Chemotactic 5-oxo-eicosatetraenoic acids induce oxygen radical production, Ca2+-mobilization, and actin reorganization in human eosinophils via a pertussis toxin-sensitive G-protein.
The arachidonic acid metabolites 5-oxo-[6E,8Z,11Z,14Z]-eicosatetraen oic acid (5oETE) and 5-oxo-15-hydroxy-[6E,8Z,11Z,13E]-eicosatetrae noi c acid (5oHETE) are potent eosinophil chemotaxins. Here, the activation profile of 5-oxo-eicosanoids in eosinophils was further characterized and compared to other eosinophil activators such as complement fragment C5a (C5a), platelet-activating factor (PAF), interleukin-5 (IL-5), and phorbol ester (PMA). Flow cytometric studies revealed a rapid and transient actin polymerization upon stimulation by both 5-oxo-eicosanoids. Desensitization studies using actin polymerization as the parameter indicated cross-desensitization between the two 5-oxo-eicosanoids but revealed no interference with the response to other chemotaxins. Fluorescence measurements with Fura-2-labeled eosinophils in the presence of EGTA indicated Ca2+-mobilization from intracellular stores by 5oETE and 5oHETE. Both 5-oxo-eicosanoids stimulated the production of reactive oxygen metabolites as demonstrated by lucigenin-dependent chemiluminescence, superoxide dismutase-inhibitable cytochrome C reduction, and flow cytometric dihydrorhodamine-123 analysis. At optimal concentrations the changes induced by 5-oxo-eicosanoids were comparable to those obtained by C5a and PAF, whereas IL-5 and PMA induced only a restricted pattern of cell responses. Cell responses elicited by 5-oxo-eicosanoids were inhibited by pertussis toxin, indicating coupling of the putative 5-oxo-eicosanoid-receptor to G-proteins. These results indicate that 5-oxo-eicosanoids are stong activators of eosinophils with comparable biologic activity to the eosinophil chemotaxins C5a and PAF. These findings point to a role of 5-oxo-eicosanoids in the pathogenesis of eosinophilic inflammation as chemotaxins as well as activators of pro-inflammatory activities.
Czech
W
W
Department of Dermatology, University of Freiburg, Germany.
Barbisch
M
M
Tenscher
K
K
Schöpf
E
E
Schröder
J M
JM
Norgauer
J
J
D000199:Actins / Q000737:chemistry; D001095:Arachidonic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002630:Chemotactic Factors / Q000494:pharmacology*; D004804:Eosinophils / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D037342:Pertussis Toxin; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016897:Respiratory Burst / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D000199:Actins; D001095:Arachidonic Acids; D002630:Chemotactic Factors; D017382:Reactive Oxygen Species; D010566:Virulence Factors, Bordetella; C080828:5-oxo-6,8,11,14-eicosatetraenoic acid; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium