Thrombin promotes the expression of thrombospondin-1 and ‐2 in a rat model of intracerebral hemorrhage

The Contributions of Thrombospondin-1 to Epilepsy Formation

Epilepsy is a neural network disorder caused by uncontrolled neuronal hyperexcitability induced by an imbalance between excitatory and inhibitory networks. Abnormal synaptogenesis plays a vital role in the formation of overexcited networks. Recent evidence has confirmed that thrombospondin-1 (TSP-1), mainly secreted by astrocytes, is a critical cytokine that regulates synaptogenesis during epileptogenesis. Furthermore, numerous studies have reported that TSP-1 is also involved in other processes, such as angiogenesis, neuroinflammation, and regulation of Ca2+ homeostasis, which are closely associated with the occurrence and development of epilepsy. In this review, we summarize the potential contributions of TSP-1 to epilepsy development.

Benzene, 1,2,4-Trimethoxy-5-(2-Methyl-1-Propen-1-yl), a New Neuroprotective Agent, Treats Intracerebral Hemorrhage by Inhibiting Apoptosis, Inflammation, and Oxidative Stress

The highest disability rates and mortality among neurodegenerative diseases were caused by intracerebral hemorrhage (ICH). We previously proved that Benzene, 1,2,4-trimethoxy-5-(2-methyl-1-propen-1-yl) (BTY) has an inhibitory effect on sodium ion channel and an activation effect on GABA_A receptor, which were related to the brain injury. Based on this, we aimed to investigate BTY's neuroprotection on intracerebral hemorrhage and its underlying mechanism. In the in vivo study, a stereotactic injection of collagenase VII in Sprague Dawley rats (0.5 U) induced ICH and the BTY was intraperitoneally injected at 2 h after ICH. The neurological deficit scores, blood-brain barrier (BBB) permeability, and other indicators were assessed 24 h after ICH. The results showed that the BTY reduced brain edema and hematoma volume, improved neurological function and BBB permeability, and inhibited inflammatory factors and neuron apoptosis. The cell experiments proved that the BTY suppressed oxidative stress, cell apoptosis, intracellular calcium influx, and stabilized mitochondrial membrane potential by reducing glutamate's excitotoxicity. This study for the first time exhibited desirable neuroprotection of BTY, indicating it may be a promising neuroprotective agent for ICH therapy.

Temporal profile of angiogenesis and expression of extracellular matrix-related genes in rat brains following experimental intracerebral hemorrhage

BACKGROUND

Angiogenesis is essential for the repair process after intracerebral hemorrhage (ICH).

METHODS

Given the importance of the extracellular matrix (ECM) in angiogenesis, we analysed the temporal profile of angiogenesis in rat brains on days 4, 7, and 21 after ICH. To this end, we compared the expression of ECM-related genes between ICH-induced and sham-operated groups using a complementary DNA (cDNA) array. We further measured protein expression using western blot and immunohistochemistry assays. Fluorescein isothiocyanate (FITC)-dextran was injected into the tail vein to examine the angioarchitecture in the perihematomal region.

RESULTS

Among the 88 ECM-related genes, we identified 42, 50, and 38 genes that were significantly upregulated on days 4, 7, and 21 after ICH, respectively (P < 0.05). Particularly, collagens, integrins, and matrix metalloproteinases (MMPs) were significantly increased on day 4 post-ICH and continued to increase at the other time points. Western blot and immunohistochemistry analyses showed a comparable trend in the upregulation of MMPs. Compared to the sham group, FITC-dextran labelling demonstrated decreased perfusion and increased vascular permeability in the perihematomal region in the ICH group. Doxycycline, an MMP inhibitor, significantly reduced angiogenesis (P < 0.05).

CONCLUSIONS

The results of this study indicate that MMPs are involved in modulating angiogenesis following ICH.

Plasminogen deficiency causes reduced angiogenesis and behavioral recovery after stroke in mice

Plasminogen is involved in the process of angiogenesis; however, the underlying mechanism is unclear. Here, we investigated the potential contribution of plasmin/plasminogen in mediating angiogenesis and thereby contributing to functional recovery post-stroke. Wild-type plasminogen naive (Plg^+/+) mice and plasminogen knockout (Plg^-/-) mice were subjected to unilateral permanent middle cerebral artery occlusion (MCAo). Blood vessels were labeled with FITC-dextran. Functional outcomes, and cerebral vessel density were compared between Plg^+/+ and Plg^-/- mice at different time points after stroke. We found that Plg^-/- mice exhibited significantly reduced functional recovery, associated with significantly decreased vessel density in the peri-infarct area in the ipsilesional cortex compared with Plg^+/+ mice. In vitro, cerebral endothelial cells harvested from Plg^-/- mice exhibited significantly reduced angiogenesis assessed using tube formation assay, and migration, as evaluated using Scratch assays, compared to endothelial cells harvested from Plg^+/+ mice. In addition, using Western blots, expression of thrombospondin (TSP)-1 and TSP-2 were increased after MCAo in the Plg^-/- group compared to Plg^+/+ mice, especially in the ipsilesional side of brain. Taken together, our data suggest that plasmin/plasminogen down-regulates the expression level of TSP-1 and TSP-2, and thereby promotes angiogenesis in the peri-ischemic brain tissue, which contributes to functional recovery after ischemic stroke.

Expression and methylation status of vascular endothelial growth factor and thrombospondin-1 genes in congenital factor XIII-deficient patients with intracranial hemorrhage

Congenital factor XIII (FXIII) deficiency is one of the rarest bleeding disorders, with an incidence of one per 2 million persons. Intracranial hemorrhage (ICH), a major cause of mortality in FXIII deficiency, is reported to be associated with vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1). Therefore, we investigated the association of VEGF and TSP-1 expression and methylation patterns with ICH in congenital FXIII deficiency patients. This study was conducted on 40 participants with FXIII, 20 of whom experienced ICH (cases), and 20 who did not (controls). Methylation pattern, gene expression, and plasma protein level were assessed using bisulfite sequencing PCR, quantitative real-time PCR, and ELISA. We found a partially methylated pattern for both VEGF and TSP-1 (P > 0.05). VEGF mRNA levels of the case group were significantly higher than those of the control group (P < 0.05), whereas TSP-1 mRNA levels did not show significant upregulation (P > 0.05). Plasma VEGF and TSP-1 concentrations in the case group were higher, but not statistically significant (P > 0.05). Our findings showed no obvious correlation between VEGF or TSP-1 methylation patterns and expression, suggesting that their expression in FXIII deficiency may not solely be controlled by gene methylation.

Early Tranexamic Acid Administration After Traumatic Brain Injury Is Associated With Reduced Syndecan-1 and Angiopoietin-2 in Patients With Traumatic Intracranial Hemorrhage

OBJECTIVE

To evaluate the effect of early tranexamic acid (TXA) administration on circulating markers of endotheliopathy.

SETTING

Twenty trauma centers in the United States and Canada.

PARTICIPANTS

Patients with moderate-to-severe traumatic brain injury (TBI) (MS-TBI) and intracranial hemorrhage who were not in shock (systolic blood pressure ≥90 mm Hg).

DESIGN

TXA (2 g) or placebo administered prior to hospital arrival, less than 2 hours postinjury. Blood samples and head computed tomographic scan collected upon arrival. Plasma markers measured using Luminex analyte platform. Differences in median marker levels evaluated using t tests performed on log-transformed variables. Comparison groups were TXA versus placebo and less than 45 minutes versus 45 minutes or more from time of injury to treatment administration.

MAIN MEASURES

Plasma levels of angiopoietin-1, angiopoietin-2, syndecan-1, thrombomodulin, thrombospondin-2, intercellular adhesion molecule 1, vascular adhesion molecule 1.

RESULTS

Demographics and Injury Severity Score were similar between the placebo (n = 129) and TXA (n = 158) groups. Levels of syndecan-1 were lower in the TXA group (median [interquartile range or IQR] = 254.6 pg/mL [200.7-322.0] vs 272.4 pg/mL [219.7-373.1], P = .05. Patients who received TXA less than 45 minutes postinjury had significantly lower levels of angiopoietin-2 (median [IQR] = 144.3 pg/mL [94.0-174.3] vs 154.6 pg/mL [110.4-209.8], P = .05). No differences were observed in remaining markers.

CONCLUSIONS

TXA may inhibit early upregulation of syndecan-1 and angiopoietin-2 in patients with MS-TBI, suggesting attenuation of protease-mediated vascular glycocalyx breakdown. The findings of this exploratory analysis should be considered preliminary and require confirmation in future studies.

Thrombin-induced miRNA-24-1-5p upregulation promotes angiogenesis by targeting prolyl hydroxylase domain 1 in intracerebral hemorrhagic rats

OBJECTIVE

Thrombin is a unique factor that triggers post-intracerebral hemorrhage (ICH) angiogenesis by increasing hypoxia-inducible factor-1α (HIF-1α) at the protein level. However, HIF-1α mRNA remains unchanged. MicroRNAs (miRNAs) mediate posttranscriptional regulation by suppressing protein translation from mRNAs. This study aimed to determine if miRNAs might be involved in thrombin-induced angiogenesis after ICH by targeting HIF-1α or its upstream prolyl hydroxylase domains (PHDs).

METHODS

The study was divided into two parts. In part 1, rats received an injection of thrombin into the right globus pallidus. An miRNA array combined with miRNA target prediction, luciferase activity assay, and miRNA mimic/inhibitor transfection were used to identify candidate miRNAs and target genes. Part 2 included experiments 1 and 2. In experiment 1, rats were randomly divided into the sham group, ICH group, and ICH+hirudin-treated (thrombin inhibitor) group. In experiment 2, the rats were randomly divided into the sham group, ICH group, ICH+antagomir group, ICH+antagomir-control group, and ICH+vehicle group. Western blotting and quantitative real-time polymerase chain reaction were used to determine the expression of protein and miRNA, respectively. The coexpression of miR-24-1-5p (abbreviated to miR-24) and von Willebrand factor was detected by in situ hybridization and immunohistochemical analysis. The angiogenesis was evaluated by double-labeling immunofluorescence. Neurological function was evaluated by body weight, modified Neurological Severity Scores, and corner turn and foot-fault tests.

RESULTS

In part 1, it was shown that miR-24, which is predicted to target PHD1, was upregulated (fold-change of 1.83) after thrombin infusion, and that the miR-24 mimic transfection decreased luciferase activity and downregulated PHD1 expression (p < 0.05). miR-24 inhibitor transfection increased PHD1 expression (p < 0.05). In part 2, it was shown that miR-24 was expressed in endothelial cells. The HIF-1α protein level and proliferating cell nuclear antigen-positive (PCNA+) nuclei in vessels were increased, while the PHD1 protein level was decreased after ICH, and these effects were reversed by hirudin (p < 0.05). The antagomiR-24-treated rats exhibited a markedly lower body weight and significantly poorer recovery from neurological deficit compared with those in ICH groups (p < 0.05). AntagomiR-24 intervention also led to lower miR-24 expression, a higher PHD1 protein level, and fewer PCNA+ nuclei in vessels compared with those in ICH groups (p < 0.05).

CONCLUSIONS

The present study suggests that thrombin reduces HIF-1α degradation and initiates angiogenesis by increasing miR-24, which targets PHD1 after ICH.

Role of thrombospondin‑1 and thrombospondin‑2 in cardiovascular diseases (Review)

Thrombospondin (TSP)-1 and TSP-2 are matricellular proteins in the extracellular matrix (ECM), which serve a significant role in the pathological processes of various cardiovascular diseases (CVDs). The multiple effects of TSP-1 and TSP-2 are due to their ability to interact with various ligands, such as structural components of the ECM, cytokines, cellular receptors, growth factors, proteases and other stromal cell proteins. TSP-1 and TSP-2 regulate the structure and activity of the aforementioned ligands by interacting directly or indirectly with them, thereby regulating the activity of different types of cells in response to environmental stimuli. The pathological processes of numerous CVDs are associated with the degradation and remodeling of ECM components, and with cell migration, dysfunction and apoptosis, which may be regulated by TSP-1 and TSP-2 through different mechanisms. Therefore, investigating the role of TSP-1 and TSP-2 in different CVDs and the potential signaling pathways they are associated with may provide a new perspective on potential therapies for the treatment of CVDs. In the present review, the current understanding of the roles TSP-1 and TSP-2 serve in various CVDs were summarized. In addition, the interacting ligands and the potential pathways associated with these thrombospondins in CVDs are also discussed.

Intra-arterial transplantation of human bone marrow mesenchymal stem cells (hBMMSCs) improves behavioral deficits and alters gene expression in rodent stroke model

Stroke is a multi-factorial polygenic disease and is a major cause of death and adult disability. Administration of bone marrow stem cells protects ischemic rat brain by facilitating recovery of neurological functions. But the molecular mechanism of stem cells action and their effect on gene expression is not well explored. In this study, we have transplanted 1 × 10⁶ human bone marrow mesenchymal stem cells (hBMMSCs) in middle cerebral artery occluded (MCAo) adult male Wistar rats through intracarotid artery route at 24 h after surgery. Motor behavioral tests (rotarod and open field) were performed to assess the changes in motor functions at day 0 and day1, 4, 8 and 14. The expression of studied genes at mRNA and protein level was quantified by using Q-PCR and western blotting, respectively. Further, we have assessed the methylation pattern of promoter of these genes by using methylation-specific PCR. Data were analyzed statistically and correlated. A significant improvement in behavioral deficits was observed in stem cells treated group after 14th day post stroke. Significantly (p < 0.05) increased mRNA and protein levels of brain derived neurotrophic factor and ANP genes in hBMMSCs treated group along with decrease in methylation level at their promoter was observed. On the other hand, significantly decreased mRNA and protein level of TSP1 and WNK1 in hBMMSCs treated group was observed. In conclusion, hBMMSCs administration significantly improves the behavioral deficits by improving motor and locomotor coordination. The promoter of TSP1 and WNK1 genes was found to be hyper-methylated in hBMMSCs group resulting in their decreased expression while the promoter of ANP and brain derived neurotrophic factor was found to be hypo-methylated. This study might shed a light on how hBMMSCs affect the gene expression by modulating methylation status.

The Roles of Thrombospondins in Hemorrhagic Stroke

Hemorrhagic stroke is a devastating cerebrovascular disease with significant morbidity and mortality worldwide. Thrombospondins (TSPs), as matricellular proteins, belong to the TSP family which is comprised of five members. All TSPs modulate a variety of cellular functions by binding to various receptors. Recently, TSPs gained attention in the area of hemorrhagic stroke, especially TSP-1. TSP-1 participates in angiogenesis, the inflammatory response, apoptosis, and fibrosis after hemorrhagic stroke through binding to various molecules including but not limited to CD36, CD47, and TGF-β. In this review, we will discuss the roles of TSPs in hemorrhagic stroke and focus primarily on TSP-1.

Early Combined Therapy with Pharmacologically Induced Hypothermia and Edaravone Exerts Neuroprotective Effects in a Rat Model of Intracerebral Hemorrhage

In present study, we evaluated acute neuroprotective effects of combined therapy with pharmacologically induced hypothermia and edaravone in a rat model of intracerebral hemorrhage (ICH). ICH was caused by injection of 0.5 U of collagenase VII to the caudate nucleus of male Sprague-Dawley rats. Sham-treated animals receive injections of normal saline instead of collagenase VII. All animals were randomly divided into five groups: sham group, ICH group, hypothermia group, edavarone (10 mg/kg) group, and combined hypothermia + edavarone group. Hypothermia was induced by injection of the second-generation neurotensin receptor agonist HPI-201 (2 mg/kg at 1 h after ICH; 1 mg/kg at 4 and 7 h after ICH). Hypothermia was sustained for at least 6 h. The study outcomes were the extent of brain edema, permeability of the blood-brain barrier (Evan's blue dye), expression of matrix metalloproteinase-9 and inflammatory cytokines (IL-1β, IL-4, IL-6, and TNF-α), and expression of apoptosis-related proteins (caspase-3, cytochrome C, Bcl-2, and Bax). Brain edema, permeability of the blood-brain barrier, and expression of metalloproteinase-9 were increased, while expression of caspase-3 and Bcl-2 was decreased by ICH. We observed that the combined therapy was significantly more potent in reverting the above negative trends induced by ICH. In conclusion, our results indicate that a combination of pharmacologically induced hypothermia and edavarone leads to potentiation of their respective neuroprotective effects.

Plasma thrombospondin-1 and clinical outcomes in traumatic brain injury

OBJECTIVE

Thrombospondin-1 (TSP-1) acts as an anti-angiogenic factor, and its expression in rat brain is upregulated after intracerebral hemorrhage. The current study was designed to investigate the change of plasma TSP-1 levels and assess the prognostic predictive effect of plasma TSP-1 level and it is associated with head trauma severity in the patients with severe traumatic brain injury (STBI).

MATERIALS AND METHODS

The plasma TSP-1 levels of 134 patients and 134 healthy controls were measured using enzyme-linked immunosorbent assay. The relationships between plasma TSP-1 levels and trauma severity reflected by Glasgow Coma Scale (GCS) scores as well as between plasma TSP-1 levels and short-term and long-term clinical outcomes were analyzed using multivariate analysis.

RESULTS

Plasma TSP-1 levels were statistically significantly higher in patients than in healthy controls. The multivariate analysis demonstrated close association of TSP-1 with GCS scores and also identified TSP-1 as an independent predictor for 1-week mortality, 6-month mortality, and 6-month unfavorable outcome. Plasma TSP-1 levels had high prognostic predictive value based on receiver operating characteristic curve. The difference between its prognostic predictive value and GCS scores was not statistically significant.

CONCLUSIONS

Plasma TSP-1 levels are elevated and are highly associated with head trauma severity and short-term and long-term outcomes of STBI. TSP-1 may be a good prognostic biomarker of STBI.

Hantavirus Infection Suppresses Thrombospondin-1 Expression in Cultured Endothelial Cells in a Strain-Specific Manner

Hantavirus infection is associated with two frequently fatal diseases in humans: Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The pathogenesis of hantavirus infection is complex and not fully understood; however, it is believed to involve virus-induced hyperinflammatory immune responses. Thrombospondin-1 (THBS1) is a large homotrimeric protein that plays a putative role in regulating blood homeostasis. Hyperresponsiveness to inflammatory stimuli has also been associated with defects in the THBS1 gene. Our data suggest that hantavirus infection of human umbilical cord vein endothelial cells (HUVEC) suppress the accumulation of THBS1 in the extracellular matrix. Additionally, this suppression is dependent on virus replication, implying a direct mechanism of action. Our data also imply that the pathogenic Andes and Hantaan strains inhibit THBS1 expression while the non-pathogenic Prospect Hill strain showed little inhibition. These observations suggest that a dysregulation of THBS1 may contribute to the pathogenesis of hantavirus infection.

Effect of ephrin-B2 on the expressions of angiopoietin-1 and -2 after focal cerebral ischemia/reperfusion

Ephrin-B2 has been shown to participate in angiogenesis, but the underlying mechanisms involved remain unclear. In this study, a rat model of focal cerebral ischemia was prepared by focal middle cerebral artery occlusion, followed by 24-hour reperfusion. Then, ephrin-B2 protein was administered intracerebroventricularly for 3 consecutive days via a micro-osmotic pump. Western blot assay and quantitative real-time reverse transcription PCR demonstrated the expression levels of angiopoietin-1 (Ang-1) mRNA and protein in the penumbra cortex of the ephrin-B2 treated group were decreased at day 4 after reperfusion, and increased at day 28, while the expression levels of angiopoietin-2 (Ang-2) were highly up-regulated at all time points tested. Double immunofluorescent staining indicated that Ang-1 and Ang-2 were both expressed in vascular endothelial cells positive for CD31. These findings indicate that ephrin-B2 influences the expressions of Ang-1 and Ang-2 during angiogenesis following transient focal cerebral ischemia.

Natural Hirudin Increases Rat Flap Viability by Anti-Inflammation via PARs/p38/NF-κB Pathway

The present study aimed to evaluate the effect of natural hirudin on rat random skin flap viability and to determine the mechanism. Forty-eight rats were randomly divided into 2 groups. After the dorsal skin flap operation (3 cm × 10 cm in size), subcutaneous injections of 6 ATU hirudin were administered to group H (n = 24) every 12 h, while group C (n = 24) received an equal volume of 0.9% normal saline. Six rats from each group were euthanized 1, 2, 4, and 7 days after the operation. A full skin sample was collected from these rats to measure the p38-mitogen-activated protein kinase (p38-MAPK), phospho-p38- (Pp38-) MAPK, nuclear factor-κB (NF-κB) p65, phosphor-NF-κB (pNF-κB) p65, tumour necrosis factor- (TNF-) α, interleukin- (IL-) 6, and intercellular adhesion molecule- (ICAM-) 1 levels via western blot (WB) assays. The results showed that flap viability was significantly higher in the hirudin-treated group, which showed a reduced inflammatory response compared with the control group. The Pp38/p38, pNF-κB p65/NF-κB p65, TNF-α, IL-6, and ICAM-1 levels in the hirudin-treated group were lower than those in the control group. The results demonstrated that hirudin could improve random skin flap viability and suggested that this effect maybe occurs by blocking the thrombin/proteinase-activated receptors (PARs)/p38/NF-κB signalling pathway, thus decreasing the inflammatory response.

Predictive value of thrombospondin-1 for outcomes in patients with acute ischemic stroke

BACKGROUND

Thrombospondin-1 is a potent regulator of angiogenesis. The expression of cerebral thrombospondin-1 is promoted in a rat model of intracerebral hemorrhage. The current study was designed to investigate the change of plasma thrombospondin-1 concentrations and assess the prognostic value of plasma thrombospondin-1 concentrations for long-term mortality and functional outcome of ischemic stroke patients.

METHODS

This study included 192 patients and 150 healthy controls. The plasma thrombospondin-1 concentrations were measured using enzyme-linked immunosorbent assay. An unfavorable outcome was defined as a modified Rankin Scale score >3. The relationships between plasma thrombospondin-1 concentrations and 6-month clinical outcomes were analyzed using multivariate analysis.

RESULTS

Compared with healthy controls, plasma thrombospondin-1 concentrations were statistically significantly elevated in patients. Using multivariate analysis, thrombospondin-1 emerged as an independent predictor for 6-month mortality, 6-month unfavorable outcome and 6-month overall survival. Plasma thrombospondin-1 concentrations possessed high predictive values under receiver operating characteristic curve. Their predictive values were similar to those of National Institutes of Health Stroke Scale scores.

CONCLUSIONS

Plasma thrombospondin-1 concentrations are elevated obviously and are highly associated with long-term outcome of ischemic stroke.

The use of ADSCs as a treatment for chronic stroke

Stroke is one of the disorders for which clinically effective therapeutic modalities are most needed, and numerous ways have been explored to attempt to investigate their feasibilities. However, ischemic- or hemorrhagic-induced inflammatory neuron death causes irreversible injuries and infarction regions, and there are currently no truly effective drugs available as therapy. It is therefore urgent to be able to provide a fundamental treatment method to regenerate neuronal brain cells, and therefore, the use of stem cells for curing chronic stroke could be a major breakthrough development. In this review, we describe the features and classification of stroke and focus on the benefits of adipose tissue-derived stem cells and their applications in stroke animal models. The results show that cell-based therapies have resulted in significant improvements in neuronal behaviors and functions through different molecular mechanisms, and no safety problems have so far arisen after transplantation. Further, we propose a clinical possibility to create a homing niche by reducing the degree of invasive intracerebroventricular transplantation and combining it with continuous intravenous administration to achieve a complete cure.