Tumor necrosis factor alpha (TNF) and TNF-receptor 1 (TNF-R1) are involved in thymocyte migration during Trypanosoma cruzi infection

PEREZ A; SILVA-BARBOSA SD; BERBERT L; REVELLI S; BOTTASSO O; SAVINO W

Buzios

Congreso; XIII International Congress of Protistology, XXV Annual Meeting of the Brazilian Society of Protozoology and XXXVI Annual Meeting on Basic Research in Chagas Disease; 2009

Brazilian Society of Protozoology

TUMOR NECROSIS FACTOR ALPHA (TNF-a) and TNF-RECEPTOR 1 (TNF-R1) ARE INVOLVED IN THYMOCYTE MIGRATION DURING TRYPANOSOMA CRUZI INFECTION Pérez A.R.1*, Silva-Barbosa S.D.2, Berbert L.R.2, Revelli S.1, Bottasso O.1, Savino W.2. 1Instituto  de Inmunología, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Argentina; 2Laboratory of Thymus Research, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. Although TNF-a is protective during Trypanosoma cruzi infection, its overproduction could be detrimental to the host and might contribute to the pathophysiology of the disease. During murine acute infection, we detected an increased exit of immature CD4+CD8+ double positive (DP) T-cells linked to a massive loss of DP cells by apoptosis, in parallel to increased intrathymic contents of tumor necrosis factor alpha (TNF-a) and extracellular matrix proteins (ECM), including fibronectin (FN). DP cell death seems to be TNF-a-independent, but since normal thymocyte export is influenced by ECM and cytokines/chemokines-mediated interactions, we explored the TNF-a plus FN combined contribution to the migratory activity of thymocytes during infection. Briefly, 2,5x106 thymocytes from infected or non-infected mice were incubated in transwell devices and allowed to migrate during 3 hours through a membrane coated with FN (10 mg/ml) plus TNF-a (25 pg/ml) or BSA (PBS/BSA 0.5%). Migrating cells were counted and their phenotype analyzed by cytometry. In all cases, thymocytes from infected mice showed a higher migratory response than non-infected independently of membrane treatment. Strikingly, in infected animals, FN interactions with TNF-a enhanced motility of total thymocytes compared with FN/BSA (p<0.05). The analysis of thymocyte subset input showed similar results, especially in DP cells from infected mice (p<0.05). The blocking of TNF-a activity by anti-TNF-a antibody, diminished significantly DP migration. Thymocytes from infected TNF-R1-/- mice turns down in half the input on FN/TNF-a compared with their normal TNF-R1+/+ counterparts, whereas the addition of TNF-a blocking antibody deeply abrogated DP cell migration, suggesting a role for TNF-R2 in thymocyte migratory activity. Our results put forward that in vivo thymic anomalous exportation of immature and potentially auto reactive DP T cells could be related with a high expression of molecules involved in migratory activity and co-stimulated by TNF-a-deposition. Financial support: CNPq/ProSul (Brazil) and SCyT-UNR (Argentina)