The metabolite alpha-ketoglutarate inhibits vascular calcification partially through modulation of the TET2/NLRP3 inflammasome signaling pathway

Abstract

Introduction: Vascular calcification is prevalent in chronic kidney disease (CKD), but existing medical treatments fail to achieve satisfactory therapeutic effects. Vascular calcification is now recognized as an active multifactorial process involving diverse mechanisms. Alpha-ketoglutarate (AKG), an intermediate in tricarboxylic acid cycle, has been demonstrated to extend lifespan and ameliorate age-related osteoporosis. However, whether AKG inhibits vascular calcification remains unknown.

Methods: Here, mineral deposition was studied with AKG treatment in rodent and human vascular smooth muscle cells (VSMCs) under osteogenic conditions in vivo and in vitro.

Results: AKG treatment remarkably ameliorated calcification of rat and human arterial rings ex vivo and aortic calcification in CKD rats and mice. Mechanistically, AKG treatment upregulated DNA demethylase ten-eleven translocation 2 (TET2) expression during vascular calcification. Knockdown of TET2 by siRNA and pharmacological inhibition of TET2 by Bobcat339 promoted vascular calcification in rat VSMCs. Bobcat339 also enhanced rat aortic ring calcification. Conversely, TET2 overexpression ameliorated vascular calcification in rat VSMCs, rat aortic rings and CKD rats. Furthermore, VSMC-specific TET2 deficiency promoted aortic calcification in CKD mice. Both TET2 siRNA and Bobcat339 independently counteracted the inhibitory effect of AKG on vascular calcification of rat VSMCs. Inhibitory effect of AKG administration on vascular calcification was reduced in TET2 knockout mice. TET2 overexpression reduced the levels of the NLRP3 inflammasome pathway, cleaved Caspase-1 and IL-1β protein expression in VSMCs and NLRP3 agonist Nigericin-induced cell calcification.

Conclusions: Our study demonstrate that AKG attenuates vascular calcification partially via upregulation of TET2 and inhibition of NLRP3 inflammasome, indicating the critical role of epigenetic modifier in vascular calcification. Modulation of TET2 may become a promising strategy for the treatment of vascular calcification.

Keywords: DNA demethylation; NLRP3 inflammasome; TET2; chronic kidney disease; vascular calcification; α-ketoglutarate.