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This Article Full Text Full Text (PDF) All Versions of this Article: 291/2/L157    most recent 00358.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Mueller-Ortiz, S. L. Articles by Wetsel, R. A. Search for Related Content PubMed PubMed Citation Articles by Mueller-Ortiz, S. L. Articles by Wetsel, R. A.

Ablation of the complement C3a anaphylatoxin receptor causes enhanced killing of Pseudomonas aeruginosa in a mouse model of pneumonia

¹Research Center for Immunology and Autoimmune Diseases, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas Health Science Center at Houston, Houston; and ²Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, Texas

Submitted 18 August 2005 ; accepted in final form 31 January 2006

The C3a anaphylatoxin is a 77-amino acid peptide that is generated by enzymatic cleavage of C3 during activation of the complement system. C3a mediates numerous biological functions on binding its receptor (C3aR), which is present on both myeloid and nonmyeloid cells. To investigate the biological impact of C3a-mediated effects during acute pneumonia caused by Pseudomonas aeruginosa, we subjected C3aR-deficient mice and matched wild-type (WT) mice to P. aeruginosa pulmonary infection. C3aR-deficient mice exhibited increased killing of P. aeruginosa in the lungs, less dissemination of bacteria into the bloodstream, and a decreased inflammatory response to P. aeruginosa pulmonary infection compared with WT mice. To examine whether the absence of C3aR would impact the humoral immune response to P. aeruginosa, we immunized WT and C3aR-deficient mice via intraperitoneal injection with live P. aeruginosa. Both groups of mice developed similar levels of antibody specific to P. aeruginosa. Immunized C3aR-deficient and WT mice were subjected to P. aeruginosa pulmonary infection, and C3aR-deficient mice again displayed increased killing of P. aeruginosa in the lungs, less dissemination of bacteria into the bloodstream, and a decreased inflammatory response in the lungs. Collectively, these data demonstrate that independently of antibody production, absence of C3aR causes enhanced killing of P. aeruginosa despite a diminished inflammatory response in a mouse model of pneumonia.

bacteria; pulmonary; infection; inflammation; antibody