Investigation of the Mitigation of DMSO-Induced Cytotoxicity by Hyaluronic Acid following Cryopreservation of Human Nucleus Pulposus Cells.

To develop an off-the-shelf therapeutic product for intervertebral disc (IVD) repair using nucleus pulposus cells (NPCs), it is beneficial to mitigate dimethyl sulfoxide (DMSO)-induced cytotoxicity caused by intracellular reactive oxygen species (ROS). Hyaluronic acid (HA) has been shown to protect chondrocytes against ROS. Therefore, we examined the potential of HA on mitigating DMSO-induced cytotoxicity for the enhancement of NPC therapy. Human NPC cryopreserved in DMSO solutions were thawed, mixed with equal amounts of EDTA-PBS (Group E) or HA (Group H), and incubated for 3-5 h. After incubation, DMSO was removed, and the cells were cultured for 5 days. Thereafter, we examined cell viability, cell proliferation rates, Tie2 positivity (a marker of NP progenitor cells), and the estimated numbers of Tie2 positive cells. Fluorescence intensity of DHE and MitoSOX staining, as indicators for oxidative stress, were evaluated by flow cytometry. Group H showed higher rates of cell proliferation and Tie2 expressing cells with a trend toward suppression of oxidative stress compared to Group E. Thus, HA treatment appears to suppress ROS induced by DMSO. These results highlight the ability of HA to maintain NPC functionalities, suggesting that mixing HA at the time of transplantation may be useful in the development of off-the-shelf NPC products.

Repurposing alpelisib, an anti-cancer drug, for the treatment of severe TIE2-mutated venous malformations: Preliminary pharmacokinetics and pharmacodynamic data.

Extensive venous malformations involving limbs severely impact quality of life, mostly due to chronic pain and functional limitations. But patients can also display coagulopathy with associated risks of life-threatening thromboembolism and bleeding. Available pharmacological treatments (e.g., sirolimus) are not universally effective. Novel therapies are urgently needed for patients with treatment-resistant venous malformations. We report three patients with TIE-2 receptor mutations treated with alpelisib for 6 months (daily dosing: 50 mg for children weighing <50 kg and 100 mg for those >50 kg). Pain was controlled, gait improved, size of the abnormal venous network decreased, and coagulopathy dramatically improved. Drug exposure was highly variable, suggesting that alpelisib dosing should be individualized to patient's characteristics and guided by therapeutic drug monitoring.

Quantile-specific heritability of serum growth factor concentrations.

BACKGROUND: "Quantile-dependent expressivity" occurs when the effect size of a genetic variant depends upon whether the phenotype (e.g. growth factor concentration) is high or low relative to its distribution. METHODS: Quantile-regression analysis was applied to family sets from the Framingham Heart Study to determine whether the heritability (h2) of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), angiopoietin-2, and angiopoietin-2 (sTie-2) and VEGFR1 (sFlt-1) receptor concentrations were quantile-specific. RESULTS: Quantile-specific h2 (±SE) increased with increasing percentiles of the age- and sex-adjusted VEGF (Ptrend<10-16), HGF (Ptrend=0.0004), angiopoietin-2 (Ptrend=0.0002), sTie-2 (Ptrend=1.2 × 10-5), and sFlt-1 distributions (Ptrend=0.04). CONCLUSION: Heritabilities of VEGF, HGF, angiopoitein-2, sTie-2 and sFlt-1 concentrations are quantile dependent. This may explain reported interactions of genetic loci (rs10738760, rs9472159, rs833061, rs3025039, rs2280789, rs1570360, rs2010963) with metabolic syndrome, diet, recurrent miscarriage, hepatocellular carcinoma, erysipelas, diabetic retinopathy, and bevacizumab treatment in their effect on VEGF concentrations.

Effect of Whole Tissue Culture and Basic Fibroblast Growth Factor on Maintenance of Tie2 Molecule Expression in Human Nucleus Pulposus Cells.

Previous work showed a link between Tie2+ nucleus pulposus progenitor cells (NPPC) and disc degeneration. However, NPPC remain difficult to maintain in culture. Here, we report whole tissue culture (WTC) combined with fibroblast growth factor 2 (FGF2) and chimeric FGF (cFGF) supplementation to support and enhance NPPC and Tie2 expression. We also examined the role of PI3K/Akt and MEK/ERK pathways in FGF2 and cFGF-induced Tie2 expression. Young herniating nucleus pulposus tissue was used. We compared WTC and standard primary cell culture, with or without 10 ng/mL FGF2. PI3K/Akt and MEK/ERK signaling pathways were examined through western blotting. Using WTC and primary cell culture, Tie2 positivity rates were 7.0 ± 2.6% and 1.9 ± 0.3% (p = 0.004), respectively. Addition of FGF2 in WTC increased Tie2 positivity rates to 14.2 ± 5.4% (p = 0.01). FGF2-stimulated expression of Tie2 was reduced 3-fold with the addition of the MEK inhibitor PD98059 (p = 0.01). However, the addition of 1 µM Akt inhibitor, 124015-1MGCN, only reduced small Tie2 expression (p = 0.42). cFGF similarly increased the Tie2 expression, but did not result in significant phosphorylation in both the MEK/ERK and PI3K/Akt pathways. WTC with FGF2 addition significantly increased Tie2 maintenance of human NPPC. Moreover, FGF2 supports Tie2 expression via MEK/ERK and PI3K/Akt signals. These findings offer promising tools and insights for the development of NPPC-based therapeutics.

Angiopoietin/Tie2 Axis Regulates the Age-at-Injury Cerebrovascular Response to Traumatic Brain Injury.

Although age-at-injury influences chronic recovery from traumatic brain injury (TBI), the differential effects of age on early outcome remain understudied. Using a male murine model of moderate contusion injury, we investigated the underlying mechanism(s) regulating the distinct response between juvenile and adult TBI. We demonstrate similar biomechanical and physical properties of naive juvenile and adult brains. However, following controlled cortical impact (CCI), juvenile mice displayed reduced cortical lesion formation, cell death, and behavioral deficits at 4 and 14 d. Analysis of high-resolution laser Doppler imaging showed a similar loss of cerebral blood flow (CBF) in the ipsilateral cortex at 3 and 24 h post-CCI, whereas juvenile mice showed enhanced subsequent restoration at 2-4 d compared with adults. These findings correlated with reduced blood-brain barrier (BBB) disruption and increased perilesional vessel density. To address whether an age-dependent endothelial cell (EC) response affects vessel stability and tissue outcome, we magnetically isolated CD31+ ECs from sham and injured cortices and evaluated mRNA expression. Interestingly, we found increased transcripts for BBB stability-related genes and reduced expression of BBB-disrupting genes in juveniles compared with adults. These differences were concomitant with significant changes in miRNA-21-5p and miR-148a levels. Accompanying these findings was robust GFAP immunoreactivity, which was not resolved by day 35. Importantly, pharmacological inhibition of EC-specific Tie2 signaling abolished the juvenile protective effects. These findings shed new mechanistic light on the divergent effects that age plays on acute TBI outcome that are both spatial and temporal dependent.SIGNIFICANCE STATEMENT Although a clear "window of susceptibility" exists in the developing brain that could deter typical developmental trajectories if exposed to trauma, a number of preclinical models have demonstrated evidence of early recovery in younger patients. Our findings further demonstrate acute neuroprotection and improved restoration of cerebral blood flow in juvenile mice subjected to cortical contusion injury compared with adults. We also demonstrate a novel role for endothelial cell-specific Tie2 signaling in this age-related response, which is known to promote barrier stability, is heightened in the injured juvenile vasculature, and may be exploited for therapeutic interventions across the age spectrum following traumatic brain injury.

Emerging vascular endothelial growth factor antagonists to treat neovascular age-related macular degeneration.

INTRODUCTION: Evolving anti-vascular endothelial growth factor (VEGF) treatments for neovascular age-related macular degeneration (nAMD) include long acting agents, combination strategies involving new pathways, topical agents, sustained-release, and genetic therapy strategies. Areas covered: Brolucizumab and abicipar pegol have smaller molecular size, facilitating higher concentrations and potentially longer duration than current anti-VEGF agents. Agents being combined with anti-VEGFs include OPT-302 (to inhibit VEGF-C and VEGF-D); pegpleranib and rinucumab (to inhibit platelet derived growth factor, PDGF - but both failed to show consistently improved visual outcomes compared to anti-VEGF monotherapy); and RG7716, ARP-1536 and nesvacumab (to activate the Tie-2 tyrosine kinase receptor, which reduces permeability). X-82 is an oral anti-VEGF and anti-PDGF being tested in phase 2 studies. Topical anti-VEGF ± anti-PDGF drugs under study include pazopanib, PAN-90806, squalamine lactate, regorafinib, and LHA510. Sustained-release anti-VEGF delivery treatments, such as the ranibizumab Port Delivery System, GB-102, NT-503, hydrogel depot, Durasert, and ENV1305 aim to reduce the burden of frequent injections. Gene therapies with new viral vectors hold the potential to induce sustained expression of anti-angiogenic proteins via the retina's cellular apparatus, and include AVA-101/201, ADVM-202/302, AAV2-sFLT01, RGX314, and Retinostat. Expert opinion: There are many emerging anti-VEGF treatments that aim to improve visual outcomes and reduce the treatment burden of nAMD.

Pulmonary vascular inflammation: effect of TLR signalling on angiopoietin/TIE regulation.

Increased pulmonary vascular resistance is a critical complication in sepsis. Toll-like receptor (TLR) as well as angiopoietin (ANG) signalling both contribute to the emergence of pulmonary arterial hypertension. We hypothesized that TLR stimulation by bacterial ligands directly affects expression and secretion of ligands and receptors of the angiopoietin/TIE axis. Microvascular endothelial (HPMEC) and smooth muscle cells (SMC) of pulmonary origin were incubated with thrombin and with ligands for TLR2, -4, -5, and -9. Expression and secretion of ANG1, -2, TIE2 and IL-8 were determined using quantitative real-time PCR and ELISA. TLR stimulation had no impact either on the expression of ANG2 and TIE2 in HPMEC or on that of ANG1 in SMC. However, overall levels of both released ANG1 and -2 were halved upon stimulation with the TLR9 ligand CpG, and ANG2 release was significantly enhanced by TLR4 activation when initially provoked by sequentially performed stimulation. Furthermore, enhanced ANG2 activity increased endothelial permeability, as demonstrated in an in vitro transwell assay. We conclude that sole TLR stimulation by bacterial ligands plays no significant role for altered expression and secretion of ANG1, -2 and TIE2 in human pulmonary vascular cells. The interplay between various stimuli is required to induce imbalances between ANG1 and -2.

Genetic dissection of tie pathway in mouse lymphatic maturation and valve development.

OBJECTIVE: The genetic program underlying lymphatic development is still incompletely understood. This study aims to dissect the role of receptor tyrosine kinase with immunoglobulin-like and EGF (epidermal growth factor)-like domains 1 (Tie1) and Tie2 in lymphatic formation using genetically modified mouse models. APPROACH AND RESULTS: We generated conditional knockout mouse models targeting Tie1, Tie2, and angiopoietin-2 in this study. Tie1(ΔICD/ΔICD) mice, with its intracellular domain targeted, appeared normal at E10.5 but displayed subcutaneous edema by E13.5. Lymph sac formation occurred in Tie1(ΔICD/ΔICD) mice, but they had defects with the remodeling of primary lymphatic network to form collecting vessels and valvulogenesis. Consistently, induced deletion of Tie1-ICD postnatally using a ubiquitous Cre deleter led to abnormal lymphangiogenesis and valve formation in Tie1-ICD(iUCKO/-) mice. In comparison with the lymphatic phenotype of Tie1 mutants, we found that the diameter of lymphatic capillaries was significantly less in mice deficient of angiopoietin-2, besides the disruption of collecting lymphatic vessel formation as previously reported. There was also no lymphedema observed in Ang2(-/-) mice during embryonic development, which differs from that of Tie1(ΔICD/ΔICD) mice. We further investigated whether Tie1 exerted its function via Tie2 during lymphatic development. To our surprise, genetic deletion of Tie2 (Tie2(iUCKO/-)) in neonate mice did not affect lymphatic vessel growth and maturation. CONCLUSIONS: In contrast to the important role of Tie2 in the regulation of blood vascular development, Tie1 is crucial in the process of lymphatic remodeling and maturation, which is independent of Tie2.

A phase 1b study of trebananib in combination with pegylated liposomal doxorubicin or topotecan in women with recurrent platinum-resistant or partially platinum-sensitive ovarian cancer.

OBJECTIVE: To examine the tolerability and antitumor activity of trebananib plus pegylated liposomal doxorubicin (PLD) or topotecan in recurrent platinum-resistant or partially platinum-sensitive ovarian cancer. METHODS: In this open-label phase 1b study, patients received trebananib 10 mg/kg or 15 mg/kg IV QW plus PLD 50 mg/m(2) (cohorts A1 and A3, respectively) or topotecan 4 mg/m(2) (cohorts B1 and B3, respectively). Endpoints were dose-limiting toxicity (DLT; primary); treatment-emergent adverse events (AEs), overall response rate, anti-trebananib antibodies, and pharmacokinetics (secondary). RESULTS: 103 patients were enrolled. One patient in A1 and B1 had DLTs. Across all cohorts, the most common AEs were nausea, fatigue, and peripheral edema. Across both trebananib plus PLD cohorts (A1/A3), grade 4 AEs were pulmonary embolism, disease progression, and anemia. Two patients had grade 5 intestinal perforation (n=1) and sudden death (n=1). Across both trebananib plus topotecan cohorts (B1/B3), grade 4 AEs were neutropenia, hypokalemia, decreased granulocyte count, chest pain, dyspnea, decreased neutrophil count, and pulmonary embolism. Two patients had grade 5 disease progression. One patient had grade 5 pleural effusion associated with progressive disease. Confirmed objective response rates were 36.0% (A1), 34.8% (A3), 16.7% (B1), and 0.0% (B3). Median progression-free survival duration (months) was 7.4 (A1), 7.1 (A3), 3.5 (B1), and 3.1 (B3), respectively. No drug-drug interactions were apparent. CONCLUSIONS: Trebananib 10mg/kg and 15 mg/kg IV QW plus PLD or topotecan appear to have acceptable toxicity profiles in recurrent platinum-resistant or partially platinum-sensitive ovarian cancer. Antitumor activity was evident across all cohorts.

Rebastinib attenuates liver injury following cecal ligation and puncture in male mice.

Sepsis remains a public health issue with high morbidity and mortality. Liver injury due to sepsis is associated with poor outcomes and an increased risk of death among septic patients. Rebastinib is a small molecule inhibiting the Tie2 receptor and vascular endothelial growth factor receptor-2 (VEGFR2). The current study aimed to reveal the potential protective impact of Rebastinib against sepsis-induced liver injury. Twenty-four adult male mice were allocated into four groups (six per group) as follows: Sham group was exposed to anesthesia and laparotomy with no cecal ligation and puncture procedure (CLP); CLP group was subjected CLP procedure; vehicle-treated group was pretreated with vehicle (oral route) one hour prior to CLP procedure; Rebastinib group was pretreated with oral Rebastinib one hour before induction of CLP. Collected blood was used to measure the serum levels of AST, ALT, and angiopoietin 2. Homogenized liver tissues were used to investigate IL-6, TNF-α, ICAM-1, MIF, VEGF, F2-isoprostanes, and caspase-11 levels. Histological examination was used to determine the severity of liver damage. Compared to the sham group, mice subjected to CLP had high levels of these biomarkers with a high degree of liver injury. In contrast, Rebastinib markedly reduced these levels and mitigated the liver damage. Rebastinib may be a hepatoprotective agent against sepsis-associated liver injury.

Paricalcitol Improves the Angiopoietin/Tie-2 and VEGF/VEGFR2 Signaling Pathways in Adriamycin-Induced Nephropathy.

Renal endothelial cell (EC) injury and microvascular dysfunction contribute to chronic kidney disease (CKD). In recent years, increasing evidence has suggested that EC undergoes an endothelial-to-mesenchymal transition (EndoMT), which might promote fibrosis. Adriamycin (ADR) induces glomerular endothelial dysfunction, which leads to progressive proteinuria in rodents. The activation of the vitamin D receptor (VDR) plays a crucial role in endothelial function modulation, cell differentiation, and suppression of the expression of fibrotic markers by regulating the production of nitric oxide (NO) by activating the endothelial NO synthase (eNOS) in the kidneys. This study aimed to evaluate the effect of paricalcitol treatment on renal endothelial toxicity in a model of CKD induced by ADR in rats and explore mechanisms involved in EC maintenance by eNOS/NO, angiopoietins (Angs)/endothelium cell-specific receptor tyrosine kinase (Tie-2, also known as TEK) and vascular endothelial growth factor (VEGF)-VEGF receptor 2 (VEGFR2) axis. The results show that paricalcitol attenuated the renal damage ADR-induced with antiproteinuric effects, glomerular and tubular structure, and function protection. Furthermore, activation of the VDR promoted the maintenance of the function and structure of glomerular, cortical, and external medullary endothelial cells by regulating NO production. In addition, it suppressed the expression of the mesenchymal markers in renal tissue through attenuation of (transforming growth factor-beta) TGF-ß1/Smad2/3-dependent and downregulated of Ang-2/Tie-2 axis. It regulated the VEGF/VEGFR2 pathway, which was ADR-deregulated. These effects were associated with lower AT1 expression and VDR recovery to renal tissue after paricalcitol treatment. Our results showed a protective role of paricalcitol in the renal microvasculature that could be used as a target for treating the beginning of CKD.

Notoginsenoside R1 activates the Ang2/Tie2 pathway to promote angiogenesis.

BACKGROUND: Therapeutic angiogenesis is a novel strategy for the treatment of ischemic diseases that involves promotion of angiogenesis in ischemic tissues via the use of proangiogenic agents. However, effective proangiogenic drugs that activate the Ang2/Tie2 signaling pathway remain scarce. PURPOSE: We aimed to investigate the proangiogenic activity of notoginsenoside R1 (NR1) isolated from total saponins of Panax notoginseng with regard to activation of the Ang2/Tie2 signaling pathway. METHODS: We examined the proangiogenic effects of NR1 by assessing the effects of NR1 on the proliferation, migration, invasion and tube formation of human umbilical vein endothelial cells (HUVECs). The aortic ring assay and vascular endothelial growth factor receptor inhibitor (VRI)-induced vascular regression in the zebrafish model were used to confirm the proangiogenic effects of NR1 ex vivo and in vivo. Furthermore, the molecular mechanism was investigated by Western blot analysis. RESULTS: We found that NR1 promoted the proliferation, mobility and tube formation of HUVECs in vitro. NR1 also increased the number of sprouting vessels in rat aortic rings and rescued VRI-induced vascular regression in zebrafish. NR1-induced angiogenesis was dependent on Tie2 receptor activation mediated by increased autocrine Ang2 in HUVECs, and inhibition of the Ang2/Tie2 pathway abrogated the proangiogenic effects of NR1. CONCLUSIONS: Our results suggest that NR1 promotes angiogenesis by activating the Ang2/Tie2 signaling pathway. Thus, NR1-induced activation of the Ang2/Tie2 pathway is an effective proangiogenic approach. NR1 may be useful agent for the treatment of ischemic diseases.

Targeting Angiopoietin in Retinal Vascular Diseases: A Literature Review and Summary of Clinical Trials Involving Faricimab.

This review summarizes the latest findings in the literature of Angiopoietin-2 (Ang-2), Tyrosine-protein kinase receptor (Tie-2) complex, and faricimab along with their involvement for the treatment of retinal vascular diseases in various clinical trials. In ischemic diseases, such as diabetic retinopathy, Ang-2 is upregulated, deactivating Tie-2, resulting in vascular leakage, pericyte loss, and inflammation. Recombinant Angiopeotin-1 (Ang-1), Ang-2-blocking molecules, and inhibitors of vascular endothelial protein tyrosine phosphatase (VE-PTP) decrease inflammation-associated vascular leakage, showing therapeutic effects in diabetes, atherosclerosis, and ocular neovascular diseases. In addition, novel studies show that angiopoietin-like proteins may play an important role in cellular metabolism leading to retinal vascular diseases. Current therapeutic focus combines Ang-Tie targeted drugs with other anti-angiogenic or immune therapies. Clinical studies have identified faricimab, a novel bispecific antibody designed for intravitreal use, to simultaneously bind and neutralize Ang-2 and VEGF-A for treatment of diabetic eye disease. By targeting both Ang-2 and vascular endothelial growth factor-A (VEGF-A), faricimab displays an improved and sustained efficacy over longer treatment intervals, delivering superior vision outcomes for patients with diabetic macular edema and reducing the treatment burden for patients with neovascular age-related macular degeneration and diabetic macular edema. Phase 2 results have produced promising outcomes with regard to efficacy and durability. Faricimab is currently being evaluated in global Phase 3 studies.

Innovative therapies for neovascular age-related macular degeneration.

Introduction: Investigational anti-VEGF treatments for neovascular age-related macular degeneration (nAMD) aim to improve visual outcomes and reduce treatment burden; these include long-acting agents, combination strategies, topical agents, sustained-release, and genetic therapies. Areas covered: The authors provide a comprehensive review of investigational therapies for nAMD, focusing on therapies currently in clinical trial. Expert opinion: Long-acting anti-VEGF agents have demonstrated promising results in phase 3 studies, and include Brolucizumab, a single-chain antibody fragment, and Abicipar, a designed ankyrin repeat protein (DARPin). Other unique anti-VEGF agents in current trials include Conbercept - a fusion protein of the VEGF receptor domains, KSI-301 - an anti-VEGF antibody biopolymer conjugate, and OPT-302 - an inhibitor of VEGF-C/D. Strategies to activate the Tie-2 receptor, some in combination with VEGF inhibition, are of interest, with recent trials of Faricimab, ARP-1536, and nesvacumab. Topical anti-VEGF ± anti-PDGF agents, such as pazopanib, squalamine lactate, regorafenib, and LHA510 have shown limited efficacy and/or have not been advanced, although PAN-90806 continues to advance with promising initial results. Sustained-release anti-VEGF treatments, to address treatment burden, include the ranibizumab Port Delivery System, GB-102, NT-503, hydrogel depot, Durasert, and ENV1305. Similarly, genetic therapies, including RGX-314 and ADVM-022, aim to provide sustained anti-VEGF expression from the retina.

Tie-2/Angiopoietin pathway modulation as a therapeutic strategy for retinal disease.

Introduction: The Tie-2/Angiopoietin pathway is a therapeutic target for the treatment of neovascular age-related macular degeneration (nAMD) and diabetic macular edema (DME). Activation of Tie-2 receptor via Ang-1 maintains vascular stability to limit exudation. Ang-2, a competitive antagonist to Ang-1, and VE-PTP, an endothelial-specific phosphatase, interfere with the Tie-2-Ang-1 axis, resulting in vascular leakage. Areas covered: Faricimab, a bispecific antibody that inhibits VEGF-A and Ang-2, is in phase 3 trials for nAMD and DME. Nesvacumab is an Ang-2 inhibitor; when coformulated with aflibercept, it failed to show benefit over aflibercept monotherapy in achieving visual gains in phase 2 studies of nAMD and DME. ARP-1536 is an intravitreally administered VE-PTP inhibitor undergoing preclinical studies. AKB-9778 is a subcutaneously administered VE-PTP inhibitor that, when combined with monthly ranibizumab, reduced DME more effectively than ranibizumab monotherapy in a phase 2 study. AKB-9778 monotherapy did not reduce diabetic retinopathy severity score compared to placebo. AXT107, currently in the preclinical phase, promotes conversion of Ang-2 into a Tie-2 agonist and blocks signaling through VEGFR2 and other receptor tyrosine-kinases. Expert opinion: Tie-2/Angiopoietin pathway modulators show promise to reduce treatment burden and improve visual outcomes in nAMD and DME, with potential to treat cases refractory to current treatment modalities.

Endothelial Activation: The Ang/Tie Axis in Sepsis.

Sepsis, a dysregulated host response to infection that causes life-threatening organ dysfunction, is a highly heterogeneous syndrome with no specific treatment. Although sepsis can be caused by a wide variety of pathogenic organisms, endothelial dysfunction leading to vascular leak is a common mechanism of injury that contributes to the morbidity and mortality associated with the syndrome. Perturbations to the angiopoietin (Ang)/Tie2 axis cause endothelial cell activation and contribute to the pathogenesis of sepsis. In this review, we summarize how the Ang/Tie2 pathway is implicated in sepsis and describe its prognostic as well as therapeutic utility in life-threatening infections.

Expressions and Clinical Significances of Angiopoietin-1, Angiopoietin-2, and Tie-2 Receptor in Patients With Colorectal Cancer.

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.

Role of Angiopoietins and Tie-2 in Diabetic Retinopathy.

OBJECTIVE: The aim of this study was to determine the serum levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), soluble vascular endothelial tyrosine kinase receptor (Tie-2) and vascular endothelial growth factor (VEGF), in the serum of type 2 diabetic patients having non-proliferative (NPDR) or proliferative diabetic retinopathy (PDR). METHODS: One hundred patients with type 2 diabetes mellitus were involved in this cross-sectional study. They were classified into 25 diabetic patients without retinopathy, 35 patients with NPDR and 40 PDR patients. The study was carried out in the outpatients clinic of the Research Institute of Ophthalmology, Giza, Egypt from August 2016 through May 2017. Serum VEGF, Ang-1, Ang-2 and Tie-2 receptor levels were assayed using enzyme linked immunosorbent assay (ELISA). Data were analyzed by SPSS version 20 and Microsoft Excel (Version 10) using ANOVA, Harman's single factor test, and Pearson's Product Moment Correlation. RESULTS: The serum levels of Ang-2 and VEGF were significantly elevated in NPDR groups and PDR group compared to diabetics without retinopathy groups (p<0.001). The serum levels of Ang-1 were significantly higher in the NPDR group compared to the diabetics without retinopathy groups (p<0.01), while no significant difference was observed between the PDR and diabetics without retinopathy groups. Ang-1/Ang-2 ratio was the lowest in the PDR group compared to the NPDR and diabetics without retinopathy groups. The serum levels of Tie-2 were not significantly changed among the three studied groups, serum Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups. CONCLUSION: The angiopoietin/Tie system and VEGF are essential features in the commencement and development of PDR.

The Osmopressor-Induced Angiopoietin-1 Secretion in Plasma and Subsequent Activation of the Tie-2/Akt/eNOS Signaling Pathway in Red Blood Cell.

BACKGROUND: Water ingestion induces the osmopressor response, which typically presents as increased total peripheral vascular resistance in young healthy subjects. A previous study has suggested that the RBC membrane receptor is involved in osmopressor stress. Recent studies have indicated nitric oxide synthase phosphorylation in RBCs. However, the main process in signaling pathway activation to elicit such a response is unknown. Herein, we hypothesized that hypo-osmotic stress following water ingestion modulates the eNOS/NO pathway, thereby alternating vascular resistance. METHODS: We included 24 young, healthy subjects. Physiological parameters and blood samples were collected at 5 minutes before and 25 and 50 minutes after 50 ml water, 500 ml water, or 500 ml normal saline ingestion. A human receptor tyrosine kinase (RTK) phosphorylation antibody array was used to simultaneously detect and monitor the biological activation pathways in RBCs. RESULTS: Of the 71 RTKs assayed during the osmopressor response, several RTKs were significantly upregulated, including Tie-2 and Tie-1. Plasma angiopoietin-1 levels significantly increased at 25 minutes after 500 ml water ingestion compared to those at baseline. Simultaneous phosphorylation of Tie-2, Akt, and eNOS in RBCs occurred. RBCs in vitro were stimulated with angiopoietin-1, Tie-2, or 0.8% saline and showed significant increase in Tie-2, Akt, and eNOS phosphorylation upon angiopoietin-1 treatment and enhanced activation upon cotreatment of angiopoietin-1 and 0.8% saline. CONCLUSIONS: The hypo-osmotic stimulus of water ingestion increases angiopoietin-1 secretion and subsequently activates the Tie-2/Akt/eNOS signaling pathway in RBCs, thereby revealing a novel biological mechanism simultaneously occurring with the osmopressor response.

Effect of propranolol on angiopoietin and Tie2 in nude mice model with hemangioma / 中华医学美学美容杂志

Objective:To investigate the effect of propranolol on angiopoietin and its receptor in the nude mouse model of infantile hemangioma, so as to clarify the mechanism of propranolol in the treatment of hemangioma.Methods:The proliferative hemangioma tissue from the 980 Hospital of PLA was transplanted into the back of 50 female nude mice during May 2015 to Sept. 2016. After establishment of the hemangioma model, the nude mice were randomly divided into two groups, 25 in each group. The experimental group was gavaged with 0.4 ml propranolol every 2 days, and the control group was gavaged with normal saline every 2 days. The mice were killed in batches on the 7th, 14th, 21st and 28th day, the tumor morphology was observed by HE staining. The expression of VEGF, Ang1, Ang2 and Tie2 protein in hemangiomas was detected by immunohistochemistry and Western blot.Results:After 28 days, the hemangioma in propranolol group showed regression phase. The endothelial cells of hemangioma decreased, and the nuclear staining became shallow, the lumen enlarged, and fibrous connective tissue could be seen between the blood vessels. The expression of VEGF, Ang2 and Tie2 was lower than those in the control group ( P<0.05), and the expression of VEGF, Ang2 and Tie2 was decreased by 47.1%, 34.7% and 37.5%, respectively, while the expression of Ang1 was increased by 40.5% compared with the control group ( P<0.05). Conclusions:Propranolol may inhibit the growth of hemangioma in nude mice by promoting the expression of Ang1 and inhibiting the expression of VEGF, Ang2 and Tie2.