Z Gastroenterol 2012; 50 - P1_35
DOI: 10.1055/s-0031-1295766

Mapping differential susceptibility of primary hepatocytes to TGF-β in the BXD population of recombinant inbred mouse lines

R Müllenbach 1, R Hall 2, S Dooley 3, F Lammert 2
  • 1Klinik für Innere Medizin II, Homburg
  • 2Universitätsklinikum des Saarlandes, Homburg, Deutschland
  • 3II. Med. Klinik; Medizinische Fakultät Mannheim der Universität Heidelberg, Mannheim

Aims: TGF-β is the central pro-fibrogenic cytokine in liver, and exerts autocrine effects on neighbouring hepatocytes as well as attracting and activating myofibroblasts. We suspect that differential sensitivity to autocrine TGF-β signalling might be a factor underlying the susceptibility to developing fibrosis in various aetiologies.

Hypothesis: Genetic variants causing different hepatocellular sensitivity to TGF-β induced damage might modulate susceptibility to fibrogenesis in response to chronic hepatocellular damage.

Methods: We cultured primary hepatocytes from two different inbred laboratory mouse strains, C57BL/6J (B6) and DBA/2J (D2) as well as 19 BXD inbred lines, which represent recombinant inbred F2 offspring generated from these strains. The mosaic genomic architecture of the BXD reference population has been determined using >14,000 polymorphic markers covering the entire genome. Cells were subjected to TGF-β stimulation (5ng/ml) for 48 hours and hepatocellular damage assayed by measuring lactate dehydrogenase (LDH) in the supernatant as a percentage of total LDH (supernatant + cells). Median LDH increase after 48 hours of TGF-β treatment compared to untreated cells was used as trait for interval mapping.

Results: Genome-wide linkage analysis by interval mapping identified a genomic locus on mouse chromosome 11 that co-segregates with the phenotype (LOD=3.8). Array-based expression analysis of 160 genes from the 10 megabase (Mb) candidate region revealed TGF-β regulated genes, among them 5 CCL genes from a cluster of 11 chemokine ligands (CC-motif) at position 82–84 Mb.

Conclusions: Genome-wide mapping of hepatocellular damage in vitro in response to TGF-β treatment identified a single genomic region that is significantly associated with the phenotype "differential hepatocellular damage". Further functional candidate gene analysis will identify genes that modulate the phenotype and thus might contribute to inherited fibrosis susceptibility.