TL1A inhibition for inflammatory bowel disease treatment: From inflammation to fibrosis.

The pivotal role of TL1A in modulating immune pathways crucial for inflammatory bowel disease (IBD) and intestinal fibrosis offers a promising therapeutic target. Phase 2 trials (TUSCANY and ARTEMIS-UC) evaluating an anti-TL1A antibody show progress in expanding IBD therapeutic options. First-in-human data reveal reduced expression of genes associated with extracellular matrix remodeling and fibrosis post-anti-TL1A treatment. Investigational drug TEV-48574, potentially exerting dual antifibrotic and anti-inflammatory effects, is undergoing a phase 2 basket study in both ulcerative colitis (UC) and Crohn disease (CD). Results are eagerly awaited, marking advancements in IBD therapeutics. This critical review comprehensively examines the existing literature, illuminating TL1A and the intricate role of DR3 in IBD, emphasizing the evolving therapeutic landscape and ongoing clinical trials, with potential implications for more effective IBD management.

TNFSF15 inhibits progression of diabetic retinopathy by blocking pyroptosis via interacting with GSDME.

Diabetic retinopathy is a common microvascular complication of diabetes and a leading cause of blindness. Pyroptosis has emerged as a mechanism of cell death involved in diabetic retinopathy pathology. This study explored the role of GSDME-mediated pyroptosis and its regulation by TNFSF15 in diabetic retinopathy. We found GSDME was upregulated in the progression of diabetic retinopathy. High glucose promoted GSDME-induced pyroptosis in retinal endothelial cells and retinal pigment epithelial cells, attributed to the activation of caspase-3 which cleaves GSDME to generate the pyroptosis-executing N-terminal fragment. TNFSF15 was identified as a binding partner and inhibitor of GSDME-mediated pyroptosis. TNFSF15 expression was increased by high glucose but suppressed by the caspase-3 activator Raptinal. Moreover, TNFSF15 protein inhibited high glucose- and Raptinal-induced pyroptosis by interacting with GSDME in retinal cells. Collectively, our results demonstrate TNFSF15 inhibits diabetic retinopathy progression by blocking GSDME-dependent pyroptosis of retinal cells, suggesting the TNFSF15-GSDME interaction as a promising therapeutic target for diabetic retinopathy.

TNFSF15 facilitates the differentiation of CD11b+ myeloid cells into vascular pericytes in tumors.

OBJECTIVE: Immature vasculature lacking pericyte coverage substantially contributes to tumor growth, drug resistance, and cancer cell dissemination. We previously demonstrated that tumor necrosis factor superfamily 15 (TNFSF15) is a cytokine with important roles in modulating hematopoiesis and vascular homeostasis. The main purpose of this study was to explore whether TNFSF15 might promote freshly isolated myeloid cells to differentiate into CD11b+ cells and further into pericytes. METHODS: A model of Lewis lung cancer was established in mice with red fluorescent bone marrow. After TNFSF15 treatment, CD11b+ myeloid cells and vascular pericytes in the tumors, and the co-localization of pericytes and vascular endothelial cells, were assessed. Additionally, CD11b+ cells were isolated from wild-type mice and treated with TNFSF15 to determine the effects on the differentiation of these cells. RESULTS: We observed elevated percentages of bone marrow-derived CD11b+ myeloid cells and vascular pericytes in TNFSF15-treated tumors, and the latter cells co-localized with vascular endothelial cells. TNFSF15 protected against CD11b+ cell apoptosis and facilitated the differentiation of these cells into pericytes by down-regulating Wnt3a-VEGFR1 and up-regulating CD49e-FN signaling pathways. CONCLUSIONS: TNFSF15 facilitates the production of CD11b+ cells in the bone marrow and promotes the differentiation of these cells into pericytes, which may stabilize the tumor neovasculature.

Tumor necrosis factor-like cytokine 1A plays a role in inflammatory bowel disease pathogenesis.

The binding of tumor necrosis factor-like cytokine 1A (TL1A) to death receptor 3 (DR3) plays an important role in the interaction between dendritic cells (DCs) and T cells and contributes to intestinal inflammation development. However, the mechanism by which DCs expressing TL1A mediate helper T (Th) cell differentiation in the intestinal lamina propria (LP) during the pathogenesis of inflammatory bowel disease remains unclear. In this study, we found that TL1A/DR3 promoted Th1 and Th17 cell differentiation in T-T and DC-T cell interaction-dependent manners. TL1A-deficient CD4+ T cells failed to polarize into Th1/Th17 cells and did not cause colonic inflammation in a T cell transfer colitis model. Notably, TL1A was located in the cytoplasm and nuclei of DCs, positively regulated the DC-specific ICAM-grabbing nonintegrin/RAF1/nuclear factor κB signaling pathway, enhanced the antigen uptake ability of DCs, and promoted TLR4-mediated DC activation, inducing naive CD4+ T cell differentiation into Th1 and Th17 cells. Our work reveals that TL1A plays a regulatory role in inflammatory bowel disease pathogenesis.

Bradykinin-pretreated Human cardiac-specific c-kit+ Cells Enhance Exosomal miR-3059-5p and Promote Angiogenesis Against Hindlimb Ischemia in mice.

BACKGROUND: Protection of cardiac function following myocardial infarction was largely enhanced by bradykinin-pretreated cardiac-specific c-kit+ (BK-c-kit+) cells, even without significant engraftment, indicating that paracrine actions of BK-c-kit+ cells play a pivotal role in angiogenesis. Nevertheless, the active components of the paracrine actions of BK-c-kit+ cells and the underlying mechanisms remain unknown. This study aimed to define the active components of exosomes from BK-c-kit+ cells and elucidate their underlying protective mechanisms. METHODS: Matrigel tube formation assay, cell cycle, and mobility in human umbilical vein endothelial cells (HUVECs) and hindlimb ischemia (HLI) in mice were applied to determine the angiogenic effect of condition medium (CM) and exosomes. Proteome profiler, microRNA sponge, Due-luciferase assay, microRNA-sequencing, qRT-PCR, and Western blot were used to determine the underlying mechanism of the angiogenic effect of exosomes from BK-c-kit+. RESULTS: As a result, BK-c-kit+ CM and exosomes promoted tube formation in HUVECs and the repair of HLI in mice. Angiogenesis-related proteomic profiling and microRNA sequencing revealed highly enriched miR-3059-5p as a key angiogenic component of BK-c-kit+ exosomes. Meanwhile, loss- and gain-of-function experiments revealed that the promotion of angiogenesis by miR-3059-5p was mainly through suppression of TNFSF15-inhibited effects on vascular tube formation, cell proliferation and cell migration. Moreover, enhanced angiogenesis of miR-3059-5p-inhibited TNFSF15 has been associated with Akt/Erk1/2/Smad2/3-modulated signaling pathway. CONCLUSION: Our results demonstrated a novel finding that BK-c-kit+ cells enrich exosomal miR-3059-5p to suppress TNFSF15 and promote angiogenesis against hindlimb ischemia in mice.

Mixtures of per- and poly-fluoroalkyl substances (PFAS) reduce the in vitro activation of human T cells and basophils.

In the last decades, per- and poly-fluoroalkyl substances (PFAS), widely used industrial chemicals, have been in the center of attention because of their omnipotent presence in water and soils worldwide. Although efforts have been made to substitute long-chain PFAS towards safer alternatives, their persistence in humans still leads to exposure to these compounds. PFAS immunotoxicity is poorly understood as no comprehensive analyses on certain immune cell subtypes exist. Furthermore, mainly single entities and not PFAS mixtures have been assessed. In the present study we aimed to investigate the effect of PFAS (short-chain, long-chain and a mixture of both) on the in vitro activation of primary human immune cells. Our results show the ability of PFAS to reduce T cells activation. In particular, exposure to PFAS affected T helper cells, cytotoxic T cells, Natural Killer T cells, and Mucosal associated invariant T (MAIT) cells, as assessed by multi-parameter flow cytometry. Furthermore, the exposure to PFAS reduced the expression of several genes involved in MAIT cells activation, including chemokine receptors, and typical proteins of MAIT cells, such as GZMB, IFNG and TNFSF15 and transcription factors. These changes were mainly induced by the mixture of both short- and long-chain PFAS. In addition, PFAS were able to reduce basophil activation induced by anti-FcεR1α, as assessed by the decreased expression of CD63. Our data clearly show that the exposure of immune cells to a mixture of PFAS at concentrations mimicking real-life human exposure resulted in reduced cell activation and functional changes of primary innate and adaptive human immune cells.

Hypomethylation of Tumor necrosis factor-like cytokine 1A(TL1A) and its decoy receptor 3 expressive level increase has diagnostic value in HBV-associated cirrhosis.

For patients with cirrhosis, early diagnosis is the key to delaying the development of liver fibrosis and improving prognosis. This study aimed to investigate the clinical significance of TL1A, which is a susceptibility gene for hepatic fibrosis, and DR3 in the development of cirrhosis and fibrosis. We analyzed the expression of TL1A, DR3, and other inflammatory cytokines associated with liver fibrosis in serum and PBMCs in 200 patients.TL1A methylation level was lower in patients with HBV-associated LC than in the other groups. In addition, the mRNA level and serum of TL1A and DR3 expression levels were found to increase in the LC. Hypomethylation of the TL1A promoter is present in HBV-associated LC, and TL1A and DR3 are highly expressed in HBV-associated cirrhosis. These results indicate that TL1A and DR3 may play an important role in the pathogenesis of LC and TL1A methylation levels may serve as a noninvasive biomarker for early diagnosis and progression of LC.

Integrated Analysis of Transcriptome Changes in Osteoarthritis: Gene Expression, Pathways and Alternative Splicing.

OBJECTIVE: Osteoarthritis (OA) is the most prevalent joint disease characterized by the degeneration of articular cartilage and the remodeling of its underlying bones, resulting in pain and loss of function in the knees and hips. As far as we know, no curative treatments are available except for the joint replacement. The precise molecular mechanisms which are involved in the degradation of cartilage matrix and development of osteoarthritis are still unclear. DESIGN: By analyzing RNA-seq data, we found the molecular changes at the transcriptome level such as alternative splicing, gene expression, and molecular pathways in OA knees cartilage. RESULTS: Expression analysis have identified 457 differential expressed genes including 266 up-regulated genes such as TNFSF15, ST6GALNAC5, TGFBI, ASPM, and TYM, and 191 down-regulated genes such as ADM, JUN, IRE2, PIGA, and MAFF. Gene set enrichment analysis (GSEA) analysis identified down-regulated pathways related to translation, transcription, immunity, PI3K/AKT, and circadian as well as disturbed pathways related to extracellular matrix and collagen. Splicing analysis identified 442 differential alternative splicing events within 284 genes in osteoarthritis, including genes involved in extracellular matrix (ECM) and alternative splicing, and TIA1 was identified as a key regulator of these splicing events. CONCLUSIONS: These findings provide insights into disease etiology, and offer favorable information to support the development of more effective interventions in response to the global clinical challenge of osteoarthritis.

Increased Serum Levels of Tumor Necrosis Factor-like Ligand 1A in Atopic Dermatitis.

Atopic dermatitis (AD) is a common chronic skin disease with pruritus, affecting 5-20% of the population in developed countries. Though its cause varies from genetic polymorphisms to the environmental factors, the T-helper (Th) 2 inflammation is one of the main characteristic pathoses. TNF superfamily ligand A (TL1A) is a recently discovered cytokine, which is released by various immune cells and reported to have an ability to stimulate Th1, Th2, and Th17 responses. Its association was investigated in chronic inflammatory disease, such as rheumatoid arthritis, inflammatory bowel disease, and psoriasis. However, its role on AD is unclear. To elucidate the association of TL1A in AD, we measured the serum TL1A levels in AD patients and healthy controls and performed the immunohistochemistry of TL1A. The result showed that the serum TL1A levels were higher in AD patients than healthy controls, and they positively correlated with the serum immunoglobulin E levels, serum Lactate dehydrogenase, and the number of eosinophils in peripheral blood. The immunohistochemistry of TL1A also showed TL1A expression in epithelium of AD samples. Because previous studies indicate TL1A has a certain role as an inflammation enhancer in Th2 and/or Th17 polarized disease, TL1A in AD may also has a role as an inflammation generator.

Role of TL1A in Inflammatory Autoimmune Diseases: A Comprehensive Review.

TL1A, also called TNFSF15, is a member of tumor necrosis factor family. It is expressed in different immune cell, such as monocyte, macrophage, dendritic cell, T cell and non-immune cell, for example, synovial fibroblast, endothelial cell. TL1A competitively binds to death receptor 3 or decoy receptor 3, providing stimulatory signal for downstream signaling pathways, and then regulates proliferation, activation, apoptosis of and cytokine, chemokine production in effector cells. Recent findings showed that TL1A was abnormally expressed in autoimmune diseases, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, primary biliary cirrhosis, systemic lupus erythematosus and ankylosing spondylitis. In vivo and in vitro studies further demonstrated that TL1A was involved in development and pathogenesis of these diseases. In this study, we comprehensively discussed the complex immunological function of TL1A and focused on recent findings of the pleiotropic activity conducted by TL1A in inflammatory autoimmune disease. Finish of the study will provide new ideas for developing therapeutic strategies for these diseases by targeting TL1A.

TL1A/DR3 Axis, A Key Target of TNF-a, Augments the Epithelial-Mesenchymal Transformation of Epithelial Cells in OVA-Induced Asthma.

Tumor necrosis factor (TNF)-like cytokine 1A (TL1A), a member of the TNF family, exists in the form of membrane-bound (mTL1A) and soluble protein (sTL1A). TL1A binding its only known functional receptor death domain receptor 3 (DR3) affects the transmission of various signals. This study first proposed that the TL1A/DR3 axis was significantly upregulated in patients and mice with both asthma and high TNF-a expression and in TNF-a-stimulated epithelial Beas-2B cells. Two independent approaches were used to demonstrate that the TL1A/DR3 axis of mice was strongly correlated with TNF-a in terms of exacerbating asthmatic epithelial-mesenchymal transformation (EMT). First, high expression levels of EMT proteins (e.g., collagen I, fibronectin, N-cadherin, and vimentin) and TL1A/DR3 axis were observed when mice airways were stimulated by recombinant mouse TNF-a protein. Moreover, EMT protein and TL1A/DR3 axis expression synchronously decreased after mice with OVA-induced asthma were treated with infliximab by neutralizing TNF-a activity. Furthermore, the OVA-induced EMT of asthmatic mice was remarkably improved upon the deletion of the TL1A/DR3 axis by knocking out the TL1A gene. TL1A siRNA remarkably intervened EMT formation induced by TNF-a in the Beas-2B cells. In addition, EMT was induced by the addition of high concentrations of recombinant human sTL1A with the cell medium. The TL1A overexpression via pc-mTL1A in vitro remarkably increased the EMT formation induced by TNF-a. Overall, these findings indicate that the TL1A/DR3 axis may have a therapeutic role for asthmatic with high TNF-a level.

TNFSF15 facilitates differentiation and polarization of macrophages toward M1 phenotype to inhibit tumor growth.

Macrophages of the M2 phenotype in malignant tumors significantly aid tumor progression and metastasis, as opposed to the M1 phenotype that exhibits anti-cancer characteristics. Raising the ratio of M1/M2 is thus a promising strategy to ameliorate the tumor immunomicroenvironment toward cancer inhibition. We report here that tumor necrosis factor superfamily-15 (TNFSF15), a cytokine with anti-angiogenic activities, is able to facilitate the differentiation and polarization of macrophages toward M1 phenotype. We found that tumors formed in mice by Lewis lung carcinoma (LLC) cells artificially overexpressing TNFSF15 exhibited retarded growth. The tumors displayed a greater percentage of M1 macrophages than those formed by mock-transfected LLC cells. Treatment of mouse macrophage RAW264.7 cells with recombinant TNFSF15 led to augmentation of the phagocytic and pro-apoptotic capacity of the macrophages against cancer cells. Mechanistically, TNFSF15 activated STAT1/3 in bone marrow cells and MAPK, Akt and STAT1/3 in naive macrophages. Additionally, TNFSF15 activated STAT1/3 but inactivated STAT6 in M2 macrophages. Modulations of these signals gave rise to a reposition of macrophage phenotypes toward M1. The ability of TNFSF15 to promote macrophage differentiation and polarization toward M1 suggests that this unique cytokine may have a utility in the reconstruction of the immunomicroenvironment in favor of tumor suppression.

Co-Expression and Functional Interactions of Death Receptor 3 and E-Selectin in Clear Cell Renal Cell Carcinoma.

Similar to the behavior of inflamed tubular epithelial cells, clear cell renal cell carcinoma (ccRCC) cells express death receptor 3 (DR3 or TNFSFR25) in situ, and expression increases with tumor grade. Surprisingly, E-selectin, which can be induced in endothelial cells by DR3 signaling, is also expressed by ccRCC cells and increases with tumor grade. In ccRCC organ cultures, addition of tumor necrosis factor-like 1A (TL1A or TNFSF15), the ligand for DR3, activates NF-κB and mitogen-activated protein kinases, induces both DR3 and E-selectin expression in an NF-κB-dependent manner, and promotes cell cycle entry. DR3 immunoprecipitated from ccRCC tissue contains sialyl Lewis X moieties (the ligand recognized by E-selectin), proximity ligation assays reveal DR3, and E-selectin interacts on ccRCC cells. Similar to that with the addition of TL1A, the addition of soluble E-selectin to ccRCC organ cultures activates NF-κB and mitogen-activated protein kinases in ccRCC cells and increases both DR3 and E-selectin expression and cell-cycle entry. In contrast, normal renal tubular epithelium, which poorly expresses DR3, is minimally responsive to either of these ligands. These data suggest a functional role for autocrine/paracrine DR3/E-selectin interactions in ccRCC and its progression, revealing a potential new target for therapeutic intervention.

Nonylphenol regulates TL1A through the AhR/HDAC2/HNF4α pathway in endothelial cells to promote the angiogenesis of colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the most malignant cancers worldwide. Nonylphenol (NP) is an endocrine-disruptor chemical and plays an important role in the development of cancers. However, the effects of NP on CRC remain unclear. In this study, we aimed to investigate the potential mechanisms of NP in the pathogenesis of CRC. METHODS: The levels of AhR, TL1A and HDAC2 in CRC tissues and endothelial cells were assessed by RT-qPCR or western blot. CHIP and dual luciferase reporter assays were used to confirm the interaction between AhR and HDAC2, or HNF4α and TL1A. The CCK8, would healing and tube formation assays were conducted to evaluate the proliferation, migration and angiogenesis of HUVECs. Western blot determined HNF4α protein and HNF4α acetylation levels. The secreted TL1A protein was detected by ELISA. The angiogenesis-related factor CD31 was tested by IHC. RESULTS: The expression level of AhR was significantly up-regulated in CRC tissues and endothelial cells. Moreover, NP activated the AhR pathway mediated colorectal endothelial cell angiogenesis and proliferation, while TL1A overexpression resisted these effects caused by NP. Besides, NP was found to modulate HNF4α deacetylation through AhR/HDAC2 to inhibit TL1A. Furthermore, in vivo experiments proved that NP regulated CRC growth and angiogenesis via AhR/HDAC2/HNF4α/TL1A axis. CONCLUSION: This study revealed that NP promoted CRC growth and angiogenesis through AhR/HDAC2/HNF4α/TL1A pathway and could be a new therapeutic target for CRC treatment.

Effect and Mechanism of TL1A Expression on Epithelial-Mesenchymal Transition during Chronic Colitis-Related Intestinal Fibrosis.

BACKGROUND AND AIMS: Recent evidences reveal that epithelial to mesenchymal transition (EMT) exacerbates the process of intestinal fibrosis. Tumor necrosis factor-like ligand 1A (TL1A) is a member of the tumor necrosis family (TNF), which can take part in the development of colonic inflammation and fibrosis by regulating immune response or inflammatory factors. The purpose of this study was to elucidate the possible contribution of TL1A in onset and progression of intestinal inflammation and fibrosis through EMT. METHODS: Colonic specimens were obtained from patients with inflammatory bowel disease (IBD) and control individuals. The expression levels of TL1A and EMT-related markers in intestinal tissues were evaluated. Furthermore, the human colorectal adenocarcinoma cell line, HT-29, was stimulated with TL1A, anti-TL1A antibody, or BMP-7 to assess EMT process. In addition, transgenic mice expressing high levels of TL1A in lymphoid cells were used to further investigate the mechanism of TL1A in intestinal fibrosis. RESULTS: High levels of TL1A expression were detected in the intestinal specimens of patients with ulcerative colitis and Crohn's disease and were negatively associated with the expression of an epithelial marker (E-cadherin), while it was positively associated with the expression of interstitial markers (FSP1 and α-SMA). Transgenic mice with high expression of TL1A were more sensitive to dextran sodium sulfate and exhibited severe intestinal inflammation and fibrosis. Additionally, the TGF-ß1/Smad3 pathway may be involved in TL1A-induced EMT, and the expression of IL-13 and EMT-related transcriptional molecules (e.g., ZEB1 and Snail1) was increased in the intestinal specimens of the transgenic mice. Furthermore, TL1A-induced EMT can be influenced by anti-TL1A antibody or BMP-7 in vitro. CONCLUSIONS: TL1A participates in the formation and process of EMT in intestinal fibrosis. This new knowledge enables us to better understand the pathogenesis of intestinal fibrosis and identify new therapeutic targets for its treatment.

TNFSF15 Promotes Antimicrobial Pathways in Human Macrophages and These Are Modulated by TNFSF15 Disease-Risk Variants.

BACKGROUND & AIMS: TNFSF15 genetic variants leading to increased TNF superfamily member 15 (TNFSF15) expression confer risk for inflammatory bowel disease (IBD), and TNFSF15 is being explored as a therapeutic target in IBD patients. Although the focus for TNFSF15-mediated inflammatory outcomes has been predominantly on its action on T cells, TNFSF15 also promotes inflammatory outcomes in human macrophages. Given the critical role for macrophages in bacterial clearance, we hypothesized that TNFSF15 promotes antimicrobial pathways in human macrophages and that macrophages from TNFSF15 IBD risk carriers with higher TNFSF15 expression have an advantage in these antimicrobial outcomes. METHODS: We analyzed protein expression, signaling, bacterial uptake, and intracellular bacterial clearance in human monocyte-derived macrophages through flow cytometry, enzyme-linked immunosorbent assay, and gentamicin protection. RESULTS: Autocrine/paracrine TNFSF15 interactions with death receptor 3 (DR3) were required for optimal levels of pattern-recognition-receptor (PRR)-induced bacterial clearance in human macrophages. TNFSF15 induced pyruvate dehydrogenase kinase 1-dependent bacterial uptake and promoted intracellular bacterial clearance through reactive oxygen species, nitric oxide synthase 2, and autophagy up-regulation. The TNFSF15-initiated TNF receptor-associated factor 2/receptor-interacting protein kinase 1/RIP3 pathway was required for mitogen-activated protein kinase and nuclear factor-κB activation, and, in turn, induction of each of the antimicrobial pathways; the TNFSF15-initiated Fas-associated protein with death domain/mucosa-associated lymphoid tissue lymphoma translocation protein 1/caspase-8 pathway played a less prominent role in antimicrobial functions, despite its key role in TNFSF15-induced cytokine secretion. Complementation of signaling pathways or antimicrobial pathways restored bacterial uptake and clearance in PRR-stimulated macrophages where TNFSF15:DR3 interactions were inhibited. Monocyte-derived macrophages from high TNFSF15-expressing rs6478108 TT IBD risk carriers in the TNFSF15 region showed increased levels of the identified antimicrobial pathways. CONCLUSIONS: We identify that autocrine/paracrine TNFSF15 is required for optimal PRR-enhanced antimicrobial pathways in macrophages, define mechanisms regulating TNFSF15-dependent bacterial clearance, and determine how the TNFSF15 IBD risk genotype modulates these outcomes.

Signaling in TNFSF15-mediated Suppression of VEGF Production in Endothelial Cells.

Vascular endothelial growth factor (VEGF) plays a pivotal role in promoting neovascularization. Tumor necrosis factor superfamily 15 (TNFSF15) is an antiangiogenic cytokine prominently produced by endothelial cells in a normal vasculature. In this study, Western blot, quantitative polymerase chain reaction (qPCR), and dual luciferase reporter gene assay were used to validate the mechanisms of TNFSF15-mediated suppression of VEGF production in endothelial cells. We report that TNFSF15 inhibits VEGF production via microRNA-29b (miR-29b) targeting the 3'-UTR of VEGF transcript in mouse endothelial cell line bEnd.3. Neutralizing antibody against TNFSF15, 4-3H, inhibits the level of miR-29b and reinvigorates VEGF. In addition, TNFSF15 activates the JNK signaling pathway as well as the transcription factor GATA3, resulting in enhanced miR-29b production. SP600125, an inhibitor of JNK, eradicates TNFSF15-induced GATA3 expression. Moreover, GATA3 siRNA suppressed TNFSF15-induced miR-29b expression. Together, this study provides evidence and method of activation of the JNK-GATA3 signaling pathway by TNFSF15 that suppresses VEGF gene expression, which gives rise to upregulation of miR-29b.

Direct signaling of TL1A-DR3 on fibroblasts induces intestinal fibrosis in vivo.

Tumor necrosis factor-like cytokine 1A (TL1A, TNFSF15) is implicated in inflammatory bowel disease, modulating the location and severity of inflammation and fibrosis. TL1A expression is increased in inflamed mucosa and associated with fibrostenosing Crohn's disease. Tl1a-overexpression in mice causes spontaneous ileitis, and exacerbates induced proximal colitis and fibrosis. Intestinal fibroblasts express Death-receptor 3 (DR3; the only know receptor for TL1A) and stimulation with TL1A induces activation in vitro. However, the contribution of direct TL1A-DR3 activation on fibroblasts to fibrosis in vivo remains unknown. TL1A overexpressing naïve T cells were transferred into Rag-/- , Rag-/- mice lacking DR3 in all cell types (Rag-/-Dr3-/-), or Rag-/- mice lacking DR3 only on fibroblasts (Rag-/-Dr3∆Col1a2) to induce colitis and fibrosis, assessed by clinical disease activity index, intestinal inflammation, and collagen deposition. Rag-/- mice developed overt colitis with intestinal fibrostenosis. In contrast, Rag-/-Dr3-/- demonstrated decreased inflammation and fibrosis. Despite similar clinical disease and inflammation as Rag-/-, Rag-/-Dr3∆Col1a2 exhibited reduced intestinal fibrosis and attenuated fibroblast activation and migration. RNA-Sequencing of TL1A-stimulated fibroblasts identified Rho signal transduction as a major pathway activated by TL1A and inhibition of this pathway modulated TL1A-mediated fibroblast functions. Thus, direct TL1A signaling on fibroblasts promotes intestinal fibrosis in vivo. These results provide novel insight into profibrotic pathways mediated by TL1A paralleling its pro-inflammatory effects.

TNFSF15 facilitates human umbilical cord blood haematopoietic stem cell expansion by activating Notch signal pathway.

The lack of efficient ex vivo expansion methods restricts clinical use of haematopoietic stem cells (HSC) for the treatment of haematological malignancies and degenerative diseases. Umbilical cord blood (UCB) serves as an alternative haematopoietic stem cell source. However, currently what limits the use of UCB-derived HSC is the very low numbers of haematopoietic stem and progenitor cells available for transplantation in a single umbilical cord blood unit. Here, we report that TNFSF15, a member of the tumour necrosis factor superfamily, promotes the expansion of human umbilical cord blood (UCB)-derived HSC. TNFSF15-treated UCB-HSC is capable of bone marrow engraftment as demonstrated with NOD/SCID or NOD/Shi-SCID/IL2Rgnull (NOG) mice in both primary and secondary transplantation. The frequency of repopulating cells occurring in the injected tibiae is markedly higher than that in vehicle-treated group. Additionally, signal proteins of the Notch pathway are highly up-regulated in TNFSF15-treated UCB-HSC. These findings indicate that TNFSF15 is useful for in vitro expansion of UCB-HSC for clinical applications. Furthermore, TNFSF15 may be a hopeful selection for further UCB-HSC application or study.

A TRAIL-TL1A Paracrine Network Involving Adipocytes, Macrophages, and Lymphocytes Induces Adipose Tissue Dysfunction Downstream of E2F1 in Human Obesity.

Elevated expression of E2F1 in adipocyte fraction of human visceral adipose tissue (hVAT) associates with a poor cardiometabolic profile. We hypothesized that beyond directly activating autophagy and MAP3K5 (ASK)-MAP kinase signaling, E2F1 governs a distinct transcriptome that contributes to adipose tissue and metabolic dysfunction in obesity. We performed RNA sequencing of hVAT samples from age-, sex-, and BMI-matched patients, all obese, whose visceral E2F1 protein expression was either high (E2F1high) or low (E2F1low). Tumor necrosis factor superfamily (TNFSF) members, including TRAIL (TNFSF10), TL1A (TNFSF15), and their receptors, were enriched in E2F1high While TRAIL was equally expressed in adipocytes and stromal vascular fraction (SVF), TL1A was mainly expressed in SVF, and TRAIL-induced TL1A was attributed to CD4+ and CD8+ subclasses of hVAT T cells. In human adipocytes, TL1A enhanced basal and impaired insulin-inhibitable lipolysis and altered adipokine secretion, and in human macrophages it induced foam cell biogenesis and M1 polarization. Two independent human cohorts confirmed associations between TL1A and TRAIL expression in hVAT and higher leptin and IL6 serum concentrations, diabetes status, and hVAT-macrophage lipid content. Jointly, we propose an intra-adipose tissue E2F1-associated TNFSF paracrine loop engaging lymphocytes, macrophages, and adipocytes, ultimately contributing to adipose tissue dysfunction in obesity.