Effect of prolonged, submaximal exercise and carbohydrate ingestion on monocyte intracellular cytokine production in humans

Molecular and biochemical investigations of the anti-fatigue effects of tea polyphenols and fruit extracts of Lycium ruthenicum Murr. on mice with exercise-induced fatigue

Background: The molecular mechanisms regulating the therapeutic effects of plant-based ingredients on the exercise-induced fatigue (EIF) remain unclear. The therapeutic effects of both tea polyphenols (TP) and fruit extracts of Lycium ruthenicum (LR) on mouse model of EIF were investigated. Methods: The variations in the fatigue-related biochemical factors, i.e., lactate dehydrogenase (LDH), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-2 (IL-2), and interleukin-6 (IL-6), in mouse models of EIF treated with TP and LR were determined. The microRNAs involved in the therapeutic effects of TP and LR on the treatment of mice with EIF were identified using the next-generation sequencing technology. Results: Our results revealed that both TP and LR showed evident anti-inflammatory effect and reduced oxidative stress. In comparison with the control groups, the contents of LDH, TNF-α, IL-6, IL-1β, and IL-2 were significantly decreased and the contents of SOD were significantly increased in the experimental groups treated with either TP or LR. A total of 23 microRNAs (21 upregulated and 2 downregulated) identified for the first time by the high-throughput RNA sequencing were involved in the molecular response to EIF in mice treated with TP and LR. The regulatory functions of these microRNAs in the pathogenesis of EIF in mice were further explored based on Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses with a total of over 20,000-30,000 target genes annotated and 44 metabolic pathways enriched in the experimental groups based on GO and KEGG databases, respectively. Conclusion: Our study revealed the therapeutic effects of TP and LR and identified the microRNAs involved in the molecular mechanisms regulating the EIF in mice, providing strong experimental evidence to support further agricultural development of LR as well as the investigations and applications of TP and LR in the treatment of EIF in humans, including the professional athletes.

Sequential Submaximal Training in Elite Male Rowers Does Not Result in Amplified Increases in Interleukin-6 or Hepcidin

Previous research investigating single bouts of exercise have identified baseline iron status and circulating concentrations of interleukin-6 (IL-6) as contributors to the magnitude of postexercise hepcidin increase. The current study examined the effects of repeated training bouts in close succession on IL-6 and hepcidin responses. In a randomized, crossover design, 16 elite male rowers completed two trials, a week apart, with either high (1,000 mg) or low (<50 mg) calcium pre-exercise meals. Each trial involved two, submaximal 90-min rowing ergometer sessions, 2.5 hr apart, with venous blood sampled at baseline; pre-exercise; and 0, 1, 2, and 3 hr after each session. Peak elevations in IL-6 (approximately 7.5-fold, p < .0001) and hepcidin (approximately threefold, p < .0001) concentrations relative to baseline were seen at 2 and 3 hr after the first session, respectively. Following the second session, concentrations of both IL-6 and hepcidin remained elevated above baseline, exhibiting a plateau rather than an additive increase (2 hr post first session vs. 2 hr post second session, p = 1.00). Pre-exercise calcium resulted in a slightly greater elevation in hepcidin across all time points compared with control (p = .0005); however, no effect on IL-6 was evident (p = .27). Performing multiple submaximal training sessions in close succession with adequate nutritional support does not result in an amplified increase in IL-6 or hepcidin concentrations following the second session in male elite rowers. Although effects of calcium intake require further investigation, athletes should continue to prioritize iron consumption around morning exercise prior to exercise-induced hepcidin elevations to maximize absorption.

Ursolic acid does not change the cytokine levels following resistance training in healthy men: A pilot balanced, double-blind and placebo-controlled clinical trial

Ursolic acid (UA) is a natural compound that shows anti-inflammatory actions. However, no human studies have investigated the cytokine profile during the RT and UA consumption. The purpose of this study was to verify if UA is able to potentiate the anti-inflammatory activity after RT, reflecting in the reduction of blood inflammatory markers in healthy men. Twenty-seven participants were allocated to two groups: control (CON) (n = 13) and UA (n = 14). For 8weeks, each group performed RT and consumed capsules containing a placebo (400 mg/day) or UA (400 mg/day). Serum cytokine concentrations were evaluated before and after the training period. There was no difference in the serum cytokine concentrations of TNF-α, IL-10 and IL-6 (p > 0.05). In conclusion, UA supplementation for 8weeks was not able to change the blood TNF-α, IL-10, and IL-6 concentrations in healthy men undergoing RT. However, further studies are warranted to investigate other inflammatory markers.

The Role of Exercise Training on Low-Grade Systemic Inflammation in Adults with Overweight and Obesity: A Systematic Review

Low-grade systemic inflammation leads to critical alterations of several tissues and organs that can promote the appearance of non-communicable diseases, a risk that is increased in adults with obesity. Exercise training may counteract low-grade systemic inflammation, but there is a lack of consensus on how cytokines are modulated by training in adults with obesity. This study aimed of examining the effects of exercise training on circulating pro- and anti-inflammatory cytokines in adults with overweight and obesity, and whether exercise-induced fat mass reduction could mediate that effect. The search was conducted on Medline (Pubmed), SPORTDiscus and Web of Science databases from January 1998 to August 2021, using keywords pertaining to inflammation, exercise, and obesity. A total of 27 studies were selected, in which the circulating concentration levels of cytokines were analyzed. Endurance training (ET) decreased circulating CRP, IL-6 and TNF-α levels. TNF-α was reduced after resistance and concurrent training (CT), while IL-10 increased after resistance training (RT). Changes in IL-10 and CRP coincided with fat mass reduction, while decreased TNF-α levels were concomitant with changes in IL-6 and IL-10. Exercise training may reduce systemic low-grade inflammation profile in adults with overweight and obesity.

No effect of intradialytic neuromuscular electrical stimulation on inflammation and quality of life: a randomized and parallel design clinical trial

Neuromuscular electrical stimulation (NMES) elicits muscle contraction and has been shown to improvement of quality of life. However, if NMES improvement the quality of life and attenuate the inflammation is not fully understood. Therefore, our aim sought to assess the effects of short-term of intradialytic NMES on inflammation and quality of life in patients with chronic kidney disease patients undergoing hemodialysis. A randomized clinical trial conducted with parallel design enrolled adult hemodialysis patients three times a week during 1 month. Patients were randomly assigned to two groups (control group, n = 11; 4F/7 M) or (NMES group, n = 10; 4F/6 M). Pre-and post-intervention, was measured the high-sensitivity C reactive protein, interleukin-6, interleukin-10, and TNFα by the ELISA, and quality of life was applied using the SF-36. During each hemodialysis session, NMES was applied bilaterally at thigh and calves for 40 min. There was not change in cytokines (hs-CRP, IL-6, IL-10, and TNFα) concentrations time × group interaction. In addition, no difference was found in eight domains of quality of life. In addition, the groups did not differ for muscle strength and muscle mass. In conclusion, we found that intradialytic NMES did not change inflammation neither quality of life.

Exercise-induced modulation of monocytes in breast cancer survivors

Background

Exercise training reduces inflammation in breast cancer survivors; however, the mechanism is not fully understood.

Objectives

The effects of acute and chronic exercise on monocyte toll-like receptor (TLR2 and 4) expression and intracellular cytokine production were examined in sedentary breast cancer survivors.

Methods

Eleven women with stage I, II, or III breast cancer within one year of treatment completion performed an acute, intermittent aerobic exercise trial. Blood samples were obtained before, immediately, and 1 h after a 45-min acute exercise trial that was performed before and after 16 weeks of combined aerobic and resistance. LPS-stimulated intracellular IL-1ß, TNF, and IL-6 production, and TLR2 and TLR4 expression were evaluated in CD14⁺CD16^- and CD14⁺CD16⁺ monocytes using flow cytometry.

Results

Exercise training decreased IL-1ß⁺CD14⁺CD16^- proportion (24.6%, p=0.016), IL-1ß⁺CD14⁺CD16^- mean fluorescence intensity (MFI) (-9989, p=0.014), IL-1ß⁺CD14⁺CD16⁺ MFI (-11101, p=0.02), and IL-6⁺CD14⁺CD16^- proportion (16.9%, P=0.04). TLR2 and TLR4 expression did not change following exercise training but decreased 1 h after acute exercise in CD14⁺CD16^- (-63, p=0.002) and CD14⁺CD16⁺ (-18, p=0.006) monocytes, respectively. Immediately after the acute exercise, both monocyte subgroup cell concentration increased, with CD14⁺CD16⁺ concentrations being decreased at 1 h post without changes in intracellular cytokine production.

Conclusions

Exercise training reduced monocyte intracellular pro-inflammatory cytokine production, especially IL-1ß, although these markers did not change acutely. While acute exercise downregulated the expression of TLR2 and TLR4 on monocytes, this was not sustained over the course of training. These results suggest that the anti-inflammatory effect of combined aerobic and resistance exercise training in breast cancer survivors may be, in part, due to reducing resting monocyte pro-inflammatory cytokine production.

Dietary supplementation of a Saccharomyces cerevisiae fermentation product attenuates exercise-induced stress markers in young horses

Mitigation of exercise-induced stress is of key interest in determining ways to optimize performance horse health. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would decrease markers of exercise-induced stress and inflammation in young horses, Quarter Horse yearlings (mean ± SD; 9 ± 1 mo) were randomly assigned to receive either no supplementation (CON; n = 8) or 21 g/d S. cerevisiae fermentation product (10.5 g/feeding twice daily; SCFP; n = 10) top-dressed on a basal diet of custom-formulated grain as well as ad libitum Coastal bermudagrass hay. After 8 wk of dietary treatments, horses underwent a 2-h submaximal exercise test (SET) on a free-stall mechanical exerciser. Serum was collected before dietary treatment supplementation (week 0), at week 8 pre-SET, and 0, 1, and 6 h post-SET and analyzed for concentrations of cortisol and serum amyloid A (SAA) by commercial enzyme-linked immunosorbent assay (ELISA) and for cytokine concentrations by commercial bead-based ELISA. Data were analyzed using linear models with repeated measures in SAS v9.4. From week 0 to 8 (pre-SET), serum cortisol decreased (P = 0.01) and SAA did not change, but neither were affected by diet. Serum concentrations of all cytokines decreased from week 0 to 8 (P ≤ 0.008), but granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, and interleukin-8 (IL-8) decreased to a greater extent in CON than in SCFP horses (P ≤0.003). In response to the week 8 SET, serum cortisol increased in all horses (P < 0.0001) but returned to pre-SET levels by 1 h post-SET in horses receiving SCFP. At 6 h post-SET, cortisol concentrations in CON horses returned to pre-SET concentrations, whereas cortisol declined further in SCFP horses to below pre-SET levels (P = 0.0002) and lower than CON (P = 0.003) at that time point. SAA increased at 6 h post-SET in CON (P < 0.0001) but was unchanged through 6 h in SCFP horses. All cytokines except G-CSF increased in response to the SET (P < 0.0001) but showed differing response patterns. Concentrations of IL-1β, IL-6, and tumor necrosis factor-alpha were lesser (P ≤ 0.05), and concentrations of G-CSF and IL-18 tended to be lesser (P ≤ 0.09) in SCFP compared with CON horses throughout recovery from the SET. In summary, 8 wk of dietary supplementation with 21 g/d of SCFP may mitigate cellular stress following a single, prolonged submaximal exercise bout in young horses.

IL-6 family cytokines as potential therapeutic strategies to treat metabolic diseases

Metabolic disease is highly prevalent. Here we discuss the therapeutic utility of using gp130 receptor ligands as a therapeutic strategy to treat metabolic disease.

The Role of Exercise, Diet, and Cytokines in Preventing Obesity and Improving Adipose Tissue

The prevalence of obesity continues to rise worldwide despite evidence-based public health recommendations. The promise to adopt a healthy lifestyle is increasingly important for tackling this global epidemic. Calorie restriction or regular exercise or a combination of the two is accepted as an effective strategy in preventing or treating obesity. Furthermore, the benefits conferred by regular exercise to overcome obesity are attributed not only to reduced adiposity or reduced levels of circulating lipids but also to the proteins, peptides, enzymes, and metabolites that are released from contracting skeletal muscle or other organs. The secretion of these molecules called cytokines in response to exercise induces browning of white adipose tissue by increasing the expression of brown adipocyte-specific genes within the white adipose tissue, suggesting that exercise-induced cytokines may play a significant role in preventing obesity. In this review, we present research-based evidence supporting the effects of exercise and various diet interventions on preventing obesity and adipose tissue health. We also discuss the interplay between adipose tissue and the cytokines secreted from skeletal muscle and other organs that are known to affect adipose tissue and metabolism.

Metabolic communication during exercise

The coordination of nutrient sensing, delivery, uptake and utilization is essential for maintaining cellular, tissue and whole-body homeostasis. Such synchronization can be achieved only if metabolic information is communicated between the cells and tissues of the entire organism. During intense exercise, the metabolic demand of the body can increase approximately 100-fold. Thus, exercise is a physiological state in which intertissue communication is of paramount importance. In this Review, we discuss the physiological processes governing intertissue communication during exercise and the molecules mediating such cross-talk.

Bone-Muscle Mutual Interactions

PURPOSE OF REVIEW

The purpose of this review is to describe the current state of our thinking regarding bone-muscle interactions beyond the mechanical perspective.

RECENT FINDINGS

Recent and prior evidence has begun to dissect many of the molecular mechanisms that bone and muscle use to communicate with each other and to modify each other's function. Several signaling factors produced by muscle and bone have emerged as potential mediators of these biochemical/molecular interactions. These include muscle factors such as myostatin, Irisin, BAIBA, IL-6, and the IGF family and the bone factors FGF-23, Wnt1 and Wnt3a, PGE2, FGF9, RANKL, osteocalcin, and sclerostin. The identification of these signaling molecules and their underlying mechanisms offers the very real and exciting possibility that new pharmaceutical approaches can be developed that will permit the simultaneous treatments of diseases that often occur in combination, such as osteoporosis and sarcopenia.

Preliminary study of the association of serum irisin levels with poor sleep quality in rheumatoid arthritis patients

STUDY OBJECTIVES

Sleep disorders are significant problems in patients with rheumatoid arthritis (RA) and are associated with poor quality of life. Irisin is myokine which may have anti-inflammatory and energy regulatory roles. This study assessed the association of serum irisin levels with the quality of sleep and disease activity in RA patients.

METHODS

In sum, 58 RA patients and 30 matched healthy controls were included. Disease activity score in 28 joints (DAS28-ESR) and the patients' global score were calculated. RA patients were grouped according to the Pittsburgh Sleep Quality Index score (PSQI) into good-sleepers (group 1) defined as a PQSI score≤5 and poor sleepers (group 2) with a PSQI > 5. Serum irisin levels were measured for both patients and controls by commercially available enzyme-linked immunosorbent assay kits.

RESULTS

Poor sleep quality was found in 26 (45%) of the RA patients. Irisin levels were significantly lower in RA patients with poor sleep compared to those with good sleep and healthy controls (p < 0.001). Serum irisin levels correlated inversely with disease duration, morning stiffness duration, DAS28-ESR, global score, and total PSQI score (r = -0.722 to -0.263 & p values≤0.001-0.04) indicating a possible anti-inflammatory role of irisin in RA patients. The analysis employed Student's t-test, ANOVA, and Pearson correlation.

CONCLUSIONS

Irisin levels were decreased in RA patients with poor sleep quality compared to RA patients with good sleep quality and healthy controls, indicating a possible association of decreased serum irisin with sleep impairment in RA patients.

Reduced inflammatory and phagocytotic responses following normobaric hypoxia exercise despite evidence supporting greater immune challenge

This study examined changes in immune markers following sustained treadmill exercise in normobaric hypoxia. Ten subjects performed 1 h of treadmill exercise (65% maximal oxygen uptake) under normoxic (NORM: fraction of inspired oxygen (F_IO₂) = 20.9%) and normobaric hypoxic (HYP: F_IO₂ = 13.5%) conditions. Blood samples, collected before, after (Post), 1 h after (1-Post), and 4 h after (4-Post) exercise, were assayed for plasma cytokines (interleukin (IL)-1RA/IL-1β/IL-8/tumor necrosis factor alpha (TNF-α)) and markers of leukocyte activation (macrophage inflammatory protein-1β (MIP-1β)/myeloperoxidase (MPO)/soluble intercellular adhesion molecule-1 (sICAM-1)) using ELISA. Pro- to anti-inflammatory cytokine ratios (TNF-α/IL-1RA; IL-1β/IL-1RA) were calculated. Peripheral blood mononuclear cells (PBMC) were analyzed for changes in inflammatory status (phosphorylated nuclear factor kappa B/nuclear factor kappa B) using Western Blot. Data were analyzed with 2-way (condition × time) repeated-measure ANOVAs with Newman-Keuls post hoc tests. MIP-1β was elevated at 1-Post HYP exercise (+11%; p < 0.01) but did not increase following exercise in NORM. TNF-α/IL-1RA and IL-1β/IL-1RA ratios were both reduced (p < 0.05) following HYP exercise (-16% and -52%, respectively, at 1-Post and -7% and -32%, respectively, at 4-Post). IL-8 increased (p < 0.05) at Post and 1-Post NORM (+33% and +57%, respectively) and HYP (+60% and +83%, respectively) exercise, but was not different between conditions (p > 0.05). Interestingly, plasma sICAM-1 did not increase (p > 0.05) following NORM exercise but was increased (p < 0.05) at Post (+17%), 1-Post (+16%), and 4-Post (+14%) HYP exercise. There was also a delayed peak in plasma MPO concentrations following HYP exercise and PBMC exhibited a reduced (p < 0.05) inflammatory capacity at Post (-38%) and 1-Post (-49%). Novelty Following HYP exercise, participants exhibited (i) circulatory bias towards anti-inflammation; (ii) elevated sICAM; (iii) delayed peak in plasma MPO; and (iv) diminished inflammatory response in PBMC. Collectively, these data suggest immunosuppression. This is undesirable, given that elevated MIP-1β (reported here) and elevated intestinal fatty acid binding protein (reported previously) both suggest higher lipopolysaccharide concentrations following HYP exercise.

Glucose Ingestion Inhibits Endurance Exercise-Induced IL-6 Producing Macrophage Infiltration in Mice Muscle

Background: Carbohydrate (CHO) supplementation during exercise attenuates exercise-induced increases in plasma Interleukin (IL)-6 concentration. However, the effects of CHO supplementation on muscle IL-6 production during endurance exercise is controversial. The purpose of this study was to investigate the effects of CHO supplementation on muscle IL-6 production during endurance exercise with a special focus on the IL-6 producing cells. Methods: C57BL/6J mice were divided into three groups—sedentary with water ingestion group as the control (Con; n = 10), exercise with water ingestion group (Ex; n = 10), and exercise with 6% glucose ingestion group (Ex + glucose; n = 10). The Ex and Ex + glucose groups completed 3 h of treadmill running (24 m/min, 7% incline) and were sacrificed immediately after exercise. Results: The exercise-induced increases of plasma IL-6 concentration and gastrocnemius IL-6 gene expression were attenuated by glucose ingestion. However, the increases of soleus IL-6 gene expression and gastrocnemius and soleus IL-6 protein expression were not attenuated by glucose ingestion. Furthermore, we observed that macrophages that infiltrated muscle produce IL-6 and glucose ingestion attenuated the infiltration of IL-6-producing macrophages. Conclusion: This study revealed that infiltrating macrophages may be one type of IL-6-producing cells during endurance exercise, and the infiltration of these cells in muscle was attenuated by glucose ingestion. However, the effects of glucose ingestion on muscle IL-6 production were limited.

Protective effects of tea polyphenols on exhaustive exercise-induced fatigue, inflammation and tissue damage

Background: The beneficial properties of tea polyphenols have been extensively studied; however, less attention has been paid to their effects, especially anti-inflammatory effect during exhaustive exercise.

Objective: The present study assessed the potential protective effects of tea polyphenols against the fatigue, inflammation and tissue injury caused by an exhaustive exercise bout in rats.

Design: Twenty-four healthy male rats were divided into three groups. Group C was a sedentary control group, Groups E+TP and Group E performed a single exhaustive swimming test; all groups had normal diets, but Group E+TP was supplemented with tea polyphenols. All rats were immediately euthanized after exhaustive exercise, and biochemical and inflammatory parameters, including lactic acid (LA), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), lactic dehydrogenase (LDH), and creatine kinase (CK) activity levels, were measured. Reverse transcription (RT) and Real-Time PCR was employed to evaluate the mRNA expression of IL-1β in the liver.

Results: The results showed a decrease in serum LA levels (22%, p < 0.05) in rats that consumed dietary tea polyphenols. Interestingly, dietary tea polyphenols decreased the serum levels of pro-inflammatory factors (TNF-α: 13%, p < 0.05; IL-1β: 10%, p < 0.05; and IL-6: 48%, p < 0.05) and shifted the serum IL-10/TNF-α ratio to a predominantly anti-inflammatory milieu (0.52 ± 0.07 vs. 0.67 ± 0.10, p < 0.01). Furthermore, the polyphenols effectively inhibited the release of tissue damage markers (CK: 24%, p < 0.05 and LDH: 28%, p < 0.05) in the serum and decreased IL-1β mRNA expression in the liver.

Conclusions: This study indicated that tea polyphenols could significantly protect rats from the fatigue, inflammation and tissue damage induced by acute exhaustive exercise.

Nutritional interventions and the IL-6 response to exercise

IL-6 is a pleiotropic cytokine with a wide range of biologic effects. In response to prolonged exercise, IL-6 is synthesized by contracting skeletal muscle and released into circulation. Circulating IL-6 is thought to maintain energy status during exercise by acting as an energy sensor for contracting muscle and stimulating glucose production. If tissue damage occurs, immune cells infiltrate and secrete cytokines, including IL-6, to repair skeletal muscle damage. With adequate rest and nutrition, the IL-6 response to exercise is attenuated as skeletal muscle adapts to training. However, sustained elevations in IL-6 due to repeated bouts of unaccustomed activities or prolonged exercise with limited rest may result in untoward physiologic effects, such as accelerated muscle proteolysis and diminished nutrient absorption, and may impair normal adaptive responses to training. Recent intervention studies have explored the role of mixed meals or carbohydrate, protein, ω-3 fatty acid, or antioxidant supplementation in mitigating exercise-induced increases in IL-6. Emerging evidence suggests that sufficient energy intake before exercise is an important factor in attenuating exercise-induced IL-6 by maintaining muscle glycogen. We detail various nutritional interventions that may affect the IL-6 response to exercise in healthy human adults and provide recommendations for future research exploring the role of IL-6 in the adaptive response to exercise.-Hennigar, S. R., McClung, J. P., Pasiakos, S. M. Nutritional interventions and the IL-6 response to exercise.

Acute high-intensity interval exercise reduces human monocyte Toll-like receptor 2 expression in type 2 diabetes

Type 2 diabetes (T2D) is characterized by chronic low-grade inflammation that contributes to disease pathophysiology. Exercise has anti-inflammatory effects, but the impact of high-intensity interval training (HIIT) is not known. The purpose of this study was to determine the impact of a single session of HIIT on cellular, molecular, and circulating markers of inflammation in individuals with T2D. Participants with T2D (n = 10) and healthy age-matched controls (HC; n = 9) completed an acute bout of HIIT (7 × 1 min at ~85% maximal aerobic power output, separated by 1 min of recovery) on a cycle ergometer with blood samples obtained before (Pre), immediately after (Post), and at 1 h of recovery (1-h Post). Inflammatory markers on leukocytes were measured by flow cytometry, and TNF-α was assessed in both LPS-stimulated whole blood cultures and plasma. A single session of HIIT had an overall anti-inflammatory effect, as evidenced by 1) significantly lower levels of Toll-like receptor (TLR) 2 surface protein expression on both classical and CD16+ monocytes assessed at Post and 1-h Post compared with Pre (P < 0.05 for all); 2) significantly lower LPS-stimulated TNF-α release in whole blood cultures at 1-h Post (P < 0.05 vs. Pre); and 3) significantly lower levels of plasma TNF-α at 1-h Post (P < 0.05 vs. Pre). There were no differences between T2D and HC, except for a larger decrease in plasma TNF-α in HC vs. T2D (group × time interaction, P < 0.05). One session of low-volume HIIT has immunomodulatory effects and provides potential anti-inflammatory benefits to people with, and without, T2D.

Recovery of the immune system after exercise

The notion that prolonged, intense exercise causes an "open window" of immunodepression during recovery after exercise is well accepted. Repeated exercise bouts or intensified training without sufficient recovery may increase the risk of illness. However, except for salivary IgA, clear and consistent markers of this immunodepression remain elusive. Exercise increases circulating neutrophil and monocyte counts and reduces circulating lymphocyte count during recovery. This lymphopenia results from preferential egress of lymphocyte subtypes with potent effector functions [e.g., natural killer (NK) cells, γδ T cells, and CD8⁺ T cells]. These lymphocytes most likely translocate to peripheral sites of potential antigen encounter (e.g., lungs and gut). This redeployment of effector lymphocytes is an integral part of the physiological stress response to exercise. Current knowledge about changes in immune function during recovery from exercise is derived from assessment at the cell population level of isolated cells ex vivo or in blood. This assessment can be biased by large changes in the distribution of immune cells between blood and peripheral tissues during and after exercise. Some evidence suggests that reduced immune cell function in vitro may coincide with changes in vivo and rates of illness after exercise, but more work is required to substantiate this notion. Among the various nutritional strategies and physical therapies that athletes use to recover from exercise, carbohydrate supplementation is the most effective for minimizing immune disturbances during exercise recovery. Sleep is an important aspect of recovery, but more research is needed to determine how sleep disruption influences the immune system of athletes.

Implications of exercise-induced adipo-myokines in bone metabolism

Physical inactivity has been recognized, by the World Health Organization as the fourth cause of death (5.5 % worldwide). On the contrary, physical activity (PA) has been associated with improved quality of life and decreased risk of several diseases (i.e., stroke, hypertension, myocardial infarction, obesity, malignancies). Bone turnover is profoundly affected from PA both directly (load degree is the key determinant for BMD) and indirectly through the activation of several endocrine axes. Several molecules, secreted by muscle (myokines) and adipose tissues (adipokines) in response to exercise, are involved in the fine regulation of bone metabolism in response to the energy availability. Furthermore, bone regulates energy metabolism by communicating its energetic needs thanks to osteocalcin which acts on pancreatic β-cells and adipocytes. The beneficial effects of exercise on bone metabolism depends on the intermittent exposure to myokines (i.e., irisin, IL-6, LIF, IGF-I) which, instead, act as inflammatory/pro-resorptive mediators when chronically elevated; on the other hand, the reduction in the circulating levels of adipokines (i.e., leptin, visfatin, adiponectin, resistin) sustains these effects as well as improves the whole-body metabolic status. The aim of this review is to highlight the newest findings about the exercise-dependent regulation of these molecules and their role in the fine regulation of bone metabolism.

Effect of acute exercise and hypoxia on markers of systemic and mucosal immunity

Purpose

To determine how immune markers are affected by acute hypoxic exercise at the same relative intensity.

Methods

Twelve endurance-trained males (age: 28 ± 4 years, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2max: 63.7 ± 5.3 mL/kg/min) cycled for 75 min at 70 % of altitude-specific \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2max, once in normoxia (N) and once in hypobaric hypoxia equivalent to 2000 m above sea-level (H). Blood and saliva samples were collected pre-, post- and 2 h post-exercise.

Results

Participants cycled at 10.5 % lower power output in H vs. N, with no significant differences in heart rate (P = 0.10) or rating of perceived exertion (P = 0.21). Post-exercise plasma cortisol was higher in H vs. N [683 (95 % CI 576–810) nmol/l vs. 549 (469–643) nmol/l, P = 0.017]. The exercise-induced decrease in CD4:CD8 ratio was greater in H vs. N (−0.5 ± 0.2 vs. −0.3 ± 0.2, P = 0.019). There were no significant between-trial differences for adrenocorticotropic hormone, plasma cytokines, antigen-stimulated cytokine production, salivary immunoglobulin-A or lactoferrin. However, there was a main trial effect for concentration [F(11) = 5.99, P < 0.032] and secretion [F(11) = 5.01, P < 0.047] of salivary lysozyme, with this being higher in N at every time-point.

Conclusion

Whether the observed differences between H and N are of sufficient magnitude to clinically impair host defence is questionable, particularly as they are transient in nature and since other immune markers are unaffected. As such, acute hypoxic exercise likely does not pose a meaningful additional threat to immune function compared to exercise at sea level, provided that absolute workload is reduced in hypoxia so that relative exercise intensity is the same.

Menstrual cycle phase and carbohydrate ingestion alter immune response following endurance exercise and high intensity time trial performance test under hot conditions

Background

Sex hormones are known to regulate some responses during exercise. Evaluation of the differences in exercise response with regard to menstrual cycle will help understand the menstrual cycle phase specific adaptations to exercise and athletic performance.

Methods

We investigated the effects of menstrual cycle phase and carbohydrate (CHO) ingestion on immune response during endurance exercise at 30°C. Six healthy women completed 4 trials comprising 90 min of cycling at 50% peak aerobic power V˙O2peak and a high intensity time trial performance test (POST). They ingested a placebo- or CHO-containing beverage during the trials, which were performed during both the follicular and luteal phases of the menstrual cycle. In all trials, thermoregulatory, cardiorespiratory, and immune responses were measured during exercise and after POST.

Results

Although the thermoregulatory responses differed between the menstrual cycle phases, the cardiorespiratory responses were not different. After placebo ingestion, leukocyte concentration (cells/μL) at POST (15.9 × 10³) in the luteal phase was significantly higher than that in the follicular phase (12.9 × 10³). The rise in leukocyte concentration was attenuated upon CHO ingestion, and the difference between menstrual cycle phases disappeared. A significant positive correlation was found between leukocyte concentration and serum free fatty acid concentrations. Interleukin-6, calprotectin, and myeloperoxidase concentrations significantly increased at POST in all trials, but no significant differences were observed between menstrual cycle phase or beverage type. Concentrations of other cytokines did not change during exercise in any of the 4 trials. Menstrual cycle phase and beverage type had no significant effect on the POST outcome. Thus, differences in leukocyte mobilization between menstrual cycle phases could result from the effect of sex hormones on substrate utilization.

Conclusions

The menstrual cycle affected circulating leukocyte concentrations during endurance exercise with POST when a placebo was ingested. Therefore, we recommend ingesting CHO beverages to attenuate immune disturbances, especially in the luteal phase, even though they are unlikely to enhance test performance.

Vitamin C supplementation does not influence plasma and blood mononuclear cell IL-6 and IL-10 levels after exercise

The aim of this study was to determine whether the highest vitamin C supplementation associated with complete bioavailability influences the plasma and blood mononuclear cell IL-6 and IL-10 response to exercise. A double-blinded study of supplementation with vitamin C was performed. After 15 days of supplementation with vitamin C (500 mg · day(-1), n = 16) or a placebo (n = 15), participants in the study completed a 15-km run competition. Blood samples were taken before and after competition. Oxidative stress markers, antioxidants, cortisol, IL-6 and IL-10 were determined in plasma or serum. IL-6 and IL-10 protein and mRNA levels were measured in blood mononuclear cells. Although higher plasma and blood mononuclear cell vitamin C levels were observed in the supplemented group when compared with the placebo one, the two groups showed identical exercise-induced changes in all the measured parameters. Exercise induced increased IL-6 and IL-10 levels in plasma and blood mononuclear cells. IL-6 and IL-10 mRNA levels in blood mononuclear cells increased after the competition. After recovery, IL-6 mRNA returned to basal levels and IL-10 mRNA levels remained elevated. In conclusion, exercise induced increased IL-6 and IL-10 production in blood mononuclear cells. However, vitamin C supplementation did not influence IL-6 and IL-10 response to exercise.

Influence of Hydration Status on Changes in Plasma Cortisol, Leukocytes, and Antigen-Stimulated Cytokine Production by Whole Blood Culture following Prolonged Exercise

Elevated antigen-stimulated anti-inflammatory cytokine production appears to be a risk factor for upper respiratory tract illness in athletes. The purpose of this study was to determine the effects of prolonged exercise and hydration on antigen-stimulated cytokine production. Twelve healthy males cycled for 120 min at 60% V˙O2max⁡ on two occasions, either euhydrated or moderately hypohydrated (induced by fluid restriction for 24 h). Blood samples were collected before and after exercise and following 2 h recovery for determination of cell counts, plasma cortisol, and in vitro antigen-stimulated cytokine production by whole blood culture. Fluid restriction resulted in mean body mass loss of 1.3% and 3.9% before and after exercise, respectively. Exercise elicited a significant leukocytosis and elevated plasma cortisol, with no differences between trials. IL-6 production was significantly reduced 2 h postexercise (P < 0.05), while IL-10 production was elevated postexercise (P < 0.05). IFN-γ and IL-2 production tended to decrease postexercise. No significant effect of hydration status was observed for the measured variables. Prolonged exercise appears to result in augmented anti-inflammatory cytokine release in response to antigen challenge, possibly coupled with acute suppression of proinflammatory cytokine production, corresponding with studies using mitogen or endotoxin as stimulant. Moderate hypohydration does not appear to influence these changes.

Muscle as a secretory organ

Skeletal muscle is the largest organ in the body. Skeletal muscles are primarily characterized by their mechanical activity required for posture, movement, and breathing, which depends on muscle fiber contractions. However, skeletal muscle is not just a component in our locomotor system. Recent evidence has identified skeletal muscle as a secretory organ. We have suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert either autocrine, paracrine, or endocrine effects should be classified as "myokines." The muscle secretome consists of several hundred secreted peptides. This finding provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs such as adipose tissue, liver, pancreas, bones, and brain. In addition, several myokines exert their effects within the muscle itself. Many proteins produced by skeletal muscle are dependent upon contraction. Therefore, it is likely that myokines may contribute in the mediation of the health benefits of exercise.

β-Hydroxy-β-methylbutyrate (HMB)-free acid attenuates circulating TNF-α and TNFR1 expression postresistance exercise

The purpose of this study was to examine the effect of β-hydroxy-β-methylbutyrate-free acid (HMB-FA) and cold-water immersion (CWI) on circulating concentrations of TNF-α and monocyte TNF-α receptor 1 (TNFR1) expression. Forty resistance-trained men (22.3 ± 2.4 yr) were randomized into four groups [placebo (PL), HMB-FA, CWI, and HMB-FA-CWI] and performed an acute, intense exercise protocol (four sets of up to 10 repetitions of the squat, dead lift, and split squat). Participants also performed four sets of up to 10 repetitions of the squat at 24 and 48 h following the initial exercise bout. Blood was sampled before exercise (PRE), immediately postexercise (IP), and 30 min, 24 h, and 48 h postexercise (30P, 24P, and 48P, respectively). Circulating TNF-α was assayed, and TNFR1 expression on CD14+ monocytes was measured by flow cytometry. The exercise protocol significantly elevated TNF-α in only PL ( P = 0.006) and CWI ( P = 0.045) IP. Mean percent changes show that TNF-α significantly increased from PRE to IP for only PL and CWI groups ( P < 0.05), whereas the percent change of TNF-α for HMB-FA and HMB-FA-CWI was not significant. TNFR1 expression was elevated in PL ( P = 0.023) and CWI ( P = 0.02) at 30P compared with PRE, whereas both HMB-FA-treated groups did not increase significantly. In conclusion, HMB-FA attenuated circulating TNF-α IP and TNFR1 expression during recovery compared with PL and CWI. HMB-FA supplementation may attenuate the initial immune response to intense exercise, which may reduce recovery time following intense exercise.

The effect of physical activity on mediators of inflammation

Being physically active and undertaking exercise on a regular basis are critical lifestyle behaviours which protect against the development of numerous chronic metabolic conditions. One of the key mechanisms by which physical activity exerts favourable health effects appears to be due to its capacity to reduce chronic low-grade inflammation. Single bouts of exercise have a potent anti-inflammatory influence with recent advances describing important effects of acute exercise on inflammatory mediators produced within skeletal muscle (myokines), adipose tissue (adipokines) and leucocytes. The accumulated effects of physical activity or exercise training on systemic inflammation have been studied widely within epidemiological research; however, information from intervention trials is still emerging. Current data suggest that the most marked improvements in the inflammatory profile are conferred with exercise performed at higher intensities, with combined aerobic and resistance exercise training potentially providing the greatest benefit. The purpose of this review is to describe recent advances in our understanding surrounding the acute and chronic effects of physical activity on key mediators of inflammation. Within this, particular attention is given to the interleukin-6 system owing to its apparent centrality in mediating the anti-inflammatory effects of exercise.

Targeting gp130 to prevent inflammation and promote insulin action

Obesity and type 2 diabetes are now the most prevalent metabolic diseases in the Western world and the development of new strategies to treat these metabolic diseases is most warranted. Obesity results in a state of chronic low-grade inflammation in metabolically active tissues such as the liver, adipose tissue, brain and skeletal muscle. Work in our laboratory has focussed on the role of the cytokine interleukin-6 (IL)-6 and other IL-6-like cytokines that signal through the gp130 receptor complex. We have focussed on the role of blocking IL-6 trans-signalling to prevent inflammation on the one hand, and activating membrane-bound signalling to promote insulin sensitivity on the other hand. Since the cloning of the IL-6 gene nearly 30  years ago, a pattern has emerged associating IL-6 with a number of diseases associated with inflammation including rheumatoid arthritis (RA), Crohn's disease and several cancers. Accordingly, tocilizumab, an IL-6 receptor-inhibiting monoclonal antibody, is now useful for the treatment of RA. However, this may not be the most optimal strategy to block inflammation associated with IL-6 and may result in unwanted side effects that, paradoxically, could actually promote metabolic disease.

Interleukin-6 myokine signaling in skeletal muscle: a double-edged sword?

Interleukin (IL)-6 is a cytokine with pleiotropic functions in different tissues and organs. Skeletal muscle produces and releases significant levels of IL-6 after prolonged exercise and is therefore considered as a myokine. Muscle is also an important target of the cytokine. IL-6 signaling has been associated with stimulation of hypertrophic muscle growth and myogenesis through regulation of the proliferative capacity of muscle stem cells. Additional beneficial effects of IL-6 include regulation of energy metabolism, which is related to the capacity of actively contracting muscle to synthesize and release IL-6. Paradoxically, deleterious actions for IL-6 have also been proposed, such as promotion of atrophy and muscle wasting. We review the current evidence for these apparently contradictory effects, the mechanisms involved and discuss their possible biological implications.

Cancer cachexia prevention via physical exercise: molecular mechanisms

Cancer cachexia is a debilitating consequence of disease progression, characterised by the significant weight loss through the catabolism of both skeletal muscle and adipose tissue, leading to a reduced mobility and muscle function, fatigue, impaired quality of life and ultimately death occurring with 25-30 % total body weight loss. Degradation of proteins and decreased protein synthesis contributes to catabolism of skeletal muscle, while the loss of adipose tissue results mainly from enhanced lipolysis. These mechanisms appear to be at least, in part, mediated by systemic inflammation. Exercise, by virtue of its anti-inflammatory effect, is shown to be effective at counteracting the muscle catabolism by increasing protein synthesis and reducing protein degradation, thus successfully improving muscle strength, physical function and quality of life in patients with non-cancer-related cachexia. Therefore, by implementing appropriate exercise interventions upon diagnosis and at various stages of treatment, it may be possible to reverse protein degradation, while increasing protein synthesis and lean body mass, thus counteracting the wasting seen in cachexia.

Interleukin-6: possible biological roles during exercise

Interleukin-6 (IL-6) is a multifunctional cytokine that exerts its modulatory effects on cells that express membrane bound IL-6 receptors; however, IL-6 in a complex with soluble IL-6R can bind to any cell that express glycoprotein 130 (gp130). Thus, all cell types may respond to the pro- as well as anti-inflammatory properties of IL-6. Since the first report of acute exercise-induced increase in plasma IL-6 in the early 1990s, scientists have tried to elucidate the factors that influence the magnitude of change of plasma IL-6, as well as the possible biological roles of this cytokine. Evidence suggests that exercise intensity and duration as well as the form of contraction (e.g., eccentric or concentric) and muscle damage all influence IL-6 response to acute exercise. However, data on training status and performance on plasma IL-6 concentration changes during exercise are more inconclusive, as discussed in this review. In the last decade, most of the studies have focused on IL-6 as an 'energy sensor' possibly secreted by skeletal muscle that activates glycogenolysis in the liver and lipolysis in fat tissue in order to provide muscle with the growing energy demands during exercise.

Muscles, exercise and obesity: skeletal muscle as a secretory organ

During the past decade, skeletal muscle has been identified as a secretory organ. Accordingly, we have suggested that cytokines and other peptides that are produced, expressed and released by muscle fibres and exert either autocrine, paracrine or endocrine effects should be classified as myokines. The finding that the muscle secretome consists of several hundred secreted peptides provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs, such as adipose tissue, liver, pancreas, bones and brain. However, some myokines exert their effects within the muscle itself. Thus, myostatin, LIF, IL-6 and IL-7 are involved in muscle hypertrophy and myogenesis, whereas BDNF and IL-6 are involved in AMPK-mediated fat oxidation. IL-6 also appears to have systemic effects on the liver, adipose tissue and the immune system, and mediates crosstalk between intestinal L cells and pancreatic islets. Other myokines include the osteogenic factors IGF-1 and FGF-2; FSTL-1, which improves the endothelial function of the vascular system; and the PGC-1α-dependent myokine irisin, which drives brown-fat-like development. Studies in the past few years suggest the existence of yet unidentified factors, secreted from muscle cells, which may influence cancer cell growth and pancreas function. Many proteins produced by skeletal muscle are dependent upon contraction; therefore, physical inactivity probably leads to an altered myokine response, which could provide a potential mechanism for the association between sedentary behaviour and many chronic diseases.

Peripheral signals of energy homeostasis as possible markers of training stress in athletes: a review

The importance of physical exercise in regulating energy balance and ultimately body mass is widely recognized. There have been several investigative efforts in describing the regulation of the energy homeostasis. Important in this regulatory system is the existence of several peripheral signals that communicate the status of body energy stores to the hypothalamus including leptin, adiponectin, ghrelin, interleukin-6, interleukin-1β, and tumor necrosis factor-α--different cytokines and other peptides that affect energy homeostasis. In certain circumstances, all these peripheral signals may be used to reveal the condition of the athlete as the result of several months of prolonged exercise training. These hormone and cytokine concentrations characterize a physical stress condition in which different hormone and cytokine responses are apparently linked to changes in physical performance. The possibility to use these peripheral signals as markers of training stress (and possible overreaching/overtraining) in elite athletes should be considered. These measured hormone and cytokine levels could also be used to characterize the physical stress of single exercise session, as the hormone and cytokine response to exercise may actually be a response to the concurrent energy deficit. In summary, different peripheral signals of energy homeostasis may be sensitive to changes in specific training stress and may be useful for predicting the onset of possible overreaching/overtraining in athletes.

The melanocortin 3 receptor: a novel mediator of exercise-induced inflammation reduction in postmenopausal women?

The purpose of this study was to determine whether resistance exercise training-induced reductions in inflammation are mediated via melanocortin 3 receptor expression in obese (BMI 32.7 ± 3.7) women (65.6 ± 2.8 yrs) randomized to either a control (N = 11) or resistance training group (N = 12). The resistance trained group performed resistance training 3 days/week for 12 weeks. Resting blood samples were collected before and after the training intervention in both resistance trained and control groups. Resistance training upregulated melanocortin 3 receptor mRNA by 16-fold (P = .035) and decreased monocyte count, without changing leukocyte number, body composition, or body weight. Resistance trained individuals exhibited increased sensitivity to inflammatory stimuli, whereas control individuals exhibited no change. While there was no change in whole blood tumor necrosis factor alpha mRNA between the groups, whole blood interleukin 10 mRNA was higher in the resistance trained group following the intervention period. In summary, it appears that resistance training may modulate melanocortin 3 receptor expression, providing a possible mechanism for the anti-inflammatory effects of exercise training.

Comparison the Effect of One Session Submaximal Exercise on Plasma Levels of IL6 and TNF- a in Obese and Non-Obese Women

BACKGROUND

Cytokines are a group of low-molecular-weight regulatory proteins that produced by cells in response to stimulation. In fact, they increase in response to immune system during exercise. Also, many cytokines such as IL-6 and TNFα are secreted from adipose tissue in obese people. So the aim of this study was to investigate the effect of one session submaximal exercise on plasma levels of IL6 and TNFα in obese and non-obese women.

METHODS

Sixteen healthy women aged 20-30 years old participated in the study. Subjects were classified into obese (n=8) and nonobese (n=8) groups who performed submaximal exercise program (50-65% HRM) for 30minutes. Blood samples were taken for cytokines measurement, before and after exercise. Data were analyzed with SPSS15. The effect of exercise on mentiones variables was evaluated using t-test and covariance test.

RESULTS

Level of IL-6 increased significantly in two studied groups after 30 minutes submaximal exercise (P<0.05). Levels of TNFα increased significantly in obese subjects but not in non-obese subjects. There were no significant changes in the levels of IL-6 and TNFα after 30 minutes submaximal exercise between two studied groups (P>0.05).

CONCLUSION

After submaximal exercise, plasma level of IL6 and TNFα may increase and adipose tissue is the main source of circulating IL6 and TNFα.

Source and kinetics of interleukin-6 in humans during exercise demonstrated by a minimally invasive model

The objective of this study was to use a novel and non-invasive model to explore whether: (1) exercise-induced increases in systemic levels of interleukin-6 (IL-6) and other cytokines can be ascribed to local production in working muscle; and (2) how acute release of retained blood from an exercised limb impacts on metabolites in the systemic circulation. On two experimental days, at least 3 weeks apart, six healthy moderately trained male subjects performed one-legged knee-extensor exercise for 2 h at 60% of their maximal workload. On one occasion venous outflow from the exercised leg was inhibited for 18 min by inflating a cuff around the thigh as proximally as possible immediately following exercise. On the control occasion venous outflow was not inhibited. Venous blood samples were collected from an arm vein at 2-min intervals after exercise. During inhibition of venous outflow from the exercised leg systemic plasma levels of IL-6 decreased within minutes to near pre-exercise levels, whereas plasma glucose levels increased to higher levels than without the cuff. After release of the cuff, systemic levels of IL-6 increased rapidly to match levels on the control occasion. On release of the cuff, plasma levels of free fatty acids (FFAs) declined more than without the cuff. In conclusion, the observed increase in systemic IL-6 plasma concentrations during exercise can be attributed to release from the working limb. Other potential sources of IL-6 outside the working limb do not contribute significantly to the increase in plasma IL-6 levels during exercise.

Physical activity, immunity and infection

During the last few decades, scientific evidence has confirmed a wide range of health benefits related to regular physical activity. How physical activity affects the immune function and infection risk is, however, still under debate. Commonly, intensive exercise suppresses the activity and levels of several immune cells, while other immune functions may be stimulated by moderate physical activity. With this knowledge, the understanding of the relationship between different levels of physical activity on the immune function has been raised as a potential tool to protect health not only in athletes but also in the general population; the mechanisms that translate a physically active lifestyle into good health continue to be investigated. Reviewing the literature, although several outcomes (i.e. the mechanisms by which different levels and duration of physical activity programmes affect numerous cell types and responses) remain unclear, given that the additional benefits encompass healthy habits including exercise, the use of physical activity programmes may result in improved health of elderly populations. Moderate physical activity or moderate-regulated training may enhance the immune function mainly in less fit subjects or sedentary population and the pre-event fitness status also seems to be an important individual factor regarding this relationship. Although adequate nutrition and regular physical activity habits may synergistically improve health, clinical trials in athletes using nutritional supplements to counteract the immune suppression have been inconclusive so far.Further research is necessary to find out to what extent physical activity training can exert an effect on the immune function.

Expression of intracellular cytokines, HSP72, and apoptosis in monocyte subsets during exertional heat stress in trained and untrained individuals

This study examined intracellular cytokine, heat shock protein (HSP) 72, and cellular apoptosis in classic and inflammatory CD14+monocyte subsets during exertional heat stress (EHS). Subjects were divided into endurance-trained [TR; n = 12, peak aerobic power (V̇o2peak) = 70 ± 2 ml·kg lean body mass (LBM)−1·min−1] and sedentary-untrained (UT; n = 11, V̇o2peak= 50 ± 1 ml·kg LBM−1·min−1) groups before walking at 4.5 km/h with 2% elevation in a climatic chamber (40°C, 30% relative humidity) wearing protective clothing until exhaustion (Exh). Venous blood samples at baseline and 0.5°C rectal temperature increments (38.0, 38.5, 39.0, 39.5, and 40.0°C/Exh) were analyzed for cytokines (TNF-α, IL-1β, IL-6, IL-1ra, and IL-10) in CD14++CD16−/CD14+CD16+and HSP72/apoptosis in CD14Bri/CD14Dimsubsets. In addition, serum levels of extracellular (e)HSP72 were also examined. Baseline and Exh samples were separately stimulated with LPS (1 μg/ml) or heat shocked (42°C) and cultured in vitro for 2 h. A greater temperature-dependent increase in CD14+CD16+cells was observed in TR compared with UT subjects as well as a greater LPS tolerance following in vitro LPS stimulation. TNF-α and IL-1β cytokine expression was elevated in CD14+CD16+but not in CD14++CD16−cells. A greater induction of intracellular HSP72 and eHSP72 was observed in TR compared with UT subjects, which coincided with reduced apoptosis at Exh and following in vitro heat shock. Induced HSP in vitro was not uniform across CD14+subsets. Findings suggest that circulating CD14+CD16+, but not CD14++CD16−monocytes, contribute to the proinflammatory cytokine profiles observed during EHS. In addition, the enhanced HSP72 response in endurance-trained individuals may confer improved heat tolerance through both anti-inflammatory and anti-apoptotic mechanisms.

CD33+ CD14- phenotype is characteristic of multinuclear osteoclast-like cells in giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a benign bone tumor with a shown clinical behavior of local recurrences and rare distant metastases. GCTB is composed of uniformly distributed osteoclastic giant cells, thought to originate from the fusion of monocyte-macrophage lineage cells, in a background consisting of mononuclear rounded cells and spindle-shaped cells. Several reports showed the specific expression of markers, such as CD14 on the mononuclear rounded cell population, however, lacking osteoclastic giant cells. Blood monocytes that were CD14+, CD33+, or CD14+/CD33+ have also been shown to be programmed as pre-osteoclasts. The macrophage marker CD33 is expressed earlier than CD14 in macrophage maturation, whereas CD14 is expressed longer than CD33. The aim of this study was to investigate CD14/CD33 expression profiles in GCTB. Nineteen GCTB tumor samples of 19 patients were studied. Immunofluorescent analyses were performed with monoclonal antibodies against CD14, CD33, RANK, and CD51. To unambiguously further prove the expression of these molecules, quantitative RT-PCR was used with subsequent sequencing of its products. All samples showed similar immunoreactivity profiles. The mononuclear rounded cell population was positive for RANK, CD51, CD14, and CD33. The osteoclastic giant cell population expressed RANK and CD51, as well as CD33, but was consistently negative for CD14 expression. The CD14 and CD33 profiles were confirmed by quantitative RT-PCR. These RT-PCR products were sequence verified. Osteoclasts in GCTB are the result of fusion of CD33-expressing pre-osteoclasts that further fuse with CD14+ mononuclear cells. Although these results reflect a static rather than a dynamic spectrum, we strongly believe that osteoclastogenesis seems not to be the exclusive result of fusion of intratumoral CD14+ mononuclear cells. Moreover, CD33-modulated osteoclastogenesis opens up the possibility for novel therapeutic directions.

Muscle as an endocrine organ: focus on muscle-derived interleukin-6

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. However, the first identified and most studied myokine is the gp130 receptor cytokine interleukin-6 (IL-6). IL-6 was discovered as a myokine because of the observation that it increases up to 100-fold in the circulation during physical exercise. Identification of IL-6 production by skeletal muscle during physical activity generated renewed interest in the metabolic role of IL-6 because it created a paradox. On one hand, IL-6 is markedly produced and released in the postexercise period when insulin action is enhanced but, on the other hand, IL-6 has been associated with obesity and reduced insulin action. This review focuses on the myokine IL-6, its regulation by exercise, its signaling pathways in skeletal muscle, and its role in metabolism in both health and disease.

Effect of spaceflight on ability of monocytes to respond to endotoxins of gram-negative bacteria

Astronauts live and work in relatively crowded, confined environments on the Space Shuttle and the International Space Station. They experience a unique set of stressors that contribute to a diminishment of many immune responses. This study investigated the ability of the shuttle crew members' monocytes to respond to gram-negative endotoxin that they could encounter during infections. Blood specimens were collected from 20 crew members and 15 control subjects 10 days before launch, 3 to 4 h after landing, and 15 days after landing and from crew members during their annual medical examination at 6 to 12 months after landing. When challenged with gram-negative endotoxin, the crew member's monocytes collected at all three time points produced lower levels of interleukin-6 (IL-6) and IL-1beta and higher levels of IL-1ra and IL-8 compared to those of control subjects. Cytokines were assessed by measuring the number of cells positive for intracellular cytokines. These values returned to normal 6 to 12 months after landing, except for IL-1ra, which was still higher (five- to sixfold) than in controls. This phenomenon was accompanied by an increased expression of Toll-like receptor 4 and decreased expression of CD14 on the crew members' monocytes at all time points. There were also increased levels of the lipopolysaccharide binding protein in the plasma of the crew members 3 to 4 h and 15 days after landing. This study shows that spaceflight-associated factors (in-flight and preflight) modulate the response of monocytes to gram-negative endotoxins.

The metabolic role of IL-6 produced during exercise: is IL-6 an exercise factor?

For most of the last century, researchers have searched for a muscle contraction-induced factor that mediates some of the exercise effects in other tissues such as the liver and the adipose tissue. It has been called the ‘work stimulus’, the ‘work factor’ or the ‘exercise factor’. In the search for such a factor, a cytokine, IL-6, was found to be produced by contracting muscles and released into the blood. It has been demonstrated that IL-6 has many biological roles such as: (1) induction of lipolysis; (2) suppression of TNF production; (3) stimulation of cortisol production. The IL-6 gene is rapidly activated during exercise, and the activation of this gene is further enhanced when muscle glycogen content is low. In addition, carbohydrate supplementation during exercise has been shown to inhibit the release of IL-6 from contracting muscle. Thus, it is suggested that muscle-derived IL-6 fulfils the criteria of an exercise factor and that such classes of cytokines could be termed ‘myokines’.

Exercise and the inflammatory response in chronic obstructive pulmonary disease (COPD)—Does training confer anti-inflammatory properties in COPD?

There is increasing evidence that systemic inflammation plays an important role in the pathogenesis of COPD. Inflammatory markers show relationships with exercise performance, health related quality of life and breathlessness. These are important clinical outcomes in the management of COPD. Even more so is the consideration that systemic inflammation in COPD may be directly associated with mortality and deterioration of disease. Long-term exercise training clearly has beneficial properties in healthy subjects, whether the same is true in COPD remains to be seen. This review discusses aspects of the anti-inflammatory effects of exercise in relation to patients with COPD. There is intriguing evidence that the exercise-induced cytokine response differs in COPD patients compared with healthy subjects. We consider the role of IL-6 in the manifestation of fatigue in COPD and consider the implications of raised CRP- and TNF-alpha. Early data suggests beneficial effects of polyunsaturated fatty acid PUFA supplementation and exercise training in combination with appropriate nutritional support may yield rewarding therapeutic benefits. This review raises the hypothesis that physical training in COPD is associated with immunological changes that may confer anti-inflammatory benefits and in part, explain changes seen after pulmonary rehabilitation in COPD patients.

Increased inflammatory response of blood cells to repeated bout of endurance exercise

PURPOSE

The aim of the present study was to assess the effects of two 30-min consecutive exercise bouts on a treadmill at 80% VO2max separated by a 4-h rest interval, on blood cell counts and the production of tissue factor, cytokines, and eicosanoids in lipopolysaccharide (LPS)-stimulated blood.

METHODS

Blood samples were taken from eight endurance athletes (mean+/-SD: age, 23.4+/-1.6 yr; VO2max, 66.0+/-6.4 L.min.kg), both immediately before and after each exercise bout. Cell counts were performed, and the heparinized blood was subjected to LPS-stimulation for 2 h.

RESULTS

There was a significant rise in white blood cell counts after the first exercise bout (81%, P<0.001), increasing to 123% (P<0.001) after the second bout. After the first and second runs, the tissue factor activity in LPS-stimulated monocytes was enhanced by 70% (not significant) and almost 200% (P=0.012), respectively, compared with baseline values. The high monocyte responsiveness after the second bout remained undiminished 2 h later. Similarly, the interleukin (IL)-8 production had risen 70% (P=0.022) after the first run and 100% (P=0.005) after the second run, relative to baseline values. IL-6 or leukotriene B4 levels did not change significantly. The rise in LPS-induced thromboxane B2 was 80% (P=0.024) after the first run and 63% after the second run (P=0.071, not significant). VO2max correlated negatively with the concentration of granulocytes immediately after the second exercise bout (R=0.864, P=0.006).

CONCLUSIONS

The results of this study are evidence that two physical exercise bouts separated by a 4-h rest are associated with an enhanced propensity of the blood cells to generate tissue factor activity and some proinflammatory products compared with one exercise bout.