OBJECTIVE: To investigate the independent effects of irisin on insulin resistance (IR) in ovary of polycystic ovary syndrome (PCOS) and explore possible pathways.
METHODS: We established PCOS medel using Poretsky L\'s method, then PCOS rats were randomly divided into model group (M) and irisin group (I), and normal rats (N) were used as the control. Then rats in the group I were injected with recombinant irisin. Then the levels of circulating fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of IR (HOMA-IR) and PI3K/AKT and MAPK/ERK pathways in each group were observed, as well as the effects of irisin on the levels of circulating HOMA-IR and PI3K/AKT and MAPK/ERK pathways in ovary of PCOS rats were evaluated.
RESULTS: Compared with normal group, levels of FBG, FINS, and HOMA-IR of model group were significantly increased (p < 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.015, p = 0.010, p = 0.005, and p = 0.009, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.001, and p = 0.005, respectively) were decreased, while the levels of average optical density of p-ERK, ERK (p = 0.011, and p = 0.013, respectively) and level of mRNA concentration of ERK (p < 0.001) were increased in ovary. After irisin intervention, compared with model group, levels of FBG, FINS, and HOMA-IR of rats in irisin group were significantly decreased (p = 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.030, p = 0.024, p = 0.012, and p = 0.025, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.002, and p = 0.003, respectively) were significantly increased, while the levels of average optical density of p-ERK, ERK (p = 0.004, and p = 0.026, respectively) and level of mRNA concentration of ERK (p = 0.001) were significantly decreased.
CONCLUSIONS: Our study demonstrated that irisin could not only improve circulating insulin resistance, but may also improve ovarian IR through an increase in the activity of PI3K/AKT signaling and a decrease of MAPK/ERK signaling.

Irisin is a glycosylated protein formed from the hydrolysis of fibronectin type III domain-containing protein 5 (FNDC5). Irisin is widely involved in the regulation of glucose and lipid metabolism. In addition, recent studies have demonstrated that Irisin can inhibit inflammation, restrain oxidative stress and have neuroprotective effects, which suggests that Irisin may have a good therapeutic effect on central nervous system diseases. Therefore, this review summarizes the role of Irisin in central nervous system diseases, including its signal pathways and possible mechanisms, etc. Irisin may be a potential candidate drug for the treatment of central nervous system diseases.

The purpose of the study is to elucidate whether irisin is a promising predictive biomarker for kidney-related events in patients with T2DM and concomitant asymptomatic HF. We prospectively enrolled 146 T2DM patients who had either evidence of structural cardiac abnormality or elevated levels of N-terminal brain natriuretic pro-peptide (NT-proBNP) > 125 pmol/mL and followed them for 52 weeks. Structural cardiac abnormalities were used as the minimum from the following criteria: abnormal left ventricular (LV) global longitudinal strain (GLS) < -16%, LV hypertrophy, left atrial volume index > 34 mL/m2, abnormal ratio of early transmitral diastolic filling velocity/early mitral annular velocity ≥ 13 units. All the patients underwent echocardiographic and Doppler examinations by two blinded, highly experienced echocardiographers. NT-proBNP, irisin, TNF-alpha, and hs-CRP were quantified in the serum at baseline, at 26 weeks, and at the end of the study. The kidney-related outcomes consisted of an eGFR reduction by 40% from baseline, or end-stage kidney disease, or kidney replacement therapy. We found that levels of irisin at baseline < 4.15 ng/mL and/or its decrease > 20% from baseline in T2DM patients predicted kidney-related events better than baseline levels/dynamic NT-proBNP and the use of SGLT2 inhibitors. In conclusion, we established that a low baseline level of irisin and its 20% decrease correlated with newly kidney-related events in T2DM patients with asymptomatic HFpEF/HFmrEF.

OBJECTIVE: Cardiovascular diseases (CVD) are the leading cause of death worldwide. In 2019, 523 million people were diagnosed with CVD, with 18.6 million deaths. Improved treatment and diagnostics could reduce CVD\'s impact. Irisin (Ir) is crucial for heart function and may be a biomarker for heart attack. Ir is a glycoprotein with sugar residues attached to its protein structure. This glycosylation affects Ir stability, solubility, and receptor interactions on target cells. Its secondary structure includes a fibronectin type III domain, essential for its biological functions. Ir helps cardiomyocytes to respond to hypoxia and protects mitochondria. The aim of the study was to determine the FNDC5 gene expression level and the Ir level in HL-1 cardiomyocytes subjected to hypoxia.
METHODS: We examined the effect of hypoxia on the expression levels of the FNDC5 gene and those of Ir in mouse cardiomyocytes of the HL-1 cell line. Real-time PCR (RT-PCR) was used to estimate the expression levels of the FNDC5 gene. Western blot and immunofluorescence methods were used to analyze the Ir protein levels.
RESULTS: Analyses showed an increased Ir level in HL-1 cardiomyocytes in response to hypoxia. This is the first study to confirm the presence of Ir in HL-1 cells.
CONCLUSIONS: The observed increase in Ir expression in murine cardiomyocytes is associated with the hypoxic environment and can be potentially used to diagnose hypoxia and CVD.

UNASSIGNED: This systematic review and meta-analysis aimed to investigate the association between circulating irisin levels and osteoporosis in women, exploring irisin\'s potential role in the pathophysiology and management of osteoporosis.
UNASSIGNED: We searched PubMed, Embase, Web of Science, Cochrane Library, CNKI, WanFang, and VIP databases up to January 2023. The inclusion criteria were observational studies reporting on circulating irisin levels in women. The standardized mean difference (SMD) and correlation coefficients with a 95% confidence interval (CI) were used as the main effect measures under a random-effects model. Heterogeneity was evaluated using the Cochrane Q statistic and the I2 statistics. Subgroup analysis and univariate meta-regression analysis were performed to identify the sources of heterogeneity. The quality of the included study was assessed by the Newcastle-Ottawa Score. The quality of evidence was evaluated using the GRADE system. Publication bias was assessed using Begg\'s and Egger\'s test, and the trim-and-fill method. Sensitivity analysis was performed to assess the stability of the results.
UNASSIGNED: Fifteen studies with a total of 2856 participants met the criteria. The analysis showed significantly lower irisin levels in postmenopausal osteoporotic women compared to non-osteoporotic controls (SMD = -1.66, 95% CI: -2.43 to -0.89, P < 0.0001; I2 = 98%, P < 0.00001) and in postmenopausal individuals with osteoporotic fractures than in non-fractures controls (SMD = -1.25, 95% CI: -2.15 to -0.34, P = 0.007; I2 = 97%, P < 0.00001). Correlation analysis revealed that irisin levels positively correlated with lumbar spine BMD (r = 0.37, 95% CI: 0.18 to 0.54), femoral BMD (r = 0.30, 95% CI: 0.18 to 0.42), and femoral neck BMD (r = 0.31, 95% CI: 0.14 to 0.47) in women. Despite significant heterogeneity, the robustness of the results was supported by using the random effects model and sensitivity analysis.
UNASSIGNED: The current evidence suggests that lower irisin levels are significantly associated with osteoporosis and fracture in postmenopausal women, suggesting its utility as a potential biomarker for early detection of osteoporosis and therapeutic target. However, further high-quality prospective research controlling for confounding factors is needed to clarify the relationship between irisin levels and osteoporotic outcomes.
UNASSIGNED: https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023410264.

暂无摘要。

OBJECTIVE: To explore the relationship between serum irisin levels and glucose and lipid metabolism among adolescents in Yinchuan City.
METHODS: From 2017 to 2020, a conbination of convenient sampling and stratified cluster random sampling method were used to select 1219 adolescents aged 12 to 18 years old in Yinchuan City as research subjects. The height and weight were measured using the height and sitting height meter and the bioelectrical impedance analyzer. Blood indicators such as fasting plasma glucose(FPG), totalcholesterol(TC), triglyceride(TG), low-density lipoprotein cholesterol(LDL-C) and high-density lipoprotein cholesterol(HDL-C) were measured using fully automatic biochemical analyzer. Serum irisin levels were measured by enzyme-linked immunosorbent assay(ELISA). Binary logistic regression was used to analyze the correlation between irisin and abnormal glucose and lipid metabolism.
RESULTS: The FPG, TC, HDL-C and LDL-C levels of subjects in the highest tertile of irisin levels were significantly lower than those of subjects in the lowest tertile of irisin levels(F values were 5.13, 3.15, 3.07 and 5.01, P<0.05), and the differences were statistically significant(all P<0.05). The serum irisin levels in the hyperglycemia group(t=2.87, P<0.01), hypercholesterolemia group(t=2.36, P=0.02) and hyperLDL-Cemia group(t=2.34, P=0.02) were significantly lower than those in the normoglycemia group, normal TC group and normal LDL-C group. Meanwhile, the irisin level in the low HDL-Cemia group(t=-2.57, P=0.01) was significantly higher than that in the normal HDL-C group, and the differences were statistically significant(P<0.05). Participants in the highest tertile of irisin had 0.51, 0.49 and 0.50 times the risk of hyperglycemia(OR=0.51, 95%CI 0.29-0.87), hypercholesterolemia(OR=0.49, 95%CI 0.27-0.89) and hyperLDL-cemia(OR=0.50, 95%CI 0.25-0.99) compared with those in the lowest tertile.
CONCLUSIONS: Low levels of irisin are associated with the occurrence of hyperglycemia, hypercholesterolemia, and hyperLDL-Cemia in adolescents.

Irisin, a hormone-like adipo-myokine, has garnered considerable attention in recent years for its potential impact in metabolic diseases. Its physiological effects are similar to those of thyroid hormones, prompting numerous investigations into potential correlations and interactions between irisin and thyroid function through various in vitro and animal experiments. However, existing studies suggest that the relationship between irisin and thyroid diseases is highly complex and multifaceted. In this paper, we have summarized the research results on serum irisin and thyroid function, providing an overview of advancements and constraints in current research on irisin and thyroid hormones. The aim is to offer insights and directions for future clinical trials in this field.

UNASSIGNED: The lack of physical activity is a common issue in modern society and is considered a major risk factor for various chronic non-communicable diseases. Bioactive factors secreted by skeletal muscle during exercise play a crucial role in inter-organ interactions. Since the concept of \"myokines\" was proposed in 2004, hundreds of regulatory myokines have been identified. Visual analysis of research on exercise-regulated myokines is significant to explore research hotspots and frontiers in this field.
UNASSIGNED: Research literature on exercise-regulated myokines from 2003 to 2023 in the \"Web of Science\" database was used as the data source. Knowledge maps were drawn using \"VOS Viewer, CiteSpace, and R-bibliometrix\" software.
UNASSIGNED: A total of 1,405 papers were included, showing a fluctuating yet slow growth in annual publications. The United States and China led in the number of publications and collaboration networks. Harvard University ranked first with 120 publications. CIBER (centrality 0.16) and the University of California System (centrality 0.16) were pivotal in advancing this field. PEDERSEN BK led author rankings with 41 publications and 1,952 citations. FRONTIERS IN PHYSIOLOGY ranked first among journals with 64 publications and the highest g-index (39), while PLoS One had the highest h-index (25) and most citations (2,599). Key co-cited reference clusters included #1 skeletal muscle dysfunction, #2 obesity, #6 ASCs, and #7 adaptive immunocytes. Pontus Boström\'s paper had a notable citation burst intensity of 77.37. High-frequency keywords were \"exercise\" (509), \"skeletal muscle\" (452), and \"expression\" (293), with long-term keywords such as #0 irisin, #2 insulin resistance, #3 transcription, and #6 physical activity. Recently, keywords like \"physical exercise,\" \"resistance exercise,\" \"aerobic exercise,\" \"insulin,\" and \"oxidative stress\" have emerged.
UNASSIGNED: Research in the field of exercise-regulated myokines shows an overall upward trend. The focus areas include myokines mediated by different types of exercise, the interaction of irisin-mediated muscle with other organs, and the important role of myokine-mediated oxidative stress in exercise simulation.

The purpose of this study was to analyze the mechanism by which irisin affects β-cell pyroptosis in type 2 diabetes mellitus (T2DM). The in vivo T2DM model was established by raised with high-fat diet and intraperitoneally injection of streptozocin. Min6 cells were divided into four groups: negative control (NC), high glucose (HG), HG + irisin, and HG + irisin+3-MA. The cell viability was determined by CCK-8 assay. Dual-luciferase gene reporter assay was conducted to confirm the binding between miR-19b-3p and SOCS3. The expression level of FNDC5 and GSDMD was visualized using the immunofluorescence assay. The protein level of FNDC5, Beclin1, LC3II/I, NLRP3, cleaved-caspase-1, GSDMD-N, STAT3, p-STAT3, and SOCS3 was determined by Western blotting. The secretion of irisin, lactate dehydrogenase (LDH), and insulin was checked by ELISA. In vivo results showed that pathological changes in islet tissues with declined number of β cells, elevated FBG value, decreased FIN and HOMA-β value, elevated autophagy-associated proteins expressions, and activated NLRP3 signaling in T2DM mice, which were dramatically reversed by FNDC5 overexpression. Furthermore, the declined level of miR-19b-3p and p-STAT3, as well as the upregulation of SOCS3, was greatly rescued by FNDC5 overexpression. The in vitro data confirmed the binding site between SOCS3 and miR-19b-3p. SOCS3 was downregulated and p-STAT3 was upregulated in miR-19b-3p mimic-treated Min6 cells. In HG-stimulated Min6 cells, the elevated cell viability, increased production of insulin, decreased release of LDH, and inactivated NLRP3 signaling induced by irisin were abolished by miR-19b-3p inhibitor and STAT3 inhibitor. The increased level of autophagy-related proteins and activated SOCS3/STAT3 axis induced by irisin in HG-stimulated Min6 cells were abolished by miR-19b-3p inhibitor. The inhibitory effect of irisin against NLRP3 signaling in HG-stimulated Min6 cells was abrogated by 3-MA. In conclusion, irisin alleviated the pyroptosis of β cells in T2DM by inhibiting NLRP3 signaling through miR-19b-3p/SOCS3/STAT3 axis mediated autophagy.