Effect of six months' exercise training on C-reactive protein levels in healthy elderly subjects

Effects of different exercise modalities on inflammatory markers in the obese and overweight populations: unraveling the mystery of exercise and inflammation

In the realm of obesity and overweight, the risk of chronic diseases significantly escalates, closely intertwined with inflammatory factors. Research suggests that specific exercise interventions, particularly aerobic exercise and resistance exercise, can have beneficial effects on inflammation levels. However, debates persist regarding the actual impact of exercise in the obese and overweight population. We employed meta-analysis research methods and searched the China National Knowledge Infrastructure Wanfang Data, PubMed, and Web of Science databases to gather controlled experiments on the effects of resistance exercise or aerobic exercise on C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). Two researchers independently conducted literature screening and data extraction. The quality of the literature was assessed according to the Cochrane Handbook standards, and subgroup analyses of CRP, IL-6, and TNF-α were performed using RevMan 5.4 software. Through quantitative synthesis of results from 22 selected studies encompassing a total of 1,135 research subjects, this study systematically explored the specific regulatory effects of different exercise modalities on inflammatory markers in the obese and overweight population. The findings indicate that both aerobic exercise and resistance exercise effectively reduce CRP levels in obese individuals, with aerobic exercise demonstrating a more pronounced effect. Aerobic exercise also significantly lowers IL-6 levels, while the impact of resistance exercise on IL-6 is relatively minor. However, in terms of reducing TNF-α levels, neither modality appears to exert a significant effect. Overall, exercise, especially aerobic exercise, emerges as a positive regulator of inflammatory markers in the context of obesity and overweight.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Exercise to spot the differences: a framework for the effect of exercise on hippocampal pattern separation in humans

Exercise has a beneficial effect on mental health and cognitive functioning, but the exact underlying mechanisms remain largely unknown. In this review, we focus on the effect of exercise on hippocampal pattern separation, which is a key component of episodic memory. Research has associated exercise with improvements in pattern separation. We propose an integrated framework mechanistically explaining this relationship. The framework is divided into three pathways, describing the pro-neuroplastic, anti-inflammatory and hormonal effects of exercise. The pathways are heavily intertwined and may result in functional and structural changes in the hippocampus. These changes can ultimately affect pattern separation through direct and indirect connections. The proposed framework might guide future research on the effect of exercise on pattern separation in the hippocampus.

The Effects of Exercise on Aging-Induced Exaggerated Cytokine Responses: An Interdisciplinary Discussion

Aging is generally known to be associated with dynamic biological changes, physiological dysfunction, and environmental and psychological decline. Several studies have suggested that aging is associated with increased inflammatory cytokines, causing several diseases. However, the effect of exercise on aging has been less delineated, and the relationships between cytokine activation, aging, and exercise also need further study. Here, we discuss some ideas about the effect of exercise on aging-induced exaggerated cytokine responses and discuss the possible roles of the aging-induced exaggerated cytokine response following exercise. Evidence from these findings suggests that exercise is a beneficially applicable model to use in studies on the mechanisms underlying the age-associated gradated cytokine response, and these results may provide guidelines for health professionals with diverse backgrounds.

Dietary Weight Loss, Exercise, and Inflammation in Older Adults with Overweight or Obesity and Cardiometabolic Disease

OBJECTIVE

This study aimed to examine exercise modality during weight loss on change in inflammation among older adults with overweight or obesity and cardiometabolic disease.

METHODS

A total of 222 older adults with a mean (SD) age of 66.9 (4.7) years and a mean (SD) BMI of 33.5 (3.5) kg/m2 were randomized to weight loss (WL; n = 68), WL plus aerobic training (WL + AT; n = 79), or WL plus resistance training (WL + RT; n = 75) for 18 months. C-reactive protein (CRP) and interleukin-6 were measured at baseline, 6 months, and 18 months.

RESULTS

All groups lost significant weight from baseline to 18 months, with average adjusted changes of -5.5% for WL, -9.0% for WL + AT, and -10.1% for WL + RT. WL + RT and WL + AT lost significantly more weight than WL (P < 0.05). At 18 months, CRP values in WL + RT were significantly lower than WL (2.25 pg/mL vs. 3.38 pg/mL; P = 0.004). The only difference in interleukin-6 was that at 18 months, WL + RT was lower than WL + AT (2.32 pg/mL vs. 2.75 pg/mL; P = 0.03).

CONCLUSIONS

The addition of RT during WL was more effective at reducing levels of CRP than WL. Although results were in the expected direction, there was no difference in CRP between WL and WL + AT.

Abdominal Fat Is Directly Associated With Inflammation In Persons With Type-2 Diabetes Regardless Of Glycemic Control - A Jordanian Study

BACKGROUND AND AIM

Systemic inflammation is related to the progression of complications associated with diabetes. This study aimed to investigate the association between general and abdominal obesity and inflammation in patients with type-2 diabetes with or without glycemic control.

METHODS

A total of 198 men (n=73) and women (n=125) diagnosed with type 2 diabetes participated in this study. General obesity markers, body mass index (BMI), and abdominal fat were assessed. Circulating concentrations of glycated hemoglobin (HbA1C), C-reactive protein (CRP), and serum interleukin-6 (IL-6) were determined. Poor glycemic control and good glycemic control were defined as having fasting HbA1C concentrations ≥7% and <7%, respectively. Multivariate adjusted analysis of covariance was used to determine the relation between BMI and abdominal fat and markers of inflammation in patients with good and poor glycemic control.

RESULTS

Patients in <7% HbA1C category, those with high abdominal fat had ≈262% higher CRP and ≈30.6% higher IL-6 compared to those with low abdominal fat (p˂0.05). Patients in ≥7% HbA1C category, those with high abdominal fat had ≈41.4% higher CRP and ≈33.9% higher IL-6 compared to those with low abdominal fat (p˂0.05). Abdominal fat was directly related to CRP (p˂0.023) and IL-6 (p˂0.002) concentrations in both groups of type-2 diabetic patients with <7% and ≥7% HbA1C. In patients with ≥7% HbA1C, BMI was directly related to CRP (p˂0.02) and IL-6 (p˂0.047). Whereas in patients with <7% HbA1C, BMI was not associated with CRP or IL-6 concentrations.

CONCLUSION

High level of abdominal fat is associated with systemic inflammation in type-2 diabetes regardless of glycemic control. Abdominal fat is a better predictor (determinant) of inflammation than BMI in patients with type-2 diabetes with or without glycemic control.

Effect of lifestyle improvement program on the biomarkers of adiposity, inflammation and gut hormones in overweight/obese Asian Indians with prediabetes

AIMS

While lifestyle modification is known to offer several metabolic benefits, there is paucity of comprehensive data on changes in biomarkers of adiposity, inflammation as well as gut hormones. We investigated these biomarkers in overweight/obese individuals with prediabetes randomized to either 4 months of a lifestyle improvement program or standard care and followed them up for a year.

METHODS

Participants [standard care and intervention arm (n = 75 each)] were randomly selected from the Diabetes Community Lifestyle Improvement Program trial. Glycemic and lipid control and anthropometric measurements were assessed by standard protocols. Adipokines, inflammatory markers and gut hormones were measured using multiplex and standard ELISA kits.

RESULTS

Along with modest benefits in primary outcomes (glycemic and lipid control and weight reduction), participants in the intervention group showed significant reductions (p < 0.001) in plasma levels of leptin (17.6%), TNF-α (35%), IL-6 (33.3%), MCP-1 (22.3%) and PYY (28.3%) and increased levels of adiponectin (33.1%) and ghrelin (23.6%) at the end of 4 months of lifestyle intervention. The changes were independent of weight and persisted even at 1 year of follow-up. In contrast, participants from the standard care arm did not show any statistically significant improvements on the above parameters.

CONCLUSIONS

Participants who underwent an intensive lifestyle improvement program showed metabolic benefits as well as favorable beneficial changes in systemic levels of adipokines, cytokines and gut hormones, not only during the intervention period, but also during 12-month follow-up period.

Sexual dimorphisms of mRNA and miRNA in human/murine heart disease

BACKGROUND

Sexual dimorphisms are well recognized in various cardiac diseases such as ischemic cardiomyopathy (ICM), hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Thorough understanding of the underlying genetic programs is crucial to optimize treatment strategies specified for each gender. By performing meta-analysis and microarray analysis, we sought to comprehensively characterize the sexual dimorphisms in the healthy and diseased heart at the level of both mRNA and miRNA transcriptome.

RESULTS

Existing mRNA microarray data of both mouse and human heart were integrated, identifying dozens/ hundreds of sexually dimorphic genes in healthy heart, ICM, HCM, and DCM. These sexually dimorphic genes overrepresented gene ontologies (GOs) important for cardiac homeostasis. Further, microarray of miRNA, isolated from mouse sham left ventricle (LV) (n = 6 & n = 5 for male & female) and chronic MI LV (n = 19 & n = 19) and from human normal LV (n = 6 & n = 6) and ICM LV (n = 4 & n = 5), was conducted. This revealed that 13 mouse miRNAs are sexually dimorphic in MI and 6 in normal heart. In human, 3 miRNAs were sexually dimorphic in ICM and 15 in normal heart. These data revealed miRNA-mRNA networks that operate in a sexually-biased fashion.

CONCLUSIONS

mRNA and miRNA transcriptome of normal and disease heart show significant sex differences, which might impact the cardiac homeostasis. Together this study provides the first comprehensive picture of the genome-wide program underlying the heart sexual dimorphisms, laying the foundation for gender specific treatment strategies.

Repeated Excessive Exercise Attenuates the Anti-Inflammatory Effects of Exercise in Older Men

Introduction/Purpose: A number of studies have investigated the effect of training with a moderate exercise dose (3-6 h/weekly) on the inflammatory profile in blood, and the data are inconsistent. Cross-sectional studies indicate a positive effect of physical activity level on inflammation levels and risk of metabolic disease. However, it is not clear whether this may be dose dependent and if very prolonged repeated exercise therefore may be beneficial for low-grade inflammation. Based on this we studied how excessive repeated prolonged exercise influenced low-grade inflammation and adipose tissue anti-inflammatory macrophage content in six older male recreationally trained cyclists. Low-grade inflammation and adipose tissue macrophage content were investigated in six older trained men (age: 61 ± 4 years; VO_2peak: 48 ± 2 mL kg^-1 min^-1) following repeated prolonged exercise. Methods: Cycling was performed daily for 14 days covering in total 2,706 km (1,681 miles). Maximal oxygen uptake (VO_2peak) was measured before and after the cycling. Duration and intensity of the exercise were determined from heart rates sampled during cycling. An adipose tissue biopsy from subcutaneous abdominal fat and a blood sample were obtained at rest in the overnight fasted state before and after the cycling. Anti-inflammatory adipose tissue macrophages (ATM) were immunohistochemically stained in cross sectional sections using a CD163 binding antibody. The ATM and adipocyte sizes were analyzed blindly. Results: The cyclists exercised daily for 10 h and 31 ± 37 min and average intensity was 53 ± 1% of VO_2peak. Body weight remained unchanged and VO_2peak decreased by 6 ± 2% (P = 0.04). Plasma inflammatory cytokines, TNFα and IL-18 remained unchanged, as did hsCRP, but plasma IL-6 increased significantly. CD163 macrophage content remained unchanged, as did adipocyte cell size. The HbA1c was not significantly decreased, but there was a trend (P < 0.07) toward an increased insulin resistance as estimated by the Quicki Index. Conclusion: The regular prolonged exercise did not influence abdominal adipose tissue inflammation, but the higher plasma IL-6 concentration concurrent with a trend toward higher insulin resistance and decreased VO_2peak implies that the excessive amount of exercise probably attenuated the possible potential anti-inflammatory effects of exercise.

Association of the Composite Inflammatory Biomarker GlycA, with Exercise-Induced Changes in Body Habitus in Men and Women with Prediabetes

GlycA is a new composite measure of systemic inflammation and a predictor of many inflammatory diseases. GlycA is the nuclear magnetic resonance spectroscopy-derived signal arising from glucosamine residues on acute-phase proteins. This study aimed to evaluate how exercise-based lifestyle interventions modulate GlycA in persons at risk for type 2 diabetes. GlycA, fitness, and body habitus were measured in 169 sedentary adults (45–75 years) with prediabetes randomly assigned to one of four six-month exercise-based lifestyle interventions. Interventions included exercise prescription based on the amount (energy expenditure (kcal/kg weight/week (KKW)) and intensity (%VO_2peak). The groups were (1) low-amount/moderate-intensity (10KKW/50%) exercise; (2) high-amount/moderate-intensity (16KKW/50%) exercise; (3) high-amount/vigorous-intensity (16KKW/75%) exercise; and (4) a Clinical Lifestyle (combined diet plus low-amount/moderate-intensity exercise) intervention. Six months of exercise training and/or diet-reduced GlycA (mean Δ: −6.8 ± 29.2 μmol/L; p = 0.006) and increased VO_2peak (mean Δ: 1.98 ± 2.6 mL/kg/min; p < 0.001). Further, visceral (mean Δ: −21.1 ± 36.6 cm²) and subcutaneous fat (mean Δ: −24.3 ± 41.0 cm²) were reduced, while liver density (mean Δ: +2.3 ± 6.5HU) increased, all p < 0.001. When including individuals in all four interventions, GlycA reductions were associated with reductions in visceral adiposity (p < 0.03). Exercise-based lifestyle interventions reduced GlycA concentrations through mechanisms related to exercise-induced modulations of visceral adiposity. This trial is registered with Clinical Trial Registration Number NCT00962962.

The Anti-Inflammatory Actions of Exercise Training

The list of diseases with a known inflammatory etiology is growing. Cardiovascular disease, osteoporosis, diabetes, geriatric cachexia, and Alzheimer's disease have all been shown to be linked to or exacerbated by aberrantly regulated inflammatory processes. Nevertheless, there is mounting evidence that those who are physically active, or who become physically active, have a reduction in biomarkers associated with chronic inflammation. There was strong early consensus that exercise-induced reductions in inflammation were explained by body mass index or body fatness, but recent studies provide support for the contention that exercise has body fat-independent anti-inflammatory effects. With few exceptions, the anti-inflammatory effects of exercise appear to occur regardless of age or the presence of chronic diseases. What remains unclear are the mechanisms by which exercise training induces these anti-inflammatory effects, but there are several intriguing possibilities, including release of endogenous products, such as heat shock proteins; selective reduction of visceral adipose tissue mass or reducing infiltration of adipocytes by macrophages; shift in immune cell phenotype; cross-tolerizing effects; or exercise-induced shifts in accessory proteins of toll-like receptor signaling. However, future research endeavors are likely to uncover additional potential mechanisms, and it could be some time before functional mechanisms are made clear. In summary, the potential anti-inflammatory influences of exercise training may provide a low-cost, readily available, and effective treatment for low-grade systemic inflammation and could contribute significantly to the positive effects of exercise training on chronic disease.

Effects of exercise on c-reactive protein in healthy patients and in patients with heart disease: A meta-analysis

Decreases in circulating hsCRP have been associated with increased physical activity and exercise training, although the ability of exercise interventions to reduce hsCRP and which individuals benefit the most remains unclear. This meta-analysis evaluates the ability of exercise to reduce hsCRP levels in healthy individuals and in individuals with heart disease. A systematic review and meta-analysis was conducted that included exercise interventions trials from 1995 to 2012. Forty-three studies were included in the final analysis for a total of 3575 participants. Exercise interventions significantly reduced hsCRP (standardized mean difference -0.53 mg/L; 95% CI, -0.74 to -0.33). Results of sub-analysis revealed no significant difference in reductions in hsCRP between healthy adults and those with heart disease (p = .20). Heterogeneity between studies could not be attributed to age, gender, intervention length, intervention type, or inclusion of diet modification. Exercise interventions reduced hsCRP levels in adults irrespective of the presence of heart disease.​.

Exercise Modulates Oxidative Stress and Inflammation in Aging and Cardiovascular Diseases

Despite the wealth of epidemiological and experimental studies indicating the protective role of regular physical activity/exercise training against the sequels of aging and cardiovascular diseases, the molecular transducers of exercise/physical activity benefits are not fully identified but should be further investigated in more integrative and innovative approaches, as they bear the potential for transformative discoveries of novel therapeutic targets. As aging and cardiovascular diseases are associated with a chronic state of oxidative stress and inflammation mediated via complex and interconnected pathways, we will focus in this review on the antioxidant and anti-inflammatory actions of exercise, mainly exerted on adipose tissue, skeletal muscles, immune system, and cardiovascular system by modulating anti-inflammatory/proinflammatory cytokines profile, redox-sensitive transcription factors such as nuclear factor kappa B, activator protein-1, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha, antioxidant and prooxidant enzymes, and repair proteins such as heat shock proteins, proteasome complex, oxoguanine DNA glycosylase, uracil DNA glycosylase, and telomerase. It is important to note that the effects of exercise vary depending on the type, intensity, frequency, and duration of exercise as well as on the individual's characteristics; therefore, the development of personalized exercise programs is essential.

The effect of exercise on lipid profiles and inflammatory markers in lean male adolescents: a prospective interventional study

BACKGROUND

Physical activity improves body composition and inflammatory markers in obese individuals, but little is known about the nonobese population.

OBJECTIVE

The aim of this study was to investigate associations between exercise and inflammatory cytokines in lean male adolescents in Taiwan.

METHODS

This interventional study enrolled a total of 79 normal body weight male adolescents [mean age, 16.8 (1.0) years] from the Army Academy of Taiwan. Body composition and inflammatory markers were measured at baseline and upon completion of a 12-week exercise intervention program.

RESULTS

Subjects' postintervention anthropometric measures, including waist circumference [74.6 (5.2)→72.6 (5.2) cm], hip circumference [92.3 (4.1)→89.9 (5.0) cm], body fat mass [10.2 (3.2)→8.2 (3.2) kg], and body fat percentage [15.8% (4.2)→12.6 (4.5)%] declined significantly compared to preintervention (all P<0.001), as did systolic blood pressure (P=0.002) and mean blood pressure (P = 0.020). Postintervention body height and free fat mass increased significantly (both P<0.001). Subjects' postintervention lipids including total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglycerides increased significantly (all P<0.001). Inflammatory markers including adiponectin [14.32 (6.68)→31.31 (30.53) μg/mL, P<0.001], interleukin 6 [2.15 (4.81)→2.86 (6.37) pg/mL, P=0.005], and C-reactive protein [1.00 (2.57)→2.30 (4.17) μg/mL, P<0.001] increased significantly postintervention, but not leptin.

CONCLUSIONS

Exercise training significantly improves body composition and anti-inflammatory adiponectin levels in lean male adolescents.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.

Diet and diet combined with chronic aerobic exercise decreases body fat mass and alters plasma and adipose tissue inflammatory markers in obese women

The purpose of this study was to investigate the effect of 6 months aerobic exercise and diet alone or in combination on markers of inflammation (MOI) in circulation and in adipose abdominal tissue (AT) in obese women. Thirty obese subjects were randomized into a 24-week intervention: (1) exercise (EX), (2) diet (DI), and (3) exercise and diet (EXD). Blood samples were collected at baseline, after 12 and 24 weeks. AT biopsies were obtained only at baseline and after 24 weeks. In the EXD and DI groups, the fat loss was after 12 weeks was -13.74 and -7.8 % (P < 0.01) and after 24 weeks was -21.82 and -17 % (P < 0.01) with no changes in the EX group. After 12 and 24 weeks, maximal oxygen consumption (VO2max) was increased by 21.81-39.54 % (P < 0.05) in the EXD group and 18.09-40.95 % in the EX group with no changes in the DI group. In the EXD and DI groups, circulating levels of tumor necrosis factor α and interleukin 6 were decreased after 24 weeks for both groups (P < 0.01). No changes in the EX group. Homeostatic model assessment for insulin resistance decreased (P < 0.05) only after 24 weeks in the EXD group. In AT biopsies, subjects in the EXD and DI groups exhibited a significant decrease in MO (P < 0.01 for all). No changes in AT biopsies were found in the EX group. In conclusion, chronic aerobic exercise was found to have no effects on circulating and AT MOI despite an increased VO2max. Rather important body composition modifications were found to have beneficial effects on circulating and AT MOI in these obese women.

Effect of hypoxic training on inflammatory and metabolic risk factors: a crossover study in healthy subjects

The purpose of this study was to investigate the influence of hypoxic physical exercise on metabolic syndrome (MS) risk markers and high-sensitivity C-reactive protein (CRP) and to compare its effects on preperitoneal fat, arterial stiffness, and several blood parameters related to MS to those of a control group who trained under normoxic conditions. Fourteen healthy men were examined. Participants performed treadmill exercise 3 days per week for 4 weeks, under either normobaric hypoxic or normobaric normoxic conditions, for 50 min (including a 5-min warm-up and 5-min cool down) after a 30-min rest period. Exercise was performed at a heart rate (HR) corresponding to 60% of the HR at each individual's maximum oxygen uptake. Training under the different environmental conditions was performed 4 months apart to ensure a sufficient washout period. Waist circumference, preperitoneal fat thickness, brachial-ankle pulse wave velocity, and high-sensitivity CRP after training were significantly lower in the hypoxic group than in the normoxic group. Our results suggest that regular short-term hypoxic training may more effectively reduce arterial stiffness, and thus prevent arteriosclerosis, compared to training performed at a similar exercise intensity under normoxic conditions.

Life-long endurance exercise in humans: circulating levels of inflammatory markers and leg muscle size

Human aging is associated with a loss of skeletal muscle and an increase in circulating inflammatory markers. It is unknown whether endurance training (Tr) can prevent these changes. Therefore we studied 15 old trained (O-Tr) healthy males and, for comparison, 12 old untrained (O-Un), 10 Young-Tr (Y-Tr) and 12 Young-Un (Y-Un). Quadriceps size, VO2 peak, CRP, IL-6, TNF-α and its receptors, suPAR, lipid profile, leucocytes and glucose homeostasis were measured. Tr was associated with an improved insulin profile (p<0.05), and lower leucocyte (p<0.05) and triglyceride levels (p<0.05), independent of age. Aging was associated with poorer glucose control (p<0.05), independent of training. The age-related changes in waist circumference, VO2 peak, cholesterol, LDL, leg muscle size, CRP and IL-6 were counteracted by physical activity (p<0.05). A significant increase in suPAR with age was observed (p<0.05). Most importantly, life-long endurance exercise was associated with a lower level of the inflammatory markers CRP and IL-6 (p<0.05), and with a greater thigh muscle area (p<0.05), compared to age-matched untrained counterparts. These findings in a limited group of individuals suggest that regular physical endurance activity may play a role in reducing some markers of systemic inflammation, even within the normal range, and in maintaining muscle mass with aging.

Independent and combined effects of physical activity and weight loss on inflammatory biomarkers in overweight and obese older adults

OBJECTIVES

To determine the independent effect of long-term physical activity (PA) and the combined effects of long-term PA and weight loss (WL) on inflammation in overweight and obese older adults.

DESIGN

Eighteen-month randomized, controlled trial.

SETTING

The community infrastructure of cooperative extension centers.

PARTICIPANTS

Overweight and obese (body mass index >28.0 kg/m(2) ) community-dwelling men and women aged 60 to 79 at risk for cardiovascular disease (CVD).

INTERVENTION

Physical activity + weight loss (PA + WL) (n = 98), PA only (n = 97), or successful aging (SA) health education (n = 93) intervention.

MEASUREMENTS

Biomarkers of inflammation (adiponectin, leptin, high-sensitivity interleukin (hsIL)-6, IL-6sR, IL-8, and soluble tumor necrosis factor receptor 1) were measured at baseline and 6 and 18 months.

RESULTS

After adjustment for baseline biomarker, wave, sex, and visit, leptin and hsIL-6 showed a significant intervention effect. Specifically, leptin was significantly lower in the PA + WL group (21.3 ng/mL, 95% confidence interval (CI) = 19.7-22.9 ng/mL) than in the PA (29.3 ng/mL, 95% CI = 26.9-31.8 ng/mL) or SA (30.3 ng/mL, 95% CI = 27.9-32.8 ng/mL) group (both P < .001), and hsIL-6 was significantly lower in the PA + WL group (2.1 pg/mL, 95% CI = 1.9-2.3 pg/mL) than in the PA (2.5 pg/mL, 95% CI = 2.3-2.7 pg/mL) or SA (2.4 pg/mL, 95% CI = 2.2-2.6 pg/mL) group (P = .02).

CONCLUSION

Addition of dietary-induced WL to PA reduced leptin and hsIL-6 more than PA alone and more than a SA intervention in older adults at risk for CVD. Results suggest that WL, rather than increased PA, is the lifestyle factor primarily responsible for improvement in the inflammatory profile.

A consideration of biomarkers to be used for evaluation of inflammation in human nutritional studies

To monitor inflammation in a meaningful way, the markers used must be valid: they must reflect the inflammatory process under study and they must be predictive of future health status. In 2009, the Nutrition and Immunity Task Force of the International Life Sciences Institute, European Branch, organized an expert group to attempt to identify robust and predictive markers, or patterns or clusters of markers, which can be used to assess inflammation in human nutrition studies in the general population. Inflammation is a normal process and there are a number of cells and mediators involved. These markers are involved in, or are produced as a result of, the inflammatory process irrespective of its trigger and its location and are common to all inflammatory situations. Currently, there is no consensus as to which markers of inflammation best represent low-grade inflammation or differentiate between acute and chronic inflammation or between the various phases of inflammatory responses. There are a number of modifying factors that affect the concentration of an inflammatory marker at a given time, including age, diet and body fatness, among others. Measuring the concentration of inflammatory markers in the bloodstream under basal conditions is probably less informative compared with data related to the concentration change in response to a challenge. A number of inflammatory challenges have been described. However, many of these challenges are poorly standardised. Patterns and clusters may be important as robust biomarkers of inflammation. Therefore, it is likely that a combination of multiple inflammatory markers and integrated readouts based upon kinetic analysis following defined challenges will be the most informative biomarker of inflammation.

Effect of exercise on markers of inflammation in breast cancer survivors: the Yale exercise and survivorship study

Physical activity is associated with improved breast cancer survival, but the underlying mechanisms, possibly including modification of the inflammatory state, are not well understood. We analyzed changes in interleukin (IL)-6, C-reactive protein (CRP), and TNF-α in a randomized controlled trial of exercise in postmenopausal breast cancer survivors. Seventy-five women, recruited through the Yale-New Haven Hospital Tumor Registry, were randomized to either a six-month aerobic exercise intervention or usual care. Correlations were calculated between baseline cytokines, adiposity, and physical activity measures. Generalized linear models were used to assess the effect of exercise on IL-6, CRP, and TNF-α. At baseline, IL-6 and CRP were positively correlated with body fat and body mass index (BMI) and were inversely correlated with daily pedometer steps (P < 0.001). We found no significant effect of exercise on changes in inflammatory marker concentrations between women randomized to exercise versus usual care, though secondary analyses revealed a significant reduction in IL-6 among exercisers who reached 80% of the intervention goal compared with those who did not. Future studies should examine the effect of different types and doses of exercise and weight loss on inflammatory markers in large-scale trials of women diagnosed with breast cancer.

Biologic and epigenetic impact of commuting to work by car or using public transportation: a case-control study

BACKGROUND AND AIMS

Commuting by public transportation (PT) entails more physical activity and energy expenditure than by cars, but its biologic consequences are unknown.

METHODS

In 2009-2010, we randomly sampled New York adults, usually commuting either by car (n=79) or PT (n=101). Measures comprised diet and physical activity questionnaires, weight and height, white blood cell (WBC) count, C reactive protein, (CRP) gene-specific methylation (IL-6), and global genomic DNA methylation (LINE-1 methylation).

RESULTS

Compared to the 101 PT commuters, the 79 car drivers were about 9 years older, 2 kg/m(2) heavier, more often non-Hispanic whites, and ate more fruits and more meats. The 2005 guidelines for physical activity were met by more car drivers than PT users (78.5% vs. 65.0%). There were no differences in median levels of CRP (car vs. PT: 0.6 vs. 0.5mg/dl), mean levels of WBC (car vs. PT: 6.7 vs. 6.5 cells/mm(3)), LINE-1 methylation (car vs. PT: 78.0% vs. 78.3%), and promoter methylation of IL-6 (car vs. PT: 56.1% vs. 58.0%).

CONCLUSIONS

PT users were younger and lighter than car drivers, but their commute mode did not translate into a lower inflammatory response or a higher DNA methylation, maybe because, overall, car drivers were more physically active.

Neuroimmunological effects of physical exercise in depression

The search for an extended understanding of the causes of depression, and for the development of additional effective treatments is highly significant. Clinical and pre-clinical studies suggest stress is a key mediator in the pathophysiology of depression. Exercise is a readily available therapeutic option, effective as a first-line treatment in mild to moderate depression. In pre-clinical models exercise attenuates stress-related depression-like behaviours. Cellular and humoral neuroimmune mechanisms beyond inflammation and oxidative stress are highly significant in understanding depression pathogenesis. The effects of exercise on such mechanisms are unclear. When clinical and pre-clinical data is taken together, exercise may reduce inflammation and oxidation stress via a multitude of cellular and humoral neuroimmune changes. Astrocytes, microglia and T cells have an antiinflammatory and neuroprotective functions via a variety of mechanisms. It is unknown whether exercise has effects on specific neuroimmune markers implicated in the pathogenesis of depression such as markers of immunosenescence, B or T cell reactivity, astrocyte populations, self-specific CD4+ T cells, T helper 17 cells or T regulatory cells.

Effects of physical activity on cardiovascular disease

Much attention has been directed toward lifestyle modifications as effective means of reducing cardiovascular disease risk. In particular, physical activity has been heavily studied because of its well-known effects on metabolic syndrome, insulin sensitivity, cardiovascular disease risk, and all-cause mortality. However, data regarding the effects of exercise on various stages of the atherosclerosis pathway remain conflicting. The investigators review previously published reports for recent observational and interventional trials investigating the effects of physical activity on markers of (or causal factors for) atherosclerotic burden and vascular disease, including serum lipoproteins, systemic inflammation, thrombosis, coronary artery calcium, and carotid intima-media thickness. In conclusion, the data show a correlation between physical activity and triglyceride reduction, apolipoprotein B reduction, high-density lipoprotein increase, change in low-density lipoprotein particle size, increase in tissue plasminogen activator activity, and decrease in coronary artery calcium. Further research is needed to elucidate the effect of physical activity on inflammatory markers and intima-media thickness.

Sixteen weeks of exercise reduces C-reactive protein levels in young women

PURPOSE

Regular exercise has been shown to protect against breast cancer risk, and one possible mechanism is through a reduction in inflammation. The purpose of this study was to examine the effects of 16 wk of aerobic exercise training on adipokines and inflammatory markers in healthy young women.

METHODS

Participants were 319 sedentary women aged 18-30 yr, with body mass index of 18-40 kg · m, randomized to an exercise intervention or no exercise for approximately 16 wk. Adiponectin, leptin, C-reactive protein (CRP), and amyloid A (AA) were measured at baseline and after 16 wk. Adiponectin was measured by enzyme-linked immunosorbent assay, and AA, CRP, and leptin were measured by multiplex bead array assays.

RESULTS

Exercise significantly decreased CRP levels in the exercise group compared with the control group (-1.41 mg · L in exercisers vs -0.005 mg · L in controls, P = 0.040), and this effect was largely driven by changes in CRP that occurred in the obese exercisers. There was no effect of exercise on levels of SAA, adiponectin, or leptin. There was also no effect of exercise on stress and depression scores. Neither change in percent body fat nor change in fitness influenced the effects of exercise on these inflammatory markers.

CONCLUSIONS

This study demonstrated that a 16-wk aerobic exercise program significantly decreased levels of CRP in young women, especially in those who were obese. There was no evidence that this effect was mediated by changes in perceived stress, percent body fat, or fitness. These findings suggest that adopting an exercise routine early in life may decrease future risk of breast cancer and other chronic diseases in obese women.

Effect of diet with and without exercise training on markers of inflammation and fat distribution in overweight women

The independent effects of exercise and weight loss on markers of inflammation (MOI) in obese individuals have not been clearly characterized. The objectives of this study were to: (i) identify the independent effects of exercise and weight loss on MOI and (ii) determine whether changes in MOI were associated with changes in fat distribution. Subjects were 126 healthy, premenopausal women, BMI 27-30 kg/m(2). They were randomized to one of three groups: diet only, diet + aerobic-, or diet + resistance training until a BMI <25 kg/m(2) was achieved. Fat distribution was measured with computed tomography, and body composition with dual-energy X-ray absorptiometry. Serum concentrations of tumor necrosis factor (TNF)-α, soluble TNF receptor 1 (sTNF-R1), soluble TNF receptor 2 (sTNF-R2), C-reactive protein (CRP), and interleukin (IL)-6 were assessed. Results of repeated-measures ANOVA indicated a significant effect of time on MOI, such that MOI decreased with weight loss. Results of mixed-model analysis indicated that adjusting for intra-abdominal adipose tissue (IAAT) and total fat mass explained the decreases in TNF-α and sTNF-R1, whereas only total fat mass explained the decreases in sTNF-R2, IL-6, and CRP. In conclusion, weight loss was associated with decreases in MOI. The effect of weight loss appeared to be mediated by changes in total fat mass or IAAT. Addition of exercise did not alter the response, suggesting that weight loss has a more profound impact for reducing MOI in overweight women than exercise.

Increased proinflammatory and oxidant gene expression in circulating mononuclear cells in older adults: amelioration by habitual exercise

We tested the hypothesis that peripheral blood mononuclear cells (PBMC) of older adults demonstrate a proinflammatory/-oxidative gene expression profile that can be improved by regular aerobic exercise. PBMC were isolated from young (n = 25, 18-33 yr) and middle-aged/older (n = 40, 50-76 yr) healthy adults. The older adults had greater mRNA expression (real-time RT-PCR) of the proinflammatory/-oxidant transcription factor nuclear factor-κB (1.58-fold, P < 0.05) and receptor for advanced glycation end products (1.12-fold, P < 0.05), the proinflammatory cytokines tumor necrosis factor-α (1.90-fold, P < 0.05) and monocyte chemoattractant protein-1 (1.47-fold, P < 0.05), and the oxidant-producing enzymes nicotinamide adenine dinucleotide phosphate-oxidase (0.91-fold, P < 0.05) and inducible nitric oxide synthase (2.60-fold, P < 0.05). In 11 subjects (58-70 yr), maximal oxygen consumption (+11%) and exercise time (+19%) were increased (both P < 0.001), and expression of the above proinflammatory/-oxidative genes was or tended to be decreased in PBMC after vs. before 2 mo of aerobic exercise (brisk walking ∼6 days/wk, 50 min/day, 70% of maximal heart rate). Expression of interleukin-6 was not different with age or exercise intervention. Age group- and exercise intervention-related differences in gene expression were independent of other factors. PBMC of healthy older adults demonstrate increased expression of several genes associated with inflammation and oxidative stress, which is largely ameliorated by habitual aerobic exercise. This proinflammatory/-oxidative gene signature may represent a therapeutic target for lifestyle and pharmacological prevention and treatment strategies.

Effects of interventions on oxidative stress and inflammation of cardiovascular diseases

Excessive oxidative stress and low-grade chronic inflammation are major pathophysiological factors contributing to the development of cardiovascular diseases (CVD) such as hypertension, diabetes and atherosclerosis. Accumulating evidence suggests that a compromised anti-oxidant system can lead to excessive oxidative stress in cardiovascular related organs, resulting in cell damage and death. In addition, increased circulating levels of pro-inflammatory cytokines, such as tumor necrosis factor α, interleukin-6 and C-reactive protein, are closely related to morbidity and mortality of cardiovascular complications. Emerging evidence suggests that interventions including nutrition, pharmacology and exercise may activate expression of cellular anti-oxidant systems via the nuclear factor erythroid 2-related factor 2-Kelch-like ECH-associated protein 1 signaling pathway and play a role in preventing inflammatory processes in CVD. The focus of the present review is to summarize recent evidence showing the role of these anti-oxidant and anti-inflammatory interventions in cardiovascular disease. We believe that these findings may prompt new effective pathogenesis-oriented interventions, based on the exercise-induced protection from disease in the cardiovascular system, aimed at targeting oxidant stress and inflammation.

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.

Targeting inflammation to slow or delay functional decline: where are we?

The role of inflammation in the pathophysiology of chronic age-related diseases is increasingly recognized, and inflammation could represent the common pathway linking diseases and disability. Thus, targeting inflammation could represent a useful strategy at preventing or delaying functional decline. In this paper we review recent evidence suggesting that selected drugs, such as statins, fibrates, angiotensin converting enzyme-inhibitors and angiotensin receptor blockers, and physical exercise may be able to contrast functional decline by blunting inflammation. Results from randomized trials investigating the effects of physical activity programs on inflammation and functional decline is still limited, and further investigations are warranted.

The effect of aerobic versus strength-based training on high-sensitivity C-reactive protein in older adults

Increased levels of inflammatory markers, namely, high-sensitive C-reactive protein (hs-CRP), have been associated with several chronic diseases including atherosclerosis, type 2 diabetes and hypertension. Forty-five women and men aged >64 years participated in the study and were randomly assigned to two exercise intervention groups and a non-exercising control group. The participants assigned to the exercising groups followed a 16-week exercise protocol based either on aerobic training (AT) or strength training (ST) followed by a further 16 weeks off-training period. The control group (C) remained sedentary throughout the study. Evaluation of body mass, BMI, waist circumference, aerobic endurance, lower-body strength, upper-body strength, triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol and hs-CRP were performed at baseline, after 16 weeks (post-training for the exercise groups) and at 32 weeks (follow-up). Both, AT and ST groups significantly increased functional fitness at the end of the exercise programs when compared to baseline values. hs-CRP concentrations were maintained throughout the study for the C group, while decreasing 10% at 16 weeks and 51% at 32 weeks for the AT group. In the ST group the hs-CRP concentrations decreased by 11 and 39% at 16 and 32 weeks, respectively. Decreases in hs-CRP concentrations were statistically significant for the AT and ST groups at the 32-week evaluation when compared to baseline. Reduction in hs-CRP concentrations seemed to be associated with strength gains and adiposity loss.

Exercise training as a treatment for chronic inflammation in the elderly

Persistent subclinical inflammation predisposes to chronic disease, as well as the development of sarcopenia and disability, in frail elderly. Thus, the inflammatory pathway is a potential target for interventions to reduce aging-related disease and disability. This article highlights emerging data suggesting that increasing physical activity could be effective for reducing chronic inflammation in the elderly.

Effect of exercise training on chronic inflammation

Persistent, sub-clinical inflammation, as indicated by higher circulating levels of inflammatory mediators, is a prominent risk factor for several chronic diseases, as well as aging-related disability. As such, the inflammatory pathway is a potential therapeutic target for lifestyle interventions designed to reduce disease and disability. Physical exercise is well recognized as an important strategy for reducing the risk of chronic disease, and recent research has focused on its role in the improvement of the inflammatory profile. This review summarizes the evidence for and against the role of increasing physical activity in the reduction of chronic inflammation. Large population-based cohort studies consistently show an inverse association between markers of systemic inflammation and physical activity or fitness status, and data from several small-scale intervention studies support that exercise training diminishes inflammation. However, data from large, randomized, controlled trials designed to definitively test the effects of exercise training on inflammation are limited, and results are inconclusive. Future studies are needed to refine our understanding of the effects of exercise training on systemic low-grade inflammation, the magnitude of such an effect, and the amount of exercise necessary to elicit clinically meaningful changes in the deleterious association between inflammation and disease.

A yearlong exercise intervention decreases CRP among obese postmenopausal women

PURPOSE

To investigate the effect of a yearlong moderate-intensity aerobic exercise intervention on C-reactive protein (CRP), serum amyloid A (SAA), and interleukin 6 (IL-6) among overweight or obese postmenopausal women.

METHODS

In a randomized controlled trial, 115 postmenopausal, overweight or obese, sedentary women, aged 50-75 yr were randomized to an aerobic exercise intervention of moderate-intensity (60%-75% observed maximal HR), for > or = 45 min x d(-1), 5 d x wk (n = 53), or to a 1-d x wk(-1) stretching control (n = 62), on an intent-to-treat basis. CRP, SAA, and IL-6 were measured at baseline, at 3 months, and at 12 months.

RESULTS

From baseline to 12 months, CRP decreased 10% in exercisers and increased 12% in controls (P = 0.01); no effects were observed for SAA and IL-6. Among participants at baseline who were obese (body mass index (BMI) > or = 30 kg x m(-2)) or had abdominal obesity (waist circumference (WC) > or = 88 cm), exercise resulted in a more pronounced reduction in CRP (BMI > or = 30 kg x m(-2), P = 0.002; WC > or = 88 cm, P < 0.0001), borderline for SAA (BMI > or = 30 kg x m(-2), P = 0.08; WC > or = 88 cm, P = 0.04); no intervention effects were observed among women who did not have these characteristics. Overall, weight loss was minimal in the exercise intervention ( approximately 1.8 kg). Linear trends were observed between CRP and 12-month changes in aerobic fitness (Ptrend = 0.006), exercise adherence (Ptrend = 0.004), percentage body fat (Ptrend = 0.002), body weight (Ptrend = 0.002), WC (Ptrend = 0.02), and intra-abdominal fat (Ptrend = 0.03).

CONCLUSIONS

A moderate-intensity exercise intervention reduced CRP for 12 months among women who were obese at baseline. These findings support the role of exercise in modulating inflammatory processes that are related to increased risk of chronic disease among obese women.

The effect of a 12 week walking intervention on markers of insulin resistance and systemic inflammation

OBJECTIVES

The purpose of the present study was to determine whether a community-based walking intervention, using pedometers, is effective in reducing systemic inflammatory markers.

METHODS

Participants (age=49(8.9)) were recruited in Glasgow, United Kingdom, from August to December 2006 and were randomly assigned to a control (n=24; 6 males, no change in walking) and intervention group (n=24; 5 males gradually increasing walking by 3000 steps/day on 5 days of the week). Blood samples were collected at baseline, and after 12 weeks, and analysed for glucose, insulin, high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), tumour necrosis factor-alpha (TNF-alpha) and soluble TNF receptors I and II (sTNFR1 and sTNFRII).

RESULTS

In the control group baseline step counts were 6356 (2953) steps/day and did not change (P>0.05) after 12 weeks, 6709 (2918) steps/day. The intervention group increased (P<0.001) step count from 6682 (3761) steps/day at baseline to 10182 (4081) steps/day at 12 weeks. Over the 12 week period there was no change in any other variables measured, in either control or intervention group.

CONCLUSION

We conclude that the current community-based intervention did not affect systemic markers of inflammation or insulin sensitivity.

Exercise training and plasma C-reactive protein and interleukin-6 in elderly people

OBJECTIVES

To determine the effects of a long-term exercise intervention on two prominent biomarkers of inflammation (C-reactive protein (CRP) and interleukin-6 (IL-6)) in elderly men and women.

DESIGN

Single-blind, randomized, controlled trial: The Lifestyle Interventions and Independence for Elders (LIFE) Trial.

SETTING

The Cooper Institute, Dallas, Texas; Stanford University, Stanford, California; University of Pittsburgh, Pittsburgh, Pennsylvania; and Wake Forest University, Winston-Salem, North Carolina.

PARTICIPANTS

Four hundred twenty-four elderly (aged 70-89), nondisabled, community-dwelling men and women at risk for physical disability.

INTERVENTION

A 12-month moderate-intensity physical activity (PA) intervention and a successful aging (SA) health education intervention.

MEASUREMENTS

CRP and IL-6.

RESULTS

After adjustment for baseline IL-6, sex, clinic site, diabetes mellitus, treatment group, visit, and group-by-visit interaction, the PA intervention resulted in a lower (P=.02) IL-6 concentration than the SA intervention. Adjusted mean IL-6 at month 12 was 8.5% (0.21 pg/mL) higher in the SA than the PA group. There were no significant differences in CRP between the groups at 12 months (P=.09). Marginally significant interaction effects of the PA intervention according to baseline functional status (P=.05) and IL-6 (above vs below the median; P=.06) were observed. There was a greater effect of the PA intervention on participants with lower functional status and those with a higher baseline IL-6.

CONCLUSION

Greater PA results in lower systemic concentrations of IL-6 in elderly individuals, and this benefit is most pronounced in individuals at the greatest risk for disability and subsequent loss of independence.

No reduction in C-reactive protein following a 12-month randomized controlled trial of exercise in men and women

Low-grade systemic inflammation is suggested to play a role in the development of several chronic diseases including cancer. Higher levels of physical activity and lower adiposity have been associated with reduced levels of markers of systemic inflammation, such as C-reactive protein (CRP); however, reductions in CRP have not been consistently observed in randomized controlled trials of exercise.

PURPOSE

To examine the effect of a 12-month aerobic exercise intervention on CRP levels in men and women.

METHODS

One hundred two men and 100 women, sedentary and of ages 40 to 75 years, with mean body mass index (BMI) of 29.9 and 28.7 kg/m(2), respectively, were randomly assigned to a 12-month moderate-to-vigorous aerobic exercise intervention (6 d/wk, 60 min/d, 60-85% maximum heart rate) or control group. Fasting blood samples were collected at baseline and at 12 months. CRP levels were measured by high-sensitivity latex-enhanced nephelometry.

RESULTS

At baseline, CRP was 1.16 and 2.11 mg/L for men and women, respectively, and CRP was correlated with percent body fat (r = 0.48, P < or =0.001), BMI (r = 0.37, P < or = 0.001), and aerobic fitness (r = -0.49, P < or = 0.001). No intervention effects were observed for CRP in men or women, or when stratified by baseline BMI (<30 versus > or =30 kg/m(2)), baseline CRP (<3 versus > or =3 mg/L), or change in body weight, body composition, or aerobic fitness.

CONCLUSION

A 12-month moderate-to-vigorous aerobic exercise intervention did not affect CRP levels in previously sedentary men or women with average-risk CRP values at baseline.

Is regular exercise a friend or foe of the aging immune system? A systematic review

OBJECTIVE

The purpose of the current review is to synthesize the available evidence from prospective clinical trials that are relevant to the clinical question: "What, if any, are the effects of regular aerobic and/or resistance exercise on the immune system in healthy older adults?"

DATA SOURCES

Electronic databases were searched, using terms pertaining to immunology, exercise, and aging. Using the Ovid interface, the following databases were explored: Allied and Complimentary Medicine (AMED) (1985 to 2008), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 2008), all EBM Reviews (Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED), EMBASE (1980 to 2008), and MEDLINE (1950 to 2008). The MEDLINE database was searched a second time through the PubMed interface.

STUDY SELECTION

Prospective controlled clinical trials were selected for review if they investigated the effects of an exercise intervention (minimum 4 weeks in duration) on an immune outcome measure in an older but otherwise healthy population. A total of 19 articles representing 17 trials were identified.

DATA EXTRACTION

Quality assessment of the relevant articles was performed using the Jadad et al criteria. Data extraction was performed using a standardized instrument. Data regarding the participants, interventions, and laboratory and clinical immunologic outcomes were synthesized.

DATA SYNTHESIS

Available data provide no clear evidence of acute or chronic effects of exercise on lymphocyte or natural killer (NK) cell numbers or phenotype (ie, surface markers)/activity, with 2 exceptions: (1) strength or endurance exercise may cause an acute transient elevation in circulating CD8+ T cells, and (2) regular aerobic exercise appears to enhance immunologic memory in the context of vaccination. The effects of strength training on NK cell activity are unclear. Furthermore, regular aerobic exercise appears to be associated with a reduction in chronic inflammation. Finally, no prospective controlled trials have clearly documented clinical immunologic benefits of regular exercise, which may well relate to underpowering of these studies.

CONCLUSIONS

Overall, in healthy older adults, regular, particularly aerobic, exercise appears to be a friend of the immune system, helping to offset diminished adaptive responses and chronic inflammation. The possibility exists that particularly strenuous exercise may cause acute immunologic changes, such as diminished NK cell activity, which could predispose to infection in certain individuals. However, given the possible benefits of regular exercise on the immune system and the many definite benefits on other systems, the evidence presented here should not dissuade practitioners from suggesting regular exercise to otherwise healthy older adults.

Apolipoprotein E genotype and sex influence C-reactive protein levels regardless of exercise training status

C-reactive protein (CRP) is a marker for systemic inflammation and increased cardiovascular disease risk. Regular exercise may decrease CRP. Apolipoprotein E (apo E) has 3 common genotype variants--E2/3, 3/3, and 3/4--that modulate lipid metabolism and may have other metabolic physiologic roles, including some evidence that the genotype affects CRP levels. We assessed fasting serum CRP in 117 (male = 51, female = 66) healthy adults who volunteered for a 6-month aerobic exercise program. Both pre- and posttraining measurements were available in 71 (male = 31, female = 40) subjects. At baseline and follow-up, the numbers of subjects in the 3 groups were approximately equal: 2/3, n = 33 and 20; 3/3, n = 41 and 26; and 3/4, n = 43 and 25. At baseline, CRP levels differed by apo E genotype: means +/- SD were 2.84 +/- 2.18, 2.59 +/- 2.34, and 1.90 +/- 2.13 mg/L for E2/3, 3/3, and 3/4 subjects, respectively (3/4 vs 2/3, P < .05). In women, CRP was higher than that in men (3.14 +/- 2.49 vs 2.12 +/- 2.13 mg/L, P < .006). Exercise failed to affect CRP in the entire cohort (2.68 +/- 2.38 vs 2.52 +/- 2.48 mg/L) or in any apo E genotype group, and the apo E genotype effect observed at baseline persisted after training. In a largely white study cohort, CRP is higher in apo E3/3 than in 3/4 subjects and in women compared with men, but remains unchanged by 6 months of standard aerobic exercise training of the volume and higher intensity promoted by national organizations to reduce cardiovascular disease risk. How apo E genotype affects CRP is not known.

Immunological outcomes of exercise in older adults

Aging is associated with a dysregulation of the immune system known as immunosenescence. Immunosenescence involves cellular and molecular alterations that impact both innate and adaptive immunity, leading to increased incidences of infectious disease morbidity and mortality as well as heightened rates of other immune disorders such as autoimmunity, cancer, and inflammatory conditions. While current data suggests physical activity may be an effective and logistically easy strategy for counteracting immunosenescence, it is currently underutilized in clinical settings. Long-term, moderate physical activity interventions in geriatric populations appear to be associated with several benefits including reduction in infectious disease risk, increased rates of vaccine efficacy, and improvements in both physical and psychosocial aspects of daily living. Exercise may also represent a viable therapy in patients for whom pharmacological treatment is unavailable, ineffective, or inappropriate. The effects of exercise impact multiple aspects of immune response including T cell phenotype and proliferation, antibody response to vaccination, and cytokine production. However, an underlying mechanism by which exercise affects numerous cell types and responses remains to be identified. Given this evidence, an increase in the use of physical activity programs by the healthcare community may result in improved health of geriatric populations.

The Influence of Exercise Training on Inflammatory Cytokines and C-Reactive Protein

PURPOSE

The purpose of this study was to examine the influence of a 12-wk exercise training program on inflammatory cytokine and C-reactive protein (CRP) concentrations. A secondary purpose was to determine whether training-induced changes in cytokines and CRP were influenced by age.

METHODS

Twenty-nine younger (18-35 yr) and 31 older (65-85 yr) subjects were assigned to young physically active (YPA, N = 15; 25 +/- 5 yr), young physically inactive (YPI, N= 14; 25 +/- 4.7 yr), old physically active (OPA, N = 14; 71 +/- 4 yr), or old physically inactive (OPI, N = 17; 71 +/- 4 yr) groups. The inactive groups completed 12 wk (3 d.wk) of aerobic and resistance exercises, and the physically active control groups continued their normal exercise programs. Blood samples were collected before and after the 12-wk period, and the concentrations of serum CRP, plasma interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1beta) were determined using separate ELISA.

RESULTS

Control (YPA and OPA) estimated VO2max was unchanged. Exercise training increased estimated VO2max an average of 10.4% and increased strength by an average of 38.1% in both PI groups. Serum CRP decreased with training (YPI and OPI) groups and was not different from the YPA and OPA groups after training. Plasma IL-6 and IL-1beta did not change, whereas TNF-alpha was higher than YPI and YPA at baseline and after the intervention period.

CONCLUSION

These results support the use of combined aerobic/resistance training as a modality to reduce the risk of cardiovascular disease development as defined by a decrease in serum CRP concentration in healthy humans.