Newcastle disease virus represses the activation of human hepatic stellate cells and reverses the development of hepatic fibrosis in mice
ABSTRACT
BACKGROUND/AIMS: Activated hepatic stellate cells (HSCs) are the crucial factor responsible for liver fibrosis and involved in development of hepatocellular carcinoma (HCC) by interaction with tumour cells. Newcastle disease virus (NDV) has the oncolytic characteristics of intrinsically selective replication in neoplasia cells and transformed cells. But, NDV replication in HSCs and effects on hepatic fibrosis have not been reported.
METHODS: We detected the effect of conditioned medium (CM) from human HCC cells on the activation of human HSC line, LX-2 by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and reverse transcriptase-polymerase chain reaction (RT-PCR). The replication of NDV was evaluated in LX-2 cells and primary-cultured mouse HSCs by flow cytometry or by a fluorescence microscope. Indices for hepatic fibrosis were determined in HSCs and a hepatic fibrosis mouse model by gelatin zymography, RT-PCR, Western blot and Sirius red staining after NDV infection. Colocalization of NDV virions and alpha-smooth muscle actin (alpha-SMA) were detected by double immunofluorescence staining. Detection of apoptosis was carried out in liver tissues of NDV-treated mice by the TdT-mediated dUTP nick-end labelling assay.
RESULTS: Tumour-CM and transforming growth factor-beta1 (TGF-beta1) could promote the proliferation and activation of LX-2 cells, indicated by the enhanced expression of alpha-SMA, collagen I, tissue inhibitor of metalloproteinase (TIMP)-1 and TGF-beta1. Activated HSCs facilitated the replication of NDV, thereby repressing the secretion of MMP, the expression of these indices for hepatic fibrosis and the expression of alpha-SMA and collagen fibrils in hepatic fibrosis of the mouse induced by carbon tetrachloride.
CONCLUSIONS: HCC cells promote the activation of HSCs and NDV attenuates the activation and represses the hepatic fibrosis by selective replication in activated HSCs.