Co-operative signalling through DP(1) and DP(2) prostanoid receptors is required to enhance leukotriene C(4) synthesis induced by prostaglandin D(2) in eosinophils.
OBJECTIVE
Prostaglandin (PG) D(2) has emerged as a key mediator of allergic inflammatory pathologies and, particularly, PGD(2) induces leukotriene (LT) C(4) secretion from eosinophils. Here, we have characterized how PGD(2) signals to induce LTC(4) synthesis in eosinophils.


METHODS
Antagonists and agonists of DP(1) and DP(2) prostanoid receptors were used in a model of PGD(2) -induced eosinophilic inflammation in vivo and with PGD(2) -stimulated human eosinophils in vitro, to identify PGD(2) receptor(s) mediating LTC(4) secretion. The signalling pathways involved were also investigated.


RESULTS
In vivo and in vitro assays with receptor antagonists showed that PGD(2) -triggered cysteinyl-LT (cysLT) secretion depends on the activation of both DP(1) and DP(2) receptors. DP(1) and DP(2) receptor agonists elicited cysLTs production only after simultaneous activation of both receptors. In eosinophils, LTC(4) synthesis, but not LTC(4) transport/export, was activated by PGD(2) receptor stimulation, and lipid bodies (lipid droplets) were the intracellular compartments of DP(1) /DP(2) receptor-driven LTC(4) synthesis. Although not sufficient to trigger LTC(4) synthesis by itself, DP(1) receptor activation, signalling through protein kinase A, did activate the biogenesis of eosinophil lipid bodies, a process crucial for PGD(2) -induced LTC(4) synthesis. Similarly, concurrent DP(2) receptor activation used Pertussis toxin-sensitive and calcium-dependent signalling pathways to achieve effective PGD(2) -induced LTC(4) synthesis.


CONCLUSIONS
Based on pivotal roles of cysLTs in allergic inflammatory pathogenesis and the collaborative interaction between PGD(2) receptors described here, our data suggest that both DP(1) and DP(2) receptor antagonists might be attractive candidates for anti-allergic therapies.
Mesquita-Santos
F P
FP
Laboratório de Inflamação, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Bakker-Abreu
I
I
Luna-Gomes
T
T
Bozza
P T
PT
Diaz
B L
BL
Bandeira-Melo
C
C
D000818:Animals; D002118:Calcium / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004804:Eosinophils / Q000378:metabolism; D006801:Humans; D017997:Leukotriene C4 / Q000096:biosynthesis*; D015289:Leukotrienes / Q000378:metabolism; D008297:Male; D051379:Mice; D037342:Pertussis Toxin / Q000494:pharmacology; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D015230:Prostaglandin D2 / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D015289:Leukotrienes; D011448:Prostaglandin Antagonists; D011971:Receptors, Immunologic; D011982:Receptors, Prostaglandin; C112381:cysteinyl-leukotriene; C501562:prostanoid D receptor 1, human; D017997:Leukotriene C4; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; D003545:Cysteine; D015230:Prostaglandin D2; D002118:Calcium; C036293:prostaglandin D2 receptor