Neutrophil Adhesion to Vascular Prosthetic Surfaces Triggers Nonapoptotic Cell Death

Abstract

ObjectiveTo test the hypothesis that neutrophil adhesion to expanded polytetrafluoroethylene (ePTFE) and Dacron triggers cell death. Summary Background DataVascular prosthetic infections are intransigent clinical dilemmas associated with excessive rates of death and complications. Impaired neutrophil function has been implicated in the infection of implanted cardiovascular devices. ePTFE and Dacron are potent neutrophil stimuli able to elicit activation responses such as reactive oxygen species production independent of exogenous/soluble agonists. Reactive oxygen species that are released into the medium when neutrophils are challenged by soluble agonists are known to cause selfdestruction. The authors therefore sought to examine whether neutrophil adhesion to prosthetic graft materials decreases neutrophil viability by means of reactive oxygen species production. MethodsNeutrophils were adhered to surfaces for up to 6 hours. Cell viability was monitored with propidium iodide staining and lactate dehydrogenase release. ResultsWithin 6 hours of adhesion to ePTFE and Dacron, respectively, 59% Ϯ 11% and 44% Ϯ 5% (n ϭ 7) of the neutrophils were stained by propidium iodide. Indistinguishable results were obtained with plasma-coated ePTFE and Dacron. In contrast, less than 2% of the neutrophils adherent to fibrinogen-, immunoglobin-, or fetal bovine serum-coated polystyrene surfaces for 6 hours were positive for propidium iodide. The increase in membrane permeability to propidium iodide was accompanied by a two-to threefold increase in lactate dehydrogenase release. Pretreatment of neutrophils with Nacetyl-L-cysteine, cytochalasin D, or cyclosporin A significantly reduced the number of propidium iodide-positive ePTFE and Dacron adherent neutrophils. ConclusionsNeutrophil adhesion to ePTFE and Dacron triggers a rapid nonapoptotic cell death. The effect of ePTFE and Dacron on neutrophil viability appears to be caused by reactive oxygen species production. The premature death of graft-adherent neutrophils provides a novel explanation of the defect in neutrophil bacterial killing associated with vascular prosthetic grafts.Vascular prosthetic infections are intransigent clinical complications associated with excessive rates of death and complications. It has been estimated that the number of vascular graft procedures performed in the United States per year exceeds 500,000, including peripheral vascular reconstruction and coronary bypass grafts. Because of the limitations of prosthetic materials in small vessel configurations, they are used in less than a third of these procedures. Infections occur in 2% to 12% of implanted vascular prostheses despite the use of systemic antibiotic prophylaxis. When these events unfold, they are associated with death rates of 30% to 50% and limb loss in approximately one third to one half of survivors. 1-4The epidemiology of vascular prosthetic infections supports the hypothesis that implant infections occur because of contamination of the prosthesis with small numbers of bacteria that find...

Virulent Shigella flexneri Causes Damage to Mitochondria and Triggers Necrosis in Infected Human Monocyte-Derived Macrophages

“…One objective in this study was to examine the temporal correlation between the change in cell membrane permeability and other intracellular events that take place in the same cell. To this end, the effect of Shigella on cell viability was examined by using a microscopy-based assay with two fluorescent dyes, the red-fluorescing membrane-impermeable dye PI and the green-fluorescing membrane-permeable dye Syto 9 (29). In preliminary studies, cells were stained and analyzed by fluorescence microscopy within 30 min of infection and subsequently at 30-min intervals.…”

“…Timedependent changes in cell membrane permeability were monitored by fluorescence microscopy by using two DNA binding dyes, the green fluorescent dye Syto 9 and the red fluorescent vital dye propidium iodide (PI) (Molecular Probes), as described previously (29). A stock of the dyes was made by diluting each dye at a ratio of 1:200 in HBSS.…”

Neutrophil survival on biomaterials is determined by surface topography

“…Whole blood was collected into EDTA-containing Vacutainer tubes and isolated with single-step neutrophil isolation medium (Cardinal Associates Inc, Santa Fe, NM), as described. 2,23 The neutrophils were resuspended in Hanks' balanced salt solution (HBBS) with Ca ϩϩ and Mg ϩϩ (Gibco, Grand Island, NY). The isolated neutrophils were 97% viable.…”

“…We reported that neutrophil adhesion to uncoated or plasma-coated expanded polytetrafluoroethylene (ePTFE) 1 and Dacron, but not to uncoated or protein coated polystyrene surfaces, triggered within hours nonapoptotic cell death in vitro and in vivo. 2 The changes observed included increased membrane permeability and cytoplasmic degeneration in the absence of DNA fragmentation. Since the cell death response induced by biomaterials is distinct from apoptosis, we coined the term "synxenatosis," because the cell death (thanato, death) was precipitated by neutrophil attachment (syndesi) to a foreign (xeno) material.…”

“…Since the cell death response induced by biomaterials is distinct from apoptosis, we coined the term "synxenatosis," because the cell death (thanato, death) was precipitated by neutrophil attachment (syndesi) to a foreign (xeno) material. 2 The relative propensity of Dacron and ePTFE to become infected has never been resolved, though most clinicians favor the view that ePTFE is less infection prone. It is not clear whether these differences will be borne out over the long term or in different applications.…”