REDUCTION OF PEYER´S PATCHES IN ACUTE TRYPANOSOMA CRUZI INFECTION

GARECA JULIO C ; GAZZONI YAMILA; BRUNOTTO VALENTINA; AMEZCUA VESELY M CAROLINA; ALMADA LAURA; ACOSTA-RODRÍGUEZ EVA V; MONTES CAROLINA L; GRUPPI ADRIANA

San Luis

Congreso; LXXI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA; 2023

Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by Trypanosoma cruzi. The acute phase of experimental T. cruziinfection results in splenomegaly and expansion in lymph nodes, polyclonal B cell activation, hypergammaglobulinemia and unspecific antibodies (Abs) in sera. Parasite-specific Abs are also present in infected mice and have been described as an important mechanism to parasitemia control. The contribution of the different B cells subsets to this infection are diverse and not completely understood.In this work, we evaluated B cell response in gut during T. cruzi infection since intestine is the tissue with the highest number of B cells. For that, 8-12 weeks old C57BL/6 mice were intraperitoneally injected with 2500 trypomastigotes of T. cruzi Tulahuén strain or with PBS (control mice). At different days post infection (dpi) small intestine, Peyer´s patches (PP) and mesenteric lymph node (MLN) were obtained. By macroscope evaluation we observed a decrease in the size of PP and MLN at the time of highest parasitemia (18 dpi). PP decrease was transient since at 82 dpi they recovered the normal size. By immunofluorescence (IF), at 18 dpi, we observed a decrease in B and CD4+ and CD8+T cells in PP but infiltrating T cells in the muscle layer of small intestine. Accordingly, by FACS, we observed that PP had a marked decrease in the number of T and B cells, being the greatest reduction in B cell population. Moreover, TUNEL assay performed on PP and MLN at different dpi showed negative result in PP obtained at 10 dpi, while positive signal, indicating apoptosis, was observed inside the follicles and medullary zone of the MLN. In MLN from infected mice, CD169+ metallophilic macrophages disappeared from the subcapsular sinus and clustered around the B cell follicles, and follicles were highly disorganized containing high frequency of CD4+ T cells. The findings suggest that T. cruzi infection impacts on gut immune response, leading to changes in B and T cell populations of PP and MLN. In summary, absence of apoptosis and the reduction in lymphocytes number indicate that T. cruziinfection is affecting the cellular traffic in PP. In addition, the high tissue disorganization of MLN from infected mice suggest that T. cruzi affects the generation of productive gut immune response.