Beneficial effects of suplatast tosilate (IPD-1151T) in a rat cystitis model induced by intravesical hydrochloric acid.

OBJECTIVE: To examine the effects of suplatast tosilate (IPD-1151T), a Th2 cytokine inhibitor recently recognized to improve the symptoms in patients with interstitial cystitis (IC), in a rat model of HCl-induced chronic cystitis, to elucidate the possible mechanisms by which the drug improves the symptoms of IC. MATERIALS AND METHODS: Chronic cystitis was induced by intravesical instillation of 0.2 mL of 0.4 m HCl in female adult rats. After a once-daily oral administration of IPD-1151T (0.1-100 mg/kg) or prednisolone (5 mg/kg) for 7 days, cystometry was performed under urethane anaesthesia. The bladder from HCl-induced cystitis rats was also assessed histopathologically. RESULTS: On cystometrography there was frequent voiding in cystitis rats. Administration of IPD-1151T for 7 days after intravesical HCl instillation dose-dependently increased the micturition volume and intercontraction intervals. Treatment with prednisolone had similar therapeutic effects. Histological analyses in the bladder from cystitis rats revealed oedema and infiltration of inflammatory cells such as mast cells and eosinophils in the lamina propria and the transitional epithelial thickening. These histological changes and the number of mast cells and eosinophils were reduced by administration of IPD-1151T or prednisolone. CONCLUSION: The present results indicate that IPD-1151T improves bladder function and pathological changes in HCl-induced cystitis rats, as previously observed in patients with IC. The rat cystitis model induced by HCl could provide useful information for studying proposed therapies for IC which might involve T cell-dependent inflammatory responses as one of its potential pathophysiologies.

Effects of a novel anti-hyperlipidemic agent, S-2E, on blood lipid levels in rats with fructose-induced hypertriglyceridemia.

Using rats with fructose-induced hypertriglyceridemia, an animal model of human hypertriglyceridemia, we investigated whether (+)-(S)-p-[1-(p-tert-butylphenyl)-2-oxo-4-pyrrolidinyl]-methoxybenzoic acid (S-2E), a novel anti-hyperlipidemic agent, reduced the elevated levels of triglyceride (TG) and non-high-density lipoprotein cholesterol (non-HDL-C), and then whether it elevated HDL-C levels. At doses of 3-30 mg/kg, S-2E reduced elevated TG levels and non-HDL-C levels simultaneously in a dose-dependent manner after a week. Furthermore, S-2E treatment at 10 mg/kg for 4 weeks showed similar effects, while the elongation of intervals between feeding periods led to further increases in these levels. Interestingly, S-2E increased blood HDL-C levels after 4 weeks of treatment. It is therefore reasonable to assume that S-2E may be useful to improve dyslipidemia such as hypertriglyceridemia and low levels of HDL-C.

Lafutidine inhibits Helicobacter pylori-induced interleukin-8 production in human gastric epithelial cells.

BACKGROUND AND AIM: Attachment of Helicobacter pylori to gastric epithelial cells leads to the production of chemokines, such as interleukin-8 (IL-8), which in turn activate and recruit neutrophils to the site of infection. Lafutidine [(+/-)-2-(furfurylsulfinyl)-N-(4-(4-(piperidinomethyl)-2-pyridyl)oxy-(Z)-2-butenyl)acetamide] is a new type of antiulcer drug that possesses an antisecretory action as well as gastroprotective activity, independent of its antisecretory action. In the present study, we examined the effects of lafutidine on H. pylori-induced IL-8 release and H. pylori adhesion to MKN45 cells. METHODS: MKN45 cells were stimulated with H. pylori, tumor necrosis factor (TNF)-alpha, or IL-1beta, then IL-6 and IL-8 levels in the culture supernatants were determined with a specific enzyme-linked immunosorbent assay kit. RESULTS: Lafutidine significantly inhibited both the release of IL-8 induced by H. pylori and the adhesion of H. pylori to cells in a dose-dependent manner. These properties of lafutidine are unrelated to the blockade of histamine H(2)-receptors, because the same effects have not been observed with other H(2)-receptor antagonists, such as cimetidine and famotidine. Lafutidine also significantly inhibited H. pylori-induced IL-6 release. Both TNF-alpha and IL-1beta-induced IL-8 releases, conversely, were little affected by lafutidine up to a concentration of 10(-5) M. CONCLUSIONS: These results suggest that lafutidine inhibits IL-8 release by inhibiting H. pylori adherence to gastric epithelial cells, indicating a novel mechanism by which lafutidine protects against the mucosal inflammation associated with H. pylori infection.

Protein kinase C activation by Helicobacter pylori in human gastric epithelial cells limits interleukin-8 production through suppression of extracellular signal-regulated kinase.

Helicobacter pylori (H. pylori) infection of gastric epithelial cells has been shown to induce interleukin (IL)-8 production, but the signal transduction mechanism leading to IL-8 production has not been clearly defined. Here, we investigate the role of protein kinase C (PKC) in the mechanism of induction of IL-8 release by H. pylori in human gastric epithelial cells. In MKN45 cells, H. pylori-induced IL-8 release was enhanced by treatment with PKC inhibitors (GF109203X and calphostin C) and PKC depletion, which completely inhibited PKC activity. Moreover, PKC inhibitors and PKC depletion increased extracellular signal-regulated kinase (ERK) activity and phosphorylation, but not calcium/calmodulin-dependent protein kinase II (CaMK II) activity, in response to H. pylori infection. PKC activated by H. pylori inhibited activation of ERK induced by H. pylori without affecting the CaMK II activity and negatively regulated IL-8 production in human gastric epithelial cells.

Anti-hyperlipidemic action of a newly synthesized benzoic acid derivative, S-2E.

A newly synthesized benzoic acid derivative, (+)-(S)-p-[1-(p-tert-butylphenyl)-2-oxo-4-pyrrolidinyl]methoxybenzoic acid (S-2E), has the capacity to inhibit the biosynthesis of both sterol and fatty acids. Here, we report the mechanism by which S-2E lowers blood cholesterol and triglyceride levels. In the liver, S-2E was converted into its active metabolite, S-2E-CoA. S-2E-CoA noncompetitively inhibited the enzymatic activities of both 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase and acetyl-CoA carboxylase at K(i)=18.11 microM and K(i)=69.2 microM, respectively. Interestingly, pharmacokinetic experiments in rats showed that the concentration of S-2E-CoA in the liver was sufficient to inhibit the activities of HMG-CoA reductase and acetyl-CoA carboxylase, for example, when orally given to rats at 10 mg/kg. Indeed, S-2E (3-30 mg/kg) given orally suppressed the secretion rate of very-low-density lipoprotein (VLDL)-cholesterol and triglyceride in Triton WR-1339-injected rats. Furthermore, S-2E lowered the blood total cholesterol and triglyceride levels simultaneously in Zucker fatty rats. Collectively, S-2E may be useful in the treatment of familial hypercholesterolemia and mixed hyperlipidemia.

Identification of a signaling cascade for interleukin-8 production by Helicobacter pylori in human gastric epithelial cells.

Infecting gastric epithelial cells with Helicobacter pylori (H. pylori) has been shown to induce interleukin-8 (IL-8) production, but the signal transduction mechanism leading to IL-8 production is not defined clearly. In the present study, we investigated the molecular mechanism responsible for H. pylori-induced IL-8 release in human gastric epithelial cells. IL-8 levels in culture supernatants were determined by an enzyme linked-immunosorbent assay. Extracellular signal-regulated kinase (ERK) activity was tested using an in vitro kinase assay, which measured the incorporation of [gamma-33P]ATP into a synthetic peptide that is a specific ERK substrate. ERK phosphorylation and IkappaBalpha degradation by H. pylori infection were assessed by western blotting. In MKN45 cells, H. pylori-induced IL-8 release in a time-dependent manner. This IL-8 release was abolished by treatment with intracellular Ca2+ chelators (BAPTA-AM and TMB-8) but not by EGTA or nifedipine. The Ca2+ ionophore A23187 also induced IL-8 release to an extent similar to that of H. pylori infection. Calmodulin inhibitors (W7 and calmidazolium) and tyrosine kinase inhibitors (genistein and ST638) completely blocked IL-8 release by H. pylori and A23187. PD98059, an ERK pathway inhibitor, completely abolished H. pylori-induced IL-8 release. Moreover, BAPTA-AM, calmidazolium, and genistein, but not nifedipine, suppressed the ERK activation induced by H. pylori infection. PD98059 as well as MG132, an NF-kappaB pathway inhibitor, blocked both IL-8 production and degradation of IkappaBalpha induced by H. pylori infection, whereas only PD98059 inhibited ERK activity in response to H. pylori. There was no significant difference between IL-8 production induced by the cagA positive wild-type strain and the cagA negative isogenic mutant strain of H. pylori; therefore, CagA is not involved in the IL-8 production pathway. H. pylori-induced IL-8 production is dominantly regulated by Ca2+/calmodulin signaling, and ERK plays an important role in signal transmission for the efficient activation of H. pylori-induced NF-kappaB activity, resulting in IL-8 production.

Sensitizing effects of lafutidine on CGRP-containing afferent nerves in the rat stomach.

1. Capsaicin sensitive afferent nerves play an important role in gastric mucosal defensive mechanisms. Capsaicin stimulates afferent nerves and enhances the release of calcitonin gene-related peptide (CGRP), which seems to be the predominant neurotransmitter of spinal afferents in the rat stomach, exerting many pharmacological effects by a direct mechanism or indirectly through second messengers such as nitric oxide (NO). 2. Lafutidine is a new type of anti-ulcer drug, possessing both an antisecretory effect, exerted via histamine H(2) receptor blockade, and gastroprotective activities. Studies with certain antagonists or chemical deafferentation techniques suggest the gastroprotective actions of lafutidine to be mediated by capsaicin sensitive afferent nerves, but this is an assumption based on indirect techniques. In order to explain the direct relation of lafutidine to afferent nerves, we conducted the following studies. 3. We determined CGRP and NO release from rat stomach and specific [(3)H]-resiniferatoxin (RTX) binding to gastric vanilloid receptor subtype 1 (VR1), which binds capsaicin, using EIA, a microdialysis system and a radioreceptor assay, respectively. 4. Lafutidine enhanced both CGRP and NO release from the rat stomach induced by a submaximal dose of capsaicin, but had no effect on specific [(3)H]-RTX and capsaicin binding to VR1. 5. In conclusion, our findings demonstrate that lafutidine modulates the activity of capsaicin sensitive afferent nerves in the rat stomach, which may be a key mechanism involved in its gastroprotective action.