Sunday, August 10, 2008

CCR2 Receptor Is Essential to Activate Microbicidal Mechanisms to Control Toxo Infection in the CNS

Am J Pathol. 2008 Aug 7. [Epub ahead of print]

CCR2 Receptor Is Essential to Activate Microbicidal Mechanisms to Control Toxoplasma gondii Infection in the Central Nervous System

Benevides L, Milanezi CM, Yamauchi LM, Benjamim CF, Silva JS, Silva NM.

From the Department of Biochemistry and Immunology,* School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo; the State University of Londrina, Londrina, Paraná; the Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro; and the Department of Morphology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil.

Chemokines comprise a structurally related family of cytokines that regulate leukocyte trafficking. Because infection with Toxoplasma gondii can induce an important inflammatory reaction that, if left uncontrolled, can lead to death, we investigated the role of the chemokine receptor CCR2 in T. gondii infection. We orally infected CCR2(-/-) mice with five ME-49 T. gondii cysts and monitored morbidity, survival, and immune response thereafter. The CCR2(-/-) mice displayed higher susceptibility to infection as all mice died on day 28 after infection. Despite similar Th1 responses, a more evident anti-inflammatory response was induced in the peripheral organs of CCR2(-/-) mice compared with wild-type C57BL/6 mice. Additionally, CCR2(-/-) mice presented greater parasitism and a milder inflammatory reaction in their peripheral organs with lesser CD4(+) and MAC-1(+) and greater CD8(+) cell migration. The parasite load decreased in these organs in CCR2(-/-) mice but remained uncontrolled in the central nervous system. Additionally, we observed down-regulated inducible nitric oxide synthase expression in peripheral organs from CCR2(-/-) mice that was associated with a small nitric oxide production by spleen macrophages. In conclusion, in the absence of CCR2, another mechanism is activated to control tissue parasitism in peripheral organs. Nevertheless, CCR2 is essential for the activation of microbicidal mediators that control T. gondii replication in the central nervous system.

PMID: 18688032 [PubMed - as supplied by publisher]

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