Selective Stimulation of Cardiac Lymphangiogenesis Reduces Myocardial Edema and Fibrosis Leading to Improved Cardiac Function Following Myocardial Infarction.

BACKGROUND: The lymphatic system regulates interstitial tissue fluid balance, and lymphatic malfunction causes edema. The heart has an extensive lymphatic network displaying a dynamic range of lymph flow in physiology. Myocardial edema occurs in many cardiovascular diseases, eg, myocardial infarction (MI) and chronic heart failure, suggesting that cardiac lymphatic transport may be insufficient in pathology. Here, we investigate in rats the impact of MI and subsequent chronic heart failure on the cardiac lymphatic network. Further, we evaluate for the first time the functional effects of selective therapeutic stimulation of cardiac lymphangiogenesis post-MI. METHODS AND RESULTS: We investigated cardiac lymphatic structure and function in rats with MI induced by either temporary occlusion (n=160) or permanent ligation (n=100) of the left coronary artery. Although MI induced robust, intramyocardial capillary lymphangiogenesis, adverse remodeling of epicardial precollector and collector lymphatics occurred, leading to reduced cardiac lymphatic transport capacity. Consequently, myocardial edema persisted for several months post-MI, extending from the infarct to noninfarcted myocardium. Intramyocardial-targeted delivery of the vascular endothelial growth factor receptor 3-selective designer protein VEGF-CC152S, using albumin-alginate microparticles, accelerated cardiac lymphangiogenesis in a dose-dependent manner and limited precollector remodeling post-MI. As a result, myocardial fluid balance was improved, and cardiac inflammation, fibrosis, and dysfunction were attenuated. CONCLUSIONS: We show that, despite the endogenous cardiac lymphangiogenic response post-MI, the remodeling and dysfunction of collecting ducts contribute to the development of chronic myocardial edema and inflammation-aggravating cardiac fibrosis and dysfunction. Moreover, our data reveal that therapeutic lymphangiogenesis may be a promising new approach for the treatment of cardiovascular diseases.

Endothelial cell Bcl-2 and lymph node metastasis in patients with oral squamous cell carcinoma.

BACKGROUND: Loco-regional spread of disease causes high morbidity and is associated with the poor prognosis of malignant oral tumors. Better understanding of mechanisms underlying the establishment of lymph node metastasis is necessary for the development of more effective therapies for patients with oral cancer. The aims of this work were to evaluate a possible correlation between endothelial cell Bcl-2 and lymph node metastasis in patients with oral squamous cell carcinoma (OSCC), and to study signaling pathways that regulate Bcl-2 expression in lymphatic endothelial cells. METHODS: Endothelial cells were selectively retrieved from paraffin-embedded tissue sections of primary human OSCC from patients with or without lymph node metastasis by laser capture microdissection. RT-PCR was used to evaluate Bcl-2 expression in tumor-associated endothelial cells and in tumor cells. In vitro, mechanistic studies were performed to examine the effect of vascular endothelial growth factor (VEGF)-C on the expression of Bcl-2 in primary human lymphatic endothelial cells. RESULTS: We observed that Bcl-2 expression is upregulated in the endothelial cells of human oral tumors with lymph node metastasis as compared to endothelial cells from stage-matched tumors without metastasis. VEGF-C induced Bcl-2 expression in lymphatic endothelial cells via VEGFR-3 and PI3k/Akt signaling. Notably, OSCC cells express VEGF-C and induce Bcl-2 in lymphatic endothelial cells. CONCLUSIONS: Collectively, this work unveiled a mechanism for the induction of Bcl-2 in lymphatic endothelial cells and suggested that endothelial cell Bcl-2 contributes to lymph node metastasis in patients with oral squamous cell carcinoma.

Sunitinib inhibits lymphatic endothelial cell functions and lymph node metastasis in a breast cancer model through inhibition of vascular endothelial growth factor receptor 3.

INTRODUCTION: Metastasis is a common event and the main cause of death in cancer patients. Lymphangiogenesis refers to the formation of new lymphatic vessels and is thought to be involved in the development of metastasis. Sunitinib is a multi-kinase inhibitor that blocks receptor tyrosine kinase activity, including that of vascular endothelial growth factor receptors (VEGFRs). Although sunitinib is a clinically available angiogenesis inhibitor, its effects on lymphangiogenesis and lymph node metastasis remain unclear. The purpose of this study was to investigate the effects of sunitinib on vascular endothelial growth factor receptor 3 (VEGFR-3) and a related event, lymphangiogenesis. METHODS: The effects of sunitinib on the degree of phosphorylation of VEGFR-2/3 and other signaling molecules was examined in lymphatic endothelial cells (LECs) treated with the drug; VEGF-induced LEC growth, migration, and tube formation were also examined. For the in vivo study, luciferase-expressing breast cancer cells were transplanted into mammary fat pads of mice; the microvessel and lymphatic vessel density was then measured after treatment with sunitinib and anti-VEGFR-2 antibody. RESULTS: First, in human LECs, sunitinib blocked both VEGFR-2 and VEGFR-3 phosphorylation induced by VEGF-C or VEGF-D, and abrogated the activation of the downstream molecules extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt. Furthermore, sunitinib attenuated the cell-proliferation activity induced by VEGF-C/D and prevented VEGF-C-induced migration and tube formation of the LECs; however, anti-VEGFR2 treatment shows only a partial effect on the growth and functions of the LECs. We used a breast cancer cell line expressing luciferase as a metastatic cancer model. Sunitinib treatment (40 mg/kg/day) inhibited the growth of the primary tumor transplanted in the mammary fat pad of the mice and significantly reduced the number of blood and lymphatic vessels in the tumor. Furthermore, the development of axillary lymph node metastasis, detected by bioluminescent imaging, was markedly suppressed. This effect of sunitinib was more potent than that of DC101, an anti-mouse VEGFR-2 antibody. CONCLUSIONS: The results suggest that sunitinib might be beneficial for the treatment of breast cancer by suppressing lymphangiogenesis and lymph node metastasis, through inhibition, particularly important, of VEGFR-3.

Qingjie Fuzheng Granule suppresses lymphangiogenesis in colorectal cancer via the VEGF-C/VEGFR-3 dependent PI3K/AKT pathway.

SCOPE: To investigate the effect of Qingjie Fuzheng Granule (QFG) on lymphangiogenesis and lymphatic metastasis in colorectal cancer. METHODS: The effects of QFG on the expression and secretion of vascular endothelial growth factor-C (VEGF-C) in HCT-116 cells were investigated both in vitro and in vivo. HCT-116 cells were treated with different concentrations (0.2, 0.5, and 1.0 mg/mL) of QFG. The VEGF-C expression level was determined using RT-qPCR and western blotting, and the VEGF-C concentration in supernatant was measured by ELISA. Tumor xenograft models of HCT-116 cells were generated using BALB/c nude mice, and the mice were randomly divided into a control group (gavaged with normal saline) and QFG group (gavaged with 2 g/kg QFG). The effect of QFG on tumor growth was evaluated by comparing the volume and weight of tumors between two groups. Immunohistochemistry (IHC) and RT-qPCR were performed to detect the expression levels of VEGF-C, vascular endothelial growth factor receptor 3 (VEGFR-3), and LYVE-1 (lymphatic vessel endothelial hyaluronan receptor 1). ELISA was performed to measure the concentration of serum VEGF-C. TMT proteomics technology and Reactome pathway analysis were used to explore the mechanism of QFG inhibiting lymphangiogenesis in tumor. The VEGF-C (5 ng/mL)-stimulated human lymphatic endothelial cell (HLEC) model was conducted to evaluate the effect of QFG on lymphangiogenesis in vitro. The model cells were treated with different concentrations (0.2, 0.5, and 1.0 mg/mL) of QFG. Cell viability was then determined using an MTT assay. The cell migration, invasion, and tube-formation ability were analyzed using transwell migration, matrigel invasion and tube formation assays, respectively. The underlying mechanism was uncovered, the levels of VEGFR-3, matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9), p-PI3K/PI3K, p-AKT/AKT and p-mTOR/ mTOR were detected using western blotting. RESULTS: QFG significantly reduced VEGF-C expression and secretion in HCT-116 cells. QFG evidently suppressed in vivo tumor growth and the expression of VEGF-C, VEGFR-3, and LYVE-1. The serum VEGF-C level was also reduced by QFG. Moreover, TMT proteomics technology and Reactome pathway analysis identified 95 differentially expressed protein and multiple enriched pathway about matrix metalloproteinase and extracellular matrix, which is direct associate with lymphangiogenesis. In vitro experiment, QFG inhibited the viability, migration, invasion and tube formation of HLECs. Additionally, QFG reduced the VEGFR-3, MMP-2, MMP-9 expression levels, and the p-PI3K/PI3K, p-AKT/AKT, p-mTOR/ mTOR ratios. CONCLUSION: QFG can exert its effect on both tumor cells and HLECs, exhibiting ani- lymphangiogenesis in colorectal cancer via the VEGF-C/VEGFR-3 dependent PI3K/AKT pathway pathway.

HA-ving lymphatics improves lung transplantation.

Lung allografts are prone to rejection, even though recipients undergo aggressive immunosuppressive therapy. Lymphatic vessels serve as conduits for immune cell trafficking and have been implicated in the mediation of allograft rejection. In this issue of the JCI, Cui et al. provide compelling evidence that lymphatic vessel formation improves lung allograft survival in a murine transplant model. Moreover, their data suggest a potential mechanism for the beneficial effects of lymphatics that does not involve immune cell or antigen transport. Together, the results of this study provide new insight into the role of lymphatic vessels in transplant tolerance.

Therapeutic lymphangiogenesis ameliorates established acute lung allograft rejection.

Lung transplantation is the only viable option for patients suffering from otherwise incurable end-stage pulmonary diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. Despite aggressive immunosuppression, acute rejection of the lung allograft occurs in over half of transplant recipients, and the factors that promote lung acceptance are poorly understood. The contribution of lymphatic vessels to transplant pathophysiology remains controversial, and data that directly address the exact roles of lymphatic vessels in lung allograft function and survival are limited. Here, we have shown that there is a marked decline in the density of lymphatic vessels, accompanied by accumulation of low-MW hyaluronan (HA) in mouse orthotopic allografts undergoing rejection. We found that stimulation of lymphangiogenesis with VEGF-C156S, a mutant form of VEGF-C with selective VEGFR-3 binding, alleviates an established rejection response and improves clearance of HA from the lung allograft. Longitudinal analysis of transbronchial biopsies from human lung transplant recipients demonstrated an association between resolution of acute lung rejection and decreased HA in the graft tissue. Taken together, these results indicate that lymphatic vessel formation after lung transplantation mediates HA drainage and suggest that treatments to stimulate lymphangiogenesis have promise for improving graft outcomes.

Effects of vascular endothelial growth factor-C and -D on osteoclast differentiation and function in human peripheral blood mononuclear cells.

OBJECTIVE: The purpose of this study was to clarify the interaction of vascular endothelial growth factors (VEGFs)-C and -D with cell surface foetal liver kinase-1 (Flk-1) and fms-like tyrosine kinase-4 (Flt-4) receptors in the induction and activity of osteoclasts in cultured human peripheral blood mononuclear cells (PBMCs). DESIGN: PBMCs were cultured on chamber slides or on ivory discs for 2 or 3 weeks in the presence of macrophage-colony stimulating factor (M-CSF), VEGF-A, -C or -D, or placental growth factor (PlGF) with or without receptor activator of nuclear factor kappa-B ligand (RANKL). The number of osteoclasts in each group was counted and the area of ivory resorption was measured. In addition, osteoclast differentiation was further analysed under the same conditions, but with the addition of specific neutralizing antibodies against Flk-1 and Flt-4. RESULTS: RANKL was essential for the induction of osteoclasts in PBMCs. However, significant differences were found in the number of osteoclasts induced by VEGF-A, -C, -D or M-CSF with RANKL compared with control groups lacking or containing RANKL. Blocking of either Flk-1 or Flt-4 resulted in a reduction in the enhancement of osteoclast differentiation in PBMCs by VEGF-C or -D with RANKL. The osteoclasts induced by VEGF-A, -C, -D or M-CSF with RANKL formed significantly larger resorption lacunae than those formed by osteoclasts induced by RANKL alone. CONCLUSIONS: This study showed that VEGF-C and -D play a role in the induction of osteoclast differentiation through both Flk-1 and Flt-4 receptors and influence the area of the ivory resorption in PBMCs.

Targeting vascular endothelial growth factor receptor-1 and -3 with cediranib (AZD2171): effects on migration and invasion of gastrointestinal cancer cell lines.

The effect of vascular endothelial growth factor (VEGF) ligands and cediranib on tumor cell proliferation, migration, and invasion was determined. It has recently been suggested that autocrine signaling through the VEGF receptor (VEGFR) pathway may play a role in tumor cell survival, invasion, and migration. The purpose of the present study was to determine the expression of VEGFRs and VEGFR ligands in a panel of gastrointestinal carcinoma cells. Additionally, we evaluated the effects of VEGF autocrine signaling on tumor cell proliferation, migration, and invasion utilizing cediranib (AZD2171), a pan-VEGFR inhibitor. Five colorectal, three pancreatic, and two hepatocellular carcinoma cell lines were screened for VEGFR and VEGF expression by several methods. Expression of VEGFR-1 and VEGFR-3 was cell line-dependent, whereas VEGFR-2 was not detected. Secretion of VEGF-A was detected in the supernatants of all cell lines whereas VEGF-C secretion was detected in the Panc-1, MiaPaca2, and Hep1 cells only. Tumor cells showed increased migratory activity, but not proliferation, when stimulated with VEGFs. The pan-VEGFR inhibitor cediranib (100 nmol/L) inhibited tumor cell migration and invasion, with no effects on proliferation. Cediranib decreased VEGFR-1 and VEGFR-3 phosphorylation as well as activation of downstream effectors. VEGFR-1 and VEGFR-3 expression was detected in all the gastrointestinal carcinoma cells evaluated. Although activation of the VEGF pathway did not affect cell proliferation, our data indicate that this pathway seems to play a role in tumor cell migration and invasion in these cell lines. Therefore, inhibition of VEGFR by cediranib may represent a clinically relevant treatment option for gastrointestinal tumors.

Vascular endothelial growth factor receptor-3 activity is modulated by its association with caveolin-1 on endothelial membrane.

Vascular endothelial growth factor receptor-3 (VEGFR-3) is constitutively expressed in lymphatic vessels and transiently in endothelial cells of blood vessels during angiogenesis. Here we report that VEGFR-3 localizes in the caveolae membrane of endothelial cells and co-immunoprecipitates with caveolin-1. Caveolin-1 silencing or its depletion from the cell membrane by cholesterol increases VEGFR-3 autophosphorylation, suggesting that caveolin acts as a negative regulator of VEGFR-3 activity. Receptor activation induces caveolin-1 phosphorylation on tyrosine residues including tyrosine 14. Cell treatment with Src or Abl inhibitors PP2 or STI571, prior to receptor stimulation, affects caveolin-1 phosphorylation without affecting receptor autophosphorylation, suggesting that both Src and Abl are involved in VEGFR-3-dependent caveolin-1 phosphorylation. Caveolin-1 phosphorylation in Src/Fyn/Yes knockout cells demonstrated that Abl phosphorylates caveolin-1 independently from Src family members. These results suggest a functional interaction between VEGFR-3 and caveolin-1 to modulate endothelial cell activation during angiogenesis.