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 type

MRP3, an organic anion transporter able to transport anti-cancer drugs

The human multidrug-resistance protein (MRP) gene family contains at least six members: MRP1, encoding the multidrug-resistance protein; MRP2 or cMOAT, encoding the canalicular multispecific organic anion transporter; and four homologs, called MRP3, MRP4, MRP5, and MRP6. In this report, we characterize MRP3, the closest homolog of MRP1. Cell lines were retrovirally transduced with MRP3 cDNA, and new monoclonal antibodies specific for MRP3 were generated. We show that MRP3 is an organic anion and multidrug transporter, like the GS-X pumps MRP1 and MRP2. In Madin–Darby canine kidney II cells, MRP3 routes to the basolateral membrane and mediates transport of the organic anion S-(2,4-dinitrophenyl-)glutathione toward the basolateral side of the monolayer. In ovarian carcinoma cells (2008), expression of MRP3 results in low-level resistance to the epipodophyllotoxins etoposide and teniposide. In short-term drug exposure experiments, MRP3 also confers high-level resistance to methotrexate. Neither 2008 cells nor Madin–Darby canine kidney II cells overexpressing MRP3 showed an increase in glutathione export or a decrease in the level of intracellular glutathione, in contrast to cells overexpressing MRP1 or MRP2. We discuss the possible function of MRP3 in (hepatic) physiology and its potential contribution to drug resistance of cancer cells

La prison du Pied-du-Courant

Background & Aims: We have specified the features of progressive familial intrahepatic cholestasis type 3 and investigated in 31 patients whether a defect of the multidrug resistance 3 gene (MDR3) underlies this phenotype. Methods: MDR3 sequencing liver MDR3 immunohistochemistry, and biliary phospholipid dosage were performed, Results: Liver histology showed a pattern of biliary cirrhosis with patency of the biliary tree. Age at presentation ranged from the neonatal period to early adulthood. Sequence analysis revealed 16 different mutations in 17 patients. Mutations were identified on both alleles in 12 patients and only on 1 allele in 5, Four mutations lead to a frame shift, 2 are nonsense, and 10 are missense, An additional missense mutation probably representing a polymorphism was found in 5 patients, MDR3 mutations were associated with abnormal MDRB canalicular staining and a low proportion of biliary phospholipids, Gallstones or episodes of cholestasis of pregnancy were found in patients or parents. Children with missense mutations had a less severe disease and more often a beneficial effect of ursodeoxycholic acid therapy. Conclusions: At least one third of the patients with a progressive familial intrahepatic cholestasis type 3 phenotype have a proven defect of MDR3, This gene defect should also be considered in adult liver diseases

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

With the introduction of DAA's, 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.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-γ-ELISpot assays. Plasma levels of miR-122 were measured by qPCR.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-γ HCV-specific T cell responses did not change by week 12 of follow-up (77.5 versus 125 SFU/10(6) 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.Our data shows that successful treatment of CHC patients with and without prior RG-101 dosing results in reduction of broad immune activation, and normalization of miR-122 levels (EudraCT: 2014-002808-25).EudraCT: 2014-002808-25

Incidence and prevalence of primary biliary cholangitis in the Netherlands – A nationwide cohort study

Background &amp; Aims: Although primary biliary cholangitis (PBC) is considered a rare disorder, accurate determination of its incidence and prevalence remains challenging due to limited comprehensive population-based registries. We aimed to assess the incidence and prevalence of PBC in the Netherlands over time through the nationwide Dutch PBC Cohort Study (DPCS). Methods: DPCS retrospectively included every identifiable patient with PBC in the Netherlands from 1990 onwards in all 71 Dutch hospitals. Incidence and prevalence were assessed between 2008-2018 by Poisson regression between sex and age groups over time. Results: On the 1st of January 2008, there were 1,458 patients with PBC in the Netherlands. Between 2008-2018, 2,187 individuals were newly diagnosed, 46 were transplanted and 468 died. The yearly incidence of PBC in 2008 was 1.38, increasing to 1.74 per 100,000 persons in 2018. When compared to those aged <45 years, females aged 45-64 years (adjusted incidence rate ratio 4.21, 95% CI 3.76-4.71, p <0.001) and males ≥65 years (adjusted incidence rate ratio 14.41, 95% CI 9.62-21.60, p <0.001) were at the highest risk of being diagnosed with PBC. The male-to-female ratio of patients newly diagnosed with PBC during the study period was 1:14 in those <45 years, 1:10 in patients aged 45-64 years, and 1:4 in those ≥65 years. Point prevalence increased from 11.9 in 2008 to 21.5 per 100,000 persons in 2018. Average annual percent change in this time period was 5.94% (95% CI 5.77-6.15, p <0.05), and was the highest among the population aged ≥65 years (5.69%, 95% CI 5.32-6.36, p <0.001). Conclusions: In this nationwide cohort study, we observed an increase in both the incidence and prevalence of PBC in the Netherlands over the past decade, with marked age and sex differences. Impact and implications:: This nationwide Dutch primary biliary cholangitis (PBC) Cohort Study, including all hospitals in the Netherlands, showed that the incidence and prevalence of PBC have increased over the last decade. The age-dependent PBC incidence rate differed for males (highest risk ≥65 years) and females (highest risk between 45 and 65 years), which may be related to a difference in the timing of exposure to environmental triggers of PBC. The largest increase in PBC prevalence over time was observed in the population aged ≥65 years, which may have implications for the use of second-line therapies. These results therefore indicate that further studies are needed to elaborate on the advantages and disadvantages of add-on therapies in the elderly population