (ATP) provider. However, this process leads to the increase of free radicals and the so-called reactive oxygen species (ROS), which are necessary for the maintenance of cell signaling and homeostasis. In addition, mitochondrial biogenesis is influenced by exercise in continuous crosstalk between the mitochondria and the nuclear genome. Excessive workloads may induce severe mitochondrial stress, resulting in oxidative damage. In this regard, the objective of this work was to provide a general overview of the molecular mechanisms involved in mitochondrial adaptation during exercise and to understand if some nutrients such as antioxidants may be implicated in blunt adaptation and/or an impact on the performance of exercise by different means.

The mitochondrial signaling peptide MOTS-c improves myocardial performance during exercise training in rats

Cardiac remodeling is a physiological adaptation to aerobic exercise and which is characterized by increases in ventricular volume and the number of cardiomyocytes. The mitochondrial derived peptide MOTS-c functions as an important regulator in physical capacity and performance. Exercise elevates levels of endogenous MOTS-c in circulation and in myocardium, while MOTS-c can significantly enhance exercise capacity. However, the effects of aerobic exercise combined with MOTS-c on cardiac structure and function are unclear. We used pressure–volume conductance catheter technique to examine cardiac function in exercised rats with and without treatment with MOTS-c. Surprisingly, MOTS-c improved myocardial mechanical efficiency, enhanced cardiac systolic function, and had a tendency to improve the diastolic function. The findings suggest that using exercise supplements could be used to modulate the cardiovascular benefits of athletic training.

Advances in Cardiotoxicity Induced by Altered Mitochondrial Dynamics and Mitophagy

Mitochondria are the most abundant organelles in cardiac cells, and are essential to maintain the normal cardiac function, which requires mitochondrial dynamics and mitophagy to ensure the stability of mitochondrial quantity and quality. When mitochondria are affected by continuous injury factors, the balance between mitochondrial dynamics and mitophagy is broken. Aging and damaged mitochondria cannot be completely removed in cardiac cells, resulting in energy supply disorder and accumulation of toxic substances in cardiac cells, resulting in cardiac damage and cardiotoxicity. This paper summarizes the specific underlying mechanisms by which various adverse factors interfere with mitochondrial dynamics and mitophagy to produce cardiotoxicity and emphasizes the crucial role of oxidative stress in mitophagy. This review aims to provide fresh ideas for the prevention and treatment of cardiotoxicity induced by altered mitochondrial dynamics and mitophagy.

New Insights into Molecular Mechanisms Mediating Adaptation to Exercise; A Review Focusing on Mitochondrial Biogenesis, Mitochondrial Function, Mitophagy and Autophagy

Exercise itself is fundamental for good health, and when practiced regularly confers a myriad of metabolic benefits in a range of tissues. These benefits are mediated by a range of adaptive responses in a coordinated, multi-organ manner. The continued understanding of the molecular mechanisms of action which confer beneficial effects of exercise on the body will identify more specific pathways which can be manipulated by therapeutic intervention in order to prevent or treat various metabolism-associated diseases. This is particularly important as exercise is not an available option to all and so novel methods must be identified to confer the beneficial effects of exercise in a therapeutic manner. This review will focus on key emerging molecular mechanisms of mitochondrial biogenesis, autophagy and mitophagy in selected, highly metabolic tissues, describing their regulation and contribution to beneficial adaptations to exercise.

Post-Effort Changes in Autophagy- and Inflammation-Related Gene Expression in White Blood Cells of Healthy Young Men

Acute, strenuous physical exertion requiring high levels of energy production induces the production of reactive oxygen species and metabolic disturbances that can damage the mitochondria. Thus, selective autophagic elimination of defective mitochondria may improve resistance to oxidative stress and potentially to inflammation. The main goal of this study was to evaluate the impacts of intense effort on changes in the expression of select genes related to post-effort inflammation and autophagy. Thirty-five men aged 16–21 years were recruited to the study. The impacts of both aerobic (endurance) and anaerobic (speed) efforts on selected genes encoding chemokines (CXCL5, 8–12) were analyzed. Significant increases in the expression of all studied genes excluding CXCL12 were observed. Moreover, both types of effort induced an increase in the expression of genes encoding IL-2, -4, -6, -10, IFN-γ and TNF-α, excluding IL-17A. Generally, these efforts caused a significant increase in the relative expression of apoptosis- (BCL2 and BAX) and autophagy- (BNIP3, BECN1, MAP1LC3B, ATG5, ATG7, ATG12, ATG16L1 and SQSTM1) related genes. It seems that the duration of physical activity and its bioenergetic cost has an important impact on the degree of increase in expression of this panel of autophagy-related genes. Anaerobic effort is more strenuous than aerobic effort and requires a higher bioenergetic investment. This may explain the stronger impact of anaerobic effort on the expression of the studied genes. This observation seems to support the protective role of autophagy proposed in prior studies.

Exercise suppresses NLRP3 inflammasome activation in mice with diet-induced NASH: a plausible role of adropin

NLRP3 inflammasome activation, which can be triggered by reactive oxygen species (ROS), contributes to nonalcoholic steatohepatitis (NASH) progression. Exercise is an effective therapeutic strategy for NASH. However, whether exercise prevents NLRP3 activation in NASH has not been investigated. Here, we investigated the effect of exercise on NLRP3 inflammasome in mice with high-fat diet (HFD)-induced or methionine and choine-deficient (MCD) diet-induced NASH and explored whether adropin, a metabolic peptide hormone shown to inhibit inflammation, mediates an exercise-induced benefit against NLRP3 inflammasome activation. Exercise alleviated diet-induced hepatic steatosis, inflammation, and fibrosis. Importantly, exercise significantly reduced the expression of NLRP3 inflammasome components, decreased Caspase-1 enzymatic activity, normalized IL-1β production, and suppressed ROS overproduction in HFD-fed and MCD diet-fed mice. The exercise-elicited NLRP3 inflammasome inhibition was accompanied by increased adropin levels. Moreover, serum adropin levels were negatively correlated with serum IL-1β levels. We further explored the effect of adropin on the NLRP3 inflammasome in palmitic acid (PA)-treated hepatocytes and Kupffer cells. Although adropin treatment did not significantly decrease the levels of all inflammasome components, it reduced the active Caspase-1 level, decreased Caspase-1 activity and downregulated IL-1β expression in hepatocytes and Kupffer cells (KCs) treated with PA. Moreover, ROS levels in PA-stimulated hepatocytes and Kupffer cells were reduced upon adropin treatment. In summary, we demonstrated that the inhibitory effect of exercise on NLRP3 inflammasome activation was associated with adropin induction, resulting in NASH improvement.

IRGM1, a guardian of mitochondrial DAMP-mediated autoinflammation

IRGM1 is recognized as a master regulator of type I interferon responses against pathogens, while also protecting against autoimmune diseases. It has now been shown that IRGM1 controls autoinflammatory responses by modulating mitophagy flux.

Pinocembrin ameliorates intermittent hypoxia-induced neuroinflammation through BNIP3-dependent mitophagy in a murine model of sleep apnea

BACKGROUND

Intermittent hypoxia (IH) caused by obstructive sleep apnea (OSA) leads to neuroinflammation. Pinocembrin has been shown to have neuroprotective effects, while the therapeutic functions under IH condition are still unknown.

METHODS

An OSA model was established by CIH exposure inside custom-made chambers. C57BL/6 mice were intraperitoneally injected with pinocembrin (40 mg/kg, i.p.) or vehicle (PBS containing 5% povidone; i.p.), and the changes of behavior on mice were detected by the Morris water maze test. Immunohistochemical staining, western blotting, immunofluorescence assays, and immunoprecipitation were used to investigate the association between NLRP3 inflammasome and BNIP3-dependent mitophagy. The mitochondrial morphology and mitophagosomes were detected under a transmission electron microscope. The detrimental effects of IH were tested by annexin V-FITC/PI staining, Mito SOX Red staining, and JC-1 mitochondrial membrane potential assay.

RESULTS

In this study, our observations in vivo indicated that the administration of pinocembrin can restore spatial learning and memory ability and reduce neuronal apoptosis and hippocampal inflammation. Pinocembrin treatment significantly inhibited the formation of NLRP3 inflammasome and infiltration of microglia and enhanced BNIP3-mediated mitophagy in the hippocampus of IH mice. Additionally, our in vitro results show that pinocembrin protects microglial cells against IH-induced cytotoxicity by activating BNIP3-dependent mitophagy through the JNK-ERK signaling pathway.

CONCLUSIONS

In summary, our findings demonstrated that pinocembrin can act as a potential therapeutic strategy for IH-induced neuroinflammation.

Cellular Protein Quality Control in Diabetic Cardiomyopathy: From Bench to Bedside

Heart failure is a serious comorbidity and the most common cause of mortality in diabetes patients. Diabetic cardiomyopathy (DCM) features impaired cellular structure and function, culminating in heart failure; however, there is a dearth of specific clinical therapy for treating DCM. Protein homeostasis is pivotal for the maintenance of cellular viability under physiological and pathological conditions, particularly in the irreplaceable cardiomyocytes; therefore, it is tightly regulated by a protein quality control (PQC) system. Three evolutionarily conserved molecular processes, the unfolded protein response (UPR), the ubiquitin-proteasome system (UPS), and autophagy, enhance protein turnover and preserve protein homeostasis by suppressing protein translation, degrading misfolded or unfolded proteins in cytosol or organelles, disposing of damaged and toxic proteins, recycling essential amino acids, and eliminating insoluble protein aggregates. In response to increased cellular protein demand under pathological insults, including the diabetic condition, a coordinated PQC system retains cardiac protein homeostasis and heart performance, on the contrary, inappropriate PQC function exaggerates cardiac proteotoxicity with subsequent heart dysfunction. Further investigation of the PQC mechanisms in diabetes propels a more comprehensive understanding of the molecular pathogenesis of DCM and opens new prospective treatment strategies for heart disease and heart failure in diabetes patients. In this review, the function and regulation of cardiac PQC machinery in diabetes mellitus, and the therapeutic potential for the diabetic heart are discussed.

Irisin and Autophagy: First Update

Aging and sedentary life style are considered independent risk factors for many disorders. Under these conditions, accumulation of dysfunctional and damaged cellular proteins and organelles occurs, resulting in a cellular degeneration and cell death. Autophagy is a conserved recycling pathway responsible for the degradation, then turnover of cellular proteins and organelles. This process is a part of the molecular underpinnings by which exercise promotes healthy aging and mitigate age-related pathologies. Irisin is a myokine released during physical activity and acts as a link between muscles and other tissues and organs. Its main beneficial function is the change of subcutaneous and visceral adipose tissue into brown adipose tissue, with a consequential increase in thermogenesis. Irisin modulates metabolic processes, acting on glucose homeostasis, reduces systemic inflammation, maintains the balance between resorption and bone formation, and regulates the functioning of the nervous system. Recently, some of its pleiotropic and favorable properties have been attributed to autophagy induction, posing irisin as an important regulator of autophagy by exercise. This review article proposes to bring together for the first time the "state of the art" knowledge regarding the effects of irisin and autophagy. Furthermore, treatments on relation between exercise/myokines and autophagy have been also achieved.

Energy Metabolism in Exercise-Induced Physiologic Cardiac Hypertrophy

Physiologic hypertrophy of the heart preserves or enhances systolic function without interstitial fibrosis or cell death. As a unique form of physiological stress, regular exercise training can trigger the adaptation of cardiac muscle to cause physiological hypertrophy, partly due to its ability to improve cardiac metabolism. In heart failure (HF), cardiac dysfunction is closely associated with early initiation of maladaptive metabolic remodeling. A large amount of clinical and experimental evidence shows that metabolic homeostasis plays an important role in exercise training, which is conducive to the treatment and recovery of cardiovascular diseases. Potential mechanistic targets for modulation of cardiac metabolism have become a hot topic at present. Thus, exploring the energy metabolism mechanism in exercise-induced physiologic cardiac hypertrophy may produce new therapeutic targets, which will be helpful to design novel effective strategies. In this review, we summarize the changes of myocardial metabolism (fatty acid metabolism, carbohydrate metabolism, and mitochondrial adaptation), metabolically-related signaling molecules, and probable regulatory mechanism of energy metabolism during exercise-induced physiological cardiac hypertrophy.

Inflammasome and Mitophagy Connection in Health and Disease

The inflammasome is a large intracellular protein complex that activates inflammatory caspase-1 and induces the maturation of interleukin (IL)-1β and IL-18. Mitophagy plays an essential role in the maintenance of mitochondrial homeostasis during stress. Previous studies have indicated compelling evidence of the crosstalk between inflammasome and mitophagy. Mitophagy regulation of the inflammasome, or vice versa, is crucial for various biological functions, such as controlling inflammation and metabolism, immune and anti-tumor responses, and pyroptotic cell death. Uncontrolled regulation of the inflammasome often results in pathological inflammation and pyroptosis, and causes a variety of human diseases, including metabolic and inflammatory diseases, infection, and cancer. Here, we discuss how improved understanding of the interactions between inflammasome and mitophagy can lead to novel therapies against various disease pathologies, and how the inflammasome-mitophagy connection is currently being targeted pharmacologically by diverse agents and small molecules. A deeper understanding of the inflammasome-mitophagy connection will provide new insights into human health and disease through the balance between mitochondrial clearance and pathology.

Different Intensity Exercise Preconditions Affect Cardiac Function of Exhausted Rats through Regulating TXNIP/TRX/NF-ĸBp65/NLRP3 Inflammatory Pathways

Objective

To investigate whether exercise preconditioning (EP) improves the rat cardiac dysfunction induced by exhaustive exercise (EE) through regulating NOD-like receptor protein 3 (NLRP3) inflammatory pathways and to confirm which intensity of EP is better.

Method

Ninety healthy male Sprague Dawley rats were randomly divided into five groups: a control group (CON), exhaustive exercise group (EE), low-, middle-, and high-intensity exercise precondition and exhaustive exercise group (LEP + EE, MEP + EE, HEP + EE group). We established the experimental model by referring to Bedford's motion load standard to complete the experiment. Then, the pathological changes of the myocardium were observed under a light microscope. Biomarker of myocardial injury in serum and oxidative stress factor in myocardial tissue were evaluated by ELISAs. The cardiac function parameters were detected using a Millar pressure and volume catheter. The levels of thioredoxin-interacting protein (TXNIP), thioredoxin protein (TRX), nuclear transcription factor kappa B_p65 (NF-ĸB_p65), NLRP3, and cysteinaspartate specific proteinase 1 (Caspase-1) protein in rats' myocardium were detected by western blotting.

Results

1. The myocardial structures of three EP + EE groups were all improved compared with EE groups. 2. The levels of the creatine phosphating-enzyme MB (CK-MB), reactive oxygen species (ROS), interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor alpha (TNF-α) in three EP + EE groups were all increased compared with CON but decreased compared with the EE group (P < 0.05). 3. Compared with the CON group, slope of end-systolic pressure volume relationship (ESPVR), ejection fraction (EF), and peak rate of the increase in pressure (dP/dt_max) all dropped to the lowest level in the EE group (P < 0.05), while the values of cardiac output (CO), stroke volume (SV), end-systolic volume (Ves), end-diastolic volume (Ved), and relaxation time constant (Tau) increased in the EE group (P < 0.05). 4. Compared with the CON group, the expression levels of TXNIP, NF-ĸB_p65, NLRP3, and Caspase-1 all increased obviously in the other groups (P < 0.05); meanwhile, they were all decreased in three EP + EE groups compared with the EE group (P < 0.05). 5. NLRP3 was positively correlated with heart rate, IL-6, and ROS, but negatively correlated with EF (P < 0.01).

Conclusion

EP protects the heart from EE-induced injury through downregulating TXNIP/TRX/NF-ĸB_p65/NLRP3 inflammatory signaling pathways. Moderate intensity EP has the best protective effect.

Exercise-Induced Mitophagy in Skeletal Muscle and Heart

Regular exercise enhances mitochondrial function by promoting healthy mitochondrial remodeling, but the underlying mechanisms are not thoroughly understood. An emerging hypothesis suggests that, in addition to anabolic events such as mitochondria biogenesis, the selective degradation of dysfunctional mitochondria (i.e., mitophagy) also is a key component of exercise-mediated adaptations in striated muscle, which eventually leads to better mitochondrial functions.

Role of Mitophagy in Cardiovascular Disease

Cardiovascular disease is the leading cause of mortality worldwide, and mitochondrial dysfunction is the primary contributor to these disorders. Recent studies have elaborated on selective autophagy-mitophagy, which eliminates damaged and dysfunctional mitochondria, stabilizes mitochondrial structure and function, and maintains cell survival and growth. Numerous recent studies have reported that mitophagy plays an important role in the pathogenesis of various cardiovascular diseases. This review summarizes the mechanisms underlying mitophagy and advancements in studies on the role of mitophagy in cardiovascular disease.

The Effect of Glutamine Supplementation on Oxidative Stress and Matrix Metalloproteinase 2 and 9 After Exhaustive Exercise

Background

Glutamine is the most abundant amino acid in plasma and skeletal muscles and an important fuel for immune system cells. It has beneficial anti-inflammatory and antioxidant properties which may be considered as a potentially useful supplement for athletes. The present study was conducted to investigate the effect of glutamine supplementation on oxidative stress and matrix metalloproteinase 2 and 9 after exhaustive exercise in young healthy males.

Materials and methods

In this study, 30 healthy males (supplement =15 and control=15) were randomly assigned into two groups. The supplement group received 0.3 g/kg BW of glutamine along with 25 gr of sugar dissolved in 250 cc water per day. The control group received 25 gr of sugar in 250 cc water per day. Fasting blood samples were taken at baseline and at the end of 14 days of intervention. The participants underwent exercise until experiencing full-body exhaustive fatigue for 16 ± 2.84 mins, and then fasting blood samples were taken. Serum levels of TAC, MDA, MMP2, MMP9, glutathione, and hs-CRP were measured.

Results

Serum levels of MDA and hs-CRP significantly decreased in the supplement group (p< 0.05). The serum level of TAC significantly increased in the supplement group (p< 0.05). Glutathione serum levels significantly increased after exhaustive exercise (p< 0.05). Serum levels of MMP2 and MMP9 remained unchanged.

Conclusion

Results of this study showed that, some biochemical factors are time-dependent and can increase or decrease over time, as well as, serum levels of hs-CRP and MDA decreased with glutamine supplementation along with the increase in the TAC serum levels, but this supplementation had no effect on serum levels of MMP2 and MMP9 in exhaustive exercise.

Interaction between autophagy and the NLRP3 inflammasome

Autophagy, a metabolic pathway that plays an important role in maintaining the dynamic balance of cells, has two types, i.e. non-selective autophagy and selective autophagy. The role of non-selective autophagy is primarily to allow cells to circulate nutrients in an energy-limited environment, while selective autophagy primarily cleans up the organelles inside the cells to maintain the cell structure. The NLRP3 inflammasome is an innate immune response produced by the organism that can promote the secretion of interleukin-1β and interleukin-18 through caspase-1 activation and resist the damage of some pathogens. However, when the NLRP3 inflammasome is overactivated, it can cause various inflammatory diseases, such as inflammatory liver disease and inflammatory bowel disease. Many previous studies have shown that autophagy can inhibit the NLRP3 inflammasome, while in recent years, new studies have found that autophagy can also promote the NLRP3 inflammasome in some cases, and the NLRP3 inflammasome can, in turn, affect autophagy. In this review, the interaction between autophagy and the NLRP3 inflammasome is explored, and then the application of this interaction in disease treatment is discussed.

Physical Exercise and Selective Autophagy: Benefit and Risk on Cardiovascular Health

Physical exercise promotes cardiorespiratory fitness, and is considered the mainstream of non-pharmacological therapies along with lifestyle modification for various chronic diseases, in particular cardiovascular diseases. Physical exercise may positively affect various cardiovascular risk factors including body weight, blood pressure, insulin sensitivity, lipid and glucose metabolism, heart function, endothelial function, and body fat composition. With the ever-rising prevalence of obesity and other types of metabolic diseases, as well as sedentary lifestyle, regular exercise of moderate intensity has been indicated to benefit cardiovascular health and reduce overall disease mortality. Exercise offers a wide cadre of favorable responses in the cardiovascular system such as improved dynamics of the cardiovascular system, reduced prevalence of coronary heart diseases and cardiomyopathies, enhanced cardiac reserve capacity, and autonomic regulation. Ample clinical and experimental evidence has indicated an emerging role for autophagy, a conservative catabolism process to degrade and recycle cellular organelles and nutrients, in exercise training-offered cardiovascular benefits. Regular physical exercise as a unique form of physiological stress is capable of triggering adaptation while autophagy in particular selective autophagy seems to be permissive to such cardiovascular adaptation. Here in this mini-review, we will summarize the role for autophagy in particular mitochondrial selective autophagy namely mitophagy in the benefit versus risk of physical exercise on cardiovascular function.

Therapeutic Approaches in Mitochondrial Dysfunction, Inflammation, and Autophagy in Uremic Cachexia: Role of Aerobic Exercise

Chronic kidney disease (CKD) causes several systemic changes, including muscular homeostasis, and eventually results in muscle atrophy. CKD-induced muscle atrophy is highly prevalent, and exercise is well known to enhance muscle function in these cases, although the exact mechanism remains unclear. Here, we aim to assess whether the protective effect of aerobic exercise in 5/6 nephrectomized (CKD) mice is associated with mitochondrial dysfunction, autophagy, or inflammation. C57BL/6J mice were randomly allocated into 3 different experimental groups: Sham, CKD, and CKD+aerobic exercise (CKD+AE). Renal function was assessed via serum creatinine and urea levels, and histological PAS and Masson staining were performed. Muscle wasting was determined based on grip strength, cross-sectional area (CSA), and MyHC protein expression. We also measured mitochondrial dysfunction in mice by assessing mtDNA, ROS, ATP production, and mitochondrial configuration. Autophagy was determined via assessments for Atg7, LC3, and SQSTM1 on western blotting. Inflammation was identified via proinflammatory cytokines and NLRP3 inflammasome components using real-time PCR and western blotting. We found that CKD mice exhibited higher BUN and creatinine levels and more severe glomerulosclerosis in the glomeruli and renal tubulointerstitial fibrosis, relative to the Sham group; all these effects were relieved by aerobic exercise. Moreover, grip strength, CSA, and MyHC protein expression were improved after 8 weeks of aerobic exercise. Furthermore, aerobic exercise significantly decreased MDA levels, increased SOD2 activity and ATP production, and improved mitochondrial configuration, relative to the CKD group. In addition, aerobic exercise downregulated the overexpression of proinflammatory cytokines and NLRP3 inflammasome components and balanced the mitochondrial biogenesis and autophagy-lysosomal system. Thus, we observed that aerobic exercise may ameliorate CKD-induced muscle wasting by improving mitochondrial dysfunction, inflammation, and autophagy-lysosomal system in uremic cachexia.

PINK1-parkin pathway of mitophagy protects against contrast-induced acute kidney injury via decreasing mitochondrial ROS and NLRP3 inflammasome activation

Contrast-induced acute kidney injury (CI-AKI) occurs in more than 30% of patients after intravenous iodinated contrast media and causes serious complications, including renal failure and mortality. Recent research has demonstrated that routine antioxidant and alkaline therapy failed to show benefits in CI-AKI patients with high risk for renal complications. Mitophagy is a mechanism of selective autophagy, which controls mitochondrial quality and mitochondrial reactive oxygen species (ROS) through degradation of damaged mitochondria. The role of mitophagy and its regulation of apoptosis in CI-AKI are poorly understood. In this study, we demonstrated that mitophagy was induced in renal tubular epithelial cells (RTECs) during CI-AKI, both in vivo and in vitro. Meanwhile, contrast media-induced mitophagy was abolished when silencing PINK1 or PARK2 (Parkin), indicating a dominant role of the PINK1-Parkin pathway in mitophagy. Moreover, mitochondrial damage, mitochondrial ROS, RTEC apoptosis, and renal injury under contrast exposure were more severe in PINK1- or PARK2-deficient cells and mice than in wild-type groups. Functionally, PINK1-Parkin-mediated mitophagy prevented RTEC apoptosis and tissue damage in CI-AKI through reducing mitochondrial ROS and subsequent NLRP3 inflammasome activation. These results demonstrated that PINK1-Parkin-mediated mitophagy played a protective role in CI-AKI by reducing NLRP3 inflammasome activation.

Silibinin Alleviates the Learning and Memory Defects in Overtrained Rats Accompanying Reduced Neuronal Apoptosis and Senescence

Excessive physical exercise (overtraining; OT) increases oxidative stress and induces damage in multiple organs including the brain, especially the hippocampus that plays an important role in learning and memory. Silibinin, a natural flavonoid derived from milk thistle of Silybum marianum, has been reported to exert neuroprotective effect. In this study, rats were subjected to overtraining exercise, and the protective effects of silibinin were investigated in these models. Morris water maze and novel object recognition tests showed that silibinin significantly attenuated memory defects in overtrained rats. At the same time, the results of Nissl, TUNEL and SA-β-gal staining showed that silibinin reversed neuronal loss caused by apoptosis, and delayed cell senescence of the hippocampus in the overtrained rats, respectively. In addition, silibinin decreased malondialdehyde (MDA) levels which is associated with reactive oxygen species (ROS) generation. Silibinin prevented impairment of learning and memory caused by excessive physical exercise in rats, accompanied by reduced apoptosis and senescence in hippocampus cells.

Emerging views of mitophagy in immunity and autoimmune diseases

Mitophagy is a vital form of autophagy for selective removal of dysfunctional or redundant mitochondria. Accumulating evidence implicates elimination of dysfunctional mitochondria as a powerful means employed by autophagy to keep the immune system in check. The process of mitophagy may restrict inflammatory cytokine secretion and directly regulate mitochondrial antigen presentation and immune cell homeostasis. In this review, we describe distinctive pathways of mammalian mitophagy and highlight recent advances relevant to its function in immunity. In addition, we further discuss the direct and indirect evidence linking mitophagy to inflammation and autoimmunity underlying the pathogenesis of autoimmune diseases including inflammatory bowel diseases (IBD), systemic lupus erythematosus (SLE) and primary biliary cirrhosis (PBC).Abbreviations: AICD: activation induced cell death; AIM2: absent in melanoma 2; ALPL/HOPS: alkaline phosphatase, biomineralization associated; AMA: anti-mitochondrial antibodies; AMFR: autocrine motility factor receptor; ATG: autophagy-related; BCL2L13: BCL2 like 13; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3 like; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CARD: caspase recruitment domain containing; CASP1: caspase 1; CD: Crohn disease; CGAS: cyclic GMP-AMP synthase; CXCL1: C-X-C motif chemokine ligand 1; DEN: diethylnitrosamine; DLAT/PDC-E2: dihydrolipoamide S-acetyltransferase; DNM1L/Drp1: dynamin 1 like; ESCRT: endosomal sorting complexes required for transport; FKBP8: FKBP prolyl isomerase 8; FUNDC1: Fun14 domain containing 1; GABARAP: GABA type A receptor-associated protein; HMGB1: high mobility group box 1; HPIV3: human parainfluenza virus type 3; IBD: inflammatory bowel diseases; IEC: intestinal epithelial cell; IFN: interferon; IL1B/IL-1β: interleukin 1 beta; iNK: invariant natural killer; IRGM: immunity related GTPase M; LIR: LC3-interacting region; LPS: lipopolysaccharide; LRRK2: leucine rich repeat kinase 2; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MARCH5: membrane associated ring-CH-type finger 5; MAVS: mitochondrial antiviral signaling protein; MDV: mitochondria-derived vesicle; MFN1: mitofusin 1; MHC: major histocompatibility complex; MIF: macrophage migration inhibitory factor; mtAP: mitochondrial antigen presentation; mtDNA: mitochondrial DNA; MTOR: mechanistic target of rapamycin kinase; mtROS: mitochondrial ROS; MUL1: mitochondrial E3 ubiquitin protein ligase 1; NBR1: NBR1 autophagy cargo receptor; NFKB/NF-ĸB: nuclear factor kappa B subunit; NK: natural killer; NLR: NOD-like receptor; NLRC4: NLR family CARD domain containing 4; NLRP3: NLR family pyrin domain containing 3; OGDH: oxoglutarate dehydrogenase; OMM: outer mitochondrial membrane; OPTN: optineurin; ox: oxidized; PARK7: Parkinsonism associated deglycase; PBC: primary biliary cirrhosis; PEX13: peroxisomal biogenesis factor 13; PHB/PHB1: prohibitin; PHB2: prohibitin 2; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PINK1: PTEN induced kinase 1; PLEKHM1: pleckstrin homology and RUN domain containing M1; PRKN/PARK2: parkin RBR E3 ubiquitin protein ligase; RAB: member RAS oncogene family; RHEB: Ras homolog: mTORC1 binding; RIPK2: receptor interacting serine/threonine kinase 2; RLR: DDX58/RIG-I like receptor; ROS: reactive oxygen species; SBD: small bile ducts; SLC2A1/GLUT1: solute carrier family 2 member 1; SLE: systemic lupus erythematosus; SMURF1: SMAD specific E3 ubiquitin protein ligase 1; SQSTM1/p62: sequestosome 1; TAX1BP1: Tax1 binding protein 1; TCR: T cell receptor; TFAM: transcription factor A: mitochondrial; Th17: T helper 17; TLR9: toll like receptor 9; TMEM173/STING: transmembrane protein 173; TNF/TNF-α: tumor necrosis factor; Ub: ubiquitin; UC: ulcerative colitis; ULK1: unc-51 like autophagy activating kinase 1; WIPI: WD repeat domain: phosphoinositide interacting; ZFYVE1/DFCP1: zinc finger FYVE-type containing 1.

The Effects of Acute and Chronic Aerobic Activity on the Signaling Pathway of the Inflammasome NLRP3 Complex in Young Men

Background and Objectives: The results of the studies show that the intensity and volume of aerobic exercise activity produce different responses of the immune system. This study aims to show how the signaling pathway of the inflammatory NLRP3 complex is influenced by the acute and chronic effects of moderate and high-intensity aerobic exercises in young men. Materials and Methods: Accordingly, 60 healthy (BMI = 23.56 ± 2.67) young (24.4 ± 0.4) students volunteered to participate in the study that was randomly divided into two experimental (n = 20) groups and one control (n = 20) group. The training protocol started with two intensity levels of 50% for a moderate group and 70% of maximum heart rate for high group for 30 min and then continued until reaching 70% (moderate group) and 90% (high group) of the maximum heart rate, respectively. Using Real Time-PCR method, the expression of NLRP3 gene and ELISA- were measured by IL-1β, IL-18. Results: The results showed that acute aerobic exercise with moderate intensity had no significant effect on the expression of NLRP3 gene and serum levels of IL-1β and IL-18 cytokines (p > 0.05) when acute exercise, with high intensity, begins an initiation of the activity of the inflammatory complex with elevated serum levels of IL-1β, IL-18, and NLRP3 gene expression (p < 0.05). In addition, chronic exercise with moderate intensity significantly reduced the expression of NLRP3 gene and serum levels of IL-1β, IL-18 cytokines (p < 0.05). In the case of chronic exercise with high intensity, a significant increase in expression of gene, NLRP3 and serum levels of IL-1β, IL-18 cytokines were observed (p < 0.05). Conclusions: Generally, it can be concluded that chronic exercise with moderate intensity is effective in decreasing the expression of the inflammasome and inflammation.

Autophagy and aging: Maintaining the proteome through exercise and caloric restriction

Accumulation of dysfunctional and damaged cellular proteins and organelles occurs during aging, resulting in a disruption of cellular homeostasis and progressive degeneration and increases the risk of cell death. Moderating the accrual of these defunct components is likely a key in the promotion of longevity. While exercise is known to promote healthy aging and mitigate age‐related pathologies, the molecular underpinnings of this phenomenon remain largely unclear. However, recent evidences suggest that exercise modulates the proteome. Similarly, caloric restriction (CR), a known promoter of lifespan, is understood to augment intracellular protein quality. Autophagy is an evolutionary conserved recycling pathway responsible for the degradation, then turnover of cellular proteins and organelles. This housekeeping system has been reliably linked to the aging process. Moreover, autophagic activity declines during aging. The target of rapamycin complex 1 (TORC1), a central kinase involved in protein translation, is a negative regulator of autophagy, and inhibition of TORC1 enhances lifespan. Inhibition of TORC1 may reduce the production of cellular proteins which may otherwise contribute to the deleterious accumulation observed in aging. TORC1 may also exert its effects in an autophagy‐dependent manner. Exercise and CR result in a concomitant downregulation of TORC1 activity and upregulation of autophagy in a number of tissues. Moreover, exercise‐induced TORC1 and autophagy signaling share common pathways with that of CR. Therefore, the longevity effects of exercise and CR may stem from the maintenance of the proteome by balancing the synthesis and recycling of intracellular proteins and thus may represent practical means to promote longevity.

Role of NLRP3 inflammasome in the development of bladder pain syndrome interstitial cystitis

Although it has been proposed that NOD-like receptor protein 3 (NLRP3) inflammasome activation may have an important contribution to the onset of bladder pain syndrome/interstitial cystitis (BPS/IC), as of today there is still insufficient evidence to accept or to reject this hypothesis. However, taking into consideration that inflammasomes have been already shown as important mediators of cyclophosphamide-induced bladder inflammation and that some studies have also revealed human bladder epithelium expresses high levels of NLRP3, such a hypothesis seems to be reasonable. The purpose of this review is to discuss a scenario that NLRP3 inflammasome is a crucial player in the development of this disease. Identification of a novel mediator of bladder inflammation and pain could lead to emerging new therapeutic strategy and the first causative therapy.

Regulation of autophagic and mitophagic flux during chronic contractile activity-induced muscle adaptations

Autophagy and mitophagy are important for training-inducible muscle adaptations, yet it remains unclear how these systems are regulated throughout the adaptation process. Here, we studied autophagic and mitophagic flux in the skeletal muscles of Sprague-Dawley rats (300-500 g) exposed to chronic contractile activity (CCA; 3 h/day, 9 V, 10 Hz continuous, 0.1 ms pulse duration) for 1, 2, 5, and 7 days (N = 6-8/group). In order to determine the flux rates, colchicine (COL; 0.4 mg/ml/kg) was injected 48 h before tissue collection, and we evaluated differences of autophagosomal protein abundances (LC3-II and p62) between colchicine- and saline-injected animals. We confirmed that CCA resulted in mitochondrial adaptations, including improved state 3 respiration as early as day 1 in permeabilized muscle fibers, as well significant increases in mitochondrial respiratory capacity and marker proteins in IMF mitochondria by day 7. Mitophagic and autophagic flux (LC3-II and p62) were significantly decreased in skeletal muscle following 7 days of CCA. Notably, the mitophagic system seemed to be downregulated prior (day 3-5) to changes in autophagic flux (day 7), suggesting enhanced sensitivity of mitophagy compared to autophagy with chronic muscle contraction. Although we detected no significant change in the nuclear translocation of TFEB, a regulator of lysosomal biogenesis, CCA increased total TFEB protein, as well as LAMP1, in skeletal muscle. Thus, chronic muscle activity reduces mitophagy in parallel with improved mitochondrial function, and this is supported by enhanced lysosomal degradation capacity.

Genes involved in the regulation of different types of autophagy and their participation in cancer pathogenesis

Autophagy is a highly conserved mechanism of self-digestion that removes damaged organelles and proteins from cells. Depending on the way the protein is delivered to the lysosome, four basic types of autophagy can be distinguished: macroautophagy, selective autophagy, chaperone-mediated autophagy and microautophagy. Macroautophagy involves formation of autophagosomes and is controlled by specific autophagy-related genes. The steps in macroautophagy are initiation, phagophore elongation, autophagosome maturation, autophagosome fusion with the lysosome, and proteolytic degradation of the contents. Selective autophagy is macroautophagy of a specific cellular component. This work focuses on mitophagy (selective autophagy of abnormal and damaged mitochondria), in which the main participating protein is PINK1 (phosphatase and tensin homolog-induced putative kinase 1). In chaperone-mediated autophagy, the substrate is bound to a heat shock protein 70 chaperone before it is delivered to the lysosome. The least characterized type of autophagy is microautophagy, which is the degradation of very small molecules without participation of an autophagosome. Autophagy can promote or inhibit tumor development, depending on the severity of the disease, the type of cancer, and the age of the patient. This paper describes the molecular basis of the different types of autophagy and their importance in cancer pathogenesis.

Alterations of Cardiac KATP Channels and Autophagy Contribute in the Late Cardioprotective Phase of Exercise Preconditioning

The cardiac effects of exercise preconditioning (EP) are well established; however, the mechanisms involving cardiac ATP-sensitive potassium channel (K_ATP channel) subunits and autophagy are yet to be fully established. The present work aims to investigate the alterations of cardiac K_ATP channel subunits Kir6.2, SUR2A, and autophagy-related LC3 during the late cardioprotective phase of EP against exhaustive exercise-induced myocardial injury. Rats run on treadmill for four running time intervals, each with 10 minutes running and rest. Exhaustive exercise was performed 24 h after EP. Cardiac biomarkers, cTnI and NT-proBNP, along with the histological stain, were served as indicators of myocardial injury. Cardiac K_ATP channel subunits Kir6.2 and SUR2A were analyzed in this study, and autophagy was evaluated by LC3. The results revealed that EP reduced the exhaustive exercise-induced high level of serum cTnI and myocardial ischemia/hypoxia; however, it did not reveal any changes in the serum NT-proBNP level or cardiac BNP. Cardiac SUR2A mRNA significantly upregulated during the exhaustive exercise. The high levels of Kir6.2, SUR2A, LC3IIpuncta and LC3II turnover observed after exhaustive exercise were significantly mitigated by EP in the late phase. These results suggest that EP alleviates myocardial injury induced by exhaustive exercise through the downregulation of cardiac K_ATP channels and autophagy.

Reactive Oxygen Species as Intracellular Signaling Molecules in the Cardiovascular System

BACKGROUND

Redox signaling plays an important role in the lives of cells. This signaling not only becomes apparent in pathologies but is also thought to be involved in maintaining physiological homeostasis. Reactive Oxygen Species (ROS) can activate protein kinases: CaMKII, PKG, PKA, ERK, PI3K, Akt, PKC, PDK, JNK, p38. It is unclear whether it is a direct interaction of ROS with these kinases or whether their activation is a consequence of inhibition of phosphatases. ROS have a biphasic effect on the transport of Ca2+ in the cell: on one hand, they activate the sarcoplasmic reticulum Ca2+-ATPase, which can reduce the level of Ca2+ in the cell, and on the other hand, they can inactivate Ca2+-ATPase of the plasma membrane and open the cation channels TRPM2, which promote Ca2+-loading and subsequent apoptosis. ROS inhibit the enzyme PHD2, which leads to the stabilization of HIF-α and the formation of the active transcription factor HIF.

CONCLUSION

Activation of STAT3 and STAT5, induced by cytokines or growth factors, may include activation of NADPH oxidase and enhancement of ROS production. Normal physiological production of ROS under the action of cytokines activates the JAK/STAT while excessive ROS production leads to their inhibition. ROS cause the activation of the transcription factor NF-κB. Physiological levels of ROS control cell proliferation and angiogenesis. ROS signaling is also involved in beneficial adaptations to survive ischemia and hypoxia, while further increases in ROS can trigger programmed cell death by the mechanism of apoptosis or autophagy. ROS formation in the myocardium can be reduced by moderate exercise.

Exercise Combined with Rhodiola sacra Supplementation Improves Exercise Capacity and Ameliorates Exhaustive Exercise-Induced Muscle Damage through Enhancement of Mitochondrial Quality Control

Mounting evidence has firmly established that increased exercise capacity (EC) is associated with considerable improvements in the survival of patients with cardiovascular disease (CVD) and that antistress capacity is a prognostic predictor of adverse cardiovascular events in patients with CVD. Previous studies have indicated that aerobic exercise (AE) and supplementation with Rhodiola sacra (RS), a natural plant pharmaceutical, improve EC and enable resistance to stress; however, the underlying mechanism remains unclear. This study explored the ability of AE and RS, alone or combined, to improve EC and ameliorate exhaustive exercise- (EE-) induced stress and elucidate the mechanism involved. We found that AE and RS significantly increased EC in mice and ameliorated EE-induced stress damage in skeletal and cardiac muscles (SCM); furthermore, a synergistic effect was detected for the first time. To our knowledge, the present work is the first to report that AE and RS activate mitophagy, mitochondrial dynamics, and biogenesis in SCM, both in the resting state and after EE. These data indicate that AE and RS synergistically improve EC in mice and protect SCM from EE-induced stress by enhancing mitochondrial quality control, including the activation of mitophagy, mitochondrial dynamics, and biogenesis, both at rest and after EE.

Potential signaling pathways of acute endurance exercise-induced cardiac autophagy and mitophagy and its possible role in cardioprotection

Cardiac myocytes are terminally differentiated cells and possess extremely limited regenerative capacity; therefore, preservation of mature cardiac myocytes throughout the individual's entire life span contributes substantially to healthy living. Autophagy, a lysosome-dependent cellular catabolic process, is essential for normal cardiac function and mitochondria maintenance. Therefore, it may be reasonable to hypothesize that if endurance exercise promotes cardiac autophagy and mitochondrial autophagy or mitophagy, exercise-induced cardiac autophagy (EICA) or exercise-induced cardiac mitophagy (EICM) may confer propitious cellular environment and thus protect the heart against detrimental stresses, such as an ischemia-reperfusion (I/R) injury. However, although the body of evidence supporting EICA and EICM is growing, the molecular mechanisms of EICA and EICM and their possible roles in cardioprotection against an I/R injury are poorly understood. Here, we introduce the general mechanisms of autophagy in an attempt to integrate potential molecular pathways of EICA and EICM and also highlight a potential insight into EICA and EICM in cardioprotection against an I/R insult.

The Crosstalk between the Gut Microbiota and Mitochondria during Exercise

Many physiological changes occur in response to endurance exercise in order to adapt to the increasing energy needs, mitochondria biogenesis, increased reactive oxygen species (ROS) production and acute inflammatory responses. Mitochondria are organelles within each cell that are crucial for ATP production and are also a major producer of ROS and reactive nitrogen species during intense exercise. Recent evidence shows there is a bidirectional interaction between mitochondria and microbiota. The gut microbiota have been shown to regulate key transcriptional co-activators, transcription factors and enzymes involved in mitochondrial biogenesis such as PGC-1α, SIRT1, and AMPK genes. Furthermore, the gut microbiota and its metabolites, such as short chain fatty acids and secondary bile acids, also contribute to host energy production, ROS modulation and inflammation in the gut by attenuating TNFα- mediated immune responses and inflammasomes such as NLRP3. On the other hand, mitochondria, particularly mitochondrial ROS production, have a crucial role in regulating the gut microbiota via modulating intestinal barrier function and mucosal immune responses. Recently, it has also been shown that genetic variants within the mitochondrial genome, could affect mitochondrial function and therefore the intestinal microbiota composition and activity. Diet is also known to dramatically modulate the composition of the gut microbiota. Therefore, studies targeting the gut microbiota can be useful for managing mitochondrial related ROS production, pro-inflammatory signals and metabolic limits in endurance athletes.

Effects of aerobic training on markers of autophagy in the elderly

Autophagy is a molecular process essential for the maintenance of cellular homeostasis, which appears to (i) decline with age and (ii) respond to physical exercise. In addition, recent evidence suggests a crosstalk between autophagy and toll-like receptor (TLR)-associated inflammatory responses. This study assessed the effects of aerobic exercise training on autophagy and TLR signaling in older subjects. Twenty-nine healthy women and men (age, 69.7 ± 1.0 year) were randomized to a training (TG) or a control (CG) group. TG performed an 8-week aerobic training program, while CG followed their daily routines. Peripheral blood mononuclear cells were isolated from blood samples obtained before and after the intervention, and protein levels of protein 1 light chain 3 (LC3), sequestosome 1 (p62/SQSTM1), beclin-1, phosphorylated unc-51-like kinase (ULK-1), ubiquitin-like autophagy-related (Atg)12, Atg16, and lysosome-associated membrane protein (LAMP)-2 were measured. TLR2 and TLR4 signaling pathways were also analyzed. Peak oxygen uptake increased in TG after the intervention. Protein expression of beclin-1, Atg12, Atg16, and the LC3II/I ratio increased following the training program (p < 0.05), while expression of p62/SQSTM1 and phosphorylation of ULK-1 at Ser(757) were lower (p < 0.05). Protein content of TLR2, TLR4, myeloid differentiation primary response gen 88 (MyD88), and TIR domain-containing adaptor-inducing interferon (TRIF) were not significantly modified by exercise. The current data indicate that aerobic exercise training induces alterations in multiple markers of autophagy, which seem to be unrelated to changes in TLR2 and TLR4 signaling pathways. These results expand knowledge on exercise-induced autophagy adaptations in humans and suggest that the exercise type employed may be a key factor explaining the potential relationship between autophagy and TLR pathways.

Exercise amelioration of depression-like behavior in OVX mice is associated with suppression of NLRP3 inflammasome activation in hippocampus

Exercise has benefit for perimenopause women in many ways, such as affective disorders. Our previous study has demonstrated that inflammation in hippocampus contributes to development of depression-like behavior in ovariectomized (OVX) rats. Recently, oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome has been implicated to be involved in lipopolysaccharide (LPS)- and chronic stress-induced depression-like behavior in rodents. We sought to investigate whether ovariectomy-induced depression-like behavior is associated with NLRP3 inflammasome activation in brain and the effect of exercise on NLRP3 inflammasome activation in this model. The results showed that ovariectomy resulted in depression-like behavior in mice and an increase in levels of IL-1β and IL-18 in hippocampus. Exercise ameliorated the depression-like behavior and decreased levels of IL-1β and IL-18 in hippocampus. The level of IL-1β and IL-18 in hippocampus correlated to depression-like behavior in OVX mice. The levels of NLRP3, cleaved caspase-1 P10 and CD11b in hippocampus were increased in OVX mice compared with control group. Exercise could reduce the levels of NLRP3, cleaved caspase-1 P10 and CD11b in OVX mice. Our study suggests that NLRP3 inflammasome activation contribute to inflammation in hippocampus upon to deprivation of ovary. Exercise amelioration of depression-like behavior is associated with suppression of NLRP3 inflammasome activation in hippocampus of this model.