Banca de DEFESA: GRAZIELE QUINTELA DE CARVALHO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GRAZIELE QUINTELA DE CARVALHO
DATA : 05/07/2019
HORA: 13:00
LOCAL: Instituto Gonçalo Moniz
TÍTULO:

Mechanisms of activation of neutrophils infected by Leishmania infantum: role of heme and lipofosfoglican (LPG)

PALAVRAS-CHAVES:

Neutrophil, Leishmania, Heme, lipofosfoglican (LPG).

PÁGINAS: 80
GRANDE ÁREA: Ciências Biológicas
ÁREA: Parasitologia
SUBÁREA: Protozoologia de Parasitos
ESPECIALIDADE: Protozoologia Parasitária Humana
RESUMO:

Visceral Leishmaniasis (VL) is among the most relevant zoonoses transmitted by vectors. Severe patients with VL present blood disorders, such as hemolysis and heme free, which may alter the behavior of neutrophils. In the present study, we noticed that in patients with VL there is a direct association between heme levels and neutropenia. From in vitro tests, we have seen that heme reduces the survival of human neutrophils infected with Leishmania infantum through the production of reactive oxygen species and release of neutrophilic enzymes, while favoring the viability of the parasite. In addition, neutrophils infected with heme showed an increase in the enzymatic activity of superoxide dismutase-1 (SOD-1) and with interference in the oxidative pathways there was a reduction in the proliferation rate of L. infantum in these cells. Thus, the activation of neutrophils in the presence of heme, causes the death of the cell and the survival of the parasites. We then investigated the lipofosfoglican (LPG) of L. infantum as well as the activation trigger of neutrophils at the initial moments of infection. In order to evaluate how the L. infantum surface LPG interferes with the activation of neutrophils, we infected human neutrophils with LPG deficient parasites (∆lpg1) and compared them with wild promastigotes (WT) or parasites that had their LPG reconstituted (∆lpg1+LPG1). The absence of LPG in ∆lpg1 forms increased the infection rate, but favored the mortality of these forms in neutrophils compared to WT or ∆lpg1+LPG1. Regarding the activation of neutrophils, there was an expressive production of reactive oxygen species (ROS) in cultures infected with L. infantum ∆lpg1, able to modulate the survival of these promastigotes. These findings stimulate new interpretations in the context of VL and evidence the complexity of neutrophil-parasite interactions depending on the stimulus.

MEMBROS DA BANCA:
Interno - 796.762.515-34 - JULIANA PERRONE BEZERRA DE MENEZES FULLAM - UFBA
Interno - 028.288.917-55 - VALÉRIA DE MATOS BORGES - UFRJ
Interno - 1205225 - WASHINGTON LUIS CONRADO DOS SANTOS
Externo ao Programa - 1816975 - LUCAS PEDREIRA DE CARVALHO
Externo à Instituição - VIVIANE SAMPAIO BOAVENTURA DE OLIVEIRA - Fiocruz-Ba
Externo à Instituição - NATALIA BARBOSA CARVALHO