Tuesday, September 20, 2011

A Critical Role for SOCS3 in Innate Resistance to Toxoplasma gondii

Cell Host Microbe. 2011 Sep 15;10(3):224-36

A Critical Role for SOCS3 in Innate Resistance to Toxoplasma gondii

Whitmarsh RJ, Gray CM, Gregg B, Christian DA, May MJ, Murray PJ, Hunter CA

SourceDepartment of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 380 South University Avenue, Philadelphia, PA 19104, USA.

The innate and adaptive immune responses that confer resistance to the intracellular pathogen Toxoplasma gondii critically depend on IL-12 production, which drives interferon-γ (IFN-γ) expression. Certain cytokines can activate STAT3 and limit IL-12 production to prevent infection-associated immune pathology, but T. gondii also directly activates STAT3 to evade host immunity. We show that suppressor of cytokine signaling molecule 3 (SOCS3), a target of STAT3 that limits signaling by the pleiotropic cytokine IL-6, is upregulated in response to infection but is dispensable for the immune-inhibitory effects of T. gondii. Unexpectedly, mice with targeted deletion of SOCS3 in macrophages and neutrophils have reduced IL-12 responses and succumb to toxoplasmosis. Anti-IL-6 administration or IL-12 treatment blocked disease susceptibility, suggesting that in the absence of SOCS3, macrophages are hypersensitive to the anti-inflammatory properties of IL-6. Thus, SOCS3 has a critical role in suppressing IL-6 signals and promoting immune responses to control T. gondii infection.

Copyright © 2011 Elsevier Inc. All rights reserved.

PMID:21925110[PubMed - in process]

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