Are the cut-offs of the rheumatoid factor and anti-cyclic citrullinated peptide antibody different to distinguish rheumatoid arthritis from their primary differential diagnoses?

OBJECTIVE

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) are commonly used for diagnosis of rheumatoid arthritis (RA), although other rheumatic diseases with arthritis can test positive. This study aimed to determine the cutoff values for RF and anti-CCP with the best diagnostic performance in a sample of patients with RA, compared with other rheumatic diseases.

METHODS

This was a descriptive, prospective study. EUROINMMUN enzyme-linked immunosorbent assays for RF isotypes immunoglobulin (Ig) A (IgA), IgG and IgM and third-generation assay IgG for anti-CCP were used in serum samples of patients with RA, other rheumatic diseases and healthy subjects. The cutoff with the best diagnostic performance was determined by the Youden Index and receiver operating characteristic analysis Results: Three hundred and thirty-two serum samples were analysed. The cutoffs proposed in our population were for RF in RA patients versus other rheumatic diseases, and healthy subjects IgM 135 IU/mL, for each disease, compared with RA, were psoriatic arthritis (Psa) IgA 47.2 IU/mL, clinically suspicious arthralgia (CSA) IgA 39.5 IU/mL, primary Sjögren's syndrome (pSS) IgM 180.6 IU/mL, systemic lupus erythematosus (SLE) IgA 42.6 IU/mL, primary fibromyalgia (pFM) IgM 68.6 IU/mL, osteoarthritis (OA) IgM 48 IU/mL, gout IgM 117 IU/mL and healthy IgM 16.3 IU/mL. For anti-CCP, in RA patients versus other rheumatic diseases, and healthy subjects 6.95 IU/mL, for each disease, compared with RA, were Psa 6.8 IU/mL, CSA 9.95 IU/mL, pSS 20.7 IU/mL, SLE 6 IU /mL, pFM 11.8 IU/mL, OA 11.9 IU/mL, gout 5 IU/mL and healthy 5 IU/mL.

CONCLUSION

Irrespective of the manufacturer's suggested cutoff, the RA versus differential diagnosis cutoffs must be considered.

Multisite chronic pain and the risk of autoimmune diseases: A Mendelian randomization study

Background

Accumulating evidence has demonstrated that an association between chronic pain and autoimmune diseases (AIDs). Nevertheless, it is unclear whether these associations refer to a causal relationship. We used a two-sample Mendelian randomization (MR) method to determine the causal relationship between chronic pain and AIDs.

Methods

We assessed genome-wide association study (GWAS) summary statistics for chronic pain [multisite chronic pain (MCP) and chronic widespread pain (CWP)], and eight common AIDs, namely, amyotrophic lateral sclerosis (ALS), celiac disease (CeD), inflammatory bowel disease (IBD), multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus Erythematosus (SLE), type 1 diabetes (T1D) and psoriasis. Summary statistics data were from publicly available and relatively large-scale GWAS meta-analyses to date. The two-sample MR analyses were first performed to identify the causal effect of chronic pain on AIDs. The two-step MR and multivariable MR were used to determine if mediators (BMI and smoking) causally mediated any connection and to estimate the proportion of the association mediated by these factors combined.

Results

With the utilization of MR analysis, multisite chronic pain was associated with a higher risk of MS [odds ratio (OR) = 1.59, 95% confidence interval (CI) = 1.01-2.49, P = 0.044] and RA (OR = 1.72, 95% CI = 1.06-2.77, P = 0.028). However, multisite chronic pain had no significant effect on ALS (OR = 1.26, 95% CI = 0.92-1.71, P = 0.150), CeD (OR = 0.24, 95% CI = 0.02-3.64, P = 0.303), IBD (OR = 0.46, 95% CI = 0.09-2.27, P = 0.338), SLE (OR = 1.78, 95% CI = 0.82-3.88, P = 0.144), T1D (OR = 1.15, 95% CI = 0.65-2.02, P = 0.627) or Psoriasis (OR = 1.59, 95% CI = 0.22-11.26, P = 0.644). We also found positive causal effects of MCP on BMI and causal effects of BMI on MS and RA. Moreover, there were no causal connections between genetically predicted chronic widespread pain and the risk of most types of AIDs disease.

Conclusion

Our MR analysis implied a causal relationship between MCP and MS/RA, and the effect of MCP on MS and RA may be partially mediated by BMI.

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.

Major Histocompatibility Complex Class II HLA-DRB1 Allelic Epitopes in Fibromyalgia

BACKGROUND

Preliminary evidence has pointed an association of the gene HLA-DRB1 with fibromyalgia. HLA-DRB1 alleles carrying the shared or susceptibility epitope encoding the five-amino acid motif QKRAA, QRRAA or RRRAA in positions 70 to 74 of the major histocompatibility complex class II DRβ chain are associated with several autoimmune diseases.

OBJECTIVE

The objective of this study was to test the hypothesis that susceptibility epitope-encoding HLA-DRB1 alleles are associated with fibromyalgia.

METHODS

Using a case-control design, the prevalence of susceptibility epitope-encoding HLADRB1 alleles in 27 white Caucasian patients fulfilling the revised diagnostic criteria for fibromyalgia of the American College of Rheumatology was compared with that in 27 white Caucasian ageand sex-matched healthy controls.

RESULTS

13 (48%) of the fibromyalgia patients had susceptibility epitope-coding HLA-DRB1 alleles compared with 15 (56%) of the controls (P = 0.785). The DRB1*01 allele encoding the protective epitope 70-DERAA-74 motif was found in one of the control subjects; none of the fibromyalgia patients had such a protective epitope.

CONCLUSION

While the present study does not provide evidence supporting the potential role of HLA-DRB1 in the etiology of fibromyalgia, it does not exclude the possibility that there is a polygenic component to a putative genetic causative role.

The autonomic aspects of the post-COVID19 syndrome

The SARS-CoV-2 outbreak, responsible for the widespread COVID-19, led to one of the most rogue pandemics in modern time, yet the major effects of the pandemic may still be ahead of us. SARS-CoV-2 had been found to possess autoimmune properties. Close to 20 distinct autoantibodies which target GPCR of the nervous system and renin-angiotensin system-related molecules were found significantly associated with the clinical severity of COVID-19. The new on-set of more than 10 various autoimmune disorders were documented as well. Additionally, clinical presentations of persisted symptoms were triggered in numerous recently recovered COVID-19 patients, which led to the formulation of the novel term “post-COVID19 syndrome”. Manifestations related to post-COVID-19 syndrome exist among approximately 50–80% of symptomatic COVID-19 patients who recovered, and among patients reported more than 50 different long-term effects of the SARS-CoV-2 infection. Many of the common symptoms of the post-COVID19 syndrome are not explained by the virus-related injury alone. Similarly to chronic fatigue syndrome and fibromyalgia, autoimmune-mediated autonomic nervous system dysfunction may play a significant part in the pathogenesis of such symptoms, including chronic fatigue, cognitive impairment, mood related disorders, and numerous more. Importantly, therapeutic options such as immunomodulatory and immunosuppressive therapy may favor some post-COVID19 patients, while plasmapheresis and IVIG could be considered in severe cases. Nevertheless, as physical exercise has been found to stabilize the autonomic nervous system, exercise therapy might be a safer and more effective remedy for the post-COVID19 syndrome.

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.

Immune System Sex Differences May Bridge the Gap Between Sex and Gender in Fibromyalgia

The fibromyalgia syndrome (FMS) is characterized by chronic widespread pain, sleep disturbances, fatigue, and cognitive alterations. A limited efficacy of targeted treatment and a high FMS prevalence (2–5% of the adult population) sums up to high morbidity. Although, altered nociception has been explained with the central sensitization hypothesis, which may occur after neuropathy, its molecular mechanism is not understood. The marked female predominance among FMS patients is often attributed to a psychosocial predisposition of the female gender, but here we will focus on sex differences in neurobiological processes, specifically those of the immune system, as various immunological biomarkers are altered in FMS. The activation of innate immune sensors is compatible with a neuropathy or virus-induced autoimmune diseases. Considering sex differences in the immune system and the clustering of FMS with autoimmune diseases, we hypothesize that the female predominance in FMS is due to a neuropathy-induced autoimmune pathophysiology. We invite the scientific community to verify the autoimmune hypothesis for FMS.

Putative salivary biomarkers useful to differentiate patients with fibromyalgia

Fibromyalgia (FM) is a chronic pain disorder characterized by widespread pain and associated with unspecific symptoms. So far, no laboratory tests have been validated. The aim of the present study was to investigate the presence in saliva of potential diagnostic and/or prognostic biomarkers which could be useful for the management of FM patients. Specifically, the salivary profile of FM patients was compared with those of healthy subjects, subjects suffering migraine (model of non-inflammatory chronic pain), and patients affected by rheumatoid arthritis (model of inflammatory chronic pain). For proteomics analysis 2-DE and SELDI-TOF-MS were applied. From 2-DE serotransferrin and alpha-enolase were found differentially expressed in FM. Hence, their expression was validated by ELISA together with phosphoglycerate-mutase-I and transaldolase, which were found in a previous work. Moreover, ROC curve was calculated by comparing FM patients versus control subjects (healthy plus migraine) to investigate the discriminative power of biomarkers. The best performance was obtained by combining alpha-enolase, phosphoglycerate-mutase-I and serotransferrin. On the other hand, none of the candidate proteins showed a statistical correlation with clinical features. Finally, preliminary SELDI analysis highlighted two peaks whose identification need to be validated. Overall, these results could be useful in supporting the clinical diagnosis of FM. SIGNIFICANCE: FM is one of the most common chronic pain condition which is associated with significant disability. The fibromyalgic pain is a peculiar characteristic of this disease and FM patients suffer from reduced quality of life, daily functioning and productivity. Considering the deep complexity of FM, the discovery of more objective markers is crucial for supporting clinical diagnosis. Therefore, the aim of the present study was the selection of biomarkers effectively associated with fibromyalgic pain which will enable clinicians to achieve an unambiguous diagnosis, and to improve approaches to patients' management. We defined a panel of 3 salivary proteins which could be one of the criteria to be taken into account. Consequently, the identification of disease salivary biomarkers could be helpful in detecting FM clusters and targeted treatment. Actually, our future perspective foresees to develop a simple, rapid and not invasive point-of-care testing which will be of use during the diagnostic process. In addition, the present results can offer a clue for shedding light upon the complex entity of such a disease like FM.

Infection Elicited Autoimmunity and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: An Explanatory Model

Myalgic encephalomyelitis (ME) often also called chronic fatigue syndrome (ME/CFS) is a common, debilitating, disease of unknown origin. Although a subject of controversy and a considerable scientific literature, we think that a solid understanding of ME/CFS pathogenesis is emerging. In this study, we compiled recent findings and placed them in the context of the clinical picture and natural history of the disease. A pattern emerged, giving rise to an explanatory model. ME/CFS often starts after or during an infection. A logical explanation is that the infection initiates an autoreactive process, which affects several functions, including brain and energy metabolism. According to our model for ME/CFS pathogenesis, patients with a genetic predisposition and dysbiosis experience a gradual development of B cell clones prone to autoreactivity. Under normal circumstances these B cell offsprings would have led to tolerance. Subsequent exogenous microbial exposition (triggering) can lead to comorbidities such as fibromyalgia, thyroid disorder, and orthostatic hypotension. A decisive infectious trigger may then lead to immunization against autoantigens involved in aerobic energy production and/or hormone receptors and ion channel proteins, producing postexertional malaise and ME/CFS, affecting both muscle and brain. In principle, cloning and sequencing of immunoglobulin variable domains could reveal the evolution of pathogenic clones. Although evidence consistent with the model accumulated in recent years, there are several missing links in it. Hopefully, the hypothesis generates testable propositions that can augment the understanding of the pathogenesis of ME/CFS.

Nonvitamin, Nonmineral Dietary Supplement Use among Adults with Fibromyalgia: United States, 2007-2012

BACKGROUND

Fibromyalgia (FMS) is a pain condition affecting 2-6% of US adults; effective treatment remains limited. Determinants of nonvitamin, nonmineral dietary supplement (NVNM) use among adults with FMS are not well-studied. We investigated the relation of NVNM use to FMS, and trends, in two nationally representative samples of US adults ≥18 years.

METHODS

Data were drawn from 2007 and 2012 National Health Interview Surveys (N's = 20127 and 30672, resp.). Logistic regression was used to examine associations of FMS to NVNM use (past 12 months) and evaluate potential modifying influences of gender and comorbidities. Multivariate models adjusted for sampling design, demographic, lifestyle, and health-related factors.

RESULTS

FMS was significantly higher in 2012 than in 2007 (1.7% versus 1.3%), whereas NVNM use decreased (57% versus 41%; p < 0.0001). Adults reporting diagnosis were more likely to use NVNMs within 12 months, 30 days, or ever relative to adults without; positive associations remained significant after controlling for demographics, lifestyle characteristics, medical history, and other confounders (ranges: 2007 and 2012 AORs = 2.3-2.7; 1.5-1.6, resp.; p's < 0.0001).

CONCLUSION

In this cross-sectional study of two national samples, NVNM use was strongly and positively associated with FMS, highlighting the need for further study.

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.

Assessing the prevalence of autoimmune, endocrine, gynecologic, and psychiatric comorbidities in an ethnically diverse cohort of female fibromyalgia patients: does the time from hysterectomy provide a clue?

Background

This retrospective chart review investigated differences in the prevalence of medical comorbidity between women with fibromyalgia (FM) (n=219) and a control group women with chronic pain (CP) without FM (n=116). The specific aims were to compare the prevalence of autoimmune, psychiatric, endocrine, gynecologic pathology, the relationship between timing of gynecologic surgery, and pain onset. We additionally sought to compare the number of comorbidities in an ethnically diverse cohort.

Methods

This was a retrospective chart review of patients seen in FM or CP clinics at an academic medical center in 2009–2010.

Results

Logistic regression modeling found that gynecologic, endocrine, and autoimmune diagnoses were independently associated with a diagnosis of FM. Detailed analyses showed that thyroid disease (P<0.01) and gynecologic surgery (P<0.05) were significantly more common in FM. Women with FM were more likely to have multiple autoimmune, endocrine, gynecologic, or psychiatric pathologies. A relationship was observed between the timing of gynecologic surgery and pain onset in FM, with more surgeries observed in the years just prior to pain onset or in the year after pain onset. A similar pattern was not found in the control group.

Conclusion

This study demonstrates that autoimmune, endocrine, and gynecologic pathologies occur more commonly in women with FM than in those with CP, which is consistent with findings in less ethnically diverse samples. Moreover, a relationship was found between timing of pain onset and gynecologic surgery. A larger prospective study of the relationship between gynecologic surgery and pain onset in FM is warranted.

Comparing Genomic Profiles of Women With and Without Fibromyalgia

BACKGROUND

Fibromyalgia syndrome (FMS), a chronic musculoskeletal condition characterized by diffuse pain, fatigue, sleep impairment, and cognitive dysfunction, is associated with significant functional disability. Its underlying biological mechanisms are unknown. This study investigated differentially expressed genes between women with FMS and healthy volunteers.

METHODS

Women who met the 1990 or 2010 American College of Rheumatology fibromyalgia criteria were compared to age- and race-matched pain-free healthy women. Peripheral blood samples were collected, and a full genome microarray gene expression analysis was performed. One-way analysis of variance was used to identify differentially expressed genes using the filtering criterion of 1% false discovery rate. Analysis of canonical pathways associated with these genes was performed. Confirmatory quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay verified microarray results. Independent t-tests compared gene and protein expression between groups.

RESULT

Participants were 54 women with FMS and 25 controls. Expression arrays from a subset of women with FMS (n = 29) and controls (n = 20) showed upregulation of 12 genes (>1.8-fold change, p < .05) in the FMS sample. Differentially expressed genes were related to B-cell development, primary immunodeficiency signaling, and mitotic roles of polo-like kinase. CENPK and HSP90AA1 were the most differentially expressed genes (p < .01).

CONCLUSION

Activity of interrelated pathways related to immune response, and homeostasis appears to be relevant to the experience of FMS. Replication and exploration of the relationship between gene expression and symptom severity will help determine clinical relevance of these findings.

Proinflammatory cytokines and DHEA-S in women with fibromyalgia: impact of psychological distress and menopausal status

Though fibromyalgia is not traditionally considered an inflammatory disorder, evidence for elevated inflammatory processes has been noted in this disorder in multiple studies. Support for inflammatory markers in fibromyalgia has been somewhat equivocal to date, potentially due to inattention to salient patient characteristics that may affect inflammation, such as psychiatric distress and aging milestones like menopause. The current study examined the relationships between proinflammatory cytokines and hormone levels, pain intensity, and psychological distress in a sample of 34 premenopausal and postmenopausal women with fibromyalgia. Our results indicated significant relationships between interleukin-8 and ratings of pain catastrophizing (r=0.555, P<0.05), pain anxiety (r=0.559, P<0.05), and depression (r=0.551, P<0.05) for postmenopausal women but not premenopausal women (r,0.20 in all cases). Consistent with previous studies, ratios of interleukin-6 to interleukin-10 were significantly lower in individuals with greater levels of depressive symptoms (r=−0.239, P<0.05). Contrary to previous research, however, dehydroepiandrosterone sulfate did not correlate with pain intensity or psychological or biological variables. The results of the current study highlight the importance of psychological functioning and milestones of aging in the examination of inflammatory processes in fibromyalgia.