Hepatic Stellate Cell-mediated Increase in CCL5 Chemokine Expression after X-ray Irradiation Determined In Vitro and In Vivo.

Abstract

Radiation exposure causes hepatitis which induces hepatic steatosis and fibrosis. Although hepatic stellate cells (HSCs) have been considered potential pathological modulators for the development of hepatitis due to viral and microbial infections, their involvement in radiation-induced hepatitis is yet to be determined. This study aimed to clarify the relationship between radiation exposure and expressions of inflammatory cytokines and chemokines in HSCs in vitro and in vivo. HSCs were obtained from 1-week-old mice, known to be highly sensitive to radiation-induced hepatocellular carcinoma, using a newly established method combining liver perfusion, cell dissociation, and density gradient centrifugation, followed by magnetic negative selection of hematopoietic and endothelial cells with anti-CD45.2 and CD146 antibodies. The isolated HSCs were confirmed by the expression of desmin and glial fibrillary acidic protein (GFAP). We demonstrated that primary cultured HSCs, exposed to X-ray irradiation (0, 1.9, and 3.8 Gy) and cultured for 3 and 7 days, produced elevated levels of C-C motif chemokine ligand 5 (CCL5, also known as RANTES) inflammatory chemokine in a dose-dependent manner. An in vivo immunofluorescence method confirmed that increased CCL5 signals were observed in GFAP-positive HSCs in mouse livers 7 days after whole-body X-ray irradiation (1.9 and 3.8 Gy). Adequate expression of C-C motif chemokine receptor 5 (Ccr5), a receptor for CCL5, was also detected using real-time PCR in the liver of both irradiated and non-irradiated mice. Taken together, our data suggest that HSCs may drive hepatitis via CCL5/CCR5 axis in the liver under radiation-induced stress. Furthermore, this newly established experimental protocol can help evaluate the expression of other inflammatory cytokines in primary cultures of HSCs isolated from infant mice.