Type 1 fimbriate Escherichia coli stimulates a unique pattern of degranulation by human polymorphonuclear leukocytes

Abstract

Uropathogenic strains of Escherichia coli bearing mannose-sensitive (type 1) fimbriae promote a unique pattern of degranulation from human polymorphonuclear leukocytes (PMN). Significant quantities of the primary (10) and tertiary (30) granule markers, neutral protease-myeloperoxidase and N-acetyl-o-D-glucosaminidase, respectively, were released by PMN in a dose-and time-dependent manner when stimulated by these defined bacterial strains. Organisms bearing mannose-resistant (P) fimbriae promoted release of only the secondary (2°) granule marker, vitamin B12-binding protein. When this pattern of degranulation was compared to that produced by PMN in response to a variety of soluble and particulate stimuli, only the calcium ionophore A23187 similarly triggered 1°and 30 granule marker release. All the other stimuli tested-zymosan, serum-treated and unopsonized; n-formylmethionyl-leucyl-phenylalanine; and phorbol myristate acetatepromoted release of only the 2°granule marker. These results demonstrate selectivity of PMN degranulation in response to a number of transmembrane signals. In addition, the capacity of E. coli to promote PMN degranulation is dependent on its phenotypic fimbrial expression, a surface characteristic which correlates significantly with its relative surface hydrophobicity as measured by binding to octyl Sepharose. Those bacteria demonstrating the greatest hydrophobicity were capable of triggering discharge of all three granule marker proteins. Thus, the mannose-sensitive fimbriae of uropathogenic E. coli may contribute significantly to their potential pathophysiologic role in renal scarring.

Potent leukocidal action of Escherichia coli hemolysin mediated by permeabilization of target cell membranes.

“…Myeloperoxidase (MPO) and elastase were taken as markers for primary lysosomes (45,46). Vitamin B 12 binding protein was considered a marker for secondary lysosomes, and glucosaminidase was chosen as a marker of tertiary granules (47). Measurements of MPO, vitamin B 12 binding protein, and glucosaminidase release were performed exclusively in protein-free buffer (HBSS or PBS).…”

“…15689) . MPO, vitamin B 12 binding protein, and glucosaminidase were quantified according to described procedures (47). The maximal release (100%) values were those obtained by sonication of cell aliquots (15 s, 50 W).…”

Chemotaxis and degranulation of polymorphonuclear leukocytes in the presence of sulfide

“…For the degranulation experitnents, ITVILP was dissolved in dimethyl sulfoxide (1 mmol/l) and stored at -70 C. This stock solution was diluted 1/100 in PBS itntnediately before use. Serumopsonized zytnosan was prepared as described by Steadtnan et al (18). The serum-opsonized zymosan was suspended in PBS (12.5 mg/nil) and stored at -70 C. In the anaerobic experiments, the solutions containing the various stimulating agents were prepared in the anaerobic chamber.…”

Virulence factors in Escherichia coli urinary tract infection.

“…Type 1 fimbriae promote adherence to hPMNLs (34,277,394,515,547) and phagocytosis by hPMNLs (494,600); antifimbrial antibodies and solutions of mannose or a.-methylmannoside block these interactions (334,335,494,600). When present on unopsonized or hydrophilic bacteria (which interact minimally with phagocytes in the absence of type 1 fimbriae), type 1 fimbriae play a more important role in adherence to phagocytes (155,515), granule release (506), and phagocytosis (394) than when they are present on opsonized or hydrophobic organisms (which readily interact with phagocytes even when nonfimbriated). Whereas purified type 1 fimbriae agglutinate phagocytes (334), only aggregated type 1 fimbriae (i.e., intact fimbriated bacteria or latex beads coated with purified type 1 fimbriae) stimulate chemiluminescence (155,334), demonstrating that monovalent binding is insufficient to stimulate the oxidative burst.…”