The anti-inflammatory effect of exercise: its role in diabetes and cardiovascular disease control

Exercise increases pancreatic β-cell viability in a model of type 1 diabetes through IL-6 signaling

Type 1 diabetes (T1D) is provoked by an autoimmune assault against pancreatic β cells. Exercise training enhances β-cell mass in T1D. Here, we investigated how exercise signals β cells in T1D condition. For this, we used several approaches. Wild-type and IL-6 knockout (KO) C57BL/6 mice were exercised. Afterward, islets from control and trained mice were exposed to inflammatory cytokines (IL-1β plus IFN-γ). Islets from control mice and β-cell lines (INS-1E and MIN6) were incubated with serum from control or trained mice or medium obtained from 5-aminoimidazole-4 carboxamide1-β-d-ribofuranoside (AICAR)-treated C2C12 skeletal muscle cells. Subsequently, islets and β cells were exposed to IL-1β plus IFN-γ. Proteins were assessed by immunoblotting, apoptosis was determined by DNA-binding dye propidium iodide fluorescence, and NO(•) was estimated by nitrite. Exercise reduced 25, 75, and 50% of the IL-1β plus IFN-γ-induced iNOS, nitrite, and cleaved caspase-3 content, respectively, in pancreatic islets. Serum from trained mice and medium from AICAR-treated C2C12 cells reduced β-cell death, induced by IL-1β plus IFN-γ treatment, in 15 and 38%, respectively. This effect was lost in samples treated with IL-6 inhibitor or with serum from exercised IL-6 KO mice. In conclusion, muscle contraction signals β-cell survival in T1D through IL-6.

Does 8 weeks of strenuous bicycle exercise improve diabetes-related inflammatory cytokines and free fatty acids in type 2 diabetes patients and individuals at high-risk of metabolic syndrome?

In the present study, the effects of 8 weeks of low volume high intensity interval training (HIIT) was investigated on circulating diabetes-related cytokines and free fatty acids (FFA) in adults with type 2 diabetes (T2D) and matched controls (CON).

METHODS

Participants exercised for 8 weeks (3 weekly sessions: 10 × 60 sec HIIT) on a cycle ergometer supervised by medical staff. Prior to the intervention and after the last HIIT session, venous blood samples were collected.

RESULTS

Circulating omentin-1 concentrations increased significantly in both the CON-group (p = 0.003) and in the T2D-group (p = 0.002). Pentraxin-3 (p = 0.010) and IL-1ra (p = 0.031) levels increased significantly in the CON-group. Plasma FFA in the T2D-group was significantly reduced after 60 min (p = 0.011). Post HIIT area under curve of circulating FFAs was reduced by -17.73 ± 6.99% (p = 0.041) in the T2D-group.

CONCLUSION

We observed only modest exercise-induced improvements of multiple diabetes-related cytokines. Circulating levels of FFAs were significantly lowered in the T2D-group.

Impact of training status on LPS-induced acute inflammation in humans

The aim of the present study was to examine the impact of training status on the ability to induce a lipopolysaccharide (LPS)-induced inflammatory response systemically as well as in skeletal muscle (SkM) and adipose tissue (AT) in human subjects. Seventeen young (23.8 ± 2.5 yr of age) healthy male subjects were included in the study with eight subjects assigned to a trained (T) group and nine subjects assigned to an untrained (UT) group. On the experimental day, catheters were inserted in the femoral artery and vein of one leg for blood sampling and a bolus of 0.3 ng LPS/kg body wt was injected into an antecubital vein in the forearm. Femoral arterial blood flow was measured by ultrasound Doppler, and arterial and venous blood samples were drawn before (Pre) LPS injection and 30, 60, 90, and 120 min after the LPS injection. Vastus lateralis muscle and abdominal subcutaneous AT biopsies were obtained Pre and 60 and 120 min after the LPS injection. LPS increased the systemic plasma TNFα and IL-6 level as well as the TNFα and IL-6 mRNA content in SkM and AT of both UT and T. However, whereas the LPS-induced inflammatory response in SkM was enhanced in T subjects relative to UT, the inflammatory response systemically and in AT was somewhat delayed in T subjects relative to UT. The present findings highlight that training status affects the ability to induce a LPS-induced acute inflammatory response in a tissue-specific manner.

The effect of a community-based, primary health care exercise program on inflammatory biomarkers and hormone levels

The aim of this study was to analyze the impact of a community-based exercise program in primary care on inflammatory biomarkers and hormone levels. The 1-year quasiexperimental study involved 13 women (mean age = 56.8 ± 11.4 years) and it was developed in two basic health care units in Rio Claro City, Brazil. The physical exercise intervention was comprised of two, 60-minute sessions/week. The inflammatory biomarkers were measured at baseline, 6 months, and 1 year. Repeated measures ANOVA analyses indicated that the intervention was effective in reducing CRP and TNFα after 1 year compared to baseline and 6 months (P < 0.05). There were no changes in IL10, IL6, and insulin after 1 year. However, leptin significantly increased at 1 year (P = 0.016). The major finding of this study is that a community-based exercise program can result in a decrease or maintenance of inflammatory biomarkers after 1 year, and thus has the potential to be a viable public health approach for chronic disease prevention.

Reductions in C-reactive protein in older adults with type 2 diabetes are related to improvements in body composition following a randomized controlled trial of resistance training

BACKGROUND

Reductions in skeletal muscle mass and increased adiposity are key elements in the aging process and in the pathophysiology of several chronic diseases. Systemic low grade inflammation associated with obesity has been shown to accelerate the age-related decline in skeletal muscle. The aim of this investigation was to determine the effects of 12 months of progressive resistance training (PRT) on systemic inflammation, and whether reductions in systemic inflammation were associated with changes in body composition. We hypothesized that reductions in systemic inflammation following 12 months of PRT in older adults with type 2 diabetes would be associated with reductions in adiposity and increases in skeletal muscle mass.

METHODS

Participants (n = 103) were randomized to receive either PRT or sham-exercise, 3 days a week for 12 months. C-reactive protein (CRP) was used to assess systemic inflammation. Skeletal muscle mass and total fat mass were determined using bioelectrical impedance.

RESULTS

Twelve months of PRT tended to reduce CRP compared to sham exercise (β = -0.25, p = 0.087). Using linear mixed-effects models, the hypothesized relationships between body composition adaptations and CRP changes were significantly stronger for skeletal muscle mass (p = 0.04) and tended to be stronger for total fat mass (p = 0.07) following PRT when compared to sham-exercise. Using univariate regression models, stratified by group allocation, reductions in CRP were associated with increases in skeletal muscle mass (p = 0.01) and reductions in total fat mass (p = 0.02) in the PRT group, but not in the sham-exercise group (p = 0.87 and p = 0.32, respectively).

CONCLUSIONS

We have shown for the first time that reductions in systemic inflammation in older adults with type 2 diabetes following PRT were associated with increases in skeletal muscle mass. Furthermore, reductions in CRP were associated with reductions in adiposity, but only when associated with PRT. Lifestyle interventions aimed at reducing systemic inflammation in older adults with type 2 diabetes should therefore incorporate anabolic exercise such as PRT to optimize the anti-inflammatory benefits of favorable body composition adaptations.

Exercise mitigates the adverse effects of hyperhomocysteinemia on macrophages, MMP-9, skeletal muscle, and white adipocytes

Regular exercise is a great medicine with its benefits encompassing everything from prevention of cardiovascular risk to alleviation of different muscular myopathies. Interestingly, elevated levels of homocysteine (Hcy), also known as hyperhomocysteinemia (HHcy), antagonizes beta-2 adrenergic receptors (β2AR), gamma amino butyric acid (GABA), and peroxisome proliferator-activated receptor-gamma (PPARγ) receptors. HHcy also stimulates an elevation of the M1/M2 macrophage ratio, resulting in a more inflammatory profile. In this review we discuss several potential targets altered by HHcy that result in myopathy and excessive fat accumulation. Several of these HHcy mediated changes can be countered by exercise and culminate into mitigation of HHcy induced myopathy and metabolic syndrome. We suggest that exercise directly impacts levels of Hcy, matrix metalloproteinase 9 (MMP-9), macrophages, and G-protein coupled receptors (GPCRs, especially Gs). While HHcy promotes the M1 macrophage phenotype, it appears that exercise may diminish the M1/M2 ratio, resulting in a less inflammatory phenotype. HHcy through its influence on GPCRs, specifically β₂AR, PPARγ and GABA receptors, promotes accumulation of white fat, whereas exercise enhances the browning of white fat and counters HHcy-mediated effects on GPCRs. Alleviation of HHcy-associated pathologies with exercise also includes reversal of excessive MMP-9 activation. Moreover, exercise, by reducing plasma Hcy levels, may prevent skeletal muscle myopathy, improve exercise capacity and rescue the obese phenotype. The purpose of this review is to summarize the pathological conditions surrounding HHcy and to clarify the importance of regular exercise as a method of disease prevention.

Beyond obesity and lifestyle: a review of 21st century chronic disease determinants

The obesity epidemic and associated chronic diseases are often attributed to modern lifestyles. The term "lifestyle" however, ignores broader social, economic, and environmental determinants while inadvertently "blaming the victim." Seen more eclectically, lifestyle encompasses distal, medial, and proximal determinants. Hence any analysis of causality should include all these levels. The term "anthropogens," or "…man-made environments, their by-products and/or lifestyles encouraged by these, some of which may be detrimental to human health" provides a monocausal focus for chronic diseases similar to that which the germ theory afforded infectious diseases. Anthropogens have in common an ability to induce a form of chronic, low-level systemic inflammation ("metaflammation"). A review of anthropogens, based on inducers with a metaflammatory association, is conducted here, together with the evidence for each in connection with a number of chronic diseases. This suggests a broader view of lifestyle and a focus on determinants, rather than obesity and lifestyle per se as the specific causes of modern chronic disease. Under such an analysis, obesity is seen more as "a canary in a mineshaft" signaling problems in the broader environment, suggesting that population obesity management should be focused more upstream if chronic diseases are to be better managed.

In case of obesity, longevity-related mechanisms lead to anti-inflammation

The exact mechanisms which contribute to longevity have not been figured out yet. Our aim was to find out a common way for prompting longevity by bringing together the well-known applications such as food restriction, exercise, and probiotic supplementing in an experimental obesity model. Experimental obesity was promoted in a total of 32 young (2 months old) and 32 aged (16 months old) male Wistar albino rats through 8-week cafeteria diet (salami, chocolate, chips, and biscuits). Old and young animals were divided into groups each consisting of eight animals and also divided into four subgroups as obese control, obese food restriction, obese probiotic-fed and obese exercise groups. Probiotic group diet contained 0.05 %w/total diet inactive and lyophilized Lactobacillus casei str. Shirota. The exercise group was subjected to treadmill running 1 h/day, at 21 m/min and at an uphill incline of 15 % for 5 days a week. Food restriction group was formed by giving 40 % less food than the others. The control group was fed regular pellet feed ad libitum. This program was continued for 16 weeks. Blood samples from all the groups were analyzed for fasting glucose, insulin, IGF-1, insulin-like growth factor binding protein 3 (IGFBP-3), interleukin (IL)-6, IL-12, malondialdehyde (MDA), fT3, TT3, fT4, TT4, and liver tissue MDA levels were measured. All applications showed anti-inflammatory effects through the observed changes in the levels of IGFBP-3, IL-6, and IL-12 in the young and old obese rats. While the interventions normally contribute to longevity by recruiting different action mechanisms, anti-inflammatory effect is the only mode of action for all the applications in the obesity model.

Exercise, but not quercetin, ameliorates inflammation, mitochondrial biogenesis, and lipid metabolism in skeletal muscle after strenuous exercise by high-fat diet mice

[Purpose]

The purpose of this study was to investigate whether moderate exercise and quercetin intake with a low fat diet contribute to inflammatory cytokine production, mitochondrial biogenesis, and lipid metabolism in skeletal muscle after strenuous exercise by high-fat diet mice.

[Methods]

Male C57BL/6 mice were randomly divided into four groups: (1) High-fat for 12 weeks and low-fat diet control (C; n = 6); (2) high-fat diet for 12 weeks and low-fat diet with quercetin (Q; n = 4); (3) high-fat diet for 12 weeks and low-fat diet with exercise (E; n = 4); or (4) high-fat diet for 12 weeks and low-fat diet with exercise and quercetin (EQ; n = 5). Quercetin (10 mg/kg) was administered once per day, 5 day/week for 8 weeks. Exercise training was performed at moderate intensity for 8 weeks, 5 days/week for 30–60 min/day. Mice were subjected to a strenuous exercise bout of 60 min at a speed of 25 m/min (VO₂ max 85%) conducted as an exercise-induced fatigue just before sacrifice.

[Results]

As results, body weights were significantly different among the groups. Exercise training significantly reduced inflammatory cytokines after strenuous exercise in skeletal muscle of high-fat diet mice. Exercise training increased Tfam mRNA in the soleus muscle after strenuous exercise. Exercise training significantly decreased lipogenesis markers in skeletal muscle of obese mice after strenuous exercise. Moderate exercise significantly increased lipolysis markers in the tibialis anterior muscle.

[Conclusion]

These findings suggest that exercise training reduced inflammatory cytokine levels and improved mitochondrial biogenesis and lipid metabolism. However quercetin supplementation did not affect these parameters. Thus, long-term moderate exercise training has positive effects on obesity.

Muscle as a secretory organ

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

Insulin signaling in skeletal muscle of HIV-infected patients in response to endurance and strength training

Human immunodeficiency virus (HIV)-infected patients with lipodystrophy have decreased insulin-stimulated glucose uptake. Both endurance and resistance training improve insulin-stimulated glucose uptake in skeletal muscle of HIV-infected patients, but the mechanisms are unknown. This study aims to identify the molecular pathways involved in the beneficial effects of training on insulin-stimulated glucose uptake in skeletal muscle of HIV-infected patients. Eighteen sedentary male HIV-infected patients underwent a 16 week supervised training intervention, either resistance or strength training. Euglycemic-hyperinsulinemic clamps with muscle biopsies were performed before and after the training interventions. Fifteen age- and body mass index (BMI)-matched HIV-negative men served as a sedentary baseline group. Phosphorylation and total protein expression of insulin signaling molecules as well as glycogen synthase (GS) activity were analyzed in skeletal muscle biopsies in relation to insulin stimulation before and after training. HIV-infected patients had reduced basal and insulin-stimulated GS activity (%fractional velocity, [FV]) as well as impaired insulin-stimulated Akt(thr308) phosphorylation. Despite improving insulin-stimulated glucose uptake, neither endurance nor strength training changed the phosphorylation status of insulin signaling proteins or affected GS activity. However; endurance training markedly increased the total Akt protein expression, and both training modalities increased hexokinase II (HKII) protein. HIV-infected patients with lipodystrophy have decreased insulin-stimulated glucose uptake in skeletal muscle and defects in insulin-stimulated phosphorylation of Akt(thr308). Endurance and strength training increase insulin-stimulated glucose uptake in these patients, and the muscular training adaptation is associated with improved capacity for phosphorylation of glucose by HKII, rather than changes in markers of insulin signaling to glucose uptake or glycogen synthesis.

Exercise-mediated improvements in painful neuropathy associated with prediabetes in mice

Recent research suggests that exercise can be effective in reducing pain in animals and humans with neuropathic pain. To investigate mechanisms in which exercise may improve hyperalgesia associated with prediabetes, C57Bl/6 mice were fed either standard chow or a high-fat diet for 12 weeks and were provided access to running wheels (exercised) or without access (sedentary). The high-fat diet induced a number of prediabetic symptoms, including increased weight, blood glucose, and insulin levels. Exercise reduced but did not restore these metabolic abnormalities to normal levels. In addition, mice fed a high-fat diet developed significant cutaneous and visceral hyperalgesia, similar to mice that develop neuropathy associated with diabetes. Finally, a high-fat diet significantly modulated neurotrophin protein expression in peripheral tissues and altered the composition of epidermal innervation. Over time, mice that exercised normalized with regards to their behavioral hypersensitivity, neurotrophin levels, and epidermal innervation. These results confirm that elevated hypersensitivity and associated neuropathic changes can be induced by a high-fat diet and exercise may alleviate these neuropathic symptoms. These findings suggest that exercise intervention could significantly improve aspects of neuropathy and pain associated with obesity and diabetes. Additionally, this work could potentially help clinicians determine those patients who will develop painful versus insensate neuropathy using intraepidermal nerve fiber quantification.

Whole-body cryostimulation as an effective method of reducing low-grade inflammation in obese men

This study was aimed to evaluate anti-inflammatory effect of the whole body cryostimulation in obese men. Fourteen subjects (BMI >30 kg m⁻²), divided into two subgroups according to cardiorespiratory fitness: higher (HCF) or lower (LCF), have been exposed to 10 sessions in a cryogenic chamber (−110 °C). Blood samples were collected before, 30 min and 24 h after the first, fifth and last cryostimulation. Coldness exposures affected blood cytokine profile; however, the response depended on subjects’ fitness capacity. Concentrations of pro-inflammatory cytokines in the LCF decreased by 19, 6.8, and 7.4 % in IL-6, resistin, and visfatin, respectively. TNFα in the LCF dropped 4.3-fold compared to baseline, while in the HCF, changes were smaller, yet significant. Anti-inflammatory cytokine IL-10 increased in both groups. No changes in adiponectin and leptin were observed in either group. Obtained results suggest that whole body cryostimulation can be a supplementary method for obese in reducing systemic inflammation.

Resistance training decreases serum inflammatory markers in diabetic rats

Inflammation plays an important role in the genesis and progression of diabetes. The purpose of this study was to investigate the effect of resistance training on serum levels of some inflammatory markers associated with diabetes mellitus. Twenty-four male Wistar rats (290 ± 19 g) were randomly divided into three groups: non-diabetic control (non-DC), diabetic control (DC), and diabetic trained (DT). Animals in DT group were subjected to a resistance training program with the use of a ladder (3 days/week, for 4 weeks). Body weight, serum high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, fasting glucose, and insulin were measured. Four weeks of resistance training decreased serum levels of TNF-α, hs-CRP, and IL-6 in diabetic rats when compared with DC animals. We conclude that resistance training with appropriate intensity, duration, and recovery between exercise bouts has marked anti-inflammatory effects on diabetic rats. This may be an efficient strategy to protect against some diabetic complications.

Influence of lifestyle factors on inflammation in men and women with type 2 diabetes: results from the National Health and Nutrition Examination Survey, 1999-2004

BACKGROUND

Type 2 diabetes is associated with low-grade systemic inflammation, increasing the risk for various adverse health outcomes.

PURPOSE

Our objective was to investigate the association between C-reactive protein (CRP), a marker for systemic inflammation, and lifestyle factors in a national sample of people with type 2 diabetes.

METHODS

This study analyzed data from 1,086 men and women with diabetes, who completed the 1999-2004 NHANES. Lifestyle factors included diet quality, body mass index (BMI), smoking, and physical activity.

RESULTS

Stratified logistic regression showed that for both men and women, BMI was a strong predictor of elevated CRP after adjusting for age, energy intake, race/ethnicity, medications, diabetes duration, and glycosylated hemoglobin. However, among men, but not among women, the likelihood of elevated CRP increased with lower diet quality and physical inactivity.

CONCLUSIONS

Among people with type 2 diabetes, higher levels of CRP were associated with lower diet quality and physical inactivity among men, and with obesity among both men and women.

Common genetic variation in the human FNDC5 locus, encoding the novel muscle-derived 'browning' factor irisin, determines insulin sensitivity

Aims/hypothesis

Recently, the novel myokine irisin was described to drive adipose tissue ‘browning’, to increase energy expenditure, and to improve obesity and insulin resistance in high fat-fed mice. Here, we assessed whether common single nucleotide polymorphisms (SNPs) in the FNDC5 locus, encoding the irisin precursor, contribute to human prediabetic phenotypes (overweight, glucose intolerance, insulin resistance, impaired insulin release).

Methods

A population of 1,976 individuals was characterized by oral glucose tolerance tests and genotyped for FNDC5 tagging SNPs. Subgroups underwent hyperinsulinaemic-euglycaemic clamps, magnetic resonance imaging/spectroscopy, and intravenous glucose tolerance tests. From 37 young and 14 elderly participants recruited in two different centres, muscle biopsies were obtained for the preparation of human myotube cultures.

Results

After appropriate adjustment and Bonferroni correction for the number of tested variants, SNPs rs16835198 and rs726344 were associated with in vivo measures of insulin sensitivity. Via interrogation of publicly available data from the Meta-Analyses of Glucose and Insulin-related traits Consortium, rs726344’s effect on insulin sensitivity was replicated. Moreover, novel data from human myotubes revealed a negative association between FNDC5 expression and appropriately adjusted in vivo measures of insulin sensitivity in young donors. This finding was replicated in myotubes from elderly men.

Conclusions/interpretation

This study provides evidence that the FNDC5 gene, encoding the novel myokine irisin, determines insulin sensitivity in humans. Our gene expression data point to an unexpected insulin-desensitizing effect of irisin.

Metabolic programming of MEST DNA methylation by intrauterine exposure to gestational diabetes mellitus

Epigenetic processes are primary candidates when searching for mechanisms that can stably modulate gene expression and metabolic pathways according to early life conditions. To test the effects of gestational diabetes mellitus (GDM) on the epigenome of the next generation, cord blood and placenta tissue were obtained from 88 newborns of mothers with dietetically treated GDM, 98 with insulin-dependent GDM, and 65 without GDM. Bisulfite pyrosequencing was used to compare the methylation levels of seven imprinted genes involved in prenatal and postnatal growth, four genes involved in energy metabolism, one anti-inflammatory gene, one tumor suppressor gene, one pluripotency gene, and two repetitive DNA families. The maternally imprinted MEST gene, the nonimprinted glucocorticoid receptor NR3C1 gene, and interspersed ALU repeats showed significantly decreased methylation levels (4-7 percentage points for MEST, 1-2 for NR3C1, and one for ALUs) in both GDM groups, compared with controls, in both analyzed tissues. Significantly decreased blood MEST methylation (3 percentage points) also was observed in adults with morbid obesity compared with normal-weight controls. Our results support the idea that intrauterine exposure to GDM has long-lasting effects on the epigenome of the offspring. Specifically, epigenetic malprogramming of MEST may contribute to obesity predisposition throughout life.

Serum irisin levels in new-onset type 2 diabetes

AIMS

Irisin has been identified as a novel myokine that drives brown-fat-like conversion of white adipose tissue. In this cross-sectional study, we investigated whether serum irisin levels are decreased in patients with type 2 diabetes (T2D) compared with control subjects with normal glucose tolerance (NGT), and assessed the association between serum irisin levels and various metabolic parameters.

METHODS

The study population was selected from a population-based study and included 104 subjects with NGT and 104 subjects with new-onset T2D. Serum irisin and adiponectin levels and metabolic parameters were measured. Multivariate logistic regression analysis was performed to assess the association between irisin levels and newly diagnosed T2D.

RESULTS

Serum irisin levels were significantly decreased in the new-onset T2D group compared with the NGT control group (p=0.003). In a multivariable model adjusted for various metabolic parameters, increased irisin levels were associated with reduced odds (OR 0.64, 95% CI 0.47-0.88, p=0.006) of prevalent newly diagnosed T2D. Furthermore, multiple regression analysis showed that 2 h plasma glucose was an independent variable influencing serum irisin levels (p=0.004).

CONCLUSION

In the present study, we found that serum irisin levels were decreased in T2D patients and inversely associated with newly diagnosed T2D, suggesting that irisin may play a crucial role in glucose intolerance and T2D.

The role of intratumoral and systemic IL-6 in breast cancer

Chronic low-grade inflammation plays an important role in the pathogenesis of several cancer forms including breast cancer. The pleiotropic cytokine IL-6 is a key player in systemic inflammation, regulating both the inflammatory response and tissue metabolism during acute stimulations. Here, we review the associations between IL-6 and breast cancer ranging from in vitro cell culture studies to clinical studies, covering the role of IL-6 in controlling breast cancer cell growth, regulation of cancer stem cell renewal, as well as breast cancer cell migration. Moreover, associations between circulating IL-6 and risk of breast cancer, prognosis for patients with prevalent disease, adverse effects and interventions to control systemic IL-6 levels in patients are discussed. In summary, direct application of IL-6 on breast cancer cells inhibits proliferation in estrogen receptor positive cells, while high circulating IL-6 levels are correlated with a poor prognosis in breast cancer patients. This discrepancy reflects distinct roles of IL-6, with elevated systemic levels being a biomarker for tumor burden, physical inactivity, and impaired metabolism, while local intratumoral IL-6 signaling is important for controlling breast cancer cell growth, metastasis, and self renewal of cancer stem cells.

Short-term exercise training improves insulin sensitivity but does not inhibit inflammatory pathways in immune cells from insulin-resistant subjects

Background. Exercise has an anti-inflammatory effect against, and immune cells play critical roles in the development, of insulin resistance and atherosclerotic vascular disease (AVD). Thus, the goal of this study was to determine whether exercise improves insulin sensitivity in insulin-resistant subjects by downregulating proinflammatory signaling in immune cells. Methods. Seventeen lean, 8 obese nondiabetic, and 11 obese type 2 diabetic individuals underwent an aerobic exercise program for 15 days and an insulin clamp before and after exercise. Peripheral mononuclear cells (PMNC) were obtained for determination of Toll-like receptor (TLR) 2 and 4 protein content and mitogen-activated protein kinase phosphorylation. Results. Compared with that in lean individuals, TLR4 protein content was increased by 4.2-fold in diabetic subjects. This increase in TLR4 content was accompanied by a 3.0-fold increase in extracellular signal-regulated kinase (ERK) phosphorylation. Exercise improved insulin sensitivity in the lean, obese, and type 2 diabetes groups. However, exercise did not affect TLR content or ERK phosphorylation. Conclusions. TLR4 content and ERK phosphorylation are increased in PMNC of type 2 diabetic individuals. While exercise improves insulin sensitivity, this effect is not related to changes in TLR2/TLR4 content or ERK phosphorylation in PMNC of type 2 diabetic individuals.

Influence of a low-dose cox-2 inhibitor drug on exercise-induced inflammation, muscle damage and lipid peroxidation

The purpose of this study was to examine the effect of acute low-dose celecoxib administration on exercise-induced inflammation, muscle damage and lipid peroxidation. Twenty healthy untrained males (age: 25.5±4.5 yrs, weight: 72.7±7.9 kg, height: 177.3±7.2 cm) were randomly assigned to treatment (T) or placebo (P) groups. Blood samples were obtained before, immediately after, 3 h after and 24 h after exercise. Subjects ran for 30 min at 75% V.O₂ max on a treadmill. Participants consumed 100 mg celecoxib or a placebo immediately after and 12 h after the immediately post-exercise blood sample. Total leukocytes, neutrophils, creatine kinase (CK), C-reactive protein (CRP) and malondialdehyde (MDA) were assessed at each time point. Significant increases in total leukocytes and neutrophils were observed 3 h after exercise in both groups (P < 0.05). CK and CRP levels were significantly increased immediately, 3 h and 24 h after exercise in both groups (P < 0.05). A significant increase in MDA was observed immediately after exercise in both groups (P < 0.05); however, no significant group differences were observed for MDA or CK. These findings suggest that inhibition of cyclo-oxygenase activity with low-dose celecoxib does not affect exercise-induced inflammation, muscle damage, or lipid peroxidation.

The effects of exercise modalities on adiposity in obese rats

OBJECTIVE

The aim of the present study was to evaluate the effect of both swimming and resistance training on tumor necrosis factor-alpha and interleukin-10 expression, adipocyte area and lipid profiles in rats fed a high-fat diet.

METHODS

The study was conducted over an eight-week period on Wistar adult rats, who were divided into six groups as follows (n = 10 per group): sedentary chow diet, sedentary high-fat diet, swimming plus chow diet, swimming plus high-fat diet, resistance training plus chow diet, and resistance training plus high-fat diet. Rats in the resistance training groups climbed a vertical ladder with weights on their tails once every three days. The swimming groups swam for 60 minutes/day, five days/week.

RESULTS

The high-fat diet groups had higher body weights, a greater amount of adipose tissue, and higher tumor necrosis factor-alpha expression in the visceral adipose tissue. Furthermore, the high-fat diet promoted a negative change in the lipid profile. In the resistance training high-fat group, the tumor necrosis factor-alpha expression was lower than that in the swimming high-fat and sedentary high-fat groups. Moreover, smaller visceral and retroperitoneal adipocyte areas were found in the resistance training high-fat group than in the sedentary high-fat group. In the swimming high-fat group, the tumor necrosis factor-alpha expression was lower and the epididymal and retroperitoneal adipocyte areas were smaller compared with the sedentary high-fat group.

CONCLUSION

The results showed that both exercise modalities improved the lipid profile, adiposity and obesity-associated inflammation in rats, suggesting their use as an alternative to control the deleterious effects of a high-fat diet in humans.

Resistance exercise modulates lipid plasma profile and cytokine content in the adipose tissue of tumour-bearing rats

Cancer cachexia is a multifactorial syndrome characterised by progressive weight loss, frequently accompanied by anorexia, sarcopenia, and chronic systemic inflammation. The white adipose tissue is markedly affected by cachexia and contributes to this syndrome throught the secretion of pro-inflammatory factors which reach the adjacent tissues and the circulation. A nonpharmacologic intervention that may attenuate cancer cachexia is chronic physical activity, but the effect of resistance training upon adipose tissue inflammation in cachexia has never been examined. For that purpose we designed a protocol in which animals were randomly assigned to a control group (CT, n=7), a Tumour bearing group (TB, n=7), a Resistance Trained group (RT, n=7) and a Resistance Trained tumour bearing group (RTTB, n=7). Trained rats climbed a vertical ladder with an extra load attached to the tail, representing 75-90% of total body mass, 3 times per week, for 8 weeks. In the 6 th week of resistance training, tumour cells (3 × 10(7) Walker 256 carcinosarcoma) were inoculated in the tumour groups. Body, adipose tissue, muscle and tumour mass was determined, as well a blood biochemical parameters, and the hormone and cytokine profile assessed. The glycogen content of the liver and muscle was measured. IL-10, IL-6 and TNF-α protein expression was evaluated in the mesenteric adipose tissue (MEAT) examined. Resistance training increased by 9% body weight gain in RTTB (final weight 310.8 ± 9.8 g), when compared with TB (final weight 288.3 ± 4.9 g). LDL-c levels were decreased in RTTB (0.28 ± 0.9 mmol/L) by 43% when compared with TB (0.57 ± 0.1 mmol/L). HDL-c levels were increased in RTTB (1.31 ± 0.12 mmol/L) by 15% in regard to CT (1.13 ± 0.7 mmol/L) and 22% as compared with TB (1.07 ± 0.07 mmol/L). RTTB testosterone levels (577 ± 131 ng/mL) were 55% higher when compared with CT (254 ± 41.3 ng/mL) and 63% higher when compared with TB (221 ± 23.1 ng/mL). Adiponectin levels were augmented in RT (23 μg/mL) by 43% when compared with TB (11 μg/mL). Protein expression of IL-6 was increased 38% in TB MEAT (5.95 pg/μg), as compared with CT (3.64 pg/μg) and 50% compared with RTTB (2.91 pg/μg). Similar results with respect to TNF-α TB (7.18 pg/μg) were observed: 39% and 46%, higher protein expression in comparison with CT (4.63 pg/μg) and RTTB (3.8 pg/μg), respectively. IL-10 protein expression was found to be increased in TB (4.4 pg/μg) and RTTB (3.2 pg/μg) 50% and 47%, respectively, in comparison with CT (1.2 pu/μg). The IL-10/TNF-α ratio was higher in RTTB in relation to all others experimental groups. The results show a robust effect of resistance exercise training in preventing important symptoms of cancer cachexia, thus strongly suggesting it may appear as an alternative to endurance exercise as a non-pharmacological therapy in the management of this syndrome.

Prostaglandin E2: from clinical applications to its potential role in bone- muscle crosstalk and myogenic differentiation

Prostaglandin E(2) (PGE(2)), a prostanoid synthesized from arachidonic acid via the cyclooxygenase pathway, is a modulator of physiological responses including inflammation, fever, and muscle regeneration. Several patents have been filed that are related to PGE(2), one of them being directly related to skeletal muscles. In this report, we first summarize the key patents describing inventions for the utilization of PGE(2) for either diagnostic or therapeutic purposes, including skeletal muscle. In the second part of our work we present new and exciting data that demonstrates that PGE(2) accelerates skeletal muscle myogenic differentiation. Our discovery resulted from our recent and novel concept of bone-muscle crosstalk. Bone and muscle are anatomically intimate endocrine organs and we aimed to determine whether this anatomical intimacy also translates into a biochemical communication from bone cells to muscle cells at the in vitro level. The effects of MLOY4 osteocyte-like cell conditioned medium (CM) and three osteocyte-secreted factors, PGE(2), sclerostin and monocyte chemotactic protein (MCP-3), on C2C12 myogenic differentiation were evaluated using morphological analyses, a customized 96-gene PCR array, and measurements of intracellular calcium levels. MLO-Y4 CM and PGE(2), but not sclerostin and MCP-3, induced acceleration of myogenesis of C2C12 myoblasts that was linked with significant modifications in intracellular calcium homeostasis. This finding should further stimulate the pursuit of new patents to explore the use of PGE(2) and the new concept of bone-muscle crosstalk for the development and application of inventions designed to treat muscle diseases characterized by enhanced muscle wasting, such as sarcopenia.

A short-term diet and exercise intervention ameliorates inflammation and markers of metabolic health in overweight/obese children

The present study was designed to examine the effects of short-term diet and exercise on markers of metabolic health, serum-stimulated production of inflammatory biomarkers from cultured monocytes and adipocytes, and serum lipomics. Twenty-one overweight/obese children (9 boys and 12 girls, age 13.0 ± 0.5 yr, BMI 33.0 ± 1.8 kg/m(2)) were placed on a 2-wk ad libitum, high-fiber, low-fat diet and daily exercise regimen. Fasting serum samples were taken pre- and postintervention for determination of cytokines, metabolic risk markers, and lipomics. Monocytes and adipocytes were incubated with pre- and postintervention serum to investigate changes in cytokine secretion. Correlative associations were calculated, followed by hierarchical clustering to determine relationships between fatty acid (FA) species and clinical biomarkers. Despite remaining overweight/obese, interleukin (IL)-6, IL-8, TNFα, PAI-1, resistin, amylin, leptin, insulin, and IL-1ra decreased and adiponectin increased. Culture studies indicated decreases in monocyte secretion of IL-6, TNFα, and IL-1β and adipocyte secretion of IL-6. Lipomic analysis revealed a decrease in total lipids and decreases in saturated FAs and an increase in 18:1/18:0. In general, Pearson's correlations revealed that inflammatory markers are negatively associated with a cluster of polyunsaturated FAs and positively correlated with several saturated FAs. These results indicate significant modification of multiple indices of metabolic health with short-term rigorous lifestyle modification in overweight/obese children prior to obesity reversal.

Persistence of inflammatory response to intense exercise in diabetic rats

In this study we evaluated the onset and resolution of inflammation in control and streptozotocin-induced diabetic rats subjected to a single session of intense exercise. The following measurements were carried out prior to, immediately after, and 2 and 24 hours after exercise: plasma levels of proinflammatory cytokines (TNF-α, IL-1β, IL-6, CINC-2α/β, MIP-3α, and IL-6), immunoglobulins (IgA and IgM), acute phase proteins (CRP and C3), and creatine kinase (CK) activity. We also examined the occurrence of macrophage death by measurements of macrophages necrosis (loss of membrane integrity) and DNA fragmentation. An increase was observed in the concentration of IL-1β (3.3-fold) and TNF-α (2.0-fold) and in the proportion of necrotic macrophages (4.5-fold) in diabetic rats 24 hours after exercise, while the control group showed basal measurements. Twenty-four hours after the exercise, serum CK activity was elevated in diabetic rats but not in control animals. We concluded that lesion and inflammations resulting from intense exercise were greater and lasted longer in diabetic animals than in nondiabetic control rats.

Effect of interval training program on white blood cell count in the management of hypertension: A randomized controlled study

OBJECTIVE

Elevated white blood cell (WBC) count is considered to be prospectively and positively associated with cardiovascular diseases, particularly hypertension. Also, the positive role of exercise in the management of hypertension has been well and long established. However the relationship between WBC count and hypertensive management particularly in the nonpharmacological technique is ambiguous and unclear. Therefore the purpose of the present study was to determine the effect of interval training program on WBC count and cardiovascular parameters in male hypertensive patients.

MATERIALS AND METHODS

A total of 245 male patients with mild to moderate (systolic blood pressure (SBP) between 140 mmHg and 179 mmHg and diastolic blood pressure (DBP) between 90 mmHg and 109 mmHg) essential hypertension were age matched and grouped into experimental and control groups. The experimental (n=140; 58.90±7.35 years) group involved in an 8-week interval training (60-79% HR max reserve) program of between 45 minutes to 60 minutes, while the age-matched controls hypertensive (n=105; 58.27±6.24 years) group remain sedentary during this period. Cardiovascular parameters (SBP, DBP, and VO(2) max) and WBC count were assessed. Student's t and Pearson correlation tests were used in data analysis.

RESULTS

Findings of the study revealed a significant effect of the interval training program on VO2max, SBP, and DBP and WBC count at P<0.05 and VO2max is negatively related to the WBC count (r=-0.339) at P<0.01.

CONCLUSIONS

It was concluded that the interval training program is an effective adjunct nonpharmacological management of hypertension and the therapeutic effect of exercise programs may be mediated through suppression of inflammatory (WBC count) reaction.

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

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

Effect of kidney failure and hemodialysis on protein and amino acid metabolism

PURPOSE OF REVIEW

Despite technological innovations in renal replacement therapy, mortality is still high in patients with end-stage renal disease. This increase in mortality is not only limited to dialysis patients, but also includes all stages of chronic kidney disease (CKD) and is mainly because of cardiovascular disease. Protein-energy wasting becomes clinically manifest at an advanced CKD stage, early before or during the dialytic stage, and increases the morbidity and mortality in this patients' population. The purpose of this article is to review the recent observations on alterations of amino acid and protein metabolism which cause wasting and increase cardiovascular risk.

RECENT FINDINGS

Recent studies have consistently increased our understanding of mechanisms causing wasting and vascular disease in CKD patients. These include changes in amino acid and lipoprotein metabolism potentially leading to alterations of biology and function of the vascular wall, anorexia and endocrine dysfunction, altered muscle intracellular signaling through the insulin receptor substrate/phosphatidylinositol 3-kinase/Akt pathway, and defective myocyte regeneration. These mechanisms may trigger wasting through an increase in protein degradation and/or acceleration of apoptotic processes in skeletal muscle and may be accelerated by hemodialysis, leading to progression of vascular disease and wasting.

SUMMARY

The new understanding holds promise for new treatments which can prevent/treat vascular diseases and wasting in CKD patients.

Reproducible isolation of lymph node stromal cells reveals site-dependent differences in fibroblastic reticular cells

Within lymph nodes, non-hematopoietic stromal cells organize and interact with leukocytes in an immunologically important manner. In addition to organizing T and B cell segregation and expressing lymphocyte survival factors, several recent studies have shown that lymph node stromal cells shape the naïve T cell repertoire, expressing self-antigens which delete self-reactive T cells in a unique and non-redundant fashion. A fundamental role in peripheral tolerance, in addition to an otherwise extensive functional portfolio, necessitates closer study of lymph node stromal cell subsets using modern immunological techniques; however this has not routinely been possible in the field, due to difficulties reproducibly isolating these rare subsets. Techniques were therefore developed for successful ex vivo and in vitro manipulation and characterization of lymph node stroma. Here we discuss and validate these techniques in mice and humans, and apply them to address several unanswered questions regarding lymph node composition. We explored the steady-state stromal composition of lymph nodes isolated from mice and humans, and found that marginal reticular cells and lymphatic endothelial cells required lymphocytes for their normal maturation in mice. We also report alterations in the proportion and number of fibroblastic reticular cells (FRCs) between skin-draining and mesenteric lymph nodes. Similarly, transcriptional profiling of FRCs revealed changes in cytokine production from these sites. Together, these methods permit highly reproducible stromal cell isolation, sorting, and culture.

Hypothalamic inflammation is reversed by endurance training in anorectic-cachectic rats

Aim

We tested the effects of a cancer cachexia-anorexia sydrome upon the balance of anti and pro-inflammatory cytokines in the hypothalamus of sedentary or trained tumour-bearing (Walker-256 carcinosarcoma) rats.

Methods

Animals were randomly assigned to a sedentary control (SC), sedentary tumour-bearing (ST), and sedentary pair-fed (SPF) groups or, exercised control (EC), exercised tumour-bearing (ET) and exercised pair-fed (EPF) groups. Trained rats ran on a treadmill (60%VO_2max) for 60 min/d, 5 days/wk, for 8 wks. We evaluated food intake, leptin and cytokine (TNF-α, IL1β) levels in the hypothalamus.

Results

The cumulative food intake and serum leptin concentration were reduced in ST compared to SC. Leptin gene expression in the retroperitoneal adipose tissue (RPAT) was increased in SPF in comparison with SC and ST, and in the mesenteric adipose tissue (MEAT) the same parameter was decreased in ST in relation to SC. Leptin levels in RPAT and MEAT were decreased in ST, when compared with SC. Exercise training was also able to reduce tumour weight when compared to ST group. In the hypothalamus, IL-1β and IL-10 gene expression was higher in ST than in SC and SPF. Cytokine concentration in hypothalamus was higher in ST (TNF-α and IL-1β, p < 0.05), compared with SC and SPF. These pro-inflammatory cytokines concentrations were restored to control values (p < 0.05), when the animals were submitted to endurance training.

Conclusion

Cancer-induced anorexia leads towards a pro-inflammatory state in the hypothalamus, which is prevented by endurance training which induces an anti-inflammatory state, with concomitant decrease of tumour weight.

Transcriptome-wide gene regulation by gentle treadmill walking during the progression of monoiodoacetate-induced arthritis

OBJECTIVE

Physiotherapies are the most widely recommended conservative treatment for arthritic diseases. The present study was undertaken to examine the molecular mechanisms underlying the effects of gentle treadmill walking (GTW) on various stages of monoiodoacetate-induced arthritis (MIA) to elucidate the basis for the success or failure of such therapies in joint damage.

METHODS

Knees were obtained from untreated control rats, rats with MIA that did not undergo GTW, rats with MIA in which GTW regimens were started 1 day post-MIA induction, and rats with MIA in which GTW regimens were started after cartilage damage had progressed to grade 1 or grade 2. The cartilage was examined macroscopically, microscopically, and by microfocal computed tomography imaging. Transcriptome-wide gene expression analysis was performed, and microarray data were assessed by Ingenuity Pathways Analysis to identify molecular functional networks regulated by GTW.

RESULTS

GTW intervention started on day 1 post-MIA induction significantly prevented the progression of MIA, but its efficacy was reduced when implemented on knees exhibiting close to grade 1 cartilage damage. GTW accelerated cartilage damage in knees with close to grade 2 damage. Transcriptome-wide gene expression analysis revealed that GTW intervention started 1 day post-MIA inception significantly suppressed inflammation-associated genes and up-regulated matrix-associated gene networks. However, delayed GTW intervention after grade 1 damage had occurred was less effective in suppressing proinflammatory genes or up-regulating matrix synthesis.

CONCLUSION

The present findings suggest that GTW suppresses proinflammatory gene networks and up-regulates matrix synthesis to prevent progression of cartilage damage in MIA-affected knees. However, the extent of cartilage damage at the initiation of GTW may be an important determinant of the success or failure of such therapies.

The interleukin-6 and noradrenaline mediated inflammation-stress feedback mechanism is dysregulated in metabolic syndrome: effect of exercise

Background

Metabolic syndrome (MS) is a metabolic disorder associated with obesity, type-II diabetes, and "low grade inflammation", with the concomitant increased risk of cardiovascular events. Removal of the inflammatory mediator signals is a promising strategy to protect against insulin resistance, obesity, and other problems associated with MS such as cardiovascular disease. The aim of the present investigation was to determine the "inflammatory and stress status" in an experimental model of MS, and to evaluate the effect of a program of habitual exercise and the resulting training-induced adaptation to the effects of a single bout of acute exercise.

Methods

Obese Zucker rats (fa/fa) were used as the experimental model of MS, and lean Zucker rats (Fa/fa) were used for reference values. The habitual exercise (performed by the obese rats) consisted of treadmill running: 5 days/week for 14 weeks, at 35 cm/s for 35 min in the last month. The acute exercise consisted of a single session of 25-35 min at 35 cm/s. Circulating concentrations of IL-6 (a cytokine that regulates the inflammatory and metabolic responses), CRP (a systemic inflammatory marker), and corticosterone (CTC) (the main glucocorticoid in rats) were determined by ELISA, and that of noradrenaline (NA) was determined by HPLC. Glucose was determined by standard methods.

Results

The genetically obese animals showed higher circulating levels of glucose, IL-6, PCR, and NA compared with the control lean animals. The habitual exercise program increased the concentration of IL-6, PCR, NA, and glucose, but decreased that of CTC. Acute exercise increased IL-6, CRP, and NA in the sedentary obese animals, but not in the trained obese animals. CTC was increased after the acute exercise in the trained animals only.

Conclusion

Animals with MS present a dysregulation in the feedback mechanism between IL-6 and NA which can contribute to the systemic low-grade inflammation and/or hyperglycaemia of MS. An inappropriate exercise intensity can worsen this dysregulation, contributing to the metabolic, inflammatory, and stress disorders associated with MS. Habitual exercise (i.e., training) induces a positive adaptation in the response to acute exercise.

Non-nutrient causes of low-grade, systemic inflammation: support for a 'canary in the mineshaft' view of obesity in chronic disease

A form of low-grade, systemic inflammation ('metaflammation') is linked to many types of chronic disease. Initially, this was thought to be causally related to weight gain and obesity and a possible explanation of the link between obesity and disease. However, several lifestyle-related inducers of such inflammation, some of which are associated with obesity, but some of which are not, have now been identified. The most common of these have been nutritive related, suggesting that there could still be a relationship, either directly or indirectly, with obesity. Here we provide evidence for non-nutritive inflammatory inducers, providing further support for an earlier suggestion that while obesity, beyond a point, may have a direct link with disease, this may be neither necessary nor sufficient to explain the current epidemic of chronic disease. A more ubiquitous cause encompassing all inflammatory inducers is the modern, post-industrial environment and lifestyles emanating from this. Obesity may thus be more of 'a canary in the mineshaft', warning of bigger global problems, than just a single pathway to modern environmentally driven disease.

Muscles and their myokines

In the past, the role of physical activity as a life-style modulating factor has been considered as that of a tool to balance energy intake. Although it is important to avoid obesity, physical inactivity should be discussed in a much broader context. There is accumulating epidemiological evidence that a physically active life plays an independent role in the protection against type 2 diabetes, cardiovascular diseases, cancer, dementia and even depression. For most of the last century, researchers sought a link between muscle contraction and humoral changes in the form of an 'exercise factor', which could be released from skeletal muscle during contraction and mediate some of the exercise-induced metabolic changes in other organs such as the liver and the adipose tissue. We have suggested that cytokines or other peptides that are produced, expressed and released by muscle fibres and exert autocrine, paracrine or endocrine effects should be classified as 'myokines'. Given that skeletal muscle is the largest organ in the human body, our discovery that contracting skeletal muscle secretes proteins sets a novel paradigm: skeletal muscle is an endocrine organ producing and releasing myokines, which work in a hormone-like fashion, exerting specific endocrine effects on other organs. Other myokines work via paracrine mechanisms, exerting local effects on signalling pathways involved in muscle metabolism. It has been suggested that myokines may contribute to exercise-induced protection against several chronic diseases.

In humans IL-6 is released from the brain during and after exercise and paralleled by enhanced IL-6 mRNA expression in the hippocampus of mice

AIM

Plasma interleukin-6 (IL-6) increases during exercise by release from active muscles and during prolonged exercise also from the brain. The IL-6 release from muscles continues into recovery and we tested whether the brain also releases IL-6 in recovery from prolonged exercise in humans. Additionally, it was evaluated in mice whether brain release of IL-6 reflected enhanced IL-6 mRNA expression in the brain as modulated by brain glycogen levels.

METHODS

Nine healthy male subjects completed 4 h of ergometer rowing while the arterio-jugular venous difference (a-v diff) for IL-6 was determined. The IL-6 mRNA and the glycogen content were determined in mouse hippocampus, cerebellum and cortex before and after 2 h treadmill running (N = 8).

RESULTS

At rest, the IL-6 a-v diff was negligible but decreased to -2.2 ± 1.9 pg ml(-1) at the end of exercise and remained low (-2.1 ± 2.1 pg ml(-1) ) 1 h into the recovery (P < 0.05 vs. rest). IL-6 mRNA was expressed in the three parts of the brain with the lowest content in the hippocampus (P < 0.05) coupled to the highest glycogen content (3.2 ± 0.8 mmol kg(-1) ). Treadmill running increased the hippocampal IL-6 mRNA content 2-3-fold (P < 0.05), while the hippocampal glycogen content decreased to 2.6 ± 0.6 mmol kg(-1) (P < 0.05) with no significant changes in the two other parts of the brain.

CONCLUSION

Human brain releases IL-6 both during and in recovery from prolonged exercise and mouse data suggest that concurrent changes in IL-6 mRNA and glycogen levels make the hippocampus a likely source of the IL-6 release from the brain.

Clinical relevance of serum vascular endothelial growth factor and interleukin-6 in patients with colorectal cancer

BACKGROUND/AIM

Some biological factors play a role in stimulation of malignant growth, metastasis and angiogenesis; however, their clinical relevance has not yet been well established for most of them. This work was aimed at studying the clinical relevance of serum vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6), in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

Preoperative serum levels of VEGF and IL-6 were measured by enzyme-linked immuno-assay in 35 CRC patients and in 30 healthy controls.

RESULTS

CRC patients with or without metastasis had significantly higher VEGF and IL-6 levels than healthy controls (all P < 0.001). Patients with advanced clinical stage had significantly higher levels of VEGF and IL-6 than those with early clinical stage (all P < 0.001). Also, patients with metastatic disease had significantly higher VEGF and IL-6 levels than those with localized disease (all P < 0.001). The diagnostic accuracy for invasiveness was 83% for VEGF (cut off value = 240 pg/ml) and 66% for IL-6 (cut off value = 6.7 pg/ml), with sensitivity 79% and 74% and specificity 68% and 59%, respectively.

CONCLUSION

In CRC patients, preoperative measurement of serum VEGF and Il-6 may prove useful non-invasive diagnostic indicators associated with advanced clinical stage and tumor metastasis that warrants further investigations.