Evaluation der immunologischen und antineoplastischen Eigenschaften von immunstimulativer DNA (CpG-ODN) beim Transitionalzellkarzinom. Untersuchungen zur Zytokinexpression am orthotopen, murinen Harnblasenkarzinommodell

Intravesical BCG installation is established and efficient in the prophylaxis of recurrent intermediate and high-risk transitional cell carcinoma (TCC) but its mode of action has not yet been elucidated. Diverse studies could show that this effect is based on the structure of the bacterial DNA: Small CpG-oligonucleotides (CpG-ODN) containing a central unmethylated CpG motif are able to mimic the immunostimulatory activity. Recent work proved the efficacy of synthetic CpG-ODN as an inducer for a strong Th1-response and there is evidence for a direct and/or adjuvant antineoplastic effect. Purpose of this work was to examine the effects of cytokine expression in the murine bladder and local lymhnodes after intravesical instillation of CpG-ODN in an orthotopic bladder cancer model. An orthotopic C57/Bl6 murine bladder cancer model was established in female C57/BL6 mice using the corresponding syngenic MB49 TCC cell line. Mice were divided in three groups (n = 12). The first group (early-onset) recived CpG-ODN directly after instillation of MB49 TCC cell line, the second group (late-onset) were treated with CpG-ODN five days after tumorcell instillation where as the last group served as control-group and recived no treatment. Mices were sacrificed 13 days after tumorcell instillation and urinary bladder and local lymphnodes were used for the further examinations. We evaluated the expression of Th1-based cytokines (IL 12, IFNγ, and TGFβ) and Th2-based cytokines (TNF-α, IL-4 and IL 10) in these two tissues using quantative real-time-PCR. Repeated intravesical instillation of CpG-ODN in orthotopic murine tumor bearing urinary bladders results in significant upregulation of both Th1- and Th2- cytokines. Furthermore these effects are detectable in local lymphnodes. CpG-ODN treated animals demonstrate an upregulation of Th2-cytokines, which is even stronger in the early-onset-group than in the late-onset-group. This fact is probably due to the schedule of the CpG-treatment. Early or late onset of CpG-ODN instillation after inoculation of tumorcells seems to have no greater effects. Examinations of local lymphnodes present similar results. Although CpG-ODN is only locally instillated in urinary bladder the cytokine regulation in lymphnodes follow the same tendence. These results suggest that CpG-ODN has not only local, but also systemic immunological effects. CpG-ODN seem to have promising antineoplastic potential. They exert a pronounced immunological response in the cancerous murine urinary bladder and in local lymphnodes. The mechanism of action appears to be mediated immunologically. In the orthotopic tumor model up-regulation of Th1- and Th2 -cytokines parallels the clinical effects recently described. Investigations in human bladder cancer will have to determine the therapeutic potential of CpG-ODN in this disease.