Exercise and adrenergic regulation of immunity.

Exercise training has a profound impact on immunity, exerting a multitude of positive effects in indications such as immunosenescence, cancer, viral infections and inflammatory diseases. The immune, endocrine and central nervous systems work in a highly synergistic manner and it has become apparent that catecholamine signaling through leukocyte ß-adrenergic receptors (ß-ARs) is a key mechanism by which exercise mediates improvements in immune function to help mitigate numerous disease conditions. Central to this is the preferential mobilization and redistribution of effector lymphocytes with potent anti-viral and anti-tumor activity, their interaction with muscle-derived cytokines, and the effects of catecholamine signaling on mitochondrial biogenesis, immunometabolism and the resulting inflammatory response. Here, we review the impact of acute and chronic exercise on adrenergic regulation of immunity in the context of aging, cancer, viral infections and inflammatory disease. We also put forth our contention that exercise interventions designed to improve immunity, prevent disease and reduce inflammation should consider the catecholamine-AR signaling axis as a therapeutic target and ask whether or not the adrenergic signaling machinery can be 'trained' to improve immune responses to stress, disease or during the normal physiological process of aging. Finally, we discuss potential strategies to augment leukocyte catecholamine signaling to boost the effects of exercise on immunity in individuals with desensitized ß-ARs or limited exercise tolerance.

Abdominal Obesity-Related Disturbance of Insulin Sensitivity Is Associated with CD8+ EMRA Cells in the Elderly.

Aging and overweight increase the risk of developing type 2 diabetes mellitus. In this cross-sectional study, we aimed to investigate the potential mediating role of T-EMRA cells and inflammatory markers in the development of a decreased insulin sensitivity. A total of 134 healthy older volunteers were recruited (age 59.2 (SD 5.6) years). T cell subpopulations were analyzed by flow cytometry. Furthermore, body composition, HOMA-IR, plasma tryptophan (Trp) metabolites, as well as cytokines and adipokines were determined. Using subgroup and covariance analyses, the influence of BMI on the parameters was evaluated. Moreover, correlation, multiple regression, and mediation analyses were performed. In the subgroup of participants with obesity, an increased proportion of CD8+EMRA cells and elevated concentrations of plasma kynurenine (KYN) were found compared to the lower-weight subgroups. Linear regression analysis revealed that an elevated HOMA-IR could be predicted by a higher proportion of CD8+EMRA cells and KYN levels. A mediation analysis showed a robust indirect effect of the Waist-to-hip ratio on HOMA-IR mediated by CD8+EMRA cells. Thus, the deleterious effects of abdominal obesity on glucose metabolism might be mediated by CD8+EMRA cells in the elderly. Longitudinal studies should validate this assumption and analyze the suitability of CD8+EMRA cells as early predictors of incipient prediabetes.

Reliability and suitability of physiological exercise response and recovery markers.

There is currently insufficient evidence about the reliable quantification of exercise load and athlete's recovery management for monitoring training processes. Therefore, this test-retest study investigated the reliability of various subjective, muscle force, and blood-based parameters in order to evaluate their suitability for monitoring exercise and recovery cycles. 62 subjects completed two identical 60-min continuous endurance exercise bouts intermitted by a four-week recovery period. Before, immediately after, three, and 24 h after each exercise bout, analysis of parameters were performed. Significant changes over time were found for rating of perceived exertion (RPE), multidimensional mood state questionnaire (MDMQ), maximum voluntary contraction parameters (MVCs), and blood-based biomarkers (p < 0.05). Excellent reliability was calculated for MVCs, mean corpuscular volume and 5-bound distance (ICC > 0.90). A good reliability was found for thiobarbituric acid reactive substances (TBARS) (ICC = 0.79) and haematological markers (ICC = 0.75-0.86). For RPE, MDMQ, interleukin (IL-) 1RA, IL-6, IL-8, IL-15, cortisol, lactate dehydrogenase (LDH), creatine kinase (CK) only moderate reliability was found (ICC < 0.75). Significant associations for IL1-RA and CK to MVC were found. The excellent to moderate reliability of TBARS, LDH, IL-1RA, six measured haematological markers, MVCs and MDMQ implicate their suitability as physiological exercise response and recovery markers for monitoring athletes' load management.