Tumour necrosis factor superfamily member 15 (Tnfsf15) facilitates lymphangiogenesis via up-regulation of Vegfr3 gene expression in lymphatic endothelial cells

Regulation of VEGFR3 signaling in lymphatic endothelial cells

The receptor tyrosine kinase vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3) is the principal transmembrane receptor responsible for sensing and coordinating cellular responses to environmental lymphangiogenic stimuli in lymphatic endothelial cells (LECs). VEGFC and D (VEGFC/D) function as the cognate ligands to VEGFR3 by stimulating autophosphorylation of intracellular VEGFR3 tyrosine kinase domains that activate signal cascades involved in lymphatic growth and survival. VEGFR3 primarily promotes downstream signaling through the phosphoinositide 3-kinase (PI3K) and Ras signaling cascades that promote functions including cell proliferation and migration. The importance of VEGFR3 cascades in lymphatic physiology is underscored by identification of dysfunctional VEGFR3 signaling across several lymphatic-related diseases. Recently, our group has shown that intracellular modification of VEGFR3 signaling is a potent means of inducing lymphangiogenesis independent of VEGFC. This is important because long-term treatment with recombinant VEGFC may have deleterious consequences due to off-target effects. A more complete understanding of VEGFR3 signaling pathways may lead to novel drug development strategies. The purpose of this review is to 1) characterize molecular mediators of VEGFC/VEGFR3 downstream signaling activation and their functional roles in LEC physiology and 2) explore molecular regulation of overall VEGFR3 expression and activity within LECs.

Injectable Thermosensitive Gel CH-BPNs-NBP for Effective Periodontitis Treatment through ROS-Scavenging and Jaw Vascular Unit Protection

Periodontitis, a prevalent inflammatory condition in the oral cavity, is closely associated with oxidative stress-induced tissue damage mediated by excessive reactive oxygen species (ROS) production. The jaw vascular unit (JVU), encompassing both vascular and lymphatic vessels, plays a crucial role in maintaining tissue fluid homeostasis and contributes to the pathological process in inflammatory diseases of the jaw. This study presents a novel approach for treating periodontitis through the development of an injectable thermosensitive gel (CH-BPNs-NBP). The gel formulation incorporates black phosphorus nanosheets (BPNs), which are notable for their ROS-scavenging properties, and dl-3-n-butylphthalide (NBP), a vasodilator that promotes lymphatic vessel function within the JVU. These results demonstrate that the designed thermosensitive gel serve as a controlled release system, delivering BPNs and NBP to the site of inflammation. CH-BPNs-NBP not only protects macrophages and human lymphatic endothelial cells from ROS attack but also promotes M2 polarization and lymphatic function. In in vivo studies, this work observes a significant reduction in inflammation and tissue damage, accompanied by a notable promotion of alveolar bone regeneration. This research introduces a promising therapeutic strategy for periodontitis, leveraging the unique properties of BPNs and NBP within an injectable thermosensitive gel.

O-GlcNAc modification in endothelial cells modulates adiposity via fat absorption from the intestine in mice

Introduction

Endothelial cells have a crucial function in transporting and exchanging various nutrients. O-GlcNAcylation, mediated by O-GlcNAc transferase (OGT), involves the addition of N-acetylglucosamine to proteins and serves as an intracellular nutrient sensing mechanism. However, the role of O-GlcNAcylation in endothelial cells remains poorly understood.

Objective

This study investigated the role of O-GlcNAcylation in endothelial cells.

Methods

Endothelial-cell-specific Ogt -knockout mice (Ogt-ECKO) were generated by crossing Ogt-floxed mice (Ogt-flox) with VE-Cadherin Cre ERT2 mice. Ogt-ECKO mice and Ogt-flox control mice were subjected to a normal or high-fat diet, and their body weight, glucose metabolism, and lipid metabolism were examined.

Results

Ogt-ECKO mice exhibited reduced body weight compared with Ogt-flox control mice under a high-fat diet. Lipid absorption was significantly impaired in Ogt-ECKO mice. Changes in the intercellular junctions of small intestinal lacteal endothelial cells from a button-like to a zipper-like configuration were observed. Furthermore, Ogt-ECKO mice showed decreased expression of VEGFR3. The administration of a nitric oxide donor restored lipid absorption and reversed the morphological alterations in Ogt-ECKO mice.

Conclusions

These findings demonstrate the critical role of O-GlcNAcylation in endothelial cells in lipid absorption in the intestine through the modulation of lacteal junction morphology. These results provide novel insight into the metabolic regulatory mechanisms under physiological conditions and have implications for the development of new therapeutic strategies for obesity.

miR-455-3p regulates lymphangiogenesis in silicosis by regulating VEGF-C/VEGFR3

Silicosis is a disease characterized by lung inflammation and fibrosis caused by long-term inhalation of free silicon dioxide (SiO2). Recent studies have found that a large number of lymphatic hyperplasia occurs during the occurrence and development of silicosis. miRNAs play an important role in lymphangiogenesis. However, the regulation and mechanism of miRNAs on lymphangiogenesis in silicosis remain unclear. In this study, lymphangiogenesis was observed in silicosis rats, and VEGF-C-targeted miRNAs were screened, and the effect of miRNAs on the formation of human lymphatic endothelial cells (HLECs) tubular structure was investigated in vitro. The results showed that SiO2 promoted the expressions of Collagen Ι and α-SMA, TNF-α, IL-6 and VEGF-C increased first and then decreased, and promoted the formation of lymphatic vessels. Bioinformatics methods screened miR-455-3p for targeted binding to VEGF-C, and dual luciferase reporter genes confirmed VEGF-C as the target gene of miR-455-3p, and miR-455-3p was down-regulated in the lung tissue of silicosis rats. Transfection of miR-455-3p Inhibitors down-regulated the expression level of miR-455-3p and up-regulated the expression levels of VEGF-C and VEGFR-3 in HLECs, enhanced migration ability and increased tube formation. Transfection of miR-455-3p Mimics showed an opposite trend. These results suggest that miR-455-3p further regulates the tubular structure formation of HLECs by regulating VEGF-C/VEGFR3. Therefore, targeting miR-455-3p may provide a new therapeutic strategy for SiO2-induced silicosis injury.

Aging-related biomarker discovery in the era of immune checkpoint inhibitors for cancer patients

Older patients with cancer, particularly those over 75 years of age, often experience poorer clinical outcomes compared to younger patients. This can be attributed to age-related comorbidities, weakened immune function, and reduced tolerance to treatment-related adverse effects. In the immune checkpoint inhibitors (ICI) era, age has emerged as an influential factor impacting the discovery of predictive biomarkers for ICI treatment. These age-linked changes in the immune system can influence the composition and functionality of tumor-infiltrating immune cells (TIICs) that play a crucial role in the cancer response. Older patients may have lower levels of TIICs infiltration due to age-related immune senescence particularly T cell function, which can limit the effectivity of cancer immunotherapies. Furthermore, age-related immune dysregulation increases the exhaustion of immune cells, characterized by the dysregulation of ICI-related biomarkers and a dampened response to ICI. Our review aims to provide a comprehensive understanding of the mechanisms that contribute to the impact of age on ICI-related biomarkers and ICI response. Understanding these mechanisms will facilitate the development of treatment approaches tailored to elderly individuals with cancer.

Targeting Kindlin-2 in adipocytes increases bone mass through inhibiting FAS/PPARγ/FABP4 signaling in mice

Osteoporosis (OP) is a systemic skeletal disease that primarily affects the elderly population, which greatly increases the risk of fractures. Here we report that Kindlin-2 expression in adipose tissue increases during aging and high-fat diet fed and is accompanied by decreased bone mass. Kindlin-2 specific deletion (K2KO) controlled by Adipoq-Cre mice or adipose tissue-targeting AAV (AAV-Rec2-CasRx-sgK2) significantly increases bone mass. Mechanistically, Kindlin-2 promotes peroxisome proliferator-activated receptor gamma (PPARγ) activation and downstream fatty acid binding protein 4 (FABP4) expression through stabilizing fatty acid synthase (FAS), and increased FABP4 inhibits insulin expression and decreases bone mass. Kindlin-2 inhibition results in accelerated FAS degradation, decreased PPARγ activation and FABP4 expression, and therefore increased insulin expression and bone mass. Interestingly, we find that FABP4 is increased while insulin is decreased in serum of OP patients. Increased FABP4 expression through PPARγ activation by rosiglitazone reverses the high bone mass phenotype of K2KO mice. Inhibition of FAS by C75 phenocopies the high bone mass phenotype of K2KO mice. Collectively, our study establishes a novel Kindlin-2/FAS/PPARγ/FABP4/insulin axis in adipose tissue modulating bone mass and strongly indicates that FAS and Kindlin-2 are new potential targets and C75 or AAV-Rec2-CasRx-sgK2 treatment are potential strategies for OP treatment.

TNFSF15 and MIA Variant Associated with Immunotherapy and Prognostic Evaluation in Esophageal Cancer

Background

Esophageal cancer (ESCA) is a common gastrointestinal tumor, and China is one of the regions with a high incidence. Tumor immune-related cells play important roles in the tumorigenesis and development of ESCA. However, the role of tumor immune-related genes in the development of ESCA has not been established.

Methods

In this study, weighted gene coexpression network analysis (WGCNA) was used to analyze ESCA gene expression using data from The Cancer Genome Atlas (TCGA) database. Gene expression was associated with clinical traits, and modules related to CD8+T cells, dendritic cells, and regulatory T cells (Tregs) were obtained.

Results

The GO analysis showed that inflammatory chemotaxis networks were activated by cell chemotaxis, chemokine activity, and chemokine binding receptor. Three hub genes (IL17C, TNFSF15, and MIA) related to tumor immunity and metastasis were identified by WGCNA, and the abnormal expression of each hub gene in ESCA has a poor prognosis, especially in patients with high expression (P < 0.05). The risk assessment analysis also showed that tumor stage was positively correlated with tumor risk in ESCA (P < 0.05). Therefore, more than 50 pairs of tumor tissues from the T1-T3 stages with different degrees of differentiation and paracancerous tissues were selected to confirm the expression of the three genes using RT-qPCR and immunofluorescence (IF). The infiltration of CD8+ T cells in tumor tissues was lower than that in normal tissues. According to the RT-qPCR, the expressions of IL17 C, TNFSF15, and MIA in moderately and poorly differentiated tissues were significantly higher than those in normal tissues (P < 0.05). In contrast, their expressions were decreased in high differentiated tissues (P < 0.05). Furthermore, IL17C, TNFSF15, and MIA were all positively correlated with immune checkpoint PD-1; TNFSF15 and MIA were also positively correlated with CTLA4, TIGIT, and CD96.

Conclusion

In summary, IL17C, TNFSF15, and MIA may act as biomarkers for prognosis in moderately and poorly differentiated ESCAs, and they may be used as predictive genes of immunotherapy associated with CD8+ T cell and Tregs invasion in ESCAs.

Robust Acquisition of Spatial Transcriptional Programs in Tissues With Immunofluorescence-Guided Laser Capture Microdissection

The functioning of tissues is fundamentally dependent upon not only the phenotypes of the constituent cells but also their spatial organization in the tissue, as local interactions precipitate intra-cellular events that often lead to changes in expression. However, our understanding of these processes in tissues, whether healthy or diseased, is limited at present owing to the difficulty in acquiring comprehensive transcriptional programs of spatially- and phenotypically-defined cells in situ. Here we present a robust method based on immunofluorescence-guided laser capture microdissection (immuno-LCM-RNAseq) to acquire finely resolved transcriptional programs with as few as tens of cells from snap-frozen or RNAlater-treated clinical tissues sufficient to resolve even isoforms. The protocol is optimized to protect the RNA with a small molecule inhibitor, the ribonucleoside vanadyl complex (RVC), which thereby enables the typical time-consuming immunostaining and laser capture steps of this procedure during which RNA is usually severely degraded in existing approaches. The efficacy of this approach is exemplified by the characterization of differentially expressed genes between the mouse small intestine lacteal cells at the tip versus the main capillary body, including those that function in sensing and responding to local environmental cues to stimulate intra-cellular signalling. With the extensive repertoire of specific antibodies that are presently available, our method provides an unprecedented capability for the analysis of transcriptional networks and signalling pathways during development, pathogenesis, and aging of specific cell types within native tissues.

A Protective Role of Tumor Necrosis Factor Superfamily-15 in Intracerebral Hemorrhage-Induced Secondary Brain Injury

Destabilization of blood vessels by the activities of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) following intracerebral hemorrhage (ICH) has been considered the main causes of aggravated secondary brain injury. Here, we show that tumor necrosis factor superfamily-15 (TNFSF15; also known as vascular endothelial growth inhibitor), an inhibitor of VEGF-induced vascular hyper-permeability, when overexpressed in transgenic mice, exhibits a neuroprotective function post-ICH. In this study, we set-up a collagenase-induced ICH model with TNFSF15-transgenic mice and their transgene-negative littermates. We observed less lesion volume and neural function perturbations, together with less severe secondary injuries in the acute phase that are associated with brain edema and inflammation, including vascular permeability, oxidative stress, microglia/macrophage activation and neutrophil infiltration, and neuron degeneration, in the TNFSF15 group compared with the littermate group. Additionally, we show that there is an inhibition of VEGF-induced elevation of MMP-9 in the perihematomal blood vessels of the TNFSF15 mice following ICH, concomitant with enhanced pericyte coverage of the perihematomal blood vessels. These findings are consistent with the view that TNFSF15 may have a potential as a therapeutic agent for the treatment of secondary injuries in the early phase of ICH.

Effect of VEGFC on lymph flow and inflammation-induced alveolar bone loss

The lymphatic system plays a crucial role in the maintenance of tissue fluid homeostasis and the immunological response to inflammation. The effects of lymphatic drainage dysfunction on periodontitis have not been well studied. Here we show that lymphatic vessel endothelial receptor 1 (LYVE1)+ /podoplanin (PDPN)+ lymphatic vessels (LVs) are increased in the periodontal tissues, with accumulation close to the alveolar bone surface, in two murine periodontitis models: rheumatoid arthritis (RA)-associated periodontitis and ligature-induced periodontitis. Further, PDPN+ /alpha-smooth muscle actin (αSMA)- lymphatic capillaries are increased, whereas PDPN+ /αSMA+ collecting LVs are decreased significantly in the inflamed periodontal tissues. Both mouse models of periodontitis have delayed lymph flow in periodontal tissues, increased TRAP-positive osteoclasts, and significant alveolar bone loss. Importantly, the local administration of adeno-associated virus for vascular endothelial growth factor C, the major growth factor that promotes lymphangiogenesis, increases the area and number of PDPN+ /αSMA+ collecting LVs, promotes local lymphatic drainage, and reduces alveolar bone loss in both models of periodontitis. Lastly, LYVE1+ /αSMA- lymphatic capillaries are increased, whereas LYVE1+ /αSMA+ collecting LVs are decreased significantly in gingival tissues of patients with chronic periodontitis compared with those of clinically healthy controls. Thus, our findings reveal an important role of local lymphatic drainage in periodontal inflammation-mediated alveolar bone loss. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Formation of new lymphatic vessels in glioma: An immunohistochemical analysis

We investigated the distribution and formation of new lymphatic vessels in gliomas. Specimens from seven glioma cases were analyzed by immunohistochemical staining for CD34, lymphatic endothelial hyaluronic acid receptor 1 (LYVE‐1), prospero‐related homeobox 1 (Prox1), nestin, and hypoxia‐inducible factor 1α (HIF‐1α). Three types of vessels were observed in glioma specimens: LYVE‐1⁺ lymphatic vessels, CD34⁺ blood vessels, and LYVE‐1⁺/CD34⁺ blood vessels. Prox1⁺/LYVE‐1⁺ cells were distributed in some lymphatic vessels as well as among vascular endothelial cells and glioma cells. Nestin⁺ cells were scattered throughout the gliomas, and some lymphatic cells also expressed nestin. HIF‐1α⁺ Prox1⁺ cells were widely distributed within the glioma specimens. The present immunohistochemical analysis revealed upregulation of Prox1 and HIF‐1α in some glioma tissues as well as the differentiation of nestin⁺ tumor stem cells into LYVE‐1⁺ lymphatic vessels.

Anlotinib suppresses lymphangiogenesis and lymphatic metastasis in lung adenocarcinoma through a process potentially involving VEGFR-3 signaling

Objective: Lymphatic metastasis is one of the leading causes of malignancy dispersion in various types of cancer. However, few anti-lymphangiogenic drugs have been approved for clinical use to date. Therefore, new therapies to block lymphangiogenesis are urgently required. Methods: Immunohistochemistry, immunofluorescence, Western blot, migration assays, and lymphangiogenesis and lymphatic metastasis assays were used. Results: Anlotinib, a receptor tyrosine kinase inhibitor, suppressed the rate of new metastatic lesions (31.82% in the placebo arm and 18.18% in the anlotinib arm) in patients with advanced lung adenocarcinoma who were enrolled in our ALTER-0303 study. D2-40⁺-lymphatic vessel density was strongly correlated with disease stage, metastasis, and poor prognosis in 144 Chinese patients with lung adenocarcinoma. In mice bearing A549^EGFP tumors, tumor lymphatic vessel density, tumor cell migration to lymph nodes, and the number of distant metastatic lesions were lower in the anlotinib group than in the controls. Anlotinib inhibited the growth and migration of human lymphatic endothelial cells (hLECs) and lymphangiogenesis in vitro and in vivo. Treatment of hLECs with anlotinib downregulated phosphorylated vascular endothelial growth factor receptor 3 (VEGFR-3). Conclusions: Anlotinib inhibits lymphangiogenesis and lymphatic metastasis, probably through inactivating VEGFR-3 phosphorylation. The results indicate that anlotinib may be beneficial for treatment in avoiding lymphangiogenesis and distant lymphatic metastasis in lung adenocarcinoma. (Trial registration: ALTER0303; NCT02388919; March 17, 2015.).

Shikonin Suppresses Lymphangiogenesis via NF-κB/HIF-1α Axis Inhibition

Lymphangiogenesis, the formation of lymphatic vessels from preexisting ones, promotes cancer growth and metastasis. Finding natural compounds with anti-lymphangiogenic activity will be useful for preventive treatment of lymphatic metastasis. Shikonin, an ingredient of a traditional Japanese and Chinese medicinal herb Lithospermum erythrorhizon, has been widely used in several pharmaceutical and cosmetic preparations, as well as in food colorants. Shikonin has been reported to inhibit lymphangiogenesis in vitro, but the mechanism of inhibition has not been determined. The aim of this study is to investigate the mechanism of anti-lymphangiogenesis of shikonin in primary human lymphatic endothelial cells (HMVEC-dLy). Shikonin, at non-toxic concentrations, significantly inhibited cord formation ability of lymphatic endothelial cells in a dose- and time-dependent manner. Western blotting analysis showed that shikonin decreased nuclear factor-kappaB (NF-κB) activation, as indicated by phosphorylation and nuclear translocation of NF-κB p65, and also reduced both mRNA and protein levels of hypoxia-inducible factor-1 (HIF-1)α. Use of an NF-κB inhibitor (BAY 11-7085) and HIF-1α small interfering RNA (siRNA) transfection revealed that NF-κB activation was upstream of HIF-1α expression, which controls cord formation by HMVEC-dLy. In addition, the reduction of vascular endothelial growth factor C (VEGF-C) and vascular endothelial growth factor receptor-3 (VEGFR-3) mRNA levels were also found in HMVEC-dLy that treated with shikonin. In conclusion, shikonin inhibits lymphangiogenesis in vitro by interfering the NF-κB/HIF-1α pathway and involves in suppression of VEGF-C and VEGFR-3 mRNA expression.

Comparative Transcriptomic Analysis Identifies a Range of Immunologically Related Functional Elaborations of Lymph Node Associated Lymphatic and Blood Endothelial Cells

Lymphatic and blood vessels are formed by specialized lymphatic endothelial cells (LEC) and blood endothelial cells (BEC), respectively. These endothelial populations not only form peripheral tissue vessels, but also critical supporting structures in secondary lymphoid organs, particularly the lymph node (LN). Lymph node LEC (LN-LEC) also have been shown to have important immunological functions that are not observed in LEC from tissue lymphatics. LN-LEC can maintain peripheral tolerance through direct presentation of self-antigen via MHC-I, leading to CD8 T cell deletion; and through transfer of self-antigen to dendritic cells for presentation via MHC-II, resulting in CD4 T cell anergy. LN-LEC also can capture and archive foreign antigens, transferring them to dendritic cells for maintenance of memory CD8 T cells. The molecular basis for these functional elaborations in LN-LEC remain largely unexplored, and it is also unclear whether blood endothelial cells in LN (LN-BEC) might express similar enhanced immunologic functionality. Here, we used RNA-Seq to compare the transcriptomic profiles of freshly isolated murine LEC and BEC from LN with one another and with freshly isolated LEC from the periphery (diaphragm). We show that LN-LEC, LN-BEC, and diaphragm LEC (D-LEC) are transcriptionally distinct from one another, demonstrating both lineage and tissue-specific functional specializations. Surprisingly, tissue microenvironment differences in gene expression profiles were more numerous than those determined by endothelial cell lineage specification. In this regard, both LN-localized endothelial cell populations show a variety of functional elaborations that suggest how they may function as antigen presenting cells, and also point to as yet unexplored roles in both positive and negative regulation of innate and adaptive immune responses. The present work has defined in depth gene expression differences that point to functional specializations of endothelial cell populations in different anatomical locations, but especially the LN. Beyond the analyses provided here, these data are a resource for future work to uncover mechanisms of endothelial cell functionality.

Counterbalance: modulation of VEGF/VEGFR activities by TNFSF15

Vascular hyperpermeability occurs in angiogenesis and several pathobiological conditions, producing elevated interstitial fluid pressure and lymphangiogenesis. How these closely related events are modulated is a fundamentally important question regarding the maintenance of vascular homeostasis and treatment of disease conditions such as cancer, stroke, and myocardial infarction. Signals mediated by vascular endothelial growth factor receptors, noticeably VEGFR-1, −2, and −3, are centrally involved in the promotion of both blood vessel and lymphatic vessel growth. These signaling pathways are counterbalanced or, in the case of VEGFR3, augmented by signals induced by tumor necrosis factor superfamily-15 (TNFSF15). TNFSF15 can simultaneously downregulate membrane-bound VEGFR1 and upregulate soluble VEGFR1, thus changing VEGF/VEGFR1 signals from pro-angiogenic to anti-angiogenic. In addition, TNFSF15 inhibits VEGF-induced VEGFR2 phosphorylation, thereby curbing VEGFR2-mediated enhancement of vascular permeability. Third, and perhaps more interestingly, TNFSF15 is capable of stimulating VEGFR3 gene expression in lymphatic endothelial cells, thus augmenting VEGF-C/D-VEGFR3-facilitated lymphangiogenesis. We discuss the intertwining relationship between the actions of TNFSF15 and VEGF in this review.

The ability of tumor necrosis factor superfamily-15 (TNFSF15) protein to balance the actions of vascular endothelial growth factors (VEGFs) highlights new therapeutic strategies for the treatment of diseases that disrupt the circulatory system. Gui-Li Yang at the Tianjin Neurological Institute and Lu-Yuan Li at Nankai University describe the mechanisms through which TNFSF15 inhibits blood vessel growth mediated by VEGF receptor-1 (VEGFR1) and counterbalances the increase in vascular permeability mediated by VEGFR2. Interestingly, TNFSF15 enhances the effects of VEGFR3 on the formation of lymphatic vessels by promoting VEGFR3 gene expression in lymphatic endothelial cells. Further research will determine whether TNFSF15′s unique capacity to regulate the properties of both blood and lymph vessels can be harnessed to improve the treatment of conditions such as cancer, stroke, myocardial infarction and lymphoedema.

Tumor necrosis factor superfamily 15 promotes lymphatic metastasis via upregulation of vascular endothelial growth factor-C in a mouse model of lung cancer

Lymphatic metastasis is facilitated by lymphangiogenic growth factor vascular endothelial growth factor-C (VEGFC) that is secreted by some primary tumors. We previously identified tumor necrosis factor superfamily 15 (TNFSF15), a blood vascular endothelium-derived cytokine, in lymphatic endothelial cells, as a key molecular modulator during lymphangiogenesis. However, the effect of TNFSF15 on tumor lymphatic metastasis and the underlying molecular mechanisms remain unclear. We report here that TNFSF15, which is known to inhibit primary tumor growth by suppressing angiogenesis, can promote lymphatic metastasis through facilitating lymphangiogenesis in tumors. Mice bearing tumors induced by A549 cells stably overexpressing TNFSF15 exhibited a significant increase in densities of lymphatic vessels and a marked enhancement of A549 tumor cells in newly formed lymphatic vessels in the primary tumors as well as in lymph nodes. Treatment of A549 cells with TNFSF15 results in upregulation of VEGFC expression, which can be inhibited by siRNA gene silencing of death domain-containing receptor-3 (DR3), a cell surface receptor for TNFSF15. In addition, TNFSF15/DR3 signaling pathways in A549 cells include activation of NF-κB during tumor lymphangiogenesis. Our data indicate that TNFSF15, a cytokine mainly produced by blood endothelial cells, facilitates tumor lymphangiogenesis by upregulating VEGFC expression in A549 cells, contributing to lymphatic metastasis in tumor-bearing mice. This finding also suggests that TNFSF15 may have potential as an indicator for prognosis evaluation.

TNFSF15 suppresses VEGF production in endothelial cells by stimulating miR-29b expression via activation of JNK-GATA3 signals

Vascular endothelial cell growth factor (VEGF) plays a pivotal role in promoting neovascularization. VEGF gene expression in vascular endothelial cells in normal tissues is maintained at low levels but becomes highly up-regulated in a variety of disease settings including cancers. Tumor necrosis factor superfamily 15 (TNFSF15; VEGI; TL1A) is an anti-angiogenic cytokine prominently produced by endothelial cells in a normal vasculature. We report here that VEGF production in mouse endothelial cell line bEnd.3 can be inhibited by TNFSF15 via microRNA-29b (miR-29b) that targets the 3'-UTR of VEGF transcript. Blocking TNFSF15 activity by using either siRNA against the TNFSF15 receptor known as death domain-containing receptor-3 (DR3; TNFRSF25), or a neutralizing antibody 4-3H against TNFSF15, led to inhibition of miR-29b expression and reinvigoration of VEGF production. In addition, we found that TNFSF15 activated the JNK signaling pathway as well as the transcription factor GATA3, resulting in enhanced miR-29b production. Treatment of the cells either with SP600125, an inhibitor of JNK, or with JNK siRNA, led to eradication of TNFSF15-induced GATA3 expression. Moreover, GATA3 siRNA suppressed TNFSF15-induced miR-29b expression. These findings suggest that VEGF gene expression can be suppressed by TNFSF15-stimulated activation of the JNK-GATA3 signaling pathway which gives rise to up-regulation of miR-29b.

TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation

Vascular hyperpermeability is critical in ischemic diseases, including stroke and myocardial infarction, as well as in inflammation and cancer. It is well known that the VEGF-VEGFR2 signaling pathways are pivotal in promoting vascular permeability; however, counterbalancing mechanisms that restrict vascular permeability to maintain the integrity of blood vessels are not yet fully understood. We report that TNF superfamily member 15 (TNFSF15), a cytokine largely produced by vascular endothelial cells and a specific inhibitor of the proliferation of these same cells, can inhibit VEGF-induced vascular permeability in vitro and in vivo, and that death receptor 3 (DR3), a cell surface receptor of TNFSF15, mediates TNFSF15-induced dephosphorylation of VEGFR2. Src homology region 2 domain-containing phosphatase-1 (SHP-1) becomes associated with DR3 upon TNFSF15 interaction with the latter. In addition, a protein complex consisting of VEGFR2, DR3, and SHP-1 is formed in response to the effects of TNFSF15 and VEGF on endothelial cells. It is plausible that this protein complex provides a structural basis for the molecular mechanism in which TNFSF15 induces the inhibition of VEGF-stimulated vascular hyperpermeability.-Yang, G.-L., Zhao, Z., Qin, T.-T., Wang, D., Chen, L., Xiang, R., Xi, Z., Jiang, R., Zhang, Z.-S., Zhang, J., Li. L.-Y. TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation.