J. Marleen L. de Vree

Tissue Distribution and Induction of Human Multidrug Resistant Protein 3

The multidrug resistance protein (MRP) family consists of several members and, for some of these transporter proteins, distinct roles in multidrug resistance and normal tissue functions have been well established (MRP1 and MRP2) or are still under investigation (MRP3). MRP3 expression studies in human tissues have been largely restricted to the mRNA level. In this report we extended these studies and further explored MRP3 expression at the protein level. Western blot and immunohistochemistry with two MRP3-specific monoclonal antibodies, M3II-9 and M3II-21, showed MRP3 protein to be present in adrenal gland, and kidney and in tissues of the intestinal tract: colon, pancreas, gallbladder, and liver. In epithelia, MRP3 was found to be located at the basolateral sides of cell membranes. In normal liver, MRP3 was detected at lower levels than anticipated from the mRNA data and was found present mainly in the bile ducts. In livers from patients with various forms of cholestasis, MRP3 levels were frequently increased in the proliferative cholangiocytes, with sometimes additional staining of the basolateral membranes of the hepatocytes. This was especially evident in patients with type 3 progressive familial intrahepatic cholestasis. The present results support the view that MRP3 plays a role in the cholehepatic and enterohepatic circulation of bile and in protection within the biliary tree and tissues along the bile circulation route against toxic bile constituents. The possible functional roles for MRP3 in the adrenal gland and in the kidney remain as yet unknown. In a panel of 34 tumor samples of various histogenetic origins, distinct amounts of MRP3 were detected in a limited number of cases, including lung, ovarian, and pancreatic cancers. These findings may be of potential clinical relevance when considering the drug treatment regimens for these tumor types.

FIC1, the protein affected in two forms of hereditary cholestasis, is localized in the cholangiocyte and the canalicular membrane of the hepatocyte

BACKGROUND/AIMS FIC1 (familial intrahepatic cholestasis 1) is affected in two clinically distinct forms of hereditary cholestasis, namely progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis. Here we examined the subcellular localization of this protein within the liver. METHODS Antibodies raised against different epitopes of human FIC1 were used for immunoblot analysis and immunohistochemical detection of FICI. RESULTS Immunoblot analysis of intestine and liver tissue extracts from human, rat and mouse origin indicated that the antibodies raised against FIC1 specifically detected FIC1 as a 140-kDa protein. In the liver homogenate of a PFIC1 patient, FIC1 could not be detected. Analysis of isolated rat liver membrane vesicles indicated that this protein is predominantly present in the canalicular membrane fraction. Immunohistochemical detection of the protein in liver sections confirmed that FIC1 was present in the canalicular membrane, whereas no staining was observed in the PFIC1 patients liver. Double label immunofluorescence of murine liver revealed that FIC1 colocalized with cytokeratin 7 in cholangiocytes. CONCLUSIONS The localization of FIC1 in the canalicular membrane and cholangiocytes suggests that it may directly or indirectly play a role in bile formation since mutations in FICI are associated with severe symptoms of cholestasis.

Immune phenotype and function of natural killer and T cells in chronic hepatitis C patients who received a single dose of anti‐MicroRNA‐122, RG‐101

MicroRNA‐122 is an important host factor for the hepatitis C virus (HCV). Treatment with RG‐101, an N‐acetylgalactosamine‐conjugated anti‐microRNA‐122 oligonucleotide, resulted in a significant viral load reduction in patients with chronic HCV infection. Here, we analyzed the effects of RG‐101 therapy on antiviral immunity. Thirty‐two chronic HCV patients infected with HCV genotypes 1, 3, and 4 received a single subcutaneous administration of RG‐101 at 2 mg/kg (n = 14) or 4 mg/kg (n = 14) or received a placebo (n = 2/dosing group). Plasma and peripheral blood mononuclear cells were collected at multiple time points, and comprehensive immunological analyses were performed. Following RG‐101 administration, HCV RNA declined in all patients (mean decline at week 2, 3.27 log10 IU/mL). At week 8 HCV RNA was undetectable in 15/28 patients. Plasma interferon‐γ‐induced protein 10 (IP‐10) levels declined significantly upon dosing with RG‐101. Furthermore, the frequency of natural killer (NK) cells increased, the proportion of NK cells expressing activating receptors normalized, and NK cell interferon‐γ production decreased after RG‐101 dosing. Functional HCV‐specific interferon‐γ T‐cell responses did not significantly change in patients who had undetectable HCV RNA levels by week 8 post–RG‐101 injection. No increase in the magnitude of HCV‐specific T‐cell responses was observed at later time points, including 3 patients who were HCV RNA–negative 76 weeks postdosing. Conclusion: Dosing with RG‐101 is associated with a restoration of NK‐cell proportions and a decrease of NK cells expressing activation receptors; however, the magnitude and functionality of ex vivo HCV‐specific T‐cell responses did not increase following RG‐101 injection, suggesting that NK cells, but not HCV adaptive immunity, may contribute to HCV viral control following RG‐101 therapy. (Hepatology 2017;66:57–68).

Dietary cholesterol does not normalize low plasma cholesterol levels but induces hyperbilirubinemia and hypercholanemia in Mdr2 P-glycoprotein-deficient mice

BACKGROUND/AIMS Mdr2 P-glycoprotein deficiency in mice (Mdr2(-/-) leads to formation of cholesterol/cholesterol-depleted bile and reduced plasma HDL cholesterol. We addressed the questions: (1) does HDL in Mdr2(-/-) mice normalize upon phospholipid and/or cholesterol feeding, and (2): is the Mdr2(-/-) liver capable of handling excess dietary cholesterol. METHODS Male and female Mdr2(-/-) and Mdr2(+/+) mice were fed diets with or without additional phosphatidylcholine and/or cholesterol. Plasma, hepatic and biliary lipids as well as liver function parameters and expression of transport proteins involved in bile formation were analyzed. RESULTS Feeding excess phospholipids and/or cholesterol did not affect lipoprotein levels in Mdr2(+/+) or Mdr2(-/+) mice. Dietary cholesterol caused hyperbilirubinemia (male +100%; female +500%) and elevated plasma bile salts (male +200%; female +1250%) in Mdr2(-/-) mice only, independent of phospholipids. Bile flow nor biliary bile salt and bilirubin secretion were affected in cholesterol-fed Mdr2(-/-) mice. Elevated plasma bile salts may be related to cholesterol-induced reduction of hepatic Na+-taurocholate cotransporting protein expression in Mdr2(-/-) mice. CONCLUSION Excess dietary phospholipids and cholesterol do not normalize low HDL associated with Mdr2 P-glycoprotein-deficiency. Induction of hyperbilirubinemia and hypercholanemia by dietary cholesterol in Mdr2(-/-) mice delineates the important role of biliary lipid secretion in normal hepatic functioning.

Immune responses in DAA treated chronic hepatitis C patients with and without prior RG-101 dosing

Background&aims: With the introduction of DAAs, the majority of treated chronic hepatitis C patients (CHC) achieve a viral cure. The exact mechanisms by which the virus is cleared after successful therapy, is still unknown. The aim was to assess the role of the immune system and miRNA levels in acquiring a sustained virological response after DAA treatment in CHC patients with and without prior RG‐101 (anti‐miR‐122) dosing. Methods: In this multicenter, investigator‐initiated study, 29 patients with hepatitis C virus (HCV) genotype 1 (n = 11), 3 (n = 17), or 4 (n = 1) infection were treated with sofosbuvir and daclatasvir ± ribavirin. 18 patients were previously treated with RG‐101. IP‐10 levels were measured by ELISA. Ex vivo HCV‐specific T cell responses were quantified in IFN‐&ggr;‐ELISpot assays. Plasma levels of miR‐122 were measured by qPCR. Results: All patients had an SVR12. IP‐10 levels rapidly declined during treatment, but were still elevated 24 weeks after treatment as compared to healthy controls (median 53.82 and 39.4 pg/mL, p = 0.02). Functional IFN‐&ggr; HCV‐specific T cell responses did not change by week 12 of follow‐up (77.5 versus 125 SFU/106 PBMC, p = 0.46). At follow‐up week 12, there was no difference in plasma miR‐122 levels between healthy controls and patients with and without prior RG‐101 dosing. Conclusions: Our data shows that successful treatment of CHC patients with and without prior RG‐101 dosing results in reduction of broad immune activation, and normalisation of miR‐122 levels (EudraCT: 2014‐002808‐25). Trial registration: EudraCT: 2014‐002808‐25. HighlightsDAA treatment is highly effective in chronic hepatitis C patients with and without prior anti‐miR‐122 treatment.Successful treatment of chronic hepatitis C patients results in reduction of broad immune activation.There is no restoration of HCV adaptive immunity after SVR in chronic hepatitis C patients.Plasma miR‐122 levels normalise after successful treatment of chronic hepatitis C virus infection.