Plasma irisin is elevated in type 2 diabetes and is associated with increased E-selectin levels

Prenatal irisin is inversely related to the term placental telomere length

Irisin is a myokine mainly produced by skeletal muscle that impacts the body's systemic metabolism. It is connected to aging, telomere length, and oxidative stress markers in human adults and in vitro. The serum irisin concentration increases during pregnancy and has been linked to some birth outcomes like macrosomia. On the other hand, its inverse relation with the chance of pregnancy disorders like preeclampsia and gestational diabetes suggests a protective role for this myokine in pregnancy. It is suggested that irisin may exert its impact on pregnancy by affecting the placenta, which has not been studied yet. Here, we questioned whether prenatal serum irisin is related to placental markers, including telomere length and antioxidant activity. Research has shown that the status of these markers at birth can predict the predisposition to some chronic diseases later in life. We included 80 pregnant mothers (17-41 years old) and newborn dyads randomly selected from the enrolled participants of the Rafsanjan Birth Cohort Study (one of the five district areas of the PERSIAN birth cohort studies), who delivered at the Nik-Nafs Maternity Hospital in Rafsanjan in 2022. Irisin levels were measured in the mother's blood serum in pregnancy using ELISA. The relative telomere length and the GPX and SOD enzyme activities were measured in the term placenta using real-time PCR and colorimetric assays, respectively. We found an inverse relationship between the serum irisin levels during pregnancy and relative telomere length in the term placenta. Irisin level was not significantly associated with the activity of SOD and GPX enzymes. Therefore, our data does not support the protective role of prenatal irisin on the placental telomere shortening and oxidative stress. Future studies are warranted to assess more placental markers in relation to pregnancy irisin levels.

Exercise and exerkines: Mechanisms and roles in anti-aging and disease prevention

Aging is a complex biological process characterized by increased inflammation and susceptibility to various age-related diseases, including cognitive decline, osteoporosis, and type 2 diabetes. Exercise has been shown to modulate mitochondrial function, immune responses, and inflammatory pathways, thereby attenuating aging through the regulation of exerkines secreted by diverse tissues and organs. These bioactive molecules, which include hepatokines, myokines, adipokines, osteokines, and neurokines, act both locally and systemically to exert protective effects against the detrimental aspects of aging. This review provides a comprehensive summary of different forms of exercise for older adults and the multifaceted role of exercise in anti-aging, focusing on the biological functions and sources of these exerkines. We further explore how exerkines combat aging-related diseases, such as type 2 diabetes and osteoporosis. By stimulating the secretion of these exerkines, exercise supports healthy longevity by promoting tissue homeostasis and metabolic balance. Additionally, the integration of exercise-induced exerkines into therapeutic strategies represents a promising approach to mitigating age-related pathologies at the molecular level. As our understanding deepens, it may pave the way for personalized interventions leveraging physical activity to enhance healthspan and improve quality of life.

The protective effect of irisin against hemorrhagic injury is mediated by PI3K and p38 pathways in hemorrhage/resuscitation

The objective of this study was to investigate whether phosphoinositide 3-kinase (PI3K) and p38 mitogen-activated kinase contribute to the protection of irisin during hemorrhage/resuscitation. Experimental groups were divided based on the different treatments during resuscitation as follows: (1) hemorrhage: adult male CD-1 mice were subjected to hemorrhage at a mean arterial blood pressure of 35-45 mm Hg for 60 minutes, followed by resuscitation with shed blood and lactated Ringer's solution (n = 13); (2) hemorrhage + irisin: receiving irisin (5 μg/kg; n = 13); (3) hemorrhage + irisin + PI3K inhibitor: receiving both Ly294002 (1 mg/kg, i.v.) and irisin (n = 6); and (4) hemorrhage + irisin + p38 inhibitor: receiving SB202190 (1 mg/kg, i.v.) and irisin (n = 6). Compared with hemorrhage/resuscitation control, irisin improved cardiac function and the recovery of hemodynamics in association with the decreased systemic interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α, which were completely abrogated by PI3K or p38 inhibitions. Furthermore, the inhibition of PI3K or p38 abolished irisin-induced reduction of the inflammatory cell infiltration and terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine nick-end labeling-positive apoptosis in the cardiac and skeletal muscles. Irisin reduced TNF-α and IL-6 expression in cardiac and skeletal muscles, which was abrogated by the inhibition of PI3K or p38. Irisin-treated hemorrhage increases the phosphorylation of PI3K and p38 in both cardiac and skeletal muscles, which was mitigated by the inhibition of PI3K or p38. PI3K and p38 play an important role in modulating the protective effect of irisin during the hemorrhage/resuscitation. SIGNIFICANCE STATEMENT: This study has identified a critical pathway in the regulation of trauma/hemorrhage by using a preclinical trauma model, in which irisin, as a hormone factor, stimulates PI3K and p38 pathways to induce protection against traumatic conditions. The study holds promise for developing a new therapeutic strategy to target irisin and its pathways related to PI3K and p38 to treat trauma and its comorbidities to reduce mortality for clinical implications.

Irisin expression and FNDC5 (rs3480) gene polymorphism in type 2 diabetic patients with and without CAD

BACKGROUND

Irisin was found to correlate with coronary artery disease (CAD) in diabetic patients. This study investigated the association of irisin and FNDC5 (SNP rs3480) with the presence and severity of CAD in T2DM.

METHODS

This cross-sectional study included 100 patients with T2DM divided into two groups, DM group (n = 50), including patients without CAD and CAD group (n = 50), including those confirmed to have CAD by coronary angiography. Irisin was measured. SNP rs3480 genotyping of FNDC5 was done.

RESULTS

Irisin levels were significantly lower in the CAD group (p < 0.001). The CAD group had significantly higher HbA1c and lower HDL (p < 0.001). Patients with controlled DM had significantly higher irisin levels (p < 0.001). single nucleotide polymorphism (SNP) rs3480 was not associated with irisin levels, and the FNDC5 rs3480 AA reference allele was significantly associated with significant CAD.

CONCLUSION

Irisin appears to be protective against developing CAD in diabetic patients. Irisin level was an independent predictor of significant CAD in diabetic patients combined with the FNDC5 rs3480 genotype.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04957823.

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 (β =  - 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.

New insights into the roles of Irisin in diabetic cardiomyopathy and vascular diseases

Diabetes mellitus (DM) is a prevalent chronic disease in the 21st century due to increased lifespan and unhealthy lifestyle choices. Extensive research indicates that exercise can play a significant role in regulating systemic metabolism by improving energy metabolism and mitigating various metabolic disorders, including DM. Irisin, a well-known exerkine, was initially reported to enhance energy expenditure by indicating the browning of white adipose tissue (WAT) through peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) signaling. In this review, we summarize the potential mechanisms underlying the beneficial effects of Irisin on glucose dysmetabolism, including reducing gluconeogenesis, enhancing insulin energy expenditure, and promoting glycogenesis. Additionally, we highlight Irisin's potential to improve diabetic vascular diseases by stimulating nitric oxide (NO) production, reducing oxidative and nitrosative stress, curbing inflammation, and attenuating endothelial cell aging. Furthermore, we discuss the potential of Irisin to improve diabetic cardiomyopathy by preventing cardiomyocyte loss and reducing myocardial hypertrophy and fibrosis. Given Irisin's promising functions in managing diabetic cardiomyopathy and vascular diseases, targeting Irisin for therapeutic purposes could be a fruitful avenue for future research and clinical interventions.

Impact of L-Arginine on diabetes-induced neuropathy and myopathy: Roles of PAI-1, Irisin, oxidative stress, NF-κβ, autophagy and microRNA-29a

BACKGROUND

T2DM is a chronic disorder with progressive neuromuscular alterations. L-arginine (ARG) is the most common semi-essential amino acid having several metabolic functions.

AIM

to investigate the impact of L-arginine in combating diabetic-induced neuromyopathy and its possible mechanisms.

MATERIALS & METHODS

24 rats were divided into CON, CON+ARG, DC, DC+ARG. Behavioral tests, Body weight (BW), fasting blood glucose (FBG), insulin, total antioxidant capacity (TAC), malondialdehyde (MDA), plasminogen activator inhibitor-1 (PAI-1), and irisin were done. Creatine kinase-MM (CK-MM), interleukin 4 (IL-4), interleukin 6 (IL-6), TAC, MDA, expression of microRNA-29a mRNA & light chain 3 protein were determined in muscle. Histological and NF-κβ immunohistochemical expression in muscle and nerve were assessed.

RESULTS

ARG supplementation to diabetic rats improved altered behavior, significantly increased BW, insulin, TAC, irisin and Il-4, decreased levels of glucose, microRNA-29a, NF-κβ and LC3 expression, PAI-1, CK-MM and restored the normal histological appearance.

CONCLUSIONS

ARG supplementation potently alleviated diabetic-induced neuromuscular alterations.

Irisin and Triglyceride Glucose Index as Markers of Dyslipidemia in Young Adults

Irisin, is a new myokine, considered a favorable metabolic factor and inversely associated with non-communicable diseases. The biological activities of irisin are currently unknown; however, they include browning white adipose tissue, insulin sensitivity, and anti-inflammatory and antioxidant effects. Triglyceride glucose index is a notable insulin resistance marker that predicts the risk of metabolic dyslipidemia and cardiovascular risk. The study aimed to evaluate the relation of irisin and Triglyceride glucose index (TyG) in young adults to assess the cardiovascular risk. This observational cross-sectional study included 80 participants aged 18 to 35 years (male and females) with cut-off TyG > 4.5 as the prime criteria. With consent, anthropometric measurements were documented. Fasting lipid profile parameters were analyzed, and atherogenic lipid ratios and TyG index were calculated. Serum irisin was analyzed in Bio-Rad ELISA using a standardized Abbkine kit. Decreased irisin levels (0.32 ± 0.04ng/ml) and increased TyG index (4.95 ± 0.012) were observed in the participants with elevated triglyceride levels. The lipid profile parameters and atherogenic lipid ratios were observed to be elevated in males as compared to females. Correlation of irisin with lipid parameters revealed statistically significant positive correlation with HDLc (r = + 0.305) and negative correlation with non-HDLc (r = - 0.393), TC/HDLc (r = -0.508), LDLc/HDLc (r= -0.475) and TyG (r = -0.28). The study concludes that decreased irisin and increased TyG index in young adults reflect the state of metabolic dyslipidemia which enables the identification of individuals with metabolic and atherogenic risk.

A pilot study: effect of irisin on trabecular bone in a streptozotocin-induced animal model of type 1 diabetic osteopathy utilizing a micro-CT

Background

Osteoporosis is a significant co-morbidity of type 1 diabetes mellitus (DM1) leading to increased fracture risk. Exercise-induced hormone 'irisin' in low dosage has been shown to have a beneficial effect on bone metabolism by increasing osteoblast differentiation and reducing osteoclast maturation, and inhibiting apoptosis and inflammation. We investigated the role of irisin in treating diabetic osteopathy by observing its effect on trabecular bone.

Methods

DM1 was induced by intraperitoneal injection of streptozotocin 60 mg/kg body weight. Irisin in low dosage (5 µg twice a week for 6 weeks I/P) was injected into half of the control and 4-week diabetic male Wistar rats. Animals were sacrificed six months after induction of diabetes. The trabecular bone in the femoral head and neck was analyzed using a micro-CT technique. Bone turnover markers were measured using ELISA, Western blot, and RT-PCR techniques.

Results

It was found that DM1 deteriorates the trabecular bone microstructure by increasing trabecular separation (Tb-Sp) and decreasing trabecular thickness (Tb-Th), bone volume fraction (BV/TV), and bone mineral density (BMD). Irisin treatment positively affects bone quality by increasing trabecular number p < 0.05 and improves the BMD, Tb-Sp, and BV/TV by 21-28%. The deterioration in bone microarchitecture is mainly attributed to decreased bone formation observed as low osteocalcin and high sclerostin levels in diabetic bone samples p < 0.001. The irisin treatment significantly suppressed the serum and bone sclerostin levels p < 0.001, increased the serum CTX1 levels p < 0.05, and also showed non-significant improvement in osteocalcin levels.

Conclusions

This is the first pilot study to our knowledge that shows that a low dose of irisin marginally improves the trabecular bone in DM1 and is an effective peptide in reducing sclerostin levels.

Potential role of irisin in digestive system diseases

Digestive system diseases (DSD) are very complex conditions that severely threaten human health. Therefore, there is an urgent need to develop new pharmacological treatment strategies. Irisin, a myokine discovered in 2012, is produced by fibronectin type III domain-containing protein 5 (FNDC5), which is a transmembrane protein. Irisin is involved in promoting the browning of white adipose tissue, the regulation of energy metabolism, and the improvement of insulin resistance. Irisin is also an essential mediator of the inflammatory response, oxidative stress, and cell apoptosis. Recent studies have proved that irisin concentration is altered in DSD and exerts pivotal effects on the initiation, progression, and prognosis of these diseases through various mechanisms. Therefore, studying the expression and function of irisin may have great significance for the diagnosis and treatment of DSD. Here, we focus on irisin and explore the multiple molecular pathways targeted by irisin therapy. This review indicates that irisin can serve as a diagnostic marker or potential therapeutic agent for DSD. DATA AVAILABILITY: Not applicable.

Dulaglutide Protects Mice against Diabetic Sarcopenia-Mediated Muscle Injury by Inhibiting Inflammation and Regulating the Differentiation of Myoblasts

Background

Type 2 diabetes mellitus increases the risk of sarcopenia, which is characterized by decreased muscle mass, strength, and function. However, there are no effective drugs to treat diabetic sarcopenia, and its underlying mechanism remains unknown. Here, we aimed to determine whether the GLP-1 receptor agonist (GLP-1RA) dulaglutide (Dul) affects the progression of diabetic sarcopenia.

Methods

db/db mice were injected intraperitoneally with 0.6 mg/kg dulaglutide for 10 weeks. Mouse muscle tissues were then pathologically evaluated and stained with F4/80 or MPO to detect macrophages and neutrophils, respectively. In addition, inflammatory factors and FNDC5 in the muscle tissues were detected using qRT-PCR. Moreover, C2C12 cells were induced to enable their differentiation into skeletal muscle cells, and muscle factor levels were then detected. Furthermore, changes in muscle factor levels were detected at various glucose concentrations (11 mM, 22 mM, and 44 mM).

Results

In vivo, dulaglutide alleviated muscle tissue injury; reduced levels of the inflammatory factors, IL-1β, IL-6, CCL2, and CXCL1; and reversed the level of FNDC5 in the muscle tissues of db/db mice. In vitro, a C2C12 cell differentiation model was established through the observation of cell morphology and determination of myokine levels. Upon stimulation with high glucose, the differentiation of C2C12 cells was inhibited. Dulaglutide improved this inhibitory state by upregulating the levels of both FNDC5 mRNA and protein.

Conclusions

Treatment with the GLP-1RA dulaglutide protects db/db mice against skeletal muscle injury by inhibiting inflammation and regulating the differentiation of myoblasts. High glucose inhibited the differentiation of C2C12 cells and decreased the mRNA and protein levels of myokines. Dulaglutide could reverse the differentiation state induced in C2C12 cells by high glucose.

Association between Serum Irisin and Leptin Levels and Risk of Depressive Symptoms in the Diabetic Elderly Population

BACKGROUND

Adipokines are considered to be involved in the pathogenesis of diabetes and depression. The associations of serum levels of leptin and irisin with depressive symptoms were investigated in elderly patients with type 2 diabetes (T2DM).

METHODS

189 elderly diabetics were assessed with the 30-item Geriatric Depression Scale (GDS-30), and 57 patients with depressive symptoms and 132 controls were selected. Blood biochemical parameters, including serum irisin and leptin, were measured.

RESULTS

Serum irisin levels were decreased and leptin concentrations were significantly higher in T2DM patients with depressive symptoms compared to controls. In all subjects, the irisin level was inversely correlated with the leptin level and the GDS-30 score, whereas the leptin level was highly correlated with BMI and the GDS-30 score. Higher levels of leptin and lower concentrations of irisin are, among other factors, variables indicative of predictive capacity for depressive symptoms in elderly patients with T2DM.

CONCLUSIONS

The results indicated that irisin and leptin levels may be used as diagnostic markers of depressive symptoms in diabetic, elderly patients and as potential therapeutic targets for the treatment. Further prospective and more extensive studies are needed to clarify the role of these adipokines in the common pathogenesis of depression and diabetes.

Oxidative Stress, Reductive Stress and Antioxidants in Vascular Pathogenesis and Aging

This review is focused on the mechanisms that regulate health, disease and aging redox status, the signal pathways that counteract oxidative and reductive stress, the role of food components and additives with antioxidant properties (curcumin, polyphenols, vitamins, carotenoids, flavonoids, etc.), and the role of the hormones irisin and melatonin in the redox homeostasis of animal and human cells. The correlations between the deviation from optimal redox conditions and inflammation, allergic, aging and autoimmune responses are discussed. Special attention is given to the vascular system, kidney, liver and brain oxidative stress processes. The role of hydrogen peroxide as an intracellular and paracrine signal molecule is also reviewed. The cyanotoxins β-N-methylamino-l-alanine (BMAA), cylindrospermopsin, microcystins and nodularins are introduced as potentially dangerous food and environment pro-oxidants.

Pharmacological and physiological roles of adipokines and myokines in metabolic-related dementia

Dementia is a detrimental neuropathologic condition with considerable physical, mental, social, and financial impact on patients and society. Patients with metabolic syndrome (MetS), a group of diseases that occur in tandem and increase the risk of neurologic diseases, have a higher risk of dementia. The ratio between muscle and adipose tissue is crucial in MetS, as these contain many hormones, including myokines and adipokines, which are involved in crosstalk and local paracrine/autocrine interactions. Evidence suggests that abnormal adipokine and myokine synthesis and release may be implicated in various MetS, such as atherosclerosis, diabetic mellitus (DM), and dyslipidemia, but their precise role is unclear. Here we review the literature on adipokine and myokine involvement in MetS-induced dementia via glucose and insulin homeostasis regulation, neuroinflammation, vascular dysfunction, emotional changes, and cognitive function.

Irisin and Bone in Sickness and in Health: A Narrative Review of the Literature

Irisin is a hormone-like myokine produced by the skeletal muscle in response to exercise. Upon its release into the circulation, it is involved in the browning process and thermogenesis, but recent evidence indicates that this myokine could also regulate the functions of osteoblasts, osteoclasts, and osteocytes. Most human studies have reported that serum irisin levels decrease with age and in conditions involving bone diseases, including both primary and secondary osteoporosis. However, it should be emphasized that recent findings have called into question the importance of circulating irisin, as well as the validity and reproducibility of current methods of irisin measurement. In this review, we summarize data pertaining to the role of irisin in the bone homeostasis of healthy children and adults, as well as in the context of primary and secondary osteoporosis. Additional research is required to address methodological issues, and functional studies are required to clarify whether muscle and bone damage per se affect circulating levels of irisin or whether the modulation of this myokine is caused by the inherent mechanisms of underlying diseases, such as genetic or inflammatory causes. These investigations would shed further light on the effects of irisin on bone homeostasis and bone disease.

Irisin promotes fracture healing by improving osteogenesis and angiogenesis

Background

Osteogenesis and angiogenesis are important for bone fracture healing. Irisin is a muscle-derived monokine that is associated with bone formation.

Methods

To demonstrate the effect of irisin on bone fracture healing, closed mid-diaphyseal femur fractures were produced in 8-week-old C57BL/6 mice. Irisin was administrated intraperitoneally every other day after surgery, fracture healing was assessed by using X-rays. Bone morphometry of the fracture callus were assessed by using micro-computed tomography. Femurs of mice from each group were assessed by the three-point bending testing. Effect of irisin on osteogenic differentiation in mesenchymal stem cells in vitro was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), alkaline phosphatase staining and alizarin red staining. Angiogenesis of human umbilical vein endothelial cells (HUVECs) were evaluated by qRT-PCR, migration tests, and tube formation assays.

Results

Increased callus formation, mineralization and tougher fracture healing were observed in the irisin-treated group than in the control group, indicating the better fracture callus healing due to Irisin treatment. The vessel surface and vessel volume fraction of the callus also increased in the irisin-treated group. The expression of BMP2, CD31, and VEGF in callus were enhanced in the irisin-treated group. In mouse bone mesenchymal stem cells, irisin promoted ALP expression and mineralization, and increased the expression of osteogenic genes, including OSX, Runx2, OPG, ALP, OCN and BMP2. Irisin also promoted HUVEC migration and tube formation. Expression of angiogenic genes, including ANGPT1, ANGPT2, VEGFb, CD31, FGF2, and PDGFRB in HUVECs were increased by irisin.

Conclusion

All the results indicate irisin can promote fracture healing through osteogenesis and angiogenesis. These findings help in the understanding of muscle–bone interactions during fracture healing.

The Translational Potential of this Article

Irisin was one of the most important monokine secreted by skeletal muscle. Studies have found that irisin have anabolic effect one bone remodeling through affecting osteocyte and osteoblast. Based on our study, irisin could promote bone fracture healing by increasing bone mass and vascularization, which provide a potential usage of irisin to promote fracture healing and improve clinical outcomes.

Irisin reduces inflammatory signaling pathways in inflammation-mediated metabolic syndrome

Irisin is an exercise induced myokine first shown to induce the browning of white adipose tissue (WAT) which increases energy expenditure, improves glucose tolerance, and reduces insulin resistance. Among irisin's involvement in lipid homeostasis, osteoblast proliferation, and muscle growth, it also acts as a mediator of many inflammatory pathways throughout the body. This review aims to describe the role of irisin in inflammatory processes and understand how targeting irisin can alter the inflammatory response in metabolic syndrome (MetS). The mechanisms involved in irisin's anti-inflammatory functions include reducing production of pro-inflammatory cytokines while increasing production of anti-inflammatory cytokines, reducing macrophage proliferation, inducing alternatively activated (M2-type) macrophage polarization, inhibiting pathways of increased vascular permeability, and preventing the formation of inflammasomes. While there are some contradictory results, most studies found reduced levels of irisin in MetS and type II diabetes mellitus (T2DM). Irisin treatment of cells exposed to inflammatory stimuli ameliorates the inflammatory response and promotes cellular viability. Numerous methods have been studied to increase plasma irisin levels including dietary, behavioral, and pharmaceutical. Further investigation is necessary to understand how irisin can be targeted for disease modification.

Clinical Importance of FNDC-5 and Selectin-E mRNA Expression Among Type 2 Diabetics with and without Obesity

BACKGROUND

Type 2 diabetes mellitus (T2DM) is growing illnesses associated with metabolic dysregulation such as obesity affecting a large population become leading causes of death worldwide. Fibronectin type III domain-containing protein 5 (FNDC-5) and selectin-E were suggested to have effects on metabolism and diabetes, therefore present study aimed to evaluate the clinical importance of FNDC-5 and selectin-E among the T2DM patients with and without obesity.

METHODS

Study included cohort of 200 T2DM patients with and without obesity. We evaluated FNDC-5, selectin-E mRNA expression as well as vitamin-D, and vitamin-B12 levels in among the T2DM patients with and without obesity.

RESULTS

Study observed significant difference in biochemical parameters included in study. T2DM patients with obesity had significantly higher fasting blood glucose levels (p<0.0001) and HbA1c (glycated hemoglobin) (p<0.0001) compared to those T2DM patients without obesity. T2DM patients with obesity also had higher systolic blood pressure (p=0.001), LDL (low density lipoprotein) (p=0.02), TG (triglycerides) (p=0.02) and cholesterol (p=0.01) compared to T2DM patients without obesity. The mRNA expression of FNDC-5 (p<0.0001) was lower in T2DM patients with obesity compared to T2DM patients without obesity. It was observed that the T2DM patients with vitamin-D deficiency had significantly lower FNDC-5 mRNA expression (p=0.03) when compared with those with sufficient vitamin-D level. T2DM patients with clinically normal vitamin-B12 level expressed 0.60 fold FNDC-5 mRNA expression while B12 deficient T2DM patients had 0.28 fold FNDC-5 mRNA expression (p=0.005). No as such significant association was was observed with selectin-E. A negative correlation of FNDC-5 mRNA expression with Post prandial glucose (mg/dl) (p=0.04) and TG (mg/dl) (p=0.02) was observed.

CONCLUSION

FNDC-5 down regulation was observed with T2DM with obesity, vitamin-D and vitamin-B12 deficiency suggesting obesity, vitamin-D and vitamin-B12 deficiency could be the factor for FNDC-5 down-regulation leading to worseness or progression of disease. We suggest that FNDC-5 down-regulation could be used as an indicator for T2DM worseness and development of other associated complications.

The Association of Serum Irisin with Bone Mineral Density and Turnover Markers in New-Onset Type 2 Diabetic Patients

BACKGROUND

Irisin, an exercise-induced myokine and adipocytokine, has been reported to decrease in type 2 diabetic patients. Recently, several research studies indicated that circulating levels were correlated with bone mineral density (BMD). To evaluate bone metabolism, bone turnover markers (BTMs) should be included. However, with respect to newly diagnosed T2DM patients, the relevance of their irisin levels to their BTMs and BMD remains unclear. The investigation of serum irisin levels in patients who have been newly diagnosed with type 2 diabetes and illumination of the relationship between serum irisin levels and those two indices of BMD and BTMs mentioned above are the intention of this cross-sectional study.

METHODS

66 new-onset type 2 diabetic patients (T2DM group), together with 82 control subjects (NGT group), were recruited in this study. Serum irisin concentrations and BTMs (including osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP), and β-C-terminal telopeptides of type I collagen (β-CTX)) were determined by the enzyme-linked immunosorbent assay (ELISA). Glucose, lipid profile, and insulin were considered as measuring indicators as well. Dual-energy X-ray absorptiometry (DXA) was utilized to evaluate the indicator of BMD. Serum irisin, BTMs, and BMD were compared between diabetic patients and healthy individuals. Pearson and Spearman correlation analyses were applied as well to assess correlations between irisin and BTMs and BMD. Multiple stepwise regression analysis was conducted to identify the independent factors of irisin. ROC curve analyses were carried out for serum irisin prediction for osteoporosis/osteopenia (OP).

RESULTS

The serum levels of irisin, procollagen type 1, intact N-terminal propeptide (P1NP), and osteocalcin (OC) were evidently lower in T2DM subjects than in NGT subjects (10.90 ± 1.88 vs .11.69 ± 2.06 ng/mL, P < 0.05; 36.42(25.68,51.70) vs. 44.52(35.73,58.05)ng/ml, P < 0.05; 16.15(12.40,21.66) vs. 18.70(15.56, 23.22)ng/ml, P < 0.05). Among patients with T2DM, the circulating irisin level of those with OP was lower than that of normal BMD (9.98 ± 2.09 vs. 11.39 ± 1.57 ng/ml, P < 0.01); irisin had a negative correlation with β-C-terminal telopeptides of type I collagen (β-CTX) (r = -0.496, P < 0.001) and came back unrelated to Lumbar BMD; Lumbar BMD was negatively relevant to OC (r = -0.274, P < 0.05) and β-CTX (r = -0.410, P < 0.01). Multiple linear regression analyses of stepwise models implied that TG, LDL-C, and β-CTX were independently associated with serum irisin concentrations (P < 0.01 or P < 0.05).

CONCLUSION

Serum irisin level was declined in patients with type 2 diabetes diagnosed in the near term and had a certain association with bone turnover markers. It is suggested to consider irisin as a potential biomarker of bone metabolic disorder in T2DM patients with the initial diagnosis.

Evaluation of serum adropin and irisin levels and its association with anthropometric obesity indices and biochemical parameters in Type 2 diabetic patients

BACKGROUND/AIM:

The newly described proteins adropin and irisin are a highly conserved polypeptide that plays essential roles in metabolic and energy homeostasis, insulin resistance, and fat browning. The aim of this study is to evaluate the circulating levels of serum adropin and irisin in type 2 diabetes mellitus (T2DM) patients and also to elucidate possible relationships between serum adropin and irisin levels with anthropometric obesity indices and biochemical parameters.

SUBJECTS AND METHODS:

Single-center prospective observational study included 90 T2DM patients referred to the diabetes outpatient clinic. Height, weight, and waist circumference (WC) were measured. Body mass index (BMI) and waist to height ratio (WHtR) were calculated. Fasting blood glucose, glycosylated hemoglobin, serum lipids, creatinine, urea, and blood urea nitrogen were evaluated. Estimated glomerular filtration rate (GFR) was calculated, serum adropin and irisin were evaluated.

RESULTS:

The results showed a significant positive correlation between adropin and irisin in females but not in males ( r = 0.311; P = 0.042). In males’ group, serum adropin levels showed significant negative correlation with serum glucose (–0.423, P = < 0.05), HbA1C (–0.364, P = < 0.05), and GFR (–0.355, P = < 0.05). In contrast, creatinine was showed a significant positive correlation with adropin in males (0.381, P = < 0.05). In females’ group, adropin showed a significant negative correlation with weight (–0.371, P = < 0.05), BMI (–0.349, P = < 0.05), WC (–0.402, P = < 0.01), and WHtR (–0.398, P = < 0.01). Contrary, in males’ group, serum irisin levels showed significant positive correlation with weight (0.338, P = < 0.05), BMI (0.332, P = < 0.05), WC (0.409, P = < 0.01), and WHtR (0.432, P = < 0.01).

CONCLUSION:

This study demonstrated that, in T2DM patients, circulating serum adrpoin correlated negatively with anthropometric obesity indices of obesity in females, while serum irisin was positively correlated with anthropometric obesity indices of obesity in males.

The Associations Between Serum Concentrations of Irisin and Glucose-dependent Insulinotropic Polypeptide with Body Mass Index Among Women with and Without Polycystic Ovary Syndrome

BACKGROUND

The actions of adipocytokines may be a connective factor between obesity and polycystic ovary syndrome (PCOS). It is suggested that irisin, as recently described cytokine secreted by skeletal muscles and glucose-dependent insulinotropic polypeptide (GIP) as an incretin hormone that induces cytokine expression, may play key roles in favoring obesity in these women.

OBJECTIVES

We aimed to evaluate the association between body mass index (BMI) and serum concentrations of irisin/GIP in women with and without PCOS in the linear and non-linear models.

METHODS

This cross-sectional study was conducted among 159 PCOS and 82 healthy eumenorrheic non-hirsute women aged 20 - 50 years. The fractional-polynomial model was used to develop a model of continuous risk factors, which evaluates non-linear associations between irisin/GIP and BMI among women with and without PCOS.

RESULTS

Women with PCOS were significantly younger (28.2 ± 5.8 vs. 33.0 ± 7.8 years, P < 0.001) and had a greater BMI (26.6 ± 5.2 vs. 25.2 ± 4.8 kg/m², P = 0.04) than the healthy counterparts. There were no significant linear and non-linear associations between serum concentration of irisin/GIP and BMI in both groups. The analysis of pair-wise age and BMI matching of women with PCOS and controls confirmed these findings.

CONCLUSIONS

This study showed that irisin and GIP have no association with BMI in women with or without PCOS. This finding could help to better understand the underlying pathophysiological status of PCOS, insulin resistance, and obesity-related disorders. Further large cohort studies are needed to confirm these findings.

Effects of serum irisin, neuregulin 4, and weight management on obese adolescent girls with polycystic ovary syndrome

The study is aimed at investigating the association of serum irisin, neuregulin 4 (NRG4), and anti-müllerian hormone (AMH) with adolescent obesity with polycystic ovary syndrome (PCOS) and the efficacy of weight management interventions. Serum levels of irisin, NRG4, AMH, sex steroid hormone, body mass index (BMI), serum insulin, and C-peptide were measured in 52 obese adolescent girls with PCOS (PCOS group) and 43 obese adolescent girls without PCOS (non-PCOS group). The levels of AMH, NRG4, serum irisin, sex steroid hormones, BMI, serum insulin, and C-peptide were evaluated in obese PCOS girls before and after one year weight management. The levels of AMH, serum insulin, NRG4, and total testosterone of PCOS group were significantly higher than those of non-PCOS group. On the contrary, serum irisin and serum C-peptide in PCOS group were significantly lower than that in non-PCOS group. The levels of fat mass, percent body fat, total testosterone, AMH, NRG4, and serum insulin in the obese girls with PCOS showed significant decreases compared with before weight management intervention. On the contrary, after one year of body weight management intervention, serum irisin and serum C-peptide was significantly increased. Adolescent obesity complicated with PCOS is significantly associated with glucose and lipid metabolism and sex steroid hormone disorders, but the exact pathophysiological and clinical features are highly variable. Weight management intervention can significantly improve the clinical symptoms and hematological indicators, serum irisin and NRG4 can be used as two essential biomarkers for evaluating weight management.

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

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

Role of Irisin in Endocrine and Metabolic Disorders—Possible New Therapeutic Agent?

Irisin is a novel hormone that provides a possible solution for the treatment of metabolic disorders. Discovered in 2012 by Boström et al., irisin very quickly became an interesting subject in medical research. Irisin has been found in cerebrospinal fluid, the cerebellum, thyroid, pineal gland, liver, pancreas, testis, spleen, adult stomach, and human fetuses. Regarding the actions of irisin, both in animals and humans, the results are contradictory but interesting. Its capability to influence adipose tissue and glycemic homeostasis may be utilized in order to treat hypothyroidism, polycystic ovary syndrome, Prader–Willi syndrome, and other endocrine and metabolic disorders. Considering its osteogenic potential, irisin might be a therapeutic choice in diseases caused by a sedentary lifestyle. New data indicate that irisin treatment may serve in the treatment of severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) infection. Furthermore, several therapeutic agents, such as insulin, metformin, fenofibrate, exenatide, and melatonin, influence the concentrations of irisin in animal models or in humans. Nutritional factors including polyunsaturated fatty acids may also have an effect on irisin concentrations. While it may be “too good to be true,” irisin offers many opportunities for future research that would aim to find its optimal therapeutical role in endocrine and metabolic diseases.

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.

Effects of increased physical activity and/or weight loss diet on serum myokine and adipokine levels in overweight adults with impaired glucose metabolism

AIM

The purpose of this study was to investigate the changes in serum irisin, fibroblast growth factor-21 (FGF21), visfatin, follistatin like protein-1 (FSTL1), and meteorin-like protein (Metrnl) levels in response to increased physical activity and/or diet interventions in overweight subjects with impaired glucose metabolism (IGM).

METHODS

A total of 60 subjects (BMI > 25.0 kg/m²) with IGM were recruited in this single-centered interventional study. Twelve subjects dropped out during the study and the study was completed with 48 patients. Patients were divided into two groups as diet only (DI, n = 24) and diet and physical activity intervention (DPA, n = 24). Patients in DI group received a diet program while DPA group received a diet combined with a physical activity intervention for 12 weeks. Additional 24 healthy subjects were recruited to compare the baseline levels of proteins. Serum protein levels, anthropometric measurements, and biochemical parameters were assessed.

RESULTS

Irisin, FGF21, visfatin, and FSTL1 levels significantly decreased in both groups after 12-week intervention (p < 0.001). However, there were no differences in protein levels between DI and DPA groups (p > 0.05). Likewise, the total change in weight was similar in both DI (-4.35 kg) and DPA (-4.85 kg) groups (p > 0.05). A 5% reduction in initial body weight with DPA therapy resulted in a stronger correlation between the changes in irisin, visfatin, and FSTL1 levels and fasting glucose and HbA1c levels.

CONCLUSIONS

These results demonstrate that serum irisin, FGF21, visfatin, and FSTL1 levels decreased in response to weight loss interventions. Weight loss induced by DI or DPA therapies had similar lowering effects on these proteins in subjects with IGM, and these myokines might be related to glucose metabolism biomarkers.

Irisin plays an important role in the outcomes of newly diagnosed prediabetes in adults in Guiyang, China

AIMS/INTRODUCTION

To explore the potential role of irisin in the outcomes of newly diagnosed prediabetes.

MATERIALS AND METHODS

Data were obtained from the Guiyang subcenter of the Risk Evaluation of cAncers in Chinese diabeTic Individuals: a lONgitudinal (REACTION) study. A total of 2,530 participants had newly diagnosed prediabetes at baseline and completed follow up. The nested 1:1 case-control study included 161 participants who developed diabetes mellitus at follow up, and 161 age- and sex-matched controls. The follow-up study included 86 matched case-control pairs. Fasting serum irisin levels were measured using enzyme-linked immunosorbent assay.

RESULTS

Baseline serum irisin levels were higher in the cases than in the controls (P = 0.002); high baseline serum irisin levels were an independent risk factor for the development of diabetes (odds ratio 1.235, 95% confidence interval 1.025-1.488). After adjustment for age, sex, body mass index, glycated hemoglobin (HbA1c), smoking, exercise, and family history of diabetes, subjects in the highest quartile of irisin levels had a higher risk of diabetes than those in the lowest quartile (odds ratio 3.065, 95% confidence interval 1.511-6.218). The extent of decrease in irisin levels during follow-up was greater in the cases than in the controls (P < 0.001). Baseline serum irisin levels were positively correlated with the extent of decrease in irisin during follow-up (r = 0.773, P < 0.001). After adjustment for confounding factors, subjects with a decrease of irisin above the median had much higher risk for diabetes (odds ratio 5.077, 95% confidence interval 2.112-12.206).

CONCLUSIONS

Irisin might play an important role in the outcomes of newly diagnosed prediabetes in adults in Guiyang, and can predict the risk for developing diabetes in these individuals.

Effects of physical activity on cell-to-cell communication during type 2 diabetes: A focus on miRNA signaling

Type 2 diabetes (TD2) is a progressive disease characterized by hyperglycemia that results from alteration in insulin secretion, insulin resistance, or both. A number of alterations involving different tissues and organs have been reported to the development and the progression of T2D, and more relevantly, through cell-to-cell communication pathways. Recent studies demonstrated that miRNAs are considerably implicated to cell-to-cell communication during T2D. Physical activity (PA) is associated with decreasing risks of developing T2D and acts as insulin-like factor. Cumulative evidence suggests that this effect could be mediated in part through improving insulin sensitivity in T2D and obese patients and modulating miRNAs synthesis and release in healthy patients. Therefore, the practice of PA should ideally be established before the initiation of T2D. This review describes cell-to-cell communications involved in the pathophysiology of T2D during PA.

Exercise-Linked Irisin: Consequences on Mental and Cardiovascular Health in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with insulin resistance and hyperglycemia. Chronic exposure to a T2DM microenvironment with hyperglycemia, hyperinsulinemia, oxidative stress and increased levels of proinflammatory mediators, has negative consequences to the cardiovascular system and mental health. Therefore, atherosclerotic cardiovascular diseases (CVD) and mental health issues have been strongly associated with T2DM. Lifestyle modifications, including physical exercise training, are necessary to prevent T2DM development and its associated complications. It is widely known that the regular practice of exercise provides several physiological benefits to subjects with T2DM, such as managing glycemic and blood pressure levels. Different types of exercise, from aerobic to resistance training, are effective to improve mental health and cognitive function in T2DM. Irisin is a myokine produced in response to exercise, which has been pointed as a relevant mechanism of action to explain the benefits of exercise on cardiovascular and mental health in T2DM patients. Here, we review emerging clinical and experimental evidence about exercise-linked irisin consequences to cardiovascular and mental health in T2DM.

The role of Irisin in multiorgan protection

Physical exercise is an effective strategy for improving human health. Various organs, including the heart, lung and kidney, can benefit from exercise. However, the underlying molecular mechanisms by which exercise protects organs remain unknown. Irisin, a myokine secreted from muscle in response to exercise, has attracted increased attention from researchers. The role of irisin in multiorgan protection has been gradually revealed, and this muscle-derived circulating factor is regarded as an essential bridge linking exercise and organ health. The mechanisms by which irisin protects diverse organs are different. Here, we review the research progress on the multiorgan protective effects of irisin and discuss the underlying molecular mechanisms.

Effects of a Combined Endurance/Strength Training Program on Circulating Irisin Levels in Overweight/Obese Men and Women with Type 2 Diabetes Mellitus

Irisin is a promising therapeutic target in patients with type 2 diabetes mellitus (T2DM), as studies have demonstrated that irisin can induce "browning" of adipocytes and mitigate pro-inflammatory conditions. Sex-specific changes in irisin levels have been reported in a study involving healthy men and women following physical training. The present study aims to analyze the effects of an 8-week training intervention on circulating irisin levels in patients with T2DM and to find out whether the training responses differ between T2DM men and women. Twenty-nine overweight/obese T2DM patients (19 men, 10 women; age: 46-74 years; body mass index >25 kg/m²) participated in a combined moderate-intensity endurance/strength training program (3 times a week). The irisin levels of men and women did not differ significantly. The post-training irisin levels did not differ significantly from the pre-training values, and there was no interaction effect of sex. This study shows no training-induced (sex-specific) changes in circulating irisin levels in T2DM patients. Large-scale studies using other forms of training are needed to fully clarify whether basal irisin levels can be changed in T2DM men and/or women to counteract T2DM.

The Usefulness of Diagnostic Panels Based on Circulating Adipocytokines/Regulatory Peptides, Renal Function Tests, Insulin Resistance Indicators and Lipid-Carbohydrate Metabolism Parameters in Diagnosis and Prognosis of Type 2 Diabetes Mellitus with Obesity

The quantitative analysis of selected regulatory molecules, i.e., adropin, irisin, and vaspin in the plasma of obese patients with newly diagnosed, untreated type 2 diabetes mellitus, and in the same patients after six months of using metformin, in relation to adropinemia, irisinemia and vaspinemia in obese individuals, was performed. The relationship between plasma concentration of the adipocytokines/regulatory peptides and parameters of renal function (albumin/creatinine ratio-ACR, estimated glomerular filtration rate-eGFR), values of insulin resistance indicators (Homeostatic Model Assessment of Insulin Resistance (HOMA-IR2), Homeostatic Model Assessment of Insulin Sensitivity (HOMA-S), Homeostatic Model Assessment of β-cell function (HOMA-B), quantitative insulin sensitivity check index (QUICKI), insulin), and parameters of carbohydrate-lipid metabolism (fasting plasma glucose-FPG, glycated hemoglobin-HbA_1C, estimated glucose disposal rate-eGDR, fasting lipid profile, TG/HDL ratio) in obese type 2 diabetic patients was also investigated. Circulating irisin and vaspin were found significantly different in subjects with metabolically healthy obesity and in type 2 diabetic patients. Significant increases in blood levels of both analyzed adipokines/regulatory peptides were observed in diabetic patients after six months of metformin treatment, as compared to pre-treatment levels. The change in plasma vaspin level in response to metformin therapy was parallel with the improving of insulin resistance/sensitivity parameters. An attempt was made to identify a set of biochemical tests that would vary greatly in obese non-diabetic subjects and obese patients with type 2 diabetes, as well as a set of parameters that are changing in patients with type 2 diabetes under the influence of six months metformin therapy, and thus differentiating patients' metabolic state before and after treatment. For these data analyses, both statistical measures of strength of the relationships of individual parameters, as well as multidimensional methods, including discriminant analysis and multifactorial analysis derived from machine learning methods, were used. Adropin, irisin, and vaspin were found as promising regulatory molecules, which may turn out to be useful indicators in the early detection of T2DM and differentiating the obesity phenotype with normal metabolic profile from T2DM obese patients. Multifactorial discriminant analysis revealed that irisin and vaspin plasma levels contribute clinically relevant information concerning the effectiveness of metformin treatment in T2D patients. Among the sets of variables differentiating with the highest accuracy the metabolic state of patients before and after six-month metformin treatment, were: (1) vaspin, HbA1c, HDL, LDL, TG, insulin, and HOMA-B (ACC = 88 [%]); (2) vaspin, irisin, QUICKI, and eGDR (ACC = 86 [%]); as well as, (3) vaspin, irisin, LDL, HOMA-S, ACR, and eGFR (ACC = 86 [%]).

Serum Irisin Levels and Clinical Implication in Elderly Patients With Type 2 Diabetes Mellitus

Background

The aim of this study is to evaluate the level and role of serum irisin in elderly patients with type 2 diabetes mellitus (T2DM) using case-control study.

Methods

A total of 71 patients with T2DM were selected as the case group according to the inclusion criteria and exclusion criteria; and the ratio of 1:1 was calculated according to the inclusion rate of the residents. The cohort established in Guankou Town, Jimei District, Xiamen City, Fujian Province, China and the residents of this cohort were selected at the age of 60 and above. A total of 71 healthy subjects were included as the control group with the same gender and the age with a difference of ± 5 years old. The clinical data of the subjects were collected to determine their previous history, blood pressure, body mass index (BMI), hemoglobin (HB), liver function test, renal function test, fasting blood glucose and serum lipid. The irisin level in serum was measured by enzyme-linked immunosorbent assay (ELISA). The data were analyzed by using SPSS17.0 software. Single factor analysis using Chi-square test or t-test was performed to compare the differences between T2DM patients with the control group of the general data, clinical indicators and irisin level in serum. Logistic regression was used to analyze the protective factors and risk factors of diabetes mellitus.

Results

The results of single factor analysis showed that the level of irisin in T2DM group was significantly lower than that in the control group (703.37 ± 241.51 ng/mL and 800.22 ± 275.59 ng/mL, respectively). The levels of BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), triglyceride (TG) and fasting plasma glucose (FPG) in T2DM group were higher than those in control group, and differences were statistically significant. Logistic regression analysis indicated that irisin may be a protective factor for type 2 diabetes (odds ratio (OR) = 0.997, 95% confidence interval (CI): 0.994 - 0.999).

Conclusions

The serum irisin level in T2DM group was significantly lower than that in control group, suggesting that irisin may be a protective factor for type 2 diabetes.

Role of Skeletal Muscle in Insulin Resistance and Glucose Uptake

The skeletal muscle is the largest organ in the body, by mass. It is also the regulator of glucose homeostasis, responsible for 80% of postprandial glucose uptake from the circulation. Skeletal muscle is essential for metabolism, both for its role in glucose uptake and its importance in exercise and metabolic disease. In this article, we give an overview of the importance of skeletal muscle in metabolism, describing its role in glucose uptake and the diseases that are associated with skeletal muscle metabolic dysregulation. We focus on the role of skeletal muscle in peripheral insulin resistance and the potential for skeletal muscle-targeted therapeutics to combat insulin resistance and diabetes, as well as other metabolic diseases like aging and obesity. In particular, we outline the possibilities and pitfalls of the quest for exercise mimetics, which are intended to target the molecular mechanisms underlying the beneficial effects of exercise on metabolic disease. We also provide a description of the molecular mechanisms that regulate skeletal muscle glucose uptake, including a focus on the SNARE proteins, which are essential regulators of glucose transport into the skeletal muscle. © 2020 American Physiological Society. Compr Physiol 10:785-809, 2020.

Perivascular adipose tissue in cardiovascular diseases-an update

The perivascular adipose tissue (PVAT) has been recently recognized as an important factor in vascular biology, with implications in the pathogenesis of cardiovascular diseases. The cell types and the precursor cells of PVAT appear to be different according to their location, with the component cell type including white, brown, and beige adipocytes. PVAT releases a panel of adipokines and cytokines that maintain vascular homeostasis, but it also has the ability of intervention in the pathogenesis of the atherosclerotic plaques development and in the vascular tone modulation. In this review, we summarize the current knowledge and discuss the role of PVAT as a major contributing factor in the pathogenesis of ischemic coronary disease, hypertension, obesity, and diabetes mellitus. The new perspective of PVAT as an endocrine organ, along with the recent knowledge of the mechanisms involved in dysfunctional PVAT intervention in local vascular homeostasis perturbations, nowadays represent a new area of research in cardiovascular pathology, aiming to discover new therapeutic methods.

Circulating Irisin and esRAGE as Early Biomarkers of Decline of Metabolic Health

A decline in metabolic health may take place before observing any alteration in the levels of the traditional metabolic markers. New indicators of metabolic derangement are therefore compelling. Irisin is a myokine with important metabolic functions. The role of irisin as a metabolic biomarker in humans has not been fully established yet. We quantified plasma irisin and esRAGE in 106 apparently healthy individuals and we performed a cluster analysis to evaluate their associations with metabolic profile. Plasma levels of various traditional markers of metabolic risk (i.e., glucose and lipid levels) were all within the ranges of normality. We identified two clusters of individuals. Compared to cluster 2, individuals in cluster 1 had higher irisin levels, a metabolic profile shifted toward the limits of the reference ranges and lower esRAGE levels. The traditional metabolic blood tests seem not to be enough to identify a metabolic decline early. Irisin increase and esRAGE decrease may reflect a metabolic derangement at the beginning of its development. The role of these molecules as early biomarkers of decline of metabolic health seems an interesting topic to be further explored.

A comparative study of the antidiabetic effect of two training protocols in streptozotocin-nicotinamide diabetic rats

Background Physical inactivity is the major risk factor for type 2 diabetes (T2D). The present study was conducted to investigate the effects of resistance training and endurance training on diabetic-related metabolic parameters in diabetic rats. Materials and methods Twenty-four male Wistar rats were randomly assigned to four groups of six rats each: control group (C), diabetic group (D), resistance training group (RES) and endurance training group (END). T2D was induced intraperitoneally using nicotinamide (120 mg/kg) and streptozotocin (STZ, 65 mg/kg). The training period was 70 days. The irisin, betatrophin, insulin, fasting blood glucose (FBG) and lipid profiles were measured in the serum of all rats. Results Diabetes significantly increased serum levels of FBG (p < 0.001), which were decreased significantly after the administration of training (p < 0.001). Training administration had a significant effect in normalizing serum lipid profiles (p < 0.001) and it was shown to increase the serum levels of irisin, betatrophin (p < 0.001) and insulin (END: p < 0.001 and resistance training: p < 0.05). It was also found that the endurance training was more effective in improving this parameters when compared with resistance training (p < 0.05). In addition, the irisin revealed a significant positive association with betatrophin (END: p < 0.01 and resistance training: p < 0.05) and insulin (END: p < 0.01 and RES: p < 0.05) values in diabetic groups. Conclusion This study demonstrated that endurance training was more effective in diabetic related metabolic derangement compared with resistance training. This effect is probably due to better regulation of irisin, betatrophin and insulin relative to resistance training.

Several Circulating Biomarkers for PCOS Diagnosis

AIMS

Irisin, Betatrophin and Zinc-α2-glycoprotein (ZAG) have been shown to be associated with insulin resistance (IR) and polycystic ovary syndrome (PCOS), respectively. The purpose of this study is to explore the potential accuracy of this combination of three cytokines in screening PCOS.

METHODS

186 individuals were recruited for this study. Circulating Irisin, Betatrophin and ZAG concentrations were measured by enzyme-linked immunosorbent assay. The association between these serum biomarkers and PCOS was assessed by logistic regression analysis. Receiver operating curve (ROC) analysis was performed to evaluate the diagnostic value of these biomarkers for PCOS women.

RESULTS

In women with PCOS, serum Irisin and Betatrophin levels were markedly elevated compared to those in healthy controls (p<0.01), while ZAG levels were lower (p<0.01). PCOS women with IR (M-value<6.28) had lower circulating ZAG concentrations, and higher circulating Irisin and Betatrophin levels relative to PCOS women without IR (M-value ≥ 6.28). ROC curve analyses showed that the AUC for Irisin, ZAG and Betatrophin for predicting PCOS were 0.77, 0.83 and 0.85, respectively. In a joint ROC curves analysis of these serum markers and other parameters, the results showed that the AUC was 0.93, and the sensitivity and specificity were 82.1 % and 92.3 %, respectively.

CONCLUSIONS

When compared to using single cytokine, the analysis of Irisin, ZAG and Betatrophin elevates the accuracy in diagnosing PCOS.

Cytokines and Abnormal Glucose and Lipid Metabolism

Clear evidence indicates that cytokines, for instance, adipokines, hepatokines, inflammatory cytokines, myokines, and osteokines, contribute substantially to the development of abnormal glucose and lipid metabolism. Some cytokines play a positive role in metabolism action, while others have a negative metabolic role linking to the induction of metabolic dysfunction. The mechanisms involved are not fully understood, but are associated with lipid accumulation in organs and tissues, especially in the adipose and liver tissue, changes in energy metabolism, and inflammatory signals derived from various cell types, including immune cells. In this review, we describe the roles of certain cytokines in the regulation of metabolism and inter-organ signaling in regard to the pathophysiological aspects. Given the disease-related changes in circulating levels of relevant cytokines, these factors may serve as biomarkers for the early detection of metabolic disorders. Moreover, based on preclinical studies, certain cytokines that can induce improvements in glucose and lipid metabolism and immune response may emerge as novel targets of broader and more efficacious treatments and prevention of metabolic disease.

Increased Expression of Meteorin-Like Hormone in Type 2 Diabetes and Obesity and Its Association with Irisin

Type 2 diabetes (T2D) is a growing pandemic associated with metabolic dysregulation and chronic inflammation. Meteorin-like hormone (METRNL) is an adipomyokine that is linked to T2D. Our objective was to evaluate the changes in METRNL levels in T2D and obesity and assess the association of METRNL levels with irisin. Overall, 228 Arab individuals were enrolled. Plasma levels of METRNL and irisin were assessed using immunoassay. Plasma levels of METRNL and irisin were significantly higher in T2D patients than in non-diabetic patients (p < 0.05). When the population was stratified based on obesity, METRNL and irisin levels were significantly higher in obese than in non-obese individuals (p < 0.05). We found a significant positive correlation between METRNL and irisin (r = 0.233 and p = 0.001). Additionally, METRNL and irisin showed significant correlation with various metabolic biomarkers associated with T2D and Obesity. Our data shows elevated METRNL plasma levels in individuals with T2D, further exacerbated with obesity. Additionally, a strong positive association was observed between METRNL and irisin. Further studies are necessary to examine the role of these proteins in T2D and obesity, against their ethnic background and to understand the mechanistic significance of their possible interplay.

A Randomized-Controlled Trial Pilot Study Examining the Effect of Pelvic Floor Muscle Training on the Irisin Concentration in Overweight or Obese Elderly Women with Stress Urinary Incontinence

Objective

This study aimed to examine the effect of pelvic floor muscle training on the irisin (Ir) concentration in overweight or obese elderly women with stress urinary incontinence.

Methods

The number of participants included in analysis was 49: 28 women in the experimental group and 21 women in the control group. The experimental group (EG) underwent pelvic floor muscle training, whereas no therapeutic intervention was applied to the control group (CG). Irisin concentration, severity of urinary incontinence (RUIS), and body mass index (BMI) were measured in all women at the initial and final assessments.

Results

By comparing the initial and final assessment results we have been able to demonstrate statistically significant differences in the measured variables in the experimental group. No statistically significant differences in the measured variables were reported for the control group at the initial and final assessments. Moderate negative correlation was observed between the BMI results with the irisin concentration results in the EG at the initial assessment and no correlation at the final assessment. Weak positive correlation was observed between the BMI results with the irisin concentration in the CG at the initial and final assessment.

Conclusion

Further studies are necessary to observe the regulation of irisin concentration and explain mechanisms underlying these effects.

Increased irisin versus reduced fibroblast growth factor1 (FGF1) in relation to adiposity, atherogenicity and hematological indices in metabolic syndrome patients with and without prediabetes

Background Irisin and fibroblast growth factor 1 (FGF1) are intricately involved in metabolic syndrome (MetS) and prediabetes (preDM) pathophysiology. This study aimed to compare and correlate irisin and FGF1 plasma levels, adiposity, atherogenicity and hematological indices in 29 normoglycemic MetS and 30 newly diagnosed drug naive prediabetic (PreDM) MetS patients vs. 29 lean and normoglycemic controls. Materials and methods Irisin and FGF1 plasma levels were measured using colorimetric assays. Intergroup comparisons were conducted by analysis of variance (ANOVA). Spearman's rank correlation was also examined. Results The mean circulating irisin levels (ng/mL) were significantly higher in the normoglycemic (but not prediabetic) MetS group (p < 0.01), while the mean circulating FGF1 levels (pg/mL) were markedly lower in the prediabetic (but not normoglycemic) MetS group (p < 0.05). Of note unlike FGF1, irisin in the MetS (both normoglycemic and prediabetic;N=59) groups correlated significantly and positively with each of waist circumference (WC), hip circumference (HC), body mass index (BMI), body adiposity index (BAI) and high-density lipoprotein-cholesterol (HDL-C) but not the non-HDL-C. Distinctively MetS-irisin negatively associated with the non-HDL-C/HDL-C ratio, total cholesterol (TC)/HDL-C ratio and the low-density lipoprotein-cholesterol (LDL-C)/HDL-C ratio, but positively with the red cell distribution width (RDW). In the same pool of 59 MetS reruits; Neither biomarker had a relationship with the visceral adiposity index (VAI), the lipid accumulation product (LAP), the conicity index (CI), the waist-hip ratio (WHR), the waist-to-height ratio (WHtR), the blood ratios or the atherogenicity index of plasma (AIP). Conclusions As any potential molecular crosstalk of irisin and FGF1 in MetS or its related dysregularities cannot be ruled out; Conversely the utility of irisin and FGF1 as surrogate prognostic biomarkers and putative pharmacotherapeutic targets in the predtion/prevention/management of diabetes and MetS is strongly suggested.

Irisin: A Hope in Understanding and Managing Obesity and Metabolic Syndrome

White adipose tissue (WAT) is an endocrine organ highly integrated in homeostasis and capable of establishing ways of communicating and influencing multiple metabolic processes. Brown adipose tissue promotes energy expenditure by incorporating the uncoupling protein 1 (UCP1), also known as thermogenin, which decouples cellular respiration and heat production, in the mitochondrial membranes. Recent data suggest the presence of a thermogenic cell formation from white adipocytes (beige or brite cells) with a potential role in preventing obesity and metabolic syndrome. The formation of these cells is influenced by physical exertion that induces expression of PPARγ coactivator-1 (PGC1) and downstream membrane protein, fibronectin type III domain-containing protein 5 (FNDC5) in skeletal muscle. Irisin, a thermogenic adipomyokine produced by FNDC5 cleavage is involved in the browning of adipose tissue. While animal studies are congruent with regard to the relationship between physical exertion and irisin release, the results from human studies are less than clear. Therefore, this review focuses on recent advances in our understanding of muscle and adipose tissue thermogenesis. Further, it describes the molecular mechanisms by which irisin impacts exercise, glucose homeostasis and obesity. Finally, the review discusses current gaps and controversies related to irisin release, its mode of action and its future potential as a therapeutic tool in managing obesity and metabolic syndrome.

Perivascular adipose tissue (PVAT) in atherosclerosis: a double-edged sword

Perivascular adipose tissue (PVAT), the adipose tissue that surrounds most of the vasculature, has emerged as an active component of the blood vessel wall regulating vascular homeostasis and affecting the pathogenesis of atherosclerosis. Although PVAT characteristics resemble both brown and white adipose tissues, recent evidence suggests that PVAT develops from its own distinct precursors implying a closer link between PVAT and vascular system. Under physiological conditions, PVAT has potent anti-atherogenic properties mediated by its ability to secrete various biologically active factors that induce non-shivering thermogenesis and metabolize fatty acids. In contrast, under pathological conditions (mainly obesity), PVAT becomes dysfunctional, loses its thermogenic capacity and secretes pro-inflammatory adipokines that induce endothelial dysfunction and infiltration of inflammatory cells, promoting atherosclerosis development. Since PVAT plays crucial roles in regulating key steps of atherosclerosis development, it may constitute a novel therapeutic target for the prevention and treatment of atherosclerosis. Here, we review the current literature regarding the roles of PVAT in the pathogenesis of atherosclerosis.