Effects of blocking chemokine receptor CCR1 with BX471 in two models of fibrosis prevention and rescue in mice

Background: The induction, progression and resolution of liver fibrosis are influenced by multiple chemokines. The inhibition of CCR1 signalling by a specific non-peptide inhibitor (BX471) reduces kidney fibrosis after unilateral ureteral obstruction via suppression of leukocyte recruitment in mice. However, it remains unclear whether selective CCR1 inhibition also affects hepatic fibrogenesis. Therefore we aimed to study the effect of this intervention on liver fibrosis in prevention (CCl4 administration) and rescue (ABCB4-deficient mice) mouse models. Methods: In the prevention model, hepatic fibrosis was induced by repeated injections of CCl4. Additionally, the verum group was treated with subcutaneous injections of BX471, while controls received vehicle only. ABCB4 deficient mice (on the BALB/c-background) with sclerosing cholangitis and biliary fibrosis received BX471 or vehicle, respectively (rescue model). Liver histopathology was assessed after Sirius red staining of collagen, and hepatic collagen contents were measured. In addition, we performed gene expression analyses of fibrosis-related genes. Results: BX471 injections were tolerated moderately well by all mice, and all mice developed hepatic fibrosis. Significant differences were neither observed in serum aminotransferase activities after 6 weeks of treatment between the two groups in the prevention nor in the rescue model. Interestingly, hepatic collagen contents were significantly higher in mice treated with BX471 in the prevention model as compared to controls but histological stages of liver sections did not differ. Of note, we observed only moderate effects on liver fibrosis in the ABCB4 knock-out model. Conclusions: Our data indicate that BX471 treatment did neither affect serum and tissue markers of liver injury and fibrosis in the CCl4 model and only moderately in the Abcb4-/- model of biliary fibrosis. The animal models indicate that treatment with BX471 alone is unlikely to exert major beneficial effects in chronic liver disease