Inflamed glomeruli-specific gene activation that uses recombinant adenovirus with the Cre/loxP system

The authors previously reported that bone marrow-derived CD11b(+)CD18(+) ce lls could be used as a vehicle to deliver foreign genes into inflamed glome ruli and that this vehicle cell (v-cell) could retard the progression of ne phritis by delivering anti-inflammatory molecules. As a next step, the auth ors tried to establish a switching system by which v-cells are activated on ly at the inflamed glomeruli. A recombinant adenovirus (Ad) that expressed Cre recombinase under the control of the interleukin-1 beta (IL-1 beta) pro moter (AxIL-1pr/Cre) was constructed and transfected into v-cells. After co nfirming that AxIL-1pr/Cre expresses Cre by lipopolysaccharide (LPS) treatm ent, AxIL-1pr/Cre was infected together with another Ad bearing a switching reporter unit in which the LacZ gene is activated under the control of the CAG promoter by the Cre-mediated excisional deletion of interposed stuffer DNA. Only a negligible number of double-infected (Cre/loxPCAG) cells expre ssed LacZ. This number, however, was significantly increased by LPS, which suggests that LPS-induced Cre effectively deletes the stuffer DNA, which al lows for a complete CAG promoter. DBA/2j mice were then transplanted with C re/loxPCAG cells via a tail vein and treated with anti-glomerular basement membrane (GBM) serum. To trace the transplanted cells, marker v-cells, infe cted with AxCANLacZ to constitutively express the LacZ gene, were also used . Although transplanted cells expressing LacZ collected in the spleen indep endent of anti-GBM treatment, they did not express the LacZ gene in the mic e transplanted with Cre/loxPCAG cells. On the other hand, transplanted cell s were recruited in the glomeruli and expressed the LacZ gene upon anti-GBM treatment. These results suggested that only the v-cells recruited in the glomeruli could be switched on and activate Foreign genes.