Protective effect of alizarin on vascular endothelial dysfunction via inhibiting the type 2 diabetes-induced synthesis of THBS1 and activating the AMPK signaling pathway

BACKGROUND

In this study, we investigated the protective effects of alizarin (AZ) on endothelial dysfunction (ED). AZ has inhibition of the type 2 diabetes mellitus (T2DM)-induced synthesis of thrombospondin 1 (THBS1). Adenosine 5'-monophosphate- activated protein kinase (AMPK), particularly AMPKα2 isoform, plays a critical role in maintaining cardiac homeostasis.

PURPOSE

The aim of this study was to investigate the ameliorative effect of AZ on vascular injury caused by T2DM and to reveal the potential mechanism of AZ in high glucose (HG)-stimulated human umbilical vein endothelial cells (HUVECs) and diabetic model rats.

STUDY DESIGN

HUVECs, rats and AMPK-/- transgenic mice were used to investigate the mitigating effects of AZ on vascular endothelial dysfunction caused by T2DM and its in vitro and in vivo molecular mechanisms.

METHODS

In type 2 diabetes mellitus rats and HUVECs, the inhibitory effect of alizarin on THBS1 synthesis was verified by immunohistochemistry (IHC), immunofluorescence (IF) and Western blot (WB) so that increase endothelial nitric oxide synthase (eNOS) content in vitro and in vivo. In addition, we verified protein interactions with immunoprecipitation (IP). To probe the mechanism, we also performed AMPKα2 transfection. AMPK's pivotal role in AZ-mediated prevention against T2DM-induced vascular endothelial dysfunction was tested using AMPKα2-/- mice.

RESULTS

We first demonstrated that THBS1 and AMPK are targets of AZ. In T2DM, THBS1 was robustly induced by high glucose and inhibited by AZ. Furthermore, AZ activates the AMPK signaling pathway, and recoupled eNOS in stressed endothelial cells which plays a protective role in vascular endothelial dysfunction.

CONCLUSIONS

The main finding of this study is that AZ can play a role in different pathways of vascular injury due to T2DM. Mechanistically, alizarin inhibits the increase in THBS1 protein synthesis after high glucose induction and activates AMPKα2, which increases NO release from eNOS, which is essential in the prevention of vascular endothelial dysfunction caused by T2DM.

CD47 blockade reduces ischemia/reperfusion injury in murine heart transplantation and improves donor heart preservation

BACKGROUND

Myocardial ischemia-reperfusion injury (MIRI) is an important cause of early dysfunction and exacerbation of immune rejection in transplanted hearts. The integrin-related protein CD47 exacerbates myocardial ischemia-reperfusion injury by inhibiting the nitric oxide signaling pathway through interaction with thrombospondin-1 (TSP-1). In addition, the preservation quality of the donor hearts is a key determinant of transplant success. Preservation duration beyond four hours is associated with primary graft dysfunction. We hypothesized that blocking the CD47-TSP-1 system would attenuate ischemia-reperfusion injury in the transplanted heart and, thus, improve the preservation of donor hearts.

METHODS

We utilized a syngeneic mouse heart transplant model to assess the effect of CD47 monoclonal antibody (CD47mAb) to treat MIRI. Donor hearts were perfused with CD47mAb or an isotype-matched control immunoglobulin (IgG2a) and were implanted into the abdominal cavity of the recipients after being stored in histidine-tryptophan-ketoglutarate (HTK) solution at 4 °C for 4 h or 8 h.

RESULTS

At both the 4-h and 8-h preservation time points, mice in the experimental group perfused with CD47mAb exhibited prolonged survival in the transplanted heart, reduced inflammatory response and oxidative stress, significantly decreased inflammatory cell infiltration, and fewer apoptosis-related biomarkers.

CONCLUSION

The application of CD47mAb for the blocking of CD47 attenuates MIRI as well as improves the preservation and prognosis of the transplanted heart in a murine heart transplant model.

Extracellular Matrix Remodeling in Atopic Dermatitis Harnesses the Onset of an Asthmatic Phenotype and Is a Potential Contributor to the Atopic March

The development of atopic dermatitis in infancy, and subsequent allergies, such as asthma in later childhood, is known as the atopic march. The mechanism is largely unknown, however the course of disease indicates an inter-epithelial crosstalk, through the onset of inflammation in the skin and progression to other mucosal epithelia. In this study, we investigated if and how skin-lung epithelial crosstalk contributes to the development of the atopic march. First, we emulated inter-epithelial crosstalk through indirect coculture of bioengineered atopic-like skin disease models and three-dimensional bronchial epithelial models triggering an asthma-like phenotype in the latter. A subsequent secretome analysis identified thrombospondin-1, CD44, complement factor C3, fibronectin, and syndecan-4 as potentially relevant skin-derived mediators. Because these mediators are extracellular matrix-related proteins, we then studied the involvement of the extracellular matrix, unveiling distinct proteomic, transcriptomic, and ultrastructural differences in atopic samples. The latter indicated extracellular matrix remodeling triggering the release of the above-mentioned mediators. In vivo mouse data showed that exposure to these mediators dysregulated activated circadian clock genes which are increasingly discussed in the context of atopic diseases and asthma development. Our data point toward the existence of a skin-lung axis that could contribute to the atopic march driven by skin extracellular matrix remodeling.

CGRP sensory neurons promote tissue healing via neutrophils and macrophages

The immune system has a critical role in orchestrating tissue healing. As a result, regenerative strategies that control immune components have proved effective1,2. This is particularly relevant when immune dysregulation that results from conditions such as diabetes or advanced age impairs tissue healing following injury2,3. Nociceptive sensory neurons have a crucial role as immunoregulators and exert both protective and harmful effects depending on the context4-12. However, how neuro-immune interactions affect tissue repair and regeneration following acute injury is unclear. Here we show that ablation of the NaV1.8 nociceptor impairs skin wound repair and muscle regeneration after acute tissue injury. Nociceptor endings grow into injured skin and muscle tissues and signal to immune cells through the neuropeptide calcitonin gene-related peptide (CGRP) during the healing process. CGRP acts via receptor activity-modifying protein 1 (RAMP1) on neutrophils, monocytes and macrophages to inhibit recruitment, accelerate death, enhance efferocytosis and polarize macrophages towards a pro-repair phenotype. The effects of CGRP on neutrophils and macrophages are mediated via thrombospondin-1 release and its subsequent autocrine and/or paracrine effects. In mice without nociceptors and diabetic mice with peripheral neuropathies, delivery of an engineered version of CGRP accelerated wound healing and promoted muscle regeneration. Harnessing neuro-immune interactions has potential to treat non-healing tissues in which dysregulated neuro-immune interactions impair tissue healing.

Stromal thrombospondin 1 suppresses angiogenesis in oral submucous fibrosis

A decline in mucosal vascularity is a histological hallmark of oral submucous fibrosis (OSF), a premalignant disease that is largely induced by betel quid chewing. However, the lack of available models has challenged studies of angiogenesis in OSF. Here, we found that the expression of thrombospondin 1 (THBS1), an endogenous angiostatic protein, was elevated in the stroma of tissues with OSF. Using a fibroblast-attached organoid (FAO) model, the overexpression of THBS1 in OSF was stably recapitulated in vitro. In the FAO model, treatment with arecoline, a major pathogenic component in areca nuts, enhanced the secretion of transforming growth factor (TGF)-β1 by epithelial cells, which then promoted the expression of THBS1 in fibroblasts. Furthermore, human umbilical vein endothelial cells (HUVECs) were incorporated into the FAO to mimic the vascularized component. Overexpression of THBS1 in fibroblasts drastically suppressed the sprouting ability of endothelial cells in vascularized FAOs (vFAOs). Consistently, treatment with arecoline reduced the expression of CD31 in vFAOs, and this effect was attenuated when the endothelial cells were preincubated with neutralizing antibody of CD36, a receptor of THBS1. Finally, in an arecoline-induced rat OSF model, THBS1 inhibition alleviated collagen deposition and the decline in vascularity in vivo. Overall, we exploited an assembled organoid model to study OSF pathogenesis and provide a rationale for targeting THBS1.

TSP-1 increases autophagy level in cartilage by upregulating HSP27 which delays progression of osteoarthritis

This study aimed to determine whether Thrombospondin-1 (TSP-1) can be used as a biomarker to diagnose early osteoarthritis (OA) and whether it has a chondroprotective effect against OA. We examined TSP-1 expression in cartilage, synovial fluid, and serum at different time points after anterior cruciate ligament transection (ACLT) surgery in rats. Subsequently, TSP-1 was overexpressed or silenced to detect its effects on extracellular matrix (ECM) homeostasis, autophagy level, proliferation and apoptosis in chondrocytes. Adenovirus encoding TSP-1 was injected into the knee joints of ACLT rats to test its effect against OA. Combined with proteomic analysis, the molecular mechanism of TSP-1 in cartilage degeneration was explored. Intra-articular injection of an adenovirus carrying the TSP-1 sequence showed chondroprotective effects against OA. Moreover, TSP-1 expression decreases with OA progression and can effectively promote cartilage proliferation, inhibit apoptosis, and helps to sustain the balance between ECM anabolism and catabolism. Overexpression of TSP-1 also can increase autophagy by upregulating Heat Shock Protein 27 (HSP27, hspb1), thereby enhancing its effect as a stimulator of autophagy. TSP-1 is a hopeful strategy for OA treatment.

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.

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.

Relationship between elevated circulating thrombospondin-1 levels and vascular complications in diabetes mellitus

AIMS/INTRODUCTION

Thrombospondin-1 (TSP-1) participates in a series of physiological and pathological processes by binding to various receptors regulating cell proliferation, adhesion and apoptosis. Elevated circulating TSP-1 is linked with diabetic vascular complications (DVC). This study aimed to determine the relationship between circulating TSP-1 levels and DVC.

MATERIALS AND METHODS

A comprehensive search of PubMed, Embase, Web of Science and CNKI databases was carried out. A meta-analysis was carried out to compare circulating TSP-1 levels between diabetes patients without vascular complications (DNVC), diabetes patients with DVC and non-diabetes patients. The correlation between TSP-1 and metabolic parameters was also analyzed. Subgroup analysis was carried out according to complication type, defined as diabetic retinopathy, diabetic nephropathy and diabetic cardiovascular disease (DCVD).

RESULTS

A total of eight studies were included. Compared with non-diabetes patients, diabetic patients, including DNVC and DVC, had significantly higher circulating TSP-1 levels (standardized mean difference [SMD] 2.660, 95% CI 1.17-4.145, P = 0.000). DNVC had significantly higher circulating TSP-1 levels than non-diabetes patients (SMD 3.613, 95% CI 1.607-5.619, P = 0.000). DVC had significantly higher TSP-1 levels than DNVC (SMD 0.568, 95% CI 0.100-1.036, P = 0.017). TSP-1 was significantly positively correlated with fasting plasma glucose (overall Fisher's z = 0.696, 95% CI 0.559-0.833) and HbA1c (overall Fisher's z = 0.849, 95% CI 0.776-0.923).

CONCLUSIONS

Elevated circulating TSP-1 levels are closely related to DVC, especially in diabetic nephropathy and diabetic cardiovascular disease. Circulating TSP-1 detection might be helpful in the timely diagnosis and treatment of DVC.

Thrombospondin 1 and Reelin act through Vldlr to regulate cardiac growth and repair

Adult mammalian cardiomyocytes have minimal cell cycle capacity, which leads to poor regeneration after cardiac injury such as myocardial infarction. Many positive regulators of cardiomyocyte cell cycle and cardioprotective signals have been identified, but extracellular signals that suppress cardiomyocyte proliferation are poorly understood. We profiled receptors enriched in postnatal cardiomyocytes, and found that very-low-density-lipoprotein receptor (Vldlr) inhibits neonatal cardiomyocyte cell cycle. Paradoxically, Reelin, the well-known Vldlr ligand, expressed in cardiac Schwann cells and lymphatic endothelial cells, promotes neonatal cardiomyocyte proliferation. Thrombospondin1 (TSP-1), another ligand of Vldlr highly expressed in adult heart, was then found to inhibit cardiomyocyte proliferation through Vldlr, and may contribute to Vldlr's overall repression on proliferation. Mechanistically, Rac1 and subsequent Yap phosphorylation and nucleus translocation mediate the regulation of the cardiomyocyte cell cycle by TSP-1/Reelin-Vldlr signaling. Importantly, Reln mutant neonatal mice displayed impaired cardiomyocyte proliferation and cardiac regeneration after apical resection, while cardiac-specific Thbs1 deletion and cardiomyocyte-specific Vldlr deletion promote cardiomyocyte proliferation and are cardioprotective after myocardial infarction. Our results identified a novel role of Vldlr in consolidating extracellular signals to regulate cardiomyocyte cell cycle activity and survival, and the overall suppressive TSP-1-Vldlr signal may contribute to the poor cardiac repair capacity of adult mammals.

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.

Thrombospondin-1 promotes liver fibrosis by enhancing TGF-β 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-β 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.

Evaluating von Willebrand factor and ADAMTS13 levels in thalassemia major patients and assessing a possible association with Thrombospondin-1

INTRODUCTION

Alterations in the endothelium and endothelial adhesion proteins such as von Willebrand factor (vWF) play major roles in hypercoagulability in thalassemia. vWF protein release leads to platelet aggregation and thrombi formation at the site of vascular injury. It is then degraded by the proteolytic enzyme ADAMTS13. Thrombospondin-1 is a multifactorial glycoprotein, which was reported to compete with ADAMTS13 for sites of vWF proteolysis. In this study, levels of vWF, ADAMTS13, and TSP-1 proteins were determined in β-thalassemia major patients. A possible association between TSP-1 and vWF and ADAMTS-13 was also evaluated.

METHODS

The study was conducted on 80 β-thalassemia major patients and 80 age and sex matched healthy controls. The 80 patients were sub-divided into two groups; splenectomised and non-splenectomised. vWF, ADAMTS13 and TSP-1 plasma level were measured using ELISA technique.

RESULTS

There was no significant difference in vWF and TSP-1 levels between patients and controls (p > 0.05). However, ADAMTS13 levels and ADAMTS13 activity/vWF antigen ratio were significantly higher in patients compared to controls (p < 0.05). VWF antigen and TSP-1 level were significantly higher in splenectomised patients (p = 0.025 and p < 0.001, respectively). We also observed a significant decrease in ADAMTS13 activity/vWF antigen ratio among splenectomised compared to non- splenectomised patients (p = 0.019). Correlation analysis showed a significant negative correlation between TSP-1 and vWF Collagen Binding Activity (r = -0.394, p = 0.021) and a positive correlation with ADAMTS13 activity/vWF antigen ratio (r = 0.356, p = 0.039) in splenectomised compared to non- splenectomised patients.

CONCLUSION

Our findings highlight the adequacy of patient management protocols for β-TM in Kuwait as patients presented with comparable levels of platelets, vWF and TSP-1 compared to normal controls. The reported increase in ADAMTS13 in patients may be required to maintain normal levels of vWF. Although no active thrombotic episodes were reported at the time of the study, the significant rise in platelets, vWF:Ag and TSP-1 levels in splenectomised patients may indicate a tendency towards hypercoagulability. Monitoring of splenectomised patients is recommended.

Electroacupuncture activates angiogenesis by regulating the PI3K/Pten/Thbs1 signaling pathway to promote the browning of adipose tissue in HFD-induced obese mice

This study investigated the effect of electroacupuncture (EA) on the browning of white adipose tissue (WAT) via angiogenesis and its potential mechanism in obese mice. Four-week-old male C56BL/6 mice were randomly divided into a high-fat diet (HFD) and a normal chow diet (ND) group. After 12 weeks, HFD mice were randomly divided into two groups to receive or not receive EA for 3 weeks. After EA treatment, body weight, adipocyte size, serum glucose (GLU), triacylglycerol (TG), cholesterol (CHO), leptin (Lep), monocyte chemoattractant protein-1 (MCP-1), WAT browning-related genes, angiogenesis-related genes, and the PI3K/Pten/Thbs1 signaling pathway were evaluated. The results indicated that EA significantly reduced body weight, adipocyte size, and serum concentrations of GLU, TG, CHO, Lep and MCP-1 and promoted WAT browning. Angiogenesis and the PI3K/Pten/Thbs1 signaling pathway were all activated by EA intervention. The expression levels were consistent with the results of RNA-seq and confirmed via qRTPCR and WB. Our study showed that EA may activate angiogenesis via the PI3K/Pten/Thbs1 signaling pathway in WAT, thereby promoting the browning and thermogenesis of adipose tissue.

THBS1-Mediated Degradation of Collagen via the PI3K/AKT Pathway Facilitates the Metastasis and Poor Prognosis of OSCC

Oral squamous cell carcinoma (OSCC) is a prevalent form of malignant tumor, characterized by a persistently high incidence and mortality rate. The extracellular matrix (ECM) plays a crucial role in the initiation, progression, and diverse biological behaviors of OSCC, facilitated by mechanisms such as providing structural support, promoting cell migration and invasion, regulating cell morphology, and modulating signal transduction. This study investigated the involvement of ECM-related genes, particularly THBS1, in the prognosis and cellular behavior of OSCC. The analysis of ECM-related gene data from OSCC samples identified 165 differentially expressed genes forming two clusters with distinct prognostic outcomes. Seventeen ECM-related genes showed a significant correlation with survival. Experimental methods were employed to demonstrate the impact of THBS1 on proliferation, migration, invasion, and ECM degradation in OSCC cells. A risk-prediction model utilizing four differentially prognostic genes demonstrated significant predictive value in overall survival. THBS1 exhibited enrichment of the PI3K/AKT pathway, indicating its potential role in modulating OSCC. In conclusion, this study observed and verified that ECM-related genes, particularly THBS1, have the potential to influence the prognosis, biological behavior, and immunotherapy of OSCC. These findings hold significant implications for enhancing survival outcomes and providing guidance for precise treatment of OSCC.

Uncovering pharmacological mechanisms of Phellinus linteus on focal segmental glomeruloscleosis rats through tandem mass tag-based quantitative proteomic analysis, network pharmacology analysis and experimental validation

OBJECTIVE

To explore the underlying molecular mechanism of ().

METHODS

We used a tandem mass tag-based quantitative proteomic method to determine the differentially expressed proteins. Network pharmacology analysis was used to analysis the main components of and construct the compound-target network. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to validate the analyses results.

RESULTS

The expression levels of thrombospondin-1 (TSP-1) and transforming growth factor (TGF)-β1/Smad3 signaling pathway proteins were significantly upregulated in focal segmental glomeruloscleosis (FSGS) rats. The reduced the expression levels of TSP-1 and TGF-β1 signaling pathway proteins. Network pharmacology analysis revealed that protocatechualdehyde was the main active component. Subsequent and experiments validated the results of proteomic and network pharmacology analyses.

CONCLUSIONS

Our results suggested that may inhibit renal sclerosis by inhibiting TSP-1-activated TGF-β1 signaling and may have potential applications in the treatment of FSGS.

Granzyme B Contributes to Choroidal Neovascularization and Age-Related Macular Degeneration Through Proteolysis of Thrombospondin-1

Age-related macular degeneration (AMD) is a leading cause of irreversible central vision loss in the elderly. The pathology of neovascular age-related macular degeneration (nAMD), also known as wet AMD, is associated with an abnormal blood vessel growth in the eye and involves an imbalance of proangiogenic and antiangiogenic factors. Thrombospondin (TSP)-1 and TSP-2 are endogenous matricellular proteins that inhibit angiogenesis. TSP-1 is significantly diminished in eyes with AMD, although the mechanisms involved in its reduction are unknown. Granzyme B (GzmB) is a serine protease with an increased extracellular activity in the outer retina and choroid of human eyes with nAMD-related choroidal neovascularization (CNV). This study investigated whether TSP-1 and TSP-2 are GzmB substrates using in silico and cell-free cleavage assays and explored the relationship between GzmB and TSP-1 in human eyes with nAMD-related CNV and the effect of GzmB on TSP-1 in retinal pigment epithelial culture and an explant choroid sprouting assay (CSA). In this study, TSP-1 and TSP-2 were identified as GzmB substrates. Cell-free cleavage assays substantiated the GzmB proteolysis of TSP-1 and TSP-2 by showing dose-dependent and time-dependent cleavage products. TSP-1 and TSP-2 proteolysis were hindered by the inhibition of GzmB. In the retinal pigment epithelium and choroid of human eyes with CNV, we observed a significant inverse correlation between TSP-1 and GzmB, as indicated by lower TSP-1 and higher GzmB immunoreactivity. In CSA, the vascular sprouting area increased significantly with GzmB treatment and reduced significantly with TSP-1 treatment. Western blot showed significantly reduced expression of TSP-1 in GzmB-treated retinal pigment epithelial cell culture and CSA supernatant compared with that in controls. Together, our findings suggest that the proteolysis of antiangiogenic factors such as TSP-1 by extracellular GzmB might represent a mechanism through which GzmB may contribute to nAMD-related CNV. Future studies are needed to investigate whether pharmacologic inhibition of extracellular GzmB can mitigate nAMD-related CNV by preserving intact TSP-1.

O-fucosylation of thrombospondin type I repeats is dispensable for trafficking thrombospondin 1 to platelet secretory granules

Thrombospondin 1 (THBS1) is a secreted extracellular matrix glycoprotein that regulates a variety of cellular and physiological processes. THBS1's diverse functions are attributed to interactions between the modular domains of THBS1 with an array of proteins found in the extracellular matrix. THBS1's three Thrombospondin type 1 repeats (TSRs) are modified with O-linked glucose-fucose disaccharide and C-mannose. It is unknown whether these modifications impact trafficking and/or function of THBS1 in vivo. The O-fucose is added by Protein O-fucosyltransferase 2 (POFUT2) and is sequentially extended to the disaccharide by β3glucosyltransferase (B3GLCT). The C-mannose is added by one or more of four C-mannosyltransferases. O-fucosylation by POFUT2/B3GLCT in the endoplasmic reticulum has been proposed to play a role in quality control by locking TSR domains into their three-dimensional fold, allowing for proper secretion of many O-fucosylated substrates. Prior studies showed the siRNA knockdown of POFUT2 in HEK293T cells blocked secretion of TSRs 1-3 from THBS1. Here we demonstrated that secretion of THBS1 TSRs 1-3 was not reduced by CRISPR-Cas9-mediated knockout of POFUT2 in HEK293T cells and demonstrated that knockout of Pofut2 or B3glct in mice did not reduce the trafficking of endogenous THBS1 to secretory granules of platelets, a major source of THBS1. Additionally, we demonstrated that all three TSRs from platelet THBS1 were highly C-mannosylated, which has been shown to stabilize TSRs in vitro. Combined, these results suggested that POFUT2 substrates with TSRs that are also modified by C-mannose may be less susceptible to trafficking defects resulting from the loss of the glucose-fucose disaccharide.

Neutrophil extracellular trap formation in anti-neutrophil cytoplasmic antibody-associated and large-vessel vasculitis

Levels of neutrophil extracellular traps (NETs) were measured in plasma of healthy controls (HC, n = 30) and patients with granulomatosis with polyangiitis (GPA, n = 123), microscopic polyangiitis (MPA, n = 61), Takayasu's arteritis (TAK, n = 58), and giant cell arteritis (GCA, n = 68), at times of remission or activity and correlated with levels of the platelet-derived thrombospondin-1 (TSP-1). Levels of NETs were elevated during active disease in patients with GPA (p < 0.0001), MPA (p = 0.0038), TAK (p < 0.0001), and GCA (p < 0.0001), and in remission for GPA, p < 0.0001, MPA, p = 0.005, TAK, p = 0.03, and GCA, p = 0.0009. All cohorts demonstrated impaired NET degradation. Patients with GPA (p = 0.0045) and MPA (p = 0.005) had anti-NET IgG antibodies. Patients with TAK had anti-histone antibodies (p < 0.01), correlating with presence of NETs. Levels of TSP-1 were increased in all patients with vasculitis, and associated with NET formation. NET formation is a common process in vasculitides. Targeting NET formation or degradation could be potential therapeutic approaches for vasculitides.

The Mechanism of miR-21-5p/TSP-1-Mediating Exercise on the Function of Endothelial Progenitor Cells in Aged Rats

(1) Background: The declined function of peripheral circulating endothelial progenitor cells (EPCs) in aging individuals resulted in decreased endothelial cell regeneration and vascular endothelial function. Improving EPCs function in aging individuals plays an important role in preventing cardiovascular diseases. (2) Methods: Thirty aged (18-month-old) male Sprague-Dawley rats were randomly divided into control and exercise groups. An aerobic exercise intervention was performed 5 days/week for 8 weeks. EPCs functions, miR-21-5p, and TSP-1 expressions were detected after the intervention. The senescence rate, proliferation, and migration of EPCs were examined after overexpression of miR-21-5p and inhibition of TSP-1 expression. (3) Results: The senescence rate, proliferation, and migration of EPCs in exercise groups were significantly improved after exercise intervention. The miR-21-5p expression was increased and the TSP-1 mRNA expression was decreased in the EPCs after the intervention. miR-21-5p overexpression can improve EPCs function and inhibit TSP-1 expression but has no effect on senescence rate. Inhibition of TSP-1 expression could improve the function and reduce the senescence rate. (4) Conclusions: Our results indicate that long-term aerobic exercise can improve the functions of EPCs in aging individuals by downregulating TSP-1 expression via miR-21-5p, which reveals the mechanism of exercise in improving cardiovascular function.

Low-dose nifedipine rescues impaired endothelial progenitor cell-mediated angiogenesis in diabetic mice

It is of great clinical significance to develop potential novel strategies to prevent diabetic cardiovascular complications. Endothelial progenitor cell (EPC) dysfunction is a key contributor to diabetic vascular complications. In the present study we evaluated whether low-dose nifedipine could rescue impaired EPC-mediated angiogenesis and prevent cardiovascular complications in diabetic mice. Diabetes was induced in mice by five consecutive injections of streptozotocin (STZ, 60 mg·kg-1·d-1, i.p.). Diabetic mice were treated with low-dose nifedipine (1.5 mg·kg-1·d-1, i.g.) for six weeks. Then, circulating EPCs in the peripheral blood were quantified, and bone marrow-derived EPCs (BM-EPCs) were prepared. We showed that administration of low-dose nifedipine significantly increased circulating EPCs, improved BM-EPCs function, promoted angiogenesis, and reduced the cerebral ischemic injury in diabetic mice. Furthermore, we found that low-dose nifedipine significantly increased endothelial nitric oxide synthase (eNOS) expression and intracellular NO levels, and decreased the levels of intracellular O2.- and thrombospondin-1/2 (TSP-1/2, a potent angiogenesis inhibitor) in BM-EPCs of diabetic mice. In cultured BM-EPCs, co-treatment with nifedipine (0.1, 1 μM) dose-dependently protected against high-glucose-induced impairment of migration, and suppressed high-glucose-induced TSP-1 secretion and superoxide overproduction. In mice with middle cerebral artery occlusion, intravenous injection of diabetic BM-EPCs treated with nifedipine displayed a greater ability to promote local angiogenesis and reduce cerebral ischemic injury compared to injection of diabetic BM-EPCs treated with vehicle, and the donor-derived BM-EPCs homed to the recipient ischemic brain. In conclusion, low-dose nifedipine can enhance EPCs' angiogenic potential and protect against cerebral ischemic injury in diabetic mice. It is implied that chronic treatment with low-dose nifedipine may be a safe and economic manner to prevent ischemic diseases (including stroke) in diabetes.

VR-10 polypeptide interacts with CD36 to induce cell apoptosis and autophagy in choroid-retinal endothelial cells: Identification of VR-10 as putative novel therapeutic agent for choroid neovascularization (CNV) treatment

Choroid neovascularization (CNV) is important adverse pathological changes that contributes to the aggravation of hypoxic-ischemic eye diseases, and our preliminary work evidences that the thrombospondin-1 (TSP-1) synthetic polypeptide VR-10 may be the candidate therapeutic agent for the treatment of CNV, but its detailed effects and molecular mechanisms are not fully delineated. In this study, the CNV models in BN rats were established by using the laser photocoagulation method, which were further subjected to VR-10 peptide treatment. The RNA-seq and bioinformatics analysis suggested that VR-10 peptide significantly altered the expression patterns of genes in the rat ocular tissues, and the changed genes were especially enriched in the CD36-associated signal pathways. Next, by performing the Real-Time qPCR and Western Blot analysis, we expectedly found that VR-10 upregulated the anti-angiogenesis biomarker (PEDF) and downregulated pro-angiogenesis biomarkers (VEGF, HIF-1 and IL-17) in rat tissues. In addition, we evidenced that VR-10 downregulated CDK2, CDK4, CDK6, Cyclin D1 and Cyclin D2 to induce cell cycle arrest, upregulated cleaved Caspase-3, Bax and downregulated Bcl-2 to promote cell apoptosis, and increased LC3B-II/I ratio and facilitate p62 degradation to promote cell autophagy in RF/6A cells, which were all reversed by knocking down CD36. Moreover, VR-10 upregulated PEDF, and decreased the expression levels of VEGF, HIF-1 and IL-17 to block angiogenesis of RF/6A cells in a CD36-dependent manner. Taken together, VR-10 peptide interacts with its receptor CD36 to regulate the biological functions of RF/6A cells, and these data suggest that VR-10 peptide may be the putative therapeutic drug for the treatment of CNV in clinic.

Targeting the CD47/thrombospondin-1 signaling axis regulates immune cell bioenergetics in the tumor microenvironment to potentiate antitumor immune response

BACKGROUND

CD47 is an integral membrane protein that alters adaptive immunosurveillance when bound to the matricellular glycoprotein thrombospondin-1 (TSP1). We examined the impact of the CD47/TSP1 signaling axis on melanoma patient response to anti-PD-1 therapy due to alterations in T cell activation, proliferation, effector function, and bioenergetics.

METHODS

A syngeneic B16 mouse melanoma model was performed to determine if targeting CD47 as monotherapy or in combination with anti-PD-1 impacted tumor burden. Cytotoxic (CD8+) T cells from Pmel-1 transgenic mice were used for T cell activation, cytotoxic T lymphocyte, and cellular bioenergetic assays. Single-cell RNA-sequencing, ELISA, and flow cytometry was performed on peripheral blood mononuclear cells and plasma of melanoma patients receiving anti-PD-1 therapy to examine CD47/TSP1 expression.

RESULTS

Human malignant melanoma tissue had increased CD47 and TSP1 expression within the tumor microenvironment compared with benign tissue. Due to the negative implications CD47/TSP1 can have on antitumor immune responses, we targeted CD47 in a melanoma model and observed a decrease in tumor burden due to increased tumor oxygen saturation and granzyme B secreting CD8+ T cells compared with wild-type tumors. Additionally, Pmel-1 CD8+ T cells exposed to TSP1 had reduced activation, proliferation, and effector function against B16 melanoma cells. Targeting CD47 allowed CD8+ T cells to overcome this TSP1 interaction to sustain these functions. TSP1 exposed CD8+ T cells have a decreased rate of glycolysis; however, targeting CD47 restored glycolysis when CD8+ T cells were exposed to TSP1, suggesting CD47 mediated metabolic reprogramming of T cells. Additionally, non-responding patients to anti-PD-1 therapy had increased T cells expressing CD47 and circulating levels of TSP1 compared with responding patients. Since CD47/TSP1 signaling axis negatively impacts CD8+ T cells and non-responding patients to anti-PD-1 therapy have increased CD47/TSP1 expression, we targeted CD47 in combination with anti-PD-1 in a melanoma model. Targeting CD47 in combination with anti-PD-1 treatment further decreased tumor burden compared with monotherapy and control.

CONCLUSION

CD47/TSP1 expression could serve as a marker to predict patient response to immune checkpoint blockade treatment, and targeting this pathway may preserve T cell activation, proliferation, effector function, and bioenergetics to reduce tumor burden as a monotherapy or in combination with anti-PD-1.

Thrombospondin 1 and Nuclear Factor Kappa B Signaling Pathways in Non-alcoholic Fatty Liver Disease

AIM

We aimed to evaluate the circulating thrombospondin-1 (TSP-1) and nuclear factor kappa B (NF-κB) in nonalcoholic fatty liver disease (NAFLD) in order to integrate these signaling pathways in the inflammatory and fibrogenic processes of this liver disorder.

METHODS

Ninety-five NAFLD patients were recruited in the study. The study also included 83 age-sex matched healthy controls.

RESULTS

The number of patients with metabolic syndrome (MetS) criteria was 57 (60%). TSP-1 level was found to be statistically significantly lower in the NAFLD group compared to the control group (p=0.037). However, NF-κB level was found to be significantly higher in the NAFLD group compared to the control group (p=0.004). There was a significant negative correlation between plasma TSP-1 levels with glucose (r=-0.235, p=0.022), alanine aminotransferase (r=-0.261, p=0.011) and aspartate transaminase (r=-0.328, p=0.001) levels. In addition, a significant negative correlation was found between plasma TSP-1 and NF-κB levels (r=-0.729, p<0.001).

CONCLUSIONS

Our results suggest a close relationship between increased NF-κB and reduced TSP-1 in NAFLD. TSP-1 and NF-κB signaling pathways might have a role in the inflammatory and fibrogenic processes. Furthermore, they may be used as a noninvasive marker and could assist as a therapeutic target for NAFLD.

A biocompatible nanoparticle-based approach to inhibiting renal ischemia reperfusion injury in mice by blocking thrombospondin-1 activity

Thrombospondin-1 (TSP-1) is a key mediator of renal ischemia-reperfusion injury (IRI), a major cause of kidney dysfunction under various disease conditions and a risk factor of renal allograft rejection. In this study, we developed a nanotechnology-based therapy targeting TSP-1 to prevent renal IRI. A biocompatible nanoparticle (NP) capable of specific binding to TSP-1 was prepared by conjugating NPs with TSP-1-binding (LSKL) peptides. LSKL/NPs not only effectively adsorbed recombinant TSP-1 proteins in vitro, but also efficiently neutralized TSP-1 in mice undergoing renal IRI. IRI-induced elevation of TSP-1 in the kidney was significantly inhibited by post-IR treatment with LSKL/NPs, but not free LSKL or NPs. Furthermore, TSP-1 proteins adsorbed on LSKL/NPs were functionally inactive and unable to induce apoptosis in renal tubular epithelial cells. Importantly, LSKL/NPs induced strong protection against renal IRI, as shown by markedly diminished serum creatinine levels and improved histological lesions of the kidney. Thus, LSKL/NPs provide a useful means of depleting and inactivating TSP-1 and a potential therapy for renal IRI.

The matricellular protein thrombospondin-1 in lung inflammation and injury

Matricellular proteins comprise a diverse group of molecular entities secreted into the extracellular space. They interact with the extracellular matrix (ECM), integrins, and other cell-surface receptors, and can alter matrix strength, cell attachment to the matrix, and cell-cell adhesion. A founding member of this group is thrombospondin-1 (TSP-1), a high molecular-mass homotrimeric glycoprotein. Given the importance of the matrix and ECM remodeling in the lung following injury, TSP-1 has been implicated in a number of lung pathologies. This review examines the role of TSP-1 as a damage controller in the context of lung inflammation, injury resolution, and repair in noninfectious and infectious models. This review also discusses the potential role of TSP-1 in human diseases as it relates to lung inflammation and injury.

[Apoptosis of Megakaryocytic Leukemia Cell Line Meg-01 Induced by TSP-1 Via CD36/Caspase-3]

OBJECTIVE

To investigate the effect of thrombospondin-1 (TSP-1) on apoptosis of human megakaryocytic leukemia cell line Meg-01 and its possible mechanism.

METHODS

The expression of CD36 antigen in Meg-01 cells was detected by flow cytometry and immunocytochemistry. Meg-01 cells were cultured for 48 hours with TSP-1 and CD36 antibody FA6-152 at different concentrations. The early apoptosis and activity of caspase-3 were detected by flow cytometry. The effect of TSP-1 on the growth and differentiation of megakaryocytes was investigated by cell counting and CFU-MK culture.

RESULTS

The flow cytometry and immunocytochemistry showed that CD36 antigen was expressed on the surface of Meg-01 cells. TSP-1 (5 μg/ml) inhibited the growth of Meg-01 cells, but had unobvious effect on M-07e cells. After addition of CD36 antibody FA6-152 (5, 10, and 25 μg/ml), the inhibition effect of TSP-1 was significantly reduced. TSP-1 (2.5, 5, and 7.5 μg/ml) increased the positive expression of Annexin V (P<0.01) and caspase-3 activity (P<0.01), which indicated that TSP-1 had a significant effect on inducing apoptosis. After addition of CD36 antibody FA6-152 (25 μg/ml), the apoptosis induced by TSP-1 in Meg-01 cells was significantly reduced. TSP-1 (5, 10, and 25 μg/ml) could significantly inhibit the formation of CFU-MK in mouse bone marrow cells, while β-TG could not. CD36 antibody FA6-152 (25 μg/ml) could significantly reduce the inhibition of TSP-1 on CFU-MK.

CONCLUSION

TSP-1 may induce apoptosis of megakaryocytic leukemia cell line Meg-01 cells via CD36/caspase-3, which provides a potential new drug development and treatment target for clinical treatment of megakaryocytic leukemia.

Fasciola hepatica Fatty Acid Binding Protein 1 Modulates T cell Polarization by Promoting Dendritic Cell Thrombospondin-1 Secretion Without Affecting Metabolic Homeostasis in Obese Mice

Background

The parasitic trematode Fasciola hepatica evades host immune defenses through secretion of various immunomodulatory molecules. Fatty Acid Binding Proteins (fhFABPs) are among the main excreted/secreted proteins and have been shown to display anti-inflammatory properties. However, little is currently known regarding their impact on dendritic cells (DCs) and their subsequent capacity to prime specific CD4+ T cell subsets.

Methodology/Principal Findings

The immunomodulatory effects of both native F. hepatica extracts and recombinant fhFABPs were assessed on monocyte-derived human DCs (moDCs) and the underlying mechanism was next investigated using various approaches, including DC-allogenic T cell co-culture and DC phenotyping through transcriptomic, proteomic and FACS analyses. We mainly showed that fhFABP1 induced a tolerogenic-like phenotype in LPS-stimulated moDCs characterized by a dose-dependent increase in the cell-surface tolerogenic marker CD103 and IL-10 secretion, while DC co-stimulatory markers were not affected. A significant decrease in secretion of the pro-inflammatory cytokines IL-12p70 and IL-6 was also observed. In addition, these effects were associated with an increase in both Th2-on-Th1 ratio and IL-10 secretion by CD4+ T cells following DC-T cell co-culture. RNA sequencing and targeted proteomic analyses identified thrombospondin-1 (TSP-1) as a non-canonical factor highly expressed and secreted by fhFABP1-primed moDCs. The effect of fhFABP1 on T cell skewing was abolished when using a TSP-1 blocking antibody during DC-T cell co-culture. Immunomodulation by helminth molecules has been linked to improved metabolic homeostasis during obesity. Although fhFABP1 injection in high-fat diet-fed obese mice induced a potent Th2 immune response in adipose tissue, it did not improved insulin sensitivity or glucose homeostasis.

Conclusions/Significance

We show that fhFABP1 modulates T cell polarization, notably by promoting DC TSP-1 secretion in vitro, without affecting metabolic homeostasis in a mouse model of type 2 diabetes.

CD47 Binding on Vascular Endothelial Cells Inhibits IL-17-Mediated Leukocyte Adhesion

To address the conflicting role of thrombospondin (TSP)-1 reported in acute and chronic pathologies, this study investigated the role of TSP-1 in regulating leukocyte recruitment and regulation of VCAM-1 expression using mouse models of uveitis. The spontaneously increased VCAM-1 expression and leukocyte adhesion in retinas of TSP-1-deficient mice suggested a TSP-1-mediated regulation of VCAM-1 expression. In a chronic uveitis model, induced by immunizing wild-type mice with specific interphotoreceptor retinoid-binding protein (IRBP) peptide, topically applied TSP-1-derived CD47-binding peptide significantly reduced the clinical disease course and retinal leukocyte adhesion as compared to the control peptide-treated group. In contrast, in LPS-mediated acute uveitis, TSP-1 deficiency significantly reduced the retinal leukocyte adhesion. The results of our in vitro study, using vascular endothelial cell (EC) cultures, demonstrate that unlike TNF-α, VCAM-1 expression induced by IL-17 is associated with a reduced expression of endogenous TSP-1. Such reduced endogenous TSP-1 expression in IL-17-stimulated ECs helps limit the CD36-mediated increased VCAM-1 expression, while favoring CD47-mediated inhibition of VCAM-1 expression and leukocyte adhesion. Thus, our study identifies TSP-1:CD47 interaction as a molecular pathway that modulates IL-17-mediated VCAM-1 expression, contributing to its anti-inflammatory effect in chronic inflammatory conditions.

Transforming growth factor-β1/Thrombospondin-1/CD47 axis mediates dysfunction in CD34+ cells derived from diabetic older adults

Aging with diabetes is associated with impaired vasoprotective functions and decreased nitric oxide (NO) generation in CD34+ cells. Transforming growth factor- β1 (TGF-β1) is known to regulate hematopoietic functions. This study tested the hypothesis that transforming growth factor- β1 (TGF-β1) is upregulated in diabetic CD34+ cells and impairs NO generation via thrombospondin-1 (TSP-1)/CD47/NO pathway. CD34+ cells from nondiabetic (ND) (n=58) or diabetic older adults (DB) (both type 1 and type 2) (n=62) were isolated from peripheral blood. TGF-β1 was silenced by using an antisense delivered as phosphorodiamidate morpholino oligomer (PMO-TGF-β1). Migration and proliferation in response to stromal-derived factor-1α (SDF-1α) were evaluated. NO generation and eNOS phosphorylation were determined by flow cytometry. CD34+ cells from older, but not younger, diabetics have higher expression of TGF-β1 compared to that observed in cells derived from healthy individuals (P<0.05, n=14). TSP-1 expression was higher (n=11) in DB compared to ND cells. TGFβ1-PMO decreased the secretion of TGF-β1, which was accompanied with decreased TSP-1 expression. Impaired proliferation, migration and NO generation in response to SDF-1α in DB cells were reversed by TGF-β1-PMO (n=6). TSP-1 inhibited migration and proliferation of nondiabetic CD34+ cells that was reversed by CD47-siRNA, which also restored these responses in diabetic CD34+ cells. TSP-1 opposed SDF-1α-induced eNOS phosphorylation at Ser1177 that was reversed by CD47-siRNA. These results infer that increased TGF-β1 expression in CD34+ cells induces dysfunction in CD34+ cells from diabetic older adults via TSP-1/CD47-dependent inhibition of NO generation.

Hypoxia Inhibits Subretinal Inflammation Resolution Thrombospondin-1 Dependently

Hypoxia is potentially one of the essential triggers in the pathogenesis of wet age-related macular degeneration (wetAMD), characterized by choroidal neovascularization (CNV) which is driven by the accumulation of subretinal mononuclear phagocytes (MP) that include monocyte-derived cells. Here we show that systemic hypoxia (10% O2) increased subretinal MP infiltration and inhibited inflammation resolution after laser-induced subretinal injury in vivo. Accordingly, hypoxic (2% O2) human monocytes (Mo) resisted elimination by RPE cells in co-culture. In Mos from hypoxic mice, Thrombospondin 1 mRNA (Thbs1) was most downregulated compared to normoxic animals and hypoxia repressed Thbs-1 expression in human monocytes in vitro. Hypoxic ambient air inhibited MP clearance during the resolution phase of laser-injury in wildtype animals, but had no effect on the exaggerated subretinal MP infiltration observed in normoxic Thbs1-/--mice. Recombinant Thrombospondin 1 protein (TSP-1) completely reversed the pathogenic effect of hypoxia in Thbs1-/--mice, and accelerated inflammation resolution and inhibited CNV in wildtype mice. Together, our results demonstrate that systemic hypoxia disturbs TSP-1-dependent subretinal immune suppression and promotes pathogenic subretinal inflammation and can be therapeutically countered by local recombinant TSP-1.

Fatty Acids, CD36, Thrombospondin-1, and CD47 in Glioblastoma: Together and/or Separately?

Glioblastoma (GBM) is one of the most aggressive tumors of the central nervous system, characterized by a wide range of inter- and intratumor heterogeneity. Accumulation of fatty acids (FA) metabolites was associated with a low survival rate in high-grade glioma patients. The diversity of brain lipids, especially polyunsaturated fatty acids (PUFAs), is greater than in all other organs and several classes of proteins, such as FA transport proteins (FATPs), and FA translocases are considered principal candidates for PUFAs transport through BBB and delivery of PUFAs to brain cells. Among these, the CD36 FA translocase promotes long-chain FA uptake as well as oxidated lipoproteins. Moreover, CD36 binds and recognizes thrombospondin-1 (TSP-1), an extracellular matrix protein that was shown to play a multifaceted role in cancer as part of the tumor microenvironment. Effects on tumor cells are mediated by TSP-1 through the interaction with CD36 as well as CD47, a member of the immunoglobulin superfamily. TSP-1/CD47 interactions have an important role in the modulation of glioma cell invasion and angiogenesis in GBM. Separately, FA, the two membrane receptors CD36, CD47, and their joint ligand TSP-1 all play a part in GBM pathogenesis. The last research has put in light their interconnection/interrelationship in order to exert a cumulative effect in the modulation of the GBM molecular network.

Thrombospondin-1 expression and modulation of Wnt and hippo signaling pathways during the early phase of Trypanosoma cruzi infection of heart endothelial cells

The protozoan parasite, Trypanosoma cruzi, causes severe morbidity and mortality in afflicted individuals. Approximately 30% of T. cruzi infected individuals present with cardiac pathology. The invasive forms of the parasite are carried in the vascular system to infect other cells of the body. During transportation, the molecular mechanisms by which the parasite signals and interact with host endothelial cells (EC) especially heart endothelium is currently unknown. The parasite increases host thrombospondin-1 (TSP1) expression and activates the Wnt/β-catenin and hippo signaling pathways during the early phase of infection. The links between TSP1 and activation of the signaling pathways and their impact on parasite infectivity during the early phase of infection remain unknown. To elucidate the significance of TSP1 function in YAP/β-catenin colocalization and how they impact parasite infectivity during the early phase of infection, we challenged mouse heart endothelial cells (MHEC) from wild type (WT) and TSP1 knockout mice with T. cruzi and evaluated Wnt signaling, YAP/β-catenin crosstalk, and how they affect parasite infection. We found that in the absence of TSP1, the parasite induced the expression of Wnt-5a to a maximum at 2 h (1.73±0.13), P< 0.001 and enhanced the level of phosphorylated glycogen synthase kinase 3β at the same time point (2.99±0.24), P<0.001. In WT MHEC, the levels of Wnt-5a were toned down and the level of p-GSK-3β was lowest at 2 h (0.47±0.06), P< 0.01 compared to uninfected control. This was accompanied by a continuous significant increase in the nuclear colocalization of β-catenin/YAP in TSP1 KO MHEC with a maximum Pearson correlation coefficient of (0.67±0.02), P< 0.05 at 6 h. In WT MHEC, the nuclear colocalization of β-catenin/YAP remained steady and showed a reduction at 6 h (0.29±0.007), P< 0.05. These results indicate that TSP1 plays an important role in regulating β-catenin/YAP colocalization during the early phase of T. cruzi infection. Importantly, dysregulation of this crosstalk by pre-incubation of WT MHEC with a β-catenin inhibitor, endo-IWR 1, dramatically reduced the level of infection of WT MHEC. Parasite infectivity of inhibitor treated WT MHEC was similar to the level of infection of TSP1 KO MHEC. These results indicate that the β-catenin pathway induced by the parasite and regulated by TSP1 during the early phase of T. cruzi infection is an important potential therapeutic target, which can be explored for the prophylactic prevention of T. cruzi infection.

Curcumin improves angiogenesis in the heart of aged rats: Involvement of TSP1/NF-κB/VEGF-A signaling

BACKGROUND

Cardiac aging is an irreversible process that is determined by a number of slowly deleterious changes in morphological and physiological properties of the heart. We investigated the effects of curcumin on cardiac angiogenesis, in old male rats.

MATERIALS AND METHODS

Rats randomly divided into young, age (rats of 26-28 months of age) and curcumin-age (rats of 26-28 months of age treatment with curcumin 50mg/kg). Finally, the expression of VEGF, NF-κB, and TSP-1 were assessed by ELISA in cardiac tissue. Also, angiogenesis was determined by immunostaining for PECAM-1/CD31 and apoptosis was evaluated by TUNEL.

RESULTS

After 2 months, curcumin-age had significantly higher cardiac VEGF-A and NF-κB and lower cardiac TSP-1 expression levels in comparison with age and young. A significant increase in levels of NF-κB and TSP-1 were observed in the age group.

CONCLUSION

Results suggest that curcumin through regulation of cardiogenic mediators and improving cardiac angiogenesis can promote heart performance in the senescent rats.

Role of Thrombospondin‑1 in sepsis‑induced myocardial injury

Sepsis often causes myocardial injury with a high mortality. The aim of the present study was to investigate the effects of thrombospondin‑1 (THBS1) on myocardial cell injury, oxi‑dative stress and apoptosis in sepsis. The expression of THBS1 mRNA in lipopolysaccharide (LPS)‑induced mouse primary cardiomyocytes was detected by reverse transcription‑quantitative PCR (RT‑qPCR). A eukaryotic small interfering (si)RNA expression vector was constructed and transfected into myocardial cells to knockdown THBS1 mRNA expression, which was confirmed by RT‑qPCR. Four in vitro experimental groups were used: i) Control, ii) LPS, iii) THBS1 siRNA (siTHBS1) and iv) siTHBS + LPS. ELISA was used to detect cardiac troponin I (cTnI), pro‑brain natriuretic peptide (proBNP), reactive oxygen species (ROS), caspase‑3, IL‑6 and TNF‑α. In vivo mouse sepsis models were also established, and H&E, TUNEL and caspase‑3 staining were used to evaluate myocardial cell injury and apoptosis. Clinical samples were collected to analyze the serum THBS1 levels and to associate this with the prognosis of patients with sepsis‑induced myocardial injury. The expression level of THBS1 mRNA in myocardial cells induced by LPS was increased, and the serum THBS1 level in patients with myocardial injury in sepsis was also significantly increased compared with patients without sepsis‑induced myocardial injury. In the siTHBS1‑treated mice with myocardial injury, the levels of cTnI and proBNP were significantly decreased, the levels of the inflammatory cytokines IL‑6 and TNF‑α were significantly decreased, ROS were significantly decreased, caspase‑3 was significantly decreased, and myocardial cell apoptosis was also reduced, compared with the LPS group. Data from the present study suggested that THBS1 may be closely related to the biological behavior of myocardial cells and may be a therapeutic target for myocardial injury in sepsis.

Dual Role of Thrombospondin-1 in Flow-Induced Remodeling

(1) Background: Chronic increases in blood flow, as in cardiovascular diseases, induce outward arterial remodeling. Thrombospondin-1 (TSP-1) is known to interact with matrix proteins and immune cell-surface receptors, but its contribution to flow-mediated remodeling in the microcirculation remains unknown. (2) Methods: Mesenteric arteries were ligated in vivo to generate high- (HF) and normal-flow (NF) arteries in wild-type (WT) and TSP-1-deleted mice (TSP-1-/-). After 7 days, arteries were isolated and studied ex vivo. (3) Results: Chronic increases in blood flow induced outward remodeling in WT mice (increasing diameter from 221 ± 10 to 280 ± 10 µm with 75 mmHg intraluminal pressure) without significant effect in TSP-1-/- (296 ± 18 to 303 ± 14 µm), neutropenic or adoptive bone marrow transfer mice. Four days after ligature, pro inflammatory gene expression levels (CD68, Cox2, Gp91phox, p47phox and p22phox) increased in WT HF arteries but not in TSP-1-/- mice. Perivascular neutrophil accumulation at day 4 was significantly lower in TSP-1-/- than in WT mice. (4) Conclusions: TSP-1 origin is important; indeed, circulating TSP-1 participates in vasodilation, whereas both circulating and tissue TSP-1 are involved in arterial wall thickness and diameter expansion.

Potential of thrombospondin-1 in treatment of polycystic ovary syndrome rat model: a preliminary study

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a common gynecological endocrine disease in reproductive women, and the endocrine levels are also affected by diseases. The aim of this study was to determine the effect of thrombospondin-1 (TSP-1) on PCOS rat model.

METHODS

We established the PCOS rat model, the serum hormones including TSP-1 expression were determined and morphological characteristics were investigated to evaluate the model. These above endocrine and morphological features were investigated again to evaluate the effect of TSP-1 treatment.

RESULTS

In the PCOS model group, the serum hormones change (higher luteinizing hormone, testosterone and estrogen) and decreased TSP-1 expression levels were found compared with the control group. Besides, the morphological characteristics of PCOS were also observed in the model group. After TSP-1 treatment, the higher TSP-1, ANGPT2, PDGFB and PDGFD expression levels, the lower LH and T levels, decreased vessel density as well as VEGFA and ANGPT1 expression levels were found compared with the control group, and the ovary morphological changes were also observed in the TSP-1 experimental group.

CONCLUSIONS

TSP-1 delivery system might be an alternative therapy for PCOS treatment.

miR-19a-3p Promotes Tumor-Relevant Behaviors in Bladder Urothelial Carcinoma via Targeting THBS1

OBJECTIVE

miR-19a-3p is widely increased in several cancers and can be used as an oncogenic factor in these cancers. However, the molecular mechanism of miR-19a-3p in bladder urothelial carcinoma (BLCA) is still open. So, the study was aimed at exploring the mechanism of miR-19a-3p in BLCA cells.

METHODS

Bioinformatics analysis was employed to find the differential miRNAs and mRNAs, and the target miRNA and mRNA were determined. Real-time quantitative PCR was used to evaluate miR-19a-3p and THBS1 levels in human urethral epithelial cells and BLCA cells. Western blot was carried out to assay protein expression of THBS1 in human urethral epithelial cells and BLCA cells. Behaviors of BLCA cells were detected through cellular functional assays. Dual-luciferase gene assay was conducted to validate the binding of miR-19a-3p and THBS1.

RESULTS

miR-19a-3p was increased in BLCA cells, while THBS1 was less expressed in BLCA cells. The miR-19a-3p functions as an oncogene in BLCA. THBS1 was a target of miR-19a-3p, and it could reverse the promotion of miR-19a-3p on cell malignant behaviors in BLCA.

CONCLUSION

miR-19a-3p facilitates cell progression in BLCA via binding THBS1, which may be an underlying therapeutic target for BLCA treatment.

Apatinib inhibits glioma cell malignancy in patient-derived orthotopic xenograft mouse model by targeting thrombospondin 1/myosin heavy chain 9 axis

We determined the antitumor mechanism of apatinib in glioma using a patient-derived orthotopic xenograft (PDOX) glioma mouse model and glioblastoma (GBM) cell lines. The PDOX mouse model was established using tumor tissues from two glioma patients via single-cell injections. Sixteen mice were successfully modeled and randomly divided into two equal groups (n = 8/group): apatinib and normal control. Survival analysis and in vivo imaging was performed to determine the effect of apatinib on glioma proliferation in vivo. Candidate genes in GBM cells that may be affected by apatinib treatment were screened using RNA-sequencing coupled with quantitative mass spectrometry, data mining of The Cancer Genome Atlas, and Chinese Glioma Genome Atlas databases, and immunohistochemistry analysis of clinical high-grade glioma pathology samples. Quantitative reverse transcription-polymerase chain reaction (qPCR), western blotting, and co-immunoprecipitation (co-IP) were performed to assess gene expression and the apatinib-mediated effect on glioma cell malignancy. Apatinib inhibited the proliferation and malignancy of glioma cells in vivo and in vitro. Thrombospondin 1 (THBS1) was identified as a potential target of apatinib that lead to inhibited glioma cell proliferation. Apatinib-mediated THBS1 downregulation in glioma cells was confirmed by qPCR and western blotting. Co-IP and mass spectrometry analysis revealed that THBS1 could interact with myosin heavy chain 9 (MYH9) in glioma cells. Simultaneous THBS1 overexpression and MYH9 knockdown suppressed glioma cell invasion and migration. These data suggest that apatinib targets THBS1 in glioma cells, potentially via MYH9, to inhibit glioma cell malignancy and may provide novel targets for glioma therapy.

Lysyl hydroxylase 1 (LH1) deficiency promotes angiotensin II (Ang II)-induced dissecting abdominal aortic aneurysm

Rationale: The progressive disruption of extracellular matrix (ECM) proteins, particularly early elastin fragmentation followed by abnormalities in collagen fibril organization, are key pathological processes that contribute to dissecting abdominal aortic aneurysm (AAA) pathogenesis. Lysyl hydroxylase 1 (LH1) is essential for type I/III collagen intermolecular crosslinking and stabilization. However, its function in dissecting AAA has not been explored. Here, we investigated whether LH1 is significantly implicated in dissecting AAA progression and therapeutic intervention. Methods and Results: Sixteen-week-old male LH1-deficient and wild-type (WT) mice on the C57Bl/6NCrl background were infused with angiotensin II (Ang II, 1000 ng/kg per minute) via subcutaneously implanted osmotic pumps for 4 weeks. Ang II increased LH1 levels in the abdominal aortas of WT mice, whereas mice lacking LH1 developed dissecting AAA. To evaluate the related mechanism, we performed whole-transcriptomic analysis, which demonstrated that LH1 deficiency aggravated gene transcription alterations; in particular, the expression of thrombospondin-1 was markedly upregulated in the aortas of LH1-deficient mice. Furthermore, targeting thrombospondin-1 with TAX2 strongly inhibited the proinflammatory process, matrix metalloproteinase (MMP) activity and vascular smooth muscle cells (VSMCs) apoptosis, ultimately decreasing the incidence of dissecting AAA. Restoration of LH1 protein expression in LH1-deficient mice by intraperitoneal injection of an adeno-associated virus normalized thrombospondin-1 levels, subsequently alleviating dissecting AAA formation and preserving aortic structure and function. Consistently, in human AAA specimens, decreased LH1 expression was associated with increased thrombospondin-1 levels. Conclusions: LH1 deficiency contributes to dissecting AAA pathogenesis, at least in part, by upregulating thrombospondin-1 expression, which subsequently enables proinflammatory processes, MMP activation and VSMCs apoptosis. Our study provides evidence that LH1 is a potential critical therapeutic target for AAA.

The Impact of Lower Limb Immobilization and Rehabilitation on Angiogenic Proteins and Capillarization in Skeletal Muscle

PURPOSE

Skeletal muscle vascularization is important for tissue regeneration after injury and immobilization. We examined whether complete immobilization influences capillarization and oxygen delivery to the muscle and assessed the efficacy of rehabilitation by aerobic exercise training.

METHODS

Young healthy males had one leg immobilized for 14 d and subsequently completed 4 wk of intense aerobic exercise training. Biopsies were obtained from musculus vastus lateralis, and arteriovenous blood sampling for assessment of oxygen extraction and leg blood flow during exercise was done before and after immobilization and training. Muscle capillarization, muscle and platelet content of vascular endothelial growth factor (VEGF), and muscle thrombospondin-1 were determined.

RESULTS

Immobilization did not have a significant impact on capillary per fiber ratio or capillary density. The content of VEGF protein in muscle samples was reduced by 36% (P = 0.024), and VEGF to thrombospondin-1 ratio was 94% lower (P = 0.046). The subsequent 4-wk training period increased the muscle VEGF content and normalized the muscle VEGF to thrombospondin-1 ratio but did not influence capillarization. Platelet VEGF content followed the trend of muscle VEGF. At the functional level, oxygen extraction, blood flow, and oxygen delivery at rest and during submaximal exercise were not affected by immobilization or training.

CONCLUSIONS

The results demonstrate that just 2 wk of leg immobilization leads to a strongly reduced angiogenic potential as evidenced by reduced muscle and platelet VEGF content and a reduced muscle VEGF to thrombospondin-1 ratio. Moreover, a subsequent period of intensive aerobic exercise training fails to increase capillarization in the previously immobilized leg, possibly because of the angiostatic condition caused by immobilization.

Augmentation of CD47/SIRPα signaling protects cones in genetic models of retinal degeneration

Inherited retinal diseases, such as retinitis pigmentosa (RP), can be caused by thousands of different mutations, a small number of which have been successfully treated with gene replacement. However, this approach has yet to scale and may not be feasible in many cases, highlighting the need for interventions that could benefit more patients. Here, we found that microglial phagocytosis is upregulated during cone degeneration in RP, suggesting that expression of "don't-eat-me" signals such as CD47 might confer protection to cones. To test this, we delivered an adeno-associated viral (AAV) vector expressing CD47 on cones, which promoted cone survival in 3 mouse models of RP and preserved visual function. Cone rescue with CD47 required a known interacting protein, signal regulatory protein α (SIRPα), but not an alternative interacting protein, thrombospondin-1 (TSP1). Despite the correlation between increased microglial phagocytosis and cone death, microglia were dispensable for the prosurvival activity of CD47, suggesting that CD47 interacts with SIRPα on nonmicroglial cells to alleviate degeneration. These findings establish augmentation of CD47/SIRPα signaling as a potential treatment strategy for RP and possibly other forms of neurodegeneration.

Characterization of Thrombospondin Type 1 Repeat in Haliotis diversicolor and Its Possible Role in Osteoinduction

Thrombospondin repeats (TSR) are important peptide domains present in the sequences of many extracellular and transmembrane proteins with which a variety of ligands interact. In this study, we characterized HdTSR domains in the ADAMTS3 protein of Thai abalone, Haliotis diversicolor, based on the transcriptomic analysis of its mantle tissues. PCR amplification and localization studies demonstrated the existence of HdTSR transcript and protein in H. diversicolor tissues, particularly in both the inner and outer mantle epithelial folds. We, therefore, generated a short recombinant protein, termed HdTSR1/2, based on the existence of the WxxWxxW or WxxxxW motif (which binds to TGF-β, a known signaling in bone formation/repair) in HdTSR1 and HdTSR2 sequences and used it to test the osteoinduction function in the pre-osteoblastic cell line, MC3T3-E1. This recombinant protein demonstrated the ability to induce the differentiation of MC3T3-E1 cells by the concentration- and time-dependent upregulation of many known osteogenic markers, including RUNX2, COL1A1, OCN, and OPN. We also demonstrated the upregulation of the SMAD2 gene after cell treatment with HdTSR1/2 proteinindicating its possible interaction through TGF-β, which thus activates its downstream signaling cascade and triggers the biomineralization process in the differentiated osteoblastic cells. Together, HdTSR domains existed in an extracellular ADAMTS3 protein in the mantle epithelium of H. diversicolor and played a role in osteoinduction as similar to the other nacreous proteins, opening up its possibility to be developed as an inducing agent of bone repair.

Targeting TSP-1 decreased periodontitis by attenuating extracellular matrix degradation and alveolar bone destruction

An important factor in periodontitis pathogenesis relates to a network of interactions of various cytokines. Thrombospondin-1 (TSP-1) is upregulated in several inflammatory diseases. We previously found that Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS)-induced TSP-1 production, and that TSP-1 simultaneously and effectively elevated inflammatory cytokines in THP-1 macrophages. This suggests that TSP-1 plays an important role in the pathology of periodontitis. However, the function of TSP-1 on oral cells is largely unknown. This study aimed to elucidate the underlying molecular mechanisms of TSP-1 in human periodontal fibroblasts (hPDLFs). We demonstrated that TSP-1 is highly expressed in the gingival crevicular fluid of patients with chronic periodontitis and in the inflammatory gingival tissues of rats. TSP-1 overexpression or treatment with recombinant human TSP-1(rTSP-1) promoted the expression of MMP-2, MMP-9 and RANKL/OPG in hPDLFs, while anti-TSP-1 inhibited cytokines production from P. gingivalis LPS-treated hPDLFs. Additional experiments showed that SB203580 (a special p38MAPK inhibitor) inhibited MMP-2, MMP-9 and RANKL/OPG expression induced by rTSP-1. Thus, TSP-1 effectively promoted P. gingivalis LPS-induced periodontal tissue (extracellular matrix (ECM) and alveolar bone) destruction by the p38MAPK signalling pathway, indicating that it may be a potential therapeutic target against periodontitis.

METTL3 Regulates Angiogenesis by Modulating let-7e-5p and miRNA-18a-5p Expression in Endothelial Cells

[Figure: see text].

Functions of Thrombospondin-1 in the Tumor Microenvironment

The identification of thrombospondin-1 as an angiogenesis inhibitor in 1990 prompted interest in its role in cancer biology and potential as a therapeutic target. Decreased thrombospondin-1 mRNA and protein expression are associated with progression in several cancers, while expression by nonmalignant cells in the tumor microenvironment and circulating levels in cancer patients can be elevated. THBS1 is not a tumor suppressor gene, but the regulation of its expression in malignant cells by oncogenes and tumor suppressor genes mediates some of their effects on carcinogenesis, tumor progression, and metastasis. In addition to regulating angiogenesis and perfusion of the tumor vasculature, thrombospondin-1 limits antitumor immunity by CD47-dependent regulation of innate and adaptive immune cells. Conversely, thrombospondin-1 is a component of particles released by immune cells that mediate tumor cell killing. Thrombospondin-1 differentially regulates the sensitivity of malignant and nonmalignant cells to genotoxic stress caused by radiotherapy and chemotherapy. The diverse activities of thrombospondin-1 to regulate autophagy, senescence, stem cell maintenance, extracellular vesicle function, and metabolic responses to ischemic and genotoxic stress are mediated by several cell surface receptors and by regulating the functions of several secreted proteins. This review highlights progress in understanding thrombospondin-1 functions in cancer and the challenges that remain in harnessing its therapeutic potential.

Thrombospondin 1 in Metabolic Diseases

The thrombospondin family comprises of five multifunctional glycoproteins, whose best-studied member is thrombospondin 1 (TSP1). This matricellular protein is a potent antiangiogenic agent that inhibits endothelial migration and proliferation, and induces endothelial apoptosis. Studies have demonstrated a regulatory role of TSP1 in cell migration and in activation of the latent transforming growth factor beta 1 (TGFβ1). These functions of TSP1 translate into its broad modulation of immune processes. Further, imbalances in immune regulation have been increasingly linked to pathological conditions such as obesity and diabetes mellitus. While most studies in the past have focused on the role of TSP1 in cancer and inflammation, recently published data have revealed new insights about the role of TSP1 in physiological and metabolic disorders. Here, we highlight recent findings that associate TSP1 and its receptors to obesity, diabetes, and cardiovascular diseases. TSP1 regulates nitric oxide, activates latent TGFβ1, and interacts with receptors CD36 and CD47, to play an important role in cell metabolism. Thus, TSP1 and its major receptors may be considered a potential therapeutic target for metabolic diseases.