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Infection and Immunity, January 2008, p. 317-323, Vol. 76, No. 1
0019-9567/08/$08.00+0 doi:10.1128/IAI.00618-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom,1 School of Dentistry, University of Birmingham, St. Chad's Queensway, Birmingham B4 6NN, United Kingdom2
Received 1 May 2007/ Returned for modification 16 July 2007/ Accepted 31 October 2007
Porphyromonas gingivalis, a gram-negative anaerobe which is implicated in the etiology of active periodontitis, secretes degradative enzymes (gingipains) and sheds proinflammatory mediators (e.g., lipopolysaccharides [LPS]). LPS triggers the secretion of interleukin-8 (IL-8) from immune (72-amino-acid [aa] variant [IL-872aa]) and nonimmune (IL-877aa) cells. IL-877aa has low chemotactic and respiratory burst-inducing activity but is susceptible to cleavage by gingipains. This study shows that both R- and K-gingipain treatments of IL-877aa significantly enhance burst activation by fMLP and chemotactic activity (P < 0.05) but decrease burst activation and chemotactic activity of IL-872aa toward neutrophil-like HL60 cells and primary neutrophils (P < 0.05). Using tandem mass spectrometry, we have demonstrated that R-gingipain cleaves 5- and 11-aa peptides from the N-terminal portion of IL-877aa and the resultant peptides are biologically active, while K-gingipain removes an 8-aa N-terminal peptide yielding a 69-aa isoform of IL-8 that shows enhanced biological activity. During periodontitis, secreted gingipains may differentially affect neutrophil chemotaxis and activation in response to IL-8 according to the cellular source of the chemokine.
Published ahead of print on 19 November 2007.
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