ROLE OF REGULATORY T CELLS IN Yersinia enterocolitica-INDUCED REACTIVE ARTHRITIS IN TNFRP55-/- MICE

CARGNELUTTI E; ANZULOVICH AC; DI GENARO MS

Potrero de los Funes, San Luis

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Regulatory T (Treg) cells suppress physiological and pathological immune responses. We have demonstrated that TNFRp55-/- (KO) mice develop a severe and chronic reactive arthritis (ReA) after Yersinia enterocolitica (Ye) infection. Also, KO mice show significant differences of IL-10 levels at regional lymph nodes (RLN) to the joint. The aim of this work was to investigate whether Treg cells play a role in our ReA model. We determined the frequency of Treg cells and the Foxp3 mRNA expression. C57BL/6 wild-type (WT) and KO mice were infected with Ye O:3. Seven, 14 and 21 days after infection, CD4+CD25+Foxp3+ cells from RLN were analyzed by flow cytometry; Foxp3 mRNA expression in RLN CD4+T cells was determined by RT-qPCR. We found that on day 14 (arthritis onset), KO mice showed significantly lower frequency of CD4+CD25+Foxp3+ cells, compared to WT mice (3.7%±0.13; 5.1% ±0.46, respectively; p<0.05), this result was in line with relative expression of Foxp3 mRNA (0.78±0.03; 1.2±0.03, respectively; p<0.005). In contrast, despite O mice showed arthritis on day 21 (chronic phase), a significantly higher frequency of Treg cells was found in these mice compared to WT (4.4%±0.27; 3.4%±0.29, respectively; p<0.05). We concluded that at local site, TNFRp55 signaling influences the Foxp3 expression and Treg frequency. Moreover, Treg decrease is involved in ReA onset in TNFRp55-/- mice.