Angiopoietin-related/angiopoietin-like proteins regulate angiogenesis

Cell and transcriptomic diversity of infrapatellar fat pad during knee osteoarthritis

OBJECTIVES

In this study, we employ a multiomic approach to identify major cell types and subsets, and their transcriptomic profiles within the infrapatellar fat pad (IFP), and to determine differences in the IFP based on knee osteoarthritis (KOA), sex and obesity status.

METHODS

Single-nucleus RNA sequencing of 82 924 nuclei from 21 IFPs (n=6 healthy control and n=15 KOA donors), spatial transcriptomics and bioinformatic analyses were used to identify contributions of the IFP to KOA. We mapped cell subclusters from other white adipose tissues using publicly available literature. The diversity of fibroblasts within the IFP was investigated by bioinformatic analyses, comparing by KOA, sex and obesity status. Metabolomics was used to further explore differences in fibroblasts by obesity status.

RESULTS

We identified multiple subclusters of fibroblasts, macrophages, adipocytes and endothelial cells with unique transcriptomic profiles. Using spatial transcriptomics, we resolved distributions of cell types and their transcriptomic profiles and computationally identified putative cell-cell communication networks. Furthermore, we identified transcriptomic differences in fibroblasts from KOA versus healthy control donor IFPs, female versus male KOA-IFPs and obese versus normal body mass index (BMI) KOA-IFPs. Finally, using metabolomics, we defined differences in metabolite levels in supernatants of naïve, profibrotic stimuli-treated and proinflammatory stimuli-treated fibroblasts from obese compared to normal BMI KOA-IFPs.

CONCLUSIONS

Overall, by employing a multiomic approach, this study provides the first comprehensive map of the cellular and transcriptomic diversity of human IFP and identifies IFP fibroblasts as key cells contributing to transcriptomic and metabolic differences related to KOA disease, sex or obesity.

Single-cell RNA sequencing of the holothurian regenerating intestine reveals the pluripotency of the coelomic epithelium

In holothurians, the regenerative process following evisceration involves the development of a "rudiment" or "anlage" at the injured end of the mesentery. This regenerating anlage plays a pivotal role in the formation of a new intestine. Despite its significance, our understanding of the molecular characteristics inherent to the constituent cells of this structure has remained limited. To address this gap, we employed state-of-the-art scRNA-seq and HCR-FISH analyses to discern the distinct cellular populations associated with the regeneration anlage. Through this approach, we successfully identified thirteen distinct cell clusters. Among these, two clusters exhibit characteristics consistent with putative mesenchymal cells, while another four show features akin to coelomocyte cell populations. The remaining seven cell clusters collectively form a large group encompassing the coelomic epithelium of the regenerating anlage and mesentery. Within this large group of clusters, we recognized previously documented cell populations such as muscle precursors, neuroepithelial cells and actively proliferating cells. Strikingly, our analysis provides data for identifying at least four other cellular populations that we define as the precursor cells of the growing anlage. Consequently, our findings strengthen the hypothesis that the coelomic epithelium of the anlage is a pluripotent tissue that gives rise to diverse cell types of the regenerating intestinal organ. Moreover, our results provide the initial view into the transcriptomic analysis of cell populations responsible for the amazing regenerative capabilities of echinoderms.

Prognostic value of serum angiopoietin-like protein 2 in patients with acute coronary syndrome

BACKGROUND

Angiopoietin-like protein 2 (Angptl2) is a cytokine that is released to stimulate inflammation and accelerate atherogenesis. Our study sought to assess the predictive significance of serum Angptl2 in individuals diagnosed with acute coronary syndrome (ACS) and determine whether it can enhance prognostic performance beyond the GRACE risk score.

METHODS

We recruited a total of 1060 patients with ACS in a consecutive manner. The levels of Angptl2 in serum were analyzed at baseline. The subjects were then followed up for 12 months to monitor the occurrence of major adverse cardiovascular events (MACE).

RESULTS

The level of serum Angptl2 showed a positive correlation with the GRACE score (r = 0.54, p < 0.001). Survival analysis revealed that increased levels of serum Angptl2 were associated with higher occurrence of the composite of MACE (log-rank p < 0.001) and its specific components (log-rank p = 0.011 for all-cause death, p = 0.007 for non-fatal myocardial infarction and p < 0.001 for revascularization respectively). Throughout the follow-up period, 163 instances (15.4%) of endpoint events were documented. In terms of MACE, both serum Angptl2 levels (HR: 1.178, 95% CI: 1.058-1.313, p = 0.003) and the GRACE risk score (HR: 1.181, 95% CI: 1.007-1.385, p = 0.041) emerged as significant predictors following Cox multivariate adjustment. Additionally, the addition of serum Angptl2 to the GRACE score improved the predictive capacity for prognosis [increase in area under the receiveroperating characteristic curve (AUC) from 0.740 to 0.794, p = 0.020; net reclassification improvement (NRI) = 0.401, p = 0.001; integrated discrimination improvement (IDI) = 0.022, p = 0.008].

CONCLUSION

Serum Angptl2 might be a useful prognostic biomarker and combining serum Angptl2 with the GRACE score increased the efficacy of prognosis prediction in ACS patients.

TRIAL REGISTRATION

Not applicable.

Critical signaling molecules in the temporomandibular joint osteoarthritis under different magnitudes of mechanical stimulation

The mechanical stress environment in the temporomandibular joint (TMJ) is constantly changing due to daily mandibular movements. Therefore, TMJ tissues, such as condylar cartilage, the synovial membrane and discs, are influenced by different magnitudes of mechanical stimulation. Moderate mechanical stimulation is beneficial for maintaining homeostasis, whereas abnormal mechanical stimulation leads to degeneration and ultimately contributes to the development of temporomandibular joint osteoarthritis (TMJOA), which involves changes in critical signaling molecules. Under abnormal mechanical stimulation, compensatory molecules may prevent degenerative changes while decompensatory molecules aggravate. In this review, we summarize the critical signaling molecules that are stimulated by moderate or abnormal mechanical loading in TMJ tissues, mainly in condylar cartilage. Furthermore, we classify abnormal mechanical stimulation-induced molecules into compensatory or decompensatory molecules. Our aim is to understand the pathophysiological mechanism of TMJ dysfunction more deeply in the ever-changing mechanical environment, and then provide new ideas for discovering effective diagnostic and therapeutic targets in TMJOA.

Role of the angiopoietin-like protein family in the progression of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most frequent cause of chronic liver disease, with a range of conditions including non-alcoholic fatty liver, non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Currently recognized as the liver component of the metabolic syndrome, NAFLD is intimately linked to metabolic diseases. Angiopoietin-like proteins (ANGPTLs) comprise a class of proteins that resemble angiopoietins structurally. It is closely related to obesity, insulin resistance and lipid metabolism, and may be the critical factor of metabolic syndrome. In recent years, many studies have found that there is a certain correlation between ANGPTLs and the occurrence and progression of NAFLD disease spectrum. This article reviews the possible mechanisms and roles of ANGPTL protein in the pathogenesis and progression of NAFLD.

Diverse contribution of amniogenic somatopleural cells to cardiovascular development: With special reference to thyroid vasculature

BACKGROUND

The somatopleure serves as the primordium of the amnion, an extraembryonic membrane surrounding the embryo. Recently, we have reported that amniogenic somatopleural cells (ASCs) not only form the amnion but also migrate into the embryo and differentiate into cardiomyocytes and vascular endothelial cells. However, detailed differentiation processes and final distributions of these intra-embryonic ASCs (hereafter referred to as iASCs) remain largely unknown.

RESULTS

By quail-chick chimera analysis, we here show that iASCs differentiate into various cell types including cardiomyocytes, smooth muscle cells, cardiac interstitial cells, and vascular endothelial cells. In the pharyngeal region, they distribute selectively into the thyroid gland and differentiate into vascular endothelial cells to form intra-thyroid vasculature. Explant culture experiments indicated sequential requirement of fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) signaling for endothelial differentiation of iASCs. Single-cell transcriptome analysis further revealed heterogeneity and the presence of hemangioblast-like cell population within ASCs, with a switch from FGF to VEGF receptor gene expression.

CONCLUSION

The present study demonstrates novel roles of ASCss especially in heart and thyroid development. It will provide a novel clue for understanding the cardiovascular development of amniotes from embryological and evolutionary perspectives.

CDK4/6 inhibitors induce breast cancer senescence with enhanced anti-tumor immunogenic properties compared with DNA-damaging agents

Since therapy-induced senescence (TIS) can either support or inhibit cancer progression, identifying which types of chemotherapeutic agents can produce the strongest anti-tumor TIS is an important issue. Here, cyclin-dependent kinase4/6 inhibitors (CDK4/6i)-induced senescence was compared to the TIS induced by conventional DNA-damaging agents. Despite both types of agents eliciting a similar degree of senescence, we observed increased expression of the senescence-associated secretory phenotype (SASP) and ligands related to pro-tumor immunity (IL6, CXCL8, TGFβ, CD274, and CEACAM1) and angiogenesis (VEGFA) mainly in TIS induced by DNA-damaging agents rather than by CDK4/6i. Additionally, although all agents increased the expression of anti-tumor immunomodulatory proteins related to antigen presentation (MHC-I, B2M) and T cell chemokines (CXCL9, 10, 11), CDK4/6i-induced senescent cells still maintained this expression at a similar or even higher intensity than cells treated with DNA-damaging agents, despite the absence of nuclear factor-kappa-B (NF-κB) and p53 activation. These data suggest that in contrast with DNA-damaging agents, which augment the pro-tumorigenic microenvironment via pro-inflammatory SASP, CDK4/6i can generate TIS only with antitumor immunomodulatory proteins.

Angiopoietin-Like Proteins: Cardiovascular Biology and Therapeutic Targeting for the Prevention of Cardiovascular Diseases

Despite the best pharmacologic tools available, cardiovascular diseases (CVDs) remain a major cause of morbidity and mortality in developed countries. After 2 decades of research, new therapeutic targets, such as angiopoietin-like proteins (ANGPTLs), are emerging. ANGPTLs belong to a family of 8 members, from ANGPTL1 to ANGPTL8; they have structural homology with angiopoietins and are secreted in the circulation. ANGPTLs display a multitude of physiological and pathologic functions; they contribute to inflammation, angiogenesis, cell death, senescence, hematopoiesis, and play a role in repair, maintenance, and tissue homeostasis. ANGPTLs-particularly the triad ANGPTL3, 4, and 8-have an established role in lipid metabolism through the regulation of triacylglycerol trafficking according to the nutritional status. Some ANGPTLs also contribute to glucose metabolism. Therefore, dysregulation in ANGPTL expression associated with abnormal circulating levels are linked to a plethora of CVD and metabolic disorders including atherosclerosis, heart diseases, diabetes, but also obesity and cancers. Because ANGPTLs bind to different receptors according to the cell type, antagonists are therapeutically inadequate. Recently, direct inhibitors of ANGPTLs, mainly ANGPTL3, have been developed, and specific monoclonal antibodies and antisense oligonucleotides are currently being tested in clinical trials. The aim of the current review is to provide an up-to-date preclinical and clinical overview on the function of the 8 members of the ANGPTL family in the cardiovascular system, their contribution to CVD, and the therapeutic potential of manipulating some of them.

Single-cell transcriptomics of human-skin-equivalent organoids

Several methods for generating human-skin-equivalent (HSE) organoid cultures are in use to study skin biology; however, few studies thoroughly characterize these systems. To fill this gap, we use single-cell transcriptomics to compare in vitro HSEs, xenograft HSEs, and in vivo epidermis. By combining differential gene expression, pseudotime analyses, and spatial localization, we reconstruct HSE keratinocyte differentiation trajectories that recapitulate known in vivo epidermal differentiation pathways and show that HSEs contain major in vivo cellular states. However, HSEs also develop unique keratinocyte states, an expanded basal stem cell program, and disrupted terminal differentiation. Cell-cell communication modeling shows aberrant epithelial-to-mesenchymal transition (EMT)-associated signaling pathways that alter upon epidermal growth factor (EGF) supplementation. Last, xenograft HSEs at early time points post transplantation significantly rescue many in vitro deficits while undergoing a hypoxic response that drives an alternative differentiation lineage. This study highlights the strengths and limitations of organoid cultures and identifies areas for potential innovation.

ANGPTL2 binds MAG to efficiently enhance oligodendrocyte differentiation

BACKGROUND

Oligodendrocytes have robust regenerative ability and are key players in remyelination during physiological and pathophysiological states. However, the mechanisms of brain microenvironmental cue in regulation of the differentiation of oligodendrocytes still needs to be further investigated.

RESULTS

We demonstrated that myelin-associated glycoprotein (MAG) was a novel receptor for angiopoietin-like protein 2 (ANGPTL2). The binding of ANGPTL2 to MAG efficiently promoted the differentiation of oligodendrocytes in vitro, as evaluated in an HCN cell line. Angptl2-null mice had a markedly impaired myelination capacity in the early stage of oligodendrocyte development. These mice had notably decreased remyelination capacities and enhanced motor disability in a cuprizone-induced demyelinating mouse model, which was similar to the Mag-null mice. The loss of remyelination ability in Angptl2-null/Mag-null mice was similar to the Angptl2-WT/Mag-null mice, which indicated that the ANGPTL2-mediated oligodendrocyte differentiation effect depended on the MAG receptor. ANGPTL2 bound MAG to enhance its phosphorylation level and recruit Fyn kinase, which increased Fyn phosphorylation levels, followed by the transactivation of myelin regulatory factor (MYRF).

CONCLUSION

Our study demonstrated an unexpected cross-talk between the environmental protein (ANGPTL2) and its surface receptor (MAG) in the regulation of oligodendrocyte differentiation, which may benefit the treatment of many demyelination disorders, including multiple sclerosis.

Maternal and cord blood betatrophin (angiopoietin-like protein 8) in pregnant women with gestational diabetes and normoglycemic controls: A systematic review, meta-analysis, and meta-regression

AIMS

This systematic review and meta-analysis examined maternal and cord blood betatrophin levels in pregnant women with gestational diabetes mellitus (GDM) and normoglycemic controls.

MATERIAL AND METHODS

PubMed, Cochrane Library, Embase, LILACS, WangFang, and China National Knowledge Infrastructure were searched for literature from inception until May 2022. The primary outcomes were maternal and cord blood betatrophin levels. A random-effect meta-analysis was used to estimate the pooled results. The mean differences (MDs) or standardised MDs (SMD) and their 95% confidence intervals (CIs) were calculated. I² tests were used to evaluate the heterogeneity. The quality of studies was evaluated using the Newcastle-Ottawa Scale.

RESULTS

Betatrophin levels were reported in 22 studies with a total of 3034 pregnant women, and in seven studies including cord blood from 456 infants. Women with GDM display higher betatrophin levels than the normoglycemic controls (SMD = 0.85, 95% CI: 0.38-1.31) during the second half of the pregnancy. The sensitivity analysis indicated that no single study had significantly influenced the betatrophin overall outcomes. There was heterogeneity between the studies as evidenced by high I² values. Meta-regression analysis indicated a significant regression coefficient for maternal betatrophin and glycosilated haemoglobin. There was no significant difference in cord blood betatrophin in infants from women with and without GDM (SMD = 0.34, 95% CI: -0.15-0.83). Women with GDM also had significantly higher insulin, glucose, glycosylated haemoglobin, HOMA-IR, LDL-cholesterol, HDL-cholesterol, triglycerides, and body mass index compared with the normoglycemic controls.

CONCLUSIONS

Maternal betatrophin levels were higher in women with GDM than in the normoglycemic controls. There was no difference in cord blood betatrophin.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022311372.

Comprehensive Analysis of Potential Prognostic Values of ANGPTLs in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignant tumors in the world. CRC recurrence and metastasis cause poor prognosis. ANGPTLs (angiopoietin-like proteins) are a family of proteins that are widely involved in metabolic disease and tumorigenesis. The roles of ANGPTLs in CRC are still controversial and deserve further research. In this study, several databases were employed to explore the expression profiles, prognostic values, genetic alterations, potential biological function, and immune infiltration correlation of ANGPTLs in CRC. The expression of ANGPTL4 was significantly positively correlated with the stage of CRC. Therefore, cell and molecular experiments were further performed to explore the roles of ANGPTL4. Our results showed that the transcriptions of ANGPTLs in colon cancer and rectal cancer tissues were lower than those in normal tissues, but the protein expression varied among different ANGPTLs. In addition, the high expression of ANGPTLs led to a relatively poor oncological outcome. Specifically, the expression of ANGPTL4 is significantly positively correlated with the stage of CRC. Further investigation revealed that ANGPTLs are mainly involved in signal transduction and the regulation of transcription, while KEGG pathway analyses demonstrated pathways in cancer. Additionally, we also observed that ANGPTL4 could promote the proliferation and migration of CRC cells, and four specific small molecule compounds had potential ANGPTL4-binding capabilities, suggesting the clinical application of these small molecule compounds on CRC treatment. Our findings imply the prognostic values and potential therapeutic targets of ANGPTLs in CRC.

Identification of Oxidative Stress-Associated Molecular Subtypes and Signature for Predicting Survival Outcome of Cervical Squamous Cell Carcinoma

Background

Cervical squamous cell carcinoma (CESC) is the gynecologic malignancy with high incidence rate and high mortality rate. Oxidative stress participates in gene regulation and malignant tumor progression, including CESC.

Methods

RNA-seq, clinical information, and genomic mutation were from The Cancer Genome Atlas- (TCGA-) CESC and GSE44001 datasets. Oxidative stress-related genes were obtained from the gene set enrichment analysis (GSEA) website. ConsensusClusterPlus was used for clustering, which was assessed by the Kaplan-Meier (KM) survival curve analysis, mutation analysis, immunocharacteristic analysis, and therapy. Prognostic signatures were built by combining weighted correlation network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO) algorithm, and stepAIC. The prognostic power of this model was evaluated using the KM survival curve analysis, receiver operating characteristic (ROC) curve analysis, nomogram, and decision curve analysis (DCA).

Results

218 of the 291 CESC cases (74.91%) presented oxidative stress-related gene mutation, especially FBXW7. Three clusters were determined based on oxidative stress-related genes, among which cluster 3 (C3) presented low-frequency mutation and hyperimmune state and was sensitive to immunotherapy. This research developed a 5-gene oxidative stress-related prognostic signature and a RiskScore model. As shown by ROC analysis, in the TCGA and GSE44001 datasets, the RiskScore model showed a high prediction accuracy for 1-, 3-, and 5-year CESC overall survival. High RiskScore was associated with enhanced immune status. The nomogram model was greatly predictive of the overall survival of CESC patients.

Conclusion

Our prognostic model was based on oxidative stress-related genes in CESC, potentially aids in CESC prognosis, and provides potential targets against CESC.

TGF-β2 enhances expression of equine bone marrow-derived mesenchymal stem cell paracrine factors with known associations to tendon healing

Background

Mesenchymal stem cells (MSCs) secrete paracrine factors and extracellular matrix proteins that contribute to their ability to support tissue healing and regeneration. Both the transcriptome and the secretome of MSCs can be altered by treating the cells with cytokines, but neither have been thoroughly investigated following treatment with the specific cytokine transforming growth factor (TGF)-β2.

Methods

RNA-sequencing and western blotting were used to compare gene and protein expression between untreated and TGF-β2-treated equine bone marrow-derived MSCs (BM-MSCs). A co-culture system was utilized to compare equine tenocyte migration during co-culture with untreated and TGF-β2-treated BM-MSCs.

Results

TGF-β2 treatment significantly upregulated gene expression of collagens, extracellular matrix molecules, and growth factors. Protein expression of collagen type I and tenascin-C was also confirmed to be upregulated in TGF-β2-treated BM-MSCs compared to untreated BM-MSCs. Both untreated and TGF-β2-treated BM-MSCs increased tenocyte migration in vitro.

Conclusions

Treating equine BM-MSCs with TGF-β2 significantly increases production of paracrine factors and extracellular matrix molecules important for tendon healing and promotes the migration of tenocytes in vitro.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03172-9.

Contribution of organokines in the development of NAFLD/NASH associated hepatocellular carcinoma

Globally the incidence of hepatocellular carcinoma (HCC) is on an upsurge. Evidence is accumulating that liver disorders like nonalcoholic fatty liver disease (NAFLD) and its more progressive form nonalcoholic steatohepatitis (NASH) are associated with increased risk of developing HCC. NAFLD has a prevalence of about 25% and 50%-90% in obese population. With the growing burden of obesity epidemic worldwide, HCC presents a major healthcare burden. While cirrhosis is one of the major risk factors of HCC, available literature suggests that NAFLD/NASH associated HCC also develops in minimum or noncirrhotic livers. Therefore, there is an urgent need to understand the pathogenesis and risk factors associated with NAFLD and NASH related HCC that would help in early diagnosis and favorable prognosis of HCC secondary to NAFLD. Adipokines, hepatokines and myokines are factors secreted by adipocytes, hepatocytes and myocytes, respectively, playing essential roles in cellular homeostasis, energy balance and metabolism with autocrine, paracrine and endocrine effects. In this review, we endeavor to focus on the role of these organokines in the pathogenesis of NAFLD/NASH and its progression to HCC to augment the understanding of the factors stimulating hepatocytes to acquire a malignant phenotype. This shall aid in the development of novel therapeutic strategies and tools for early diagnosis of NAFLD/NASH and HCC.

Aqueous angiopoietin-like levels correlate with optical coherence tomography angiography metrics in diabetic macular edema

AIM

To quantitatively detect aqueous levels of angiopoietin-like (ANGPTL)3, ANGPTL4, and ANGPTL6 and investigate their correlation with optical coherence tomography angiography (OCTA) findings in patients with diabetic macular edema (DME).

METHODS

This cross-sectional study included 23 patients (27 eyes) with type 2 diabetes and 16 control subjects (20 eyes). All patients underwent OCTA imaging and ultra-wide field fundus photography. Diabetic patients were categorized into two groups according to the presence or absence of diabetic retinopathy (DME group, 14 patients, 16 eyes); and non-diabetic retinopathy (NDR) group, 9 patients, 11 eyes, respectively. Aqueous levels of ANGPTL3, ANGPTL4, and ANGPTL6 were assessed using suspension array technology, and foveal-centered 3×3 mm² OCTA scans were automatically graded to determine the central, inner, and full vessel density (CVD, IVD, FVD); central, inner, and full perfusion density (CPD, IPD, FPD), foveal avascular zone (FAZ) area, FAZ perimeter, and FAZ circularity index (FAZ-CI) on superficial capillary plexuses. Additionally, central subfield thickness (CST), cube volume (CV), and cube average thickness (CAT) were measured in a model of macular cube 512×128.

RESULTS

Aqueous ANGPTL3 levels were not significantly different among the three groups (P>0.05). ANGPTL4 levels were significantly higher in the DME group than the control and NDR groups (P<0.0001 and P<0.001), while ANGPTL6 levels were significantly higher in the DME group than the control group (P<0.05). In the whole cohort, the aqueous ANGPTL3 levels correlated negatively with the IVD, FVD, IPD, and FPD, and positively with the CV and CAT. The aqueous ANGPTL4 levels correlated negatively with the CVD, IVD, FVD, CPD, IPD, and FPD, and positively with the FAZ perimeter, CST, CV, and CAT. The aqueous ANGPTL6 levels correlated negatively with the IVD, FVD, IPD, FPD, FAZ-CI and positively with CST, CV, CAT.

CONCLUSION

ANGPTL4 and ANGPTL6 may be associated with vascular leakage in DME and may represent good targets for DME therapy. In addition, OCTA metrics may be useful for evaluating macular ischemia in DME.

Hepatokines and Non-Alcoholic Fatty Liver Disease: Linking Liver Pathophysiology to Metabolism

The liver plays a key role in maintaining energy homeostasis by sensing and responding to changes in nutrient status under various metabolic conditions. Recently highlighted as a major endocrine organ, the contribution of the liver to systemic glucose and lipid metabolism is primarily attributed to signaling crosstalk between multiple organs via hepatic hormones, cytokines, and hepatokines. Hepatokines are hormone-like proteins secreted by hepatocytes, and a number of these have been associated with extra-hepatic metabolic regulation. Mounting evidence has revealed that the secretory profiles of hepatokines are significantly altered in non-alcoholic fatty liver disease (NAFLD), the most common hepatic manifestation, which frequently precedes other metabolic disorders, including insulin resistance and type 2 diabetes. Therefore, deciphering the mechanism of hepatokine-mediated inter-organ communication is essential for understanding the complex metabolic network between tissues, as well as for the identification of novel diagnostic and/or therapeutic targets in metabolic disease. In this review, we describe the hepatokine-driven inter-organ crosstalk in the context of liver pathophysiology, with a particular focus on NAFLD progression. Moreover, we summarize key hepatokines and their molecular mechanisms of metabolic control in non-hepatic tissues, discussing their potential as novel biomarkers and therapeutic targets in the treatment of metabolic diseases.

ANGPTL2 Promotes Inflammation via Integrin α5β1 in Chondrocytes

BACKGROUND

Angiopoietin-like protein 2 (ANGPTL2) is a secreted molecule with numerous physiologic and pathologic functions, for example, in angiogenesis, hematopoiesis, and tumorigenesis. Although recent studies implicated ANGPTL2 in chronic inflammation in mouse peritoneal macrophages, human ligamentum flavum fibroblasts, and human retinal microvascular endothelial cells, the mechanism underlying ANGPTL2-associated inflammation in chondrocytes remains unclear. Therefore, it was investigated whether ANGPTL2 is expressed in or functions in chondrocytes.

METHODS

Expression of ANGPTL2 and its receptor, integrin α5β1 were examined over time in ATDC5 cells using real-time RT-PCR (reverse transcription-polymerase chain reaction) analysis. ATDC5 cells were then incubated with or without ANGPTL2 for 3 hours, and expression of the IL-1β, TNF-α, COX-2, aggrecanase (ADAMTS)-5, matrix metalloproteinase (MMP)-3, and MMP-13 genes were examined using real-time RT-PCR. Additionally, phosphorylation of ERK, JNK, p38, Akt, and NF-κB was examined by western blotting. Furthermore, it was also investigated for the effect of anti-integrin α₅β₁ antibody on the expression of inflammatory markers and intracellular signaling pathways.

RESULTS

ANGPTL2 induced the phosphorylation of all 3 MAPKs, Akt, and NF-κB and dramatically upregulated the expression of inflammation-related factor genes. Inhibiting the activation of integrin α5β1 suppressed these reactions.

CONCLUSION

ANGPTL2 may induce inflammatory factors by stimulating the integrin α5β1/MAPKs, Akt, and NF-κB signaling pathway.

DL-3-n-butylphthalide suppressed autophagy and promoted angiogenesis in rats with vascular dementia by activating the Shh/Ptch1 signaling pathway

DL-3-n-butylphthalide (NBP) has neuroprotective effect on chronic cerebral hypoperfusion animals. Here, we explored the role and underlying mechanism of NBP on autophagy and angiogenesis in rats with vascular dementia (VD). Adult male Sprague-Dawley (SD) rats were subjected to permanent bilateral occlusion of the common carotid arteries (2VO) to establish VD model. These rats were randomly divided into five groups: sham, model, NBP₁₂₀ (120 mg/kg), Shh siRNA (50 nM), and NBP₁₂₀ + Shh siRNA groups. Our results showed that NBP treatment attenuated memory damage in rats with VD, as demonstrated by Morris water maze tests. Immunofluorescence (IF) assay revealed that NBP induced neuronal process length and neuronal activity in hippocampus, which were reversed by Shh silencing. Furthermore, NBP treatment also reduced the expression of autophagy marker proteins B-cell lymphoma-2 interacting protein 1 (Beclin 1) and microtubule-associated protein 1 light chain 3 (LC3), which were further enhanced by Shh silencing. Meanwhile, NBP promoted the angiogenesis, which was accompanied by upregulated vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF)-1, and Angiopoietin (Ang) expression in the hippocampus. And Shh siRNA co-treatment blocked the angiogenesis induced by NBP. Altogether, our results established that NBP treatment suppressed autophagy and improved angiogenesis and neurobehavioral recovery in VD rats partly by activating the Shh/Ptch1 signaling pathway.

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.

Regulation of lipoprotein metabolism by ANGPTL3, ANGPTL4, and ANGPTL8

Triglyceride-rich lipoproteins deliver fatty acids to tissues for oxidation and for storage. Release of fatty acids from circulating lipoprotein triglycerides is carried out by lipoprotein lipase (LPL), thus LPL serves as a critical gatekeeper of fatty acid uptake into tissues. LPL activity is regulated by a number of extracellular proteins including three members of the angiopoietin-like family of proteins. In this review, we discuss our current understanding of how, where, and when ANGPTL3, ANGPTL4, and ANGPTL8 regulate lipoprotein lipase activity, with a particular emphasis on how these proteins interact with each other to coordinate triglyceride metabolism and fat partitioning.

Identification of Estrogen Signaling in a Prioritization Study of Intraocular Pressure-Associated Genes

Elevated intraocular pressure (IOP) is the only modifiable risk factor for primary open-angle glaucoma (POAG). Herein we sought to prioritize a set of previously identified IOP-associated genes using novel and previously published datasets. We identified several genes for future study, including several involved in cytoskeletal/extracellular matrix reorganization, cell adhesion, angiogenesis, and TGF-β signaling. Our differential correlation analysis of IOP-associated genes identified 295 pairs of 201 genes with differential correlation. Pathway analysis identified β-estradiol as the top upstream regulator of these genes with ESR1 mediating 25 interactions. Several genes (i.e., EFEMP1, FOXC1, and SPTBN1) regulated by β-estradiol/ESR1 were highly expressed in non-glaucomatous human trabecular meshwork (TM) or Schlemm’s canal (SC) cells and specifically expressed in TM/SC cell clusters defined by single-cell RNA-sequencing. We confirmed ESR1 gene and protein expression in human TM cells and TM/SC tissue with quantitative real-time PCR and immunofluorescence, respectively. 17β-estradiol was identified in bovine, porcine, and human aqueous humor (AH) using ELISA. In conclusion, we have identified estrogen receptor signaling as a key modulator of several IOP-associated genes. The expression of ESR1 and these IOP-associated genes in TM/SC tissue and the presence of 17β-estradiol in AH supports a role for estrogen signaling in IOP regulation.

Angiopoietin-Like Proteins 2 and 3 in Children and Adolescents with Obesity and Their Relationship with Hypertension and Metabolic Syndrome

Background

Angiopoietin-like protein 2 (ANGPTL2) is one of the adipocyte-derived inflammatory factors which connects obesity to insulin resistance. ANGPTL3 has a direct role in regulation of lipid metabolism. The objective of this study was to evaluate ANGPTL2 and ANGPTL3 in childhood obesity and their relationship with metabolic syndrome.

Methods

70 children and adolescents, 35 obese and 35 normal-weight subjects, were enrolled in this research after complete clinical examination and anthropometric evaluations. Serum ANGPTL2 and ANGPTL3 and insulin were measured by enzyme-linked immunosorbent assay (ELISA). Homeostatic model assessment of insulin resistance (HOMA-IR) was calculated and used to estimate insulin resistance (IR). Colorimetric methods were used for the assessment of fasting plasma glucose (FPG), LDL-C, HDL-C, total cholesterol (TC), and triglyceride (TG).

Results

The levels of ANGPTL2 and ANGPTL3 were significantly higher in obese subjects than those in controls, but they did not differ significantly in subjects with or without IR. ANGPTL3 was found to be significantly elevated in obese children with metabolic syndrome (MetS) in comparison with those without MetS. Both of the studied ANGPTLs were positively correlated with BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), TC, and LDL-C. The correlation between ANGPTL3 and either TC or LDL-C remained significant after adjusting for BMI.

Conclusion

Serum ANGPTL2 and ANGPTL3 were elevated in obesity and associated with blood pressure and indices of metabolic syndrome, suggesting that they might be involved in the advancement of obesity-related hypertension and metabolic syndrome.

Lipoprotein profile and lipid metabolism of PXB-cells®, human primary hepatocytes from liver-humanized mice: proposal of novel in vitro system for screening anti-lipidemic drugs

We investigated lipid metabolism in PXB-cells, which are human primary hepatocytes isolated from liver-humanized mice, and HepG2 and HuH-7 human hepatoma cell lines. Lipoprotein levels were higher in PXB-cells than in the 2 other cell lines, and PXB-cells mainly released triglycerides and cholesterol as very low density lipoprotein (VLDL), similar to actual liver tissue, whereas the major lipoprotein released from the 2 hepatoma cell lines was LDL. RT-PCR analysis demonstrated that the gene expression levels of apolipoprotein B100 (ApoB100), the apolipoprotein of VLDL/LDL, were similar in PXB-cells and HepG2 cells, while the overexpression of ApoC2, ApoC3, and ApoE, which are components of VLDL, but not LDL, was observed in PXBcells. A protein immunoassay revealed that ApoB100 levels secreted from PXB-cells and HuH-7 cells were similar; however, ApoC3 levels were higher in PXB-cells than in the two other cell lines. We also examined the anti-lipidemic activities of fenofibrate using this assay system. Fenofibrate suppressed lipoprotein production from PXB-cells in a dose-dependent manner mainly by activating the β-oxidation pathway. These results suggest that PXB-cells produce high levels of lipoproteins and are suitable for screening anti-lipidemic agents.

Angiopoietin-like Proteins in Colorectal Cancer-A Literature Review

Colorectal cancer (CRC) is one of the most common types of malignancy, with an annual incidence of about 10% of the total number of new cases. Despite well-developed screening tests, mortality from this type of cancer remains unchanged. Therefore, it is important to search for more accurate markers that are useful in the detection of colorectal cancer (especially in its early stages), and treatment. Angiopoietin-like proteins (ANGPTLs) are a family of eight proteins with a diversity of applications, including pro- and anti-angiogenic properties. Consequently, we performed an extensive search of the literature, pertaining to our investigation, via the MEDLINE/PubMed database. Based on the available literature, we summarize that some of those proteins are characterized by increased or decreased concentrations during the course of CRC. We can also assume that some ANGPTLs can inhibit the development of CRC, while others induce its progress. Moreover, some factors are dependent on the stage or histological type of the tumor, the presence of hypoxia, or metastases. Most importantly, some ANGPTLs can be useful in anti-cancer therapy. Therefore, further studies on ANGPTLs as potential markers of CRC should be continued.

Altered Expression of Secreted Mediator Genes That Mediate Aggressive Breast Cancer Metastasis to Distant Organs

Simple Summary

Heterogeneity is the characteristic of breast tumors, making it difficult to understand the molecular mechanism. Alteration of gene expression in the primary tumor versus the metastatic lesion remains challenging for getting any specific targeted therapy. To better understand how gene expression profile changes during metastasis, we compare the primary tumor and distant metastatic tumor gene expression using primary breast tumors compared with its metastatic variant in animal models. Our RNA sequencing data from cells revealed that parental cell and the metastatic variant cell are different in gene expression while gene signature significantly altered during metastasis to distant organs than primary breast tumors. We found that secreted mediators encoding genes (ANGPTL7, MMP3, LCN2, S100A8, and ESM1) are correlated with poor prognosis in the clinical setting as divulged from METABRIC and TCGA-BRCA cohort data analysis.

Abstract

Due to the heterogeneous nature of breast cancer, metastasis organotropism has been poorly understood. This study assessed the specific cancer-related gene expression changes occurring with metastatic breast cancer recurrence to distant organs compared with non-metastatic breast cancer. We found that several secreted mediators encoding genes notably, LCN2 and S100A8 overexpressed at the distant metastatic site spine (LCN2, 5-fold; S100A8, 6-fold) and bone (LCN2, 5-fold; S100A8, 3-fold) vs. primary tumors in the syngeneic implantation/tumor-resection metastasis mouse model. In contrast, the ESM-1 encoding gene is overexpressed in the primary tumors and markedly downregulated at distant metastatic sites. Further digging into TCAGA-BRCA, SCAN-B, and METABRIC cohorts data analysis revealed that LCN2, S100A8, and ESM-1 mediators encoding individual gene expression scores were strongly associated with disease-specific survival (DSS) in the METABRIC cohort (hazard ratio (HR) > 1, p < 0.0004). The gene expression scores predicted worse clinically aggressive tumors, such as high Nottingham histological grade and advanced cancer staging. Higher gene expression score of ESM-1 gene was strongly associated with worse overall survival (OS) in the triple-negative breast cancer (TNBC) and hormonal receptor (HR)-positive/HER2-negative subtype in METABRIC cohort, HER2+ subtype in TCGA-BRCA and SCAN-B breast cancer cohorts. Our data suggested that mediators encoding genes with prognostic and predictive values may be clinically useful for breast cancer spine, bone, and lung metastasis, particularly in more aggressive subtypes such as TNBC and HER2+ breast cancer.

Influence of Angptl1 on osteoclast formation and osteoblastic phenotype in mouse cells

Background

Osteoblasts and osteoclasts play important roles during the bone remodeling in the physiological and pathophysiological states. Although angiopoietin family Angiopoietin like proteins (Angptls), including Angptl1, have been reported to be involved in inflammation, lipid metabolism and angiogenesis, the roles of Angptl1 in bone have not been reported so far.

Methods

We examined the effects of Angptl1 on the osteoblast and osteoclast phenotypes using mouse cells.

Results

Angptl1 significantly inhibited the osteoclast formation and mRNA levels of tartrate-resistant acid phosphatase and cathepsin K enhanced by receptor activator of nuclear factor κB ligand in RAW 264.7 and mouse bone marrow cells. Moreover, Angptl1 overexpression significantly enhanced Osterix mRNA levels, alkaline phosphatase activity and mineralization induced by bone morphogenetic protein-2 in ST2 cells, although it did not affect the expression of osteogenic genes in MC3T3-E1 and mouse osteoblasts. On the other hand, Angptl1 overexpression significantly reduced the mRNA levels of peroxisome proliferator-activated receptor γ and adipocyte protein-2 as well as the lipid droplet formation induced by adipogenic medium in 3T3-L1 cells.

Conclusions

The present study first indicated that Angptl1 suppresses and enhances osteoclast formation and osteoblastic differentiation in mouse cells, respectively, although it inhibits adipogenic differentiation of 3T3-L1 cells. These data suggest the possibility that Angptl1 might be physiologically related to bone remodeling.

ANGPTL8 roles in proliferation, metabolic diseases, hypothyroidism, polycystic ovary syndrome, and signaling pathways

A new and atypical member of the ANGPTL family is angiopoietin-like protein 8 (ANGPTL8). This newly discovered hormone is a drug target that can be used to treat diabetes and dyslipidemia. The protein, as a hepatocyte-derived circulating factor, can control the triglyceride level of plasma. ANGPTL8 is significantly associated with inflammation and metabolic syndrome consequences such as obesity, diabetes, hypothyroidism, and PCOS. ANGPTL8 gene has four exons encoding a 22/5 kDa weight of 198 amino acid polypeptides. A highly preserved ANGPTL8 gene among mammals exhibits the essential hormone functions of ANGPTL8. Nevertheless, the physiological function of this hormone in the body is poorly understood. Studies published in PubMed (2008-2020), Google Scholar (2004-2020), and Scopus (2004-2020) databases of clinical trials were reviewed. This analysis is aimed at collecting information on ANGPTL8. The emphasis of this review was on gathering information about the role of ANGPTL8 in the metabolism of glucose and lipids and cell proliferation. It addition to the different roles of ANGPTL8 in diabetes and lipid metabolism, this review emphasized on the protein role in signaling pathways. The study also proposes the signaling pathways that may be considered as a new target for treatment.

CSN5 Promotes Carcinogenesis of Thyroid Carcinoma Cells Through ANGPTL2

COP9 signalosome subunit 5 (CSN5) plays a key role in carcinogenesis of multiple cancers and contributes to the stabilization of target proteins through deubiquitylation. However, the underlying role of CSN5 in thyroid carcinoma has not been reported. In this research, our data showed that CSN5 was overexpressed in thyroid carcinoma tissues compared with paracancerous tissues. Furthermore, a series of gain/loss functional assays were performed to demonstrate the role of CSN5 in facilitating thyroid carcinoma cell proliferation and metastasis. Additionally, we found there was a positive correlation between CSN5 and angiopoietin-like protein 2 (ANGPTL2) protein levels in thyroid carcinoma tissues and that CSN5 promoted thyroid carcinoma cell proliferation and metastasis through ANGPTL2. We also identified the underlying mechanism that CSN5 elevated ANGPTL2 protein level by directly binding it, decreasing its ubiquitination and degradation. Overall, our results highlight the significance of CSN5 in promoting thyroid carcinoma carcinogenesis and implicate CSN5 as a promising candidate for thyroid carcinoma treatment.

Evaluation of serum Angiopoietin-like protein 2 (ANGPTL-2), Angiopoietin-like protein 8 (ANGPTL-8), and high-sensitivity C-reactive protein (hs-CRP) levels in patients with gestational diabetes mellitus and normoglycemic pregnant women

OBJECTIVE

In the present study, we aimed to investigate the role of the fasting serum levels of Anjiopoetın 2 - like protein (ANGPTL2), Anjiopoetın 8-like protein (ANGPTL8), and high-sensitivity C-reactive protein (hs-CRP) in the etiopathogenesis of gestational diabetes mellitus (GDM), and analyze the relationships between insulin resistance parameters.

MATERIAL AND METHOD

The 90 individuals admitted to İzmir Katip Celebi University Hospital Internal Medicine, Endocrinology and Obstetrics, and gynecology outpatient clinic were included in the study of similar ages and similar demographic characteristics. Forty-five women with diet-controlled GDM and 45 women with normoglycemic pregnancy were enrolled. ANGPTL-2, ANGPTL-8, hs-CRP, creatinine, ALT, GGT, lipid profile, HBA1c(%), and serum insülin, c-peptide levels were studied in the fasting serum samples of research groups. All individuals had 75-g OGTT testing. GDM screening was performed at 24-28 weeks' gestation. Exclusion criteria were as follows: Age <18 years or >40 years, pregestational diabetes (type 1 or 2), drug or alcohol abuse, thyroid dysfunction, Hepatitis B, and other infectious diseases (Herpes virus, Streptococcus B carriers, Chlamydia and Candida), Thalassemia carriers or other significant medical conditions, the use of any medication that interferes with lipid or glucose metabolism that would affect glucose regulation.

RESULT

Forty-five women with GDM and for the control group, 45 women with normoglycemic pregnant women were identified. The mean gestational age was 30.7 (18-38) for GDM and 29.6 (24-39) for the control group. Serum ANGPTL-8 (GDM =19.5 ± 93 Control = 0.73 ± 3.78 p = <.001). There was a statistically significant difference between the case and control groups for serum ANGPTL-8 levels. Serum ANGPTL-2 (GDM =19.9 ± 23.1 Control = 26.0 ± 23.4 p = .105) and serum hs-CRP(GDM =106 ± 65.1 Control =98.2 ± 87.3 p = .768). There was no statistically significant difference between the case and control groups for serum ANGPTL-2 and hsCRP levels. Serum ANGPTL8 levels were positively correlated with FPG (r = 0.391, p = <.001), FPI (r = 0.212, p = .045), 1-h PPG (r = 0.514, p = <.001), 2-h PPG (r = 0.502, p = <.001), HOMA-IR) score (r = 0.310, p = .003), TG (r = 0.245, p = .020); they were not except for BMI, hs-CRP levels and ANGPTL2 levels.

CONCLUSIONS

ANGPTL8 levels were significantly higher in GDM than in healthy control group. ANGPTL2 levels and hs-CRP levels were similar to the healthy control group. Elevated serum ANGPTL8 levels were correlated significantly with insulin resistance parameters, the main component of GDM pathophysiology. Our data showed that ANGPTL8 could be a new biomarker for diagnosing GDM.

Higher levels of circulating ANGPTL2 are associated with macular edema in patients with type 2 diabetes

Macular edema (ME) is an inflammatory disease characterized by increased microvascular permeability. Here, we proposed that plasma angiopoietin-like protein 2 (ANGPTL2) level may be related to the severity of ME patients with type 2 diabetes mellitus (T2DM). In this cross-sectional study, 172 T2DM patients were recruited and divided into clinically significant macular edema (CSME), non-CSME (nCSME), and control groups. Serum ANGPTL2 level was quantified by ELISA and best corrected vision acuity (BCVA) was detected. After adjust age, sex, body mass index (BMI), and duration of diabetes variables, ANGPTL2 performed statistics difference among CSME-, nCSME-groups, and control group (4.46 [3.97, 4.96, 95%CI] ng/mL in CSME group, 3.80 [3.42, 4.18, 95%CI] ng/mL in nCSME-group, 3.33 [3.03, 3.63, 95%CI] ng/mL in control, P < .01). After adjustment of confounding factors, high levels of circulating ANGPTL2 were related with the diagnosis of ME, BCVA, and C reactive protein (CRP) through univariate regression analysis (P < .05). Meanwhile, in the multiple regression model, ANGPTL2 took the mainly effect proportion for the diagnosis of diabetic macular edema (DME), with a LogWorth value 3.559 (P < .001). Our study suggested that elevated circulating ANGPTL2 may be associated with the development of DME and the severity of visual impairment in patients with type 2 diabetes.

Hepatokines and metabolism: Deciphering communication from the liver

Background

The liver is a key regulator of systemic energy homeostasis and can sense and respond to nutrient excess and deficiency through crosstalk with multiple tissues. Regulation of systemic energy homeostasis by the liver is mediated in part through regulation of glucose and lipid metabolism. Dysregulation of either process may result in metabolic dysfunction and contribute to the development of insulin resistance or fatty liver disease.

Scope of review

The liver has recently been recognized as an endocrine organ that secretes hepatokines, which are liver-derived factors that can signal to and communicate with distant tissues. Dysregulation of liver-centered inter-organ pathways may contribute to improper regulation of energy homeostasis and ultimately metabolic dysfunction. Deciphering the mechanisms that regulate hepatokine expression and communication with distant tissues is essential for understanding inter-organ communication and for the development of therapeutic strategies to treat metabolic dysfunction.

Major conclusions

In this review, we discuss liver-centric regulation of energy homeostasis through hepatokine secretion. We highlight key hepatokines and their roles in metabolic control, examine the molecular mechanisms of each hepatokine, and discuss their potential as therapeutic targets for metabolic disease. We also discuss important areas of future studies that may contribute to understanding hepatokine signaling under healthy and pathophysiological conditions.

Structure and Function of Angiopoietin-like Protein 3 (ANGPTL3) in Atherosclerosis

BACKGROUND

Angiopoietin-Like Proteins (ANGPTLs) are structurally related to the angiopoietins. A total of eight ANGPTLs (from ANGPTL1 to ANGPTL8) have been identified so far. Most ANGPTLs possess multibiological functions on lipid metabolism, atherosclerosis, and cancer. Among them, ANGPTL3 has been shown to regulate the levels of Very Low-Density Lipoprotein (VLDL) made by the liver and play a crucial role in human lipoprotein metabolism.

METHOD

A systematic appraisal of ANGPTLs was conducted, focusing on the main features of ANGPTL3 that has a significant role in atherosclerosis.

RESULTS

Angiopoietins including ANGPTL3 are vascular growth factors that are highly specific for endothelial cells, perform a variety of other regulatory activities to influence inflammation, and have been shown to possess both pro-atherosclerotic and atheroprotective effects.

CONCLUSION

ANGPTL3 has been demonstrated as a promising target in the pharmacological management of atherosclerosis. However, many questions remain about its biological functions.

High-Serum Angiopoietin-Like Protein 3 Levels Associated with Cardiovascular Outcome in Patients with Coronary Artery Disease

Background

Angiopoietin-like protein 3 (ANGPTL3) plays a pivotal role in lipid metabolism and angiogenesis, and there is growing interest regarding the association between ANGPTL3 and coronary artery disease (CAD). This study aims to investigate whether ANGPTL3 levels can be used to predict the future occurrence of major adverse cardiovascular events (MACEs) in patients with CAD.

Methods

Overall, 90 patients with CAD were enrolled between January and December 2012. The study's primary endpoint was incidence of MACEs. Patient follow-up was completed on June 30, 2017.

Results

Following a median follow-up period of 54 months, 33 MACEs had occurred. Patients reporting MACEs had lower statin use (P=0.022) and higher serum C-reactive protein (P < 0.001) and serum ANGPTL3 (P < 0.001) levels than those without MACEs. Kaplan–Meier analysis revealed higher cumulative incidence of CV events in the high ANGPTL3 group (median ANGPTL3 level ≥ 222.37 ng/mL) than in the low ANGPTL3 group (log-rank P=0.046). Multivariable Cox regression analysis demonstrated that ANGPTL3 levels were independently associated with MACEs in patients with CAD (hazard ratio: 1.003; 95% confidence interval: 1.000–1.005; P=0.026) after adjusted for age, gender, and body mass index, classical risk factors, and potential confounders.

Conclusions

Serum ANGPTL3 levels could serve as a biomarker for future occurrence of MACEs in patients with CAD.

Changes in gene expression in human skeletal stem cells transduced with constitutively active Gsα correlates with hallmark histopathological changes seen in fibrous dysplastic bone

Fibrous dysplasia (FD) of bone is a complex disease of the skeleton caused by dominant activating mutations of the GNAS locus encoding for the α subunit of the G protein-coupled receptor complex (Gsα). The mutation involves a substitution of arginine at position 201 by histidine or cysteine (Gsα^{R201H or R201C}), which leads to overproduction of cAMP. Several signaling pathways are implicated downstream of excess cAMP in the manifestation of disease. However, the pathogenesis of FD remains largely unknown. The overall FD phenotype can be attributed to alterations of skeletal stem/progenitor cells which normally develop into osteogenic or adipogenic cells (in cis), and are also known to provide support to angiogenesis, hematopoiesis, and osteoclastogenesis (in trans). In order to dissect the molecular pathways rooted in skeletal stem/progenitor cells by FD mutations, we engineered human skeletal stem/progenitor cells with the Gsα^R201C mutation and performed transcriptomic analysis. Our data suggest that this FD mutation profoundly alters the properties of skeletal stem/progenitor cells by pushing them towards formation of disorganized bone with a concomitant alteration of adipogenic differentiation. In addition, the mutation creates an altered in trans environment that induces neovascularization, cytokine/chemokine changes and osteoclastogenesis. In silico comparison of our data with the signature of FD craniofacial samples highlighted common traits, such as the upregulation of ADAM (A Disintegrin and Metalloprotease) proteins and other matrix-related factors, and of PDE7B (Phosphodiesterase 7B), which can be considered as a buffering process, activated to compensate for excess cAMP. We also observed high levels of CEBPs (CCAAT-Enhancer Binding Proteins) in both data sets, factors related to browning of white fat. This is the first analysis of the reaction of human skeletal stem/progenitor cells to the introduction of the FD mutation and we believe it provides a useful background for further studies on the molecular basis of the disease and for the identification of novel potential therapeutic targets.

ANGPTL6-mediated angiogenesis promotes alpha fetoprotein-producing gastric cancer progression

Alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC) is regarded as a rare but highly malignant gastric adenocarcinoma subtype and its clinic pathological presentation mimics hepatocellular carcinoma. However, the underlying mechanism of this disease remains elusive. The level of ANGPTL6 in AFPGC cell lines is much higher than that of common types of gastric cancer cells. A high level of ANGPTL6 confers a poor prognosis and is correlated with the expression of CD34 (an endothelial cell marker). ANGPTL6 promotes endothelial cell migration and tube formation, Moreover, ANGPTL6 knockdown inhibits cancer cell apoptosis and invasiveness. Mechanistically, ANGPTL6 activates the ERK1/2 and AKT pathways. Treatment of ERK1/2 or AKT inhibitor can attenuated cell migration and tube formation. ANGPTL6 loss results in tumor growth in vivo. Our study revealed that ANGPTL6 is an important driver gene of angiogenesis in AFPGC development. These findings provide not only an effective biomarker for diagnosis but also an attractive therapeutic target for use in AFPGC patients.

Intron retention as an alternative splice variant of the cattle ANGPTL6 gene

Angiopoietin-like protein 6, which is encoded by ANGPTL6 gene (also known as angiopoietin growth factor, AGF), has been extensively characterized with regard to its proposed functions as angiogenesis and energy metabolism. The present results showed the occurrence of alternative splicing by intron retention (IR) event in the bovine ANGPTL6 gene (bANGPTL6). By means of RT-PCR, TA clone and sequencing, we have shown that the bANGPTL6 gene has a splice variant generated by the retention of its partial intron 3. The computational analysis of the bANGPTL6 genomic sequence showed that its intron 3 has a high percentage of GC (62.31%) and a length of 199 nt, characteristics that have been associated with an IR event. The IR event does not interfere with the coding region as the bANGPTL6 prepropeptide is entirely coded in the third exon. Additionally, both the intronless (namely, bANGPTL6α) and intron-retaining (namely, bANGPTL6β) ANGPTL6 transcripts are constitutively co-expressed in the bovine liver. Further, the relative expression level of different variants in liver was tested by both semi-RT-PCR and RT-qPCR methods. The results suggested bANGPTL6β are significantly higher than bANGPTL6α. Overall, our findings will be helpful for studies on the molecular mechanism of IR events and the functions of ANGPTL6 gene. Specially, bANGPTL6β gene probably contributes to a new target for treatment of obesity and obesity-related diseases.

The Roles of ANGPTL Families in Cancer Progression

Angiopoietins play important roles in angiogenesis and the maintenance of hematopoietic stem cells. Angiopoietin-like proteins (ANGPTLs) are identified as proteins structurally similar to angiopoietins, and the ANGPTL family now consists of eight members. ANGPTLs are secretary proteins, and some ANGPTLs are not only angiogenic factors but also proteins with multiple functions such as glucose metabolism, lipid metabolism, redox regulation and chronic inflammation. Chronic inflammation is one of the key factors in carcinogenesis and cancer growth, proliferation, invasion and metastasis. ANGPTL 2, 3, 4, 6 and 7 are pro-inflammatory factors and regulate cancer progression, while ANGPTL1 inhibits tumor angiogenesis and metastasis. In this review, we describe the roles of ANGPTLs in cancer progression and discuss the possibility of disturbing the progression of cancer by regulating ANGPTLs expression.

Enhanced ANGPTL2 expression in adipose tissues and its association with insulin resistance in obese women

Angiopoietin-like protein 2 has been proposed to be a key mediator linking obesity and insulin resistance. However, no detailed study of ANGPTL2 expression in human adipose tissues has yet been reported. To investigate the pattern and regulation of ANGPTL2 expression in human adipose tissues in obesity and its related diseases, we recruited 32 non-diabetic and 13 type 2 diabetic obese women and 32 normal-weight women. ANGPTL2 mRNA was expressed at a similar level in visceral and subcutaneous adipose tissues. Adipose tissue ANGPTL2 mRNA was much higher in obese patients. Adipose tissue ANGPTL2 mRNA and serum ANGPTL2 levels showed strong associations with metabolic parameters associated with insulin resistance. In adipose tissue, ANGPTL2 mRNA was closely correlated with the expression of genes involved in inflammation and ER stress. ANGPTL2 mRNA was principally expressed in adipocytes, and its expression was markedly higher in the adipocyte but non-adipocyte fraction of obese adipose tissues. Culture of human adipocytes under conditions mimicking the microenvironment of obese adipose tissue (especially, increased ER stress) stimulated ANGPTL2 gene expression and secretion. In addition, co-culture of adipocytes and macrophages suggested that ANGPTL2 excessively produced by adipocytes, may contribute inflammation and remodeling in obese adipose tissues, thereby promoting insulin resistance.

Simplified Preparation of αvβ3 Integrin-Targeted Microbubbles Based on a Clinically Available Ultrasound Contrast Agent: Validation in a Tumor-Bearing Mouse Model

The usefulness of ultrasound molecular imaging with α_vβ₃ integrin-targeted microbubbles for detecting tumor angiogenesis has been demonstrated. Recently, we developed α_vβ₃ integrin-targeted microbubbles by modifying clinically available microbubbles (Sonazoid, Daiichi-Sankyo Pharmaceuticals, Tokyo, Japan) with a secreted glycoprotein (lactadherin). The aims of our present study were to simplify the preparation of lactadherin-bearing Sonazoid and to examine the diagnostic utility of lactadherin-bearing Sonazoid for α_vβ₃ integrin-expressing tumor vessels by using SK-OV-3-tumor-bearing mice. By incubating 1.2 × 10⁷ Sonazoid microbubbles with 1.0 µg lactadherin, the complicated washing and centrifugation steps during the microbubble preparation could be omitted with no significant reduction in labeling ratio of lactadherin-bearing Sonazoid. In addition, the number of Sonazoid microbubbles accumulated in the SK-OV-3 tumor was significantly increased by modifying Sonazoid with lactadherin. Our data suggest that the lactadherin-bearing Sonazoid is an easily prepared and potentially clinically translatable targeted microbubble for α_vβ₃ integrin-expressing vessels.

Angiopoietin-like protein 3 and 4 in obesity, type 2 diabetes mellitus, and malnutrition: the effect of weight reduction and realimentation

Background

Angiopoietin-like proteins (ANGPTLs) 3 and 4 are circulating factors that participate in the regulation of lipid and glucose metabolism.

Subjects and methods

We measured serum ANGPTL3 and 4 levels in 23 patients with obesity, 40 patients with obesity and type 2 diabetes mellitus (T2DM), 22 patients with anorexia nervosa (AN), 15 subjects undergoing 72-h fasting, and 12 patients with short bowel syndrome (SBS), and their changes after very-low-calorie diet (VLCD), bariatric surgery, partial realimentation, acute fasting, and parenteral nutrition in order to assess their possible role in metabolic regulations.

Results

Serum ANGPTL4 levels were higher in obese subjects without/with T2DM (94.50 ± 9.51 and 134.19 ± 7.69 vs. 50.34 ± 4.22 ng/ml, p < 0.001) and lower in subjects with AN relative to healthy control subjects (38.22 ± 4.48 vs. 65.80 ± 7.98 ng/ml, p = 0.002), while serum ANGPTL3 levels demonstrated inverse tendency. Nutritional status had no effect on ANGPTL3 and 4 mRNA expression in adipose tissue. Fasting decreased ANGPTL3 and increased ANGPTL4 levels, while VLCD reduced only ANGPTL3. Bariatric surgery and realimentation of AN or SBS patients had no effect on either ANGPTL. Multiple regression analysis identified BMI as an independent predictor of ANGPTL3; and BMI and HbA_1c as independent predictors of ANGPTL4, respectively.

Conclusions

Taken together, our data suggest that serum ANGPTL3 and 4 levels are influenced by nutritional status and fasting and could be involved in the metabolic disturbances present in obesity and AN.

Angiopoietin-Like Proteins in Angiogenesis, Inflammation and Cancer

Altered expression of secreted factors by tumor cells or cells of the tumor microenvironment is a key event in cancer development and progression. In the last decade, emerging evidences supported the autocrine and paracrine activity of the members of the Angiopoietin-like (ANGPTL) protein family in angiogenesis, inflammation and in the regulation of different steps of carcinogenesis and metastasis development. Thus, ANGPTL proteins become attractive either as prognostic or predictive biomarkers, or as novel target for cancer treatment. Here, we outline the current knowledge about the functions of the ANGPTL proteins in angiogenesis, cancer progression and metastasis. Moreover, we discuss the most recent evidences sustaining their role as prognostic or predictive biomarkers for cancer therapy. Although the role of ANGPTL proteins in cancer has not been fully elucidated, increasing evidence suggest their key effects in the proliferative and invasive properties of cancer cells. Moreover, given the common overexpression of ANGPTL proteins in several aggressive solid tumors, and their role in tumor cells and cells of the tumor microenvironment, the field of research about ANGPTL proteins network may highlight new potential targets for the development of future therapeutic strategies.

ANGPTL2 - A New Causal Player in Accelerating Heart Disease Development in the Aging

In parallel with the increase in the number of elderly people worldwide, the number of patients with heart disease is also rapidly increasing. Of the heart diseases, cardiovascular disease (CVD) and heart failure (HF) are strongly associated with adverse health outcomes that decrease productivity in later years. Recently, ANGPTL2, a secreted glycoprotein and member of the angiopoietin-like protein family, has received attention as a causal player in the development of CVD and HF. Prolonged ANGPTL2 autocrine/paracrine signaling in vascular tissue leads to chronic inflammation and pathologic tissue remodeling, accelerating CVD development. Excess ANGPTL2 autocrine/paracrine signaling induced in the pathologically stressed heart accelerates cardiac dysfunction by decreasing myocardial energy metabolism. Conversely, ANGPTL2 inactivation in vascular tissue and the heart delays development or progression of CVD and HF, respectively. Moreover, there is increased evidence for an association between elevated circulating ANGPTL2 levels and CVD and HF. Interestingly, ANGPTL2 expression is also associated with cellular senescence, which may promote premature aging and development of aging-associated diseases, including CVD and HF. Overall, ANGPTL2 autocrine/paracrine signaling is a new factor in accelerating heart disease development in the aging. Here, we focus on current topics relevant to ANGPTL2 function in heart disease.

High Circulating Levels of ANGPTL2: Beyond a Clinical Marker of Systemic Inflammation

Angiopoietin-like 2 (ANGPTL2) is a proinflammatory protein belonging to the angiopoietin-like family. ANGPTL2 is secreted and detected in the systemic circulation. Different observational clinical studies reported that circulating levels of ANGPTL2 increase significantly in various chronic inflammatory diseases and showed associations between ANGPTL2 levels and diagnosis and/or prognosis of cardiovascular diseases, diabetes, chronic kidney disease, and various types of cancers. However, these studies did not address the following questions: (a) what are the sources of circulating ANGPTL2? (b) How and by which mechanisms an increase in circulating ANGPTL2 contributes to the pathogenesis of chronic inflammatory diseases? (c) Does an increase in circulating levels of ANGPTL2 measured in a well-defined chronic medical condition originate from a specific cell type? Mechanistic hypotheses have been proposed based on studies performed in mice and cultured cells, and proinflammatory, prooxidative, proangiogenic, proliferative, and antiapoptotic properties of ANGPTL2 have been reported. The aim of this review is to propose answers concerning the potential sources of circulating ANGPTL2 and its common pathological properties associated with various chronic inflammatory diseases and death in humans. We believe that high circulating ANGPTL2 levels are more than an inflammatory marker and may reflect the senescent cellular load of an individual.

ANGPTL1 attenuates colorectal cancer metastasis by up-regulating microRNA-138

Background

Angiopoietin-like protein 1 (ANGPTL1) has been reported to suppress migration and invasion in lung and breast cancer, acting as a novel tumor suppressor candidate. Nevertheless, its effects on colorectal cancer (CRC) remain poorly defined. In this study, we aim to demonstrate the biological function of ANGPTL1 in CRC cells.

Methods

We explored ANGPTL1 mRNA expression in human CRC tissues and its association with prognosis. CRC cell lines overexpressing ANGPTL1 or with ANGPTL1 knocked down were constructed and analyzed for changes in proliferation, colony formation, migration and invasion. ANGPTL1-regulated microRNAs were analyzed, and microRNA inhibitor and mimics were used to explore the role of microRNA in ANGPTL1-associated biological function.

Results

ANGPTL1 mRNA expression was down-regulated in CRC tissues, and high ANGPTL1 expression predicted better survival in CRC patients. ANGPTL1 overexpression resulted in suppressed migration and invasion in vitro, and it prolonged overall survival in mouse models. By contrast, its down-regulation enhanced migration and invasion of CRC cells. MicroRNA-138 expression was positively correlated with ANGPTL1 mRNA level in CRC tissues and up-regulated by ANGPTL1 in CRC cells. In addition, the microRNA-138 inhibitor or mimics could reverse or promote the ANGPTL1-mediated inhibition of the migratory capacity of CRC cells, respectively.

Conclusions

This study is the first to demonstrate the biological function of ANGPTL1 in CRC cells. ANGPTL1 expression was down-regulated in CRC tissues and inversely correlated with poor survival. ANGPTL1 repressed migration and invasion of CRC cells, and microRNA-138 was involved in this process.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0548-7) contains supplementary material, which is available to authorized users.

Plasma and adipose tissue level of angiopoietin-like 7 (ANGPTL7) are increased in obesity and reduced after physical exercise

Objective

ANGPTL7 is a member of the Angiopoietin-like (ANGPTL) protein family that is composed of eight proteins (1–8). Increasing evidence is associating ANGPTL proteins to obesity and insulin resistance. The biological role of ANGPTL7 is yet to be understood except for a recently proposed role in the pathophysiology of glaucoma. This study was designed to shed light on the function of ANGPTL7 in obesity and its modulation by physical exercise as well as its potential association with lipid profile.

Methods

A total of 144 subjects were enrolled in this study and finished three months of physical exercise. The participants were classified based on their BMI, 82 subjects were non-obese and 62 obese. ANGPTL7 levels in plasma and adipose tissue were measured by ELISA, RT-PCR and immunohistochemistry.

Results

In this study, we showed that ANGPTL7 level was increased in the plasma of obese subjects (1249.05± 130.39 pg/mL) as compared to non-obese (930.34 ± 87.27 pg/mL) (p-Value = 0.032). ANGPTL7 Gene and protein expression levels in adipose tissue also showed over two fold increase. Physical exercise reduced circulating level of ANGPTL7 in the obese subjects to 740.98± 127.18 pg/mL, (p-Value = 0.007). ANGPTL7 expression in adipose tissue was also reduced after exercise. Finally, ANGPTL7 circulating level showed significant association with TG level in the obese subjects (R² = 0.183, p-Value = 0.03).

Conclusion

In conclusion, our data shows for the first time that obesity increases the level of ANGPTL7 in both plasma and adipose tissue. Increased expression of ANGPTL7 might play a minor role in the regulation of TG level in obese subjects either directly or through interaction with other ANGPTL protein members. Physical exercise reduced the level of ANGPTL7 highlighting the potential for targeting this protein as a therapeutic target for regulating dyslipidemia.

Angiopoietin-like protein 6 in patients with obesity, type 2 diabetes mellitus, and anorexia nervosa: The influence of very low-calorie diet, bariatric surgery, and partial realimentation

AIM OF THE STUDY

Angiopoietin-like protein 6 (ANGPTL6) is a circulating protein with a potential role in energy homeostasis. The aim of the study was to explore the changes in ANGPTL6 levels in patients with obesity (Body mass index, BMI > 40 kg/m²) with and without type 2 diabetes mellitus (T2DM) undergoing dietary intervention (very low calorie diet - VLCD) and in a subgroup of T2DM patients after bariatric surgery. Additionally, we examined changes in ANGPTL6 in anorexia nervosa (AN) patients at baseline and after partial realimentation. We also explored the changes in ANGPTL6 mRNA expression in subcutaneous adipose tissue (SAT) of obese subjects.

MATERIALS AND METHODS

The study included 23 non-diabetic obese patients, 40 obese patients with T2DM (27 underwent VLCD and 13 underwent bariatric surgery), 22 patients with AN, and 37 healthy control subjects.

RESULTS

ANGPTL6 levels of AN patients were increased relative to the control group (68.6 ± 9.9 ng/ml) and decreased from 110.2 ± 13.3 to 73.6 ± 7.1 ng/ml (p = 0.004) after partial realimentation. Baseline ANGPTL6 levels in patients with obesity and T2DM did not differ from the control group. VLCD decreased ANGPTL6 levels only in obese patients with T2DM. Bariatric surgery induced a transient elevation of ANGPTL6 levels with a subsequent decrease to baseline levels. ANGPTL6 mRNA expression transiently increased after bariatric surgery and returned to baseline levels after 12 months.

CONCLUSIONS

Collectively, our data suggest that serum ANGPTL6 levels and ANGPTL6 mRNA expression in SAT are affected by metabolic disorders and their treatment but do not appear to directly reflect nutritional status.