Small molecule targeting of the STAT5/6 Src homology 2 (SH2) domains to inhibit allergic airway disease

J Morgan Knight,Pijus Mandal,Pietro Morlacchi,Garbo Mak,Evan Li,Matthew Madison,Cameron Landers,Brandon Saxton,Ed Felix,Brian Gilbert,Joel Sederstrom,Atul Varadhachary,Melissa M Singh,Dev Chatterjee,David B Corry,John S Mcmurray

doi:10.1074/jbc.ra117.000567

Abstract

Asthma is a chronic inflammatory disease of the lungs and airways and one of the most burdensome of all chronic maladies. Previous studies have established that expression of experimental and human asthma requires the IL-4/IL-13/IL-4 receptor α (IL-4Rα) signaling pathway, which activates the transcription factor STAT6. However, no small molecules targeting this important pathway are currently in clinical development. To this end, using a preclinical asthma model, we sought to develop and test a small-molecule inhibitor of the Src homology 2 domains in mouse and human STAT6. We previously developed multiple peptidomimetic compounds on the basis of blocking the docking site of STAT6 to IL-4Rα and phosphorylation of Tyr641 in STAT6. Here, we expanded the scope of our initial in vitro structure-activity relationship studies to include central and C-terminal analogs of these peptides to develop a lead compound, PM-43I. Conducting initial dose range, toxicity, and pharmacokinetic experiments with PM-43I, we found that it potently inhibits both STAT5- and STAT6-dependent allergic airway disease in mice. Moreover, PM-43I reversed preexisting allergic airway disease in mice with a minimum ED50 of 0.25 μg/kg. Of note, PM-43I was efficiently cleared through the kidneys with no long-term toxicity. We conclude that PM-43I represents the first of a class of small molecules that may be suitable for further clinical development against asthma.

Highlights

Asthma is a chronic inflammatory disease of the lungs and airways and one of the most burdensome of all chronic maladies
Asthma is a chronic inflammatory disease of the lungs and airways that is marked by exaggerated airway-constrictive responses against diverse provocative challenges; accumulation of mucus and fibrin plugs in the airway that further compromise airflow; airway and systemic eosinophilia; T helper type 2 (TH2) cells and innate lymphoid cells type 2 (ILC2) that secrete the cytokines interleukin-4 (IL-4), IL-5, and IL-13; and vigorous IgE antibody responses [1,2,3]
To examine the importance of the central (Tle-Pro) scaffold on signal transducer and activator of transcription 6 (STAT6) affinity, we synthesized a series of conformationally constrained dipeptides (Fig. 1a)

Summary

Introduction

Asthma is a chronic inflammatory disease of the lungs and airways and one of the most burdensome of all chronic maladies. No small molecules targeting this important pathway are currently in clinical development. Conducting initial dose range, toxicity, and pharmacokinetic experiments with PM-43I, we found that it potently inhibits both STAT5- and STAT6-dependent allergic airway disease in mice. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We dedicate this manuscript to the memory of John S. The development of asthma is complex and is initiated in part by airway epithelial cells that recognize exogenous antigen or pathogens through pattern recognition receptors. Airway epithelial cells secrete the inflammatory cytokines IL-25, IL-33, and TSLP [1, 2] to promote ILC2 recruitment and enhance dendritic cell luminal sampling, migration to lymph nodes, and antigen presentation to initiate B and T cell activation (1, 6 – 8)

Results

Discussion

Conclusion