A biosensor for D-2-hydroxyglutarate in frozen sections and intraoperative assessment of IDH mutation status.

The oncometabolite D-2-hydroxyglutarate (D-2-HG) has emerged as a valuable biomarker in tumors with isocitrate dehydrogenase (IDH) mutations. Efficient detection methods are required and rapid intraoperative determination of D-2-HG remains a huge challenge. Herein, D-2-HG dehydrogenase from Achromobacter xylosoxidans (AX-D2HGDH) was found to have high substrate specificity. AX-D2HGDH dehydrogenizes D-2-HG and reduces flavin adenine dinucleotide (FAD) bound to the enzyme. Interestingly, the dye resazurin can be taken as another substrate to restore FAD. AX-D2HGDH thus catalyzes a bisubstrate and biproduct reaction: the dehydrogenation of D-2-HG to 2-ketoglutarate and simultaneous reduction of non-fluorescent resazurin to highly fluorescent resorufin. According to steady-state analysis, a ping-pong bi-bi mechanism has been concluded. The Km values for resazurin and D-2-HG were determined as 0.56 µM and 10.93 µM, respectively, suggesting high affinity to both substrates. On the basis, taking AX-D2HGDH and resazurin as recognition and fluorescence transducing element, a D-2-HG biosensor (HGAXR) has been constructed. HGAXR exhibits high sensitivity, accuracy and specificity for D-2-HG in different biological samples. With the aid of HGAXR and the matched low-cost palm-size detecting device, D-2-HG levels in frozen sections of resected brain tumor tissues can be measured in a direct, simple and accurate manner with a fast detection (1-3 min). As the technique of frozen section is familiar to surgeons and pathologists, HGAXR and the portable device can be easily integrated into the current workflow, having potential to provide rapid intraoperative pathology for IDH mutation status and guide decision-making during surgery.

Irisin protected hemopoietic stem cells and improved outcome of severe bone marrow failure.

Acquired aplastic anemia (AA) is a bone marrow failure (BMF) disease, characterized by fatty bone marrow (BM) and BM hypocellularity resulted from auto-immune dysregulated T cells-mediated destruction of BM haemopoietic stem cells (HPSC). The objective of this study was to investigate potential therapeutic effect of irisin, a molecule involved in adipose tissue transition, on AA mouse model. Our results showed that the concentration of irisin in serum was lower in AA patients than in healthy controls, suggesting a role of irisin in the pathogenesis of AA. In the AA mice, irisin administration prolonged the survival rate, prevented or attenuated peripheral pancytopenia, and preserved HPSC in the BM. Moreover, irisin also markedly reduced BM adipogenesis. In vitro results showed that irisin increased both cell proliferation and colony numbers of HPSC. Furthermore, our results demonstrated that irisin upregulated the expression of mitochondrial ATPase Inhibitory Factor 1 (IF1) in HPSC, inhibited the activation of mitochondrial fission protein (DRP1) and enhanced aerobic glycolysis. Taken together, our findings indicate novel roles of irisin in the pathogenesis of AA, and in the protection of HPSC through stimulation of proliferation and regulation of mitochondria function, which provides a proof-of-concept for the application of irisin in AA therapy.

Patient-derived bladder cancer organoid model to predict sensitivity and feasibility of tailored precision therapy.

Background: Bladder cancer is a common and highly heterogeneous malignant tumor with a relatively poor prognosis. Thus, personalized treatment strategies for bladder cancer are essential for improving patient outcomes. Materials and methods: We developed an efficient 3-dimensional in vitro organoid culture system for bladder cancer organoids (BCOs), which maintains the homology with the original patient tumors and the heterogeneity between different individuals. In addition, we constructed chimeric antigen receptor (CAR)-T cells targeting B7H3 and evaluated the antitumor function of CAR-T cells by coculturing them with BCOs. Results: The BCOs closely resembled the characteristics of human tumors and were used to test individual sensitivity to platinum-based drugs and olaparib therapy. Coculture with CAR-T cells demonstrated specific antigen recognition and immune activation, indicating their potential in immunotherapy. Conclusions: Our study highlights the potential of BCOs to facilitate the development of personalized medicine for bladder cancer and improve the efficiency of drug discovery for bladder cancer therapy.

Expression of Recombinant Rat Secretable FNDC5 in Pichia Pastoris and Detection of Its Biological Activity.

FNDC5 is the precursor of the myokine irisin proposed to exhibit favorable metabolic activity, including anti-obesity and anti-diabetes effects. The diversity of FNDC5 transcripts has been reported by several studies, but the role and existence of these transcripts are not well defined. In our previous study, a novel secretable FNDC5 (sFNDC5) isoform lacking the transmembrane region was found in rat INS-1 cells and multiple rat tissues. In the current study, we established a high-yield system for the expression and purification of sFNDC5 in Pichia pastoris, and functional investigations were undertaken using 3T3-L1 cells. We discovered that this new isoform has similar and even stronger biological functions than irisin, which may be due to its more complete structure without cleavage. Hence, we believe that sFNDC5, as the first identified readily secretable derivative, can better induce lipolysis and can potentially prevent obesity and related metabolic diseases.

GLP-1 Induces the Expression of FNDC5 Derivatives That Execute Lipolytic Actions.

Multiple GLP-1-derived therapeutics are clinically used to treat type 2 diabetes and obesity. However, the underlying mechanism of how these drugs regulate the body weight of obese patients remains incompletely understood. Here, we report that the lipolysis effects of GLP-1 on ß cells can depend on its induced expression of fibronectin type III domain containing 5 (FNDC5). The transmembrane FNDC5 is a precursor of the recently identified hormone irisin that possesses a range of bioactivities, including anti-obesity and anti-diabetes. We revealed that GLP-1 upregulates the expression and secretion of FNDC5 in ß cells, while GLP-1 itself fails to activate the lipolysis genes in FNDC5-knockout ß cells. In addition, liraglutide, a clinically used GLP-1 receptor agonist, induced the expression of FNDC5 in mouse pancreas and brain tissues and increased the serum level of secreted FNDC5. Furthermore, we observed the expression of the well-known membrane-associated FNDC5 and a novel, secretable FNDC5 (sFNDC5) isoform in ß cells and multiple rat tissues. Recombinant sFNDC5 stimulated lipolysis of wild type and FNDC5-knockout ß cells. This new isoform further induced lipolysis and browning of adipocytes, and similar to irisin, executed potent anti-obesity activities in an obese mouse model. Overall, our studies provided new mechanistic insights into GLP-1's anti-obesity actions in which GLP-1 induces the secretion of FNDC5 derivatives from its responsive organs that then mediate its anti-obesity activities.

Conditional control of chimeric antigen receptor T-cell activity through a destabilizing domain switch and its chemical ligand.

BACKGROUND AIMS: Despite the impressive efficacy of chimeric antigen receptor (CAR) T-cell therapy, adverse effects, including cytokine release syndrome and neurotoxicity, impede its therapeutic application, thus making the modulation of CAR T-cell activity a priority. The destabilizing domain mutated from Escherichia coli dihydrofolate reductase (DHFR) is inherently unstable and degraded by proteasomes unless it is stabilized by its chemical ligand trimethoprim (TMP), a Food and Drug Administration-approved drug. Here the authors reveal a strategy to modulate CAR T-cell activity at the protein level by employing DHFR and TMP as a chemical switch system. METHODS: First, the system was demonstrated to work in human primary T cells. To introduce the system to CAR T cells, DHFR was genetically fused to the carboxyl terminal of a third-generation CAR molecule targeting CD19 (CD19-CAR), constructing the CD19-CAR-DHFR fusion. RESULTS: The CD19-CAR-DHFR molecule level was shown to be modulated by TMP. Importantly, the incorporation of DHFR had no impact on the recognition specificity and normal function of the CAR molecule. Little adverse effect on cell proliferation and apoptosis was detected. It was proved that TMP could regulate cytokine secretion and the in vitro cytotoxicity of CD19-CAR-DHFR T cells. Furthermore, the in vivo anti-tumor efficacy was demonstrated to be controllable through the manipulation of TMP administration. The approach to control CD19-CAR also succeeded in 19-BBZ(71), another CD19-targeting CAR with a different structure. CONCLUSIONS: The proposed approach based on DHFR and TMP provides a facile strategy to bring CAR T-cell therapy under conditional user control, and the strategy may have the potential to be transplantable.

The Effect of Irisin as a Metabolic Regulator and Its Therapeutic Potential for Obesity.

Obesity is a worldwide health problem due to the imbalance of energy intake and energy expenditure. Irisin, a newly identified exercise-responsive myokine, which is produced by the proteolytic cleavage of fibronectin type III domain-containing protein 5 (FNDC5), has emerged as a promising therapeutic strategy to combat obesity and obesity-related complications. Various studies in mice have shown that irisin could respond to systematic exercise training and promote white-to-brown fat transdifferentiation, but the role and function of irisin in humans are controversial. In this review, we systematically introduced and analyzed the factors that may contribute to these inconsistent results. Furthermore, we also described the potential anti-inflammatory properties of irisin under a variety of inflammatory conditions. Finally, the review discussed the existing unresolved issues and controversies about irisin, including the transcription of the irisin precursor FNDC5 gene in humans, the cleavage site of the yet unknown proteolytic enzyme that cleaves irisin from FNDC5, and the reliability of irisin levels measured with available detection methods.

Fluorescent assay for quantitative analysis of trimethylamine N-oxide.

Trimethylamine N-oxide (TMAO), a gut microbial metabolite involved in cardiovascular and kidney diseases, has great potential as a biomarker, thus making TMAO quantification of great significance. The current assay methods are mainly established on mass spectrometry. However, the classic enzymatic approach is absent, which may be because there is no appropriate single-enzyme reaction. Here, we prepared TMAO demethylase and formaldehyde dehydrogenase and found that these two bacterial enzymes catalyze an efficient coupled reaction that produces NADH from TMAO conversion. With the participation of another enzyme, diaphorase, the multienzymatic coupling system was constructed, which realizes the output of fluorescence signals from TMAO input using resazurin as a probe, thus laying the foundation for fluorescent assay. Through optimization, the sensitivity and specificity were improved. A pretreatment procedure was developed to eliminate formaldehyde that pre-exists with TMAO to avoid an interference effect. Our assay is suitable for quantifying serum TMAO in the range of 2.05-50 µM, covering actual levels in clinical samples, and exhibits a high degree of accordance with mass spectrometry. Therefore, the established fluorometric microplate assay is facile, sensitive and accurate and may enable low-cost and high-throughput analysis of TMAO in clinical laboratory diagnosis.

Focus on Characteristics of COVID-19 with the Special Reference to the Impact of COVID-19 on the Urogenital System.

Coronavirus disease 2019 (COVID-19) is a new infectious disease that first emerged in December 2019. It has infected more than 4,890,000 people in more than 200 countries. This virus can cause progressive respiratory symptoms and severe diseases such as organ failure and death. The complete genomic sequence of SARS-CoV-2 was determined after the virus's identification, and the sequence analysis showed that SARS-CoV-2 strains are genetically similar to SARS-CoV. Angiotensin converting enzyme II is an entry receptor for SARS-CoV-2, which is highly expressed in the kidney, so some patients had symptoms of kidney damage. Here we reviewed the current progress of COVID-19 and its urogenital manifestations. In this rapidly moving field, this review was comprehensive as of May 30, 2020.

An improved clear cell renal cell carcinoma stage prediction model based on gene sets.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma and accounts for cancer-related deaths. Survival rates are very low when the tumor is discovered in the late-stage. Thus, developing an efficient strategy to stratify patients by the stage of the cancer and inner mechanisms that drive the development and progression of cancers is critical in early prevention and treatment. RESULTS: In this study, we developed new strategies to extract important gene features and trained machine learning-based classifiers to predict stages of ccRCC samples. The novelty of our approach is that (i) We improved the feature preprocessing procedure by binning and coding, and increased the stability of data and robustness of the classification model. (ii) We proposed a joint gene selection algorithm by combining the Fast-Correlation-Based Filter (FCBF) search with the information value, the linear correlation coefficient, and variance inflation factor, and removed irrelevant/redundant features. Then the logistic regression-based feature selection method was used to determine influencing factors. (iii) Classification models were developed using machine learning algorithms. This method is evaluated on RNA expression value of clear cell renal cell carcinoma derived from The Cancer Genome Atlas (TCGA). The results showed that the result on the testing set (accuracy of 81.15% and AUC 0.86) outperformed state-of-the-art models (accuracy of 72.64% and AUC 0.81) and a gene set FJL-set was developed, which contained 23 genes, far less than 64. Furthermore, a gene function analysis was used to explore molecular mechanisms that might affect cancer development. CONCLUSIONS: The results suggested that our model can extract more prognostic information, and is worthy of further investigation and validation in order to understand the progression mechanism.

Developing prognostic gene panel of survival time in lung adenocarcinoma patients using machine learning.

BACKGROUND: Transcriptome data generates massive amounts of information that can be used for characterization and prognosis of patient outcomes for many diseases. The goal of our research is to predict the survival time of lung adenocarcinoma patients and improve the accuracy of classifying the long-survival cohort and short-survival cohort. METHODS: We filtered prognostic features related with survival time of lung adenocarcinoma patients by the method of Relief and predicted whether survival time of the patient is >3 years or not-using eight machine learning algorithms (Support Vector Machines, Random Forests, Logistic Regression, Naïve Bayes, Linear Regression, Support Vector Regression (kernel Poly), Support Vector Regression (kernel Linear), and Ridge Regression). Then the best-performed algorithm was chosen to build a predictive model of survival time of lung adenocarcinoma patients. Further, another dataset was used to verify the stability and suitability of this model. We explored the underlying mechanisms of RNA expression changes with the corresponding DNA mutations and DNA methylation patterns in the 22 selected genetic features. RESULTS: The best machine learning algorithm was Naïve Bayes (accuracy=75%, AUC =0.81) using the top 22 genetic features, and this algorithm had the stable and great performance on another dataset as well. The coupled mutation number of the long-survival group (>6 years) was less than the short-survival group (<1 year) in 22 genes (P=0.031). CONCLUSIONS: The expression of gene panel can predict the survival time of lung adenocarcinoma patients using Naïve Bayes. These 22 genes do affect the survival time of lung adenocarcinoma.

Effects of irisin on the differentiation and browning of human visceral white adipocytes.

BACKGROUND: The aim of this study was to explore the effects of irisin on human visceral adipose tissue and adipocytes functions. METHODS: Fresh human visceral white adipose tissues derived from 11 donors were used to examine the effects of irisin on browning, adipogenesis and osteogenesis gene expression, and anti-inflammatory properties. Preadipocytes were also used to examine the effects of irisin on mitochondrial respiration, adipogenic differentiation, and osteogenic differentiation. KEY RESULTS: Irisin significantly increased cellular mitochondrial energy metabolism in differentiated visceral adipocytes. Irisin also increased mRNA levels of transcriptional regulators of brite/beige adipocytes (UCP-1, PGC1α, PRDM16, TMEM26, and CD137) in subcutaneous white adipose tissue but not in visceral/brown adipose tissue or their derived mature adipocytes. In parallel, irisin increased the protein levels of UCP-1 in subcutaneous white adipose tissue, but had no effect on the expression of this protein in visceral white adipose tissue and perirenal brown adipose tissue. However, irisin inhibited adipogenic differentiation, promoted osteogenic differentiation in visceral adipocytes, down-regulated adipogenesis, and upregulated osteogenesis genes expression in visceral fat tissue. Moreover, administration of irisin reduced the expression of proinflammatory marker mRNAs in both visceral and subcutaneous white adipose tissue. CONCLUSIONS: Our data suggest that (1) irisin may increase mitochondrial respiration and glycolysis in visceral adipocytes by a UCP-1 independent pathway; (2) irisin promotes anti-inflammatory activity on fat tissue.

Curcumin induces apoptosis and inhibits angiogenesis in murine malignant mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare form of cancer that is associated with asbestos exposure. Unfortunately, current therapies have limited efficacy. Previous studies have indicated that curcumin exerts antiproliferative and antitumor effects, and has low toxicity. The present study aimed to evaluate the anticancer effects of curcumin on the RN5 MPM cell line. The inhibitory effects of curcumin on cell viability were determined using the sulforhodamine B assay. In addition, cell cycle progression was analyzed by propidium iodide (PI) staining and flow cytometry, and curcumin­induced apoptosis was measured by Annexin V/PI double staining. The translocation of apoptosis-inducing factor (AIF) was assessed by western blotting and immunofluorescence, and the expression levels of the phosphoinositide 3-kinase (PI3K)-AKT serine/threonine kinase (Akt)­mammalian target of rapamycin (mTOR) signaling pathway proteins and mitochondria-associated proteins were evaluated by western blotting. In vivo antitumor effects were evaluated in a subcutaneous murine model. Briefly, tumors were harvested from the mice, and immunohistochemistry was conducted to evaluate cell proliferation, apoptosis and angiogenesis. The results indicated that curcumin inhibited RN5 cell viability and induced apoptotic cell death. In addition the findings suggested that curcumin-induced cell apoptosis occurred via the mitochondrial pathway, and caspase­independent and AIF-dependent pathways. Further analysis revealed that curcumin may act as a PI3K-Akt-mTOR signaling pathway inhibitor by downregulating PI3K, p-Akt, p-mTOR and p-p70 ribosomal protein S6 kinase. Furthermore, curcumin inhibited tumor angiogenesis in vivo. In conclusion, curcumin may be potent enough to be developed as a novel therapeutic agent for the treatment of MPM.

Metformin inhibits proliferation and cytotoxicity and induces apoptosis via AMPK pathway in CD19-chimeric antigen receptor-modified T cells.

BACKGROUND: CD19-chimericantigen receptor (CAR) modified T cells (CD19-CAR T cells) have been well documented to possess potent anti-tumor properties against CD19-expressingleukemia cells. As a traditional medicine, metformin has been widely used to treat type II diabetes mellitus and more recently has become a candidate for the treatment of cancer. However, no report has revealed the direct effect of metformin on CD19-CAR T cell biological function and its underling mechanisms. PURPOSE: The purpose of this research was to explore the effect of metformin on CD19-CAR T cell biological function and the mechanisms involved. METHODS: CD19-CAR T cells proliferation, apoptosis and cytotoxicity were mainly tested by CCK-8 assay, flow cytometry and ELISA. The detection of mechanism primarily used western blot. Bioluminescence imaging is the main application technology of animal studies. RESULTS: In the current study, it was found that metformin inhibited CD19-CAR T cell proliferation and cytotoxicity and induced apoptosis. Furthermore, our study revealed that metformin activated AMPK and suppressed mTOR and HIF1α expression. By using an AMPK inhibitor, compound C, we demonstrated the crucial roles of AMPK in CD19-CAR T cells when they were treated with metformin. Finally, we verified that metformin suppressed the cytotoxicity of CD19-CAR T cell in vivo. CONCLUSION: Taken together, these results indicated that metformin may play an important role in modulating CD19-CAR T cell biological functions in an AMPK-dependent and mTOR/HIF1α-independent manner.

Two-photon fluorescent polydopamine nanodots for CAR-T cell function verification and tumor cell/tissue detection.

Chimeric antigen receptor T-Cell (CAR-T) immunotherapy has been regarded as one of the most promising methods for cancer therapy. How to verify CAR-T cell function and efficiency is very significant for clinical applications. Meanwhile, the identification of tumor cells/tissues is very important for tumor diagnosis and operation. In this study, biocompatible and mass-produced polydopamine (PDA) nanodots have been prepared by a facile method. Oxidized polydopamine (OPDA) can be synthesized by the reaction between PDA and hydrogen peroxide at atmospheric pressure and temperature, and it possesses both one-photon and two-photon fluorescence properties. OPDA nanodots can image living cells for long time periods without mitosis and proliferation inhibition. After ingestion of OPDA nanodots, Raji cells can be used to verify CAR-T cell lethality and efficiency by visualization through fluorescence. The fluorescence intensity change originating from the conversion of PDA into OPDA can function as a signal to identify the tumor and normal cells/tissues because of the different concentration of ROS in tumor cells (high) and normal cells (low). Therefore, the facile synthesis of mass-produced novel organic nanodots with two-photon fluorescence properties will have wide applications in long time living cell imaging without mitosis and proliferation inhibition, CAR-T cell function verification and tumor cell/tissue detection.

Irisin inhibits high glucose-induced endothelial-to-mesenchymal transition and exerts a dose-dependent bidirectional effect on diabetic cardiomyopathy.

Emerging evidence indicates that irisin provides beneficial effects in diabetes. However, whether irisin influences the development of diabetic cardiomyopathy (DCM) remains unclear. Therefore, we investigated the potential role and mechanism of action of irisin in diabetes-induced myocardial dysfunction in mice. Type 1 diabetes was induced in mice by injecting streptozotocin, and the diabetic mice were administered recombinant r-irisin (low or high dose: 0.5 or 1.5 µg/g body weight/day, I.P.) or PBS for 16 weeks. Irisin treatment did not alter blood glucose levels in the diabetic mice. However, the results of echocardiographical and histopathological assays indicated that low-dose irisin treatment alleviated cardiac fibrosis and left ventricular function in the diabetic mice, whereas high-dose irisin failed to mitigate the ventricular function impairment and increased collagen deposition. The potential mechanism underlying the effect of low-dose irisin involved irisin-mediated inhibition of high glucose-induced endothelial-to-mesenchymal transition (EndMT); conversely, high-dose irisin treatment enhanced high glucose-induced MMP expression by stimulating MAPK (p38 and ERK) signalling and cardiac fibroblast proliferation and migration. Low-dose irisin alleviated DCM development by inhibiting high glucose-induced EndMT. By contrast, high-dose irisin disrupted normal MMP expression and induced cardiac fibroblast proliferation and migration, which results in excess collagen deposition. Thus, irisin can inhibit high glucose-induced EndMT and exert a dose-dependent bidirectional effect on DCM.

Irisin-mediated protective effect on LPS-induced acute lung injury via suppressing inflammation and apoptosis of alveolar epithelial cells.

It is considered that the essence of acute lung injury (ALI) is an excessive and uncontrolled inflammatory response in lung, of which mainly is attributed to the release of inflammatory mediators. Recent studies demonstrated that irisin, which is a metabolism associated factor after physical exercise could suppression of inflammation by regulating cellular signaling pathways, however, the underlying molecular mechanism remains to be determined. The present study aimed to reveal the potential mechanism responsible for the anti-inflammatory effects of irisin on LPS-induced acute lung injury in mice and in A549 cells. The results of histopathological changes showed that irisin ameliorated the lung injury that was induced by LPS in time- and dose-dependent manner. QRT-PCR assays demonstrated that irisin suppressed the production of IL-1ß, IL-6, MCP-1 and TNF-α, and western blot assays demonstrated that irisin suppressed apoptosis of ALI. The expression of caspase-3 and Bax were decreased and Bcl-2 was increased by irisin administration. Further study was conducted on nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) using pathways using western blots. The results showed that irisin inhibited reduced LPS-induced activation of MAPK and NF-κB signaling. All results indicated that irisin has protective effect on LPS-induced ALI in mice and in A549 cells. Thus, irisn related with physical exercise may be a potential therapy for the treatment of pulmonary inflammation.

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.

Irisin Inhibits Atherosclerosis by Promoting Endothelial Proliferation Through microRNA126-5p.

BACKGROUND: Irisin is a newly discovered myokine that has been considered a promising candidate for the treatment of cardiovascular disease through improving endothelial function. However, little is known about the role of irisin in the progression of atherosclerosis. METHODS AND RESULTS: We used a carotid partial ligation model of apolipoprotein E-deficient mice fed on a high-cholesterol diet to test the anti-atherosclerosis effect of irisin. Irisin treatment significantly suppressed carotid neointima formation. It was associated with increased endothelial cell proliferation. In addition, irisin promoted human umbilical vein endothelial cell survival via upregulating microRNA126-5p expression through the ERK signaling pathway. Inhibition of microRNA126-5p using the microRNA126-5p inhibitor abolished the prosurvival effect. The same results were demonstrated in vivo as the expression of microRNA126-5p noticeably increased in ligated carotid artery after irisin treatment. Furthermore, in vivo blockade of microRNA126-5p expression using the antagomir abolished the inhibitory effects of irisin on neointima formation, lesional lipid deposition, macrophage area, and the pro-proliferation effects on endothelial cells. CONCLUSIONS: Taken together, our study demonstrates that irisin significantly reduces atherosclerosis in apolipoprotein E-deficient mice via promoting endothelial cell proliferation through microRNA126-5p, which may have a direct therapeutic effect on atherosclerotic diseases.