3-5 However, gliotoxin
also has broad actions in vivo and in culture, targeting not only HSCs, but also immune and endothelial cells (ECs) and hepatocytes.5, 6 An alternative strategy is to ectopically express the herpes simplex virus/thymidine kinase (HSV-Tk) gene in target cells, Tipifarnib cost which renders them susceptible to killing by the antiviral agent, ganciclovir (GCV), but only when the cells are proliferating. This possibility was first reported as an anticancer approach7 and further refined8 in murine sarcoma and lymphoma cells, provoking both apoptotic and nonapoptotic cell death.9, 10 The approach has also been reported in liver injury models and in cultured HSCs,11 but has not been used to deplete HSCs in vivo.12 We have exploited this strategy by using mice expressing the HSV-Tk gene driven by the GFAP promoter, which is a marker of HSCs in rodent liver.1 The approach has uncovered a novel, unexpected role for HSCs in amplifying acute liver injury (ALI). 4-HNE, 4-hydroxy-2-nonenal;
Abs, antibodies; AA, allyl alcohol; ALI, acute liver injury; ALT, alanine aminotransferase; Palbociclib mw α-SMA, alpha smooth muscle actin; AST, aspartate aminotransferase; BDL, bile duct ligation; CXCR4, C-X-C chemokine receptor type 4; DCs, dendritic cells; ECs, endothelial cells; GCV, ganciclovir; GFAP, glial fibrillary acidic protein; H&E, hematoxylin and eosin; HSC, Bcl-w hepatic stellate cell; HSV-Tk, herpes simplex virus/thymidine kinase; IF, immunofluorescence; IFN-γ, interferon-gamma; IHC, immunohistochemistry; IL, interleukin; IP, intraperitoneally; JNK, c-Jun N-terminal kinase; mRNA, messenger RNA; NK, natural killer; PARP, poly(ADP-ribose) polymerase; PCR, polymerase chain reaction; PDGFR, platelet-derived growth factor receptor; Tg, transgenic; Tregs, T-regulatory cells; TUNEL, terminal deoxynucleotidyl
transferase dUTP nick end labeling; WT, wild type. Further information is provided in the Suppprting Materials and Methods. Seven- to eight-week-old male Gfap-Tk mice (B6.Cg-Tg(Gfap-Tk)7.1Mvs/J; Jackson Laboratory, Bar Harbor, ME) were used for in vivo experiments in accord with institutional animal care and use committee protocols. Transgenic (Tg) mice express the HSV-Tk gene driven by the mouse glial fibrillary acidic protein (GFAP) promoter. HSV-Tk-negative littermates served as controls (wild type; WT). All treatment schemes are depicted in Supporting Fig. 1. CCl4 and allyl alcohol (AA) were purchased from Sigma-Aldrich (St. Louis, MO). Mice were treated with CCl4 (0.25 μL/g, intraperitoneally [IP], diluted in 50 μL of corn oil, on days 1, 4, 7, and 10) and AA (0.0125 μL/g, IP, diluted in 100 μL of 0.9% NaCl, on days 2, 5, and to induce ALI and optimize HSC proliferation while evoking only modest liver damage.