Am. J. Respir. Cell Mol. Biol., Vol 13, No. 3, Sep 1995, 366-375.
Calcium and protein kinase C dependency of lipoxygenase-derived neutrophil chemotactic activity release from bronchial epithelial cells
S Koyama, JG Garcia, SI Rennard and RA Robbins
First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.
In the present investigation, we evaluated the roles of calcium,
calcium-calmodulin, inositol turnover, and protein kinase C in the release
of lipoxygenase-derived metabolites with neutrophil chemotactic activity
(NCA) from bronchial epithelial cells (BECs) in response to endotoxin (ETX)
and opsonized zymosan (OZ). Both ETX and OZ stimulated BECs to release NCA
[56.9 +/- 5.1 (ETX), 65.2 +/- 5.1 (OZ) versus 15.2 +/- 3.0 (controls)
cells/high power field, P < 0.001]. The lipoxygenase inhibitors,
nordihydroguaiaretic acid and diethylcarbamazine, and phospholipase A2
inhibitors, mepacrine and dibucaine, blocked the release of NCA in response
to ETX, OZ, calcium ionophore A23187 (A23187), and phorbol myristate
acetate (PMA). The calcium channel blockers, nifedipine and verapamil, and
two putative inhibitors of calcium release from intracellular storage
sites, 8-(N,N-diethylamine)- octyl-3,4,5-trimethoxybenzoate hydrochloride
and ruthenium red, inhibited the release of NCA induced by ETX but had
little effect on the release of NCA induced by OZ. However, depletion of
extracellular calcium inhibited the release of NCA in response to both ETX
and OZ. Calmodulin inhibitors, compound 48/80 and N-(6-aminohexyl)-1
naphthalenesulfonamide (W-7), inhibited the release of NCA in response to a
variety of endotoxin concentrations. Lithium chloride, an inositol turnover
inhibitor, inhibited the release of NCA in response to both ETX and OZ, but
less attenuation was observed in the response to OZ. A protein kinase C
inhibitor, dihydrosphingosine, inhibited the release of NCA in response to
both ETX and OZ. Finally, A23187 and PMA stimulated the release of NCA and
[3H]arachidonic acid independently and additively. These data suggest that
the release of NCA from BECs in response to OZ may be predominantly
mediated by inositol turnover and protein kinase C and that the release of
NCA in response to ETX may be regulated by calcium influx and calcium
release from intracellular storage sites, calcium-calmodulin activation,
inositol turnover, and protein kinase C activation. Protein kinase C
augmented the release of NCA and [3H]arachidonic acid independent of and in
combination with calcium. These results may suggest the calcium and protein
kinase C dependency of the release of NCA from BECs.