Fibromyalgia and Irritable Bowel Syndrome Interaction: A Possible Role for Gut Microbiota and Gut-Brain Axis

Gut Microbiota: A Modulator and Therapeutic Target for Chronic Pain

Chronic pain is a prevalent condition, impacting nearly one-fifth of the global population. Despite the availability of various clinical treatments, each comes with inherent limitations, and few offer a complete cure, resulting in a significant social and economic burden. Therefore, it is important to determine the pathogenesis and causes of chronic pain. Numerous studies have shown a close link between the intestinal microflora and chronic pain. The gut microbiota can exert their effects on chronic pain through both central and peripheral mechanisms and is able to communicate with the brain through its own components or metabolites. They also can regulate chronic pain by affecting pro- and anti-inflammatory cells. This review is aimed at reviewing the connection between gut flora and different types of chronic pain, including visceral pain, neuropathic pain, inflammatory pain, musculoskeletal pain, migraine, and chronic cancer pain; exploring the central and peripheral mechanisms of the influence of gut flora on chronic pain; and attempting to provide novel treatment options for chronic pain, that is, the gut microbiota can be regulated by probiotics, fecal microbial transplantation, and natural products to treat chronic pain. By examining the intricate relationship between gut flora and chronic pain, the review sought to pave the way for new treatment strategies that target the gut microbiota, offering hope for more effective pain management.

HMGB1 derived from macrophages and enteric glial cells contributes to the butyrate-induced colonic hypersensitivity in mice

High mobility group box1 (HMGB1), a nuclear protein, once acetylated by histone acetyltransferase, is released into the extracellular space, and causes pain signals, thereby contributing to pathological pain. Repeated intracolonic administration of butyrate, known to inhibit histone deacetylase (HDAC), produces colonic hypersensitivity in rodents, being widely used as models for irritable bowel syndrome (IBS). Thus, we asked whether HMGB1 would participate in the butyrate-induced colonic hypersensitivity in mice, and analyzed the underlying mechanisms. Repeated butyrate treatment caused colonic hypersensitivity to distension and intraluminal sulfide, a functional enhancer of Cav3.2 channels, in mice, which was prevented by repeated treatment with an anti-HMGB1-neutralizing antibody, thrombomodulin alfa (TMα) capable of causing thrombin-dependent degradation of HMGB1, antagonists for RAGE, TLR4 and CXCR4, membrane receptors of HMGB1, liposomal clodronate, a macrophage depletor, and ethyl pyruvate capable of inhibiting HMGB1 release from macrophages. Butyrate treatment increased the number of Iba1-positive macrophages, but not S100B-positive enteric glial cells (EGCs), and the rate of cytosolic/whole cell HMGB1 levels in both types of cells in the colonic mucosa. In macrophage-like RAW264.7 cells and EGC-like CRL-2690 cells, butyrate as well as trichostatin A, a well-known HDAC inhibitor, at the same concentrations that increased histone acetylation, evoked cytoplasmic translocation and extracellular release of nuclear HMGB1. Together, butyrate is considered to cause HMGB1 release from macrophages and EGCs most probably by inhibiting HDAC, resulting in colonic hypersensitivity in mice. HMGB1 and its membrane receptors might serve as drug targets for colonic hypersensitivity in IBS patients.

Predictors of response to a dietary intervention in patients with irritable bowel syndrome

BACKGROUND

Different diets have emerged as potential therapeutic options for patients with irritable bowel syndrome (IBS).

OBJECTIVE

To identify predictors of improvement after a low-FODMAP, low-starch and low-sucrose diet among patients with IBS.

METHODS

We performed a descriptive cross-sectional study including patients with IBS according to Rome IV criteria undertaking a social-media based program with a two-week dietary intervention. Patients completed an online survey before and after the intervention including the presence of intestinal and extra-intestinal symptoms, the IBS-SSS (irritable bowel syndrome symptoms severity scale) and the PHQ-9 (patient health questionnaire-9). Clinical improvement was defined as a decrease of at least 50% in IBS-SSS post dietary intervention. Variables associated with symptomatic response were identified with logistic regression analysis. A clinical score to predict response was created and tested with a with a receiver operating characteristic (ROC) curve analysis.

RESULTS

A total of 3583 patients with IBS were included. Mean IBS-SSS before and after dietary intervention was 295.5±52.32 and 240±48.66, respectively (p=0.01); 1178 (32.8%) patients showed clinical improvement. A mean basal IBS-SSS >400 (OR 3.04), chronic headache (OR 1.96), and chronic fatigue (OR 1.81) were significantly associated with symptomatic response. Patients with arthralgia (OR 0.41) and/or fibromyalgia (OR 0.33) were less likely to improve. Each variable received the following individuals scores: IBS-SSS >400: +2, chronic headache: +1.5, chronic fatigue: +1, arthralgia: -1, and fibromyalgia: -1. The ROC curve analysis of the proposed score showed an area under the curve of 0.72 (95% CI 0.69-0.76). A score ≥3 had a sensitivity of 72.64% and specificity of 60.56% for predicting symptomatic improvement.

CONCLUSIONS

There are clinical variables that could serve as reliable predictors of response to a low-FODMAP, low-sucrose, low-starch diet among patients with IBS. Further research is needed to understand the link between the presence of extra-intestinal symptoms and clinical improvement after dietary interventions for IBS.

Journey of Hope for Patients with Fibromyalgia: From Diagnosis to Self-Management-A Qualitative Study

BACKGROUND/OBJECTIVES

Fibromyalgia syndrome (FMS) is a chronic, debilitating condition characterized by widespread pain, fatigue, and psychological distress. There is a lack of qualitative studies on the unique experiences of patients with FMS in Arab countries, particularly through social media. Despite the availability of diagnostic criteria, diagnosing and managing patients remains challenging. This study aimed to describe the experiences of patients with FMS in Arab countries, their understanding of the illness, and perceptions of treatment.

METHODS

A qualitative study was conducted using a content analysis of patients' narratives published in a supportive group, describing their experiences with fibromyalgia. The dataset included 2305 quotes from 192 main posts and 2113 comments collected between 2019 and 2024.

RESULTS

The analysis of the posts and associated comments revealed six main themes: patients' experiences with the syndrome, symptoms, searching for a doctor, pharmacological management, self-management, and the impact of fibromyalgia and peer support. Most posts and comments focused on patients' experiences with self-management approaches and coping strategies, highlighting significant noncompliance with therapeutic modalities. Factors influencing patients' experiences and decisions included their relationship with physicians, medication side effects, personal fears, and physical and mental health.

CONCLUSIONS

Patients with FMS in Arab countries face similar challenges to those in other regions, including physical, psychological, social, and economic impacts. Many patients reject conventional therapeutic management strategies and adopt coping mechanisms to mitigate adverse effects and healthcare costs. The findings suggest that the physician-patient relationship, as well as the physician's knowledge and attitude toward fibromyalgia syndrome, are the cornerstones of gaining patients' trust.

Role of Vitamin D Status and Alterations in Gut Microbiota Metabolism in Fibromyalgia-Associated Chronic Inflammatory Pain

Background/Objectives: Several studies suggest gut microbiota metabolites as important immuno-modulators in inflammatory pain. We aimed to investigate the relationship between vitamin D status and gut dysbiosis markers in fibromyalgia (FM)-associated chronic inflammation. Methods: Blood samples were collected from sixty-eight female FM patients (49.9 ± 12.35 years). Pain intensity was assessed by FIQ-R. The serum levels of the pro-inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17, IFN-γ, as well as those of vitamin D (25(OH)D3) and the kynurenine/tryptophan ratio (Kyn/Trp) were determined by ELISA and HPLC, respectively. The plasma levels of the SCFAs acetate, butyrate, and propionate were detected by GC-MS. Results: A mean FIQ-R score indicated that the patients could be classified as having moderate FM. The mean levels of all cytokines, but IL-6 and IL-1β, were higher than the normal reference values. The highest concentrations of cytokines were observed in patients showing the highest FIQ-R scores and the lowest 25(OH)D3 levels. Deficient levels of acetate were found paralleled by an increase in Kyn/Trp. The highest acetate concentrations were detected in patients with the lowest FIQ-R scores and 25(OH)D3 levels. Significantly negative correlations were found between 25(OH)D3 concentrations and FIQ-R scores (p = 0.007) as well as IL-17 levels (p = 0.002) and between acetate and TNF-α (p = 0.040) as well as FIQ-R scores (p = 0.028), while significantly positive correlations were observed between Kyn/Trp and IL-17 (p = 0.027) as well as IFN-γ (p = 0.003). Conclusions: Our preliminary data suggest that the vitamin D status along with altered gut microbiota metabolism plays a major role in FM-related inflammatory pain. Replication of these findings in a larger cohort is required to provide additional insights.

Lateral periaqueductal gray participate in the regulation of irritable bowel syndrome induced by chronic restraint stress

Irritable bowel syndrome (IBS) is a functional bowel disorder defined by recurrent abdominal pain, coupled with irregular bowel habits and alterations in the frequency as well as the consistency of stool. At present, IBS is considered as a disease of gut-brain interaction, and an increasing number of studies are focusing on the brain-gut axis. However, the brain regions associated with IBS have not been fully studied yet. In this study, we utilized the chronic restraint stress (CRS) model to evoke IBS-like symptoms in mice, which were accompanied by anxiety-like behaviors and hyperalgesia. Through cFOS staining, we observed the activation of the lateral periaqueductal gray (LPAG) in the mice after CRS. By inhibiting the activity of the LPAG through tetanus toxin or chemogenetics, we found that IBS-like symptoms could be relieved, whereas chemogenetic activation of the LPAG induced IBS-like symptoms. Finally, we utilized the classic analgesic drug sufentanil and found that it could alleviate CRS-induced IBS-like symptoms.

Multiple Aspects of Irritable Bowel Syndrome and the Role of the Immune System: An Overview of Systematic Reviews with a Focus on Polyphenols

Irritable bowel syndrome (IBS) is a complex and often debilitating condition that significantly impacts the gastrointestinal system and the overall quality of life of those affected. IBS is characterized by a variety of distressing symptoms, including cramping, abdominal pain, and irregular bowel movements, underlined by an intricate interplay of immune system dysfunction in its pathology. Numerous studies highlight an increased cellular immune response, with elevated levels of proinflammatory cytokines, mucosal alterations due to immune imbalance, and visceral hypersensitivity. Notably, studies indicate increased levels of proinflammatory cytokines, immune imbalances that lead to mucosal changes, and heightened visceral sensitivity. The roles of effector and regulatory T cells are particularly intriguing, as their modification appears to amplify inflammation and may even contribute to autoimmune disorders. This overview of systematic reviews explores the connections between IBS and immune responses, with a focus on immune cell alterations and proliferation of lymphocytes and mast cells in affected individuals. Furthermore, we explore various aspects of IBS management, including its pharmacological approaches. A systematic search of PubMed and Web of Science yielded 676 articles, which were ultimately narrowed down to 9 key studies that met our inclusion criteria. These studies collectively underscore the activation of the immune system with the degranulation of the mast cells in patients with IBS, where the release of inflammatory mediators can compromise intestinal permeability, exacerbating symptoms further. Additionally, we examine the multifaceted management strategies for IBS, emphasizing the potential therapeutic benefits of dietary polyphenols as antioxidants. The present study aims to enhance our understanding of IBS and offer insights into more effective treatment strategies for this challenging condition.

A Systematic Review of the Effect of Polyphenols on Alterations of the Intestinal Microbiota and Shared Bacterial Profiles Between Metabolic Syndrome and Acne

Introduction: Microbiota, composed of micro-organisms like bacteria, viruses, and non-pathogenic fungi, plays a crucial role in digestion, vitamin production, and protection against dangerous microbes. Several factors, including age, diet, alcohol consumption, stress, environmental microorganisms, and therapies (particularly antibiotics), as well as birth and nursing, could modify the microbiota. Recent research has highlighted its alteration and involvement in a various disease, including metabolic syndrome and acne. This systematic review aimed to identify common biomarkers and microbiota alterations shared between metabolic syndrome and acne, and to explore how the potential prebiotic activities of polyphenols may promote intestinal eubiosis. Materials and methods: A comprehensive search in PubMed and EMBASE resulted in 4142 articles, from which nine studies were selected based on specific criteria after removing duplicates and reviewing abstracts and full texts. All studies correlated the microbiota alteration in both pathologies and the activity of polyphenols in metabolic syndrome. Results: This review suggests that acne may be influenced by some of the same microorganisms involved in metabolic syndrome. While the literature highlights the effectiveness of polyphenols in treating metabolic syndrome, no studies have yet demonstrated their specific impact on acne. Conclusions: The research points to the potential benefits of polyphenols in modulating the microbiota, which could be relevant for individuals with metabolic syndrome. However, due to the limited data available, it was not possible to establish a direct correlation between metabolic syndrome and acne.

Adapted Low-FODMAP Diet in IBS Patients with and without Fibromyalgia: Long-Term Adherence and Outcomes

BACKGROUND/OBJECTIVES

A low-FODMAPs Diet (LFD) is considered a "second line" dietary strategy for irritable bowel syndrome (IBS) but, after a period of strict restriction of all FODMAP foods, it has to be adapted and tailored to each patient (AdLFD). Fibromyalgia often coexists with IBS in up to 65% of cases. Our aims were to evaluate if comorbid fibromyalgia influenced the long-term clinical outcomes and adherence to an AdLFD in IBS patients.

METHODS

IBS patients with or without fibromyalgia who had started an AdLFD were enrolled. Patients had been evaluated before starting the LFD (T0). After a mean follow-up of 62.5 ± 22.7 months (T1), they were re-evaluated using questionnaires on disease severity, bowel habits, psychological status, and adherence to AdLFD.

RESULTS

In total, 51 IBS patients entered the study. Nineteen of them had comorbid fibromyalgia. Thirty patients reported a reduction in symptom severity at T1 in comparison with T0. Despite some slight differences in single IBS Symptom Severity Score items, comorbid fibromyalgia did not influence the IBS-SSS total score at T1. Patients with comorbid fibromyalgia showed a higher Hospital Anxiety and Depression Scale (HADS) score at baseline. A total of 44 patients showed good long-term adherence to the AdLFD. All patients improved their HADS score and had long-term adherence to the AdLFD.

CONCLUSIONS

Comorbid fibromyalgia showed only a slight influence on long-term outcomes of an AdLFD on IBS symptoms, without affecting the relief of global symptoms. No influence on long-term adherence to AdLFD was detected. Hence, this approach can be taken into account in fibromyalgia patients for a nonpharmacological management of IBS symptoms. However, multicentric studies on larger samples would be welcome in the future.

Bidirectional Two-Sample Mendelian Randomization Analysis Reveals Causal Associations Between Modifiable Risk Factors and Fibromyalgia

Introduction

This study aims to investigate the potential causal effects of modifiable risk factors on Fibromyalgia (FM).

Methods

Genetic variants associated with 34 exposure factors were obtained from Genome-wide association studies (GWAS). Summary statistics for FM were acquired from the FinnGen consortium. Bidirectional Mendelian randomization (MR) analysis was conducted between all exposures and outcomes. The inverse-variance weighted (IVW) method was employed as the primary estimation technique. Heterogeneity and pleiotropy were assessed using MR-PRESSO global test, the weighted median, Cochran's Q statistic and MR-Egger.

Results

Depression (OR=2.087, 95% CI: 1.466-2.971), alcohol consumption (OR=1.489, 95% CI: 1.094-2.028), body fat percentage (OR=1.524, 95% CI: 1.153-2.013) and body mass index (BMI) (OR=1.542, 95% CI: 1.271-1.872) were associated with an increased risk of FM among genetically susceptible individuals. Conversely, higher education level (OR=0.404, 95% CI: 0.297-0.549), longer years of education (OR=0.489, 95% CI: 0.290-0.825) and higher household income (OR=0.328, 95% CI: 0.215-0.502) were protective against FM. Additionally, rheumatoid arthritis (OR=1.138, 95% CI: 1.061-1.221) and ankylosing spondylitis (OR=1.079, 95% CI: 1.021-1.140) were identified as important risk factors for FM.

Conclusion

This MR study unveiled a complex causal relationship between modifiable risk factors and FM. Psychosocial factors significantly increase the odds of FM, while obesity and some autoimmune diseases that frequently coexist with FM demonstrate causal associations. Additionally, lifestyle habits such as alcohol consumption are causally related to FM. Further investigation is needed to determine whether risk factors contribute to the pathogenesis of FM through mechanisms involving central sensitization, inflammatory, and hyperalgesia. This study enhances our understanding of the factors that drive FM onset and progression, offering valuable insights for future targeted prevention and treatment strategies.

Nociplastic pain mechanisms and toll-like receptors as promising targets for its management

ABSTRACT

Nociplastic pain, characterized by abnormal pain processing without an identifiable organic cause, affects a significant portion of the global population. Unfortunately, current pharmacological treatments for this condition often prove ineffective, prompting the need to explore new potential targets for inducing analgesic effects in patients with nociplastic pain. In this context, toll-like receptors (TLRs), known for their role in the immune response to infections, represent promising opportunities for pharmacological intervention because they play a relevant role in both the development and maintenance of pain. Although TLRs have been extensively studied in neuropathic and inflammatory pain, their specific contributions to nociplastic pain remain less clear, demanding further investigation. This review consolidates current evidence on the connection between TLRs and nociplastic pain, with a specific focus on prevalent conditions like fibromyalgia, stress-induced pain, sleep deprivation-related pain, and irritable bowel syndrome. In addition, we explore the association between nociplastic pain and psychiatric comorbidities, proposing that modulating TLRs can potentially alleviate both pain syndromes and related psychiatric disorders. Finally, we discuss the potential sex differences in TLR signaling, considering the higher prevalence of nociplastic pain among women. Altogether, this review aims to shed light on nociplastic pain, its underlying mechanisms, and its intriguing relationship with TLR signaling pathways, ultimately framing the potential therapeutic role of TLRs in addressing this challenging condition.

Macrophages and Gut Barrier Function: Guardians of Gastrointestinal Health in Post-Inflammatory and Post-Infection Responses

The gut barrier is essential for protection against pathogens and maintaining homeostasis. Macrophages are key players in the immune system, are indispensable for intestinal health, and contribute to immune defense and repair mechanisms. Understanding the multifaceted roles of macrophages can provide critical insights into maintaining and restoring gastrointestinal (GI) health. This review explores the essential role of macrophages in maintaining the gut barrier function and their contribution to post-inflammatory and post-infectious responses in the gut. Macrophages significantly contribute to gut barrier integrity through epithelial repair, immune modulation, and interactions with gut microbiota. They demonstrate active plasticity by switching phenotypes to resolve inflammation, facilitate tissue repair, and regulate microbial populations following an infection or inflammation. In addition, tissue-resident (M2) and infiltration (M1) macrophages convert to each other in gut problems such as IBS and IBD via major signaling pathways mediated by NF-κB, JAK/STAT, PI3K/AKT, MAPK, Toll-like receptors, and specific microRNAs such as miR-155, miR-29, miR-146a, and miR-199, which may be good targets for new therapeutic approaches. Future research should focus on elucidating the detailed molecular mechanisms and developing personalized therapeutic approaches to fully harness the potential of macrophages to maintain and restore intestinal permeability and gut health.

Review of the Patient Burden and Therapeutic Landscape of Irritable Bowel Syndrome with Constipation in the United States

Irritable bowel syndrome (IBS) is a common disorder of the gut-brain axis. IBS with constipation (IBS-C) accounts for approximately one-third of IBS cases and is associated with substantial burden of illness and decreased quality of life. This narrative review provides an overview of the current and upcoming treatment options and disease management for IBS-C from a US perspective and discusses the importance of the relationship between patient and health care provider in diagnosis and treatment. A positive diagnostic strategy for IBS-C is recommended, based on clinical history, physical examination, and minimal laboratory tests. An effective communication strategy between patients and health care professionals is essential to ensure early diagnosis and reduce both health care costs and overall disease burden. Treatment typically begins with lifestyle interventions and nonpharmacologic options, such as dietary interventions, fiber supplements, and osmotic laxatives. In patients with inadequate response to these therapies, 4 currently available therapies (lubiprostone, linaclotide, plecanatide, and tenapanor) approved by the US Food and Drug Administration may relieve IBS-C symptoms. These agents are generally well tolerated and efficacious in improving IBS-C symptoms, including constipation and abdominal pain. In patients with persistent abdominal pain and/or psychological symptoms, brain-gut behavioral therapy or neuromodulator therapy may be beneficial.

The Role of the Microbiota in the Pathogenesis and Treatment of Atopic Dermatitis-A Literature Review

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a high prevalence worldwide. AD pathogenesis is complex and consists of immune system dysregulation and impaired skin barrier, influenced by genetic and environmental factors. The purpose of the review is to show the complex interplay between atopic dermatitis and the microbiota. Human microbiota plays an important role in AD pathogenesis and the course of the disease. Dysbiosis is an important factor contributing to the development of atopic diseases, including atopic dermatitis. The gut microbiota can influence the composition of the skin microbiota, strengthening the skin barrier and regulating the immune response via the involvement of bacterial metabolites, particularly short-chain fatty acids, in signaling pathways of the gut-skin axis. AD can be modulated by antibiotic intake, dietary adjustments, hygiene, and living conditions. One of the promising strategies for modulating the course of AD is probiotics. This review offers a summary of how the microbiota influences the development and treatment of AD, highlighting aspects that warrant additional investigation.

Online Questionnaire with Fibromyalgia Patients Shows Negative Correlations between Disease Severity and Adherence to Mediterranean Diet

Fibromyalgia (FM) is a multidimensional disorder in which intense chronic pain is accompanied by a variety of psychophysical symptoms that impose a burden on the patients' quality of life. Despite the efforts and the recent advancement in research, FM pathogenesis and effective treatment remain unknown. Recently, the possible role of dietary patterns and/or components has been gaining attention. The current study aimed to investigate a potential correlation between adherence to the Mediterranean diet (MedDiet) and FM severity in a sample of Italian FM patients. An online survey was designed, composed of customized questions and validated questionnaires with the aim of investigating the intensity and type of pain, the presence of other psychophysical symptoms, the overall impact of FM, general food and lifestyle habits, and adherence to the MedDiet. The collected responses were analyzed for descriptive statistics, linear regression, and propensity score analyses. The results show that, despite considerable use of pharmaceuticals and supplements, FM participants suffered from a high-severity grade disease. However, those with good adherence to the MedDiet experienced a lower pain intensity and overall FM impact. A propensity score analysis indicates a positive influence of the MedDiet against FM severity, thus unveiling the need for well-designed intervention studies to evaluate the therapeutic potential of different dietary patterns.

Role of soluble epoxide hydrolase in pain and depression comorbidity

The coexistence of chronic pain and depression in clinical practice places a substantial social burden and profoundly impacts in patients. Although a clear correlation exists, the underlying mechanism of comorbidity between chronic pain and depression remains elusive. Research conducted in recent decades has uncovered that soluble epoxide hydrolase, a pivotal enzyme in the metabolism of polyunsaturated fatty acids, plays a crucial role in inflammation. Interestingly, this enzyme is intricately linked to the development of both pain and depression. With this understanding, this review aims to summarize the roles of soluble epoxide hydrolase in pain, depression, and their comorbidity. Simultaneously, we will also explore the underlying mechanisms, providing guidance for future research and drug development.

Restrictive Diets in Patients with Fibromyalgia: State of the Art

Around 20-30% of Fibromyalgia patients modify their dietary habits after diagnosis, including avoiding certain food groups such as cereals. In this systematic review, we used the PRISMA guidelines to select the main studies that have evaluated the effectiveness of restrictive diets, including elimination and vegetarian diets, in patients with Fibromyalgia. Data on vegetarian/vegan diets are more consistent than data on elimination diets due to higher quality and better results of the published studies. Although the results are favorable in most of the studies, their heterogenicity and the scarce and low quality of the evidence (small number of patients included, often non-randomized and uncontrolled studies and multiple confounding factors and biases) does not allow for a positive recommendation about these restrictive diets in Fibromyalgia patients. Several factors other than food restriction could influence the symptomatic and functional improvements observed after restrictive diets, such as the placebo effect, weight loss that often occurs, coexistence with gastrointestinal diseases and positive effects of unrestricted foods. We must advance more and improve in our knowledge of the effectiveness of restrictive diets and variables related to them before recommending them systematically to all patients with Fibromyalgia. Randomized, placebo-controlled trials with large sample sizes, longer follow-up periods and standardized outcome measures that explore predictors of dietary response are needed to better understand the relationship between Fibromyalgia and nutrition.

Unraveling the Complex Web of Fibromyalgia: A Narrative Review

Fibromyalgia is a complex and often misunderstood chronic pain disorder. It is characterized by widespread musculoskeletal pain, fatigue, and heightened sensitivity, and has evolved in diagnostic criteria and understanding over the years. Initially met with skepticism, fibromyalgia is now recognized as a global health concern affecting millions of people, with a prevalence transcending demographic boundaries. The clinical features and diagnosis of fibromyalgia encompass a range of symptoms beyond pain, including sleep disturbances and cognitive difficulties. This study emphasizes the importance of a comprehensive evaluation for accurate diagnosis, considering the shift from tender point reliance to a more holistic approach. Etiology and pathophysiology involve genetic predisposition, neurotransmitter dysregulation, central sensitization, and immune system involvement. Risk factors such as gender, age, family history, and comorbid conditions contribute to susceptibility. The impact on quality of life is profound, affecting physical and social aspects, often accompanied by mood disorders. Management approaches include pharmacological interventions, non-pharmacological therapies, lifestyle modifications, and alternative treatments. This study also delves into emerging research, exploring advances in neurobiological understanding, brain imaging, genetic markers, glutamate modulation, cannabinoids, gut microbiome, and digital health tools for fibromyalgia management. Overall, this study provides a nuanced and up-to-date overview of the complexities surrounding fibromyalgia, aiming to enhance understanding and support for individuals grappling with this challenging condition.

Causal association between gut microbiota and fibromyalgia: a Mendelian randomization study

Background

Fibromyalgia (FM) is a syndrome characterized by chronic and widespread musculoskeletal pain. A number of studies have implied a potential association between gut microbiota and FM. However, the casual association between gut microbiota and FM remains unknown.

Method

Mendelian randomization (MR) study was conducted using the summary statistics of genetic variants from the genome-wide association study (GWAS). Inverse variance weighted (IVW), combined with MR-Egger and weighted median were used to investigate the causal association between 119 gut microbiota genera and FM. Sensitivity analyses were performed on the MR results, including heterogeneity test, leave-one-out test and pleiotropy test.

Results

A total of 1,295 single nucleotide polymorphism (SNPs) were selected as instrumental variables (IVs), with no significant heterogeneity and pleiotropy according to the sensitivity analyses. Five gut microbiota genera were found to have significant casual association with FM. Coprococcus2 (OR = 2.317, p-value = 0.005, 95% CI: 1.289-4.167), Eggerthella (OR = 1.897, p-value = 0.001, 95% CI: 1.313-2.741) and Lactobacillus (OR = 1.576, p-value =0.020, 95% CI: 1.073-2.315) can increase the risk of FM. FamillyXIIIUCG001 (OR = 0.528, p-value = 0.038, 95% CI: 0.289-0.964) and Olsenella (OR = 0.747, p-value = 0.050, 95% CI: 0.557-1.000) can decrease the risk of FM.

Conclusion

This MR study found that gut microbiota is casually associated with FM. New insights into the mechanisms of FM mediated by gut microbiota are provided.

Increased gut permeability and bacterial translocation are associated with fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome: implications for disease-related biomarker discovery

Background

There is growing evidence of the significance of gastrointestinal complaints in the impairment of the intestinal mucosal barrier function and inflammation in fibromyalgia (FM) and in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). However, data on intestinal permeability and gut barrier dysfunction in FM and ME/CFS are still limited with conflicting results. This study aimed to assess circulating biomarkers potentially related to intestinal barrier dysfunction and bacterial translocation and their association with self-reported symptoms in these conditions.

Methods

A pilot multicenter, cross-sectional cohort study with consecutive enrolment of 22 patients with FM, 30 with ME/CFS and 26 matched healthy controls. Plasma levels of anti-beta-lactoglobulin antibodies (IgG anti-β-LGB), zonulin-1 (ZO-1), lipopolysaccharides (LPS), soluble CD14 (sCD14) and interleukin-1-beta (IL-1β) were assayed using ELISA. Demographic and clinical characteristics of the participants were recorded using validated self-reported outcome measures. The diagnostic accuracy of each biomarker was assessed using the receiver operating characteristic (ROC) curve analysis.

Results

FM patients had significantly higher levels of anti-β-LGB, ZO-1, LPS, and sCD14 than healthy controls (all P < 0.0001). In ME/CFS patients, levels of anti-β-LGB, ZO-1, LPS, and sCD14 were significantly higher than controls, but lower than in FM (all P < 0.01), while there was no significant difference in IL-1β level. In the FM and ME/CFS cohorts, both anti-β-LGB and ZO-1 correlated significantly with LPS and sCD14 (P < 0.001 for both). In the FM group, both anti-β-LGB and ZO-1 were correlated significantly with physical and mental health components on the SF-36 scale (P < 0.05); whereas IL-1β negatively correlated with the COMPASS-31 score (P < 0.05). In the ME/CFS cohort, ZO-1 was positively correlated with the COMPASS-31 score (P < 0.05). The ROC curve analysis indicated a strong ability of anti-β-LGB, ZO-1, LPS and sCD14 to predictively distinguish between FM and ME/CFS from healthy controls (P < 0.0001).

Conclusion

Biomarkers of intestinal barrier function and inflammation were associated with autonomic dysfunction assessed by COMPASS-31 scores in FM and ME/CFS respectively. Anti-β-LGB antibodies, ZO-1, LPS, and sCD14 may be putative predictors of intestinal barrier dysfunction in these cohorts. Further studies are needed to assess whether these findings are causal and can therefore be applied in clinical practice.