Distinct isoforms of protein kinase C are involved in human eosinophil functions induced by platelet-activating factor.
BACKGROUND
Platelet-activating factor (PAF) is a potent stimulator of eosinophils. Recently, treatment with a protein kinase C (PKC) inhibitor which generally inhibits PKC isoforms has been shown to modulate several eosinophil functions in distinct manners, in that PKC inhibition enhanced CD11b expression and cellular adhesion, but inhibited superoxide generation and degranulation in PAF-stimulated human eosinophils. These results suggested that distinct PKC isoforms were likely to be involved in each eosinophil function induced by PAF. We have therefore investigated whether or not the PKC isoforms involved in PAF-induced CD11b expression and superoxide generation were different.


METHODS
Human eosinophils prepared from healthy volunteers were treated with PKC inhibitors, bis-indolylmaleimide I (BisI; a general PKC inhibitor), myristoylated PKC inhibitor peptide (myr-psiPKC; a PKCalpha, beta and delta inhibitor) and rottlerin (a PKCdelta inhibitor), followed by stimulation with PAF. CD11b expression was determined using flow cytometry and superoxide generation was evaluated using a cytochrome c reduction assay.


RESULTS
BisI treatment led to enhancement of PAF-induced CD11b expression, while myr-psiPKC and rottlerin did not. In contrast, PAF-induced superoxide generation was inhibited by treatment with BisI, myr-psiPKC and rottlerin.


CONCLUSIONS
PKCalpha, beta and delta are not involved in PAF-induced CD11b expression, but PKCdelta is involved in the PAF-induced activation of superoxide anion generation.
Takizawa
Takumi
T
Department of Pediatrics, Gunma University School of Medicine, Maebashi, Gunma, Japan.
Kato
Masahiko
M
Suzuki
Masato
M
Tachibana
Atsushi
A
Motegi
Youichi
Y
Fujiu
Toru
T
Kimura
Hirokazu
H
Arakawa
Hirokazu
H
Mochizuki
Hiroyuki
H
Tokuyama
Kenichi
K
Morikawa
Akihiro
A
D000098:Acetophenones / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D039481:CD11b Antigen / Q000096:biosynthesis / Q000187:drug effects; D018821:CD18 Antigens / Q000187:drug effects / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004804:Eosinophils / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000096:biosynthesis / Q000187:drug effects; D007527:Isoenzymes / Q000145:classification / Q000187:drug effects; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000145:classification* / Q000187:drug effects*; D012016:Reference Values; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
D000098:Acetophenones; D001578:Benzopyrans; D039481:CD11b Antigen; D018821:CD18 Antigens; D004791:Enzyme Inhibitors; D016023:Integrins; D007527:Isoenzymes; D010972:Platelet Activating Factor; D013481:Superoxides; C085746:rottlerin; D011493:Protein Kinase C