Anti-VEGF therapy reduces intestinal inflammation in Endoglin heterozygous mice subjected to experimental colitis

Chronic intestinal inflammation is associated with pathological angiogenesis that further amplifies the inflammatory response. Vascular endothelial growth factor (VEGF), is a major angiogenic cytokine that has been implicated in chronic colitis and inflammatory bowel diseases. Endoglin (CD105), a transforming growth factor-β superfamily co-receptor expressed on endothelial and some myeloid cells, is a modulator of angiogenesis involved in wound healing and potentially in resolution of inflammation. We showed previously that Endoglin heterozygous (Eng ^+/?) mice subjected to dextran sodium sulfate developed severe colitis, abnormal colonic vessels and high tissue VEGF. We therefore tested in the current study if treatment with a monoclonal antibody to VEGF could ameliorate chronic colitis in Eng ^+/? mice. Tissue inflammation and microvessel density (MVD) were quantified on histological slides. Colonic wall thickness, microvascular hemodynamics and targeted MAdCAM-1⁺ inflamed vessels were assessed in vivo by ultrasound. Mediators of angiogenesis and inflammation were measured by Milliplex and ELISA assays. Colitic Eng ^+/? mice showed an increase in intestinal inflammation, MVD, colonic wall thickness, microvascular hemodynamics and the number of MAdCAM-1⁺ microvessels relative to colitic Eng ^+/+ mice; these parameters were all attenuated by anti-VEGF treatment. Of all factors up-regulated in the inflamed gut, granulocyte colony-stimulating factor (G-CSF) and amphiregulin were further increased in colitic Eng ^+/? versus Eng ^+/+ mice. Anti-VEGF therapy decreased tissue VEGF and inflammation-induced endoglin, IL-1β and G-CSF in colitic Eng ^+/? mice. Our results suggest that endoglin modulates intestinal angiogenic and inflammatory responses in colitis. Furthermore, contrast-enhanced ultrasound provides an excellent non-invasive imaging modality to monitor gut angiogenesis, inflammation and responses to anti-angiogenic treatment.     

Persistent infiltration and pro-inflammatory differentiation of monocytes cause unresolved inflammation in brain arteriovenous malformation

An abnormally high number of macrophages are present in human brain arteriovenous malformations (bAVM) with or without evidence of prior hemorrhage, causing unresolved inflammation that may enhance abnormal vascular remodeling and exacerbate the bAVM phenotype. The reasons for macrophage accumulation at the bAVM sites are not known. We tested the hypothesis that persistent infiltration and pro-inflammatory differentiation of monocytes in angiogenic tissues increase the macrophage burden in bAVM using two mouse models and human monocytes. Mouse bAVM was induced through deletion of AVM causative genes, Endoglin (Eng) globally or Alk1 focally, plus brain focal angiogenic stimulation. An endothelial cell and vascular smooth muscle cell co-culture system was used to analyze monocyte differentiation in the angiogenic niche. After angiogenic stimulation, the Eng-deleted mice had fewer CD68⁺ cells at 2 weeks (P = 0.02), similar numbers at 4 weeks (P = 0.97), and more at 8 weeks (P = 0.01) in the brain angiogenic region compared with wild-type (WT) mice. Alk1-deficient mice also had a trend toward more macrophages/microglia 8 weeks (P = 0.064) after angiogenic stimulation and more RFP⁺ bone marrow-derived macrophages than WT mice (P = 0.01). More CD34⁺ cells isolated from peripheral blood of patients with ENG or ALK1 gene mutation differentiated into macrophages than those from healthy controls (P < 0.001). These data indicate that persistent infiltration and pro-inflammatory differentiation of monocytes might contribute to macrophage accumulation in bAVM. Blocking macrophage homing to bAVM lesions should be tested as a strategy to reduce the severity of bAVM.     

Expression pattern of angiogenic factors and prognosis after hepatic resection in hepatocellular carcinoma: importance of angiopoietin-2 and hypoxia-induced factor-1 alpha.

BACKGROUND: Hepatocellular carcinoma (HCC) is a hypervascular tumor and angiogenesis plays an important role in its progression. Angiogenesis is regulated by a balance between pro and antiangiogenic molecules. The aim of this study was to investigate the expressions of angiogenic factors and elucidate their roles in angiogenesis in HCC. METHODS: We investigated immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietins (Ang-1 and Ang-2), hypoxia-induced factor-1alpha (HIF-1alpha) and thrombospondin-1 (TSP-1) in 60 specimens of surgically resected HCC. We investigated the relationship between their expressions and clinicopathological factors or prognosis. RESULTS: Ang-2 staining had a significant correlation with the grade of differentiation of HCC cells (P=0.0082). VEGF and Ang-2 expression correlated positively with microvessel density (MVD) (P=0.0061 and 0.0374, respectively). MVD of well-differentiated HCC were significantly lower than those of moderately and poorly differentiated HCC. The disease-free survival time of patients with high Ang-2 and/or HIF-1alpha expression was significantly shorter than that of the low expression group (P=0.0278 and 0.0374, respectively). CONCLUSION: Our study showed that the expression of VEGF and Ang-2 correlated with MVD. Strong Ang-2 expression and/or high nuclear expression of HIF-1alpha is a significant predictive factor for recurrence after curative resection in HCC patients.     

Lack of thrombospondin-1 increases angiogenesis in a model of chronic inflammatory bowel disease

Background and aims

Vascular abnormalities and expression of pro-angiogenic factors are observed in inflammatory bowel diseases (IBD). In this study, the role of thrombospondin-1 (TSP-1), an antiangiogenic protein, was analyzed using the dextran sulfate sodium (DSS) model for IBD.

Materials and methods

Wild-type (WT) and thrombospondin-1-deficient (TSP-1^-/-) mice were subjected to four cycles (7 days) of DSS. Basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), transforming growth factor beta 1 (TGFß-1), and pro-apoptotic proteins such as Fas and its ligand (FasL) were determined by enzyme-linked immunosorbent assay. Double immunohistochemistry for cluster of differential 31 (CD31) and panendothelial cell antigen-32 antibodies was performed for detecting blood vessels. The terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay was also performed for identifying apoptotic cells. Inflammation, dysplasia, microvascular density (MVD), apoptotic indices (AI), protein 53 (p53), and ß-catenin expression were determined.

Results

VEGF and bFGF protein levels and MVD were higher in the TSP-1^-/- mice (p?=?0.0312, p?=?0.0246, and p?=?0.0085, respectively). AI in the endothelial cells (EC) and FasL levels were significantly lower in TSP-1^-/- compared to WT mice (p?=?0.0042 and p?=?0.0362, respectively). Dysplasia was detected in 66% of TSP-1^-/- mice compared to 14% in WT mice. Hscores of ß-catenin and areas overexpressing p53 were higher in TSP-1^-/- mice (p?=?0.0002 and p?=?0.0339, respectively).

Conclusion

TSP-1 may decrease angiogenesis by reducing the levels of pro-angiogenic factors and inducing apoptosis in EC through the Fas or FasL pathway. These findings, along with the increased overexpression of p53 and ß-catenin in TSP-1^-/- mice, underline its role in carcinogenesis.

     

Plasma and platelet-derived vascular endothelial growth factor and angiopoietin-1 in hypertension: effects of antihypertensive therapy

BACKGROUND: Platelets carry angiogenic growth factors vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1). Although platelet-derived growth factors are important in the pathogenesis and metastasis of malignancy, their role in the pathogenesis of complications and the response to treatment in hypertension is less known. OBJECTIVE: To test the hypotheses that there are differences in VEGF and Ang-1 in the plasma and within platelets from patients with hypertension, and that levels change with successful treatment. METHODS: We recruited 42 previously untreated patients with hypertension (25 male; mean age 53 years) and 30 age- and sex-matched controls. Plasma VEGF, Ang-1 and soluble P-selectin (sPsel, an index of platelet activation), and total platelet [platelet VEGF (pVEGF) and platelet Ang-1 (pAng-1)] were measured by ELISA. The patients were then treated for 6 months with amlodipine-based antihypertensive therapy, achieving a mean blood pressure below 140/80 mmHg. RESULTS: Patients with hypertension had significantly higher levels of plasma sPsel (P =0.01), VEGF (P < 0.001) and Ang-1 (P = 0.01), as well as pVEGF (P < 0.001) and pAng-1 (P =0.02). The levels of plasma and platelet angiogenic growth factors were significantly reduced after antihypertensive treatment (VEGF, P = 0.01; pVEGF, P < 0.001; Ang-1, P < 0.001; pAng-1, P = 0.04). There were no correlations with blood pressure or the levels of sPsel. CONCLUSION: Levels of plasma and intra-platelet VEGF and Ang-1 are increased in hypertension and are decreased with treatment. Platelet levels of VEGF and Ang-1 may be related to platelet activation but may also involve other mechanisms (for example, the general vascular and haemodynamic changes) that are seen in hypertension.     

Angiogenic growth factors in rheumatoid arthritis

We investigated whether the angiogenic profile, which is based on the local expression and systemic levels of angiogenic growth factors (VEGF, Ang-1, Ang-2, and the corresponding receptors), differs between rheumatoid arthritis (RA) and osteoarthritis (OA) patients. We determined the expression of VEGF, Ang-1, and Ang-2 together with its receptors (VEGFR-1/-2 and Tie2) in synovium tissue (ST) and muscular tissue (MT) from patients with RA and OA using quantitative PCR. Tissue samples were obtained from 15 RA and 19 OA patients during total knee arthroplasty. Control MT samples (n = 10) were obtained during spinal surgery. Results are correlated to VEGF and angiopoietin serum levels via ELISA measurements. The VEGF expressions in ST and serum levels were significantly higher in RA patients than in OA patients (P < 0.05). Furthermore, the VEGFR-1 and VEGFR-2 expression in ST from RA patients were significantly higher than in OA patients (P < 0.001 and P < 0.05). The relative concentration of angiopoietins (Ang-1/Ang-2 ratio) was significantly increased in RA (P < 0.01). Serum levels for Ang-2 showed no significant differences. Statistical analysis showed a significant higher level of Tie2 in RA patients (P < 0.001). Analysis of local levels of VEGF, VEGFR-1, VEGFR-2, Ang-1, Ang-2, and Tie2 in the muscular tissue showed no significant difference between RA and OA patients. These results underline the importance of pro-angiogenic growth factor levels for RA corroborating the assumption that VEGF and angiopoietins play an important role in the pathogenesis of RA.     

Exploring the link between serum peroxides and angiogenesis in a bi-ethnic population from South Africa: The SAfrEIC study

BackgroundReactive oxygen species (ROS) play a fundamental role in angiogenesis, and in turn, angiogenic growth factors also affect ROS. Angiogenesis and ROS are intricately involved in vascular deterioration. Since black populations are known to have elevated oxidative stress and hypertension, we determined whether relationships exist between angiogenic growth factors and serum peroxides in Africans and Caucasians and evaluated the relationships with cardiovascular measurements.MethodsWe measured vascular endothelial growth factor-A (VEGF), angiopoietin 2 (Ang-2), and serum peroxides in Africans (N = 262) and Caucasians (N = 364) aged 20 to 70 years.ResultsAfricans displayed higher blood pressure, serum peroxide levels, VEGF, and Ang-2 (all P ≤ .002) than similarly aged Caucasians (P = .44). In multivariable adjusted analyses, Ang-2 was independently associated with serum peroxides in African men (R² = 0.31; β = 0.21; P = .014) and women (R² = 0.09; β = 0.22; P = .025); and VEGF with serum peroxides in African men (R² = 0.12; β = 0.24; P = .014), with no statistically significant associations in Caucasians. Cardiovascular measurements did not associate with serum peroxides or angiogenic factors in any subgroup.ConclusionsSignificant independent relationships exist between angiogenic growth factors and serum peroxides only in Africans who also displayed an unfavorable cardiovascular profile when compared with Caucasians. These results suggest that interplay between ROS and angiogenesis occur in African individuals that may form part of the mechanisms involved in vascular deterioration.     

Prospective, randomized, single-blind comparison of effects of 6?months' treatment with atorvastatin versus pravastatin on leptin and angiogenic factors in patients with coronary artery disease

Leptin has been reported to exert an atherosclerotic effect by regulating expression of angiogenic factors that have been implicated in the pathogenesis of coronary artery disease (CAD). The purpose of this study was to investigate whether lipid-lowering therapy (LLT) with statins could affect leptin levels and angiogenic factors in patients with CAD. This study included 76 patients with CAD and 15 subjects without CAD (non-CAD). CAD patients were randomized to 6?months of intensive LLT with atorvastatin or moderate LLT with pravastatin. Plasma leptin, angiopoetin-2 (Ang-2), hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) levels were measured prior to statin therapy (baseline) and after 6?months. Baseline levels of leptin, Ang-2, HGF and VEGF were higher in the CAD group than in the non-CAD group (all P?<?0.05). Treatment with intensive LLT decreased leptin, Ang-2, HGF and VEGF levels, whereas moderate LLT did not change these levels. This study suggests that LLT with atorvastatin decreases leptin levels and angiogenic factors in patients with CAD, possibly contributing to the beneficial effects of LLT with atorvastatin in CAD.     

PD-L1 expression correlates with VEGF and microvessel density in patients with uniformly treated classical Hodgkin lymphoma

Recent studies have reported the associations between programmed death-ligand 1 (PD-L1) or PD-L2/PD-1 pathways and pro-angiogenic genes including hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF) in several malignancies. However, no study has examined the relationship or prognostic implication of PD-L1, PD-L2, PD-1, VEGF expression, and microvessel density (MVD) in classical Hodgkin lymphoma (cHL) patients. Diagnostic tissues from 109 patients with doxorubicin, bleomycin, vinblastine, and dacarbazine-treated cHL were evaluated retrospectively by immunohistochemical analysis for PD-L1, PD-L2, PD-1, VEGF expression, and for CD31 expression as a measure of MVD. There was a positive correlation between PD-L1 and VEGF expression (P = 0.008) and additionally between PD-L2 and VEGF expression (P = 0.001). The mean MVD in tumors positive for both PD-L1 and VEGF was significantly (P = 0.022) higher than the mean MVD in tumors negative for both markers. High PD-1 expression group had lower (P = 0.019) 5-year overall survival rate than low PD-1 expression group. Multivariate analysis revealed that PD-1 was an independent prognostic factor for cHL with significance (P = 0.026). However, PD-L1, PD-L2, and VEGF expression had no prognostic impact. Our data confirmed the positive correlations between PD-L1, VEGF, or MVD. Our findings provided evidence supporting new therapeutic approaches including combinations of anti-PD-L1/PD-1 and anti-VEGF therapy in addition to the current standard regimen for cHL.     

Regulation of angiogenesis in the bone marrow of myelodysplastic syndromes transforming to overt leukaemia

To investigate the regulatory mechanisms of angiogenesis in the development of myelodysplastic syndromes (MDS) and its progression to overt leukaemia (OL), bone marrow samples from control, paired samples from MDS patients before and after transformation to OL (MDS --> OL) and de novo acute myeloid leukaemia (AML) were analysed. Immunohistochemical staining showed a significant increase of bone marrow microvascular density (MVD) in MDS and de novo AML compared with controls. Surprisingly, in MDS, MVD significantly decreased upon transformation to OL, which was also significantly lower than the MVD of de novo AML. This evidence was strengthened by the pattern of angiogenic mediator gene expression, confirming the importance of various angiogenic mediators including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), tumour necrosis factor alpha (TNFalpha), hepatocyte growth factor (HGF) and the angiopoietin family of mediators (Ang-1 and Ang-2) as well as the receptors for angiogenic mediators, such as VEGF receptor 2 (VEGFR2) and the tyrosine kinase receptor, TIE2. By contrast, the anti-angiogenic mediator, transforming growth factor-beta (TGFbeta) exhibited significantly higher expression in the bone marrow of MDS --> OL, indicating the importance of this cytokine as the suppressive factor of angiogenesis in MDS. These findings indicate that the bone marrow microenvironment in MDS --> OL and de novo AML differs remarkably, suggesting the different efficacy of anti-angiogenic therapy between de novo AML and leukaemia secondary to MDS.     

肾上腺皮质肿瘤VEGF、TSP-1的表达及其与微血管密度的关系

目的 研究血管内皮生长因子(VEGF)、血小板反应素1(TSP-1)在肾上腺皮质肿瘤中的表达及其与微血管密度(MVD)的关系.方法 采用免疫组化方法检测13例肾上腺皮质癌、30例肾上腺皮质腺瘤和7例正常肾上腺组织中VEGF、TSP-1及MVD(以CD34为标记)的表达.结果 肾上腺皮质癌VEGF表达高于肾上腺皮质腺瘤,差异有统计学意义(P＜0.01);TSP-1在正常肾上腺皮质表达明显高于肾上腺皮质癌(P＜0.01);MVD在肾上腺皮质癌为(107.67±11.91)/视野,显著高于肾上腺皮质腺瘤(59.46±21.31)/视野和正常肾上腺皮质组织(25.10±3.94)/视野(均P＜0.01);VEGF的表达与MVD呈正相关(P＜0.01),TSP-1的表达与MVD呈负相关(P＜0.01),VEGF与TSP-1的表达呈负相关(P＜0.01).结论 VEGF和TSP-1在肾上腺皮质肿瘤的表达失衡是其肿瘤血管异常生成的重要原因.     

Arterial endothelium-specific activin receptor-like kinase 1 expression suggests its role in arterialization and vascular remodeling

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by epistaxis, mucocutaneous telangiectases, and arteriovenous malformations (AVM). Two genes are linked to HHT: endoglin (ENG) in HHT1 and activin receptor-like kinase 1 (ACVRL1; ALK1) in HHT2. Although both genes are involved in the transforming growth factor beta signaling pathways, the pathogenetic mechanisms for HHT remain elusive. It was shown that mutations in the Alk1 gene in mice and zebrafish resulted in an embryonic lethal phenotype due to severe dilation of blood vessels. We created a novel null mutant mouse line for Alk1 (Alk1lacZ) by replacing its exons, including the one that encodes the transmembrane domain, with the beta-galactosidase gene. Using Alk1lacZ mice, we show that Alk1 is predominantly expressed in developing arterial endothelium. Alk1 expression is greatly diminished in adult arteries, but is induced in preexisting feeding arteries and newly forming arterial vessels during wound healing and tumor angiogenesis. We also show that hemodynamic changes, which require vascular remodeling, may regulate Alk1 expression. Our studies suggest the role of Alk1 signaling in arterialization and remodeling of arteries. Contrary to the current view of HHT as venous disease, our findings suggest that the arterioles rather than the venules are the primary vessels affected by the loss of an Alk1 allele, and that blood vessels with reduction in Alk1 expression may harbor defects in responding to demands for vascular remodeling.     

Therapeutic effect of anti-vascular endothelial growth factor receptor I antibody in the established collagen-induced arthritis mouse model

Synovial angiogenesis plays an important role in the inflammation in rheumatoid arthritis (RA). Vascular endothelial growth factor (VEGF) is a key molecule in angiogenesis and binds to specific receptors, known as vascular endothelial growth factor receptor I (VEGF RI). In this study, we investigated the therapeutic efficacy of anti-VEGF RI antibody (Ab) on RA using a collagen-induced arthritis (CIA) mouse model. Twelve DBA/1 mice were divided into three groups. All mice except controls were injected with type II collagen. Mice in the anti-VEGF-RI-Ab-treated groups were injected on one posterior paw with 50 μg anti-VEGF RI Ab twice weekly for 3 weeks. Arthritis score and paw thickness were measured and histopathologic assessment of joint sections was performed by hematoxylin–eosin. The infiltration of CD45⁺ inflammatory cells and neovascularization were evaluated by immunohistochemical staining. Anti-VEGF RI Ab significantly attenuated the arthritis severity and histopathologic findings in the CIA mice model. The infiltration of CD45⁺ cells decreased in anti-VEGF-RI-Ab-treated joint tissues. Staining for CD31 revealed reduced synovial neovascularization after anti-VEGF RI Ab treatment. The data showing that in vivo administration of anti-VEGF RI Ab suppressed arthritis in established CIA mice suggest anti-VEGF RI Ab treatment may serve as a new therapeutic modality for RA.     

A monoclonal antibody that blocks VEGF binding to VEGFR2 (KDR/Flk-1) inhibits vascular expression of Flk-1 and tumor growth in an orthotopic human breast cancer model

Vascular endothelial growth factor (VEGF) is a primary stimulant of tumor angiogenesis. We previously raised a neutralizing anti-VEGF monoclonal antibody 2C3 that blocks the interaction of VEGF with VEGFR2 (KDR/Flk-1) but not with VEGFR1 (FLT-1/flt-1). Here, we describe the therapeutic effects of 2C3 on tumor growth in an orthotopic model of MDA-MB-231 human breast carcinoma implanted in the mammary fat pads (MFP) of nude mice. Administration of 2C3 to mice with 100–150 mm³ tumors inhibited tumor growth by 75%, as compared to recipients of the isotype-matched irrelevant control IgG, C44. Treatment with 2C3 also inhibited the establishment of tumor colonies and reduced tumor burden in the lungs of mice injected intravenously with MDA-MB-231 cells. No toxicity was observed in these studies. The mean microvascular density (MVD) of tumors in 2C3-treated mice was 55 ± 5 per mm², as compared to 188 ± 5 per mm² in the C44-treated control group. The decrease in MVD closely correlated with the degree of inhibition of tumor growth. Treated tumors mostly contained mid-size and large vessels. Microvessels were mainly confined to the peripheral layer of tumor that bordered on the normal MFP epithelium. Tumor vessels had decreased expression of VEGFR2, indicating that neutralization of tumor-derived VEGF by 2C3 down-regulates the expression of VEGFR2 on tumor vasculature. This, in turn, may limit re-initiation of angiogenesis by either tumor-derived or stromal VEGF. These findings suggest that 2C3 is a candidate for treating primary cancer and for preventing the outgrowth of tumor metastases in cancer patients.     

Mig6 haploinsufficiency protects mice against streptozotocin-induced diabetes

Aims/hypothesis

EGF and gastrin co-administration reverses type 1 diabetes in rodent models. However, the failure of this to translate into a clinical treatment suggests that EGF-mediated tissue repair is a complicated process and warrants further investigation. Thus, we aimed to determine whether EGF receptor (EGFR) feedback inhibition by mitogen-inducible gene 6 protein (MIG6) limits the effectiveness of EGF therapy and promotes type 1 diabetes development.

Methods

We treated Mig6 (also known as Errfi1) haploinsufficient mice (Mig6 ^+/?) and their wild-type littermates (Mig6 ^+/+) with multiple low doses of streptozotocin (STZ), and monitored diabetes development via glucose homeostasis tests and histological analyses. We also investigated MIG6-mediated cytokine-induced desensitisation of EGFR signalling and the DNA damage repair response in 832/13 INS-1 beta cells.

Results

Whereas STZ-treated Mig6 ^+/+ mice became diabetic, STZ-treated Mig6 ^+/? mice remained glucose tolerant. In addition, STZ-treated Mig6 ^+/? mice exhibited preserved circulating insulin levels following a glucose challenge. As insulin sensitivity was similar between Mig6 ^+/? and Mig6 ^+/+ mice, the preserved glucose tolerance in STZ-treated Mig6 ^+/? mice probably results from preserved beta cell function. This is supported by elevated Pdx1 and Irs2 mRNA levels in islets isolated from STZ-treated Mig6 ^+/? mice. Conversely, MIG6 overexpression in isolated islets compromises glucose-stimulated insulin secretion. Studies in 832/13 cells suggested that cytokine-induced MIG6 hinders EGFR activation and inhibits DNA damage repair. STZ-treated Mig6 ^+/? mice also have increased beta cell mass recovery.

Conclusions/interpretation

Reducing Mig6 expression promotes beta cell repair and abates the development of experimental diabetes, suggesting that MIG6 may be a novel therapeutic target for preserving beta cells.     

Levodopa Positively Affects Neovascular Age-Related Macular Degeneration

BackgroundAge-related macular degeneration (AMD) is a common cause of blindness worldwide. Neovascular AMD (nAMD) is an advanced form of the disease, in which excess vascular endothelial growth factor (VEGF) induces growth of new blood vessels that leak fluid, accounting for 90% of vision loss in AMD. Dysfunction of the retinal pigment epithelium likely initiates AMD. Retinal pigment epithelial cells express a G protein-coupled receptor, GPR143, which downregulates VEGF in response to levodopa. Anti-VEGF therapy effectively treats nAMD, suggesting that excessive VEGF activity drives the pathology.MethodsIn an open-label pilot study, in patients with newly diagnosed nAMD and naïve to anti-VEGF injections (Cohort-1), the effects of carbidopa-levodopa on vision and anatomic outcomes were evaluated for 4 weeks. Then patients were followed 5 months further with ascending levodopa doses. Patients previously treated with anti-VEGF injection therapy (Cohort-2) were also treated with ascending levodopa doses and evaluated for 6 months.ResultsLevodopa was safe, well tolerated, and delayed anti-VEGF injection therapy while improving visual outcomes. In the first month, retinal fluid decreased by 29% (P = .02, n = 12) without anti-VEGF treatment. Through 6 months the decrease in retinal fluid was sustained, with a mean frequency of 0.38 injections/month. At month 6, mean visual acuity improved by 4.7 letters in Cohort-1 (P = .004, n = 15) and by 4.8 letters in Cohort-2 (P = .02, n = 11). Additionally, there was a 52% reduction in the need for anti-VEGF injections in Cohort-2 (P = .002).ConclusionsOur findings suggest efficacy and support the pharmacological targeting of GPR143 with levodopa for the treatment of nAMD in future studies.     

Prognostic impact of angiopoietin-2 in multiple myeloma

Purpose

Angiogenesis is an essential process for the expansion of multiple myeloma (MM). Angiopoietin-2 (Ang-2), Ang-1 and their receptor possess important roles in this procedure. The aim of the study was to measure serum levels of Ang-2 along with known markers of angiogenesis and to estimate their prognostic impact on the survival.

Methods

Bone marrow microvascular density (MVD), estimated by CD31, and circulating levels of known angiogenic factors Ang-2, interleukin-6, soluble CD105 and platelet-derived growth factor-AB, measured by ELISA, were measured in 77 newly diagnosed patients with active MM and in 57 of them who responded to chemotherapy.

Results

All measured parameters were increased in MM patients, were also increasing in advanced disease and decreased after effective treatment. Ang-2 correlated positively with the other angiogenic factors and MVD. Moreover, Ang-2 values above the median were accompanied by worse survival.

Conclusion

Ang-2 correlates strongly with the angiogenic process and its serum levels are importantly prognostic for survival, highlighting the role of angiopoietins pathway in the biology of MM.     

Angiopoietin-2 is associated with decreased endothelial nitric oxide and poor clinical outcome in severe falciparum malaria

Adherence of parasitized erythrocytes to activated endothelium causes microvascular obstruction, tissue ischemia, and clinical complications in severe malaria (SM); however, the mechanisms leading to endothelial activation remain unclear. The angiogenic factors, angiopoietin-2 (Ang-2) and vascular endothelial growth factor (VEGF) are modulators of endothelial activation, with Ang-2 release from Weibel–Palade bodies (WPBs) being regulated by endothelial nitric oxide (NO). We explored the relationships between endothelial NO bioavailability, Ang-2, VEGF, tissue perfusion, and clinical outcomes in SM. We measured plasma Ang-2 and VEGF, together with biomarkers of severity from 146 adults with and without SM, in parallel with longitudinal measures of endothelial function by using reactive hyperemia peripheral arterial tonometry (a measure of endothelial NO bioavailability). Regression was used to relate concentrations of Ang-2/VEGF with malaria disease severity, biomarkers of perfusion, endothelial activation, and parasite biomass. The longitudinal relationship between Ang-2 and endothelial function was assessed by using a mixed-effects model. Ang-2 concentrations were elevated in SM and associated with increased venous lactate, plasma intercellular cell adhesion molecule-1 concentrations, parasite biomass, and mortality. In contrast, VEGF concentrations were inversely associated with these biomarkers. Ang-2 concentrations were significantly better predictors of death than venous lactate (P = 0.03). Recovery of endothelial function was associated with falling concentrations of Ang-2. Ang-2 release from endothelial cells with reduced NO bioavailability is likely to contribute to endothelial activation, sequestered parasite biomass, impaired perfusion, and poor outcome in severe falciparum malaria. Agents that improve endothelial NO, reduce WPB exocytosis, and/or antagonize Ang-2 may have therapeutic roles in SM.