Anne-miek van Loenen-Weemaes

Comparison of effects of VDR versus PXR, FXR and GR ligands on the regulation of CYP3A isozymes in rat and human intestine and liver

In this study, we compared the regulation of CYP3A isozymes by the vitamin D receptor (VDR) ligand 1 alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) against ligands of the pregnane X receptor (PXR), the glucocorticoid receptor (GR) and the farnesoid X receptor (FXR) in precision-cut tissue slices of the rat jejunum, ileum, colon and liver, and human ileum and liver. In the rat, 1,25(OH)(2)D(3) strongly induced CYP3A1 mRNA, quantified by qRT-PCR, along the entire length of the intestine, induced CYP3A2 only in ileum but had no effect on CYP3A9. In contrast, the PXR/GR ligand, dexamethasone (DEX), the PXR ligand, pregnenolone-16 alpha carbonitrile (PCN), and the FXR ligand, chenodeoxycholic acid (CDCA), but not the GR ligand, budesonide (BUD), induced CYP3A1 only in the ileum, none of them influenced CYP3A2 expression, and PCN, DEX and BUD but not CDCA induced CYP3A9 in jejunum, ileum and colon. In rat liver, CYP3A1, CYP3A2 and CYP3A9 mRNA expression was unaffected by 1,25(OH)(2)D(3), whereas CDCA decreased the mRNA of all CYP3A isozymes; PCN induced CYP3A1 and CYP3A9, BUD induced CYP3A9, and DEX induced all three CYP3A isozymes. In human ileum and liver, 1,25(OH)(2)D(3) and DEX induced CYP3A4 expression, whereas CDCA induced CYP3A4 expression in liver only. In conclusion, the regulation of rat CYP3A isozymes by VDR, PXR, FXR and GR ligands differed for different segments of the rat and human intestine and liver, and the changes did not parallel expression levels of the nuclear receptors.

Targeting 15d-Prostaglandin J2 to Hepatic Stellate Cells: Two Options Evaluated

PurposeDelivery of apoptosis-inducing compounds to hepatic stellate cells (HSC) may be an effective strategy to reverse liver fibrosis. The aim of this study was therefore to examine the selective targeting of the apoptosis-inducing drug 15-deoxy-Δ12,14-prostaglandin J2 (15dPGJ2) with two different HSC-carriers: human serum albumin modified with the sugar mannose-6-phosphate (M6PHSA) or albumin modified with PDGF-receptor recognizing peptides (pPBHSA).Methods and ResultsAfter chemical conjugation of 15dPGJ2 to the carriers, the constructs displayed pharmacological activity and specific receptor-mediated binding to HSC in vitro. Unlike 15dPGJ2-pPBHSA, the cellular binding of 15dPGJ2-M6PHSA was reduced by a scavenger receptor antagonist. In vivo, both conjugates rapidly accumulated in fibrotic livers. Intrahepatic analysis revealed that 15dPGJ2-M6PHSA mainly accumulated in HSC, and to a lesser extent in Kupffer cells. 15dPGJ2-pPBHSA also predominantly accumulated in HSC with additional uptake in hepatocytes. Assessment of target receptors in human cirrhotic livers revealed that M6P/IGFII-receptor expression was present in fibrotic areas. PDGF-β receptor expression was abundantly expressed on human fibroblasts.ConclusionsThese studies show that 15dPGJ2 coupled to either M6PHSA or pPBHSA is specifically taken up by HSC and is highly effective within these cells. Both carriers differ with respect to receptor specificity, leading to differences in intrahepatic distribution. Nevertheless, both carriers can be used to deliver the apoptosis-inducing drug 15dPGJ2 to HSC in vivo.

Pharmacokinetic and biodistribution profile of recombinant human interleukin-10 following intravenous administration in rats with extensive liver fibrosis

AbstractPurpose. Because interleukin-10 (IL-10) seems a promising new antifibrotic drug, we investigated the pharmacokinetic and biodistribution profile of this potent therapeutic cytokine in rats with extensive liver fibrosis (BDL-3). IL-10 receptor expression was also determined in relation to these aspects. Methods. To study the pharmacokinetic and biodistribution of IL-10, rhIL-10 was labeled with 125-iodine. Plasma samples of 125IrhIL-10 were obtained over a 30-min time period after administration of radiolabeled-cytokine to BDL-3 and normal rats. The tissue distribution was assessed 10 and 30 min after i.v. administration of 125IrhIL-10. IL-10 receptor expression was determined by immunohistochemical staining and RT-PCR technique. Results. The 125IrhIL-10 plasma curves followed two-compartment kinetics with a lower AUC in BDL-3 rats as compared to control. Plasma clearance and distribution volume at steady state were larger in BDL-3 rats. Tissue distribution analysis in normal rats showed that 125IrhIL-10 highly accumulated in kidneys. In BDL-3 rats, the liver content of 125IrhIL-10 increased by a factor of 2, whereas kidney accumulation did not significantly change. Immunohistochemical staining and RT-PCR analysis showed that IL-10 receptor was clearly upregulated in BDL-3 rat livers. Conclusions. In normal rats, 125IrhIL-10 rapidly disappears from the circulation, and the kidney is predominantly responsible for this. In BDL-3 rats, the liver largely contributes to this rapid plasma disappearance, probably due to an increase in IL-10 receptor expression. The extensive renal clearance of IL-10 in vivo may limit a clinical application of this cytokine for the treatment of chronic liver diseases. To optimize the therapeutic effects of IL-10 in hepatic diseases, alternative approaches that either decrease renal disposition or that further enhance hepatic delivery should be considered.

Effects of a New Bioactive Lipid-Based Drug Carrier on Cultured Hepatic Stellate Cells and Liver Fibrosis in Bile Duct-Ligated Rats

In the fibrotic liver, hepatic stellate cells (HSC) produce large amounts of collagen and secrete variety of mediators that promote development of fibrosis in this organ. Therefore, these cells are considered an attractive target for antifibrotic therapies. We incorporated the bioactive lipid dilinoleoylphosphatidylcholine (DLPC) into the membrane of liposomes, and then we evaluated its effect on hepatic stellate cell activation and liver fibrosis. To target DLPC-liposomes to HSC, human serum albumin modified with mannose 6-phosphate (M6P-HSA) was coupled to the surface of these liposomes. In vitro, the effects of the carrier were determined in primary cultures of HSC, Kupffer cells, and liver endothelial cells using real-time reverse transcription-polymerase chain reaction. In vivo DLPC-liposomes were tested in bile duct-ligated rats. Targeted M6P-HSA-DLPC-liposomes and DLPC-liposomes significantly reduced gene expression levels for collagen 1α1, α-smooth muscle actin (α-SMA), and transforming growth factor-β (TGF-β) in cultured HSC. In fibrotic livers, DLPC-liposomes decreased gene expression for TGF-β and collagen 1α1 as well as α-SMA and collagen protein expression. In contrast, M6P-HSA-DLPC-liposomes enhanced expression of profibrotic and proinflammatory genes in vivo. In cultured Kupffer and endothelial cells M6P-HSA liposomes influenced the expression of proinflammatory genes. Both types of liposomes increased hepatocyte glycogen content in fibrotic livers, indicating improved functionality of the hepatocytes. We conclude that DLPC-containing liposomes attenuate activation of cultured HSC. In fibrotic livers, M6P-HSA-mediated activation of Kupffer and endothelial cells probably counteracts this beneficial effect of DLPC-liposomes. Therefore, these bioactive drug carriers modulate the activity of all liver cells during liver fibrosis.

Chemical modification of interleukin-10 with mannose 6-phosphate groups yields a liver-selective cytokine

Cytokines are considered a promising immunotherapy for chronic diseases, because of their potency and fundamental roles in pathological processes. However, their therapeutic use is limited because of their poor pharmacokinetics and pleiotropic effects in various organs. These problems may be overcome by cell-specific delivery of the cytokine. This approach involves chemical modification of the protein with homing devices that recognize receptors on target cells. The cytokine interleukin-10 (IL10) may be valuable as a therapeutic cytokine for patients with liver cirrhosis. However, its rapid renal elimination and general immunosuppressive activities limit therapeutic use. We therefore aim to target this cytokine in the liver, in particular to fibrogenic hepatic stellate cells (HSCs). We show that IL10 is successfully modified with mannose 6-phosphate (M6P), which is a homing device for the mannose 6-phosphate/insulin-like growth factor II (M6P/IGFII) receptor expressed on activated HSCs. Chemical modification did not diminish IL10 efficacy with regard to in vitro anti-inflammatory (lipopolysaccharide-stimulated tumor necrosis factor α release) and antifibrotic (collagen deposition and degradation) activities. Biodistribution studies with radiolabeled M6P-IL10 and IL10 in rats with liver fibrosis showed that modification with M6P groups induced a shift in the distribution from the kidneys (IL10) to the liver (M6P-IL10). Hepatocellular binding of M6P-IL10 occurred via M6P/IGFII receptors and scavenger receptors, indicating that not only HSCs but also Kupffer and endothelial cells are target cells. IL10 did not bind to these receptors. We conclude that we prepared an active and liver-specific form of the cytokine IL10 that can be evaluated for its efficacy to treat liver diseases.

Pharmacokinetics and whole body distribution of elastase derived angiostatin(k1-3) in rats

In the current study, we determined short‐term pharmacokinetics and whole body distribution of elastase derived angiostatin [angiostatin(k1‐3)] in rats after i.v. injection of radiolabelled protein. Since in gamma‐camera studies, no tumor specific angiostatin(k1‐3) accumulation was observed, general pharmacokinetics were studied in tumor free rats. By one‐compartment model fitting of the data, Km 7.3 ± 1.7 μg • ml−1, Vmax 0.94 ± 0.19 μg • min−1, V1 10.9 ± 2.5 ml and intrinsic clearance (Vmax / Km) 0.128 ml • min−1 were calculated. Of the injected dose (I.D.) of angiostatin(k1‐3), 12.1 ± 2.1% per gram tissue was present in the kidneys 10 min after injection. Accumulation of angiostatin(k1‐3) was detectable in spleen, liver, lungs and heart 10 min after injection. Sixty minutes after injection, kidney associated angiostatin(k1‐3) had decreased, whereas in stomach and small intestines a small increase was seen. Immunohistochemical analysis demonstrated specific staining of interstitial cells of the kidney, liver Kupffer cells and endothelium of larger blood vessels of the lungs. Renal clearance of angiostatin(k1‐3) and/or fragments is a major route of elimination, whereas lack of accumulation of radioactivity in the faeces indicates little hepatic elimination or hepatic elimination followed by enterohepatic cycling of the proteins degradation products. Instant blood coagulation at the site of vascular activation and the occurrence of respiratory problems upon administration of higher doses of angiostatin(k1‐3) warrants further investigation of the proteins potential side effects. The data presented can be applied to study the relation between angiostatin(k1‐3) treatment regimens, blood concentration levels, anti‐tumor activity and harmful effects. Int. J. Cancer 91:1–7, 2001.