Kruppel-like factor 15 induces the development of mature hepatocyte-like cells from hepatoblasts.

The liver is an important metabolic organ that controls homeostasis in the body. Moreover, it functions as a hematopoietic organ, while its metabolic function is low during development. Hepatocytes, which are parenchymal cells of the liver, acquire various metabolic functions by the maturation of hepatic progenitor cells during the fetal period; however, this molecular mechanism is still unclear. In this study, Kruppel-like factor 15 (KLF15) was identified as a new regulator of hepatic maturation through a comprehensive analysis of the expression of transcriptional regulators in mouse fetal and adult hepatocytes. KLF15 is a transcription factor whose expression in the liver increases from the embryonic stage throughout the developmental process. KLF15 induced the overexpression of liver function genes in mouse embryonic hepatocytes. Furthermore, we found that the expression of KLF15 could also induce the expression of liver function genes in hepatoblasts derived from human induced pluripotent stem cells (iPSCs). Moreover, KLF15 increased the promoter activity of tyrosine aminotransferase, a liver function gene. KLF15 also suppressed the proliferation of hepatoblasts. These results suggest that KLF15 induces hepatic maturation through the transcriptional activation of target genes and cell cycle control.

Case of hepatitis B virus reactivation after ibrutinib therapy in which the patient remained negative for hepatitis B surface antigens throughout the clinical course.

A 71-year-old man was diagnosed with B-cell chronic lymphocytic leukemia. He was negative for hepatitis B surface antigen (HBsAg), positive for antibodies against the hepatitis B surface and core, and negative for hepatitis B virus (HBV)-DNA before starting chemotherapy. A total of 13 months after the initiation of ibrutinib (a Bruton's tyrosine kinase inhibitor), the patient's alanine aminotransferase levels suddenly increased to 427 U/L. As the level of serum HBV-DNA increased to 5.2 logIU/mL, a diagnosis of HBV reactivation was made, whereas the patient remained negative for HBsAg. The patient's serum alanine aminotransferase levels normalized after the initiation of entecavir at a dose of 1 mg/day. However, it took >1 year to achieve an undetectable level of HBV-DNA, even with an add-on therapy of tenofovir disoproxil fumarate. Interestingly, the patient remained negative for HBsAg throughout the clinical course owing to triple HBsAg escape mutations: Q101K, M133L, and G145A.

Clinicopathological Features of Autoimmune Hepatitis with IgG4-Positive Plasma Cell Infiltration.

BACKGROUND: We aimed to elucidate the characteristics and prognosis of autoimmune hepatitis (AIH) patients with immunoglobulin (Ig) G4-positive plasma cell infiltration. METHODS: We enrolled 84 AIH patients. The number of IgG- and IgG4-positive plasma cells was immunohistochemically counted per high-power field in the portal area. Patients with 3 or more IgG4-positive plasma cells on average and a ratio of IgG4 to IgG-positive plasma cells ≥5% were defined as IgG4-associated AIH (IgG4-AIH), and their clinicopathological characteristics and prognosis were compared to those of the remaining classical-AIH patients. RESULTS: Ten (11.9%) and 74 patients (88.1%) were categorized as IgG4-AIH and classical-AIH patients, respectively. The median age of the IgG4-AIH patients was 67 years, the majority was female (80.0%), and the distribution was similar to that of the classical-AIH patients. The IgG4-AIH patients exhibited significantly more severe phenotypes in portal inflammation, interface hepatitis, fibrosis, and rosette formation. All clinical laboratory data were similar except for serum IgG4 levels, which were higher in IgG4-AIH patients (168.5 vs. 22.9 mg/dL, p = 0.014). During a median follow-up period of 139 months, the relapse rate was significantly lower in the IgG4-AIH group than in the classical-AIH group (11.1 vs. 49.2%; p = 0.048). Twelve (16.2%) and 6 (8.1%) classical-AIH patients underwent liver-related events and liver-related deaths, respectively. In contrast, none of the IgG4-AIH patients progressed to severe liver disease. CONCLUSIONS: The IgG4-AIH patients had more severe inflammation and advanced fibrosis in the liver. However, their prognosis was not poor compared to that of classical-AIH patients. IgG4-AIH may have a phenotype distinct from classical-AIH.

Nineteen-year prognosis in Japanese patients with biopsy-proven nonalcoholic fatty liver disease: Lean versus overweight patients.

BACKGROUND: Many studies have investigated the prognosis of nonalcoholic fatty liver disease (NAFLD); however, most studies had a relatively short follow-up. To elucidate the long-term outcome of NAFLD, we conducted a retrospective cohort study of patients with biopsy-proven NAFLD. METHODS: We re-evaluated 6080 patients who underwent liver biopsy from 1975 to 2012 and identified NAFLD patients without other etiologies. With follow-up these patients, we evaluated the outcome-associated factors. RESULTS: A total of 223 patients were enrolled, 167 (74.9%) was non-alcoholic steatohepatitis (NASH). The median follow-up was 19.5 (0.5-41.0) years and 4248.3 person-years. The risk of type 2 diabetes mellitus (T2DM) and hypertension was 11.7 (95% confidence interval [CI] 8.70-15.6) and 7.99 (95% CI 6.09-10.5) times higher, respectively, in NAFLD patients than in the general population. Twenty-three patients died, 22 of whom had NASH. Major causes of death were extrahepatic malignancy and cardiovascular disease (21.7%) followed by liver-related mortality (13.0%). All-cause mortality was significantly higher in NASH patients than in nonalcoholic fatty liver patients (P = 0.041). In multivariate analysis, older age (hazard ratio [HR] 1.09 [95% CI 1.05-1.14], P<0.001) and T2DM (HR 2.87 [95% CI 1.12-7.04], P = 0.021) were significantly associated with all-cause mortality. The factors significantly associated with liver-related events were older age, T2DM, milder hepatic steatosis, and advanced liver fibrosis. Body mass index wasn't associated with either mortality or liver-related events. CONCLUSIONS: T2DM was highly prevalent in NAFLD patients and was significantly associated with both all-cause mortality and liver-related events. The lean patients' prognosis wasn't necessarily better than that of overweight patients.

Hypothyroidism is a Predictive Factor for Better Clinical Outcomes in Patients with Advanced Hepatocellular Carcinoma Undergoing Lenvatinib Therapy.

Patients with advanced hepatocellular carcinoma (HCC) undergoing molecular targeted therapy often experience non-negligible adverse events (AEs). Paradoxically, certain AEs are reportedly associated with a good prognosis. We aimed to identify factors predictive of treatment duration and overall survival (OS) in patients with HCC undergoing lenvatinib therapy. Forty-six consecutive patients with advanced HCC who received lenvatinib therapy from April 2018 to November 2019 were prospectively followed until November 2019. Treatment efficacy was assessed according to the modified Response Evaluation Criteria in Solid Tumors for 2-3 months after therapy initiation. The disease control rate (DCR) was defined as the percentage of patients with a complete response, partial response, or stable disease. The DCR was 65.2%, with a median survival of 10.2 months. Grade 2/3 hypoalbuminemia resulted in shorter treatment duration. Factors predictive of longer OS were a Child-Pugh score of 5 at baseline and the occurrence of Grade 2/3 hypothyroidism. Conversely, Grade 2/3 hypoalbuminemia was associated with a poorer prognosis. An AE of Grade 2/3 hypothyroidism was associated with a better prognosis in patients receiving lenvatinib treatment for advanced HCC. Continuing anticancer therapy with appropriate thyroid hormone replacement may contribute to longer OS.

The Impact of a Heterozygous SLCO1B3 Null Variant on the Indocyanine Green Retention Test.

Indocyanine green (ICG) retention test is widely used for preoperative evaluation of liver function. OATP1B3 (gene symbol: SLCO1B3) is the major transporter for hepatic ICG uptake. We previously demonstrated that the individuals with a homozygous SLCO1B3 null allele revealed markedly impaired ICG clearance. However, the effect of heterozygosity of this variant on ICG clearance remains unknown. We compared the results of ICG retention rate at 15 min (ICG-R15) and hepatic OATP1B3 expression among individuals whose SLCO1B3 genotype was determined. Although OATP1B3 expression was significantly lower in the heterozygosity than the wild-type, the ICG-R15 results were comparable; 8.4 ± 3.4 (mean ± SD) % in the heterozygosity and 8.7 ± 6.0% in the wild-type. A homozygous individual revealed markedly high ICG-R15 (79.8%) and lacked OATP1B3 expression. In conclusion, the individuals with a heterozygous SLCO1B3 null variant had similar ICG clearance capacity to those with the wild-type despite decreased hepatic OATP1B3 expression.

A Case of Rare Cutaneous Metastasis from Advanced Pancreatic Cancer.

A 71-year-old woman presented to a nearby hospital with an occipital scalp ulcer with exudate. Thoracoabdominal enhanced computed tomography (CT) was performed due to suspected cancer. The imaging results showed tumors in the pancreatic tail and at multiple sites in the lung, whereupon she was referred to our hospital for further investigation. Histological analysis of the occipital scalp ulcer and the pancreatic tumor led to the diagnosis of pancreatic adenocarcinoma with cutaneous metastasis and multiple lung metastases. Combination chemotherapy (gemcitabine and nab-paclitaxel) was started, and about 4 months later the patient experienced right lower back pain. Abdominal CT showed partial sclerosis of the right iliac bone and multiple spinal lesions, which were diagnosed as multiple bone metastases. Narcotic analgesia was started for the right lower back pain. Since then, FOLFIRINOX has been introduced as second-line chemotherapy against tumor growth, and treatment has been ongoing for 10 months since the initial chemotherapy. Pancreatic cancer is a rapidly growing cancer and can show early metastasis to other organs, lymph node metastasis, and peritoneal dissemination; therefore, the prognosis of pancreatic cancer is very poor. Cutaneous metastasis from pancreatic cancer is rare, and only a few cases have been reported. Here, we report an unusual case of pancreatic adenocarcinoma with cutaneous metastasis and multiple lung and bone metastases.

Eosinophilic Cholecystitis Associated with Eosinophilic Granulomatosis with Polyangiitis.

We report a case of eosinophilic cholecystitis associated with eosinophilic granulomatosis with polyangiitis (EGPA) complicated by cerebral hemorrhage. A 60-year-old man presented to a local hospital with a diagnosis of acute cholecystitis, with persistent fever and epigastric pain for 2 weeks. His symptoms persisted despite 3-week hospitalization; therefore, he was transferred to our hospital for further evaluation. Laboratory investigations upon admission showed white blood cells 26,300/µL and significant eosinophilia (eosinophils 61%). Abdominal computed tomography revealed no gallbladder enlargement but a circumferentially edematous gallbladder wall. Additional blood test results were negative for antineutrophil cytoplasmic and perinuclear antineutrophil cytoplasmic antibodies; however, immunoglobulin (Ig)G and IgE levels were high at 1,953 mg/dL and 3,040/IU/mL, respectively. He improved following endoscopic transnasal gallbladder drainage for cholecystitis and was diagnosed with EGPA and received corticosteroid and immunosuppressant combination therapy. The eosinophil count decreased immediately after treatment, and abdominal pain and numbness resolved. He returned with left-sided suboccipital hemorrhage likely attributed to EGPA 6 months after discharge. EGPA is characterized by inflammation of small blood vessels and clinically manifests with an allergic presentation of bronchial asthma, as well as renal dysfunction, interstitial pneumonia, enteritis, and cerebral hemorrhage. Few reports have described cholecystitis as a presenting symptom of EGPA. We report a rare case of such a presentation with added considerations.

Effect of Sodium Glucose Co-Transporter 2 Inhibitors on Liver Fat Mass and Body Composition in Patients with Nonalcoholic Fatty Liver Disease and Type 2 Diabetes Mellitus.

BACKGROUND AND OBJECTIVE: Sodium glucose co-transporter 2 inhibitors increase urinary glucose excretion and reduce visceral adiposity and body weight, but their efficacy on patients with nonalcoholic fatty liver disease has not been sufficiently investigated. The aim of this study was to assess the effect of sodium glucose co-transporter 2 inhibitors on liver fat mass and body composition in patients with nonalcoholic fatty liver disease and type 2 diabetes mellitus. METHODS: We retrospectively analyzed 17 patients with nonalcoholic fatty liver disease and type 2 diabetes who received sodium glucose co-transporter 2 inhibitors between November 2016 and July 2017. Changes in liver fat, subcutaneous and visceral fat, body composition, and liver function-related parameters were assessed after 24 weeks of sodium glucose co-transporter 2 inhibitor treatment and compared to baseline values. RESULTS: Ten patients received dapagliflozin at 5 mg/day and seven patients received canagliflozin at 100 mg/day for 24 weeks. All patients completed the study without any serious adverse effects and achieved body weight loss and improved glycated hemoglobin levels. Liver fat mass evaluated by proton magnetic resonance spectroscopy was significantly reduced (19.1% vs. 9.2%, p < 0.01), and so were both subcutaneous and visceral fat mass. The body fat/body weight ratio decreased, whereas the skeletal muscle mass/body weight ratio increased. Liver function (aspartate aminotransferase, alanine aminotransferase, and γ-glutamyl transpeptidase) improved significantly. CONCLUSIONS: Sodium glucose co-transporter 2 inhibitor treatment not only improved glycemic control but also reduced liver fat mass in patients with nonalcoholic fatty liver disease and type 2 diabetes. Body weight loss was primarily attributable to a reduction in fat mass, especially visceral fat. Thus, sodium glucose co-transporter 2 inhibitors could potentially serve as a therapeutic agent for patients with nonalcoholic fatty liver disease and type 2 diabetes.

Successful Balloon-Occluded Retrograde Transvenous Obliteration for Gastric Varices Using Foam Sclerosant Followed by Glue Embolization of Gastrorenal Shunt via the Brachial Vein Approach in a Severely Obese Patient.

Balloon-occluded retrograde transvenous obliteration is an effective treatment for gastric varices. In this report, we illustrate a consecutive treatment strategy via brachial vein approach and n-butyl cyanoacrylate (NBCA) packing of the gastrorenal shunt (GRS) after injecting sclerosing agent in a severely obese patient. The brachial vein approach reduced the burden on the patient, and the closure of the GRS using NBCA shortened the procedure time. These techniques may improve patient comfort as well as reduce medical costs and the risks of several complications.

Impaired Renal Function May Not Negate the Efficacy of Tolvaptan in the Treatment of Cirrhotic Patients with Refractory Ascites.

BACKGROUND AND OBJECTIVE: Tolvaptan, an oral vasopressin V2 receptor antagonist, has been widely used for the treatment of patients with cirrhosis and ascites. However, its efficacy in patients with renal dysfunction remains unknown. The objective of this study was to investigate the efficacy and safety of tolvaptan in patients with decompensated cirrhosis and severe chronic kidney disease (s-CKD). METHODS: We studied 43 patients with liver cirrhosis who received tolvaptan (7.5 mg/day) for refractory ascites. s-CKD was defined as an estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m2. Response to tolvaptan was defined as weight loss ≥ 1.5 kg in 7 days of treatment. RESULTS: Eighteen patients (42%) had s-CKD (s-CKD group), while the other 25 patients (58%) did not have s-CKD (n-CKD group). Rates of response to tolvaptan were similar: 68% in the n-CKD group and 56% in the s-CKD group. Urine volumes increased significantly from baseline to day 7 in both groups. Incidences of adverse events were also similar (P = 0.93). Mean eGFR did not decline even in the s-CKD group (27.3 ± 2.2 mL/min/1.73 m2 at baseline vs. 26.6 ± 2.3 mL/min/1.73 m2 on day 7; P = 0.9). The cumulative survival rate did not differ significantly between the n-CKD and s-CKD groups. In the s-CKD group, responders obtained a better prognosis than non-responders. CONCLUSIONS: Tolvaptan significantly increased urine volumes similarly in patients with s-CKD and n-CKD without affecting renal function. As responders achieved a better prognosis, tolvaptan could be a good option to treat ascites in patients with cirrhosis and s-CKD.

Culture System of Bile Duct-Like Cystic Structures Derived from Human-Inducible Pluripotent Stem Cells.

Inducible pluripotent stem (iPS) cells are multipotent stem cells that are produced by gene transfer of reprogramming factors to somatic cells. They are thought to be an important source of regenerative medicine because of their pluripotency and self-renewal ability. Although the liver has high regeneration ability, continuous death of hepatocytes due to chronic inflammation leads to liver cirrhosis and liver carcinoma. With regard to such serious liver diseases, liver transplantation is used as a complete cure, but there is a problem of donor shortage. Therefore, transplantation therapy using liver tissue generated from stem cells in vitro is expected.We are developing a system to induce the differentiation of cholangiocytes, one of important non-parenchymal cells in living liver tissue, from human iPS cells. Bile duct-like cystic structures can be induced by purifying human iPS cell-derived hepatoblasts expressing hepatic progenitor cell surface markers and inducing differentiation under appropriate culture conditions. These cells are considered to be useful in constructing a hepatic organoid that reproduces the liver structure of the living body.

Utility of a 3D Roadmap During Balloon-occluded Retrograde Transvenous Obliteration for Gastric Varices.

OBJECTIVE: We describe our initial clinical experience regarding the use of a 3D roadmap during balloon-occluded retrograde transvenous obliteration (BRTO) in three patients. METHODS: Between June 2016 and July 2016, three BRTO procedures were performed in three patients with gastric varices. Preprocedural intravenous dynamic CT was performed, and portal venous phase CT images were postprocessed to obtain volume rendering (VR) images. A 3D roadmap was developed by overlaying the VR images onto the real-time X-ray fluoroscopy images. This 3D roadmap was used for interventional guidance during the BRTO procedure. RESULTS: Using a 3D roadmap, the catheterization of the gastrorenal shunt was successfully accomplished. In addition, in all three patients, the sclerosant could reach the gastric varices without the administration of iodinated contrast medium. Fluoroscopy time and the iodinated contrast dose administered in the present cohort were also substantially lower than in our previous cohorts that did not use a 3D roadmap. CONCLUSION: Using a 3D roadmap during BRTO enables easier and faster catheter manipulation, thereby helping to reduce both radiation exposure and the need to administer iodinated contrast medium.

Foetal hepatic progenitor cells assume a cholangiocytic cell phenotype during two-dimensional pre-culture.

Liver consists of parenchymal hepatocytes and other cells. Liver progenitor cell (LPC) is the origin of both hepatocytes and cholangiocytic cells. The analyses of mechanism regulating differentiation of LPCs into these functional cells are important for liver regenerative therapy using progenitor cells. LPCs in adult livers were found to form cysts with cholangiocytic characteristics in 3D culture. In contrast, foetal LPCs cannot form these cholangiocytic cysts in the same culture. Thus, the transition of foetal LPCs into cholangiocytic progenitor cells might occur during liver development. Primary CD45(-)Ter119(-)Dlk1(+) LPCs derived from murine foetal livers formed ALBUMIN (ALB)(+)CYTOKERATIN (CK)19(-) non-cholangiocytic cysts within 3D culture. In contrast, when foetal LPCs were pre-cultured on gelatine-coated dishes, they formed ALB(-)CK19(+) cholangiocytic cysts. When hepatocyte growth factor or oncostatin M, which are inducers of hepatocytic differentiation, was added to pre-culture, LPCs did not form cholangiocytic cysts. These results suggest that the pre-culture on gelatine-coated dishes changed the characteristics of foetal LPCs into cholangiocytic cells. Furthermore, neonatal liver progenitor cells were able to form cholangiocytic cysts in 3D culture without pre-culture. It is therefore possible that the pre-culture of mid-foetal LPCs in vitro functioned as a substitute for the late-foetal maturation step in vivo.

Off-treatment durability of antiviral response to nucleoside analogues in patients with chronic hepatitis B.

BACKGROUND: Off-treatment durability of nucleoside analogue (NA) therapy in patients with chronic hepatitis B has not been well investigated. In this study we monitored antiviral effect of NA therapy and evaluated off-treatment durability after NA cessation in patients with chronic hepatitis B. PATIENTS AND METHODS: A total of 94 consecutive patients (39 HBeAg-negative and 55 HBeAg-positive patients) who received NA therapy were followed up for approximately 9 years. We discontinued NA according to the following criteria; undetectable serum HBV-DNA by polymerase chain reaction (PCR) on three separate occasions at least 6 months apart in HBeAg-negative patients (APASL stopping recommendation), and seroconversion from HBeAg-positive to HBeAb-positive and undetectable serum HBV-DNA by PCR for at least 12 months in HBeAg-positive patients. RESULTS: The cumulative rate of relapse after NA cessation was 48 % and 40 % in HBeAg-negative and -positive patients, respectively. Higher baseline serum alanine aminotransferase level was the only significant predictor for maintaining remission. No patients experienced decompensation after relapse. HBsAg loss occurred at an annual rate of 1.4 % and 0.4 % in HBeAg-negative and -positive patients, respectively. Hepatocellular carcinoma developed at an annual rate of 0.6 % in both HBeAg-negative and -positive patients. CONCLUSIONS: Almost half of the patients did not relapse after cessation of NA therapy in both HBeAg-negative and -positive patients. Therefore, NA therapy could be discontinued with close monitoring if the APASL stopping recommendation is satisfied even in HBeAg-negative patients.

Effects of ethanol and acetaldehyde load on erythrocyte deformability in healthy subjects and patients with liver cirrhosis.

Alcohol intake leads to the distribution of alcohol and its metabolite, acetaldehyde throughout the blood and organs. Hepatic cirrhosis is associated with abnormal red blood cell morphology and function, particularly impaired red blood cell deformability. To investigate the effect of drinking on red blood cells in patients with hepatic cirrhosis, erythrocyte deformability was evaluated in response to alcohol and acetaldehyde tolerance. Erythrocyte deformability in 10 healthy and 15 cirrhotic subjects was examined by filterability of the red blood cells. Erythrocyte deformability decreased markedly in the cirrhosis group compared with the healthy group (p < 0.05). No significant change in erythrocyte deformability was observed in healthy or cirrhotic subjects due to ethanol 100 mM tolerance. Acetaldehyde tolerance elicited a significant decrease in erythrocyte deformability at 2 mM in the cirrhosis group (p < 0.05). Alcohol consumption in cirrhotic patients was suggested to worsen erythrocyte deformability and red blood cell function. Decreased erythrocyte deformability worsens microcirculation in the liver, resulting in more severe hepatic dysfunction.

A Paracrine Mechanism Accelerating Expansion of Human Induced Pluripotent Stem Cell-Derived Hepatic Progenitor-Like Cells.

Hepatic stem/progenitor cells in liver development have a high proliferative potential and the ability to differentiate into both hepatocytes and cholangiocytes. In this study, we focused on the cell surface molecules of human induced pluripotent stem (iPS) cell-derived hepatic progenitor-like cells (HPCs) and analyzed how these molecules modulate expansion of these cells. Human iPS cells were differentiated into immature hepatic lineage cells by cytokines. In addition to hepatic progenitor markers (CD13 and CD133), the cells were coimmunostained for various cell surface markers (116 types). The cells were analyzed by flow cytometry and in vitro colony formation culture with feeder cells. Twenty types of cell surface molecules were highly expressed in CD13(+)CD133(+) cells derived from human iPS cells. Of these molecules, CD221 (insulin-like growth factor receptor), which was expressed in CD13(+)CD133(+) cells, was quickly downregulated after in vitro expansion. The proliferative ability was suppressed by a neutralizing antibody and specific inhibitor of CD221. Overexpression of CD221 increased colony-forming ability. We also found that inhibition of CD340 (erbB2) and CD266 (fibroblast growth factor-inducible 14) signals suppressed proliferation. In addition, both insulin-like growth factor (a ligand of CD221) and tumor necrosis factor-like weak inducer of apoptosis (a ligand of CD266) were provided by feeder cells in our culture system. This study revealed the expression profiles of cell surface molecules in human iPS cell-derived HPCs and that the paracrine interactions between HPCs and other cells through specific receptors are important for proliferation.

No contribution of the ABCB11 p.444A polymorphism in Japanese patients with drug-induced cholestasis.

European studies have revealed that the ABCB11 c.1331T>C (V444A) polymorphism (rs2287622) C-allele frequency is higher among patients with drug-induced cholestasis. Given the low incidence of this disease, however, this association has not been sufficiently elucidated. We aimed to investigate the significance of this polymorphism in Japanese patients. We determined ABCB11 V444A polymorphism frequencies and HLA genotypes in two independent drug-induced cholestasis cohorts. Expression and taurocholate transport activity of proteins from 444A variants were analyzed using Madin-Darby canine kidney II cells. In cohort 1 (n = 40), the V444A polymorphism C-allele frequency (66%) was lower than that in controls (n = 190, 78%), but this difference was not significant (P = 0.09). In cohort 2 (n = 119), comprising patients with cholestatic (n = 19), hepatocellular (n = 74), and mixed (n = 26) liver injuries, the C-allele frequency was lower among patients with cholestatic liver injury (68%) than among those with hepatocellular (75%) or mixed liver injury (83%), although this difference was not significant. In cohort 1, HLA-A*0201 was observed more frequently in patients (22%) than in controls [11%; P = 0.003; odds ratio, 2.4 (95% confidence interval, 1.4-4.0)]. Taurocholate transport activity of 444A-encoded protein was significantly lower than that of 444V-encoded protein (81% of 444V, P < 0.05) because of the reduced protein stability. In conclusion, ABCB11 444A had slightly reduced transport activity, but it did not contribute to the occurrence of drug-induced cholestasis in Japanese patients. Therefore, genetic susceptibility to acquired cholestasis may differ considerably by ethnicity.