Marie-Odile Roy

Oxysterols direct immune cell migration via EBI2.

Epstein–Barr virus-induced gene 2 (EBI2, also known as GPR183) is a G-protein-coupled receptor that is required for humoral immune responses; polymorphisms in the receptor have been associated with inflammatory autoimmune diseases. The natural ligand for EBI2 has been unknown. Here we describe the identification of 7α,25-dihydroxycholesterol (also called 7α,25-OHC or 5-cholesten-3β,7α,25-triol) as a potent and selective agonist of EBI2. Functional activation of human EBI2 by 7α,25-OHC and closely related oxysterols was verified by monitoring second messenger readouts and saturable, high-affinity radioligand binding. Furthermore, we find that 7α,25-OHC and closely related oxysterols act as chemoattractants for immune cells expressing EBI2 by directing cell migration in vitro and in vivo. A critical enzyme required for the generation of 7α,25-OHC is cholesterol 25-hydroxylase (CH25H). Similar to EBI2 receptor knockout mice, mice deficient in CH25H fail to position activated B cells within the spleen to the outer follicle and mount a reduced plasma cell response after an immune challenge. This demonstrates that CH25H generates EBI2 biological activity in vivo and indicates that the EBI2–oxysterol signalling pathway has an important role in the adaptive immune response.

Discovery and optimization of novel antagonists to the human neurokinin-3 receptor for the treatment of sex-hormone disorders (Part I).

Neurokinin-3 receptor (NK3R) has recently emerged as important in modulating the tonic pulsatile gonadotropin-releasing hormone (GnRH) release. We therefore decided to explore NK3R antagonists as therapeutics for sex-hormone disorders that can potentially benefit from lowering GnRH pulsatility with consequent diminished levels of plasma luteinizing hormone (LH) and correspondingly attenuated levels of circulating androgens and estrogens. The discovery and lead optimization of a novel N-acyl-triazolopiperazine NK3R antagonist chemotype achieved through bioisosteric lead change from the high-throughput screening (HTS) hit is described. A concomitant improvement in the antagonist bioactivity and ligand lipophilic efficiency (LLE) parameter were the principal guidelines in the lead optimization efforts. Examples of advanced lead analogues to demonstrate the amenability of this chemotype to achieving a suitable pharmacokinetic (PK) profile are provided as well as pharmacokinetic-pharmacodynamic (PKPD) correlations to analyze the trends observed for LH inhibition in castrated rats and monkeys that served as preliminary in vivo efficacy models.

Discovery of 3-aryl-5-acylpiperazinyl-pyrazoles as antagonists to the NK3 receptor

A series of 3-aryl-5-acylpiperazinyl-pyrazoles (e.g., 3a-b) initially identified through a high-throughput screening campaign using the aequorin Ca(2+) bioluminescence assay as novel, potent small molecule antagonists of the G protein-coupled human tachykinin NK(3) receptor (hNK3-R) is described. Preliminary profiling revealed poor plasma and metabolic stability for these structures in rodents. Further optimization efforts resulted in analogs with improved potency, stability, and pharmacokinetic properties as well as good brain permeability, for example, compounds 26 and 42. Unexpected cytotoxicity was observed in such N-Me pyrazole structures as compounds 41-42.