Junko Maruyama

Deficiency of tenascin C attenuates allergen-induced bronchial asthma in the mouse

Tenascin C (TN‐C) is an extracellular matrix glycoprotein whose expression is increased in several inflammatory diseases of the lung, including bronchial asthma. However, the exact function of TN‐C in the pathogenesis of lung inflammation remains unclear. In the present study, we compared the degree of bronchial asthma in wild‐type and TN‐C‐deficient (–/–) BALB/c mice. Bronchial asthma was induced by sensitization and challenge with ovalbumin. Littermates treated with saline were used as controls. Cytokines in bronchoalveolar lavage fluid and plasma were measured by enzyme immunoassays. The number of eosinophils in the lung was significantly increased in wild‐type mice compared with TN‐C‐knockout mice. Airway hyperreactivity, NF‐κB activation and concentrations of monocyte chemoattractant protein‐1, IL‐5, IL‐13, metalloproteinase‐9 and immunoglobulin‐E in the bronchoalveolar lavage fluid were significantly decreased in ovalbumin‐sensitized/challenged TN‐C‐knockout mice compared with their wild‐type counterparts. In vitro experiments disclosed that TN‐C significantly stimulates the secretion of IL‐5, IL‐13, IFN‐γ and immunoglobulin‐E from spleen lymphocytes. These observations suggest that TN‐C is involved in the pathogenesis of bronchial asthma.

Vasodilatory Effects of Ketamine on Pulmonary Arteries in Rats with Chronic Hypoxic Pulmoanry Hypertension

To study the effects of ketamine on structurally remodeled pulmonary arteries from rats with hypoxic pulmonary hypertension (PH) and the effects of ketamine on endothelium-dependent and -independent relaxation, rats were exposed to hypobaric hypoxia (air at 380 mm Hg for 10 days). We measured the responses to ketamine, acetylcholine, and sodium nitroprusside (SNP) in prostaglandin F2 alpha-precontracted ring segments from a left extrapulmonary artery (EPA, 1.4-1.6 mm in outside diameter [OD]) and an intrapulmonary artery (IPA, 0.7-1.1 mm OD) obtained from control and PH rats. The effects of acetylcholine and SNP were decreased in EPA and IPA rings from PH rats compared with control rings. In contrast, ketamine produced a greater relaxation response in rings from PH rats at 3 times 10-5 -3 times 10-4 in the EPA and at 10-4 -10-3 M in the IPA compared to control rings. A nitric oxide synthase inhibitor, nitro-L-arginine (10-4 M), inhibited the relaxation in response to acetylcholine in both control and PH rats. Pretreatment with ketamine (10-4 M) had no effect on the relaxation response to any concentration of acetylcholine or SNP in either control or PH rats. We conclude that nitric-oxide-mediated relaxation, but not ketamine-induced relaxation, was impaired in structurally remodeled hypertensive pulmonary arteries. Ketamine had no effects on nitric oxide-mediated relaxation in either normal or PH rats. (Anesth Analg 1995;80:786-92)

Persistent Release of IL-1s from Skin Is Associated with Systemic Cardio-Vascular Disease, Emaciation and Systemic Amyloidosis: The Potential of Anti-IL-1 Therapy for Systemic Inflammatory Diseases

The skin is an immune organ that contains innate and acquired immune systems and thus is able to respond to exogenous stimuli producing large amount of proinflammatory cytokines including IL-1 and IL-1 family members. The role of the epidermal IL-1 is not limited to initiation of local inflammatory responses, but also to induction of systemic inflammation. However, association of persistent release of IL-1 family members from severe skin inflammatory diseases such as psoriasis, epidermolysis bullosa, atopic dermatitis, blistering diseases and desmoglein-1 deficiency syndrome with diseases in systemic organs have not been so far assessed. Here, we showed the occurrence of severe systemic cardiovascular diseases and metabolic abnormalities including aberrant vascular wall remodeling with aortic stenosis, cardiomegaly, impaired limb and tail circulation, fatty tissue loss and systemic amyloid deposition in multiple organs with liver and kidney dysfunction in mouse models with severe dermatitis caused by persistent release of IL-1s from the skin. These morbid conditions were ameliorated by simultaneous administration of anti-IL-1α and IL-1β antibodies. These findings may explain the morbid association of arteriosclerosis, heart involvement, amyloidosis and cachexia in severe systemic skin diseases and systemic autoinflammatory diseases, and support the value of anti-IL-1 therapy for systemic inflammatory diseases.

Protective role of protein C inhibitor in monocrotaline-induced pulmonary hypertension

Summary.  Background: Protein C inhibitor (PCI) plays a role in multiple biological processes including fertilization, coagulation, fibrinolysis and kinin systems. Objectives: We hypothesized that PCI participates in the pathogenesis of pulmonary hypertension. To demonstrate this, we compared the development of pulmonary hypertension in mice overexpressing PCI in the lung with wild‐type (WT) mice. Pulmonary hypertension was induced by s.c. injection of 600 mg kg−1 of monocrotaline weekly for 8 weeks. Results: Right ventricular arterial pressure was significantly increased in monocrotaline‐treated WT mice compared with that in monocrotaline‐treated transgenic mice. Bronchoalveolar lavage fluid (BALF) levels of thrombin–antithrombin complex, monocyte chemoattractant protein‐1 and platelet‐derived growth factor, and the plasma level of tumor necrosis factor‐α were significantly increased in monocrotaline‐treated WT mice as compared with monocrotaline‐treated PCI transgenic mice. Increased level of PCI‐thrombin complex was detected in BALF from monocrotaline‐treated PCI transgenic mice as compared with saline‐treated PCI transgenic mice. Conclusions: This study showed that increased expression of PCI in the lung is protective against monocrotaline‐induced pulmonary hypertension, suggesting a potential beneficial effect of PCI for the therapy of this disease.

Correlation of inhaled nitric-oxide induced reduction of pulmonary artery pressure and vascular changes

The purpose of the present study was to determine the relationship between hypertensive pulmonary vascular remodelling and the changes in mean pulmonary artery pressure (mPAP) during low-dose nitric oxide (NO) inhalation. Rats were exposed to chronic hypobaric hypoxia (air at 50.5 kPa (380 mmHg), 10% oxygen, for 5–29 days) to induce chronic pulmonary hypertension (PH) with pulmonary vascular structural changes. After the chronic hypoxic exposure, the rats had an indwelling pulmonary artery catheter inserted and changes in mPAP with NO were correlated to morphometrical analysis of pulmonary vascular changes. All concentrations of inhaled NO (0.1–2.0 parts per million) reduced mPAP with a similar per cent reduction from baseline mPAP in PH rats, while no changes were observed in control rats. During NO inhalation in PH rats, the absolute value of the decrease in mPAP, but not per cent reduction in mPAP, significantly correlated with baseline mPAP, the percentage of muscularised arteries at the alveolar wall level and at the alveolar duct level, and the per cent medial wall thickness of muscularised arteries. In the chronic hypoxic pulmonary hypertension model, the severity of pulmonary vascular remodelling did not alter the reactivity of the pulmonary arteries to nitric oxide and might, in part, determine the magnitude of nitric-oxide induced absolute reduction in mean pulmonary artery pressure.

Role of nitric oxide in pathophysiology and treatment of pulmonary hypertension.

Pulmonary hypertension is a condition characterized by vasoconstriction, vascular cell proliferation, inflammation, microthrombosis, and vessel wall remodelation. Pulmonary endothelial cells produce vasoactive substances with vasoconstrictive as well as vasodilatative effects. The imbalance of these endothelium-derived vasoactive substances induced by endothelial dysfunction is very important in the pathogenesis of PH. One of most important substances with vasodilatative effect is nitric oxide. We provide a comprehensive insight into role of NO in the pathgenesis of PH and discuss perspectives and challenges in PH therapy based on NO administration.

Atrial natriuretic peptide gene transfection with a novel envelope vector system ameliorates pulmonary hypertension in rats

OBJECTIVES A novel hemagglutinating virus of Japan (HVJ, a murine parainfluenza virus) envelope vector system, in which DNA is incorporated into an inactivated viral particle deprived of its genome, was recently developed as a ready-to-use vector for gene therapy. We therefore investigated whether intratracheal gene transfer using this vector can induce transgene expression in the lung and whether atrial natriuretic peptide gene transfer ameliorates pulmonary hypertension in rats. METHODS Rats transfected intratracheally with beta-galactosidase vector, atrial natriuretic peptide vector, or mock vector were investigated for the evaluation of beta-galactosidase expression, atrial natriuretic peptide mRNA expression, and inflammatory cell infiltration. Rats were divided into 5 treatment groups (n = 73): normoxic rats treated intratracheally with mock vector or atrial natriuretic peptide gene and chronic hypoxic rats treated similarly with mock vector, atrial natriuretic peptide, or a reporter gene, beta-galactosidase. Pulmonary hypertension and transfected gene expression were evaluated. RESULTS Beta-galactosidase gene transfer induced its intense enzymatic activity in bronchial and alveolar epithelial cells but not in other organs in normoxic rats. Transfected lungs were not associated with inflammatory cell infiltration. Atrial natriuretic peptide gene transfection inhibited pulmonary hypertension, which is associated with its mRNA expression in the lungs. Indices of right ventricular hypertrophy and pulmonary vascular diseases induced by chronic hypoxia were significantly but incompletely ameliorated. CONCLUSIONS HVJ-envelope vector is an efficient, relatively safe, and ready-to-use gene delivery system for pulmonary vascular diseases. Atrial natriuretic peptide gene transfer to lungs by using this vector could be a promising therapeutic approach against pulmonary hypertension.

Adjuvant Cardioprotection in Cardiac Surgery: Update

Cardiac surgery patients are now more risky in terms of age, comorbidities, and the need for complex procedures. It brings about reperfusion injury, which leads to dysfunction and/or loss of part of the myocardium. These groups of patients have a higher incidence of postoperative complications and mortality. One way of augmenting intraoperative myocardial protection is the phenomenon of myocardial conditioning, elicited with brief nonlethal episodes of ischaemia-reperfusion. In addition, drugs are being tested that mimic ischaemic conditioning. Such cardioprotective techniques are mainly focused on reperfusion injury, a complex response of the organism to the restoration of coronary blood flow in ischaemic tissue, which can lead to cell death. Extensive research over the last three decades has revealed the basic mechanisms of reperfusion injury and myocardial conditioning, suggesting its therapeutic potential. But despite the enormous efforts that have been expended in preclinical studies, almost all cardioprotective therapies have failed in the third phase of clinical trials. One reason is that evolutionary young cellular mechanisms of protection against oxygen handling are not very robust. Ischaemic conditioning, which is among these, is also limited by this. At present, the prevailing belief is that such options of treatment exist, but their full employment will not occur until subquestions and methodological issues with the transfer into clinical practice have been resolved.

Role of thrombin in interleukin-5 expression from basophils.

Interleukin-5 (IL-5) plays a key role in the pathogenesis of bronchial asthma. Thrombin is a procoagulant factor that has been also reported to participate in the inflammatory response by stimulating the secretion of cytokines. Interaction of inflammatory cells with airway epithelial cells may also promote the secretion of cytokines. However, the role of thrombin and cell-to-cell interaction in pathogenesis of allergic inflammation is unclear. In this study, we evaluated the role of thrombin and cell-to-cell interaction in the secretion of IL-5 from basophils. The human basophil cell line KU-812 was used in the assays. Thrombin and co-culture with alveolar epithelial cells significantly stimulated the secretion of IL-5 from KU-812 cells as compared to controls. Secretion of IL-5 was synergistically stimulated when KU-812 cells were incubated in the presence of both thrombin and alveolar epithelial cells. Co-culture of KU-812 cells with epithelial cells significantly increased the expression of tissue factor, an activator of coagulation activation, in a cell dose-dependent manner. Secretion of IL-5 from KU-812 basophils co-cultured with epithelial cells was significantly inhibited by LY294002, an inhibitor of phosphatidylinositol 3-kinase. These results suggest that thrombin and cell interaction with lung epithelial cells may augment the inflammatory response in allergic diseases by stimulating the secretion of IL-5 from basophils.

Exercise training does not alter acetylcholine-induced responses in isolated pulmonary artery from rat

In chronic exercise-trained animals, acetylcholine (ACh)-stimulated endothelial nitric oxide (NO) release is enhanced in the systemic circulation. The purpose of the present study was to determine whether chronic exercise training also enhances NO-mediated relaxation in rat pulmonary artery. Sprague-Dawley rats were randomly divided into groups of exercise-trained and sedentary control rats. The exercise-trained rats ran on a motor-driven treadmill at 30 m x min(-1) up a 15 degree incline 10-60 min x day(-1), 5 days per week for 10 weeks, and had less body weight, lower serum total cholesterol and triglyceride levels than sedentary rats. Contraction induced by potassium chloride and prostaglandin (PG)F2alpha were similar between isolated conduit pulmonary arterial rings from sedentary and exercise-trained rats. There were no differences between PGF2alpha-precontracted rings from sedentary and exercise trained rats in both ACh and sodium nitroprusside-induced relaxations. The NO synthase inhibitor, nitro-L-arginine, suppressed ACh-induced relaxation in both sedentary and exercise-trained rats. These results suggested chronic exercise training did not alter the acetylcholine-induced endothelial NO production and release and the sensitivity of vascular smooth muscle cell to NO in isolated conduit pulmonary artery of rat.