Background: Abnormal accumulation of senescent cells in the vessel wall leads to a compromised vascular function contributing to vascular aging. Soluble DPP4 (dipeptidyl peptidase 4; sDPP4) secretion from visceral adipose tissue is enhanced in obesity, now considered a progeric condition. sDPP4 triggers vascular deleterious effects, albeit its contribution to vascular aging is unknown. We aimed to explore sDPP4 involvement in vascular aging, unraveling the molecular pathway by which sDPP4 acts on the endothelium.
Methods: Human endothelial cell senescence was assessed by senescence-associated β-galactosidase assay, visualization of DNA damage, and expression of prosenescent markers, whereas vascular function was evaluated by myography over human dissected microvessels. In visceral adipose tissue biopsies from a cohort of obese patients, we explored several age-related parameters in vitro and ex vivo.
Results: By a common mechanism, sDPP4 triggers endothelial cell senescence and endothelial dysfunction in isolated human resistance arteries. sDPP4 activates the metabotropic receptor PAR2 (protease-activated receptor 2), COX-2 (cyclooxygenase 2) activity, and the production of TXA2 (thromboxane A2) acting over TP (thromboxane receptor) receptors (PAR2-COX-2-TP axis), leading to NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing 3) inflammasome activation. Obese patients exhibited impaired microarterial functionality in comparison to control nonobese counterparts. Importantly, endothelial dysfunction in obese patients positively correlated with greater expression of DPP4, prosenescent, and proinflammatory markers in visceral adipose tissue nearby the resistance arteries. Moreover, when DPP4 activity or sDPP4-induced prosenescent mechanism was blocked, endothelial dysfunction was restored back to levels of healthy subjects.
Conclusions: These results reveal sDPP4 as a relevant mediator in early vascular aging and highlight its capacity activating main proinflammatory mediators in the endothelium that might be pharmacologically tackled.
Keywords: cellular senescence; dipeptidyl peptidase 4; endothelium; inflammasomes; microvessels; obesity.