[show abstract][hide abstract] ABSTRACT: Neutrophil migration into injured tissues is invariably accompanied by pain. Bv8/prokineticin 2 (PK2), a chemokine characterized by a unique structural motif comprising five disulfide bonds, is highly expressed in inflamed tissues associated to infiltrating cells. Here, we demonstrate the fundamental role of granulocyte-derived PK2 (GrPK2) in initiating inflammatory pain and driving peripheral sensitization. In animal models of complete Freund's adjuvant-induced paw inflammation the development and duration of pain temporally correlated with the expression levels of PK2 in the inflamed sites. Such an increase in PK2 mRNA depends mainly on a marked up-regulation of PK2 gene transcription in granulocytes. A substantially lower up-regulation was also detected in macrophages. From a pool of peritoneal granulocytes, elicited in rats by oyster glycogen, we purified the GrPK2 protein, which displayed high affinity for the prokineticin receptors (PKRs) and, when injected into the rat paw, induced hypersensitivity to noxious stimuli as the amphibian prokineticin Bv8 did. Mice lacking PKR1 or PKR2 developed significantly less inflammation-induced hyperalgesia in comparison with WT mice, confirming the involvement of both PKRs in inflammatory pain. The inflammation-induced up-regulation of PK2 was significantly less in pkr1 null mice than in WT and pkr2 null mice, demonstrating a role of PKR1 in setting PK2 levels during inflammation. Pretreatment with a nonpeptide PKR antagonist, which preferentially binds PKR1, dose-dependently reduced and eventually abolished both prokineticin-induced hypernociception and inflammatory hyperalgesia. Inhibiting PK2 formation or antagonizing PKRs may represent another therapeutic approach for controlling inflammatory pain.
Proceedings of the National Academy of Sciences 09/2009; 106(34):14646-51. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bv8 is a small protein secreted by frog skin. Mammalian homologues of Bv8, the prokineticins PK1 and PK2, and their G-protein coupled receptors prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2) have been identified and linked to several biological effects as gut motility, neurogenesis, angiogenesis, circadian rhythms, hematopoiesis, and nociception. Emerging evidences indicated that prokineticins are also associated with pathologies of the reproductive and nervous system, myocardial infarction, and tumorigenesis. Bv8 elicits a dose-dependent reduction in nociceptive threshold to thermal, mechanical, and chemical stimuli. The prokineticin receptors are present in a fraction of C- and Adelta-fiber neurons also expressing the vanilloid receptors, TRPV1 and TRPA1. Mice lacking PKR genes exhibit impaired Bv8-induced hyperalgesia, develop deficient responses to noxious heat, capsaicin, and protons and show reduced thermal and mechanical hypersensitivity to paw inflammation, indicating a requirement for PKR signaling in activation and sensitization of primary afferent fibers. Bv8/PK2 is highly expressed by neutrophils and other inflammatory cells and must be considered as new pronociceptive mediators in inflamed tissues. Bv8-like hyperalgesic activity was demonstrated in extracts of rat inflammatory granulocytes. Bv8 stimulates macrophage and T lymphocyte to differentiate towards an inflammatory and Th1 profile indicating that Bv8/PK2 plays a role in immunoinflammatory responses. Blockade of PKRs may represent a novel therapeutic strategy in acute and inflammatory pain conditions.
International Review of Neurobiology 02/2009; 85:145-57. · 1.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: On the basis of a Janssen's patent, we approached a new synthesis of some 1,3,5-triazin-4,6-diones as potential non peptidic prokineticin receptor antagonists, containing the following substitutions: (N(1) and N(5) link a 4-methoxybenzyl and a 4-ethylbenzyl, respectively; C(2) can link an amino-ethyl-guanidine (reference compound 1) or an ethylendiamine (2) or an amino-ethyl-amino-2-imidazoline (3). New compounds were assessed for PKR1 and PKR2 affinity. Antagonist properties were evaluated as inhibition of 1 nM Bv8-induced intracellular Ca2+ mobilization.
Journal of Medicinal Chemistry 12/2008; 51(23):7635-9. · 5.61 Impact Factor