Extracellular PBEF/NAMPT/visfatin activates pro-inflammatory signalling in human vascular smooth muscle cells through nicotinamide phosphoribosyltransferase activity

Abstract

Aims/hypothesis Extracellular pre-B cell colony-enhancing factor/nicotinamide phosphoribosyltransferase/visfatin (ePBEF/NAMPT/visfatin) is an adipocytokine, whose circulating levels are enhanced in metabolic disorders, such as diabetes mellitus and obesity. Here, we explored the ability of ePBEF/NAMPT/visfatin to promote vascular inflammation, as a condition closely related to atherothrombotic diseases. We specifically studied the ability of PBEF/ NAMPT/visfatin to directly activate pathways leading to inducible nitric oxide synthase (iNOS) induction in cultured human aortic smooth muscle cells, as well as the mechanisms involved. Methods iNOS levels and extracellular signal-regulated kinase (ERK) 1/2 activity were determined by western blotting. Nuclear factor (NF)-κB activity was assessed by electrophoretic mobility shift assay. Results ePBEF/NAMPT/visfatin (10-250 ng/ml) induced iNOS in a concentration-dependent manner. At a submaximal concentration (100 ng/ml), ePBEF/NAMPT/visfatin time-dependently enhanced iNOS levels up to 18 h after stimulation. Over this time period, ePBEF/NAMPT/visfatin elicited a sustained activation of NF-κB and triggered a biphasic ERK 1/2 activation. By using the respective ERK 1/2 and NF-κB inhibitors, PD98059 and pyrrolidine dithiocarbamate, we established that iNOS induction by ePBEF/NAMPT/visfatin required the consecutive upstream activation of ERK 1/2 and NF-κB. The pro-inflammatory action of ePBEF/NAMPT/visfatin was not prevented by insulin receptor blockade. However, exogenous nicotinamide mononucleotide, the product of NAMPT activity, mimicked NF-κB activation and iNOS induction by ePBEF/NAMPT/visfatin, while the NAMPT inhibitor APO866 prevented the effects of ePBEF/NAMPT/visfatin on iNOS and NF-κB. Conclusions/interpretation Through its intrinsic NAMPT activity, ePBEF/NAMPT/visfatin appears to be a direct contributor to vascular inflammation, a key feature of atherothrombotic diseases linked to metabolic disorders.

Visfatin/PBEF/Nampt induces EMMPRIN and MMP-9 production in macrophages via the NAMPT-MAPK (p38, ERK1/2)-NF-κB signaling pathway

“…In endothelial cells, visfatin has ben shown to up-regulate the monocyte chemoattractant protein-1 and MMP-9 production (22)(23)(24). In smooth muscle cells, visfatin has been found to induce production of the pro-inflammatory factor, iNOS (10). This study demonstrates herein that visfatin induces EMMPRIN and MMP-9 in macrophages.…”

“…It has been demonstrated that visfatin up-regulates iNOS via the ERK1/2-NF-κB pathway in smooth muscle cells (10). Liu et al have reported that p38 and ERK1/2 phosphorylation is required in the monocyte chemotactic protein-1 and interleukin-6 inductions in endothelial cells (25).…”

“…Wang et al (27) have reported that visfatin stimulates vascular smooth muscle cell proliferation via the NMN-mediated ERK1/2 and p38 signaling. In a recent study, Romacho et al (10) have shown that NAMPT activity is involved in visfatin's pro-inflammatory action in smooth muscle cells. Our findings are in line with these reports.…”

“…After being starved with 0.3% FBS for 12 h, macrophage cells were stimulated with different concentrations of visfatin (0, 50, 100, 200, 400 ng/ml) or NMN (100 µmol/l) (10). cells were also treated with visfatin (200 ng/ml) for different times (0, 5, 10, 15, 30, 60 min).…”

The Role of Vistafin in Diabetes-Induced Impairment of Endothelial Repair System

“…Probably it may suggest that increased circulating level of Vistafin/NAMT is compensating response to mitigate EPC mobbing and differentiation through the NFkappaB pathway and to attenuate vascular reparation [26][27][28]. It is worth noting that vistafin/NAMT is able to mediate several biological actions on endothelial directly via EPC differentiation and indirectly involving in vascular reparation vascular smooth muscle cells, metalloproteinases and growth factors [29,30]. The Figure is presented principal schema explained the role of vistafin/NAMT in endothelial repair.…”