Yoshifumi Saito

Anticholestatic effects of bezafibrate in patients with primary biliary cirrhosis treated with ursodeoxycholic acid

Bezafibrate is a widely used hypolipidemic agent and is known as a ligand of the peroxisome proliferator‐activated receptors (PPARs). Recently this agent has come to be recognized as a potential anticholestatic medicine for the treatment of primary biliary cirrhosis (PBC) that does not respond sufficiently to ursodeoxycholic acid (UDCA) monotherapy. The aim of this study was to explore the anticholestatic mechanisms of bezafibrate by analyzing serum lipid biomarkers in PBC patients and by cell‐based enzymatic and gene expression assays. Nineteen patients with early‐stage PBC and an incomplete biochemical response to UDCA (600 mg/day) monotherapy were treated with the same dose of UDCA plus bezafibrate (400 mg/day) for 3 months. In addition to the significant improvement of serum biliary enzymes, immunoglobulin M (IgM), cholesterol, and triglyceride concentrations in patients treated with bezafibrate, reduction of 7α‐hydroxy‐4‐cholesten‐3‐one (C4), a marker of bile acid synthesis, and increase of 4β‐hydroxycholesterol, a marker of CYP3A4/5 activity, were observed. In vitro experiments using human hepatoma cell lines demonstrated that bezafibrate controlled the target genes of PPARα, as well as those of the pregnane X receptor (PXR); down‐regulating CYP7A1, CYP27A1, and sinusoidal Na+/taurocholate cotransporting polypeptide (NTCP), and up‐regulating CYP3A4, canalicular multidrug resistance protein 3 (MDR3), MDR1, and multidrug resistance‐associated protein 2 (MRP2). Conclusion: Bezafibrate is a dual PPARs/PXR agonist with potent anticholestatic efficacy in early‐stage PBC patients with an incomplete biochemical response to UDCA monotherapy. (HEPATOLOGY 2013)

A new, effective and safe therapeutic option using proton irradiation for hepatocellular carcinoma

BACKGROUND/AIMS Conventional radiation is almost useless for hepatocellular carcinoma (HCC) because of the severe adverse effects of the irradiation to the accompanying liver cirrhosis. In contrast, the proton beam has Bragg peak, which limits distribution of the beam. The aim of this study was to prove the usefulness of proton irradiation for HCC. METHODS The proton irradiation was performed in 32 nodular lesions in 24 patients with HCC who had unresectable tumors or serious complications; the proton irradiation was performed either as monotherapy (15 lesions) or as combination therapy to insufficient Lipiodol-targeted chemotherapy (Kodama Co. Ltd., Tokyo, Japan) (17 lesions). The energy was 250 MeV, and 50-87 Gy (76.5 +/- 9.5, mean +/- SD) in total was irradiated for a time period of 17-69 days. RESULTS After 1 year, size reduction was seen in 12 out of 13 lesions (92%) in the monotherapy group and 9 out of 9 lesions (100%) in the combination therapy group; after 2 years, size reduction was seen 4 out of 5 lesions (80%) in the monotherapy group and 5 out of 5 lesions (100%) in the combination therapy group. Local tumor control has being assured for 2 years of the observation, which is continuing for another 2 years. None of the patients have experienced any serious adverse effects. CONCLUSIONS These results show that proton irradiation is a new, safe, and effective therapeutic option in cases of HCC, even in patients with unresectable tumors or those with serious complications.

Cholesterol 25-hydroxylation activity of CYP3A

To date, many studies have been conducted using 25-hydroxycholesterol, which is a potent regulator of lipid metabolism. However, the origins of this oxysterol have not been entirely elucidated. Cholesterol 25-hydroxylase is one of the enzymes responsible for the metabolism of 25-hydroxycholesterol, but the expression of this enzyme is very low in humans. This oxysterol is also synthesized by sterol 27-hydroxylase (CYP27A1) and cholesterol 24-hydroxylase(CYP46A1), but it is only a minor product of these enzymes. We now report that CYP3A synthesizes a significant amount of 25-hydroxycholesterol and may participate in the regulation of lipid metabolism. Induction of CYP3A by pregnenolone-16α-carbonitrile caused the accumulation of 25-hydroxycholesterol in a cell line derived from mouse liver. Furthermore, treatment of the cells with troleandomycin, a specific inhibitor of CYP3A, significantly reduced cellular 25-hydroxycholesterol concentrations. In cells that overexpressed human recombinant CYP3A4, the activity of cholesterol 25-hydroxylation was found to be higher than that of cholesterol 4β-hydroxylation, a known marker activity of CYP3A4. In addition, 25-hydroxycholesterol concentrations in normal human sera correlated positively with the levels of 4β-hydroxycholesterol (r = 0.650, P < 0.0001, n = 78), but did not significantly correlate with the levels of 27-hydroxycholesterol or 24S-hydroxycholesterol. These results demonstrate the significance of CYP3A on the production of 25-hydroxycholesterol.

Clinical features of gastroduodenal injury associated with long-term low-dose aspirin therapy

Low-dose aspirin (LDA) is clinically used for the prevention of cardiovascular and cerebrovascular events with the advent of an aging society. On the other hand, a very low dose of aspirin (10 mg daily) decreases the gastric mucosal prostaglandin levels and causes significant gastric mucosal damage. The incidence of LDA-induced gastrointestinal mucosal injury and bleeding has increased. It has been noticed that the incidence of LDA-induced gastrointestinal hemorrhage has increased more than that of non-aspirin non-steroidal anti-inflammatory drug (NSAID)-induced lesions. The pathogenesis related to inhibition of cyclooxygenase (COX)-1 includes reduced mucosal flow, reduced mucus and bicarbonate secretion, and impaired platelet aggregation. The pathogenesis related to inhibition of COX-2 involves reduced angiogenesis and increased leukocyte adherence. The pathogenic mechanisms related to direct epithelial damage are acid back diffusion and impaired platelet aggregation. The factors associated with an increased risk of upper gastrointestinal (GI) complications in subjects taking LDA are aspirin dose, history of ulcer or upper GI bleeding, age > 70 years, concomitant use of non-aspirin NSAIDs including COX-2-selective NSAIDs, and Helicobacter pylori (H. pylori) infection. Moreover, no significant differences have been found between ulcer and non-ulcer groups in the frequency and severity of symptoms such as nausea, acid regurgitation, heartburn, and bloating. It has been shown that the ratios of ulcers located in the body, fundus and cardia are significantly higher in bleeding patients than the ratio of gastroduodenal ulcers in patients taking LDA. Proton pump inhibitors reduce the risk of developing gastric and duodenal ulcers. In contrast to NSAID-induced gastrointestinal ulcers, a well-tolerated histamine H2-receptor antagonist is reportedly effective in prevention of LDA-induced gastrointestinal ulcers. The eradication of H. pylori is equivalent to treatment with omeprazole in preventing recurrent bleeding. Continuous aspirin therapy for patients with gastrointestinal bleeding may increase the risk of recurrent bleeding but potentially reduces the mortality rates, as stopping aspirin therapy is associated with higher mortality rates. It is very important to prevent LDA-induced gastroduodenal ulcer complications including bleeding, and every effort should be exercised to prevent the bleeding complications.

Multiple regression analysis for assessing the growth of small hepatocellular carcinoma: The MIB-1 labeling index is the most effective parameter

Abstract: The aim of this study was to clarify whether histological parameters reflected tumor aggressiveness in patients with hepatocellular carcinoma (HCC). The tumor volume doubling times (TVDTs) of 21 HCCs, less than 3 cm in diameter at the start of the observation period, were calculated in 21 patients in whom the natural progression of the lesion was observed by ultrasonography. Paraffin-embedded sections were prepared from samples obtained by ultrasound-guided fine-needle liver biopsy at the end of the observation period. The histological parameters examined were the MIB-1 labeling index (LI), for which we performed immunohistochemical staining with the MIB-1 monoclonal antibody, using an antigen retrieval method; the nucleo-cytoplasmic (N/C ratio), cellularity, and the nuclear form factor (NFF), were calculated with an imaging analyzer. We performed multiple regression analysis for estimating the growth of small HCCs. With the N/C ratio (0.154 ± 0.068; mean ± SD), cellularity (453 ± 21.8 cells/104 μm2), NFF (1.150 ± 0.096), and degree of HCC differentiation as independent variables, only the MIB-1 LI (11.8 ± 6.1%) showed a significant correlation with TVDT (207.5 ± 162.6 days) (r = −0.658; P < 0.05). Compared to the conventional indices of histological atypism tested, i.e., N/C ratio, cellularity NFF, and degree of HCC differentiation, only MIB-1 LI was significantly correlated with small HCC growth rate. The MIB-1 LI may therefore be a simple and useful index of tumor aggressiveness.

Serum concentration of 27-hydroxycholesterol predicts the effects of high-cholesterol diet on plasma LDL cholesterol level

Aim:  The effect of dietary cholesterol on plasma cholesterol concentrations varies widely among individuals. Recent studies suggest that the synthesis of oxysterols is up‐regulated when tissue cholesterol is saturated. The present study was undertaken to test the hypothesis that a serum high concentration of 27‐hydroxycholesterol, one of the oxysterols, reflects positive cholesterol balance in the body and predicts intolerance to a high‐cholesterol diet.

Bile acid malabsorption deactivates pregnane X receptor in patients with Crohn's disease.

Background:Recent studies have suggested that the downregulation of pregnane X receptor (PXR) may contribute to the susceptibility and exacerbation of Crohn’s disease (CD). Because bile acid malabsorption is one of the features of CD and bile acids are potential activators of PXR, we explored the relationship between bile acid malabsorption and PXR activities in patients with CD. Methods:Twenty-one patients with CD (4 ileal-resected and 17 nonresected), 10 with ulcerative colitis (UC), and 26 healthy controls were studied. Serum biomarkers for the activity of CYP3A4, a target gene of PXR, and for cholesterol and bile acid metabolism were quantified by liquid chromatography-tandem mass spectrometry or enzyme-linked immunosorbent assay. Results:The concentrations of 4&bgr;-hydroxycholesterol (4&bgr;-HC), a known marker for CYP3A4 activity, and those of 25-hydroxycholesterol (25-HC), another metabolite by CYP3A4, were significantly reduced in all patients with CD, especially in those with the history of ileal resection. The concentration of 7&agr;-hydroxy-4-cholesten-3-one (C4), a marker for hepatic bile acid biosynthesis, was significantly elevated, whereas the levels of fibroblast growth factor 19 (FGF19), a marker for intestinal bile acid flux, were reduced in patients with CD compared with patients with UC and controls. A significant negative correlation was observed between 4&bgr;-HC or 25-HC and C4 concentrations in all patients with CD. Conclusions:The degree of bile acid malabsorption was closely associated with the deactivation of PXR in CD. Enterohepatic circulation of bile acids is a key factor for preservation of baseline activity of hepatointestinal PXR.

Small-bowel mucosal injuries in low-dose aspirin users with obscure gastrointestinal bleeding.

AIM To investigate the clinical differences between small intestinal injuries in low-dose aspirin (LDA) users and in non-steroidal anti-inflammatory drug (NSAID) users who were examined by capsule endoscopy (CE) for obscure gastrointestinal bleeding (OGIB). METHODS A total of 181 patients who underwent CE for OGIB were included in this study. Based on clinical records, laboratory data such as hemoglobin levels, major symptoms, underlying diseases, the types and duration of LDA and NSAID use, and endoscopic characteristics of CE were reviewed. RESULTS Out of a total of 45 cases of erosive lesions, 27 cases were taking LDA or NSAIDs (7 were on NSAIDs, 9 were on LDA alone, 9 were on LDA and thienopyridine, and 2 were on LDA and warfarin).The prevalence of ulcers or erosion during chronic use of LDA, LDA and the anti-platelet drug thienopyridine (clopidogrel or ticlopidine), and NSAIDs were 64.3%, 80.0%, and 75.0%, respectively. Erosive lesions were observed predominantly in chronic LDA users, while ulcerative lesions were detected mainly in NSAID users. However, concomitant use of thienopyridine such as clopidogrel with LDA increased the proportion of ulcers. The erosive lesions were located in the whole of the small intestine (jejunum and ileum), whereas ulcerative lesions were mainly observed in the ileum (P < 0.05). CONCLUSION Our CE findings indicate that chronic LDA users and NSAID users show different types and locations of small-bowel mucosal injuries. The concomitant use of anti-platelet drugs with LDA tends to exacerbate the injuries from LDA-type to NSAID-type injuries.

Serum carnitine as an independent biomarker of malnutrition in patients with impaired oral intake

Carnitine is a vitamin-like compound that plays important roles in fatty acid β-oxidation and the control of the mitochondrial coenzyme A/acetyl-CoA ratio. However, carnitine is not added to ordinary enteral nutrition or total parenteral nutrition. In this study, we determined the serum carnitine concentrations in subjects receiving ordinary enteral nutrition (EN) or total parenteral nutrition (TPN) and in patients with inflammatory bowel diseases to compare its levels with those of other nutritional markers. Serum samples obtained from 11 EN and 11 TPN patients and 82 healthy controls were examined. In addition, 10 Crohn’s disease and 10 ulcerative colitis patients with malnutrition who were barely able to ingest an ordinary diet were also evaluated. Carnitine and its derivatives were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The carnitine concentrations in EN and TPN subjects were significantly lower compared with those of the control subjects. Neither the serum albumin nor the total cholesterol level was correlated with the carnitine concentration, although a significant positive correlation was found between the serum albumin and total cholesterol levels. Indeed, patients with CD and UC showed significantly reduced serum albumin and/or total cholesterol levels, but their carnitine concentrations remained normal. In conclusion, only a complete blockade of an ordinary diet, such as EN or TPN, caused a reduction in the serum carnitine concentration. Serum carnitine may be an independent biomarker of malnutrition, and its supplementation is needed in EN and TPN subjects even if their serum albumin and total cholesterol levels are normal.

Impact of determination of hepatitis B virus subgenotype and pre-core/core-promoter mutation for the prediction of acute exacerbation of asymptomatic carriers

Aim:  A large cohort study in Japan revealed that the specific viral profile may influence the fulminant outcome in acute hepatitis B virus (HBV) infections, while the genetic influence on outcome has not been clarified in patients with acute exacerbation of chronic liver disease caused by HBV. We experienced a case of fatal liver failure that developed as the result of chronic HBV infection. To determine possible genetic factor involving acute exacerbation, genetic analysis of serum from the patient and his siblings was performed.