Exercise-Induced Irisin, the Fat Browning Myokine, as a Potential Anticancer Agent

Irisin: muscle's novel player in endoplasmic reticulum stress and disease

Irisin, an exercise-induced myokine, exhibits elevated levels during physical activity, yet its role in modulating the unfolded protein response (UPR) remains poorly understood. This comprehensive review pioneers an in-depth examination of irisin-mediated endoplasmic reticulum (ER) stress mitigation across various diseases. We provide a nuanced characterization of irisin's molecular profile, biological activity, and significance as a skeletal muscle-derived cytokine analogue. Our discussion elucidates the complex interplay between exercise, irisin signalling, and metabolic outcomes, highlighting key molecular interactions driving salutary effects. Moreover, we delineate the UPR's role as a critical ER stress countermeasure and underscore irisin's pivotal function in alleviating this stress, revealing potential therapeutic avenues for disease management. Exercise-induced release of irisin ameliorates ER stress through AMPK phosphorylation during various diseases (Icon image source: www.flaticon.com ).

Antioxidant-Rich Functional Foods and Exercise: Unlocking Metabolic Health Through Nrf2 and Related Pathways

This article reviews the synergistic effects of antioxidant-enriched functional foods and exercise in improving metabolic health, focusing on the underlying molecular mechanisms. The review incorporates evidence from PubMed, SCOPUS, Web of Science, PsycINFO, and reference lists of relevant reviews up to 20 December 2024, highlighting the central role of the Nrf2 pathway. As a critical regulator of oxidative stress and metabolic adaptation, Nrf2 mediates the benefits of these interventions. This article presents an innovative approach to understanding the role of Nrf2 in the regulation of oxidative stress and inflammation, highlighting its potential in the prevention and treatment of various diseases, including cancer, neurodegenerative disorders, cardiovascular and pulmonary diseases, diabetes, inflammatory conditions, ageing, and infections such as COVID-19. The novelty of this study is to investigate the synergistic effects of bioactive compounds found in functional foods (such as polyphenols, flavonoids, and vitamins) and exercise-induced oxidative stress on the activation of the Nrf2 pathway. This combined approach reveals their potential to improve insulin sensitivity and lipid metabolism and reduce inflammation, offering a promising strategy for the management of chronic diseases. However, there are significant gaps in current research, particularly regarding the molecular mechanisms underlying the interaction between diet, physical activity, and Nrf2 activation, as well as their long-term effects in different populations, including those with chronic diseases. In addition, the interactions between Nrf2 and other critical signalling pathways, including AMPK, NF-κB, and PI3K/Akt, and their collective contributions to metabolic health are explored. Furthermore, novel biomarkers are presented to assess the impact of these synergistic strategies, such as the NAD+/NADH ratio, the GSH ratio, and markers of mitochondrial health. The findings provide valuable insights into how the integration of an antioxidant-rich diet and regular exercise can improve metabolic health by activating Nrf2 and related molecular pathways and represent promising strategies for the prevention and treatment of metabolic disorders. Further studies are needed to fully understand the therapeutic potential of these interventions in diseases related to oxidative stress, such as cardiovascular disease, neurodegenerative disease, diabetes, and cancer.

The role of irisin and cytokines in the etiology of parotid tumors

This study explores the role of irisin and interleukins in parotid tumors by determining the tissue staining intensity of irisin, the salivary and plasma levels of irisin, and the plasma levels of IL-4, IL-6, IL-10 and TNF-alpha in individuals with parotid tumors. Forty-eight patients and forty healthy individuals were included to the study and allocated into four group. Benign Group I (pleomorphic adenoma), Group II (Warthin's tumor), Group III (mucoepidermoid carcinoma) and Group IV (benign parotid control group, healthy control group). Parotid tissue, plasma and saliva samples were collected from each of the patients with parotid tumors, while plasma and saliva samples were collected from the healthy individuals. Normal parotid tissue for histologic evaluation was obtained from unaffected areas in patients with parotid tumors. The levels of irisin in the plasma and saliva were significantly lower in the parotid tumors, while the plasma levels of IL-6 and TNF-alpha were higher in patients with parotid tumors, but no statistically significant difference in IL-4 and IL-10 levels was found. The histopathological intensity of FNDC-5/irisin staining was significantly decreased in the parotid tumor tissues when compared to the benign parotid control group with normal parotid tissue. The low histopathological tissue staining intensity and plasma and salivary levels of irisin suggest that irisin may be a protective protein in parotid tumors.

Key Risk Factors, Sex Differences, and the Influence of High-Intensity Exercise on Colorectal Carcinogenesis: A 10-Year Cohort Study Based on 1,120,377 Individuals from the NHISS Data

Colorectal cancer (CRC) is the third most common cancer globally. Therefore, this study aims to examine data from the National Health Insurance Sharing Service (NHISS) to investigate factors influencing colon cancer incidence, focusing on key variables and optimal cutoff points. The patient cohort from the NHISS database included 1,120,377 individuals aged 1-85 years. CRC data were retrieved using diagnostic codes from the Korean Standard Classification of Diseases and Causes of Death. Analyses included logistic regression and receiver operating characteristic curve assessments. In this retrospective cohort study, 1,120,377 patients were analyzed for over 10 years, including 2802 with CRC via propensity score matching (PSM). Key risk factors were blood pressure, fasting blood sugar, liver somatic index, alcohol consumption, smoking duration, and hemoglobin levels. Patients with CRC showed sex differences in gamma-glutamyl transpeptidase (GGT). High-intensity exercise (3 days/week) reduced CRC risk by 26% (p < 0.05). Optimal threshold points for GGT and Charlson Comorbidity Index (CCI) were 23.50 U/L (AUC, 0.52) and 1.50 (AUC, 0.58), respectively. CCI scores were higher in patients with cancer, especially men with peptic ulcers and both sexes with metastatic cancer (p < 0.01). Our findings reveal new risk factors and interventions, including tailored exercise programs for CRC management, highlighting the importance of enhanced preventive strategies and personalized care.

Associations between total, free and bioavailable 25-hydroxyvitamin D forms with adiponectin and irisin in maternal-neonatal pairs at birth from Greece

Background

Apart from the well-established skeletal effects, vitamin D has been explored as a secretagogue influencing various adipokines, including adiponectin and irisin. Recent evidence suggests that specific forms of 25-Hydroxyvitamin D (25(OHD), such as free and bioavailable 25(OH)D, may provide more accurate measurements of vitamin D status. The relationship between vitamin D status and serum irisin and adiponectin concentrations remains largely unexplored, particularly during pregnancy.

Methods

We analyzed data from 67 healthy maternal-neonatal pairs from Northern Greece at birth. Biochemical and hormonal tests were conducted on each maternal-neonatal pair. The vitamin D forms were estimated using validated mathematical models. Subsequently, regression analyses were conducted to determine the association between the vitamin D forms and adipokine levels.

Results

Bioavailable maternal 25(OH)D was inversely associated with neonatal irisin concentrations [β=-73.46 (-140.573 to -6.341), p=0.034]. No other associations were observed between maternal vitamin D status and neonatal adipokine concentrations.

Conclusion

In conclusion, maternal bioavailable vitamin D concentrations are inversely associated with neonatal serum irisin concentrations, warranting further studies to evaluate the underlying mechanisms for this finding.

Effects of Exercise-Induced Changes in Myokine Expression on the Tumor Microenvironment

In this narrative review, we summarize the direct and indirect effects that myokines have on the tumor microenvironment. We took studies of various cancer types and species into account. Systematic reviews and meta-analyses that matched the search terms were also considered. We searched databases for six months. As a narrative approach was chosen, no data was analyzed or reanalyzed. The goal of this narrative review is to create an overview on the topic to identify research gaps and answer the questions as to whether myokine expression may be relevant in cancer research in regard to the tumor microenvironment. Six commonly known myokines were chosen. We found strong links between the influence exercise has on interleukin-6, oncostatin M, secreted protein acidic and rich in cysteine, and irisin in the context of tumor progression and inhibition via interactions with the tumor microenvironment. It became clear that the effects of myokines on the tumor microenvironment can vary and contribute to disease progression or regression. Interactions among myokines and immune cells must also be considered and require further investigation. To date, no study has shown a clear connection, while multiple studies suggest further investigation of the topic, similar to the effects of exercise on myokine expression.

Treadmill exercise with nanoselenium supplementation affects the expression of Irisin/FNDC5 and semaphorin 3A in rats exposed to cigarette smoke extract

In the current study, we investigated the impacts of 6 weeks of aerobic interval training (AIT) with selenium nanoparticles (SeNPs) on muscle, serum, and lung irisin (FNDC5) and Sema3A in rats exposed to cigarette smoke extract (CSE). To this end, 49 male Wistar rats (8 weeks old) were divided into seven groups: control, SeNPs (2.5 mg/kg b.w by oral gavage, 3 days/week, 6 weeks), AIT (49 min/day, 5 days/week for 6 weeks, interval), SeNPs + AIT, CSE (150 µL by IP injection, 1 day/week for 6 weeks), CSE + AIT, and CSE + SeNPs + AIT. The CSE group showed a significant reduction in irisin and Sema3A serum levels, as well as a decrease in FNDC5 and Sema3A gene expression in lung tissue (p < 0.05). A combined treatment (AIT with SeNPs) significantly increased the serum level and the expression of muscle and lung irisin (FNDC5) and Sema3A in CSE received groups (p < 0.05). There was a positive and significant correlation between muscle FNDC5 and lung FNDC5 in the CSE + SeNPs + AIT group (r = 0.92, p = 0.025). In addition, there was a positive and significant correlation between serum Sema3A and lung Sema3A of CSE + SeNPs + AIT group (r = 0.97, p = 0.004). Seemingly, performing aerobic exercises with the antioxidant and anti-inflammatory supplement nano-selenium in the model of lung damage (similar to COPD) can boost myokine irisin and Sema3A, especially in serum and lung tissue. These results displayed the paracrine/endocrine regulatory function of these myokines on other tissues. In other words, these interventions emphasized the creation of crosstalk between skeletal muscles and damaged lung, focusing on its recovery; however, further research is needed.

Prevention of Alzheimer's disease through diet: An exploratory review

Introduction

This exploratory review article describes about the genetic factors behind Alzheimer's disease (AD), their association with foods, and their relationships with cognitive impairment. It explores the dietary patterns and economic challenges in AD prevention.

Methods

Scopus, PubMed and Google Scholar were searched for articles that examined the relationships between Diets, Alzheimer's Disease (AD), and Socioeconomic conditions in preventative Alzheimer's disease studies. Graphs and Network analysis data were taken from Scopus under the MeSH search method, including words, Alzheimer's, APoE4, Tau protein, APP, Amyloid precursor protein, Beta-Amyloid, Aβ, Mediterranean Diet, MD, DASH diet, MIND diet, SES, Socioeconomic, Developed country, Underdeveloped country, Preventions. The network analysis was done through VOS viewer.

Results

Mediterranean diet (MD) accurately lowers AD (Alzheimer's Disease) risk to 53% and 35% for people who follow it moderately. MIND scores had a statistically significant reduction in AD rate compared to those in the lowest tertial (53% and 35% reduction, respectively). Subjects with the highest adherence to the MD and DASH had a 54% and 39% lower risk of developing AD, respectively, compared to those in the lowest tertial. Omega-6, PUFA, found in nuts and fish, can play most roles in the clearance of Aβ. Vitamin D inhibits induced fibrillar Aβ apoptosis. However, the high cost of these diet components rise doubt about the effectiveness of AD prevention through healthy diets.

Conclusion

The finding of this study revealed an association between diet and the effects of the chemical components of foods on AD biomarkers. More research is required to see if nutrition is a risk or a protective factor for Alzheimer's disease to encourage research to be translated into therapeutic practice and to clarify nutritional advice.

LRP10, PGK1 and RPLP0: Best Reference Genes in Periprostatic Adipose Tissue under Obesity and Prostate Cancer Conditions

Obesity (OB) is a metabolic disorder characterized by adipose tissue dysfunction that has emerged as a health problem of epidemic proportions in recent decades. OB is associated with multiple comorbidities, including some types of cancers. Specifically, prostate cancer (PCa) has been postulated as one of the tumors that could have a causal relationship with OB. Particularly, a specialized adipose tissue (AT) depot known as periprostatic adipose tissue (PPAT) has gained increasing attention over the last few years as it could be a key player in the pathophysiological interaction between PCa and OB. However, to date, no studies have defined the most appropriate internal reference genes (IRGs) to be used in gene expression studies in this AT depot. In this work, two independent cohorts of PPAT samples (n = 20/n = 48) were used to assess the validity of a battery of 15 literature-selected IRGs using two widely used techniques (reverse transcription quantitative PCR [RT-qPCR] and microfluidic-based qPCR array). For this purpose, ΔCt method, GeNorm (v3.5), BestKeeper (v1.0), NormFinder (v.20.0), and RefFinder software were employed to assess the overall trends of our analyses. LRP10, PGK1, and RPLP0 were identified as the best IRGs to be used for gene expression studies in human PPATs, specifically when considering PCa and OB conditions.

Recent Advances in Nutraceuticals for the Treatment of Sarcopenic Obesity

Sarcopenic obesity, low muscle mass, and high body fat are growing health concerns in the aging population. This review highlights the need for standardized criteria and explores nutraceuticals as potential therapeutic agents. Sarcopenic obesity is associated with insulin resistance, inflammation, hormonal changes, and reduced physical activity. These factors lead to impaired muscle activity, intramuscular fat accumulation, and reduced protein synthesis, resulting in muscle catabolism and increased fat mass. Myostatin and irisin are myokines that regulate muscle synthesis and energy expenditure, respectively. Nutritional supplementation with vitamin D and calcium is recommended for increasing muscle mass and reducing body fat content. Testosterone therapy decreases fat mass and improves muscle strength. Vitamin K, specifically menaquinone-4 (MK-4), improves mitochondrial function and reduces muscle damage. Irisin is a hormone secreted during exercise that enhances oxidative metabolism, prevents insulin resistance and obesity, and improves bone quality. Low-glycemic-index diets and green cardamom are potential methods for managing sarcopenic obesity. In conclusion, along with exercise and dietary support, nutraceuticals, such as vitamin D, calcium, vitamin K, and natural agonists of irisin or testosterone, can serve as promising future therapeutic alternatives.

Irisin: An anti-inflammatory exerkine in aging and redox-mediated comorbidities

Human beings lead largely sedentary lives. From an evolutionary perspective, such lifestyle is not beneficial to health. Exercise can promote many enabling pathways, particularly through circulating exerkines, to optimize individual health and quality of life. Such benefits might explain the protective effects of exercise against aging and noncommunicable diseases. Nevertheless, the miRNA-mediated molecular mechanisms and exerkine interorgan crosstalk that underlie the beneficial effects of exercise remain poorly understood. In this mini review, we focused on the exerkine, irisin, mainly produced by muscle contraction during adaptation to exercise and its beneficial effects on body homeostasis. Herein, the complex role of irisin in metabolism and inflammation is described, including its subsequent effects on thermogenesis through browning to control obesity and improve glycemic regulation for diabetes mellitus control, its potential to improve cognitive function (via brain derived neurotrophic factor), and its pathways of action and role in aging.

Physical Activity as the Best Supportive Care in Cancer: The Clinician's and the Researcher's Perspectives

Multidisciplinary supportive care, integrating the dimensions of exercise alongside oncological treatments, is now regarded as a new paradigm to improve patient survival and quality of life. Its impact is important on the factors that control tumor development, such as the immune system, inflammation, tissue perfusion, hypoxia, insulin resistance, metabolism, glucocorticoid levels, and cachexia. An increasing amount of research has been published in the last years on the effects of physical activity within the framework of oncology, marking the appearance of a new medical field, commonly known as "exercise oncology". This emerging research field is trying to determine the biological mechanisms by which, aerobic exercise affects the incidence of cancer, the progression and/or the appearance of metastases. We propose an overview of the current state of the art physical exercise interventions in the management of cancer patients, including a pragmatic perspective with tips for routine practice. We then develop the emerging mechanistic views about physical exercise and their potential clinical applications. Moving toward a more personalized, integrated, patient-centered, and multidisciplinary management, by trying to understand the different interactions between the cancer and the host, as well as the impact of the disease and the treatments on the different organs, this seems to be the most promising method to improve the care of cancer patients.

Aerobic Versus Resistance Training: Leptin and Metabolic Parameters Improvement in Type 2 Diabetes Obese Men

Purpose: The purpose of the research was to determine the changes in metabolic parameters, leptin, and irisin levels after aerobic and resistance training in type-2 diabetes obese men. Methods: Forty-five participants in the age range of 17-25 years were randomized into three groups: aerobic training (AT), resistance training (RT), and control (CO). All training sessions were fulfilled 4 days per week for two months. The aerobic training began with intensity of 65% of the maximum aerobic power and finished with 90%. The resistance program started with 50% of one-repetition maximum and reached 70% in the 8th week. Results: Factorial analysis of variance and Bonferroni post-hoc test revealed significant decreases in leptin (p = .043), fasting blood sugar (FBS) (p = .023), insulin (p = .001), homeostasis model assessment for insulin resistance (HOMA-IR) (p = .022) in AT compared with CO and insulin (p = .006) in AT compared with RT. The change of percent body fat (PBF) was positively correlated only with change of HOMA-IR in AT group (p = .032) at p < .05. Conclusion: The result suggests that, compared to resistance training, aerobic training can control metabolic situations such as insulin resistance through the leptin hormone function, and not irisin in type-2 diabetes obese men.

Muscle-to-tumor crosstalk: The effect of exercise-induced myokine on cancer progression

Physical exercise has gradually become a focus in cancer treatment due to its pronounced role in reducing cancer risk, enhancing therapeutic efficacy, and improving prognosis. In recent decades, skeletal muscles have been considered endocrine organs, exerting their biological functions via the endocrine, autocrine, and paracrine systems by secreting various types of myokines. The amount of myokines secreted varies depending on the intensity, type, and duration of exercise. Recent studies have shown that muscle-derived myokines are highly involved the effects of exercise on cancer. Multiple myokines, such as interleukin-6 (IL-6), oncostatin M (OSM), secreted protein acidic and rich in cysteine (SPARC), and irisin, directly mediate cancer progression by influencing the proliferation, apoptosis, stemness, drug resistance, metabolic reprogramming, and epithelial-mesenchymal transformation (EMT) of cancer cells. In addition, IL-6, interleukin-8 (IL-8), interleukin-15 (IL-15), brain-derived neurotrophic factor (BDNF), and irisin can improve obesity-induced inflammation by stimulating lipolysis of adipose tissues, promoting glucose uptake, and accelerating the browning of white fat. Furthermore, some myokines could regulate the tumor microenvironment, such as angiogenesis and the immune microenvironment. Cancer cachexia occurs in up to 80% of cancer patients and is responsible for 22%-30% of patient deaths. It is characterized by systemic inflammation and decreased muscle mass. Exercise-induced myokine production is important in regulating cancer cachexia. This review summarizes the roles and underlying mechanisms of myokines, such as IL-6, myostatin, IL-15, irisin, fibroblast growth factor 21 (FGF21) and musclin, in cancer cachexia. Through comprehensive analysis, we conclude that myokines are potential targets for inhibiting cancer progression and the associated cachexia.

Physical Exercise Restrains Cancer Progression through Muscle-Derived Factors

Simple Summary

The benefits of physical exercise against cancer onset and progression, as well as the adverse effects of physical inactivity have changed the way that we utilize exercise for cancer patients. Nevertheless, although guidelines of various scientific societies and organizations propose exercise as a complementary intervention during cancer therapies, the exact cellular and molecular mechanisms by which exercise acts against cancer have not yet been elucidated. In the present review, we analyze the factors which either are secreted from skeletal muscle or are regulated by exercise and can restrain cancer evolution. We also describe the exercise-induced factors that counteract severe side effects of cancer treatment, as well as the ways that muscle-derived factors are delivered to the target cells.

Abstract

A growing body of in vitro and in vivo studies suggests that physical activity offers important benefits against cancer, in terms of both prevention and treatment. However, the exact mechanisms implicated in the anticancer effects of exercise remain to be further elucidated. Muscle-secreted factors in response to contraction have been proposed to mediate the physical exercise-induced beneficial effects and be responsible for the inter-tissue communications. Specifically, myokines and microRNAs (miRNAs) constitute the most studied components of the skeletal muscle secretome that appear to affect the malignancy, either directly by possessing antioncogenic properties, or indirectly by mobilizing the antitumor immune responses. Moreover, some of these factors are capable of mitigating serious, disease-associated adverse effects that deteriorate patients’ quality of life and prognosis. The present review summarizes the myokines and miRNAs that may have potent anticancer properties and the expression of which is induced by physical exercise, while the mechanisms of secretion and intercellular transportation of these factors are also discussed.

Myokines and Resistance Training: A Narrative Review

In the last few years, the muscular system has gained attention due to the discovery of the muscle-secretome and its high potency for retaining or regaining health. These cytokines, described as myokines, released by the working muscle, are involved in anti-inflammatory, metabolic and immunological processes. These are able to influence human health in a positive way and are a target of research in metabolic diseases, cancer, neurological diseases, and other non-communicable diseases. Therefore, different types of exercise training were investigated in the last few years to find associations between exercise, myokines and their effects on human health. Particularly, resistance training turned out to be a powerful stimulus to enhance myokine release. As there are different types of resistance training, different myokines are stimulated, depending on the mode of training. This narrative review gives an overview about resistance training and how it can be utilized to stimulate myokine production in order to gain a certain health effect. Finally, the question of why resistance training is an important key regulator in human health will be discussed.

FNDC5/Irisin: Physiology and Pathophysiology

A sedentary lifestyle or lack of physical activity increases the risk of different diseases, including obesity, diabetes, heart diseases, certain types of cancers, and some neurological diseases. Physical exercise helps improve quality of life and reduces the risk of many diseases. Irisin, a hormone induced by exercise, is a fragmented product of FNDC5 (a cell membrane protein) and acts as a linkage between muscles and other tissues. Over the past decade, it has become clear that irisin is a molecular mimic of exercise and shows various beneficial effects, such as browning of adipocytes, modulation of metabolic processes, regulation of bone metabolism, and functioning of the nervous system. Irisin has a role in carcinogenesis; numerous studies have shown its impact on migration, invasion, and proliferation of cancer cells. The receptor of irisin is not completely known; however, in some tissues it probably acts via a specific class of integrin receptors. Here, we review research from the past decade that has identified irisin as a potential therapeutic agent in the prevention or treatment of various metabolic-related and other diseases. This article delineates structural and biochemical aspects of irisin and provides an insight into the role of irisin in different pathological conditions.

The role of a recently discovered peptide—irisin—in physiological and pathological processes

Irisin, a cleaved fragment of fibronectin type III domain-containing protein 5 (FNDC5), was originally described as a factor stimulating browning of white adipose tissue, produced during physical exercise by skeletal muscles. However, irisin is not only a new and promising biomarker of metabolism; its expression has been found in a wide variety of tissues and organs such as the peripheral nerves, stomach, pancreas, and skin, and recent data also indicate its role in cancer. Numerous studies focus on the protective role of this protein, which could become an important factor in predicting disease risk, disease prognosis, or possible metastases in cancer patients. Possible use of irisin in therapy is also worth considering. The aim of this paper is to systematize knowledge on the role of irisin in patients and to draw attention to its role in skin diseases including acne vulgaris, psoriasis vulgaris, and hidradenitis suppurativa.

Serum irisin is a novel biomarker for bladder cancer detection

BACKGROUND

This study intended to investigate irisin levels in bladder cancer patients and healthy controls.

OBJECTIVE

Our aim was to evaluate if serum irisin could be used as a diagnostic tool in bladder cancer and further, if it could differentiate muscle-invasive and non-muscle-invasive bladder cancer patients.

METHODS

In this study, 90 primary bladder cancer patients in addition to 30 age-matched healthy individuals for the control group were prospectively included. Bladder cancer patients were divided into two subgroups as non-muscle-invasive (60 patients) and muscle-invasive (30 patients). Blood samples were obtained before the diagnosis of the disease. Serum irisin levels were measured using ELISA. Demographic data as well as tumor grade and stage were noted.

RESULTS

Mean serum irisin level was significantly lower in the bladder cancer patients compared to the control group (4.53 ± 2.55 vs. 16.5 ± 5.67, p < 0.001). Also, serum irisin level was statistically lower in the muscle-invasive bladder cancer group compared to the non-muscle-invasive counterparts (3.19 ± 1.47 vs. 5.18 ± 2.73, p < 0.001). Serum irisin could differentiate bladder cancer patients from healthy individuals with a sensitivity of 86.2% and a specificity of 89.7% at a cut-off value of 8.689 (AUC = 0.859). Moreover, to discriminate between NMIBC and MIBC, the sensitivity was 75% and the specificity was 73.7% at a cut-off value of 3.97 (AUC = 0.732).

CONCLUSION

Our results showed that serum irisin levels can be used for the diagnosis of bladder cancer. Also, it can help distinguish high-grade and stage tumor.

Irisin Is Correlated with Blood Pressure in Obstructive Sleep Apnea Patients

BACKGROUND

Despite approximately 95% primary cases of hypertension, secondary hypertension seems to be common with resistant forms. Notably, obstructive sleep apnea (OSA) is known as a common cause of secondary hypertension and has a major characteristic of obesity. Irisin acts as a link between muscles and adipose tissues in obesity, playing an essential role in human blood pressure (BP) regulation. However, whether irisin is associated with secondary hypertension caused by OSA and how it takes effect essentially have not been elucidated.

PURPOSE

To investigate the changes of irisin and its relationship with BP in OSA.

METHODS

72 snoring patients finished Epworth Sleep Scale (ESS) evaluation before polysomnography (PSG). BP was the average of three brachial BP values by mercury sphygmomanometer. Serum irisin level was determined by enzyme-linked immunosorbent assay (ELISA). Results were analyzed by SPSS software.

RESULTS

Irisin was higher in the severe and quite severe group than that in control and nonsevere groups (p < 0.05). For BP, significant differences were found between the control group and the other three groups (p < 0.05) and between the quite severe and the other three groups (p ≤ 0.001). Positive correlations were found between irisin and apnea-hypopnea index (AHI), AHI and BP, and irisin level and BP. Negative correlations were between irisin and SpO2 nadir and SpO2 nadir and BP. Positive correlation still existed between AHI and irisin even after adjusting for some obesity-related variables.

CONCLUSIONS

Irisin may serve as a potential biomarker for severity of OSA independently of obesity and imply the development of hypertension.

Cardiorespiratory Fitness and Muscular Strength Moderates the Relationship between FNDC5 Polymorphism and Adiposity in Children and Adolescents

The human locus FNDC5 rs16835198 contributes positively to anthropometric phenotypes in children and adolescents. However, the role of specific components of physical fitness in this relationship is not known. The present study aimed to verify the moderator role of cardiorespiratory fitness (CRF) and muscular strength in the relationship between rs16835198 polymorphism FNDC5 and adiposity in children and adolescents. This cross-sectional study was carried out by genotyping the rs16835198 FNDC5 polymorphism in 1701 children and adolescents (mean age 11.73 ± 2.75 years). Obesity was assessed using waist circumference and body mass index (BMI) z-scores. To evaluate CRF and muscular strength, the 6 min run/walk test and lower limb strength (LLS) were used. Linear regression models were applied, and all analyses were adjusted for age, sex, skin color, living area, and school type. A significant interaction term for CRF (p = 0.038) and LLS (p = 0.040) × rs16835198 FNDC5 with WC was identified. Regarding BMI, a significant interaction term for CRF (p = 0.007) and LLS (p = 0.044) × rs16835198 FNDC5 was observed. Moreover, medium and high CRF and LLS levels protected against higher WC and BMI. In conclusion, adiposity levels of children and adolescents with a genetic predisposition to obesity might be modified by improving CRF and muscular strength.

Irisin serum increasing pattern is higher at moderate-intensity continuous exercise than at moderate-intensity interval exercise in obese females

Lifestyle, unhealthy eating patterns, and low physical activity become trigger factors of obesity. Therefore, lifestyle modification with an exercise-based nonpharmacological approach is one of the strategies for combat obesity. This study aims to analyse the response of moderate-intensity interval and continuous exercise to irisin level increasing pattern on the obese female. A total of 21 obese females were enrolled in this study and given moderate-intensity interval exercise (MIIE) and moderate-intensity continuous exercise (MICE). ELISA was used to quantify the serum level of irisin in all samples. Statistical analysis was performed using one way-ANOVA and Tukey’s honestly significant difference (HSD) post hoc test. Mean irisin levels of pre-exercise at control (CON), MIIE, and MICE were 3.26±1.28l, 3.44±0.56 and 3.89±1.08 ng/ml, respectively (P=0.519). The mean irisin level of 10 min post-exercise was 2.99±0.86 ng/ml at CON, 4.82±1.01 ng/ml at MIIE, and 5.99±1.27 ng/ml at MICE (P=0.000). The mean irisin levels of 6 h post-exercise were 3.04±0.60, 4.56±0.87, and 5.73±1.02 ng/ml at CON, MIIE, and MICE, respectively (P=0.000). The mean irisin level of 24 h post-exercise was 3.04±0.91 ng/ml at CON, 4.64±0.69 ng/ml at MIIE, and 5.69±1.53 ng/ml at MICE (P=0.002). We conclude that the post-exercise serum irisin level increased in both MICE and MIIE subjects, and the post-exercise serum irisin level maintained higher in the MICE than in the MIIE in the obese female subjects.

The role of senolytics in osteoporosis and other skeletal pathologies

The skeletal system undergoes irreversible structural deterioration with aging, leading to increased fracture risk and detrimental changes in mobility, posture, and gait. This state of low bone mass and microarchitectural changes, diagnosed as osteoporosis, affects millions of individuals worldwide and has high clinical and economic burdens. Recently, pre-clinical studies have linked the onset of age-related bone loss with an accumulation of senescent cells in the bone microenvironment. These senescent cells appear to be causal to age-related bone loss, as targeted clearance of these cells leads to improved bone mass and microarchitecture in old mice. Additionally, other pathologies leading to bone loss that result from DNA damage, such as cancer treatments, have shown improvements after clearance of senescent cells. The development of new therapies that clear senescent cells, termed "senolytics", is currently underway and may allow for the modulation of bone loss that results from states of high senescent cell burden, such as aging.

Obesity and Thyroid Axis

Development of obesity is primarily the result of imbalance between energy intake and energy expenditure. Thyroid hormones influence energy expenditure by regulating cellular respiration and thermogenesis and by determining resting metabolic rate. Triiodothyronine influences lipid turnover in adipocytes and impacts appetite regulation through the central nervous system, mainly the hypothalamus. Thyroid-stimulating hormone may also influence thermogenesis, suppress appetite and regulate lipid storage through lipolysis and lipogenesis control. Subclinical hypothyroidism may induce changes in basal metabolic rate with subsequent increase in BMI, but obesity can also affect thyroid function via several mechanisms such as lipotoxicity and changes in adipokines and inflammatory cytokine secretion. The present study investigated the complex and mutual relationships between the thyroid axis and adiposity.

Assessment of cancer prevention effect of exercise

There are many documents about benefits of exercise on human health. However, evidences indicate to positive effect of exercise on disease prevention, understanding of many aspects of this mechanism need more investigations. Determination of critical genes which effect human health.GSE156249 including 12 gene expression profiles of healthy individual biopsy from vastus lateralis muscle before and after 12-week combined exercise training intervention were extracted from gene expression omnibus (GEO) database. The significant DEGs were included in interactome unit by Cytoscape software and STRING database. The network was analyzed to find the central nodes subnetwork clusters. The nodes of prominent cluster were assessed via gene ontology by using ClueGO. Number of 8 significant DEGs and 100 first neighbors analyzed via network analysis. The network includes 2 clusters and COL3A1, BGN, and LOX were determined as central DEGs. The critical DEGs were involved in cancer prevention process.

Progress and Challenges in the Biology of FNDC5 and Irisin

In 2002, a transmembrane protein-now known as FNDC5-was discovered and shown to be expressed in skeletal muscle, heart, and brain. It was virtually ignored for 10 years, until a study in 2012 proposed that, in response to exercise, the ectodomain of skeletal muscle FNDC5 was cleaved, traveled to white adipose tissue, and induced browning. The wasted energy of this browning raised the possibility that this myokine, named irisin, might mediate some beneficial effects of exercise. Since then, more than 1000 papers have been published exploring the roles of irisin. A major interest has been on adipose tissue and metabolism, following up the major proposal from 2012. Many studies correlating plasma irisin levels with physiological conditions have been questioned for using flawed assays for irisin concentration. However, experiments altering irisin levels by injecting recombinant irisin or by gene knockout are more promising. Recent discoveries have suggested potential roles of irisin in bone remodeling and in the brain, with effects potentially related to Alzheimer's disease. We discuss some discrepancies between research groups and the mechanisms that are yet to be determined. Some important questions raised in the initial discovery of irisin, such as the role of the mutant start codon of human FNDC5 and the mechanism of ectodomain cleavage, remain to be answered. Apart from these specific questions, a promising new tool has been developed-mice with a global or tissue-specific knockout of FNDC5. In this review, we critically examine the current knowledge and delineate potential solutions to resolve existing ambiguities.

Current Evidence of the Role of the Myokine Irisin in Cancer

Simple Summary

Regular exercise/physical activity is beneficial for the health of an individual and lowers the risk of getting different diseases, including cancer. How exactly exercise results in these health benefits is not known. Recent studies suggest that the molecule irisin released by muscles into the blood stream after exercise may be responsible for these effects. This review summarizes all the available in vitro/cell culture, animal and human studies that have investigated the relationship between cancer and irisin with the aim to shed light and understand the possible role of irisin in cancer. The majority of the in vitro studies indicate anticancer properties of irisin, but more animal and human studies are required to better understand the exact role of irisin in cancer.

Abstract

Cancer is a disease associated with extreme human suffering, a huge economic cost to health systems, and is the second leading cause of death worldwide. Regular physical activity is associated with many health benefits, including reduced cancer risk. In the past two decades, exercising/contracting skeletal muscles have been found to secrete a wide range of biologically active proteins, named myokines. Myokines are delivered, via the circulation, to different cells/tissues, bind to their specific receptors and initiate signaling cascades mediating the health benefits of exercise. The present review summarizes the existing evidence of the role of the myokine irisin in cancer. In vitro studies have shown that the treatment of various cancer cells with irisin resulted in the inhibition of cell proliferation, survival, migration/ invasion and induced apoptosis by affecting key proliferative and antiapoptotic signaling pathways. However, the effects of irisin in humans remains unclear. Although the majority of the existing studies have found reduced serum irisin levels in cancer patients, a few studies have shown the opposite. Similarly, the majority of studies have found increased levels of irisin in cancer tissues, with a few studies showing the opposite trend. Clearly, further investigations are required to determine the exact role of irisin in cancer.

ANGPTL3 Variants Associate with Lower Levels of Irisin and C-Peptide in a Cohort of Arab Individuals

ANGPTL3 is an important regulator of lipid metabolism. Its inhibition in people with hypercholesteremia reduces plasma lipid levels dramatically. Genome-wide association studies have associated ANGPTL3 variants with lipid traits. Irisin, an exercise-modulated protein, has been associated with lipid metabolism. Intracellular accumulation of lipids impairs insulin action and contributes to metabolic disorders. In this study, we evaluate the impact of ANGPTL3 variants on levels of irisin and markers associated with lipid metabolism and insulin resistance. ANGPTL3 rs1748197 and rs12130333 variants were genotyped in a cohort of 278 Arab individuals from Kuwait. Levels of irisin and other metabolic markers were measured by ELISA. Significance of association signals was assessed using Bonferroni-corrected p-values and empirical p-values. The study variants were significantly associated with low levels of c-peptide and irisin. Levels of c-peptide and irisin were mediated by interaction between carrier genotypes (GA + AA) at rs1748197 and measures of IL13 and TG, respectively. While levels of c-peptide and IL13 were directly correlated in individuals with the reference genotype, they were inversely correlated in individuals with the carrier genotype. Irisin correlated positively with TG and was strong in individuals with carrier genotypes. These observations illustrate ANGPTL3 as a potential link connecting lipid metabolism, insulin resistance and cardioprotection.

Serum Levels of Irisin and Omentin-1 in Breast Neoplasms and Their Association with Tumor Histology

Breast cancer is associated with obesity, possibly due to direct effects of adipokines and myokines, such as omentin-1 and irisin. In this study, we aimed to evaluate omentin-1 and irisin levels in women with benign and/or malignant breast neoplasms vs. healthy controls. Disease-free individuals (N = 56) and patients with histologically proven benign (N = 61) or malignant tumor (N = 96; subdivided into recently diagnosed/treatment-naïve (N = 72) and chemotherapy-treated (N = 24) subgroups) were enrolled in this study. Demographic, biochemical, and tumor histological characteristics were recorded. Body composition parameters were assessed using bioelectrical impedance. Serum irisin and omentin-1 levels were quantified with ELISA kits. In adjusted models, irisin levels were higher in both benign and malignant cases compared to controls but were comparable between neoplasms. Further adjustment for omentin-1 levels showed that age (odds ratio (OR) = 1.05, 95% confidence interval (95% CI) = (1.02, 1.08), p < 0.01) and irisin levels (OR = 5.30, 95% CI = (1.24, 22.38), p=0.03) were independent predictors of the presence of malignancy. These molecules were associated with each other and with other anthropometric and demographic parameters. Irisin was associated with tumor histological characteristics including Ki67% levels, Elston-Ellis grading system, and estrogen receptors status. Omentin-1 was also associated with the Elston-Ellis grading system. In conclusion, serum irisin is increased in patients with both benign and malignant diseases of the breast. When combined with omentin-1, irisin concentration was associated with the presence of breast malignancy. This molecule's role as a potential diagnostic and/or prognostic agent in breast malignancies warrants further investigation in larger prospective studies.

Exercise-Induced Myokines can Explain the Importance of Physical Activity in the Elderly: An Overview

Physical activity has been found to aid the maintenance of health in the elderly. Exercise-induced skeletal muscle contractions lead to the production and secretion of many small proteins and proteoglycan peptides called myokines. Thus, studies on myokines are necessary for ensuring the maintenance of skeletal muscle health in the elderly. This review summarizes 13 myokines regulated by physical activity that are affected by aging and aims to understand their potential roles in metabolic diseases. We categorized myokines into two groups based on regulation by aerobic and anaerobic exercise. With aging, the secretion of apelin, β-aminoisobutyric acid (BAIBA), bone morphogenetic protein 7 (BMP-7), decorin, insulin-like growth factor 1 (IGF-1), interleukin-15 (IL-15), irisin, stromal cell-derived factor 1 (SDF-1), sestrin, secreted protein acidic rich in cysteine (SPARC), and vascular endothelial growth factor A (VEGF-A) decreased, while that of IL-6 and myostatin increased. Aerobic exercise upregulates apelin, BAIBA, IL-15, IL-6, irisin, SDF-1, sestrin, SPARC, and VEGF-A expression, while anaerobic exercise upregulates BMP-7, decorin, IGF-1, IL-15, IL-6, irisin, and VEGF-A expression. Myostatin is downregulated by both aerobic and anaerobic exercise. This review provides a rationale for developing exercise programs or interventions that maintain a balance between aerobic and anaerobic exercise in the elderly.

Identification of irisin as a therapeutic agent that inhibits oxidative stress and fibrosis in a murine model of chronic pancreatitis

BACKGROUND

Abnormal activation of pancreatic stellate cells (PSCs) plays a crucial role in the pathogenesis of chronic pancreatitis (CP). Irisin, an exercise-induced hormone, has been shown to mitigate liver fibrosis by inhibiting the activation of hepatic stellate cells. However, the effect of irisin in CP has not been evaluated.

METHODS

This study aimed to determine whether irisin is protective in CP. CP was induced by 6 IP injections of cerulein (50 μg/kg/body weight). HPSCs were treated with 5 ng/ml TGF-β1 as in vitro experiment.

RESULTS

Our results showed that repeated cerulein injection induced severe pancreatic injury and fibrosis in mice and the serum irisin level in cerulein-treated mice decreased as in CP patients. Excessive oxidative and ER stress was also present in the pancreas of cerulein-treated mice. Irisin treatment significantly alleviated pancreatic injury and fibrosis, which was associated with reduced oxidative and ER stress. In cultured PSCs, irisin directly inhibited TGF-β-induced α-SMA and collagen I expression. This effect appears to be mediated through downregulation of kindlin-2 and inhibition of the SMAD2/3 pathway.

CONCLUSIONS

Irisin alleviated pancreatic injury and fibrosis, which was associated with reduced oxidative and ER stress. Thus, irisin may offer therapeutic potential for patients with CP.

New insights into the cellular activities of Fndc5/Irisin and its signaling pathways

Fndc5, a well-defined myokine and also identified as an adipokine, has a critical role in modulation of metabolism and protection against obesity. These important functions are mediated by irisin, a secretory peptide produced from proteolytic processing of Fndc5. The other beneficial physiological effects of irisin are alleviation of oxidative stress, neuroprotective effects, and anti-inflammatory properties and associated anti-metastatic effects. Fndc5/irisin exerts its biological effects through several intracellular signaling pathways. The major signaling pathway is thought to be MAPK signaling pathways which are involved in neural differentiation, browning of white adipocytes, as well as osteoblast proliferation and differentiation. Other essential functions of Fndc5/irisin are mediated through additional pathways including AMPK pathway, PI3K/AKT, and STAT3/Snail. Thorough understanding of the mechanisms of irisin actions are essential in order to develop Fndc5/irisin for therapeutic purposes. In the present review, we focus on the current knowledge of the signaling pathways that elicit irisin actions.

Effect of ursodeoxycholic acid therapy due to pregnant intrahepatic cholestasis on chemerin and irisin levels

The purpose of the work was to assess changes in chemerin and irisin levels in women with diagnosed intrahepatic cholestasis of pregnant women treated with ursodeoxycholic acid. The study group consisted of 50 patients with diagnosed and confirmed intrahepatic cholestasis of pregnant women at 24-25 weeks of pregnancy treatment by ursodeoxycholic acid (UDCA). The study also included a group of 40 pregnant women, without concomitant intrahepatic cholestasis of pregnancy (ICP). In the pregnant ICP group, whole blood was collected 4 times: before the first dose of drug, 4 and 8 weeks after the first dose, and day after delivery. It was observed that statistically significant differences in the concentration of irisine occur between the time before starting treatment and the 8-week therapy and 1 day after delivery. The Pearson correlation analysis (r's) showed two statistically significant relationships (p < .05). The first of these can be found between the concentration of irisine and chemerin in the group of nonpregnant women and the second in the group of patients with intrahepatic pregnant cholestasis before the first dose of UDCA. A significant relationship between irisin and chemerin concentrations was confirmed in the group of pregnant ICP patients during UDCA acid therapy and among healthy pregnant women.

Updated concept of sarcopenia based on muscle-bone relationship

Sarcopenia is an age-related loss of skeletal muscle mass and strength. It has been widely recognized that low muscle mass was essential in the diagnosis of sarcopenia, whereas recent studies have emphasized the importance of muscle strength. In practice, muscle quality as well as muscle mass might determine the strength and physical performance. A new diagnostic algorithm of sarcopenia has recently been established, in which low muscle strength is a key characteristic factor for the diagnosis of sarcopenia. Although many factors are supposed to be involved in the pathology and development of sarcopenia, precise mechanisms remain to be elucidated. Recent studies have also focused on the crosstalk between muscles and bones, including functional involvement of myokines and osteokines.

The diagnostic and prognostic roles of serum irisin in bladder cancer

BACKGROUND

Egypt is among the countries with the highest incidence of bladder cancer (BC). Adipokines involved in BC development. This study aimed to examine the diagnostic and prognostic roles of irisin in BC through its function as an adipokine.

PATIENTS AND METHODS

This study included 150 subjects; 75 patients newly diagnosed as BC and 75 apparently healthy subjects. Serum irisin levels were quantified by enzyme-linked immunosorbent assay.

RESULTS

Serum irisin levels exhibited significantly lower levels in BC patients compared to controls (1.07 [0.51-1.96] and 1.8 [0.5-2.44] µg/mL), respectively (P < 0.001). Serum irisin was positively correlated with BMI (r = 0.386, P = 0.001) and negatively correlated with serum cholesterol (r = -0.58, P < 0.0001). Irisin had 74.7% sensitivity and 90.7% specificity at a cutoff point of ≤1.2 µg/mL. Serum irisin levels reduction can predict the BC stages, when adjusted for BMI and serum cholesterol level, serum irisin had an adjusted odds ratio of 14 (P = 0.001). Low serum irisin patients had a higher mortality rate when compared to those with high levels (38.2% vs 5%).

CONCLUSION

BC patients had significantly lower levels of serum irisin. Serum irisin showed acceptable performance criteria in BC diagnosis. It had a limited role in BC grading but showed a decreasing trend in different BC stages. Serum irisin seems to be an excellent diagnostic and prognostic marker for BC.

The Impact of the Adipose Organ Plasticity on Inflammation and Cancer Progression

Obesity is characterized by chronic and low-grade systemic inflammation, an increase of adipose tissue, hypertrophy, and hyperplasia of adipocytes. Adipose tissues can be classified into white, brown, beige and pink adipose tissues, which display different regulatory, morphological and functional characteristics of their adipocyte and immune cells. Brown and white adipocytes can play a key role not only in the control of energy homeostasis, or through the balance between energy storage and expenditure, but also by the modulation of immune and inflammatory responses. Therefore, brown and white adipocytes can orchestrate important immunological crosstalk that may deeply impact the tumor microenvironment and be crucial for cancer establishment and progression. Recent works have indicated that white adipose tissues can undergo a process called browning, in which an inducible brown adipocyte develops. In this review, we depict the mechanisms involved in the differential role of brown, white and pink adipocytes, highlighting their structural, morphological, regulatory and functional characteristics and correlation with cancer predisposition, establishment, and progression. We also discuss the impact of the increased adiposity in the inflammatory and immunological modulation. Moreover, we focused on the plasticity of adipocytes, describing the molecules produced and secreted by those cells, the modulation of the signaling pathways involved in the browning phenomena of white adipose tissue and its impact on inflammation and cancer.