Project description:Autosomal recessive polycystic kidney disease is a severe, monogenetically inherited kidney and liver disease and PCK rats carrying the orthologous mutant gene serve as a model of human disease. We combined selective MALDI imaging of sulfated kidney lipids and Fisher discriminant analysis of imaging data sets for identification of candidate lipid markers of progressive disease in PCK rats. Our study highlights strong increases in lower mass lipids as main classifiers of cystic disease. Structure determination by high resolution mass spectrometry identifies these altered lipids as taurine-conjugated bile acids. Beside increased levels of serum-cholesterol these sulfated lipids are selectively elevated in the PCK rat model but not in models of related hepatorenal fibrocystic diseases suggesting that they be molecular markers of the disease. Genome-scale gene expression profiling of PCK and SD livers as control was performed to attempt elucidation of some of the underlying mechanisms leading to increases of cholesterol and taurine-conjugated bile acids in the PCK rat. Several pathways were found to be changed in cystic livers with up regulation or down regulation of important gene sets. Enhanced expression of steroid biosynthesis genes might result in the observed increased levels of cholesterol. In contrast, primary bile acid biosynthesis was found to be down regulated in diseased livers. These findings might be explained by compensatory mechanisms of liver metabolism to reduce toxic levels of accumulated bile acids. Snap-frozen liver tissue of 10 week old rats were subjected for RNA extraction and hybridization on Affymetrix microarrays to perform genome-scale gene expression profiling of n = 6 diseased PCK and n = 6 Sprague Dawley rat livers as control.
Project description:The Th2 cytokine IL-13 has been described to be involved in biliary epithelial injury and liver fibrosis in patients as well as in animal models. IL-13 was found to reduce tight junction-associated barrier function of bile ducts, to promote cholangiocyte hyperplasia, and thus causing biliary epithelial injury. We generated Abcb4-/-- and IL-13-/- double-knockout mice on fibrosis susceptible genetic background BALB/c. Molecular and cellular mechanisms of hepatic and ileal pathology were investigated by mRNA microarray. Depletion of IL-13 in Abcb4-/--mice resulted in a tenfold decrease of total serum bile acid concentrations at the age of 8 weeks and lead to a recovery of intrahepatic bile duct integrity. The decrease of serum bile acid in 8 week old mice went along with relative enhancement of bile acid excretion and normalization of the composition of fecal bile excretion, correction of fecal microbiome, and improved ileal integrity. Liver integrity, measured by serum ALT, was ameliorated in younger mice and strongly correlated with the concentration of serum bile acids. 52 weeks old Abcb4-/-IL-13-/--mice exhibited significantly reduced hepatic fibrosis.
Project description:Arrays comparing Pseudomonas aeruginosa growth in a defined synthetic cystic fibrosis sputum medium with and without aromatic amino acids. Additional arrays comparing wild-type Pseudomonas aeruginosa and phhR mutant P. aeruginosa in defined synthetic cystic fibrosis sputum medium.
Project description:Autosomal recessive polycystic kidney disease is a severe, monogenetically inherited kidney and liver disease and PCK rats carrying the orthologous mutant gene serve as a model of human disease. We combined selective MALDI imaging of sulfated kidney lipids and Fisher discriminant analysis of imaging data sets for identification of candidate lipid markers of progressive disease in PCK rats. Our study highlights strong increases in lower mass lipids as main classifiers of cystic disease. Structure determination by high resolution mass spectrometry identifies these altered lipids as taurine-conjugated bile acids. Beside increased levels of serum-cholesterol these sulfated lipids are selectively elevated in the PCK rat model but not in models of related hepatorenal fibrocystic diseases suggesting that they be molecular markers of the disease. Genome-scale gene expression profiling of PCK and SD livers as control was performed to attempt elucidation of some of the underlying mechanisms leading to increases of cholesterol and taurine-conjugated bile acids in the PCK rat. Several pathways were found to be changed in cystic livers with up regulation or down regulation of important gene sets. Enhanced expression of steroid biosynthesis genes might result in the observed increased levels of cholesterol. In contrast, primary bile acid biosynthesis was found to be down regulated in diseased livers. These findings might be explained by compensatory mechanisms of liver metabolism to reduce toxic levels of accumulated bile acids.
Project description:The multidrug resistance gene 2 (Mdr2 or Abcb4) encodes a P-glycoprotein (Pgp) - a phospholipid flippase - that is the murine orthologue of the MDR3 gene in humans. The MDR2 protein is principally expressed in the bile canalicular membrane of the liver. A homozygous disruption of Abcb4 causes absence of phospholipids from bile. This phospholipid deficiency results in liver injury. The Balb-Abcb4-/- mouse strain has been generated by introgressing the Abcb4 knockout from the fibrosis-resistant FVB/NJ (FVB.129P2-Abcb4tm1Bor/J) strain into the susceptible BALB/cJ background, by backcrossing FVB- Abcb4-/- mice in to fibrosis-susceptible BALB/cJ mice for 10 generations. cDNA expression profiling of mRNA from liver of four single male mutant mice against a pool of RNA from four wild type controls (n=8). For each mutant animal two technical replicates were performed including a dye swap experiment.
Project description:Many patients with Cystic Fibrosis suffer from Gastroeosphgeal Refux Disease (GERD). This disease may lead to the aspiration of bile into the lungs. We invesigated the effect of bile on the CF lung pathogen P. aeruginosa. We analysed gene expression profiles, comparing bile treated and untreated cells to identified distinct classes of up/down-regulated genes.
Project description:Many patients with Cystic Fibrosis suffer from Gastroeosphgeal Refux Disease (GERD). This disease may lead to the aspiration of bile into the lungs. We invesigated the effect of bile on the CF lung pathogen P. aeruginosa. We analysed gene expression profiles, comparing bile treated and untreated cells to identified distinct classes of up/down-regulated genes. P. aeruginosa PAO1 was grown to log stage for RNA extraction and hybridization on Affymetrix microarrays. We conducted three biological replicates as to increase the resolution of expression profiles.
Project description:DICER1 syndrome is a tumor predisposition syndrome caused by familial genetic mutations in DICER1. Pathogenic variants of DICER1 have been discovered in many rare cancers, including cystic liver tumors. However, the molecular mechanisms underlying liver lesions induced by these variants remain unclear. In the present study, we sought to gain a better understanding of the pathogenesis of these variants by generating a mouse model of liver-specific DICER1 syndrome. The mouse model developed bile duct hyperplasia with fibrosis, similar to congenital hepatic fibrosis, as well as cystic liver tumors resembling those in Caroli's syndrome, intrahepatic cholangiocarcinoma, and hepatocellular carcinoma. Interestingly, the mouse model of DICER1 syndrome showed abnormal formation of primary cilia in the bile duct epithelium, which is a known cause of bile duct hyperplasia and cyst formation. These results indicated that DICER1 mutations contribute to cystic liver tumors by inducing defective primary cilia. The mouse model generated in this study will be useful for elucidating the potential mechanisms of tumorigenesis induced by DICER1 variants and for obtaining a comprehensive understanding of DICER1 syndrome.