CONICET | Buscador de Institutos y Recursos Humanos

We previously demonstrated that T. cruzi-infected weaning rats (21-day old) were more susceptible to infection than their adult counterparts (aged 70-days). To gain a further insight on this age-related susceptibility, we evaluated some features of the inflammatory response elicited either by T. cruzi infection or LPS (mimetic to T. cruzi-GPI anchors) challenge in weaning and adult rats. LPS inoculation in weaning rats led to a 50% mortality and an increased IL-10 production respect adult-challenged rats (overall p<0.02). Opposite cytokine profiles were seen during T. cruzi infection, with TNF-a levels being higher in weaning rats (90 h p.i.; p=0.016), and IL-10 showing increased values in adult animals (24 h p.i.; p=0.029). Accompanying these findings, corticosterone and TGF-b levels detectable in both infected groups were more elevated in weaning animals (p<0.05). Noticeably, younger rats had a decreased ability to control parasitemia compared with adult animals. In vitro studies evidenced that weaning rat-derived peritoneal macrophages exposed to LPS produced higher TNF-a levels in comparison to whose derived from adult counterparts (p=0.05). The greater susceptibility of weaning rats to the T. cruzi infection seems to be related to a different profile of the inflammatory reaction, also involving the adrenal endocrine response.