Serum levels of irisin in gestational diabetes mellitus during pregnancy and after delivery

The Role of Irisin throughout Women's Life Span

Since its discovery, much attention has been drawn to irisin's potential role in metabolic and reproductive diseases. This narrative review summarizes and updates the possible role played by this fascinating molecule in different physiological (puberty and menopause) and pathological (polycystic ovary syndrome (PCOS), functional hypothalamic amenorrhea (FHA), endometriosis, and gestational diabetes) conditions that can affect women throughout their entire lives. Irisin appears to be an important factor for the hypothalamic-pituitary-gonadal axis activation, and appears to play a role in the timing of puberty onset. Serum irisin levels have been proposed as a biomarker for predicting the future development of gestational diabetes (GDM). Its role in PCOS is still controversial, although an "irisin resistance" mechanism has been hypothesized. In addition to its impact on metabolism, irisin also appears to influence bone health. Irisin levels are inversely correlated with the prevalence of fractures in postmenopausal women. Similar mechanisms have also been postulated in young women with FHA. In clinical settings, further controlled, prospective and randomized clinical trials are needed to investigate the casual relationship between irisin levels and the conditions described and, in turn, to establish the role of irisin as a prognostic/diagnostic biomarker or a therapeutic target.

Physical exercise for a healthy pregnancy: the role of placentokines and exerkines

Complications such as diabetes and preeclampsia can occur during pregnancy. Moderate-intensity exercise can prevent such complications by releasing placentokines and exerkines, such as apelin, adiponectin, leptin, irisin, and chemerin. Exercise and apelin increase thermogenesis and glucose uptake in pregnancy by activating AMPK, PI3K, PGC-1α, AKT1, UCP3, and sarcolipin. Exercise increases apelin levels to reduce preeclampsia symptoms by increasing eNOS, NO, placental growth factor (PlGF), and VEGF and decreasing levels of fms-like tyrosine kinase 1 (sFlt-1), soluble endoglin (sEng), and oxidative stress. A negative relationship has been reported between plasma leptin and VO2peak/kg and VO2peak in women with gestational diabetes. In active women, decreases in leptin levels reduce the risk of preeclampsia by ~ 40%. Higher adiponectin levels are associated with greater physical activity and lead to increased insulin sensitivity. Increased adiponectin levels in preeclampsia and exercise counteract inflammatory and atherogenic activities while also having vascular protective effects. Exercise increases irisin levels that correlate negatively with fasting glucose, insulin concentration, and glycosylated hemoglobin levels. Irisin augments mRNA expression levels of UCP1 and cell death-inducing DNA fragmentation factor-like effector A (cidea) to cause browning of adipose tissue, increased thermogenesis, and increased energy consumption. Irisin concentrations in mothers with preeclampsia in the third trimester negatively correlate with systolic and diastolic blood pressure. Expression levels of chemerin, IL-6, and TNF-α are increased in gestational diabetes, and the increases in chemerin in late pregnancy positively correlate with the ratio of sFlt-1 to PlGF as a marker of preeclampsia. The effects of physical exercise on placentokines and exerkines in women at various stages of pregnancy remain poorly understood.

The Mother-Child Dyad Adipokine Pattern: A Review of Current Knowledge

An important role in the network of interconnections between the mother and child is played by adipokines, which are adipose tissue hormones engaged in the regulation of metabolism. Alternations of maternal adipokines translate to the worsening of maternal insulin resistance as well as metabolic stress, altered placenta functions, and fetal development, which finally contribute to long-term metabolic unfavorable conditions. This paper is the first to summarize the current state of knowledge concerning the concentrations of individual adipokines in different biological fluids of maternal and cord plasma, newborn/infant plasma, milk, and the placenta, where it highlights the impact of adverse perinatal risk factors, including gestational diabetes mellitus, preeclampsia, intrauterine growth restriction, preterm delivery, and maternal obesity on the adipokine patterns in maternal-infant dyads. The importance of adipokine measurement and relationships in biological fluids during pregnancy and lactation is crucial for public health in the area of prevention of most diet-related metabolic diseases. The review highlights the huge knowledge gap in the field of hormones participating in the energy homeostasis and metabolic pathways during perinatal and postnatal periods in the mother-child dyad. An in-depth characterization is needed to confirm if the adverse outcomes of early developmental programming might be modulated via maternal lifestyle intervention.

Adipokines in Pregnancy: A Systematic Review of Clinical Data

Adipokines are signaling proteins involved in metabolic, endocrinological, vascular and immunogenic processes. Associations of various adipokines with not only insulin resistance but also with increased insulin sensitivity, increased systolic blood pressure, and atherosclerosis highlight the significance of adipokines in several components of metabolic syndrome and metabolic diseases in general. As pregnancy presents a unique metabolic state, the role of adipokines in pregnancy, and even in various pregnancy complications, appears to be key to elucidating these metabolic processes. Many studies in recent years have attempted to clarify the role of adipokines in pregnancy and gestational pathologies. In this review, we aim to investigate the changes in maternal adipokine levels in physiological gestation, as well as the association of adipokines with pregnancy pathologies, such as gestational diabetes mellitus (GDM) and preeclampsia (PE). Furthermore, we will analyze the association of adipokines in both maternal serum and cord blood with parameters of intrauterine growth and various pregnancy outcomes.

Comparison irisin peptide serum level in pregnant women with and without gestational diabetes mellitus: A case-control study

INTRODUCTION

Gestational diabetes mellitus (GDM) is a metabolic disease that affects mother and foetus during pregnancy, causing acute and chronic adverse effects. Irisin is proposed as a novel marker to predict GDM. The aim of this study was to assess the role of irisin peptide serum levels in gestational diabetes and compare with healthy pregnant women.

METHODS

This case-control study was conducted on women at 24 to 34 weeks of gestation in Ghaem Hospital affiliated with Mashhad University of Medical Sciences between May 2016 and June 2019. In two study groups, GDM and non-GDM women, an association between maternal serum irisin levels and clinical and biochemical parameters were evaluated. Maternal serum irisin levels were measured by an enzyme immunoassay method. Body mass index, serum levels of glucose, oral glucose tolerance test (OGTT), insulin, haemoglobin A1C, homeostatic model assessment of insulin resistance (HOMA IR) and irisin were evaluated.

RESULTS

Totally, 56 participants (30 non-GDM women and 26 women with GDM) were enrolled. Not statistically significant was observed in serum irisin levels between GDM and non-GDM women. (p = .814) Irisin levels were not significantly associated with maternal age, systolic and diastolic blood pressure, the number of pregnancies, gestational age, fasting blood sugar, insulin, HOMA IR, one-hour and two-hour serum glucose and body mass index.

CONCLUSIONS

There is no significant difference between GDM and non-GDM groups in the case of irisin value and later, no association of irisin with metabolic and anthropometric parameters. These findings need to be assessed in future experiments.

The role of exercise-induced myokines in promoting angiogenesis

Ischemic diseases are a major cause of mortality or disability in the clinic. Surgical or medical treatment often has poor effect on patients with tissue and organ ischemia caused by diffuse stenoses. Promoting angiogenesis is undoubtedly an effective method to improve perfusion in ischemic tissues and organs. Although many animal or clinical studies tried to use stem cell transplantation, gene therapy, or cytokines to promote angiogenesis, these methods could not be widely applied in the clinic due to their inconsistent experimental results. However, exercise rehabilitation has been written into many authoritative guidelines in the treatment of ischemic diseases. The function of exercise in promoting angiogenesis relies on the regulation of blood glucose and lipids, as well as cytokines that secreted by skeletal muscle, which are termed as myokines, during exercise. Myokines, such as interleukin-6 (IL-6), chemokine ligand (CXCL) family proteins, irisin, follistatin-like protein 1 (FSTL1), and insulin-like growth factor-1 (IGF-1), have been found to be closely related to the expression and function of angiogenesis-related factors and angiogenesis in both animal and clinical experiments, suggesting that myokines may become a new molecular target to promote angiogenesis and treat ischemic diseases. The aim of this review is to show current research progress regarding the mechanism how exercise and exercise-induced myokines promote angiogenesis. In addition, the limitation and prospect of researches on the roles of exercise-induced myokines in angiogenesis are also discussed. We hope this review could provide theoretical basis for the future mechanism studies and the development of new strategies for treating ischemic diseases.

Changes of Circulating Irisin and High-Sensitivity C-Reactive Protein Levels in Morbidly Obese Individuals with Type 2 Diabetes After Roux-en-Y Gastric Bypass

Background: Irisin has been recently reported to provide beneficial effects in obesity and diabetes. Elevation of high-sensitivity C-reactive protein (hs-CRP) reflects the inflammatory state that has been shown to play a key role in obesity and its comorbidities. Objective: Our study aimed to compare the changes of circulating irisin levels in an obese diabetic population who underwent laparoscopic Roux-en-Y gastric bypass (LRYGB) versus a control-matched population who underwent usual medical care plus diabetes support education (DSE) program. In addition, we aimed to explore the association between circulating irisin and hs-CRP levels after the interventions. Methods: In a prospective controlled trial, we studied 58 obese individuals with type 2 diabetes before and 12 months after intervention. Twenty-nine subjects underwent LRYGB and 29 subjects received DSE. Results: At 12-month follow-up, compared with the DSE group, patients who underwent LRYGB lost more weight (LRYGB; -33.4 ± 11.2, and DSE; 0.2 ± 4.9 kg; P < .001), fat mass (P < .001), and fat-free mass (P < .05). Circulating irisin (P < .05) and hs-CRP level (P < .05) were also significantly lower. Within the LRYGB group, the reduction of irisin level was positively associated with the changes of hs-CRP levels (r = 0.39, P < .05). Conclusions: To the best of our knowledge, this is the first study showing that LRYGB significantly reduces circulating irisin levels compared with usual medical care and DSE, in an obese diabetic population. After LRYGB, the irisin reduction significantly correlates with the reduction of hs-CRP. The elevation of circulating irisin levels suggests irisin resistance in the obese state and its decrease after LRYGB might reflect the resolution of irisin resistance. Future investigations are needed to confirm and explore the mechanisms of irisin resistance in obesity, its resolution after LRYGB, and the pathophysiological significance.

Role of Serum Irisin During Early Pregnancy to Predict The Development of Gestational Diabetes Mellitus at 24-28 Weeks of Pregnancy in high-risk patients

AIMS

The aim of this prospective study was to investigate the role of serum irisin during early pregnancy to predict the development of GDM at 24-28 weeks in high-risk patients.

METHODOLOGY

This study was conducted among the pregnant women attending the Department of Endocrinology and antenatal clinic of Department of Obstetrics and Gynecology of MKCG Medical College for a period of one year with at least one risk factor for the development of gestational diabetes mellitus (GDM). Blood samples were collected for measurement of fasting plasma glucose, serum insulin, serum irisin, lipids (TC, LDL, HDL, TG), and HbA1c. Oral glucose tolerance test was performed using 75 g of glucose during the first trimester and between 24-28 weeks of pregnancy. Patients were diagnosed as GDM based upon IADPSG criteria at 24-28 weeks. Serum irisin, glycemic parameters, and homeostatic model assessment of insulin resistance during first trimester were analyzed for predicting GDM between 24-28 weeks.

RESULTS

Sixty-five patients were included in the study, out of which 20 (30.8%) patients developed GDM and the rest 45 patients had normal glucose tolerance (NGT). The first trimester mean serum irisin concentration was significantly lower in women who later developed GDM compared with women who had NGT (111.65 ± 25.43 μg/L vs 185.89 ± 28.89 μg/L). Serum irisin concentration was the best predictor with an optimal threshold value of 149 μg/L, which had sensitivity, specificity, positive predictive value, and negative predictive value of 90%, 91.1%, 81.8%, 95.3%, respectively, for predicting GDM at 24-28 weeks of pregnancy.

CONCLUSION

We suggest the utility of serum irisin as an early biomarker to predict the development of GDM later in pregnancy in high-risk patients.

Novel Biomolecules in the Pathogenesis of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is one of the most common metabolic diseases in pregnant women. Its early diagnosis seems to have a significant impact on the developing fetus, the course of delivery, and the neonatal period. It may also affect the later stages of child development and subsequent complications in the mother. Therefore, the crux of the matter is to find a biopredictor capable of singling out women at risk of developing GDM as early as the very start of pregnancy. Apart from the well-known molecules with a proven and clear-cut role in the pathogenesis of GDM, e.g., adiponectin and leptin, a potential role of newer biomolecules is also emphasized. Less popular and less known factors with different mechanisms of action include: galectins, growth differentiation factor-15, chemerin, omentin-1, osteocalcin, resistin, visfatin, vaspin, irisin, apelin, fatty acid-binding protein 4 (FABP4), fibroblast growth factor 21, and lipocalin-2. The aim of this review is to present the potential and significance of these 13 less known biomolecules in the pathogenesis of GDM. It seems that high levels of FABP4, low levels of irisin, and high levels of under-carboxylated osteocalcin in the serum of pregnant women can be used as predictive markers in the diagnosis of GDM. Hopefully, future clinical trials will be able to determine which biomolecules have the most potential to predict GDM.

Association between plasma irisin in pregnancy and postpartum glucose levels among Chinese women: A cohort study

AIMS/INTRODUCTION

The association between plasma irisin and glucose levels in the general population is controversial, and few studies have longitudinally detected this correlation. We aimed to examine whether irisin in pregnancy was associated with postpartum glucose levels among Chinese women and explore the modifiable factors.

MATERIALS AND METHODS

We carried out a prospective cohort study in Guangzhou, China, during 2017 and 2018, and 453 pregnant women (20-28 weeks) were enrolled. Plasma irisin levels in pregnancy were tested. At 6-8 weeks after delivery, 93 women with gestational diabetes mellitus (GDM) underwent a 75-g oral glucose tolerance test, and the other 360 women had a fasting blood glucose (FBG) test. Multivariable linear, quantile and logistic regressions were carried out.

RESULTS

The mean plasma irisin in mid-pregnancy was 13.73 ng/mL. We observed a significantly negative association between mid-pregnancy irisin and postpartum FBG (β: -0.056 ± 0.024). However, quantile regression showed the association was only significant in high percentiles of FBG levels (P50 to P95 ), and the magnitude showed an increasing trend. Higher baseline irisin was also associated with a lower risk of postpartum impaired fasting glucose (relative risk 0.563, 95% confidence interval 0.384-0.825). Furthermore, we found significant interactions between irisin and predominant breast-feeding on FBG and impaired fasting glucose (both Pinteraction  < 0.05). In women with GDM, baseline irisin was non-significantly associated with postpartum postprandial 2-h glucose levels (β: -0.305 ± 0.160, P = 0.061).

CONCLUSIONS

Plasma irisin levels in mid-pregnancy were negatively associated with FBG levels and impaired fasting glucose at 6-8 weeks postpartum among Chinese women, and stronger associations were observed in women with higher FBG values. Furthermore, breast-feeding might modify this relationship.

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.

Prenatal exercise in fetal development: a placental perspective

Maternal obesity (MO) and gestational diabetes mellitus (GDM) are common in Western societies, which impair fetal development and predispose offspring to metabolic dysfunction. Placenta is the organ linking the mother to her fetus, and MO suppresses the development of vascular system and expression of nutrient transporters in placenta, thereby affecting fetal development. For maintaining its proper physiological function, placenta is energy demanding, which is met through extensive oxidative phosphorylation. However, the oxidative capacity of placenta is suppressed due to MO and GDM. Recently, several studies showed that physical activity during pregnancy enhances oxidative metabolism and improves placental function, which might be partially mediated by exerkines, referring to cytokines elicited by exercise. In addition, as an endocrine organ, placenta secretes cytokines, termed placentokines, including apelin, superoxide dismutase 3, irisin, and adiponectin, which mediate fetal development and maternal metabolism. Possible molecular mechanisms linking maternal exercise and placentokines to placental and fetal development are further discussed. As an emerging field, up to now, available studies are limited, mostly conducted in rodents. Given the epidemics of obesity and metabolic disorders, as well as the prevalence of maternal sedentary lifestyle, the effects of exercise of pregnant women on placental function and placentokine secretion, as well as their impacts on fetal development, need to be further examined.

Circulating Myonectin and Irisin Levels in Gestational Diabetes Mellitus - A Case-control Study

OBJECTIVE

The objective of this study was to assess the levels of serum myonectin and irisin in pregnant women with and without gestational diabetes mellitus (GDM).

METHOD

A total of 80 pregnant women participated in our study (which consisted of 40 patients with GDM, 40 participants as the control group). Myonectin and irisin levels were analyzed through the ELISA technique, in addition to metabolic parameters in the serum samples of the participants.

RESULTS

It was found that the levels of irisin and myonectin were lower in the GDM group compared to the control group. Moreover, it was determined that the values of age (p<0.001), body mass index (p=0.001), gravida (p=0.001), parity (p = 0.016), fasting serum glucose (p=0.001), fasting serum insulin (p=0.007), postprandial serum glucose (p=0.006), HbA1c (p<0.001), HOMA-IR (p<0.001) were higher; HDL cholesterol (p<0.001) was lower. Insulin resistance was significantly higher in the GDM group.

CONCLUSIONS

Levels of myonectin and irisin were determined to be low in the GDM group. Our results have demonstrated that myonectin and irisin could play a role in the development of GDM and that irisin as well as myonectin could be a novel biomarker for GDM.

Neurological consequences of exercise during prenatal Zika virus exposure to mice pups

PURPOSE/AIM

Zika virus (ZIKV) infection during the pregnancy period is related to microcephaly and neurobehavioral disorders at birth, while prenatal exercise is supposed to provide neuroprotection in newborns pups. The aim of this study was to investigate the neurological consequences of exercise during prenatal ZIKV exposure to mice pups.

MATERIAL AND METHODS

Twelve weeks female mice were randomly assigned into three groups: Control group, intraperitoneally injected with saline (Control); untrained group, intraperitoneally injected with ZIKV (ZIKV); and trained group, intraperitoneally injected with ZIKV (ZIKV/swim). There was one familiarization week prior to the beginning of the swimming training. Dams swam for 60 min/session, 5 days/week, during 4 weeks. Mating occurred between the fifth and seventh day of the first week of the swimming training. ZIKV 10⁶ plaque-forming units/100 µl (10⁶ PFUs/100 µl) or an equal volume of saline was intraperitoneally injected in the pregnant mice at embryonic day 10.5. Pup's body mass and brain weight were measured at postnatal day 1 (P1). Behavioral tests were performed from P30 to P35. Thereafter, hippocampal levels of syntaxin-1, GFAP, IBA-1, and BDNF were measured.

RESULTS

Exercise during prenatal ZIKV exposure prevented brain atrophy, development of depression, anxiety, and disruption of social behavior. Exercise during prenatal ZIKV exposure inhibited the overexpression of microglia (IBA-1) and astrocytes (GFAP), with reduction of BDNF levels in the hippocampi of female and male mice pups. No significant changes were seen in syntaxin-1 levels.

CONCLUSION

Our findings reveal beneficial effects of exercise during pregnancy exposure to ZIKV in mice pups.

Irisin level and neonatal birthweight: A systematic review and meta-analysis

Irisin is an important crosstalk myokine between adipose and muscle tissue. Disorders in irisin secretion can lead to fetal growth abnormalities and even lead to metabolic syndromes in adult life. This study aimed to evaluate the association between irisin level in umbilical cord blood and maternal serum with neonatal birthweight. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement and the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline were followed. A comprehensive search of eight databases (PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, CBM, CNKI, WANFANG and VIP) was performed from inception to November 2019. Studies with original date reporting irisin levels in newborns of small for gestational age (SGA) and newborns of large for gestational age (LGA) were included. Additionally, studies reporting correlation coefficients of irisin with birthweight were analyzed. Newcastle-Ottawa score system and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach were applied. Seventeen studies with 1866 participants were included. Pooled analysis indicated decreased cord irisin levels in SGA newborns (MD -10.57, 95 % CI -13.41 to -7.73) and increased irisin levels in LGA newborns (MD 3.80, 95 % CI 1.91-5.70). Umbilical cord irisin level was positively correlated with neonatal birthweight (r = 0.41 95 %CI 0.04 to 0.68). The pooled correlation coefficient of maternal serum irisin with birthweight has no statistical significance. This meta-analysis suggested that the umbilical cord irisin levels were impaired in fetal growth abnormalities. Umbilical cord blood irisin level was positively correlated with birthweight.

Association between plasma irisin and glucose metabolism in pregnant women is modified by dietary n-3 polyunsaturated fatty acid intake

AIMS/INTRODUCTION

The role of irisin in maternal glucose metabolism and how it would respond to dietary n-3 polyunsaturated fatty acid (n-3 PUFA) intake remains unclear. This study aimed to explore whether maternal plasma irisin is associated with glucose metabolism and whether this association is modified by dietary n-3 PUFA.

MATERIALS AND METHODS

A total of 932 pregnant women (20-28 weeks' gestation) aged 20-45 years were recruited. Dietary n-3 PUFA was estimated using a validated quantitative food frequency questionnaire. Plasma irisin and insulin were tested by enzyme-linked immunosorbent assay, and insulin resistance (IR) was estimated using the homeostatic model assessment (HOMA). Gestational diabetes mellitus was diagnosed with a 75-g oral glucose tolerance test. Adjusted multivariable linear regression and logistic regression were carried out to examine the associations between plasma irisin and glucose metabolism. The moderating effect of dietary n-3 PUFA intake was determined by fully multiplicative models by including the interaction term.

RESULTS

Maternal plasma irisin was negatively associated with HOMA-IR and oral glucose tolerance test 0 h glucose level (β -0.250, -0.067; corrected P-value for false discovery rate = 0.012, 0.018, respectively), positively associated with HOMA of insulin sensitivity (β 0.028; corrected P-value for false discovery rate = 0.012), but not associated with postprandial glucose or the risk of gestational diabetes mellitus. Furthermore, we found a moderating effect of dietary n-3 PUFA on the relationships of plasma irisin with HOMA-IR and HOMA of insulin sensitivity; these associations were strengthened with increased n-3 PUFA intake (β -0.037, 0.004; P = 0.014, 0.041, respectively).

CONCLUSIONS

Plasma irisin was negatively associated with HOMA-IR and fasting glucose, whereas it was positively associated with HOMA of insulin sensitivity in pregnant women. We first showed that these associations were modified by dietary n-3 PUFA intake.

Placental Regulation of Energy Homeostasis During Human Pregnancy

Successful pregnancies rely on sufficient energy and nutrient supply, which require the mother to metabolically adapt to support fetal needs. The placenta has a critical role in this process, as this specialized organ produces hormones and peptides that regulate fetal and maternal metabolism. The ability for the mother to metabolically adapt to support the fetus depends on maternal prepregnancy health. Two-thirds of pregnancies in the United States involve obese or overweight women at the time of conception. This poses significant risks for the infant and mother by disrupting metabolic changes that would normally occur during pregnancy. Despite well characterized functions of placental hormones, there is scarce knowledge surrounding placental endocrine regulation of maternal metabolic trends in pathological pregnancies. In this review, we discuss current efforts to close this gap of knowledge and highlight areas where more research is needed. As the intrauterine environment predetermines the health and wellbeing of the offspring in later life, adequate metabolic control is essential for a successful pregnancy outcome. Understanding how placental hormones contribute to aberrant metabolic adaptations in pathological pregnancies may unveil disease mechanisms and provide methods for better identification and treatment. Studies discussed in this review were identified through PubMed searches between the years of 1966 to the present. We investigated studies of normal pregnancy and metabolic disorders in pregnancy that focused on energy requirements during pregnancy, endocrine regulation of glucose metabolism and insulin resistance, cholesterol and lipid metabolism, and placental hormone regulation.

Maternal and umbilical cord blood subfatin and spexin levels in patients with gestational diabetes mellitus

Subfatin and spexin are two novel adipokines implicated in glucose homeostasis. This study was designed to investigate changes in blood subfatin and spexin levels during gestational diabetes mellitus (GDM) and childbirth, and define the mechanisms of these hormones in the physiopathology of GDM. A total of 60 pregnant women, comprising 30 diagnosed with GDM and 30 with normal gestation, were included in the study. The diagnosis of GDM was made through a 75-g oral glucose tolerance test (OGTT) administered between 24 and 28 weeks of pregnancy. The amounts of subfatin, spexin, and insulin were measured in blood samples by enzyme-linked immunosorbent assays; lipid profiles, glucose, and other biochemical parameters were measured by using an autoanalyzer. Levels of subfatin and spexin were significantly higher in blood samples drawn at baseline (before OGTT) in mothers with GDM compared to those with normal gestation. Similar observations were made in maternal and cord blood sampled at the end of pregnancy. However, at delivery, the increase in subfatin and spexin concentrations observed at baseline was abrogated in both groups of pregnant women, although levels in mothers with GDM were comparatively higher. These results show that levels of subfatin and spexin increased because of GDM and suggest that these hormones could be potential biomarkers for the diagnosis and management of GDM.

Serum irisin levels as a potential marker for diagnosis of gestational diabetes mellitus

OBJECTIVES

The aim of this study was to compare serum irisin, trace elements (Zn, Cu, Mg) levels between the group of pregnant women with gestational diabetes mellitus (GDM) and healthy pregnant group.

MATERIAL AND METHODS

Sixty pregnant women with GDM and 30 healthy pregnant women. The two groups were matched for maternal age, gestational age. Maternal serum irisin levels were measured by enzyme-linked immunosorbent assay kit at 24-28 weeks of gestation. An association between maternal serum irisin levels and clinical and biochemical parameters was evaluated. Body mass index, serum levels of glucose, OGTT, insulin, HbA1C, HOMA IR, HOMAβ, Hb%, and irisin were investigated and analyzed in the study group and controls.

RESULTS

Pregnant women with GDM had significantly higher fasting blood glucose FBG (p = 0.004), first-houEr OGTT glucose (p = 0.001), second-hour OGTT glucose (p = 0.001), fasting insulin FI (p = 0.001) levels, HOMA IR (p = 0.001), HOMAβ (p = 0.001), HbA1C(p = 0.001), Hb% (p = 0.017), as compared to controls. serum irisin levels were significantly lower (p =0.001) in women subsequently developed GDM (mean ± SD =71.65±8.03) than healthy pregnant controls (mean ± SD 136.54±22.56). Correlation analysis between irisin levels and anthropometric and biochemical parameters in patients with gestational diabetes revealed that none of the investigated parameters correlated with serum irisin level.

CONCLUSIONS

The present results suggest that serum irisin levels might presented as a novel marker for GDM, with decreased levels of irisin being symptomatic of GDM.

A systematic review of the association of neuregulin 4, a brown fat-enriched secreted factor, with obesity and related metabolic disturbances

Neuregulin 4 (Nrg4), a novel brown fat-enriched hormone, plays a key role in the modulation of glucose and lipid metabolism and energy balance. Recent data have demonstrated that the expression of Nrg4 is substantially down-regulated in mouse and human obesity, making its regulatory aspect intriguing. Because of the close relationship between Nrg4, obesity, and associated metabolic diseases, this systematic review aimed to assess the association of Nrg4 with obesity and related metabolic disturbances, emphasizing its possible mechanisms of action in these disorders. We searched PubMed/Medline, ScienceDirect, Scopus, EMBASE, ProQuest, and Google Scholar up until June 2019. The evidence reviewed here indicates that Nrg4 may contribute to the prevention of obesity and related metabolic complications by elevating brown adipose tissue activity, increasing the expression of thermogenic markers, decreasing the expression of lipogenic/adipogenic genes, exacerbating white adipose tissue browning, increasing the number of brite/beige adipocytes, promoting hepatic fat oxidation and ketogenesis, inducing neurite outgrowth, enhancing blood vessels in adipose tissue, increasing the circulatory levels of healthy adipokines, and improving glucose homeostasis. Thus, Nrg4 appears to be a novel therapeutic strategy for the treatment of obesity and associated metabolic complications. However, prospective cohort studies are warranted to confirm these outcomes.

Could serum levels of irisin be used in gestational diabetes predicting?

OBJECTIVE

Gestational diabetes mellitus (GDM) is a metabolic disorder during pregnancy leading to acute and chronic complications in both mother and newborn. The pathogenesis of GDM has not been fully understood, However, since the disease shares risk factors with type 2 diabetes mellitus (T2DM), a relationship between these two disease states is plausible. The recently discovered peptide irisin has been hypothesized to be a regulator of body metabolism. However, studies ended up with controversial results. In the present study, we aimed to investigate the relationship between irisin levels and gestational diabetes mellitus and the possible benefits of the metabolic profile.

MATERIALS AND METHODS

We performed a cross-sectional analysis of circulating levels of irisin in 100 pregnant women similar for age and body mass index and the groups included 50 gestational diabetic patients and 50 healthy pregnant volunteers. Serum irisin levels were measured by ELISA kit.

RESULTS

Mean age and body mass index levels were similar in both groups. Median HbA1c, fasting blood glucose, Glucose 1 h, Glucose 2 h and fasting insülin levels were higher in with gestational diabetic patients compared to the control group. In gestational diabetic group, the median irisin level was lower than in the control group.

CONCLUSION

Serum irisin levels were lower in gestational diabetic patients. Further investigations are needed to explore the underlying biological effects of irisin on pregnant women.

Circulating irisin levels of prenatal and postnatal patients with gestational diabetes mellitus: A systematic review and meta-analysis

AIMS

At present, there are few studies on the relationship between circulating irisin levels and gestational diabetes mellitus (GDM), and the results are inconsistent. Therefore, this study conducts a systematic review and meta-analysis to comprehensively discuss the role of irisin in the occurrence and development of GDM.

METHODS

We searched the articles on the relationship between GDM and circulating irisin levels up to September 2019, using the CNKI, WANFANG-DATA, PubMed and the Web of Science databases.

RESULTS

Twenty two articles including 3563 participants were selected in the meta-analysis. Meta-analysis found the blood irisin levels for GDM group were significantly lower than that for control group during pregnancy(SMD = -0.88, 95%CI: -1.34, -0.42, P < 0.001). However, there was no significant difference of irisin levels in the postpartum blood and cord blood between the two groups (SMD = -1.44, 95 %CI: -3.79, 0.92, P = 0.23; SMD = -0.17, 95 %CI: -0.59, 0.25, P = 0.42, respectively).

CONCLUSIONS

Compared with the control group, irisin levels in the GDM group during pregnancy are lower. However, it is no significant difference of irisin levels in the postpartum blood and cord blood. Irisin may play an important role in the occurrence and development of GDM, which needs further research to demonstrate.

Pathophysiological role of endogenous irisin against tumorigenesis and metastasis: Is it a potential biomarker and therapeutic?

In the last few decades, there has been notable progress in understanding the molecular and cellular basis of the complex process involved in cancer. In this context, tumor-promoting inflammation, dysregulation of apoptotic signaling, tissue invasion and metastasis, and cancer microenvironment have recently attracted interest from researchers. Irisin is a hormone released by muscles during exercise and it directly acts on key functional cells involving energy metabolism and homeostasis. Recently, many studies have reported the anticancer effect of irisin against different types of cancer. Translation of these findings to clinical practice for the diagnosis and treatment of several types of cancer is urgently required. In this review, we summarized preclinical and clinical studies on the anticancer effects of irisin in various types of cancer, and also discussed the mechanisms activated by irisin to suppress cancer pathogenesis. We further discussed the serum level of irisin related to different types of cancer to understand more clearly the association between irisin concentration and tumor burden. This review may serve as a solid foundation for researchers and physicians to support basic and clinical studies on irisin as a promising strategy for early diagnosis and treatment of a various types of cancers.

Comprehensive evaluation of irisin levels in fetomaternal circulation of pregnant women with obesity or gestational diabetes mellitus

AIM

To evaluate maternal and cord blood irisin levels in pregnant women with gestational diabetes mellitus (GDM) and in obese pregnant women without GDM.

METHODS

The study included 109 patients, with 34 patients in the GDM group, 40 in the obese non-GDM group, and 35 in the control group. Maternal serum irisin levels at the time of delivery were measured by an enzyme-linked immunosorbent assay kit. The correlation of serum irisin levels with metabolic parameters and anthropometric measurements was analyzed.

RESULTS

There were significant differences between the study groups in terms of cord arterial, cord venous, and maternal serum irisin levels (P < 0.001, P < 0.01, P < 0.001, respectively). Cord arterial, cord venous, and maternal serum irisin levels were higher in the obese group compared to the control (P < 0.01, P < 0.01, P < 0.01, respectively) and the GDM group (P < 0.001, P < 0.001, P < 0.001, respectively).

CONCLUSION

Elevation in irisin levels of women who have pregnancies complicated with obesity may be explained as part of the compensation mechanism against disturbed metabolic functions. Pregnant individuals with GDM have lower serum irisin levels in comparison to healthy pregnant women. In this regard, it is possible that the measurement of serum irisin levels may be utilized in the future for prediction, prevention, and treatment of GDM.

Skeletal muscle as a protagonist in the pregnancy metabolic syndrome

The pregnant woman normally shows clinical manifestations similar to a metabolic syndrome (MS), due to her metabolic and hemodynamic adaptations in order to share nutrients with the child. If those adjustments are surpassed, a kind of pregnancy MS (PregMS) could appear, characterized by excessive insulin resistance and vascular maladaptation. Skeletal muscle (SKM) must be a protagonist in the PregMS: SKM strength and mass have been associated inversely with MS incidence in non-pregnant patients, and in pregnant women muscular activity modulates metabolic and vascular adaptations that favor better outcomes. Of note, a sedentary lifestyle affects exactly in the other way. Those effects may be explained not only by the old paradigm of SKM being a great energy consumer and store, but because it is an endocrine organ whose chronic activity or deconditioning correspondingly releases myokines modulating insulin sensitivity and cardiovascular adaptation, by direct or indirect mechanisms not well understood. In this document, we present evidence to support the concept of a PregMS and hypothesize on the role of the SKM mass, fiber types composition and myokines in its pathophysiology. Also, we discuss some exercise interventions in pregnancy as a way to test our hypotheses.

Acute Postexercise Change in Circulating Irisin Is Related to More Favorable Lipid Profile in Pregnant Women Attending a Structured Exercise Program and to Less Favorable Lipid Profile in Controls: An Experimental Study with Two Groups

INTRODUCTION

The blood irisin concentrations may be affected both by exercise and pregnancy. We aimed to determine acute responses in serum irisin after a single exercise session and relationships between exercise-induced changes in this hormone and lipid profile in pregnancy.

MATERIAL AND METHODS

It was an experimental study in 20 Caucasian women in normal pregnancy (age 30 ± 3 years, 28 ± 6 weeks of gestation; mean ± SD). Participants were assigned to training (n = 8) and control groups (n = 12). Before the experiment, women from the training group attended a structured exercise program 3 times a week for 6 weeks. Blood samples were collected before and 30 minutes after a single bout of 60-minute moderate- to high-intensity exercise to determine serum levels of irisin, insulin, glucose concentration, and lipid profile.

RESULTS

At baseline, we recorded slightly lower irisin levels in the training group compared to controls (12.2 ± 2.4 and 13.9 ± 3.3 ng · ml^-1, respectively). Only in the training group all women presented increase in irisin levels after exercise (on average by 14%); and this change was statistically significant (p = 0.002). In the controls, we found positive significant relationships between postexercise irisin change and low-density lipoproteins (R = 0.594; p = 0.04) and total cholesterol (R = 0.734; p = 0.006). Surprisingly, in the training group, these relationships were also significant but inverse (R = -0.738 and p = 0.036; R = -0.833 and p = 0.01, respectively).

CONCLUSIONS

Training and control pregnant women responded differently to a single exercise session, both in the postexercise change in irisin and its relationship to the blood lipids. Only in the training group we observed the postexercise increase in irisin, which was related to more favorable lipid profile. Systematic prenatal physical activity may optimize the postexercise irisin response and lipid metabolism regulated by this hormone. Therefore, exercise programs should be promoted in pregnant women and obstetric care providers.

Reduced plasma level of irisin in first trimester as a risk factor for the development of gestational diabetes mellitus

BACKGROUND

The aim of this prospective cohort study was to investigate the association of first trimester irisin concentrations and the subsequent development of gestational diabetes mellitus (GDM).

METHODS

This cohort study was conducted at three maternity centers in China from July 2015 to June 2016. Data for fasting plasma glucose (FPG) and irisin concentrations in the first trimester and one-step GDM screening with 75-g oral glucose tolerance test (OGTT) performed between 24 and 28 weeks of gestation were collected and analyzed.

RESULTS

Plasma from women was available for 1150 women, of whom 135 (11.7%) developed GDM. The median value of irisin in those included women was 141.2 (IQR, 99.4-192.9) ng/ml. In multivariate models comparing the first (Q1), second (Q2) and third (Q3) quartiles against the fourth (Q4) quartile of irisin, levels of irisin in Q1 and Q2 were associated with GDM, and increased risk of GDM by 440% (odds ratios [OR] = 5.40; 95% confidence intervals [CI]: 2.35-11.40) and 283% (OR: 3.83; 95%CI: 1.63-8.01). A model containing known risk factors plus irisin compared with a model containing known risk factors without irisin showed a greater discriminatory ability to predict GDM, the area under the curve (AUC) increased from 0.776 to 0.809. A significant difference in the AUC between the clinical variables alone and the addition of irisin level was observed (difference, 0.034; P = 0.03).

CONCLUSIONS

Reduced plasma levels of irisin in first trimester was associated with the increased risk of GDM and might be useful in identifying women at risk for GDM for early prevention strategies.

Irisin Maternal Plasma and Cord Blood Levels in Mothers with Spontaneous Preterm and Term Delivery

Irisin, an adipomyokine identified in 2012, has been investigated in association with common pregnancy complications, including gestational diabetes mellitus, preeclampsia, and intrauterine growth restriction. The objective of this study is to examine the potential role of irisin in preterm birth (PTB) by comparing its level between mothers with term and preterm labor. Maternal peripheral blood and cord blood samples were collected from 30 mothers who delivered prematurely and from 35 mothers who delivered at term. Irisin concentrations were measured in all samples using ELISA, and four common single nucleotide polymorphisms in the irisin gene were determined (rs16835198, rs726344, rs3480, and rs1746661). Univariable and multivariable regression modeling was applied to evaluate maternal and cord blood irisin concentrations in relation to preterm/term labor. Irisin concentration in umbilical cord blood was found to be associated with PTB in the univariable model (p = 0.046). On the other hand, no differences in maternal blood irisin levels between mothers with preterm and term deliveries were established. To the best of our knowledge, this is the first study determining irisin levels in term and preterm deliveries in maternal peripheral blood and umbilical cord blood. Our study shows a possible association between cord blood irisin concentration and PTB occurrence.

Colostrum and mature breast milk analysis of serum irisin and sterol regulatory element-binding proteins-1c in gestational diabetes mellitus

Background: We aimed to evaluate irisin and SREBP-1c levels in serum, colostrum and mature breast milk in women with and without gestational diabetes (GDM); and to relate them with maternal glucose, lipid profile and weight status of babies. Methods: GDM positive women (n = 33) and normal glucose tolerant women (NGT) (n = 33) were recruited. Maternal blood samples were collected at 28th week of gestation and later at 6-week post-partum while breast milk samples of the lactating mothers were collected within 72 hours of birth (colostrum) and at 6 weeks post-partum (mature milk). Irisin and SREBP-1c levels were analyzed by commercially available ELISA kits for all maternal samples. Results: Lower levels of irisin were seen in serum, colostrum and mature breast milk of GDM females (p < .01). SREBP-1c profile showed a similar trend of low serum levels in GDM, however, they were undetectable in colostrum and mature breast milk. Weak to moderate correlations of serum irisin with BMI (r = 0.439; p < .001), GTT 0 hours (r = 0.403; p = .01), HbA1c (r = -0.312; p = .011), Fasting blood glucose (r = 0.992; p = .008), and baby weight at birth (r = 0.486; p < .001). Colostrum and mature breast milk irisin showed positive associations with baby weight at 6 weeks (r = 0.325; p = .017; r = 0.296; p = .022, respectively). Serum SREBP-1c at 6 weeks correlated with random blood glucose (r = 0.318; p = .009), and HbA1c (r= -0.292; p = .011). All correlations were lost once we adjusted for maternal BMI. Conclusions: Low irisin and SREBP1-c levels may favor development of GDM in pregnant subjects. Further, low mature breast milk levels may act as a continued stressor from fetal to infant life as long as breast-feeding is continued. Further studies are required to identify the mechanistic relationship between these biomarkers and GDM.

Irisin in metabolic diseases

INTRODUCTION

Irisin is a myokine/adipokine induced by the exercise in mice and humans, which is proposed to induce "browning" of white adipose tissue, its primary target, thus increasing thermogenesis and energy expenditure. Since its identification, irisin has been linked to favorable effects on metabolic diseases, including obesity, type 2 diabetes mellitus (T2DM), lipid metabolism and cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS), and metabolic bone diseases. Generally, despite the promising profile of irisin in rodents, its effects on human are less recognized.

REVIEW

Most, but not all studies show a positive association between irisin and indices of adiposity. In T2DM, NAFLD, and CVD, most observational studies reported lower irisin levels in patients than controls. Regarding metabolic bone diseases, irisin is positively associated with bone mineral density and strength in athletes, and inversely associated with osteoporotic fractures in postmenopausal osteoporosis. In PCOS, data remain largely conflicting. Irisin does not seem to be further reduced when two metabolic diseases, e.g., T2DM and NAFLD, or obesity and NAFLD exist though more data are needed. Furthermore, it seems that diverse confounders may have affected the results of different clinical studies.

CONCLUSION

Irisin remains an appealing molecule from a pathophysiological point of view and an appealing therapeutic target for metabolic diseases, albeit much research is still needed.

Irisin a Novel Metabolic Biomarker: Present Knowledge and Future Directions

The rising prevalence of chronic diseases such as type 2 diabetes and cardiovascular diseases owing to fat mass excess has been described. In recent years, muscle function/dysfunction has become relevant in metabolic homeostasis. Irisin was described as an exercise-induced myokine. It is the product of type I membrane protein cleavage encoded by the fibronectin type III domain containing 5 (FNDC5) gene. The main beneficial function attributable to irisin is the change of subcutaneous and visceral adipose tissue into brown adipose tissue, with a consequential increase in thermogenesis. Irisin has also been described as a hormone that may have a key role in glucose homeostasis. The way the association of type 2 diabetes with obesity occurs is not fully understood. In recent years, the possible pathways through which irisin could interact with other organs such as the brain or bone have been described. The present paper intends to review the new findings and possible new directions in irisin research.

The Exercise-Induced Irisin Is Associated with Improved Levels of Glucose Homeostasis Markers in Pregnant Women Participating in 8-Week Prenatal Group Fitness Program: A Pilot Study

Background

Both exercise and pregnancy influence serum irisin concentration.

Aim

To determine how the interaction of pregnancy and exercise affects irisin level and whether various patterns of exercise adherence had different effect on irisin concentration.

Methods

It was a one-group pretest-posttest study among 9 Caucasian nulliparous healthy women in normal pregnancy (age 23 ± 3 years, 21 ± 2 weeks of gestation; mean ± SD) who participated in 8-week group fitness program. Before and after exercise intervention, we determined serum concentrations of irisin and selected parameters of lipid profile and glucose homeostasis markers.

Results

In active women, irisin slightly decreased with the development of pregnancy. After 8 weeks of exercising, irisin correlated negatively with fasting glucose (R = -0.922; p = 0.001), glycated hemoglobin (R = -0.784; p = 0.012), and insulin concentrations (R = -0.845; p = 0.004). In women exercising below recommended level, we observed a significant drop in irisin concentration, whereas in women exercising at least three times a week this myokine slightly increased (31% difference; 90% confidence limits ±28; a large, clear effect).

Conclusions

Irisin stimulated by prenatal exercise may improve glucose homeostasis markers in healthy women and compensate for metabolic changes induced by pregnancy. Moreover, the frequency of exercise may regulate the changes in exercise-induced irisin concentration.

Irisin stimulates cell proliferation and invasion by targeting the PI3K/AKT pathway in human hepatocellular carcinoma

Irisin is a newly identified myokine that may be cancer-associated, and its impact on liver cancer is unclear. To understand the roles of irisin in liver cancer, we investigated its effect in HepG2 and SMCC7721 hepatocellular carcinoma cells, and the underlying mechanisms. We determined irisin levels in liver tissues and serum samples obtained from patients by using real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Irisin levels in cancerous livers were significantly upregulated compared with those in control livers, but serum irisin levels remained unchanged. Additionally, we evaluated the effects of different concentrations of human recombinant modified and active (glycosylated) irisin (IM) or human recombinant nonmodified irisin (INM) on cell migration, proliferation, viability, and invasiveness. CCK8, transwell, and scratching assays demonstrated that irisin significantly increased cell proliferation, invasion, and migration through activation of the PI3K/AKT pathway. Irisin-induced cell proliferation, migration, and invasion were blocked by a PI3K inhibitor (LY294002). Irisin also decreased the cytotoxicity of doxorubicin in HepG2 cells. These data indicate that increased irisin levels may have protective roles in liver cancer cells through partial activation of the PI3K/AKT pathway, which may facilitate liver cancer progression and decrease the sensitivity to chemotherapy.

The brown-fat-secreted adipokine neuregulin 4 is decreased in gestational diabetes mellitus

AIMS

Neuregulin 4 has recently been recognized as a novel adipokine secreted by brown adipose tissue (BAT), with beneficial effects on murine insulin resistance and hepatic steatosis. Yet, thus far, neither regulation of neuregulin 4 in gestational diabetes mellitus (GDM) nor its longitudinal changes in the peripartum period have been elucidated.

METHODS

Circulating neuregulin 4 levels were measured by ELISA in 74 women with GDM and 74 healthy, gestational-age-matched controls. Also, neuregulin 4 was quantified during pregnancy and compared with postpartum levels in a follow-up study of 25 women with previous GDM and 25 healthy control women.

RESULTS

Women with GDM had lower median serum levels of the novel BAT-secreted adipokine neuregulin 4 (3.0μg/L) compared with healthy (non-GDM) pregnant controls (3.5μg/L; P=0.020), and the area under the glucose curve (AUC_Glucose) was an independent and negative predictor of circulating neuregulin 4 (P=0.033). Also, median postpartum serum concentrations of neuregulin 4 (3.2μg/L) were not significantly different from prepartum levels (2.8μg/L; P=0.328). In addition, neuregulin 4 was positively and independently associated with irisin (P=0.009), but not other BAT-secreted adipokines.

CONCLUSION/INTERPRETATION

Women with GDM have significantly lower circulating neuregulin 4 levels compared with healthy pregnant controls, and the AUC_Glucose is negatively and independently associated with neuregulin 4 during pregnancy. Neuregulin 4 is positively correlated with irisin during pregnancy, as well as in a longitudinal fashion. Future studies are now needed to better elucidate the precise pathomechanisms of the regulation of BAT-secreted adipokines during pregnancy.

New insights into the effects of irisin levels in HIV-infected subjects: correlation with adiposity, fat-free mass, and strength parameters

OBJECTIVE

Patients infected with the human immunodeficiency virus (HIV) have an increased risk of metabolic disorders and alterations on irisin levels. Therefore, the purpose of the current investigation was to quantify the circulating irisin concentration in HIV-infected subjects under highly active antiretroviral therapy and to determine possible correlations between irisin levels with fat mass, fat-free mass, body mass index (BMI), and muscle strength.

SUBJECTS AND METHODS

Cross-sectional study of 10 men (36.7 ± 11.3 years) and 10 women (42.5 ± 10.3 years) infected with HIV, recruited from the Specialized Service Center in the State Center of Reference for High and Medium Complexity. Blood samples were collected to determine plasma irisin levels, glucose, HDL, total cholesterol, triglycerides, and LDL. Body composition (fat mass, fat-free mass) and anthropometrics (body mass index; BMI) were measured by bioelectrical impedance. Muscle strength was assessed using a mechanic hand dynamometer and one maximum repetition tests.

RESULTS

Irisin levels correlated positively with fat mass (r = 0.67; p = 0.001) and BMI (r = 0.48; p = 0.036). In contrast, there was an inverse correlation between irisin levels and fat-free mass (r = -0.41; p = 0.008) and five strength parameters: right hand grip (r = -0.46; p = 0.044); left hand grip (r = -0.50; p = 0.027), relative hand grip (r = -0.79; p = 0.001), bench press (r = -0.58; p = 0.009), leg press (r = -0.40; p = 0.085), and biceps curl (r = -0.059; p = 0.009).

CONCLUSION

Irisin levels correlated positively with body fat and negatively with fat-free mass and strength parameters in HIV-infected patients. Female patients infected with HIV receiving highly active antiretroviral therapy have higher levels of irisin compared with men in a similar circumstance.

Role of serum levels of irisin and oxidative stress markers in pregnant women with and without gestational diabetes

Irisin regulates glucose levels, lipid levels, insulin sensitivity, and low-grade inflammation. Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy, and is associated with increased rates of perinatal problems. Oxidative stress biomarkers have a role in the pathogenesis of patients with GDM. In total, 94 patients were included in our study including 46 control patients and 48 patients with GDM. Fasting blood glucose, HOMA-IR, total oxidative stress (TOS), irisin, and oxidative stress index (OSI) levels of the patients were measured. Serum OGTT, OSI, irisin HOMA, TOS, and insulin levels were statistically significantly higher in the patient group than in the control group. This was the first study to investigate the relation between serum irisin levels and oxidative stress markers in patients with GDM. The results revealed that irisin is an oxidative stress marker and a metabolic protective hormone.

Regulation of the novel adipokines/ hepatokines fetuin A and fetuin B in gestational diabetes mellitus

OBJECTIVE

Fetuin B has recently been introduced as a novel adipokine/hepatokine which is significantly increased in hepatic steatosis and mediates impaired insulin action, as well as glucose intolerance. However, regulation of fetuin B in gestational diabetes mellitus (GDM), as well as its longitudinal changes in the peripartum period, have not been elucidated, so far.

DESIGN AND METHODS

Circulating fetuin A and fetuin B were quantified in 74 women with GDM and 74 healthy and gestational age-matched controls by enzyme-linked immunosorbent assay during pregnancy (median gestational age: 201days). Furthermore, fetuin B was quantified during pregnancy as compared to postpartum levels in a follow-up study (median time after delivery: 4years and 115days).

RESULTS

Median [interquartile range] serum fetuin B levels were significantly higher in women with GDM (4.8 [1.7] mg/l) as compared to non-diabetic pregnant controls (4.3 [1.2] mg/l) (p=0.013) during pregnancy. In multivariate analysis, GDM status, insulin resistance, and fetuin A were independent and positive predictors of circulating fetuin B. Furthermore, fetuin B serum concentrations significantly decreased after delivery from 4.6 [1.7] mg/l (prepartum) to 3.0 [2.2] mg/l (postpartum) in all women (p<0.001).

CONCLUSIONS

Women with GDM have significantly higher fetuin B levels as compared to healthy pregnant control women and GDM status, insulin resistance, and fetuin A positively predict circulating fetuin B. Postpartum fetuin B is decreased as compared to prepartum values suggesting a placental co-secretion of this novel adipokine/hepatokine. Further studies need to elucidate factors contributing to fetuin B regulation in humans, as well as the pathophysiological significance of fetuin B upregulation in GDM.

Relationship between Irisin Concentration and Serum Cytokines in Mother and Newborn

Introduction

Irisin is considered to be a myokine and adipokine that may also participate in reproductive functions, as it increases significantly throughout pregnancy. However, the regulation of circulating irisin and its relationship with other cytokines has not been assessed thus far in pregnant women and their offspring.

Objective

The aim of this study was to evaluate differences in irisin and cytokine concentrations between women at the end of pregnancy and their offspring, as well as the relationship between maternal and newborn irisin and maternal and newborn biomarkers.

Methods

Twenty-eight mother/newborn pairs were included in this study. The following biomarkers were evaluated in maternal venous and arterial umbilical cord blood samples: irisin, 27 cytokine panel, total antioxidant capacity (TAC), total plasma protein, and free fatty acid concentration.

Results

The newborns had significantly lower irisin concentrations compared to their mothers (p = 0.03), but this difference was present only in babies born from mothers without labor prior to cesarean section delivery (p = 0.01). No significant differences in maternal and newborn irisin concentrations were found between diabetic and non-diabetic mothers or between overweight/obese and normal weight mothers. A significant positive correlation was found between TAC level and irisin concentration in newborns. Maternal and newborn interleukin (IL)-1β, IL-1RA, IL-5, IL-7, and interferon gamma-induced protein (IP)-10 levels were significantly positively correlated with irisin concentrations in both study groups. In addition, maternal IL1β, IL-5, IL-7, and IP-10 levels positively predicted maternal irisin concentrations. Furthermore, arterial cord blood TAC and IL-1β and IL1-RA levels positively predicted newborn irisin concentrations. Multiple regression analyses showed that maternal IL-13 negatively predicted offspring irisin levels (p = 0.03) and that maternal IL-1β positively predicted newborn irisin concentrations (p = 0.046).

Conclusion

No evidence was found that serum irisin concentrations in mothers at pregnancy termination or those of their newborns correlated with maternal body mass index, the presence of diabetes mellitus, or free fatty acid levels. However, the results of this study indicated that cytokines might predict irisin concentration in mothers and their offspring, although interactions between irisin levels during pregnancy and the newborn have not yet been fully elucidated.

Evaluation of cord blood irisin levels in term newborns with small gestational age and appropriate gestational age

Background

Most recently, a novel myokine, named irisin, was identified in human that expressed by skeletal muscle after exercise. Irisin increases energy expenditure by turning white adipose tissue into brown adipose tissue. Thus improves carbohydrate homeostasis in humans. Irisin is considered as a potential biomarker for obesity and metabolic syndrome. In recent years, numerous studies have been conducted about irisin with adults, although number of studies with newborns is limited.

Objective

To evaluate cord blood irisin level with small gestational age (SGA) and appropriate gestational age (AGA) in term newborns.

Methods

A cross-sectional study of 34 AGA and 34 SGA term newborns who were born in (1–30) December 2015 in Fatih University Hospital. Estimated fetal weight were calculated using the Hadlock formula by gynecologists to pregnant women in second trimester. All the babies were classified at birth as SGA or AGA. SGA was defined according to the Lubchenco scale for gender and gestational age. We collected umbilical cord blood at the time of delivery. Cord blood irisin levels were measured using commercial enzyme-linked immunosorbent assays in our hospital laboratory.

Results

Cord blood irisin levels were significantly lower in SGA group [median 30 (25 ± 8) ng/ml] than in AGA group [median 40 (39 ± 13) ng/ml, p < 0.001]. No statistically significant differences were observed among the groups in terms of the demographic features (gender, mode of delivery, gestational weeks, 1–5 min Apgar score) (p > 0.05). Mothers with gestational diabetes, hypertension, asthma, chronic disease, use of drug or a history of smoking exposure were excluded from the study. When the study data were evaluated, Yates Continuity Correction and Fisher’s exact tests were used in descriptive statistical methods and for comparison of qualitative data.

Conclusion

Our results support the idea that irisin have a physiologic role in neonates. Low level of irisin is associated with the impaired carbohydrate metabolism in term infants with SGA. However, further studies with larger series are warranted to confirm this.

The relationships of irisin with bone mineral density and body composition in PCOS patients

OBJECTIVE

Our study aims to assay the irisin level and investigate the relationships of irisin level with body mass index (BMI), body composition and bone metabolism in the polycystic ovary syndrome (PCOS) and control women.

METHODS

Fifty two PCOS and 39 control women were recruited. Serum sex hormone, fasting insulin and C-peptide were tested. Fasting serum irisin and adiponectin were measured with enzyme-linked immunosorbent assay. Body composition and bone mineral density were assayed by dual energy X-ray absorptiometry.

RESULTS

Polycystic ovary syndrome women showed different body compositions compared with controls. Serum irisin level of PCOS did not show significant difference compared with controls although it was decreased. The level of adiponectin in PCOS patients was significantly reduced. BMI had no correlation with irisin level. It indicated a positive correlation between serum irisin levels and bone mineral density in the control group and a negative correlation in the PCOS group after BMI and age adjusted. Furthermore, total lean mass has a significant effect on irisin concentration in the PCOS group. There are no correlations between adiponection and body compositions and bone mineral density in both groups.

CONCLUSIONS

The abnormal body composition in PCOS may contribute to the circulation irisin. The crosstalk of irisin in different organs was found and may be related to disease development in PCOS.

Relationship between myostatin and irisin in type 2 diabetes mellitus: a compensatory mechanism to an unfavourable metabolic state?

Myostatin and irisin are two myokines related to energy metabolism, acting on skeletal muscle and recently suggested on adipose tissue in mice. However, the exact role of these myokines in humans has not been fully established. Our aim was to evaluate the relationship between serum levels of myostatin and irisin in type 2 diabetes mellitus patients and non-diabetic controls and to explore its links with metabolic parameters. Case-control study including 73 type 2 diabetes mellitus patients and 55 non-diabetic subjects as control group. Circulating myostatin and irisin levels were measured by enzyme-linked immunosorbent assays. Type 2 diabetes mellitus patients showed significantly lower myostatin levels (p = 0.001) and higher irisin levels (p = 0.036) than controls. An inverse relationship was observed between myostatin and irisin levels (p = 0.002). Moreover, in type 2 diabetes mellitus patients, after adjusting by confounder factors, myostatin was negatively related to fasting plasma glucose (p = 0.005) and to triglyceride levels (p = 0.028) while irisin showed a positive association with these variables (p = 0.017 and p = 0.006 respectively). A linear regression analysis showed that irisin and fasting plasma glucose levels were independently associated to myostatin levels and that myostatin and triglyceride levels were independently associated to irisin concentrations in type 2 diabetes mellitus patients. Our results suggest that serum levels of myostatin and irisin are related in patients with type 2 diabetes. Triglyceride and glucose levels could modulate myostatin and irisin concentrations as a compensatory mechanism to improve the metabolic state in these patients although further studies are needed to elucidate whether the action of these myokines represents an adaptative response.

Irisin as an early marker for predicting gestational diabetes mellitus: a prospective study

OBJECTIVE

The objective of this study is to evaluate maternal serum irisin levels in the first and second trimesters of pregnancy in women diagnosed with and without gestational diabetes mellitus (GDM).

METHODS

We performed a prospective, nested case-control study in 258 pregnant women who were enrolled at the time of the first prenatal visit (6-11th weeks of gestation) and followed until delivery. Among the entire population, we selected 20 women who subsequently developed GDM and 30 women with uneventful pregnancies. Blood samples were collected once from each participant at 6-11th weeks of gestation during the fetal viability scan and at 24-28th weeks of gestation during screening for GDM.

RESULTS

In the first trimester, irisin levels were significantly lower in women who later developed GDM (median = 453 ng/mL, range: 257-811 ng/mL) than in controls (median = 721 ng/mL, range: 700-786 ng/mL). In the second trimester, the difference in irisin levels between the GDM group (median = 749 ng/mL; range: 456-910 ng/mL) and controls (median = 757 ng/mL; range: 703-898 ng/mL) was not statistically significant.

CONCLUSIONS

Irisin may be a useful biomarker in early pregnancy to predict the development of GDM.

Cord blood irisin levels are positively correlated with birth weight in newborn infants

BACKGROUND

Irisin is a novel myokine, secreted from skeletal muscle after exercise. Irisin mediates exercise-related energy expenditure by turning white adipose tissue (WAT) into brown adipose tissue (BAT). Thus, irisin is considered as a potential biomarker for obesity and metabolic syndrome. Infants born small for gestational age (SGA) have increased risk for metabolic syndrome. However, the physiologic role of irisin in neonates remains to be studied.

OBJECTIVE

To evaluate the association of umbilical cord blood irisin levels with gestational age and birth weight categories in neonates.

METHODS

A cross-sectional study of 341 newborns, from 26 to 41weeks' gestation. We collected umbilical cord blood and analyzed plasma for irisin by ELISA.

RESULTS

Plasma irisin levels were positively correlated with gestational age (r=0.21, p<0.001), and birth weight Z-score (r=0.18, p<0.001). SGA infants had significantly lower irisin (median [interquartile range] 55.38 [46.56-65.72]ng/mL) compared to appropriate for gestational age infants (64.41 [53.87-76.76]ng/mL) and large for gestational age infants (68.70 [54.78-79.09]ng/mL, p<0.01). The association between SGA and lower irisin remained significant in multivariate analysis independent of gestational age, maternal age, maternal BMI, and gestational diabetes (p=0.03). In singleton infants, irisin was also significantly negatively associated with maternal preeclampsia (p=0.01).

CONCLUSIONS

Our results support the notion that irisin may have a physiologic role in neonates. We speculate that decreased levels of irisin in SGA infants may contribute to the development of catch-up growth and metabolic syndrome later in life.

Cord blood irisin at the extremes of fetal growth

BACKGROUND/AIMS

Irisin, a novel myokine with antiobesity properties, drives brown-fat-like conversion of white adipose tissue, thus increasing energy expenditure and improving glucose tolerance. We aimed to investigate circulating irisin concentrations in large-for-gestational-age (LGA) and intrauterine-growth-restricted (IUGR) fetuses, both associated with metabolic dysregulation and long-term susceptibility to obesity and metabolic syndrome development.

METHODS

Plasma irisin and insulin concentrations were determined by ELISA and IRMA, respectively, in 80 mixed arteriovenous cord blood samples from LGA (n=30), IUGR (n=30) and appropriate-for-gestational-age (AGA, n=20) singleton full-term pregnancies. Fetuses were classified as LGA, IUGR or AGA, based on customized birth-weight standards adjusted for significant determinants of fetal growth.

RESULTS

Fetal irisin concentrations were lower in IUGR cases than AGA controls (p=0.031). Cord blood irisin concentrations were similar in LGA and AGA groups and positively correlated with birth-weight, as well as customized centiles (r=0.245, p=0.029 and r=0.247, p=0.027, respectively). Insulin concentrations were higher in LGA, compared to AGA fetuses (p=0.036). In the LGA group, fetal irisin concentrations positively correlated with fetal insulin concentrations (r=0.374, p=0.042).

CONCLUSIONS

Impaired skeletal muscle metabolism in IUGR fetuses may account for their irisin deficiency, which may be part of the fetal programming process, leading to increased susceptibility to later metabolic syndrome development. Furthermore, irisin down-regulation may predispose IUGR infants to hypothermia at birth, by inducing less "browning" of their adipose tissue and consequently less non-shivering thermogenesis. Irisin upregulation with increasing birth-weight may contribute to a slower fat gain during early infancy ("catch-down"), by promoting higher total energy expenditure. The positive correlation between irisin and insulin in the LGA group may reflect a counterbalance of the documented hyperinsulinemia, which is partly responsible for the excessive fat deposition in the LGA fetus.