Influence of tart cherry juice on airway biomarkers of inflammation and oxidative stress following a 42.2km trail run

Introduction Tart cherry juice (CJ) has been shown to alleviate the development of respiratory symptoms following a Marathon (Dimitriou et al., 2015) by possibly reducing exercise-induced airway inflammation (Verges et al., 2005). Therefore, this study examined the effects of CJ supplementation before and following a 42.2km trail run on biomarkers of airway inflammation and oxidative stress. Methods Nineteen recreational runners were randomly assigned to either consumption of CJ or placebo (PL) (age 39 ? 8 years; height 1.75 ? 0.7 m; mass 71.9 ? 8.2 kg; completion time 210 ? 25 min), from 4 days prior to 48h following a 42.2km trail run. Fractional exhaled nitric oxide (FeNO) and hypertonic inhalation-induced sputum (IS) samples were measured immediately before and after the run and then 24h and 48h post run. Both, FeNO and IS are non-invasive methods that can determine the type and severity of airway inflammation. Induced sputum samples were analysed for biomarkers of: a) inflammation (CD163; CD3E; CD44; CD62E; CD66E; Elastase and Interleukin-6 (IL-6)) and b) oxidative stress (protein carbonyls (PC) and superoxide dismutases (SOD)). The percentage of markers expressed on the surface of activated cells was determined using flow cytometry and the remaining biomarkers (IL-6; PC and SOD) were analysed using enzyme-linked immunosorbent assays (ELISA). Data were analysed using magnitude based inferences and results are reported as factor changes. Results Compared to PL, CJ was beneficial for changes in CD163 (B-post 1.11 v 0.60, likely moderate; B-48h 1.60 v 0.75, very likely moderate), CD44 (B-48h 1.18 v 0.59, likely moderate), CD62E (B-post 1.08 v 0.69, likely small), CD66E (B-post 0.91 v 0.52, likely moderate; B-48h 1.03 v 0.67, likely small), IL-6 (B-48h 1.32 v 0.83, possible small) and SOD (B-post 1.01 v 0.77, likely small; B-24h 1.14 v 0.80, likely small; B-48h 0.96 v 0.70, likely small). However, CJ was harmful for changes in FENO (B-post 1.09 v 1.28, possible trivial; B-24h 1.04 v 1.21, possible small; B-48h 1.11 v 1.25, possible small) and PC (B-post 1.07 v 1.41, possible small; B-24h 0.99 v 1.22, possible small; B-48h 1.11 v 1.43, possible small). All other effects were unclear. Conclusion Airway inflammation biomarkers were decreased in the cherry juice group, whereas an increase was observed in the placebo group. However, cherry juice led to greater increases in FENO and PC compared to placebo. Cherry juice was beneficial for limiting exercise-induced airway inflammation