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Airway hyperresponsiveness (AHR), goblet cell metaplasia, and mucus overproduction are important features of bronchial asthma. To elucidate the molecular mechanisms behind these pulmonary pathologies, we examined for genes preferentially expressed in the lungs of a murine model of allergic asthma by using suppression subtractive hybridization (SSH). We identified a gene called gob-5 that had a selective expression pattern in the airway epithelium with AHR. Here, we show that gob-5, a member of the calcium-activated chloride channel family, is a key molecule in the induction of murine asthma. Intratracheal administration of adenovirus-expressing antisense gob-5 RNA into AHR-model mice efficiently suppressed the asthma phenotype, including AHR and mucus overproduction. In contrast, overexpression of gob-5 in airway epithelia by using an adenoviral vector exacerbated the asthma phenotype. Introduction of either gob-5 or hCLCA1, the human counterpart of gob-5, into the human mucoepidermoid cell line NCI-H292 induced mucus production as well as MUC5AC expression. Our results indicated that gob-5 may play a critical role in murine asthma, and its human counterpart hCLCA1 is therefore a potential target for asthma therapy.

Mucus overproduction is a clinical feature of asthma. Ca2+-activated Cl- channel 1 (CaCC1) has been identified as a protein that is expressed in intestinal epithelia and that plays an important role in fluid and electrolyte transport. Recently, its mouse counterpart, gob-5, was identified as a key molecule in the induction of murine asthma through mucus overproduction. To elucidate the relationship of CaCC1 to human asthma, we examined CaCC1 expression using real-time quantitative polymerase chain reaction analysis in bronchial tissues from patients with asthma and normal control subjects. The expression of CaCC1 was significantly upregulated in patients with bronchial asthma compared with control subjects. In situ hybridization and immunohistochemical analysis demonstrated that CaCC1 is located in the bronchial epithelium, especially in mucus-producing goblet cells. In vitro transfection of a CaCC1 expression vector into the human mucoepidermoid cell line, NCI-H292, increased mucus production and induced the MUC5AC gene. These results suggest that CaCC1 plays a direct role in mucus production and differentiation in goblet cells and may contribute to the pathogenesis of asthma through its mucus-inducing activity.

We examined the involvement of cyclooxygenase (COX)-1 as well as COX-2 in the healing of gastric ulcers and investigated which prostaglandin (PG) EP receptor subtype is responsible for the healing-promoting action of PGE2. Male SD rats and C57BL/6 mice, including wild-type, COX-1(-/-), and COX-2(-/-), were used. Gastric ulcers were produced by thermocauterization under ether anesthesia. Gastric ulcer healing was significantly delayed in both rats and mice by indomethacin and rofecoxib but not SC-560 given for 14 days after ulceration. The impaired healing was also observed in COX-2(-/-) but not COX-1(-/-) mice. Mucosal PGE2 content increased after ulceration, and this response was significantly suppressed by indomethacin and rofecoxib but not SC-560. The delayed healing in mice caused by indomethacin was significantly reversed by the coadministration of 11-deoxy-PGE1 (EP3/EP4 agonist) but not other prostanoids, including the EP1, EP2, and EP3 agonists. By contrast, CJ-42794 (selective EP(4) antagonist) significantly delayed the ulcer healing in rats and mice. VEGF expression and angiogenesis were both upregulated in the ulcerated mucosa, and these responses were suppressed by indomethacin, rofocoxib, and CJ-42794. The expression of VEGF in primary rat gastric fibroblasts was increased by PGE2 or AE1-329 (EP4 agonist), and these responses were both attenuated by coadministration of CJ-42794. These results confirmed the importance of COX-2/PGE2 in the healing mechanism of gastric ulcers and further suggested that the healing-promoting action of PGE2 is mediated by the activation of EP4 receptors and is associated with VEGF expression.

Visible-light-mediated addition of α-aminoalkyl radicals generated from α-silylamines to α,β-unsaturated carbonyl compounds using a photoredox catalyst is developed. We also succeeded in the isolation of a silyl enol ether as a primary product of the photochemical reaction.

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Amlexanox markedly inhibits histamine release from rat mast cells. To clarify the mechanism of this inhibition, we investigated the effect of amlexanox on cAMP content, which, when increased, inhibits histamine release in rat peritoneal mast cells. At concentrations of 10^––8––10^––6M, amlexanox or isoproterenol increased the cAMP content of mast cells over that of control cells about 2-fold. When the mast cells were incubated with 10^––8, 10^––7 and 10^––6M of amlexanox combined with 10^––7M isoproterenol, the cAMP contents were synergistically increased 15-, 60- and 88-fold, respectively. 3-Isobutyl-1-methylxanthine (IBMX) at 10^––6––10^––4M increased the cAMP content 1.7––3.8-fold, and a combination of 10^––4M IBMX and 10^––7M isoproterenol synergistically increased the cAMP content 41-fold. A combination of amlexanox and IBMX synergistically increased the cAMP content 19-fold. The increase in cAMP content, when amlexanox and isoproterenol were combined, was transient; it peaked at 0.5 min after the drugs were administered, then decreased to 20–30% of the peak value about 2 min later. Pretreatment of mast cells with amlexanox reduced the effect of the combination of amlexanox and isoproterenol, indicating tachyphylaxis; pretreatment with IBMX had no such effect. The cAMP content of macrophages was also increased by amlexanox, but when combined with isoproterenol or PGE₂, the effect was additive. Amlexanox inhibited cAMP phosphodiesterase in rat mast cells; its IC₅₀ value was 1.4 × 10^––5M, and its inhibitory activity was half that of IBMX. These results suggest that amlexanox inhibits histamine release by augmenting the cAMP content in mast cells, and that this augmentation is caused by enhancing the cAMP generation and, additively, by inhibiting cAMP phosphodiesterase.

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