The selective induction of apoptosis in HSC by the targeted thymidine kinase/Ganciclovir system

• Published in: Zeitschrift für Gastroenterologie
• Main Authors: Kovalenko, E, Borkham-Kamphorst, E, Bomble, M, Gressner, AM, Weiskirchen, R
• Format: Conference Proceeding
• Language: English; German
• Published: 23.01.2008
• Subjects: gene therapy; tissue inhibitor of metalloproteinases-1; adenoviruses; antifibrotic therapy; transcriptional targeting
• ISSN: 0044-2771; 1439-7803
• DOI: 10.1055/s-2008-1037480

Background/Aims: Liver fibrogenesis is the consequence of a dysbalance of synthesis and degradation of extracellular matrix components. During hepatic fibrogenesis, hepatic stellate cells (HSC) are the major producer of these constituents. Therefore, HSC are in the focus of antifibrotic therapies. A previous report from us have demonstrated that the thymidine kinase/Ganciclovir system directed under transcriptional control of the tissue inhibitor of metalloproteinases–1 (TIMP–1) promoter is suitable to induce apoptosis in culture-activated HSC [1]. We now extended our studies and tested if a selective induction of HSC apoptosis with this system is achievable in vivo . Methods: Rats were treated with two injection of CCl 4 (1ml/kg bodyweight). Subsequently, animals received a recombinant adenovirus (Ad-TIMP-tk) that expressed the thymidine kinase under the TIMP–1 promoter. Selective apoptosis was induced by administration of Ganciclovir. The functionality and selective expression of the adenoviral device was tested by immunohistochemistry using an antibody directed against thymidine kinase. Furthermore, apoptosis was determined by TUNEL staining. Endogenous expression of TIMP–1 in animals that received CCl 4 for up to twelve weeks was analysed by Western blot, immunohistochemistry, RT-PCR, and qPCR (Taqman). Results: Endogenous TIMP–1 expression was highest one week after beginning of CCl 4 administration. The immunohistochemistry of liver slices revealed that the recombinant virus Ad-TIMP-tk was expressed and induced apoptosis in activated HSC. Conclusions: We found that the expression of the thymidine kinase/Ganciclovir system under control of a selective promoter that becomes upregulated during transdifferentiation is suitable to induce HSC apoptosis in an in vivo model of hepatic fibrogenesis. Future studies are aimed to analyse if the observed apoptosis decrease the expression of extracellular matrix components. Literatur: [1] Janoschek N, van de Leur E, Gressner AM, Weiskirchen R. (2004) Biochem Biophys Res Commun. 316, 1107-1115.