Histamine up-regulates phosphodiesterase 4 activity and reduces prostaglandin E2-inhibitory effects in human neutrophils.
OBJECTIVE
To investigate whether histamine produces up-regulation of phosphodiesterase (PDE) activity with functional consequences in human peripheral blood neutrophils.


METHODS
PDE activity was studied by a radioisotopic method following anion-exchange chromatography. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for detection of mRNA transcripts of PDE4 subtypes. Cyclic AMP (cAMP) levels were measured by enzyme-immunoassay, and superoxide generation by cytochrome c reduction.


METHODS
Neutrophils were incubated for 4 h with histamine (1 microM).


RESULTS
PDE4 was the only isoenzyme activity increased in treated neutrophils. Kinetic analysis showed a approximately 1.5-fold increase in Vmax without alteration of Km values. cAMP content in treated cells was higher than resting values (0.52+/-0.07 vs. 2.75+/-0.31 pmol/10(6) cells). RT-PCR showed increased expression of mRNA transcripts for PDE4B in histamine-treated cells. Functionally, up-regulation of PDE4 reduced the inhibition by prostaglandin E2 of zymosan-induced superoxide generation.


CONCLUSIONS
Histamine up-regulates PDE4 activity and produces heterologous desensitisation of human neutrophils.
Dasí
F J
FJ
Departament de Farmacologia, Facultat de Medicina i Odontologia, Universitat de València, Spain.
Ortiz
J L
JL
Cortijo
J
J
Morcillo
E J
EJ
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D015232:Dinoprostone / Q000494:pharmacology*; D006632:Histamine / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D009895:Opsonin Proteins / Q000494:pharmacology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D013481:Superoxides / Q000378:metabolism; D014158:Transcription, Genetic; D015054:Zymosan / Q000494:pharmacology
D009895:Opsonin Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D013481:Superoxides; D006632:Histamine; D015054:Zymosan; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C517360:PDE4B protein, human; D015232:Dinoprostone