Visfatin/eNampt induces endothelial dysfunction in vivo: a role for Toll-Like Receptor 4 and NLRP3 inflammasome

Abstract

Visfatin/extracellular-nicotinamide-phosphoribosyltranferase-(enampt) is a multifaceted adipokine enhanced in type-2-diabetes and obesity. Visfatin/eNampt cause in vitro endothelial dysfunction and vascular inflammation, although whether the same effects are achieved in vivo is unknown. Toll-like receptor-4 (TLR4), a main surface pattern recognition receptor of innate immune system is a potential target for visfatin/eNampt. We studied its capacity to generate vascular dysfunction in vivo, focusing on TLR4 role and downstream activation of nod-like-receptor-protein-3 (NLRP3)-inflammasome. 4 month-old C57BL/6 mice were exposed to 7 days infusion of visfatin/eNampt, alone or together with FK 866 (Nampt enzymatic inhibitor), CLI 095 (TLR4 blocker), MCC 950 (NLRP3-inflammasome inhibitor), or anakinra (interleukin(IL)-1-receptor antagonist). Endothelial dysfunction was tested in isolated microvessels. In human umbilical endothelial cells (HUVEC), proteins related to the NLRP3inflammasome phosphorylated p-65, NLRP3, caspase-1, pro-IL-1β, and mature IL-1β were determined by Western blot, while the inflammasome related apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC-specks) was studied by immunofluorescence. Impaired endotheliumdependent relaxations were observed in isolated mesenteric microvessels from visfatin/eNamptinfused mice. This effect was attenuated by co-treatment with FK 866 or CLI 095, supporting a role for Nampt enzymatic activity and TLR4 activation. Moreover, cultured HUVEC exposed to visfatin/ eNampt showed higher expression and activation of NLRP3-inflammasome. Again, this effect relied on Nampt enzymatic activity and TLR4 activation, and it was abrogated by the inflammasome assembly blockade with MCC 950. The endothelial dysfunction evoked by visfatin/eNampt infusion in vivo was also sensitive to both MCC 950 and anakinra treatments, suggesting that the NLRP3-inflammasomedriven tissular release of IL-1β is the final mediator of endothelial damage. We conclude that Visfatin/ enampt produces in vivo vascular dysfunction in mice by a Nampt-dependent TLR4-mediated pathway, involving NLRP3-inflammasome and paracrine IL-1β. Thus, those targets may become therapeutic strategies for attenuating the adipokine-mediated vascular dysfunction associated to obesity and/or type-2-diabetes.

Visfatin: An emerging adipocytokine bridging the gap in the evolution of cardiovascular diseases

“…Recent evidence further argues that the inflammatory effects of visfatin are due to its ability to increase expression of lipoxygenase in human endothelial cells (Han et al, 2020). This is consistent with another recent report showing that visfatin induces endothelial dysfunction via NLRP3inflammasome and paracrine IL-1β signaling (Romacho et al, 2020).…”

Peripapillary Retinal Vascular Involvement in Early Post-COVID-19 Patients

“…The role of platelets in inducing or amplifying the endothelial damage in COVID-19 patients is still a matter of discussion. A low platelet count, possibly due to destruction, bone marrow infection, or autoimmune phenomena, was reported to cause a five-fold mortality rate increase in COVID-19 patients and the rates reported were very heterogeneous among the analyzed studies [ 41 , 42 ]. However, the opposite is more common in COVID-19 patients: usually the platelet count is higher than in patients with sepsis or ARDS.…”

Adipose Tissue Immunomodulation: A Novel Therapeutic Approach in Cardiovascular and Metabolic Diseases

“…Chemerin was demonstrated to promote aortic atherosclerosis by promoting NF-κB signaling and p38 MAPK phosphorylation ( 397 , 398 ). Additionally, and via the activation of NLRP3 signaling, the adipokine visfatin was shown to induce vascular endothelial dysfunction and tissue inflammation ( 399 , 400 ). Finally, resistin was demonstrated to activate the renin-angiotensin system inducing hypertension ( 401 , 402 ).…”