A Review on the Role of Irisin in Insulin Resistance and Type 2 Diabetes Mellitus

Effect of coadministration of omega-3 fatty acids with glimepiride on glycemic control, lipid profile, irisin, and sirtuin-1 in type 2 diabetes mellitus patients: a randomized controlled trial

BACKGROUND AND OBJECTIVE

Type 2 diabetes mellitus (T2DM) is caused by insulin resistance or tissue insensitivity to insulin, as well as relative insulin insufficiency. Diabetes that is uncontrolled for an extended period of time is linked to substantial comorbidities and organ damage. The purpose of the current study is to assess the effect of coadministration of omega-3 fatty acids with glimepiride on blood glucose, lipid profile, serum irisin, and sirtuin-1 levels in T2DM patients.

METHODS

This clinical trial involved 70 type 2 diabetic patients randomly assigned to glimepiride 3 mg with either omega-3 capsules contained fish oil 1000 mg, 13% of eicosapentaenoic acid (EPA) and 9% docosahexaenoic acid (DHA) (omega-3 group, n = 35) or placebo capsules contained corn oil and linoleic acid (control group, n = 35) daily for three months. Blood samples were obtained at the start of the study and 12 weeks later for biochemical examination of HbA1c%, FBG, fasting insulin, and lipid profile. In addition, the atherogenic index of plasma (AIP) was calculated. Human enzyme-linked immunosorbent assay (ELISA) kits were utilized for assessing serum irisin and sirtuin-1 levels before and after the intervention.

RESULTS

Compared to the control group, omega-3 fatty acids decreased serum fasting blood glucose (FBG, p < 0.001), glycated hemoglobin percent (HbA1C%, p < 0.001), total cholesterol (TC, p < 0.001), triglycerides (TGs, p = 0.006), low density lipoprotein (LDL, p = 0.089), and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR, p = 0.021) after three months of intervention. However, a significant increase was reported in serum irisin and high density lipoprotein (HDL) between both groups after intervention (p = 0.026 and p = 0.007, respectively). The atherogenic index of plasma (AIP) increased in the control group but decreased in the omega-3 group, with significant differences between the two groups (p < 0.001).

CONCLUSION

The present study found that supplementing with omega-3 fatty acids might dramatically enhance blood irisin levels, as well as improve glycemic control and lipid profile in type 2 diabetes mellitus patients using glimepiride.

TRIAL REGISTRATION

This study is registered on ClinicalTrials.gov under identifier NCT03917940 . (The registration date: April 17, 2019).

Serum Irisin Levels Are Inversely Correlated With the Severity of Coronary Artery Disease Confirmed by Coronary Angiography: A Comparative Cross-Sectional Study

Introduction Irisin, a newly discovered myokine, has been reported for its role in coronary artery disease (CAD), which is a major cause of mortality worldwide. Atherosclerosis is the primary cause of CAD. Irisin has been reported to reduce atherosclerosis by improving endothelial function and inhibiting inflammation via iNOS/NF-κB pathways. We sought to investigate the relationship between serum irisin levels and the severity of CAD that is confirmed with coronary angiography. Methods A comparative cross-sectional study was designed between the Chemical Pathology and Cardiology departments at KEMU/Mayo Hospital in Lahore, Pakistan. Patients were divided into group A with mild CAD (<50% stenosis) and group B with moderate-severe CAD (>50% stenosis). Serum was collected from venous blood, and irisin levels were analyzed by ELISA. Inclusion criteria: patients with stable CAD. Exclusion criteria: History of coronary artery bypass grafting (CABG), acute coronary syndrome (ACS), active or chronic infection, hepatic or renal dysfunction. Results The mean + SD age (years) of patients in group B (57.0±9.5) was significantly higher than group A (50.0±13.7). Irisin levels (μg/ml) were significantly higher in group A (15.3±4.6) than in group B (9.3±2.4). Irisin levels were significantly negatively correlated with the severity of CAD (% stenosis). Conclusion Serum irisin levels are low in patients with moderate to severe CAD, and they are negatively correlated with the severity of CAD (% stenosis).

Hydrogen Sulfide Regulates Irisin and Glucose Metabolism in Myotubes and Muscle of HFD-Fed Diabetic Mice

Irisin, a novel myokine, is secreted by the muscle following proteolytic cleavage of fibronectin type III domain containing 5 (FNDC5) and is considered a novel regulator of glucose homeostasis. Cystathionine γ-lyase (CSE) produces hydrogen sulfide (H₂S) and is involved in glucose homeostasis. We examined the hypothesis that H₂S deficiency leads to decreased FNDC5 and irisin secretion, and thereby alters glucose metabolism. High-fat diet-fed mice exhibited elevated blood glucose and significantly reduced levels of CSE, H₂S, and PGC-1α, with decreased FNDC5/irisin levels and increased oxidative stress in the muscle compared with those of normal diet-fed mice (control). High glucose or palmitate decreases CSE/PGC-1α/FNDC5 levels and glucose uptake in myotubes. Inhibitors (propargylglycine and aminooxyacetate) of H₂S producing enzymes or CSE siRNA significantly decreased levels of H₂S and FNDC5 along with PGC-1α; similar H₂S-deficient conditions also resulted in decreased GLUT4 and glucose uptake. The levels of H₂S, PGC-1α, and FNDC5 and glucose uptake were significantly upregulated after treatment with l-cysteine or an H₂S donor. Myoblast differentiation showed upregulation of PGC-1α and FNDC5, which was consistent with the increased expression of CSE/H₂S. These findings suggest that the upregulation of H₂S levels can have beneficial effects on glucose homeostasis via activation of the PGC-1α/FNDC5/irisin signaling pathway.

Beneficial effects of MgSO4 on TFAM, UPC3 and FNDC5 mRNA expressions in skeletal muscle of type 2 diabetic rats: a possible mechanism to improve insulin resistance

BACKGROUND

Hypomagnesemia has been associated with development of type 2 diabetes mellitus (T2DM) and its complications. Irisin has beneficial effects on glucose uptake and improves hepatic glucose and lipid metabolism. In this study, we aimed to evaluate the effects of long-term treatment of MgSO₄ and insulin on insulin resistance, dyslipidemia, serum and hepatic irisin levels, skeletal muscle gene expression of fibronectin type III domain-containing protein 5 (FNDC5), mitochondrial transcription factor A (TFAM) and mitochondrial uncoupling protein 3 (UCP3) in T2DM rats.

METHODS AND RESULTS

Twenty-four rats were divided into four groups: Control group, diabetic control (DC) using a high-fat diet + streptozotocin, insulin-treated diabetic group (DC + Ins), MgSO₄-treated diabetic group (DC + Mg). At the end of therapies, serum concentrations of FBG, TG, insulin, Ox-LDL, along with serum and hepatic irisin levels were measured. FNDC5, TFAM, and UCP3 mRNA expressions were measured in the skeletal muscle by Real-time PCR. In comparison with DC group, MgSO₄ therapy resulted in decreased FBG, TG, Ox-LDL, improved serum insulin and irisin levels, and increased mRNA expressions of FNDC5, UCP3 and TFAM. Insulin therapy significantly decreased FBG, Ox-LDL, FNDC5 and serum irisin levels compared with the control group. While, insulin therapy markedly increased TFAM and UCP3 compared with the DC group.

CONCLUSIONS

In conclusion, MgSO₄ can improve insulin resistance and hyperlipidemia partly through decreasing Ox-LDL, increasing serum irisin levels as well as increasing FNDC5, TFAM, and UCP3 mRNA expressions in T2DM rats. These findings can be considered in the management of diabetes treatment.

Effects of low and high intensity interval training exercises on VO2max and components of neuromuscular and vascular system in male volunteers

OBJECTIVES

To evaluate the effects of different intensity exercises on maximal oxygen consumption (VO_2max and levels of components, namely brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrKB), vascular endothelial growth factor (VEGF), peroxisome proliferator activated receptor-gamma coactivator (PGC-1α), and irisin.

METHODS

Thirty-six male participants were divided into control (CNT), low-intensity (LIIT), and high-intensity interval training (HIIT) groups. LIIT and HIIT groups consisted of 8 exercises (20 s work and rest in each repetition, respectively) conducted for 4 weeks. VO_2max and protein component levels were determined pre- and post-training. VO_2max capacity was also determined using the Yo Yo Intermittent Recovery Test-1 (Yo Yo IR-1). Statistical analysis was conducted to determine significance of the differences observed.

RESULTS

According to the YoYo IR-1, VO_2max, serum BDNF, VEGF, PGC1α, irisin, and TrkB data obtained in the study, a statistically significant difference between the groups was observed (p<0.05). While the interaction effect was found to be statistically significant in the study using PGC1α, VEGF, and TrkB data (p<0.05), it was not found to be statistically significant using YoYo IR-1, VO_2max, serum BDNF, or irisin data (p>0.05).

CONCLUSION

HIIT and LIIT improved all study parameters, while HIIT showed a greater effect than LIIT.

Pilates and TRX training methods can improve insulin resistance in overweight women by increasing an exercise-hormone, Irisin

AIMS AND BACKGROUND

Physical inactivity is leading to obesity and consequently insulin resistance and diabetes. Feasible and cost efficient strategies like Pilates and total body resistance exercise (TRX) training can impede obesity and its compilation. The aim of this study was to investigate the effects of 8 weeks Pilates and TRX training programs on irisin concentration and insulin resistance in overweight women.

METHOD

Thirty overweight women (Body mass index (BMI): 25-29.9 kg/m2) were divided, based on their BMI, into 3 groups; control, Pilates and TRX. The participants in the training groups were subjected to moderate intensity of Pilates or TRX exercise training 3 times a week for 8 weeks. Blood samples were taken at pre-test and 48 h after the last training session and used for analyzing irisin, insulin and glucose. Data were analyzed by ANCOVA and paired-samples t-test.

RESULTS

The finding showed that the Pilates training decreased body weight and BMI compared to the pre-test (P < 0.05). Also, it has been revealed that irisin concentration in response to Pilates and TRX training programs were increased in comparison with the control group (P < 0.05). However, there was no significant difference in irisin concentrations between training groups (p > 0.05). Moreover, fasting insulin, glucose and insulin resistance were significantly reduced after exercise intervention compared to the pre-test which were significantly lowered compared to the control group as well.

CONCLUSION

The results suggest Pilates and TRX trainings are two efficient model of exercise that by eliciting an exercise-hormone, irisin, can improve insulin resistance in overweight women.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Clinically confirmed DEL-1 as a myokine attenuates lipid-induced inflammation and insulin resistance in 3T3-L1 adipocytes via AMPK/HO-1- pathway

Regular exercise is the first line of therapy for treating obesity-mediated metabolic disorders, including insulin resistance. It has been reported that developmental endothelial locus-1 (DEL-1) enhances macrophage efferocytosis, resulting in inflammation clearance as well as improves insulin resistance in skeletal muscle. However, the relationship between exercise and DEL-1, and the effects of DEL-1 on insulin signalling in adipocytes have not been fully elucidated to date. Protein expression levels were determined by Western blot analysis. Cells were transfected with small interfering (si) RNA to suppress gene expression. Lipid accumulation levels were detected using Oil red-O staining. Proinflammatory cytokine secretion levels were measured using ELISA. DEL-1 expression levels were induced in the skeletal muscle of people who exercised using microarray analysis. Recombinant DEL-1 augmented AMP-activated protein kinase (AMPK) phosphorylation and haem oxygenase (HO)-1 expression to alleviating inflammation and impairment of insulin signalling in 3T3-L1 adipocytes treated with palmitate. siRNA of AMPK or HO-1 also mitigated the effects of DEL-1 on inflammation and insulin resistance. DEL-1 ameliorates inflammation and insulin resistance in differentiated 3T3-L1 cells via AMPK/HO-1 signalling, suggesting that DEL-1 may be the exercise-mediated therapeutic target for treating insulin resistance and type 2 diabetes.

Irisin Gene Delivery Ameliorates Burn-Induced Sensory and Motor Neuropathy

Burn-related neuropathy is common and often involves pain, paresthesia, or muscle weakness. Irisin, an exercise-induced myokine after cleavage from its membrane precursor fibronectin type III domain-containing 5 (FNDC5), exhibits neuroprotective and anti-inflammatory activities. A rat model of third-degree burn on the right hind paw was used to investigate the therapeutic role of irisin/FNDC5. Rats received burn injury and were treated with intrathecal recombinant adenovirus containing the irisin sequence (Ad-irisin) at 3 weeks postburn. One week later, mechanical allodynia was examined. The expression of irisin in cerebrospinal fluid (CSF) was detected. Ipsilateral gastrocnemius muscle and lumbar spinal cord were also obtained for further investigation. Furthermore, the anti-apoptotic effect of recombinant irisin in SH-SY5Y cells was evaluated through tumor necrosis factor alpha (TNFα) stimulus to mimic burn injury. We noted intrathecal Ad-irisin attenuated pain sensitization and gastrocnemius muscle atrophy by modulating the level of irisin in CSF, and the expression of neuronal FNDC5/irisin and TNFα in the spinal cord. Ad-irisin also ameliorated neuronal apoptosis in both dorsal and ventral horns. Furthermore, recombinant irisin attenuated TNFα-induced SH-SY5Y cell apoptosis. In summary, irisin attenuated allodynia and muscle wasting by ameliorating neuroinflammation-induced neuronal apoptosis.

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

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

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

Background

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

Methods

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

Results

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

Conclusions

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

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

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

Maximizing Longevity and Healthspan: Multiple Approaches All Converging on Autophagy

Our understanding of the molecular basis of aging has greatly increased over the past few decades. In this review, we provide an overview of the key signaling pathways associated with aging, and whose modulation has been shown to extend lifespan in a range of model organisms. We also describe how these pathways converge onto autophagy, a catabolic process that functions to recycle dysfunctional cellular material and maintains energy homeostasis. Finally, we consider various approaches of therapeutically modulating these longevity pathways, highlighting exercise as a potent geroprotector.

Irisin Enhances Doxorubicin-Induced Cell Apoptosis in Pancreatic Cancer by Inhibiting the PI3K/AKT/NF-κB Pathway

Background

Irisin, a myokine released from skeletal muscle following exercise, has been shown to affect the proliferation of some cancer cells and chemosensitivity of anticancer drugs like doxorubicin (DOX). However, the effects of irisin on chemosensitivity in pancreatic cancer (PC) cells have not been studied.

Material/Methods

In this study, the effects of irisin co-treatment with DOX or gemcitabine (GEM) on MIA PaCa-2, BxPC-3 PC cells, and H9c2 cardiomyocytes were investigated. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, flow cytometry, and TUNEL (TdT-mediated dUTP nick-end labeling) assays were conducted to evaluate cytotoxicity induced by DOX or GEM. Fluorescence microscopy and flow cytometry experiments were performed to assess the intracellular accumulation of DOX. Cellular levels of apoptosis-related protein expression and protein phosphorylation were determined by Western blot analyses.

Results

The results showed that irisin can increase the chemosensitivity of PC cells to DOX or GEM. The analyses of apoptosis indicated that irisin enhances DOX-induced cellular apoptosis by increasing the expression of cleaved PARP (poly ADP-ribose polymerase) and cleaved caspase-3, and reducing the expression of B cell lymphoma/lewkmia-2 (BCL-2) and B cell lymphoma-extra large (BCL-xL) in PC cells but not in H9c2 cells. Irisin attenuated serine/threonine kinase AKT (protein kinase B/PKB) phosphorylation and inhibited the activation of nuclear factor κB (NF-κB) signaling in PC cells.

Conclusions

Irisin can potentiate the cytotoxicity of doxorubicin in PC cells without increasing cardiotoxicity, possibly through inactivating the PI3K/AKT/NF-κB signaling pathway.

Comparison of irisin hormone expression between thyroid cancer tissues and oncocytic variant cells

Objective: The incidence of thyroid cancer has been continuously increasing. The main objective of this study was to investigate irisin expression in various thyroid pathologies and to compare these expression patterns with irisin expression in healthy thyroid tissues.

Methods: The study groups consisted of 20 cases each of control thyroid tissue, Hashimoto’s thyroiditis, thyroid papillary carcinoma, oncocytic papillary carcinoma, follicular thyroid carcinoma, oncocytic follicular thyroid carcinoma, medullary thyroid carcinoma, anaplastic thyroid carcinoma. Irisin expression was evaluated using immunohistochemistry. Irisin levels in thyroid tissue supernatants were measured using ELISA.

Results: Patients with HT showed increased irisin expression compared with controls (p<0.05). In addition, mild immunoreactivity was observed in the thyroid tissues of patients with papillary carcinoma while significantly increased irisin immunoreactivity was observed tissues of patients with oncocytic papillary carcinoma (p<0.05). There was no difference in irisin immunoreactivity in thyroid tissues between patients with follicular carcinoma and controls. However, irisin immunoreactivity was higher in tissues of patients with oncocytic follicular carcinoma than in tissues of patients with follicular carcinoma (p<0.05). No irisin immunoreactivity was observed in tissues of patients with medullary carcinoma, a malignant tumor the thyroid; however, irisin expression was significantly increased in tissues of patients with anaplastic carcinoma compared with that in tissues of controls (p<0.05). Furthermore, in all thyroid tissues with irisin expression, irisin immunoreactivity was observed in follicular cells, indicating that irisin is produced by these cells.

Conclusion: Irisin is a novel potential immunohistochemical marker for differentiating oncocytic variants of papillary and FTCs from papillary and follicular thyroid cancers.

Curcumin protects islet cells from glucolipotoxicity by inhibiting oxidative stress and NADPH oxidase activity both in vitro and in vivo

Curcumin possesses medicinal properties that are beneficial in various diseases, such as heart disease, cancer, and type 2 diabetes mellitus (T2 DM). It has been proposed that pancreatic beta cell dysfunction in T2 DM is promoted by oxidative stress caused by NADPH oxidase over-activity. The aim of the present study was to evaluate the efficacy of curcumin as a protective agent against high glucose/palmitate (HP)-induced islet cell damage and in streptozotocin (STZ)-induced DM rats. INS-1 cells were exposed to HP with or without curcumin. Cell proliferation, islet cell morphological changes, reactive oxygen species production, superoxide dismutase and catalase activity, insulin levels, NADPH oxidase subunit expression, and the expression of apoptotic factors by INS-1 cells were observed. Our results show that curcumin can effectively inhibit the impairment of cell proliferation and activated oxidative stress, increase insulin levels, and reduce the high expression of NADPH oxidase subunits and apoptotic factors induced by HP in INS-1 cells. The STZ-induced DM rat model was also used to determine whether curcumin can protect islets in vivo. Our results show that curcumin significantly reduced pathological damage and increased insulin levels of islets in STZ-induced DM rats. Curcumin also successfully inhibited the high expression of NADPH oxidase subunits and apoptotic factors in STZ-induced DM rats. These results suggest that curcumin is able to attenuate HP-induced oxidative stress in islet cells and protect these cells from apoptosis by modulating the NADPH pathway. In view of its efficiency, curcumin has potential for translation applications in protecting islets from glucolipotoxicity.

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

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