Obesity is an asthma comorbidity associated with increased exacerbation rates and greater healthcare utilization by mechanisms that are not explained by increases in Type 2 helper T cell (Th2)-related biomarkers of airway inflammation associated with atopic asthma. In addition to an altered immune response in the lung (Th1/Th17) obese asthmatics are also plagued by the low-grade, chronic, systemic inflammation attributed to adipocyte secretion of pro-inflammatory chemokines and cytokines. Also contributing to systemic inflammation is the uncoupling of nitric oxide synthase (NOS) by the arginine (Arg) metabolite, asymmetric dimethyl arginine (ADMA). Low Arg/ADMA ratios are correlated with increasing body mass index and the resulting lower fractional exhaled nitric oxide (FeNO). NOS uncoupling leads to low nitric oxide bioavailability and an increase in superoxide anion production, thus contributing to the overall oxidative environment. The objective of this study is to characterize the effects of the dietary supplements nitrate (NO3-) and nitrite (NO2-) (NOx) and conjugated linoleic acid (cLA) on airway hyperresponsiveness and inflammation in obese asthmatics. Epidemiological and clinical studies using NOx or cLA (individually) supplementations have reported on their benefits in relation to disease pathologies including cardiovascular disease and metabolic disorder. A recent pilot study we conducted demonstrated the formation of the electrophilic fatty acid, nitro-cLA (NO2-cLA) from NOx + cLA supplementation in healthy subjects at concentrations ~3X endogenous basal levels. Importantly, these levels are within a dose range that exerts systemic effects in preclinical animal models. This occurs because nitroalkene fatty acids mediate anti-inflammatory signaling actions via post translational modification of key transcriptional regulatory proteins and enzymes. These effects have been demonstrated with NO2-cLA in animal and cell culture models and safety has been demonstrated using a synthetic homolog nitro-oleic acid in FDA-approved phase 1 clinical trials. Since the individual dietary constituents NO3-, NO2-, and cLA are all associated with decreased risk of metabolic syndrome symptoms and NO2-cLA is a modulator of inflammation, it is hypothesized that obese asthmatics treated with NO3- + NO2- (NOx) + cLA will manifest improved FeNO and reduced airway hyperresponsiveness and inflammation. This hypothesis will be tested by pursuing two Specific Aims:
Aim 1 : Improve airway .NO bioavailability and airway hyperresponsiveness with NOx + cLA treatment.
Aim 2 : Determine if NOx + cLA reduce the systemic and airway inflammation that contributes to the obese asthmatic phenotype. FeNO and nitrosyl hemoglobin, inflammatory cytokines and chemokines, NO2-cLA, and markers of oxidative stress will be measured as well as clinical markers of asthma including airway hyperresponsiveness and the asthma control test. Positive clinical outcomes using NOx + cLA dietary supplementation provides a complementary and integrative health intervention as well as a novel therapeutic strategy for targeting the obese asthmatic pathology.
This project will determine the effects of nitrogen oxides (NOx, nitrate and nitrite) and conjugated linoleic acid (cLA) on airway hyperresponsiveness and systemic and airway-specific inflammation in obese asthmatics. These species have reported individual beneficial effects on cardiovascular function, inflammatory signaling, airway hyperresponsiveness and metabolic syndrome. In addition to their individual benefits, these species are the precursors of nitro-conjugated linoleic acid (NO2-cLA). NO2-cLA is an electrophilic nitro fatty acid with pleiotropic signaling properties and has been shown to abrogate inflammation. Obese asthmatics suffer from chronic, systemic inflammation that contributes to complications in lung function. In addition, increased body mass index is associated with nitric oxide synthase uncoupling leading to low nitric oxide bioavailability and increased formation of superoxide. This dietary supplement (NOx + cLA) approach will address obesity- derived and asthma-derived inflammation, increase nitric oxide bioavailability and reduce airway hyperresponsiveness.
|Buchan, Gregory J; Bonacci, Gustavo; Fazzari, Marco et al. (2018) Nitro-fatty acid formation and metabolism. Nitric Oxide 79:38-44|
|Woodcock, Chen-Shan Chen; Huang, Yi; Woodcock, Steven R et al. (2018) Nitro-fatty acid inhibition of triple-negative breast cancer cell viability, migration, invasion, and tumor growth. J Biol Chem 293:1120-1137|
|Hughan, Kara S; Wendell, Stacy Gelhaus; Delmastro-Greenwood, Meghan et al. (2017) Conjugated Linoleic Acid Modulates Clinical Responses to Oral Nitrite and Nitrate. Hypertension :|