Inhibition of Epigenetic Reader BET Proteins by Apabetalone Counters Inflammation in Activated Innate Immune Cells from Fabry Disease Patients Receiving ERT

Abstract

Abstract Fabry disease (FD) is a rare genetic disorder with a deficit in the degradation pathway of a glycolipid, globotriaocylceramide (Gb3). Gb3 deposits in various tissues evoke immune-mediated systemic inflammation, driving the progression of FD complications. In particular, cardiac and renal problems, leading causes of mortality in FD patients, are insufficiently managed by enzyme replacement therapy (ERT) in the long term. Here, we examined immune profiles in unstimulated peripheral blood mononuclear cells (PBMCs) from FD patients on ERT relative to untreated patients. The results showed an upregulation of the CCR2/MCP-1 axis, particularly in the presence of renal dysfunction. We also observed an increase of IL12B transcripts in unstimulated PBMCs when tracking the immune status over two years of ERT in patients with early-stage chronic kidney disease (CKD). Interestingly, pro-inflammatory responses in LPS-stimulated PBMCs were countered by apabetalone, a clinical-stage candidate that inhibits Bromodomain and Extra Terminal (BET) proteins, epigenetic readers. Apabetalone treatment dose dependently inhibited MCP-1 and IL-12 production by up to 90%. Apabetalone downregulated the transcription of other pro-inflammatory cytokines including TNF-α, IL-6 and IL-8 by 70%, 48% and 54%, respectively. Reactive oxygen species (ROS) are an indicator of oxidative damage caused by intracellular Gb3 deposits in FD patients. Apabetalone suppressed ROS levels by up to ~70% in LPS-stimulated neutrophils. Hence, apabetalone treatment may reduce pathological inflammation and oxidative stress in FD patients and thus complement ERT to optimize patient outcomes, warranting further investigation of apabetalone as a therapeutic for FD.