Irisin, physical activity and fitness status in healthy humans: No association under resting conditions in a cross-sectional study

Fibronectin type III domain-containing protein 5 (FNDC5)-like immunoreactivity and mRNA abundance in domestic animal tissues

Irisin is a 112-amino acid peptide hormone that is cleaved from fibronectin type III domain-containing protein 5 (FNDC5), a type I transmembrane protein abundantly found in muscle tissue. Irisin is a putative mediator of the benefits of exercise, neuroprotection, bone growth, and cardiac health. However, few studies have focused on irisin in domestic animals. Further, whether processed irisin is detectable in domestic animal tissues remains uncertain. To address this, we determined FNDC5 mRNA and protein concentration in anatine (duck) and porcine (pig) skeletal muscle, and in equine (horse), swine, and anatine serum samples. RT-PCR analysis identified FNDC5 mRNA in all pig and duck skeletal muscle samples. An approximately 25 kDa band representing FNDC5 was detected in both pig and duck skeletal muscle. Fluorescence immunohistochemistry using a rabbit monoclonal FNDC5/irisin primary antibody and a goat polyclonal anti-rabbit secondary antibody localized FNDC5/irisin-like immunoreactivity in both the glandular and muscular regions of pig stomach. FNDC5/irisin-like immunoreactivity was also identified in horse, pig, and duck serum using a multispecies irisin ELISA. The average values of irisin-like immunoreactivity were 13.7 (duck), 15.4 (horse), and 7.0 (pig) ng/mL in samples tested. Our results support the presence of irisin precursor in several domestic animals. Processed irisin, however, was not detectable. Further studies are required to validate reliable tools to detect and quantify processed irisin in domestic animals.

Irisin in domestic animals

Irisin is a 112 amino acid peptide hormone cleaved from the fibronectin type III domain-containing protein. Irisin is highly conserved across vertebrates, suggesting evolutionarily conserved common functions among domestic animals. These functions include the browning of white adipose tissue and increased energy expenditure. Irisin has been detected and studied primarily in plasma, serum, and skeletal muscle, but has also been found in adipose tissue, liver, kidney, lungs, cerebrospinal fluid, breast milk, and saliva. This wider tissue presence of irisin suggests additional functions beyond its role as a myokine in regulating energy use. We are beginning to understand irisin in domestic animals. The goal of this review is to provide an up-to-date commentary on irisin structure, tissue distribution, and functions across vertebrates, especially mammals of importance in veterinary medicine. Irisin could be explored as a potential candidate for developing therapeutic agents and biomarkers in domestic animal endocrinology.

Associations of Circulating Irisin and Fibroblast Growth Factor-21 Levels with Measures of Energy Homeostasis in Highly Trained Adolescent Rhythmic Gymnasts

The aim of this investigation was to determine the associations of serum irisin and fibroblast growth factor-21 (FGF-21) with the measures of energy homeostasis, training stress and other energy homeostasis hormones in highly trained adolescent rhythmic gymnasts (RG). Thirty-three RG and 20 untrained controls (UC) aged 14−18 years participated in this study. Body composition, resting energy expenditure (REE), peak oxygen consumption, and different energy homeostasis hormones in serum, including irisin, FGF-21, leptin, and resistin, were measured. Irisin and FGF-21 were not significantly different (p > 0.05) between RG and UC groups. In RG, serum irisin was positively associated with REE (r = 0.40; p = 0.021) and leptin (r = 0.60; p = 0.013), while serum FGF-21 was related to body fat mass (r = 0.46; p = 0.007) and leptin (r = 0.45; p = 0.009). Irisin was related to FGF-21, independent of age, body fat, and lean masses (r = 0.36; p = 0.049) in RG. In conclusion, serum irisin concentration was associated with energy expenditure and serum FGF-21 level with energy availability measures in lean adolescent athletes, while no relationships of irisin and FGF-21 with energy status measures were observed in lean nonathletic adolescents.

Circulating Irisin Level as a Biomarker for Pure Aortic Stenosis and Aortic Valve Calcification

Irisin, a myokine mainly secreted by skeletal and cardiac muscles, is actively involved in cardiovascular diseases. However, whether irisin is associated with aortic stenosis remains unknown. Two hundred ninety-three severe AS patients who underwent transcatheter aortic valve implantation were enrolled and followed-up for 35 months on average. Enzyme-linked immunosorbent assay (ELISA) was applied to measure circulating irisin levels. Patients were divided into two groups based on the median plasma irisin level. We found that high plasma irisin levels were independently associated with pure aortic stenosis (PAS) after adjusting for age, body mass index, history of peripheral vascular disease, and creatinine (OR = 3.015, 95% CI 1.775-5.119, P < 0.001). ROC curve analysis showed a significant predictive value of irisin for PAS (AUC = 0.647, 95% CI 0.583-0.711, P < 0.001). The severity of aortic valve calcification was negatively associated with plasma irisin levels (P < 0.05). In conclusion, irisin is an independent predictor for PAS and is negatively associated with the severity of aortic valve calcification.

Irisin is more strongly associated with leisure-time physical activity than resistin and high-density lipoprotein cholesterol are

Obectives

Irisin is a myokine with a potential role in cardiometabolic diseases, but previous studies have described inconsistencies between serum irisin and physical activity (PA). Our aim was to analyze the relationship between serum irisin and leisure-time PA (LTPA) in a large sample of the general adult population, and secondarily, to evaluate its relationship with two PA-related biomarkers (HDL cholesterol and resistin).

Design

A cross-sectional study was nested in the “CDC of the Canary Islands” cohort participants (n = 3827, 18–75 years, 60% women).

Methods

PA was collected by administering the Minnesota leisure-time physical activity questionnaire, and physical examination and blood tests (irisin, resistin, HDL-cholesterol) were performed.

Results

Irisin inversely correlated with BMI (p < 0.001 in women) and resistin (p = 0.038 in women, p = 0.004 in men), and directly with HDL cholesterol (p < 0.001in women). There was a direct association of irisin with leisure-time and energy expenditure in light, moderate and vigorous LTPA, which was stronger in women than men. The distribution of leisure-time and PA variables across irisin quintiles showed a significant trend, except for light LPTA in men. Adjusting for age, sex and BMI, the association of irisin with leisure-time and LTPA variables was stronger than the association of these variables with resistin and HDL cholesterol, reaching the strongest association for irisin with the 80th percentile of time of LTPA (OR = 2.57; 95% CI = 2.00–3.31).

Conclusions

There is a direct and independent association between serum irisin levels and LTPA in the general adult population, which is stronger than other biomarkers of PA. Findings on exercise-related irisin support the possibility of irisin health benefits.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Sestrin2 ablation attenuates the exercise-induced browning of white adipose tissue in C57BL/6J mice

AIM

With exercise, white adipose tissues (WAT) are readily convertible to a "brown-like" state, altering from lipid-storing to energy-catabolizing function, which counteracts obesity and increases insulin sensitivity. Sestrin2 (SESN2) is a stress-inducible protein that can regulate the cold-induced increase of uncoupling protein 1 (UCP1), which is paramount for the thermogenic capacity of brown-like WAT. This study aimed to elucidate the necessity of SESN2 in mediating exercise-induced browning of WAT.

METHODS

We used 8-week, male wild-type and SESN2 knockout C57BL/6J mice to explore the potential role of SESN2 in the exercise-induced WAT browning process. Over a 3-week intervention (sedentary versus treadmill exercise, normal chow versus 60% high-fat diet), we examined the exercise-induced alterations of the browning phenotype in different depots of white fat. In vitro, 3T3-L1 pre-adipocytes and primary adipocytes were used to determine the potential mechanism.

RESULTS

Our data revealed that SESN2 was required for the exercise-induced subcutaneous WAT (scWAT) browning. This may be mediated by higher fibronectin type III domain containing 5 (FNDC5) contents in scWAT locally, rather than skeletal muscle FNDC5 expression and circulating serum irisin levels. SESN2 ablation significantly impaired the exercise-improved glucose metabolism, where browning of scWAT may serve as an essential pathway. Moreover, SESN2 ablation significantly attenuated the exercise-promoted respiratory exchange ratio and indexes of energy metabolism (oxygen uptake and energy expenditure).

CONCLUSION

Taken together, our results provided evidence that SESN2 is a key integrating factor in driving the diverse metabolic benefits conferred by aerobic exercise.

The exercise-instrumental music program and irisin levels in younger non-professional athletes

A passive lifestyle and lack of exercise are triggering factors in increasing metabolic syndrome, whereas metabolic syndrome is associated with increased morbidity and mortality. This study aimed to analyse an exercise-based non-pharmacological approach combined with instrumental music to the plasma levels of irisin. The study employed a randomised pretest-posttest-only group design recruiting 30 male participants. The individuals aged between 19-21 years, body mass index (BMI) 18.5-24.9 kg/m2, normal blood pressure, normal resting heart rate (RHR), VO2max 40-50 ml/kg bodyweight/min, normal haemoglobin (Hb). The subjects were randomly divided into three groups, MIE (n=10, moderate-intensity exercise), MIEM (n=10, moderate-intensity exercise + instrumental music), and HIE (n=10, high-intensity exercise). Blood sampling was collected from pre- and 5 min post-exercise treatment. ELISA method was used to measure the circulating irisin levels. The non-parametric Kruskal-Wallis test, Mann Whitney test and Spearman correlation were chosen to analyse the data. The results showed that there is no significant difference in pre-exercise irisin levels (ng/ml) in MIE (1.58±0.89), MIEM (1.77±3.12), and HIE (1.65±0.88) with a P-value of 0.098. Importantly, the alteration of irisin levels post-exercise program revealed that the level of this peptide (ng/ml) is higher in HIE (7.28±5.11) compared to MIE (1.95±1.85) and MIEM (4.16±3.40) with a P-value of 0.019. The plasma levels of irisin significantly correlate to energy expenditure (r=0.353, P≤0.01), plasma peroxisome proliferator-activated receptor gamma coactivator-1α (r=0.597, P≤0.001), and high-density lipoprotein (r=0.513, P≤0.01). In summary, increased irisin secretion may directly contribute to the gradual alteration of energy expenditure and correlate to physical exercise intensity-related musical treatment.

Influence of Healthy Physical Fitness on the Teaching of Aerobics Course Based on Big Data Mining Technology

Healthy physical fitness is one of the hot topics discussed by scholars at home and abroad in recent years, and it is a key indicator for evaluating students' physical function and body shape. Aerobics, also known as bodybuilding, means that the body and health of students should have a better promotion effect, but in reality, many students found that after elective aerobics, body shape and health level basically did not improve, which is related to the setting of aerobics courses, especially the lack of physical training. Aerobics and other sports have common requirements in physical training, such as strength quality, speed quality, endurance quality, agility quality, and flexibility quality. This article is aimed at studying the impact of healthy physical fitness based on big data mining technology on the teaching of aerobics. On the basis of analyzing the process of data mining, the composition of healthy physical fitness, and the role of aerobics, it is used to test students in a certain university through experimental methods and statistical methods. Carry out aerobics teaching experiment, and compare and analyze the data measured by the experimental samples. The experimental results show that the use of healthy physical fitness in aerobics teaching can effectively promote the learning and improvement of aerobics skills.

Sex-Specific Relationship between the Cardiorespiratory Fitness and Plasma Metabolite Patterns in Healthy Humans-Results of the KarMeN Study

Cardiorespiratory fitness (CRF) represents a strong predictor of all-cause mortality and is strongly influenced by regular physical activity (PA). However, the biological mechanisms involved in the body's adaptation to PA remain to be fully elucidated. The aim of this study was to systematically examine the relationship between CRF and plasma metabolite patterns in 252 healthy adults from the cross-sectional Karlsruhe Metabolomics and Nutrition (KarMeN) study. CRF was determined by measuring the peak oxygen uptake during incremental exercise. Fasting plasma samples were analyzed by nuclear magnetic resonance spectroscopy and mass spectrometry coupled to one- or two-dimensional gas chromatography or liquid chromatography. Based on this multi-platform metabolomics approach, 427 plasma analytes were detected. Bi- and multivariate association analyses, adjusted for age and menopausal status, showed that CRF was linked to specific sets of metabolites primarily indicative of lipid metabolism. However, CRF-related metabolite patterns largely differed between sexes. While several phosphatidylcholines were linked to CRF in females, single lyso-phosphatidylcholines and sphingomyelins were associated with CRF in males. When controlling for further assessed clinical and phenotypical parameters, sex-specific CRF tended to be correlated with a smaller number of metabolites linked to lipid, amino acid, or xenobiotics-related metabolism. Interestingly, sex-specific CRF explanation models could be improved when including selected plasma analytes in addition to clinical and phenotypical variables. In summary, this study revealed sex-related differences in CRF-associated plasma metabolite patterns and proved known associations between CRF and risk factors for cardiometabolic diseases such as fat mass, visceral adipose tissue mass, or blood triglycerides in metabolically healthy individuals. Our findings indicate that covariates like sex and, especially, body composition have to be considered when studying blood metabolic markers related to CRF.

Levels of Physical Activity and Their Relationship With Motivational Determinants, Self-Regulation, and Other Health-Related Parameters in University Students

Motivational processes and emotional self-regulation are relevant factors for predicting the practice of physical exercise and for certain health-related parameters. The aim of the present work, developed along two different phases, was, on the one hand, to determine the prevalence of physical inactivity and, on the other hand, to carry out a comparative analysis between physically active and inactive university students in relation to their motivational determinants, emotional self-regulation, physical condition, health-related quality of life and other health parameters. The results obtained showed a prevalence of physical inactivity of 12.78%. Physically inactive participants showed significantly lower scores in intrinsic motivation, emotion regulation, and in some dimensions of health-related quality of life, as well as significantly high levels of body fat mass. Lastly, logistic regression analysis identified low scores in Emotional Clarity (p= .009) and Identified Regulation (p = .011), and high scores in Amotivation (p = .006) as reliable predictors of a physically inactive lifestyle. These results are useful for the design and implementation of programs aimed at promoting health and physical activity, with special attention on physically inactive youth populations.

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.

Irisin: linking metabolism with heart failure

The heart is an organ with extremely high energy expenditure, and cardiac performance is consistent with its metabolic level. Under pathological situations, the heart adjusts its metabolic pattern through mitochondrial regulation and substrate selection to maintain energy homeostasis. Heart failure is associated with impaired cardiac energy production, transduction or utilization. Reduced exercise tolerance, skeletal muscle dystrophy and even cardiac cachexia are commonly found in patients with advanced heart failure. Irisin is a newly identified myokine and is mainly secreted by skeletal muscles after exercise. Irisin regulates metabolism and plays essential roles in the development of metabolic diseases. The heart is another abundant source of irisin synthesis and secretion other than skeletal muscle. However, the functions of irisin in the heart have not been completely elucidated. This review introduces the current understanding of the physiological role of irisin, alteration of irisin levels in heart failure, possible mechanisms of irisin in metabolic remodeling and cardiac hypertrophy, and perspectives of irisin serving as a novel target in the management of heart failure.

Impact of supervised exercise training on pulmonary function parameters, exercise capacity and Irisin Biomarker in Interstitial lung disease patients

OBJECTIVES

To assess the impact of supervised exercise training (SET) on pulmonary function Parameters, exercise capacity and Irisin biomarker in Interstitial Lung Disease (ILD) patients.

METHODS

Ten (10)patients with ILD and 18 healthy controls of age between 30-40+ years were selected for 8-week SET program. Before and after SET all subjects performed exercise capacity six minutes' walk test (6MWT), heart rate (HR) changes were recorded, shortness of Breath Respiratory Questionnaire (SOBQ) was obtained and Irisin levels were measured by Enzyme-Linked Immunosorbent Assay (ELISA). This interventional study was carried out at Department of Physiology, Faculty of Medicine, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia, from October 2018 to February 2019.

RESULTS

Mean six minutes' walk distance (6MWD) was 395 ± 68.4 m at 1st visit increased significantly (p=0.001) to 458.8± 87.1 mat 15 visit. However, 6MWD values found significantly higher in controls (517.4±84.1 m; 561.7±81.6 m; p=0.013) than ILD patients. Overall change (difference between post and pre exercise) in HRvalue was recorded lower in ILD patients (30-35 bpm) as compared to controls (40-45 bpm). Moreover, ILD patients had overall higher SOBQ score than controls. Pre SET Irisin levels of ILD patients (4.24 ±1.73 pg/ml) and controls (3.43 ±1.04pg/ml) were found unchanged dafter SET (4.48±2.02pg/ml, 3.39 ±1.41pg/ml, p=0.677, p=0.093)respectively. However, patients Irisin values were found higher as compared to controls before and after SET.

CONCLUSION

Exercise capacity and Dyspneain patients with ILD were improved after 8-week of SET program. No major changes in Irisin levels among patients with ILD and controls were observed. Additional research requires to be carried out on large number of subjects to deter Minutese the advantages of exercise in ILD.

Circulating Irisin in Healthy Adults: Changes after Acute Exercise, Correlation with Body Composition, and Energy Expenditure Parameters in Cross-Sectional Study

Background and Objectives: Skeletal muscles are considered to be the main source of circulating irisin, both at rest and during physical activity. The aim of this study was to investigate the connection between irisin, body composition, and energy metabolism in humans. Materials and Methods: Serum irisin concentrations before and after acute aerobic exercise on a treadmill in 84 healthy adults were measured and their association with body composition and energy expenditure (EE) (obtained from indirect calorimetry) was determined. Results: The total pre-exercise irisin concentrations in males and females were similar, but higher in females when expressed per body mass kg (p < 0.001). There was an association between pre-exercise irisin per body mass kg, visceral fat rating (rho = −0.52, p = 0.001), and lean tissue % (rho = 0.41, p < 0.05) in males and lean body mass index (LBMI) (rho = −0.59, p < 0.001) in females. The pre-exercise irisin concentration correlated with the resting metabolic rate (RMR) in both sexes (rho = 0.44 in males, rho = 0.36 in females; p < 0.05), but with walking, running, and the EE difference from RMR in running (Δ running EE) in males only (rho = 0.32 to 0.37, p < 0.05). There was no significant change in irisin concentration after exercise in 58% of participants, while it decreased in 23%, and increased in 19%. In male subjects with no change in irisin concentration after exercise, running (p < 0.05) and Δ running EE per body mass kg (p < 0.05) were higher than in those with decreased irisin concentration. Conclusions: These findings indicate that the association of irisin concentration with body composition and EE parameters has sex-dependent differences, and acute exercise can lead to various changes in post-exercise irisin levels.

An NMR-Based Approach to Identify Urinary Metabolites Associated with Acute Physical Exercise and Cardiorespiratory Fitness in Healthy Humans-Results of the KarMeN Study

Knowledge on metabolites distinguishing the metabolic response to acute physical exercise between fit and less fit individuals could clarify mechanisms and metabolic pathways contributing to the beneficial adaptations to exercise. By analyzing data from the cross-sectional KarMeN (Karlsruhe Metabolomics and Nutrition) study, we characterized the acute effects of a standardized exercise tolerance test on urinary metabolites of 255 healthy women and men. In a second step, we aimed to detect a urinary metabolite pattern associated with the cardiorespiratory fitness (CRF), which was determined by measuring the peak oxygen uptake (VO_2peak) during incremental exercise. Spot urine samples were collected pre- and post-exercise and 47 urinary metabolites were identified by nuclear magnetic resonance (NMR) spectroscopy. While the univariate analysis of pre-to-post-exercise differences revealed significant alterations in 37 urinary metabolites, principal component analysis (PCA) did not show a clear separation of the pre- and post-exercise urine samples. Moreover, both bivariate correlation and multiple linear regression analyses revealed only weak relationships between the VO_2peak and single urinary metabolites or urinary metabolic pattern, when adjusting for covariates like age, sex, menopausal status, and lean body mass (LBM). Taken as a whole, our results show that several urinary metabolites (e.g., lactate, pyruvate, alanine, and acetate) reflect acute exercise-induced alterations in the human metabolism. However, as neither pre- and post-exercise levels nor the fold changes of urinary metabolites substantially accounted for the variation of the covariate-adjusted VO_2peak, our results furthermore indicate that the urinary metabolites identified in this study do not allow to draw conclusions on the individual's physical fitness status. Studies investigating the relationship between the human metabolome and functional variables like the CRF should adjust for confounders like age, sex, menopausal status, and LBM.

Glyphosate and AMPA levels in human urine samples and their correlation with food consumption: results of the cross-sectional KarMeN study in Germany

Glyphosate (N-[phosphonomethyl]-glycine) is the most widely used herbicide worldwide. Due to health concerns about glyphosate exposure, its continued use is controversially discussed. Biomonitoring is an important tool in safety evaluation and this study aimed to determine exposure to glyphosate and its metabolite AMPA, in association with food consumption data, in participants of the cross-sectional KarMeN study (Germany). Glyphosate and AMPA levels were measured in 24-h urine samples from study participants (n = 301). For safety evaluation, the intake of glyphosate and AMPA was calculated based on urinary concentrations and checked against the EU acceptable daily intake (ADI) value for glyphosate. Urinary excretion of glyphosate and/or AMPA was correlated with food consumption data. 8.3% of the participants (n = 25) exhibited quantifiable concentrations (> 0.2 µg/L) of glyphosate and/or AMPA in their urine. In 66.5% of the samples, neither glyphosate (< 0.05 µg/L) nor AMPA (< 0.09 µg/L) was detected. The remaining subjects (n = 76) showed traces of glyphosate and/or AMPA. The calculated glyphosate and/or AMPA intake was far below the ADI of glyphosate. Significant, positive associations between urinary glyphosate excretion and consumption of pulses, or urinary AMPA excretion and mushroom intake were observed. Despite the widespread use of glyphosate, the exposure of the KarMeN population to glyphosate and AMPA was found to be very low. Based on the current risk assessment of glyphosate by EFSA, such exposure levels are not expected to pose any risk to human health. The detected associations with consuming certain foods are in line with reports on glyphosate and AMPA residues in food.

Irisin and markers of metabolic derangement in non-diabetic Caucasian subjects with stage I-II obesity during early aging

Irisin concentrations are decreased in subjects with overt diabetes and upregulated in those with obesity or impaired fasting glucose. However, gender-balanced data in older populations, in whom risk factors commonly culminate in overt cardiovascular disease, are scarce. We assessed in non-diabetic Caucasian subjects with stage I-II obesity in the early aging range (50 to 70 years), the relationship between irisin, body composition and markers of metabolic derangement by gender. In 60 (31 women, 29 men) non-diabetics with a body mass index ≥30 - ≤40 kg/m², we measured anthropometrics and body composition (Air Displacement Plethysmography). We assayed lipid and glucose profile by routine methods, plasma irisin by ELISA and measured insulin resistance by the HOMA index. Irisin levels were higher in women than in men (161 [105–198]) vs 83 [33–115] ng/ml, P<0.001), and correlated directly with HOMA index in both (rho 0.735, P<0.001 M, rho 0.452, P = 0.011 F). Sex differences were maintained across insulin resistance severity stages. In men, irisin concentrations correlated directly with body mass index (rho 0.755, P<0.001), waist circumference (rho 0.623, P<0.001), fat mass index (rho 0.762, P<0.001), glucose (rho 0.408, P = 0.028), the fatty liver index (rho 0.705, P<0.001) and FINDRISC score (rho 0.536, P = 0.003). Among non-diabetic Caucasian subjects with obesity in the early stages of aging, irisin levels reflect the amount of body fat and insulin resistance severity, independently of between-gender differences in the adipomyokine concentrations and are associated with markers of visceral adiposity in men but not in women.

Dissimilar Impact of a Mediterranean Diet and Physical Activity on Anthropometric Indices: A Cross-Sectional Study from the ILERVAS Project

There is a close relationship between lifestyle behaviors and excess adiposity. Although body mass index (BMI) is the most used approach to estimate excess weight, other anthropometric indices have been developed to measure total body and abdominal adiposity. However, little is known about the impact of physical activity and adherence to a Mediterranean diet on these indices. Here we report the results of a cross-sectional study with 6672 middle-aged subjects with low to moderate cardiovascular risk from the Ilerda Vascular (ILERVAS) project. The participants' adherence to physical activity (International Physical Activity Questionnaire short form) and MedDiet (Mediterranean Diet Adherence Screener) was evaluated. Measures of total adiposity (BMI, Clínica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE), and Deurenberg's formula), central adiposity (waist and neck circumferences, conicity index, waist to height ratio, Bonora's equation, A body adiposity index, and body roundness index), and lean body mass (Hume formula) were assessed. Irrespective of sex, lower indices of physical activity were associated with higher values of total body fat and central adiposity. This result was constant regardless of the indices used to estimate adiposity. However, the association between MedDiet and obesity indices was much less marked and more dependent on sex than that observed for physical activity. Lean body mass was influenced by neither physical activity nor MedDiet adherence. No joint effect between physical activity and MedDiet to lower estimated total or central adiposity indices was shown. In conclusion, physical activity is related to lower obesity indices in a large cohort of middle-aged subjects. MedDiet showed a slight impact on estimated anthropometric indices, with no joint effect when considering both lifestyle variables. ClinTrials.gov Identifier: NCT03228459.

Association between Circulating Irisin and C-Reactive Protein Levels: A Systematic Review and Meta-Analysis

BACKGROUND

Although previous studies have demonstrated that irisin plays an anti-inflammatory role in the body, conflicting results have been reported regarding the correlation between serum levels of irisin and C-reactive protein (CRP). The present meta-analysis was conducted to further investigate the correlation between irisin and CRP levels.

METHODS

We systematically searched PubMed, the Cochrane Library, Web of Science, Embase, SCOPUS, and Ovid to retrieve studies assessing the correlation between irisin and CRP levels. Meta-analyses were performed using a random-effects model, and the I² index was used to evaluate heterogeneity.

RESULTS

Of the 428 studies that were initially found, 14 studies with 2,530 participants met the inclusion criteria for the meta-analysis. The pooled effect size was calculated as 0.052 (95% confidence interval, -0.047 to 0.152; P=0.302). Subgroup analyses identified s ignificant, positive, but weak correlations between CRP and irisin levels in cohort studies, studies conducted among healthy participants, studies in which the male-to-female ratio was less than 1, in overweight or obese subjects, and in studies with a sample size of at least 100 participants.

CONCLUSION

The present meta-analysis found no overall significant correlation between irisin and CRP levels, although a significant positive correlation was found in overweight or obese subjects. Well-designed studies are needed to verify the results of the present meta-analysis.

Extracellular Vesicles: Delivery Vehicles of Myokines

Movement and regular physical activity are two important factors that help the human body prevent, reduce and treat different chronic diseases such as obesity, type 2 diabetes, heart diseases, hypertension, sarcopenia, cachexia and cancer. During exercise, several tissues release molecules into the blood stream, and are able to mediate beneficial effects throughout the whole body. In particular, contracting skeletal muscle cells have the capacity to communicate with other organs through the release of humoral factors that play an important role in the mechanisms of adaptation to physical exercise. These muscle-derived factors, today recognized as myokines, act as endocrine and paracrine hormones. Moreover, exercise may stimulate the release of small membranous vesicles into circulation, whose composition is influenced by the same exercise. Combining the two hypotheses, these molecules related to exercise, named exer-kines, might be secreted from muscle cells inside small vesicles (nanovesicles). These could act as messengers in tissue cross talk during physical exercise. Thanks to their ability to deliver useful molecules (such as proteins and miRNA) in both physiological and pathological conditions, extracellular vesicles can be thought of as promising candidates for potential therapeutic and diagnostic applications for several diseases.

Fndc5 loss-of-function attenuates exercise-induced browning of white adipose tissue in mice

Fibronectin type III domain containing 5 (Fndc5) is a transmembrane protein highly expressed in the skeletal muscle. It was reported that exercise promotes the shedding of the extracellular domain of Fndc5, generating a circulating peptide (irisin) that cross-talks to adipose tissues to convert lipid-storing white adipocytes to energy-catabolizing beige adipocytes. However, the requirement of Fndc5 in mediating the beneficial effect of exercise remains to be determined. Here, we created a mouse model of Fndc5 mutation through transcription activator-like effector nuclease-mediated DNA targeting. The Fndc5 mutant mice have normal skeletal muscle development, growth, regeneration, as well as glucose and lipid metabolism at resting state, even when fed a high-fat diet. In response to running exercise, however, the Fndc5 mutant mice exhibit reduced glucose tolerance and insulin sensitivity and have lower maximal oxygen consumption compared with the exercised wild-type mice. Mechanistically, Fndc5 mutation attenuates exercise-induced browning of white adipose tissue that is crucial for the metabolic benefits of physical activities. These data provide genetic evidence that Fndc5 is dispensable for muscle development and basal metabolism but essential for exercise-induced browning of white adipose tissues in mice.-Xiong, Y., Wu, Z., Zhang, B., Wang, C., Mao, F., Liu, X., Hu, K., Sun, X., Jin, W., Kuang, S. Fndc5 loss-of-function attenuates exercise-induced browning of white adipose tissue in mice.

Association of serum concentrations of irisin and the adipokines adiponectin and leptin with epicardial fat in cardiovascular surgery patients

Epicardial fat located adjacent to the heart and coronary arteries is associated with increased cardiovascular risk. Irisin is a myokine produced by skeletal muscle after physical exercise, and originally described as a molecule able to promote the browning of white adipose tissue and energy expenditure. In order to decrease cardiovascular risk, it has been proposed as a promising therapeutic target in obesity and type 2 diabetes. We investigated the relationships between serum concentrations of irisin and the adipokines adiponectin and leptin and body fat including epicardial fat in patients undergoing cardiovascular surgery. We obtained serum samples from 93 patients undergoing cardiovascular surgery (age 69.6 (SD 12.8) years, BMI 24.1 ± 4.8 kg/m²). Computed tomography (CT) and echocardiographic data were obtained from the routine preoperative examination. Subcutaneous fat area (SFA, cm²) and visceral fat area (VFA, cm²) near the umbilicus were automatically measured using the standard fat attenuation range. Epicardial fat area (EFA, cm²) was measured at the position where the heart became a long axis image with respect to the apex of the heart in the coronal section image. Total body fat mass, body fat percentage, and skeletal muscle volume (SMV) were estimated using bioelectrical impedance analysis (BIA). Serum irisin concentration was measured by enzyme-linked immunosorbent assay, and compared with adiponectin and leptin concentrations. The data were also compared with the clinical biochemical data. EFA was strongly correlated with BMI (P = 0.0001), non-HDL-C (P = 0.029), TG (P = 0.004), body fat mass (P = 0.0001), and body fat percentage (P = 0.0001). Serum leptin concentration showed a significant positive correlation with BMI (P = 0.0001) and TG (P = 0.001). Adiponectin, but not irisin, showed a significant negative correlation with BMI (P = 0.006) and TG (P = 0.001). Serum leptin level had a significant positive correlation with EFA, VFA, and SFA. In contrast, the serum adiponectin level was significantly negatively correlated with EFA, VFA, and SFA. The serum irisin level was also negatively correlated with EFA (r = -0.249, P = 0.015), and SFA (r = -0.223, P = 0.039), and tended to correlate with VFA (r = -0.198, P = 0.067). The serum level of adiponectin was negatively correlated with that of leptin (r = -0.296, P = 0.012), but there were no significant correlations between irisin and either adiponectin or leptin. Multivariate linear regression demonstrated that EFA showed a positive association with serum leptin level (β = 0.438, P = 0.0001) and a negative correlation with serum irisin level (β = -0.204, P = 0.038) and serum adiponectin level (β = -0.260, P = 0.015) after adjusting for age, sex, and BMI. The present study provided the first evidence of associations of the serum irisin and adipokines (adiponectin and leptin) concentrations with epicardial fat in cardiovascular surgery patients. Irisin may play a role in preventing excess adiposity including epicardial fat, and consequently cardiovascular risk in patients.