Endocrine Abstracts

Aim: Cardiovascular disease is more common in individuals with diabetes mellitus and obesity. Visfatin is elevated in obesity and T2DM; and thought to be an inflammatory mediator within atherosclerotic lesions inducing gelatinase activity, contributing to plaque destabilisation. We investigated the activation of NF-κB, a well-known pro-inflammatory transcription factor, by visfatin, in Human Endothelial Cells (EC).

Research design and methods: We stably transfected EAHy926 (human) cells with a cis-reporter pNF-κB-Luc plasmid containing luciferase reporter gene linked to five repeats of NF-κB binding sites. Using luciferase reporter assay, quantitative PCR, western blotting and gelatin zymography, we studied the involvement of NF-κB signalling in gelatinase mediated vascular inflammation by visfatin; employing the NF-κB inhibitor, BAY 11-7085.

Results: Visfatin induced a significant dose dependent increase in NF-κB mediated transcriptional activity (P<0.001), with a comparable potency to TNFα, a robust inducer of NF-κB activity. Also, when transfected ECs were pre-incubated with visfatin for 16 h, followed by TNFα stimulation for 2 h revealed a significant inhibition of TNFα induced NF-κB activity (P<0.001), suggesting receptor desensitisation. Furthermore the NF-κB inhibitor, BAY 11-7085, significantly down-regulated visfatin induced MMP-2 and MMP-9 expressions at mRNA, protein and zymogen levels.

Conclusions: We were able to demonstrate that visfatin is a profound stimulator of NF-κB transcriptional activity in human ECs, also the crucial involvement of NF-κB signalling in visfatin induced activation of gelatinases-MMP-2/9. Moreover, the hypo responsiveness of NF-κB mediated transcriptional activity induced by visfatin is of importance since pro inflammatory cytokine ‘overload’ exists in obesity and T2DM suggesting an important role of visfatin in the pathogenesis of vascular inflammation.

In summary, our finding reveals a new insight into visfatin’s diverse roles in dysmetabolic states and reaffirms the emerging roles of adipokines as mediators of inflammatory response.