Baker's yeast ß-glucan supplementation increases monocytes and cytokines post-exercise: implications for infection risk?

Strenuous aerobic exercise is known to weaken the immune system, and while many nutritional supplements have been proposed to boost post-exercise immunity, few are known to be effective. The purpose of the present study was to evaluate whether 10 d of supplementation with a defined source of baker's yeast ß-glucan (BG, Wellmune WGP®) could minimise post-exercise immunosuppression. Recreationally active men and women (n 60) completed two 10 d trial conditions using a cross-over design with a 7 d washout period: placebo (rice flour) and baker's yeast BG (250 mg/d of ß-1,3/1,6-glucans derived from Saccharomyces cerevisiae) before a bout of cycling (49 ± 6 min) in a hot (38 ± 2°C), humid (45 ± 2 % relative humidity) environment. Blood was collected at baseline (before supplement), pre- (PRE), post- (POST) and 2 h (2H) post-exercise. Total and subset monocyte concentration was measured by four-colour flow cytometry. Plasma cytokine levels and lipopolysaccharide (LPS)-stimulated cytokine production were measured using separate multiplex assays. Total (CD14⁺) and pro-inflammatory monocyte concentrations (CD14⁺/CD16⁺) were significantly greater at POST and 2H (P<0·05) with BG supplementation. BG supplementation boosted LPS-stimulated production of IL-2, IL-4, IL-5 and interferon-γ (IFN-γ) at PRE and POST (P<0·05). Plasma IL-4, IL-5 and IFN-γ concentrations were greater at 2H following BG supplementation. It appears that 10 d of supplementation with BG increased the potential of blood leucocytes for the production of IL-2, IL-4, IL-5 and IFN-γ. The key findings of the present study demonstrate that BG may have potential to alter immunity following a strenuous exercise session.

Mouse blood monocytes: standardizing their identification and analysis using CD115.

Monocytes have been used to assess immune dysfunction and disease. While mouse models are a useful longitudinal analog, few researchers have assessed changes in mouse monocytes. The purpose of this study was to provide recommendations for the sample processing and flow cytometric analysis of mouse blood monocytes. Blood was drawn in a non-lethal manner from CD-1 male mice to be used in three experiments. Experiment 1 compared commonly used mouse monocyte markers. Experiment 2 compared the stability of CD115 expression after immediate (0h) and delayed (2 and 4h) processing following blood collection under various experimental conditions (laser strength, anticoagulant, and storage temp.). Experiment 3 compared the consistency of CD115(+) monocyte and subset concentrations using decreasing (40, 20, 10 and 5µL) volumes of blood. In experiment 1, >95% of CD115(+) events co-expressed CD11b; >85% co-expressed CD14. 70% of CD14(+) and 50% of CD11b(+) events co-expressed CD115. In experiment 2, CD115 expression decreased by 33% between 0 and 4h when stored at room temperature. Blood treated with EDTA and refrigerated maintained CD115 stability. In experiment 3, calculated concentrations for total monocyte events varied by <10% when 40, 20 and 10µL of blood were stained. While CD115 staining provides the most distinct monocyte population, it is important to treat blood with EDTA and refrigerate if sample processing will be delayed over 2h. Collectively, the findings of the present study outline important considerations that must be addressed when examining mouse monocytes in small, non-lethal blood samples.

Weight gain in response to high-fat feeding in CD-1 male mice.

The purpose of this study was to compare weight gain and food intake during high-fat feeding in outbred CD-1 male mice while considering several different experimental designs. This study was completed using data from three separate experiments and was designed to address different experimental design issues. Experiment 1 compared mice housed in groups or singly. Experiment 2 compared adolescent and young adult mice. Experiment 3 examined mice that had been previously exercise-trained prior to diet-induced weight gain. Data from each experiment were analysed using repeated measures analysis of variance and linear regression. While housing and age did not significantly affect weight gain, mice that were previously exercise-trained consumed significantly more kilocalories than sedentary mice while maintaining comparable body weights. We generated a linear prediction model using data from Experiments 1 and 2 that will allow investigators to calculate the weeks of high-fat feeding needed to reach a target body weight. Our key findings characterize the issues related to and affecting experimental design when utilizing an outbred mouse diet-induced weight gain model and will serve as a guide for future researchers.