Published online before print December 28, 2007

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Copyright © 2008 American Society for Investigative Pathology
American Journal of Pathology, doi:10.2353/ajpath.2008.070567

Accepted for publication September 13, 2007.

Article

Both TLR2 and TLR4 Are Required for the Effective Immune Response in Staphylococcus aureus-Induced Experimental Murine Brain Abscess

Werner Stenzel^*@, Sabine Soltek, Monica Sanchez-Ruiz^*, Shizuo Akira, Hrvoje Miletic^*, Dirk Schlüter, and Martina Deckert^*

From the Abteilung für Neuropathologie,* Universität zu Köln, Köln, Germany; the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Mannheim, Universität Heidelberg, Mannheim, Germany; the Department of Host Defense, Research Institute for Microbial Diseases, Osaka University and ERATO of Japan Science and Technology Corporation, Osaka, Japan; and the Institut für Medizinische Mikrobiologie, Otto-von-Guericke Universität Magdeburg, Magdeburg, Germany

^@ To whom correspondence should be addressed. E-mail: w.stenzel{at}uni-koeln.de.

	Abstract

Toll-like receptors (TLRs) play central roles in the innate reaction to bacterial products and transmit specific immune responses against these pathogens. TLRs are expressed on numerous cell types, including innate immune cells, and on astrocytes, neurons, and microglial cells of the central nervous system (CNS). Lipoproteins and lipopolysaccharides are specifically recognized by TLR2 and TLR4, respectively. We examined the in vivo role of TLR2 and TLR4 in Staphylococcus aureus-induced brain abscess. Phenotypically, 87% of TLR2^-/- mice and 43% of TLR4^-/- mice died whereas all wild-type (WT) mice recovered. Clearance of bacteria from the CNS was significantly delayed in TLR2^-/- mice compared with TLR4^-/- and WT animals. Recruitment of granulocytes and macrophages to the CNS, as well as microglial activation and expansion, was up-regulated in TLR2^-/- mice. Although inflammation persisted especially in the CNS of TLR2^-/- mice, but also of TLR4^-/- mice, WT mice terminated the infection more effectively. Collectively, these data show that the immune response to experimental S. aureus-induced brain abscess depends crucially on the recognition of S. aureus by TLR2 but that TLR4 is also required for an optimal intracerebral immune response in this disorder.