Background/objectives: Disruptions in redox balance lead to oxidative stress, a promoter of morbidity in critical illness. This study aimed to: (1) characterize the plasma and alveolar thiol/disulfide redox pools, (2) examine their associations with alveolar macrophage phagocytosis, and (3) determine the effect of high dose Vitamin D3on plasma thiol/disulfide redox. Subjects/methods: Subjects were 30 critically ill, ventilated adults in a double-blind randomized trial of high-dose (250 000 or 500 000 IU) Vitamin D3or placebo. Baseline bronchoalveolar lavage fluid (BALF) samples were analyzed for determination of alveolar phagocytosis index (PI) and for concentrations of glutathione (GSH), glutathione disulfide (GSSG), cysteine (Cys), cystine (CySS), and their respective redox potentials (EhGSSG and EhCySS). Plasma redox outcomes were assessed at baseline and days 7 and 14. Results: Baseline plasma Cys was inversely associated with alveolar PI (ρ = -0.69, P = 0.003), and EhCySS was positively associated with PI (ρ = 0.61, P = 0.01). Over time, among all subjects there was an increase in plasma GSH levels and a decrease in EhGSSG (P < 0.01 for both), with no difference by treatment group. Vitamin D3decreased oxidized plasma GSSG to a more normal state (P for group x time = 0.009). Conclusions: Oxidative stress indicators were positively associated with alveolar macrophage phagocytic function in acutely ill ventilated adults. High-dose Vitamin D3decreased plasma GSSG concentrations, which suggests that Vitamin D can possibly improve the oxidative stress environment.
Objective Redox status and inflammation are important in the pathophysiology of numerous chronic diseases. Epidemiological studies have linked vitamin D status to a number of chronic diseases. We aimed to examine the relationships between serum 25-hydroxyvitamin D [25(OH)D] and circulating thiol/disulphide redox status and biomarkers of inflammation. Design This was a cross-sectional study of N = 693 adults (449 females, 244 males) in an apparently healthy, working cohort in Atlanta, GA. Plasma glutathione (GSH), cysteine (Cys) and their associated disulphides were determined with high-performance liquid chromatography, and their redox potentials (E h GSSG and Eh CySS) were calculated using the Nernst equation. Serum inflammatory markers included interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α, assayed on a multiplex platform, and C-reactive protein (CRP), assayed commercially. Relationships were assessed with multiple linear regression analyses. Results Serum 25(OH)D was positively associated with plasma GSH (β ± SE: 0·002 ± 0·0004) and negatively associated with plasma Eh GSSG (β ± SE: -0·06 ± 0·01) and Cys (β ± SE: -0·01 ± 0·003) (P < 0·001 for all); statistical significance remained after adjusting for age, gender, race, percentage body fat and traditional cardiovascular risk factors (P = 0·01-0·02). The inverse relationship between serum 25(OH)D and CRP was confounded by percentage body fat, and full adjustment for covariates attenuated serum 25(OH)D relationships with other inflammatory markers to nonstatistical significance. Conclusions Serum 25(OH)D concentrations were independently associated with major plasma thiol/disulphide redox systems, suggesting that vitamin D status may be involved in redox-mediated pathophysiology.