Background. Crry is a regulator of complement that inhibits the C3 convertase of both the classical and alternative pathways in rodents. In order to examine a potential therapeutic effect of recombinant soluble Crry in immune-mediated renal injury, we employed an adenovirus-based genetransfer approach. Methods. We constructed an adenovirus expressing soluble Crry with a c-myc tag at the C-terminus (AdsCrry). To evaluate the expression of the sCrry protein in vitro, western blotting, an enzyme-linked immunosorbent assay (ELISA), and a complement-dependent hemolysis assay were performed. In vivo mRNA expression was evaluated by reverse transcriptase-polymerase chain reaction (RTPCR). We assessed effects of AdsCrry on histological damage in a complement-dependent mesangioproliferative glomerulonephritis model in rat (anti-Thy-1 nephritis). Results. Western blotting analysis of culture media of cells transfected with AdsCrry demonstrated successful expression of the transgene. This was confirmed by quantitative analysis by ELISA. In vitro hemolysis assays showed that the recombinant protein was active and inhibited complement-dependent cell lysis in a dose-dependent manner. Our PCR analysis showed that systemic administration of AdsCrry leads to successful expression of the transgene in the liver. Animals of the glomerulonephritis model treated with AdsCrry showed less microaneurysm formation at day 7. Conclusions. The adenovirus vector AdsCrry produced functionally active soluble Crry with a c-myc tag. Systemic administration of this vector resulted in expression of the transgene in the liver, and analysis of the animals suggested some promise for a therapeutic approach by in vivo gene transfer of a recombinant complement regulatory protein in immune-mediated renal disease.
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