Fibromyalgia: Genetics and epigenetics insights may provide the basis for the development of diagnostic biomarkers

Assessing the benefits on quality of life of a multicomponent intervention for fibromyalgia syndrome in primary care: patients' and health professionals' appraisals: a qualitative study protocol

INTRODUCTION

Fibromyalgia syndrome (FMS) is a complex condition still scarcely understood and with ambiguity when prescribing treatment. Both patients and healthcare providers can supply valuable information for the development of new treatment strategies. The qualitative narrative analysis of participant's accounts is potentially helpful to reveal new insights about their opinions, needs, and experiences and, consequently, to model healthcare interventions accurately. International treatment guidelines suggest a promising future for multicomponent intervention (MI) approaches for FMS. This study aims to assess the benefits of a MI for patients with FMS in the context of primary care (PC) in Terres de L'Ebre, Catalonia (Spain). Furthermore, it is intended to detect the overall perception of effectiveness and to understand patients' lived experience and its impact on the quality of life.

METHOD AND ANALYSIS

Qualitative research from a socioconstructivism paradigm perspective and a Hermeneutic Phenomenological method. For data collection, four focus group discussions (FGDs) of 8-12 people (2 FGDs of patients and 2 of professionals) and 10-12 key informant interviews with the participants in the MI group will be carried out. All the information will be recorded and verbatim transcribed to perform an interpretive thematic analysis.

ETHICS AND DISSEMINATION

This study protocol has been approved by the Clinical Research Ethics Committee from the IDIAPJGol Institute, on 25 April 2018 (code P18/068), according to the Declaration of Helsinki/Tokyo. All participants will receive oral/written information about the study, and they will be required to sign an informed consent sheet. Data anonymity will be guaranteed. Dissemination will be carried out through publications in scientific journals, presentations in academic meetings, workshops and through the local and national media.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT04049006; Pre-results.

Pain and Cortisol in Patients with Fibromyalgia: Systematic Review and Meta-Analysis

This systematic review and meta-analysis sought to gain further insight into the relationship between cortisol reactivity and chronic widespread pain in patients with fibromyalgia. The studies selected were those conducted in adults with fibromyalgia that were random controlled, non-controlled or observational. Studies were excluded if they examined diseases other than fibromyalgia or if they did not report on pain or cortisol. Twelve studies met inclusion criteria. Data were extracted into tabular format using predefined data fields by two reviewers and assessed for accuracy by a third reviewer. The methodological quality of the studies was assessed using the PEDro scale. Data Synthesis: Of 263 studies identified, 12 were selected for our review and 10 were finally included as their methodological quality was good. In the meta-analysis, we calculated effect sizes of interventions on pain indicators and cortisol levels in patients with fibromyalgia. A small overall effect of all the interventions was observed on pain tolerance and pressure pain thresholds, yet this effect lacked significance (ES = 0.150; 95%CI 0.932–1.550; p > 0.05). Conclusions: While some effects of individual nonpharmacological therapeutic interventions were observed on both cortisol levels and measures of pain, our results suggest much further work is needed to elucidate the true relationship between chronic widespread pain and cortisol levels in patients with fibromyalgia.

Effects of Workplace-Related Factors on the Prevalence of Fibromyalgia among Israeli Kindergarten Teachers

Background

Fibromyalgia syndrome (FMS), a chronic widespread pain disorder, has been associated with various models of stress, including those that are workplace-related. In a previous study, we have documented the significantly increased prevalence of FMS among schoolteachers, as well as correlating symptoms with stressful workplace-related factors. In the current study, we have focused on the specific population of kindergarten teachers and attempted to document both the prevalence of FMS symptoms among this group and the association with stress and symptoms of posttrauma.

Methods

All participants in the study were working as kindergarten teachers in Israel at the time of the study. Participants responded to a questionnaire documenting FMS symptom, which included the widespread pain index (WPI) and symptom severity scale (SSS), which together constitute the suggested American College of Rheumatology (ACR) FMS diagnostic criteria. Additional items on the questionnaire documented work motivation and performance, the occurrence of workplace-related stressful events, and the presence of posttraumatic symptoms.

Results

242 participants were recruited to the current study, including 239 (98.8%) females and 3 (1.2%) males. 62 individuals (25.6%) were found to fulfill ACR FMS criteria. Significant differences in work performance were found between teachers fulfilling FMS criteria compared with those not fulfilling criteria. Thus, FMS-positive teachers reported significantly higher rates of missing workdays, leaving work early, and a lower quality of interaction with children in the kindergarten and with peers and supervisors. Motivation to work was also significantly lower among these individuals. The widespread pain index (WPI) and symptom severity scale (SSS), which together constitute the components of the FMS diagnostic criteria, were positively correlated with both stress and posttraumatic symptoms. In addition, widespread pain, disordered sleep, difficulty with concentration, and other FMS symptoms were strongly correlated with many specific stressful factors at the workplace, including the number of children in the kindergarten, interaction with parents, lack of optimal physical conditions in the classrooms, and various demands on behalf of the educational system.

Conclusion

FMS symptoms were found to be highly prevalent among Israeli kindergarten teachers, at a rate that greatly exceeds the prevalence in the general Israeli population. Stressful work-related events appear to be positively associated with the occurrence of FMS symptoms and may serve as triggers for their development. Healthcare professionals treating individuals engaged in this occupation should be vigilant for the occurrence of symptoms that are clinically associated with FMS and overlapping functional disorders.

Physician Prescribing Patterns and Risk of Future Long-Term Opioid Use Among Patients With Rheumatoid Arthritis: A Prospective Observational Cohort Study

OBJECTIVE

To identify the extent to which opioid prescribing rates for patients with rheumatoid arthritis (RA) vary in the US and to determine the implications of baseline opioid prescribing rates on the probability of future long-term opioid use.

METHODS

We identified patients with RA from physicians who contributed ≥10 patients within the first 12 months of participation in the Corrona RA Registry. The baseline opioid prescribing rate was calculated by dividing the number of patients with RA reporting opioid use during the first 12 months by the number of patients with RA providing data that year. To estimate odds ratios (ORs) for long-term opioid use, we used generalized linear mixed models.

RESULTS

During the follow-up period, long-term opioid use was reported by 7.0% (163 of 2,322) of patients of physicians with a very low rate of opioid prescribing (referent) compared to 6.8% (153 of 2,254) of patients of physicians with a low prescribing rate, 12.5% (294 of 2,352) of patients of physicians with a moderate prescribing rate, and 12.7% (307 of 2,409) of patients of physicians with a high prescribing rate. The OR for long-term opioid use after the baseline period was 1.16 (95% confidence interval [95% CI] 0.79-1.70) for patients of low-intensity prescribing physicians, 1.89 (95% CI 1.27-2.82) for patients of moderate-intensity prescribing physicians, and 2.01 (95% CI 1.43-2.83) for patients of high-intensity prescribing physicians, compared to very low-intensity prescribing physicians.

CONCLUSION

Rates of opioid prescriptions vary widely. Our findings indicate that baseline opioid prescribing rates are a strong predictor of whether a patient will become a long-term opioid user in the future, after controlling for patient characteristics.

Investigational drugs in early phase clinical trials targeting thermotransient receptor potential (thermoTRP) channels

INTRODUCTION

Thermo transient receptor potential (thermoTRP) channels are some of the most intensely pursued therapeutic targets of the past decade. They are considered promising targets of numerous diseases including chronic pain and cancer. Modulators of these proteins, in particular TRPV1-4, TRPM8 and TRPA1, have reached clinical development, but none has been approved for clinical practice yet.

AREAS COVERED

The therapeutic potential of targeting thermoTRP channels is discussed. The discussion is centered on our experience and on available data found in SciFinder, PubMed, and ClinicalTrials.gov database from the past decade. This review focuses on the therapeutic progress concerning this family of channels, including strategies to improve their therapeutic index for overcoming adverse effects.

EXPERT OPINION

Although thermoTRPs are pivotal drug targets, translation to the clinic has faced two key problems, (i) unforeseen side effects in Phase I trials and, (ii) poor clinical efficacy in Phase II trials. Thus, there is a need for (i) an enhanced understanding of the physiological role of these channels in tissues and organs and (ii) the development of human-based pre-clinical models with higher clinical translation. Furthermore, progress in nanotechnology-based delivery strategies will positively impact thermoTRP human pharmacology.

The Influence of Pro-inflammatory Cytokines and Genetic Variants in the Development of Fibromyalgia: A Traditional Review

Fibromyalgia is a complex syndrome characterized by widespread chronic pain, without any obvious etiology, and it is often accompanied by a constellation of symptoms such as fatigue, sleep disturbances and cognitive dysfunction, to name a few. The syndrome may be associated with a variety of autoimmune and psychiatric conditions. Fibromyalgia can occur with other musculoskeletal pathologies and its symptoms can overlap with other chronic painful conditions such as chronic myofascial pain syndromes seen in cervical and lumbar spinal osteoarthritis and degenerative disc disease. Gene polymorphisms have been related to a decreased pain threshold and an increased susceptibility to disorders associated with chronic pain. Some of those genetic variants might trigger the onset of fibromyalgia. Researchers are looking into the possible factors that might contribute to its pathophysiology. It is important to study the connections between pro-inflammatory cytokines and genetic variants in pain-related genes and their roles in predisposition and development of fibromyalgia. The objective of this review article is to provide a brief overview of the pro-inflammatory cytokines commonly associated with fibromyalgia, as well as to look into the genes that have shown some level of involvement in the development of fibromyalgia and its symptomatology.

Nutritional Interventions in the Management of Fibromyalgia Syndrome

Fibromyalgia (FM) is a multifactorial syndrome of unknown etiology, characterized by widespread chronic pain and various somatic and psychological manifestations. The management of FM requires a multidisciplinary approach combining both pharmacological and nonpharmacological strategies. Among nonpharmacological strategies, growing evidence suggests a potential beneficial role for nutrition. This review summarizes the possible relationship between FM and nutrition, exploring the available evidence on the effect of dietary supplements and dietary interventions in these patients. Analysis of the literature has shown that the role of dietary supplements remains controversial, although clinical trials with vitamin D, magnesium, iron and probiotics' supplementation show promising results. With regard to dietary interventions, the administration of olive oil, the replacement diet with ancient grains, low-calorie diets, the low FODMAPs diet, the gluten-free diet, the monosodium glutamate and aspartame-free diet, vegetarian diets as well as the Mediterranean diet all appear to be effective in reducing the FM symptoms. These results may suggest that weight loss, together with the psychosomatic component of the disease, should be taken into account. Therefore, although dietary aspects appear to be a promising complementary approach to the treatment of FM, further research is needed to provide the most effective strategies for the management of FM.

A Cross-Sectional Study on Central Sensitization and Autonomic Changes in Fibromyalgia

Fibromyalgia is a multi-symptomatic disorder characterized by generalized pain. The pathophysiology of fibromyalgia is supposedly an interplay between central nervous system hyper-responsiveness, autonomic dysfunction, and peripheral pain. In this cross-sectional study, the objective was to assess central sensitization and autonomic activity in patients with fibromyalgia compared with control. Fifty adults diagnosed with fibromyalgia by the modified American College of Rheumatology 2010 criteria and an equal number of age- and sex-matched controls participated in the study in an urban tertiary care hospital. Central sensitization was assessed by history and by evidence of increased prefrontal cortical activity as measured by cortical oxygenation using functional near-infrared spectroscopy. Autonomic activity was assessed by heart rate variability, electrodermal activity, and deep breathing test in three physiological states: rest, sympathetic stress (cold pressor test), and deep breathing. Mann–Whitney U-test, paired t-test, Wilcoxon test, and Friedman test with Bonferroni a priori were used to analyze the data. Cortical activity was significantly higher in the fibromyalgia group than control. There was no significant difference in autonomic activity between the fibromyalgia and control groups. In the fibromyalgia group, variable degrees of sympathetic hyperactivity and normal parasympathetic activity were observed. Central sensitization may be playing a primary role in the pathophysiology of generalized pain in fibromyalgia.

Contribution of central sensitization to stress-induced spreading hyperalgesia in rats with orofacial inflammation

Temporomandibular disorder (TMD) is commonly comorbid with fibromyalgia syndrome (FMS). The incidence of these pain conditions is prevalent in women and prone to mental stress. Chronic pain symptoms in patients with FMS and myofascial TMD (mTMD) are severe and debilitating. In the present study, we developed a new animal model to mimic the comorbidity of TMD and FMS. In ovariectomized female rats, repeated forced swim (FS) stress induced mechanical allodynia and thermal hyperalgesia in the hindpaws of the 17β-estradiol (E2) treated rats with orofacial inflammation. Subcutaneous injection of E2, injection of complete Freund’s adjuvant (CFA) into masseter muscles or FS alone did not induce somatic hyperalgesia. We also found that the somatic hyperalgesia was accompanied by upregulation of GluN1 receptor and serotonin (5-hydroxytryptamine, 5-HT)_3A receptor expression in the dorsal horn of spinal cord at L4-L5 segments. Intrathecal injection of N-methyl-D-aspartic acid receptor (NMDAR) antagonist 2-amino-5-phosphonovaleric acid (APV) or 5-HT₃ receptor antagonist Y-25130 blocked stress-induced wide-spreading hyperalgesia. These results suggest that NMDAR-dependent central sensitization in the spinal dorsal horn and 5-HT-dependent descending facilitation contribute to the development of wide-spreading hyperalgesia in this comorbid pain model.

Sural Nerve Size in Fibromyalgia Syndrome: Study on Variables Associated With Cross-Sectional Area

Increased cross-sectional area (CSA) of sural nerve, documented by ultrasound (US), has been revealed in small fibers neuropathy, condition present in about half of patients with fibromyalgia (FM). The aims of this study were to evaluate sural nerve CSA and to establish the variables associated with increased CSA in FM patients. A cross-sectional assessment was conducted in consecutive FM patients. Demographic data, clinimetric parameters [Fibromyalgia Impact Questionnaire (FIQR)], the neuropathic pain features [PainDetect Questionnaire (PDQ)], and the sural nerve CSA were recorded. CSA was determined by US, examining the sural nerve at the lateral region of the calf. CSA was compared with demographic and clinical variables. A multiple regression analysis was conducted applying CSA as dependent variable. One hundred and ten FM patients were enrolled. Sural nerve CSA showed a significant association with body mass index (BMI) (r = 0.422; p < 0.0001) and with PDQ (r = 0.361; p = 0.0001). The multiple regression analysis confirmed that BMI (p = 0.0001) and PDQ (p = 0.0028) were the two independent variables associated with CSA. The severity of the disease, measured with FIQR, showed no association. An increase in sural nerve CSA is closely related to BMI and to distinctive neuropathic symptoms. Overweight and obesity appear to be associated with a FM phenotype with documented peripheral nervous system involvement. Ultrasound examination of the sural nerve at calf level may reveal useful information in patients with FM, identifying a cluster of patients with peripheral nervous system alterations. This cluster of patients is generally overweight or obese, and complains of painful symptoms with neuropathic features.

Activation of Transposable Elements in Immune Cells of Fibromyalgia Patients

Advancements in nucleic acid sequencing technology combined with an unprecedented availability of metadata have revealed that 45% of the human genome constituted by transposable elements (TEs) is not only transcriptionally active but also physiologically necessary. Dysregulation of TEs, including human retroviral endogenous sequences (HERVs) has been shown to associate with several neurologic and autoimmune diseases, including Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). However, no study has yet addressed whether abnormal expression of these sequences correlates with fibromyalgia (FM), a disease frequently comorbid with ME/CFS. The work presented here shows, for the first time, that, in fact, HERVs of the H, K and W types are overexpressed in immune cells of FM patients with or without comorbid ME/CFS. Patients with increased HERV expression (N = 14) presented increased levels of interferon (INF-β and INF-γ) but unchanged levels of TNF-α. The findings reported in this study could explain the flu-like symptoms FM patients present with in clinical practice, in the absence of concomitant infections. Future work aimed at identifying specific genomic loci differentially affected in FM and/or ME/CFS is warranted.

The TRPV2 cation channels: from urothelial cancer invasiveness to glioblastoma multiforme interactome signature

Changes in transient receptor potential (TRP) Ca²⁺ permeable channels are associated with development and progression of different types of cancer. Herein, we report data relative to the expression and function of TRP vanilloid 2 (TRPV2) channels in cancer. Overexpression of TRPV2 is observed in high-grade urothelial cancers and treatment with the TRPV2 agonist cannabidiol induces apoptosis. In prostate cancer, TRPV2 promotes migration and invasion, and TRPV2 overexpression characterizes the castration-resistant phenotype. In breast cancer cells, inhibition of TRPV2 by tranilast reduces the insulin-like growth factor-1 stimulated proliferation. TRPV2 overexpression in triple-negative breast cancer cells is associated with high recurrence-free survival. Increased TRPV2 overexpression is present in patients with esophageal squamous cell carcinoma associated with advanced disease, lymph node metastasis, and poor prognosis. Increased TRPV2 transcripts have been found both in benign hepatoma and in hepatocarcinomas, where TRPV2 expression is associated with portal vein invasion and reduction of cancer stem cell expression. TRPV2 expression and function has been also evaluated in gliomagenesis. This receptor negatively controls survival, proliferation, and resistance to CD95- or BCNU-induced apoptosis. In glioblastoma stem cells, TRPV2 activation promotes differentiation and inhibits the proliferation in vitro and in vivo. In glioblastoma, the TRPV2 is part of an interactome-based signature complex, which is negatively associated with survival, and it is expressed in high risk of recurrence and temozolomide-resistant patients. Finally, also in hematological malignancies, such as myeloma or acute myeloid leukemia, TRPV2 might represent a target for novel therapeutic approaches. Overall, these findings demonstrate that TRPV2 exhibits an oncogenic activity in different types of cancers, controlling survival, proliferation, migration, angiogenesis, and invasion signaling pathways. Thus, it prompts the pharmacological use of TRPV2 targeting in the control of cancer progression.

Biomarkers in Temporomandibular Disorder and Trigeminal Neuralgia: A Conceptual Framework for Understanding Chronic Pain

In this review, we will explore the use of biomarkers in chronic pain, using the examples of two prototypical facial pain conditions: trigeminal neuralgia and temporomandibular disorder. We will discuss the main categories of biomarkers and identify various genetic/genomic, molecular, neuroradiological, and psychophysical biomarkers in both facial pain conditions, using them to compare and contrast features of neuropathic, nonneuropathic, and mixed pain. By using two distinct model facial pain conditions to explore pain biomarkers, we aim to familiarize readers with different types of biomarkers currently being studied in chronic pain and explore how these biomarkers may be used to develop new precision medicine approaches to pain diagnosis, prognosis, and management.

5'UTR polymorphism in the serotonergic receptor HTR3A gene is differently associated with striatal Dopamine D2/D3 receptor availability in the right putamen in Fibromyalgia patients and healthy controls-Preliminary evidence

BACKGROUND

Extensive literature has investigated the role of serotonin (5-HT) in the control of the central dopamine (DA) systems, and their dysfunction in the pathological conditions. 5-HT stimulates the local DA release in striatal regions via activation of various receptors including serotonin receptor-3 (5-HT3). Several studies have related polymorphisms (SNPs) in the serotonin receptor-3 (HTR3) genes to be associated with the pain modulation and endogenous pain suppression. A few studies suggested a functional role of 5'UTR SNP in the serotonergic receptor HTR3A gene (rs1062613) in the development of the chronic pain and Fibromyalgia syndrome (FMS) in particular. Here, we investigated the effect of a 5'UTR SNP in the serotonergic receptor HTR3A gene (rs1062613) on striatal dopamine D2/D3 receptor (DRD2) availability and reward-associated DA release in response to unpredictable monetary rewards in 23 women with FMS and 17 age-matched healthy female controls. Furthermore, we aimed to examine if SNP rs1062613 is associated with thermal pain and pain tolerance thresholds.

METHODS

We used PET and [¹¹ C]raclopride to assess the DRD2 availability. In the same participants we used the [¹¹ C]raclopride PET bolus-plus-infusion method to measure the [¹¹ C]raclopride receptor binding potential (ΔBP) between an unpredictable reward condition and a sensorimotor control condition. DRD2 availability and ΔBP were assessed in MRI-based striatal regions of interest. Thermal pain and pain tolerance thresholds were assessed outside the scanner.

RESULTS

The frequency of SNP rs1062613 genotype differed significantly between groups, indicating that CC homozygotes were more frequent in FMS patients (82.6%) than in healthy controls (41.3%). Our results showed a significant main effect of SNP rs1062613 on [¹¹ C]raclopride binding potential in the right caudate nucleus indicating a higher DRD2 receptor availability for CC-genotype of this SNP. Furthermore, we found a significant group × SNP interaction on [¹¹ C]raclopride binding potential in the right putamen, indicating a higher DRD2 availability in T-carriers compared to CC genotype of SNP rs1062613 in FMS patients, whereas this effect was not present in healthy controls. However, we did not find an influence of SNP rs1062613 on reward-related DA release. In addition, there was no association between SNP rs1062613 and pain threshold or pain tolerance threshold in our data.

CONCLUSION

These preliminary results indicate that SNP rs1062613 in the serotonergic receptor HTR3A gene possibly modulates the DRD2 receptor availability.

Exosomes as a new pain biomarker opportunity

Exosomes are extracellular microvesicles implicated in intercellular communication with ability to transfer cargo molecules, including protein, lipids, and nucleic acids, at both close and distant target sites. It has been shown that exosomes are implicated in physiological and pathological processes. In recent years, the interest on exosomes' role in many pain states has increased. Their involvements in pain processes have been demonstrated by studies on different chronic pain diseases, both inflammatory and neuropathic, such as osteoarthritis, rheumatoid arthritis, inflammatory bowel diseases, neurodegenerative pathologies, complex regional pain syndrome, and peripheral nerve injury. Animal and clinical studies investigated exosomes-based treatments, showing their ability to improve painful symptoms with fewer side effects, with potential immunoprotective and anti-inflammatory effect. Specific molecular patterns characterize exosomes' cargo according to the cellular origin, epigenetic modifications, environmental state, and stressor factors. Therefore, the identification of specific cargo's profile associated to pain states may lead to recognize specific pathological states and to consider the use of exosomes as biomarkers of diseases. Furthermore, exosomes' ability to transfer information and their presence in many accessible biological fluids suggest a potential use as novel non-invasive therapeutic tools in pain field.

Lower limb muscle strength and serotonin receptor gene polymorphism as factors associated in women with fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a chronic pain syndrome characterized by generalized skeletal muscle chronic pain. Its etiology is not well defined, because there are several factors that may trigger it such as physical and/or emotional stresses, or a genetic susceptibility, involving serotonergic, dopaminergic and catecholaminergic paths. The objective of this study was to investigate the association between the strength of the lower limb, genetic polymorphism of the serotonin receptor gene HTR_2A in women with fibromyalgia.

METHODS

In this observational study of case-control type 48 women were evaluated who belonged to the group with FM (52 ± 12 years) and 100 women in the control group (58 ± 11 years). Socio demographic and anthropometric data were collected and peripheral blood samples for DNA extraction; genotypic analyzes were performed by means of PCR in real time by TaqMan® system. The lower limb muscle strength was assessed through the test of sitting down and standing up for 30 s. The chi-square test or Fischer Exact was used for possible associations among the variables; the t-test for independent samples was used to compare the averages among the groups; the value of significance adopted was 5%.

RESULTS

There was an association between the polymorphism of the HTR2A gene with FM, demonstrating that carriers of the genotype GG have 24.39 times more likely to develop the syndrome (IC95% 5.15-115.47; p = 0.01). It was observed an association between FM and the test to sit and stand up demonstrating that women with fibromyalgia have lower limb muscle strength (p = 0.01). The study showed that the white race has 3.84 times more likely to develop FM (p = 0.01).

CONCLUSION

The results of this study suggest that women of Caucasian ethnicity with GG genotype or G allele presented greater risk of developing fibromyalgia and that these patients have lower limb muscle strength compared to the control group.

Pain complaints are associated with quick returns and insomnia among Norwegian nurses, but do not differ between shift workers and day only workers

PURPOSE

To determine whether common work schedule characteristics among Norwegian nurses were associated with subjective pain complaints.

METHODS

A cross-sectional study in a sample of 1585 nurses, part of the longitudinal questionnaire-based cohort project 'Survey of Shift work, Sleep and Health' (SUSSH). Pain from six regions were assessed: 'headache', 'neck/shoulder/upper back', 'upper extremities', 'lower back', 'lower extremities', and 'abdomen'. Logistic and negative binomial regression (adjusted for age, sex, percentage of full-time equivalent, marital status and children living at home) were conducted where work schedule, number of night shifts last year, number of quick returns (QR) last year (< 11 h between shifts) and insomnia were predictors of localized pain, widespread pain and number of pain sites.

RESULTS

Localized pain, widespread pain and number of pain sites were associated with insomnia (OR 2.06, 95% CI 1.66-2.55, OR 2.14, 95% CI 1.47-3.09, IRR 1.70, 95% CI 1.51-1.91, respectively). Work schedule and number of night shifts worked last year were not associated with any of the three pain measures. Number of QRs worked last year tended to be associated with number of pain sites.

CONCLUSION

The study did not support the hypothesis that non-daytime work schedules are associated with pain complaints. Neither was there support for the hypothesis linking number of night shifts, or the number of QRs, to pain complaints. Future studies should aim to determine the association between QRs and pain in more detail. Pain complaints were associated with insomnia.

Cellular and Molecular Mechanisms in the Pathogenesis of Classical, Vascular, and Hypermobile Ehlers‒Danlos Syndromes

The Ehlers‒Danlos syndromes (EDS) constitute a heterogenous group of connective tissue disorders characterized by joint hypermobility, skin abnormalities, and vascular fragility. The latest nosology recognizes 13 types caused by pathogenic variants in genes encoding collagens and other molecules involved in collagen processing and extracellular matrix (ECM) biology. Classical (cEDS), vascular (vEDS), and hypermobile (hEDS) EDS are the most frequent types. cEDS and vEDS are caused respectively by defects in collagen V and collagen III, whereas the molecular basis of hEDS is unknown. For these disorders, the molecular pathology remains poorly studied. Herein, we review, expand, and compare our previous transcriptome and protein studies on dermal fibroblasts from cEDS, vEDS, and hEDS patients, offering insights and perspectives in their molecular mechanisms. These cells, though sharing a pathological ECM remodeling, show differences in the underlying pathomechanisms. In cEDS and vEDS fibroblasts, key processes such as collagen biosynthesis/processing, protein folding quality control, endoplasmic reticulum homeostasis, autophagy, and wound healing are perturbed. In hEDS cells, gene expression changes related to cell-matrix interactions, inflammatory/pain responses, and acquisition of an in vitro pro-inflammatory myofibroblast-like phenotype may contribute to the complex pathogenesis of the disorder. Finally, emerging findings from miRNA profiling of hEDS fibroblasts are discussed to add some novel biological aspects about hEDS etiopathogenesis.