Regulation by CRAMP of the responses of murine peritoneal macrophages to extracellular ATP.
Peritoneal macrophages were isolated from wild type (WT) mice and from mice invalidated for the P2X(7) receptor (KO) which had been pretreated with thioglycolate. In cells from WT mice, 1 mM ATP increased the intracellular concentration of calcium ([Ca(2+)](i)), the uptake of ethidium bromide, the production of reactive oxygen species (ROS), the secretion of IL-1beta, the release of oleic acid and of lactate dehydrogenase; it decreased the intracellular concentration of potassium ([K(+)](i)). In KO mice, ATP transiently increased the [Ca(2+)](i) confirming that the P2X(7) receptor is a major receptor of peritoneal macrophages. WKYMVm, an agonist of receptors for formylated peptides (FPR) also increased the [Ca(2+)](i) in murine macrophages. The slight increase of the [Ca(2+)](i) was strongly potentiated by ivermectin confirming the expression of functional P2X(4) receptors by murine peritoneal macrophages. CRAMP, the unique antimicrobial peptide derived from cathelin in mouse inhibited all the responses coupled to P2X(7) receptors in macrophages from WT mice. Agonists for FPR had no effect on the increase of the [Ca(2+)](i) in response to ATP. CRAMP had no effect on the increase of the [Ca(2+)](i) evoked by a combination of ATP and ivermectin in macrophages from P2X(7)-KO mice. In summary CRAMP inhibits the responses secondary to the activation of the murine P2X(7) receptors expressed by peritoneal macrophages. This inhibition is not mediated by FPR receptors and is specific since CRAMP has no effect on the response coupled to P2X(4) receptors. It can thus be concluded that the interaction between P2X(7) receptors and cathelin-derived antimicrobial peptides is species-specific, in some cases (man) positive in others (mouse) negative.
Seil
Michèle
M
Laboratoire de Chimie biologique et médicale et de Microbiologie pharmaceutique, Institut de Pharmacie C.P. 205/3, Université libre de Bruxelles, Bruxelles, Belgium.
Kabré
Elie
E
Nagant
Carole
C
Vandenbranden
Michel
M
Fontanils
Unai
U
Marino
Aida
A
Pochet
Stéphanie
S
Dehaye
Jean-Paul
JP
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D002118:Calcium / Q000378:metabolism; D054804:Cathelicidins / Q000737:chemistry / Q000494:pharmacology*; D004996:Ethidium / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects* / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019301:Oleic Acid / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D017433:Protein Structure, Secondary; D017382:Reactive Oxygen Species / Q000378:metabolism; D044042:Receptors, Formyl Peptide / Q000819:agonists; D013055:Spectrophotometry, Infrared
D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; D053583:Interleukin-1beta; D007473:Ion Channels; D017382:Reactive Oxygen Species; D044042:Receptors, Formyl Peptide; D019301:Oleic Acid; D000255:Adenosine Triphosphate; D004996:Ethidium; D011188:Potassium; D002118:Calcium