No abstract

There is an unmet need in severe asthma where approximately 40% of patients exhibit poor β-agonist responsiveness, suffer daily symptoms and show frequent exacerbations. Antagonists of the Ca 2+ -activated Cl − channel, TMEM16A, offers a new mechanism to bronchodilate airways and block the multiple contractiles operating in severe disease. To identify TMEM16A antagonists we screened a library of ∼580,000 compounds. The anthelmintics niclosamide, nitazoxanide, and related compounds were identified as potent TMEM16A antagonists that blocked airway smooth muscle depolarization and contraction. To evaluate whether TMEM16A antagonists resist use- and inflammatory-desensitization pathways limiting β-agonist action, we tested their efficacy under harsh conditions using maximally contracted airways or airways pretreated with a cytokine cocktail. Stunningly, TMEM16A antagonists fully bronchodilated airways, while the β-agonist isoproterenol showed only partial effects. Thus, antagonists of TMEM16A and repositioning of niclosamide and nitazoxanide represent an important additional treatment for patients with severe asthma and COPD that is poorly controlled with existing therapies. It is of note that drug repurposing has also attracted wide interest in niclosamide and nitazoxanide as a new treatment for cancer and infectious disease. For the first time we identify TMEM16A as a molecular target for these drugs and thus provide fresh insights into their mechanism for the treatment of these disorders in addition to respiratory disease.

The lymphocyte-specific kinase (Lck) is a cytoplasmic tyrosine kinase of the Src family expressed in T cells and natural killer (NK) cells. Genetic evidence in both mice and humans demonstrates that Lck kinase activity is critical for signaling mediated by the T cell receptor (TCR), which leads to normal T cell development and activation. Selective inhibition of Lck is expected to offer a new therapy for the treatment of T-cell-mediated autoimmune and inflammatory disease. Screening of our kinase-preferred collection identified aminoquinazoline 1 as a potent, nonselective inhibitor of Lck and T cell proliferation. In this report, we describe the synthesis and structure-activity relationships of a series of novel aminoquinazolines possessing in vitro mechanism-based potency. Optimized, orally bioavailable compounds 32 and 47 exhibit anti-inflammatory activity (ED(50) of 22 and 11 mg/kg, respectively) in the anti-CD3-induced production of interleukin-2 (IL-2) in mice.

Asthma is a heterogeneous disease characterized by airway inflammation and hyperreactivity. IL-17 receptor A (IL-17RA) is a shared receptor subunit required for activity of IL-17 family cytokines, including IL-17A and IL-25. IL-17A and IL-25 induce different proinflammatory responses, and concentrations are elevated in subjects with asthma. However, the individual contributions of IL-17A and IL-25 to disease pathogenesis are unclear. We explored proinflammatory activities of the IL-17 pathway in models of pulmonary inflammation and assessed its effects on contractility of human bronchial airway smooth muscle. In two mouse models, IL-17RA, IL-17RB, or IL-25 blockade reduced airway inflammation and airway hyperreactivity. Individually, IL-17A and IL-25 enhanced contractility of human bronchial smooth muscle induced by methacholine or carbachol. IL-17A had more pronounced effects on methacholine-induced contractility in bronchial rings from donors with asthma compared with donors without asthma. Blocking the IL-17 pathway via IL-17RA may be a useful therapy for some patients with asthma by reducing pulmonary inflammation and airway hyperreactivity.

Structure-based rational design led to the synthesis of a novel series of potent PI3K inhibitors. The optimized pyrrolopyridine analogue 63 was a potent and selective PI3Kβ/δ dual inhibitor that displayed suitable physicochemical properties and pharmacokinetic profile for animal studies. Analogue 63 was found to be efficacious in animal models of inflammation including a keyhole limpet hemocyanin (KLH) study and a collagen-induced arthritis (CIA) disease model of rheumatoid arthritis. These studies highlight the potential therapeutic value of inhibiting both the PI3Kβ and δ isoforms in the treatment of a number of inflammatory diseases.