Attenuation of T-lymphocyte demargination and adhesion molecule expression in response to moderate exercise in physically fit individuals

Effects of Caloric Intake and Aerobic Activity in Individuals with Prehypertension and Hypertension on Levels of Inflammatory, Adhesion and Prothrombotic Biomarkers-Secondary Analysis of a Randomized Controlled Trial

Background: Cardiopulmonary fitness and low calorie diets have been shown to reduce inflammation but few studies have been conducted in individuals with elevated blood pressure (BP) in a randomized intervention setting. Thereby, adhesion biomarkers, e.g., soluble intercellular adhesion molecule (sICAM)-3, have not been examined so far. Methods: Sixty-eight sedentary prehypertensive and mildly hypertensive individuals (mean age ± SEM: 45 ± 1 years; mean BP: 141/84 ± 1/1 mmHg) were randomized to one of three 12-week intervention groups: cardio training and caloric reduction, cardio training alone, or wait-list control group. Plasma levels of inflammatory, adhesion and prothrombotic biomarkers were assessed. In a second step, intervention groups were combined to one sample and multivariate regression analyses were applied in order to account for exercise and diet behavior changes. Results: There were no significant differences among the intervention groups. In the combined sample, greater caloric reduction was associated with a larger increase of sICAM-3 (p = 0.026) and decrease of C-reactive protein (p = 0.018) as a result of the interventions. More cardio training was associated with increases of sICAM-3 (p = 0.046) as well as interleukin-6 (p = 0.004) and a decrease of tumor necrosis factor-α (p = 0.017) levels. Higher BP predicted higher plasminogen activator inhibitor (PAI)-1 (p = 0.001), and greater fitness predicted lower PAI-1 levels (p = 0.006) after the intervention. Conclusions: In prehypertensive and hypertensive patients, plasma levels of the adhesion molecule sICAM-3 and inflammatory biomarkers have different response patterns to cardio training with and without caloric reduction. Such anti-inflammatory and anti-thrombotic effects may have implications for the prevention of atherothrombotic cardiovascular disease among individuals at increased risk.

An attempt to induce an immunomodulatory effect in rowers with spirulina extract

Background

The aim of this study was to analyze the response of selected components of the immune system in rowers to maximal physical exercise, and to verify if this response can be modulated by supplementation with spirulina (cyanobacterium Spirulina platensis).

Method

The double-blind study included 19 members of the Polish Rowing Team. The subjects were randomly assigned to the supplemented group (n = 10), receiving 1500 mg of spirulina extract for 6 weeks, or to the placebo group (n = 9). The participants performed a 2000-m test on a rowing ergometer at the beginning (1st examination) and at the end of the supplementation period (2nd examination). Blood samples were obtained from the antecubital vein prior to each exercise test, 1 min after completing the test, and after a 24-h recovery period. Subpopulations of T regulatory lymphocytes (Tregs) [CD4+/CD25+/CD127-], cytotoxic lymphocytes (CTLs) [CD8+/TCRαβ+], natural killer (NK) cells [CD3-/CD16+/CD56+] and TCRδγ-positive (Tδγ) cells were determined by means of flow cytometry.

Results

On the 2nd examination, athletes from the supplemented group showed neither a post-exercise increase in Treg count nor a post-recovery decrease in Tδγ cell count (both observed in the placebo group), and presented with significantly lower values of Treg/CTL prior to and after the exercise. During the same examination, rowers from the placebo group showed a significant post-recovery increase in Treg/(NK + Tδγ + CTL) ratio, which was absent in the supplemented group.

Conclusion

The results of this study imply that supplementation with spirulina extract may protect athletes against a deficit in immune function (especially, anti-infectious function) associated with strenuous exercise, and may cause a beneficial shift in "overtraining threshold" preventing a radical deterioration of immunity.

Maximal exercise increases mucosal associated invariant T cell frequency and number in healthy young men

PURPOSE

Mucosal associated invariant T (MAIT) cells have properties of the innate and acquired immune systems. While the response to vigorous exercise has been established for most leukocytes, MAIT cells have not been investigated. Therefore, the purpose was to determine if MAIT cell lymphocytosis occurs with acute maximal aerobic exercise and if this response is influenced by exercise duration, cardiovascular fitness, or body composition.

METHODS

Twenty healthy young males with moderate fitness levels performed an extended graded exercise test until volitional fatigue. Peripheral blood mononuclear cells were isolated from venous blood obtained prior and immediately after exercise and were labeled to identify specific T cell populations using flow cytometry.

RESULTS

The percentage of MAIT cells relative to total T cells significantly increased from 3.0 to 3.8% and absolute MAIT cell counts increased by 2.2-fold following maximal exercise. MAIT cell subpopulation proportions were unchanged with exercise. Within cytotoxic T lymphocytes (CTL), MAIT cells consisted of 8% of these cells and this remained constant after exercise. MAIT cell counts and changes with exercise were not affected by body composition, VO_2peak, or exercise duration.

CONCLUSIONS

Maximal exercise doubled MAIT cell numbers and showed preferential mobilization within total T cells but the response was not influenced by fitness levels, exercise duration, or body composition. These results suggest that acute exercise could be used to offset MAIT cell deficiencies observed with certain pathologies. MAIT cells also make up a substantial proportion of CTLs, which may have implications for cytotoxicity assays using these cells.

Immunological effects of behavioral activation with exercise in major depression: an exploratory randomized controlled trial

Major depression (MD) is associated with peripheral inflammation and increased cardiovascular risk. Regular physical exercise can have anti-inflammatory effects. The present study examined whether behavioral activation with exercise affects inflammatory processes in MD. Ninety-eight patients with MD were randomly assigned to cognitive-behavioral therapy (CBT) emphasizing exercise during behavioral activation (CBT-E), CBT with pleasurable low-energy activities as an active control condition (CBT-C) or a passive waiting list control group (WL). Plasma levels of C-reactive protein (CRP), interleukin (IL)-6, IL-10, lipopolysaccharide (LPS)-stimulated IL-6 production, and blood immune cell counts were analyzed at baseline and weeks 8 (post-behavioral activation) and 16 (post-treatment). Thirty non-depressed age- and sex-matched controls were included to examine potential immunological alterations in MD at baseline. Patients with MD exhibited higher levels of CRP, higher neutrophil and monocyte counts, lower IL-10 levels and reduced LPS-stimulated IL-6 production compared to controls (P<0.001-0.045). Multilevel modeling indicated that CBT-E was associated with increased anti-inflammatory IL-10 at weeks 8 and 16 compared to CBT-C and WL (P=0.004-0.018). CBT-E did not significantly affect other immunological makers in the total sample. A subgroup analysis including patients with potentially higher cardiovascular risk (CRP ⩾1 μg ml^-1) indicated that CRP was reduced in CBT-E compared to CBT-C (P<0.007) and marginally reduced compared to WL (P<0.085) after week 16. The present findings provide new insights into immunological effects of behavioral treatments against depression. Behavioral activation in conjunction with exercise may have the potential to reverse, in part, immunological alterations in MD.

Inflammation and exercise: Inhibition of monocytic intracellular TNF production by acute exercise via β2-adrenergic activation

Regular exercise is shown to exert anti-inflammatory effects, yet the effects of acute exercise on cellular inflammatory responses and its mechanisms remain unclear. We tested the hypothesis that sympathoadrenergic activation during a single bout of exercise has a suppressive effect on monocytic cytokine production mediated by β₂ adrenergic receptors (AR). We investigated the effects of 20-min moderate (65-70% VO₂ peak) exercise-induced catecholamine production on LPS-stimulated TNF production by monocytes in 47 healthy volunteers and determined AR subtypes involved. We also examined the effects of β-agonist isoproterenol and endogenous β- and α-agonists epinephrine and norepinephrine, and receptor-subtype-specific β- and α-antagonists on TNF production in a series of in vitro investigations. LPS-stimulated TNF production by peripheral blood monocytes was determined intracellularly by flow cytometry, using an intracellular protein transport inhibitor. Percent TNF-producing monocytes and per-cell TNF production with and without LPS was suppressed by exercise with moderate to large effects, which was reversed by a β₂-AR antagonist in spite that plasma TNF levels did not change. This inhibitory response in TNF production by exercise was mirrored by β-AR agonists in an agonist-specific and dose-dependent manner in vitro: similar isoproterenol (EC₅₀=2.1-4.7×10^-10M) and epinephrine (EC₅₀=4.4-10×10^-10M) potency and higher norepinephrine concentrations (EC₅₀=2.6-4.3×10^-8M) needed for the effects. Importantly, epinephrine levels observed during acute exercise in vivo significantly inhibited TNF production in vitro. The inhibitory effect of the AR agonists was abolished by β₂-, but not by β₁- or α-AR blockers. We conclude that the downregulation of monocytic TNF production during acute exercise is mediated by elevated epinephrine levels through β₂-ARs. Decreased inflammatory responses during acute exercise may protect against chronic conditions with low-grade inflammation.

Acute bouts of exercise induce a suppressive effect on lymphocyte proliferation in human subjects: A meta-analysis

OBJECTIVE

Lymphocyte proliferative responses are commonly used to assess immune function in clinical settings, yet it is unclear how proliferative capacity is altered by exercise. This analysis aims to quantitatively assess the proliferative response of lymphocytes following an acute bout of exercise.

METHODS

Electronic databases were searched for articles containing the keywords "exercise" OR "acute" OR "aerobic" OR "resistance training" OR "immune function" AND "proliferation" AND "lymphocyte." Initial results yielded 517 articles of which 117 were reviewed in full. Twenty-four articles met the inclusion criteria. Calculated standardized mean difference (SMD) and corresponding standard errors (SE) were integrated using random-effect models.

RESULTS

Analyses uncovered evidence for suppression of proliferative capacity following acute exercise in general (SMD=-0.18, 95% CI: -0.21, -0.16) with long duration, high intensity exercise exhibiting a moderate suppressive effect (SMD=-0.55, 95% CI: -0.86, -0.24). Discordant proliferative responses for long duration, high intensity exercise in competitive versus non-competitive settings were identified with enhanced proliferation (SMD=0.46, 95% CI: 0.03, 0.89) observed following competitive events and a large suppressive effect detected for similar activities outside of a competitive environment (SMD: -1.28, 95% CI: -1.61, -0.96) (p=0.02).

CONCLUSION

Evidence suggests lymphocyte proliferation is suppressed following acute bouts of exercise, with exercise lasting longer than one hour having a greater magnitude of effect regardless of exercise intensity. Variations in observed effect sizes across intensity, duration, and competitive environment further highlight our need to acknowledge the impact of study designs in advancing our understanding of exercise immunology.

Beta-adrenergic receptor mediated inflammation control by monocytes is associated with blood pressure and risk factors for cardiovascular disease

Overwhelming data indicate that individuals with even mildly elevated blood pressure (BP) are at great risk for developing clinical hypertension and future cardiovascular disease (CVD). There remains a lack of consensus regarding treatment strategies for mildly elevated BP, termed prehypertension, and the knowledge of pathophysiology and mechanisms of its clinical outcomes remains limited. Our primary aim was to investigate βAR-mediated inflammation control (BARIC) responses of blood monocytes to isoproterenol (Iso) in relation to BP and CVD risk factors, including obesity, depressive mood, fasting glucose, triglycerides, and cholesterol levels in the 64 prehypertensive compared to 84 individuals with normal BP. BARIC was determined by measuring the degree of inhibition in lipopolysaccharides-stimulated monocytic intracellular TNF production by ex vivo Iso treatment (10(-8)M). Depressive mood was assessed by Beck Depression Inventory (BDI). Fasting metabolic and lipid panels were assessed, and plasma levels of inflammatory cytokines TNF, IL-1β, IL-6 were measured in a subset to confirm proinflammatory state of prehypertensive participants. Prehypertensive participants were older, heavier, included more men, and presented higher levels of fasting glucose, triglycerides, cholesterol, and plasma TNF compared to normotensive participants (p's<.05). BARIC was significantly attenuated in the prehypertensive compared to normotensive group (p<.05). BARIC was negatively associated with systolic BP, diastolic BP, age, BMI, fasting glucose, triglycerides, total and low density cholesterol levels, and somatic depressive symptoms in all participants (p's<.0001 to .05). However, among the prehypertensive individuals BARIC was positively associated with SBP even after controlling for the covariates (age, gender, race, BMI, glucose and lipid panel, somatic BDI scores) (p<.05). This differing nature of the BARIC-SBP relationship between the two BP groups may be attributed to moderating factors such as cardiorespiratory fitness or depressive symptoms that could not be clearly deciphered in this current study. Nonetheless, our findings indicate the associations between inflammation dysregulation mediated by sympathoadrenal activation and BP that is observable even among individuals with normal to mildly elevated BP. BARIC may be a useful and sensitive indicator of elevated risk for vascular inflammatory disease that can be detected even at lower BP levels, especially given its associations with traditional CVD risk factors and the critical role of monocytes in atherogenic processes.

Acute immunomodulatory effects of binge alcohol ingestion

BACKGROUND

Blood alcohol is present in a third of trauma patients and has been associated with organ dysfunction. In both human studies and in animal models, it is clear that alcohol intoxication exerts immunomodulatory effects several hours to days after exposure, when blood alcohol is no longer detectable. The early immunomodulatory effects of alcohol while blood alcohol is still elevated are not well understood.

METHODS

Human volunteers achieved binge alcohol intoxication after high-dose alcohol consumption. Blood was collected for analysis prior to alcohol ingestion, and 20 min, 2 h, and 5 h after alcohol ingestion. Flow cytometry was performed on isolated peripheral blood mononuclear cells, and cytokine generation in whole blood was measured by enzyme-linked immunosorbent assay (ELISA) after 24-h stimulation with lipopolysaccharide (LPS) and phytohemagglutinin-M (PHA) stimulation.

RESULTS

An early pro-inflammatory state was evident at 20 min when blood alcohol levels were ∼130 mg/dL, which was characterized by an increase in total circulating leukocytes, monocytes, and natural killer cells. During this time, a transient increase in LPS-induced tumor necrosis factor (TNF)-α levels and enhanced LPS sensitivity occurred. At 2 and 5 h post-alcohol binge, an anti-inflammatory state was shown with reduced numbers of circulating monocytes and natural killer cells, attenuated LPS-induced interleukin (IL)-1β levels, and a trend toward increased interleukin (IL)-10 levels.

CONCLUSIONS

A single episode of binge alcohol intoxication exerted effects on the immune system that caused an early and transient pro-inflammatory state followed by an anti-inflammatory state.

Social defeat promotes a reactive endothelium in a brain region-dependent manner with increased expression of key adhesion molecules, selectins and chemokines associated with the recruitment of myeloid cells to the brain

Repeated social defeat (RSD) in mice causes myeloid cell trafficking to the brain that contributes to the development of prolonged anxiety-like behavior. Myeloid cell recruitment following RSD occurs in regions where neuronal and microglia activation is observed. Thus, we hypothesized that crosstalk between neurons, microglia, and endothelial cells contributes to brain myeloid cell trafficking via chemokine signaling and vascular adhesion molecules. Here we show that social defeat caused an exposure- and brain region-dependent increase in several key adhesion molecules and chemokines involved in the recruitment of myeloid cells. For example, RSD induced distinct patterns of adhesion molecule expression that may explain brain region-dependent myeloid cell trafficking. VCAM-1 and ICAM-1 mRNA expression were increased in an exposure-dependent manner. Furthermore, RSD-induced VCAM-1 and ICAM-1 protein expression were localized to the vasculature of brain regions implicated in fear and anxiety responses, which spatially corresponded to previously reported patterns of myeloid cell trafficking. Next, mRNA expression of additional adhesion molecules (E- and P-selectin, PECAM-1) and chemokines (CXCL1, CXCL2, CXCL12, CCL2) were determined in the brain. Social defeat induced an exposure-dependent increase in mRNA levels of E-selectin, CXCL1, and CXCL2 that increased with additional days of social defeat. While CXCL12 was unaffected by RSD, CCL2 expression was increased by six days of social defeat. Last, comparison between enriched CD11b(+) cells (microglia/macrophages) and enriched GLAST-1(+)/CD11b(-) cells (astrocytes) revealed RSD increased mRNA expression of IL-1β, CCL2, and CXCL2 in microglia/macrophages but not in astrocytes. Collectively, these data indicate that key mediators of leukocyte recruitment were increased in the brain vasculature following RSD in an exposure- and brain region-dependent manner.

Training status and sex influence on senescent T-lymphocyte redistribution in response to acute maximal exercise

PURPOSE

Investigate training status and sex effects on the redistribution of senescent and naïve T-lymphocytes following acute exercise.

METHODS

Sixteen (8 male, 8 female) trained (18.3±1.7yr) soccer players (Tr) and sixteen (8 male, 8 female) untrained (19.3±2.0yr) controls (UTr) performed a treadmill running test to volitional exhaustion. Blood lymphocytes were isolated before (Pre), immediately post, and 1-h post-exercise for assessment of cell surface expression of CD28 and CD57 on CD4(+) and CD8(+) T-lymphocyte subsets. Plasma was used to determine cytomegalovirus (CMV) serostatus.

RESULTS

Exercise elicited a redistribution of T-lymphocyte subsets. Senescent CD4(+) and CD8(+) T-lymphocytes increased by 42.4% and 45.9% respectively, while naïve CD4(+) and CD8(+) T-lymphocytes decreased by 8.7% and 22.5% respectively in response to exercise. A main effect (P<0.05) of training status was observed for senescent CD4(+), CD8(+) and naïve CD8(+) T-lymphocytes: UTr had a higher proportion of senescent and a lower proportion of naïve CD8(+) T-lymphocytes than Tr. A main effect (P<0.05) of sex was observed in senescent CD4(+), CD8(+) and naïve CD4(+), CD8(+) T-lymphocytes. Males had a higher proportion of senescent and lower proportion of naïve T-lymphocytes than females. A sex-by-training status interaction (P<0.05) was observed for the senescent and naïve CD4(+) T-lymphocytes (but not CD8(+)) with the highest percentage of senescent and lowest percentage of naïve T-lymphocytes observed in UTr males. CMV exerted a significant main covariate effect (P<0.05) in the senescent and naïve (P<0.05) CD8(+) T-lymphocytes but not in the senescent and naïve CD4(+) T-lymphocytes.

CONCLUSION

This study highlights important sex and training status differences in the senescent and naïve T-lymphocyte redistribution in response to exercise that warrants further investigation.

Benefit of physical fitness against inflammation in obesity: role of beta adrenergic receptors

Evidence shows that both poor physical fitness and obesity are linked to low-grade inflammation and inflammatory diseases. However, their relative roles on inflammation and underlying mechanisms remain unclear. Given the inhibitory effect of catecholamines on inflammatory cytokine production, we speculated that compromised responsiveness of immune cells' beta adrenergic receptors (β-ARs) to agonists may be associated with constitutively elevated levels of inflammatory cytokines. We examined circulating levels of inflammatory cytokines TNF, IL-1β, IL-6 and β-AR sensitivity of, 70 overweight or obese compared to 26 normal-weight, otherwise healthy individuals in order to investigate the associations among obesity, physical fitness, and low-grade inflammation and to examine the role of β-ARs in these relationships. Cardiorespiratory fitness was determined by VO2peak (ml/kg/min) via a treadmill exercise. Beta-AR sensitivity was evaluated by measuring the degree of inhibition in lipopolysaccharides-stimulated monocytic intracellular TNF production by isoproterenol. In all participants, BMI, which was initially a predictor of IL-1β and IL-6 levels independent of demographic characteristics, no longer significantly predicted them after controlling for fitness levels. Among the overweight or obese participants, greater cardiorespiratory fitness was a strong predictor of lower levels of TNF and IL-1β after controlling for the covariates. When β-AR sensitivity was controlled for, however, fitness was no longer a significant predictor of those cytokines. Monocytic β-AR sensitivity was negatively associated with inflammatory marker levels and diminished in obese individuals; however, when fitness was controlled for, the significant weight group differences in β-AR sensitivity disappeared. Our findings indicate that better cardiorespiratory fitness protects against obesity-related low-grade inflammation and β-AR desensitization. Given the significance of β-AR function in pathogenesis of various diseases, clinical implications of its role in the fitness-inflammation association among the obese are profound.

Effects of a simulated tennis match on lymphocyte subset measurements

Tennis is an activity requiring both endurance and anaerobic components, which could have immunosuppressive effects postexercise.

PURPOSE

The purpose of this investigation was to determine the effect of a simulated tennis match on apoptotic and migratory markers on lymphocyte subsets.

METHOD

Male high school (n = 5) and college (n = 3) tennis players (M(age) = 18.9 +/- 3.3 years) completed 10 sets of a tennis protocol including serves, forehand strokes, and backhand groundstrokes with 1-min rest periods between sets. Apoptosis antigen 1 receptor (CD95) and chemokine receptor fractalkine (CX3CR1) expression was analyzed on helper T lymphocytes (CD4+), cytotoxic T lymphocytes (CD8+), and B lymphocytes (CD19+) twice, at resting baseline and immediately after all 10 sets of the tennis protocol.

RESULTS

An increase was observed in each lymphocyte subtype (p < .02, effect size = .41), and comparison of absolute changes revealed increases in CD4+/CD95+, CD8+/CD95+, and CD8+/CX3CR1 lymphocytes following the tennis protocol (p < .01, effect size = .43), but not in CD19+ cells.

CONCLUSIONS

A simulated tennis match has adequate intensity to induce immune modulations in terms of increased cell death and cellular migration in T lymphocyte subsets. Lymphocytopenia following tennis play is influenced by both apoptotic and migratory mechanisms.

Differential TNF production by monocyte subsets under physical stress: blunted mobilization of proinflammatory monocytes in prehypertensive individuals

Elevated blood pressure (BP) and infiltration of the vasculature by monocytes contribute to vascular pathology; but, monocyte migratory characteristics based on differing inflammatory potential under adrenergic activation remains unclear. We compared nonclassical (CD14(+)CD16(++); HLA-DR(+)), intermediate (CD14(++)CD16(+); HLA-DR(++)), and classical (CD14(++)CD16(-); HLA-DR(+/-)) monocyte trafficking and their LPS-stimulated TNF production in response to a physical stressor (20-min treadmill exercise at 65-70% VO(2peak)) in participants with high prehypertension (PHT), mild PHT or normal BP (NBP). To determine adrenergic receptor (AR) sensitivity, pre-exercise cells were also treated with isoproterenol (Iso). When cells were stimulated with LPS, the CD16 molecules were downregulated, and monocyte subsets were differentiated based on HLA-DR expression. Monocyte subpopulations (as % of total monocytes) and intracellular TNF production were evaluated by flow cytometry. TNF production in all subsets decreased post-exercise and with ex-vivo incubation with Iso, irrespective of BP (p<0.001), with nonclassical and intermediate monocytes being a major source of TNF production. Overall, % nonclassical monocytes increased, % intermediate did not change, whereas % classical decreased post-exercise (p<0.001). However, % increase in nonclassical monocytes under exercise-induced adrenergic activation was blunted in high PHT individuals (p<0.05), but not in individuals with mild PHT and NBP. These findings extend our previous reports by showing that the mobilization of proinflammatory monocytes under physical stress is attenuated with even mild BP elevation. This may be indicative of monocytic AR desensitization and/or greater adhesion of "proinflammatory" monocytes to the vascular endothelium in hypertension with potential clinical implications of vascular pathology.

Effects of Chinese herbal recipes on immunity in immunosuppressive mice

The Chinese herbal formula consisting of Astragalus membranaceus, Epimedium brevicornum, Paeoniae Alba Radix and Radix Ophiopogonis in proper proportions were adopted in order to investigate the immunoenhancing properties of the herbal formula. Fifty ICR mice were randomly divided into 5 groups (NS- NS+Hy-L+Hy-M+Hy-H+Hy ). The mice in hydrocortisone (Hy) groups were injected with hydrocortisone i.p. to induce the immunosuppressive condition. The mice in group NS were administered with normal saline as controls. The mice in groups NS+Hy-L+Hy-M+Hy-H+Hy were administered with normal saline, low, moderate and high dose of the herbal prescription respectively by gavage for 6 days. The level of serum hemolysin, the function of antibody function cell-AFC-and CD4⁺/CD8⁺ T cell ratio were measured at the end of experiments. The results showed that the level of serum hemolysin, the function of AFC and CD4⁺/CD8⁺ T cell ratio in L+Hy-M+Hy-H+Hy groups increased significantly compared with those in NS or NS+Hy groups. These results indicate that Chinese herbal medicine prescription can enhance humoral immunity and cellular immune function of the immunosuppressive mouse.

Repeated high-intensity Wingate cycle bouts influence markers of lymphocyte migration but not apoptosis

Studies have shown significant changes in lymphocytes during continuous exercise, but little has been shown on the effect of repeated high intensity bouts. This study was designed to examine the effect of repeated intermittent bouts on lymphocyte subset cell count, apoptosis, and migration. A series of 6 Wingate anaerobic cycle tests were performed by participants (N = 8) with blood samples attained before, immediately following, and after a designated recovery period (excess postexercise oxygen consumption (EPOC)) to observe lymphocyte changes. Lymphocyte subsets (CD4+, CD4/CD45RA+, CD8+, CD8+/CD45RA+, CD19+) were assessed for apoptosis (annexin V+) and cellular migration (CX(3)CR1). Our results indicate that the CD8+ and CD8+/CD45RA+ subsets were significantly influenced by the repetitive Wingate cycling protocol such that cell counts increased with exercise, and then decreased at EPOC termination (p = 0.016). The observed postexercise decrease in CD8+ and CD8+/CD45RA+ cells was accompanied by a significant change in the CX(3)CR1 cell migration receptor (p = 0.019), but not apoptosis (p = 0.87). This indicates that with repetitive high-intensity cycling, the response in CD8+ cells following the bout is likely due to cell migration rather than cell death.

Stress, exercise, and Alzheimer's disease: a neurovascular pathway

Genetic factors are known to play a role in Alzheimer's disease (AD) vulnerability, yet less than 1% of incident AD cases are directly linked to genetic causes, suggesting that environmental variables likely play a role in the majority of cases. Several recent human and animal studies have examined the effects of behavioral factors, specifically psychological stress and exercise, on AD vulnerability. Numerous animal studies have found that, while stress exacerbates neuropathological changes associated with AD, exercise reduces these changes. Some human studies suggest that psychological stress can increase the risk of developing AD, while other studies suggest that exercise can significantly reduce AD risk. Most animal studies investigating the mechanisms responsible for the effects of these behavioral factors have focused on neuronal processes, including the effects of stress hormones and neurotrophic factors on the neuropathological hallmarks of AD, namely amyloid-beta (Aβ) deposition and tau-phosphorylation. However, cumulative evidence indicates that, in humans, AD is associated with the presence of cerebrovascular disease, and cardiovascular risk factors are associated with increased risk of developing AD. There is an extensive literature demonstrating that behavioral factors, particularly stress and exercise, can powerfully modulate the pathophysiology of vascular disease. Thus, the following model proposes that the influence of stress and exercise on AD risk may be partially due to the effects of these behavioral factors on vascular homeostasis and pathology. These effects are likely due to both indirect modification of AD risk through alterations in vascular risk factors, such as hypertension, diabetes, and aortic stiffening, as well as direct influence on the cerebrovasculature, including changes in cerebral blood flow, angiogenesis, and vascular disease. Future studies examining the effects of behavioral factors on AD risk should incorporate measures of both peripheral and cerebral vascular function to further our understanding of the mechanisms by which behavior can modify AD susceptibility. Greater knowledge of the molecular mechanisms behind these behavioral effects would further our understanding of the disease and lead to innovative treatment and preventive approaches.

Depression as a potential modulator of Beta-adrenergic-associated leukocyte mobilization in heart failure patients

OBJECTIVES

the aim of this study was to determine whether depressive symptoms are related to alterations in the sensitivity of peripheral blood mononuclear cells to β-adrenergic agonists in patients with heart failure (HF) by measuring in vitro chemotaxis (CTX) to isoproterenol at rest and after acute exercise in patients with HF and controls.

BACKGROUND

clinical outcomes are worse for patients with HF presenting with symptoms of depression. Sympathetically modulated immune dysregulation associated with depression may be one mechanism leading to worse prognosis.

METHODS

seventy-seven patients with HF and 44 controls (mean age 56.4 ± 1.3 years) completed the Beck Depression Inventory and a 15-min mild-graded exercise task on a stationary bicycle. Exercise intensity was kept relative to fitness levels for all participants by gradually increasing resistance to reach a Borg scale subjective rating of 12 to 13, "somewhat hard." Plasma norepinephrine and epinephrine levels were measured before and after exercise. Chemotaxis to isoproterenol was determined by measuring in vitro peripheral blood mononuclear cell migration through a modified Boyden chamber.

RESULTS

In patients with HF, depressive symptom severity was associated with greater CTX after exercise (p = 0.001). Higher resting norepinephrine in patients with HF was also associated with increased CTX to exercise (p = 0.03).

CONCLUSIONS

patients with HF with higher depressive symptoms and norepinephrine exhibited increased peripheral blood mononuclear cell CTX to isoproterenol to mild exercise, suggesting greater β-adrenergic sensitivity. Increased immune migration in patients with HF who have elevated depressive symptoms could be associated with cardiac remodeling and HF disease progression.

Cognitive awareness of carbohydrate intake does not alter exercise-induced lymphocyte apoptosis

OBJECTIVE

The purpose of this investigation was to determine whether cognitive awareness of carbohydrate beverage consumption affects exercise-induced lymphocyte apoptosis, independent of actual carbohydrate intake.

INTRODUCTION

Carbohydrate supplementation during aerobic exercise generally protects against the immunosuppressive effects of exercise. It is not currently known whether carbohydrate consumption or simply the knowledge of carbohydrate consumption also has that effect.

METHODS

Endurance trained male and female (N = 10) athletes were randomly assigned to one of two groups based on either a correct or incorrect cognitive awareness of carbohydrate intake. In the incorrect group, the subjects were informed that they were receiving the carbohydrate beverage but actually received the placebo beverage. Participants completed a 60-min ride on a cycle ergometer at 80% VO₂peak under carbohydrate and placebo supplemented conditions. Venous blood samples were collected at rest and immediately after exercise and were used to determine the plasma glucose concentration, lymphocyte count, and extent of lymphocyte apoptosis. Cognitive awareness, either correct or incorrect, did not have an effect on any of the measured variables.

RESULTS

Carbohydrate supplementation during exercise did not have an effect on lymphocyte count or apoptotic index. Independent of drink type, exercise resulted in significant lymphocytosis and lymphocyte apoptosis (apoptotic index at rest = 6.3 ± 3% and apoptotic index following exercise = 11.6 ± 3%, P < 0.01).

CONCLUSION

Neither carbohydrate nor placebo supplementation altered the typical lymphocyte apoptotic response following exercise. While carbohydrate supplementation generally has an immune-boosting effect during exercise, it appears that this influence does not extend to the mechanisms that govern exercise-induced lymphocyte cell death.

Latent cytomegalovirus infection amplifies CD8 T-lymphocyte mobilisation and egress in response to exercise

Exercise induces mobilisation of CD8(+) T lymphocytes (CD8TL) into the peripheral blood. This response is largely confined to effector-memory CD8TLs: antigen experienced cells which have a strong tissue-homing and effector potential. This study investigated whether effector-memory cells also account for the CD8TL egress from peripheral blood following exercise. As latent Cytomegalovirus (CMV) infection is associated with a robust expansion in the number and proportion of effector-memory CD8TLs, we also investigated if CMV serostatus was a determinant of the CD8TL responses to exercise. Fourteen males (Mean age 35, SD ± 14 yrs), half of whom were CMV seropositive (CMV(+)), ran on a treadmill for 60 min at 80% VO(2) max. Blood was collected at baseline, during the final minute of exercise, and 15 min and 60 min thereafter. CD8TL memory subsets were characterised by flow cytometry, using the cell-surface markers CD45RA, CD27, and CD28. The results confirmed that CD8TLs with an effector-memory phenotype (CD27(-)CD28(-)CD45RA(+/-)) exhibited the largest increase during exercise (+200% to +250%), and also showed the largest egress from blood 60 min post-exercise (down to 40% of baseline values). Strikingly, the mobilisation and subsequent egress of total CD8TLs was nearly twice as large in CMV(+) individuals. This effect appeared specific to CD8TLs, and was not seen for CD4(+) T lymphocytes or total lymphocytes. This effect of CMV serostatus was largely driven by the higher numbers of exercise-responsive effector-memory CD8TLs in the CMV(+) participants. This is the first study to demonstrate that infection history is a determinant of immune system responses to exercise.

Acute exercise mobilises CD8+ T lymphocytes exhibiting an effector-memory phenotype

An acute bout of exercise evokes mobilisation of lymphocytes into the bloodstream, which can be largely attributed to increases in CD8+ T lymphocytes (CD8TLs) and natural killer (NK) cells. Evidence further suggests that, even within these lymphocyte subsets, there is preferential mobilisation of cells that share certain functional and phenotypic characteristics, such as high cytotoxicity, low proliferative ability, and high tissue-migrating potential. These features are characteristic of effector-memory CD8TL subsets. The current study therefore investigated the effect of exercise on these newly-identified subsets. Thirteen healthy and physically active males (mean+/-SD: age 20.9+/-1.5 yr) attended three sessions: a control session (no exercise); cycling at 35% Watt(max) (low intensity exercise); and 85% Watt(max) (high intensity exercise). Each bout lasted 20 min. Blood samples were obtained before exercise, during the final min of exercise, and +15, and +60 min post-exercise. CD8TLs were classified into naïve, central memory (CM), effector-memory (EM), and CD45RA+ effector-memory (RAEM) using combinations of the cell surface markers CCR7, CD27, CD62L, CD57, and CD45RA. In parallel, the phenotypically distinct CD56(bright) 'regulatory' and CD56(dim) 'cytotoxic' NK subsets were quantified. The results show a strong differential mobilisation of CD8TL subsets (RAEM>EM>CM>naïve); during high intensity exercise the greatest increase was observed for RAEM CD8Tls (+450%) and the smallest for naïve cells (+84%). Similarly, CD56(dim) NK cells (+995%) were mobilised to a greater extent than CD56(bright) (+153%) NK cells. In conclusion, memory CD8TL that exhibit a high effector and tissue-migrating potential are preferentially mobilised during exercise. This finding unifies a range of independent observations regarding exercise-induced phenotypic and functional changes in circulating lymphocytes. The selective mobilisation of cytotoxic tissue-migrating subsets, both within the NK and CD8TL population, may enhance immune-surveillance during exercise.

Depressive symptoms are associated with soluble P-selectin reactivity to acute exercise in heart failure

BACKGROUND

To determine the effects of depressive symptom severity on the circulating soluble adhesion molecule response to an acute exercise challenge in patients with heart failure (HF) compared with control subjects.

METHODS

Thirty-eight male HF patients and 19 male control subjects (mean age +/- SEM: 55.5 +/- 1.9) completed the Beck Depression Inventory (BDI) before undergoing a moderate 20-minute bicycle exercise at approximately 65% to 70% VO(2peak). Plasma levels of the soluble adhesion molecules P-selectin (sP-selectin) (sCD62P) and soluble intercellular adhesion molecule-1 (sICAM-1) were determined immediately before and after and 10 minutes after exercise.

RESULTS

Higher BDI scores moderated greater increases in sP-selectin levels in response to exercise over time in HF patients as compared with control subjects [F(1.8/84.5) = 3.25, p = .05]. Post hoc testing revealed that in HF patients, but not in control subjects, higher BDI scores were significantly associated with greater increases in sP-selectin levels over time in response to exercise [BDI by exercise interaction: F(1.6/49.6) = 5.67, p = .010]. Also, in HF patients, but not in control subjects, higher BDI scores were associated with higher sP-selectin levels at pre-exercise and postexercise time points [main effect BDI: F(1/31) = 4.86, p = .035].

CONCLUSIONS

Our findings suggest that in male HF patients with increasing depressive symptom severity, levels of the adhesion molecule sP-selectin are higher before and after exercise and have greater increases in response to exercise. This could have implications for acute coronary syndromes associated with exercise and thereby may impact mortality.

A potential shift from adaptive immune activity to nonspecific inflammatory activation associated with higher depression symptoms in chronic heart failure patients

BACKGROUND

Chronic heart failure (CHF) patients with elevated depression symptoms are at greater risk of morbidity and mortality. The mechanisms linking symptoms of depression with disease progression in CHF are unclear. However, research studies have found evidence of alterations in immune activity associated with depression symptoms that may influence heart function. The present study sought to determine the relationship between depression symptoms and chemotaxis of peripheral blood mononuclear cells (PBMCs) in CHF patients, both at rest and in response to moderate exercise.

METHODS AND RESULTS

Sixty-five patients diagnosed with CHF (mean age, 59.8 +/- 14.5 years) and 45 non-CHF control subjects (mean age, 52.1 +/- 11.6) completed the Beck Depression Inventory (BDI) before undergoing a moderate 20-minute bicycle exercise task. Chemotaxis of PBMCs was examined in vitro to a bacterial peptide f-met leu phe (fMLP) and a physiologic chemokine, stromal cell derived factor-1 (SDF-1) immediately before and after exercise. CHF patients had reduced chemotaxis to SDF-1 (P = .025) compared with non-CHF subjects. Higher BDI scores were associated with reduced baseline chemotaxis to SDF-1 in both CHF and non-CHF subjects (P = .027). In contrast, higher BDI scores were associated with increased chemotaxis to fMLP (P = .049) and SDF-1 (P = .018) in response to exercise in the CHF patients.

CONCLUSION

The present study suggests a shift in immune cell mobility in CHF patients with greater depression symptom severity, with reduced chemotaxis to a physiologically specific chemokine at rest but increased chemotaxis to both nonspecific and specific chemical attractants in response to physical activity. This could have implications for cardiac repair and remodeling in CHF patients and therefore may affect disease progression.

Effects of an exercise challenge on mobilization and surface marker expression of monocyte subsets in individuals with normal vs. elevated blood pressure

High blood pressure (BP) and monocyte activation are associated with atherogenic processes. Especially, CD16 expressing monocytes are shown to be activated in many inflammatory conditions but their characteristics in hypertension is unknown. We compared CD16(++), CD16(+) and CD16(-) monocyte populations and their cellular adhesion molecule (CAM), chemokine receptor, and activation marker expression in response to a moderate 20-min treadmill exercise bout at 65-70% V O(2peak) in 44 participants with elevated (EBP) or normal BP (NBP). Blood was drawn before, immediately after, and 10min after exercise. Phenotyping of monocytes and detection of surface markers were done by flow cytometry. Monocyte subset by exercise [pre, post, 10-min post] repeated measures ANOVA and group [EBP vs. NBP] by exercise repeated measures of ANCOVA with age, BMI, and fitness as covariates were employed. Circulating numbers of all the three monocyte subsets increased after exercise (p<0.001), with the largest % increase for CD16(+)CD14(++). Percents of CD16(++)CD14(+) and CD16(+)CD14(++) increased, whereas % CD16(-)CD14(++) decreased (p<0.001). Also, pre to post exercise changes in CD62L, CD11b, CXCR2, and HLA-DR expression were different among the monocyte subsets (p's<0.001). BP status did not significantly affect monocyte subset trafficking, although post-exercise changes in CD62L and CXCR2 levels were greater in EBP individuals (p<0.05). We conclude that exercise leads to a different mobilization among monocyte subsets based on CD16 expression. Individuals with high BP showed greater responses to a physical challenge in some monocyte chemokine receptors and selectins, but its clinical implications need further examination.

The potential anti-inflammatory benefits of improving physical fitness in hypertension

Hypertension is associated with an increased risk of stroke and atherosclerosis. In addition to elevated blood pressure, hypertension is characterized by neuroendocrine and immune activation, including elevated levels of C-reactive protein, inflammatory cytokines, and soluble adhesion molecules, which are predictive of morbidity and mortality outcomes. Pharmacological treatment for hypertension reduces blood pressure, but has limited effectiveness in reducing the accompanying inflammation and its associated morbidity and mortality. Exercise and diet interventions regularly show reductions in blood pressure in hypertensive individuals. Similar interventions in other populations show reductions in many inflammatory markers, but these effects have not been routinely examined in hypertensive individuals. The mechanisms through which exercise might exert an anti-inflammatory action include the sympathetic nervous system, the hypothalamic-pituitary-adrenal axis, as well as direct effects of blood pressure. Here, exercise is promoted as a potentially effective treatment for both the elevated blood pressure and chronic inflammation found in hypertension.

Do circulating leucocytes and lymphocyte subtypes increase in response to brief exercise in children with and without asthma?

BACKGROUND

Exercise can alter health in children in both beneficial (eg reduced long-term risk of atherosclerosis) and adverse (eg exercise-induced asthma) ways. The mechanisms linking exercise and health are not known, but may rest, partly, on the ability of exercise to increase circulating immune cells. Little is known about the effect of brief exercise, more reflective of naturally occurring patterns of physical activity in children, on immune cell responses.

OBJECTIVES

To determine whether (1) a 6-min bout of exercise can increase circulating inflammatory cells in healthy children and (2) the effect of brief exercise is greater in children with a history of asthma.

METHODS

Children with mild-moderate persistent asthma and age-matched controls (n = 14 in each group, mean age 13.6 years) performed a 6-min bout of cycle-ergometer exercise. Spirometry was performed at baseline and after exercise. Blood was drawn before and after exercise, leucocytes were quantified and key lymphocyte cell surface markers were assessed by flow cytometry.

RESULTS

Exercise decreased spirometry only in children with asthma, but increased (p<0.001) most types of leucocytes (eg lymphocytes (controls, mean (SD) 1210 (208) cells/microl; children with asthma, 1119 (147) cells/microl) and eosinophils (controls, 104 (22) cells/microl; children with asthma, 88 (20) cells/microl)) to the same degree in both groups. Similarly, exercise increased T helper cells (controls, 248 (60) cells/microl; children with asthma, 232 (53) cells/microl) and most other lymphocyte subtypes tested. By contrast, although basophils (16 (5) cells/microl) and CD4+ CD45RO+ RA+ lymphocytes (19 (4) cells/microl) increased in controls, no increase in these cell types was found in children with asthma.

CONCLUSIONS

Exercise increased many circulating inflammatory cells in both children with asthma and controls. Circulating inflammatory cells did increase in children with asthma, but not to a greater degree than in controls. In fact, basophils and T helper lymphocyte memory transition cells did not increase in children with asthma, whereas they did increase in controls. Even brief exercise in children and adolescents robustly mobilizes circulating immune cells.

Physical fitness attenuates leukocyte-endothelial adhesion in response to acute exercise

Studies suggest that physical fitness promotes cardiovascular health, including improved endothelial function and possibly reduced inflammatory responses to stressors. This study examined the effects of fitness on leukocyte-endothelial adhesion in response to an acute exercise challenge. Peripheral blood mononuclear cell (PBMC) adhesion to human umbilical venous endothelial cells (HUVEC) was examined in 18 more-fit and 19 less-fit individuals [mean age 39 yr (SD 11)] before and after a 20-min treadmill exercise at 65-70% peak oxygen consumption. PBMC were isolated from whole blood (Ficoll-Paque) at rest and immediately after exercise. HUVEC were incubated for 4 h in the presence of cytokines IL-1 and IL-8 to activate endothelial adhesion molecule expression. Fit subjects showed a significant reduction in PBMC-HUVEC adhesion after exercise (P < 0.01) compared with less-fit subjects, who showed no significant change. Regardless of fitness levels, both at rest and in response to exercise, soluble ICAM-1 in the incubation media attenuated PBMC-HUVEC adhesion by approximately 81% (P < 0.001). The findings indicate that immune cells that demarginate in response to exercise have reduced ability to adhere in individuals who are physically fit, an effect apparently independent of ICAM-1 binding. The findings provide evidence of how physical fitness might protect individuals from inflammatory responses to exercise.

The effects of intensive, moderate and downhill treadmill running on human blood lymphocytes expressing the adhesion/activation molecules CD54 (ICAM-1), CD18 (β2 integrin) and CD53

This study examined the effects of intensive, moderate and downhill treadmill running on blood lymphocyte expression of adhesion/activation (AA) molecules. Trained subjects completed three treadmill-running protocols of identical duration: (1) an intensive protocol at 80% VO2max to volitional exhaustion, (2) a moderate protocol at 60% VO2max and (3) a -10% downhill (eccentric) protocol at 80% VO2max. Blood samples were taken before, immediately after, 1 and 24 h after exercise. Isolated lymphocytes were assessed for expression of the AA molecules CD54, CD18 and CD53 by flow cytometry. Lymphocyte counts increased immediately after all running protocols. Lymphocytopenia was observed 1 h after the intensive and eccentric protocols only. Plasma creatine kinase increased 24 h after the downhill protocol only. Increases in the number and percentage of CD54+, CD18bright and CD53bright lymphocytes were observed immediately after the intensive and eccentric protocols, with the numbers falling below pre-exercise values at 1 h post-exercise for all protocols. No differences were found between the intensive protocol and the eccentric protocol at the same relative intensity. Analysis of lymphocyte subsets showed that the total number of CD3+, CD4+, CD8+ and CD56+ lymphocytes increased after the intensive protocol before falling below pre-exercise values at 1 h post-exercise. A relatively greater mobilisation of CD56+ and CD8+ cells accounts for the changes in CD54+, CD18bright and CD53bright cell populations. Lymphocytes that enter and exit the circulation following exercise express high levels of AA molecules, which may mediate extravasation and post-exercise lymphocytopenia. This effect appears to be influenced by exercise intensity and not muscle damage.