Dual functions of angiopoietin-like protein 2 signaling in tumor progression and anti-tumor immunity.

Angiopoietin-like protein 2 (ANGPTL2) is a secreted glycoprotein homologous to angiopoietins. Previous studies suggest that tumor cell-derived ANGPTL2 has tumor-promoting function. Here, we conducted mechanistic analysis comparing ANGPTL2 function in cancer progression in a murine syngeneic model of melanoma and a mouse model of translocation renal cell carcinoma (tRCC). ANGPTL2 deficiency in tumor cells slowed tRCC progression, supporting a tumor-promoting role. However, systemic ablation of ANGPTL2 accelerated tRCC progression, supporting a tumor-suppressing role. The syngeneic model also demonstrated a tumor-suppressing role of ANGPTL2 in host tumor microenvironmental cells. Furthermore, the syngeneic model showed that PDGFRα+ fibroblasts in the tumor microenvironment express abundant ANGPTL2 and contribute to tumor suppression. Moreover, host ANGPTL2 facilitates CD8+ T-cell cross-priming and enhances anti-tumor immune responses. Importantly, ANGPTL2 activates dendritic cells through PIR-B-NOTCH signaling and enhances tumor vaccine efficacy. Our study provides strong evidence that ANGPTL2 can function in either tumor promotion or suppression, depending on what cell type it is expressed in.

High throughput functional profiling of genes at intraocular pressure loci reveals distinct networks for glaucoma.

INTRODUCTION: Primary open angle glaucoma (POAG) is a leading cause of blindness globally. Characterized by progressive retinal ganglion cell degeneration, the precise pathogenesis remains unknown. Genome-wide association studies (GWAS) have uncovered many genetic variants associated with elevated intraocular pressure (IOP), one of the key risk factors for POAG. We aimed to identify genetic and morphological variation that can be attributed to trabecular meshwork cell (TMC) dysfunction and raised IOP in POAG. METHODS: 62 genes across 55 loci were knocked-out in a primary human TMC line. Each knockout group, including five non-targeting control groups, underwent single-cell RNA-sequencing (scRNA-seq) for differentially-expressed gene (DEG) analysis. Multiplexed fluorescence coupled with CellProfiler image analysis allowed for single-cell morphological profiling. RESULTS: Many gene knockouts invoked DEGs relating to matrix metalloproteinases and interferon-induced proteins. We have prioritized genes at four loci of interest to identify gene knockouts that may contribute to the pathogenesis of POAG, including ANGPTL2, LMX1B, CAV1, and KREMEN1. Three genetic networks of gene knockouts with similar transcriptomic profiles were identified, suggesting a synergistic function in trabecular meshwork cell physiology. TEK knockout caused significant upregulation of nuclear granularity on morphological analysis, while knockout of TRIOBP, TMCO1 and PLEKHA7 increased granularity and intensity of actin and the cell-membrane. CONCLUSION: High-throughput analysis of cellular structure and function through multiplex fluorescent single-cell analysis and scRNA-seq assays enabled the direct study of genetic perturbations at the single-cell resolution. This work provides a framework for investigating the role of genes in the pathogenesis of glaucoma and heterogenous diseases with a strong genetic basis.

ANGPTL2 knockdown induces autophagy to relieve alveolar macrophage pyroptosis by reducing LILRB2-mediated inhibition of TREM2.

Acute lung injury (ALI) is featured with a robust inflammatory response. Angiopoietin-like protein 2 (ANGPTL2), a pro-inflammatory protein, is complicated with various disorders. However, the role of ANGPTL2 in ALI remains to be further explored. The mice and MH-S cells were administrated with lipopolysaccharide (LPS) to evoke the lung injury in vivo and in vitro. The role and mechanism of ANGPTL was investigated by haematoxylin-eosin, measurement of wet/dry ratio, cell count, terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling, reverse transcription quantitative polymerase chain reaction, immunofluorescence, enzyme-linked immunosorbent assay, detection of autophagic flux and western blot assays. The level of ANGPTL2 was upregulated in lung injury. Knockout of ANGPTL2 alleviated LPS-induced pathological symptoms, reduced pulmonary wet/dry weight ratio, the numbers of total cells and neutrophils in BALF, apoptosis rate and the release of pro-inflammatory mediators, and modulated polarization of alveolar macrophages in mice. Knockdown of ANGPTL2 downregulated the level of pyroptosis indicators, and elevated the level of autophagy in LPS-induced MH-S cells. Besides, downregulation of ANGPTL2 reversed the LPS-induced the expression of leukocyte immunoglobulin (Ig)-like receptor B2 (LILRB2) and triggering receptor expressed on myeloid cells 2 (TREM2), which was reversed by the overexpression of LILRB2. Importantly, knockdown of TREM2 reversed the levels of autophagy- and pyroptosis-involved proteins, and the contents of pro-inflammatory factors in LPS-induced MH-S cells transfected with si ANGPTL2, which was further inverted with the treatment of rapamycin. Therefore, ANGPTL2 silencing enhanced autophagy to alleviate alveolar macrophage pyroptosis via reducing LILRB2-mediated inhibition of TREM2.

Endothelial cell-derived angiopoietin-like protein 2 supports hematopoietic stem cell activities in bone marrow niches.

Bone marrow niche cells have been reported to fine-tune hematopoietic stem cell (HSC) stemness via direct interaction or secreted components. Nevertheless, how niche cells control HSC activities remains largely unknown. We previously showed that angiopoietin-like protein 2 (ANGPTL2) can support the ex vivo expansion of HSCs by binding to human leukocyte immunoglobulin-like receptor B2. However, how ANGPTL2 from specific niche cell types regulates HSC activities under physiological conditions is still not clear. Herein, we generated an Angptl2-flox/flox transgenic mouse line and conditionally deleted Angptl2 expression in several niche cells, including Cdh5+ or Tie2+ endothelial cells, Prx1+ mesenchymal stem cells, and Pf4+ megakaryocytes, to evaluate its role in the regulation of HSC fate. Interestingly, we demonstrated that only endothelial cell-derived ANGPTL2 and not ANGPTL2 from other niche cell types plays important roles in supporting repopulation capacity, quiescent status, and niche localization. Mechanistically, ANGPTL2 enhances peroxisome-proliferator-activated receptor D (PPARD) expression to transactivate G0s2 to sustain the perinuclear localization of nucleolin to prevent HSCs from entering the cell cycle. These findings reveal that endothelial cell-derived ANGPTL2 serves as a critical niche component to maintain HSC stemness, which may benefit the understanding of stem cell biology in bone marrow niches and the development of a unique strategy for the ex vivo expansion of HSCs.

Menstrual blood-derived stromal cells: insights into their secretome in acute hypoxia conditions.

BACKGROUND: Despite constant advances in regenerative medicine, the closure of chronic wounds is still challenging. Therapeutic approaches using locally administered MSCs have been considered a promising option. However, the viability of these cells is seriously threatened by acute hypoxic stress linked to wound healing. In this work, we aimed to study the tolerance of Menstrual blood-derived stromal cells (MenSCs) to acute hypoxia and their therapeutic paracrine effect. METHODS: Isolated MenSCs were phenotypically characterized and evaluated in terms of proliferation, viability, and gene expression, under acute hypoxia (AH) compared with conventional cultured condition or normoxia (N). A step further, the secretome of MenSCs under acute hypoxia was analyzed with respect to their miRNAs content and by in vitro functional assays. For the analysis of differences between the two groups, Student's t-test was performed and one-way ANOVA and Tukey's multiple comparisons test for multiple groups were used. RESULTS: Our results revealed that the viability of MenSCs was not affected under acute hypoxia, although proliferation rate slowed down. Gene analysis revealed 5 up-regulated (BNIP3, ANGPTL4, IL6, IL1B, and PDK1) and 4 down-regulated genes (IDO1, HMOX1, ANGPTL2, and HGF) in AH compared to N. Global gene expression analysis revealed a decrease in the gene ontology functions of migration and wound response with respect to the normoxic condition. In contrast, functions such as angiogenesis were enriched under the AH condition. Regarding the secretome analysis, two miRNAs involved in angiogenic processes (hsa-miR-148a-3p and hsa-miR-378a-3p), were significantly up-expressed when compared to the normoxic condition, being MYC gene, the unique target of both. Functional assays on HUVECs revealed a potential pro-angiogenic capacity of MenSCs cultured in both oxygen conditions (N and AH) based on the wound closure and tube formation results of their released paracrine factors. However, when compared to normoxia, the paracrine factors of MenSCs under acute hypoxia slightly reduced the proliferation, migration, and in vitro wound closure of HUVECs. CONCLUSIONS: MenSC exhibited a good survival capacity under acute hypoxic conditions as well as beneficial properties applicable in the field of tissue regeneration through their secretome, which makes them a potential cell source for wound healing interventions.

ANGPTL2 Deletion Attenuates Neuroinflammation and Cognitive Dysfunction Induced by Isoflurane in Aged Mice through Modulating MAPK Pathway.

Postoperative cognitive dysfunction (POCD) is a well-known complication after surgery with cognitive impairments. Angiopoietin-like protein 2 (ANGPTL2) has been found to be associated with inflammation. However, the role of ANGPTL2 in inflammation of POCD is unclear. Here, mice were subjected into isoflurane anesthesia. It was demonstrated that isoflurane increased ANGPTL2 expression and promoted pathological change in brain tissues. However, downregulation of ANGPTL2 alleviated the pathological change and elevated learning and memory abilities, improving isoflurane-induced cognitive dysfunction in mice. In addition, isoflurane-induced cell apoptosis and inflammation were repressed via ANGPTL2 knockdown in mice. Downregulation of ANGPTL2 was also verified to suppress isoflurane-induced microglial activation, evidenced by a decrease of Iba1 and CD86 expressions and an increase of CD206 expression. Further, the isoflurane-induced MAPK signaling pathway was repressed through downregulation of ANGPTL2 in mice. In conclusion, this study proved that downregulation of ANGPTL2 attenuated isoflurane-induced neuroinflammation and cognitive dysfunction in mice via modulating the MAPK pathway, which provided a new therapeutic target for POCD.

Angptl2 gene knockdown is critical for abolishing angiotensin II-induced vascular smooth muscle cell proliferation and migration.

Angiopoietin-like 2 (Angptl2) is reported to be correlated with cardiovascular diseases, but its role in hypertension remains unclear. This study aimed to investigate the role and potential mechanism of Angptl2 in hypertension. Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were used to detect the expression of Angptl2. Angiotensin II (Ang II) stimulates vascular smooth muscle cells (VSMCs) to mimic hypertension in vitro. Cell proliferation, migration, and invasion abilities were determined using CCK-8, cell colony formation, wound healing, and transwell assays, respectively. The cell cycle distribution was detected by flow cytometry. The expression of Ki67 was determined by immunofluorescence, and protein expression was measured using western blotting. Angptl2 was found to be elevated in hypertensive rats in vivo and in VSMCs upon Ang II stimulation in vitro. Angptl2 knockdown suppressed cell proliferation, colony formation, cell migration, and invasion as well as the downregulation of Ki67. Additionally, Angptl2 knockdown hindered cell cycle progression and downregulated protein expression of CDK2/4 and cyclin D1, but upregulated p21 expression. Furthermore, Angptl2 knockdown inhibited activation of the NLRP3 inflammasome. Our findings suggest that Angptl2 knockdown suppresses VSMC proliferation, migration, and invasion induced by Ang II. Angptl2 may be a new target for vascular remodeling in hypertension.

Efficient expansion of mouse hematopoietic stem cells ex vivo by membrane anchored Angptl2.

Hematopoietic stem cell (HSC) transplantation represents an important curative therapy for numerous hematological and immune diseases. Many efforts have been applied to achieve attainable ex vivo HSC expansion. We previously showed that angiopoietin-like proteins 2 (Angptl2) binds and activates the immune inhibitory receptor human leukocyte immunoglobulin (Ig)-like receptor B2 (LILRB2) to support the expansion of HSC. However, soluble Angptl2 is unstable and the downstream signaling would be attenuated by ligand-binding triggered receptor endocytosis, compromising the potential of Angptl2 to expand HSCs. We proposed that membrane anchored Angptl2 will overcome these limitations. In this study, we constructed the C-terminal and N-terminal anchored membrane Angptl2 (Cm-Angptl2 and Nm-Angptl2) by adding a transmembrane domain at the C-terminal or an anchor sequence at the N-terminal respectively. Both forms of Angptl2 showed efficient expression on the surface of feeder cells. Nm-Angptl2, but not Cm-Angptl2, induces a potent activation of LILRB2 reporter, indicating the fibronectin (FBN) domain at the C-terminus of Angptl2 is essential to stimulate LILRB2 signaling. Compared to soluble Angptl2, Nm-Angptl2 displays higher activities to activate LILRB2 reporter, and to promote the expansion of mouse HSCs as determined by transplantation and limiting dilution assay. Our study revealed the importance of FBN domain for Angptl2 to activate LILRB2 and demonstrated that Nm-Angptl2 have enhanced activities than the soluble protein in LILRB2 activation and HSC expansion, providing a strategy to explore the mode of ligand induced receptor signaling, and an optimized approach to expand HSCs ex vivo.

Biomarkers of endothelial activation and dysfunction in cardiovascular diseases.

Endothelial activation and dysfunction is an important contributor to atherosclerosis, cardiovascular diseases and cardiorenal syndrome. Endothelial dysfunction is also linked with metabolic syndrome and type II diabetes. The search for specific and sensitive biomarkers of endothelial activation and dysfunction may have important clinical implications. This review pinpoints the differences in biomarkers between endothelial activation and endothelial dysfunction in cardiovascular diseases, and then briefly describes the most relevant biomarkers of endothelial activation. Biomarkers of endothelial activation include endothelial adhesion molecules, cytokines, C-reactive protein, CD62E+/E-selectin activated endothelial microparticles, oxidation of low density lipoproteins, asymmetric dimethylarginine and endocan. This review also presents an update on the novel biomarkers of endothelial dysfunction, such as matrix metalloproteinases (e.g., MMP-7, MMP-9), ANGPTL2, endogdlin, annexin V+ endothelial apoptotic microparticles, and serum homocysteine. Finally, this review emphasizes the limitations of biomarkers of endothelial activation and dysfunction in clinical setting.

ANGPTL2 expression in the intestinal stem cell niche controls epithelial regeneration and homeostasis.

The intestinal epithelium continually self-renews and can rapidly regenerate after damage. Dysregulation of intestinal epithelial homeostasis leads to severe inflammatory bowel disease. Additionally, aberrant signaling by the secreted protein angiopoietin-like protein 2 (ANGPTL2) causes chronic inflammation in a variety of diseases. However, little is known about the physiologic role of ANGPTL2 in normal tissue homeostasis and during wound repair following injury. Here, we assessed ANGPTL2 function in intestinal physiology and disease in vivo Although intestinal development proceeded normally in Angptl2-deficient mice, expression levels of the intestinal stem cell (ISC) marker gene Lgr5 decreased, which was associated with decreased transcriptional activity of ß-catenin in Angptl2-deficient mice. Epithelial regeneration after injury was significantly impaired in Angptl2-deficient relative to wild-type mice. ANGPTL2 was expressed and functioned within the mesenchymal compartment cells known as intestinal subepithelial myofibroblasts (ISEMFs). ANGPTL2 derived from ISEMFs maintained the intestinal stem cell niche by modulating levels of competing signaling between bone morphogenetic protein (BMP) and ß-catenin. These results support the importance of ANGPTL2 in the stem cell niche in regulating stemness and epithelial wound healing in the intestine.

Angiopoietin-like protein 2 decreases peritoneal metastasis of ovarian cancer cells by suppressing anoikis resistance.

Peritoneal metastasis is a common mode of spread of ovarian cancer. Despite therapeutic advances, some patients have intractable peritoneal metastasis. Therefore, in-depth characterization of the molecular mechanism of peritoneal metastasis is a key imperative. Angiopoietin-like protein 2 (ANGPTL2) is an inflammatory factor which activates NF-κB signaling and plays an important role in the pathogenesis of various inflammatory diseases including cancers, such as lung and breast cancer. In this study, we examined the role of ANGPTL2 in ovarian cancer peritoneal metastasis. We observed no difference of cell proliferation between ANGPTL2-expressing and control cells. In the mouse intraperitoneal xenograft model, formation of peritoneal metastasis by ANGPTL2-expressing cells was significantly decreased compared to control. In the in vitro analysis, the expressions of integrin α5ß1, α6, and ß4, but not those of αvß3, α3, α4, and ß1, were significantly decreased in ANGPTL2-expressing cells compared to control cells. ANGPTL2-expressing cells showed significantly inhibited adherence to laminin compared to control. In addition, we observed upregulation of anoikis (a form of programmed cell death occurring under an anchorage-independent condition) and significant decrease in the expression of Bcl-2 in ANGPTL2-expressing cells as compared to control cells. These results suggest that ANGPTL2 expression in ovarian cancer cells represses peritoneal metastasis by suppressing anoikis resistance.

Characterization of Tumor Blood Vasculature Expression of Human Invasive Bladder Cancer by Laser Capture Microdissection and Transcriptional Profiling.

Tumor-associated blood vessels differ from normal vessels and play key roles in tumor progression. We aimed to identify biomolecules that are expressed differentially in human bladder cancer-associated blood vessels to find novel biomarkers and mechanisms involved in tumor-associated angiogenesis. The transcriptome of tumor blood vasculature from human invasive bladder carcinoma (I-BLCA) and normal bladder tissue vasculature was compared using differential expression and unsupervised hierarchical clustering analyses. Pathway analysis identified up-regulation of genes involved in the proliferation, cell cycle, angiogenesis, inflammation, and transforming growth factor-ß signaling in tumor blood vasculature. A common consensus gene expression signature was identified between bladder cancer tumor blood vasculature with tumor blood vasculature of other solid cancers, which correlated with the overall survival of patients with several of the solid cancers investigated in The Cancer Genome Atlas data set. In bladder tumor blood vasculature, the secreted factor angiopoietin-like protein 2 (ANGPTL2), was confirmed to be up-regulated by quantitative RT-PCR and immunohistochemical staining. The up-regulation of ANGPTL2 in plasma was also observed in non-invasive bladder carcinoma and I-BLCA. We semiquantitatively analyzed expression of ANGPTL2 in tissue microarrays from I-BLCA and surprisingly found an opposite correlation between staining intensity and progression-free survival. Our results indicate that ANGPTL2 might serve as a potential biomarker to predict progression-free survival in I-BLCA.

Blocking angiotensin 2 receptor attenuates diabetic nephropathy via mitigating ANGPTL2/TL4/NF-κB expression.

BACKGROUND: Diabetic nephropathy (DN) is a consequence of diabetes mellitus (DM) and is associated with early changes in renal angiotensin II (ANG II). These changes were evaluated using ANG II blocker valsartan early from week two of diabetes (experiment I, renoprotective) and late from week nine of diabetes (experiment II, renotherapeutic) to the end of both experiments at week twelve. METHODS AND RESULTS: In both experiments, adult male Wister rats were divided into (i) vehicle group; (ii) valsartan received oral 30 mg/Kg/day; (iii) diabetic received single 50 mg/Kg intraperitoneal streptozotocin injection; (iv) renoprotection, diabetic rats received valsartan treated in experiments I and II. DM effects on urine albumin excretion, blood pressure, and renal ANG II were measured. Urinary nephrin, kidney injury molecule-1 (KIM-1), renal angiopoietin-like protein 2 (ANGPTL2), and toll-like receptor 4 (TLR 4) mRNA expression were tested. DM-initiated fibrotic markers integrin, α-smooth muscle actin expression, and collagen IV and apoptotic protein caspase 3 were tested. DM induced early changes starting from week four in the tested variables. At week twelve, in both experiments, valsartan intervention showed a significant reduction in ANG II, ANGPTL2, TLR 4 and integrin expression and improvement in albuminuria, blood pressure, urinary biomarkers, fibrotic and apoptotic markers. CONCLUSIONS: Changes leading to DN starts early in the disease course and ANG II reduction decreased the expression of ANGPTL2 and integrin which preserve the glomerular barrier. Blocking ANG II was able to decrease TLR 4 and inflammatory cytokines leading to decreasing DN.

Vitreous levels of vascular endothelial growth factor, stromal cell-derived factor-1α, and angiopoietin-like protein 2 in patients with active proliferative diabetic retinopathy.

PURPOSE: To determine the vitreous levels of vascular endothelial growth factor (VEGF), stromal cell-derived factor-1α (SDF-1α) and angiopoietin-like protein 2 (ANGPTL2) in patients with active proliferative diabetic retinopathy (PDR), and to ascertain their contribution on different clinical presentation of active PDR. METHODS: This case-control study included 31 eyes with active PDR and 10 eyes with idiopathic macular hole (MH) (control group). Eyes with active PDR were divided into three subgroups: vitreous hemorrhage (VH), tractional retinal detachment (TRD) caused by active fibrovascular membrane (FVM), and coexistence of VH and TRD with FVM. Vitreous samples obtained during vitrectomy were analyzed for concentrations of VEGF, SDF-1α, and ANGPTL2. RESULTS: Vitreous level of VEGF (2021 (168-6550) pg/ml vs 110.1 (74.5-236) pg/ml), SDF-1α (517 (194-1044) pg/ml vs 388 (320-535) pg/ml), and ANGPTL2 (725 (131-1590) ng/ml vs 196 (75.9-437) ng/ml) were significantly higher in eyes with active PDR than in control group (p < 0.001, p = 0.002, and p < 0.001, respectively). The concentrations of these meaditors in each active PDR subgroups were also significantly higher than control group (p < 0.05). The vitreous level of ANGPTL2 was significantly higher in eyes with TRD caused by FVM (1033 ± 401 ng/ml) than in eyes with VH (561 ± 237 ng/ml; p = 0.008). CONCLUSION: High levels of SDF-1α, ANGPTL2 and particularly VEGF seem to be associated with PDR. Since the vitreous levels of ANGPTL2 tend to be higher in eyes with active fibrovascular tractional detachment, vitreous levels of this chemokine seem to be affected by the clinical presentation of vascularly active PDR eyes.

JAB1 Promotes High Glucose-Induced Inflammation and Extracellular Matrix Deposition in Glomerular Mesangial Cells by Regulating Angiopoietin-Like Protein 2.

Diabetic or hyperglycaemic conditions stimulate the inflammatory response, excessive accumulation of extracellular matrix, and result in glomerulosclerosis, a scarring process of diabetic nephropathy. c-Jun activation domain-binding protein 1 (JAB1) functions as a regulator of pathways involved in cellular apoptosis and proliferation. The role of JAB1 in diabetic nephropathy was investigated in this study. Firstly, glomerular mesangial cells (GMCs) were treated with high glucose, and high glucose conditions induced up-regulation of JAB1 in the GMCs. Moreover, IL-6, TNF-α, MCP-1, and IL-1ß were also elevated in high glucose-induced GMCs. Secondly, silencing of JAB1 reduced the levels of IL-6, TNF-α, MCP-1, and IL-1ß in high glucose-induced GMCs. In addition, silencing of JAB1 attenuated the high glucose-induced decrease of superoxide dismutase (SOD) and the increase of reactive oxygen species (ROS) and malondialdehyde (MDA). The increased TGF-ß1, collagen I, collagen IV, and fibronectin levels in high glucose-induced GMCs were restored by knockdown of JAB1. Thirdly, angiopoietin-like protein 2 (ANGPTL2) expression was reduced by JAB1. Over-expression of ANGPTL2 weakened the JAB1 silence-induced decrease of IL-6, TNF-α, MCP-1, IL-1ß, TGF-ß1, collagen I, collagen IV, and fibronectin. In conclusion, silencing of JAB1 reduced extracellular matrix deposition and suppressed inflammation in high glucose-induced GMCs through down-regulation of ANGPTL2.

Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence.

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

Serum Angiopoietin-Like Protein 2 and NT-Pro BNP Levels and Their Associated Factors in Patients with Chronic Heart Failure Participating in a Phase III Cardiac Rehabilitation Program.

Angiopoietin-like protein 2 (ANGPTL2) promotes chronic inflammation and plays a key role in the pathogenesis of heart failure. Cardiac rehabilitation (CR) is an integral component of heart failure management and has been shown to have anti-inflammatory effects. However, ANGPTL2 concentration in chronic heart failure patients undergoing CR has not been evaluated. This study aimed to investigate serum ANGPTL2 levels and their associated factors and compare the results with those of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with chronic heart failure undergoing phase III CR.A total of 56 patients were enrolled. Clinical characteristics including body composition, grip strength, exercise tolerance, duration of CR, blood counts and biochemistry, and echocardiographic parameters were evaluated for their association with serum ANGPTL2 and NT-proBNP levels.The median (first and third quartiles) value of ANGPTL2 was 4.05 (2.70-5.57) ng/mL. Clinical parameters that correlated with serum ANGPTL2 levels were body weight, body mass index, body fat mass, body fat percentage, anaerobic threshold (AT), C-reactive protein, and total protein (TP), which were mostly distinct from those that correlated with serum NT-proBNP levels. A multivariate analysis revealed that AT and TP were independent factors related to ANGPTL2 levels, whereas age, left ventricular ejection fraction, and left atrial dimension were independently related to NT-proBNP levels.These observations suggest that CR increases the exercise tolerance and exhibits anti-inflammatory effects simultaneously, and this situation is reflected by decreased serum ANGPLT2 and TP levels. ANGPTL2 may be a useful marker of inflammation and impaired exercise tolerance in patients with chronic heart failure.

Shotgun Proteomics of Isolated Urinary Extracellular Vesicles for Investigating Respiratory Impedance in Healthy Preschoolers.

Urine proteomic applications in children suggested their potential in discriminating between healthy subjects from those with respiratory diseases. The aim of the current study was to combine protein fractionation, by urinary extracellular vesicle isolation, and proteomics analysis in order to establish whether different patterns of respiratory impedance in healthy preschoolers can be characterized from a protein fingerprint. Twenty-one 3-5-yr-old healthy children, representative of 66 recruited subjects, were selected: 12 late preterm (LP) and 9 full-term (T) born. Children underwent measurement of respiratory impedance through Forced Oscillation Technique (FOT) and no significant differences between LP and T were found. Unbiased clustering, based on proteomic signatures, stratified three groups of children (A, B, C) with significantly different patterns of respiratory impedance, which was slightly worse in group A than in groups B and C. Six proteins (Tripeptidyl peptidase I (TPP1), Cubilin (CUBN), SerpinA4, SerpinF1, Thy-1 membrane glycoprotein (THY1) and Angiopoietin-related protein 2 (ANGPTL2)) were identified in order to type the membership of subjects to the three groups. The differential levels of the six proteins in groups A, B and C suggest that proteomic-based profiles of urinary fractionated exosomes could represent a link between respiratory impedance and underlying biological profiles in healthy preschool children.

Tumor cell-derived angiopoietin-like protein 2 establishes a preference for glycolytic metabolism in lung cancer cells.

We previously revealed that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) accelerates the metastatic capacity of tumors in an autocrine/paracrine manner by activating tumor cell motility and invasiveness and the epithelial-mesenchymal transition. However, the effects of ANGPTL2 on cancer cell glycolytic metabolism, which is a hallmark of tumor cells, are unknown. Here we report evidence supporting a role for tumor cell-derived ANGPTL2 in establishing a preference for glycolytic metabolism. We report that a highly metastatic lung cancer cell subline expressing abundant ANGPTL2 showed upregulated expression of the glucose transporter GLUT3 as well as enhanced glycolytic metabolism relative to a less metastatic parental line. Most notably, ANGPTL2 overexpression in the less metastatic line activated glycolytic metabolism by increasing GLUT3 expression. Moreover, ANGPTL2 signaling through integrin α5ß1 increased GLUT3 expression by increasing transforming growth factor-ß (TGF-ß) signaling and expression of the downstream transcription factor zinc finger E-box binding homeobox 1 (ZEB1). Conversely, ANGPTL2 knockdown in the highly metastatic subline decreased TGF-ß1, ZEB1, and GLUT3 expression and antagonized glycolytic metabolism. In primary tumor cells from patients with lung cancer, ANGPTL2 expression levels correlated with GLUT3 expression. Overall, this work suggests that tumor cell-derived ANGPTL2 accelerates activities associated with glycolytic metabolism in lung cancer cells by activating TGF-ß-ZEB1-GLUT3 signaling.

Anti-inflammatory activity of berberine in non-alcoholic fatty liver disease via the Angptl2 pathway.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease worldwide. Recent studies have shown that the Angptl2 pathway mediated hepatic inflammatory response plays an important role in the progression of nonalcoholic fatty liver disease. Our study investigated the possible molecular mechanisms of berberine (BBR) in the treatment of the liver inflammatory response in the livers of rats with high-fat diet-induced NAFLD via the Angptl2 pathway. RESULTS: At the end of 12 weeks, compared with the control group rats, the high-fat- diet group rats showed obvious pathological and biochemical changes. The levels of pro-infalmmatory cytokines (CCL2, TNF-α) were increased, the infiltration of inflammatory cells (CCR2) was elevated, and the hepatic mRNA and protein levels of Angptl2, NF-κB and Foxo1 were increased to different degrees. Nevertheless, following treatment with BBR, liver tissue pathology, biochemical data, and Angptl2 pathway-related genes expression were significantly ameliorated. CONCLUSIONS: Our findings demonstrate that BBR might attenuate the liver inflammatory response in the livers of rats with high-fat diet-induced NAFLD through the regulation of the Angptl2 pathway.