Normal production of inflammatory cytokines in chronic fatigue and fibromyalgia syndromes determined by intracellular cytokine staining in short-term cultured blood mononuclear cells

Proteomics in Patients with Fibromyalgia Syndrome: A Systematic Review of Observational Studies

PURPOSE OF REVIEW

Fibromyalgia syndrome (FMS) is a disease of unknown pathophysiology, with the diagnosis being based on a set of clinical criteria. Proteomic analysis can provide significant biological information for the pathophysiology of the disease but may also reveal biomarkers for diagnosis or therapeutic targets. The present systematic review aims to synthesize the evidence regarding the proteome of adult patients with FMS using data from observational studies.

RECENT FINDINGS

An extensive literature search was conducted in MEDLINE/PubMed, CENTRAL, and clinicaltrials.gov from inception until November 2022. The study protocol was published in OSF. Two independent reviewers evaluated the studies and extracted data. The quality of studies was assessed using the modified Newcastle-Ottawa scale adjusted for proteomic research. Ten studies fulfilled the protocol criteria, identifying 3328 proteins, 145 of which were differentially expressed among patients with FMS against controls. The proteins were identified in plasma, serum, cerebrospinal fluid, and saliva samples. The control groups included healthy individuals and patients with pain (inflammatory and non-inflammatory). The most important proteins identified involved transferrin, α-, β-, and γ-fibrinogen chains, profilin-1, transaldolase, PGAM1, apolipoprotein-C3, complement C4A and C1QC, immunoglobin parts, and acute phase reactants. Weak correlations were observed between proteins and pain sensation, or quality of life scales, apart from the association of transferrin and a2-macroglobulin with moderate-to-severe pain sensation. The quality of included studies was moderate-to-good. FMS appears to be related to protein dysregulation in the complement and coagulation cascades and the metabolism of iron. Several proteins may be dysregulated due to the excessive oxidative stress response.

ME/CFS and Long COVID share similar symptoms and biological abnormalities: road map to the literature

Some patients remain unwell for months after "recovering" from acute COVID-19. They develop persistent fatigue, cognitive problems, headaches, disrupted sleep, myalgias and arthralgias, post-exertional malaise, orthostatic intolerance and other symptoms that greatly interfere with their ability to function and that can leave some people housebound and disabled. The illness (Long COVID) is similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well as to persisting illnesses that can follow a wide variety of other infectious agents and following major traumatic injury. Together, these illnesses are projected to cost the U.S. trillions of dollars. In this review, we first compare the symptoms of ME/CFS and Long COVID, noting the considerable similarities and the few differences. We then compare in extensive detail the underlying pathophysiology of these two conditions, focusing on abnormalities of the central and autonomic nervous system, lungs, heart, vasculature, immune system, gut microbiome, energy metabolism and redox balance. This comparison highlights how strong the evidence is for each abnormality, in each illness, and helps to set priorities for future investigation. The review provides a current road map to the extensive literature on the underlying biology of both illnesses.

Regulatory T-cells and IL-5 mediate pain outcomes in a preclinical model of chronic muscle pain

Fibromyalgia (FM) is a chronic musculoskeletal pain disorder primarily diagnosed in women. Historically, clinical literature focusing on cytokines and immune cells has been inconsistent. However, recent key studies show several layers of immune system dysfunction in FM. Preclinically, studies of the immune system have focused on monocytes with little focus on other immune cells. Importantly, T-cells are implicated in the development and resolution of chronic pain states, particularly in females. Our previous work showed that monocytes from women with FM produced more interleukin 5 (IL-5) and systemic treatment of IL-5 reversed mechanical hypersensitivity in a preclinical model of FM. Typically, IL-5 is produced by T_H2-cells, so in this study we assessed T-cell populations and cytokine production in female mice using the acid-induced chronic muscle pain model of FM before and after treatment with IL-5. Two unilateral injections of pH4.0 saline, five days apart, into the gastrocnemius muscle induce long-lasting widespread pain. We found that peripheral (blood) regulatory T_helper-cells (CD4⁺ FOXP3+) are downregulated in pH4.0-injected mice, with no differences in tissue (lymph nodes) or CD8⁺ T-cell populations. We tested the analgesic properties of IL-5 using a battery of spontaneous and evoked pain measures. Interestingly, IL-5 treatment induced place preference in mice previously injected with pH4.0 saline. Mice treated with IL-5 show limited changes in T-cell populations compared to controls, with a rescue in regulatory T-cells which positively correlates with improved mechanical hypersensitivity. The experiments in this study provide novel evidence that downregulation of regulatory T-cells play a role in chronic muscle pain pathology in the acidic saline model of FM and that IL-5 signaling is a promising target for future development of therapeutics.

[Mechanisms underlying chronic fatigue, a symptom too often overlooked II- From deregulated immunity to neuroinflammation and its consequences]

Hypothalamus stimulation by inflammatory and / or stress signals can trigger activation of the HPA (hypothalamic-pituitary-adrenal) axis, which includes the hypothalamus, pituitary and adrenal gland. Acute activation of the HPA axis is fundamental for the fight or flight response. It allows a maximal energy mobilization available for an effort, whilst erasing fatigue. On the contrary, the chronic activation of this axis decreases muscle efficiency and leads to chronic fatigue. In this second part of our review will be discussed several strategic points that need to be considered for attempting to understand and treat together inflammation and chronic fatigue.

IL-5 mediates monocyte phenotype and pain outcomes in fibromyalgia

ABSTRACT

Fibromyalgia (FM) is characterized by widespread chronic pain, fatigue, and somatic symptoms. The influence of phenotypic changes in monocytes on symptoms associated with FM is not fully understood. The primary aim of this study was to take a comprehensive whole-body to molecular approach in characterizing relationships between monocyte phenotype and FM symptoms in relevant clinical populations. Lipopolysaccharide-evoked and spontaneous secretion of IL-5 and other select cytokines from circulating monocytes was higher in women with FM compared to women without pain. In addition, greater secretion of IL-5 was significantly associated with pain and other clinically relevant psychological and somatic symptoms of FM. Furthermore, higher levels of pain and pain-related symptoms were associated with a lower percentage of intermediate monocytes (CD14++/CD16+) and a greater percentage of nonclassical monocytes (CD14+/CD16++) in women with FM. Based on findings from individuals with FM, we examined the role of IL-5, an atypical cytokine secreted from monocytes, in an animal model of widespread muscle pain. Results from the animal model show that IL-5 produces analgesia and polarizes monocytes toward an anti-inflammatory phenotype (CD206+). Taken together, our data suggest that monocyte phenotype and their cytokine profiles are associated with pain-related symptoms in individuals with FM. Furthermore, our data show that IL-5 has a potential role in analgesia in an animal model of FM. Thus, targeting anti-inflammatory cytokines such as IL-5 secreted by circulating leukocytes could serve as a promising intervention to control pain and other somatic symptoms associated with FM.

Anti-Inflammatory Diets and Fatigue

Accumulating data indicates a link between a pro-inflammatory status and occurrence of chronic disease-related fatigue. The questions are whether the observed inflammatory profile can be (a) improved by anti-inflammatory diets, and (b) if this improvement can in turn be translated into a significant fatigue reduction. The aim of this narrative review was to investigate the effect of anti-inflammatory nutrients, foods, and diets on inflammatory markers and fatigue in various patient populations. Next to observational and epidemiological studies, a total of 21 human trials have been evaluated in this work. Current available research is indicative, rather than evident, regarding the effectiveness of individuals’ use of single nutrients with anti-inflammatory and fatigue-reducing effects. In contrast, clinical studies demonstrate that a balanced diet with whole grains high in fibers, polyphenol-rich vegetables, and omega-3 fatty acid-rich foods might be able to improve disease-related fatigue symptoms. Nonetheless, further research is needed to clarify conflicting results in the literature and substantiate the promising results from human trials on fatigue.

Possible Molecular Mediators Involved and Mechanistic Insight into Fibromyalgia and Associated Co-morbidities

Fibromyalgia is a chronic complex syndrome of non-articulate origin characterized by musculoskeletal pain, painful tender points, sleep problems and co-morbidities including depression, migraine. The etiopathogenesis of fibromyalgia is complex, variable and remains inconclusive. The etiological factors that have been defined include stress, genetic predisposition and environmental components. As per the reports of the American College of Rheumatology (ACR) the prevalence of fibromyalgia varies from 2 to 22% among the general population with poor diagnostic features primarily pain. Fibromyalgia encompasses a spectrum of co-morbid conditions with multifarious pathogenesis. The highly prevalent manifestations of fibromyalgia include heterogeneous pain and aches. Biochemical and neurobiological elements of fibromyalgia include neurotransmitters, hypothalamic pituitary adrenal axis (HPA axis), inflammatory cytokines, monoaminergic pathway, opioid peptides, sex hormones, nerve growth factor (NGF) and local free radical insult. An imbalance in the serotonergic system is the major underlying etiological factor that has been explored most widely. Owing to complex interplay of diverse pathophysiological pathways, overlapping co-morbidities such as depression have been clinically observed. Therapeutic management of fibromyalgia involves both non pharmacological and pharmacological measures. The current review presents various dysregulations and their association with symptoms of fibromyalgia along with their underlying neurobiological aspects.

Secreted and intracellular cytokines are complementary measures for human monocytes treated with Toll-like receptor agonists

Cytokine production by human peripheral blood mononuclear cells including monocytes, is frequently assessed by measuring secreted cytokines using enzyme linked immunosorbent assay (ELISA), whereby the total concentration of one cytokine of interest is obtained without information regarding the cell type responsible for making the cytokine. Cytokines can be retained inside the cell using protein transport inhibitors. Subsequent analysis by flow cytometry not only identifies the cell type producing the cytokine but can semi-quantitate the amount of cytokine produced by measuring the geometric mean fluorescence intensity (gMFI) and is amenable to analyzing more than one protein associated with the same cell (multiplexing). We hypothesized that a more comprehensive and biologically meaningful cytokine profile could be acquired by measuring both secreted and the retained intracellular cytokines in parallel cultures of magnetic-sorted CD14+ monocytes. Peripheral monocytes were isolated from 18 healthy donors and treated with standardized molecules that stimulate cytokine production; Toll-like receptor (TLR)4 agonist (lipopolysaccharide, LPS) or TLR7/8 agonist (R848). Pro-inflammatory cytokines (interleukin (IL)-6, IL-8 and tumour necrosis factor (TNF)) secreted into the culture medium were measured by ELISA. Parallel cultures were treated with LPS and R848 in the presence of brefeldin A (protein transport inhibitor) and the accumulated intracellular cytokines measured by flow cytometry. Each cytokine (IL-6/IL-8/TNF) gave a unique general pattern when secreted versus intracellular cytokine measurements (frequency and gMFI) were plotted to determine correlation. For monocytes treated with the TLR4 agonist, secreted IL-8 correlated with the frequency of IL-8 positive cells (R = 0.559, p = .016) and not with the amount (gMFI) of IL-8 per cell. In contrast, monocytes treated with the TLR7/8 agonist showed no correlation of secreted IL-8 with the frequency of IL-8 positive cells, but with this treatment secreted IL-6 was correlated with an increase in the frequency of IL-6 positive cells (R = 0.501, p = .034). TNF secretion from monocytes treated with either the TLR4 or TLR7/8 agonist did not correlate with the frequency or gMFI of TNF positive cells. However, there were significant correlations between the TLR4 and TLR7/8 induced TNF response (secreted and gMFI). We conclude that there are fundamental differences in secreted and intracellular IL-6/IL-8/TNF production after monocytes are treated with TLR agonists. Furthermore, secreted and intracellular cytokine analyses are complementary measures that should be used in parallel to explore inflammatory response and cytokine biology.

Higher Prevalence of "Low T3 Syndrome" in Patients With Chronic Fatigue Syndrome: A Case-Control Study

Chronic fatigue syndrome (CFS) is a heterogeneous disease with unknown cause(s). CFS symptoms resemble a hypothyroid state, possibly secondary to chronic (low-grade) (metabolic) inflammation. We studied 98 CFS patients (21-69 years, 21 males) and 99 age- and sex-matched controls (19-65 years, 23 males). We measured parameters of thyroid function, (metabolic) inflammation, gut wall integrity and nutrients influencing thyroid function and/or inflammation. Most remarkably, CFS patients exhibited similar thyrotropin, but lower free triiodothyronine (FT3) (difference of medians 0.1%), total thyroxine (TT4) (11.9%), total triiodothyronine (TT3) (12.5%), %TT3 (4.7%), sum activity of deiodinases (14.4%), secretory capacity of the thyroid gland (14.9%), 24-h urinary iodine (27.6%), and higher % reverse T3 (rT3) (13.3%). FT3 below the reference range, consistent with the "low T3 syndrome," was found in 16/98 CFS patients vs. 7/99 controls (OR 2.56; 95% confidence interval = 1.00-6.54). Most observations persisted in two sensitivity analyses with more stringent cutoff values for body mass index, high-sensitive C-reactive protein (hsCRP), and WBC. We found possible evidence of (chronic) low-grade metabolic inflammation (ferritin and HDL-C). FT3, TT3, TT4, and rT3 correlated positively with hsCRP in CFS patients and all subjects. TT3 and TT4 were positively related to hsCRP in controls. Low circulating T3 and the apparent shift from T3 to rT3 may reflect more severely depressed tissue T3 levels. The present findings might be in line with recent metabolomic studies pointing at a hypometabolic state. They resemble a mild form of "non-thyroidal illness syndrome" and "low T3 syndrome" experienced by a subgroup of hypothyroid patients receiving T4 monotherapy. Our study needs confirmation and extension by others. If confirmed, trials with, e.g., T3 and iodide supplements might be indicated.

Depression, evening salivary cortisol and inflammation in chronic fatigue syndrome: A psychoneuroendocrinological structural regression model

INTRODUCTION

Chronic Fatigue Syndrome (CFS) is a poorly understood illness that is characterized by diverse somatic symptoms, hypothalamic pituitary adrenal (HPA) axis dysfunction and heightened inflammatory indicators. These symptoms are often exacerbated and accompanied by psychological distress states and depression. Since depression is known to be associated with HPA axis dysfunction and greater inflammation, a psychoneuroendocrinological (PNE) model of inflammation was examined in persons diagnosed with CFS in order to uncover underlying biopsychosocial mechanisms in this poorly understood chronic illness.

METHODS

Baseline data were drawn from two randomized controlled trials testing the efficacy of different forms of psychosocial intervention, and included psychological questionnaires, di-urnal salivary cortisol, and blood samples. Data were analyzed with structural equation modeling (SEM).

RESULTS

The sample (N=265) was mostly middle-aged (M_age=49.36±10.9, range=20-73years), Caucasian (67.7%), female (81.7%), highly educated (85.5% completed some college, college, or graduate program), and depressed (CES-D M=23.87±12.02, range 2-57). The SEM supporting a psychoneuroendocrinological model of immune dysregulation in CFS fit the data χ² (12)=17.725, p=0.1243, RMSEA=0.043, CFI=0.935, SRMR=0.036. Depression was directly related to evening salivary cortisol and inflammation, such that higher evening cortisol predicted greater depressive symptoms (β=0.215, p<0.01) and higher pro-inflammatory cytokines (interleukin-2 [IL-2], IL-6, and tumor necrosis factor-alpha [TNF-α] levels (β=0.185, p<0.05), when controlling for covariates.

DISCUSSION

Results highlight the role of depression, cortisol and inflammation in possible biological mechanisms involved in the pathophysiology of CFS. Time-lagged, longitudinal analyses are needed to fully explore these relationships.

Potential Mediators between Fibromyalgia and C-Reactive protein: Results from a Large U.S. Community Survey

BACKGROUND

Fibromyalgia, a potentially debilitating chronic pain syndrome of unknown etiology, may be characterized by inflammation. In this study, we investigated the relation of FMS to serum C-reactive protein (CRP) in a large population of adults (18+) and investigated the influence of other factors on this relationship, including BMI, comorbidities, as well as mood and sleep disturbance.

METHODS

Participants were 52,535 Ohio Valley residents (Fibromyalgia n = 1125). All participants completed a comprehensive health survey (2005-2006) part of the C8 Health Project; serum levels of CRP were obtained, as was history of Fibromyalgia physician diagnosis. Logistic and linear regressions were used for this cross-sectional analysis.

RESULTS

Mean CRP was higher among participants reporting Fibromyalgia than those without (5.54 ± 9.8 vs.3.75 ± 7.2 mg/L, p < .0001)). CRP level showed a strong, positive association with FMS (unadjusted odds ratio (OR) for highest vs. lowest quartile = 2.5 (CI 2.1,3.0;p for trend < .0001)); adjustment for demographic and lifestyle factors attenuated but did not eliminate this association (AOR for highest vs. lowest quartile = 1.4 (CI 1.1,1.6;p for trend < .0001)). Further addition of body mass index (BMI) and comorbidities to the model markedly weakened this relationship (AORs, respectively, for highest vs lowest CRP quartile = 1.2 (CI 1.0,1.4) and 1.1 (CI 0.9,1.3). In contrast, inclusion of mood and sleep impairment only modestly reduced the adjusted risk estimate (AORs for highest vs. lowest quartile = 1.3 (CI 1.1,1.5) for each)).

CONCLUSIONS

Findings from this large cross-sectional study indicate a significant positive cross-sectional association of Fibromyalgia to serum C-reactive protein may be explained, in part, by BMI and comorbidity. Prospective research is needed to confirm this, and clarify the potential mediating influence of obesity and comorbid conditions on this relationship.

Circulating Omentin-1 and Chronic Painful Temporomandibular Disorders

AIMS

To investigate the relationship between omentin-1 levels and painful temporomandibular disorders (TMD).

METHODS

In a case-control design, chronic painful TMD cases (n = 90) and TMD-free controls (n = 54) were selected from participants in the multisite OPPERA study (Orofacial Pain: Prospective Evaluation and Risk Assessment). Painful TMD case status was determined by examination using established Research Diagnostic Criteria for TMD (RDC/TMD). Levels of omentin-1 in stored blood plasma samples were measured by using an enzyme linked immunosorbent assay. Binary logistic regression was used to calculate the odds ratios (ORs) and 95% confidence limits (CLs) for the association between omentin-1 and painful TMD. Models were adjusted for study site, age, sex, and body mass index.

RESULTS

The unadjusted association between omentin-1 and chronic painful TMD was statistically nonsignificant (P = .072). Following adjustment for covariates, odds of TMD pain decreased 36% per standard deviation increase in circulating omentin-1 (adjusted OR = 0.64; 95% CL: 0.43, 0.96; P = .031).

CONCLUSION

Circulating levels of omentin-1 were significantly lower in painful TMD cases than controls, suggesting that TMD pain is mediated by inflammatory pathways.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

DNA methylation modifications associated with chronic fatigue syndrome

Chronic Fatigue Syndrome (CFS), also known as myalgic encephalomyelitis, is a complex multifactorial disease that is characterized by the persistent presence of fatigue and other particular symptoms for a minimum of 6 months. Symptoms fail to dissipate after sufficient rest and have major effects on the daily functioning of CFS sufferers. CFS is a multi-system disease with a heterogeneous patient population showing a wide variety of functional disabilities and its biological basis remains poorly understood. Stable alterations in gene function in the immune system have been reported in several studies of CFS. Epigenetic modifications have been implicated in long-term effects on gene function, however, to our knowledge, genome-wide epigenetic modifications associated with CFS have not been explored. We examined the DNA methylome in peripheral blood mononuclear cells isolated from CFS patients and healthy controls using the Illumina HumanMethylation450 BeadChip array, controlling for invariant probes and probes overlapping polymorphic sequences. Gene ontology (GO) and network analysis of differentially methylated genes was performed to determine potential biological pathways showing changes in DNA methylation in CFS. We found an increased abundance of differentially methylated genes related to the immune response, cellular metabolism, and kinase activity. Genes associated with immune cell regulation, the largest coordinated enrichment of differentially methylated pathways, showed hypomethylation within promoters and other gene regulatory elements in CFS. These data are consistent with evidence of multisystem dysregulation in CFS and implicate the involvement of DNA modifications in CFS pathology.

Reconfigurable microfluidics with integrated aptasensors for monitoring intercellular communication

We report the development of a microsystem integrating anti-TNF-α aptasensors with vacuum-actuatable microfluidic devices that may be used to monitor intercellular communications. Actuatable chambers were used to expose to mitogen a group of ~600 cells while not stimulating another group of monocytes only 600 μm away. Co-localizing groups of cells with miniature 300 μm diameter aptamer-modified electrodes enabled monitoring of TNF-α release from each group independently. The microsystem allowed observation of the sequence of events that included 1) mitogenic activation of the first group of monocytes to produce TNF-α, 2) diffusion of TNF-α to the location of the second group of cells and 3) activation of the second group of cells resulting in the production of TNF-α by these cells. Thus, we were able to experimentally verify reciprocal paracrine crosstalk between the two groups of cells secreting the same signalling molecule. Given the prevalence of such cellular communications during injury, cancer or immune response and the dearth of available monitoring techniques, the microsystem described here is envisioned to have significant impact on cell biology.

Basal inflammation and innate immune response in chronic multisite musculoskeletal pain

Dysregulation of the immune system may play a role in chronic pain, although study findings are inconsistent. This cross-sectional study examined whether basal inflammatory markers and the innate immune response are associated with the presence and severity of chronic multisite musculoskeletal pain. Data were used on 1632 subjects of the Netherlands Study of Depression and Anxiety. The Chronic Pain Grade questionnaire was used to determine the presence and severity of chronic multisite musculoskeletal pain. Subjects were categorized in a chronic multisite musculoskeletal pain group (n=754) and a control group (n=878). Blood levels of the basal inflammatory markers C-reactive protein, interleukin-6, and tumor necrosis factor-alpha were determined. To obtain a measure of the innate immune response, 13 inflammatory markers were assessed after lipopolysaccharide (LPS) stimulation in a subsample (n=707). Subjects with chronic multisite musculoskeletal pain showed elevated levels of basal inflammatory markers compared with controls, but statistical significance was lost after adjustment for lifestyle and disease variables. For some LPS-stimulated inflammatory markers, we did find elevated levels in subjects with chronic multisite musculoskeletal pain both before and after adjustment for covariates. Pain severity was not associated with inflammation within chronic pain subjects. An enhanced innate immune response in chronic multisite musculoskeletal pain may be examined as a potential biomarker for the onset or perpetuation of chronic pain.

In myalgic encephalomyelitis/chronic fatigue syndrome, increased autoimmune activity against 5-HT is associated with immuno-inflammatory pathways and bacterial translocation

BACKGROUND

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is accompanied by activation of immuno-inflammatory pathways, increased bacterial translocation and autoimmune responses to serotonin (5-HT). Inflammation is known to damage 5-HT neurons while bacterial translocation may drive autoimmune responses. This study has been carried out to examine the autoimmune responses to 5-HT in ME/CFS in relation to inflammation and bacterial translocation.

METHODS

We examined 5-HT antibodies in 117 patients with ME/CFS (diagnosed according to the centers for disease control and prevention criteria, CDC) as compared with 43 patients suffering from chronic fatigue (CF) but not fulfilling the CDC criteria and 35 normal controls. Plasma interleukin-1 (IL-1), tumor necrosis factor (TNF)α, neopterin and the IgA responses to Gram-negative bacteria were measured. Severity of physio-somatic symptoms was measured using the fibromyalgia and chronic fatigue syndrome rating scale (FF scale).

RESULTS

The incidence of positive autoimmune activity against 5-HT was significantly higher (p<0.001) in ME/CFS (61.5%) than in patients with CF (13.9%) and controls (5.7%). ME/CFS patients with 5-HT autoimmune activity displayed higher TNFα, IL-1 and neopterin and increased IgA responses against LPS of commensal bacteria than those without 5-HT autoimmune activity. Anti-5-HT antibody positivity was significantly associated with increased scores on hyperalgesia, fatigue, neurocognitive and autonomic symptoms, sadness and a flu-like malaise.

DISCUSSION

The results show that, in ME/CFS, increased 5-HT autoimmune activity is associated with activation of immuno-inflammatory pathways and increased bacterial translocation, factors which are known to play a role in the onset of autoimmune reactions. 5-HT autoimmune activity could play a role in the pathophysiology of ME/CFS and the onset of physio-somatic symptoms. These results provide mechanistic support for the notion that ME/CFS is a neuro-immune disorder.

Association of C-reactive protein and interleukin-6 with new-onset fatigue in the Whitehall II prospective cohort study

BACKGROUND

Although basic research on neuroimmune interactions suggests that inflammatory processes may play a role in the development of fatigue, population-based evidence on this association is limited. This study examined whether plasma C-reactive protein (CRP) and interleukin-6 (IL-6), biomarkers of systemic inflammation, predict fatigue onset.

METHOD

The Whitehall II study is a large-scale cohort study conducted in 20 civil service departments in London. Plasma CRP and IL-6 were measured in 4847 non-fatigued participants at phase 3 (1991-1993, aged 39-63 years). Fatigue was assessed using the Vitality subscale of the 36-item Short Form Health Survey (SF-36) at phase 3 and phase 4 (1995-1996).

RESULTS

During a mean follow-up of 3.1 years, 957 new fatigue cases (19.7%) were identified using the pre-established cut-off score of ≤ 50 on the Vitality subscale. CRP values were dichotomized as low (<1.0 mg/l ) or high (≥ 1.0 mg/l) using the Centers for Disease Control/American Heart Association recommendations. Similarly, IL-6 values were also dichotomized as low (<1.5 pg/ml) or high (≥ 1.5 pg/ml). After full adjustment for sociodemographic and biobehavioral covariates, the odds ratios for new-onset fatigue were 1.28 [95% confidence interval (CI) 1.09-1.49, p = 0.003] for high CRP and 1.24 (95% CI 1.06-1.45, p = 0.008) for high IL-6. Similar results were found when CRP and IL-6 were treated as continuous variables.

CONCLUSIONS

Plasma CRP and IL-6 were prospectively associated with new-onset fatigue, supporting the hypothesis that low-grade inflammation has a role in the development of fatigue.

Unique immunologic patterns in fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a clinical syndrome characterized by chronic pain and allodynia. The diagnosis of FM has been one of exclusion as a test to confirm the diagnosis is lacking. Recent data highlight the role of the immune system in FM. Aberrant expressions of immune mediators, such as cytokines, have been linked to the pathogenesis and traits of FM. We therefore determined whether cytokine production by immune cells is altered in FM patients by comparing the cellular responses to mitogenic activators of stimulated blood mononuclear cells of a large number of patients with FM to those of healthy matched individuals.

METHODS

Plasma and peripheral blood mononuclear cells (PBMC) were collected from 110 patients with the clinical diagnosis of FM and 91 healthy donors. Parallel samples of PBMC were cultured overnight in medium alone or in the presence of mitogenic activators; PHA or PMA in combination with ionomycin. The cytokine concentrations of IFN-γ, IL-5, IL-6, IL-8, IL-10, MIP-1β , MCP-1, and MIP1-α in plasma as well as in cultured supernatants were determined using a multiplex immunoassay using bead array technology.

RESULTS

Cytokine levels of stimulated PBMC cultures of healthy control subjects were significantly increased as compared to matched non-stimulated PBMC cultures. In contrast, the concentrations of most cytokines were lower in stimulated samples from patients with FM compared to controls. The decreases of cytokine concentrations in patients samples ranged from 1.5-fold for MIP-1β to 10.2-fold for IL-6 in PHA challenges. In PMA challenges, we observed 1.8 to 4-fold decreases in the concentrations of cytokines in patient samples.

CONCLUSION

The cytokine responses to mitogenic activators of PBMC isolated from patients with FM were significantly lower than those of healthy individuals, implying that cell-mediated immunity is impaired in FM patients. This novel cytokine assay reveals unique and valuable immunologic traits, which, when combined with clinical patterns, can offer a diagnostic methodology in FM.

Inflammatory fatigue and sickness behaviour - lessons for the diagnosis and management of chronic fatigue syndrome

Persistent and severe fatigue is a common part of the presentation of a diverse range of disease processes. There is a growing body of evidence indicating a common inflammatory pathophysiology underlying many conditions where fatigue is a primary patient concern, including chronic fatigue syndrome. This review explores current models of how inflammatory mediators act on the central nervous system to produce fatigue and sickness behaviour, and the commonality of these processes in conditions as diverse as surgical trauma, infection, various cancers, inflammatory bowel disease, connective tissue diseases and autoimmune diseases. We also discuss evidence indicating chronic fatigue syndrome may have important pathophysiological similarities with cytokine mediated sickness behaviour, and what lessons can be applied from sickness behaviour to chronic fatigue syndrome with regards to the diagnosis and management.

Cytokine expression profiles of immune imbalance in post-mononucleosis chronic fatigue

Background

As Chronic Fatigue Syndrome (CFS) has been known to follow Epstein-Bar virus (EBV) and other systemic infections; our objective was to describe differences in immune activation in post-infective CFS (PI-CFS) patients and recovered controls. We studied 301 adolescents prospectively over 24 months following the diagnosis of monospot-positive infectious mononucleosis (IM). We found an incidence of CFS at 6, 12 and 24 months of 13%, 7% and 4% respectively.

Methods

Using chemiluminescent imaging we measured the concentrations of IL-1a, 1b, 2, 4, 5, 6, 8, 10, 12 (p70), 13, 15, 17 and 23, IFN-γ, TNF-α and TNF-β in duplicate plasma samples available in bio-bank from 9 PI-CFS subjects and 12 recovered controls at 24 months post-infection.

Results

Standard comparative analysis indicated significant differences in IL-8 and 23 across subject groups. In constructing a linear classification model IL-6, 8 and 23 were selected by two different statistical approaches as discriminating features, with IL-1a, IL-2 and IFN-γ also selected in one model or the other. This supported an assignment accuracy of better than 80% at a confidence level of 0.95 into PI-CFS versus recovered controls.

Conclusion

These results suggest that co-expression patterns in as few as 5 cytokines associated with Th17 function may hold promise as a tool for the diagnosis of post-infectious CFS.

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.

Evidence for inflammation and activation of cell-mediated immunity in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): increased interleukin-1, tumor necrosis factor-α, PMN-elastase, lysozyme and neopterin

BACKGROUND

There is evidence that inflammatory pathways and cell-mediated immunity (CMI) play an important role in the pathophysiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Activation of inflammatory and CMI pathways, including increased levels of cytokines, is known to induce fatigue and somatic symptoms. Given the broad spectrum inflammatory state in ME/CFS, the aim of this study was to examine whether inflammatory and CMI biomarkers are increased in individuals with ME/CFS.

METHODS

In this study we therefore measured plasma interleukin-(IL)1, tumor necrosis factor (TNF)α, and PMN-elastase, and serum neopterin and lysozyme in 107 patients with ME/CFS, 37 patients with chronic fatigue (CF), and 20 normal controls. The severity of ME/CFS was measured with the Fibromyalgia and Chronic Fatigue Syndrome (FF) Rating Scale.

RESULTS

Serum IL-1, TNFα, neopterin and lysozyme are significantly higher in patients with ME/CFS than in controls and CF patients. Plasma PMN-elastase is significantly higher in patients with ME/CFS than in controls and CF patients and higher in the latter than in controls. Increased IL-1 and TNFα are significantly correlated with fatigue, sadness, autonomic symptoms, and a flu-like malaise; neopterin is correlated with fatigue, autonomic symptoms, and a flu-like malaise; and increased PMN-elastase is correlated with concentration difficulties, failing memory and a subjective experience of infection.

CONCLUSIONS

The findings show that ME/CFS is characterized by low-grade inflammation and activation of CMI. The results suggest that characteristic symptoms of ME/CFS, such as fatigue, autonomic symptoms and a flu-like malaise, may be caused by inflammatory mediators, e.g. IL-1 and TNFα.

Systematic review with meta-analysis: cytokines in fibromyalgia syndrome

BACKGROUND

To perform a systematic review and meta-analysis on cytokine levels in patients with fibromyalgia syndrome (FMS).

METHODS

Through December 2010 we systematically reviewed the databases PubMed, MEDLINE, and PsycINFO and screened the reference lists of 22 review articles for suitable original articles. Original articles investigating cytokines in patients with FMS were included. Data were extracted by two independent authors. Differences of the cytokine levels of FMS patients and controls were summarized by standardized mean differences (SMD) using a random effects model. Study quality was assessed applying methodological scores: modified Center of Evidence Based Medicine, Newcastle-Ottawa-Scale, and Würzburg Methodological Quality Score.

RESULTS

Twenty-five articles were included investigating 1255 FMS patients and 800 healthy controls. Data of 13/25 studies entered meta-analysis. The overall methodological quality of studies was low. The results of the majority of studies were not comparable because methods, investigated material, and investigated target cytokines differed. Systematic review of the selected 25 articles revealed that FMS patients had higher serum levels of interleukin (IL)-1 receptor antagonist, IL-6, and IL-8, and higher plasma levels of IL-8. Meta-analysis of eligible studies showed that FMS patients had higher plasma IL-6 levels compared to controls (SMD = -0.34 [-0.64, -0.03] 95% CI; p = 0.03). The majority of investigated cytokines were not different between patients and controls.

CONCLUSIONS

The pathophysiological role of cytokines in FMS is still unclear. Studies of higher quality and with higher numbers of subjects are needed.

Aquatic exercise improves the monocyte pro- and anti-inflammatory cytokine production balance in fibromyalgia patients

Current hypotheses of the etiology of fibromyalgia (FM) include inflammatory disorders. We evaluated the effect of a pool-aquatic exercise program (8 months, two weekly 60-min sessions) on the inflammatory cytokine production by isolated monocytes, and on the serum concentration of C-reactive protein (CRP), in a group of female FM patients. Monocytes from FM patients released more IL-1β, TNFα, IL-6, and IL-10 than those from an age-matched control group of healthy women (HW). This inflammatory disorder in FM women was also manifested by high circulating concentrations of CRP. Increased IL-6 with a concomitant decreased TNFα spontaneous release was found after 4 months (midway through) of the exercise program. At the end of the program (8 months), monocytes from FM patients showed diminished spontaneous production of pro-/anti-inflammatory cytokines, with a similar spontaneous release of IL-1β and IL-6 to that of HW, but a lower production of TNFα and higher of IL-10. Lipopolysaccharide-induced production of IL-1β, TNFα, IL-6, and IL-10 also decreased at the end of the exercise program, although IL-10 remained higher than HW. The anti-inflammatory effect of the exercise program was also corroborated by a decrease in the circulating CRP concentration. Exercise also improved the health-related quality of life of FM patients.

Pathophysiology of fibromyalgia: a comparison with the tension-type headache, a localized pain syndrome

Fibromyalgia (FM) is thought to occur because of the combination of interactions among neurotransmitters, such as neuropeptide Y (NPY), stressors, hormones, cytokines, and both the immune and sympathetic nervous systems. The aim of this study was to evaluate serum concentrations of cytokines, antipolymer antibodies (APA), and NPY in 51 patients with FM, 25 with tension-type headache (TTH), and 15 healthy controls. Serum concentrations of eight different cytokines, APA and NPY, were measured. Interleukin (IL)-1RA, IL-6, IL-10, and tumor necrosis factor-alpha were higher in serum of FM patients compared with TTH patients and a significant correlation between IL-10 and Fibromyalgia Impact Questionnaire score was observed. There was a significant difference between FM and TTH versus controls in NPY levels, but not in APA levels. Cytokines and NPY take part in pain modulation and even if they are altered in FM they cannot be considered as measurable biomarkers of disease.

Cytokines across the night in chronic fatigue syndrome with and without fibromyalgia

The symptoms of chronic fatigue syndrome (CFS) are consistent with cytokine dysregulation. This has led to the hypothesis of immune dysregulation as the cause of this illness. To further test this hypothesis, we did repeated blood sampling for cytokines while patients and matched healthy controls slept in the sleep lab. Because no one method for assaying cytokines is acknowledged to be better than another, we assayed for protein in serum, message in peripheral blood lymphocytes (PBLs), and function in resting and stimulated PBLs. We found no evidence of proinflammatory cytokine upregulation. Instead, in line with some of our earlier studies, we did find some evidence to support a role for an increase in interleukin-10, an anti-inflammatory cytokine. Although the changes were small, they may contribute to the common complaint in CFS patients of disrupted sleep.

Severity of symptom flare after moderate exercise is linked to cytokine activity in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) patients often report symptom flare (SF) for >24 h after moderate exercise (post-ex). We hypothesized that SF is linked to increases in circulating cytokines and CD40 Ligand (CD40L). In 19 CFS patients and 17 controls, mental and physical fatigue and pain symptom ratings were obtained together with serum for 11 cytokines and CD40L before and at 0.5, 8, 24, and 48 h post-ex. Before exercise, CFS had lower CD40L (p<.05) but similar cytokines versus controls. In subgroups based on SF at 48 h, high SF patients (n=11) increased in IL-1beta, IL-12, IL-6, IL-8, IL-10, and IL-13 (p<.05) 8 h post-ex. Low SF patients (n=8) showed post-ex decreases in IL-10, IL-13, and CD40L, and controls decreased in IL-10, CD40L, and TNFalpha (p<.05). Thus, in CFS, cytokine activity may vary directly with SF, which may explain prior inconsistent findings.

Preliminary Evidence of Increased Pain and Elevated Cytokines in Fibromyalgia Patients with Defective Growth Hormone Response to Exercise

Mounting evidence suggests fibromyalgia (FM) symptoms are influenced by dysfunction of the hypothalamic-pituitary-hormonal axes (HPHA) and the immune response system. The predominant FM symptoms of widespread pain, fatigue, sleep disturbance, depression, stiffness and exercise intolerance are related to abnormal levels of growth hormone (GH) and are reminiscent of "sickness behavior"; a syndrome initiated by the production of pro-inflammatory cytokines in response to various stressors. Cognizant of the reciprocal relationship between HPHA activity and the immune response system, we hypothesized that serum cytokine levels and FM symptom severity would be higher in FM patients with defective growth hormone response to exhaustive exercise compared to those without. Outpatients with FM (n = 165) underwent a Modified Balke Treadmill Protocol and GH response to exhaustive exercise was measured in peripheral blood samples. Levels of IL-1α, IL-1β, IL-1RA, IL-6, IL-8, IL-10, and TNF-α were measured from stored serum on a subset of 24 participants (12 with and 12 without normal GH response to exhaustive exercise). FM symptom severity was assessed using the Fibromyalgia Impact Questionnaire (FIQ), number of tender points and cumulative myalgic scores. GH dysfunction was associated with increased pain scores on the FIQ (p = 0.024), a greater number of tender points (p = 0.014), higher myalgic scores (p = 0.001) and higher pre-exercise levels of inflammatory cytokines IL-1α (p = 0.021), IL-6 (p = 0.012), and IL-8 (p = 0.004). These results suggest that a defective growth hormone response to exercise may be associated with increased levels of blood cytokines and pain severity in FM patients.

Integrated review of the association of cytokines with fibromyalgia and fibromyalgia core symptoms

Fibromyalgia (FMS) is a chronic widespread pain (CWP) and fatigue syndrome that affects three to six million adults in the United States. Core symptoms of FMS include pain, fatigue, and mood and sleep disturbances. To date, consensus has not been reached among researchers regarding the pathogenesis of FMS nor the specific role of cytokine activation on the neuroendocrine-immune response patterns in persons with FMS. The purpose of this article is to describe and synthesize the results of research studies focused on the relationship between cytokines and FMS and among cytokines and core symptoms of FMS. There is some support in the literature for relationships among FMS symptoms and cytokines; however, there are discrepant findings related to whether proinflammatory and anti-inflammatory cytokines are elevated or reduced in persons with FMS and whether their levels correlate with the core symptoms of this disorder. Although the use of cytokine biomarkers must be considered exploratory at this time due to the lack of consistent empirical findings, biobehavioral research focused on understanding the relationship of FMS with cytokines may lead to a better understanding of this complex syndrome. This knowledge may ultimately contribute to the development of interventions for symptom management that address not only the symptom manifestation but also a biological mediator of symptoms.

Low plasma levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNFalpha), and vascular endothelial growth factor (VEGF) in patients with alpha1-antitrypsin deficiency-related fibromyalgia

Abnormalities in blood inflammatory markers have been associated with clinical manifestations and the pathogenesis of the fibromyalgia syndrome (FMS); a relationship between inherited alpha1-antitrypsin deficiency (AATD) and FMS has also been recently raised. In this study, plasma levels of inflammatory markers in FMS patients with and without AATD have been investigated. Blood samples from 138 age-matched females (79 FMS) and 59 general population (GP), with normal MM [n = 82 (59.4%)] and with MS, MZ, SZ, and ZZ AATD genotypes [n = 56 (40.6%)], were analyzed by ELISA for monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNFalpha), soluble TNFalpha receptors I and II, interleukin-8, and vascular endothelial growth factor (VEGF). Plasma levels of MCP-1, VEGF, and TNFalpha were significantly lower in FMS and GP subjects with AATD compared with those with normal MM-AAT genotypes. Moreover, plasma levels of MCP-1, VEGF, and TNFalpha were lower in AATD subjects with FMS than in those without FMS (P = 0.000, 0.000, and 0.046, respectively). No statistical differences were found for the other substances measured. Furthermore, a logistic regression model based on plasma MCP-1 cutoff value of <or=130 pg/ml allowed us to discriminate between FMS and GP subjects with a sensitivity of about 93% and a specificity of 79%. Low plasma levels of MCP-1, VEGF, and TNFalpha are related to AATD, although more markedly in FMS patients. Thus, hypotheses considering FMS as an inflammatory condition related to high plasma levels of inflammatory biomarkers cannot be supported.

Prospective association between C-reactive protein and fatigue in the coronary artery risk development in young adults study

BACKGROUND

Fatigue is highly prevalent and causes serious disruption in quality of life. Although the underlying biological mechanism is unknown, increases in inflammation have been implicated. This prospective study examined the association between C-reactive protein (CRP), a biomarker of systemic inflammation, and fatigue 5 years later.

METHODS

The Coronary Artery Risk Development in Young Adults (CARDIA) study is a population-based longitudinal study conducted in four U.S. cities. Highly sensitive CRP concentration and fatigue were measured in 2983 African American and white adults at both year 15 (2000-2001, ages 33-45 years) and year 20 (2005-2006) examinations. Fatigue was assessed using the vitality subscale of the 12-item Short Form Health Survey.

RESULTS

Plasma CRP concentration at baseline (i.e., CARDIA year 15) was a significant predictor of fatigue level 5 years later (unadjusted beta = .126, p < .001). After adjustment for potential confounders, this association remained significant (adjusted beta = .044, p = .033). Additionally, baseline CRP independently predicted fatigue in the subgroup of participants without medical comorbidity (adjusted beta = .051, p = .039). Fatigue was associated with a persistent elevation of CRP at both examinations but not with a transient elevation of CRP at only one of the examinations.

CONCLUSIONS

This is the first study to demonstrate a prospective association between an inflammatory marker and fatigue in a general population. Furthermore, the association between low-grade systemic inflammation and fatigue seems primarily driven by persistent immune activation and not explained by the presence or development of medical comorbidity.

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.

Status of immune mediators in fibromyalgia

Fibromyalgia (FM) is a form of nonarticular rheumatism characterized by long-term (> 3 months) and widespread musculoskeletal pain. However, the biophysiology of FM has remained elusive, and the treatment remains mainly empirical. There are numerous hypotheses about the pathophysiology of chronic widespread pain and FM; one includes a possible role of cytokines. Cytokines play a role in diverse clinical processes and phenomena such as fatigue, fever, sleep, pain, stress, and aching. Cytokines related to acute or repetitive tissue injuries may be responsible for long-term activation of spinal cord glia and dorsal horn neurons, thus resulting in central sensitization. Pain, stiffness, and depression in FM could be associated with some signs of inflammatory response system activation. Illumination of the pathophysiologic secrets of FM will result in more effective treatment regimens. We review the role of immune mediators in the pathophysiology of FM.

May genetic factors in fibromyalgia help to identify patients with differentially altered frequencies of immune cells?

There is common agreement that fibromyalgia (FM) is an extremely heterogeneous entity. Patients differ in their clinical symptoms, endocrine and immune parameters. In this study we evaluated endocrine and immunological features of distinct subsets of FM patients. In contrast to previous attempts to identify subsets of FM patients, based solely on their psychological and cognitive features, herein we propose to separate FM patients by genetic features. Allelic expression of the polymorphic promoter region of the serotonin transporter (5-HTTLPR) was analysed as a relevant genetic factor for FM. Seventy-five patients meeting the American College of Rheumatology criteria and 27 healthy age-matched controls participated in this study. All controls and FM patients were submitted to genotyping of 5-HTTLPR. Twenty-seven FM patients, who were able to discontinue hypnotic, sedative or psychotropic prescription medications for at least 2 weeks, were then subdivided into L (homozygote LL) or S groups (genotypes LS and SS). They were evaluated for salivary cortisol levels, absolute number of leucocyte subpopulations, including natural killer (NK) cells and activated T and B lymphocytes. Both groups presented decreased cortisol levels, more intense in the L group, increased all B lymphocytes subsets and reduced CD4+CD25high T lymphocytes. The L group had increased CD4+CD25low activated T lymphocytes, while the S group displayed elevated CD4+ human leucocyte antigen D-related (HLA-DR)+ activated T lymphocytes and decreased NK cells. We demonstrate that genetic factors may help to identify FM individuals with differentially altered frequencies of immune cells.

Mode of action of cytokines on nociceptive neurons

Cytokines are pluripotent soluble proteins secreted by immune and glial cells and are key elements in the induction and maintenance of pain. They are categorized as pro-inflammatory cytokines, which are mostly algesic, and anti-inflammatory cytokines, which have analgesic properties. Progress has been made in understanding the mechanisms underlying the action of cytokines in pain. To date, several direct and indirect pathways are known that link cytokines with nociception or hyperalgesia. Cytokines may act via specific cytokine receptors inducing downstream signal transduction cascades, which then modulate the function of other receptors like the ionotropic glutamate receptor, the transient vanilloid receptors, or sodium channels. This receptor activation, either through amplification of the inflammatory reaction, or through direct modulation of ion channel currents, then results in pain sensation. Following up on results from animal experiments, cytokine profiles have recently been investigated in human pain states. An imbalance of pro- and anti-inflammatory cytokine expression may be of importance for individual pain susceptibility. Individual cytokine profiles may be of diagnostic importance in chronic pain states, and, in the future, might guide the choice of treatment.

Association of peripheral inflammatory markers with chronic fatigue in a population-based sample

Alterations in the innate immune response may contribute to the pathogenesis of chronic fatigue syndrome (CFS). However, studies have been limited by small sample sizes, use of patients from tertiary care settings, inappropriate selection of controls, and failure to control for confounding demographic, medical and behavioral factors independently associated with immune activity. It is also not known whether specific symptoms account for observed associations between CFS and the innate immune response. To address these limitations, the current study examined plasma concentrations of high-sensitivity c-reactive protein (hs-CRP), white blood cell count (WBC) and a combined inflammation factor in a large population-based sample. Log-transformed mean plasma concentrations of hs-CRP were increased in subjects with CFS (n=102) and in subjects with unwellness symptoms that did not meet diagnostic criteria for CFS (defined as "insufficient fatigue" [ISF]) (n=240) when compared to subjects who were well (n=115). Log transformed WBC was increased in ISF and was increased at a trend level in CFS. The combined inflammation factor was increased in both CFS and ISF. Subjects with CFS and ISF did not differ on any of the inflammation measures. In the entire subject population, the physical component summary score (PCS), but not the mental component summary score (MCS), from the Medical Outcomes Study Short Form-36 (SF-36) was negatively associated with each of the inflammation measures. Depressive symptoms were also associated with increased log hs-CRP. After adjustment for age, sex, race, location of residence, BMI, depressive status and immune-modulating medications, subjects classified as ISF continued to demonstrate increased log hs-CRP, WBC and elevations on the inflammation factor when compared to well controls; however, associations between CFS and log hs-CRP and the inflammation factor were no longer statistically significant. After adjustment, PCS score also remained independently associated with each of the inflammation measures. These findings support a role for innate immune activation in unexplained fatigue and unwellness, but do not suggest that immune activation is specific to CFS.

[Cytokine regulation and pain. Results of experimental and clinical research]

Cytokines are soluble peptides and proteins that are predominantly produced and secreted by immune cells. In numerous animal experiments the endogenous increase or application of exogenous pro-inflammatory cytokines is associated with pain behavior. In turn, cytokine inhibitors reduce such pain behavior in inflammatory and neuropathic pain models. Several clinical studies point out that cytokines are also important in different human pain states. Several chronic pain syndromes are associated with systemic pro-inflammatory cytokine profiles. In some pain syndromes these pro-inflammatory profiles are accompanied by a lack of analgesic anti-inflammatory cytokines. Numerous case reports and open clinical studies, but also some controlled trials show successful analgesic treatment using cytokine inhibitors. The following review article summarizes the main data of animal experiments and clinical trials concerning the role of cytokines in pain and the potential importance of cytokine modulation in pain treatment.

Correlation between cytokines and anxious-depressive symptoms in patients with fibromyalgia

OBJECTIVE

To establish the influence of cytokines on anxious-depressive manifestations in fibromyalgia (FM) patients.

MATERIAL AND METHOD

The study comprised 56 women (50.5±7.8 years) with FM and 32 healthy female controls (39.65±9.24 years). Psychiatric symptoms were analyzed using the Hamilton Depression Rating Scale (HDRS) and the Hamilton Anxiety Rating Scale (HARS), while pain was assessed by means of a Visual Analog Scale (VAS). Proinflammatory cytokines IL-6, IL-8, IL-10, and TNFα were assayed in serum using the Luminex-xMAP method. The statistical analysis was carried out using the SSPS statistical package.

RESULTS

IL-8 values were significantly lower (p=.013) in patients than in controls. No differences were observed among IL-6, IL-10, and TNFα levels. When comparing cytokine levels with patient age, we observed a significant reduction in IL-6, IL-8, and TNFα in older patients. The values of these cytokines showed no relationship to the anxious-depressive symptoms.

CONCLUSIONS

In our series no differences in serum cytokines were seen between patients with FM and controls, with the exception of a reduction in IL-8 among patients with FM, and which could be attributed to the older age of these patients.

[Etiology and pathophysiology of fibromyalgia syndrome and chronic widespread pain]

OBJECTIVE

To write a systematic review on the etiology and pathophysiology of the fibromyalgia syndrome (FMS) and of chronic widespread pain (CWP).

METHODS

An interdisciplinary level-3 guideline (i.e. systematic literature search and assessment, logic analysis, formal consensus procedure) for the diagnosis and therapy of FMS was created in cooperation with 10 medical and psychological societies and 2 patient self-help organizations. A literature search was performed covering all available review articles on the etiology and pathophysiology of FMS and CWP using the Cochrane Collaboration Reviews (1993-12/2006), Medline (1980-2006), PsychInfo (1966-12/2006), and Scopus (1980-12/2006). For the assignment of evidence classes the system of the Oxford Centre for Evidence-Based Medicine was applied. Consensus was achieved by a multi-step nominal group procedure.

RESULTS

FMS aggregates in families (evidence level 2c). Physical and psychological stress at the workplace are risk factors for the development of CWP and FMS. Affective disorders are risk factors for the development and maintenance of FMS. Operant learning mechanisms and sensitization are risk factors for the chronification of FMS (evidence levels 2b). Several factors are associated with the pathophysiology of FMS, but the causal relationship is unclear. This includes alterations of central pain pathways, hyporeactivity of the hypothalamus-pituitary-adrenal axis, increased systemic pro-inflammatory and reduced anti-inflammatory cytokine profiles and disturbances in the dopaminergic and serotonergic systems.

CONCLUSIONS

FMS is the common final product of various etiological factors and pathophysiological mechanisms.

Normal mouse kidneys contain activated and CD3+CD4- CD8- double-negative T lymphocytes with a distinct TCR repertoire

Healthy liver, intestine, lung, and skin harbor resident lymphocytes with conventional and unconventional phenotypes. Lymphocytes also have been detected in healthy mice kidneys; however, these cells have not been well studied and have been largely overlooked. To better characterize the intra-renal lymphocytes, we extensively perfused C57BL/6J mice with PBS and then isolated mononuclear cells for flow cytometry analysis. We observed T cells, B cells, and NK cells in normal mice kidneys after extensive perfusion. Approximately 50% of kidney T lymphocytes expressed intermediate levels of CD3 (CD3int T cells). Similar to liver and lung, a high percentage of unconventional CD3+CD4(-)CD8(-) double-negative T cells was observed in normal mice kidneys, from which 11% expressed B220 antigen. Unlike the spleen and blood, the classic CD4+ and CD8+ T lymphocytes in the kidney had a high proportion of activated CD69+ and effector/memory CD44- CD62L ligand phenotypes. Also, a small percentage of CD4+CD25+forkhead box p3+ and NKT cells was observed in perfused and exanguinated kidneys. In addition, a distinct TCR repertoire was found on intra-renal conventional and unconventional T cells compared with those from the spleen. Finally, after 24 h of renal ischemia reperfusion injury (IRI), increased production of cytokines IFN-gamma and TNF-alpha by CD4+ and CD8+ T cells, isolated from perfused kidneys, was observed. These data suggest that some of these cells harbored in the kidney could be implicated in the immune response of the IRI pathogenic process.

Glucocorticoid sensitivity in fibromyalgia patients: decreased expression of corticosteroid receptors and glucocorticoid-induced leucine zipper

In fibromyalgia (FM) patients, differences in glucocorticoid receptor (GR) affinity and disturbances associated with loss of hypothalamic-pituitary-adrenal (HPA) axis resiliency have been observed. Based on these studies, we investigated whether FM would be associated with abnormalities in glucocorticoid (GC) sensitivity. Salivary and blood samples were collected from 27 FM patients and 29 healthy controls. Total plasma cortisol and salivary free cortisol were quantified by ELISA and time-resolved fluorescence immunoassay, respectively. GR sensitivity to dexamethasone was evaluated through IL-6 inhibition in stimulated whole blood. The corticosteroid receptors, GR alpha and mineralocorticoid receptor, as well as the glucocorticoid-induced leucine zipper (GILZ) and the FK506 binding protein 5 mRNA expression were assessed in peripheral blood mononuclear cells (PBMCs) by real-time RT-PCR. Furthermore, the corticosteroid receptors were analysed for polymorphism. We observed lower basal plasma cortisol levels (borderline statistical significance) and a lower expression of corticosteroid receptors and GILZ in FM patients when compared to healthy controls. The MR rs5522 (I180V) minor allele was found more often in FM patients than in controls and this variant was recently associated with a mild loss of receptor function. The lower GR and MR expression and possibly the reduced MR function may be associated with an impaired function of the HPA axis in these patients which, compounded by lower anti-inflammatory mediators, may sustain some of symptoms that contribute to the clinical picture of the syndrome.

Cytokine regulation in animal models of neuropathic pain and in human diseases

Cytokines are soluble proteins secreted mainly by immune cells and are key players in the induction and maintenance of pain. Pro-inflammatory cytokines are mostly algesic, while anti-inflammatory cytokines have analgesic properties. After the role of cytokines was shown in diverse animal models of pain, interest arose in the systemic and local regulation of cytokines in human pain states. Most clinical studies give evidence for an imbalance between pro- and anti-inflammatory cytokines in neuropathic and other pain states with pronounced pro-inflammatory cytokine profiles. Anti-cytokine treatment gives encouraging preliminary results and supports the notion of a crucial role of cytokines also in human pain states. Further research is needed for a better understanding of the mechanisms linking altered cytokine profiles to the sensation of pain.

Effects of balneotherapy on serum IL-1, PGE2 and LTB4 levels in fibromyalgia patients

The purpose of this study was to investigate the clinical effects of balneotherapy in the treatment of Fibromyalgia Syndrome (FMS) and to determine if balneotherapy influences serum levels of inflammation markers, IL-1, PGE2 and LTB4. 24 primary fibromyalgia female patients diagnosed according to American College of Rheumatology criteria were included to the study. Their ages ranged between 33 and 55 years. FMS patients were randomly assigned in two groups as, group 1 (n = 12) and group 2 (n = 12). Group 1 received 20-min bathing, once in a day for five days per week. Patients participated in the study for 3 weeks (total of 15 sessions) in Denizli. Group 2 did not receive balneotherapy. FMS patients were evaluated by tenderness measurements (tender point count and algometry), Visual Analogue Scale, Beck's Depression Index, Fibromyalgia Impact Questionnaire. Ten healthy women recruited group three as the controls. Serum PGE2, LTB4 and IL1-alpha levels were measured in all three groups. The biochemical measurements and clinical assessments were performed before and at the end of general period of therapy. Statistically significant alterations in algometric score, Visual Analogue score, Beck's Depression Index and PGE2 levels (P < 0.001), numbers of tender points (P < 0.01) and Fibromyalgia Impact Questionnaire score (P < 0.05) were found after the balneotherapy between group 1 and 2. Mean PGE2 level of FMS patients were higher compared to healthy control group (P < 0.0001) and decreased after the treatment period, only in group 1 (P < 0.05). As in the group 2 and 3, detectable IL-1 and LTB4 measurements were insufficient, statistical analysis was performed, only in group 1. After balneotherapy IL-1 and LTB4 significantly decreased in group 1 (P < 0.05). In conclusion, balneotherapy is an effective choice of treatment in patients with FMS relieving the clinical symptoms, and possibly influencing the inflammatory mediators.