The role of macrophages in the development of biliary injury in a lipopolysaccharide-aggravated hepatic ischaemia-reperfusion model.

INTRODUCTION: Endotoxins, in the form of lipopolysaccharides (LPS), are potent inducers of biliary injury. However the mechanism by which injury develops remains unclear. We hypothesized that hepatic macrophages are pivotal in the development of endotoxin-induced biliary injury and that no injury would occur in their absence. MATERIAL AND METHODS: Clodronate liposomes were used to deplete macrophages from the liver. Forty-eight rats were equally divided across six study groups: sham operation (sham), liposome treatment and sham operation (liposomes+sham), 1mg/kg LPS i.p. (LPS), liposome treatment and LPS administration (liposomes+LPS), hepatic ischaemia-reperfusion injury with LPS administration (IRI+LPS) and liposome treatment followed by IRI+LPS (liposomes+IRI+LPS). Following 6h of reperfusion, blood, bile, and liver tissue was collected for further analysis. Small bile duct injury was assessed, serum liver tests were performed and bile composition was evaluated. The permeability of the blood-biliary barrier (BBB) was assessed using intravenously administered horseradish peroxidase (HRP). RESULTS: The presence of hepatic macrophages was reduced by 90% in LPS and IRI+LPS groups pre-treated with clodronate liposomes (P<0.001). Severe small bile duct injury was not affected by macrophage depletion, and persisted in the liposomes+IRI+LPS group (50% of animals) and liposomes+LPS group (75% of animals). Likewise, BBB impairment persisted following macrophage depletion. LPS-induced elevation of the chemokine Mcp-1 in bile was not affected by macrophage depletion. CONCLUSIONS: Depletion of hepatic macrophages did not prevent development of biliary injury following LPS or LPS-enhanced IRI. Cholangiocyte activation rather than macrophage activation may underlie this injury. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Intensive lifestyle treatment for non-alcoholic fatty liver disease in children with severe obesity: inpatient versus ambulatory treatment.

BACKGROUND/AIMS: Lifestyle intervention is the only established therapy for non-alcoholic fatty liver disease (NAFLD). The optimal treatment schedule and predictors of response of this treatment have not been established in children. We aimed to evaluate the 2-year efficacy of an inpatient versus ambulatory intensive lifestyle intervention for treating NAFLD in children with severe obesity. METHODS: A cohort study of 51 severely obese non-diabetic children (mean age 14.7 (±2.4) years; BMI-z-score 3.5 (±0.5)) with liver steatosis were non-randomly allocated to inpatient treatment (2 or 6 months), ambulatory treatment or usual care. Proton Magnetic Resonance Spectroscopy determined liver steatosis and serum alanine aminotransferase (ALT) at 6 months were the primary outcome measures. Baseline variables were evaluated as predictors of treatment response. RESULTS: Liver steatosis had disappeared in 43, 29 and 22% and serum ALT normalized in 41, 33 and 6% at the end of 6 months in the inpatient, ambulatory or usual care treatment groups, respectively. Only the proportions of ALT normalization in inpatient and ambulatory treatment compared with usual care were significantly higher. Treatment effects of inpatient and ambulatory treatment were sustained at 1.5 years follow-up. No baseline characteristic, including PNPLA3 polymorphism or leptin, was consistently predictive for treatment response. CONCLUSIONS: A 6-month intensive inpatient and ambulatory lifestyle treatment in children with severe obesity reverses NAFLD in a minority of patients. This study suggests that inpatient compared with ambulatory intensive treatment does not importantly increase treatment success. Further efforts to optimize and individualize lifestyle interventions and additional treatments options are needed particular for children with severe obesity resistant to conventional lifestyle interventions.

Hepatocellular carcinoma: Dutch guideline for surveillance, diagnosis and therapy.

UNLABELLED: Hepatocellular carcinoma (HCC) is rare in the Netherlands, even though the incidence has increased quite sharply in recent years. Standard treatment options consist of surgery, orthotopic liver transplantation, radiofrequency ablation, transarterial chemoembolisation (TACE) and systemic therapy with sorafenib. The consensus-based Dutch HCC guideline, established in 2013, serves to guide surveillance, diagnosis and treatment options: Surveillance should be performed by ultrasound at six-month intervals in well-defined cirrhotic patients and in selected high-risk hepatitis B carriers; A nodule > 1 cm in cirrhotic patients with arterial hypervascularity and venous or delayed phase washout at four-phase CT or MRI scan establishes the diagnosis of HCC; In patients with HCC without underlying cirrhosis, resection should be considered regardless of tumour size; In cirrhotic HCC patients, tumour stage, severity of underlying cirrhosis, and performance status determine treatment options. The algorithm of the Barcelona Clinic Liver Cancer (BCLC) staging system should be followed; Patients with Child-Pugh A-B cirrhosis (CP < 8 points) and performance status 0-2 are candidates for any active treatment other than transplantation; In early stage HCC (BCLC stage 0 or A, compensated cirrhosis without portal hypertension) surgical resection, liver transplantation, or radiofrequency ablation should be considered; In intermediate stage HCC (BCLC stage B) TACE and÷ or radiofrequency ablation should be considered; In advanced stage HCC (BCLC stage C) sorafenib should be considered. CONCLUSION: The Dutch HCC guideline offers advice for surveillance, diagnosis and treatment of HCC.

Gallstone disease in severely obese children participating in a lifestyle intervention program: incidence and risk factors.

INTRODUCTION: Cholelithiasis is increasingly encountered in childhood and adolescence due to the rise in obesity. As in adults, weight loss is presumed to be an important risk factor for cholelithiasis in children, but this has not been studied. METHODS: In a prospective observational cohort study we evaluated the presence of gallstones in 288 severely obese children and adolescents (mean age 14.1±2.4 years, body mass index (BMI) z-score 3.39±0.37) before and after participating in a 6-month lifestyle intervention program. RESULTS: During the lifestyle intervention, 17/288 children (5.9%) developed gallstones. Gallstones were only observed in those losing >10% of initial body weight and the prevalence was highest in those losing >25% of weight. In multivariate analysis change in BMI z-score (odds ratio (OR) 3.26 (per 0.5 s.d. decrease); 95% CI:1.60-6.65) and baseline BMI z-score (OR 2.32 (per 0.5 s.d.); 95% CI: 1.16-4.70) were independently correlated with the development of gallstones. Sex, family history, OAC use, puberty and biochemistry were not predictive in this cohort. During post-treatment follow-up (range 0.4-7.8 years) cholecystectomy was performed in 22% of those with cholelithiasis. No serious complications due to gallstones occurred. CONCLUSION: The risk of developing gallstones in obese children and adolescents during a lifestyle intervention is limited and mainly related to the degree of weight loss and initial body weight.

Genetic variation in IL28B and treatment outcome in HBeAg-positive and -negative chronic hepatitis B patients treated with Peg interferon alfa-2a and adefovir.

In a cohort of 95 chronic hepatitis B patients, who were treated with peg-interferon and adefovir for 1 year, and who had 15% HBsAg loss (overall), no association was found between IL28B polymorphisms and HBeAg seroconversion or HBsAg clearance. These findings suggest that any association with outcome, if present, is less than that seen in chronic hepatitis C. Additional studies are needed to enlarge sample size and to refine our understanding of IL28B biology in the context of chronic hepatitis B response to immunomodulatory and direct antiviral therapy.

Hepatic unsaturated fatty acids in patients with non-alcoholic fatty liver disease assessed by 3.0T MR spectroscopy.

RATIONALE AND OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) is related to the metabolic syndrome and obesity. Proton magnetic resonance spectroscopy ((1)H MRS) is a non-invasive technique to assess hepatic triglyceride content (HTGC) and allows assessment of unsaturated fatty acids (UFA). There is increasing evidence that hepatic UFA are associated with the development of NAFLD. Therefore the objective of this study was to assess hepatic UFA in patients with NAFLD using (1)H MRS. MATERIALS AND METHODS: We included 26 consecutive patients with deranged liver enzymes, with and without type 2 diabetes mellitus (DM2), suspected for NAFLD. Liver function and metabolic parameters were assessed. (1)H MRS measurements were performed at 3.0T. From the (1)H MR spectra two ratios were calculated: ratio 1 (UFA); unsaturated fatty acid peak vs. reference water peak and ratio 2 (HTGC); total fatty acid peak vs. reference water peak. RESULTS: Twenty-six patients were included. In these patients hepatic UFA (ratio 1) correlated with AST/ALT ratio (r=-0.46, p=0.02), glucose levels (r=0.46, p=0.018), HOMA-IR (r=0.59, p=0.004) and HTGC (r=0.81, p<0.001). In diabetic patients (n=12) hepatic UFA correlated with alkaline phosphatase levels (r=0.72, p=0.01), HOMA-IR (r=0.73, p=0.01) and HTGC (r=0.83, p=0.002). Compared to non-diabetic patients with NAFLD, hepatic UFA levels were increased in patients with DM2 and NAFLD (0.032 vs. 0.014, p=0.03). CONCLUSION: Hepatic UFA can be assessed with (1)H MRS. (1)H MRS determined hepatic UFA correlate with clinical and metabolic parameters associated with NAFLD. Hepatic UFA are increased in patients with DM2. This study provides evidence for the use of non-invasive (1)H MRS to assess hepatic UFA in vivo.

Validation of a sensitive and specific real-time PCR for detection and quantitation of hepatitis B virus covalently closed circular DNA in plasma of chronic hepatitis B patients.

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) serves as a template for viral replication and plays a role in persistence of HBV infection. The origin and significance of cccDNA in plasma however, is not well understood. A sensitive, specific, and reproducible real-time PCR for detection and quantitation of cccDNA in plasma of chronic hepatitis B patients was developed and validated. Four HBV DNA reference panels, and 96 plasma samples of chronic hepatitis B patients were analyzed. Results were compared with total HBV DNA levels, individual ALT levels and the Histology Activity Index (HAI). This cccDNA assay had a lower limit of detection at 15 copies/PCR, a lower limit of quantitation at 91 copies/PCR and a correlation coefficient (R) of 0.98 (P < 0.0001). cccDNA was detected in two of four international panels. Significant correlation was found between cccDNA and total HBV DNA levels in both panels (R = 0.96, and R = 0.43) and in samples of the chronic hepatitis B patients (R = 0.88, P < 0.0001). In 57% of these samples cccDNA was detectable. Mean level of cccDNA was 0.16% of total HBV load. Plasma cccDNA levels were higher in HBeAg positive samples than in HBeAg negative samples (4.91 log copies/ml vs. 3.88 log copies/ml, P < 0.0001). Levels of total HBV DNA and HBV genotype did not influence cccDNA detection. ALT levels and HAI-score were not correlated with plasma cccDNA levels. These findings suggest that cccDNA levels in plasma are not the result of increased hepatocyte degeneration, but indicate that other mechanisms might be responsible.

New developments in the antiviral treatment of hepatitis C.

Chronic hepatitis C virus (HCV) infection is a major cause of liver cirrhosis and hepatocellular carcinoma. HCV is endemic in most parts of the world, with an estimated 170 million people infected worldwide and 3-4 million new cases each year. HCV-related end-stage liver disease is now the main indication for liver transplantation in the USA and Western Europe. Unfortunately, no vaccine or immunoglobulin is available to prevent HCV infection. Currently, HCV treatment consists of the combined administration of pegylated interferon and ribavirin for a period of 24-48 weeks, resulting in complete viral eradication in 40-80% of patients, depending on genotype, viral load and patient characteristics. This therapy is often accompanied with side-effects that affect compliance and reduce treatment outcomes. Recently, reliable in vitro culture systems have been developed which accelerated antiviral therapy research. Many new specifically targeted antiviral therapies for hepatitis C (STAT-C) and treatment strategies are evaluated in clinical trials. These new antiviral agents are expected to improve treatment significantly with potentially shorter treatment duration. The most promising antiviral agents will be reviewed.

CARD15 in inflammatory bowel disease and Crohn's disease phenotypes: an association study and pooled analysis.

BACKGROUND: Three major polymorphisms of the Caspase-Activation Recruitment Domain containing protein 15 gene have been described to be associated with Crohn's disease. Genotype-phenotype studies reported in literature provide conflicting data on disease localisation and behaviour. We investigated the relation of Caspase-Activation Recruitment Domain containing protein 15 with inflammatory bowel disease and Crohn's disease phenotypic characteristics in a large Dutch cohort and performed a pooled analysis on inflammatory bowel disease patients and Crohn's disease phenotypic characteristics reported in association studies. METHODS: We genotyped 781 cases and 315 controls for the R702W, G908R and 1007fsinsC variants and for six microsatellite markers in and close to Caspase-Activation Recruitment Domain containing protein 15. In the pooled analysis data of 7201 inflammatory bowel disease patients and 3720 controls from 20 studies were included. RESULTS: Association was found for Crohn's disease with R702W and 1007fsinsC, including several disease characteristics, and not for ulcerative colitis. In the pooled analysis all three common Caspase-Activation Recruitment Domain containing protein 15 variants showed strong association with Crohn's disease (p<0.00001; odds ratio varying from 3.0 for single heterozygotes to 14.7 for compound heterozygotes) and not with ulcerative colitis. Phenotype analysis showed association with small bowel involvement, stricturing and penetrating disease. CONCLUSION: Caspase-Activation Recruitment Domain containing protein 15 is associated with Crohn's disease and not with ulcerative colitis. All three common Crohn's disease-associated variants are associated with small bowel involvement, the G908R and 1007fsinsC alleles also being associated with a complicated disease course.

Bacterial population analysis of human colon and terminal ileum biopsies with 16S rRNA-based fluorescent probes: commensal bacteria live in suspension and have no direct contact with epithelial cells.

BACKGROUND: The commensal intestinal microflora has important metabolic and perhaps also immune modulatory functions. Evidence has accumulated that the microflora plays a role in the pathogenesis of inflammatory bowel disease. Therefore, there is a growing interest in the intestinal microflora and its interaction with the host. Presumably, this interaction takes place at the mucus layer. In this study, we investigated the microflora that is present at the mucus layer and addressed the following questions. Does a specific mucus-adherent microflora exist? Is there direct contact between commensal bacteria and epithelial cells? METHODS: Snap-frozen biopsies were taken of 5 colon regions and of the terminal ileum in 9 subjects with a normal colon. Fecal samples were also collected. Bacteria were detected in cryosections with fluorescent in situ hybridization (FISH) with 16S ribosomal (r)RNA-targeted probes for all bacteria and specific probes for the major representatives of anaerobic microflora (bifidobacteria, Bacteroides, clostridia, atopobia) and aerobic microflora (Enterobacteriaceae, enterococci, streptococci, lactobacilli). RESULTS: With this sensitive technique, bacteria were only observed at the luminal side of the intestinal mucus layer. Very few microcolonies were present at the mucus layer, and the composition of the bacterial microflora present in the feces was similar to that at the mucus layer of the terminal ileum and colon regions. CONCLUSIONS: We did not observe direct contact between bacteria and epithelial cells. The equal distribution of bacterial species suggests that intestinal commensal bacteria live in suspension in the lumen and that there is no specific mucus-adherent microflora.

Expression of apoptosis related proteins during malignant progression in chronic ulcerative colitis.

BACKGROUND: Chronic ulcerative colitis (CUC) is associated with increased risk of developing colon cancer through a dysplasia (intraepithelial neoplasia)-carcinoma sequence. AIMS: To investigate the expression of apoptosis and inflammatory related proteins in CUC. METHODS: The expression of proteins involved in apoptosis and inflammation (inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), Bcl-xl, Fas, and active caspase 3) was investigated and compared with that seen in sporadic colon carcinoma. RESULTS: COX-2 was negative in the epithelium of all samples. iNOS was clearly present in inflammatory areas in CUC epithelium, weakly expressed in dysplasia, and absent or weakly expressed in tumour cells. Bcl-xl was absent in CUC, increased in dysplasia, and highly expressed in most carcinomas. Fas expression was positive in the surface epithelium of CUC, dysplasia, and most tumour cells. Activated caspase 3 was weakly positive in all samples, indicating limited apoptosis. Compared with CUC associated carcinoma, iNOS was consistently expressed in sporadic colon carcinoma cells, whereas Bcl-xl was almost absent in these tumour cells and Fas was only weakly expressed. Activated caspase 3 was present in normal mucosal samples and some tumour cells. CONCLUSION: Apoptosis related proteins--particularly iNOS, Bcl-xl, and Fas-show a distinct pattern of expression in the CUC to carcinoma sequence, which differs from that seen in sporadic carcinoma, but bears a striking resemblance to that seen during neoplastic progression in Barrett's oesophagus. These results support a causal role for chronic inflammation in cancer development in CUC, and treatment of ulcerative colitis should aim to minimise inflammation.

[Improved survival and less hepatocellar carcinoma following the successful treatment of chornic hepatitis B]. / Verbeterde overleving en minder hepatocellulair carcinoom na succesvolle behandeling van chronische hepatitis B.

Successful therapy of hepatitis B e antigen(HBeAg)-positive chronic hepatitis-B patients with interferon alpha leads to HBeAg-seroconversion. The long-term results show that HBeAg-seroconversion is more than a laboratory parameter. In the long run, therapy-induced HBeAg-seroconversion leads to improved survival and a reduced risk for the development of hepatocellular carcinoma. It is striking that cirrhosis was seen twice as often among the responders to interferon therapy as among the non-responders; this could well be an expression of the degree of inflammation in the liver, which is also higher in responders.

[Nonalcoholic steatohepatitis: diagnosis, pathogenesis, treatment and prognosis]. / Niet-alcoholische steatohepatitis: diagnostiek, pathogenese, behandeling en prognose.

Nonalcoholic steatohepatitis and chronic viral hepatitis C are the two dominant liver diseases in the Netherlands. Hepatic steatosis is usually innocuous but in twenty percent of patients it develops into steatohepatitis. One-fifth of these patients develop liver cirrhosis and hepatocellular carcinoma can also be a consequence of the disease. Nonalcoholic steatohepatitis is characterized by macrovesicular steatosis, necroinflammation, loss ofhepatocytes and fibrosis. Nonalcoholic steatohepatitis often is associated with type 2 diabetes mellitus, hypertension, dyslipoproteinemia and obesity. Insulin resistance plays a major role in the pathogenesis of this disease. Drugs against insulin resistance can ameliorate nonalcoholic steatohepatitis. Gradual weight loss, a diet including polyunsaturated fatty acids and exercise are other important treatment components of this condition.

Nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is an underdiagnosed liver disease characterised by steatosis, necroinflammation and fibrosis. This disease may eventually develop into cirrhosis and hepatocellular carcinoma. NASH is highly prevalent among obese individuals and among patients with diabetes mellitus type 2. Nonalcoholic fatty liver (NAFL), a precursor of NASH, is the main cause of elevated serum liver enzymes among the general population. Insulin resistance is a major aetiological factor in NASH. Gradual weight loss, physical exercise and drugs that improve insulin sensitivity are potential therapies.

Increased incidence of azathioprine-induced pancreatitis in Crohn's disease compared with other diseases.

BACKGROUND: Azathioprine is widely used in Crohn's disease. A major drawback is the occurrence of side-effects, especially acute pancreatitis. Acute pancreatitis is rarely seen when azathioprine is used for other diseases than Crohn's disease. AIM: To survey side-effects of azathioprine after liver or renal transplantation, for systemic lupus erythematosis, Wegener's granulomatosis, autoimmune hepatitis, rheumatoid arthritis, ulcerative colitis or Crohn's disease. METHODS: A computerized search using the term 'azathioprine' or 'imuran' was performed on the Hospital Information System of the university hospital Groningen, resulting in 1564 patients matching our criteria. RESULTS: Eleven of 224 patients with Crohn's disease experienced acute pancreatitis (4.9%) compared with two of 129 (1.5%) with autoimmune hepatitis, two of 388 (0.5%) after renal transplantation, one of 254 (0.4%) after liver transplantation. Acute pancreatitis was more prevalent in Crohn's disease compared with any other disease. Azathioprine-toxicity necessitating withdrawal occurred significantly (P < 0,05) more in rheumatoid arthritis (78 of 317), ulcerative colitis (20 of 94) and Crohn's disease (52 of 224) compared with systemic lupus erythematosis (five of 73), Wegener's granulomatosis (six of 85), autoimmune hepatitis (eight of 129), after liver transplantation (17 of 254) and after renal transplantation (22 of 388). CONCLUSIONS: Acute pancreatitis is strongly associated with Crohn's disease and rarely occurs with other underlying conditions. Overall azathioprine-induced toxicity and the necessity of withdrawal is more common in inflammatory bowel disease and rheumatoid arthritis compared with other diseases.

Chronic inflammation, apoptosis and (pre-)malignant lesions in the gastro-intestinal tract.

Inflammatory conditions are characterized by activation of the transcription factor nuclear factor kappa B (NF-kappaB), resulting in the expression of NF-kappaB-regulated, inflammation-related genes, such as inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2). Expression of these genes contributes to the survival of cells. Indeed, exposure to pro-inflammatory cytokines in the absence of NF-kappaB activation leads to apoptosis.(1,2) Chronic inflammatory conditions are accompanied by constitutive activation of NF-kappaB and hence, to the continuous expression of pro-survival genes, as has been observed in chronic gastritis.(3) Although beneficial for the survival of cells during exposure to inflammatory stress, the continuous activation of NF-kappaB may also pose a risk: cells with a pro-survival phenotype may give rise to continuously proliferating cells and may thus be tumorigenic. Progression to a malignant phenotype of these cells will most likely involve additional changes in the expression of non-NF-kappaB regulated genes e.g. a shift in the balance of pro- and anti-apoptotic genes towards a more anti-apoptotic phenotype. Literature on inflammation-related genes and the apoptotic balance in pre-malignant and malignant conditions in the gastro-intestinal tract is still scarce and conflicting. In this review, we aim to give an overview of the existing literature and we will focus on inflammation- and apoptosis-related genes in the sequence of normal epithelium-inflamed epithelium-metaplasia-dysplasia-cancer in the gastrointestinal tract, in particular esophagus (Barrett's esophagus: BE), stomach (gastritis) and colon (inflammatory bowel disease: IBD).

Diffuse and intestinal type gastric carcinomas differ in their expression of apoptosis related proteins.

BACKGROUND: Gastric carcinomas can be divided into intestinal and diffuse types, with the last type having a worse prognosis. AIMS: To investigate whether specific patterns in the expression of apoptosis related proteins correlate with carcinoma type and/or prognosis METHODS: The expression of Fas, Bcl-2, Bax, Bcl-xl, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) was studied immunohistochemically and the extent of apoptosis and proliferation was investigated in 11 cases of intestinal type and in eight cases of diffuse type carcinoma. RESULTS: Fas was expressed in all intestinal type and in one diffuse type carcinoma. Bcl-xl was expressed in 10 of 11 intestinal type and in one of eight diffuse type carcinomas. Bcl-2 was expressed in lamina propria immune cells. iNOS was expressed in six of 11 intestinal type and in four of eight diffuse type carcinomas, and COX-2 was expressed in eight of 11 intestinal type and in six of eight diffuse type carcinomas. CONCLUSION: Fas and Bcl-xl expression can differentiate between intestinal type and diffuse type gastric carcinomas. No differences in apoptosis and proliferation between intestinal type and diffuse type gastric carcinomas were observed.

ATP binding cassette transporter gene expression in rat liver progenitor cells.

BACKGROUND AND AIM: Liver regeneration after severe liver damage depends in part on proliferation and differentiation of hepatic progenitor cells (HPCs). Under these conditions they must be able to withstand the toxic milieu of the damaged liver. ATP binding cassette (ABC) transporters are cytoprotective efflux pumps that may contribute to the preservation of these cells. The aim of this study was to determine the ABC transporter phenotype of HPCs. METHODS: HPC activation was studied in rats treated with 2- acetylaminofluorene (2-AAF) followed by partial hepatectomy (PHx). ABC transporter gene expression was determined by real time detection reverse transcription-polymerase chain reaction in isolated HPCs, hepatocytes, cholangiocytes, and cultured progenitor cell-like RLF phi 13 cells and by immunohistochemistry of total liver samples. ABC transporter efflux activity was studied in RLF phi 13 cells by flow cytometry. RESULTS: 2-AAF/PHx treated animals showed increased hepatic mRNA levels of the genes encoding multidrug resistance proteins Mdr1b, Mrp1, and Mrp3. Immunohistochemistry demonstrated expression of Mrp1 and Mrp3 proteins in periportal progenitor cells and of the Mdr1b protein in periportal hepatocytes. Freshly isolated Thy-1 positive cells and cultured RLF phi 13 progenitor cells highly expressed Mrp1 and Mrp3 mRNA while the hepatocyte specific transporters Mdr2, Bsep, Mrp2, and Mrp6 were only minimally expressed. Blocking Mrp activity by MK-571 resulted in accumulation of the Mrp specific substrate carboxyfluorescein in RLF phi 13 cells. CONCLUSION: HPCs express high levels of active Mrp1 and Mrp3. These may have a cytoprotective role in conditions of severe hepatotoxicity.

IBD and genetics: new developments.

BACKGROUND: Inflammatory bowel disease (IBD) is a complex disorder with an aetiology that is only partly understood. Apart from environmental factors, inheritance contributes to IBD. REVIEW: Family studies show an increased risk among family members of a patient with IBD, particularly among first-degree relatives. In twin studies, concordance for disease type and localization is observed. In genetically isolated groups there is a higher prevalence of IBD. For instance. Ashkenazi Jews carry the highest risk. Further evidence comes from animal species that spontaneously develop IBD. Unlike Mendelian inheritance, in complex genetic diseases like IBD, genes are expected to be low penetrant and therefore less prone to selection, which results in higher expected gene frequencies. NOD2/CARD15, the first gene associated with IBD, is a polymorphic gene involved in the innate immune system. The gene has over 60 variations. Three of these play a role in 27% of patients with CD, with a predilection for patients with ileal disease. CONCLUSION: Genetics plays an important role in unravelling the pathogenesis of IBD leading to possible new therapeutic approaches.