Chloride Movements in Human Neutrophils during Phagocytosis: Characterization and Relationship to Granule Release

Abstract

Chloride ion efflux is an early event occurring after exposure of human neutrophils to several soluble agonists. Under these circumstances, a rapid and reversible fall in the high basal intracellular chloride (Cl−i) levels is observed. This event is thought to play a crucial role in the modulation of several critical neutrophil responses including activation and up-regulation of adhesion molecules, cell attachment and spreading, cytoplasmic alkalinization, and activation of the respiratory burst. At present, however, no data are available on chloride ion movements during neutrophil phagocytosis. In this study, we provide evidence that phagocytosis of Candida albicans opsonized with either whole serum, complement-derived opsonins, or purified human IgG elicits an early and long-lasting Cl− efflux accompanied by a marked, irreversible loss of Cl−i. Simultaneous assessment of Cl− efflux and phagocytosis in cytochalasin D-treated neutrophils indicated that Cl− efflux occurs without particle ingestion. These results suggest that engagement of immune receptors is sufficient to promote chloride ion movements. Several structurally unrelated chloride channel blockers inhibited phagocytosis-induced Cl− efflux as well as the release of azurophilic—but not specific—granules. It implicates that different neutrophil secretory compartments display distinct sensitivity to Cl−i modifications. Intriguingly, inhibitors of Cl− exchange inhibited cytosolic Ca2+ elevation, whereas Cl− efflux was not impaired in Ca2+-depleted neutrophils. We also show that FcγR(s)- and CR3/CR1-mediated Cl− efflux appears to be dependent on protein tyrosine phosphorylation but independent of PI3K and phospholipase C activation.

The role of chloride anion and CFTR in killing ofPseudomonas aeruginosaby normal and CF neutrophils

“…Transport of chloride by the plasma membrane is well-studied and chloride influx and efflux from the cytosol has been shown to be rapid and fully exchangeable [30]. Moreover, upon stimulation with neutrophil agonists, such as opsonized zymosan or formylated peptides, there is a rapid efflux of chloride from the cytosol resulting in lowering of the cytosolic chloride level from about 90-110 mM to about 50-60 mM [41]. Recent data from our laboratory show that the phagolysosomal chloride level in zymosan-activated cells is ~72 mM, similar to that in the cytosol [42].…”

Chloride Channel Blockers Suppress Formation of Engulfment Pseudopodia in Microglial Cells

“…Since an inward Cl - -current represents an efflux of Cl - , K + as well as Cl - leaves the cell. Similarly, in human PMNs, phagocytosis of opsonized Candida albicans induces a Cl - -efflux [1]. Furthermore, in microglial cells and PMNs, application of Cl - -channel blockers suppresses engulfment of polystyrene MBs, E. coli , S. aureus , or C. albicans [[2,3,4], and present study].…”

“…Recognition of opsonised Candida albicans by human polymorphonuclear neutrophil leucocytes (PMNs) triggers the efflux of Cl - in these cells [1]. Accordingly inhibition of Cl - -channel activity in human PMNs decreases the uptake of opsonized zymosan [2].…”

Cytosolic Cl- Affects the Anticancer Activity of Paclitaxel in the Gastric Cancer Cell Line, MKN28 Cell

“…Recent studies have revealed that Cl - plays fundamental roles in various cellular functions, such as cell cycle progression and proliferation [12, 13, 24-29], water secretion [30-32], regulation of gene expression [11, 33, 34], adhesion and migration of cells [6, 35-37], and neurite outgrowth in neuronal cells [14, 38-40]. Nakajima et al [15] have also demonstrated that microtubule polymerization was enhanced by the presence of Cl - via inhibition of intrinsic GTPase activity of α-tubulin in vitro .…”

“…Among them, several reports have shown that Cl - channels might regulate various cellular functions such as cell cycle progression, proliferation, adhesion and migration including cancer cells [6-10]. We have previously reported that reduction of cytosolic Cl - concentration enhance gene expression of the α-subunit of epithelial Na + channel in Xenopus laevis kidney A6 cells [11].…”