Aerobic exercise training-induced irisin secretion is associated with the reduction of arterial stiffness via nitric oxide production in adults with obesity

The mechanisms of exercise improving cardiovascular function by stimulating Piezo1 and TRP ion channels: a systemic review

Mechanosensitive ion channels are widely distributed in the heart, lung, bladder and other tissues, and plays an important role in exercise-induced cardiovascular function promotion. By reviewing the PubMed databases, the results were summarized using the terms "Exercise/Sport", "Piezo1", "Transient receptor potential (TRP)" and "Cardiovascular" as the keywords, 124-related papers screened were sorted and reviewed. The results showed that: (1) Piezo1 and TRP channels play an important role in regulating blood pressure and the development of cardiovascular diseases such as atherosclerosis, myocardial infarction, and cardiac fibrosis; (2) Exercise promotes cardiac health, inhibits the development of pathological heart to heart failure, regulating the changes in the characterization of Piezo1 and TRP channels; (3) Piezo1 activates downstream signaling pathways with very broad pathways, such as AKT/eNOS, NF-κB, p38MAPK and HIPPO-YAP signaling pathways. Piezo1 and Irisin regulate nuclear localization of YAP and are hypothesized to act synergistically to regulate tissue mechanical properties of the cardiovascular system and (4) The cardioprotective effects of exercise through the TRP family are mostly accomplished through Ca2+ and involve many signaling pathways. TRP channels exert their important cardioprotective effects by reducing the TRPC3-Nox2 complex and mediating Irisin-induced Ca2+ influx through TRPV4. It is proposed that exercise stimulates the mechanosensitive cation channel Piezo1 and TRP channels, which exerts cardioprotective effects. The activation of Piezo1 and TRP channels and their downstream targets to exert cardioprotective function by exercise may provide a theoretical basis for the prevention of cardiovascular diseases and the rehabilitation of clinical patients.

Differences in the Impact of Various Types of Exercise on Irisin Levels: A Systematic Review and Meta-Analysis

Background

Irisin, a myokine that is responsive to exercise, induces significant changes in subcutaneous adipose tissue. By promoting the browning of white fat tissue, it enhances energy expenditure, thereby addressing overweight and obesity. This systematic review and meta-analysis aimed to compare the effects of different types of physical exercises on irisin levels in overweight and obese adults.

Methods

Specifically, the review focused on studies involving obese or overweight individuals who participated in exercise training for a minimum of 8 weeks, with measured and reported changes in serum irisin levels compared to a control group. Data were collected from four databases (Google Scholar, ISI Web of Science Core Collection, PubMed, and Scopus). The risk of bias was assessed using the Begg and Egger tests, and the results were synthesized.

Results

Initial searches identified 560 titles, out of which only seven met the criteria for inclusion in the systematic review. Statistical analysis demonstrated a significant increase in serum irisin concentration (SMD = 0.957, P = 0.005) among obese and overweight individuals who engaged in exercise, compared to the passive control group. High-intensity interval training (HIIT) (SMD = 1.229, P < 0.001) had a more pronounced effect on increasing serum irisin levels than other exercise protocols. Furthermore, the effectiveness of exercise varied based on the participants' weight status (significant changes for overweight individuals; P < 0.001 and insignificant changes for obese individuals; P = 0.1), age (significant changes for those under 40 years old; P < 0.001 and insignificant changes for those over 40 years old; P = 0.322), and gender (significant changes for men; P < 0.001 and insignificant changes for women; P = 0.285).

Conclusions

Consequently, exercise can elevate serum irisin levels, leading to alterations in adipose tissue phenotype and thermogenesis, ultimately contributing to weight reduction in obese and overweight individuals.

Exercise ameliorating myocardial injury in type 2 diabetic rats by inhibiting excessive mitochondrial fission involving increased irisin expression and AMP-activated protein kinase phosphorylation

PURPOSE

Though exercise generates beneficial effects on diabetes-associated cardiac damage, the underlying mechanism is largely unclear. Therefore, we prescribed a program of 8-week treadmill training for type 2 diabetes mellitus (T2DM) rats and determined the role of irisin signaling, via interacting with AMP-activated protein kinase (AMPK), in mediating the effects of exercise on myocardial injuries and mitochondrial fission.

METHODS

Forty 8-week-old male Wistar rats were randomly divided into groups of control (Con), diabetes mellitus (DM), diabetes plus exercise (Ex), and diabetes plus exercise and Cyclo RGDyk (ExRg). Ex and ExRg rats received 8 weeks of treadmill running, and the rats in the ExRg group additionally were treated with a twice weekly injection of Cyclo RGDyk, an irisin receptor-αV/β5 antagonist. At the end of the experiment, murine blood samples and heart tissues were collected and analyzed with methods of ELISA, Western blot, real-time quantitative polymerase chain reaction, as well as immunofluorescence staining.

RESULTS

Exercise effectively mitigated T2DM-related hyperglycemia, hyperinsulinemia, lipid dysmetabolism, and inflammation, which could be diminished by Cyclo RGDyk treatment. Additionally, exercise alleviated T2DM-induced myocardial injury and excessive mitochondrial fission, whereas the beneficial effects were blocked by the administration of Cyclo RGDyk. T2DM significantly decreased serum irisin concentrations and fibronectin type III domain-containing protein 5 (FNDC5)/irisin gene and protein expression levels in the rat heart, whereas exercise could rescue T2DM-reduced FNDC5/irisin expression. Blocking irisin receptor signaling diminished the exercise-alleviated mitochondrial fission protein expression and elevated AMPK phosphorylation.

CONCLUSION

Exercise is effective in mitigating diabetes-related insulin resistance, metabolic dysfunction, and inflammation. Irisin signaling engages in exercise-associated beneficial effects on myocardial injury and excessive mitochondrial fission in diabetes rats involving elevated AMPK phosphorylation.

Association of Lower Extremity Muscle Strength and Function with Renal Resistive Index in Individuals with and without Chronic Kidney Disease

Age-related loss of lower extremity muscle strength is pronounced in individuals with chronic kidney disease (CKD). In contrast, an increase in intrarenal flow pulsatility results in initial age-related changes in renal hemodynamics, leading to the development of CKD. To date, it remains unclear whether lower extremity muscle strength determines elevated renal flow pulsatility. This study aimed to determine the association of lower extremity muscle strength and function with intrarenal hemodynamics in individuals with and without CKD. One hundred seventy-six individuals without CKD (aged 63 ± 9 years) and 101 individuals with CKD (aged 66 ± 8 years) were included in this study. Using Doppler ultrasound, the renal resistive index (RI) was measured as a parameter of renal hemodynamics. Knee extensor muscle strength (KES), gait speed (GS), and the 30 s chair stand test (30s-CST) were used to measure lower extremity muscle strength and function. Multivariate analyses showed that GS and 30s-CST scores were independent determinants of renal RI, whereas the KES score was not associated with renal RI in individuals with and without CKD. In the two-way analysis of covariance, renal RI was the highest in individuals with CKD who had lower KES, GS, and 30s-CST scores. Reduced lower extremity muscle strength and function are independent determinants of elevated renal flow pulsatility in individuals with and without CKD.

Relationships between circulating irisin levels, cardiorespiratory fitness, and cardiometabolic risk: a cross-sectional study in Japanese adults

High cardiorespiratory fitness levels achieved through regular aerobic exercise are associated with reduced cardiometabolic risk. The exercise-induced myokine irisin possibly mediates these associations, but these relationships are unclear. This study aimed to clarify the relationships between circulating irisin levels, cardiorespiratory fitness levels, and cardiometabolic risk factors adjusted for sex and age. This cross-sectional study included 328 Japanese participants aged between 18 and 88 yr. We measured serum irisin levels and peak oxygen uptake (V̇o2peak) as cardiorespiratory fitness indicators, and body fat percentage, blood pressure, fasting blood glucose, hemoglobin A1c (HbA1c), high-density lipoprotein (HDL) cholesterol, and triglycerides as cardiometabolic risk factors. Cardiometabolic risk scores were calculated from the z-scores of the cardiometabolic risk factors. Quintiles based on V̇o2peak or irisin values, categorized by sex, showed a gradual increase in HDL cholesterol and a gradual decrease in other cardiometabolic risk factors with an increase in cardiorespiratory fitness levels or irisin. Serum irisin levels were negatively correlated with body fat percentage, blood pressure, fasting blood glucose, HbA1c, triglyceride levels, and cardiometabolic risk score and positively correlated with HDL cholesterol levels and V̇o2peak in both sexes and young, and middle-aged and older adults. The same relationship was observed in all participants after adjusting for sex and age. These results suggest that circulating irisin levels may be involved in the association between cardiorespiratory fitness and cardiometabolic risk factors, regardless of sex and age.NEW & NOTEWORTHY Circulating irisin levels gradually increased, and cardiometabolic risks gradually decreased with increasing cardiorespiratory fitness levels. The fitness levels required to increase irisin levels were moderate for young adults and lower than moderate for middle-aged and older adults. Moreover, circulating irisin levels are correlated with a reduction in cardiometabolic risk and an increase in cardiorespiratory fitness. These data suggest that circulating irisin levels are involved in the association between cardiorespiratory fitness and cardiometabolic risk.

Irisin: A Potentially Fresh Insight into the Molecular Mechanisms Underlying Vascular Aging

Aging is a natural process that affects all living organisms, including humans. Aging is a complex process that involves the gradual deterioration of various biological processes and systems, including the cardiovascular system. Vascular aging refers to age-related changes in blood vessels. These changes can increase the risk of developing cardiovascular diseases, such as hypertension, atherosclerosis, and stroke. Recently, an exercise-induced muscle factor, irisin, was found to directly improve metabolism and regulate the balance of glucolipid metabolism, thereby counteracting obesity and insulin resistance. Based on a growing body of evidence, irisin modulates vascular aging. Adenosine monophosphate-activated protein kinase (AMPK) serves as a pivotal cellular energy sensor and metabolic modulator, acting as a central signaling cascade to coordinate various cellular processes necessary for maintaining vascular homeostasis. The vascular regulatory effects of irisin are closely intertwined with its interaction with the AMPK pathway. In conclusion, understanding the molecular processes used by irisin to regulate changes in vascular diseases caused by aging may inspire the development of techniques that promote healthy vascular aging. This review sought to describe the impact of irisin on the molecular mechanisms of vascular aging, including inflammation, oxidative stress, and epigenetics, from the perspective of endothelial cell function and vascular macroregulation, and summarize the multiple signaling pathways used by irisin to regulate vascular aging.

Handgrip strength is inversely associated with augmentation index in patients with type 2 diabetes

Handgrip strength (HGS) is a measure of overall skeletal muscle strength and is used to identify risks for cardiovascular disease and mortality. Furthermore, HGS is an indicator of arterial stiffness that leads to atherosclerotic cardiovascular disease. This study aimed to examine the relationship between HGS and augmentation index (AIx) in patients with type 2 diabetes. A cross-sectional study was conducted to examine patients with type 2 diabetes whose HGS and AIx were measured in our hospital. AIx was measured noninvasively using an applanation tonometer, and multiple regression analyses were conducted to assess the independent relationship between HGS and AIx. This study included 404 patients. After adjusting for age, gender, body mass index, duration of diabetes, smoking and exercise habit, biochemical parameters, and physiological parameters related to arterial stiffness, HGS was found to be independently and inversely associated with AIx (β = - 0.270, p = 0.006). HGS was independently and inversely associated with AIx in patients with type 2 diabetes. Patients with diminished HGS should be subjected to intensive exercise therapy for reducing the risk of arterial stiffness and cardiovascular disease.Trial registration: UMIN000023010.

Aerobic exercise alleviates pyroptosis-related diseases by regulating NLRP3 inflammasome

Pyroptosis plays a crucial role in a variety of human diseases, including atherosclerosis, obesity, diabetes, depression, and Alzheimer’s disease, which usually release pyroptosis-related cytokines due to inflammation. Many studies have demonstrated that aerobic exercise is a good option for decreasing the release of pyroptosis-related cytokines. However, the molecular mechanisms of aerobic exercise on pyroptosis-related diseases remain unknown. In this review, the effects of aerobic exercise on pyroptosis in endothelial cells, adipocytes and hippocampal cells, and their potential mechanisms are summarized. In endothelial cells, aerobic exercise could inhibit NOD-like receptor protein 3 (NLRP3) inflammasome-mediated pyroptosis by improving the endothelial function, while reducing vascular inflammation and oxidative stress. In adipocytes, aerobic exercise has been shown to inhibit pyroptosis by ameliorating inflammation and insulin resistance. Moreover, aerobic exercise could restrict pyroptosis by attenuating microglial activation, neuroinflammation, and amyloid-beta deposition in hippocampal cells. In summary, aerobic exercise alleviates the pyroptosis-related diseases by regulating the NLRP3 inflammation si0067naling.

Irisin, an Effective Treatment for Cardiovascular Diseases?

Irisin, as one of the myokines induced by exercise, has attracted much attention due to its important physiological functions such as white fat browning, the improvement in metabolism, and the alleviation of inflammation. Despite the positive role that irisin has been proven to play in the prevention and treatment of cardiovascular diseases, whether it can become a biomarker and potential target for predicting and treating cardiovascular diseases remains controversial, given the unreliability of its detection methods, the uncertainty of its receptors, and the species differences between animals and humans. This paper was intended to review the role of irisin in the diagnosis and treatment of cardiovascular diseases, the potential molecular mechanism, and the urgent problems to be solved in hopes of advancing our understanding of irisin as well as providing data for the development of new and promising intervention strategies by discussing the causes of contradictory results.

Irisin Is Related to Non-Alcoholic Fatty Liver Disease (NAFLD)

Irisin is a cytokine involved in many metabolic pathways occurring, among others, in muscles, adipose tissue and liver. Thus, fluctuations in irisin levels are suggested to be related to metabolic diseases. Therefore, the purpose of our study was to evaluate whether irisin may be associated with non-alcoholic fatty liver disease (NAFLD). A total of 138 patients (70/68 male/female, mean age 65.61 ± 10.44 years) were enrolled in the study. The patients were assigned to the NAFLD group (n = 72, including 46 patients with type 2 diabetes (T2DM]) and the group without NAFLD (n = 66, 31 patients with T2DM). NAFLD was diagnosed based on ultrasound examination, Hepatic Steatosis Index (HSI) and Fatty Liver Index. Baseline anthropometric, blood pressure and biochemical parameters were collected. The serum irisin level was determined using an ELISA test. We observed that NAFLD was associated with an increased concentration of irisin. Moreover, Spearman correlations and linear regression analysis revealed that irisin level correlates with some anthropometric and biochemical parameters such as body mass index, glycated hemoglobin, aspartic aminotransferase, creatinine and urea. Logistic regression analysis depicted that odds for NAFLD increase 1.17 times for each 1 μg/mL rise of irisin concentration. Finally, ROC analysis showed that the concentration of irisin possesses a discriminate capacity for NAFLD and optimal cut points concentration could be designed. The risk of NAFLD in the subgroup with irisin concentration above 3.235 μg/mL was 4.57 times higher than in patients with the lower concentration of irisin. To conclude, the obtained results suggest that irisin concentration is associated with some anthropometric and biochemical parameters and should be further investigated toward its usage as a diagnostic biomarker of NAFLD.

Irisin Regulates Cardiac Responses to Exercise in Health and Diseases: a Narrative Review

Exercise has been recognized as an important non-pharmacological approach for the prevention, treatment, and rehabilitation of cardiovascular diseases, but the mechanisms of exercise in promoting cardiovascular health remain unclear. Exercise generates cardiac benefits via stimulating muscle to secret hundreds of myokines that directly enter circulation and target heart tissue. Therefore, inter-organ communication between skeletal muscle and heart may be one important regulating pattern, and such communication can occur through secretion of molecules, frequently known as myokines. Irisin, a newly identified myokine, is cleaved from fibronectin type III domain-containing protein 5 (FNDC5) and secreted by the stimulation of exercise. Recently, accumulating evidence focusing on the interaction between irisin and cardiac function has been reported. This review highlights the molecular signaling by which irisin regulates the benefits of exercise on cardiac function both in physiological and pathological process, and discusses the clinical potential of irisin in treating heart diseases. Exercise generates various cardiovascular benefits through stimulating skeletal muscle to secrete irisin. The exercise "hormone" irisin, both produced by exercise or recombinant form, exerts therapeutic effects in a group of cardiovascular disorders including heart failure, myocardial infarction, atherosclerosis and hypertension. However, the molecular mechanisms involved remain ambiguous.This review highlights the most up-to-date findings to bridge the gap between exercise, irisin and cardiovascular diseases, and discusses the potential clinical prospect of irisin.

Time-dependent relationships between exercise training-induced changes in nitric oxide production and hormone regulation

Aerobic exercise training (AT) reduces aging-induced deterioration of arterial stiffness and is associated with arterial nitric oxide (NO) production via changes in apelin and adropin as NO-upregulating hormones, and asymmetric dimethylarginine (ADMA) as a NO-downregulating hormone. However, the time-dependent effects of AT on NO production via NO-regulating hormones remain unclear. This study aimed to determine whether AT-induced changes in the time course of NO production via NO-regulating hormones, participate in the AT-induced improvement in central arterial stiffening with advancing age. Methods: Thirty-three healthy Japanese middle-aged and older subjects (67 ± 1 years) were randomly divided into two groups: AT intervention and sedentary controls. Subjects in the training group completed 8-week of AT. Carotid-femoral pulse wave velocity as an index of central arterial stiffness and plasma nitrate/nitrite levels significantly changed from baseline at weeks 6 (P < 0.05) and 8 (P < 0.01). Interestingly, circulating apelin and adropin levels gradually increased during AT intervention and significantly increased from baseline at weeks 4, 6, and 8 (P < 0.01). Additionally, plasma ADMA levels significantly decreased at 8-week AT intervention (P < 0.01). These results suggest that AT-induced changes in the time course of NO production via NO-regulating hormones may participate in AT-induced improvements of central arterial stiffening with advancing age.

Irisin is an Effector Molecule in Exercise Rehabilitation Following Myocardial Infarction (Review)

Background: Regular exercise is an effective non-pharmacological therapy for treatment and prevention of cardiovascular disease (CVD). The therapeutic benefits of exercise are mediated partly through improved vascular and increase in metabolic health. Release of exercise-responsive myokines, including irisin, is associated with beneficial effects of exercise in CVD patients.

Observations: The present review provides an overview of the role of exercise in cardiac rehabilitation of patients with myocardial infarction (MI). Further, the role of irisin as a motion-responsive molecule in improving vascular and metabolic health is explored. Possible mechanism of cardioprotective effect of irisin-mediated exercise on myocardial infarction are also summarized in this review.

Conclusion and significance of the review: Irisin is associated with reduced inflammation, antioxidant properties, and anti-apoptotic effect, implying that it is a potential key mediator of the beneficial effects of exercise on vascular and metabolic health. The findings show that irisin is a promising therapeutic target for treatment of patients with cardiovascular disease, particularly post-MI. Further research should be conducted to elucidate the potential mechanisms of cardioprotective effects of irisin and explored whether irisin induced by exercise exerts rehabilitation effects post-MI.

Aerobic exercise training-induced follistatin-like 1 secretion in the skeletal muscle is related to arterial stiffness via arterial NO production in obese rats

Follistatin‐like 1 (FSTL1), which is mainly secreted from skeletal muscle and myocardium, upregulates protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) phosphorylation in vascular endothelial cells. It is unclear whether skeletal muscle‐ and myocardium‐derived FSTL1 secretion induced by aerobic exercise training is involved in the reduction of arterial stiffness via arterial NO production in obese rats. This study aimed to clarify whether aerobic exercise training‐induced FSTL1 secretion in myocardium and skeletal muscle is associated with a reduction in arterial stiffness via arterial Akt‐eNOS signaling pathway in obese rats. Sixteen Otsuka Long‐Evans Tokushima Fatty (OLETF) obese rats were randomly divided into two groups: sedentary control (OLETF‐CON) and eight‐week aerobic exercise training (treadmill for 60min at 25m/min, 5days/week, OLETF‐AT). Eight Long‐Evans Tokushima Otsuka (LETO) rats were used as a healthy sedentary control group. In OLETF‐CON, serum FSTL1, arterial Akt and eNOS phosphorylation, and arterial nitrite/nitrate (NOx) levels were significantly lower, and carotid‐femoral pulse wave velocity (cfPWV) was significantly greater than those in LETO. These parameters were improved in the OLETF‐AT compared to the OLETF‐CON. In the OLETF‐AT, FSTL1 levels in slow‐twitch fiber‐rich soleus muscle were significantly greater than those in the OLETF‐CON, but not in myocardium, fast‐twitch fiber‐rich tibialis anterior muscle, and adipose tissue. Serum FSTL1 levels were positively correlated with soleus FSTL1, arterial eNOS phosphorylation, and NOx levels and negatively correlated with cfPWV. Thus, aerobic exercise training‐induced FSTL1 secretion in slow‐twitch fiber‐rich muscles may be associated with a reduction in arterial stiffness via arterial NO production in obese rats.

Effect of Exercise Training on Arterial Stiffness in Overweight or Obese Populations

The purpose was to analyze the effects of exercise training (ET) on arterial stiffness in all-age overweight or obese individuals. Sixty-one trials were included with ET improving flow-mediated dilation (FMD), pulse wave velocity (PWV), and intima-media thickness (IMT). In the subgroup analysis: (i) ET improved FMD in overweight or obese children and adolescents with a large effect size (SMD=0.83, 95% CI 0.42–1.25). PWV was decreased after ET regardless of age. IMT was decreased by ET in participants younger than 60, (ii) ET improved FMD, PWV, and IMT in participants whose BMI were smaller than 30 kg/m ² , but ET only improved PWV of participants whose BMI were larger than 30 kg/m ² . (iii) AE improved FMD, PWV, and IMT. High-intensity interval training (HIIT) decreased IMT. (iv) The increase of FMD only happened when training duration was longer than eight weeks. However, ET decreased PWV when the training duration was no longer than 12 weeks. IMT was decreased when the training duration was longer than eight weeks. ET instigated an improvement in endothelial function and arterial stiffness in overweight or obese populations, but depending on the different characteristics of exercise intervention and participants’ demographics.

Application Value of Health Education Combined with Aerobic Exercise in Nursing of Patients with Mastitis Found in Physical Examination

Objective

To explore the application value of health education combined with aerobic exercise in patients with mastitis found in physical examination.

Methods

The clinical data of 100 patients with mastitis who underwent physical examination in the physical examination center of our hospital from October 2020 to October 2021 were retrospectively analyzed. According to the order of physical examination, they were equally split into experimental group and control group. The control group received the routine clinical intervention, while the experimental group received health education combined with aerobic exercise to evaluate the clinical effects of different intervention modes on patients with mastitis.

Results

Compared with the control group, the experimental group after intervention achieved notably higher scores of CD-RISC, self-management ability, and mastitis-related knowledge (P < 0.001), lower scores of breast pain, skin color, and local mass diameter (P < 0.001), and a higher SF-36 score (P < 0.001).

Conclusion

The clinical intervention combining health education with aerobic exercise in patients with mastitis found in the physical examination is an effective method to improve their mood state and self-management ability, and further research will help provide a good solution for such patients.

Too hard to die: Exercise training mediates specific and immediate SARS-CoV-2 protection

Several mechanisms may explain how exercise training mechanistically confers protection against coronavirus disease 2019 (COVID-19). Here we propose two new perspectives through which cardiorespiratory fitness may protect against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Physical exercise-activated adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling induces endothelial nitric oxide (NO) synthase (eNOS), increases NO bio-availability, and inhibits palmitoylation, leading to specific and immediate SARS-CoV-2 protection. AMPK signaling also induces angiotensin 1-7 release and enhances eNOS activation thus further mediating cardio- and reno-protection. Irisin, a myokine released from skeletal muscles during aerobic exercise, also participates in the AMPK/Akt-eNOS/NO pathway, protects mitochondrial functions in endothelial cells, and antagonizes renin angiotensin system proinflammatory action leading to reductions in genes associated with severe COVID-19 outcomes. Collectively, all the above findings point to the fact that increased AMPK and irisin activity through exercise training greatly benefits molecular processes that mediate specific, immediate, and delayed SARS-CoV-2 protection. Maintaining regular physical activity levels is a safe and affordable lifestyle strategy against the current and future pandemics and may also mitigate against obesity and cardiometabolic disease syndemics. Move more because a moving target is harder to kill.

Irisin: A Promising Target for Ischemia-Reperfusion Injury Therapy

Ischemia-reperfusion injury (IRI) is defined as the total combined damage that occurs during a period of ischemia and following the recovery of blood flow. Oxidative stress, mitochondrial dysfunction, and an inflammatory response are factors contributing to IRI-related damage that can each result in cell death. Irisin is a polypeptide that is proteolytically cleaved from the extracellular domain of fibronectin type III domain-containing protein 5 (FNDC5). Irisin acts as a myokine that potentially mediates beneficial effects of exercise by reducing oxidative stress, improving mitochondrial fitness, and suppressing inflammation. The existing literature also suggests a possible link between irisin and IRI, involving mechanisms similar to those associated with exercise. This article will review the pathogenesis of IRI and the potential benefits and current limitations of irisin as a therapeutic strategy for IRI, while highlighting the mechanistic correlations between irisin and IRI.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Aging under Pressure: The Roles of Reactive Oxygen and Nitrogen Species (RONS) Production and Aging Skeletal Muscle in Endothelial Function and Hypertension-From Biological Processes to Potential Interventions

The proportion of adults living with hypertension increases significantly with advancing age. It is therefore important to consider how health and vitality can be maintained by the aging population until end of life. A primary risk factor for the progression of cardiovascular diseases (CVD) is hypertension, so exploring the factors and processes central to this burden of disease is essential for healthy aging. A loss of skeletal muscle quantity and quality is characteristic in normal aging, with a reduction of vasodilatory capacity caused by endothelial dysfunction, and subsequent increase in peripheral resistance and risk for hypertension. Reactive Oxygen and Nitrogen Species (RONS) encompass the reactive derivatives of NO and superoxide, which are continuously generated in contracting skeletal muscle and are essential mediators for cellular metabolism. They act together as intra and intercellular messengers, gene expression regulators, and induce programmed cell death. In excessive amounts RONS can inflict damage to endothelial and skeletal muscle cells, alter signaling pathways or prematurely promote stress responses and potentially speed up the aging process. The age-related increase in RONS by skeletal muscle and endothelial mitochondria leads to impaired production of NO, resulting in vascular changes and endothelial dysfunction. Changes in vascular morphology is an early occurrence in the etiology of CVDs and, while this is also a normal characteristic of aging, whether it is a cause or a consequence of aging in hypertension remains unclear. This review serves to focus on the roles and mechanisms of biological processes central to hypertension and CVD, with a specific focus on the effects of aging muscle and RONS production, as well as the influence of established and more novel interventions to mediate the increasing risk for hypertension and CVD and improve health outcomes as we age.

Sex and body mass index dependent associations between serum 25-hydroxyvitamin D and pulse pressure in middle-aged and older US adults

High pulse pressure (PP) is a valid indicator of arterial stiffness. Many studies have reported that vitamin D concentration is inversely associated with vascular stiffening. This association may differ depending on sex and body mass index (BMI). This study investigated the associations between vitamin D and PP and evaluated whether these associations differ according to sex and BMI, using data for individuals aged ≥ 50 years from the National Health and Nutrition Examination Survey (NHANES) 2007-2010. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were used as biomarkers of vitamin D levels. High PP was defined as ≥ 60 mmHg. Total 25(OH)D concentrations were dose-dependently associated with lower odds ratios (ORs) for high PP (p-trend = 0.01), after controlling for sociodemographic, behavioral, and dietary factors. When stratified by sex, there was a dose-dependent association between total 25(OH)D concentrations and lower risk of high PP (p-trend < 0.001) in females, but not in males. When stratified by BMI, there was a dose-dependent association between total 25(OH)D concentrations and lower risk of high PP (p-trend < 0.001) in non-overweight subjects, but not in overweight subjects. Improving the vitamin D status could delay elevation of PP and vascular stiffening in female and non-overweight subjects.

Impact of Acute Circuit Training on Irisin in Younger and Older Overweight Adults

Studies show aerobic exercise increases irisin and leads to health benefits. The impact of circuit training (CT) on irisin in overweight younger and older adults is unknown. The objectives were to determine whether, during an acute bout of CT, changes in irisin differed between overweight younger and older adults, and if irisin is associated with body composition, fitness level, or muscle strength. Inactive, overweight adults aged between 19-35 (25.9 ± 5.0; n=15) and 60-75 years old (67.7 ± 4.1; n=14) participated in this study. The primary exposure variable was an acute bout of CT (12-15 repetitions; 65-70% of 1-repetition maximum; 3 loops). The primary outcome measure was the concentration of irisin determined by ELISA before, during, and after exercise. Repeated measures analyses showed no effect of time on irisin levels during acute CT, and no interaction effect between age and time (p >0.05). No associations were observed between changes in irisin and body composition, fitness, or strength (p >0.05). In conclusion, acute CT doesn't increase irisin in overweight individuals, nor is irisin associated with the measured outcomes. Further studies are needed to elucidate the release of irisin by different types of exercise across the lifespan. NCT03715088 NOVELTY: • Younger and older adults show a similar irisin response to an acute bout of circuit training. • Irisin response is not associated with measures of body composition, cardiorespiratory fitness, nor muscle strength.

Oxidative Stress and Vascular Damage in the Context of Obesity: The Hidden Guest

The vascular system plays a central role in the transport of cells, oxygen and nutrients between different regions of the body, depending on the needs, as well as of metabolic waste products for their elimination. While the structure of different components of the vascular system varies, these structures, especially those of main arteries and arterioles, can be affected by the presence of different cardiovascular risk factors, including obesity. This vascular remodeling is mainly characterized by a thickening of the media layer as a consequence of changes in smooth muscle cells or excessive fibrosis accumulation. These vascular changes associated with obesity can trigger functional alterations, with endothelial dysfunction and vascular stiffness being especially common features of obese vessels. These changes can also lead to impaired tissue perfusion that may affect multiple tissues and organs. In this review, we focus on the role played by perivascular adipose tissue, the activation of the renin-angiotensin-aldosterone system and endoplasmic reticulum stress in the vascular dysfunction associated with obesity. In addition, the participation of oxidative stress in this vascular damage, which can be produced in the perivascular adipose tissue as well as in other components of the vascular wall, is updated.

The production, detection, and origin of irisin and its effect on bone cells

Irisin is a muscle factor discovered in 2012 that plays an important role in many tissues, including bone. Eight years since its discovery, there are still many controversies regarding its molecular biology, detection, and effects on bone. This article summarizes the points raised to date, and discusses the mechanisms by which irisin regulates bone cells. The information reviewed here provides a useful foundation for future research.

Irisin: A New Code Uncover the Relationship of Skeletal Muscle and Cardiovascular Health During Exercise

Exercise not only produces beneficial effects on muscle itself via various molecular pathways, but also mediates the interaction between muscles and other organs in an autocrine/paracrine manner through myokines, which plays a positive role in maintaining overall health. Irisin, an exercise-derived myokine, has been found involved in the regulation of some cardiovascular diseases. However, the relationship between irisin and cardiovascular health is not fully elucidated and there are some divergences on the regulation of irisin by exercise. In this review, we present the current knowledge on the origin and physiology of irisin, describe the regulation of irisin by acute and chronic exercises, and discuss the divergences of the related research results. Importantly, we discuss the role of irisin as a biomarker in the diagnosis of cardiovascular diseases and describe its treatment and molecular mechanism in some cardiovascular diseases. It is expected that irisin will be used as a therapeutic agent to combat cardiovascular diseases or other disorders caused by inactivity in the near future.

Lower Serum Irisin Levels Are Associated with Increased Abdominal Aortic Calcification in Peritoneal Dialysis Patients

Introduction

Vascular calcification (VC), with the mechanisms remaining unclear, is closely related with dialysis patients' cardiovascular mortality and all-cause mortality. Irisin is a newly identified myokine. This study aims to evaluate the serum irisin levels of peritoneal dialysis (PD) patients and their relationship with VC.

Methods

This cross-sectional study enrolled stable PD patients in Peking University Third Hospital who were followed for >6 months. We used plain X-ray films of abdomen to quantitatively evaluate VC of abdominal aorta. VC was evaluated by abdominal aortic calcification (AAC) scores, and PD patients were divided into the high AAC score group (AAC score ≥4) and the low AAC score group (AAC score <4). Demographic data and laboratory indexes were collected. Serum irisin concentrations were measured by enzyme-linked immunosorbent assay.

Results

A total of 102 PD patients were enrolled in this study, and 52 patients (51.0%) were found to have a high AAC score of ≥4. Age, diabetic mellitus proportion, pulse pressure, hypercalcemia (corrected calcium >2.54 mmol/L) rate, serum ultrasensitive C reactive protein, and AAC scores were significantly higher in the high AAC score group than those of the low AAC score group (p < 0.05). The high AAC score group had lower diastolic blood pressure, serum albumin, and serum carbon dioxide combining power compared with the low AAC score group (p < 0.05). Serum irisin levels of PD patients with a high AAC score were significantly lower than those of PD patients with a low AAC score (109.7 ± 13.1 ng/mL vs. 115.9 ± 10.1 ng/mL, p = 0.010). The multivariate logistic regression analyses showed that serum irisin, diabetic mellitus, serum ultrasensitive C reactive protein, and age were independent factors influencing the occurrence of VC in PD patients.

Conclusion

Our results are the first to provide a clinical evidence of the association between serum irisin and abdominal aortic calcification in PD patients. Lower irisin levels, diabetic mellitus, higher serum ultrasensitive C reactive protein, and older age could be potential predictive factors for VC in PD patients.

Two Months of Using Global Recommendations for Physical Activity Had No Impact on Cognitive or Motor Functions in Overweight and Obese Middle-Aged Women

BACKGROUND

The effect of globally recommended levels of physical activity on cognition and motor behavior is not completely understood. Therefore, the main aim of this study was to assess the effect of 300 minutes per week of moderate-intensity aerobic exercise on cognitive and motor performance among overweight and obese working-age women.

METHODS

Overweight and obese participants aged 38-56 years were randomized to either a control or an experimental group performing aerobic exercise at 50% to 60% of the peak oxygen consumption for a 2-month period. Changes in aerobic fitness, cardiac autonomic function, brain-derived neurotropic factor levels, and cognitive and motor performance were assessed.

RESULTS

Although aerobic exercise reduced body weight (P < .05) and improved peak oxygen consumption (P < .05), the brain-derived neurotropic factor levels and cognitive and motor performance remained unchanged. Heart rate and blood pressure decreased (P < .05), whereas heart rate variability indices were not affected. No significant correlations between changes in heart rate variability indices and cognition were observed.

CONCLUSIONS

Two months of moderate-intensity aerobic exercise decreased sympathetic activity and improved cardiovascular fitness but had no impact on cognition or motor control among these middle-aged, overweight, and obese women.

Concentrations of Circulating Irisin and Myostatin in Race and Endurace Purebred Arabian Horses-Preliminary Study

Simple Summary

Irisin and myostatin are regulatory proteins produced by muscle cells. The aim of the study was to evaluate the effect of exercise on plasma irisin and myostatin concentrations in horses in different types of training (speed versus endurance). To find out, we tested 20 Arabian horses, submitted to the two different equestrian disciplines, and consequently different training regimes. The first group of horses realized a short-term, high-speed bout of exercise whereas the second group of horses were submitted to long-lasting, endurance effort. The obtained results showed that the single bout of exercise induced an increase in plasma myostatin concentration. Plasma irisin level decreased during the race season in racehorses. This means that irisin and myostatin may play a regulatory role in the maintenance of the energy balance processes.

Abstract

Skeletal muscle is considered to be the largest endocrine organ determining the maintenance of energy homeostasis. Adaptive changes in skeletal muscles in response to physical exercise influence the production as well as secretion of myokines, which are bioactive factors that play a crucial role in energy expenditure processes. The aim of the study was to investigate the impact of two different types of exercise on the circulating level of two of these, myostatin and irisin, in trained horses. Twenty purebred Arabian horses were involved in the study: 10 three-year-old horses trained on the racetrack and 10 endurance horses aged 7.4 ± 1.9 years. The horses from both groups were regularly trained throughout the entire season, during which they also participated in Polish National competitions. To assess the influence of the training sessions on plasma myostatin and irisin concentrations, blood samples taken at rest and 30 min after the end of exercise were analyzed. In the studied horses, the single bout of exercise did not influence plasma irisin but induced an increase in plasma myostatin concentration. In racehorses, plasma irisin concentration decreased with the length of the training season. Plasma myostatin was higher in endurance horses than in three-year-old racehorses. Lack of exercise-induced fluctuation in circulating irisin in studied horses suggests that myostatin released in response to exercise provides a negative feedback signal to irisin release.