Biology of Tenascin C and its Role in Physiology and Pathology

Tenascin-C (TNC) is a multimodular extracellular matrix (ECM) protein hexameric with several molecular forms (180-250 kDa) produced by alternative splicing at the pre-mRNA level and protein modifications. The molecular phylogeny indicates that the amino acid sequence of TNC is a well-conserved protein among vertebrates. TNC has binding partners, including fibronectin, collagen, fibrillin-2, periostin, proteoglycans, and pathogens. Various transcription factors and intracellular regulators tightly regulate TNC expression. TNC plays an essential role in cell proliferation and migration. Unlike embryonic tissues, TNC protein is distributed over a few tissues in adults. However, higher TNC expression is observed in inflammation, wound healing, cancer, and other pathological conditions. It is widely expressed in a variety of human malignancies and is recognized as a pivotal factor in cancer progression and metastasis. Moreover, TNC increases both pro-and anti-inflammatory signaling pathways. It has been identified as an essential factor in tissue injuries such as damaged skeletal muscle, heart disease, and kidney fibrosis. This multimodular hexameric glycoprotein modulates both innate and adaptive immune responses regulating the expression of numerous cytokines. Moreover, TNC is an important regulatory molecule that affects the onset and progression of neuronal disorders through many signaling pathways. We provide a comprehensive overview of the structural and expression properties of TNC and its potential functions in physiological and pathological conditions.

The role of Tenascin C in intracerebral hemorrhage-induced secondary brain injury in rats via induction of neuronal cell death and neuroinflammation

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) is a major cause of stroke that causes high rates of disability and mortality in adults. Tenascin C (TNC) protein, one of the matricellular proteins associated with platelet-derived growth factor receptor (PDGFR) activation, has been reported to induce neuronal apoptosis. However, the role and underlying mechanisms of TNC in ICH-induced secondary brain injury (SBI) have not yet been fully explained. The main purpose of this study was to explore the role of TNC and its potential mechanisms in ICH.

METHODS

An ICH model was established by injecting autologous blood into the right basal ganglia in male Sprague Dawley (SD) rats, and imatinib, an inhibitor of PDGFR, was used to inhibit the release of TNC.

RESULTS

We found that TNC protein was significantly increased in the brain tissues after ICH and expressed in both neurons and microglia. We also found that the TNC level was elevated in the cerebrospinal fluid (CSF) after ICH. Additionally, we observed that the infiltration of activated microglia and the release of TNFα and IL-1β induced by ICH were decreased after inhibition of the protein levels of TNC and cleaved-TNC by a chemical inhibitor (imatinib). Furthermore, imatinib improved neuronal cell death and neurobehavioral abnormalities induced by ICH.

CONCLUSION

In summary, our study revealed that TNC protein plays an important role in ICH-induced SBI, and inhibition of TNC could alleviate ICH-induced neuroinflammation, neuronal cell death, and neurobehaviour. Therefore, TNC may be a potential therapeutic target for ICH-induced SBI.

Matricellular protein tenascin C: Implications in glioma progression, gliomagenesis, and treatment

Matricellular proteins are nonstructural extracellular matrix components that are expressed at low levels in normal adult tissues and are upregulated during development or under pathological conditions. Tenascin C (TNC), a matricellular protein, is a hexameric and multimodular glycoprotein with different molecular forms that is produced by alternative splicing and post-translational modifications. Malignant gliomas are the most common and aggressive primary brain cancer of the central nervous system. Despite continued advances in multimodal therapy, the prognosis of gliomas remains poor. The main reasons for such poor outcomes are the heterogeneity and adaptability caused by the tumor microenvironment and glioma stem cells. It has been shown that TNC is present in the glioma microenvironment and glioma stem cell niches, and that it promotes malignant properties, such as neovascularization, proliferation, invasiveness, and immunomodulation. TNC is abundantly expressed in neural stem cell niches and plays a role in neurogenesis. Notably, there is increasing evidence showing that neural stem cells in the subventricular zone may be the cells of origin of gliomas. Here, we review the evidence regarding the role of TNC in glioma progression, propose a potential association between TNC and gliomagenesis, and summarize its clinical applications. Collectively, TNC is an appealing focus for advancing our understanding of gliomas.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Effects of cilostazol treatment for patients with aneurysmal subarachnoid hemorrhage: A meta-analysis of 14 studies

OBJECTIVE

To perform an updated meta-analysis to comprehensively assess the efficacy and safety of cilostazol in preventing aneurysmal subarachnoid hemorrhage (SAH)-related secondary complications.

METHODS

Electronic databases of PubMed, the Cochrane library, CNKI and Wanfang were searched on August 2021. Pooled odds ratio (OR) and standardized mean difference (SMD) were calculated for dichotomous and continuous outcomes, respectively.

RESULTS

A total of 14 studies [comprising 18,726 aneurysmal SAH patients (6654 in the cilostazol group and 12,072 in the control group)] performed in Japan or China were included. Compared with the control group, cilostazol treatment significantly reduced the median cerebral artery (SMD = -0.49; p < 0.001), improved the therapeutic efficacy (OR = 2.37; p = 0.009), decreased the incidence of symptomatic vasospasm/delayed cerebral ischemia (OR = 0.42; p < 0.001), severe angiographic vasospasm (OR = 0.54; p < 0.001), new cerebral infarction (OR = 0.33; p < 0.001), poor outcomes (OR = 0.86; p = 0.001), mortality (OR = 0.62; p < 0.001) and increased the incidence of no or mild angiographic vasospasm (OR = 1.94; p = 0.004), but did not induce more adverse events (OR = 1.08; p = 0.871). The mechanism of cilostazol treatment was to inhibit the production of tenascin-C (SMD = -1.46; p < 0.001). These results were hardly changed by subgroup analysis.

CONCLUSION

This meta-analysis indicates cilostazol may be an effective and safe drug for aneurysmal SAH patients. However, further trials involving other world populations are required to demonstrate the generalization of treatment effects of cilostazol.

Tenascin-C induction exacerbates post-stroke brain damage

The role of tenascin-C (TNC) in ischemic stroke pathology is not known despite its prognostic association with cerebrovascular diseases. Here, we investigated the effect of TNC knockdown on post-stroke brain damage and its putative mechanism of action in adult mice of both sexes. Male and female C57BL/6 mice were subjected to transient middle cerebral artery occlusion and injected (i.v.) with either TNC siRNA or a negative (non-targeting) siRNA at 5 min after reperfusion. Motor function (beam walk and rotarod tests) was assessed between days 1 and 14 of reperfusion. Infarct volume (T2-MRI), BBB damage (T1-MRI with contrast), and inflammatory markers were measured at 3 days of reperfusion. The TNC siRNA treated cohort showed significantly curtailed post-stroke TNC protein expression, motor dysfunction, infarction, BBB damage, and inflammation compared to the sex-matched negative siRNA treated cohort. These results demonstrate that the induction of TNC during the acute period after stroke might be a mediator of post-ischemic inflammation and secondary brain damage independent of sex.

The Pathogenesis of Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) and reportedly contributes to poor neurological outcomes. In this review, we summarize the molecular and cellular mechanisms involved in the pathogenesis of hydrocephalus following aSAH and summarize its treatment strategies. Various mechanisms have been implicated for the development of chronic hydrocephalus following aSAH, including alterations in cerebral spinal fluid (CSF) dynamics, obstruction of the arachnoid granulations by blood products, and adhesions within the ventricular system. Regarding molecular mechanisms that cause chronic hydrocephalus following aSAH, we carried out an extensive review of animal studies and clinical trials about the transforming growth factor-β/SMAD signaling pathway, upregulation of tenascin-C, inflammation-dependent hypersecretion of CSF, systemic inflammatory response syndrome, and immune dysregulation. To identify the ideal treatment strategy, we discuss the predictive factors of shunt-dependent hydrocephalus between surgical clipping and endovascular coiling groups. The efficacy and safety of other surgical interventions including the endoscopic removal of an intraventricular hemorrhage, placement of an external ventricular drain, the use of intraventricular or cisternal fibrinolysis, and an endoscopic third ventriculostomy on shunt dependency following aSAH were also assessed. However, the optimal treatment is still controversial, and it necessitates further investigations. A better understanding of the pathogenesis of acute and chronic hydrocephalus following aSAH would facilitate the development of treatments and improve the outcome.

Discovery and validation of novel protein markers in mucosa of portal hypertensive gastropathy

Background

Portal hypertension induced esophageal and gastric variceal bleeding is the main cause of death among patients of decompensated liver cirrhosis. Therefore, a standardized, biomarker-based test, to make an early-stage non-invasive risk assessment of portal hypertension, is highly desirable. However, no fit-for-purpose biomarkers have yet been identified.

Methods

We conducted a pilot study consisting of 5 portal hypertensive gastropathy (PHG) patients and 5 normal controls, sampling the gastric mucosa of normal controls and PHG patients before and after endoscopic cyanoacrylate injection, using label-free quantitative (LFQ) mass spectrometry, to identify potential biomarker candidates in gastric mucosa from PHG patients and normal controls. Then we further used parallel reaction monitoring (PRM) to verify the abundance of the targeted protein.

Results

LFQ analyses identified 423 significantly differentially expressed proteins. 17 proteins that significantly elevated in the gastric mucosa of PHG patients were further validated using PRM.

Conclusions

This is the first application of an LFQ-PRM workflow to identify and validate PHG–specific biomarkers in patient gastric mucosa samples. Our findings lay the foundation for comprehending the molecular mechanisms of PHG pathogenesis, and provide potential applications for useful biomarkers in early diagnosis and treatment.

Trial registration and ethics approval: Trial registration was completed (ChiCTR2000029840) on February 25, 2020. Ethics Approvals were completed on July 17, 2017 (NYSZYYEC20180003) and February 15, 2020 (NYSZYYEC20200005).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01787-5.

Human Cerebral Cortex Proteome of Fragile X-Associated Tremor/Ataxia Syndrome

Background: Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder associated with premutation CGG-repeat expansions (55–200 repeats) in the 5′ non-coding portion of the fragile X mental retardation 1 (FMR1) gene. Core features of FXTAS include progressive tremor/ataxia, cognitive decline, variable brain volume loss, and white matter disease. The principal histopathological feature of FXTAS is the presence of central nervous system (CNS) and non-CNS intranuclear inclusions.

Objective: To further elucidate the molecular underpinnings of FXTAS through the proteomic characterization of human FXTAS cortexes.

Results: Proteomic analysis of FXTAS brain cortical tissue (n = 8) identified minor differences in protein abundance compared to control brains (n = 6). Significant differences in FXTAS relative to control brain predominantly involved decreased abundance of proteins, with the greatest decreases observed for tenascin-C (TNC), cluster of differentiation 38 (CD38), and phosphoserine aminotransferase 1 (PSAT1); proteins typically increased in other neurodegenerative diseases. Proteins with the greatest increased abundance include potentially novel neurodegeneration-related proteins and small ubiquitin-like modifier 1/2 (SUMO1/2). The FMRpolyG peptide, proposed in models of FXTAS pathogenesis but only identified in trace amounts in the earlier study of FXTAS inclusions, was not identified in any of the FXTAS or control brains in the current study.

Discussion: The observed proteomic shifts, while generally relatively modest, do show a bias toward decreased protein abundance with FXTAS. Such shifts in protein abundance also suggest altered RNA binding as well as loss of cell–cell adhesion/structural integrity. Unlike other neurodegenerative diseases, the proteome of end-stage FXTAS does not suggest a strong inflammation-mediated degenerative response.

The Role of Tenascin-C in Tissue Injury and Repair After Stroke

Stroke is still one of the most common causes for mortality and morbidity worldwide. Following acute stroke onset, biochemical and cellular changes induce further brain injury such as neuroinflammation, cell death, and blood-brain barrier disruption. Matricellular proteins are non-structural proteins induced by many stimuli and tissue damage including stroke induction, while its levels are generally low in a normal physiological condition in adult tissues. Currently, a matricellular protein tenascin-C (TNC) is considered to be an important inducer to promote neuroinflammatory cascades and the resultant pathology in stroke. TNC is upregulated in cerebral arteries and brain tissues including astrocytes, neurons, and brain capillary endothelial cells following subarachnoid hemorrhage (SAH). TNC may be involved in blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm via the activation of mitogen-activated protein kinases and nuclear factor-kappa B following SAH. In addition, post-SAH TNC levels in cerebrospinal fluid predicted the development of delayed cerebral ischemia and angiographic vasospasm in clinical settings. On the other hand, TNC is reported to promote fibrosis and exert repair effects for an experimental aneurysm via macrophages-induced migration and proliferation of smooth muscle cells. The authors review TNC-induced inflammatory signal cascades and the relationships with other matricellular proteins in stroke-related pathology.

Pleiotropic Role of Tenascin-C in Central Nervous System Diseases: From Basic to Clinical Applications

The extracellular matrix is composed of a variety of macromolecular substances secreted by cells, which form a complex network that supports and connects tissue structures, regulates the morphogenesis of tissues, and maintains the physiological activities of cells. Tenascin-C, a secreted extracellular matrix glycoprotein, is abundantly expressed after exposure to pathological stimuli. It plays an important regulatory role in brain tumors, vascular diseases, and neurodegenerative diseases by mediating inflammatory responses, inducing brain damage, and promoting cell proliferation, migration, and angiogenesis through multiple signaling pathways. Therefore, tenascin-C may become a potential therapeutic target for intracranial diseases. Here, we review and discuss the latest literature regarding tenascin-C, and we comprehensively explain the role and clinical significance of tenascin-C in intracranial diseases.

Toll-Like Receptor 4 and Tenascin-C Signaling in Cerebral Vasospasm and Brain Injuries After Subarachnoid Hemorrhage

Toll-like receptor 4 (TLR4) is expressed in various cell types in the central nervous system and exerts maximal inflammatory responses among the TLR family members. TLR4 can be activated by many endogenous ligands having damage-associated molecular patterns including heme and fibrinogen at the rupture of a cerebral aneurysm, and therefore its activation is reasonable as an initial step of cascades to brain injuries after aneurysmal subarachnoid hemorrhage (SAH). TLR4 activation induces tenascin-C (TNC), a representative of matricellular proteins that are a class of inducible, nonstructural, secreted, and multifunctional extracellular matrix glycoproteins. TNC is also an endogenous activator and inducer of TLR4, forming positive feedback mechanisms leading to more activation of the signaling transduction. Our studies have demonstrated that TLR4 as well as TNC are involved in inflammatory reactions, blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm after experimental SAH. This article reviews recent understanding of TLR4 and TNC in SAH to suggest that the TLR4-TNC signaling may be an important therapeutic target for post-SAH brain injuries.

Tenascin-C in brain injuries and edema after subarachnoid hemorrhage: Findings from basic and clinical studies

Subarachnoid hemorrhage (SAH) by a rupture of cerebral aneurysms remains the most devastating cerebrovascular disease. Early brain injury (EBI) is increasingly recognized to be the primary determinant for poor outcomes, and also considered to cause delayed cerebral ischemia (DCI) after SAH. Both clinical and experimental literatures emphasize the impact of global cerebral edema in EBI as negative prognostic and direct pathological factors. The nature of the global cerebral edema is a mixture of cytotoxic and vasogenic edema, both of which may be caused by post-SAH induction of tenascin-C (TNC) that is an inducible, non-structural, secreted and multifunctional matricellular protein. Experimental SAH induces TNC in brain parenchyma in rats and mice. TNC knockout suppressed EBI in terms of brain edema, blood-brain barrier disruption, neuronal apoptosis and neuroinflammation, associated with the inhibition of post-SAH activation of mitogen-activated protein kinases and nuclear factor-kappa B in mice. In a clinical setting, more severe SAH increases more TNC in cerebrospinal fluid and peripheral blood, which could be a surrogate marker of EBI and predict DCI development and outcomes. In addition, cilostazol, a selective inhibitor of phosphodiesterase type III that is a clinically available anti-platelet agent and is known to suppress TNC induction, dose-dependently inhibited delayed cerebral infarction and improved outcomes in a pilot clinical study. Thus, further studies may facilitate application of TNC as biomarkers for non-invasive diagnosis or assessment of EBI and DCI, and lead to development of a molecular target drug against TNC, contributing to the improvement of post-SAH outcomes.

Dose-Dependent Inhibitory Effects of Cilostazol on Delayed Cerebral Infarction After Aneurysmal Subarachnoid Hemorrhage

Cilostazol is a selective inhibitor of phosphodiesterase type III that downregulates tenascin-C (TNC), a matricellular protein, which may cause delayed cerebral infarction after aneurysmal subarachnoid hemorrhage (SAH). The authors increased the dosage and evaluated the dose-dependent effects of cilostazol on delayed cerebral infarction and outcomes in SAH patients. This was a retrospective cohort study in a single center. One hundred fifty-six consecutive SAH patients including 67 patients of admission World Federation of Neurological Surgeons grades IV-V who underwent aneurysmal obliteration within 48 h post-SAH from 2007 to 2017 were analyzed. Cilostazol (0 to 300 mg/day) was administered from 1-day post-clipping or post-coiling to day 14 or later. Cilostazol treatment dose-dependently decreased delayed cerebral infarction and tended to improve outcomes, although cilostazol did not affect other outcome measures including angiographic vasospasm. On multivariate analyses, 300 mg/day (100 mg three times) cilostazol independently decreased delayed cerebral infarction and improved 3-month outcomes, but other regimens including 200 mg/day (100 mg twice) cilostazol were not independent prognostic factors. Propensity score-matched analyses showed that the 300 mg/day cilostazol cohort had lower plasma TNC levels and a lower incidence of delayed cerebral infarction associated with better outcomes compared with the non-cilostazol cohort. The 300 mg/day cilostazol may improve post-SAH outcomes by reducing plasma TNC levels and delayed cerebral infarction, but not vasospasm. Further studies are warranted to investigate if 300 mg/day cilostazol is more beneficial to post-SAH outcomes than a usual dose of 200 mg/day cilostazol that was demonstrated to be effective in randomized controlled trials.

Serum tenascin-C predicts severity and outcome of acute intracerebral hemorrhage

BACKGROUND

Tenascin-C is a matricellular protein related to brain injury. We studied serum tenascin-C in acute intracerebral hemorrhage (ICH) and examined the associations with severity and outcome following the acute event.

METHODS

Tenascin-C samples were obtained from 162 patients with acute hemorrhagic stroke and 162 healthy controls. Poor 90-day functional outcome was defined as modified Rankin Scale score > 2. Early neurological deterioration (END) and hematoma growth (HG) were recorded at 24 h.

RESULTS

Patients had higher tenascin-C levels than controls. Tenascin-C levels were positively correlated with hematoma volume or National Institutes of Health Stroke Scale score at baseline. Elevated tenascin-C levels were independently associated with END, HG, 90-day mortality and poor functional outcome. Moreover, tenascin-C levels significantly predicted END, HG and 90-day outcomes under receiver operating characteristic curves.

CONCLUSIONS

An increase in serum tenascin-C level is associated with an adverse outcome in ICH patients, supporting the potential role of serum tenascin-C as a prognostic biomarker for hemorrhagic stroke.

Matricellular proteins as possible biomarkers for early brain injury after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage remains devastating, and the most important determinant of poor outcome is early brain injury (EBI). In clinical settings, as a surrogate marker of EBI, loss of consciousness at ictus, poor initial clinical grades, and some radiographic findings are used, but these markers are somewhat subjective. Thus, it is imperative to find biomarkers of EBI that have beneficial prognostic and therapeutic implications. In our opinion, an ideal biomarker is a molecule that is implicated in the pathogenesis of both EBI and subsequently developing delayed cerebral ischemia (DCI), being a therapeutic target, and can be measured easily in the peripheral blood in an acute stage. A good candidate of such a biomarker is a matricellular protein, which is a secreted, inducible and multifunctional extracellular matrix protein. There are many kinds of matricellular proteins reported, but only tenascin-C, osteopontin, galectin-3 and periostin are reported relevant to EBI and DCI. Reliable biomarkers of EBI may stratify aneurysmal subarachnoid hemorrhage patients into categories of risk to develop DCI, and allow objective monitoring of the response to treatment for EBI and earlier diagnosis of DCI. This review emphasizes that further investigation of matricellular proteins as an avenue for biomarker discovery is warranted.

Correlation of tenascin-C concentrations in serum with outcome of traumatic brain injury in humans

BACKGROUND

Tenascin-C, a matricellular protein, is involved in brain injury. However, change of tenascin-C concentrations in peripheral blood remains unknown after traumatic brain injury (TBI).

METHODS

Serum tenascin-C concentrations were measured in 100 healthy controls, 108 severe TBI patients, 79 moderate TBI patients and 32 mild TBI patients.

RESULTS

Serum tenascin-C concentrations of patients were significantly higher than those of controls. Tenascin-C concentrations negatively correlated with Glasgow Coma Scale (GCS) scores in all patients (r=-0.658, P<0.001). In severe TBI patients, tenascin-C in serum significantly discriminated patients at risk of 6-month mortality (area under curve, 0.821; 95% confidence interval, 0.735-0.888) and poor outcome (Glasgow Outcome Scale score of 1-3) (area under curve, 0.833; 95% confidence interval, 0.749-0.898) and emerged as an independent predictor for 6-month mortality (odds ratio, 1.114; 95% confidence interval, 1.008-1.233; P=0.005), overall survival (hazard ratio, 1.085; 95% confidence interval, 1.010-1.166; P=0.003) and unfavorable outcome (odds ratio, 1.049; 95% confidence interval, 1.014-1.076; P=0.001). By receiver-operating characteristic analysis, serum tenascin-C concentrations had similar prognostic value compared with GCS scores.

CONCLUSIONS

Enhanced serum tenascin-C concentrations are closely related to trauma severity and clinical outcomes, substantializing tenascin-C as a potential prognostic biomarker after TBI.

Preventive effects of cilostazol against the development of shunt-dependent hydrocephalus after subarachnoid hemorrhage

OBJECTIVE Chronic hydrocephalus develops in association with the induction of tenascin-C (TNC), a matricellular protein, after aneurysmal subarachnoid hemorrhage (SAH). The aim of this study was to examine if cilostazol, a selective inhibitor of phosphodiesterase Type III, suppresses the development of chronic hydrocephalus by inhibiting TNC induction in aneurysmal SAH patients. METHODS The authors retrospectively reviewed the factors influencing the development of chronic shunt-dependent hydrocephalus in 87 patients with Fisher Grade 3 SAH using multivariate logistic regression analyses. Cilostazol (50 or 100 mg administered 2 or 3 times per day) was administered from the day following aneurysmal obliteration according to the preference of the attending neurosurgeon. As a separate study, the effects of different dosages of cilostazol on the serum TNC levels were chronologically examined from Days 1 to 12 in 38 SAH patients with Fisher Grade 3 SAH. RESULTS Chronic hydrocephalus occurred in 12 of 36 (33.3%), 5 of 39 (12.8%), and 1 of 12 (8.3%) patients in the 0 mg/day, 100 to 200 mg/day, and 300 mg/day cilostazol groups, respectively. The multivariate analyses showed that older age (OR 1.10, 95% CI 1.13-1.24; p = 0.012), acute hydrocephalus (OR 23.28, 95% CI 1.75-729.83; p = 0.016), and cilostazol (OR 0.23, 95% CI 0.05-0.93; p = 0.038) independently affected the development of chronic hydrocephalus. Higher dosages of cilostazol more effectively suppressed the serum TNC levels through Days 1 to 12 post-SAH. CONCLUSIONS Cilostazol may prevent the development of chronic hydrocephalus and reduce shunt surgery, possibly by the inhibition of TNC induction after SAH.

The Role of Matricellular Proteins in Brain Edema after Subarachnoid Hemorrhage

Accumulated evidence suggests that blood-brain barrier disruption or brain edema is an important pathologic manifestation for poor outcome after aneurysmal subarachnoid hemorrhage. Many molecules may be involved, acting simultaneously or at different stages during blood-brain barrier disruption via multiple independent or interconnected signaling pathways. Matricellular protein is a class of nonstructural, secreted, and multifunctional extracellular matrix proteins, which potentially mediates brain edema formation. This study reviews the role of osteopontin and tenascin-C, representatives of matricellular proteins, in the context of brain edema formation after subarachnoid hemorrhage in both clinical and experimental settings.

Deficiency of tenascin-C and attenuation of blood-brain barrier disruption following experimental subarachnoid hemorrhage in mice

OBJECT Tenascin-C (TNC), a matricellular protein, is induced in the brain following subarachnoid hemorrhage (SAH). The authors investigated if TNC causes brain edema and blood-brain barrier (BBB) disruption following experimental SAH. METHODS C57BL/6 wild-type (WT) or TNC knockout (TNKO) mice were subjected to SAH by endovascular puncture. Ninety-seven mice were randomly allocated to WT sham-operated (n = 16), TNKO sham-operated (n = 16), WT SAH (n = 34), and TNKO SAH (n = 31) groups. Mice were examined by means of neuroscore and brain water content 24-48 hours post-SAH; and Evans blue dye extravasation and Western blotting of TNC, matrix metalloproteinase (MMP)-9, and zona occludens (ZO)-1 at 24 hours post-SAH. As a separate study, 16 mice were randomized to WT sham-operated, TNKO sham-operated, WT SAH, and TNKO SAH groups (n = 4 in each group), and activation of mitogen-activated protein kinases (MAPKs) was immunohistochemically evaluated at 24 hours post-SAH. Moreover, 40 TNKO mice randomly received an intracerebroventricular injection of TNC or phosphate-buffered saline, and effects of exogenous TNC on brain edema and BBB disruption following SAH were studied. RESULTS Deficiency of endogenous TNC prevented neurological impairments, brain edema formation, and BBB disruption following SAH; it was also associated with the inhibition of both MMP-9 induction and ZO-1 degradation. Endogenous TNC deficiency also inhibited post-SAH MAPK activation in brain capillary endothelial cells. Exogenous TNC treatment abolished the neuroprotective effects shown in TNKO mice with SAH. CONCLUSIONS Tenascin-C may be an important mediator in the development of brain edema and BBB disruption following SAH, mechanisms for which may involve MAPK-mediated MMP-9 induction and ZO-1 degradation. TNC could be a molecular target against which to develop new therapies for SAH-induced brain injuries.

Tenascin-C in development and disease of blood vessels

Tenascin-C (TNC) is an extracellular glycoprotein categorized as a matricellular protein. It is highly expressed during embryonic development, wound healing, inflammation, and cancer invasion, and has a wide range of effects on cell response in tissue morphogenesis and remodeling including the cardiovascular system. In the heart, TNC is sparsely detected in normal adults but transiently expressed at restricted sites during embryonic development and in response to injury, playing an important role in myocardial remodeling. Although TNC in the vascular system appears more complex than in the heart, the expression of TNC in normal adult blood vessels is generally low. During embryonic development, vascular smooth muscle cells highly express TNC on maturation of the vascular wall, which is controlled in a way that depends on the embryonic site of cell origin. Strong expression of TNC is also linked with several pathological conditions such as cerebral vasospasm, intimal hyperplasia, pulmonary artery hypertension, and aortic aneurysm/ dissection. TNC synthesized by smooth muscle cells in response to developmental and environmental cues regulates cell responses such as proliferation, migration, differentiation, and survival in an autocrine/paracrine fashion and in a context-dependent manner. Thus, TNC can be a key molecule in controlling cellular activity in adaptation during normal vascular development as well as tissue remodeling in pathological conditions.

Tenascin-C is a possible mediator between initial brain injury and vasospasm-related and -unrelated delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

INTRODUCTION

Tenascin-C (TNC), a matricellular protein, exerts diverse functions, including tissue remodeling and apoptosis, and is induced in cerebrospinal fluid (CSF) after aneurysmal subarachnoid hemorrhage (SAH). The purpose of this study was to examine the relationships among CSF TNC levels, initial brain injury, delayed cerebral ischemia (DCI), and vasospasm after SAH.

METHODS

CSF TNC levels were measured in 30 patients with aneurysmal SAH of Fisher computed tomography (CT) group III who were treated microsurgically or endovascularly with CSF drainage within 24 h of SAH. Admission World Federation of Neurosurgical Societies (WFNS) grade was supposed to indicate the severity of initial brain injury. Cerebral vasospasm was defined as narrowed (≥ 25 %) cerebral arteries demonstrated by angiography. DCI was defined as any neurological deterioration presumed related to ischemia that persisted for ≥ 1 h.

RESULTS

Higher CSF TNC levels were correlated with worse admission WFNS grades. Vasospasm was aggravated with higher TNC levels. DCI occurred regardless of the degree of vasospasm but was associated with TNC induction. Multivariate analyses showed that higher TNC levels and vasospasm were independent predictors of DCI occurrence.

CONCLUSIONS

SAH (initial brain injury) that is more severe induces more TNC, which may cause the subsequent development of both vasospasm and vasospasm-unrelated secondary brain injury, leading to DCI.

Effects of tenascin-C on early brain injury after subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

We previously reported that tenascin-C (TNC), a matricellular protein, was involved in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH), but the role of TNC in early brain injury (EBI) is unknown. This study assessed whether inhibition of TNC upregulation in brain by imatinib mesylate (imatinib), an inhibitor of the tyrosine kinases of platelet-derived growth factor receptors, prevents EBI after experimental SAH.

METHODS

Rats were assigned to sham, SAH plus vehicle, and SAH plus imatinib groups (n = 4 per group). Imatinib (50 mg/kg body weight) was administered intraperitoneally to rats undergoing SAH by endovascular perforation, and EBI was evaluated using terminal deoxynucleotidyl transferase-mediated uridine 5-triphosphate-biotin nick end-labeling staining at 24 h after SAH. Imatinib-treated SAH rats were also treated by a cisternal injection of recombinant TNC.

RESULTS

SAH upregulated TNC and caused EBI. Imatinib treatment suppressed both TNC upregulation and EBI at 24 h. Recombinant TNC reinduced EBI in imatinib-treated SAH rats.

CONCLUSIONS

TNC may be involved in the pathogenesis of EBI after SAH.

Vasoconstrictive effect of tenascin-C on cerebral arteries in rats

BACKGROUND AND PURPOSE

The authors have reported that tenascin-C (TNC), a matricellular protein, is induced after subarachnoid hemorrhage (SAH), associated with cerebral vasospasm. In this study, we examined whether TNC alone causes cerebral vasospasm-like constriction of the intracranial internal carotid arteries (ICAs) in rats, focusing on the p38 mitogen-activated protein kinase (MAPK)-mediated mechanisms.

METHODS

First, we injected 10 μg of TNC into the cisterna magna of healthy rats and studied morphologically whether TNC caused constriction of the left ICA at 24-72 h after administration. Second, we examined the effect of SB203580 (a p38 MAPK inhibitor) on the vessel diameter of the left ICA in healthy rats at 24 h. Third, we evaluated the effect of SB203580 on TNC-induced constriction of the left ICA in healthy rats at 24 h.

RESULTS

TNC significantly induced cerebral vasospasm-like angiographic constriction of the left ICAs, which continued at least for 72 h. SB203580 itself had no effect on the diameter of normal ICAs, but abolished the TNC-induced vasoconstrictive effect on the left ICA.

CONCLUSION

These findings show that TNC causes left ICA constriction via activation of p38 MAPK, resembling post-SAH vasospasm, and suggest the possible involvement of TNC in the pathogenesis of cerebral vasospasm.

Tenascin-C causes neuronal apoptosis after subarachnoid hemorrhage in rats

The role of tenascin-C (TNC), a matricellular protein, in brain injury is unknown. The aim of this study was to examine if TNC causes neuronal apoptosis after subarachnoid hemorrhage (SAH), a deadly cerebrovascular disorder, using imatinib mesylate (a selective inhibitor of platelet-derived growth factor receptor [PDGFR] that is reported to suppress TNC induction) and recombinant TNC. SAH by endovascular perforation caused caspase-dependent neuronal apoptosis in the cerebral cortex irrespective of cerebral vasospasm development at 24 and 72 h post-SAH, associated with PDGFR activation, mitogen-activated protein kinases (MAPKs) activation, and TNC induction in rats. PDGFR inactivation by an intraperitoneal injection of imatinib mesylate prevented neuronal apoptosis, as well as MAPKs activation and TNC induction in the cerebral cortex at 24 h. A cisternal injection of recombinant TNC reactivated MAPKs and abolished anti-apoptotic effects of imatinib mesylate. The TNC injection also induced TNC itself in SAH brain, which may internally augment neuronal apoptosis after SAH. These findings suggest that TNC upregulation by PDGFR activation causes neuronal apoptosis via MAPK activation, and that the positive feedback mechanisms may exist to augment neuronal apoptosis after SAH. TNC-induced neuronal apoptosis would be a new target to improve outcome after SAH.

Tenascin-C induces prolonged constriction of cerebral arteries in rats

Tenascin-C (TNC), a matricellular protein, is induced in association with cerebral vasospasm after subarachnoid hemorrhage. The aim of this study was to assess the vasoconstrictive effects of TNC and its mechanisms of action on cerebral arteries in vivo. Two dosages (1 and 10μg) of TNC were administered intracisternally to healthy rats, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24, 48, and 72h after the administration. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms on constricted cerebral arteries after 24h. The effects of toll-like receptor 4 (TLR4) antagonists (LPS-RS), c-Jun N-terminal kinase (JNK), and p38 inhibitors (SP600125 and SB203580) on TNC-induced vasoconstriction were evaluated at 24h. Higher dosages of TNC induced more severe cerebral arterial constriction, which continued for more than 72h. TNC administration also upregulated TLR4, and activated JNK and p38 in the smooth muscle cell layer of the constricted cerebral artery. LPS-RS blocked TNC-induced TLR4 upregulation, JNK and p38 activation, and vasoconstrictive effects. SP600125 and SB203580 abolished TNC-induced TLR4 upregulation and vasoconstrictive effects. TNC may cause prolonged cerebral arterial constriction via TLR4 and activation of JNK and p38, which may upregulate TLR4. These findings suggest that TNC causes cerebral vasospasm and provides a novel therapeutic approach against it.

Advances in tenascin-C biology

Tenascin-C is an extracellular matrix glycoprotein that is specifically and transiently expressed upon tissue injury. Upon tissue damage, tenascin-C plays a multitude of different roles that mediate both inflammatory and fibrotic processes to enable effective tissue repair. In the last decade, emerging evidence has demonstrated a vital role for tenascin-C in cardiac and arterial injury, tumor angiogenesis and metastasis, as well as in modulating stem cell behavior. Here we highlight the molecular mechanisms by which tenascin-C mediates these effects and discuss the implications of mis-regulated tenascin-C expression in driving disease pathology.

The role of tenascin C in cardiovascular disease

The extracellular matrix protein tenascin C (TnC) is expressed in a variety of embryonic tissues, but its expression in adult arteries is co-incident with sites of vascular disease. TnC expression has been linked to the development and complications of intimal hyperplasia, pulmonary artery hypertension, atherosclerosis, myocardial infarction, and heart failure. This review identifies the growing collection of evidence linking TnC with cardiovascular disease development. The transient upregulation of this extracellular matrix protein at sites of vascular disease could provide a means to target TnC in the development of diagnostics and new therapies. Studies in TnC-deficient mice have implicated this protein in the development of intimal hyperplasia. Further animal and human studies are required to thoroughly assess the role of TnC in some of the other pathologies it has been linked with, such as atherosclerosis and pulmonary hypertension. Large population studies are also warranted to clarify the diagnostic value of this extracellular matrix protein in cardiovascular disease, for example by targeting its expression using radiolabelled antibodies or measuring circulating concentrations of TnC.