Immunologische Wirkung einer Therapie mit immunstimulativer DNA (CpG-ODN) im subkutanen, murinen Harnblasenkarzinommodell unter Verwendung einer Toll-like-Rezeptor-9-Knock-out-Maus

Bladder cancer is the second most common malignant urological tumor disease. For years, the intravesical instillation of BCG has been a standard therapy, especially for high-risk urothelial carcinoma. Due to the high side effect profile, this therapy is often discontinued by patients. Investigations into the mechanism of action of BCG have revealed CG-rich DNA sequences (CpG-ODN) as the responsible immunomodulatory components. In the murine model, the stimulation of certain cytokines and mediators in the sense of a TH-1 immune response after binding to the TLR-9 receptor was detected. In this dissertation, the cytokine milieu in C57BL/6 and TLR-9(-/-)knock-out mice was compared in tumor material using the example of bladder carcinoma under therapy with CpG-ODN. We established a subcutaneous model in which all animals developed a palpable tumor by injecting 1 million tumor cells (MB49) each in the area of both flanks. A total of 38 animals were examined (20 animals of species C57BL/6 and 18 TLR-9(-/-)C57BL/6 mice). Half of the animals each received CpG-ODN into the right-sided infiltrated tumor cell on the day of tumor cell instillation. After sacrifice of the animals and removal of the subcutaneous tumor material, the cytokine expression was investigated by real-time PCR. Clinically, the treated animals showed a significantly smaller tumor size, with the tumors of the knock-out mice being larger overall compared to the C57BL/6 animals. The C57BL/6 mice treated with CpG-ODN showed a mainly TH-2-weighted immune response, whereby IL-12 - as the main representative of the TH-1-weighted immune response - was also increasingly expressed. We attribute these results to the very early start of therapy with CpG-ODN as well as the relatively early sacrifice of the animals on the 13th day of the trial. In the treatment group of TLR-9(-/-)knock-out mice, a pronounced multiple expression of cytokines of both the TH-1 and TH-2 response was observed. These results suggest that not only the signalling cascade via the TLR-9 receptor, but also other immunostimulatory mechanisms are at work. Comparing the respective tumours (right and left) of the animals examined, a systemic effect of CpG-ODN can be assumed, since immunomodulatory mechanisms with an increase in specific cytokines were also found on the non-treated side. The therapeutic use of CpG-ODN will not only gain importance in the field of oncology. For this purpose, it is desirable to understand the mechanisms of action even more precisely through further research. In this way, it may be possible to establish this promising treatment principle for further indications and use it effectively in medical practice.