Mitochondrial dysfunction and mitophagy activation in blood mononuclear cells of fibromyalgia patients: implications in the pathogenesis of the disease

Introduction

Fibromyalgia is a chronic pain syndrome with unknown etiology. Recent studies have shown some evidence demonstrating that oxidative stress may have a role in the pathophysiology of fibromyalgia. However, it is still not clear whether oxidative stress is the cause or the effect of the abnormalities documented in fibromyalgia. Furthermore, the role of mitochondria in the redox imbalance reported in fibromyalgia also is controversial. We undertook this study to investigate the role of mitochondrial dysfunction, oxidative stress, and mitophagy in fibromyalgia.

Methods

We studied 20 patients (2 male, 18 female patients) from the database of the Sevillian Fibromyalgia Association and 10 healthy controls. We evaluated mitochondrial function in blood mononuclear cells from fibromyalgia patients measuring, coenzyme Q₁₀ levels with high-performance liquid chromatography (HPLC), and mitochondrial membrane potential with flow cytometry. Oxidative stress was determined by measuring mitochondrial superoxide production with MitoSOX™ and lipid peroxidation in blood mononuclear cells and plasma from fibromyalgia patients. Autophagy activation was evaluated by quantifying the fluorescence intensity of LysoTracker™ Red staining of blood mononuclear cells. Mitophagy was confirmed by measuring citrate synthase activity and electron microscopy examination of blood mononuclear cells.

Results

We found reduced levels of coenzyme Q₁₀, decreased mitochondrial membrane potential, increased levels of mitochondrial superoxide in blood mononuclear cells, and increased levels of lipid peroxidation in both blood mononuclear cells and plasma from fibromyalgia patients. Mitochondrial dysfunction was also associated with increased expression of autophagic genes and the elimination of dysfunctional mitochondria with mitophagy.

Conclusions

These findings may support the role of oxidative stress and mitophagy in the pathophysiology of fibromyalgia.     

Cortisol and hypothalamic-pituitary-gonadal axis hormones in follicular-phase women with fibromyalgia and chronic fatigue syndrome and effect of depressive symptoms on these hormones

We investigated abnormalities of the hypothalamic-pituitary-gonadal axis and cortisol concentrations in women with fibromyalgia and chronic fatigue syndrome (CFS) who were in the follicular phase of their menstrual cycle, and whether their scores for depressive symptoms were related to levels of these hormones. A total of 176 subjects participated - 46 healthy volunteers, 68 patients with fibromyalgia, and 62 patients with CFS. We examined concentrations of follicle-stimulating hormone, luteinizing hormone (LH), estradiol, progesterone, prolactin, and cortisol. Depressive symptoms were assessed using the Beck Depression Inventory (BDI). Cortisol levels were significantly lower in patients with fibromyalgia or CFS than in healthy controls (P < 0.05); there were no significant differences in other hormone levels between the three groups. Fibromyalgia patients with high BDI scores had significantly lower cortisol levels than controls (P < 0.05), and so did CFS patients, regardless of their BDI scores (P < 0.05). Among patients without depressive symptoms, cortisol levels were lower in CFS than in fibromyalgia (P < 0.05). Our study suggests that in spite of low morning cortisol concentrations, the only abnormalities in hypothalamic-pituitary-gonadal axis hormones among follicular-phase women with fibromyalgia or CFS are those of LH levels in fibromyalgia patients with a low BDI score. Depression may lower cortisol and LH levels, or, alternatively, low morning cortisol may be a biological factor that contributes to depressive symptoms in fibromyalgia. These parameters therefore must be taken into account in future investigations.     

Fibromyalgia,myofascial pain,tender points and trigger points: splitting or lumping?

Myofascial trigger points (MTPs) have long been a contentious issue in relation to fibromyalgia, and poorly defined pain complaints in general. Can MTPs be reproducibly identified? Do MTPs have valid objective findings, such as spontaneous electromyographic activity, muscle microdialysis evidence for an inflammatory milieu or visualization with newer ultrasound techniques? Is fibromyalgia a syndrome of multiple MTPs, or is focal muscle tenderness a manifestation of central sensitization? These issues are discussed with relevance to a recent paper reporting that manual palpation of active MTPs elicits the spontaneous pain experienced by fibromyalgia patients.     

Biology and therapy of fibromyalgia. Stress, the stress response system, and fibromyalgia

Stress is a state of disharmony, or threatened homeostasis. A stressor could have a psychological origin or a biological origin. Societies have become more intricate with industrialization, and modern individuals try to adapt to the new defiance by forcing their stress response system. The main component of the stress response network is the autonomic nervous system. The present article reviews current knowledge on autonomic dysfunction in fibromyalgia. Sympathetic hyperactivity has been consistently described by diverse groups of investigators. Fibromyalgia is proposed to be a sympathetically maintained neuropathic pain syndrome, and genomic data support this contention. Autonomic dysfunction may also explain other fibromyalgia features not related to pain.     

Total antioxidant capacity and the severity of the pain in patients with fibromyalgia

The purpose of the study was to determine the oxidative and antioxidative status of plasma in patients with fibromyalgia. Total antioxidant capacity (TAC) of plasma was significantly lower in patients with fibromyalgia (n = 20) than in healthy controls (n = 20) [1.5 (SD 0.3) and 1.9 (SD 0.3) mmol Trolox equiv./l, P = 0.001]. In contrast, the total peroxide level of plasma was significantly higher in patients than in healthy controls [37.4 (SD 6.7) and 33.0 (SD 2.7) micromol H2O2/l; P = 0.01]. The oxidative stress index (OSI) level was significantly higher in patients with fibromyalgia than in healthy controls [2.5 (SD 1.0) and 1.8 (SD 0.4); P = 0.007]. A significant negative correlation between visual analogue scale (VAS) and TAC level was determined (r = -0.79, P < 0.001). The present results indicate that patients with fibromyalgia are exposed to oxidative stress and this increased oxidative stress may play a role in the etiopathogenesis of the disease. Supplementation of antioxidant vitamins such as vitamins C and E to the therapy may be indicated.     

Dysautonomia,fibromyalgia and reflex dystrophy

Autonomic nervous system dysfunction observed in fibromyalgia, characterized without exception by a sympathetic hyperactivity and hyporeactivity, has been reported. However, several studies demonstrated reduced levels of norepinephrine and neuropeptide Y at rest and after tilt table in some patients, which was improved by beta-stimulating agents. These findings support heterogeneity in fibromyalgia-associated dysautonomia. Fibromyalgia could be a generalized sympathetic dystrophy since both conditions are activated by trauma and partly linked to sympathetic mechanisms. Yet they differ on several points: hormonal and neurochemical abnormalities are observed in fibromyalgia whereas activation by peripheral trauma and hyperosteolysis are observed in reflex sympathetic dystrophy.     

Vulnerability to traumatic stress in fibromyalgia patients: 19 month follow-up after the great East Japan disaster

Introduction

The aim of this study was to investigate vulnerability and long-term influence of traumatic stress caused by the Great East Japan Disaster which occurred on March 11, 2011, in patients with fibromyalgia, which is a chronic pain syndrome probably involving central sensitization.

Methods

A total of 60 female patients with fibromyalgia were compared with female patients with rheumatoid arthritis (RA, n = 23) as another chronic pain disease, and with female healthy controls (HC, n = 26) in the observational study. To evaluate responses to traumatic stress, the scores of Impact of Event Scale-Revised (IES-R) were assessed one month after the disaster and every six months until 19 months after the disaster. We also evaluated levels of depression during the study period. To know the score of IES-R of patients with fibromyalgia during usual living, we assessed IES-R in another population of fibromyalgia patients without exposure to a great disaster.

Results

The mean score of IES-R one month after the disaster in the fibromyalgia group (24.6 [SD 18.9]) was significantly higher than that of RA group (13.4 [SD 14.5]) or HC group (9.1 [9.2]) (F = 9.96, p < 0.0001). However, the mean score of IES-R in fibromyalgia patients without exposure to a great disaster was (20.3 [SD 18.7]), which was almost the same value as the fibromyalgia group seven months after the disaster (20.2 [SD 19.5]). Repeated measures analysis of variance showed significant effect of time course in the depression-related symptoms (F = 6.68, P = 0.001), and a post-hoc test revealed that the number of depression-related symptoms one month before the disaster was significantly different from other time points until 19 months after the disaster, respectively.

Conclusions

Although response to acute stress induced by the great earthquake was likely to be settled within seven months after the disaster, depression-related symptoms have been increasing for more than one year after the disaster, despite exclusion of patients with major depression at baseline. This long-lasting worsening of depression-related symptoms may have been in response to chronic stress induced by the fear of radiation due to the nuclear power disaster. These findings suggest that patients with fibromyalgia are vulnerable to chronic stress rather than acute stress.     

Oxidative Stress Induces Mitochondrial Dysfunction in a Subset of Autism Lymphoblastoid Cell Lines in a Well-Matched Case Control Cohort

There is increasing recognition that mitochondrial dysfunction is associated with the autism spectrum disorders. However, little attention has been given to the etiology of mitochondrial dysfunction or how mitochondrial abnormalities might interact with other physiological disturbances associated with autism, such as oxidative stress. In the current study we used respirometry to examine reserve capacity, a measure of the mitochondrial ability to respond to physiological stress, in lymphoblastoid cell lines (LCLs) derived from children with autistic disorder (AD) as well as age and gender-matched control LCLs. We demonstrate, for the first time, that LCLs derived from children with AD have an abnormal mitochondrial reserve capacity before and after exposure to increasingly higher concentrations of 2,3-dimethoxy-1,4-napthoquinone (DMNQ), an agent that increases intracellular reactive oxygen species (ROS). Specifically, the AD LCLs exhibit a higher reserve capacity at baseline and a sharper depletion of reserve capacity when ROS exposure is increased, as compared to control LCLs. Detailed investigation indicated that reserve capacity abnormalities seen in AD LCLs were the result of higher ATP-linked respiration and maximal respiratory capacity at baseline combined with a marked increase in proton leak respiration as ROS was increased. We further demonstrate that these reserve capacity abnormalities are driven by a subgroup of eight (32%) of 25 AD LCLs. Additional investigation of this subgroup of AD LCLs with reserve capacity abnormalities revealed that it demonstrated a greater reliance on glycolysis and on uncoupling protein 2 to regulate oxidative stress at the inner mitochondria membrane. This study suggests that a significant subgroup of AD children may have alterations in mitochondrial function which could render them more vulnerable to a pro-oxidant microenvironment derived from intrinsic and extrinsic sources of ROS such as immune activation and pro-oxidant environmental toxicants. These findings are consistent with the notion that AD is caused by a combination of genetic and environmental factors.     

Implication of Endoplasmic Reticulum Stress in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is categorized as a neurodevelopmental disorder according to the Diagnostic and Statistical Manual of Disorders, Fifth Edition and is defined as a congenital impairment of the central nervous system. ASD may be caused by a chromosomal abnormality or gene mutation. However, these etiologies are insufficient to account for the pathogenesis of ASD. Therefore, we propose that the etiology and pathogenesis of ASD are related to the stress of the endoplasmic reticulum (ER). ER stress, induced by valproic acid, increased in ASD mouse model, characterized by an unfolded protein response that is activated by this stress. The inhibition of neurite outgrowth and expression of synaptic factors are observed in ASD. Similarly, ER stress suppresses the neurite outgrowth and expression of synaptic factors. Additionally, hyperplasia of the brain is observed in patients with ASD. ER stress also enhances neuronal differentiation. Synaptic factors, such as cell adhesion molecule and shank, play important roles in the formation of neural circuits. Thus, ER stress is associated with the abnormalities of neuronal differentiation, neurite outgrowth, and synaptic protein expression. ER stress elevates the expression of the ubiquitin-protein ligase HRD1 for the degradation of unfolded proteins. HRD1 expression significantly increased in the middle frontal cortex in the postmortem of patients with ASD. Moreover, HRD1 silencing improved the abnormalities induced by ER stress. Because other ubiquitin ligases are related with neurite outgrowth, ER stress may be related to the pathogenesis of neuronal developmental diseases via abnormalities of neuronal differentiation or maturation.     

Ovarian dysfunction, stress, and disease: a primate continuum

Menopause is recognized as a period of increased risk for coronary heart disease (CHD) and osteoporosis. Vulnerability to these conditions is often attributed to the naturally occurring estrogen deficiency characteristic of this part of the life cycle. Premenopausal reductions in endogenous estrogen occasioned by functional ovarian abnormalities or failure are hypothesized to be similarly pathogenic and to accelerate development of CHD and osteoporosis prematurely, thereby increasing the health burden of older women. These functional abnormalities, which occur along a continuum from mild, luteal phase progesterone deficiency to amenorrhea, are relatively common and are often attributed to psychogenic factors (stress, anxiety, depression, or other emotional disturbance), exercise, or energy imbalance. Although numerous investigators have commented on these functional deficits, the abnormalities can be difficult to diagnose and are generally unappreciated for the contribution they may make to postmenopausal disease. Studies in nonhuman primates confirm that these deficits are easily induced by psychological stress and exercise, and that they accelerate the development of cardiovascular disease and perhaps bone loss in the presence of a typical North American diet. However, functional reproductive deficits are also reversible and are thus potentially amenable to environmental or behavioral intervention. Data from both women and nonhuman primates support the hypothesis that functional reproductive deficits are adaptive when triggered appropriately but are detrimental when activated in an environment (e.g., sedentary lifestyle, high-fat diet) permissive to the development of chronic disease.     

Role of intracellular calcium ions in the physiopathology of fibromyalgia syndrome.

Calcium ions have a key role in the physiology of muscular contraction: changes in calcium ion concentration may be involved in the pathogenesis of fibromyalgia. Although, since the plasmatic level of calcium in fibromyalgia patients is always in the normal range, it seemed interesting to evaluate the intracellular calcium concentration. The study was carried out on two groups of subjects: 70 affected by fibromyalgia and 40 healthy controls. The results obtained show that in fibromyalgia patients the intracellular calcium concentration is significantly reduced in comparison to that of healthy controls: the reduced intracellular calcium concentration seems to be a peculiar characteristic of fibromyalgia patients and may be potentially responsible for muscular hypertonus. The effective role of this anomaly in the physiopathology of fibromyalgia and the potential role of drugs active on the calcium homeostasis are still to be confirmed.     

Animal models of fibromyalgia

Animal models of disease states are valuable tools for developing new treatments and investigating underlying mechanisms. They should mimic the symptoms and pathology of the disease and importantly be predictive of effective treatments. Fibromyalgia is characterized by chronic widespread pain with associated co-morbid symptoms that include fatigue, depression, anxiety and sleep dysfunction. In this review, we present different animal models that mimic the signs and symptoms of fibromyalgia. These models are induced by a wide variety of methods that include repeated muscle insults, depletion of biogenic amines, and stress. All potential models produce widespread and long-lasting hyperalgesia without overt peripheral tissue damage and thus mimic the clinical presentation of fibromyalgia. We describe the methods for induction of the model, pathophysiological mechanisms for each model, and treatment profiles.     

Paraoxonase and arylesterase activities in fibromyalgia

We aimed to evaluate the association of serum paraoxonase and arylesterase activities and oxidative/antioxidative status in patients with fibromyalgia. Forty-two patients with fibromyalgia and 53 healthy controls were included in the study. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. Oxidative and antioxidative status were evaluated by measuring serum lipid hydroperoxide (LOOH) levels, total antioxidant status (TAS) and free sulfhydryl groups (-SH = total thiol). Lipid parameters were determined by routine laboratory methods. Serum paraoxonase and arylesterase activities, and TAS were lower in patients with fibromyalgia than in controls (P < 0.001, for all), and the -SH level was also lower in the patient group (P = 0.03). LOOH levels were higher in the patient group than in controls (P = 0.01). Our results suggest that patients with fibromyalgia were exposed to oxidative stress, and paraoxonase and arylesterase activities were decreased in these patients. Patients with fibromyalgia might be prone to development of atherosclerosis with reduced paraoxonase and arylesterase activities.     

Retinal glutamate in diabetes and effect of antioxidants

Diabetes results in various biochemical abnormalities in the retina, but which of these abnormalities are critical in the development of retinopathy is not known. The aim of this study is to examine the effect of antioxidant supplementation on diabetes-induced alterations of retinal glutamate, and to explore the inter-relationship between alterations of retinal glutamate, oxidative stress, and nitric oxide (NO) in diabetes. Glutamate was measured in the retina at 2 months of diabetes in rats receiving diets supplemented with or without a mixture of antioxidants containing ascorbic acid, Trolox, DL alpha-tocopherol acetate, N-acetyl cysteine, beta-carotene and selenium. The relationship between glutamate, oxidative stress and NO was evaluated using both bovine retinal endothelial cells and normal rat retina. In diabetes, retinal glutamate was elevated by 40, thiobarbituric acid-reactive substances (TBARS) by 100, and NO by 70%, respectively. Administration of antioxidants inhibited the diabetes-induced increases in glutamate, TBARS and NO. Incubation of bovine retinal endothelial cells or normal rat retina with glutamate significantly increased TBARS and NO, and addition of either antioxidant (N-acetyl cysteine) or a NO synthase inhibitor prevented the glutamate-induced elevation in oxidative stress and NO. Incubation of retina with a glutamate agonist, likewise elevated oxidative stress and NO, and memantine inhibited such elevations. Thus, the alterations of retinal glutamate, oxidative stress and NO appear to be inter-related in diabetes, and antioxidant therapy may be a suitable approach to determine the roles of these abnormalities in the development of diabetic retinopathy.     

Elevated frequency of abnormalities in barn swallows from Chernobyl

Ever since the Chernobyl accident in 1986, that contaminated vast areas in surrounding countries with radiation, abnormalities and birth defects have been reported in human populations. Recently, several studies suggested that the elevated frequency of such abnormalities can be attributed to poverty and stress in affected human populations. Here, we present long-term results for a free-living population of barn swallows, Hirundo rustica, demonstrating the presence of 11 morphological abnormalities in populations around Chernobyl, but much less frequently in an uncontaminated Ukrainian control population and three more distant control populations. The presence of these abnormalities in barn swallows is associated with reduced viability. These findings demonstrate a link between morphological abnormalities and radiation in an animal population that cannot be attributed to poverty and stress. The most parsimonious hypothesis for abnormalities in animal and human populations alike is that the effects are caused by the same underlying cause, viz. radiation derived from the Chernobyl accident.     

Interactions of oxidative stress with cellular calcium dynamics and glucose metabolism in Alzheimer's disease

Considerable evidence suggests that oxidative stress (elevated levels of reactive oxygen species), altered energy metabolism, and changes in calcium dynamics are central to Alzheimer's disease (AD). Abnormalities in each of these processes occur in AD, and they can be plausibly linked to the pathology and clinical outcome of the disease. Abnormalities in these same processes in peripheral tissues, such as fibroblasts, indicate that these are inherent properties of AD cells and are not merely a secondary response to neurodegeneration. Results in cultured cells including fibroblasts demonstrate that oxidative stress can lead to the AD-related changes in calcium and energy metabolism. Data also suggest that abnormalities in the cellular calcium stores, the ability to handle oxidative stress, and to respond to metabolic impairment link the AD-causing gene mutations to the disease process. Abnormal metabolism and oxidative stress alter the proteins and cellular processes that are modified in AD, and can be readily linked to neuronal death and brain dysfunction. Prevention and/or correction of these abnormalities are appropriate therapeutic targets.     

Cortisol and hypothalamic–pituitary–gonadal axis hormones in follicular-phase women with fibromyalgia and chronic fatigue syndrome and effect of depressive symptoms on these hormones

We investigated abnormalities of the hypothalamic–pituitary–gonadal axis and cortisol concentrations in women with fibromyalgia and chronic fatigue syndrome (CFS) who were in the follicular phase of their menstrual cycle, and whether their scores for depressive symptoms were related to levels of these hormones. A total of 176 subjects participated – 46 healthy volunteers, 68 patients with fibromyalgia, and 62 patients with CFS. We examined concentrations of follicle-stimulating hormone, luteinizing hormone (LH), estradiol, progesterone, prolactin, and cortisol. Depressive symptoms were assessed using the Beck Depression Inventory (BDI). Cortisol levels were significantly lower in patients with fibromyalgia or CFS than in healthy controls (P < 0.05); there were no significant differences in other hormone levels between the three groups.     

Free radicals: a potential pathogenic mechanism in inherited muscular dystrophy

Despite years of intensive work, the biochemical defect responsible for the pathogenesis of inherited muscular dystrophy has not been identified either in humans or animal models. This review examines evidence in support of the hypothesis that free radicals may be responsible for muscle degeneration in this disorder. A variety of cellular abnormalities noted in dystrophic muscles can be accounted for by free radical mediated damage. In addition, chemical by-products associated with free radical damage are found in dystrophic muscle tissue from humans and animals with this disease. Various enzymatic antioxidant systems can be enhanced as a normal cellular response to oxidative stress, and such changes are seen both in dystrophic muscle cells and certain other tissues of dystrophic animals. An increased level of free radical damage would follow from either: enhanced production of free radical species, or a deficient component of the cellular antioxidant system, such as vitamin E. The free radical hypothesis of muscular dystrophy can account for data supporting several alternative theories of the pathogenesis of this disease, as well as other observations which have not previously been explained.     

Beyond pain in fibromyalgia: insights into the symptom of fatigue

Fatigue is a disabling, multifaceted symptom that is highly prevalent and stubbornly persistent. Although fatigue is a frequent complaint among patients with fibromyalgia, it has not received the same attention as pain. Reasons for this include lack of standardized nomenclature to communicate about fatigue, lack of evidence-based guidelines for fatigue assessment, and a deficiency in effective treatment strategies. Fatigue does not occur in isolation; rather, it is present concurrently in varying severity with other fibromyalgia symptoms such as chronic widespread pain, unrefreshing sleep, anxiety, depression, cognitive difficulties, and so on. Survey-based and preliminary mechanistic studies indicate that multiple symptoms feed into fatigue and it may be associated with a variety of physiological mechanisms. Therefore, fatigue assessment in clinical and research settings must consider this multi-dimensionality. While no clinical trial to date has specifically targeted fatigue, randomized controlled trials, systematic reviews, and meta-analyses indicate that treatment modalities studied in the context of other fibromyalgia symptoms could also improve fatigue. The Outcome Measures in Rheumatology (OMERACT) Fibromyalgia Working Group and the Patient Reported Outcomes Measurement Information System (PROMIS) have been instrumental in propelling the study of fatigue in fibromyalgia to the forefront. The ongoing efforts by PROMIS to develop a brief fibromyalgia-specific fatigue measure for use in clinical and research settings will help define fatigue, allow for better assessment, and advance our understanding of fatigue.     

Oxidative stress increases internal calcium stores and reduces a key mitochondrial enzyme

Fibroblasts from patients with genetic and non-genetic forms of Alzheimer's disease (AD) show many abnormalities including increased bombesin-releasable calcium stores (BRCS), diminished activities of the mitochondrial alpha-ketoglutarate dehydrogenase complex (KGDHC), and an altered ability to handle oxidative stress. The link between genetic mutations (and the unknown primary event in non-genetic forms) and these other cellular abnormalities is unknown. To determine whether oxidative stress could be a convergence point that produces the other AD-related changes, these experiments tested in fibroblasts the effects of H(2)O(2), in the presence or absence of select antioxidants, on BRCS and KGDHC. H(2)O(2) concentrations that elevated carboxy-dichlorofluorescein (c-H(2)DCF)-detectable ROS increased BRCS and decreased KGDHC activity. These changes are in the same direction as those in fibroblasts from AD patients. Acute treatments with the antioxidants Trolox, or DMSO decreased c-H(2)DCF-detectable ROS by about 90%, but exaggerated the H(2)O(2)-induced increases in BRCS by about 4-fold and did not alter the reduction in KGDHC. Chronic pretreatments with Trolox more than doubled the BRCS, tripled KGDHC activities, and reduced the effects of H(2)O(2). Pretreatment with DMSO or N-acetyl cysteine diminished the BRCS and either had no effect, or exaggerated the H(2)O(2)-induced changes in these variables. The results demonstrate that BRCS and KGDHC are more sensitive to H(2)O(2) derived species than c-H(2)DCF, and that oxidized derivatives of the antioxidants exaggerate the actions of H(2)O(2). The findings support the hypothesis that select abnormalities in oxidative processes are a critical part of a cascade that leads to the cellular abnormalities in cells from AD patients.