Further analysis of the prevention of atopic dermatitis by Toxoplasma gondii chronic infection

MATÍAS DAMIÁN PERRONE SIBILIA, MARÍA DE LOS ÁNGELES ALDIRICO, ARIADNA SOTO, MARIANO SERGIO PICCHIO, VANESA ROXANA SÁNCHEZ, NADIA ARCÓN, FLORENCIA MAGALÍ GIORGIO, VALENTINA MARTÍN, VAZULLI SILVIA, IGNACIO MARTÍN FENOY, ALEJANDRA GOLDMAN

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

 We previously showedthat T. gondii infection diminishes the susceptibility to developexperimental asthma. Afterwards we extended these results and showed that theparasite can also modulate an atopic dermatitis. Skin histopathology of miceinfected before allergic sensitization was similar to normal mice. This resultcorrelated with diminished IgE and IgG1 levels and reduced OVA specific Th1/Th2systemic cytokines. The aim of the present work was to further study themechanisms involved in this immunomodulatory effect. Adult BALB/c mice were orally infected with T. gondii cysts and, one month later, epicutaneously sensitizedwith OVA (TDA). Treatment was repeated twice, with a 2-week resting period between eachsensitization. Controls included non-infected mice sensitized with OVA (DA) orPBS (N) and infected mice treated with PBS (T). Local IL-4, IL-5 and IFN-g secretion was analysed in skin explants stimulated with OVA. T. gondii infection before allergic sensitization induced a local reduction inboth IL-4 and IL-5 (p≤0.05) and a trend to decrease in IFN-g levels compared to DA mice. The reduction in both Th1/Th2 cytokinessuggested that regulatory cells induced by the parasite may account for theimmunomodulatory effect. Hence, IL-10 and TGF-β supernatant levels were evaluated after ex vivo stimulation of splenocytes with OVA and changes in regulatory T cells CD4+Foxp3+ in spleen were measured by flowcytometry. No significant differences were observed in either TGF-β or CD4+Foxp3+T cells between all experimental groups. On the other hand, while a significantincrease in IL-10 levels was obtained for the DA group compared tonon-sensitized mice; infection with the parasite restored IL-10 levels in TDAgroup. Altogether, these results show thatT. gondii infection reduces both skin and systemic Th1/Th2 responses andsuggest that Tregs cells would not be involved in the immunomodulatory effect.