Wednesday, January 14, 2009

Role of autophagy in the host defense against Toxoplasma gondii in astrocytes

Autophagy. 2009 Feb 17;5(2). [Epub ahead of print]

Role of autophagy in the host defense against Toxoplasma gondii in astrocytes

Halonen SK.

Department of Microbiology, Montana State University, Bozeman, Montana, USA.

Autophagy has recently been implicated in the host defense against the intracellular protozoan pathogen, Toxoplasma gondii, a major opportunistic pathogen of the central nervous system in immunosuppressed individuals. In both IFNgamma-activated macrophages and astrocytes, the p47 GTPases traffic to the T. gondii parasitophorous vacuole, followed by vacuolar disruption, parasite killing and clearance of the dead parasites. In macrophages, it is relatively well established that autophagy is involved in parasite elimination and killing. The role of autophagy in parasite elimination in astrocytes, a dominant host cell in the central nervous system, is much less clear. Our studies indicate that in IFNgamma-stimulated astrocytes, autophagy of disrupted vacuoles and/or dead parasites does not occur but rather that degradation of the parasite occurs in the host cytoplasm. However, recent studies indicate autophagy may be involved in the elimination of the degraded parasite material from the astrocyte host cell cytoplasm and suggest that autophagous removal of degraded parasite material may be necessary for survival of the host cell. Delivery of parasite antigen from the cytosol to the endolysosomal compartments in astrocytes is of importance as it suggests a pathway by which astrocytes could present Toxoplasma antigens via the MHC Class II pathway and function as an antigen-presenting cell for the parasite in the brain.

PMID: 19139630 [PubMed - as supplied by publisher]

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