Toxoplasma gondii exposes phosphatidylserine inducing a TGF-beta1 autocrine effect orchestrating macrophage evasion.
Toxoplasmosis is a worldwide disease caused by Toxoplasma gondii. Activated macrophages control T. gondii growth by nitric oxide (NO) production. However, T. gondii active invasion inhibits NO production, allowing parasite persistence. Here we show that the mechanism used by T. gondii to inhibit NO production persisting in activated macrophages depends on phosphatidylserine (PS) exposure. Masking PS with annexin-V on parasites or activated macrophages abolished NO production inhibition and parasite persistence. NO production inhibition depended on a transforming growth factor-beta1 (TGF-beta1) autocrine effect confirmed by the expression of Smad 2 and 3 in infected macrophages. TGF-beta1 led to inducible nitric oxide synthase (iNOS) degradation, actin filament (F-actin) depolymerization, and lack of nuclear factor-kappaB (NF-kappaB) in the nucleus. All these features were reverted by TGF-beta1 neutralizing antibody treatment. Thus, T. gondii mimics the evasion mechanism used by Leishmania amazonensis and also the anti-inflammatory response evoked by apoptotic cells.
Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-600 Campos dos Goytacazes, RJ, Brazil.
Sergio H
SH
Seabra
Wanderley
W
de Souza
Renato A
RA
Damatta
D000199:Actins / Q000378:metabolism; D000818:Animals; D004926:Escherichia coli / Q000378:metabolism; D007249:Inflammation; D007891:Leishmania / Q000378:metabolism*; D008262:Macrophage Activation; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010718:Phosphatidylserines / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014122:Toxoplasma / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1
D000199:Actins; D016328:NF-kappa B; D010718:Phosphatidylserines; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse