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Changes and regulation of the C5a receptor on neutrophils during septic shock in humans


Unnewehr, Heike; Rittirsch, Daniel; Sarma, J Vidya; Zetoune, Firas; Flierl, Michael A; Perl, Mario; Denk, Stephanie; Weiss, Manfred; Schneider, Marion E; Monk, Peter N; Neff, Thomas; Mihlan, Michael; Barth, Holger; Gebhard, Florian; Ward, Peter A; Huber-Lang, Markus (2013). Changes and regulation of the C5a receptor on neutrophils during septic shock in humans. Journal of Immunology, 190(8):4215-4225.

Abstract

During experimental sepsis, excessive generation of the anaphylatoxin C5a results in reduction of the C5a receptor (C5aR) on neutrophils. These events have been shown to result in impaired innate immunity. However, the regulation and fate of C5aR on neutrophils during sepsis are largely unknown. In contrast to 30 healthy volunteers, 60 patients in septic shock presented evidence of complement activation with significantly increased serum levels of C3a, C5a, and C5b-9. In the septic shock group, the corresponding decrease in complement hemolytic activity distinguished survivors from nonsurvivors. Neutrophils from patients in septic shock exhibited decreased C5aR expression, which inversely correlated with serum concentrations of C-reactive protein (CRP) and clinical outcome. In vitro exposure of normal neutrophils to native pentameric CRP led to a dose- and time-dependent loss of C5aR expression on neutrophils, whereas the monomeric form of CRP, as well as various other inflammatory mediators, failed to significantly alter C5aR levels on neutrophils. A circulating form of C5aR (cC5aR) was detected in serum by immunoblotting and a flow-based capture assay, suggestive of an intact C5aR molecule. Levels of cC5aR were significantly enhanced during septic shock, with serum levels directly correlating with lethality. The data suggest that septic shock in humans is associated with extensive complement activation, CRP-dependent loss of C5aR on neutrophils, and appearance of cC5aR in serum, which correlated with a poor outcome. Therefore, cC5aR may represent a new sepsis marker to be considered in tailoring individualized immune-modulating therapy.

Abstract

During experimental sepsis, excessive generation of the anaphylatoxin C5a results in reduction of the C5a receptor (C5aR) on neutrophils. These events have been shown to result in impaired innate immunity. However, the regulation and fate of C5aR on neutrophils during sepsis are largely unknown. In contrast to 30 healthy volunteers, 60 patients in septic shock presented evidence of complement activation with significantly increased serum levels of C3a, C5a, and C5b-9. In the septic shock group, the corresponding decrease in complement hemolytic activity distinguished survivors from nonsurvivors. Neutrophils from patients in septic shock exhibited decreased C5aR expression, which inversely correlated with serum concentrations of C-reactive protein (CRP) and clinical outcome. In vitro exposure of normal neutrophils to native pentameric CRP led to a dose- and time-dependent loss of C5aR expression on neutrophils, whereas the monomeric form of CRP, as well as various other inflammatory mediators, failed to significantly alter C5aR levels on neutrophils. A circulating form of C5aR (cC5aR) was detected in serum by immunoblotting and a flow-based capture assay, suggestive of an intact C5aR molecule. Levels of cC5aR were significantly enhanced during septic shock, with serum levels directly correlating with lethality. The data suggest that septic shock in humans is associated with extensive complement activation, CRP-dependent loss of C5aR on neutrophils, and appearance of cC5aR in serum, which correlated with a poor outcome. Therefore, cC5aR may represent a new sepsis marker to be considered in tailoring individualized immune-modulating therapy.

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19 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Trauma Surgery
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:15 April 2013
Deposited On:17 Jan 2014 07:28
Last Modified:05 Apr 2016 17:24
Publisher:American Association of Immunologists
ISSN:0022-1767
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.4049/jimmunol.1200534
PubMed ID:23479227

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