We have observed an inhibitory action of magnolol on the production of leukotriene (LT) C4 and LTB4, important lipid mediators in allergy and inflammation. IgE- and A23187-stimulated production of LTC4 and LTB4 was measured by radio-immunoassay (RIA) in the absence or presence of various concentrations of magnolol in intact rat basophilic leukemia (RBL)-2H3 cells. Magnolol dose-dependently inhibited synthesis of LTC4 and LTB4. Magnolol inhibited the IgE-mediated increase of intracellular calcium ion concentration, resulting in the inhibition of cytosolic phospholipase A2 (cPLA2) and possibly 5-lipoxygenase (5-LO), both calcium ion-dependent enzymes. In cell-free studies magnolol inhibited LTC4 synthase activity. LTA4 hydrolase activity was only inhibited at the higher concentration (2.5 x 10(-5)M). These results indicate that magnolol inhibits production of LTs by inhibiting PLA2, 5-LO, LTC4 synthase and LTA4 hydrolase which are essential for LT-synthesis. Magnolol may have anti-allergic effect by blocking LT-synthesis.

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The exacerbation of asthma during viral infections is mainly explained by neutrophils infiltrating into the airways. However, enhanced functions of eosinophils are also observed. The aim of this study was to reveal the mechanism of how eosinophils are activated during and after viral infection of the airways, using a model of viral infection.A synthetic double-stranded RNA, poly inosinic-cytidyric acid (poly(IC)), was transfected to a human airway epithelial cell line (BEAS-2B) and the primary bronchial epithelial cells, to mimic a viral infection. The production of chemokines from the cells was investigated.The transfection of poly(IC), alone, marginally affected the eotaxin-3 production of the cells. However, the transfection of poly(IC) prior to interleukin (IL)-4 stimulation enhanced eotaxin-3 production. Poly(IC) transfection increased mRNA and protein expressions of IL-4 receptor (R)a and IL-2Rc, components of the IL-4R. In BEAS-2B cells, IL-4-mediated phosphorylation of signal transducer and activator of transcription six was enhanced in poly(IC) transfected cells. This was reversed by the addition of anti-IL-4Ra antibody, suggesting the role of an increased number of IL-4 receptors in enhanced IL-4-induced eotaxin-3 production. Poly(IC)-induced upregulation of IL4Ra was inhibited by treatment with cycloheximide or dexamethasone.In conclusion, these results suggest that viral airway infection may enhance interleukin-4-induced eotaxin-3 production through upregulation of the interleukin-4 receptor in airway epithelial cells.

Interleukin (IL)-4, IL-10, and IL-13, Th2 cell–derived cytokines, play major roles in the pathophysiology of allergic diseases. These cytokines up-regulate or down-regulate the production of arachidonic acid metabolites. In this study, we have investigated the effect of IL-4, IL-10, IL-13, and other cytokines on A23187-stimulated synthesis of leukotriene (LT) B4 in human polymorphonuclear leukocytes (PMNs). Production of LTB4 was measured by specific radioimmunoassay and high performance liquid chromatography. Messenger RNA (mRNA) expression of cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase (5-LO), and LTA4 hydrolase, which were involved in the synthesis of LTB4, was determined by reverse transcription–polymerase chain reaction and Northern blot analysis. Protein synthesis of their enzymes was determined by Western blot analysis. IL-4 and IL-13 enhanced A23187-stimulated LTB4 synthesis and increased mRNA expression and protein synthesis of LTA4hydrolase, but not those of cPLA2 or 5-LO. These results indicate that IL-4 and IL-13 transcriptionally or post-transcriptionally up-regulate the synthesis of LTB4, a potent chemotactic factor to PMNs, at the enzyme level of LTA4 hydrolase, and this up-regulation mechanism may participate in the development of allergic inflammation.

Leukotriene (LT)C 4 , a potent chemical mediator in bronchial asthma, is metabolised to the less active LTE 4 via LTD 4 in two consecutive reactions catalysed by enzymes of the glutamyl transpeptidase and dipeptidase families. The activities of these catabolic enzymes may be influenced by glucocorticosteroids. This study was conducted to examine whether this inactivation of LTC 4 is affected by dexamethasone (DEX) in transformed human bronchial epithelial cells and normal human bronchial epithelial cells.After incubation with DEX for 0-5 days, cells were resuspended in the presence of exogenous LTC 4 , and conversion of LTC 4 to LTE 4 was measured using highperformance liquid chromatography. c-Glutamyl transpeptidase (GGT) and GGTrelated enzyme (GGTRE) messenger ribonucleic acid (mRNA) expression were examined using reverse transcriptase-polymerase chain reaction analysis, and GGT activity by enzyme assay.Conversion to LTE 4 was accelerated by DEX pretreatment. GGTRE but not GGT mRNA expression was enhanced after incubation with DEX.The results indicate that dexamethasone transcriptionally upregulates the activity of c-glutamyl transpeptidase-related enzyme in human bronchial epithelial cells, which accelerates inactivation of leukotriene C 4 via conversion to leukotriene E 4 . This is a novel mechanism of glucocorticosteroids in human bronchial epithelial cells. This study was supported, in part, by a grant from the Ministry of Education, Science, Sports and Culture, Tokyo, Japan.Cysteinyl leukotrienes (cysLTs), leukotriene (LT)C 4 , LTD 4 and LTE 4 , metabolites of the arachidonate 5-lipoxygenase (5-LO) pathway [1,2], are produced in mast cells, basophils and eosinophils in the process of allergic inflammation. CysLTs stimulate mucus secretion, induce bronchial hyperresponsiveness, cause constriction of airway smooth muscle and increase vascular permeability [3][4][5][6][7][8][9]. All of these symptoms are associated with asthma in humans. In clinical studies, cysLT-receptor antagonists were therapeutically effective in bronchial asthma [10,11]. It was also shown that a part of the early-and latephase reactions caused by antigen challenge was prevented by cysLT-receptor antagonists in patients with asthma. Thus, cysLTs are considered to be strongly associated with the pathophysiology of human bronchial asthma [1,12].The synthesis of LT is initiated by transmembranous stimulation by various factors that increase the level of intracellular calcium ions, leading to translocation of cytosolic phospholipase (cPL)A 2 from the cytosol to the nuclear membrane. cPLA 2 cleaves arachidonic acid from the membrane phospholipid of the nucleus. The released arachidonic acid is converted into LTA 4 via an unstable intermediate, 5-hydroperoxyeicosatetraenoic acid, by 5-LO, which is also translocated from the cytosol to the nuclear membrane, where 5-LO-activating protein resides. The next step is the transformation of LTA 4 to LTC 4 by conjugation of LTA 4 by LTC 4 synthase on the surface of the cell nuclear membrane....

Renal hypo-uricemia is caused by an isolated renal tubular defect of uric acid (UA) handling. The incidence of renal hypo-uricemia in Japan is between 0.12% and 0.2%. 1 Recently, renal hypo-uricemia became important because dozens of patients were reported to have developed exercise-induced acute renal failure (ARF) without rhabdomyolysis. 2,3 Enomoto et al. identifi ed a UA transporter gene, human UA transporter 1 (hURAT1), encoded by SLC22A12, from human kidney. 4 It was also demonstrated that the mutations in the hURAT1 gene were recognized in subjects with renal hypo-uricemia. 5,6 The W258X in hURAT1 has been a predominant gene mutation in Japanese subjects with renal hypo-uricemia. 6 We report patients with heterozygous and homozygous mutations in the hURAT1 gene in a family with renal hypo-uricemia associated with exercise-induced ARF. Case reportThe patient was a 15-year-old boy who was admitted to Saga Medical School Hospital because of severe nausea and abdominal pain after participating in a track race at a local athletic meeting. Prior to admission, he had been well and had not experienced any similar symptoms.Physical examination showed marked tenderness in the lower quadrant, and arterial blood pressure was 136/70 mmHg. Laboratory evaluation was as follows: white blood cell count (WBC), 6800/m L; hemoglobin (Hb), 13.0 g/dL; platelet count, 190 000/m L; blood urea nitrogen (BUN), 47.5 mg/dL; serum creatinine (sCr), 4.44 mg/dL; creatine kinase (CK), 104 mg/dL; UA, 3.5 mg/dL; Na, 138 mEq/L; K, 4.0 mEq/L; Cl, 101 mEq/L. Serum C-reactive protein (CRP) was 4.47 mg/dL. No proteinuria or hematuria was found. The laboratory fi ndings were suggestive of ARF and led us to investigate the renal function. The fractional excretion of sodium (FE Na ) and the fractional excretion of uric acid (FE UA ) were increased to 6.36% (1% < normal < 2% ) and 64.8% (normal < 10% ). Urinary b 2 -microglobulin and N-acetyl glucosaminidase (NAG) were 3.75 m g/L (normal < 0.2 m g/L) and 2.8 IU/L (normal < 10 IU/L ), and 24 h creatinine clearance was 38.3 mL/ min per 1.73 m 2 (normal 88 -155 mL/min per 1.73 m 2 ). Renal ultrasonography showed normal morphology of the kidneys, ureters and bladder. The delayed computed tomography (CT) scan indicated bilateral wedge-shaped contrast enhancement in bilateral kidneys.The patient was treated conservatively. All his symptoms subsided by day 3 of hospitalization, and sCr and BUN decreased to within the normal range on day 8. The patient was discharged on day 11. The serum concentration of UA, however, decreased markedly to 0.5 mg/dL after the ARF episode. On the basis of these fi ndings, he was diagnosed as having renal hypo-uricemia complicated with exercise-induced ARF.Traditionally, renal hypo-uricemia is classifi ed into fi ve types according to the four-component theory. The renal handling of UA in the present patient was evaluated with oral administration of pyrazinamide, an anti-uricosuric drug, and probenecid and benzbromarone, uricosuric drugs. 7 Renal clearances of urate (C UA ) a...

Airway epithelial cells produce a number of chemokines, including eotaxins. Among the three known eotaxins, T helper (Th) type 2 cytokines have been observed to induce the expression of eotaxin-3 mRNA. This study investigated the effect of interferon (IFN)-gamma, a Th1 cytokine, on Th2 cytokine-induced eotaxin-3 production in a bronchial epithelial cell line, BEAS-2B. BEAS-2B cells produced eotaxin-3 after stimulation with the Th2 cytokines interleukin (IL)-13 and IL-4. When BEAS-2B cells were cultured with varying concentrations of IFN-gamma for 24 h, dose-dependent inhibition of Th2 cytokine-induced eotaxin-3 mRNA expression and protein production was observed. This was associated with downregulation of signal transducer and activator of transcription 6 activation. On the other hand, 2-d pretreatment of BEAS-2B cells with IFN-gamma dose-dependently enhanced Th2 cytokine-induced eotaxin-3 mRNA expression and production. IFN-gamma also increased the mRNA expression and protein production of IL-4 receptor (R) alpha in a time- and dose-dependent manner. In addition, IL-2Rgamma, a component of the type 1 IL-4R, was also upregulated by IFN-gamma. These results indicate that IFN-gamma has opposite effects on Th2 cytokine-induced eotaxin-3 production in BEAS-2B cells, depending on the length of exposure. Because high levels of IFN-gamma are produced during viral infection, airway viral infection may affect allergic airway inflammation in vivo by modulation of eotaxin-3 production.