ABSTRACT
Toll-like receptor (TLR) 7 and TLR8 are transmembrane receptors that recognize single-stranded RNA. Activation of these receptors results in immune cell stimulation and inflammatory cytokine production, which is normally a protective host response. However, aberrant activation of TLR7/8 is potentially pathogenic and linked to progression of certain autoimmune diseases such as lupus. Thus, we hypothesize that an inhibitor that blocks TLR7/8 would be an effective therapeutic treatment. Prior efforts to develop inhibitors of TLR7/8 have been largely unsuccessful as a result of the challenge of producing a small-molecule inhibitor for these difficult targets. Here, we report the characterization of M5049 and compound 2, molecules which were discovered in a medicinal chemistry campaign to produce dual TLR7/8 inhibitors with drug-like properties. Both compounds showed potent and selective activity in a range of cellular assays for inhibition of TLR7/8 and block synthetic ligands and natural endogenous RNA ligands such as microRNA and Alu RNA. M5049 was found to be potent in vivo as TLR7/8 inhibition efficaciously treated disease in several murine lupus models and, interestingly, was efficacious in a disease context in which TLR7/8 activity has not previously been considered a primary disease driver. Furthermore, M5049 had greater potency in disease models than expected based on its in vitro potency and pharmacokinetic/pharmacodynamic properties. Because of its preferential accumulation in tissues, and ability to block multiple TLR7/8 RNA ligands, M5049 may be efficacious in treating autoimmunity and has the potential to provide benefit to a variety of patients with varying disease pathogenesis. SIGNIFICANCE STATEMENT: This study reports discovery of a novel toll-like receptor (TLR) 7 and TLR8 inhibitor (M5049); characterizes its binding mode, potency/selectivity, and pharmacokinetic and pharmacodynamic properties; and demonstrates its potential for treating autoimmune diseases in two mouse lupus models. TLR7/8 inhibition is unique in that it may block both innate and adaptive autoimmunity; thus, this study suggests that M5049 has the potential to benefit patients with autoimmune diseases.
Subject(s)
Autoimmunity/drug effects , Drug Discovery , Toll-Like Receptor 7/antagonists & inhibitors , Toll-Like Receptor 8/antagonists & inhibitors , Animals , Female , Gene Expression Regulation/drug effects , HEK293 Cells , Humans , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/metabolism , Mice , Mice, Inbred C57BL , Models, Molecular , Protein Conformation , Toll-Like Receptor 7/chemistry , Toll-Like Receptor 7/metabolism , Toll-Like Receptor 8/chemistry , Toll-Like Receptor 8/metabolismABSTRACT
The P2X7 receptor (P2X7R) plays an important role in diverse conditions associated with tissue damage and inflammation, suggesting that the human P2X7R (hP2X7R) is an attractive therapeutic target. In the present study, the synthesis and structure-activity relationship (SAR) of a novel series of quinoline derivatives as P2X7R antagonists are described herein. These compounds exhibited mechanistic activity (YO PRO) in an engineered HEK293 expressing hP2X7R as well as a functional response (IL-1ß) in human THP-1 (hTHP-1) cellular assays. Compound 19 was identified as the most promising compound in this series with excellent cellular potency, low liver microsomal clearance, good permeability and low efflux ratio. In addition, this compound also displayed good pharmacokinetic properties and acceptable brain permeability (Kp,uu of 0.37).
