Background: The chemokine CCL5 is involved in the recruitment of immune cells and a subsequent activation of hepatic stellate cells (HSC) after liver injury. We here investigate whether inhibition of CCL5 oligomerization and glycosaminoglycan binding by a mutated CCL5 protein ((44)AANA(47)-CCL5) has the potential to ameliorate liver cell injury and fibrosis in vivo.
Methodology: Liver injury was induced in C57BL/6 mice by intraperitoneal injection of carbon tetrachloride (CCl(4)) in an acute and a chronic liver injury model. Simultaneously, mice received either (44)AANA(47)-CCL5 or vehicle. Liver cell necrosis and fibrosis was analyzed by histology, and measurement of serum transaminases and hydroxyproline. Intrahepatic mRNA expression of fibrosis and inflammation related genes were determined by quantitative RT-PCR and infiltration of immune cells was assessed by FACS analysis and immunocytochemistry. In vitro, HSC were stimulated with conditioned media of T-cell enriched splenocytes.
Principal findings: (44)AANA(47)-CCL5 treated mice displayed a significantly reduced degree of acute liver injury (liver cell necrosis, transaminases) and fibrosis (Sirus red positive area and hydroxyproline content) compared to vehicle treated mice. Ameliorated fibrosis by (44)AANA(47)-CCL5 was associated with a decreased expression of fibrosis related genes, decreased α-smoth muscle antigen (αSMA) and a reduction of infiltrating immune cells. In the acute model, (44)AANA(47)-CCL5 treated mice displayed a reduced immune cell infiltration and mRNA levels of TNF, IL-1 and CCL3 compared to vehicle treated mice. In vitro, conditioned medium of T-cell enriched splenocytes of (44)AANA(47)-CCL5 treated mice inhibited the chemotaxis and proliferation of HSC.
Conclusions: The results provide evidence that inhibition of oligomerization and glycosaminoglycan binding of the chemokine CCL5 is a new therapeutic strategy for the treatment of acute and chronic liver injuries and represents an alternative to chemokine receptor antagonism.