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Sci. Signal., 16 February 2010
Vol. 3, Issue 109, p. ra11
[DOI: 10.1126/scisignal.2000697]


Microbial Hijacking of Complement–Toll-Like Receptor Crosstalk

Min Wang1, Jennifer L. Krauss1,2, Hisanori Domon2, Kavita B. Hosur2, Shuang Liang2, Paola Magotti3, Martha Triantafilou4, Kathy Triantafilou4, John D. Lambris3, and George Hajishengallis1,2*

1 Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
2 Oral Health and Systemic Disease, University of Louisville School of Dentistry, Louisville, KY 40292, USA.
3 Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
4 Infection and Immunity Group, University of Sussex School of Life Sciences, Falmer, Brighton, BN1 9QG, UK.

Abstract: Crosstalk between complement and Toll-like receptors (TLRs) coordinates innate immunity. We report a previously unknown immune subversion mechanism involving microbial exploitation of communication between complement and TLRs. Porphyromonas gingivalis, a major oral and systemic pathogen with complement C5 convertase–like activity, synergizes with C5a (fragment of complement protein C5) to increase cyclic adenosine monophosphate (cAMP) concentrations, resulting in suppression of macrophage immune function and enhanced pathogen survival in vitro and in vivo. This synergy required TLR2 signaling, a pertussis toxin– and thapsigargin-sensitive C5a receptor pathway, with protein kinase A and glycogen synthase kinase-3β as downstream effectors. Antagonistic blockade of the C5a receptor abrogated this evasive strategy and may thus have important therapeutic implications for periodontitis and atherosclerosis, diseases in which P. gingivalis is implicated. This first demonstration of complement-TLR crosstalk for immunosuppressive cAMP signaling indicates that pathogens may not simply undermine complement or TLRs (or both) as separate entities, but may also exploit their crosstalk pathways.

* To whom correspondence should be addressed. E-mail: g0haji01{at}

Citation: M. Wang, J. L. Krauss, H. Domon, K. B. Hosur, S. Liang, P. Magotti, M. Triantafilou, K. Triantafilou, J. D. Lambris, G. Hajishengallis, Microbial Hijacking of Complement–Toll-Like Receptor Crosstalk. Sci. Signal. 3, ra11 (2010).

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