title: CXC chemokine receptor CXCR2 is essential for protective innate host response in murine Pseudomonas aeruginosa pneumonia.
abstract: Pulmonary infection due to Pseudomonas aeruginosa has emerged as a leading cause of mortality. A vigorous host response is required to effectively clear the organisms from the lungs. This host defense is dependent on the recruitment and activation of neutrophils and macrophages. A family of chemotactic cytokines (chemokines) has been shown to participate in this protective response. In this study, we assessed the role of the ELR(+) (glutamic acid-leucine-arginine motif positive) CXC chemokines and their CXC chemokine receptor (CXCR2) in lung antibacterial host defense. The intratracheal administration of Pseudomonas to mice resulted in the time-dependent influx of neutrophils to the lung, peaking at 12 to 24 h after inoculation. The influx of neutrophils was associated with a similar time-dependent expression of the ELR(+) CXC chemokines, KC, macrophage inflammatory protein 2 (MIP-2), and lipopolysaccharide-induced CXC chemokine (LIX). Selective neutralization of MIP-2 or KC resulted in modest changes in neutrophil influx but no change in bacterial clearance or survival. However, neutralization of CXCR2 resulted in a striking increase in mortality, which was associated with a marked decrease in neutrophil recruitment and bacterial clearance. Conversely, the site-specific transgenic expression of KC resulted in enhanced clearance of bacteria after Pseudomonas challenge. This study indicates that ELR(+) CXC chemokines are critical mediators of neutrophil-mediated host defense in Pseudomonas pneumonia.
authors.affiliation: Department of Pediatrics, Division of Pulmonary and Critical Care Medicine, The University of Michigan Medical School, Ann Arbor, Michigan 48109-0360, USA. wctsai@umich.edu
authors.forename: W C
authors.initials: WC
authors.lastname: Tsai
authors.forename: R M
authors.initials: RM
authors.lastname: Strieter
authors.forename: B
authors.initials: B
authors.lastname: Mehrad
authors.forename: M W
authors.initials: MW
authors.lastname: Newstead
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.forename: T J
authors.initials: TJ
authors.lastname: Standiford
mesh_terms: D000818:Animals; D001483:Base Sequence; D019743:Chemokines, CXC / Q000096:biosynthesis / Q000235:genetics; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D005260:Female; D006801:Humans; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009500:Neutralization Tests; D009504:Neutrophils / Q000276:immunology; D018410:Pneumonia, Bacterial / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D011552:Pseudomonas Infections / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019707:Receptors, Chemokine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018123:Receptors, Interleukin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D023063:Receptors, Interleukin-8B
chemical_list: D019743:Chemokines, CXC; D016207:Cytokines; D017931:DNA Primers; D012333:RNA, Messenger; D019707:Receptors, Chemokine; D018123:Receptors, Interleukin; D023063:Receptors, Interleukin-8B