Background: Non‐alcoholic steatohepatitis is a distinct entity, characterized by fatty change, lobular inflammation and fibrosis of the liver. Some cases of non‐alcoholic steatohepatitis progress to cirrhosis, but it is not easy to distinguish this disease from non‐alcoholic fatty liver by non‐invasive examinations. No proven therapy for non‐alcoholic steatohepatitis exists. Transforming growth factor‐β1 is implicated in the development of liver fibrosis, and is inhibited by α‐tocopherol (vitamin E) in the liver. Therefore, in this study, the significance of the measurement of the level of plasma transforming growth factor‐β1 and the effect of α‐tocopherol on the clinical course of non‐alcoholic steatohepatitis were investigated. Methods: Twelve patients with non‐alcoholic steatohepatitis and 10 patients with non‐alcoholic fatty liver, with a diagnosis confirmed by liver biopsy, were studied. None of the patients had a history of alcohol abuse, habitual medicine or malignant or inflammatory diseases. All patients were negative for hepatitis B, C and G virus. Patients were given dietary instruction for 6 months, and then α‐tocopherol (300 mg/day) was given for 1 year. Blood chemistries, measurement of plasma transforming growth factor‐β1 level and liver biopsies were undertaken before and after the 1‐year α‐tocopherol treatment. Results: The serum alanine transaminase level decreased in non‐alcoholic fatty liver patients, but not in non‐alcoholic steatohepatitis patients, after 6 months of dietary therapy. Although the serum alanine transaminase level in non‐alcoholic steatohepatitis patients was reduced during the 1‐year α‐tocopherol treatment, α‐tocopherol had no effect on the serum alanine transaminase level in non‐alcoholic fatty liver patients. The histological findings, such as steatosis, inflammation and fibrosis, of the non‐alcoholic steatohepatitis patients were improved after α‐tocopherol treatment. The plasma transforming growth factor‐β1 level in non‐alcoholic steatohepatitis patients was significantly elevated compared with that in non‐alcoholic fatty liver patients and healthy controls, and decreased, accompanied by an improvement in serum alanine transaminase level, with α‐tocopherol treatment. Conclusions: lOur data suggest that the measurement of the level of plasma transforming growth factor‐β1 represents a possible method of distinguishing between non‐alcoholic steatohepatitis and non‐alcoholic fatty liver. Long‐term α‐tocopherol treatment may be safe and effective for non‐alcoholic steatohepatitis. A randomized, controlled, double‐blind trial is needed to confirm the full potential of α‐tocopherol in the management of non‐alcoholic steatohepatitis.

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The glucocorticoid receptor (GR) is considered to belong to a class of transcription factors, the functions of which are exposed to redox regulation. We have recently demonstrated that thioredoxin (TRX), a cellular reducing catalyst, plays an important role in restoration of GR function in vivo under oxidative conditions. Although both the ligand binding domain and other domains of the GR have been suggested to be modulated by TRX, the molecular mechanism of the interaction is largely unknown. In the present study, we hypothesized that the DNA binding domain (DBD) of the GR, which is highly conserved among the nuclear receptors, is also responsible for communication with TRX in vivo. Mammalian two-hybrid assay and glutathione S-transferase pulldown assay revealed the direct association between TRX and the GR DBD. Moreover, analysis of subcellular localization of TRX and the chimeric protein harboring herpes simplex viral protein 16 transactivation domain and the GR DBD indicated that the interaction might take place in the nucleus under oxidative conditions. Together these observations indicate that TRX, via a direct association with the conserved DBD motif, may represent a key mediator operating in interplay between cellular redox signaling and nuclear receptormediated signal transduction.

Ursodeoxycholic acid (UDCA) is the current mainstay of treatment for various liver diseases including primary biliary cirrhosis. UDCA acts as a bile secretagogue, cytoprotective agent, immunomodulator, and inhibitor of cellular apoptosis. Despite this cumulative evidence of the cytoprotective and immunosuppressive effects of UDCA, both the target molecule and pathway of UDCA action remain unknown. We previously described that, in the absence of glucocorticoid ligand, UDCA activates the glucocorticoid receptor (GR) into DNA binding species but does not elicit its transactivational function in a transient transfection assay. Here we further studied the molecular mechanism of UDCA action and revealed that the ligand binding domain of the GR is responsible for UDCA-dependent nuclear translocation of the GR. Indeed, we demonstrated that UDCA acts on the distinct region of the ligand binding domain when compared with the classical GR agonist dexamethasone, resulting in loss of coactivator recruitment and differential regulation of gene expression by the GR. Our data clearly indicated that UDCA, at least in part via activation of the GR, suppresses NF-B-dependent transcription through the intervention of GR-p65 interaction. Together with the established clinical safety of UDCA, we may propose that UDCA could be a prototypical compound for development of a novel and selective GR modifier. Ursodeoxycholic acid (UDCA)1 is the current mainstay of treatment for primary biliary cirrhosis, which is a chronic cholestatic liver disease characterized by the destruction of biliary epithelial cells (i.e. cholangiocytes), presumably by autoimmune mechanism(s) (1-3). This hydrophilic bile acid is reported to induce biochemical, histological, and prognostic improvement in patients with primary biliary cirrhosis in the virtual absence of adverse reactions (3). UDCA acts as a bile secretagogue and cytoprotective agent (1) and exerts diverse immunomodulatory actions in vitro: suppression of immunoglobulin, interleukin-2, interleukin-4, and interferon-␥ production from lymphocytes; attenuation of major histocompatibility complex expression on hepatocytes and cholangiocytes; increase in natural killer cell activity; and inhibition of eosinophil degranulation (1, 4 -9). Recently, it has been shown that UDCA inhibits cellular apoptosis via stabilization of the mitochondria membrane (10, 11). Despite this cumulative evidence of the cytoprotective and immunosuppressive effects of UDCA, both the target molecule and pathway of UDCA action remain unknown. The glucocorticoid receptor (GR) is a member of the nuclear receptors and an important transcriptional regulator involved in widely diverse physiological functions such as control of embryonic development, cell differentiation, and metabolic homeostasis (12, 13). Moreover, therapeutic activities of glucocorticoids are believed to inevitably be mediated by the GR (14). The nuclear receptors share several structural features (e.g. the ligand binding domain (LBD), DNA binding domain (DBD), and sev...

A number of transcription factors including the glucocorticoid receptor (GR) are regulated in a redox-dependent fashion. We have previously reported that the functional activity of the GR is suppressed under oxidative conditions and restored in the presence of reducing reagents. In the present study, we have used a chimeric human GR fused to the Aequorea green fluorescent protein and demonstrated that both ligand-dependent and -independent nuclear translocation of the GR is impaired under oxidative conditions in living cells. Substitution of Cys-481 for Ser within NL1 of the human GR resulted in reduction of sensitivity to oxidative treatment, strongly indicating that Cys-481 is one of the target amino acids for redox regulation of the receptor. Taken together, we may conclude that redox-dependent regulation of nuclear translocation of the GR constitutes an important mechanism for modulation of glucocorticoid-dependent signal transduction.Glucocorticoids are indispensable not only for maintenance of metabolic homeostasis but also for treatment of a wide variety of human disorders including inflammatory diseases (1-4). Glucocorticoids exert hormone action in target tissues via binding to the glucocorticoid receptor (GR). 1 The GR, as a ligand-inducible transcription factor belonging to the nuclear receptor superfamily, is docked in the cytoplasm in the absence of hormonal ligands. Upon hormone binding, the GR dissociates from hsp90 and translocates into the nucleus to regulate target gene expression (5-8). Previous biochemical studies have proven that GR function is sensitive to redox state in vitro, most possibly via reversible modification of cysteine residues in the GR. For instance, oxidative modification of the GR decreases ligand binding and nonspecific DNA binding activities of the GR in vitro (9 -13). Moreover, we have recently presented evidence demonstrating that glucocorticoid hormone action in vivo is strictly controlled by cellular redox state and cysteine-affinitive metal ions (14 -19). Although a number of transcription factors have been shown to be regulated in a redox-dependent fashion (reviewed in Refs. 20 -22), the molecular mechanism for redox regulation of cellular GR remains largely unknown.From a signal transduction point of view, the glucocorticoid signal that finally influences gene expression must be transmitted to the nucleus via receptor translocation. Therefore, nuclear import of the GR is one of the key control points in regulation of glucocorticoid hormone action. In general, protein transport from the cytoplasm to the nucleus involves the nuclear localization signal (NLS), i.e. short peptide sequences that are necessary and sufficient for nuclear localization of their respective proteins (23). One of the best characterized NLS motifs is that of SV40 large tumor antigen (T-ag) (23). Nuclear import of the GR is mediated by NL1, a stretch of basic amino acids at the immediate C-terminal end of the receptor DNA binding domain, and a second significantly less characterized NLS in the li...

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Ursodeoxycholic acid (UDCA) has been shown to have beneficial effects on patients with primary biliary cirrhosis, suggesting that UDCA has immunomodulating effects. We investigated the effect of UDCA in patients with autoimmune hepatitis (AIH) which is characterized by immunological abnormalities. Eight patients with type 1 AIH were treated with 600 mg of UDCA per day for 2 years. Based on the criteria of the International Autoimmune Hepatitis Group, five patients were diagnosed as definite and three as probable type 1 AIH. Liver function tests were performed every 4 weeks, before and during UDCA therapy and the serum levels of anti-nuclear antibodies (ANA), smooth muscle antibodies (SMA), immunoglobulin G and gamma globulin were determined every 3 months. The levels of serum aspartate aminotransferase and alanine aminotransferase significantly decreased from 154 +/- 24 IU/L and 170 +/- 17 IU/L before UDCA therapy to 31 +/- 3 IU/L and 25 +/- 5 IU/L (P < 0.001) after 1 year of treatment and 28 +/- 2 IU/L and 23 +/- 4 IU/L (P < 0.001) after 2 years of treatment. After 2 years of treatment, the levels of serum immunoglobulin G and gamma globulin significantly decreased (P < 0.05) and ANA titres (5/8 patients) were reduced and SMA (3/5 patients) became negative. Furthermore, hepatic histopathological changes of four patients were assessed after 1 year of treatment, and an improvement of intrahepatic inflammation, but not fibrosis, was observed. In conclusion, these results suggest that UDCA has a beneficial therapeutic effect in patients with type 1 autoimmune hepatitis.

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