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Mediators of Inflammation
Volume 2007, Article ID 84318, 7 pages
http://dx.doi.org/10.1155/2007/84318
Research Article

Proinflammatory Cytokine Gene Expression by Murine Macrophages in Response to Brugia malayi Wolbachia Surface Protein

1Lymphatic Filariasis Research Unit, Department of Parasitology, and Chulalongkorn Medical Research Center, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
2Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA

Received 29 November 2006; Accepted 26 February 2007

Copyright © 2007 Chantima Porksakorn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Wolbachia, an endosymbiotic bacterium found in most species of filarial parasites, is thought to play a significant role in inducing innate inflammatory responses in lymphatic filariasis patients. However, the Wolbachia-derived molecules that are recognized by the innate immune system have not yet been identified. In this study, we exposed the murine macrophage cell line RAW 264.7 to a recombinant form of the major Wolbachia surface protein (rWSP) to determine if WSP is capable of innately inducing cytokine transcription. Interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF) mRNAs were all upregulated by the rWSP stimulation in a dose-dependant manner. TNF transcription peaked at 3 hours, whereas IL-1β and IL-6 transcription peaked at 6 hours post-rWSP exposure. The levels of innate cytokine expression induced by a high-dose (9.0 μg/mL) rWSP in the RAW 264.7 cells were comparable to the levels induced by 0.1 μg/mL E. coli-derived lipopolysaccharides. Pretreatment of the rWSP with proteinase-K drastically reduced IL-1β, IL-6, and TNF transcription. However, the proinflammatory response was not inhibited by polymyxin B treatment. These results strongly suggest that the major Wolbachia surface protein molecule WSP is an important inducer of innate immune responses during filarial infections.