TEM1/endosialin/CD248 promotes pathologic scarring and TGF-ß activity through its receptor stability in dermal fibroblasts.

BACKGROUND: Pathologic scars, including keloids and hypertrophic scars, represent a common form of exaggerated cutaneous scarring that is difficult to prevent or treat effectively. Additionally, the pathobiology of pathologic scars remains poorly understood. We aim at investigating the impact of TEM1 (also known as endosialin or CD248), which is a glycosylated type I transmembrane protein, on development of pathologic scars. METHODS: To investigate the expression of TEM1, we utilized immunofluorescence staining, Western blotting, and single-cell RNA-sequencing (scRNA-seq) techniques. We conducted in vitro cell culture experiments and an in vivo stretch-induced scar mouse model to study the involvement of TEM1 in TGF-ß-mediated responses in pathologic scars. RESULTS: The levels of the protein TEM1 are elevated in both hypertrophic scars and keloids in comparison to normal skin. A re-analysis of scRNA-seq datasets reveals that a major profibrotic subpopulation of keloid and hypertrophic scar fibroblasts greatly expresses TEM1, with expression increasing during fibroblast activation. TEM1 promotes activation, proliferation, and ECM production in human dermal fibroblasts by enhancing TGF-ß1 signaling through binding with and stabilizing TGF-ß receptors. Global deletion of Tem1 markedly reduces the amount of ECM synthesis and inflammation in a scar in a mouse model of stretch-induced pathologic scarring. The intralesional administration of ontuxizumab, a humanized IgG monoclonal antibody targeting TEM1, significantly decreased both the size and collagen density of keloids. CONCLUSIONS: Our data indicate that TEM1 plays a role in pathologic scarring, with its synergistic effect on the TGF-ß signaling contributing to dermal fibroblast activation. Targeting TEM1 may represent a novel therapeutic approach in reducing the morbidity of pathologic scars.

VEGF-Induced Endothelial Podosomes via ROCK2-Dependent Thrombomodulin Expression Initiate Sprouting Angiogenesis.

[Figure: see text].

Role of tumor endothelial marker 1 (Endosialin/CD248) lectin-like domain in lipopolysaccharide-induced macrophage activation and sepsis in mice.

Deleterious hyper-inflammation resulting from macrophage activation may aggravate sepsis and lead to lethality. Tumor endothelial marker 1 (TEM1), a type I transmembrane glycoprotein containing six functional domains, has been implicated in cancer and chronic sterile inflammatory disorders. However, the role of TEM1 in acute sepsis remains to be determined. Herein we explored the functional significance of the TEM1 lectin-like domain (TEM1D1) in monocyte/macrophage activation and sepsis using TEM1D1-deleted (TEM1LeD/LeD) transgenic mice and recombinant TEM1D1 (rTEM1D1) protein. Under stimulation with lipopolysaccharides (LPS) or several other toll-like receptor agonists, TEM1LeD/LeD macrophages produced lower levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 than wild-type TEM1wt/wt macrophages. Compared with TEM1wt/wt macrophages, LPS-macrophage binding and intracellular mitogen-activated protein kinase (MAPK)/nuclear factor (NF)-κB activation were suppressed in TEM1LeD/LeD macrophages. In vivo, TEM1D1 deletion improved survival in LPS-challenged mice with reduction of circulating TNF-α and IL-6 and alleviation of lung injury and pulmonary leukocyte accumulation. In contrast, rTEM1D1 could bind to LPS and markedly suppress LPS-macrophage binding, MAPK/NF-κB signaling in macrophages and proinflammatory cytokine production. Treatment with rTEM1D1 improved survival and attenuated circulating TNF-α and IL-6, lung injury and pulmonary accumulation of leukocytes in LPS-challenged mice. These findings demonstrated differential roles for the TEM1 lectin-like domain in macrophages and soluble TEM1 lectin-like domain in sepsis. TEM1 in macrophages mediates LPS-induced inflammation via its lectin-like domain, whereas rTEM1D1 interferes with LPS-induced macrophage activation and sepsis.

A thrombomodulin-like gene is crucial to the collective migration of epibolic blastomeres during germ layer formation and organogenesis in zebrafish.

BACKGROUND: Thrombomodulin (TM), an integral membrane protein, has long been known for its anticoagulant activity. Recent studies showed that TM displays multifaceted activities, including the involvement in cell adhesion and collective cell migration in vitro. However, whether TM contributes similarly to these biological processes in vivo remains elusive. METHODS: We adapted zebrafish, a prominent animal model for studying molecular/cellular activity, embryonic development, diseases mechanism and drug discovery, to examine how TM functions in modulating cell migration during germ layer formation, a normal and crucial physiological process involving massive cell movement in the very early stages of life. In addition, an in vivo assay was developed to examine the anti-hemostatic activity of TM in zebrafish larva. RESULTS: We found that zebrafish TM-b, a zebrafish TM-like protein, was expressed mainly in vasculatures and displayed anti-hemostatic activity. Knocking-down TM-b led to malformation of multiple organs, including vessels, heart, blood cells and neural tissues. Delayed epiboly and incoherent movement of yolk syncytial layer were also observed in early TM-b morphants. Whole mount immunostaining revealed the co-localization of TM-b with both actin and microtubules in epibolic blastomeres. Single-cell tracking revealed impeded migration of blastomeres during epiboly in TM-b-deficient embryos. CONCLUSION: Our results showed that TM-b is crucial to the collective migration of blastomeres during germ layer formation. The structural and functional compatibility and conservation between zebrafish TM-b and mammalian TM support the properness of using zebrafish as an in vivo platform for studying the biological significance and medical use of TM.

The role of vascular smooth muscle cell membrane-bound thrombomodulin in neointima formation.

BACKGROUND AND AIMS: Thrombomodulin (TM) is an endothelial cell membrane-bound anticoagulant protein expressed in normal arteries. After vascular injury, medial and neointimal smooth muscle cells (SMCs) exhibit large amounts of TM. The purpose of this study was to investigate the physiological significance of vascular SMC-bound TM. METHODS: The morphology, expression of phenotype markers and cell behaviors of cultured aortic SMCs after knockdown of TM were observed. Transgenic mice with SMC-specific TM deletion were generated, and carotid neointima formation was induced by carotid ligation. RESULTS: Cultured human aortic SMCs displayed a synthetic phenotype with a rhomboid-shaped morphology and expressed TM. TM knockdown induced a spindle-shaped change in morphology with an increased expression of contractile phenotype marker and decreased expression of synthetic phenotype marker. TM knockdown not only attenuated the proliferation of SMCs but also reduced tumor necrosis factor-α-induced nuclear factor-κB activation and interlukin-6 production. In a carotid artery ligation model, transgenic mice with SMC-specific TM deletion (SM22-cretg/TMflox/flox) had significantly less cellular proliferation in arterial walls compared with wild type mice (SM22-cretg/TM+/+). The neointima area and neointima/media area ratio were smaller in SM22-cretg/TMflox/flox mice at 4 weeks after ligation. CONCLUSIONS: Our results indicate that vascular SMC-bound TM plays a role in changes of the SMC phenotype. It also influences SMC cell behavior and injury-induced neointima formation.

Tumor Endothelial Marker 1 (TEM1/Endosialin/CD248) Enhances Wound Healing by Interacting with Platelet-Derived Growth Factor Receptors.

Tumor endothelial marker 1 (TEM1), also known as endosialin or CD248, is a type I transmembrane glycoprotein containing a C-type lectin-like domain. It is highly expressed in pericytes and fibroblasts. Dermal fibroblasts play a pivotal role during cutaneous wound healing, especially in the proliferative phase. However, the physiological function of TEM1 in wound healing is still undetermined. During the process of wound healing, the expression of both TEM1 and platelet-derived growth factor (PDGF) receptor α was highly upregulated in myofibroblasts. In vivo, fibroblast activation and collagen deposition in granulation tissues were attenuated, and wound healing was retarded in TEM1-deleted mice. In vitro, the migration, adhesion, and proliferation of NIH3T3 cells were suppressed following TEM1 knockdown by short hairpin RNA. In PDGF-BB-treated NIH3T3 cells, the downstream signal and mitogenic, and chemoattractive effects were inhibited by TEM1 knockdown. In addition, TEM1 and PDGF receptor α were colocalized in subcellular organelles in fibroblasts, and the association of TEM1 and PDGF receptor α was demonstrated by coimmunoprecipitation. In summary, these findings suggested that TEM1, in combination with PDGF receptor α, plays a critical role in wound healing by enhancing the mitogenic and chemoattractive effects of PDGF-BB and collagen deposition in myofibroblasts.

Plasminogen/thrombomodulin signaling enhances VEGF expression to promote cutaneous wound healing.

Plasminogen (Plg) and thrombomodulin (TM) are glycoproteins well known for fibrinolytic and anticoagulant functions, respectively. Both Plg and TM are essential for wound healing. However, their significance during the reparative process was separately demonstrated in previous studies. Here, we investigate the interaction between Plg and epithelial TM and its effect on wound healing. Characterization of the wound margin revealed that Plg and TM were simultaneously upregulated at the early stage of wound healing and the two molecules were bound together. In vitro, TM silencing or knockout in keratinocytes inhibited Plg activation. Plg treatment enhanced keratinocyte proliferation and migration, and these actions were abolished by TM antibody. Keratinocyte-expressed vascular endothelial growth factor (VEGF), which presented a dose-response relationship with Plg treatment, can be suppressed by TM silencing. Moreover, treatment with VEGF antibody inhibited Plg-enhanced keratinocyte proliferation and wound recovery. In vivo, TM antibody treatment and keratinocyte-specific TM knockout can impede Plg-enhanced wound healing in mice. In high-glucose environments, Plg-enhanced VEGF expression and wound healing were suppressed due at least in part to downregulation of keratinocyte-expressed TM. Taken together, our findings suggest that activation of Plg/TM signaling may hold therapeutic potential for chronic wounds in diabetic or non-diabetic individuals. KEY MESSAGES: Plg binds to TM in cutaneous wound healing. TM facilitates the activation of Plg to Plm in keratinocytes. Epithelial TM regulates Plg-enhanced wound healing through VEGF expression.

The chondroitin sulfate moiety mediates thrombomodulin-enhanced adhesion and migration of vascular smooth muscle cells.

BACKGROUND: Thrombomodulin (TM), a transmembrane glycoprotein highly expressed in endothelial cells (ECs), is a potent anticoagulant maintaining circulation homeostasis. Under inflammatory states, TM expression is drastically reduced in ECs while vascular smooth muscle cells (VSMCs) show a robust expression of TM. The functional role of TM in VSMCs remains elusive. METHODS: We examined the role of TM in VSMCs activities in human aortic VSMCs stimulated with platelet-derived growth factor-BB (PDGF-BB). Using rat embryonic aorta-derived A7r5 VSMCs which do not express TM, the role of the chondroitin sulfate (CS) moiety of TM in VSMCs was delineated with cells expressing wild-type TM and the CS-devoid TM mutant. RESULTS: Expression of TM enhanced cell migration and adhesion/spreading onto type I collagen, but had no effect on cell proliferation. Knocking down TM with short hairpin RNA reduced PDGF-stimulated adhesion and migration of human aortic VSMCs. In A7r5 cells, TM-mediated cell adhesion was eradicated by pretreatment with chondroitinase ABC which degrades CS moiety. Furthermore, the TM mutant (TMS490, 492A) devoid of CS moiety failed to increase cell adhesion, spreading or migration. Wild-type TM, but not TMS490, 492A, increased focal adhesion kinase (FAK) activation during cell adhesion, and TM-enhanced cell migration was abolished by a function-blocking anti-integrin ß1 antibody. CONCLUSION: Chondroitin sulfate modification is required for TM-mediated activation of ß1-integrin and FAK, thereby enhancing adhesion and migration activity of VSMCs.

Recombinant Thrombomodulin Exerts Anti-autophagic Action in Endothelial Cells and Provides Anti-atherosclerosis Effect in Apolipoprotein E Deficient Mice.

Stress-induced alteration in endothelial cells (ECs) integrity precedes the development of atherosclerosis. Previous studies showed that the soluble recombinant thrombomodulin (rTM) not only increases ECs proliferation but also exerts anti-apoptotic activity in ECs. However, the functional significance of soluble rTM on autophagy-related apoptosis in ECs is still undetermined. Implicating a cytoprotective role for rTM in persistent serum starvation (SS)-induced autophagy in cultured ECs, we found that treatment of rTM decreased the expression of SS-induced autophagy-related proteins, ATG5 and LC3, and the formation of autophagosomes through activation of AKT/mTOR pathway. In addition, treatment of rTM decreased SS-induced EC apoptosis, but this effect of rTM could not be recapitulated by co-treatment with a potent autophagy inducer, rapamycin and in ECs with ATG5 knockdown. In human atherosclerosis specimens, expression of autophagy markers, ATG13 and LC3, were more abundant in aortic intimal ECs with severe atherosclerosis than those without atherosclerosis. Moreover, compared to saline treatment group, administration of rTM reduced LC3 and ATG13 expression, intimal EC apoptosis, and atherosclerotic lesion severity in the aorta of apolipoprotein E deficient mice. In conclusion, treatment with rTM suppressed stress-induced autophagy overactivation in ECs, provided ECs protective effects, and decreased atherosclerosis in apolipoprotein E deficient mice.

Recombinant adeno-associated virus vector carrying the thrombomodulin lectin-like domain for the treatment of abdominal aortic aneurysm.

BACKGROUND AND AIMS: Thrombomodulin (TM), through its lectin-like domain (TMD1), sequesters proinflammatory high-mobility group box 1 (HMGB1) to prevent it from engaging the receptor for advanced glycation end product (RAGE) that sustains inflammation and tissue damage. Our previous study demonstrated that short-term treatment with recombinant TM containing all the extracellular domains (i.e., rTMD123) inhibits HMGB1-RAGE signaling and confers protection against CaCl2-induced AAA formation. In this study, we attempted to further optimize TM domains, as a potential therapeutic agent for AAA, using the recombinant adeno-associated virus (AAV) vector. METHODS: The therapeutic effects of recombinant TMD1 (rTMD1) and recombinant AAV vectors carrying the lectin-like domain of TM (rAAV-TMD1) were evaluated in the CaCl2-induced AAA model and angiotensin II-infused AAA model, respectively. RESULTS: In the CaCl2-induced model, treatment with rTMD1 suppressed the tissue levels of HMGB1 and RAGE, macrophage accumulation, elastin destruction and AAA formation, and the effects were comparable to a mole-equivalent dosage of rTMD123. In the angiotensin II-infused model, a single intravenous injection of rAAV-TMD1 (1011 genome copies), which resulted in a persistently high serum level of TMD1 for at least 12 weeks, effectively attenuated AAA formation with suppression of HMGB1 and RAGE levels and inhibition of proinflammatory cytokine production, macrophage accumulation, matrix metalloproteinase activities and oxidative stress in the aortic wall. CONCLUSIONS: These findings corroborate the therapeutic potential of the TM lectin-like domain in AAA. The attenuation of angiotensin II-infused AAA by one-time delivery of rAAV-TMD1 provides a proof-of-concept validation of its application as potential gene therapy for aneurysm development.

Monocytic thrombomodulin promotes cell adhesion through interacting with its ligand, Lewisy.

The leukocyte adhesion cascade involves multiple events that efficiently localize circulating leukocytes into the injured sites to mediate inflammatory responses. From rolling to firm adhesion, the interactions between adhesion molecules have pivotal roles in increasing the avidity of leukocytes to endothelial cells. Thrombomodulin (TM), an essential anticoagulant protein in the vasculature, is also expressed on leukocytes. We previously demonstrated that Lewisy (Ley), a specific ligand of TM, is upregulated in inflamed endothelium and is involved in leukocyte adhesion. The current study aimed to investigate whether leukocyte-expressed TM promotes cell adhesion by interacting with Ley. Using human monocytic THP-1 cells as an in vitro cell model, we showed that TM increases THP-1 cell adhesion to inflamed endothelium as well as to Ley-immobilized surface. When THP-1 adhered to activated endothelium and Ley-immobilized surface, the TM distribution became polarized. Addition of soluble Ley to a suspension of THP-1 cells with TM expression triggered an increase in the level of phosphorylated p38 mitogen-activated protein kinase (MAPK), which enabled THP-1 to adhere firmly to intercellular adhesion molecule (ICAM)-1 by activating ß2 integrins. In vivo, macrophage infiltration and neointima formation following arterial ligation-induced vascular injury were higher in wild-type TM (TMflox/flox) than in myeloid-specific TM-deficient (LysMcre/TMflox/flox) mice. Taken together, these results suggest a novel function for TM as an adhesion molecule in monocytes, where it enhances cell adhesion by binding Ley, leading to ß2 integrin activation via p38 MAPK.

Thrombomodulin promotes focal adhesion kinase activation and contributes to angiogenesis by binding to fibronectin.

Angiogenesis promotes tumor growth and metastasis. Cell adhesion molecules interact with the extracellular matrix (ECM) and increase cell adhesion and migration during angiogenesis. Thrombomodulin (TM) is a cell surface transmembrane glycoprotein expressed in endothelial cells. However, the function and significance of TM in cell-matrix interactions and angiogenesis remain unclear. Here, we first demonstrated that recombinant lectin-like domain of TM interacts with an ECM protein, fibronectin, and identified the N-terminal 70-kDa domain of fibronectin as the TM-binding site. Exogenous expression of TM in TM-deficient A2058 melanoma cells enhanced cell adhesion and migration on fibronectin and invasion on Matrigel. In addition, TM increased focal adhesion kinase (FAK) phosphorylation and matrix metalloproteinase-9 production. In mice bearing subcutaneous B16F10 melanoma tumors, immunofluorescence analysis indicated that TM was highly expressed and co-localized with fibronectin on the tumor vasculature. The interaction between TM and fibronectin in tumor blood vessels was also validated by the proximity ligation assay. In human umbilical vein endothelial cells, up-regulation of TM by vascular endothelial growth factor (VEGF), a tumor angiogenic factor, promoted cell adhesion and tube formation, whereas TM knockdown by RNA interference attenuated VEGF-induced cell adhesion and tube formation. In summary, TM promotes angiogenesis by enhancing cell adhesion, migration, and FAK activation through interaction with fibronectin. TM may represent a novel target for inhibiting tumor angiogenesis.

Myeloid thrombomodulin lectin-like domain inhibits osteoclastogenesis and inflammatory bone loss.

Osteoclastogenesis is an essential process during bone metabolism which can also be promoted by inflammatory signals. Thrombomodulin (TM), a transmembrane glycoprotein, exerts anti-inflammatory activities such as neutralization of proinflammatory high-mobility group box 1 (HMGB1) through TM lectin-like domain. This study aimed to identify the role of myeloid TM (i.e., endogenous TM expression on the myeloid lineage) in osteoclastogenesis and inflammatory bone loss. Using human peripheral blood mononuclear cells and mouse bone marrow-derived macrophages, we observed that the protein levels of TM were dramatically reduced as these cells differentiated into osteoclasts. In addition, osteoclastogenesis and extracellular HMGB1 accumulation were enhanced in primary cultured monocytes from myeloid-specific TM-deficient mice (LysMcre/TM(flox/flox)) and from TM lectin-like domain deleted mice (TM(LeD/LeD)) compared with their respective controls. Micro-computerized tomography scans showed that ovariectomy-induced bone loss was more pronounced in TM(LeD/LeD) mice compared with controls. Finally, the inhibiting effects of recombinant TM lectin-like domain (rTMD1) on bone resorption in vitro, and bone loss in both the ovariectomized model and collagen antibody-induced arthritis model has been detected. These findings suggested that the myeloid TM lectin-like domain may inhibit osteoclastogenesis by reducing HMGB1 signaling, and rTMD1 may hold therapeutic potential for inflammatory bone loss.

Toll-Like Receptor 4 Is Essential in the Development of Abdominal Aortic Aneurysm.

Toll-like receptor (TLR) family plays a key role in innate immunity and various inflammatory responses. TLR4, one of the well-characterized pattern-recognition receptors, can be activated by endogenous damage-associated molecular pattern molecules such as high mobility group box 1 (HMGB1) to sustain sterile inflammation. Evidence suggested that blockade of TLR4 signaling may confer protection against abdominal aortic aneurysm (AAA). Herein we aimed to obtain further insight into the mechanism by which TLR4 might promote aneurysm formation. Characterization of the CaCl2-induced AAA model in mice revealed that upregulation of TLR4 expression, localized predominantly to vascular smooth muscle cells (VSMCs), was followed by a late decline during a 28-day period of AAA development. In vitro, TLR4 expression was increased in VSMCs treated with HMGB1. Knockdown of TLR4 by siRNA attenuated HMGB1-enhanced production of proinflammatory cytokines, specifically interleukin-6 and monocyte chemoattractant protein-1 (MCP-1), and matrix-degrading matrix metalloproteinase (MMP)-2 from VSMCs. In vivo, two different strains of TLR4-deficient (C57BL/10ScNJ and C3H/HeJ) mice were resistant to CaCl2-induced AAA formation compared to their respective controls (C57BL/10ScSnJ and C3H/HeN). Knockout of TLR4 reduced interleukin-6 and MCP-1 levels and HMGB1 expression, attenuated macrophage accumulation, and eventually suppressed MMP production, elastin destruction and VSMC loss. Finally, human AAA exhibited higher TLR4 expression that was localized to VSMCs. These data suggest that TLR4 signaling contributes to AAA formation by promoting a proinflammatory status of VSMCs and by inducing proteinase release from VSMCs during aneurysm initiation and development.

Membrane-Bound Thrombomodulin Regulates Macrophage Inflammation in Abdominal Aortic Aneurysm.

OBJECTIVE: Thrombomodulin (TM), a glycoprotein constitutively expressed in the endothelium, is well known for its anticoagulant and anti-inflammatory properties. Paradoxically, we recently found that monocytic membrane-bound TM (ie, endogenous TM expression in monocytes) triggers lipopolysaccharide- and gram-negative bacteria-induced inflammatory responses. However, the significance of membrane-bound TM in chronic sterile vascular inflammation and the development of abdominal aortic aneurysm (AAA) remains undetermined. APPROACH AND RESULTS: Implicating a potential role for membrane-bound TM in AAA, we found that TM signals were predominantly localized to macrophages and vascular smooth muscle cells in human aneurysm specimens. Characterization of the CaCl2-induced AAA in mice revealed that during aneurysm development, TM expression was mainly localized in infiltrating macrophages and vascular smooth muscle cells. To investigate the function of membrane-bound TM in vivo, transgenic mice with myeloid- (LysMcre/TM(flox/flox)) and vascular smooth muscle cell-specific (SM22-cre(tg)/TM(flox/flox)) TM ablation and their respective wild-type controls (TM(flox/flox) and SM22-cre(tg)/TM(+/+)) were generated. In the mouse CaCl2-induced AAA model, deficiency of myeloid TM, but not vascular smooth muscle cell TM, inhibited macrophage accumulation, attenuated proinflammatory cytokine and matrix metalloproteinase-9 production, and finally mitigated elastin destruction and aortic dilatation. In vitro TM-deficient monocytes/macrophages, versus TM wild-type counterparts, exhibited attenuation of proinflammatory mediator expression, adhesion to endothelial cells, and generation of reactive oxygen species. Consistently, myeloid TM-deficient hyperlipidemic mice (ApoE(-/-)/LysMcre/TM(flox/flox)) were resistant to AAA formation induced by angiotensin II infusion, along with reduced macrophage infiltration, suppressed matrix metalloproteinase activities, and diminished oxidative stress. CONCLUSIONS: Membrane-bound TM in macrophages plays an essential role in the development of AAA by enhancing proinflammatory mediator elaboration, macrophage recruitment, and oxidative stress.

Development of Recombinant Adeno-Associated Virus Serotype 2/8 Carrying Kringle Domains of Human Plasminogen for Sustained Expression and Cancer Therapy.

Angiostatin and other plasminogen derivatives exhibit antitumor activities directly or indirectly, have demonstrated promising anticancer effects in preclinical studies, but have mostly failed in clinical trials partly due to their short serum half-lives. Our previous studies demonstrated that recombinant human plasminogen kringle 1-5 (K1-5) has superior antitumor activity compared with angiostatin. In addition, optimization of recombinant K1-5 with three amino acid substitutions enhances its antitumor effect. The current study was thus undertaken to evaluate prolonged expression of optimized K1-5 as cancer gene therapy. The recombinant adeno-associated virus (AAV) vector was used to express a secreted form of the optimized K1-5 (AAV-sK15tm) to improve its pharmacokinetic profile, which was considered to be the hurdle in angiostatin treatment of cancer. We successfully generated high-titer recombinant AAV vectors and observed sustained transgene expression for 567 days after a single injection of virus. The treated animals did not display any visible signs of abnormalities and showed normal serum biochemistry. The therapeutic potential of this treatment modality was demonstrated by both a strong inhibition of lung metastasis in the mouse B16F10 melanoma model and significant growth retardation of Lewis lung carcinoma xenografts in C57BL/6N mice as well as human A2058 melanoma xenografts in NOD/SCID (nonobese diabetic/severe combined immunodeficient) mice. Taken together, our results suggested that AAV-sK15tm produced long-term suppressive effects on cancer growth in vivo and should warrant serious consideration for clinical development.

Lewisy promotes migration of oral cancer cells by glycosylation of epidermal growth factor receptor.

Aberrant glycosylation changes normal cellular functions and represents a specific hallmark of cancer. Lewisy (Ley) carbohydrate upregulation has been reported in a variety of cancers, including oral squamous cell carcinoma (OSCC). A high level of Ley expression is related to poor prognosis of patients with oral cancer. However, it is unclear how Ley mediates oral cancer progression. In this study, the role of Ley in OSCC was explored. Our data showed that Ley was upregulated in HSC-3 and OC-2 OSCC cell lines. Particularly, glycosylation of epidermal growth factor receptor (EGFR) with Ley was found in OC-2 cells, and this modification was absent upon inhibition of Ley synthesis. The absence of Ley glycosylation of EGFR weakened phosphorylation of AKT and ERK in response to epidermal growth factor (EGF). Additionally, EGF-triggered cell migration was reduced, but cell proliferation was not affected. Ley modification stabilized EGFR upon ligand activation. Conversely, absence of Ley glycosylation accelerated EGFR degradation. In summary, these results indicate that increased expression of Ley in OSCC cells is able to promote cell migration by modifying EGFR which in turn stabilizes EGFR expression and downstream signaling. Targeting Ley on EGFR could have a potential therapeutic effect on oral cancer.

Thrombomodulin promotes corneal epithelial wound healing.

PURPOSE: To determine the role of thrombomodulin (TM) in corneal epithelial wound healing, and to investigate whether recombinant TM epidermal growth factor-like domain plus serine/threonine-rich domain (rTMD23) has therapeutic potential in corneal epithelial wound healing. METHODS: TM localization and expression in the murine cornea were examined by immunofluorescence staining. TM expression after injury was also studied. The effect of rTMD23 on corneal wound healing was evaluated by in vitro and in vivo assays. RESULTS: TM was expressed in the cornea in normal adult mice. TM expression increased in the early phase of wound healing and decreased after wound recovery. In the in vitro study, platelet-derived growth factor-BB (PDGF-BB) induced TM expression in murine corneal epithelial cells by mediating E26 transformation-specific sequence-1 (Ets-1) via the mammalian target of rapamycin (mTOR) signaling pathway. The administration of rTMD23 increased the rate of corneal epithelial wound healing. CONCLUSIONS: TM expression in corneal epithelium was modulated during the corneal wound healing process, and may be regulated by PDGF-BB. In addition, rTMD23 has therapeutic potential in corneal injury.

Thrombomodulin promotes diabetic wound healing by regulating toll-like receptor 4 expression.

Keratinocyte-expressed thrombomodulin (TM) and the released soluble TM (sTM) have been demonstrated to promote wound healing. However, the effects of high glucose on TM expression in keratinocytes and the role of TM in diabetic ulcer remain unclear. In this study, we demonstrated that expressions of TM and Toll-like receptor 4 (TLR4) were both downregulated in high-glucose cultured human keratinocytes and in skin keratinocytes of diabetic patients. In addition, the wound-triggered upregulation of TM and sTM production was abolished in both high-glucose cultured human keratinocytes and streptozotocin-induced diabetic mouse skin. Furthermore, supplementation of recombinant sTM could increase TLR4 expression and promote cutaneous wound healing in both high-glucose cultured human keratinocytes and diabetic mice. However, in Tlr4-deleted mice, which exhibited delayed wound healing, the therapeutic benefit of recombinant sTM was abrogated. Moreover, our results showed that tumor necrosis factor-α (TNF-α) expression in keratinocytes was dose-dependently upregulated by glucose, and TNF-α treatment downregulated the expression of TM and TLR4. Taken together, high-glucose environment reduces the expression of TM and TLR4 in keratinocytes possibly through the action of TNF-α, and recombinant sTM can increase the TLR4 expression and promote wound healing under diabetic condition.

Recombinant thrombomodulin inhibits lipopolysaccharide-induced inflammatory response by blocking the functions of CD14.

CD14, a multiligand pattern-recognition receptor, is involved in the activation of many TLRs. Thrombomodulin (TM), a type I transmembrane glycoprotein, originally was identified as an anticoagulant factor that activates protein C. Previously, we showed that the recombinant TM lectin-like domain binds to LPS and inhibits LPS-induced inflammation, but the function of the recombinant epidermal growth factor-like domain plus serine/threonine-rich domain of TM (rTMD23) in LPS-induced inflammation remains unknown. In the current study, we found that rTMD23 markedly suppressed the activation of intracellular signaling pathways and the production of inflammatory cytokines induced by LPS. The anti-inflammatory activity of rTMD23 was independent of activated protein C. We also found that rTMD23 interacted with the soluble and membrane forms of CD14 and inhibited the CD14-mediated inflammatory response. Knockdown of CD14 in macrophages suppressed the production of inflammatory cytokines induced by LPS, and rTMD23 inhibited LPS-induced IL-6 production in CD14-knockdown macrophages. rTMD23 suppressed the binding of LPS to macrophages by blocking the association between monocytic membrane-bound TM and CD14. The administration of rTMD23 in mice, both pretreatment and posttreatment, significantly increased the survival rate and reduced the inflammatory response to LPS. Notably, the serine/threonine-rich domain is essential for the anti-inflammatory activity of rTMD23. To summarize, we show that rTMD23 suppresses the LPS-induced inflammatory response in mice by targeting CD14 and that the serine/threonine-rich domain is crucial for the inhibitory effect of rTMD23 on LPS-induced inflammation.