2 Impressively, fra-1tg mice developed hepatic inflammatory infiltrates mainly confined to the portal tracts (Fig. 1). Infiltration of cells in fra-1tg mice was evident at 6 weeks of age (mean inflammatory area 6.33 ± 1.14 mm2). At 18 weeks we observed bridging inflammatory infiltrates between neighboring portal tracts. However, at 23 weeks of age inflammatory infiltrates covered large areas of the liver of fra-1tg mice (mean inflammatory area fra-1tg 21.08 ± 5.47 mm2 versus wildtype 1.48 ± 0.71 mm2; P < 0.05; Fig. 1B). selleck products Even more interesting, we observed a ductular reaction in fra-1tg mice, assessed by staining for cytokeratine 19 (CK19) protein (Fig. 1A). Although we could

not detect major changes in the morphology of the larger bile ducts, the small bile ducts were increased in their numbers (Fig. 2). At 10 weeks of age the mean number of bile ducts

per portal tract was 1.38 ± 0.05 and 3.24 ± 0.22 for wildtype and fra-1tg mice (mean ± SEM; P < 0.05), respectively. This further increased up to 4.90 ± 1.44 bile ducts in fra-1tg mice at 23 weeks of age, whereas it remained unchanged in wildtype mice (1.32 ± DNA Synthesis inhibitor 0.07; P < 0.05). We next investigated the activity of ALP of fra-1tg and control mice (Fig. 2). ALP is an enzyme presented in bone and liver. As mentioned, fra-1tg mice develop osteosclerosis. For our study we investigated the activity of ALP directly in liver tissue. Increased MCE ALP activity was observed in fra-1tg mice at almost all timepoints, as seen at week 10 (wildtype 1.90 ± 0.74 versus fra-1tg 3.73 ± 1.48; P < 0.05) and 23 (wildtype 0.98 ± 0.14 versus fra-1tg 3.66 ± 1.53; P < 0.05). Thus, specific increase of intrahepatic ALP points to the presence of biliary and liver abnormalities. As we observed a strong infiltration of immune cells into the portal tracts, we next asked whether increased chemokine and cytokine expression

mediates this cell influx. We found a dramatic induction of distinct chemokines, such as CXCL5 (22-fold), CCL1, CCL5, and CCL7 (about 3.5-fold), CCL-8 (10-fold), and CCL20 (10-fold). We also observed an up-regulation of chemokine receptors such as CCR4 (9-fold) and CCR2 (4-fold) in the liver of fra-1tg mice (Supporting Fig. 1). To determine the composition of the inflammatory infiltrates, we first performed IHC on liver sections of wildtype and fra-1tg mice. The infiltrate in fra-1tg mice is mainly composed of neutrophils and cluster of differentiation 3 (CD3+) T-cells. B cells and macrophages are less frequently found at the site of liver inflammation. This pattern was consistent in fra-1tg mice at all ages investigated (week 6, 10, and 18). Thus, overexpression of fra-1 causes a progressive infiltration of the liver by cells belonging to the innate and adaptive immune system (Supporting Fig. 2).