β‐Arrestin‐biased proteinase‐activated receptor‐2 antagonist C781 limits allergen‐induced airway hyperresponsiveness and inflammation

Abstract

Background and Purpose Asthma is a heterogenous disease strongly associated with inflammation that has many different causes and triggers. Current asthma treatments target symptoms such as bronchoconstriction and airway inflammation. Despite recent advances in biological therapies, there remains a need for new classes of therapeutic agents with novel, upstream targets. The proteinase‐activated receptor‐2 (PAR2) has long been implicated in allergic airway inflammation and asthma and it remains an intriguing target for novel therapies. Here, we describe the actions of C781, a newly developed low MW PAR2 biased antagonist, in vitro and in vivo in the context of acute allergen exposure. Experimental Approach A human bronchial epithelial cell line expressing PAR2 (16HBE14o‐ cells) was used to evaluate the modulation in vitro, by C781, of physiological responses to PAR2 activation and downstream β‐arrestin/MAPK and Gq/Ca2+ signalling. Acute Alternaria alternata sensitized and challenged mice were used to evaluate C781 as a prophylactically administered modulator of airway hyperresponsiveness, inflammation and mucus overproduction in vivo. Key Results C781 reduced in vitro physiological signalling in response to ligand and proteinase activation. C781 effectively antagonized β‐arrestin/MAPK signalling without significant effect on Gq/Ca2+ signalling in vitro. Given prophylactically, C781 modulated airway hyperresponsiveness, airway inflammation and mucus overproduction of the small airways in an acute allergen‐challenged mouse model. Conclusion and Implications Our work demonstrates the first biased PAR2 antagonist for β‐arrestin/MAPK signalling. C781 is efficacious as a prophylactic treatment for allergen‐induced airway hyperresponsiveness and inflammation in mice. It exemplifies a key pharmacophore for PAR2 that can be optimized for clinical development.

Protease-Activated Receptor 2 (PAR2) expressed in sensory neurons contributes to signs of pain and neuropathy in paclitaxel treated mice

“…It is unlikely that the compound is metabolized in the liver because C781 has a long half-life in liver microsomes. Our pharmacological study should be viewed as proof of concept for the efficacy of a PAR2 antagonist that selectively blocks β-arrestin signaling downstream of the receptor for the treatment of CIPN 78 . Future development of similar PAR2 antagonists with a more favorable pharmacokinetic profile will allow for longer target coverage in vivo .…”

“…Paclitaxel was injected into the peritoneal space using a 27G ½” needle. C781 was synthesized using solid-phase synthesis as described previously 78 . C781 was injected into the peritoneal space using a 27G ½” needle at a dosage of 10 mg/kg.…”

“…To determine whether established mechanical hypersensitivity caused by PTX treatment could be reversed by PAR2 signaling inhibition we used a β-arrestin signaling biased PAR2 antagonist that we developed 78 . C781 was given by intraperitoneal injection and mechanical threshold and facial grimacing was assessed following treatment.…”

Par2-mediated responses in inflammation and regeneration: choosing between repair and damage

“…In a subsequent study, a Par2 antagonist (C391) was proven to block Par2 signaling induced by the fungi [ 20 ]. A follow-up investigation showed that the antagonist C781, when given prophylactically, alleviated airway inflammation and mucus overproduction of the small airways in an acute allergen-challenged mouse model induced by Alternaria alternata [ 108 ] .…”

“…Analyzing these reports based on the tissues in which Par2 is predominantly activated, the seeming contradictions can be resolved. When the immune system is activated, as in the cases of cockroach extract, HDM extract, Alternaria alternata, Streptococcus pneumoniae, and LPS, Par2 activation in immune cells leads to the aggravation of the asthmatic and inflammatory phenotypes [ 8 – 11 , 20 , 105 – 108 , 111 ]. These asthma and inflammatory experiments were validated by the secretion of interleukins and chemokines, inflammatory markers, the presence of different leukocyte populations in the BAL, and the amount of secreted mucus.…”