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Japanese herbal medicine, inchinkoto, inhibits inducible nitric oxide synthase induction in interleukin‐1β‐stimulated hepatocytes
Author(s) -
Matsuura Takashi,
Kaibori Masaki,
Araki Yoshiro,
Matsumiya Miho,
Yamamoto Yuka,
Ikeya Yukinobu,
Nishizawa Mikio,
Okumura Tadayoshi,
Kwon AHon
Publication year - 2012
Publication title -
hepatology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.123
H-Index - 75
eISSN - 1872-034X
pISSN - 1386-6346
DOI - 10.1111/j.1872-034x.2011.00891.x
Subject(s) - nitric oxide synthase , proinflammatory cytokine , nitric oxide , transactivation , microbiology and biotechnology , signal transduction , interleukin , chemistry , pharmacology , gene expression , biology , endocrinology , immunology , inflammation , cytokine , biochemistry , gene
Aim: A herbal medicine, kampo inchinkoto (TJ‐135), is used to treat jaundice and liver fibrosis in patients with cirrhosis. In the inflamed liver, proinflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS) gene expression. Over‐production of nitric oxide (NO) by iNOS has been implicated as a factor in liver injury. We examined interleukin (IL)‐1β‐stimulated hepatocytes as a simple in vitro injury model to determine liver‐protective effects of TJ‐135. The objective was to investigate whether TJ‐135 influences iNOS induction and to determine its mechanism. Methods: Primary cultured rat hepatocytes were treated with IL‐1β in the presence or absence of TJ‐135. The induction of iNOS and its signaling pathway were analyzed. Results: IL‐1β produced increased levels of NO. This effect was inhibited by TJ‐135, which exerted its maximal effects at 3 mg/mL. TJ‐135 decreased the levels of iNOS protein and its mRNA expression. Experiments with nuclear extracts revealed that TJ‐135 inhibited the translocation of nuclear factor‐κB (NF‐κB) to the nucleus and its DNA binding. TJ‐135 also inhibited the activation of Akt, resulting in the reduction of type I IL‐1 receptor mRNA and protein expression. Transfection experiments with iNOS promoter‐luciferase constructs demonstrated that TJ‐135 suppressed iNOS induction by inhibition of promoter transactivation and mRNA stabilization. TJ‐135 reduced the expression of an iNOS gene antisense‐transcript. Delayed administration or withdrawal of TJ‐135 after IL‐1β addition also inhibited iNOS induction. Conclusions: Results indicate that TJ‐135 inhibits the induction of iNOS at both transcriptional and post‐transcriptional steps, leading to the prevention of NO production. TJ‐135 may have therapeutic potential for various liver injuries through the suppression of iNOS induction.