Inhibition of Ca2+ influx by surfactant in NR8383 alveolar macrophages.
OBJECTIVE
Pulmonary surfactants reduce alveolar surface tension and alter inflammatory cell function. We studied the effects of surfactant preparations on Ca2+ influx regulated by protein kinase C (PKC) and mitogen-activated protein kinases (MAPK) and cytokine secretion in the alveolar macrophage (AM) cell line NR8383.


METHODS
Fura-2-loaded AMs were stimulated with zymosan (200 microg/ml), 1,2-dioctanoyl-sn-glycerol (DOG, 20 microM) or C6-ceramide (C6C, 10 microM) in the presence of exogenous surfactants (beractant, calfactant or colfosceril) or surfactant phospholipid (dipalmitoyl phosphatidylcholine, DPPC), at 250 microg/ml phospholipid and changes in cytosolic free Ca2+ (Delta[Ca2+]i) and cytokines were measured.


RESULTS
Zymosan-induced Delta[Ca2+]i (117 +/- 5 nM) at 3 min was reduced (p <0.001) by beractant (50 +/- 6 nM), colfosceril (61 +/- 2 nM), calfactant (46 +/- 5 nM), and DPPC (52 +/- 5 nM). Beractant inhibited the Delta[Ca2+]i by PKC stimulation with DOG and all preparations reduced the MAPK-induced Ca2+ influx by C6C. Beractant and Ca2+ channel blocker SKF 96365 (10 microM) together abolished the zymosan-stimulated Delta[Ca2+]i. Zymosan-stimulated TNF-alpha and IL-1beta secretion was also inhibited by surfactant pretreatment.


CONCLUSIONS
These results indicate that exogenous surfactant inhibits Ca2+ influx and cytokine secretion in zymosan-stimulated AMs. This anti-inflammatory activity may be through an interaction with downstream signaling elements or Ca2+ channels.
Castro
R
R
Department of Pediatrics, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA. castror@uthscsa.edu
Sun
X H
XH
Liu
X-B
XB
Martinez
J R
JR
Zhang
G H
GH
D000818:Animals; D001688:Biological Products / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D051381:Rats; D015054:Zymosan / Q000494:pharmacology
D001688:Biological Products; D002121:Calcium Channel Blockers; D016207:Cytokines; D007093:Imidazoles; D011663:Pulmonary Surfactants; D015054:Zymosan; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; C072197:beractant; D002118:Calcium