ABSTRACT
A High-Throughput Screening (HTS) campaign identified a fundamentally new mGlu7 NAM chemotype, based on an ethyl-8-methoxy-4-(4-phenylpiperazin-1-yl)quinolone carboxylate core. The initial hit, VU0226390, was a potent mGlu7 NAM (IC50 = 647 nM, 6% L-AP4 min) with selectivity versus the other group III mGlu receptors (>30 µM vs. mGlu4 and mGlu8). A multi-dimensional optimization effort surveyed all regions of this new chemotype, and found very steep SAR, reminiscent of allosteric modulators, and unexpected piperazine mimetics (whereas classical bioisosteres failed). While mGlu7 NAM potency could be improved (IC50s ~ 350 nM), the necessity of the ethyl ester moiety and poor physiochemical and DMPK properties precluded optimization towards in vivo tool compounds or clinical candidates. Still, this hit-to-lead campaign afforded key medicinal chemistry insights and new opportunities.
Subject(s)
Receptors, Metabotropic Glutamate/antagonists & inhibitors , Allosteric Regulation/drug effects , Dose-Response Relationship, Drug , High-Throughput Screening Assays , Humans , Molecular Structure , Receptors, Metabotropic Glutamate/metabolism , Structure-Activity RelationshipABSTRACT
Herein, we report the discovery of a new, orally bioavailable and CNS-penetrant metabotropic glutamate receptor 7 (mGlu7) negative allosteric modulator (NAM) that achieves exposure in cerebral spinal fluid (CSF) 2.5× above the in vitro IC50 at minimum effective doses (MEDs) of 3 mg/kg in preclinical anxiety models.
Subject(s)
Anti-Anxiety Agents/pharmacology , Benzamides/pharmacology , Brain/metabolism , Receptors, Metabotropic Glutamate/metabolism , Triazoles/pharmacology , Allosteric Regulation , Animals , Anti-Anxiety Agents/chemical synthesis , Anti-Anxiety Agents/chemistry , Benzamides/chemical synthesis , Benzamides/chemistry , Drug Discovery , Male , Mice, Inbred C57BL , Molecular Structure , Rats, Sprague-Dawley , Structure-Activity Relationship , Triazoles/chemical synthesis , Triazoles/chemistryABSTRACT
BACKGROUND: Respiratory syncytial virus (RSV) is a major health care burden with a particularly high worldwide morbidity and mortality rate among infants. Data suggest that severe RSV-associated illness is in part caused by immunopathology associated with a robust type 2 response. OBJECTIVE: We sought to determine the capacity of RSV infection to stimulate group 2 innate lymphoid cells (ILC2s) and the associated mechanism in a murine model. METHODS: Wild-type (WT) BALB/c, thymic stromal lymphopoietin receptor (TSLPR) knockout (KO), or WT mice receiving an anti-TSLP neutralizing antibody were infected with the RSV strain 01/2-20. During the first 4 to 6 days of infection, lungs were collected for evaluation of viral load, protein concentration, airway mucus, airway reactivity, or ILC2 numbers. Results were confirmed with 2 additional RSV clinical isolates, 12/11-19 and 12/12-6, with known human pathogenic potential. RESULTS: RSV induced a 3-fold increase in the number of IL-13-producing ILC2s at day 4 after infection, with a concurrent increase in total lung IL-13 levels. Both thymic stromal lymphopoietin (TSLP) and IL-33 levels were increased 12 hours after infection. TSLPR KO mice did not mount an IL-13-producing ILC2 response to RSV infection. Additionally, neutralization of TSLP significantly attenuated the RSV-induced IL-13-producing ILC2 response. TSLPR KO mice displayed reduced lung IL-13 protein levels, decreased airway mucus and reactivity, attenuated weight loss, and similar viral loads as WT mice. Both 12/11-19 and 12/12-6 similarly induced IL-13-producing ILC2s through a TSLP-dependent mechanism. CONCLUSION: These data demonstrate that multiple pathogenic strains of RSV induce IL-13-producing ILC2 proliferation and activation through a TSLP-dependent mechanism in a murine model and suggest the potential therapeutic targeting of TSLP during severe RSV infection.
