Irisin reverses platelet derived growth factor-BB-induced vascular smooth muscle cells phenotype modulation through STAT3 signaling pathway

The effect of irisin on the ultrastructure of the thoracic aorta in rat: A morphometric study

BACKGROUND

One of the most recent hormones to be identified and isolated is irisin, extracted from mouse skeletal muscle in 2012. Irisin has been proven to alter blood pressure, which has an impact on blood vessels, enhance endothelial functions, and prevent injury to endothelial cells. The current study aimed to study the effect of irisin on the ultrastructure of the rat thoracic aorta using the transmission electron microscope (TEM).

MATERIALS AND METHODS

Twenty female rats were recruited for this study and divided into a control group (non-injected), and four experimental groups (injected groups) each consisting of 4 rats. The experimental groups were injected intraperitoneally with different doses of irisin (250ng/mL, 500ng/mL, 1000ng/mL, and 2000ng/mL) twice a week for 4weeks. Then, the descending thoracic aorta of all experimental rats were resected and proceeded with imaging.

RESULTS

The results of this study showed a change in the thickness of the tunica intima, internal elastic lamina, elastic lamellae, and external elastic lamina concerning increasing injected irisin concentration. While there was a significant increase in the thickness of tunica media (P<0.0001) and smooth muscle cells (P<0.05). Also, the results showed a significant increase in the number of elastic lamellae in the tunica media (P<0.0001).

CONCLUSION

Irisin had a major impact on the elasticity of the rat thoracic aorta wall, suggesting that it influences the growth factors of the wall and activates smooth muscle cells in addition to endothelial cells.

The emerging roles of irisin in vascular calcification

Vascular calcification is a common accompanying pathological change in many chronic diseases, which is caused by calcium deposition in the blood vessel wall and leads to abnormal blood vessel function. With the progress of medical technology, the diagnosis rate of vascular calcification has explosively increased. However, due to its mechanism's complexity, no effective drug can relieve or even reverse vascular calcification. Irisin is a myogenic cytokine regulating adipose tissue browning, energy metabolism, glucose metabolism, and other physiological processes. Previous studies have shown that irisin could serve as a predictor for vascular calcification, and protect against hypertension, diabetes, chronic kidney disease, and other risk factors for vascular calcification. In terms of mechanism, it improves vascular endothelial dysfunction and phenotypic transformation of vascular smooth muscle cells. All the above evidence suggests that irisin plays a predictive and protective role in vascular calcification. In this review, we summarize the association of irisin to the related risk factors for vascular calcification and mainly explore the role of irisin in vascular calcification.

Receptor Tyrosine Kinase: Still an Interesting Target to Inhibit the Proliferation of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) proliferation is a critical event that contributes to the pathogenesis of vascular remodeling such as hypertension, restenosis, and pulmonary hypertension. Increasing evidences have revealed that VSMCs proliferation is associated with the activation of receptor tyrosine kinases (RTKs) by their ligands, including the insulin-like growth factor receptor (IGFR), fibroblast growth factor receptor (FGFR), epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR). Moreover, some receptor tyrosinase inhibitors (TKIs) have been found and can prevent VSMCs proliferation to attenuate vascular remodeling. Therefore, this review will describe recent research progress on the role of RTKs and their inhibitors in controlling VSMCs proliferation, which helps to better understand the function of VSMCs proliferation in cardiovascular events and is beneficial for the prevention and treatment of vascular disease.

Effects of the exercise-inducible myokine irisin on proliferation and malignant properties of ovarian cancer cells through the HIF-1 α signaling pathway

Exercise has been shown to be associated with reduced risk and improving outcomes of several types of cancers. Irisin -a novel exercise-related myokine- has been proposed to exert beneficial effects in metabolic disorders including cancer. No previous studies have investigated whether irisin may regulate malignant characteristics of ovarian cancer cell lines. In the present study, we aimed to explore the effect of irisin on viability and proliferation of ovarian cancer cells which was examined by MTT assay. Then, we evaluated the migratory and invasive abilities of the cells via transwell assays. Moreover, the percentage of apoptosis induction was determined by flow cytometry. Furthermore, the mRNA expression level of genes related to the aerobic respiration (HIF-1α, c-Myc, LDHA, PDK1 and VEGF) was detected by real-time PCR. Our data revealed that irisin treatment significantly attenuated the proliferation, migration and invasion of ovarian cancer cells. Additionally, irisin induced apoptosis in ovarian cancer cells. We also observed that irisin regulated the expression of genes involved in aerobic respiration of ovarian cancer cells. Our results indicated that irisin may play a crucial role in inhibition of cell growth and malignant characteristics of ovarian cancer. These findings may open up avenues for future studies to identify the further therapeutic use of irisin in ovarian cancer management.

The Emerging Role of Irisin in Cardiovascular Diseases

Irisin, a novel hormone like polypeptide, is cleaved and secreted by an unknown protease from a membrane‐spanning protein, FNDC5 (fibronectin type III domain‐containing protein 5). The current knowledge on the biological functions of irisin includes browning white adipose tissue, regulating insulin use, and anti‐inflammatory and antioxidative properties. Dysfunction of irisin has shown to be involved in cardiovascular diseases such as hypertension, coronary artery disease, myocardial infarction, and myocardial ischemia–reperfusion injury. Moreover, irisin gene variants are also associated with cardiovascular diseases. In this review, we discuss the current knowledge on irisin‐mediated regulatory mechanisms and their roles in the pathogenesis of cardiovascular diseases.

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.

The Physiological Role of Irisin in the Regulation of Muscle Glucose Homeostasis

Irisin is a myokine that primarily targets adipose tissue, where it increases energy expenditure and contributes to the beneficial effects of exercise through the browning of white adipose tissue. As our knowledge has deepened in recent years, muscle has been found to be a major target organ for irisin as well. Several studies have attempted to characterize the role of irisin in muscle to improve glucose metabolism through mechanisms such as reducing insulin resistance. Although they are very intriguing reports, some contradictory results make it difficult to grasp the whole picture of the action of irisin on muscle. In this review, we attempted to organize the current knowledge of the role of irisin in muscle glucose metabolism. We discussed the direct effects of irisin on glucose metabolism in three types of muscle, that is, skeletal muscle, smooth muscle, and the myocardium. We also describe irisin’s effects on mitochondria and its interactions with other hormones. Furthermore, to consider the relationship between the irisin-induced improvement of glucose metabolism in muscle and systemic disorders of glucose metabolism, we reviewed the results from animal interventional studies and human clinical studies.

PDGFBB promotes proliferation and migration via regulating miR-1181/STAT3 axis in human pulmonary arterial smooth muscle cells

Platelet-derived growth factor (PDGF) can induce hyperproliferation of pulmonary artery smooth muscle cells (PASMCs), which is a key causative factor to the occurrence and progression of pulmonary arterial hypertension (PAH). We previously identified that miR-1181 is significantly downregulated by PDGFBB in human PASMCs. In this work, we further explore the function of miR-1181 and underlying regulatory mechanisms in PDGF-induced PASMCs. First, the expression pattern of miR-1181 was characterized under PDGFBB treatment, and PDGF receptor/PKCβ signaling was found to repress miR-1181 expression. Then, gain- and loss-of-function experiments were respectively conducted and revealed the prominent role of miR-1181 in inhibiting PASMC proliferation and migration. Flow cytometry analysis suggested that miR-1181 regulated the PASMC proliferation through influencing the cell cycle transition from G0/G1 to S phase. Moreover, we exhibited that miR-1181 targeting STAT3 formed a regulatory axis to modulate PASMC proliferation. Finally, serum miR-1181 expression was also observed to be reduced in adult and newborn patients with PAH. Overall, this study provides novel findings that the miR-1181/STAT3 axis mediated PDGFBB-induced dysfunction in human PASMCs, implying a potential use of miR-1181 as a therapeutic and diagnostic candidate for the vascular remodeling diseases.

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 reverses the IL-6 induced epithelial-mesenchymal transition in osteosarcoma cell migration and invasion through the STAT3/Snail signaling pathway

As a novel discovered myokine, irisin is considered to be a promising candidate for the treatment of metabolic disorders and cancer. However, little is known about the anti-metastasic effect of irisin on osteosarcoma cells and its underlying mechanisms. In the present study, we aimed to explore the effect of irisin on the migration and invasion of osteosarcoma cells and the underlying mechanisms involved. Viability and proliferation of osteosarcoma cells were examined by MTT assay. Then, by using scratch wound healing assay and Transwell assays, we evaluated migratory and invasive ability of the cells, respectively. Moreover, the expression of epithelial-to-mesenchymal transition (EMT) markers were determined by qPCR, western blot and immunofluorescence staining after treatment with IL-6 and irisin. Furthermore, the expression of ERK, p38, STAT3 and Snail were detected by western blot analysis. Finally, an inhibitor of STAT3, WP1066 was applied to testify the effect of irisin on the expression of EMT markers and Snail. It was found that irisin treatment significantly suppressed the proliferation, migration and invasion of osteosarcoma cells. Furthermore, irisin reversed the IL-6-induced epithelial-mesenchymal transition (EMT) in osteosarcoma cells by regulating the expression of E-cadherin, N-cadherin, vimentin, fibronectin, MMP-2, MMP-7 and MMP-9. In addition, irisin suppressed the IL-6-activated phosphorylation of STAT3 and the expression of Snail in osteosarcoma cells. Finally, blockade of STAT3 by WP1066 (a STAT3 inhibitor) further enhanced the effect of irisin on the EMT and Snail expression in osteosarcoma cells. Collectively, our findings revealed that irisin may play a critical role in the IL-6-induced EMT of osteosarcoma cells via the STAT3/Snail signaling pathway.

Irisin suppresses the migration, proliferation, and invasion of lung cancer cells via inhibition of epithelial-to-mesenchymal transition

Irisin is involved in promoting metabolism, immune regulation, and affects chronic inflammation in many systemic diseases, including gastric cancer. However, the role of irisin in lung cancer is not well characterized. To determine whether irisin has a protective effect against lung cancer, we cultured A549 and NCI-H446 lung cancer cells and treated them with irisin. We detected the proliferation by MTT assay, and assessed the migration and invasion of the cells by scratch wound healing assay and Tran-swell assay. The expression levels of epithelial-to-mesenchymal transition (EMT) markers and the related signaling pathways were detected by western blot analysis. Meanwhile, an inhibitor of PI3K was used to investigate the effect of irsin. Finally, the expression of Snail was detected. We demonstrated that irisin inhibits the proliferation, migration, and invasion of lung cancer cells, and has a novel role in mediating the PI3K/AKT pathway in the cells. Irisin can reverse the activity of EMT and inhibit the expression of Snail via mediating the PI3K/AKT pathway, which is a key regulator of Snail. These results revealed that irisin inhibited EMT and reduced the invasion of lung cancer cells via the PI3K/AKT/Snail pathway.