Orengedokuto and berberine improve indomethacin-induced small intestinal injury via adenosine

Background: Recent endoscopic technology has revealed that small intestinal injury is a serious threat to patients receiving nonsteroidal anti-inflammatory drugs (NSAIDs). We previously showed that Japanese herbal medicine, Orengedokuto (OGT; Huang-Lian-Jie-Du-Tang in Chinese), protects mice from lethal indomethacin (IND)-induced enteropathy. To elucidate the mechanism of the protective effect of OGT, we performed microarray analyses and high power statistical analyses of microarray data using new bioinformatics tools. Methods: Female BALB/c mice were subcutaneously injected with IND (20 mg/ kg) once a day for 2 days. OGT-treated mice received a diet containing OGT from the first IND injection until the end of the experiment. Gene expression signals of small intestine were obtained with GeneChip®. Analyses for overrepresentation of Gene Ontology categories were conducted using MetaGene Profiler (MGP) and the changes were visualized by Cell Illustrator Online (CIO). Furthermore, active ingredients of OGT were investigated. Results: MGP and CIO suggested a critical role for the adenosine system, especially adenosine deaminase (ADA), a key enzyme of adenosine catabolism. Quantitative real time RT-PCR and in situ hybridization showed that OGT decreased the expression of ADA, which possibly resulted in the elevation of the anti-inflammatory nucleoside adenosine. Blockade of the adenosine A2a receptor abrogated the protective effect of OGT. Berberine, a major ingredient of OGT, suppressed ADA expression and reduced the incidence of lethality. Conclusions: OGT may prevent IND-induced enteropathy by decreasing ADA which results in the elevation of adenosine. Modulation of the adenosine system may be an efficient therapeutic strategy for NSAID-induced enteropathy.