The small protein Bv8, isolated from the amphibian skin, belongs to a novel family of secreted proteins linked to several biological effects. We describe the expression of Bv8/prokineticins and their receptors in mouse macrophages, and characterize their proinflammatory activities.
The rodent analogue of Bv8, prokineticin-2, is expressed by macrophages, as well as its G-protein-coupled receptor prokineticin receptor (PKR-1 and PKR-2). PKR-1 is expressed more abundantly.
Bv8 induces potent chemotaxis of macrophages at concentrations as low as 10−12 M.
It stimulates lipopolysaccharide-induced production of the proinflammatory cytokines IL-1 and IL-12, reducing that of the anti-inflammatory cytokine IL-10. The effects are observed starting at the very low concentration of 10−11 M.
Effects on chemotaxis and cytokine are not pertussis-toxin sensitive, but are completely prevented by addition of the phospholipase inhibitor U73122, suggesting a Gq protein is involved in the Bv8-induced effects.
Studies in PKR-1 knockout mice indicate that all the activities exerted by Bv8 on macrophages are mediated by the PKR-1 receptor.
In conclusion, Bv8 appears to be able to induce the macrophage to migrate and to acquire a proinflammatory phenotype.
British Journal of Pharmacology (2006) 147, 225–234. doi:10.1038/sj.bjp.0706467