Major trauma enhances store-operated calcium influx in human neutrophils.
OBJECTIVE
Chemotaxins from inflammatory sites prime or activate neutrophils (PMN) by using cytosolic calcium ([Ca2+]i) fluxes as second messengers. [Ca2+]i can be mobilized rapidly by receptor-mediated entry or store-release, or more slowly by store-operated calcium influx (SOCI). We studied [Ca2+]i mobilization by chemotaxins and how trauma impacts the calcium entry mechanisms used by chemotaxins.


METHODS
[Ca2+]i flux was studied by spectrofluorometry. The contributions of early and late [Ca2+]i currents to net calcium flux were compared after stimulation by more potent (fMLP, C5a, PAF) or less potent (IL-8, GRO-alpha, and LTB4) agonists. Store operated [Ca2+]i mobilization was reflected by the ratio of area under the [Ca2+]i efflux curve to peak [Ca2+]i (efflux curve). PMN from trauma patients (ISS > 25) and pair-matched volunteer (n = 7 pairs) were then primed and stimulated with thapsigargin to compare cell calcium stores and SOCI.


RESULTS
Late [Ca2+]i mobilization made more important contributions to fMLP, PAF, and C5a signals than to IL-8, GRO-alpha, or LTB4 (p < 0.01 all comparisons). Calcium stores and store release were only marginally lower after injury (p = not significant), but trauma PMN showed far higher [Ca2+]i influx after thapsigargin (p = 0.007), and greater net SOCI (p = 0.034).


CONCLUSIONS
SOCI may play an important role in PMN activation, and trauma increases PMN SOCI. Prolonged elevations of [Ca2+]i due to enhanced SOCI may alter stimulus-response coupling to chemotaxins and contribute to PMN dysfunction after injury.
Hauser
C J
CJ
Department of Surgery, UMD-New Jersey Medical School, Newark 07103, USA. hausercj@UMDNJ.edu
Fekete
Z
Z
Livingston
D H
DH
Adams
J
J
Garced
M
M
Deitch
E A
EA
D000328:Adult; D002118:Calcium / Q000097:blood*; D015936:Complement C5a / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D016209:Interleukin-8 / Q000494:pharmacology; D007975:Leukotriene B4 / Q000494:pharmacology; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology; D013053:Spectrophotometry; D014947:Wounds and Injuries / Q000097:blood*
D016209:Interleukin-8; D010972:Platelet Activating Factor; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D002118:Calcium