Nobuhiko Shibakawa

Mechanism for p38α-mediated experimental autoimmune encephalomyelitis

Background: p38 signaling pathway plays a key role in inflammatory diseases. Results: A single copy disruption of the p38α gene or a p38α inhibitor markedly reduced the pathogenesis of EAE by decreasing IL-17 production. Conclusion: p38α regulates the pathogenesis of EAE through transcriptional regulation of IL-17 production. Significance: Anti-p38α strategy achieves therapeutic benefit for the treatment of multiple sclerosis. One of the mitogen-activated protein kinases, p38, has been found to play a crucial role in various inflammatory responses. In this study, we analyzed the roles of p38α in multiple sclerosis, using an animal model, experimental autoimmune encephalomyelitis (EAE). p38α+/− mice (p38α−/− showed embryonic lethality) showed less severe neurological signs than WT mice. Adoptive transfer of lymph node cells (LNC) from sensitized WT mice with MOG(35–55) to naive WT-induced EAE was much more severe compared with the case using LNC from sensitized p38α+/− mice. Comprehensive analysis of cytokines from MOG(35–55)-challenged LNC by Western blot array revealed that production of IL-17 was significantly reduced by a single copy disruption of the p38α gene or a p38 inhibitor. Likewise, by a luciferase reporter assay, an electrophoresis mobility shift assay, and characterization of the relationship between p38 activity and IL-17 mRNA expression, we confirmed that p38 positively regulates transcription of the Il17 gene. Furthermore, oral administration of a highly specific p38α inhibitor (UR-5269) to WT mice at the onset of EAE markedly suppressed the progression of EAE compared with a vehicle group. These results suggest that p38α participates in the pathogenesis of EAE through IL-17 induction.

Pharmacological Profile of Novel Acid Pump Antagonist 7-(4-Fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methyl cyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526)

The pharmacological profiles of the novel acid pump antagonist 7-(4-fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methylcyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526) were investigated in terms of hog gastric H+,K+-ATPase activity, gastric acid secretion, and acute gastroesophageal lesions in comparison with other proton pump inhibitors (PPIs). CS-526 inhibited H+,K+-ATPase activity in a concentration-dependent manner, with an IC50 value of 61 nM. The inhibitory effect of CS-526 on H+,K+-ATPase activity was more potent than that of any of the other PPIs examined. The inhibitory mechanism of CS-526 on H+,K+-ATPase was a competitive antagonism to the K+ binding site of H+,K+-ATPase, and it was also a reversible inhibition. In pylorus-ligated rats, intraduodenal or oral administration of CS-526 inhibited gastric acid secretion in a dose-dependent manner, and the ID50 values were 2.8 or 0.7 mg/kg, respectively. In Heidenhain pouch dogs, intrapouch administration of CS-526 inhibited histamine-stimulated gastric acid secretion in a dose- and retention time-dependent manner. In a reflux esophagitis model, intraduodenal and oral administration of CS-526 prevented esophageal lesions with ID50 values of 5.4 and 1.9 mg/kg, respectively. Lansoprazole prevented esophagitis only by intraduodenal administration (ID50 = 2.2 mg/kg). Furthermore, CS-526 inhibited acute gastric mucosal lesions. These data demonstrate that the novel acid pump antagonist CS-526 has potent antisecretory and antiulcer effects. These findings indicate that CS-526 would have a curative effect on gastroesophageal reflux disease via its potent antisecretory and antiulcer actions.

The Effect of Subchronic Administration of 7-(4-Fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methylcyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526), a Novel Acid Pump Antagonist, on Gastric Acid Secretion and Gastrin Levels in Rats

In the present report, we evaluated the effect of the novel acid pump antagonist 7-(4-fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methylcyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526) and 2-[3-methyl-4-(2,2,2-trifluoro-ethoxy)-pyridin-2-ylmethanesulfinyl]-1H-benzimidazole (lansoprazole) on rebound gastric acid secretion, using an intragastric dialysis membrane perfusion model and on the serum and antral gastrin level after a 14-day treatment in rats. The effect of CS-526 on gastric acid secretion was almost constant during the 14 days of treatment. After the 14-day treatment, gastric acid secretion had returned to pretreatment levels. However, CS-526 slightly increased and lansoprazole potently increased gastric acid secretion thereafter. In the posttreatment period, the influence on rebound gastric acid secretion by lansoprazole treatment was significant, but that by CS-526 was not. The serum gastrin concentration after the 14-day treatment with CS-526 did not increase significantly, even at 100 mg/kg/day. On the other hand, lansoprazole at 100 mg/kg/day significantly elevated the serum gastrin concentration. After the 14-day treatment with CS-526 at 100 mg/kg/day, the antral gastrin content significantly increased. Lansoprazole at the doses of 30 and 100 mg/kg/day also significantly increased the antral gastrin content after the 14-day treatment. The elevation of the serum gastrin level after the lansoprazole treatment was suppressed by the concomitant administration of CS-526. In conclusion, CS-526 has a potent antisecretory effect on gastric acid secretion without rebound gastric hypersecretion. Moreover, CS-526 had minimal effects on the serum and antral gastrin elevation. It is suggested that these effects on gastric acid secretion and serum gastrin after subchronic treatment with CS-526 would be beneficial in clinical use.

The effect of subchronic administration of CS-526, a novel acid pump antagonist, on gastric acid secretion and gastrin levels in rats

In the present report, we evaluated the effect of the novel acid pump antagonist 7-(4-fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methylcyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526) and 2-[3-methyl-4-(2,2,2-trifluoro-ethoxy)-pyridin-2-ylmethanesulfinyl]-1H-benzimidazole (lansoprazole) on rebound gastric acid secretion, using an intragastric dialysis membrane perfusion model and on the serum and antral gastrin level after a 14-day treatment in rats. The effect of CS-526 on gastric acid secretion was almost constant during the 14 days of treatment. After the 14-day treatment, gastric acid secretion had returned to pretreatment levels. However, CS-526 slightly increased and lansoprazole potently increased gastric acid secretion thereafter. In the posttreatment period, the influence on rebound gastric acid secretion by lansoprazole treatment was significant, but that by CS-526 was not. The serum gastrin concentration after the 14-day treatment with CS-526 did not increase significantly, even at 100 mg/kg/day. On the other hand, lansoprazole at 100 mg/kg/day significantly elevated the serum gastrin concentration. After the 14-day treatment with CS-526 at 100 mg/kg/day, the antral gastrin content significantly increased. Lansoprazole at the doses of 30 and 100 mg/kg/day also significantly increased the antral gastrin content after the 14-day treatment. The elevation of the serum gastrin level after the lansoprazole treatment was suppressed by the concomitant administration of CS-526. In conclusion, CS-526 has a potent antisecretory effect on gastric acid secretion without rebound gastric hypersecretion. Moreover, CS-526 had minimal effects on the serum and antral gastrin elevation. It is suggested that these effects on gastric acid secretion and serum gastrin after subchronic treatment with CS-526 would be beneficial in clinical use.