Apabetalone (RVX-208) leads to a 57% relative risk reduction of MACE in patients with diabetes mellitus (DM) and CVD. To test whether RVX-208, an inhibitor (BETi) of epigenetic readers bromodomain extra-terminal (BET) proteins lowers CVD by affecting genes mediating monocyte adhesion to endothelial cells in response to high glucose(HG) and dietary metabolite trimethyl-amine oxide (TMAO). Cultured THP-1 monocytes, HUVEC endothelial cells and primary human hepatocytes (PHH) were exposed to varying amts of glucose and TMAO. Results showed that HG (25.6 mM) induced Very Late Antigen-4 (VLA-4) mRNA, a gene mediating THP-1 adhesion by 1.3-fold and RVX-2suppressed it >50%. BETi blocked TMAO induction of VLA-4 mRNA by >50% in THP-1. In HUVECs RVX-2abrogated HG induction of E-selectin and MYD88 mRNA by 2- and 1.3-fold, respectively and lowered TMAO induction of both mRNAs by >50%. Microbiome action on dietary phospholipids followed by hepatic flavin mono-oxygenase-3 (FMO3) processing yields TMAO. In PHH exposed for 24 hours to RVX-208, FMO3 mRNA was lower by 40% but it also suppressed a transcriptional regulator of FMO3, farnesoid X receptor (FXR). BETi for 6 hours suppressed both FXR mRNA and protein within 6 hours by >80% suggesting a direct effect of BETi on the FXR gene. Furthermore, in ChiP assays BRD4, a BET protein, dissociated immediately from FXR DNA upon exposure to RVX-208. BRD4 guides a complex containing RNA pol II along active genes, its dissociation would halt transcription of the gene.
In summary, Apabetalone inhibits HG and TMAO enhanced adhesion of THP-1 to HUVECs, this process mimics a step in CVD pathogenesis. RVX-2suppresses cellular adhesion genes; VLA-4 in THP-1 and both E-selectin plus MYD88 in HUVECs. BETi blocks TMAO activity and its production by inhibiting FXR expression, a regulator of FMO3 gene transcription. Rapid actions of BETi in dissociating BRD4 from FXR DNA suggests a direct effect of RVX-2on transcription of this gene.
L. Tsujikawa: None. E. Kulikowski: Employee; Self; Resverlogix Corp.. C. Calosing: None. S. Wasiak: Employee; Self; Resverlogix Corp. D. Gilham: Employee; Self; Resverlogix Corp.. Stock/Shareholder; Self; Resverlogix Corp.. C. Halliday: None. J.O. Johansson: Employee; Self; Resverlogix Corp., Artery Therapeutics, Inc. M. Sweeney: Employee; Self; Resverlogix Corp. N.C. Wong: Stock/Shareholder; Self; Resverlogix Corp..