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 CCl4 (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 CCl4 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 CCl4 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.
adenoviruses - antifibrotic therapy - gene therapy - tissue inhibitor of metalloproteinases-1
- transcriptional targeting
