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

Inflammation, Autoimmunity, and Infection in Fibromyalgia: A Narrative Review

Fibromyalgia (FM) is a chronic disease characterized by widespread musculoskeletal pain of unknown etiology. The condition is commonly associated with other symptoms, including fatigue, sleep disturbances, cognitive impairment, and depression. For this reason, FM is also referred to as FM syndrome. The nature of the pain is defined as nociplastic according to the latest international classification and is characterized by altered nervous sensitization both centrally and peripherally. Psychosocial conditions have traditionally been considered critical in the genesis of FM. However, recent studies in animal models and humans have provided new evidence in favor of an inflammatory and/or autoimmune pathogenesis. In support of this hypothesis are epidemiological data of an increased female prevalence, similar to that of autoimmune diseases, and the frequent association with immune-mediated inflammatory disorders. In addition, the observation of an increased incidence of this condition during long COVID revived the hypothesis of an infectious pathogenesis. This narrative review will, therefore, discuss the evidence supporting the immune-mediated pathogenesis of FM in light of the most current data available in the literature.

Melatonin as a Coadjuvant in the Treatment of Patients with Fibromyalgia

Fibromyalgia syndrome (FMS) is a chronic widespread pain syndrome that is accompanied by fatigue, sleep disturbances, anxiety, depression, lack of concentration, and neurocognitive impairment. As the currently available drugs are not completely successful against these symptoms and frequently have several side effects, many scientists have taken on the task of looking for nonpharmacological remedies. Many of the FMS-related symptoms have been suggested to be associated with an altered pattern of endogenous melatonin. Melatonin is involved in the regulation of several physiological processes, including circadian rhythms, pain, mood, and oxidative as well as immunomodulatory balance. Preliminary clinical studies have propounded that the administration of different doses of melatonin to patients with FMS can reduce pain levels and ameliorate mood and sleep disturbances. Moreover, the total antioxidant capacity, 6-sulfatoxymelatonin and urinary cortisol levels, and other biological parameters improve after the ingestion of melatonin. Recent investigations have proposed a pathophysiological relationship between mitochondrial dysfunction, oxidative stress, and FMS by looking at certain proteins involved in mitochondrial homeostasis according to the etiopathogenesis of this syndrome. These improvements exert positive effects on the quality of life of FMS patients, suggesting that the use of melatonin as a coadjuvant may be a successful strategy for the management of this syndrome.

Unbiased immune profiling reveals a natural killer cell-peripheral nerve axis in fibromyalgia

ABSTRACT

The pathophysiology of fibromyalgia syndrome (FMS) remains elusive, leading to a lack of objective diagnostic criteria and targeted treatment. We globally evaluated immune system changes in FMS by conducting multiparametric flow cytometry analyses of peripheral blood mononuclear cells and identified a natural killer (NK) cell decrease in patients with FMS. Circulating NK cells in FMS were exhausted yet activated, evidenced by lower surface expression of CD16, CD96, and CD226 and more CD107a and TIGIT. These NK cells were hyperresponsive, with increased CCL4 production and expression of CD107a when co-cultured with human leukocyte antigen null target cells. Genetic and transcriptomic pathway analyses identified significant enrichment of cell activation pathways in FMS driven by NK cells. Skin biopsies showed increased expression of NK activation ligand, unique long 16-binding protein, on subepidermal nerves of patients FMS and the presence of NK cells near peripheral nerves. Collectively, our results suggest that chronic activation and redistribution of circulating NK cells to the peripheral nerves contribute to the immunopathology associated with FMS.

Effectiveness of Pain Neuroscience Education in Patients with Fibromyalgia: A Systematic Review and Meta-Analysis

PURPOSE

To assess the effects of pain neuroscience education (PNE) on patients with fibromyalgia (FM) in terms of pain intensity, fibromyalgia impact, anxiety, and pain catastrophizing.

METHODS

A systematic review and meta-analysis of randomized controlled trials was conducted. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated with RStudio software for relevant outcomes and were pooled in a meta-analysis using the random effects model.

RESULTS

A total of 8 studies were included. The meta-analysis showed statistically significant differences in the pain intensity with a moderate clinical effect in 7 studies in the post-intervention assessment (SMD:-0.76; 95% CI:-1.33- -0.19; p < 0.05) with evidence of significant heterogeneity (p < 0.05, I2=92%) but not in fibromyalgia impact, anxiety, and pain catastrophizing (p > 0.05). Regarding the follow-up assessment, only the fibromyalgia impact showed significant improvements with a very small clinical effect in 9 studies (SMD:-0.44; 95% CI:-0.73- -0.14; p < 0.05) with evidence of significant heterogeneity (p < 0.05, I2 = 80%). Applying a sensitivity analysis with the PNE face-to-face interventions, the meta-analysis showed a significant decrease of pain intensity with a moderate clinical effect at post-intervention and follow-up without evidence of significant heterogeneity (p < 0.05, I2=10%).

CONCLUSIONS

There is low quality evidence that in patients with FM, PNE can decrease the pain intensity post-intervention and also the fibromyalgia impact in the follow-up. However, it appears that PNE showed no effect on anxiety and pain catastrophizing.

Higher Risk for Sjögren's Syndrome in Patients With Fibromyalgia: A Nationwide Population-Based Cohort Study

Objectives

Clinically, associations have been observed between Sjögren's syndrome and fibromyalgia. Nonetheless, population-based evidence evaluating the risk of Sjögren's syndrome in fibromyalgia patients is lacking. The main purpose of this retrospective cohort study was to determine the association between fibromyalgia and subsequent development of Sjögren's syndrome.

Methods

This retrospective cohort study extracted data from the Longitudinal Health Insurance Database (LHID) of the Taiwan National Health Insurance (NHI). During 2000-2012, patients with newly-diagnosed fibromyalgia (International Classification of Diseases, Ninth Revision, Clinical Modification code 729.1) were defined as the exposure cohort. Age- and gender-matched individuals without fibromyalgia were used as the comparison cohort. The adjusted hazard ratios (aHR) for the occurrence of Sjögren's syndrome in those with fibromyalgia were evaluated along with stratified analyses of different subgroups.

Results

Of the 149,706 subjects whose data were extracted from the LHID, 74,853 subjects had coded fibromyalgia and 74,853 control subjects were without fibromyalgia. Compared to the control group, patients with fibromyalgia had an aHR of 2.00 (95% Confidence Interval [CI], 1.52-2.61) for developing Sjögren's syndrome. In fibromyalgia patients aged 20-49 years, the aHR for future Sjögren's syndrome was 3.07 (95% CI, 1.92-4.89).

Conclusion

Patients with fibromyalgia, both males and females, have a higher risk for developing Sjögren's syndrome than those without fibromyalgia, especially those aged 20-49 years. While managing patients, clinicians should be aware of the bidirectional association between the two diseases, which helps to understand the impact of the association on disease activity and diagnosis.

Gene Expression Profiling in Fibromyalgia Indicates an Autoimmune Origin of the Disease and Opens New Avenues for Targeted Therapy

Fibromyalgia is a chronic disorder characterized by widespread pain and by several non-pain symptoms. Autoimmunity, small fiber neuropathy and neuroinflammation have been suggested to be involved in the pathogenesis of the disease. We have investigated the gene expression profile in peripheral blood mononuclear cells obtained from ten patients and ten healthy subjects. Of the 545,500 transcripts analyzed, 1673 resulted modulated in fibromyalgic patients. The majority of these genes are involved in biological processes and pathways linked to the clinical manifestations of the disease. Moreover, genes involved in immunological pathways connected to interleukin-17 and to Type I interferon signatures were also modulated, suggesting that autoimmunity plays a role in the disease. We then aimed at identifying differentially expressed Long non-coding RNAs (LncRNAs) functionally connected to modulated genes both directly and via microRNA targeting. Only two LncRNAs of the 298 found modulated in patients, were able to target the most highly connected genes in the fibromyalgia interactome, suggesting their involvement in crucial gene regulation. Our gene expression data were confirmed by real time PCR, by autoantibody testing, detection of soluble mediators and Th-17 polarization in a validation cohort of 50 patients. Our results indicate that genetic and epigenetic mechanisms as well as autoimmunity play a pivotal role in the pathogenesis of fibromyalgia.

T Cell Subpopulations in the Physiopathology of Fibromyalgia: Evidence and Perspectives

Fibromyalgia is one of the most important “rheumatic” disorders, after osteoarthritis. The etiology of the disease is still not clear. At the moment, the most defined pathological mechanism is the alteration of central pain pathways, and emotional conditions can trigger or worsen symptoms. Increasing evidence supports the role of mast cells in maintaining pain conditions such as musculoskeletal pain and central sensitization. Importantly, mast cells can mediate microglia activation through the production of proinflammatory cytokines such as IL-1β, IL-6, and TNFα. In addition, levels of chemokines and proinflammatory cytokines are enhanced in serum and could contribute to inflammation at systemic level. Despite the well-characterized relationship between the nervous system and inflammation, the mechanism that links the different pathological features of fibromyalgia, including stress-related manifestations, central sensitization, and dysregulation of the innate and adaptive immune responses is largely unknown. This review aims to provide an overview of the current understanding of the role of adaptive immune cells, in particular T cells, in the physiopathology of fibromyalgia. It also aims at linking the latest advances emerging from basic science to envisage new perspectives to explain the role of T cells in interconnecting the psychological, neurological, and inflammatory symptoms of fibromyalgia.

Neuroimmunology: What Role for Autoimmunity, Neuroinflammation, and Small Fiber Neuropathy in Fibromyalgia, Chronic Fatigue Syndrome, and Adverse Events after Human Papillomavirus Vaccination?

Fibromyalgia is a disorder characterized by chronic widespread pain and non-pain symptoms, such as fatigue, dysautonomia, and cognitive and sleep disturbances. Its pathogenesis and treatment continue to be the subject of debate. We highlight the role of three mechanisms-autoimmunity, neuroinflammation, and small fiber neuropathy-in the pathogenesis of the disease. These mechanisms are shown to be closely interlinked (also on a molecular level), and the review considers the implementation of this relationship in the search for therapeutic options. We also pay attention to chronic fatigue syndrome, which overlaps with fibromyalgia, and propose a concept of "autoimmune hypothalamopathy" for its pathogenesis. Finally, we analyze the molecular mechanisms underlying the neuroinflammatory background in the development of adverse events following HPV vaccination and suggesting neuroinflammation, which could exacerbate the development of symptoms following HPV vaccination (though this is hotly debated), as a model for fibromyalgia pathogenesis.

Mast Cells, Neuroinflammation and Pain in Fibromyalgia Syndrome

Fibromyalgia Syndrome (FMS) is a disorder of chronic, generalized muscular pain, accompanied by sleep disturbances, fatigue and cognitive dysfunction. There is no definitive pathogenesis except for altered central pain pathways. We previously reported increased serum levels of the neuropeptides substance P (SP) and its structural analogue hemokinin-1 (HK-1) together with the pro-inflammatory cytokines IL-6 and TNF in FMS patients as compared to sedentary controls. We hypothesize that thalamic mast cells contribute to inflammation and pain, by releasing neuro-sensitizing molecules that include histamine, IL-1β, IL-6 and TNF, as well as calcitonin-gene related peptide (CGRP), HK-1 and SP. These molecules could either stimulate thalamic nociceptive neurons directly, or via stimulation of microglia in the diencephalon. As a result, inhibiting mast cell stimulation could be used as a novel approach for reducing pain and the symptoms of FMS.

Effects of aquatic physiotherapy or health education program in women with fibromyalgia: a randomized clinical trial

Background: Different treatments have been proposed for Fibromyalgia, but only few studies have compared their effects on multiples outcomes over time. Objective: The objective of this study was to investigate the effects of aquatic physiotherapy (AP) or a health education program (HEP) in a sample of women with Fibromyalgia (FM). Methods: Forty-six women with FM, aged between 25 and 60 years old, whose BMI was less than 30, were assigned to either AP (27 women) or HEP (19 women) groups in a blind randomized clinical trial lasting eleven weeks. Pain (McGill Pain questionnaire), fatigue (Piper Fatigue Scale-Revised), functional capability (Fibromyalgia Impact questionnaire), anxiety (Beck Anxiety Inventory), depression (Beck Depression Inventory) and quality of sleep (Pittsburgh Sleep Quality Index) data were collected at baseline, after six weeks and post intervention. Two-factor mixed-model analysis of variance (ANOVAs) were used to examine the effects of the treatment on each outcome variable. Results: The AP and HEP interventions showed statistically significant within-group differences on all outcome measures except reducing the pain. Between-group differences was statistically significant only for impact of FM on the participant's life [F_(1.82,80.41) = 31,99; p ≤ 0.01] indicating that patients receiving HEP experienced a greater decrease in FIQ than those treated with AP. Conclusion: The findings do not allow to affirm that one intervention is superior to the other for the treatment of people with FM. Future studies should investigate whether the combination of HEP and PA can be effective and long-lasting.

Effects of a health education program on cytokines and cortisol levels in fibromyalgia patients: a randomized controlled trial

BACKGROUND

Fibromyalgia (FM) is a syndrome characterized by widespread chronic pain associated to other symptoms, such as: fatigue, anxiety, depression and sleep disorders. Health education programs (HEP) have emerged as good non-pharmacological strategies to treat it. However, it is still not clear if the benefits are only subjective, or it has also objective impacts on immune and or neuroendocrine systems.

METHODS

Fifty-eight fibromyalgia women were randomly allocated in experimental group (n = 27) or control group (n = 31). The experimental group was submitted to HEP treatment for 11 weeks, while control group did not receive intervention at the same period. All data were collected at zero and 11th week by a blinded researcher. The statistical analysis were made in GraphPad Prism software (version 5.0) with significant level adjusted for α = 0.05.

RESULTS

Forty-four patients concluded the full study, 21 in the experimental group and 23 in the control group. Intragroup and intergroup analysis revealed that treatment induced significant increases of IL-4 plasma levels, anti-inflammatory cytokine/inflammatory cytokine ratio (AC/IC ratio), salivary cortisol levels, in addition to significant decreases on FIQ scores. Intergroup variation analyses revealed also significant increases of IL-10 plasma levels.

CONCLUSION

The results presented suggest that this kind of HEP could induce subjective and objective changes (immune and neuroendocrine), that could explain, at least in part the improvement of fibromyalgia patient's health status. (Clinical Trial Registration Number - ReBEC - RBR-5tdnbr).

Clinical profile of patients with fibromyalgia syndrome

Abstract Introduction: The new diagnostic criteria for fibromyalgia (FM) include the presence of chronic, widespread pain associated with other symptoms such as fatigue, sleep disturbance, anxiety and depression. All these symptoms should be considered when thinking and clinical decision making of physiotherapists dealing with FM. However, it is clear that the other symptoms that accompany the pain are often neglected. Objective: To measure the levels of fatigue, sleep disturbances, anxiety and depression in patients with FM and compare them to levels found in healthy controls. Methods: Forty-six women diagnosed with FM and 30 healthy controls participated in the study. The levels of each of the symptoms were assessed by four validated questionnaires in Brazil (Piper Fatigue Scale - Revised, Pittsburgh Sleep Quality Index, Beck Anxiety Inventory and the Beck Depression Inventory). Statistical analysis was performed using GraphPad Prism software and all tests used a significance level of 5% (α = 0.05). Results: FM patients had significantly elevated levels of fatigue (p = 0.0005), sleep disturbances (p = 0.003), anxiety (p = 0.0012) and depression (p = 0.0003) compared to healthy controls. Symptoms fatigue and depression correlated strongly and positively with one another and with other symptoms evaluated. Conclusion: The other symptoms that comprise the clinical picture of FM need be considered not only in order to recover the health of patients, but above all in an attempt to preserve it and promote it.

Fibromyalgia syndrome in need of effective treatments

Fibromyalgia syndrome (FMS) is a chronic, idiopathic condition of widespread musculoskeletal pain, affecting primarily women. It is clinically characterized by chronic, nonarticular pain and a heightened response to pressure along with sleep disturbances, fatigue, bowel and bladder abnormalities, and cognitive dysfunction. The diagnostic criteria have changed repeatedly, and there is neither a definitive pathogenesis nor reliable diagnostic or prognostic biomarkers. Clinical and laboratory studies have provided evidence of altered central pain pathways. Recent evidence suggests the involvement of neuroinflammation with stress peptides triggering the release of neurosenzitizing mediators. The management of FMS requires a multidimensional approach including patient education, behavioral therapy, exercise, and pain management. Here we review recent data on the pathogenesis and propose new directions for research and treatment.

Serotonin mediated immunoregulation and neural functions: Complicity in the aetiology of autism spectrum disorders

Serotonergic system has long been implicated in the aetiology of autism spectrum disorders (ASD), since platelet hyperserotonemia is consistently observed in a subset of autistic patients, who respond well to selective serotonin reuptake inhibitors. Apart from being a neurotransmitter, serotonin functions as a neurotrophic factor directing brain development and as an immunoregulator modulating immune responses. Serotonin transporter (SERT) regulates serotonin level in lymphoid tissues to ensure its proper functioning in innate and adaptive responses. Immunological molecules such as cytokines in turn regulate the transcription and activity of SERT. Dysregulation of serotonergic system could trigger signalling cascades that affect normal neural-immune interactions culminating in neurodevelopmental and neural connectivity defects precipitating behavioural abnormalities, or the disease phenotypes. Therefore, we suggest that a better understanding of the cross talk between serotonergic genes, immune systems and serotonergic neurotransmission will open wider avenues to develop pharmacological leads for addressing the core ASD behavioural deficits.

Immunomodulatory effects mediated by serotonin

Serotonin (5-HT) induces concentration-dependent metabolic effects in diverse cell types, including neurons, entherochromaffin cells, adipocytes, pancreatic beta-cells, fibroblasts, smooth muscle cells, epithelial cells, and leukocytes. Three classes of genes regulating 5-HT function are constitutively expressed or induced in these cells: (a) membrane proteins that regulate the response to 5-HT, such as SERT, 5HTR-GPCR, and the 5HT₃-ion channels; (b) downstream signaling transduction proteins; and (c) enzymes controlling 5-HT metabolism, such as IDO and MAO, which can generate biologically active catabolites, including melatonin, kynurenines, and kynurenamines. This review covers the clinical and experimental mechanisms involved in 5-HT-induced immunomodulation. These mechanisms are cell-specific and depend on the expression of serotonergic components in immune cells. Consequently, 5-HT can modulate several immunological events, such as chemotaxis, leukocyte activation, proliferation, cytokine secretion, anergy, and apoptosis. The effects of 5-HT on immune cells may be relevant in the clinical outcome of pathologies with an inflammatory component. Major depression, fibromyalgia, Alzheimer disease, psoriasis, arthritis, allergies, and asthma are all associated with changes in the serotonergic system associated with leukocytes. Thus, pharmacological regulation of the serotonergic system may modulate immune function and provide therapeutic alternatives for these diseases.

Identification of a microRNA signature for the diagnosis of fibromyalgia

Background

Diagnosis of fibromyalgia (FM), a chronic musculoskeletal pain syndrome characterized by generalized body pain, hyperalgesia and other functional and emotional comorbidities, is a challenging process hindered by symptom heterogeneity and clinical overlap with other disorders. No objective diagnostic method exists at present. The aim of this study was to identify changes in miRNA expression profiles (miRNome) of these patients for the development of a quantitative diagnostic method of FM. In addition, knowledge of FM patient miRNomes should lead to a deeper understanding of the etiology and/or symptom severity of this complex disease.

Methods

Genome-wide expression profiling of miRNAs was assessed in Peripheral Blood Mononuclear Cells (PBMCs) of FM patients (N=11) and population-age-matched controls (N=10) using human v16-miRbase 3D-Gene microarrays (Toray Industries, Japan). Selected miRNAs from the screen were further validated by RT-qPCR. Participating patients were long term sufferers (over 10 years) diagnosed by more than one specialist under 1990 American College of Rheumatology criteria.

Results

Microarray analysis of FM patient PBMCs evidenced a marked downregulation of hsa-miR223-3p, hsa-miR451a, hsa-miR338-3p, hsa-miR143-3p, hsa-miR145-5p and hsa-miR-21-5p (4-fold or more). All but the mildest inhibited miRNA, hsa-miR-21-5p, were validated by RT-qPCR. Globally, 20% of the miRNAs analyzed (233/1212) showed downregulation of at least 2-fold in patients. This might indicate a general de-regulation of the miRNA synthetic pathway in FM. No significant correlations between miRNA inhibition and FM cardinal symptoms could be identified. However, the patient with the lowest score for mental fatigue coincided with the mildest inhibition in four of the five miRNAs associated with the FM-group.

Conclusions

We propose a signature of five strikingly downregulated miRNAs (hsa-miR223-3p, hsa-miR451a, hsa-miR338-3p, hsa-miR143-3p and hsa-miR145-5p) to be used as biomarkers of FM. Validation in larger study groups is required before the results can be transferred to the clinic.

The phenotypic and genetic signatures of common musculoskeletal pain conditions

Musculoskeletal pain conditions, such as fibromyalgia and low back pain, tend to coexist in affected individuals and are characterized by a report of pain greater than expected based on the results of a standard physical evaluation. The pathophysiology of these conditions is largely unknown, we lack biological markers for accurate diagnosis, and conventional therapeutics have limited effectiveness. Growing evidence suggests that chronic pain conditions are associated with both physical and psychological triggers, which initiate pain amplification and psychological distress; thus, susceptibility is dictated by complex interactions between genetic and environmental factors. Herein, we review phenotypic and genetic markers of common musculoskeletal pain conditions, selected based on their association with musculoskeletal pain in previous research. The phenotypic markers of greatest interest include measures of pain amplification and 'psychological' measures (such as emotional distress, somatic awareness, psychosocial stress and catastrophizing). Genetic polymorphisms reproducibly linked with musculoskeletal pain are found in genes contributing to serotonergic and adrenergic pathways. Elucidation of the biological mechanisms by which these markers contribute to the perception of pain in these patients will enable the development of novel effective drugs and methodologies that permit better diagnoses and approaches to personalized medicine.

A dialogue between the immune system and brain, spoken in the language of serotonin

Neuropsychiatric disorders have long been linked to both immune system activation and alterations in serotonin (5-HT) signaling. In the CNS, the contributions of 5-HT modulate a broad range of targets, most notably, hypothalamic, limbic and cortical circuits linked to the control of mood and mood disorders. In the periphery, many are aware of the production and actions of 5-HT in the gut but are unaware that the molecule and its receptors are also present in the immune system where evidence suggests they contribute to the both innate and adaptive responses. In addition, there is clear evidence that the immune system communicates to the brain via both humoral and neuronal mechanisms, and that CNS 5-HT neurons are a direct or indirect target for these actions. Following a brief primer on the immune system, we describe our current understanding of the synthesis, release, and actions of 5-HT in modulating immune function, including the expression of 5-HT biosynthetic enzymes, receptors, and transporters that are typically studied with respect to the roles in the CNS. We then orient our presentation to recent findings that pro-inflammatory cytokines can modulate CNS 5-HT signaling, leading to a conceptualization that among the many roles of 5-HT in the body is an integrated physiological and behavioral response to inflammatory events and pathogens. From this perspective, altered 5-HT/immune conversations are likely to contribute to risk for neurobehavioral disorders historically linked to compromised 5-HT function or ameliorated by 5-HT targeted medications, including depression and anxiety disorders, obsessive-compulsive disorder (OCD), and autism. Our review raises the question as to whether genetic variation impacting 5-HT signaling genes may contribute to maladaptive behavior as much through perturbed immune system modulation as through altered brain mechanisms. Conversely, targeting the immune system for therapeutic development may provide an important opportunity to treat mental illness.