Atividade imunomoduladora de células dendríticas pulsadas com antígenos de Pythium insidiosum sobre a resposta celular in vitro

Abstract

Pythiosis is a severe disease caused by the Oomycete Pythium insidiosum which can affect animals and humans. If not diagnosed and immediately treated, pythiosis can lead the affected host to death. Pythiosis treatment is difficult since it does not respond well to drugs commonly used in fungal diseases due to the lack of ergosterol in P. insidiosum cell wall. Due to this difficulty in pythiosis treatment with drugs, a therapeutic approach that is being successfully used is immunotherapy. The most accepted hypothesis to explain immunotherapy success is that they can switch host’s immune response from a Th2 to a Th1 response, with IFN-γ and IL-2 production, which activate mononuclear cells mediators as an immune response composed of T lymphocytes and macrophages which destroy P. insidiosum hyphae. A therapeutic approach that is gaining importance is the use of dendritic cells (DCs) as adjuvant, since DCs are capable of prime a strong cellular response. In this scenario, the aim of this study was to evaluate the stimulatory and immunomodulatory effects of DCs pulsed with different P. insidiosum antigens in human Th response in vitro. Peripheral blood monocytes were differentiated into DCs, which were pulsed with the immunotherapeutic PitiumVac®, β-glucans extracted from P. insidiosum cell wall, and Heat-inactivated (HI) zoospore. After sensitization, DCs pulsed with the tested antigens were co-cultured with lymphocytes for 24 hours and the supernatant was used to quantify the Th1, Th2 and Th17 cytokines produced. We also analyzed the proliferative rate of lymphocytes cultured with the pulsed DCs after 72 hours of incubation. Our results showed that DCs pulsed with P. insidiosum HI zoospores, β-glucans and the immunotherapeutic PitiumVac® efficiently induced T cell differentiation in a Th1 phenotype by the activation of specific Th1 cytokines production in vitro. HI zoospores showed the highest Th1 response among the tested groups, with a significant increase in IL-6 and IFN-γ production. These results suggest a potential use of DCs pulsed with P. insidiosum heat-inactivated zoospores as a new therapeutic strategy in the treatment and acquisition of immunity against pythiosis.