Eosinophil Cationic Protein (ECP) Is Processed during Secretion

Abstract

The eosinophil granulocyte is an inflammatory cell involved in allergic diseases such as asthma and rhinitis. Eosinophil cationic protein (ECP) is a basic and potentially cytotoxic granule protein that is released from the eosinophil upon activation. The aim was to study secretion of molecular variants of ECP from blood eosinophils with the hypothesis that the stored noncytotoxic ECP is altered into cytotoxic species upon release from the cell. Eosinophil granulocytes were purified to >95% from venous blood from birch pollen allergic subjects, with symptoms of rhinitis, and from healthy control subjects during the birch pollen season. The cells were stimulated with IL-5, GM-CSF, or serum-opsonized Sephadex particles. Concentration of ECP in cells or supernatants was measured by means of a fluoroenzyme immunoassay, and ECP heterogeneity was studied using an affinity capture assay with the surface-enhanced laser desorption/ionization-time of flight mass spectrometry technique. Extracts of unstimulated eosinophils contained 10 major ECP variants, with molecular masses ranging from 16.1 to 17.7 kDa. Stimulation with particles mainly induced the secretion of two molecular variants at 16.1 and 16.3 kDa, while cytokine stimulation gave rise to a different secretion profile. ECP variants in the pellet extracts remained unaffected by cell activation. The modifications of secreted ECP were partly explained by differences in N-linked glycosylations. Secretion of ECP from eosinophils involves protein modification. The molecular masses of released ECP have acquired the masses of the cytotoxic species.

Eosinophil Granule Proteins: Form and Function

“…These ECP genotypes also show associations with the symptoms of allergy and asthma (80,81). Venge and colleagues (82) reported that the various ECP glycoforms are processed during eosinophil secretion; the modifications to secreted ECP by activated eosinophils is explained in part by differences in their degree of N-linked glycosylation, such that secreted ECP acquires the masses of the more cytotoxic, less glycosylated, isoforms, including the nonglycosylated species (82), explaining in part the structural and functional heterogeneity of ECP as reported in the literature.…”

Therapeutic effects of traditional Korean medicine, Jeechool-Whan in allergic rhinitis model

“…Inflammasomes are multiprotein cytoplasmic complexes that mediate the activation of inflammatory caspase-1 (Woschnagg et al, 2009). Inflammasome regulates the activation and secretion of caspase 1-regulated IL-1β and IL-18.…”

Structural determinants of the eosinophil cationic protein antimicrobial activity

“…Site-directed mutagenesis studies identifi ed the main critical residues exposed at the protein surface involved in membrane lysis and cytotoxicity (Carreras et al , 2003 ;Torrent et al , 2007 ;Singh and Batra , 2011 ). Additionally, complementary studies on the protein native posttranslational forms and comparison of polymorphism variants highlighted the contribution of glycosylation on the protein cytotoxic power (Trulson et al , 2007 ;Rubin et al , 2009 ;Woschnagg et al , 2009 ). In the following section, we detail the current knowledge on ECP antimicrobial properties.…”

“…In fact, the proteolytic processing is used extensively in immunology cascade events. A local cleavage can release the active peptides in the infection area in the same manner as cecropin is released from cathelicidins expressed in neutrophils (Zanetti et al , 1995 ;Burton and Steel , 2009 ), lactoferricin is derived from the N-terminus (Krieg et al , 1998 ;Clark et al , 2003 ); Tyr33 nitration (Ulrich et al , 2008 ) Host defense against viral infections; chemotaxis for dendritic cells (Rosenberg , 2008a ) RNase 3 (tested against several Gram-negative and -positive species (Torrent et al , 2009b(Torrent et al , , 2011b Arg97/Thr (related to asthma propensity and disease-induced pathologies) (Eriksson et al, 2007a;Adu et al , 2011 ) Gly103Arg 3 potential N-glycosylation sites; 10 purifi ed variants of N-linked glycosylated forms (Eriksson et al , 2007b ); N-glycosylation processed upon secretion by activated eosinophils (Woschnagg et al , 2009 );…”