Japanese Herbal Medicine Hochuekkito Inhibits the Expression of Proinflammatory Biomarker, Inducible Nitric Oxide Synthase, in Hepatocytes

Abstract

Hochuekkito (TJ-41) is used for the treatment of complaints in patients with general fatigue. However, there is little scientific evidence to demonstrate the liver-protective effects of TJ-41. In the inflamed liver, proinflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS). Overproduction of NO by iNOS has been implicated as a factor in liver injury. We examined proinflammatory cytokine-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of TJ-41. The objective was to investigate whether TJ-41 influences iNOS induction and to determine its mechanism. Primary cultured rat hepatocytes were treated with interleukin (IL)-1β in the presence or absence of TJ-41. The induction of iNOS and its signaling pathway were analyzed. IL-1β produced increased levels of NO. This effect was inhibited by TJ-41, which exerted its maximal effects at 6 mg/ml. TJ-41 decreased the levels of iNOS protein and its mRNA expression. Experiments with nuclear extracts revealed that TJ-41 inhibited the translocation of NF-κB to the nucleus and its DNA binding. TJ-41 also inhibited the activation of Akt, resulting in the reduction of type I IL-1 receptor mRNA and protein expression. Transfection experiments demonstrated that TJ-41 suppressed iNOS induction by the inhibition of promoter transactivation and mRNA stabilization. TJ-41 reduced the expression of an iNOS gene antisense-transcript, which is involved in iNOS mRNA stability. Results indicate that TJ-41 inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. TJ-41 may have therapeutic potential for various liver injuries through the suppression of iNOS induction.

Cinnamomi Cortex and Scutellariae Radix in the Japanese herbal medicine Kampo saireito inhibit expression of iNOS through different mechanisms in hepatocytes

“…We previously reported that four Kampo medicines (inchinkoto (three crude drugs) , hochuekkito (10 crude drugs) , ninjinyoeito (12 crude drugs) and saireito (12 crude drugs) ) and genipin (a component of inchinkoto) showed similar effects on iNOS induction/NO production and the mechanisms involved in two iNOS essential signaling pathways in our IL‐1β‐stimulated cultured hepatocytes.…”

Curcumin protects liver inflammation by suppressing expression of inducible nitric oxide synthase in primary cultured rat hepatocytes

“…7A). In regards to the activation of Akt, we previously found that inchinkoto [48], hochuekito [49], saireito [50], and genipin [51] inhibited phosphorylation of Akt. These compounds also decreased IL-1RI mRNA and protein expression, similar to curcumin.…”

“…The iNOS asRNA interacts with and stabilizes iNOS mRNA [57,58]. We have reported that drugs, such as FR183998 (Na + /H + exchanger inhibitor) [9,10], insulin-like growth factor-I [11], edaravone (free radical scavenger) [14], inchinkoto [48], hochuekito [49], saireito [50], genipin [51], glutamic acid [54], and sivelestat [59] inhibit iNOS induction. This was achieved partly by suppressing iNOS asRNA production in animal models and/or primary cultured hepatocytes.…”

Post-transcriptional inducible gene regulation by natural antisense RNA

“…Many herbal medicines and their constituents have been reported to destabilize iNOS mRNA. The levels of both iNOS mRNA and asRNA iNOS were reduced by hepatoprotective Kampo formulae inchinkoto (106) and hochuekkito (107) and by herbal medicines such as kinginka and its constituent chlorogenic acid (108), gomishi and its constituent gomisin N (109), and chinpi and its constituent nobiletin (110). Reporter assays performed in these studies have suggested that these substances regulate iNOS gene expression at the transcriptional and/or post-transcriptional levels through the 3′UTR of the iNOS mRNA.…”