Flaxseed modulates inflammatory and oxidative stress biomarkers in cystic fibrosis: a pilot study.

BACKGROUND: Cystic fibrosis (CF) leads to advanced lung disease despite aggressive care. Persistent inflammation and oxidative stress contribute to exacerbations and disease progression. Flaxseed (FS), a dietary botanical supplement with high fiber, lignan phenolics, and omega-3 fatty acids has anti-inflammatory and antioxidant properties in murine models of acute and chronic lung injury. This pilot study was designed to determine whether CF patients could tolerate FS, evaluate circulating FS metabolites, and study biomarkers of lung damage, as a prelude to studying clinical outcomes. METHODS: 10 CF patients and 5 healthy volunteers consumed 40 g of FS daily for 4 weeks with safety and tolerability being assessed. Urine was evaluated for systemic oxidative stress and plasma for FS metabolites (enterolignans) and cytokine levels. Buccal swabs were analyzed for gene expression of Nrf2-regulated antioxidant enzymes including Heme Oxygenase-1 (HO-1) and NAD(P)H Quinone Oxidoreductase 1 (NQO1). RESULTS: All subjects completed the study without serious adverse events. Plasma levels of enterolignans were detectable in both healthy controls and CF volunteers. CF patients were stratified based on plasma enterolignan levels after 2 weeks of FS administration into high- (174 to 535 nM ED and 232 to 1841 nM EL) and low- (0 to 32 nM ED and 0 to 40 nM EL) plasma lignan cohorts. The low enterolignan level cohort experienced a statistically significant drop in urinary inflammatory IsoP and plasma TNFα levels, while demonstrating higher average NQO1 mRNA levels in buccal epithelium compared to high-lignan patients. CONCLUSIONS: This pilot study demonstrated that FS is tolerated by CF patients. FS metabolites could be detected in the plasma. Future studies will assess appropriate dosing and target populations for FS, while exploring clinical outcomes. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02014181 .

Oxidative Lung Damage Resulting from Repeated Exposure to Radiation and Hyperoxia Associated with Space Exploration.

BACKGROUND: Spaceflight missions may require crewmembers to conduct Extravehicular Activities (EVA) for repair, maintenance or scientific purposes. Pre-breathe protocols in preparation for an EVA entail 100% hyperoxia exposure that may last for a few hours (5-8 hours), and may be repeated 2-3 times weekly. Each EVA is associated with additional challenges such as low levels of total body cosmic/galactic radiation exposure that may present a threat to crewmember health and therefore, pose a threat to the success of the mission. We have developed a murine model of combined, hyperoxia and radiation exposure (double-hit) in the context of evaluating countermeasures to oxidative lung damage associated with space flight. In the current study, our objective was to characterize the early and chronic effects of repeated single and double-hit challenge on lung tissue using a novel murine model of repeated exposure to low-level total body radiation and hyperoxia. This is the first study of its kind evaluating lung damage relevant to space exploration in a rodent model. METHODS: Mouse cohorts (n=5-15/group) were exposed to repeated: a) normoxia; b) >95% O2 (O2); c) 0.25Gy single fraction gamma radiation (IR); or d) a combination of O2 and IR (O2+IR) given 3 times per week for 4 weeks. Lungs were evaluated for oxidative damage, active TGFß1 levels, cell apoptosis, inflammation, injury, and fibrosis at 1, 2, 4, 8, 12, 16, and 20 weeks post-initiation of exposure. RESULTS: Mouse cohorts exposed to all challenge conditions displayed decreased bodyweight compared to untreated controls at 4 and 8 weeks post-challenge initiation. Chronic oxidative lung damage to lipids (malondialdehyde levels), DNA (TUNEL, cleaved Caspase 3, cleaved PARP positivity) leading to apoptotic cell death and to proteins (nitrotyrosine levels) was elevated all treatment groups. Importantly, significant systemic oxidative stress was also noted at the late phase in mouse plasma, BAL fluid, and urine. Importantly, however, late oxidative damage across all parameters that we measured was significantly higher than controls in all cohorts but was exacerbated by the combined exposure to O2 and IR. Additionally, impaired levels of arterial blood oxygenation were noted in all exposure cohorts. Significant but transient elevation of lung tissue fibrosis (p<0.05), determined by lung hydroxyproline content, was detected as early as 2 week in mice exposed to challenge conditions and persisted for 4-8 weeks only. Interestingly, active TGFß1 levels in +BAL fluid was also transiently elevated during the exposure time only (1-4 weeks). Inflammation and lung edema/lung injury was also significantly elevated in all groups at both early and late time points, especially the double-hit group. CONCLUSION: We have characterized significant, early and chronic lung changes consistent with oxidative tissue damage in our murine model of repeated radiation and hyperoxia exposure relevant to space travel. Lung tissue changes, detectable several months after the original exposure, include significant oxidative lung damage (lipid peroxidation, DNA damage and protein nitrosative stress) and increased pulmonary fibrosis. These findings, along with increased oxidative stress in diverse body fluids and the observed decreases in blood oxygenation levels in all challenge conditions (whether single or in combination), lead us to conclude that in our model of repeated exposure to oxidative stressors, chronic tissue changes are detected that persist even months after the exposure to the stressor has ended. This data will provide useful information in the design of countermeasures to tissue oxidative damage associated with space exploration.

Appropriate goal level for 25-hydroxyvitamin D in cystic fibrosis.

BACKGROUND: Vitamin D deficiency is common in patients with cystic fibrosis (CF), and guidelines recommend 25-hydroxyvitamin D (25OHD) levels ≥ 30 ng/mL. This threshold was selected because serum parathyroid hormone (PTH) rises in healthy individuals when the 25OHD level falls below 30 ng/mL. PTH levels > 50 pg/mL are associated with an increased risk of bone loss. However, the relationship between 25OHD and PTH has not been studied in CF. We sought to determine the appropriate goal 25OHD level in patients with CF by identifying the level below which the risk of PTH > 50 pg/mL begins to increase. METHODS: Levels of 25OHD and PTH in 216 individuals with CF were collected prospectively. Individuals with 25OHD < 30 ng/mL were treated with vitamin D2, and levels were reevaluated. RESULTS: Mean 25OHD level was 25.7 ± 12.4 ng/mL, and mean PTH level was 46.7 ± 25.9 pg/mL. In 63% of individuals, 25OHD level was < 30 ng/mL, and in 38.0% it was ≤ 20 ng/mL. Low 25OHD levels were significantly associated with elevated PTH levels, with a mean PTH of 53.1 ± 29.8 pg/mL for 25OHD level 0 to 19 ng/mL; 51.1 ± 30.7 pg/mL for 25OHD level 20 to 29 ng/mL; 38.4 ± 16.4 pg/mL for 25OHD level 30 to 39 ng/mL; and 37.2 ± 16.4 pg/mL for 25OHD level ≥ 40 ng/mL (P = .006). We assessed the sensitivity of different 25OHD thresholds to identify individuals meeting the goal of a PTH level < 50 pg/mL to reduce the risk of bone loss. To obtain 90% sensitivity, a 25OHD level ≥ 35 ng/mL was required. Strikingly, 23% of individuals with 25OHD levels 30 to 34 ng/mL still had a PTH level > 50 pg/mL. This decreased to 14% for 25OHD level ≥ 35 ng/mL. CONCLUSIONS: Inadequate serum 25OHD levels are common in adults with CF and are associated with elevated PTH levels. Aiming to maintain 25-OHD levels ≥ 35 ng/mL in individuals with CF decreases the risk of having a PTH level associated with secondary hyperparathyroidism and bone loss.