Effects of acute exhaustive exercise and chronic exercise training on type 1 and type 2 T lymphocytes.

The present study examined the effects of acute exhaustive exercise and chronic exercise training on type 1 and type 2 T lymphocyte distribution and intracellular cytokine production. Seven endurance-trained male cyclists completed exercise trials to exhaustion before, immediately after, and following 2 weeks of resting recovery from a 6-day intensified training period (ITP). During each trial, resting and post-exercise blood samples were incubated with phorbol 12-myristate 13-acetate (PMA) and ionomycin and stained for T lymphocyte surface antigens (CD3). Cells were then permeabilised, stained for intracellular cytokines and analysed using flow cytometry. Acute exhaustive exercise before and following 2 weeks of recovery from the ITP, but not immediately after the ITP, significantly reduced the circulating percentage and number of lFN-gamma+ (type 1) T cells (P<0.05). In addition, the amount of IFN-gamma produced by stimulated T lymphocytes was decreased (P<0.05) post-exercise during each trial. The percentage and number of interferon (IFN)-gamma+ T lymphocytes was decreased (P<0.05) at rest immediately after the ITP compared with before and following 2 weeks of resting recovery from the ITP. However, the amount of IFN-gamma produced by stimulated T lymphocytes at rest was unaltered following the ITP. Neither acute exercise nor chronic exercise training caused an alteration in the circulating percentage or number of interleukin (IL)-4+ (type 2) T lymphocytes. These results suggest a possible mechanism for the increased incidence of infection reported during chronic exercise training via modulation of type 1/type 2 T lymphocyte distribution.

The physiological regulation of toll-like receptor expression and function in humans.

Eleven mammalian toll-like receptors (TLRs 1-11) have been identified to date and are known to play a crucial role in the regulation of immune responses; however, the factors that regulate TLR expression and function in vivo are poorly understood. Therefore, in the present study, we investigated the physiological regulation of TLR expression and function in humans. To examine the influence of diurnal rhythmicity on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers (n = 8) at time points coinciding with the peak and nadir in the endogenous circulating cortisol concentration. While no diurnal rhythmicity in the expression of TLRs 1, 2, 4 or 9 was observed, the upregulation of costimulatory (CD80 and CD86) and antigen-presenting (MHC class II) molecules on CD14(+) monocytes following activation with specific TLR ligands was greater (P < 0.05) in samples obtained in the evening compared with the morning. To examine the influence of physical stress on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers (n = 11) at rest and following 1.5 h of strenuous exercise in the heat (34 degrees C). Strenuous exercise resulted in a decrease (P < 0.005) in the expression of TLRs 1, 2 and 4 on CD14(+) monocytes. Furthermore, the upregulation of CD80, CD86, MHC class II and interleukin-6 by CD14(+) monocytes following activation with specific TLR ligands was decreased (P < 0.05) in samples obtained following exercise compared with at rest. These results demonstrate that TLR function is subject to modulation under physiological conditions in vivo and provide evidence for the role of immunomodulatory hormones in the regulation of TLR function.

Deregulated production of protective cytokines in response to Candida albicans infection in patients with chronic mucocutaneous candidiasis.

Patients with chronic mucocutaneous candidiasis (CMC) are selectively unable to clear the yeast Candida, which results in persistent debilitating infections affecting the skin, nails, and mucous membranes. The underlying defect is unknown. Recent animal studies highlighted the importance of type 1 cytokines in protection against Candida, and previous work suggested that CMC patients may exhibit altered cytokine production in response to Candida. Based on these findings, in this study we investigated cytokine production in CMC patients by assessing a range of inflammatory, anti-inflammatory, type 1, and type 2 cytokines (interleukin-2 [IL-2], IL-4, IL-5, IL-6, IL-10, IL-12, gamma interferon [IFN-gamma], tumor necrosis factor alpha [TNF-alpha]) in whole-blood cultures in response to five different fractions of Candida albicans (carbohydrate, purified mannan, and protein-rich fractions, etc.), as well as non-Candida antigens. Our results demonstrate that cytokine production is deregulated in a Candida-specific way for some cytokines (IL-2, IL-10), is deregulated more generally for other cytokines (IL-12, IL-6, IFN-gamma), and is not markedly altered for still other cytokines (TNF-alpha, IL-4, IL-5). The most notable finding in CMC patients was the markedly impaired production of IL-12 in parallel with dramatically increased levels of IL-6 and IL-10 that occurred selectively in response to Candida. These results suggest that patients with CMC have impaired production of type 1-inducing cytokines (possibly a macrophage or dendritic cell defect?), which could result in an inability to mount protective cell-mediated responses and a failure to clear Candida. Continued tissue damage and inflammation may trigger production of high levels of inhibitory cytokines, such as the IL-10 production seen in our study, which would further reduce production of type 1-inducing cytokines in a positive feedback loop leading to persistent infection.