Eijiro Ohga

A pivotal role of cytosolic phospholipase A 2 in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is an interstitial disorder of the lung parenchyma whose mechanism is poorly understood. Potential mechanisms include the infiltration of inflammatory cells to the lungs and the generation of pro-inflammatory mediators. In particular, idiopathic pulmonary fibrosis is a progressive and fatal form of the disorder characterized by alveolar inflammation, fibroblast proliferation and collagen deposition. Here, we investigated the role of cytosolic phospholipase A2 (cPLA2) in pulmonary fibrosis using cPLA2-null mutant mice, as cPLA2 is a key enzyme in the generation of pro-inflammatory eicosanoids. Disruption of the gene encoding cPLA2 (Pla2g4a) attenuated IPF and inflammation induced by bleomycin administration. Bleomycin-induced overproduction of thromboxanes and leukotrienes in lung was significantly reduced in cPLA2-null mice. Our data suggest that cPLA2 has an important role in the pathogenesis of pulmonary fibrosis. The inhibition of cPLA2-initiated pathways might provide a novel therapeutic approach to pulmonary fibrosis, for which no pharmaceutical agents are currently available.

Amelioration of Vascular Endothelial Dysfunction in Obstructive Sleep Apnea Syndrome by Nasal Continuous Positive Airway Pressure

BACKGROUND Asymmetric NG,NG-dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide (NO) synthase and its plasma concentration is elevated in patients with cardiovascular risk factors, including hyperlipidemia, hypertension, diabetes, and hyperhomocysteinemia. Obstructive sleep apnea syndrome (OSAS) has been attracting attention as a risk factor for cardiovascular disorders because it often accompanies hypertension, obesity, glucose impairment, and dyslipidemia, all of which are factors in metabolic syndrome and risk factors for cardiovascular disease. METHODS AND RESULTS In the present study, flow-mediated vasodilatation (FMD) of the brachial artery and plasma concentrations of ADMA were measured before and after nasal continuous positive airway pressure (nCPAP) therapy, which abrogates apnea, in 10 male patients aged 36-69 years old, who were given a diagnosis of OSAS by polysomnography. The percent FMD (%FMD) improved significantly from 3.3+/-0.3% to 5.8+/-0.4% (p<0.01) and 6.6+/-0.3% (p<0.01), before, 1 week, and 4 weeks after nCPAP, respectively. At the same time, the plasma NOx concentrations, metabolites of NO, tended to increase, but the plasma ADMA concentration decreased inversely to %FMD and NOx. A negative correlation between %FMD and plasma ADMA concentration, and a positive correlation between %FMD and plasma NOx concentrations were observed. CONCLUSION Nasal CPAP improves endothelial function, in part by the decreasing ADMA concentration, thereby potentiating NO production.

Activin receptors are expressed on human lung fibroblast and activin a facilitates fibroblast-mediated collagen gel contraction

Activin A is a member of the transforming growth factor-beta superfamily that exerts its diverse biological effects through bindings to activin specific transmembrane serine/threonine kinase receptors. The fibroblast-mediated contraction of a collagen gel is thought to be a model of part of the wound-repair response and tissue contraction. In this study, we found the expression of activin type I receptors (ActR-I and ActR-IB) and type II receptor (ActR-II) on human fetal lung fibroblasts (HFL-1) by RT-PCR and immunocytochemistry. We also examined the effects of activin A on the HFL-1-mediated collagen gel contraction. Activin A stimulated collagen gel contraction in a dose dependent manner and its effect was abolished by an activin-binding protein, follistatin, that specifically suppresses activin A activities. This study demonstrated that ActR-I, ActR-1B and ActR-II are expressed on human fetal lung fibroblast and that activin A regulates fibroblast-mediated collagen gel contraction, suggesting that activin A might contribute to human lung fibroblast activities and structural remodeling observed in pulmonary fibrosis.

Obstructive sleep apnea syndrome may be a significant cause of gastroesophageal reflux disease in older people.

nitive impairment, we found that total IADL disability scores were significant predictors of subsequent hospitalization, home health care, and social services utilization. Individual IADL disabilities also predicted use of specific health services. Inability to do housework independently predicted hospitalization (odds ratio = 2.3) and use of home health care (odds ratio = 2.6) and social services (odds ratio = 6.2). Inability to shop independently predicted use of home health care (odds ratio = 2.3) and social services (odds ratio = 4.2). Inability to go independently to places out of walking distance predicted home healthcare use (odds ratio = 3.7) and social services use (odds ratio = 3.2). Inability to prepare meals independently predicted social services use (odds ratio = 4.7). Individual IADLs predict the use of home health and social services, but not the use of acute care services, after adjusting for other predisposing, enabling, and need characteristics. Identifying global and specific IADL disabilities can help predict future utilization of different health and human services. Measurement of functional ability may help to target interventions more precisely to those with specific needs and disabilities.

Molecular mechanisms underlying human beta-defensin-2 gene expression in a human airway cell line (LC2/ad).

Objective: Recently, human β‐defensin‐2 (hBD‐2), an inducible defensin, has been reported to be involved in innate immunity and host defence. To examine the exact roles of hBD‐2 in the respiratory system, we examined the molecular mechanisms of hBD‐2 gene expression in vitro.

Inhibitory Effect of Ambroxol on Superoxide Anion Production and Generation by Murine Lung Alveolar Macrophages

We examined the effect of ambroxol on superoxide anion production before and generation after phorbol-myristate acetate (PMA) stimulation of lung alveolar macrophages. Lung free cells including lung alveolar macrophages were obtained from Fischer 344 rats and guinea pigs using bronchoalveolar lavage. The superoxide anion produced by lung alveolar macrophages with or without stimulation of PMA was measured by lucigenin-dependent chemiluminescence method using a photon counter. Ambroxol inhibited the superoxide anion production and generation by lung alveolar macrophages harvested from both F344 rats and guinea pigs in a dose-dependent fashion. Approximately 16 mumol/L of ambroxol inhibited 50% of superoxide production of lung alveolar macrophages in rats and guinea pigs, whereas a slightly greater dose of ambroxol, i.e., 18-26 mumol/L, was necessary to inhibit 50% of PMA-enhanced superoxide generation by lung alveolar macrophages. These results suggest that ambroxol acts as an antioxidant in murine lungs and may be a potential therapeutic option for reactive oxygen species-associated lung disorders including bronchial asthma.

Effects of Ambroxol on Spontaneous or Stimulated Generation of Reactive Oxygen Species by Bronchoalveolar Lavage Cells Harvested from Patients With or Without Chronic Obstructive Pulmonary Diseases

We examined the effects of ambroxol on spontaneous or stimulated generation of reactive oxygen species (ROS) by bronchoalveolar lavage (BAL) cells prepared from 6 patients with chronic obstructive pulmonary disease (COPD) and age-matched control subjects without COPD. The ROS produced by BAL cells were measured by the lucigenin-dependent chemiluminescence method. The application of ambroxol into culture media containing BAL cells inhibited spontaneous and stimulated generation of ROS by BAL cells harvested from COPD patients and control subjects in an ambroxol concentration-dependent manner. These results indicate that ambroxol may be a candidate agent for reducing oxidant stresses of airways in COPD.

Effects of Angiotensin-Converting Enzyme (ACE) Inhibitors on Oxygen Radical Production and Generation by Murine Lung Alveolar Macrophages

We examined the effect of angiotensin-converting enzyme (ACE) inhibitors on oxygen radical production before and generation after phorbol-myristate acetate (PMA) stimulation of lung alveolar macrophages. Lung free cells, predominantly pulmonary alveolar macrophages, were obtained from Fischer 344 rats and guinea pigs using bronchoalveolar lavage. The oxygen radicals produced by pulmonary alveolar macrophages with or without stimulation of PMA were measured by lucigenin-dependent chemiluminescence method using a photon counter, Lumat 9501 (Berthold, Germany). Alacepril, an ACE inhibitor with SH-group, inhibited the oxygen radical production and generation by lung alveolar macrophages harvested from both rats and guinea pigs in a dose-dependent fashion. Approximately 0.3 mM of alacepril inhibited 50% of oxygen radical production of lung alveolar macrophages in both rats and guinea pigs, whereas a higher concentration (1-5 mM) of lisinopril, an ACE inhibitor without SH-group, was necessary to inhibit 50% of oxygen radical production of lung alveolar macrophages in the animals. These results suggest that an ACE inhibitor with SH-group acts as an antioxidant in murine lungs and the treatment with the ACE inhibitor may reduce oxidant stress in hypertensive patients with asthma.

Kinetics of adenovirus-mediated gene transfer to human lung fibroblasts

Many features of Ad-mediated gene transfer to human lung fibroblasts are not well understood. We tested kinetics of transduction efficiency of LacZ gene to human lung fibroblasts by E1-deleted adenovriuses containing two different promoters, i.e. CMV and RSV LTR. A dose-dependent relationship between the vector multiplicity of infection (moi) and the efficiency of LacZ gene transfer to fibroblasts was observed with each vector, and higher moi of vectors achieved 100% of transduction efficiency. Further, Ad-mediated gene transfer was enhanced by a long period of vector exposure to fibroblasts up to 6 hours. There were no differences in transduction efficiency between the two Ad vectors. LacZ gene expression by Ad vectors consistently decreased one day after infection. These results indicate that both Ad vectors are equally effective for gene transfer to human lung fibroblasts, and higher moi of vectors and/or a longer period exposure of fibroblasts to vectors can facilitate more efficient transduction of LacZ reporter gene into human lung fibroblasts.

Inhibitory effects of angiotensin-converting enzyme (ACE) inhibitors on oxygen radicals produced by bronchoalveolar lavage cells in young and aged guinea pigs

We examined the effect of angiotensin- converting enzyme (ACE) inhibitors and age on oxygen radical formation by bronchoalveolar lavage (BAL) cells. Lung-free cells, including pulmonary alveolar macrophages, were harvested from young (4-month-old) and aged (28-monthold) male guinea pigs using BAL. The oxygen radicals produced by BAL cells were measured by a lucigenin- dependent chemiluminescence method using a photon counter. Although spontaneous oxygen radical production by BAL cells from young and aged guinea pigs did not differ, the oxygen radical generation after maximal stimulation with phorbol-myristate acetate (PMA) was greater than that produced without PMA stimulation in both young and aged animals. ACE inhibitors with and without an SH-group (alacepril and lisinopril, respectively) were tested for their effect on oxygen radical formation by BAL cells; both ACE inhibitors inhibited oxygen radical production and generation by BAL cells from both young and aged guinea pigs in a dose-dependent manner. However, the alacepril concentration giving 50% inhibition (IC50) of oxygen radical generation by BAL cells was smaller than the IC50 of lisinopril in both young and aged guinea pigs. These results indicate that ACE inhibitors, in particular those with an SH-group, effectively reduce oxygen radical production by BAL cells from young and aged guinea pigs, and suggest that treatment with ACE inhibitors may be useful for ameliorating oxidant-associated pulmonary disorders in young and aged patients.