Hypotonicity induces L-selectin shedding in human neutrophils

Abstract

Expression levels of adhesion molecules on neutrophils are affected under various conditions, including ischemia, possibly because of associated increases in cell volume. We examined the effects of cell swelling in hypotonic media on the level of L-selectin (CD62L) and beta(2)-integrin (CD18) on human neutrophils. In hypotonic media, neutrophils shed L-selectin. The shedding was greatly reduced by 30 microM RO31-9790, the metalloprotease (sheddase) inhibitor. Hypotonicity-induced L-selectin shedding was also time and tonicity dependent. Decreasing tonicity caused increased shedding. In 0.6x medium (0.6x the normal tonicity of 300 mosmol/kgH(2)O), shedding increased over a 2-h period, after which >70% of the neutrophils had lost L-selectin. In contrast to L-selectin, the level of beta(2)-integrin on the neutrophil surface was not significantly affected. Thus L-selectin shedding, which occurs on neutrophil activation and is usually accompanied by beta(2)-integrin upregulation, was selectively induced by hypotonicity without a corresponding effect on beta(2)-integrin.

Mechanical Shedding of L-selectin from the Neutrophil Surface during Rolling on Sialyl Lewis x under Flow

“…We found that the fraction of neutrophils without L-selectin was significantly increased after rolling on the sLe x surface at 4 dyn/cm 2 . Leukocyte stimulation induced by chemotactic factors (15,17) or cell swelling in hypotonic media (19) gives rise to surface L-selectin cleavage, activating TACE. In addition, the crosslinking of L-selectin (16,22,34) also induces L-selectin downregulation from the cell surface.…”

“…For instance, PMA, LPS, FMLP, and other chemoattractants can induce the down-regulation of L-selectin from the cell surface (13,15,17). It is also known that cell shrinking and swelling induced by hyper-or hypotonic media induce L-selectin shedding (18,19). TNF-␣-converting enzyme (TACE; ADAM-17) has been identified as a protease responsible for the cleavage of the extracellular domain of L-selectin by cellular activation (20,21).…”

L-selectin: mechanisms and physiological significance of ectodomain cleavage

“…Others, such as synthetic sulfonated glycoproteins containing multivalent ligands presumably operate via the same mechanism as the crosslinking antibodies [23]. In addition, there are a number of other agents which induce L-selectin shedding, including LPS, both hypertonic and hypotonic shock, and chemotactic factors [2,24,25]. There are others that induce shedding of L-selectin without general cell activation which provide important information about this process.…”

IL-8-induced L-selectin shedding regulates its binding kinetics to PSGL-1

“…Crosslinking L-selectin by multivalent ligand or phenylarsine or varying osmotic pressure induces L-selectin shedding [12][13][14][15] , which can be inhibited by a hydroxamic acid-based peptide inhibitor of matrix metalloprotease KD-IX-73-4 (or TAPI-0) or [16,17] . One of the functionalities of L-selecting shedding is to regulate ARTICLES BIOPHYSICS leukocyte rolling over and binding to its ligand [18][19][20][21][22] .…”