Endothelial cells that form the inner layers of both blood and lymphatic vessels are important components of the vascular system and are involved in the pathogenesis of vascular and lymphatic diseases. Angiopoietin (Ang)-Tie axis in endothelial cells is the second endothelium-specific ligand-receptor signaling system necessary for embryonic cardiovascular and lymphatic development in addition to the vascular endothelial growth factor receptor pathway. The Ang-Tie axis also maintains vascular homeostasis by regulating postnatal angiogenesis, vessel remodeling, vascular permeability, and inflammation. Therefore, the dysfunction of this system leads to many vascular and lymphatic diseases. In light of the recent advances on the role of the Ang-Tie axis in vascular and lymphatic system-related diseases, this review summarizes the functions of the Ang-Tie axis in inflammation-induced vascular permeability, vascular remodeling, ocular angiogenesis, shear stress response, atherosclerosis, tumor angiogenesis, and metastasis. Moreover, this review summarizes the relevant therapeutic antibodies, recombinant proteins, and small molecular drugs associated with the Ang-Tie axis.
Angiopoietins ; Endothelial Cells/metabolism* ; Humans ; Lymphatic Diseases ; Lymphatic System/metabolism* ; Receptor, TIE-2/metabolism* ; Signal Transduction ; Vascular Endothelial Growth Factor A

Vision loss in diabetic retinopathy (DR) is ascribed primarily to retinal vascular abnormalities—including hyperpermeability, hypoperfusion, and neoangiogenesis—that eventually lead to anatomical and functional alterations in retinal neurons and glial cells. Recent advances in retinal imaging systems using optical coherence tomography technologies and pharmacological treatments using anti-vascular endothelial growth factor drugs and corticosteroids have revolutionized the clinical management of DR. However, the cellular and molecular mechanisms underlying the pathophysiology of DR are not fully determined, largely because hyperglycemic animal models only reproduce limited aspects of subclinical and early DR. Conversely, non-diabetic mouse models that represent the hallmark vascular disorders in DR, such as pericyte deficiency and retinal ischemia, have provided clues toward an understanding of the sequential events that are responsible for vision-impairing conditions. In this review, we summarize the clinical manifestations and treatment modalities of DR, discuss current and emerging concepts with regard to the pathophysiology of DR, and introduce perspectives on the development of new drugs, emphasizing the breakdown of the blood-retina barrier and retinal neovascularization.
Adrenal Cortex Hormones ; Angiopoietins ; Animals ; Diabetic Retinopathy* ; Endothelial Cells ; Endothelial Growth Factors ; Ischemia ; Macular Edema ; Mice ; Models, Animal ; Neuroglia ; Pericytes ; Retinal Neovascularization ; Retinal Neurons ; Retinaldehyde ; Tomography, Optical Coherence ; Vascular Endothelial Growth Factors

PURPOSE: Angiopoietin-1 (Ang-1) plays a crucial role in vascular and hematopoietic development, mainly through its cognate receptor, Tie-2. Increased levels of Ang-2 have been shown to be correlated with abnormal tumor angiogenesis in several malignancies. Hence, we estimated the increased expression of Ang-2 relative to Ang-1 in patients with colorectal cancer and correlated our finding with prognosis in order to investigate the relationships between the expressions of Ang-1/Ang-2/Tie-2 receptor and the clinical parameters or overall survival of such patients. METHODS: We retrospectively analyzed 114 tissue samples from patients with colorectal cancer by using immunohistochemistry (IHC) to examine Ang-1, Ang-2, and Tie-2 expressions and to investigate the relationship between those expressions and clinical parameters or overall survival of such patients. A Western blot analysis was used for Ang-2 expression. RESULTS: IHC staining showed a link between Ang-1 and Tie-2 (P = 0.018), as well as meaningful correlations between Ang-2 and Tie-2 receptor (P = 0.022) and between lymph-node metastasis and Ang-2 (P = 0.025). The stronger the IHC staining for Ang-2 expression was, the shorter the cumulative survival was (P = 0.016). CONCLUSION: A relationship was found to exist between Ang-2 and Tie-2 expressions. The Ang-2 was correlated with lymph-node metastasis, and high expression of Ang-2 was indicative of poor overall survival. These findings suggest that Ang-2 is a useful prognostic marker in the management of patients with colorectal cancer. In addition, we suggest that Ang/Tie-2 signaling plays an important role in the progression of colorectal cancer.
Angiopoietin-1* ; Angiopoietin-2* ; Angiopoietins ; Blotting, Western ; Colorectal Neoplasms* ; Humans ; Immunohistochemistry ; Neoplasm Metastasis ; Prognosis ; Receptor, TIE-2* ; Retrospective Studies

BACKGROUNDA recent study reported a positive association between elevated serum levels of angiopoietin-like protein 2 (ANGPTL2) and the development of type 2 diabetes in a general population. However, the relationship of serum ANGPTL2 levels with the risk of developing gestational diabetes mellitus (GDM) has not been reported to date. The aim of this study was to investigate the change of maternal serum ANGPTL2 concentrations in the first trimester of pregnancy and to determine whether ANGPTL2 is a biomarker for subsequent GDM development.

METHODSWe conducted a prospective, nested case-control study in a pregnancy cohort. First-trimester ANGPTL2 levels were measured using a high-resolution assay in 89 women who subsequently developed GDM and in a random sample of 177 women who remained euglycemic throughout the pregnancy. Median ANGPTL2 levels were compared using Mann-Whitney U-test. Logistic regression was used to compute unadjusted and multivariable-adjusted odds ratios for developing GDM among ANGPTL2 quartiles.

RESULTSThe serum levels of ANGPTL2 was higher in women with GDM than that in women without GDM (3.06 [2.59, 3.65] ng/ml vs. 2.46 [2.05, 2.96] ng/ml, P = 0.003). Fasting blood glucose was higher in women with GDM than that in women without GDM (5.0 ± 0.9 mmol/L vs. 4.4 ± 0.6 mmol/L, P < 0.001). Glucose challenge test showed that the blood glucose was higher in women with GDM than that in women without GDM (9.1 ± 3.5 mmol/L vs. 6.2 ± 1.2 mmol/L, P < 0.001). A multivariate model adjusted for baseline characteristics, medical complications, and gestational characteristics revealed that the risk of developing GDM among women in Q4 compared with Q1 was 2.90-fold more likely to develop GDM later in pregnancy.

CONCLUSIONSAt 11-13 weeks in pregnancies that develop GDM, the serum concentration of ANGPTL2 is increased, and it can be combined with maternal factors to provide effective early screening for GDM.

Angiopoietin-like Proteins ; Angiopoietins ; blood ; Biomarkers ; blood ; Blood Glucose ; metabolism ; Case-Control Studies ; Diabetes, Gestational ; blood ; diagnosis ; Female ; Humans ; Odds Ratio ; Pregnancy ; Prospective Studies ; Risk Factors

OBJECTIVETo investigate the changes and value of plasma angiopoietin-related growth factor (AGF) in patients with abdominal aortic aneurysm (AAA).

METHODSSerum AGF level was analyzed in 50 AAA patients and in 56 healthy subjects. AGF and adiponectin were quantified by enzyme-linked immunosorbent assay. Routine testing of blood biochemistry and high-sensitivity C-reactive protein were performed.

RESULTSThe plasma AGF level was significantly higher in AAA patients than in the controls [(87.91±96.87) μg/L vs. (56.89±41.32) μg/L, P=0.040],while serum adiponectin level showed no significant difference between these two groups. The plasma AGF level in patients with an AAA>5 cm and those with AAA between 3 cm and 5 cm were (96.08±68.61) μg/L and (75.27±46.05) μg/L.

CONCLUSIONSPlasma AGF is highly expressed in AAA patients. Higher serum AGF level is associates with larger AAA. Thus, AGF may be a potential serum biomarker for AAA.

Adiponectin ; blood ; Angiopoietin-like Proteins ; Angiopoietins ; blood ; Aortic Aneurysm, Abdominal ; blood ; Biomarkers ; blood ; C-Reactive Protein ; analysis ; Case-Control Studies ; Enzyme-Linked Immunosorbent Assay ; Humans

Minimal change disease (MCD) is a common pathological type of nephrotic syndrome. Its main histology is the fusion of podocyte foot process. The pathogenesis of MCD is not clear, but previously it was thought to be related to immune mechanism. In recent years more studies show that podocyte injury is the key link in the pathogenesis of MCD. In MCD mouse model and human kidney tissues, the expressions of podocyte slit membrane protein-nephrin and podocin, skeleton protein-synaptopodin are decreased, and the expression of synaptopodin is correlated with the response to hormone therapy. In addition, newest studies focused on another two potocyte associated proteins, CD80 and Angiopoietin-like-4. CD80, a T cell stimulating molecule, is expressed in potocyte. Kappa B gene sequences can be activated by external microbes, antigens through acting potocytes, which can induce the upregulation of CD80 expression, cytoskeletal protein damage and the glomerular filtration rate changes, resulting in proteinuria. Angiopoietin-like-4 can be expressed in normal potocytes, but over-expression of angiopoietin-like-4 may injure the GBM charge barrier and induce the foot process fusion, leading to MCD. However, further studies on the factors inducing CD80 and Angiopoietin-like-4 expression, and the interaction between glomerular basement membrane and the two proteins are needed. Based on the mechanism of MCD, NF-kappa B inhibitors and sialylation therapy would be a novel non-immune therapy for MCD.
Angiopoietin-like 4 Protein ; Angiopoietins ; metabolism ; Animals ; B7-1 Antigen ; metabolism ; Disease Models, Animal ; Humans ; Intracellular Signaling Peptides and Proteins ; metabolism ; Kidney ; pathology ; Membrane Proteins ; metabolism ; Mice ; Microfilament Proteins ; metabolism ; NF-kappa B ; metabolism ; Nephrosis, Lipoid ; pathology ; Podocytes ; pathology

Angiopoietin-like proteins are a family of proteins that are closely related to lipid, glucose and energy metabolism, as well as angiogenesis. To date, eight Angptls have been discovered, namely Angptl1 to Angptl8 that play key roles in metabolic regulation and marker assisted selection. In this review, we summarized current progress on the structure, signaling pathways, upstream regulatory genes and metabolic network of Angptl1-8. Finally, in combination with our work, the status and problems of animal breeding as well as the future prospects for Angptls were discussed.
Angiopoietins ; genetics ; metabolism ; Animals ; Breeding ; Energy Metabolism ; Gene Regulatory Networks ; Glucose ; metabolism ; Lipid Metabolism ; Metabolic Networks and Pathways ; Signal Transduction

The tyrosine kinase system angiopoietin (Ang)/Tie interacts with vascular endothelial growth factor pathway and regulates vessel quiescence in adults as well as later steps of the angiogenic cascade related to vessel maturation. Since all Angs are able to bind to Tie-2 but none binds to Tie-1, the function of Tie-2 and its ligands have captured attention. However, emerging evidence indicates unique roles of the orphan receptor Tie-1 in angiogenesis under physiological and pathological conditions. It is required for maintaining vascular endothelial cell integrity and survival during murine embryo development and in adult and may be involved in modulating differentiation of hematopoietic cells in adult. Tie-1 exhibits poor tyrosine kinase activity and signals via forming heterodimers with Tie-2, inhibiting Tie-2 signaling mediated by Angs. This inhibition can be relieved by Tie-1 ectodomain cleavage mediated by tumor- and inflammatory-related factors, which causes destabilization of vessels and initiates vessel remodeling. Up-regulated Tie-1 expression has been found not only in some leukemia cells and tumor related endothelial cells but also in cytoplasm of carcinoma cells of a variety of human solid tumors, which is associated with tumor progression. In addition, it has pro-inflammatory functions in endothelial cells and is involved in some inflammatory diseases associated with angiogenesis. Recent research indicated that Tie-1 gene ablation exhibited significant effects on tumor blood- and lymph-angiogenesis and improved anti-Ang therapy, suggesting Tie-1 may be a potential target for tumor anti-angiogenesis treatment.
Angiogenesis Inhibitors ; therapeutic use ; Angiopoietins ; genetics ; metabolism ; Animals ; Embryo, Mammalian ; Embryonic Development ; genetics ; Endothelial Cells ; drug effects ; metabolism ; pathology ; Gene Expression Regulation, Developmental ; Gene Expression Regulation, Neoplastic ; Humans ; Mice ; Neoplasms ; drug therapy ; genetics ; metabolism ; pathology ; Neovascularization, Pathologic ; drug therapy ; genetics ; metabolism ; pathology ; Protein Binding ; Receptor, TIE-1 ; antagonists & inhibitors ; genetics ; metabolism ; Receptor, TIE-2 ; genetics ; metabolism ; Signal Transduction

OBJECTIVE: To investigate the association between angiopoietin-like 4 (ANGPTL4) and aldolase A (ALDOA) in human melanoma cell. 
 METHODS: Overexpression or knockdown of ANGPTL4 was performed in WM-115 or WM-266-4 cells, respectively. The expression of ANGPTL4 and ALDOA was measured by RT-PCR and Western blot, respectively. The promoter activity of ALDOA gene was determined by luciferase assay.
 RESULTS: The promoter activity of ALDOA gene and the expression of ALDOA (mRNA and protein) were increased or decreased in the melanoma cells with overexpression or knockdown of ANGPTL4, which was blocked by selective protein kinase C (PKC) inhibitor or restored by PKC agonist, respectively.
 CONCLUSION ANGPTL4 promotes ALDOA expression in human melanoma cell in a PKC dependent manner.
Angiopoietin-like 4 Protein ; Angiopoietins ; genetics ; metabolism ; Blotting, Western ; Cell Line, Tumor ; Fructose-Bisphosphate Aldolase ; metabolism ; Gene Knockdown Techniques ; Humans ; Melanoma ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism

OBJECTIVETo study the effect of Astragali Radix on the denervated tibial muscle atrophy in rats, and discuss its mechanism.

METHODTotally 60 SPF-grade Sprague-Dawley rats were selected in the common peroneal nerve crush model, and then randomly divided into 6 groups: Astragali Radix high-dose, medium-dose, low-dose groups, the Mecobalamin group, the model group, and the sham operation group. They were administered with drugs after the operation. At 18 d, the pathological section staining and morphological analysis were performed. The wet-weight ratio and section area of tibial muscles were also measured. The real-time fluorescence quantification was adopted to detect the differential expression between Angptl4 and PI3K genes.

RESULT(1) Wet-weight ratio: The wet-weight ratio in Astragali Radix high-dose, medium-dose groups was much higher than that in the model group (P < 0.05 or P < 0.01). (2) Section area: The sham operation group was higher, with regular morphology; Whereas the model group showed significant decrease, with chaotic structure and obvious connective tissue proliferation; Astragali Radix groups and the mecobalamin group showed relatively small section areas, with chaotic structure and unobvious connective tissue proliferation. Compared with the model group, Astragali Radix groups showed significant increase (P < 0.01). (3) Motor end plate: The sham operation group was in uniform brownish black color and oval or round shape; Astragali Radix medium-dose and high-dose group and the mecobalamin group showed rough line edges; Astragali Radix medium-dose and low-dose groups and the model group showed decline in the number, with irregular morphology, rough line edges and a light color. (4) Angptl4 and PI3K: Compared with the model group, the Astragali Radix high-dose group showed significant increase (P < 0.05).

CONCLUSIONAstragali Radix has a significant effect in preventing and treating denervated tibial muscle atrophy. It may delay the muscle atrophy by increasing Angptl4 and PI3K gene expressions.

Angiopoietin-like 4 Protein ; Angiopoietins ; genetics ; Animals ; Astragalus Plant ; Astragalus membranaceus ; chemistry ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Gene Expression Regulation ; drug effects ; Male ; Muscular Atrophy ; drug therapy ; genetics ; pathology ; prevention & control ; Phosphatidylinositol 3-Kinases ; genetics ; Rats ; Rats, Sprague-Dawley ; Tibia