Effect of the S-nitrosoglutathione reductase inhibitor N6022 on bronchial hyperreactivity in asthma.

Abstract

Rationale

Patients with asthma demonstrate depletion of the endogenous bronchodilator GSNO and upregulation of GSNOR.

Objectives

An exploratory proof of concept clinical study of N6022 in mild asthma to determine the potential bronchoprotective effects of GSNOR inhibition. Mechanistic studies aimed to provide translational evidence of effect.

Methods

Fourteen mild asthma patients were treated with intravenous N6022 (5 mg) or placebo and observed for 7 days, with repeated assessments of the provocative dose of methacholine causing a 20% fall in FEV1 (methacholine PC20 FEV1), followed by a washout period and crossover treatment and observation. In vitro studies in isolated eosinophils investigated the effect of GSNO and N6022 on apoptosis.

Measurements and main results

This was a negative trial as it failed to reach its primary endpoint, which was change from baseline in methacholine PC20 FEV1 at 24 h. However, our exploratory analysis demonstrated significantly more two dose-doubling increases in PC20 FEV1 for N6022 compared with placebo (21% vs 6%, P < 0.05) over the 7-day observation period. Furthermore, a significant treatment effect was observed in the change in PC20 FEV1 from baseline averaged over the 7-day observation period (mean change: +0.82 mg/ml [N6022] from 1.34 mg/ml [baseline] vs -0.18 mg/ml [placebo] from 1.16 mg/ml [baseline], P = 0.023). N6022 was well tolerated in mild asthmatics. In vitro studies demonstrated enhanced eosinophilic apoptosis with N6022.

Conclusions

In this early phase exploratory proof of concept trial in asthma, N6022 did not significantly alter methacholine PC20 FEV1 at 24 h, but did have a treatment effect at 7 days compared to baseline. Further investigation of the efficacy of S-nitrosoglutathione reductase inhibition in a patient population with eosinophilic asthma is warranted.

Department

Description

Provenance

Citation

Published Version (Please cite this version)

10.1002/iid3.220

Scholars@Duke

Que

Loretta Georgina Que

Professor of Medicine

My research interests focus on studying the role of nitric oxide and related enzymes in the pathogenesis of lung disease, specifically that caused by nitrosative/oxidative stress. Proposed studies are performed in cell culture and applied to animal models of disease, then examined in human disease where relevant. It is our hope that by better understanding the role of NO and reactive nitrogen species in mediating inflammation, and regulating cell signaling, that we will not only help to unravel the basic mechanisms of NO related lung disease, but also provide a rationale for targeted therapeutic use of NO.


Key words: nitrosative defense, lung injury, nitric oxide

Tighe

Robert Matthew Tighe

Associate Professor of Medicine

The research focus of the Tighe laboratory is performing pulmonary basic-translational studies to define mechanisms of susceptibility to lung injury and disease. There are three principal focus areas. These include: 1) Identifying susceptibility factors and candidate pathways relevant to host biological responses to environmental pollutants such as ozone, woodsmoke and silica, 2) Defining protective and detrimental functions of lung macrophage subsets and their cross talk with the epithelium to regulate lung injury and repair, and 3) Determining the prognostic and theragnostic efficacy of 3D lung gas exchange imaging in pulmonary fibrosis using hyperpolarized 129Xenon MRI. 

  1. Susceptibility Factors for Environmental Lung Disease: In NIH funded studies the Tighe lab has been performing fully translational studies of lung responses to ozone. These include cell, rodent and human exposure studies to define mechanisms of susceptibility to exposure. By carefully dissecting these links, we will gain insight into how environmental pollutants acutely induce respiratory symptoms and exacerbate chronic lung diseases. This can lead to targeted therapeutics and/or identify susceptible populations. This includes exploration of genetic factors and also other metabolic and immunologic factors.

  2. Pulmonary Macrophage Functions and Crosstalk with Lung Epithelial Cells: The central hypothesis of this line of research is that macrophages are key regulators of the biologic responses to environmental pollutants and the development of chronic lung disease. The Tighe laboratory has pioneered the identification of novel pulmonary macrophage subsets and has defined their function in lung injury and repair. In both published work and areas of active investigation, the Tighe lab has identified macrophage subsets with unique genetic programming and function after challenges with environmental exposures such as ozone, wood smoke and silica. Since macrophages have both detrimental and protective functions, identifying these subsets offers the opportunity to understand their unique programing and function. This could allow development of targeted therapeutics that take advantage of these functions, polarize the immune responses and alleviate respiratory disease. In addition, we are focused on macrophage and epithelial crosstalk and how their combined responses regulate lung injury and repair. These studies include omics approaches with single-cell RNA sequencing, proteomics and metabolomics and lung organoids to identify unique signals between macrophages and epithelial cells. 

  3. Using Hyperpolarized 129Xenon MRI to Define Prognosis and Therapy Responses in Pulmonary Fibrosis: In industry funded studies, the Tighe lab is focused on using a novel image modality to assess prognosis and therapeutic responses in individuals with pulmonary fibrosis. Pulmonary fibrosis is a disorder of progressive scar formation in the lung that causes increased shortness of breath and persistent coughing, frequently leading to death from respiratory failure. Presently, there are limited modalities that can assess prognosis in pulmonary fibrosis and can determine which individuals are responding to therapies. To address this, the Tighe lab, in collaboration with Dr. Bastiaan Driehuys in the Department of Radiology, is using inhaled hyperpolarized 129Xenon gas MRI to define regional differences in lung gas exchange in individuals with pulmonary fibrosis. Our preliminary data suggest that baseline characteristics of 129Xenon MRI associate with pulmonary fibrosis prognosis. In addition, we observe changes in the 129Xenon MRI metrics following initiation of pulmonary fibrosis therapies. These initial observations are being confirmed in ongoing clinical trials.


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