Regulation of neutrophil activation by proteolytic processing of platelet-derived alpha-chemokines.

Abstract

In recent years evidence has been accumulated that platelets besides their function in coagulation play an important role in inflammation and wound repair. Upon activation platelets release a variety of mediators, among which members of the α-chemokine subfamily of proinflammatory cytokines have been identified. These platelet-derived polypeptides do not only comprise members of the so-called ß-thromboglobulin family, such as platelet basic protein (PBP), connective tissue-activating peptide III (CTAP-III), and neutrophil-activating peptide 2 (NAP-2)1, but also platelet factor 4 (PF4)2,3 and the ß-chemokine RANTES (Regulated upon activation normal T cell expressed and probably secreted)4. While ß-chemokines have been shown to activate monocytes, T lymphocytes and eosinophils, α-chemokines such as IL-8, NAP-2 and melanoma growth-stimulating activity (MGSA/gro-α) appear to represent rather selective activators of polymorphonuclear leukocytes (PMN)5. Importantly, their biological activity, such as chemotaxis and degranulation-inducing capacity, has been demonstrated to be closely connected with the presence of an N-terminal glutamic acid-leucine-arginine (ELR) motif. Only recently, attention has been paid to the regulatory properties of α-chemokines. In the present article we will focus on two aspects of regulation of PMN functions, namely 1. the proteolytic processing of platelet-derived α-chemokines as a regulatory event in the induction and modulation of PMN activation, and 2. the phenotypic and functional consequences for the PMN under the constraints of such regulatory events.KeywordsProteolytic ProcessingNeutrophil ActivationPlatelet FactorInactive PrecursorElastase ReleaseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.