Interaction between inflammatory bowel disease, physical activity, and myokines: Assessment of serum irisin levels.

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, showed a wide spectrum of intestinal and extra-intestinal manifestations, which rendered the patients physically inactive and impaired their quality of life. It has been found that physical activity is a non-pharmacological intervention that improves the quality of life for those patients. Irisin is one member of the myokines secreted by muscle contraction during exercise and could be used as an anti-inflammatory biomarker in assessing the physical activity of IBD patients. In addition, experimental studies showed that exogenous irisin significantly decreased the inflammatory markers and the histological changes of the intestinal mucosa observed in experimental colitis. Furthermore, irisin produces changes in the diversity of the microbiota. Therefore, endogenous or exogenous irisin, via its anti-inflammatory effects, will improve the health of IBD patients and will limit the barriers to physical activity in patients with IBD.

The Comparison of Irisin, Subfatin, and Adropin in Normal-Weight and Obese Polycystic Ovary Syndrome Patients.

Background: A combination of genetic and environmental factors contribute to the highly common, complex, and varied endocrine condition known as polycystic ovary syndrome (PCOS) in women. PCOS primarily affects women between the ages of 15 and 35 who are in the early to late stages of pregnancy. Thus, this study aimed to evaluate the serum levels of irisin, subfatin, and adropin in PCOS with and without obesity compared to the control group. Methods: The present cross-sectional study was conducted in 2022 at Al-Nahrain University/Department of Chemistry (Baghdad, Iraq). The serum levels of irisin, subfatin, and adropin were measured with the enzyme-linked immunosorbent assay (ELISA) method. Body mass index, lipid profile, insulin, fasting glucose, follicle-stimulating hormone, and luteinizing hormone levels were also evaluated. The data were analyzed using one-way analysis of variance (ANOVA) by GraphPad Prism software version 8.0.2. A P<0.05 was considered statistically significant. Results: The study population comprised PCOS patients (n=90, divided into 45 obese and 45 normal weight) and healthy women (n=30). According to the results, the serum levels of irisin were significantly higher (P<0.001) in obese and normal-weight PCOS patients than controls. While adropin and subfatin were significantly lower in PCOS than controls (P<0.001). Moreover, there are higher levels of serum insulin, fasting glucose, and luteinizing hormone in PCOS women than in healthy women. Conclusion: According to the findings, PCOS patients had a higher level of irisin than the controls. In addition, decreased subfatin and adropin levels were observed in PCOS patients compared with healthy women. Further research is required to confirm these results in the future.

Plasma irisin and the brain-derived neurotrophic factor levels in sedentary subjects: effect of 8-weeks lifestyle intervention.

Objectives. Sedentary lifestyle increasingly observed in the population contributes to the incremental incidence of obesity, cardiovascular diseases, mental disorders, type 2 diabetes, hyper-tension, dyslipidemia, and others. Physical inactivity together with an imbalance in caloric intake and expenditure leads to a loss of muscle mass, reduced insulin sensitivity, and accumulation of the visceral fat. Organokines (adipokines, myokines, hepatokines, etc.) serve in the organism for inter-organ communication. However, human studies focused on the exercise-related changes in plasma levels of certain myokines have produced contradictory results. In the present study, we verified a hypothesis that myokine irisin, which is expected to increase in response to physical activity, induces brain-derived neurotrophic factor (BDNF) production and by this way mediates the beneficial effect of exercise on several brain functions. Subjects and Methods. Women (n=27) and men (n=10) aged 44.5±12.0 years, who were sedentary and overweight/obese (men ≥25%, women ≥28% body fat), participated in the study. The effect of an 8-week intensive lifestyle intervention (150 minutes of moderate physical activity per week, diet modification, and reduction of caloric intake) on the selected organokines (irisin, BDNF) in the context of an expected improvement in cardiometabolic status was examined. Results. The 8-week lifestyle intervention resulted in a significant (p<0.05) reduction in body mass index, body fat, blood pressure, insulin resistance, lipid and liver parameters, and irisin levels (p<0.001). However, BDNF increase in the whole group did not reach statistical significance. After the improvement of cardiometabolic parameters, a significant decrease in irisin and increase in BDNF levels were also observed in the subgroup with unsatisfactory (≤5%) body weight reduction. Neither relationship between irisin and BDNF levels, nor effect of age or sex on their levels was observed. Conclusions. We cannot confirm the hypothesis that exercise-induced irisin may increase the BDNF levels, whereas, the organokine levels in the periphery may not completely reflect the processes in the brain compartments. The observed decrease in irisin levels after 8-week intensive lifestyle intervention program, which was in contrary to its supposed mechanisms of action and dynamics, suggests the presence of several yet undiscovered impacts on the secretion of irisin.

Plasma BDNF/Irisin Ratio Associates with Cognitive Function in Older People.

Background: Reliable blood biomarkers are crucial for early detection and treatment evaluation of cognitive impairment, including Alzheimer's disease and other dementias. Objective: To examine whether plasma biomarkers and their combination are different between older people with mild cognitive impairment (MCI) and cognitively normal individuals, and to explore their relations with cognitive performance. Methods: This cross-sectional study included 250 older adults, including 124 participants with MCI, and 126 cognitively normal participants. Plasma brain-derived neurotrophic factor (BDNF), irisin and clusterin were measured, and BDNF/irisin ratio was calculated. Global cognition was evaluated by the Montreal Cognitive Assessment. Results: Plasma irisin levels, but not BDNF, were significantly different between MCI group and cognitively normal group. Higher irisin concentration was associated with an increased probability for MCI both before and after controlling covariates. By contrast, plasma BDNF concentration, but not irisin, was linearly correlated with cognitive performance after adjusting for covariates. Higher BDNF/irisin ratios were not only correlated with better cognitive performance, but also associated with lower risks of MCI, no matter whether we adjusted for covariates. Plasma BDNF and irisin concentrations increased with aging, whereas BDNF/irisin ratios remained stable. No significant results of clusterin were observed. Conclusions: Plasma BDNF/irisin ratio may be a reliable indicator which not only reflects the odds of the presence of MCI but also directly associates with cognitive performance.

Irisin Levels in Cerebrospinal Fluid Correlate with Biomarkers and Clinical Dementia Scores in Alzheimer Disease.

OBJECTIVE: Irisin, released by muscles during exercise, was recently identified as a neuroprotective factor in mouse models of Alzheimer disease (AD). In a cohort of AD patients, we studied cerebrospinal fluid (CSF) and plasma irisin levels, sex interactions, and correlations with disease biomarkers. METHODS: Correlations between CSF and plasma irisin levels and AD biomarkers (amyloid ß 1-42, hyperphosphorylated tau, and total tau [t-tau]) and Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) were analyzed in a cohort of patients with Alzheimer dementia (n = 82), mild cognitive impairment (n = 44), and subjective memory complaint (n = 20) biologically characterized according to the recent amyloid/tau/neurodegeneration classification. RESULTS: CSF irisin was reduced in Alzheimer dementia patients (p < 0.0001), with lower levels in female patients. Moreover, CSF irisin correlated positively with Aß42 in both female (r = 0.379, p < 0.001) and male (r = 0.262, p < 0.05) patients, and negatively with CDR-SOB (r = -0.234, p < 0.05) only in female patients. A negative trend was also observed between CSF irisin and t-tau levels in all patients (r = -0.144, p = 0.082) and in the female subgroup (r = -0.189, p = 0.084). INTERPRETATION: The results highlight the relationship between irisin and biomarkers of AD pathology, especially in females. Our findings also offer perspectives toward the use of irisin as a marker of the AD continuum. ANN NEUROL 2024;96:61-73.

Effect of Alpha-1 Antitrypsin and Irisin on Post-Exercise Inflammatory Response: A Narrative Review.

Physical activity has a positive effect on human health and emotional well-being. However, in both amateur and professional athletes, training poses a risk of acute or chronic injury through repetitive overloading of bones, joints, and muscles. Inflammation can be an adverse effect of intense exercise caused by several factors including oxidative stress. The present narrative review summarizes current knowledge on inflammatory markers induced by physical exercise. Post-exercise recovery may reduce inflammatory responses and is key to effective training and adaptation of muscle tissues to sustained physical exertion.

Elevated serum irisin levels in boys with central precocious puberty independent of BMI.

INTRODUCTION: Central precocious puberty (CPP) is a prevalent endocrine disorder. Research has indicated that pubertal development is linked to nutritional metabolism. Irisin, a novel myokine/adipokine, has been identified as a potential predictor of CPP in girls. This study aims to examine the relationship between serum irisin levels and CPP in boys. MATERIAL AND METHODS: An enzyme-linked immunosorbent assay (ELISA) was used to measure serum irisin levels in 32 boys diagnosed with CPP and 33 prepubertal age-matched boys as normal controls (NC). To assess the impact of body mass index (BMI) on irisin levels, both the CPP and NC groups were divided into overweight/obese and normal-weight subgroups. Spearman correlation analysis was employed to assess the connection between irisin and clinical and biochemical parameters. Additionally, a receiver operating characteristic curve was utilised to determine the optimal threshold value for irisin. RESULTS: In the normal-weight subgroups, boys with CPP exhibited elevated irisin levels compared to controls, but not in the overweight/obese subgroups. The optimal cut-off value for irisin levels to predict CPP in the normal-weight groups was 93.09 ng/mL, yielding a sensitivity of 47.6% and a specificity of 100%. Furthermore, a positive correlation was noted between irisin levels and bone age (BA), bone age advancement (BA-CA), and BMI. CONCLUSIONS: Serum irisin levels correlate with BMI and pubertal development. Given its limited sensitivity, irisin level can only be utilised as a supplementary rather than a standalone diagnostic indicator for CPP.

Circulating levels of irisin and Meteorin-like protein in PCOS and its correlation with metabolic parameters.

INTRODUCTION: Research on obesity, which results from excessive food consumption and sedentary lifestyle, has focused on increasing energy expenditure. Recently, muscle tissue is being investigated as an endocrine active organ, secreting molecules called myokines. Multiple studies have been performed to assess myokine levels in various disorders, including polycystic ovary syndrome (PCOS) and metabolic syndrome. Irisin and Meteorin-like protein (Metrnl) are particles which, among others, are suggested to play an important role in adipose tissue browning and improving insulin sensitivity. MATERIAL AND METHODS: The study population consisted of 31 women with PCOS and 18 healthy individuals. PCOS was diagnosed based on revised 2003 Rotterdam criteria. Multiple anthropometrical, hormonal, and biochemical parameters were assessed, including oral glucose tolerance test and body composition with dual energy X-ray absorptiometry. Serum levels of irisin and Metrnl were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: There were no differences between the PCOS and control groups according to age, body mass index (BMI), waist-to-hip ratio (WHR), fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), or body mass composition. Assessment of Metrnl and irisin concentrations revealed no significant differences between PCOS and healthy women. The irisin level was negatively correlated with BMI, body fat mass, fasting glucose, and insulin concentrations. No relationship between Metrnl level and metabolic parameters was found. CONCLUSIONS: Although irisin seems to be a promising biomarker, inconsistent research limits its value in clinical use in the assessment or treatment of obesity. Metrnl level was not affected in the study population, but it might be connected to the severity of metabolic disturbances.

Irisin combined index to diagnose central precocious puberty in girls: a cross-sectional study.

BACKGROUND: To investigate serum irisin levels in girls at different developmental status and explore the significance of irisin for the diagnosis of central precocious puberty (CPP) in girls. METHODS: In this cross-sectional study 111 girls were enrolled, including 43 cases of CPP, 44 cases of peripheral precocious puberty (PPP) and 24 cases of girls with normal sexual development as controls. The data on age, weight and height, measured blood levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol, and irisin were collected. Pelvic Doppler ultrasound was performed to evaluate uterine length, transverse diameter, anteroposterior diameter. The girls were divided into non-CPP group and CPP group according to gonadotropin-releasing hormone (GnRH) stimulation test. RESULTS: Serum irisin levels were significantly higher in CPP group than in PPP group and normal control group. Serum irisin level was positively correlated with basal LH level, basal FSH level, peak LH level, peak LH /FSH ratio, uterine volume, bone age, and bone age index. The area under the curve, cut-off value, sensitivity and specificity of serum irisin were 0.958, 219.255 pg/ml, 100% and 80.6%. The combined diagnosis of CPP in girls by serum irisin and serum basal LH combined with uterine volume had an AUC, sensitivity, and specificity of 0.994, 97.6%, and 100%, superior to that of the single index. CONCLUSIONS: Serum irisin level in girls with CPP is significantly increased. An irisin combined index could help the diagnosis of CPP in girls.

Effects of 3.5-GHz radiofrequency radiation on energy-regulatory hormone levels in the blood and adipose tissue.

In recent years exposure of living beings to radiofrequency radiation (RFR) emitted from wireless equipment has increased. In this study, we investigated the effects of 3.5-GHz RFR on hormones that regulate energy metabolism in the body. Twenty-eight rats were divided into four groups: healthy sham (n = 7), healthy RFR (n = 7), diabetic sham (n = 7), and diabetic RFR (n = 7). Over a month, each group spent 2 h/day in a Plexiglas carousel. The rats in the experimental group were exposed to RFR, but the sham groups were not. At the end of the experiment, blood and adipose tissues were collected from euthanized rats. Total antioxidant, total oxidant, hydrogen peroxide, ghrelin, nesfatin-1, and irisin were determined. Insulin expression in pancreatic tissues was examined by immunohistochemical analysis. Whole body specific absorption rate was 37 mW/kg. For the parameters analyzed in blood and fat, the estimated effect size varied within the ranges of 0.215-0.929 and 0.503-0.839, respectively. The blood and adipose nesfatin-1 (p = 0.002), blood and pancreatic insulin are decreased, (p = 0.001), gherelin (p = 0.020), irisin (p = 0.020), and blood glucose (p = 0.040) are increased in healthy and diabetic rats exposed to RFR. While nesfatin-1 are negatively correlated with oxidative stress, hyperglycemia and insulin, ghrelin and irisin are positively correlated with oxidative stress and hyperglycemia. Thus, RFR may have deleterious effects on energy metabolism, particularly in the presence of diabetes.

A case-control study to evaluate irisin levels in patients with type 1 diabetes mellitus.

BACKGROUND: Irisin is a precious hormone-like myokine that plays a key role in glucose/energy expenditure and metabolic regulation This paper aimed to determine the irisin levels in patients with type 1 diabetes mellitus and their correlation with insulin therapy and glycaemic control. METHODS: Ninety type 1 diabetes mellitus patients were collected. The patients were subdivided into two groups: group I (37) newly diagnosed type 1 diabetes mellitus and group II (53) T1DM (on insulin injection); for comparison, 30 healthy individuals were included as control. The serum levels of irisin were estimated using ELISA. FSG and lipid profile were measured through spectrophotometrically. Glycated hemoglobin was determined using High-performance liquid chromatography. RESULT: Serum levels of irisin were significantly lower (P = 0.01), as compared to the control group. Also irisin level was significantly lower in group I compared to group II. Fasting serum glucose, glycated hemoglobin, and lipid profile were significantly elevated in patient groups compared to the control group. Serum irisin was negatively correlated to fasting serum glucose, and glycated hemoglobin, whereas it positively correlated to serum lipid profile. In multiple stepwise regression, only glycated hemoglobin (ß = - 0.600, P = 0.040) was determined as an independent predictor for predicting the irisin levels. The AUC was excellent (AUC = 0.996, P = 0.0001), with high diagnostic accuracy (88.2) in differentiating newly diagnosed type 1 diabetes mellitus from the healthy subject group. CONCLUSION: We demonstrated low irisin levels in type 1 diabetes mellitus and the association of the highest irisin amounts to an insulin therapy and a better glycaemic control. Furthermore, the measurement of irisin levels could be useful as laboratory markers to monitor type 1 diabetes mellitus severity and therapy response.

Glycosylated fibronectin improves first-trimester prediction of pre-eclampsia.

OBJECTIVE: To determine whether maternal serum glycosylated fibronectin (GlyFn) level in the first trimester increases the sensitivity of the Fetal Medicine Foundation (FMF) triple test, which incorporates mean arterial pressure, uterine artery pulsatility index and placental growth factor, when screening for pre-eclampsia (PE) in an Asian population. METHODS: This was a nested case-control study of Chinese women with a singleton pregnancy who were screened for PE at 11-13 weeks' gestation as part of a non-intervention study between December 2016 and June 2018. GlyFn levels were measured retrospectively in archived serum from 1685 pregnancies, including 101 with PE, using an enzyme-linked immunosorbent assay (ELISA), and from 448 pregnancies, including 101 with PE, using a point-of-care (POC) device. Concordance between ELISA and POC tests was assessed using Lin's correlation coefficient and Passing-Bablok and Bland-Altman analyses. GlyFn was transformed into multiples of the median (MoM) to adjust for maternal and pregnancy characteristics. GlyFn MoM was compared between PE and non-PE pregnancies, and the association between GlyFn MoM and gestational age at delivery with PE was assessed. Risk for developing PE was estimated using the FMF competing-risks model. Screening performance for preterm and any-onset PE using different biomarker combinations was quantified by area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at a 10% fixed false-positive rate (FPR). Differences in AUC between biomarker combinations were compared using the DeLong test. RESULTS: The concordance correlation coefficient between ELISA and POC measurements was 0.86 (95% CI, 0.83-0.88). Passing-Bablok analysis indicated proportional bias (slope, 1.08 (95% CI, 1.04-1.14)), with POC GlyFn being significantly higher compared with ELISA GlyFn. ELISA GlyFn in non-PE pregnancies was independent of gestational age at screening (P = 0.11), but significantly dependent on maternal age (P < 0.003), weight (P < 0.0002), height (P = 0.001), parity (P < 0.02) and smoking status (P = 0.002). Compared with non-PE pregnancies, median GlyFn MoM using ELISA and POC testing was elevated significantly in those with preterm PE (1.23 vs 1.00; P < 0.0001 and 1.18 vs 1.00; P < 0.0001, respectively) and those with term PE (1.26 vs 1.00; P < 0.0001 and 1.22 vs 1.00; P < 0.0001, respectively). GlyFn MoM was not correlated with gestational age at delivery with PE (P = 0.989). Adding GlyFn to the FMF triple test for preterm PE increased significantly the AUC from 0.859 to 0.896 (P = 0.012) and increased the DR at 10% FPR from 64.9% (95% CI, 48.7-81.1%) to 82.9% (95% CI, 66.4-93.4%). The corresponding DRs at 10% FPR for any-onset PE were 52.5% (95% CI, 42.3-62.5%) and 65.4% (95% CI, 55.2-74.5%), respectively. CONCLUSIONS: Adding GlyFn to the FMF triple test increased the screening sensitivity for both preterm and any-onset PE in an Asian population. Prospective non-intervention studies are needed to confirm these initial findings. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Serum irisin levels in colorectal cancer patients.

OBJECTIVE: There are limited studies investigating the role of irisin in colorectal cancer, and the results are diverse. The role of irisin in colorectal cancer patients was investigated in this study. PATIENTS AND METHODS: This cross-sectional study included 53 patients diagnosed with colorectal cancer (CRC) and 87 healthy volunteers. Serum irisin, glucose, insulin, C-peptide, and whole blood hemoglobin A1c (HbA1c) levels were measured in venous blood samples taken from patients and the control group. RESULTS: The mean serum irisin levels were significantly lower in the patient group (23.97 ± 16.94 ng/mL) than in the control group (32.71 ± 17.26 ng/mL) (p = 0.004). Serum glucose levels were 96.58 ± 15.12 mg/dL in the patient group and 81.91 ± 11.24 mg/dL in the control group. Serum glucose levels were significantly higher in the patient group than in the control group (p < 0.01). In the patient group, there was no statistically significant difference between metastasis (+) patients and metastasis (-) patients in terms of serum irisin levels (27.53 ± 18.48 ng/mL and 21.23 ± 15.43 ng/mL, respectively; p = 0.182). CONCLUSIONS: Our study has provided new insights into the potential role of irisin in CRC. However, further studies, including in vitro, in vivo, and larger patient groups, are necessary to fully understand the potential of irisin as a biomarker or therapeutic target for CRC and other diseases.

Circulating asprosin, irisin, and abdominal obesity in Chinese patients with type 2 diabetes mellitus: a case-control study.

INTRODUCTION: Studies have suggested that serum asprosin and irisin were involved in type 2 diabetes mellitus (T2DM) and obesity. This study evaluated circulating levels of asprosin and irisin and their associations with anthropometric and metabolic parameters, especially the visceral fat area (VFA) in T2DM patients with abdominal obesity (AO). MATERIAL AND METHODS: In this case-control study, 131 patients with T2DM were grouped into an AO group (n = 68) and a non-AO group (NAO) (n = 63) based on their VFA. Anthropometric and metabolic parameters as well as serum asprosin and irisin levels were measured and compared between the 2 groups. RESULTS: Compared to the NAO group, the AO group had significantly higher serum asprosin and irisin concentrations (3.67 ± 1.76 ng/mL vs. 2.85 ± 0.90 ng/mL, p = 0.001; 154.62 ± 61.87 pg/mL vs. 130.54 ± 34.89 pg/mL, p = 0.008, respectively) and greater VFA (p < 0.001). Serum asprosin in the AO group was positively associated with weight, waist circumference (WC), hipline, body mass index, fasting blood glucose (FBG), glycated haemoglobin (HbA1c), VFA, subcutaneous fat area, and total abdominal fat area (TAFA), and the serum irisin concentration in the AO group was positively correlated with WC, waist-to-hip ratio (WHR), VFA, and TAFA and negatively correlated with FBG. Stepwise logistic regression analysis suggested that FBG and VFA were independent factors positively associated with serum asprosin, and that FBG was independently, negatively associated with serum irisin, while VFA was independently, positively associated with serum irisin. CONCLUSIONS: Elevated serum asprosin and irisin levels in T2DM patients with AO and their correlations with other metabolic parameters suggest that both are potential therapeutic agents/targets in treating obesity and its related disorders.

Relationship between Serum Irisin Levels and MRI-Measured Cerebral Small Vessel Disease in Japanese Men.

AIM: Irisin, an exercise-induced myokine, is a potential neurotrophic factor; however, its relationship with cerebral small vessel disease (CSVD) remains unknown. Therefore, we investigated whether serum irisin levels are associated with CSVD in healthy Japanese men. METHODS: We analyzed data from 720 men free of stroke and participated in this observational study. Serum irisin levels were measured by enzyme-linked immunosorbent assay. CSVD was assessed on deep and subcortical white matter hyperintensities (DSWMHs), periventricular hyperintensities (PVHs), lacunar infarcts (LIs), and cerebral microbleeds (CMBs) on brain magnetic resonance imaging. We calculated the total CSVD score (ranges 0-4) to express the total CSVD burden. We computed the adjusted odds ratios (ORs), with 95% confidence intervals (CIs), of the total CSVD score and individual CSVD features using logistic regression models according to the quartiles of irisin (reference: Q1). RESULTS: Serum irisin levels were associated with lower ORs of higher (vs. zero or lower score) total CSVD score, with the lowest risk (OR, 0.63; 95% CI, 0.41-0.97) being observed in Q3 compared to Q1 after adjustment of potential covariates. Similar results were obtained for younger adults (＜65 years). Among individual CSVD features, irisin was associated with a reduced risk of LIs in the total sample and PVHs, LIs, and CMBs in younger adults. No relationship was observed in older adults (≥ 65 years). CONCLUSIONS: Serum irisin levels were associated with less burden of total CSVD in healthy Japanese men. Serum irisin levels were also related with a reduced risk of PVHs, LIs, and CMBs, but not DSWMHs.

The serum irisin response to prolonged physical activity in temperate and hot environments in older men with hypertension or type 2 diabetes.

Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m2) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (Tco) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite Tco not being different between groups, Tco was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury.

Circulating Irisin in Children and Adolescents With Prader-Willi Syndrome: Relation With Glucose Metabolism.

Irisin is a myokine involved in the browning of white adipose tissue and regulation of energy expenditure, glucose homeostasis and insulin sensitivity. Debated evidence exists on the metabolic role played by irisin in children with overweight or obesity, while few information exist in children with Prader Willi Syndrome (PWS), a condition genetically prone to obesity. Here we assessed serum irisin in relation to the metabolic profile and body composition in children and adolescents with and without PWS. In 25 PWS subjects [age 6.6-17.8y; body mass index standard deviation score (BMI SDS) 2.5 ± 0.3] and 25 age, and BMI-matched controls (age 6.8-18.0y; BMI SDS, 2.8 ± 0.1) we assessed irisin levels and metabolic profile inclusive of oral glucose tolerance test (OGTT), and body composition by dual-energy X-ray absorptiometry (DXA). In PWS, we recorded lower levels of fat-free mass (FFM) (p <0.05), fasting (p<0.0001) and 2h post-OGTT insulin (p<0.05) and lower insulin resistance as expressed by homeostatic model of insulin resistance (HOMA-IR) (p<0.0001). Irisin levels were significantly lower in PWS group than in controls with common obesity (p<0.05). In univariate correlation analysis, positive associations linked irisin to insulin OGTT0 (p<0.05), insulin OGTT120 (p<0.005), HOMA-IR (p<0.05) and fasting C-peptide (p<0.05). In stepwise multivariable regression analysis, irisin levels were independently predicted by insulin OGTT120. These results suggest a link between irisin levels and insulin sensitivity in two divergent models of obesity.

The effect of coconut oil on anthropometric measurements and irisin levels in overweight individuals.

AIM: This study aimed to discover the effects of coconut oil intake and diet therapy on anthropometric measurements, biochemical findings and irisin levels in overweight individuals. MATERIALS AND METHODS: Overweight individuals (n = 44, 19-30 years) without any chronic disease were included. In this randomized controlled crossover study, the participants were divided into two groups (Group 1: 23 people, Group 2: 21 people). In the first phase, Group 1 received diet therapy to lose 0.5-1 kg of weight per week and 20 mL of coconut oil/day, while Group 2 only received diet therapy. In the second phase, Group 1 received diet therapy while Group 2 received diet therapy and 20 mL of coconut oil/day. Anthropometric measurements were taken four times. Irisin was measured four times by enzyme-linked immunosorbent (ELISA) method and other biochemical findings were measured twice. Statistical analysis was made on SPSS 20. RESULTS: The irisin level decreased significantly when the participants only took coconut oil (p ≤ 0.05). There was a significant decrease in the participants' body weight, body mass index (BMI) level and body fat percentage (p ≤ 0.01). Insulin, total cholesterol, low density lipoproteins (LDL) cholesterol, and triglyceride (TG) levels of all participants decreased significantly (p ≤ 0.05). There was no significant difference in irisin level due to body weight loss (p ≤ 0.05); coconut oil provided a significant decrease in irisin level (p ≤ 0.05). CONCLUSION: Diet therapy and weight loss did not have an effect on irisin level, but coconut oil alone was found to reduce irisin level. Coconut oil had no impact on anthropometric and biochemical findings.

Association of irisin levels with cardiac magnetic resonance, inflammatory, and biochemical parameters in patients with chronic heart failure versus controls.

BACKGROUND AND AIMS: Chronic heart failure (CHF) represents a significant cause of morbidity and mortality globally. Metabolic maladaptation has proven to be critical in the progression of this condition. Preclinical studies have shown that irisin, an adipomyokine involved in metabolic regulations, can induce positive cardioprotective effects by improving cardiac remodeling, cardiomyocyte viability, calcium delivery, and reducing inflammatory mediators. However, data on clinical studies identifying the associations between irisin levels and functional imaging parameters are scarce in CHF patients. The objective of this study was to determine the association of irisin levels with cardiac imaging measurements through cardiac magnetic resonance, inflammatory markers, and biochemical parameters in patients with CHF compared with control subjects. METHODS AND RESULTS: Thirty-two subjects diagnosed with CHF and thirty-two healthy controls were evaluated in a cross-sectional study. Serum irisin levels were significantly lower in patients with CHF than in controls. This is the first study to report a significant positive correlation between irisin levels and cardiac magnetic resonance parameters such as left ventricular ejection fraction, fraction shortening, and global radial strain. A negative correlation was demonstrated between irisin levels and brain natriuretic peptide, insulin levels, and Homeostatic model assessment for insulin resistance index. We did not observe significant correlations between irisin levels and inflammatory cytokines. CONCLUSIONS: Given the importance of fraction shortening and global radial strain as accurate markers of ventricular wall motion, these results support the hypothesis that irisin may play an essential role in maintaining an adequate myocardial wall architecture, deformation, and thickness.