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

Irisin as an emerging target in the regulation of reproductive functions in health and disease

Germ cells are highly conserved in the gonads, nurtured to either develop into a gamete or self-renew into a stem cell reserve. Preserving the germ cell pool and protecting the reproductive organs is essential for maintaining an individual's fertility. Several factors, including a sedentary lifestyle, pollutants, hormonal disruption, drugs, and a disease condition, have been shown to impair normal reproductive function. Irisin has recently been identified as an adipomyokine involved in modulating physiological functions based on the body's metabolic status. It is being studied for its role in various functions, including fertility. Findings show the localization of irisin in various parts of the reproductive axis, with the highest levels observed during puberty and pregnancy. This raises questions about its role and function in reproduction. Studies support irisin's role in protecting against disease-induced reproductive abnormalities and infertility. Therefore, the current review focuses on how irisin influences spermatogenesis and ovarian follicular development and plays a significant role in indirectly preserving the germ cell pool by protecting the gonads against oxidative stress and inflammation.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

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.

Association of Plasma Irisin Levels with Circulating Endothelial Microparticles (EMPs) and Endothelial Progenitor Cells (EPCs) in Children Born Prematurely

Prematurity has been linked with endothelial dysfunction in later life. The purpose of this study was to evaluate the association between plasma irisin, an adipomyokine reported to protect the functional integrity of vascular endothelium, and circulating endothelial microparticles (EMPs) and endothelial progenitor cells (EPCs), consisting early biomarkers of endothelial dysfunction, in preterm-born children. We studied 131 prepubertal children; 61 preterm and 70 born at term (controls). Plasma irisin was determined by ELISA. Circulating CD62E(+), CD144(+) and CD31(+)/CD42b(-) EMPs, and CD34(+)/VEGFR-2(+)/CD45(-) and CD34(+)/VEGFR-2(+)/CD45dim EPCs, were determined by flow cytometry. Body mass index, waist-to-hip ratio, neck circumference, systolic and diastolic blood pressure, and biochemical parameters (glucose, lipids, insulin, HOMA-IR) were also evaluated. Plasma irisin was significantly lower (p = 0.001), whereas circulating EMPs and EPCs were higher, in children born prematurely compared to controls. Irisin was recognized as independent predictor for CD144(+) and CD31(+)/CD42b(-) EMPs, CD34(+)/VEGFR-2(+)/CD45(-) and CD34(+)/VEGFR-2(+)/CD45dim EPCs in the total study population, and for CD31(+)/CD42b(-) EMPs in the preterm group. In conclusion, plasma irisin correlates independently with circulating EMP and EPC subpopulations in prepubertal children and in preterm-born ones. Further studies in children will potentially elucidate the link between irisin and the primary stages of prematurity-related endothelial dysfunction.

Circulating Irisin Levels in Preadolescents and Adolescents Born Preterm

INTRODUCTION

Prematurity is associated with increased cardiometabolic risk later in life. The adipomyokine irisin has been acknowledged as a modulator of energy metabolism and insulin sensitivity. The aim of this study was to investigate circulating levels of irisin and their relation to anthropometric measurements and cardiometabolic phenotype in a population of preterm-born children versus full-term-born peers.

METHODS

A total of 160 children (87 born preterm aged 8.1-14.8 years and 73 born full-term of similar age and gender distribution) were studied. Arterial blood pressure, anthropometry, body composition assessments with dual energy X-ray absorptiometry, and skinfold measurements were performed. Blood biochemistry and circulating levels of irisin, insulin, cortisol, leptin, and adiponectin were also determined.

RESULTS

The preterm group had higher diastolic blood pressure, triceps skinfold, subscapular skinfold (SSSF), and abdominal skinfold measurements and more central adiposity than the full-term group. Irisin was significantly lower (p = 0.002), whereas leptin was higher (p = 0.03) in the preterm than the full-term group. Irisin correlated positively with gestational age (r = 0.19, p = 0.01), birth weight (r = 0.23, p = 0.003), and high-density lipoprotein cholesterol (r = 0.20, p = 0.01) and negatively with SSSF (r = -0.25, p = 0.003) and chronological age (r = -0.21, p = 0.008).

CONCLUSION

Lower levels of irisin and a slightly unhealthy adiposity and cardiometabolic pattern were detected in preterm-born children in comparison to their full-term-born peers. Whether low irisin levels in preadolescents and adolescents born prematurely could be of prognostic value for the development of cardiometabolic sequelae later in life remains to be further studied.

Maternal serum irisin levels in normotensive and preeclamptic pregnancies: a systematic review and meta-analysis

BACKGROUND

Altered irisin levels have been reported in pregnancy-associated disorders, such as preeclampsia.

OBJECTIVE

A systematic review and meta-analysis were conducted to evaluate the changes in maternal circulatory irisin levels in preeclampsia as compared to normotensive healthy pregnant controls.

METHODS

Relevant studies were identified by searching PubMed and other databases. Random-effects model was used to obtain standardized mean differences (SMDs) and its 95% confidence intervals (CIs). The sub-group meta-regression analyses were conducted to explore heterogeneity. The presence of publication bias and the study robustness was tested using funnel plot and sensitivity analyses, respectively.

RESULTS

This meta-analysis finally included 14 observations from eight studies. Compared with controls, preeclampsia patients showed significantly decreased serum irisin levels (SMD: -1.13; 95% CI: -1.63 to -0.62, p < .0001). The sub-group analysis showed that this decrease in irisin is regardless of body mass index (BMI) and gestational age of preeclampsia patients. The meta-regression analysis indicated that blood pressure is significantly associated with the observed results. There was no significant publication bias as indicated by the funnel plot analysis followed by Begg's (p = .35) and Egger's tests (p = .39). The sensitivity analysis indicated that no single study had a significant influence on the overall outcome, suggesting the robustness of this meta-analysis.

CONCLUSIONS

This meta-analysis showed significantly decreased maternal serum irisin level in preeclampsia patients as compared to normotensive pregnant women. This study highlights the need for future studies evaluating the diagnostic utilities and associations of irisin with the fetal and neonatal outcomes in preeclampsia.

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.

Hippocampal and Prefrontal Cortical Brain Tissue Levels of Irisin and GDF15 Receptor Subunits in Children

Cold-stress hormones (CSHs) stimulate thermogenesis and have direct neuroprotective effects on the brain. The obligatory receptor components of two new CSHs (irisin and growth differentiation factor-15 [GDF15]) were recently discovered. Irisin binds integrin-αV/β5 heterodimers while GDF-15 binds to the orphan receptor glial cell-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL). In addition, integrin-αV/β5 was just identified as the key receptor mediating Zika virus infection in the CNS. We measured integrin-αV, integrin-β5, and GFRAL protein levels across 78 high-quality human male/female brain tissues in infants, toddlers, preschoolers, adolescent, and adults-providing the most robust analysis to date on their levels in the human cortex and hippocampus. We report that integrin-αV was detected at all ages in the prefrontal cortex with levels greatest in adults. Integrin-αV was also detected in the hippocampus in all age groups. In contrast, integrin-β5 was detected in cortex and hippocampus largely restricted to infants. Co-expression of integrin-αV/β5 in the human infant hippocampus and cortex suggests the possibility that irisin has a more robust effect on the developing vs. the adult brain and may have implications for Zika virus infection in infants and young children.

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.

Maternal irisin level in last trimester isolated intrauterine growth-restriction

PURPOSE

Intrauterine Growth Restriction (IUGR) is the inability of the fetus to achieve the biologically accessible growth potential. Irisin is a recently discovered adipomyokine with a crucial role in energy metabolism. Our current study aimed to investigate the relationship between the isolated IUGR in the third trimester and maternal serum irisin level.

MATERIALS AND METHODS

This prospective case-control study included total 137 pregnant women who were between the 24th and 39th gestational weeks and who applied to the University of Health Sciences, Ankara Zekai Tahir Burak Women's Health Training and Research Center, between 2016 October-2017 May. The Study Group consisted of 68 pregnant women who were diagnosed with Isolated IUGR with Estimated Fetal Weight (EFW) <10th percentile. The Control Group consisted of 69 low-risk uncomplicated pregnant women, matched with the Study Group in terms of gestational week, and with EFW between 10th and 90th percentiles. Demographic data, clinical findings, fetal Doppler parameters, and obstetric-neonatal outcomes were evaluated. Maternal serum irisin levels were measured by ELISA (Enzyme-Linked Immunosorbent Assay) Method and compared between the groups.

RESULTS

Maternal serum irisin level was found to be significantly lower in IUGR Group as compared to the Control (3.83 ng/ml vs. 4.78 ng/ml, p < .001, respectively). There was a positive correlation between maternal serum irisin level and duration of pregnancy, the weight gain during pregnancy, birth weight, fetal abdominal circumference measurement and cerebroplacental ratio (r = 0.18, p = .03; r = 0.17, p = .04; r = 0.37, p < .001; r = 0.35, p < .001; r = 0.27, p = .001, respectively). Binary Logistic Regression Analysis showed that maternal serum irisin level is an independent estimator of IUGR [OR %95 CI: 8.33 (3.22 - 25.01)]. AUC (Area Under the Curve) analysis of maternal irisin for IUGR estimation was 0.75 (p < .001, 95% CI = 0.67 - 0.82). The optimal cutoff value was below 3.86 ng/ml for maternal irisin level with a sensitivity of 54.41% and a specificity of 88.41%, positive predictive value of 82.22% and negative predictive value of 66.30%.

CONCLUSION

Low level of maternal serum irisin in pregnancies with isolated IUGR was consistent with the role of irisin in metabolic pathways and with the increased risk of metabolic diseases in the future life of IUGR fetuses and their mothers.

Serum Irisin Predicts Posthepatectomy Complications in Patients with Hepatocellular Carcinoma

Background

Hepatectomy remains one of the most effective treatments for patients with hepatocellular carcinoma (HCC); however, it can lead to serious complications. Irisin, a key regulator of energy metabolism, is secreted into the circulation by shedding of the extracellular portion of the fibronectin type III domain-containing 5 (FNDC5). We have shown that irisin administration alleviates liver ischemia-reperfusion injury in mice. However, the role of preoperative irisin levels in HCC patients who underwent hepatectomy remained unknown. The purpose of this study was to determine how irisin expression changes in HCC and to explore the relationship between preoperative serum irisin levels and complications after hepatectomy.

Methods

FNDC5/irisin expression data in HCC were extracted from The Cancer Genome Atlas (TCGA) dataset. A total of 219 participants, including 102 healthy controls and 117 HCC patients, were recruited in this study. All HCC patients underwent hepatectomy at the First Affiliated Hospital of the Xi'an Jiaotong University. Preoperative serum irisin levels were measured by ELISA. Postoperative complications were assessed using the comprehensive complication index (CCI) score. The Pearson rank correlation coefficient was computed to assess the correlation between preoperative serum irisin levels and postoperative CCI scores.

Results

In TCGA dataset, FNDC5/irisin expression was downregulated in HCC tissues (P < 0.001). Similarly, serum irisin levels were decreased in HCC patients (P < 0.001). Low preoperative serum irisin levels were significantly correlated with high CCI scores after hepatectomy.

Conclusions

Irisin may be a novel serum biomarker in the diagnosis of HCC and a predictor of complications after hepatectomy.

Rates of myogenesis and myofiber numbers are reduced in late gestation IUGR fetal sheep

Intrauterine growth-restricted (IUGR) fetuses are born with reduced skeletal muscle mass. We hypothesized that reduced rates of myogenesis would contribute to fewer and smaller myofibers in IUGR fetal hindlimb muscle compared to the normally growing fetus. We tested this hypothesis in IUGR fetal sheep with progressive placental insufficiency produced by exposing pregnant ewes to elevated ambient temperatures from 38 to 116 days gestation (dGA; term = 147 dGA). Surgically catheterized control (CON, n = 8) and IUGR (n = 13) fetal sheep were injected with intravenous 5-bromo-2′-deoxyuridine (BrdU) prior to muscle collection (134 dGA). Rates of myogenesis, defined as the combined processes of myoblast proliferation, differentiation, and fusion into myofibers, were determined in biceps femoris (BF), tibialis anterior (TA), and flexor digitorum superficialis (FDS) muscles. Total myofiber number was determined for the entire cross-section of the FDS muscle. In IUGR fetuses, the number of BrdU+ myonuclei per myofiber cross-section was lower in BF, TA, and FDS (P < 0.05), total myonuclear number per myofiber cross-section was lower in BF and FDS (P < 0.05), and total myofiber number was lower in FDS (P < 0.005) compared to CON. mRNA expression levels of cyclins, cyclin-dependent protein kinases, and myogenic regulatory factors were lower (P < 0.05), and inhibitors of the cell cycle were higher (P < 0.05) in IUGR BF compared to CON. Markers of apoptosis were not different in IUGR BF muscle. These results show that in IUGR fetuses, reduced rates of myogenesis produce fewer numbers of myonuclei, which may limit hypertrophic myofiber growth. Fewer myofibers of smaller size contribute to smaller muscle mass in the IUGR fetus.

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.

Study on the relationship between the levels of irisin in umbilical cord blood and neonatal growth in China

Objective: The results of the study on the relationship between obesity and cord blood irisin were far apart. The aim of this study was to explore the relationship between cord blood irisin levels and neonatal growth in China.Methods: A cross-sectional study of 400 neonates and their mothers was conducted in the obstetrics department of Shandong provincial hospital in China. Neonates were divided into a fetal macrosomia group and a normal birth weight group based on customized birth-weight standards and divided into non-high-ponderal index group and high ponderal index group based on ponderal index. Levels of irisin in umbilical cord blood were measured by enzyme-linked immunosorbent assay.Results: Irisin concentrations in the fetal macrosomia group were significantly higher than in the normal birth weight group (p = .032). Irisin levels in the high ponderal index group were significantly higher compared with the non-high-ponderal index group (p = .032). After adjustment for confounding variables, logistic regression analysis identified macrosomia affected factors include weight gained during pregnancy (OR = 1.15, p = .028), infant's sex (OR = 9.73, p = .001) and found that affected factors of high ponderal index include weight gained during pregnancy (OR = 1.08, p = .025), maternal age (OR = 1.10, p = .018). Compared with the reference category (<108.62 ng/ml), infants with a cord blood irisin level above 241.44 ng/ml had significantly elevated risk of macrosomia (OR = 8.57, p = .010) and had significantly elevated risk of high birth ponderal index (PI) (OR = 3.15, p = .002). A nonlinear relationship was observed between irisin levels and fetal macrosomia. The higher the concentration of irisin, the greater the risk of fetal macrosomia.Conclusions: We found that as the cord blood irisin increased, the risk of having fetal macrosomia was greater. Weight gained during pregnancy and high cord blood irisin levels were independent predictors of fetal adiposity.

Relationship of Circulating Irisin with Body Composition, Physical Activity, and Cardiovascular and Metabolic Disorders in the Pediatric Population

Exercise-induced irisin, a recently discovered myokine, has been linked to insulin resistance, obesity, and other diseases in adults; however, information in children is scarce and contradictory. We analyzed the limited evidence of irisin’s effects in children and adolescents, and its association with body composition, exercise training, cardiovascular risk factors, and metabolic diseases, as well as the results of dietetic interventions. Both positive and negative correlations between irisin concentrations and body mass index, fat mass, fat-free mass, and other anthropometric parameters were found. Likewise, contradictory evidence was shown associating irisin plasma levels with cardiovascular and metabolic parameters such as glucose, insulin resistance, and cholesterol and other lipid and fatty acid plasma levels in healthy children, as well as in those with obesity and the metabolic syndrome. Gender, puberty, and hormonal differences were also examined. Furthermore, important contradictory findings according to the type and duration of exercise and of dietetic interventions in healthy and unhealthy subjects were demonstrated. In addition, correlations between mother–infant relations and circulating irisin were also identified. This review discusses the potential role of irisin in health and disease in the pediatric population.

Evaluation of irisin and visfatin levels in very low birth weight preterm newborns compared to full term newborns-A prospective cohort study

Premature infants represent one of the groups with increased risk for metabolic syndrome. Our study is the first one to evaluate irisin and visfatin levels, associated with the metabolic syndrome, both in blood of preterm and full-term infants, as well as in the breastmilk of their mothers. A total of 72 newborns was enrolled in the study, including 53 very low birth weight preterm infants and a control group of 19 term infants. The levels of irisin and visfatin were determined by a commercial enzyme-linked immunoabsorbent assay both in the baby serum and maternal milk twice, first during the 1^st week of life and then 4 weeks later. Preterm infants had significantly lower serum irisin levels compared to the term infants. Overall, serum irisin level during the 1^st week of life was positively correlated with several anthropometric measurements at birth, as well as during 5^th weeks of age. In contrast, serum visfatin levels during 5^th week of life were negatively correlated with z-scores of birth weight, weight and head circumference during 5^th week of age. We found a strong negative correlation between serum irisin and serum visfatin levels at both analyzed time points. The level of milk visfatin was significantly higher in the mothers of the preterm group during 5^th week of life. In conclusion, our results provide further evidence that irisin and visfatin may play physiologic roles in development of both preterm and full-term newborns during their first month after birth. Observed differences in irisin and visfatin serum and breastmilk concentrations during the earliest stages of life may contribute to development of catch up growth, but also, they might eventually lead to a higher risk for metabolic syndrome in prematurely born children in later years.

Biomarkers for Macrosomia Prediction in Pregnancies Affected by Diabetes

Large birthweight, or macrosomia, is one of the commonest complications for pregnancies affected by diabetes. As macrosomia is associated with an increased risk of a number of adverse outcomes for both the mother and offspring, accurate antenatal prediction of fetal macrosomia could be beneficial in guiding appropriate models of care and interventions that may avoid or reduce these associated risks. However, current prediction strategies which include physical examination and ultrasound assessment, are imprecise. Biomarkers are proving useful in various specialties and may offer a new avenue for improved prediction of macrosomia. Prime biomarker candidates in pregnancies with diabetes include maternal glycaemic markers (glucose, 1,5-anhydroglucitol, glycosylated hemoglobin) and hormones proposed implicated in placental nutrient transfer (adiponectin and insulin-like growth factor-1). There is some support for an association of these biomarkers with birthweight and/or macrosomia, although current evidence in this emerging field is still limited. Thus, although biomarkers hold promise, further investigation is needed to elucidate the potential clinical utility of biomarkers for macrosomia prediction for pregnancies affected by diabetes.

First-trimester irisin and fetuin-A concentration in predicting macrosomia

Objective: We investigated the diagnostic value of first-trimester adipokines and placental markers in predicting macrosomia. Methods: Out of 328 women recruited during the prenatal diagnosis between 11th and 13th week of pregnancy and subjected to follow up until delivery, we selected 26 women who gave birth to macrosomic babies and 34 women who gave birth to normal weight neonates for the evaluation of first trimester serum levels of pregnancy associated plasma protein-A, free β-human chorionic gonadotropin, placental growth factor (PIGF), and selected adipokines. Results: The mothers of macrosomic infants had higher PIGF (p = .049) and irisin concentrations (p = .00003), and lower fetuin-A levels (p = .0002) than had the mothers of normal weight babies. Newborn's weight correlated positively with maternal irisin (R = 0.454, p = .0003) and negatively with fetuin-A concentrations (R = -0.497, p = .00005). Multiple regression analysis showed that only serum irisin concentration was a significant predictor of birth weight (β = 0.329, p = .03), explaining 14% of its variability. The sensitivity and the specificity of irisin concentration in predicting macrosomia were 0.769 and 0.794, respectively (AUC = 0.818 [95%CI: 0.708-0.928], p = .00001) with a proposed cut-off value of 1725.4 ng/ml. Conclusions: Our results suggest that mother's irisin may be an early biomarker of macrosomia.

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.

A role for maternally derived myokines to optimize placental function and fetal growth across gestation

Exercise during pregnancy is associated with improved health outcomes for both mother and baby, including a reduced risk of future obesity and susceptibility to chronic diseases. Overwhelming evidence demonstrates a protective effect of maternal exercise against fetal birth weight extremes, reducing the rates of both large- and small-for-gestational-age infants. It is speculated that this protective effect is mediated in part through exercise-induced regulation of maternal physiology and placental development and function. However, the specific mechanisms through which maternal exercise regulates these changes remain to be discovered. We hypothesize that myokines, a collection of peptides and cytokines secreted from contracting skeletal muscles during exercise, may be an important missing link in the story. Myokines are known to reduce inflammation, improve metabolism and enhance macronutrient transporter expression and activity in various tissues of nonpregnant individuals. Little research to date has focused on the specific roles of the myokine secretome in the context of pregnancy; however, it is likely that myokines secreted from exercising skeletal muscles may modulate the maternal milieu and directly impact the vital organ of pregnancy—the placenta. In the current review, data in strong support of this potential role of myokines will be presented, suggesting myokine secretion as a key mechanism through which maternal exercise optimizes fetal growth trajectories. It is clear that further research is warranted in this area, as knowledge of the biological roles of myokines in the context of pregnancy would better inform clinical recommendations for exercise during pregnancy and contribute to the development of important therapeutic interventions.

The novel exercise-induced hormone irisin protects against neuronal injury via activation of the Akt and ERK1/2 signaling pathways and contributes to the neuroprotection of physical exercise in cerebral ischemia

BACKGROUND

Irisin is a novel exercise-induced myokine involved in the regulation of adipose browning and thermogenesis. In this study, we investigated the potential role of irisin in cerebral ischemia and determined whether irisin is involved in the neuroprotective effect of physical exercise in mice.

MATERIALS AND METHODS

The middle cerebral artery occlusion (MCAO) model was used to produce cerebral ischemia in mice. First, the plasma irisin levels and changes in expression of the irisin precursor protein FNDC5 in skeletal muscle were determined post ischemic stroke. Second, the association between plasma irisin levels and the neurological deficit score, brain infarct volume, or plasma concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β in mice with MCAO were evaluated. Third, the therapeutic effect of irisin on ischemic brain injury was evaluated in vivo and in vitro. Recombinant irisin was injected directly into the tail vein 30min after the MCAO operation, and then the effects of irisin treatment on brain infarct volume, neurological deficit, neuroinflammation, microglia activation, monocyte infiltration, oxidative stress and intracellular signaling pathway activation (Akt and ERK1/2) were measured. Irisin was also administered in cultured PC12 neuronal cells with oxygen and glucose deprivation (OGD). Finally, to assess the potential involvement of irisin in the neuroprotection of physical exercise, mice were exercised for 2weeks and an irisin neutralizing antibody was injected into these mice to block irisin 1h before the MCAO operation.

RESULTS

The plasma irisin concentration and intramuscular FNDC5 protein expression decreased after ischemic stroke. Plasma irisin levels were negatively associated with brain infarct volume, the neurological deficit score, plasma TNF-α and plasma IL-6 concentrations. In OGD neuronal cells, irisin protected against cell injury. In mice with MCAO, irisin treatment reduced the brain infarct volume, neurological deficits, brain edema and the decline in body weight. Irisin treatment inhibited activation of Iba-1⁺ microglia, infiltration of MPO-1⁺ monocytes and expression of both TNF-α and IL-6 mRNA. Irisin significantly suppressed the levels of nitrotyrosine, superoxide anion and 4-hydroxynonenal (4-HNE) in peri-infarct brain tissues. Irisin treatment increased Akt and ERK1/2 phosphorylation, while blockade of Akt and ERK1/2 by specific inhibitors reduced the neuroprotective effects of irisin. Finally, the exercised mice injected with irisin neutralizing antibody displayed more severe neuronal injury than the exercised mice injected with control IgG.

CONCLUSION

Irisin reduces ischemia-induced neuronal injury via activation of the Akt and ERK1/2 signaling pathways and contributes to the neuroprotective effect of physical exercise against cerebral ischemia, suggesting that irisin may be a factor linking metabolism and cardio-cerebrovascular diseases.

Angiopoietin-like protein 8 (ANGPTL8) in pregnancy: a brown adipose tissue-derived endocrine factor with a potential role in fetal growth

Angiopoietin-like protein 8 (ANGPTL8), a protein implicated in lipid and glucose homeostasis, is present only in mammals, suggesting that it is involved in processes unique to these vertebrates such as pregnancy and homeothermy. We explored the role of ANGPTL8 in maternal-fetal crosstalk and its relationship with newborn adiposity. In a longitudinal analysis of healthy pregnant women, ANGPTL8 levels decreased progressively during pregnancy although remained higher than levels in the postpartum period. In a cross-sectional observational study of women with or without gestational diabetes mellitus (GDM), and their offspring, ANGPTL8 levels were higher in venous cord blood than those in maternal blood and were significantly lower in GDM patients than those in healthy women. Infants small for gestational age and with low-fat mass had the highest ANGPTL8 cord blood levels. Studies in vitro revealed that ANGPTL8 was secreted by brown adipocytes and its expression was increased in experimental models of white-to-brown fat conversion. In addition, ANGPTL8 induced the expression of markers of brown adipocytes. The high levels of ANGPTL8 found in fetal life together with its relationship with newborn adiposity and brown adipose tissue point to ANGPTL8 as a potential new player in the modulation of the thermogenic machinery during the fetal-neonatal transition.

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.

E2F1 Orchestrates Transcriptomics and Oxidative Metabolism in Wharton's Jelly-Derived Mesenchymal Stem Cells from Growth-Restricted Infants

Wharton's jelly-derived Mesenchymal Stem Cells (MSCs) isolated from newborns with intrauterine fetal growth restriction were previously shown to exert anabolic features including insulin hypersensitivity. Here, we extend these observations and demonstrate that MSCs from small for gestational age (SGA) individuals have decreased mitochondrial oxygen consumption rates. Comparing normally grown and SGA MSCs using next generation sequencing studies, we measured global transcriptomic and epigenetic profiles and identified E2F1 as an over-expressed transcription factor regulating oxidative metabolism in the SGA group. We further show that E2F1 regulates the differential transcriptome found in SGA derived MSCs and is associated with the activating histone marks H3K27ac and H3K4me3. One of the key genes regulated by E2F1 was found to be the fatty acid elongase ELOVL2, a gene involved in the endogenous synthesis of docosahexaenoic acid (DHA). Finally, we shed light on how the E2F1-ELOVL2 pathway may alter oxidative respiration in the SGA condition by contributing to the maintenance of cellular metabolic homeostasis.

Novel Molecules Regulating Energy Homeostasis: Physiology and Regulation by Macronutrient Intake and Weight Loss

Excess energy intake, without a compensatory increase of energy expenditure, leads to obesity. Several molecules are involved in energy homeostasis regulation and new ones are being discovered constantly. Appetite regulating hormones such as ghrelin, peptide tyrosine-tyrosine and amylin or incretins such as the gastric inhibitory polypeptide have been studied extensively while other molecules such as fibroblast growth factor 21, chemerin, irisin, secreted frizzle-related protein-4, total bile acids, and heme oxygenase-1 have been linked to energy homeostasis regulation more recently and the specific role of each one of them has not been fully elucidated. This mini review focuses on the above mentioned molecules and discusses them in relation to their regulation by the macronutrient composition of the diet as well as diet-induced weight loss.