The reliability of the IL-6, sIL-6R and sgp130 response to a preloaded time trial

Elevated Plasma IL-6 Coincides with Activation of STAT3 in PBMC After Acute Resistance Exercise

INTRODUCTION

Changes in plasma concentrations of anti-inflammatory cytokines, such as interleukin-6 (IL-6) and IL-10, after acute resistance exercise (RE) have been widely explored. Whether observed changes in plasma cytokine concentration correspond to the activation of anti-inflammatory signaling pathways in immune cells after acute RE is unknown. This study aimed to determine if changes in plasma cytokines after acute RE resulted in the activation of anti-inflammatory signaling pathways in peripheral blood mononuclear cells (PBMC).

METHODS

Healthy young males (N = 16; age = 23.5 ± 2.7 yr; BMI = 22.4 ± 1.7 kg·m-2) participated in a single session of whole-body RE (4 sets of 4 different exercises at 70% 1-repetition maximum with the last set to failure) and a sedentary control (CON) condition in a randomized crossover design. Blood samples were collected at several time points before and after the exercise bout.

RESULTS

Higher plasma IL-6, IL-10, and IL-1 RA concentrations were observed after RE compared with CON. Phosphorylation of STAT3 and protein expression of SOCS3 in PBMC were increased in RE compared with CON. The elevation of plasma IL-6, but not IL-10, coincided with the activation of STAT3 signaling in PBMC.

CONCLUSIONS

These results highlight a potential mechanism by which RE may exert anti-inflammatory actions in circulating immune cells.

Myokine secretion during moderate-intensity physical activity: Dose-response of interleukin 6 to walking duration

During vigorous physical activity, contracting muscles secrete a variety of immunomodulatory and metabolic factors called myokines that perform a variety of functions. Foremost among these is interleukin 6 (IL-6), which increases fatty acid mobilization and stimulates anti-inflammatory cytokine release. Despite being well characterized in vigorous exercise contexts, whether IL-6 is secreted during moderate-intensity activities such as walking is unclear. This is especially pertinent as regular walking is one of the oldest and most common forms of physical activity and comes with a variety of health benefits, which may be coordinated in part by IL-6 signaling. To test the hypothesis that IL-6 release occurs during evolutionarily normal physical activity contexts like long distance walking, we performed a dose-response experiment to test the effect of walking duration on IL-6 secretion. Thirteen participants completed four moderate-intensity walking trials (55% HRmax) of varying durations (30 min, 1 h, 2 h, and 3 h) in a randomized order with intervening washout periods of at least 1 week. Using a linear mixed effects model, we found that IL-6 levels modestly increased during only the 2 h and 3 h walking trials. These results suggest that small frequent increases in IL-6 signaling may be an important mechanism underlying the health benefits of regular walking. Furthermore, this finding raises the possibility that IL-6 secretion is an adaptation to fuel physical activity, especially during periods of negative energy balance.

The exercise IL-6 enigma in cancer

Interleukin (IL)-6 elicits both anticancer and procancer effects depending on the context, which we have termed the 'exercise IL-6 enigma'. IL-6 is released from skeletal muscles during exercise to regulate short-term energy availability. Exercise-induced IL-6 provokes biological effects that may protect against cancer by improving insulin sensitivity, stimulating the production of anti-inflammatory cytokines, mobilising immune cells, and reducing DNA damage in early malignant cells. By contrast, IL-6 continuously produced by leukocytes in inflammatory sites drives tumorigenesis by promoting chronic inflammation and activating tumour-promoting signalling pathways. How can a molecule have such opposing effects on cancer? Here, we review the roles of IL-6 in chronic inflammation, tumorigenesis, and exercise-associated cancer prevention and define the factors that underpin the exercise IL-6 enigma.

IL-6 signaling in acute exercise and chronic training: Potential consequences for health and athletic performance

The cytokine interleukin-6 (IL-6) is involved in a diverse set of physiological processes. Traditionally, IL-6 has been thought of in terms of its inflammatory actions during the acute phase response and in chronic conditions such as rheumatoid arthritis and obesity. However, IL-6 is also an important signaling molecule during exercise, being acutely released from working muscle fibers with increased exercise duration, intensity, and muscle glycogen depletion. In this context, IL-6 enables muscle-organ crosstalk, facilitating a coordinated response to help maintain muscle energy homeostasis, while also having anti-inflammatory actions. The range of actions of IL-6 can be explained by its dichotomous signaling pathways. Classical signaling involves IL-6 binding to a cell-surface receptor (mbIL-6R; present on only a small number of cell types) and is the predominant signaling mechanism during exercise. Trans-signaling involves IL-6 binding to a soluble version of its receptor (sIL-6R), with the resulting complex having a much greater half-life and the ability to signal in all cell types. Trans-signaling drives the inflammatory actions of IL-6 and is the predominant pathway in disease. A single nucleotide polymorphism (rs2228145) on the IL-6R gene can modify the classical/trans-signaling balance through increasing the levels of sIL-6R. This SNP has clinical significance, having been linked to inflammatory conditions such as rheumatoid arthritis and type 1 diabetes, as well as to the severity of symptoms experienced with COVID-19. This review will describe how acute exercise, chronic training and the rs2228145 SNP can modify the IL-6 signaling pathway and the consequent implications for health and athletic performance.

The Effects of 8-Week Combined Exercise Training on Inflammatory Markers in Women with Multiple Sclerosis

PURPOSE

The present study was designed to investigate the effects of 8-week combined endurance, resistance, and balance exercise training on IL-6, CRP, and IL-10 concentrations in women with multiple sclerosis.

METHODS

Thirty participants with multiple sclerosis (Expanded Disability Status Scale ≤6) were randomized into either an exercise and control groups. The exercise group performed 8-weeks of endurance, resistance, and balance exercise training. Serum concentrations of IL-6, CRP, and IL-10 were measured before and after the 8-week intervention. Moreover, anthropometric measures were determined at the onset of and after the intervention. For within- and between groups comparisons of all variables, t test (independent and dependent) was used (p < 0.05).

RESULTS

The results revealed that IL-6 and CRP levels significantly decreased after exercise training (from 6.8 ± 1.52 to 3.2 ± 0.96, p < 0.001 and from 2.76 ± 0.98 to 1.55 ± 0.44, p = <0.001; respectively). Also, exercise training significantly increased IL-10 in the exercise group (from 16.4 ± 2.74 to 23.2 ± 2.11, p < 0.001). There was a significant difference between the 2 groups in all markers in the after 8-week exercise (p < 0.05).

CONCLUSIONS

One of the characteristics of MS disease is inflammation. Exercise training through physiological mechanisms and without aggravating the inflammatory pathology can be effective in functional and symptom reduction of patients with MS. In confirmation of this, the present study showed that 8 weeks of combined exercise training decreased pro-inflammatory markers (IL-6 and CRP) and increased anti-inflammatory cytokine (IL-10). Our findings suggested that an exercise training program can be an effective strategy for managing the immune system of women with MS at least by its significant effect on inflammatory markers.

Single Bout Exercise in Children with Juvenile Idiopathic Arthritis: Impact on Inflammatory Markers

Objective

In a context of inflammatory disease such as juvenile idiopathic arthritis (JIA), we do not know what impact physical activity may have on a deregulated immune system. The objective is to measure the impact of a single bout of exercise on plasma inflammatory markers such as calprotectin, IL-6, sIL-6R, sgp130, and the hypothalamic-pituitary-adrenal axis in children with juvenile idiopathic arthritis.

Methods

Twelve children with JIA performed a nonexercise control day and a consecutive day that included a 20 min exercise bout at 70% of max-HR at 08:30 am. Venous blood samples were taken at 08:30, 08:50, 09:30, 10:30 am, and 12:00 pm to measure plasma concentrations of calprotectin, IL-6, sIL-6R, sgp130, cortisol, and ACTH. Pain was evaluated at 08:30, 08:50 am, and 06:00 pm.

Results

There was a transient twofold increase in postexercise self-evaluated pain (p = 0.03) that disappeared in the evening. A single bout of exercise resulted in a 1.7-fold increase in plasma calprotectin (p < 0.001) but not IL-6 and its soluble receptors. Calprotectin levels returned to baseline within 3 hours after cessation of exercise.

Conclusion

Acute exercise in children with JIA induced slightly musculoskeletal leg pain and transient increased plasma calprotectin levels but not IL-6 levels. Trial registration in ClinicalTrials.gov, reference number NCT 02502539, registered on 29 May 2015.

Effects of age and sex on epigenetic modification induced by an acute physical exercise

It has been observed that, after 2 hours of aerobic exercise, plasma interleukin-6 (IL-6) increases whereas nuclear concentrations of enzyme DNA methyltransferase (DNMT) 3B significantly decreased in peripheral blood mononuclear cells (PBMCs), with no change observed in DNMT3A. The aim of the present study was to detect differences in these changes induced by exercise in plasma IL-6 levels as well as in PBMC nuclear concentrations of DNMT3A and DNMT3B, in relation to age and sex. Four groups were studied: 12 young men (24.8 ± 1.77 years old), 12 young women (23.8 ± 1.81 years old), 12 adult men (45.8 ± 1.82 years old), 12 adult women (mean 44.5 ± 2.07 years old). Participants had to run at 60% of maximal oxygen consumption (VO2max) for 120 minutes, interspersed with sprints at 90% of VO2max for the last 30 seconds of every 10 minutes. About 250 μL of PBMCs (1 × 10 cells) were treated with 100 μL of either pre-exercise plasma or post-exercise plasma and nuclear DNMT3A and DNMT3B concentrations were quantified. No change in nuclear concentration of DNMT3A following the exercise was observed. Conversely, nuclear concentrations of DNMT3B significantly decreased, with a reduction of about 78% in young men, 72% in young women, 61% in adult men, and 53% in adult women. Moreover, a strong positive correlation between the nuclear concentration of DNMT3B in PBMC following stimulation with post-exercise plasma and post-exercise plasma concentrations of IL-6 was observed in all the 4 studied groups. This study confirms that a single bout of endurance exercise is sufficient to decrease nuclear concentrations of DNMT3B and thus protein upregulation. Moreover, the epigenetic mechanisms induced by exercise apparently cause more intense changes in men than in women and that, in both of them, this effect seems to decrease with age.

Performance and Endocrine Responses to Differing Ratios of Concurrent Strength and Endurance Training

The present study examined functional strength and endocrine responses to varying ratios of strength and endurance training in a concurrent training regimen. Thirty resistance trained men completed 6 weeks of 3 d·wk of (a) strength training (ST), (b) concurrent strength and endurance training ratio 3:1 (CT3), (c) concurrent strength and endurance training ratio 1:1 (CT1), or (d) no training (CON). Strength training was conducted using whole-body multijoint exercises, whereas endurance training consisted of treadmill running. Assessments of maximal strength, lower-body power, and endocrine factors were conducted pretraining and after 3 and 6 weeks. After the intervention, ST and CT3 elicited similar increases in lower-body strength; furthermore, ST resulted in greater increases than CT1 and CON (all p ≤ 0.05). All training conditions resulted in similar increases in upper-body strength after training. The ST group observed greater increases in lower-body power than all other conditions (all p ≤ 0.05). After the final training session, CT1 elicited greater increases in cortisol than ST (p = 0.008). When implemented as part of a concurrent training regimen, higher volumes of endurance training result in the inhibition of lower-body strength, whereas low volumes do not. Lower-body power was attenuated by high and low frequencies of endurance training. Higher frequencies of endurance training resulted in increased cortisol responses to training. These data suggest that if strength development is the primary focus of a training intervention, frequency of endurance training should remain low.

Exercise-conditioned plasma attenuates nuclear concentrations of DNA methyltransferase 3B in human peripheral blood mononuclear cells

DNA methylation is modifiable by acute and chronic exercise. DNA methyltransferases (DNMT) catalyze this process; however, there is a lack of literature concerning the specific mechanisms by which exercise‐induced modifications occur. Interleukin 6 (IL‐6) stimulation of various cell lines has been shown to augment DNMT expression and nuclear translocation, which suggests a possible pathway by which exercise is able to elicit changes in epigenetic enzymes. The present study sought to elucidate the response of the de novo methyltransferases DNMT3A and DNMT3B to circulatory factors found in plasma isolated from whole blood before and after 120‐min of treadmill running at an intensity of 60% of individual velocity at V˙O2max (vV˙O2max) interspersed with 30‐sec sprints at 90% of vV˙O2max every 10‐min. Peripheral blood mononuclear cells (PBMCs) isolated from a resting participant were incubated with plasma isolated from exercising participants (n = 10) or recombinant IL‐6 (rIL‐6), followed by nuclear protein extraction and quantification of DNMT3A and DNMT3B concentrations. Nuclear concentrations of DNMT3B significantly decreased following the experimental protocol (P = 0.03), with no change observed in DNMT3A (P = 0.514).Various concentrations of rIL‐6 caused an elevation in both DNMT3A and DNMT3B nuclear concentration compared with the blank control. The conflicting results between exercising and rIL‐6 conditions suggests that IL‐6 does regulate DNMT nuclear transport, however, other plasma mediators may also exert significant influence on the nuclear concentrations of these enzymes.

Inflammatory cytokines and physical activity in multiple sclerosis

Background. Besides the functional benefits, physical activity triggers a hormonal pattern of immunologic responses with an anti-inflammatory effect in individuals who suffer from multiple sclerosis. Purpose. To analyze the influence of physical activity on multiple sclerosis and identify the intensity threshold which triggers the anti-inflammatory physiological mechanism. Methodology. A systematic review was made on the databases Medline, PubMed, ScienceDirect, PloS, PEDro, and Web of Science. Studies from references of retrieved articles were also collected. The criteria included studies published in English and random studies referred to the inflammatory process, connected with physical activity in individuals with multiple sclerosis. The studies were methodologically analyzed by two reviewers according to PEDro scale. Results and Discussion. Five random control trial studies were identified. The results revealed that with physical activity there seems to have a modulation on anti-inflammatory cytokines which improve physical and cardiorespiratory performance. More investigation is required. Conclusions. Physical activity influences the quality of life and it seems to stimulate the presence of anti-inflammatory cytokines. With light physical activity the cellular activity is lower, while with moderate activity there seems to have more capacity to help in the resolution of an inflammatory situation.