Severe asthma remains poorly understood and treated. Nearly half of severe asthma patients have little evidence for traditional IgE mediated allergy but strong evidence for a mixed adaptive immune-inflammatory process refractory to corticosteroids (CS). Published data from our group show increased interferon gamma (IFN?)/Th1 pathway activation at the protein and mRNA level in bronchoalveolar lavage (BAL) cells in 70% of patients with severe asthma, commonly associated with low level Type-2 pathway activation. This complex immune process associates with increased expression of the innate-responding cytokine IL-27 enhanced nitro-oxidative stress and low IL-10 protein levels (Project 1). In vitro, combination these cytokines on primary human airway epithelial cells (HAECs) augments nitro-oxidative stress and inflammatory pathways through enhanced activation of STAT1 and diminished activation of STAT3, contributing to nitro-oxidative stress and persistent inflammation. Based on this background, we hypothesize that active Type- 1 and -2 immune pathways, in association with enhanced IL- 27, alter the STAT1 and 3 activation balance in the airway epithelium leading to augmented nitro-oxidatvie stress, worsened inflammation and the presence of a poorly CS responsive disease. To address this hypothesis, 3 specific aims are proposed as follows:
Aim 1. Establish in human participants that Type-1 immunity combined with Type-2 immune processes identifies a molecular phenotype associated with severe poorly CS responsive asthma and that the presence of IL-27 further worsens the phenotype.
Aim 2. Identify the combined effect of Type-1 and -2 cytokines, in the presence/absence of IL-27, on HAEC phenotype in vitro. Determine the role of STAT1/STAT3 balance and nitro-oxidative stress on these effects and Aim 3. Determine the CS responsiveness of the Type-1/-2 epithelium, in the presence and absence of IL-27 and whether IL-10 or anti-oxidant approaches can improve the CS responsiveness. This proposal focuses on human samples/disease using hypothesis driven and unbiased (?omics?) approaches and mechanistic cell culture work integrated with mouse models in Project 1. These studies should identify novel pathways at the intersection of innate and adaptive immunity to better define and characterize severe asthma and its phenotypes, as well as to provide new targets for the therapy.
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