Tenascin-C (TN-C) is an extracellular matrix glycoprotein with high bioactivity. It is expressed at low levels in normal adult heart, but upregulated under pathological conditions, such as myocardial infarction (MI). Recently, we (Ref. 34) reported that MI patients with high serum levels of TN-C have a greater incidence of maladaptive cardiac remodeling and a worse prognosis. We hypothesized that TN-C may aggravate left ventricular remodeling. To examine the effects of TN-C, MI was induced by ligating coronary arteries of TN-C knockout (KO) mice under anesthesia and comparing them with sibling wild-type (WT) mice. In WT+MI mice, TN-C expression was upregulated at day 1, peaked at day 5, downregulated and disappeared by day 28, and the molecule was localized in the border zone between intact myocardium and infarct lesions. The morphometrically determined infarct size and survival rate on day 28 were comparable between the WT+MI and KO+MI groups. Echocardiography and hemodynamic analyses demonstrated left ventricular end-diastolic diameter, myocardial stiffness, and left ventricular end-diastolic pressure to be significantly increased in both WT+MI and KO+MI mice compared with sham-operated mice. However, end-diastolic pressure and dimension and myocardial stiffness of KO+MI were lower than those of the WT+MI mice. Histological examination revealed normal tissue healing, but interstitial fibrosis in the residual myocardium in peri-infarcted areas was significantly less pronounced in KO+MI mice than in WT+MI mice. TN-C may thus accelerate adverse ventricular remodeling, cardiac failure, and fibrosis in the residual myocardium after MI.

Abstract--Tenascin-C (TN-C) is an extracellular matrix protein not detected in normal adult heart, but expressed in several heart diseases closely associated with inflammation. Accumulating data suggest that TN-C may play a significant role in progression of ventricular remodeling. In this study, we aimed to elucidate the role of TN-C in hypertensive cardiac fibrosis and underlying molecular mechanisms. Angiotensin II was administered to wild-type and TN-C knockout mice for 4 weeks. In wild-type mice, the treatment induced increase of collagen fibers and accumulation of macrophages in perivascular areas associated with deposition of TN-C and upregulated the expression levels of interleukin-6 and monocyte chemoattractant protein-1 as compared with wild-type/control mice. These changes were significantly reduced in TN-C knockout/angiotensin II mice. In vitro, TN-C accelerated macrophage migration and induced accumulation of integrin αVβ3 in focal adhesions, with phosphorylation of focal adhesion kinase (FAK) and Src. TN-C treatment also induced nuclear translocation of phospho-NF-κB and upregulated interleukin-6 expression of macrophages in an NF-κB-dependent manner; this being suppressed by inhibitors for integrin αVβ3 and Src. Furthermore, interleukin-6 upregulated expression of collagen I by cardiac fibroblasts. TN-C may enhance inflammatory responses by accelerating macrophage migration and synthesis of proinflammatory/profibrotic cytokines via integrin αVβ3/FAK-Src/NF-κB, resulting in increased fibrosis. (Hypertension.2015;66:757-766.

aaUrban areas have been polluted heavily by nitrogen dioxide (NO 2 ) and suspended particulate matters (SPM) [1]. The primary source of NO 2 and SPM in urban areas is vehicle emissions. The ratio of vehicle emission to total oxides of nitrogen (NO x ) exhausts in Tokyo and Osaka in 1990 were 70% and 56%, respectively [2]. The number of diesel-powered cars has been increasing, and diesel vehicles emit more NO 2 and particulates than petrol-engined cars. Therefore, the ratio of diesel exhaust particles (DEP) to SPM is very high in urban air; in Tokyo in 1989 it was at least 40% [2]. DEP contains elemental carbon nuclei that adsorb a variety of organic compounds and a trace amount of heavy metals. Some of these organic compounds are strong mutagens and carcinogens [3][4][5]. It has been established that DEP causes lung tumours in a dosedependent manner [6].It has been shown that the prevalence of allergic rhinitis among schoolchildren is significantly higher in districts polluted by automobile exhaust than in nonpolluted districts [7]. Although, there have been numerous attempts to demonstrate the relationship between NO 2 and bronchial asthma, no direct link has been demonstrated experimentally. Furthermore, no experimental study has addressed the relationship between DEP and asthma. A previous report from our laboratory showed that repeated intratracheal instillations of DEP in mice induced chronic airway inflammation with infiltration of eosinophils and lymphocytes, and airway hyperresponsiveness with hypersecretion of mucus [8].It is clear in allergic diseases such as asthma that allergen-specific immunoglobulin (Ig) E plays a central role in hypersensitivity reactions, and that the IgE-mediated reactions are followed by chronic inflammation leading to increased airway responsiveness. It has also been shown that DEP has adjuvant effects on IgE production in mice in cases of allergic rhinitis [9]. Intranasal instillation of DEP and antigen induced an increase of antigen-specific IgE antibody in mouse sera [10]. However, some observations suggest the existence of alternative and/or additional pathways of hypersensitivity reactions. Firstly, allergeninduced bronchial hyperreactivity and eosinophilic inflammation occur in IgE and mast cell-deficient mice [11,12]. Secondly, immediate hypersensitivity and airway hyperresponsiveness were induced by the administration of ovalbumin (OVA)-specific IgE or IgG1, but not IgG2a or IgG3 [13]. We developed a murine asthma model by intratracheal instillation of DEP and OVA, and found that DEP enhanced the production of allergen specific IgG1, airway inflammation and airway hyperresponsiveness, before it enhanced IgE production [14]. Thus, both IgG and IgE antibodies are involved in allergic airway inflammation and airway hyperresponsiveness in that murine model of asthma. Both mouse strains received DEP intratracheally once a week for 5 weeks. After the second injection of DEP, ovalbumin and aluminium hydroxide were injected intraperitoneally. After the last DEP administration,...

A neurysmAl subarachnoid hemorrhage (SAH) is one of the most life-threatening cerebrovascular disorders, with high mortality and morbidity rates. 26,33 Delayed cerebral ischemia (DCI) remains the most important cause of morbidity and mortality in those patients who survive the initial bleeding. 20 Recent studies have reported that early brain injury (EBI), as well as cerebral vasospasm, is a major cause of DCI following SAH. 20EBI occurs before the onset of cerebral vasospasm and may cause DCI with no significant vasospasm. 3 Brain edema, which results mainly from blood-brain barrier (BBB) disruption, 18 plays an important role in the pathological abbreviatioNs BBB = blood-brain barrier; DCI = delayed cerebral ischemia; EBI = early brain injury; ERK = extracellular signal-regulated kinase; ICA = internal carotid artery; JNK = c-Jun N-terminal kinase; MAPK = mitogen-activated protein kinase; MMP = matrix metalloproteinase; PBS = phosphate-buffered saline; PDGF = plateletderived growth factor; SAH = subarachnoid hemorrhage; TNC = tenascin-C; TNKO = TNC knockout; WT = wild-type; ZO = zona occludens. obJective 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.

Migration and proliferation of smooth muscle cells (SMCs) are key events during neointimal formation in pathological conditions of vessels. Tenascin-C (TNC) is upregulated in the developing neointima of lesions. We evaluated the effects of TNC on responses of SMCs against platelet-derived growth factor (PDGF) stimulation. TNC coated on substrate promoted PDGF-BB-induced proliferation and migration of rat SMC cell line A10 in BrdU incorporation and transwell assays, respectively. Immunoblotting showed that TNC substrate enhanced autophosphorylation of PDGFR-β after PDGF-BB stimulation. Integrin αvβ3 is known to be a receptor for TNC in SMCs. In immunofluorescence and immunoblot of integrin αv subunit, clustering of αv-positive focal adhesions and upregulated αv expression were observed in the cells on TNC substrate. Immunoprecipitation using anti-integrin αvβ3 antibody demonstrated that PDGFR-β and integrin αvβ3 were co-precipitated and that the relative amount of PDGFR-β after the stimulation was increased by TNC treatment. TNC also promoted phosphorylation of focal adhesion kinase (FAK) at tyrosine (Y) 397 and Y925. The phosphorylated FAK was localized at focal adhesions in immunofluorescence. Phosphorylated SRC at Y418 was also seen at focal adhesions. Immunoprecipitation with αv antibody showed increased SRC association with the integrin signaling complex in the cells on TNC after PDGF treatment. In the cells on TNC substrate, crosstalk signaling between integrin αvβ3 and PDGFR-β could be amplified by SRC and FAK recruited to focal adhesions, followed by enhanced proliferation and migration of A10 cells by PDGF-BB.