Regulation by CRAMP of the responses of murine peritoneal macrophages to extracellular ATP

• Published in: Biochimica et biophysica acta 2010-03, Vol.1798 (3), p.569-578
• Main Authors: Seil, Michèle, Kabré, Elie, Nagant, Carole, Vandenbranden, Michel, Fontanils, Unai, Marino, Aida, Pochet, Stéphanie, Dehaye, Jean-Paul
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - pharmacology; Animals; Antimicrobial Cationic Peptides; Antimicrobial peptide; Calcium - metabolism; Cathelicidins - chemistry; Cathelicidins - pharmacology; Ethidium - metabolism; Extracellular Space - drug effects; Extracellular Space - metabolism; Interleukin-1beta - metabolism; Ion Channel Gating - drug effects; Ion Channels - metabolism; Ivermectin; Macrophages, Peritoneal - drug effects; Macrophages, Peritoneal - metabolism; Male; Mice; Mice, Knockout; Oleic Acid - metabolism; P2X 7-KO mice; Potassium - metabolism; Protein Structure, Secondary; Purinergic receptor; Reactive Oxygen Species - metabolism; Receptors, Formyl Peptide - agonists; Spectrophotometry, Infrared
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2009.11.002

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-1β, 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.