Specific correlations between muscle oxidative stress and chronic fatigue syndrome: a working hypothesis

Transcranial Magnetic Stimulation Improves Muscle Involvement in Experimental Autoimmune Encephalomyelitis

Skeletal muscle is affected in experimental autoimmune encephalomyelitis (EAE), which is a model of multiple sclerosis that produces changes including muscle atrophy; histological features of neurogenic involvement, and increased oxidative stress. In this study, we aimed to evaluate the therapeutic effects of transcranial magnetic stimulation (TMS) on the involvement of rat skeletal muscle and to compare them with those produced by natalizumab (NTZ). EAE was induced by injecting myelin oligodendrocyte glycoprotein (MOG) into Dark Agouti rats. Both treatments, NTZ and TMS, were implemented from day 15 to day 35. Clinical severity was studied, and after sacrifice, the soleus and extensor digitorum longus muscles were extracted for subsequent histological and biochemical analysis. The treatment with TMS and NTZ had a beneficial effect on muscle involvement in the EAE model. There was a clinical improvement in functional motor deficits, atrophy was attenuated, neurogenic muscle lesions were reduced, and the level of oxidative stress biomarkers was lower in both treatment groups. Compared to NTZ, the best response was obtained with TMS for all the parameters analyzed. The myoprotective effect of TMS was higher than that of NTZ. Thus, the use of TMS may be an effective strategy to reduce muscle involvement in multiple sclerosis.

Comparing Idiopathic Chronic Fatigue and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in Males: Response to Two-Day Cardiopulmonary Exercise Testing Protocol

(1) Introduction: Multiple studies have shown that peak oxygen consumption is reduced in the majority of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS )patients, using the gold standard for measuring exercise intolerance: cardiopulmonary exercise testing (CPET). A 2-day CPET protocol has shown different results on day 2 in ME/CFS patients compared to sedentary controls. No comparison is known between ME/CFS and idiopathic chronic fatigue (ICF) for 2-day CPET protocols. We compared ME/CFS patients with patients with chronic fatigue who did not fulfill the ME/CFS criteria in a male population and hypothesized a different pattern of response would be present during the 2nd day CPET. (2) Methods: We compared 25 male patients with ICF who had completed a 2-day CPET protocol to an age-/gender-matched group of 26 male ME/CFS patients. Measures of oxygen consumption (VO₂), heart rate (HR), systolic and diastolic blood pressure, workload (Work), and respiratory exchange ratio (RER) were collected at maximal (peak) and ventilatory threshold (VT) intensities. (3) Results: Baseline characteristics for both groups were similar for age, body mass index (BMI), body surface area, (BSA), and disease duration. A significant difference was present in the number of patients with fibromyalgia (seven ME/CFS patients vs. zero ICF patients). Heart rate at rest and the RER did not differ significantly between CPET 1 and CPET 2. All other CPET parameters at the ventilatory threshold and maximum exercise differed significantly (p-value between 0.002 and <0.0001). ME/CFS patients showed a deterioration of performance on CPET2 as reflected by VO₂ and workload at peak exercise and ventilatory threshold, whereas ICF patients showed improved performance on CPET2 with no significant change in peak workload. (4) Conclusion: This study confirms that male ME/CFS patients have a reduction in exercise capacity in response to a second-day CPET. These results are similar to published results in male ME/CFS populations. Patients diagnosed with ICF show a different response on day 2, more similar to sedentary and healthy controls.

Female Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Idiopathic Chronic Fatigue: Comparison of Responses to a Two-Day Cardiopulmonary Exercise Testing Protocol

Introduction: Multiple studies have shown that peak oxygen consumption is reduced in the majority of ME/CFS patients, using the golden standard for measuring exercise intolerance: cardiopulmonary exercise testing (CPET). A 2-day CPET protocol has shown different results on day 2 in ME/CFS patients compared to sedentary controls. No comparison is known between ME/CFS and idiopathic chronic fatigue (ICF) for 2-day CPET protocols. We compared ME/CFS patients with patients with chronic fatigue who did not fulfil the ME/CFS criteria in a male population and hypothesized a different pattern of response would be present during the 2nd day CPET. Methods: Fifty-one female patients with ICF completed a 2-day CPET protocol and were compared to an age/sex-matched group of 50 female ME/CFS patients. Measures of oxygen consumption (VO₂), heart rate (HR), systolic and diastolic blood pressure, workload (Work), and respiratory exchange ratio (RER) were collected at maximal (peak) and ventilatory threshold (VT) intensities. Results: Baseline characteristics for both groups were similar for age, BMI, BSA, and disease duration. A significance difference was present in the number of patients with fibromyalgia (seven ME/CFS patients vs zero ICF patients). Heart rate at rest and the RER did not differ significantly between CPET 1 and CPET 2. All other CPET parameters at the ventilatory threshold and maximum exercise differed significantly (p-value between 0.002 and <0.0001). ME/CFS patients showed a deterioration of performance on CPET2 as reflected by VO₂ and workload at peak exercise and ventilatory threshold, whereas ICF patients showed improved performance on CPET2 with no significant change in peak workload. Conclusion: This study confirms that female ME/CFS patients have a reduction in exercise capacity in response to a second day CPET. These results are similar to published results in female ME/CFS populations. Patients diagnosed with ICF show a different response on day 2, more similar to sedentary and healthy controls.

Validation of the Severity of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome by Other Measures than History: Activity Bracelet, Cardiopulmonary Exercise Testing and a Validated Activity Questionnaire: SF-36

Introduction: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severe and disabling chronic disease. Grading patient’s symptom and disease severity for comparison and therapeutic decision-making is necessary. Clinical grading that depends on patient self-report is subject to inter-individual variability. Having more objective measures to grade and confirm clinical grading would be desirable. Therefore, the aim of this study was to validate the clinical severity grading that has been proposed by the authors of the ME International Consensus Criteria (ICC) using more standardized measures like questionnaires, and objective measures such as physical activity tracking and cardiopulmonary exercise testing. Methods and results: The clinical database of a subspecialty ME/CFS clinic was searched for patients who had completed the SF 36 questionnaire, worn a Sensewear^TM armband for five days, and undergone a cardiopulmonary exercise test. Only patients who completed all three investigations within 3 months from each other—to improve the likelihood of stable disease—were included in the analysis. Two-hundred-eighty-nine patients were analyzed: 121 were graded as mild, 98 as moderate and 70 as having severe disease. The mean (SD) physical activity subscale of the SF-36 was 70 (11) for mild, 43 (8) for moderate and 15 (10) for severe ME/CFS patients. The mean (SD) number of steps per day was 8235 (1004) for mild, 5195 (1231) for moderate and 2031 (824) for severe disease. The mean (SD) percent predicted oxygen consumption at the ventilatory threshold was 47 (11)% for mild, 38 (7)% for moderate and 30 (7)% for severe disease. The percent peak oxygen consumption was 90 (14)% for mild, 64 (8)% for moderate and 48 (9)% for severe disease. All comparisons were p < 0.0001. Conclusion: This study confirms the validity of the ICC severity grading. Grading assigned by clinicians on the basis of patient self-report created groups that differed significantly on measures of activity using the SF-36 physical function subscale and objective measures of steps per day and exercise capacity. There was variability in function within severity grading groups, so grading based on self-report can be strengthened by the use of these supplementary measures.

Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome: correlations between peak oxygen consumption, the physical functioning scale of the SF-36 questionnaire, and the number of steps from an activity meter

Background

Most studies to assess effort intolerance in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) have used questionnaires. Few studies have compared questionnaires with objective measures like an actometer or an exercise test. This study compared three measures of physical activity in ME/CFS patients: the physical functioning scale (PFS) of the SF-36, the number of steps/day (Steps) using an actometer, and the %peak VO₂ of a cardiopulmonary stress test.

Methods

Female ME/CFS patients were selected from a clinical database if the three types of measurements were available, and the interval between measurements was ≤ 3 months. Data from the three measures were compared by linear regression.

Results

In 99 female patients the three different measures were linearly, significantly, and positively correlated (PFS vs Steps, PFS vs %peak VO₂ and Steps vs %peak VO₂: all P < 0.001). Subgroup analysis showed that the relations between the three measures were not different in patients with versus without fibromyalgia and with versus without a maximal exercise effort (RER ≥ 1.1). In 20 patients re-evaluated for symptom worsening, the mean of all three measures was significantly lower (P < 0.0001), strengthening the observation of the relations between them. Despite the close correlation, we observed a large variation between the three measures in individual patients.

Conclusions

Given the large variation in ME/CFS patients, the use of only one type of measurement is inadequate. Integrating the three modalities may be useful for patient care by detecting overt discrepancies in activity and may inform studies that compare methods of improving exercise capacity.

Circulating levels of GDF15 in patients with myalgic encephalomyelitis/chronic fatigue syndrome

Background

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating condition characterised by fatigue and post-exertional malaise. Its pathogenesis is poorly understood. GDF15 is a circulating protein secreted by cells in response to a variety of stressors. The receptor for GDF15 is expressed in the brain, where its activation results in a range of responses. Among the conditions in which circulating GDF15 levels are highly elevated are mitochondrial disorders, where early skeletal muscle fatigue is a key symptom. We hypothesised that GDF15 may represent a marker of cellular stress in ME/CFS.

Methods

GDF15 was measured in serum from patients with ME/CFS (n = 150; 100 with mild/moderate and 50 with severe symptoms), “healthy volunteers” (n = 150) and a cohort of patients with multiple sclerosis (n = 50).

Results

Circulating GDF15 remained stable in a subset of ME/CFS patients when sampled on two occasions ~ 7 months (IQR 6.7–8.8) apart, 720 pg/ml (95% CI 625–816) vs 670 pg/ml (95% CI 598–796), P = 0.5. GDF15 levels were 491 pg/ml in controls (95% CI 429–553), 546 pg/ml (95% CI 478–614) in MS patients, 560 pg/ml (95% CI 502–617) in mild/moderate ME/CFS patients and 602 pg/ml (95% CI 531–674) in severely affected ME/CFS patients. Accounting for potential confounders, severely affected ME/CFS patients had GDF15 concentrations that were significantly increased compared to healthy controls (P = 0.01). GDF15 levels were positively correlated (P = 0.026) with fatigue scores in ME/CFS.

Conclusions

Severe ME/CFS is associated with increased levels of GDF15, a circulating biomarker of cellular stress that appears which stable over several months.

Myalgic encephalomyelitis/chronic fatigue syndrome: From pathophysiological insights to novel therapeutic opportunities

Myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) is a common and disabling condition with a paucity of effective and evidence-based therapies, reflecting a major unmet need. Cognitive behavioural therapy and graded exercise are of modest benefit for only some ME/CFS patients, and many sufferers report aggravation of symptoms of fatigue with exercise. The presence of a multiplicity of pathophysiological abnormalities in at least the subgroup of people with ME/CFS diagnosed with the current international consensus "Fukuda" criteria, points to numerous potential therapeutic targets. Such abnormalities include extensive data showing that at least a subgroup has a pro-inflammatory state, increased oxidative and nitrosative stress, disruption of gut mucosal barriers and mitochondrial dysfunction together with dysregulated bioenergetics. In this paper, these pathways are summarised, and data regarding promising therapeutic options that target these pathways are highlighted; they include coenzyme Q₁₀, melatonin, curcumin, molecular hydrogen and N-acetylcysteine. These data are promising yet preliminary, suggesting hopeful avenues to address this major unmet burden of illness.

Myalgic encephalomyelitis or chronic fatigue syndrome: how could the illness develop?

A model of the development and progression of chronic fatigue syndrome (myalgic encephalomyelitis), the aetiology of which is currently unknown, is put forward, starting with a consideration of the post-infection role of damage-associated molecular patterns and the development of chronic inflammatory, oxidative and nitrosative stress in genetically predisposed individuals. The consequences are detailed, including the role of increased intestinal permeability and the translocation of commensal antigens into the circulation, and the development of dysautonomia, neuroinflammation, and neurocognitive and neuroimaging abnormalities. Increasing levels of such stress and the switch to immune and metabolic downregulation are detailed next in relation to the advent of hypernitrosylation, impaired mitochondrial performance, immune suppression, cellular hibernation, endotoxin tolerance and sirtuin 1 activation. The role of chronic stress and the development of endotoxin tolerance via indoleamine 2,3-dioxygenase upregulation and the characteristics of neutrophils, monocytes, macrophages and T cells, including regulatory T cells, in endotoxin tolerance are detailed next. Finally, it is shown how the immune and metabolic abnormalities of chronic fatigue syndrome can be explained by endotoxin tolerance, thus completing the model.

Metabolic abnormalities in chronic fatigue syndrome/myalgic encephalomyelitis: a mini-review

Chronic fatigue syndrome (CFS), commonly known as myalgic encephalomyelitis (ME), is a debilitating disease of unknown etiology. CFS/ME is a heterogeneous disease associated with a myriad of symptoms but with severe, prolonged fatigue as the core symptom associated with the disease. There are currently no known biomarkers for the disease, largely due to the lack of knowledge surrounding the eitopathogenesis of CFS/ME. Numerous studies have been conducted in an attempt to identify potential biomarkers for the disease. This mini-review offers a brief summary of current research into the identification of metabolic abnormalities in CFS/ME which may represent potential biomarkers for the disease. The progress of research into key areas including immune dysregulation, mitochondrial dysfunction, 5'-adenosine monophosphate-activated protein kinase activation, skeletal muscle cell acidosis, and metabolomics are presented here. Studies outlined in this mini-review show many potential causes for the pathogenesis of CFS/ME and identify many potential metabolic biomarkers for the disease from the aforementioned research areas. The future of CFS/ME research should focus on building on the potential biomarkers for the disease using multi-disciplinary techniques at multiple research sites in order to produce robust data sets. Whether the metabolic changes identified in this mini-review occur as a cause or a consequence of the disease must also be established.

Mechanisms Explaining Muscle Fatigue and Muscle Pain in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): a Review of Recent Findings

PURPOSE OF REVIEW

Here, we review potential causes of muscle dysfunction seen in many patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) such as the effects of oxidative and nitrosative stress (O&NS) and mitochondrial impairments together with reduced heat shock protein production and a range of metabolic abnormalities.

RECENT FINDINGS

Several studies published in the last few years have highlighted the existence of chronic O&NS, inflammation, impaired mitochondrial function and reduced heat shock protein production in many patients with ME/CFS. These studies have also highlighted the detrimental effects of chronically elevated O&NS on muscle functions such as reducing the time to muscle fatigue during exercise and impairing muscle contractility. Mechanisms have also been revealed by which chronic O&NS and or impaired heat shock production may impair muscle repair following exercise and indeed the adaptive responses in the striated muscle to acute and chronic increases in physical activity. The presence of chronic O&NS, low-grade inflammation and impaired heat shock protein production may well explain the objective findings of increased muscle fatigue, impaired contractility and multiple dimensions of exercise intolerance in many patients with ME/CFS.

Neuromuscular electrical stimulation improves skeletal muscle regeneration through satellite cell fusion with myofibers in healthy elderly subjects

The aim of this study was to determine whether neuromuscular electrical stimulation (NMES) affects skeletal muscle regeneration through a reduction of oxidative status in satellite cells of healthy elderly subjects. Satellite cells from the vastus lateralis skeletal muscle of 12 healthy elderly subjects before and after 8 wk of NMES were allowed to proliferate to provide myogenic populations of adult stem cells [myogenic precursor cells (MPCs)]. These MPCs were then investigated in terms of their proliferation, their basal cytoplasmic free Ca2+concentrations, and their expression of myogenic regulatory factors ( PAX3, PAX7, MYF5, MYOD, and MYOG) and micro-RNAs (miR-1, miR-133a/b, and miR-206). The oxidative status of these MPCs was evaluated through superoxide anion production and superoxide dismutase and glutathione peroxidase activities. On dissected single skeletal myofibers, the nuclei were counted to determine the myonuclear density, the fiber phenotype, cross-sectional area, and tension developed. The MPCs obtained after NMES showed increased proliferation rates along with increased cytoplasmic free Ca2+concentrations and gene expression of MYOD and MYOG on MPCs. Muscle-specific miR-1, miR-133a/b, and miR-206 were upregulated. This NMES significantly reduced superoxide anion production, along with a trend to reduction of superoxide dismutase activity. The NMES-dependent stimulation of muscle regeneration enhanced satellite cell fusion with mature skeletal fibers. NMES improved the regenerative capacity of skeletal muscle in elderly subjects. Accordingly, the skeletal muscle strength and mobility of NMES-stimulated elderly subjects significantly improved. NMES may thus be further considered for clinical or ageing populations.

NEW & NOTEWORTHY The neuromuscular electrical stimulation (NMES) effect on skeletal muscle regeneration was assessed in healthy elderly subjects for the first time. NMES improved the regenerative capacity of skeletal muscle through increased myogenic precursor cell proliferation and fusion with mature myofibers. The increased cytoplasmic free Ca2+concentration along with MYOD, MYOG, and micro-RNA upregulation could be related to reduced O2·−production, which, in turn, favors myogenic regeneration. Accordingly, the skeletal muscle strength of NMES-stimulated lower limbs of healthy elderly subjects improved along with their mobility.

Anti-fatigue effect by active dipeptides of fermented porcine placenta through inhibiting the inflammatory and oxidative reactions

BACKGROUND

Recently, we reported an anti-fatigue effect of fermented porcine placenta (FPP). Glycine-leucine (GL) and leucine-glycine (LG) dipeptides are main peptides of FPP. However, the therapeutic effects and underlying mechanisms of GL and LG dipeptides on fatigue are still unclear.

METHODS

Herein, we examined the anti-fatigue properties of GL and LG dipeptides using RAW264.7 macrophages and forced swimming test (FST) animal model.

RESULTS

Our data revealed that lipopolysaccharide (LPS)-induced interleukin (IL)-1β, tumor necrosis factor-α, and IL-6 productions were markedly inhibited by GL or LG in RAW264.7 macrophages without inducing cytotoxicity. LPS-enhanced nitric oxide (NO) production and inducible nitric oxide synthase expression were inhibited by GL or LG, whereas superoxide dismutase (SOD) activities were significantly enhanced by GL or LG in LPS-stimulated RAW264.7 macrophages. The present study also figured out that these effects of GL and LG were mediated by blockade of caspase-1 and nuclear factor-κB activation. In FST-induced fatigue mouse model, the mice which received the GL or LG for 21days showed significant decreases of IL-1β, IL-6, and NO serum levels. Treatment with GL or LG significantly enhanced levels of SOD and glycogen and significantly lowered levels of lactate dehydrogenase, aspartate transaminase, and alanine transaminase.

CONCLUSION

Taken together, our results indicated that GL and LG dipeptides, active components of FPP, should be considered as candidate of anti-fatigue agents.

Association of biomarkers with health-related quality of life and history of stressors in myalgic encephalomyelitis/chronic fatigue syndrome patients

Background

Myalgic encephalomyelitis chronic fatigue syndrome (ME/CFS) is a common debilitating disorder associated with an intense fatigue, a reduced physical activity, and an impaired quality of life. There are no established biological markerof the syndrome. The etiology is unknown and its pathogenesis appears to be multifactorial. Various stressors, including intense physical activity, severe infection, and emotional stress are reported in the medical history of ME/CFS patients which raises the question whether any physiological and biological abnormalities usually found in these patients could be indicative of the etiology and/or the quality-of-life impairment.

Methods

Thirty-six patients and 11 age-matched healthy controls were recruited. The following variables that appear to address common symptoms of ME/CFS were studied here: (1) muscle fatigue during exercise has been investigated by monitoring the compound muscle action potential (M-wave); (2) the excessive oxidative stress response to exercise was measured via two plasma markers (thiobarbituric acid reactive substances: TBARS; reduced ascorbic-acid: RAA); (3) a potential inflammatory component was addressed via expression of CD26 on peripheral blood mononuclear cells; (4) quality-of-life impairment was assessed using the London Handicap Scale (LHS) and the Medical Outcome Study Short Form-36 (SF-36). The medical history of each patient, including the presence of stressors such as intense sports practice, severe acute infection and/or severe emotional stress was documented.

Results

We observed that: (1) there were striking differences between cases and controls with regard to three biological variables: post-exercise M-wave, TBARS variations and CD26-expression at rest; (2) each of these three variables correlated with the other two; (3) abnormalities in the biomarkers associated with health-related quality of life: the LHS score was negatively correlated with the exercise-induced TBARS increase and positively correlated with CD26-expression while the pain component of SF-36 was negatively correlated with CD26-expression; (4) the TBARS increase and the M-wave decrease were the highest, and the CD26-expression level the lowest in patients who had been submitted to infectious stressors.

Conclusion

In ME/CFS patients, severe alterations of the muscle excitability, the redox status, as well as the CD26-expression level are correlated with a marked impairment of the quality-of-life. They are particularly significant when infectious stressors are reported in the medical history.

Nitrosative Stress, Hypernitrosylation, and Autoimmune Responses to Nitrosylated Proteins: New Pathways in Neuroprogressive Disorders Including Depression and Chronic Fatigue Syndrome

Nitric oxide plays an indispensable role in modulating cellular signaling and redox pathways. This role is mainly effected by the readily reversible nitrosylation of selective protein cysteine thiols. The reversibility and sophistication of this signaling system is enabled and regulated by a number of enzymes which form part of the thioredoxin, glutathione, and pyridoxine antioxidant systems. Increases in nitric oxide levels initially lead to a defensive increase in the number of nitrosylated proteins in an effort to preserve their function. However, in an environment of chronic oxidative and nitrosative stress (O&NS), nitrosylation of crucial cysteine groups within key enzymes of the thioredoxin, glutathione, and pyridoxine systems leads to their inactivation thereby disabling denitrosylation and transnitrosylation and subsequently a state described as "hypernitrosylation." This state leads to the development of pathology in multiple domains such as the inhibition of enzymes of the electron transport chain, decreased mitochondrial function, and altered conformation of proteins and amino acids leading to loss of immune tolerance and development of autoimmunity. Hypernitrosylation also leads to altered function or inactivation of proteins involved in the regulation of apoptosis, autophagy, proteomic degradation, transcription factor activity, immune-inflammatory pathways, energy production, and neural function and survival. Hypernitrosylation, as a consequence of chronically elevated O&NS and activated immune-inflammatory pathways, can explain many characteristic abnormalities observed in neuroprogressive disease including major depression and chronic fatigue syndrome/myalgic encephalomyelitis. In those disorders, increased bacterial translocation may drive hypernitrosylation and autoimmune responses against nitrosylated proteins.

Understanding Muscle Dysfunction in Chronic Fatigue Syndrome

Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.

Low Intensity Exercise Training Improves Skeletal Muscle Regeneration Potential

Purpose: The aim of this study was to determine whether 12 days of low-to-moderate exercise training at low altitude (598 m a.s.l.) improves skeletal muscle regeneration in sedentary adult women.

Methods: Satellite cells were obtained from the vastus lateralis skeletal muscle of seven women before and after this exercise training at low altitude. They were investigated for differentiation aspects, superoxide anion production, antioxidant enzymes, mitochondrial potential variation after a depolarizing insult, intracellular Ca²⁺ concentrations, and micro (mi)RNA expression (miR-1, miR-133, miR-206).

Results: In these myogenic populations of adult stem cells, those obtained after exercise training, showed increased Fusion Index and intracellular Ca²⁺ concentrations. This exercise training also generally reduced superoxide anion production in cells (by 12–67%), although not in two women, where there was an increase of ~15% along with a reduced superoxide dismutase activity. miRNA expression showed an exercise-induced epigenetic transcription profile that was specific according to the reduced or increased superoxide anion production of the cells.

Conclusions: The present study shows that low-to-moderate exercise training at low altitude improves the regenerative capacity of skeletal muscle in adult women. The differentiation of cells was favored by increased intracellular calcium concentration and increased the fusion index. This low-to-moderate training at low altitude also depicted the epigenetic signature of cells.

The many roads to mitochondrial dysfunction in neuroimmune and neuropsychiatric disorders

BACKGROUND

Mitochondrial dysfunction and defects in oxidative metabolism are a characteristic feature of many chronic illnesses not currently classified as mitochondrial diseases. Examples of such illnesses include bipolar disorder, multiple sclerosis, Parkinson's disease, schizophrenia, depression, autism, and chronic fatigue syndrome.

DISCUSSION

While the majority of patients with multiple sclerosis appear to have widespread mitochondrial dysfunction and impaired ATP production, the findings in patients diagnosed with Parkinson's disease, autism, depression, bipolar disorder schizophrenia and chronic fatigue syndrome are less consistent, likely reflecting the fact that these diagnoses do not represent a disease with a unitary pathogenesis and pathophysiology. However, investigations have revealed the presence of chronic oxidative stress to be an almost invariant finding in study cohorts of patients afforded each diagnosis. This state is characterized by elevated reactive oxygen and nitrogen species and/or reduced levels of glutathione, and goes hand in hand with chronic systemic inflammation with elevated levels of pro-inflammatory cytokines.

SUMMARY

This paper details mechanisms by which elevated levels of reactive oxygen and nitrogen species together with elevated pro-inflammatory cytokines could conspire to pave a major road to the development of mitochondrial dysfunction and impaired oxidative metabolism seen in many patients diagnosed with these disorders.

Central pathways causing fatigue in neuro-inflammatory and autoimmune illnesses

BACKGROUND

The genesis of severe fatigue and disability in people following acute pathogen invasion involves the activation of Toll-like receptors followed by the upregulation of proinflammatory cytokines and the activation of microglia and astrocytes. Many patients suffering from neuroinflammatory and autoimmune diseases, such as multiple sclerosis, Parkinson's disease and systemic lupus erythematosus, also commonly suffer from severe disabling fatigue. Such patients also present with chronic peripheral immune activation and systemic inflammation in the guise of elevated proinflammtory cytokines, oxidative stress and activated Toll-like receptors. This is also true of many patients presenting with severe, apparently idiopathic, fatigue accompanied by profound levels of physical and cognitive disability often afforded the non-specific diagnosis of chronic fatigue syndrome.

DISCUSSION

Multiple lines of evidence demonstrate a positive association between the degree of peripheral immune activation, inflammation and oxidative stress, gray matter atrophy, glucose hypometabolism and cerebral hypoperfusion in illness, such as multiple sclerosis, Parkinson's disease and chronic fatigue syndrome. Most, if not all, of these abnormalities can be explained by a reduction in the numbers and function of astrocytes secondary to peripheral immune activation and inflammation. This is also true of the widespread mitochondrial dysfunction seen in otherwise normal tissue in neuroinflammatory, neurodegenerative and autoimmune diseases and in many patients with disabling, apparently idiopathic, fatigue. Given the strong association between peripheral immune activation and neuroinflammation with the genesis of fatigue the latter group of patients should be examined using FLAIR magnetic resonance imaging (MRI) and tested for the presence of peripheral immune activation.

SUMMARY

It is concluded that peripheral inflammation and immune activation, together with the subsequent activation of glial cells and mitochondrial damage, likely account for the severe levels of intractable fatigue and disability seen in many patients with neuroimmune and autoimmune diseases.This would also appear to be the case for many patients afforded a diagnosis of Chronic Fatigue Syndrome.

Oxidative and Nitrosative Stress and Immune-Inflammatory Pathways in Patients with Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Myalgic Encephalomyelitis (ME) / Chronic Fatigue Syndrome (CFS) has been classified as a disease of the central nervous system by the WHO since 1969. Many patients carrying this diagnosis do demonstrate an almost bewildering array of biological abnormalities particularly the presence of oxidative and nitrosative stress (O&NS) and a chronically activated innate immune system. The proposal made herein is that once generated chronically activated O&NS and immune-inflammatory pathways conspire to generate a multitude of self-sustaining and self-amplifying pathological processes which are associated with the onset of ME/CFS. Sources of continuous activation of O&NS and immune-inflammatory pathways in ME/CFS are chronic, intermittent and opportunistic infections, bacterial translocation, autoimmune responses, mitochondrial dysfunctions, activation of the Toll-Like Receptor Radical Cycle, and decreased antioxidant levels. Consequences of chronically activated O&NS and immune-inflammatory pathways in ME/CFS are brain disorders, including neuroinflammation and brain hypometabolism / hypoperfusion, toxic effects of nitric oxide and peroxynitrite, lipid peroxidation and oxidative damage to DNA, secondary autoimmune responses directed against disrupted lipid membrane components and proteins, mitochondrial dysfunctions with a disruption of energy metabolism (e.g. compromised ATP production) and dysfunctional intracellular signaling pathways. The interplay between all of these factors leads to self-amplifying feed forward loops causing a chronic state of activated O&NS, immune-inflammatory and autoimmune pathways which may sustain the disease.

Mitochondrial dysfunctions in myalgic encephalomyelitis/chronic fatigue syndrome explained by activated immuno-inflammatory, oxidative and nitrosative stress pathways

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/cfs) is classified by the World Health Organization as a disorder of the central nervous system. ME/cfs is an neuro-immune disorder accompanied by chronic low-grade inflammation, increased levels of oxidative and nitrosative stress (O&NS), O&NS-mediated damage to fatty acids, DNA and proteins, autoimmune reactions directed against neoantigens and brain disorders. Mitochondrial dysfunctions have been found in ME/cfs, e.g. lowered ATP production, impaired oxidative phosphorylation and mitochondrial damage. This paper reviews the pathways that may explain mitochondrial dysfunctions in ME/cfs. Increased levels of pro-inflammatory cytokines, such as interleukin-1 and tumor necrosis factor-α, and elastase, and increased O&NS may inhibit mitochondrial respiration, decrease the activities of the electron transport chain and mitochondrial membrane potential, increase mitochondrial membrane permeability, interfere with ATP production and cause mitochondrial shutdown. The activated O&NS pathways may additionally lead to damage of mitochondrial DNA and membranes thus decreasing membrane fluidity. Lowered levels of antioxidants, zinc and coenzyme Q10, and ω3 polyunsaturated fatty acids in ME/cfs may further aggravate the activated immuno-inflammatory and O&NS pathways. Therefore, it may be concluded that immuno-inflammatory and O&NS pathways may play a role in the mitochondrial dysfunctions and consequently the bioenergetic abnormalities seen in patients with ME/cfs. Defects in ATP production and the electron transport complex, in turn, are associated with an elevated production of superoxide and hydrogen peroxide in mitochondria creating adaptive and synergistic damage. It is argued that mitochondrial dysfunctions, e.g. lowered ATP production, may play a role in the onset of ME/cfs symptoms, e.g. fatigue and post exertional malaise, and may explain in part the central metabolic abnormalities observed in ME/cfs, e.g. glucose hypometabolism and cerebral hypoperfusion.

Oxidative stress, prooxidants, and antioxidants: the interplay

Oxidative stress is a normal phenomenon in the body. Under normal conditions, the physiologically important intracellular levels of reactive oxygen species (ROS) are maintained at low levels by various enzyme systems participating in the in vivo redox homeostasis. Therefore, oxidative stress can also be viewed as an imbalance between the prooxidants and antioxidants in the body. For the last two decades, oxidative stress has been one of the most burning topics among the biological researchers all over the world. Several reasons can be assigned to justify its importance: knowledge about reactive oxygen and nitrogen species production and metabolism; identification of biomarkers for oxidative damage; evidence relating manifestation of chronic and some acute health problems to oxidative stress; identification of various dietary antioxidants present in plant foods as bioactive molecules; and so on. This review discusses the importance of oxidative stress in the body growth and development as well as proteomic and genomic evidences of its relationship with disease development, incidence of malignancies and autoimmune disorders, increased susceptibility to bacterial, viral, and parasitic diseases, and an interplay with prooxidants and antioxidants for maintaining a sound health, which would be helpful in enhancing the knowledge of any biochemist, pathophysiologist, or medical personnel regarding this important issue.

Stress and law enforcers: testing the relationship between law enforcement work stressors and health-related issues

This study examines the relationship between law enforcement work-related stressors and health issues. Specifically, this study attempts to determine the effects of stress-producing factors (e.g. vigorous activities at work, shift change, perceived danger associated with police work, etc.) on physiological health-related issues (e.g. the number of reported health issues, high blood pressure, back pain, and headaches) and psychosocial behavior problems (e.g. alcohol consumption and cigarette smoking) among police officers. The analyses are based on a total 1632 law enforcement officers, who represent 51 police agencies in the three major cities, New York City, Dallas Texas, and Minneapolis, USA. The research findings that emerged from this study show that the number of days in vigorous activities and perceived physiological demands have the strongest influence on the number of health-related issues. Working without a partner and frequent shift changes had the strongest influence on alcohol consumption by police officers.

A multidisciplinary approach to study a couple of monozygotic twins discordant for the chronic fatigue syndrome: a focus on potential salivary biomarkers

BACKGROUND

Chronic Fatigue Syndrome (CFS) is a severe, systemic illness characterized by persistent, debilitating and medically unexplained fatigue. The etiology and pathophysiology of CFS remains obscure, and diagnosis is formulated through the patient's history and exclusion of other medical causes. Thereby, the availability of biomarkers for CFS could be useful for clinical research. In the present study, we used a proteomic approach to evaluate the global changes in the salivary profile in a couple of monozygotic twins who were discordant for CFS. The aim was to evaluate differences of salivary protein expression in the CFS patient in respect to his healthy twin.

METHODS

Saliva samples were submitted to two-dimensional electrophoresis (2DE). The gels were stained with Sypro, and a comparison between CFS subject and the healthy one was performed by the software Progenesis Same Spot including the Analysis of variance (ANOVA test). The proteins spot found with a ≥2-fold spot quantity change and p<0.05 were identified by Nano-liquid chromatography electrospray ionization tandem mass spectrometry. To validate the expression changes found with 2DE of 5 proteins (14-3-3 protein zeta/delta, cyclophilin A, Cystatin-C, Protein S100-A7, and zinc-alpha-2-glycoprotein), we used the western blot analysis. Moreover, proteins differentially expressed were functionally analyzed using the Ingenuity Pathways Analysis software with the aim to determine the predominant canonical pathways and the interaction network involved.

RESULTS

The analysis of the protein profiles allowed us to find 13 proteins with a different expression in CFS in respect to control. Nine spots were up-regulated in CFS and 4 down-regulated. These proteins belong to different functional classes, such as inflammatory response, immune system and metabolism. In particular, as shown by the pathway analysis, the network built with our proteins highlights the involvement of inflammatory response in CFS pathogenesis.

CONCLUSIONS

This study shows the presence of differentially expressed proteins in the saliva of the couple of monozygotic twins discordant for CFS, probably related to the disease. Consequently, we believe the proteomic approach could be useful both to define a panel of potential diagnostic biomarkers and to shed new light on the comprehension of the pathogenetic pathways of CFS.

Myalgic encephalomyelitis/chronic fatigue syndrome and encephalomyelitis disseminata/multiple sclerosis show remarkable levels of similarity in phenomenology and neuroimmune characteristics

BACKGROUND

'Encephalomyelitis disseminata' (multiple sclerosis) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are both classified as diseases of the central nervous system by the World Health Organization. This review aims to compare the phenomenological and neuroimmune characteristics of MS with those of ME/CFS.

DISCUSSION

There are remarkable phenomenological and neuroimmune overlaps between both disorders. Patients with ME/CFS and MS both experience severe levels of disabling fatigue and a worsening of symptoms following exercise and resort to energy conservation strategies in an attempt to meet the energy demands of day-to-day living. Debilitating autonomic symptoms, diminished cardiac responses to exercise, orthostatic intolerance and postural hypotension are experienced by patients with both illnesses. Both disorders show a relapsing-remitting or progressive course, while infections and psychosocial stress play a large part in worsening of fatigue symptoms. Activated immunoinflammatory, oxidative and nitrosative (O+NS) pathways and autoimmunity occur in both illnesses. The consequences of O+NS damage to self-epitopes is evidenced by the almost bewildering and almost identical array of autoantibodies formed against damaged epitopes seen in both illnesses. Mitochondrial dysfunctions, including lowered levels of ATP, decreased phosphocreatine synthesis and impaired oxidative phosphorylation, are heavily involved in the pathophysiology of both MS and ME/CFS. The findings produced by neuroimaging techniques are quite similar in both illnesses and show decreased cerebral blood flow, atrophy, gray matter reduction, white matter hyperintensities, increased cerebral lactate and choline signaling and lowered acetyl-aspartate levels.

SUMMARY

This review shows that there are neuroimmune similarities between MS and ME/CFS. This further substantiates the view that ME/CFS is a neuroimmune illness and that patients with MS are immunologically primed to develop symptoms of ME/CFS.

Protective effect of HMG CoA reductase inhibitors against running wheel activity induced fatigue, anxiety like behavior, oxidative stress and mitochondrial dysfunction in mice

BACKGROUND

Chronic fatigue stress (CFS) is an important health problem with unknown causes and unsatisfactory prevention strategies, often characterized by long-lasting and debilitating fatigue, myalgia, impairment of neuro-cognitive functions along with other common symptoms. The present study has been designed to explore the protective effect of statins against running wheel activity induced fatigue anxiety.

METHODS

Male albino Laca mice (20-30 g) were subjected to swim stress induced fatigue in a running wheel activity apparatus. Atorvastatin (10, 20 mg/kg, po) and fluvastatin (5, 10 mg/kg, po) were administered daily for 21 days, one hour prior to the animals being subjected to running wheel activity test session of 6 min. Various behavioral tests (running wheel activity, locomotor activity and elevated plus maze test), biochemical parameters (lipid peroxidation, nitrite concentration, glutathione levels and catalase activity) and mitochondrial complex enzyme dysfunctions (complex I, II, III and IV) were subsequently assessed.

RESULTS

Animals exposed to 6 min test session on running wheel for 21 days showed a significant decrease in number of wheel rotations per 6 min indicating fatigue stress like behavior. Treatment with atorvastatin (10 and 20 mg/kg) and fluvastatin (10 mg/kg) for 21 days significantly improved the behavioral alterations [increased number of wheel rotations and locomotor activity, and anxiety like behavior (decreased number of entries and time spent in open arm)], oxidative defence and mitochondrial complex enzyme activities in brain.

CONCLUSION

Present study suggests the protective role of statins against chronic fatigue induced behavioral, biochemical and mitochondrial dysfunctions.

The role of mitochondrial dysfunctions due to oxidative and nitrosative stress in the chronic pain or chronic fatigue syndromes and fibromyalgia patients: peripheral and central mechanisms as therapeutic targets?

INTRODUCTION

Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are characterized by persistent pain and fatigue. It is hypothesized that reactive oxygen species (ROS), caused by oxidative and nitrosative stress, by inhibiting mitochondrial function can be involved in muscle pain and central sensitization as typically seen in these patients.

AREAS COVERED

The current evidence regarding oxidative and nitrosative stress and mitochondrial dysfunction in CFS and FM is presented in relation to chronic widespread pain. Mitochondrial dysfunction has been shown in leukocytes of CFS patients and in muscle cells of FM patients, which could explain the muscle pain. Additionally, if mitochondrial dysfunction is also present in central neural cells, this could result in lowered ATP pools in neural cells, leading to generalized hypersensitivity and chronic widespread pain.

EXPERT OPINION

Increased ROS in CFS and FM, resulting in impaired mitochondrial function and reduced ATP in muscle and neural cells, might lead to chronic widespread pain in these patients. Therefore, targeting increased ROS by antioxidants and targeting the mitochondrial biogenesis could offer a solution for the chronic pain in these patients. The role of exercise therapy in restoring mitochondrial dysfunction remains to be explored, and provides important avenues for future research in this area.

Coenzyme Q10 depletion in medical and neuropsychiatric disorders: potential repercussions and therapeutic implications

Coenzyme Q10 (CoQ10) is an antioxidant, a membrane stabilizer, and a vital cofactor in the mitochondrial electron transport chain, enabling the generation of adenosine triphosphate. It additionally regulates gene expression and apoptosis; is an essential cofactor of uncoupling proteins; and has anti-inflammatory, redox modulatory, and neuroprotective effects. This paper reviews the known physiological role of CoQ10 in cellular metabolism, cell death, differentiation and gene regulation, and examines the potential repercussions of CoQ10 depletion including its role in illnesses such as Parkinson's disease, depression, myalgic encephalomyelitis/chronic fatigue syndrome, and fibromyalgia. CoQ10 depletion may play a role in the pathophysiology of these disorders by modulating cellular processes including hydrogen peroxide formation, gene regulation, cytoprotection, bioenegetic performance, and regulation of cellular metabolism. CoQ10 treatment improves quality of life in patients with Parkinson's disease and may play a role in delaying the progression of that disorder. Administration of CoQ10 has antidepressive effects. CoQ10 treatment significantly reduces fatigue and improves ergonomic performance during exercise and thus may have potential in alleviating the exercise intolerance and exhaustion displayed by people with myalgic encepholamyletis/chronic fatigue syndrome. Administration of CoQ10 improves hyperalgesia and quality of life in patients with fibromyalgia. The evidence base for the effectiveness of treatment with CoQ10 may be explained via its ability to ameliorate oxidative stress and protect mitochondria.

A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior

It is of importance whether myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a variant of sickness behavior. The latter is induced by acute infections/injury being principally mediated through proinflammatory cytokines. Sickness is a beneficial behavioral response that serves to enhance recovery, conserves energy and plays a role in the resolution of inflammation. There are behavioral/symptomatic similarities (for example, fatigue, malaise, hyperalgesia) and dissimilarities (gastrointestinal symptoms, anorexia and weight loss) between sickness and ME/CFS. While sickness is an adaptive response induced by proinflammatory cytokines, ME/CFS is a chronic, disabling disorder, where the pathophysiology is related to activation of immunoinflammatory and oxidative pathways and autoimmune responses. While sickness behavior is a state of energy conservation, which plays a role in combating pathogens, ME/CFS is a chronic disease underpinned by a state of energy depletion. While sickness is an acute response to infection/injury, the trigger factors in ME/CFS are less well defined and encompass acute and chronic infections, as well as inflammatory or autoimmune diseases. It is concluded that sickness behavior and ME/CFS are two different conditions.

Chronic fatigue syndrome: acute infection and history of physical activity affect resting levels and response to exercise of plasma oxidant/antioxidant status and heat shock proteins

OBJECTIVES

A history of high-level physical activity and/or acute infection might constitute stress factors affecting the plasma oxidant-antioxidant status and levels of heat shock proteins (HSPs) in patients with chronic fatigue syndrome (CFS).

DESIGN

This case-control study compared data from 43 CFS patients to results from a matched control group of 23 healthy sedentary subjects.

SETTING AND SUBJECTS

Five patients had no relevant previous history (group I). Eighteen had practised high-level sport (group II), and severe acute infection had been diagnosed in nine patients (group III). A combination of sport practice and infection was noted in 11 patients (group IV).

INTERVENTIONS

After examination at rest, all subjects performed a maximal cycling exercise test. Plasma levels of two markers of oxidative stress [thiobarbituric acid reactive substances (TBARS) and reduced ascorbic acid (RAA)] and both HSP27 and HSP70 were measured.

RESULTS

At rest, compared with the control group, the TBARS level was higher in groups II, III and IV patients, and the RAA level was lower in groups III and IV. In addition, HSP70 levels were significantly lower in all CFS groups, compared with controls, but negative correlations were found between resting HSP27 and HSP70 levels and the history of physical activity. After exercise, the peak level of TBARS significantly increased in groups II, III and IV, and the variations in HSP27 and HSP70 were attenuated or suppressed, with the greatest effects in groups III and IV.

CONCLUSION

The presence of stress factors in the history of CFS patients is associated with severe oxidative stress and the suppression of protective HSP27 and HSP70 responses to exercise.

Oxidative stress and fatigue in systemic lupus erythematosus

Objective: The objective of this study is to investigate the relationship of oxidative stress to fatigue in systemic lupus erythematosus (SLE). Methods: Patients with a confirmed diagnosis of SLE by ACR criteria and healthy controls completed validated questionnaires to assess depression and fatigue. Fatigue was measured with the Fatigue Severity Scale (FSS) and the Profile of Fatigue (Prof-F). Visual analogue scales (VAS) were also used to assess fatigue and pain. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma F2-isoprostane was measured with gas chromatography/mass spectroscopy to assess oxidative stress. Evaluation included medical record review, physical exam and calculation of body mass index (BMI), disease activity (SLEDAI) and damage (SLICC) in the SLE patients. Results: Seventy-one SLE patients with low disease activity (mean SLEDAI = 1.62 standard error (SE) 0.37, range 0–8) were compared to 51 controls. Fatigue-limiting physical activity (defined as FSS ≥ 4) was present in 56% of patients and 12% of controls. F2-isoprostane was higher in SLE patients with fatigue compared to not-fatigued SLE subjects ( p = .0076) who were otherwise similar in ethnicity, disease activity and cardiovascular risk factors. Plasma F2-isoprostane was strongly correlated with FSS and Profile of Somatic Fatigue (Prof-S) ( p < .0001), VAS fatigue ( p = .005), CES-D ( p = .008) and with BMI ( p = .0001.) In a multivariate model, F2-isoprostane was a significant predictor of FSS after adjustment for age, BMI, pain and depression ( p = .0002). Conclusion: Fatigue in SLE patients with low disease activity is associated with increased F2-isoprostane. F2-isoprostane could provide a useful biomarker to explore mitochondrial function and the regulation of oxidative pathways in patients with SLE in whom fatigue is a debilitating symptom.

Chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is defined by a profound, debilitating fatigue, lasting for at least 6 months and resulting in a substantial reduction of occupational, personal, social and educational status. CFS is a relatively poorly recognized clinical entity, although everyday experience shows that there are many patients with CFS symptoms. The incidence and prevalence of CFS remain unknown in most countries; however, the working population is most affected with predominantly female patients in generative period. Although, CFS was first mentioned four centuries ago, mysterious aethiopathogensis of CFS still intrigues scientists as hundreds of studies are still published every year on the subject. About 80 different aetiological CFS factors are mentioned, which can be classified into five basic groups: genetics, immunology, infectious diseases, endocrinology and neuropsychiatry-psychology. Even today the condition is passed established based on the diagnosis by exclusion of organic and psychiatric disorders, which demands a multidisciplinary approach. As the syndrome is often misdiagnosed and mistreated, self-medication is not uncommon in CFS patients'. In addition, such patients usually suffer for years tolerating severe fatigue. Thus, at the moment there are three priorities regarding CFS; understanding pathogenesis, development of diagnostic tests and creating efficient treatment program.

[Viral infections and oxidative stress]

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Transcription profile analysis of vastus lateralis muscle from patients with chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a disabling condition characterized by unexplained chronic fatigue that impairs normal activities. Many body systems are affected and etiology has not yet been identified. In addition to immunological and psychological aspects, skeletal muscle symptoms are prominent in CFS patients. In an effort to establish which pathways might be involved in the onset and development of muscle symptoms, we used global transcriptome analysis to identify genes that were differentially expressed in the vastus lateralis muscle of female and male CFS patients. We found that the expression of genes that play key roles in mitochondrial function and oxidative balance, including superoxide dismutase 2, were altered, as were genes involved in energy production, muscular trophism and fiber phenotype determination. Importantly, the expression of a gene encoding a component of the nicotinic cholinergic receptor binding site was reduced, suggesting impaired neuromuscular transmission. We argue that these major biological processes could be involved in and/or responsible for the muscle symptoms of CFS.

Chronic fatigue syndrome combines increased exercise-induced oxidative stress and reduced cytokine and Hsp responses

OBJECTIVES

As heat shock proteins (Hsp) protect the cells against the deleterious effects of oxidative stress, we hypothesized that Hsp expression might be reduced in patients suffering from chronic fatigue syndrome (CFS) who present an accentuated exercise-induced oxidative stress.

DESIGN

This case-control study compared nine CFS patients to a gender-, age- and weight-matched control group of nine healthy sedentary subjects.

INTERVENTIONS

All subjects performed an incremental cycling exercise continued until exhaustion. We measured ventilation and respiratory gas exchange and evoked compound muscle potential (M-wave) recorded from vastus lateralis. Repetitive venous blood sampling allowed measurements of two markers of oxidative stress [thiobarbituric acid reactive substances (TBARS) and reduced ascorbic acid (RAA)], two cytokines (IL-6 and TNF-alpha) and two Hsp (Hsp27 and Hsp70) at rest, during maximal exercise and the 60-min recovery period.

RESULTS

Compared with controls, resting CFS patients had low baseline levels of RAA and Hsp70. Their response to maximal exercise associated (i) M-wave alterations indicating reduced muscle membrane excitability, (ii) early and accentuated TBARS increase accompanying reduced changes in RAA level, (iii) absence of significant increase in IL-6 and TNF-alpha, and (iv) delayed and marked reduction of Hsp27 and Hsp70 variations. The post-exercise increase in TBARS was accentuated in individuals having the lowest variations of Hsp27 and Hsp70.

CONCLUSIONS

The response of CFS patients to incremental exercise associates a lengthened and accentuated oxidative stress, which might result from delayed and insufficient Hsp production.

Functional characterization of muscle fibres from patients with chronic fatigue syndrome: case-control study

Chronic fatigue syndrome (CFS) is a disabling condition characterized by unexplained chronic fatigue that impairs normal activities. Although immunological and psychological aspects are present, symptoms related to skeletal muscles, such as muscle soreness, fatigability and increased lactate accumulation, are prominent in CFS patients. In this case-control study, the phenotype of the same biopsy samples was analyzed by determining i) fibre-type proportion using myosin isoforms as fibre type molecular marker and gel electrophoresis as a tool to separate and quantify myosin isoforms, and ii) contractile properties of manually dissected, chemically made permeable and calcium-activated single muscle fibres. The results showed that fibre-type proportion was significantly altered in CSF samples, which showed a shift from the slow- to the fast-twitch phenotype. Cross sectional area, force, maximum shortening velocity and calcium sensitivity were not significantly changed in single muscle fibres from CSF samples. Thus, the contractile properties of muscle fibres were preserved but their proportion was changed, with an increase in the more fatigue-prone, energetically expensive fast fibre type. Taken together, these results support the view that muscle tissue is directly involved in the pathogenesis of CSF and it might contribute to the early onset of fatigue typical of the skeletal muscles of CFS patients.

Inflammatory and oxidative and nitrosative stress pathways underpinning chronic fatigue, somatization and psychosomatic symptoms

PURPOSE OF REVIEW

The aim of this paper is to review recent findings on inflammatory and oxidative and nitrosative stress (IO&NS) pathways in chronic fatigue and somatization disorder.

RECENT FINDINGS

Activation of IO&NS pathways is the key phenomenon underpinning chronic fatigue syndrome (CFS): intracellular inflammation, with an increased production of nuclear factor kappa beta (NFkappabeta), cyclo-oxygenase-2 (COX-2) and inducible NO synthase (iNOS); and damage caused by O&NS to membrane fatty acids and functional proteins. These IO&NS pathways are induced by a number of trigger factors, for example psychological stress, strenuous exercise, viral infections and an increased translocation of LPS from gram-bacteria (leaky gut). The 'psychosomatic' symptoms experienced by CFS patients are caused by intracellular inflammation (aches and pain, muscular tension, fatigue, irritability, sadness, and the subjective feeling of infection); damage caused by O&NS (aches and pain, muscular tension and fatigue); and gut-derived inflammation (complaints of irritable bowel). Inflammatory pathways (monocytic activation) are also detected in somatizing disorder.

SUMMARY

'Functional' symptoms, as occurring in CFS and somatization, have a genuine organic cause, that is activation of peripheral and central IO&NS pathways and gut-derived inflammation. The development of new drugs, aimed at treating those disorders, should target these IO&NS pathways.