Masato Shiba

Imatinib mesylate prevents cerebral vasospasm after subarachnoid hemorrhage via inhibiting tenascin-C expression in rats.

Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH), but the mechanism remains unknown. The purpose of this study was to assess whether imatinib mesylate (imatinib), an inhibitor of the tyrosine kinases of PDGF receptors (PDGFRs), prevents cerebral vasospasm after SAH in rats, and to elucidate if tenascin-C (TNC), a matricellular protein, is involved in the mechanism. Imatinib (10 or 50 mg/kg body weight) was administered intraperitoneally to rats undergoing SAH by endovascular perforation, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24-72 h post-SAH. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms in cerebral arteries at 24h post-SAH. Recombinant TNC was administered intracisternally to imatinib-treated SAH rats, and the effects were evaluated by neurobehavioral tests, India-ink angiography and immunohistochemistry at 24 h post-SAH. Both dosages of imatinib significantly prevented post-SAH neurological impairments and vasospasm at 24-72 h. SAH caused PDGFR-β upregulation, PDGFR activation, mitogen-activated protein kinase activation, and TNC upregulation in the spastic cerebral arteries, all of which were significantly suppressed by imatinib treatment. Recombinant TNC reversed the anti-vasospastic effects and protein expression changes by imatinib. This study suggests that imatinib prevents cerebral vasospasm at least partly via inhibiting the upregulation of TNC, implying that TNC may be a new therapeutic target for post-SAH vasospasm.

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.

Cerebrospinal fluid tenascin-C in cerebral vasospasm after aneurysmal subarachnoid hemorrhage.

Background: Tenascin-C (TNC) has been reported to be a useful biomarker for the activity of inflammatory diseases. This study investigated the association between TNC levels in the cerebrospinal fluid (CSF) and symptomatic vasospasm after aneurysmal subarachnoid hemorrhage (SAH), and the prognostic value of TNC levels. Methods: TNC levels were measured in CSF in 33 consecutive patients diagnosed with aneurysmal SAH of Fisher computed tomography group III and were compared between those with and without subsequent cerebral vasospasm. Factors influencing symptomatic vasospasm were determined using multivariate logistic regression analyses. The receiver-operating characteristic curve technique was used to assess specificity and sensitivity in the prediction of symptomatic vasospasm. Results: The CSF TNC levels peaked immediately after SAH and were significantly higher in patients who subsequently developed symptomatic vasospasm than in those who did not. On multivariate analyses, higher TNC levels in the CSF (odds ratio, 1.059; 95% confidence interval, 1.023-1.096; P<0.001) and World Federation of Neurosurgical Societies grades IV to V on admission (odds ratio, 3.238; 95% confidence interval, 1.033-10.152; P<0.05) significantly predicted symptomatic vasospasm. To predict the onset of symptomatic vasospasm, 16.2 ng/mL was considered as an appropriate cut-off value for CSF TNC on days 1 through 6, giving a sensitivity of 81.0% and a specificity of 79.5% (negative and positive predictive values: 82.3% and 76.7%, respectively). Conclusions: TNC in the CSF may be a useful biomarker for predicting subsequent development of cerebral vasospasm.

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.

Role of Platelet-Derived Growth Factor in Cerebral Vasospasm After Subarachnoid Hemorrhage in Rats

BACKGROUND AND PURPOSE The role of platelet-derived growth factor (PDGF) remains unknown in cerebral vasospasm after subarachnoid hemorrhage (SAH). In this study, we examined the effects of PDGF receptor (PDGFR) inactivation on cerebral vasospasm in the endovascular perforation model of SAH in rats. METHODS Rats were assigned to sham, SAH plus vehicle, and SAH plus imatinib mesylate (imatinib) groups (n = 4 per group). Imatinib (50 mg/kg body weight), an inhibitor of the tyrosine kinases of PDGFR, or vehicle was administered intraperitoneally 30 min post-SAH. Vasospasm was evaluated in the left (perforation-sided) internal carotid artery by means of neurobehavioral tests, India ink angiography, and immunohistochemistry at 24 h after SAH. RESULTS Imatinib significantly inhibited post-SAH PDGFR activation in the left internal carotid artery, in which vasospasm was significantly prevented. Animals neurobehavior also showed a tendency to improve by imatinib treatment. CONCLUSIONS PDGF may play an important role in the pathogenesis of vasospasm after SAH.

Stagnation and complex flow in ruptured cerebral aneurysms: a possible association with hemostatic pattern.

OBJECT Histopathological examination has revealed that ruptured cerebral aneurysms have different hemostatic patterns depending on the location of the clot formation. In this study, the authors investigated whether the hemostatic patterns had specific hemodynamic features using computational fluid dynamics (CFD) analysis. METHODS Twenty-six ruptured middle cerebral artery aneurysms were evaluated by 3D CT angiography and harvested at the time of clipping. The hemostatic patterns at the rupture points were assessed by means of histopathological examination, and morphological parameters were obtained. Transient analysis was performed, and wall shear stress-related hemodynamic parameters and invariant Q (vortex core region) were calculated. The morphological and hemodynamic parameters were compared among the hemostatic patterns. RESULTS Hematoxylin and eosin staining of the aneurysm wall showed 13 inside-pattern, 9 outside-pattern, and 4 other-pattern aneurysms. Three of the 26 aneurysms were excluded from further analysis, because their geometry models could not be generated due to low vascular CT values. Mann-Whitney U-tests showed that lower dome volume (0.04 cm3 vs 0.12 cm3, p = 0.014), gradient oscillatory number (0.0234 vs 0.0289, p = 0.023), invariant Q (-0.801 10-2/sec2 vs -0.124 10-2/sec2, p = 0.045) and higher aneurysm formation indicator (0.986 vs 0.963, p = 0.041) were significantly related to inside-pattern aneurysms when compared with outside-pattern aneurysms. CONCLUSIONS Inside-pattern aneurysms may have simpler flow patterns and less flow stagnation than outside-pattern aneurysms. CFD may be useful to characterize the hemostatic pattern of ruptured cerebral aneurysms.

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.

Matricellular Protein: A New Player in Cerebral Vasospasm Following Subarachnoid Hemorrhage

INTRODUCTION Matricellular protein (MCP) is a class of nonstructural and secreted extracellular matrix proteins that exert diverse functions, but its role in vascular smooth muscle contraction has not been investigated. MATERIAL AND METHODS First, rat subarachnoid hemorrhage (SAH) models were produced by endovascular perforation and examined for tenascin-C (TNC) and osteopontin (OPN) induction (representatives of MCPs) in vasospastic cerebral arteries using immunostaining. Second, recombinant TNC (r-TNC), recombinant OPN (r-OPN), or both were injected into a cisterna magna in healthy rats, and the effects on the diameter of basilar arteries were determined using India ink angiography. RESULTS In SAH rats, TNC immunoreactivity was markedly induced in the smooth muscle cell layers of spastic cerebral arteries on day 1 but not in control animals. The TNC immunoreactivity decreased on day 3 as vasospasm improved: OPN immunoreactivity, on the other hand, was more induced in the arterial wall on day 3. r-TNC injections caused prolonged contractions of rat basilar arteries, which were reversed by r-OPN, although r-OPN itself had no effect on the vessel diameter. CONCLUSIONS MCPs, including TNC and OPN, may contribute to the pathophysiology of cerebral vasospasm and provide a novel therapeutic approach against it.

Epidermal growth factor-like repeats of tenascin-C-induced constriction of cerebral arteries via activation of epidermal growth factor receptors in rats.

Tenascin-C (TNC), one of matricellular proteins, has been suggested to be involved in cerebral vasospasm after aneurysmal subarachnoid hemorrhage. However, the mechanisms of how TNC constricts cerebral arteries remain unclear. The aim of this study was to examine if epidermal growth factor (EGF)-like repeats of TNC is involved in TNC-induced constriction of cerebral arteries in rats via EGF receptor (EGFR) activation. Two dosages of recombinant TNC (r-TNC) consisting of the EGF-like repeats was administered intracisternally to healthy rats, and its vasoconstrictor effects were evaluated by neurobehavioral tests and India-ink angiography at 24, 48, and 72 hours after the administration. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms on constricted cerebral arteries after 24 hours. The effects of a selective EGFR tyrosine kinase inhibitor (AG1478) on r-TNC-induced vasoconstriction were evaluated by neurobehavioral tests, India-ink angiography and immunohistochemistry at 24 hours after the administration. A higher dosage of r-TNC induced cerebral arterial constriction more severely, which continued for 48 hours. The effects were associated with the activation of EGFR and extracellular signal-regulated kinase (ERK)1/2 in the smooth muscle cell layer of the constricted cerebral artery, while c-Jun N-terminal kinase and p38 were not activated. AG1478 blocked r-TNC-induced vasoconstrictive effects, as well as activation of EGFR and ERK1/2. These findings demonstrate that TNC induces constriction of cerebral arteries via activation of EGFR and ERK1/2.

A Case of Moyamoya Disease with a Transient Neurologic Deterioration Associated with Subcortical Low Intensity on Fluid-Attenuated Inversion Recovery Magnetic Resonance Images After Bypass Surgery

BACKGROUND Moyamoya disease often is treated by revascularization surgery. In this report, we are the first to describe a case of moyamoya disease that repeatedly showed a transient subcortical low intensity (SCLI) on fluid-attenuated inversion recovery (FLAIR) magnetic resonance images postoperatively. CASE DESCRIPTION A 59-year-old woman presenting with repeated transient ischemia underwent right superficial temporal artery to middle cerebral artery anastomosis with encephalo-duro-myo-synangiosis. After the operation, the patient had a transient neurologic deterioration. Findings on magnetic resonance imaging were not particular apart from SCLI and sulcal hyperintensity on FLAIR images, but no abnormalities in cerebral blood flow on single-photon emission computed tomography with N-isopropyl [123I]-p-iodoamphetamine and no abnormalities on electroencephalogram were found. Symptoms improved in a few days, and SCLI on FLAIR images disappeared in a few months. Thereafter, when the left-sided bypass surgery was performed, similar findings occurred in the left cerebral hemisphere. CONCLUSIONS The mechanisms of transient SCLI on FLAIR images remain unclear, but this finding appears to be associated with a postoperative transient neurologic deterioration.