Phosphorylation of cofilin by LIM-kinase is necessary for semaphorin 3A-induced growth cone collapse

Semaphorin 3A is a chemorepulsive axonal guidance molecule that depolymerizes the actin cytoskeleton and collapses growth cones of dorsal root ganglia neurons. Here we investigate the role of LIM-kinase 1, which phosphorylates an actin-depolymerizing protein, cofilin, in semaphorin 3A-induced growth cone collapse. Semaphorin 3A induced phosphorylation and dephosphorylation of cofilin at growth cones sequentially. A synthetic cell-permeable peptide containing a cofilin phosphorylation site inhibited LIM-kinase in vitro and in vivo, and essentially suppressed semaphorin 3A-induced growth cone collapse. A dominant-negative LIM kinase, which could not be activated by PAK or ROCK, suppressed the collapsing activity of semaphorin 3A. Phosphorylation of cofilin by LIM-kinase may be a critical signaling event in growth cone collapse by semaphorin 3A.

PAF mediates cigarette smoke-induced goblet cell metaplasia in guinea pig airways

Goblet cell metaplasia is an important morphological feature in the airways of patients with chronic airway diseases; however, the precise mechanisms that cause this feature are unknown. We investigated the role of endogenous platelet-activating factor (PAF) in airway goblet cell metaplasia induced by cigarette smoke in vivo. Guinea pigs were exposed repeatedly to cigarette smoke for 14 consecutive days. The number of goblet cells in each trachea was determined with Alcian blue-periodic acid-Schiff staining. Differential cell counts and PAF levels in bronchoalveolar lavage fluid were also evaluated. Cigarette smoke exposure significantly increased the number of goblet cells. Eosinophils, neutrophils, and PAF levels in bronchoalveolar lavage fluid were also significantly increased after cigarette smoke. Treatment with a specific PAF receptor antagonist, E-6123, significantly attenuated the increases in the number of airway goblet cells, eosinophils, and neutrophils observed after cigarette smoke exposure. These results suggest that endogenous PAF may play a key role in goblet cell metaplasia induced by cigarette smoke and that potential roles exist for inhibitors of PAF receptor in the treatment of hypersecretory airway diseases.

Matrix metalloproteinase (MMP) system in brain: identification and characterization of brain-specific MMP highly expressed in cerebellum

The matrix metalloproteinase (MMP) family, comprising more than 20 isoforms, modulates the extracellular milieu by degrading extracellular matrix (ECM) proteins. Because MMP is one of the few groups of proteinases capable of hydrolysing insoluble fibrillar proteins, they are likely to play crucial roles in regulating both normal and pathophysiological processes in the brain. However, little is yet known about their possible neuronal functions due presumably to their unusual redundancy and to the absence of a complete catalogue of isoforms. As an initial step in understanding the MMP system in the brain, we analysed an expression spectrum of MMP in rat brain using RT-PCR and discovered a novel brain-specific MMP, MT5-MMP. MT5-MMP was the predominant species among the nongelatinase-type isoforms in brain. MT5-MMP, present in all brain tissues examined, was most strongly expressed in cerebellum and was localized in the membranous structures of expressing neurons, as assessed biochemically and immunohistochemically. In cerebellum, its expression was regulated developmentally and was closely associated with dendritic tree formation of Purkinje cells, suggesting that MT5-MMP may contribute to neuronal development. Furthermore, its stable postdevelopmental expression and colocalization with senile plaques in Alzheimer brain indicates possible roles in neuronal remodeling naturally occurring in adulthood and in regulating pathophysiological processes associated with advanced age.

Thapsigargin, a Ca(2+)-ATPase inhibitor, relaxes guinea pig tracheal smooth muscle by producing epithelium-dependent relaxing factors

A non-phorbol ester-type tumor promoter, thapsigargin has been reported to deplete Ca(2+) stores in endothelial cells by inhibiting Ca(2+)-ATPase, which in turn increases intracellular Ca(2+) by mobilization of extracellular Ca(2+), leading to activation of constitutive nitric oxide synthase (cNOS) and resultant generation of nitric oxide (NO). In the present study, to evaluate the role of Ca(2+) in the release of epithelium-dependent relaxing factor (EpDRF), we determined the effect of thapsigargin (10(-6) M) on the contraction evoked by exogenous Ca(2+) or acetylcholine (10(-5) M) in epithelium-denuded or epithelium-intact smooth muscle from guinea pig trachea. The following results were obtained: (1) In epithelium-denuded smooth muscle, the contraction evoked by exogenous Ca(2+) in Ca(2+)-free solution or by acetylcholine (10(-5) M) in Ca(2+)-containing solution did not change within 20 min after thapsigargin application, but the contraction evoked by exogenous Ca(2+) increased markedly after 120 min, indicating that thapsigargin had no effect on smooth muscle itself within 20 min of application. The following experiments were performed within 20 min of thapsigargin application. (2) In epithelium-intact smooth muscle, thapsigargin significantly suppressed the contraction evoked by acetylcholine, suggesting that thapsigargin stimulate the epithelium to produce EpDRF. N(G)-nitro-L-arginine methylester (L-NAME) partly, but significantly, attenuated this inhibitory effect of thapsigargin. (3) In epithelium-denuded smooth muscle, atropine (10(-6) M) and L-NAME (10(-5) M) did not change the contraction evoked by exogenous Ca(2+) after application of thapsigargin, suggesting that thapsigargin did not stimulate acetylcholine and NO release from nerve terminals. These results suggest that thapsigargin (10(-6) M) may stimulate EpDRF, including NO and other factor(s) by Ca(2+)-dependent mechanisms.

[A case of latex allergy with bronchial asthma]

A 26-year-old nurse consulted our department because of shortness of breath, wheezing and skin eruption after eating lunch several days before. At the consultation, the symptoms had disappeared, pulmonary function showed no abnormality, and there were no abnormal findings on chest auscultation. Latex allergy was suspected because of a history of wheezing and skin eruption after wearing latex gloves and an elevated serum IgE level specific to latex antigen. After a usage test of medical latex gloves, wheezing, skin eruption, and a decrease of FEV1.0 on pulmonary function testing were observed. The case was therefore diagnosed as latex allergy with bronchial asthma. Her symptoms were not observed after polymer coated gloves were substituted. Latex allergy is apt to complicate food allergy, an initial symptom of the present case. Specific IgE for several kinds of food was also elevated.

Cyclooxygenase-2 participates in the late phase of airway hyperresponsiveness after ozone exposure in guinea pigs

We examined the role of cyclooxygenase in airway hyperresponsiveness and inflammation after ozone exposure in guinea pigs using a non-selective (indomethacin) and a selective (JTE-522) cyclooxygenase-2 inhibitor. Spontaneously breathing guinea pigs were exposed to ozone (3 ppm) for 2 h after treatment with vehicle, indomethacin (10 mg/kg) or JTE-522 (10 mg/kg). Airway responsiveness to inhaled histamine (PC(200)) and bronchoalveolar lavage were assessed before, immediately and 5 h after ozone exposure. Ozone caused a significant airway hyperresponsiveness immediately after exposure, which persisted after 5 h. Neither JTE-522 nor indomethacin affected airway hyperresponsiveness immediately after ozone exposure, but significantly attenuated airway hyperresponsiveness 5 h after exposure, suggesting that cyclooxygenase-2 may participate in the late phase of airway hyperresponsiveness but not in the early phase. Ozone caused a significant increase in the concentration of prostaglandin E(2) and thromboxane B(2) in bronchoalveolar lavage fluid immediately after exposure, which decreased to the basal level 5 h after exposure. This increase in prostaglandin E(2) and thromboxane B(2) was significantly inhibited by JTE-522. An expression of cyclooxygenase-2 was detected not only after ozone exposure but also before, and there was no difference in the number of cyclooxygenase-2-positive cells at any time point. An exogenously applied thromboxane A(2) mimetic, U-46619 (10(-5) M), induced airway hyperresponsiveness 5 h after inhalation, but not immediately or 3 h after inhalation. These data suggest that cyclooxygenase-2 may be constitutively expressed before ozone exposure in guinea pig airway and may synthesize prostaglandin E(2) and thromboxane A(2) transiently under ozone stimulation and that thromboxane A(2) may, in turn, induce the late phase of airway hyperresponsiveness.

Decreased insulin production and increased insulin sensitivity in the klotho mutant mouse, a novel animal model for human aging

We have recently identified a novel gene, klotho (kl), which may suppress several aging phenotypes. A defect of kl gene expression in the mouse results in a syndrome resembling human aging, such as arteriosclerosis, skin atrophy, osteoporosis, and pulmonary emphysema. To determine whether mouse homozygotes for the kl mutation (kl/kl) show abnormal glucose metabolism, an oral glucose tolerance test (OGTT) was performed at 6 to 8 weeks of age. Blood glucose levels during the OGTT were significantly lower in kl/kl mice versus wild-type mice. The insulin content of the pancreas was significantly lower in kl/kl mice compared with wild-type mice. Decreased insulin production was also supported by Northern blot analysis showing lower levels of insulin mRNA in kl/kl mice. To examine how lower blood glucose levels may exist in kl/kl mice despite decreased insulin production, insulin tolerance tests (ITTs) were performed. The glucose decline following insulin injection was more severe in kl/kl mice versus wild-type mice, suggesting that insulin sensitivity was higher in kl/kl mice versus wild-type mice. In kl/kl mice, an augmented expression of GLUT4 in skeletal muscle was demonstrated by both Northern blot analysis and Western blot analysis. Thus, we conclude that insulin production is decreased and insulin sensitivity is increased in the klotho mouse, a novel animal model for human aging.

Effect of dimethylthiourea, a hydroxyl radical scavenger, on cigarette smoke-induced bronchoconstriction in guinea pigs

Cigarette smoke exposure causes bronchoconstriction in guinea pigs by stimulating cholinergic and excitatory nonadrenergic, noncholinergic (eNANC)-nerves in vagus system. The aim of this study is to elucidate the role of hydroxyl radical (OH(-)), contained in cigarette smoke, in bronchoconstriction. Anaesthetized animals were exposed to 80 puffs of smoke for 4 min. Pretreatment with dimethylthiourea, a OH(-) scavenger, significantly inhibited cigarette smoke-induced bronchoconstriction. To investigate its site of action, effects of dimethylthiourea were examined on vagally mediated bronchcoconstriction by electrical stimulation and on the bronchoconstriction by intravenous acetylcholine and neurokinin-A. Dimethylthiourea did not inhibit bronchoconstriction evoked by vagal stimulation, acetylcholine or neurokinin-A. These results suggest that dimethylthiourea inhibits cigarette smoke-induced bronchoconstriction by scavenging the smoke-derived OH(-), but not by inhibiting airway nerve function.

Recurrent chest opacities in a patient with thromboembolic pulmonary hypertension

We describe a 42-year-old man with chronic thromboembolic pulmonary hypertension associated with protein S deficiency. He presented with unusual roentgenographic findings of migratory pulmonary infiltrates.

Effect of endothelin-1 on the serotonin-induced contraction of smooth muscle in the guinea pig trachea

BACKGROUND

Endothelin (ET), a potent constrictor of smooth muscle including that of the airways, may contribute to the development of airway hyperresponsiveness.

OBJECTIVE

To investigate the role of ET-1 on the airway smooth muscle, we examined the effects of ET-1 on the serotonin-induced contraction of guinea pig tracheal smooth muscle.

METHODS

The changes in isometric tension evoked by serotonin were measured before and after the application of a subthreshold dose (a dose which did not induce smooth muscle contraction by itself) of ET-1.

RESULTS

Serotonin caused smooth muscle contraction in a dose-dependent manner. The subthreshold doses of ET-1 (1 pM) and sarafotoxin 6c (1 pM), a selective ETB receptor agonist, were found to potentiate significantly the contraction induced by serotonin. A potentiating effect of ET-1 was not altered by indomethacin or calphostin C, a protein kinase C inhibitor.

CONCLUSION

These results suggest that a subthreshold concentration of ET-1 can potentiate serotonin-induced contraction of smooth muscle through the activation of ETB receptor, while in contrast cyclooxygenase and protein kinase C were found not to be involved in this mechanism.

Basophilic cytoplasmic inclusions in a case of sporadic juvenile amyotrophic lateral sclerosis

A 24-year-old woman presented with progressive muscle atrophy and weakness of the right upper extremity. Subsequently her weakness rapidly extended to the left upper extremity, neck and lower extremities. Neurological examination disclosed involvement of the lower motor neuron system. She died 7 months after the onset. There was neuronal loss and reactive gliosis in the anterior horns of the spinal cord and much less frequently in the motor cortex. Basophilic cytoplasmic inclusions were observed in the thalamus and brain stem as well as the upper and lower motor neurons. Ultrastructurally, the inclusions lacked a limiting membrane and consisted of a meshwork of filamentous structures associated with granules. The inclusions failed to react with antibodies against phosphorylated neurofilament or cystatin C. Most of the inclusions show no reaction with anti-ubiquitin antibody, however, a few inclusions show granular reaction product deposits with this antibody. The inclusions were not immunostained with antibodies against TGN46 and MG-160, markers of the trans-Golgi network and the medial cisternae of the Golgi apparatus, respectively, suggesting that they were not derived from the Golgi apparatus which was fragmented.

An adult case of mumps brainstem encephalitis

We present an adult case of mumps brainstem encephalitis. He was successfully treated with steroid pulse therapy and recovered completely except for persistent dysuria. He had not been vaccinated and had no history of acute mumps infection. We consider that encephalitis in this case was caused by a reversible autoimmune process triggered by mumps infection. We emphasize the usefulness of pulse therapy for the treatment of some cases of mumps brainstem encephalitis in addition to the importance of mumps vaccination to prevent such a severe complication as encephalitis.

Effect of eotaxin and platelet-activating factor on airway inflammation and hyperresponsiveness in guinea pigs in vivo

Although eotaxin causes selective infiltration of eosinophils into the lung, its role in airway hyperresponsiveness remains unclear. We studied the effects of local administration of eotaxin on airway inflammation and hyperresponsiveness in guinea pigs in vivo. Airway responsiveness to inhaled histamine and differential cell counts in bronchoalveolar lavage fluid (BALF) were evaluated 12 h, 24 h, 3 d, and 7 d after intratracheal instillation of eotaxin. Significant eosinophilia in BALF was observed between 6 h and 7 d after eotaxin administration. Histologically, eosinophil accumulation was observed in the airways but not in the alveoli. In contrast, eotaxin did not affect airway responsiveness between 12 h and 7 d after its administration. We then studied the effects on airway responsiveness of subthreshold doses of interleukin 5, leukotriene D(4) (LTD(4)), and platelet-activating factor (PAF) combined with eotaxin. Neither interleukin 5 nor LTD(4) affected airway responsiveness. After eotaxin treatment, PAF significantly enhanced airway responsiveness without further increases in eosinophil counts. Eotaxin plus PAF significantly increased in eosinophil peroxidase activity in BALF compared with control and with eotaxin alone. These data indicate that eotaxin alone causes eosinophil accumulation in the airways but not hyperresponsiveness, and that additional factors such as PAF are needed to activate eosinophils for the development of airway hyperresponsiveness.

Endothelial dysfunction in the klotho mouse and downregulation of klotho gene expression in various animal models of vascular and metabolic diseases

The human aging process is associated with vascular endothelial dysfunction. However, humoral factors which might protect against endothelial dysfunction during aging have not yet been identified. We recently identified the klotho gene as a possible regulator of human aging. In the present study using the klotho-deficient heterozygous mouse, we examined whether the Klotho protein is a humoral factor protecting against endothelial dysfunction. We further cloned rat klotho cDNA and investigated whether klotho mRNA expression in rat kidney is altered under pathological conditions such as hypertension, hyperlipidemia, renal failure, and inflammatory stress. The Klotho protein itself, or its metabolites, promotes endothelial NO production in aorta as well as arterioles, and klotho mRNA in kidney is downregulated under sustained circulatory stress.

Pituitary adenylate cyclase activating peptide mediates inhibitory nonadrenergic noncholinergic relaxation

We investigated the contribution of pituitary adenylate cyclase activating peptide (PACAP) to inhibitory nonadrenergic noncholinergic (inhibitory-NANC) relaxation of tracheal smooth muscle in cats. We also investigated the roles of vasoactive intestinal peptide (VIP) and nitric oxide (NO) on this function. Smooth muscle strips prepared from feline trachea were precontracted with 1 microM serotonin, and inhibitory-NANC relaxation was induced by electrical-field stimulation in the presence of atropine and propranolol. PACAP-(6-38) (a selective antagonist of PACAP; 1, 3 and 10 microM), VIP-(10-28) (a selective antagonist of VIP; 1, 3 and 10 microM) and N(omega)-nitro-L-arginine methyl ester (L-NAME, a selective NO synthase inhibitor; 3, 10 and 30 microM) each partially but significantly attenuated the amplitude of inhibitory-NANC relaxation. The effects of PACAP-(6-38) and VIP-(10-28) were additive. Addition of PACAP-(6-38) and/or VIP-(10-28) further attenuated relaxation in the presence of L-NAME. These results suggest that PACAP, VIP and NO contribute to the relaxation induced by inhibitory-NANC in tracheal smooth muscle in cats, and that they mediate this relaxation via different pathways.

[Recurrence of catamenial pneumothorax after surgical treatment]

We reported a case of catamenial pneumothorax that was recurrent after surgical treatment. A 43-year-old woman had sudden chest pain and dyspnea during menstruation. Right pneumothorax and pleural effusion were pointed out on chest X-ray films. When the patient was 31 years old, she received a diagnosis of catamenial pneumothorax and underwent thoracotomy for resection of diaphragmatic endometriosis. However, after surgery she experienced recurrence of right pneumothorax, and was accordingly treated with danazol. The patient decided to terminate medication by herself because her symptoms had disappeared. Several years after the cessation of medication, she experienced chest pain frequently during menstruation, but did not seek a medical check-up. She visited our department because of persistent chest pain in 1997. After the patient was hospitalized, pneumothorax was diagnosed and continuous drainage was performed. Although pneumothorax was alleviated by drainage, it recurred during the patient's next menstrual period. Open lung surgery was performed. Diaphragmatic endometriosis with a small hole and inflammatory thickened lesions on the visceral pleura of the lower lobe (S 6) were found and excised. Microscopic examination of the excised specimens showed endometriosis. Visceral pleural endometriosis has been histologically demonstrated in very few cases. After surgery, hormonal therapy was started. The patient has been well for 12 months without recurrence of pneumothorax. Both surgical and hormonal treatment were considered necessary for the treatment of catamenial pneumothorax in this case.

Neutrophil elastase inhibitor, ONO-5046 suppresses ozone-induced airway mucus hypersecretion in guinea pigs

To investigate the role of neutrophil elastase in ozone-induced airway hypersecretion, we measured goblet cell secretion by using a semiquantitative morphometric technique in guinea pigs. The magnitude of mucus discharge was estimated from the mucus score, which is inversely related to the degree of mucus discharge in histological sections of trachea stained for mucus glycoprotein with periodic acid Schiff/Alcian blue. Mucus hypersecretion of goblet cells was induced by ozone exposure and persisted for up to 5 h after exposure. Pretreatment with N-[2-¿4-(2,2-dimethyl-propionyloxy) phenyl-sulfonylamino¿ benzoyl] aminoacetic acid (ONO-5046), a specific neutrophil elastase inhibitor (200 mg/kg, intraperitoneally), significantly inhibited goblet cell hypersecretion both just after and 5 h after ozone-exposure, but the latter inhibition was not complete. In bronchoalveolar lavage fluid, ozone exposure significantly increased the number of neutrophils just after and 5 h after exposure, while ONO-5046 significantly inhibited the increase in neutrophils only 5 h after ozone-exposure. These results indicate that neutrophil elastase may play an important role in the ozone-induced tracheal goblet cell hypersecretion and influx of neutrophils.

Once-daily theophylline reduces serum eosinophil cationic protein and eosinophil levels in induced sputum of asthmatics

BACKGROUND

Because eosinophilic airway inflammation is a characteristic feature of bronchial asthma, the treatment of airway inflammation is important in the management of asthma. Theophylline has been reported to reduce airway inflammation, in addition to its well-known bronchodilating effect.

OBJECTIVE

In order to evaluate the effects of theophylline on airway inflammation, we investigated 48 subjects with mild and moderate asthma.

METHODS

The patients were randomly divided into two groups, with or without theophylline treatment (control n = 24; theophylline, n = 24). We examined the level of serum eosinophil cationic protein (ECP), induced sputum samples, and peak expiratory flow (PEF) and obtained spirograms before and after 4 weeks of treatment with once-daily theophylline (200-600 mg/day) of subjects with mild or moderate asthma.

RESULTS

Theophylline significantly increased morning and evening PEF and significantly decreased the diurnal variation of PEF. After treatment with theophylline, both serum ECP and the percentage of eosinophils in induced sputum were significantly decreased. In contrast, peripheral blood eosinophil count was unchanged after treatment with theophylline.

CONCLUSIONS

These findings suggest that theophylline reduces airway inflammation and the severity of asthma, presumably via suppression of both eosinophil activity and subsequent eosinophil infiltration of the airways.

Effects of positive end-expiratory pressure ventilation on cerebral venous pressure with head elevation in dogs

Mechanical ventilation with positive end-expiratory pressure (PEEP) may prevent venous air embolism in the sitting position because cerebral venous pressure (Pcev) could be increased by the PEEP-induced increase in right atrial pressure (Pra). Whereas it is clear that there is a linear transmission of the PEEP-induced increase in Pra to Pcev while the dog is in the prone position, the mechanism of the transmission with the dog in the head-elevated position is unclear. We tested the hypothesis that a Starling resistor-type mechanism exists in the jugular veins when the head is elevated. In one group of dogs, increasing PEEP linearly increased Pcev with the dog in the prone position (head at heart level, slope = 0.851) but did not increase Pcev when the head was elevated. In another group of dogs, an external chest binder was used to produce a larger PEEP-induced increase in Pra. Further increasing Pra increased Pcev only after Pra exceeded a pressure of 19 mmHg (break pressure). This sharp inflection in the upstream (Pcev)-downstream (Pra) relationship suggests that this may be caused by a Starling resistor-type mechanism. We conclude that jugular venous collapse serves as a significant resistance in the transmission of Pra to Pcev in the head-elevated position.

Nitric oxide synthase inhibitors attenuate ozone-induced airway inflammation in guinea pigs. Possible role of interleukin-8

Nitric oxide (NO) is increased in exhaled air of asthmatics. We hypothesized that endogenous NO contributes to airway inflammation and hyperresponsiveness, and that interleukin-8 (IL-8) might be involved in this mechanism. In human transformed bronchial epithelial cells in vitro, NO donors increased IL-8 production dose-dependently. In addition, tumor necrosis factor-alpha (TNF-alpha) plus IL-1beta plus interferon-gamma (IFN-gamma) increased IL-8 in culture supernatant of epithelial cells; the combination of NO synthase (NOS) inhibitors, aminoguanidine (AG) plus N(G)-nitro-L-arginine methyl ester (L-NAME) attenuated the cytokine-induced IL-8 production in epithelial cells. In guinea pigs in vivo, ozone exposure induced airway hyperresponsiveness to acetylcholine and increased neutrophils in bronchoalveolar lavage fluid (BALF), and these changes persisted for at least 5 h. Pretreatment with NOS inhibitors had no effect on airway hyperresponsiveness or neutrophil accumulation immediately after ozone, but significantly inhibited the changes 5 h after ozone. NOS inhibitors also attenuated the increases of nitrite/nitrate levels in BALF and the IL-8 mRNA expression in epithelial cells and in neutrophils in guinea pig airways 5 h after ozone. These results suggest that endogenous NO may play an important role in the persistent airway inflammation and hyperresponsiveness after ozone exposure, presumably partly through the upregulation of IL-8.

Latex piezoelectric immunoassay: analysis of C-reactive protein in human serum

We constructed an integrated immunosensor system to combine a quartz crystal microbalance with the agglutination reaction of immunized latex beads. C-reactive protein (CRP) induced an immunoreaction due to the latex bends with anti-CRP antibody. We succeeded in determining the concentration of CRP necessary in human serum for disease diagnosis using a CRP Sensor I.

Disruption of the klotho gene causes pulmonary emphysema in mice. Defect in maintenance of pulmonary integrity during postnatal life

Homozygous mutant klotho (KL(-/-)) mice exhibit multiple phenotypes resembling human aging. In the present study, we focused on examining the pathology of the lungs of klotho mice and found that it closely resembled pulmonary emphysema in humans both histologically and functionally. Histology of the lung of KL(-/-) mice was indistinguishable from those of wild-type littermates up to 2 wk of age. The first histologic changes appeared at 4 wk of age, showing enlargement of the air spaces accompanied by destruction of the alveolar walls, and progressed gradually with age. In addition to these changes, we observed calcium deposits in type I collagen fibers in alveolar septa and degeneration of type II pneumocytes in 8- to 10-wk-old KL(-/-) mice. Pulmonary function tests revealed prolonged expiration time in KL(-/-) mice, which is comparable with the pathophysiology of pulmonary emphysema. The expression level of messenger RNA for type IV collagen, surfactant protein-A and mitochondrial beta-adenosine triphosphatase was significantly increased in KL(-/-) mice, which may represent a compensatory response to alveolar destruction. Additionally, the heterozygous mutant klotho mice also developed pulmonary emphysema late in life, around 120 wk of age. These findings indicate that klotho gene expression is essential to maintaining pulmonary integrity during postnatal life. The klotho mutant mouse is a useful laboratory animal model for examining the relationship between aging and pulmonary emphysema.

Effect of the Chinese herbal medicine, Bakumondo-to, on airway hyperresponsiveness induced by ozone exposure in guinea-pigs

OBJECTIVE

Bakumondo-to (Maimendong tang) is a Chinese herbal medicine that has been used as an anti-tussive agent. However, the effects of Bakumondo-to on airway hyperresponsiveness are unknown. We examine whether Bakumondo-to can inhibit airway hyperresponsiveness induced by ozone.

METHODOLOGY

Measurements of airway responsiveness and plasma extravasation and bronchoalveolar lavage (BAL) were performed before and after ozone exposure (3 p.p.m., 2 h). Guinea-pigs were anaesthetized with pentobarbital sodium and mechanically ventilated. Airway responsiveness was determined by an inhalation of doubling concentration of histamine, and the concentration of histamine required to produce a 200% increase in R(L) (PC200) was calculated by log-linear interpolation. Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway.

RESULTS

Ozone produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. Bakumondo-to (400 mg/kg p.o.) significantly inhibited airway hyperresponsiveness, but had no effect on neutrophil influx or plasma extravasation.

CONCLUSIONS

We demonstrated that Bakumondo-to can attenuate airway hyperresponsiveness induced by ozone without affecting airway inflammation, which suggests that Bakumondo-to may act on the subsequent mechanisms after the induction of inflammation, such as mediator release.

Role of neutrophil elastase in ozone-induced airway responses in guinea-pigs

Ozone-induced airway hyperresponsiveness occurs concurrently with neutrophilic inflammation and epithelial injury in various species including humans. The mechanism of neutrophil-induced airway hyperresponsiveness, however, has not yet been fully clarified. Neutrophil elastase (NE) is a multipotent protease released from activated neutrophils, which may play a role in ozone-induced airway hyperresponsiveness. In order to address this issue, the effects of ONO-5046, a specific NE inhibitor, were investigated in ozone-exposed guinea-pigs. Awake animals were exposed to ozone at 3 parts per million for 2 h, airway responsiveness to acetylcholine (ACh) measured and examination of bronchoalveolar lavage fluid (BALF) performed. Ozone exposure increased airway responsiveness to both inhaled and intravenous ACh, the concentration of NE in BALF and the number of neutrophils and airway epithelial cells in BALF. Although pretreatment with ONO-5046 (200 mg x kg(-1), i.p.) had no effect on these changes immediately after the exposure, it significantly inhibited airway hyperresponsiveness to inhaled ACh, whilst decreasing the number of neutrophils and epithelial cells in BALF 3-5 h after the exposure. In contrast, ONO-5046 showed no significant effect on airway hyperresponsiveness to intravenous ACh at any time. These results suggest that neutrophil elastase contributes to ozone-induced airway hyperresponsiveness developing during the hours after exposure, presumably by means of inducing epithelial injury.