Pre-B Cell Colony-Enhancing Factor (PBEF/Nampt/Visfatin) Primes Neutrophils for Augmented Respiratory Burst Activity through Partial Assembly of the NADPH Oxidase

Abstract

Pre-B cell colony-enhancing factor ([PBEF] also known as Nampt/visfatin) is a pleiotropic 52-kDa cytokine-like molecule whose activity has been implicated in multiple inflammatory disease states. PBEF promotes polymorphonuclear neutrophil (PMN) proinflammatory function by inhibiting constitutive PMN apoptosis. We investigated whether PBEF activates or primes for PMN respiratory burst. We found that although PBEF did not activate respiratory burst on its own, it primed for increased reactive oxygen species generation through the NADPH oxidase. PBEF promoted membrane translocation of cytosolic NADPH oxidase subunits p40 and p47, but not p67, induced p40 phosphorylation on Thr154, and activated the small GTPase Rac. Priming, translocation, and phosphorylation were dependent on activation of p38 and ERK MAPKs, but not of PI3K. Priming by PBEF occurred independent of its NAD-generating capacity because neither nicotinamide mononucleotide or NAD could recapitulate the effects, and a specific inhibitor of PBEF, APO-866, could not inhibit priming. Taken together, these results demonstrate that PBEF can prime for PMN respiratory burst activity by promoting p40 and p47 translocation to the membrane, and this occurs in a MAPK-dependent fashion.