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Interferona2a Treatment in the IRBP Derived-peptide Induced EAU
1Stübiger N., 2Crane I. J., 3Kötter I., 2Lamont G. R., 4Zoeller M., 5Guenthert U., 6Forrester J. V., 1Zierhut M., 1Stiemer R. H.,
1Eberhard-Karls-Universität Tübingen, Universitäts-Augenklinik, Abt. I (Tübingen)
2Department of Ophthalmology, University Aberdeen (Aberdeen)
3Eberhard-Karls-Universität Tübingen, Medizinische Universitätsklinik, Abt. II (Tübingen)
4German Cancer Research Center (Heidelberg)
5University of Basel, Institute of Medical Microbiology (Basel)
6Department of Ophthalmology, University Hospitals (Aberdeen)
Purpose: Interferons (IFN) type I were instituted in the treatment for Behçet´s Disease (BD) in 1986. The efficacy of such interferons in ocular BD, even when it was refractory to other treatments, is very promising. However, the mechanism of action is still unclear. Therefore we studied for the first time the expression of CD44 isoforms and the infiltrating cells in the EAU (experimental autoimmune uveitis) peptide-model during IFN-a treatment. CD44 isoforms constitute a family of cellular adhesion molecules exhibiting different biological functions including influence on immunpathology.
Methods: B10.RIII mice were immunized subcutaneously with 100µg of the human IRBP-derived peptide aa 161-180. IFN-a dosage was adapted from our scheme in human patients. Twelve of 24 animals received IFN-a daily, injected subcutaneously (3x106-6x106 IU) until sacrifice. Histological and immunohistochemical analyses of the eyes were carried out on animals sacrificed on day 10 and 18 post-immunization (n=6 for each treatment and time point). The applied mAbs were directed against CD45, CD3, CD4, CD8 and CD44 isoforms, i.e. standard CD44 (CD44s), splicing variants v3, v6, v7 and v10. The staining was performed on frozen sections using the alkaline-phosphatase method. Control staining was achieved on murine tongue sections.
Results: Histological analysis at day 10 showed 4 of 6 control mice to have severe EAU (grading >3) compared to only 2 of 6 IFNa-treated mice. At day 18 there was histologically little difference between control and IFN-a treated mice. The infiltrating cells were CD3+ and CD45+. From the CD44 isoforms only CD44s expression was detected in the retina exhibiting no difference between IFN-a treatment and control eyes.
Conclusions: The distinct expression of CD44s in the EAU-modell may be important for the regulation of EAU induction by CD45+ and CD3+ cells. Additionally our results imply the necessity to increase the IFN-a dosage in the EAU-model.
This study was supported by the DFG-grant ZI 350/13.