Novel Tight-Binding Inhibitory Factor-κB Kinase (IKK-2) Inhibitors Demonstrate Target-Specific Anti-Inflammatory Activities in Cellular Assays and following Oral and Local Delivery in an in Vivo Model of Airway Inflammation

Abstract

Nuclear factor-B (NF-B) is one of the major families of transcription factors activated during the inflammatory response in asthma and chronic obstructive pulmonary disease. Inhibitory factor-B kinase 2 (IKK-2) has been shown to play a pivotal role in cytokine-induced NF-B activation in airway epithelium and in disease-relevant cells. Nevertheless, the potential toxicity of specific IKK-2 inhibitors may be unacceptable for oral delivery in chronic obstructive pulmonary disease. Therefore, local delivery to the lungs is an attractive alternative that warrants further exploration. Here, we describe potent and selective small-molecule IKK-2 inhibitors [8-(5-chloro-2-(4-methylpipera- -184)] that are competitive for ATP have slow off-rates from IKK-2 and display broad in vitro anti-inflammatory activities resulting from NF-B pathway inhibition. Notably, PF-184 has been designed to have high systemic clearance, which limits systemic exposure and maximizes the effects locally in the airways. We used an inhaled lipopolysaccharide-induced rat model of neutrophilia to address whether inhibiting NF-B activation locally within the airways would show anti-inflammatory effects in the absence of systemic exposure. PHA-408, a low-clearance compound previously shown to be efficacious orally in a rodent model of arthritis, dose-dependently attenuated inhaled lipopolysaccharide-induced cell infiltration and cytokine production. Interestingly, PF-184 produced comparable dose-dependent anti-inflammatory activity by intratracheal administration and was as efficacious as intratracheally administered fluticasone propionate (fluticasone). Together, these results support the potential therapeutic utility of IKK-2 inhibition in inflammatory pulmonary diseases and demonstrate anti-inflammatory efficacy of an inhaled IKK-2 inhibitor in a rat airway model of neutrophilia.Chronic obstructive pulmonary disease (COPD) is a multifactorial chronic inflammatory disease involving the activation of many different types of inflammatory cells, including macrophages, neutrophils, lymphocytes, eosinophils, and structural cells, in the airways (Barnes, 2004b). The disease is mainly characterized by an oxidative stress (e.g., cigarette smoking)-induced pulmonary inflammation, which results in Article, publication date, and citation information can be found at

Inhaled LPS challenges in smokers: a study of pulmonary and systemic effects

“…However, there was an increase in phospho-p65 staining intensity of >20% after LPS challenge, which clearly demonstrated p65 activation. Previous studies have shown that NFkB activation is increased in the airways of COPD patients in the stable state and in sputum macrophages during exacerbations [36,37] Consequently, inhibitors of the NFkB pathway, such as IKK2 inhibitors, are being developed for the treatment of COPD [38,39].We could not detect phospho-p65 in sputum neutrophils, although we could detect total p65.This suggests that there was a technical issue with the sensitivity of phospho-p65 staining in sputum neutrophils, rather than an absence of p65 in neutrophils. Nevertheless, our findings demonstrate that NFkB activation is involved in the inflammatory response of healthy smokers due to inhaled LPS.…”

Chemical biology of inflammatory cytokine signaling

“…41,42 The phase I clinical trial of topical formulation of IMD-0354 for treatment of atopic dermatitis has been successfully completed. Other synthetic IKK inhibitors, including S1627, 43 2-benzamido-pyrimidines, 44 2-amino-3,5-diarylbenzamides, 45,46 6-aryl-7-alkoxyisoquinolines, 47 4-phenyl-7-azaindoles, 48 PHA-408 49,50 and PF-184, 50 have been reported.…”

Kinases as Novel Therapeutic Targets in Asthma and Chronic Obstructive Pulmonary Disease

“…Several IKK-b inhibitors suppressed the release of cytokines and chemokines from human airway smooth muscle and epithelial cells and were mimicked by adenovirus mediated delivery of a dominant-negative IKK-b inhibitor Newton et al, 2007). To avoid potential systemic exposure, an inhaled IKK-b inhibitor (PF-104) was developed to inhibit neutrophilic lung inflammation induced by inhaled endotoxin in mice (Sommers et al, 2009). Ainsliadimer-A is found in a Chinese herbal product that has been described as a potent and selective inhibitor of IKKa/b, thus inhibiting the classic and alternative pathways of NF-kB (Dong et al, 2015).…”