M2 macrophage-derived exosomes promote angiogenesis and improve cardiac function after myocardial infarction.

BACKGROUND: Myocardial infarction (MI) is a major cause of mortality and morbidity worldwide. The intercellular communication in post-infarction angiogenesis remains unclear. METHODS: In this study, we explored the role and mechanism of action of M2 macrophage-derived exosomes (M2-exos) in angiogenesis after MI. M2-exos were harvested and injected intramyocardially at the onset of MI. Two distinct endothelial cells (ECs) were cultured with M2-exos to explore the direct effects on angiogenesis. RESULTS: We showed that M2-exos improved cardiac function, reduced infarct size, and enhanced angiogenesis after MI. Moreover, M2-exos promoted angiogenesis in vitro; the molecules loaded in the vesicles were responsible for its proangiogenic effects. We further validated that higher abundance of miR-132-3p in M2-exos, which recapitulate their functions, was required for the cardioprotective effects exerted by M2-exos. Mechanistically, miR-132-3p carried by M2-exos down-regulate the expression of THBS1 through direct binding to its 3´UTR and the proangiogenic effects of miR-132-3p were largely reversed by THBS1 overexpression. CONCLUSION: Our findings demonstrate that M2-exos promote angiogenesis after MI by transporting miR-132-3p to ECs, and by binding to THBS1 mRNA directly and negatively regulating its expression. These findings highlight the role of M2-exos in cardiac repair and provide novel mechanistic understanding of intercellular communication in post-infarction angiogenesis.

Interstitial macrophage phenotypes in Schistosoma-induced pulmonary hypertension.

Background: Schistosomiasis is a common cause of pulmonary hypertension (PH) worldwide. Type 2 inflammation contributes to the development of Schistosoma-induced PH. Specifically, interstitial macrophages (IMs) derived from monocytes play a pivotal role by producing thrombospondin-1 (TSP-1), which in turn activates TGF-ß, thereby driving the pathology of PH. Resident and recruited IM subpopulations have recently been identified. We hypothesized that in Schistosoma-PH, one IM subpopulation expresses monocyte recruitment factors, whereas recruited monocytes become a separate IM subpopulation that expresses TSP-1. Methods: Mice were intraperitoneally sensitized and then intravenously challenged with S. mansoni eggs. Flow cytometry on lungs and blood was performed on wildtype and reporter mice to identify IM subpopulations and protein expression. Single-cell RNA sequencing (scRNAseq) was performed on flow-sorted IMs from unexposed and at day 1, 3 and 7 following Schistosoma exposure to complement flow cytometry based IM characterization and identify gene expression. Results: Flow cytometry and scRNAseq both identified 3 IM subpopulations, characterized by CCR2, MHCII, and FOLR2 expression. Following Schistosoma exposure, the CCR2+ IM subpopulation expanded, suggestive of circulating monocyte recruitment. Schistosoma exposure caused increased monocyte-recruitment ligand CCL2 expression in the resident FOLR2+ IM subpopulation. In contrast, the vascular pathology-driving protein TSP-1 was greatest in the CCR2+ IM subpopulation. Conclusion: Schistosoma-induced PH involves crosstalk between IM subpopulations, with increased expression of monocyte recruitment ligands by resident FOLR2+ IMs, and the recruitment of CCR2+ IMs which express TSP-1 that activates TGF-ß and causes PH.

The role of THBS1 and PDGFD in the immune microenvironment of Helicobacter pylori-associated gastric cancer.

BACKGROUND AND STUDY AIMS: Immunotherapy has emerged as a hot topic in cancer treatment in recent years and has also shown potential in the treatment of Helicobacter pylori-associated gastric cancer. However, there is still a need to identify potential immunotherapy targets. MATERIAL AND METHODS: We used the GSE116312 dataset of Helicobacter pylori-associated gastric cancer to identify differentially expressed genes, which were then overlapped with immune genes from the ImmPort database. The identified immune genes were used to classify gastric cancer samples and evaluate the relationship between classification and tumor mutations, as well as immune infiltration. An immune gene-based prognostic model was constructed, and the expression levels of the genes involved in constructing the model were explored in the tumor immune microenvironment. RESULTS: We successfully identified 60 immune genes and classified gastric cancer samples into two subtypes, which showed differences in prognosis, tumor mutations, immune checkpoint expression, and immune cell infiltration. Subsequently, we constructed an immune prognostic model consisting of THBS1 and PDGFD, which showed significant associations with macrophages and fibroblasts. CONCLUSION: We identified abnormal expression of THBS1 and PDGFD in cancer-associated fibroblasts (CAFs) within the tumor immune microenvironment, suggesting their potential as therapeutic targets.

Thrombospondin-1 Regulates Trophoblast Necroptosis via NEDD4-Mediated Ubiquitination of TAK1 in Preeclampsia.

Preeclampsia (PE) is considered as a disease of placental origin. However, the specific mechanism of placental abnormalities remains elusive. This study identified thrombospondin-1 (THBS1) is downregulated in preeclamptic placentae and negatively correlated with blood pressure. Functional studies show that THBS1 knockdown inhibits proliferation, migration, and invasion and increases the cycle arrest and apoptosis rate of HTR8/SVneo cells. Importantly, THBS1 silencing induces necroptosis in HTR8/SVneo cells, accompanied by the release of damage-associated molecular patterns (DAMPs). Necroptosis inhibitors necrostatin-1 and GSK'872 restore the trophoblast survival while pan-caspase inhibitor Z-VAD-FMK has no effect. Mechanistically, the results show that THBS1 interacts with transforming growth factor B-activated kinase 1 (TAK1), which is a central modulator of necroptosis quiescence and affects its stability. Moreover, THBS1 silencing up-regulates the expression of neuronal precursor cell-expressed developmentally down-regulated 4 (NEDD4), which acts as an E3 ligase of TAK1 and catalyzes K48-linked ubiquitination of TAK1 in HTR8/SVneo cells. Besides, THBS1 attenuates PE phenotypes and improves the placental necroptosis in vivo. Taken together, the down-regulation of THBS1 destabilizes TAK1 by activating NEDD4-mediated, K48-linked TAK1 ubiquitination and promotes necroptosis and DAMPs release in trophoblast cells, thus participating in the pathogenesis of PE.

Nattokinase attenuates endothelial inflammation through the activation of SRF and THBS1.

Natto contains a potent fibrinolytic enzyme called nattokinase (NK), which has thrombolytic, antihypertensive, antiatherosclerotic and lipid-lowering effects. Although NK has been recognized for its beneficial effect on humans with atherosclerotic cardiovascular disease (ASCVD), the underlying mechanisms involved in vascular inflammation-atherosclerosis development remain largely unknown. The current study aimed to explore the effects of NK on gene regulation, autophagy, necroptosis and inflammasome in vascular inflammation. The transcriptional profiles of NK in endothelial cells (ECs) by RNA sequencing (RNA-seq) revealed that NK affected THBS1, SRF and SREBF1 mRNA expression. In Q-PCR analysis, SRF and THBS1 were upregulated but SREBF1 was unaffected in ECs treated with NK. NK treatment induced autophagy and inhibited NLRP3 inflammasome and necroptosis in ECs. Furthermore, the inhibition of SRF or THBS1 by siRNA suppressed autophagy and enhanced the NLRP3 inflammasome and necroptosis. In a mouse model, NK reduced vascular inflammation by activating autophagy and inhibiting NLRP3 inflammasome and necroptosis. Our findings provide the first evidence that NK upregulates SRF and THBS1 genes, subsequently increasing autophagy and decreasing necroptosis and NLRP3 inflammasome formation to reduce vascular inflammation. Therefore, NK could serve as nutraceuticals or adjuvant therapies to reduce vascular inflammation and possible atherosclerosis progression.

Thbs1 regulates skeletal muscle mass in a TGFß-Smad2/3-ATF4-dependent manner.

Loss of muscle mass is a feature of chronic illness and aging. Here, we report that skeletal muscle-specific thrombospondin-1 transgenic mice (Thbs1 Tg) have profound muscle atrophy with age-dependent decreases in exercise capacity and premature lethality. Mechanistically, Thbs1 activates transforming growth factor ß (TGFß)-Smad2/3 signaling, which also induces activating transcription factor 4 (ATF4) expression that together modulates the autophagy-lysosomal pathway (ALP) and ubiquitin-proteasome system (UPS) to facilitate muscle atrophy. Indeed, myofiber-specific inhibition of TGFß-receptor signaling represses the induction of ATF4, normalizes ALP and UPS, and partially restores muscle mass in Thbs1 Tg mice. Similarly, myofiber-specific deletion of Smad2 and Smad3 or the Atf4 gene antagonizes Thbs1-induced muscle atrophy. More importantly, Thbs1-/- mice show significantly reduced levels of denervation- and caloric restriction-mediated muscle atrophy, along with blunted TGFß-Smad3-ATF4 signaling. Thus, Thbs1-mediated TGFß-Smad3-ATF4 signaling in skeletal muscle regulates tissue rarefaction, suggesting a target for atrophy-based muscle diseases and sarcopenia with aging.

Thrombospondin 1 enhances systemic inflammation and disease severity in acute-on-chronic liver failure.

BACKGROUND: The key role of thrombospondin 1 (THBS1) in the pathogenesis of acute-on-chronic liver failure (ACLF) is unclear. Here, we present a transcriptome approach to evaluate THBS1 as a potential biomarker in ACLF disease pathogenesis. METHODS: Biobanked peripheral blood mononuclear cells (PBMCs) from 330 subjects with hepatitis B virus (HBV)-related etiologies, including HBV-ACLF, liver cirrhosis (LC), and chronic hepatitis B (CHB), and normal controls (NC) randomly selected from the Chinese Group on the Study of Severe Hepatitis B (COSSH) prospective multicenter cohort underwent transcriptome analyses (ACLF = 20; LC = 10; CHB = 10; NC = 15); the findings were externally validated in participants from COSSH cohort, an ACLF rat model and hepatocyte-specific THBS1 knockout mice. RESULTS: THBS1 was the top significantly differentially expressed gene in the PBMC transcriptome, with the most significant upregulation in ACLF, and quantitative polymerase chain reaction (ACLF = 110; LC = 60; CHB = 60; NC = 45) was used to verify that THBS1 expression corresponded to ACLF disease severity outcome, including inflammation and hepatocellular apoptosis. THBS1 showed good predictive ability for ACLF short-term mortality, with an area under the receiver operating characteristic curve (AUROC) of 0.8438 and 0.7778 at 28 and 90 days, respectively. Enzyme-linked immunosorbent assay validation of the plasma THBS1 using an expanded COSSH cohort subjects (ACLF = 198; LC = 50; CHB = 50; NC = 50) showed significant correlation between THBS1 with ALT and γ-GT (P = 0.01), and offered a similarly good prognostication predictive ability (AUROC = 0.7445 and 0.7175) at 28 and 90 days, respectively. ACLF patients with high-risk short-term mortality were identified based on plasma THBS1 optimal cut-off value (< 28 µg/ml). External validation in ACLF rat serum and livers confirmed the functional association between THBS1, the immune response and hepatocellular apoptosis. Hepatocyte-specific THBS1 knockout improved mouse survival, significantly repressed major inflammatory cytokines, enhanced the expression of several anti-inflammatory mediators and impeded hepatocellular apoptosis. CONCLUSIONS: THBS1 might be an ACLF disease development-related biomarker, promoting inflammatory responses and hepatocellular apoptosis, that could provide clinicians with a new molecular target for improving diagnostic and therapeutic strategies.

THBS1 and THBS2 Enhance the In Vitro Proliferation, Adhesion, Migration and Invasion of Intrahepatic Cholangiocarcinoma Cells.

In intrahepatic cholangiocarcinoma (iCCA), thrombospondin 1 (THBS1) and 2 (THBS2) are soluble mediators released in the tumor microenvironment (TME) that contribute to the metastatic spreading of iCCA cells via a lymphatic network by the trans-differentiation of vascular endothelial cells to a lymphatic-like phenotype. To study the direct role of THBS1 and THBS2 on the iCCA cells, well-established epithelial (HuCCT-1) and mesenchymal (CCLP1) iCCA cell lines were subjected to recombinant human THBS1 and THBS2 (rhTHBS1, rhTHBS2) for cellular function assays. Cell growth, cell adhesion, migration, and invasion were all enhanced in both CCLP1 and HuCCT-1 cells by the treatment with either rhTHBS1 or rhTHBS2, although they showed some variability in their intensity of speeding up cellular processes. rhTHBS2 was more intense in inducing invasiveness and in committing the HuCCT-1 cells to a mesenchymal-like phenotype and was therefore a stronger enhancer of the malignant behavior of iCCA cells compared to rhTHBS1. Our data extend the role of THBS1 and THBS2, which are not only able to hinder the vascular network and promote tumor-associated lymphangiogenesis but also exacerbate the malignant behavior of the iCCA cells.

PP2A Affects Angiogenesis via Its Interaction with a Novel Phosphorylation Site of TSP1.

Alterations in angiogenic properties play a pivotal role in the manifestation and onset of various pathologies, including vascular diseases and cancer. Thrombospondin-1 (TSP1) protein is one of the master regulators of angiogenesis. This study unveils a novel aspect of TSP1 regulation through reversible phosphorylation. The silencing of the B55α regulatory subunit of protein phosphatase 2A (PP2A) in endothelial cells led to a significant decrease in TSP1 expression. Direct interaction between TSP1 and PP2A-B55α was confirmed via various methods. Truncated TSP1 constructs were employed to identify the phosphorylation site and the responsible kinase, ultimately pinpointing PKC as the enzyme phosphorylating TSP1 on Ser93. The biological effects of B55α-TSP1 interaction were also analyzed. B55α silencing not only counteracted the increase in TSP1 expression during wound closure but also prolonged wound closure time. Although B55α silenced cells initiated tube-like structures earlier than control cells, their spheroid formation was disrupted, leading to disintegration. Cells transfected with phosphomimic TSP1 S93D exhibited smaller spheroids and reduced effectiveness in tube formation, revealing insights into the effects of TSP1 phosphorylation on angiogenic properties. In this paper, we introduce a new regulatory mechanism of angiogenesis by reversible phosphorylation on TSP1 S93 by PKC and PP2A B55α.

Scleral remodeling during myopia development in mice eyes: a potential role of thrombospondin-1.

BACKGROUND: Scleral extracellular matrix (ECM) remodeling plays a crucial role in the development of myopia, particularly in ocular axial elongation. Thrombospondin-1 (THBS1), also known as TSP-1, is a significant cellular protein involved in matrix remodeling in various tissues. However, the specific role of THBS1 in myopia development remains unclear. METHOD: We employed the HumanNet database to predict genes related to myopic sclera remodeling, followed by screening and visualization of the predicted genes using bioinformatics tools. To investigate the potential target gene Thbs1, we utilized lens-induced myopia models in male C57BL/6J mice and performed Western blot analysis to detect the expression level of scleral THBS1 during myopia development. Additionally, we evaluated the effects of scleral THBS1 knockdown on myopia development through AAV sub-Tenon's injection. The refractive status and axial length were measured using a refractometer and SD-OCT system. RESULTS: During lens-induced myopia, THBS1 protein expression in the sclera was downregulated, particularly in the early stages of myopia induction. Moreover, the mice in the THBS1 knockdown group exhibited alterations in myopia development in both refraction and axial length changed compared to the control group. Western blotting analysis confirmed the effectiveness of AAV-mediated knockdown, demonstrating a decrease in COLA1 expression and an increase in MMP9 levels in the sclera. CONCLUSION: Our findings indicate that sclera THBS1 levels decreased during myopia development and subsequent THBS1 knockdown showed a decrease in scleral COLA1 expression. Taken together, these results suggest that THBS1 plays a role in maintaining the homeostasis of scleral extracellular matrix, and the reduction of THBS1 may promote the remodeling process and then affect ocular axial elongation during myopia progression.

Determination of vWF, ADAMTS-13 and Thrombospondin-1 in Venous Thromboembolism and Relating Them to the Presence of Factor V Leiden Mutation.

Thrombophilia in venous thromboembolism (VTE) is multifactorial. Von Willebrand factor (vWF) plays a major role in primary hemostasis. While elevated vWF levels are well documented in VTE, findings related to its cleaving protease (ADAMTS-13) are contradicting. The aim of this study was to determine vWF, ADAMTS-13, and the multifactorial Thrombospondin-1 (TSP-1) protein levels in patients after 3-6 months following an unprovoked VTE episode. We also explored a possible association with factor V Leiden (FVL) mutation. vWF, ADAMTS-13 and TSP-1 were analyzed using ELISA kits in 60 VTE patients and 60 controls. Patients had higher levels of vWF antigen (P = .021), vWF collagen-binding activity (P = .008), and TSP-1 protein (P < .001) compared to controls. ADAMTS-13 antigen was lower in patients (P = .046) compared to controls but ADAMTS-13 activity was comparable between the two groups (P = .172). TSP-1 showed positive correlation with vWF antigen (rho = 0.303, P = .021) and negative correlation with ADAMTS-13 activity (rho = -0.244, P = .033) and ADAMTS-13 activity/vWF antigen ratio (rho = -0.348, P = .007). A significant association was found between the presence of FVL mutation and VTE (odds ratio (OR): 9.672 (95% confidence interval (CI) 2.074-45.091- P = .004), but no association was found between the mutation and the studied proteins (P > .05). There appears to be an imbalance between vWF and ADAMTS-13 in VTE patients even after 3-6 months following the onset of VTE. We report that the odds of developing VTE in carriers of FVL mutation are 9.672 times those without the mutation, but the presence of this mutation is not associated with the studied proteins.

Thrombospondin-1 promotes liver fibrosis by enhancing TGF-ß action in hepatic stellate cells.

Insulin resistance in adipose tissue is thought to be a key contributor to the pathogenesis of various metabolic disorders including metabolic dysfunction-associated steatotic liver disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), but the mechanism underlying this contribution to MASLD/MASH has remained unknown. We previously showed that dysregulation of the PDK1-FoxO1 signaling axis in adipocytes plays a role in the development of MASLD/MASH by analysis of adipocyte-specific PDK1 knockout (A-PDK1KO) and adipocyte-specific PDK1/FoxO1 double-knockout (A-PDK1/FoxO1DKO) mice. We here focused on the role of the extracellular matrix protein thrombospondin-1 (TSP-1) as a secreted factor whose expression in adipose tissue is increased in A-PDK1KO mice and normalized in A-PDK1/FoxO1DKO mice. Genetic ablation of TSP-1 markedly ameliorated liver fibrosis in A-PDK1KO mice fed a high-fat diet. With regard to the potential mechanism of this effect, TSP-1 augmented the expression of fibrosis-related genes induced by TGF-ß in LX-2 human hepatic stellate cells. We also showed that TSP-1 expression and secretion were negatively regulated by insulin signaling via the PDK1-FoxO1 axis in cultured adipocytes. Our results thus indicate that TSP-1 plays a key role in the pathogenesis of liver fibrosis in MASH. Regulation of TSP-1 expression by PDK1-FoxO1 axis in adipocytes may provide a basis for targeted therapy of hepatic fibrosis in individuals with MASH.

Pericardial Adipose Tissue Thrombospondin-1 Associates With Antiangiogenesis in Ischemic Heart Disease.

Accumulation of ectopic pericardial adipose tissue has been associated with cardiovascular complications which, in part, may relate to adipose-derived factors that regulate vascular responses and angiogenesis. We sought to characterize adipose tissue microvascular angiogenic capacity in subjects who underwent elective cardiac surgeries including aortic, valvular, and coronary artery bypass grafting. Pericardial adipose tissue was collected intraoperatively and examined for angiogenic capacity. Capillary sprouting was significantly blunted (twofold, p <0.001) in subjects with coronary artery disease (CAD) (age 60 ± 9 years, body mass index [BMI] 32 ± 4 kg/m2, low-density lipoprotein cholesterol [LDL-C] 95 ± 46 mg/100 ml, n = 29) compared with age-, BMI-, and LDL-C matched subjects without angiographic obstructive CAD (age 59 ± 10 y, BMI 35 ± 9 kg/m2, LDL-C 101 ± 40 mg/100 ml, n = 12). For potential mechanistic insight, we performed mRNA expression analyses using quantitative real-time polymerase chain reaction and observed no significant differences in pericardial fat gene expression of proangiogenic mediators vascular endothelial growth factor-A (VEGF-A), fibroblast growth factor-2 (FGF-2), and angiopoietin-1 (angpt1), or anti-angiogenic factors soluble fms-like tyrosine kinase-1 (sFlt-1) and endostatin. In contrast, mRNA expression of anti-angiogenic thrombospondin-1 (TSP-1) was significantly upregulated (twofold, p = 0.008) in CAD compared with non-CAD subjects, which was confirmed by protein western-immunoblot analysis. TSP-1 gene knockdown using short hairpin RNA lentiviral delivery significantly improved angiogenic deficiency in CAD (p <0.05). In conclusion, pericardial fat in subjects with CAD may be associated with an antiangiogenic profile linked to functional defects in vascularization capacity. Local paracrine actions of TSP-1 in adipose depots surrounding the heart may play a role in mechanisms of ischemic heart disease.

Depleted uranium induces thyroid damage through activation of ER stress via the thrombospondin 1-PERK pathway.

Depleted uranium (DU) can cause damage to the body, but its effects on the thyroid are unclear. The purpose of this study was to investigate the DU-induced thyroid damage and its potential mechanism in order to find new targets for detoxification after DU poisoning. A model of acute exposure to DU was constructed in rats. It was observed that DU accumulated in the thyroid, induced thyroid structure disorder and cell apoptosis, and decreased the serum T4 and FT4 levels. Gene screening showed that thrombospondin 1 (TSP-1) was a sensitive gene of DU, and the expression of TSP-1 decreased with the increase of DU exposure dose and time. TSP-1 knockout mice exposed to DU had more severe thyroid damage and lower serum FT4 and T4 levels than wild-type mice. Inhibiting the expression of TSP-1 in FRTL-5 cells aggravated DU-induced apoptosis, while exogenous TSP-1 protein alleviated the decreased viability in FRTL-5 cells caused by DU. It was suggested that DU may caused thyroid damage by down-regulating TSP-1. It was also found that DU increased the expressions of PERK, CHOP, and Caspase-3, and 4-Phenylbutyric (4-PBA) alleviated the DU-induced FRTL-5 cell viability decline and the decrease levels of rat serum FT4 and T4 caused by DU. After DU exposure, the PERK expression was further up-regulated in TSP-1 knockout mice, and the increased expression of PERK was alleviated in TSP-1 over-expressed cells, as well as the increased expression of CHOP and Caspase-3. Further verification showed that inhibition of PERK expression could reduce the DU-induced increased expression of CHOP and Caspase-3. These findings shed light on the mechanism that DU may activate ER stress via the TSP 1-PERK pathway, thereby leading to thyroid damage, and suggest that TSP-1 may be a potential therapeutic target for DU-induced thyroid damage.

CD47 Activation by Thrombospondin-1 in Lymphatic Endothelial Cells Suppresses Lymphangiogenesis and Promotes Atherosclerosis.

BACKGROUND: TSP1 (thrombospondin-1)-a well-known angiogenesis inhibitor-mediates differential effects via interacting with cell surface receptors including CD36 (cluster of differentiation) and CD47. However, the role of TSP1 in regulating lymphangiogenesis is not clear. Our previous study suggested the importance of cell-specific CD47 blockade in limiting atherosclerosis. Further, our experiments revealed CD47 as a dominant TSP1 receptor in lymphatic endothelial cells (LECs). As the lymphatic vasculature is functionally linked to atherosclerosis, we aimed to investigate the effects of LEC TSP1-CD47 signaling inhibition on lymphangiogenesis and atherosclerosis. METHODS: Murine atherosclerotic and nonatherosclerotic arteries were utilized to investigate TSP1 expression using Western blotting and immunostaining. LEC-specific knockout mice were used to determine the in vivo role of LEC Cd47 in lymphangiogenesis and atherosclerosis. Various in vitro cell-based assays, in vivo Matrigel plug implantation, molecular biological techniques, and immunohistological approaches were used to evaluate the underlying signaling mechanisms. RESULTS: Elevated TSP1 expression was observed in mouse atherosclerotic aortic tissue compared with nonatherosclerotic control tissue. TSP1 at pathological concentrations suppressed both in vitro and in vivo lymphangiogenesis. Mechanistically, TSP1 inhibited VEGF (vascular endothelial growth factor)-C-induced AKT and eNOS activation in LEC and attenuated NO (nitric oxide) production. Further, CD47 silencing in LEC prevented the effects of TSP1 on lymphangiogenic AKT-eNOS signaling and lymphangiogenesis. Atheroprone AAV (adeno-associated virus) 8-PCSK9-injected LEC-specific Cd47 knockout mice (Cd47ΔLEC) had reduced atherosclerosis in both aorta and aortic root compared with control mice (Cd47ΔWT). However, no differences in metabolic parameters including body weight, plasma total cholesterol levels, and fasting blood glucose were observed. Additional immunostaining experiments performed on aortic root cross-sections indicated higher lymphatic vessel density in Cd47ΔLEC mice in comparison to controls. CONCLUSIONS: These findings demonstrate that TSP1 inhibits lymphangiogenesis via activation of CD47 in LEC, and loss of LEC Cd47 attenuates atherosclerotic lesion formation. Collectively, these results identify LEC CD47 as a potential therapeutic target in atherosclerosis.

Novel thrombospondin-1 transcript exhibits distinctive expression and activity in thyroid tumorigenesis.

Thrombospondin 1 (TSP1) is known for its cell-specific functions in cancer progression, such as proliferation and migration. It contains 22 exons that may potentially produce several different transcripts. Here, we identified TSP1V as a novel TSP1-splicing variant produced by intron retention (IR) in human thyroid cancer cells and tissues. We observed that TSP1V functionally inhibited tumorigenesis contrary to TSP1 wild-type, as identified in vivo and in vitro. These activities of TSP1V are caused by inhibiting phospho-Smad and phospho-focal adhesion kinase. Reverse transcription polymerase chain reaction and minigene experiments revealed that some phytochemicals/non-steroidal anti-inflammatory drugs enhanced IR. We further found that RNA-binding motif protein 5 (RBM5) suppressed IR induced by sulindac sulfide treatment. Additionally, sulindac sulfide reduced phospho-RBM5 levels in a time-dependent manner. Furthermore, trans-chalcone demethylated TSP1V, thereby preventing methyl-CpG-binding protein 2 binding to TSP1V gene. In addition, TSP1V levels were significantly lower in patients with differentiated thyroid carcinoma than in those with benign thyroid nodule, indicating its potential application as a diagnostic biomarker in tumor progression.

Latexin regulates sex dimorphism in hematopoiesis via gender-specific differential expression of microRNA 98-3p and thrombospondin 1.

Hematopoietic stem cells (HSCs) have the ability to self-renew and differentiate to all blood cell types. HSCs and their differentiated progeny show sex/gender differences. The fundamental mechanisms remain largely unexplored. We previously reported that latexin (Lxn) deletion increased HSC survival and repopulation capacity in female mice. Here, we find no differences in HSC function and hematopoiesis in Lxn knockout (Lxn-/-) male mice under physiologic and myelosuppressive conditions. We further find that Thbs1, a downstream target gene of Lxn in female HSCs, is repressed in male HSCs. Male-specific high expression of microRNA 98-3p (miR98-3p) contributes to Thbs1 suppression in male HSCs, thus abrogating the functional effect of Lxn in male HSCs and hematopoiesis. These findings uncover a regulatory mechanism involving a sex-chromosome-related microRNA and its differential control of Lxn-Thbs1 signaling in hematopoiesis and shed light on the process underlying sex dimorphism in both normal and malignant hematopoiesis.

Baicalin inhibited both the Furin/TGFß1/Smad3/TSP-1 pathway in endothelial cells and the AKT/Ca2+/ROS pathway in platelets to ameliorate inflammatory coagulopathy.

Inflammatory coagulopathy is resulted from endothelial dysfunction and platelet hyperactivation in inflammatory diseases. In this study, the effects of baicalin, an active component of the traditional Chinese medicine Huangqin, on inflammatory coagulopathy were observed both in vivo and in vitro. In LPS-induced rats, baicalin ameliorated coagulation indexes, inhibited platelet hyperactivation and decreased the expression of thrombospondin-1 (TSP-1) in vessels. In cultured endothelial cells, baicalin decreased the expression of TSP-1 and collagen as well as the TNF-α-induced increase in the levels of TSP-1 and ICAM-1. Baicalin could significantly decrease the platelet adhesion on endothelial cells treated with TNF-α. Baicalin also could inhibit the increase of ROS level and the activation of the NLRP3/Caspase-1/GSDMD pathway in TNF-α-induced endothelial cells. Furin was found to be the direct target of baicalin in HUVECs. Knockdown of Furin using siRNA could ameliorate the effects of baicalin on the activation of TGFß1/Smad3 pathway, TSP-1 expression and the adhesion of platelets on TNF-α-treated endothelial cells. At the same time, baicalin inhibited platelet aggregation induced by collagen or combination of collagen and TSP-1 peptide. Collagen-induced Ca2+ mobilization, ROS level increase, AKT1 phosphorylation, platelet degranulation and TSP-1 release could be all inhibited by baicalin. In all, baicalin ameliorated endothelial dysfunction by inhibiting Furin/TGFß1/Smad3/TSP-1 pathway and also ameliorated platelet activation by inhibiting AKT-related pathway. Both the inhibiting effects of baicalin on endothelial dysfunction and platelet activation might contribute to its ameliorating effects on inflammatory coagulopathy.