Fibromyalgia: A Review of Related Polymorphisms and Clinical Relevance

Pharmacotherapy for osteoarthritis-related pain: current and emerging therapies

INTRODUCTION

Osteoarthritis (OA) related pain has affected millions of people worldwide. However, the current pharmacological options for managing OA-related pain have not achieved a satisfactory effect.

AREAS COVERED

This narrative review provides an overview of the current and emerging drugs for OA-related pain. It covers the drugs' mechanism of action, safety, efficacy, and limitations. The National Library of Medicine (PubMed) database was primarily searched from 2000 to 2024.

EXPERT OPINION

Current treatment options are limited and suboptimal for OA pain management. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are the recognized and first-line treatment in the management of OA-related pain, and other drugs are inconsistent recommendations by guidelines. Emerging treatment options are promising for OA-related pain, including nerve growth factor (NGF) inhibitors, ion channel inhibitors, and calcitonin gene-related peptide (CGRP) antagonists. Besides, drugs repurposing from antidepressants and antiepileptic analgesics are shedding light on the management of OA-related pain. The management of OA-related pain is challenging as pain is heterogeneous and subjective. A more comprehensive strategy combined with non-pharmacological therapy needs to be considered, and tailored management options to individualized patients.

The role of tryptophan and its derivatives in musculoskeletal pains: A systematic review and meta-analysis

BACKGROUND

Studies present ambiguous findings regarding the role of tryptophan and its metabolites, kynurenine and serotonin in chronic musculoskeletal pain. This systematic review aimed to investigate the expression of tryptophan and its metabolites, serotonin and kynurenine in patients with local and generalized chronic musculoskeletal pain in comparison with pain-free controls.

METHODS

An electronic search was conducted in the databases MEDLINE, CINAHL, EMBASE, the Cochrane Central Registry of Controlled Trials (CENTRAL) and Web of Science for clinical and observational trials from the beginning of each database to 21 April 2023. Out of 6734 articles, a total of 17 studies were included; 12 studies were used in the meta-analysis of serotonin, 3 regarding tryptophan and 2 studies for a narrative synthesis regarding kynurenine. Risk of bias was assessed using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute, while the certainty of evidence was by GRADE.

RESULTS

All included studies showed a low risk of bias. The meta-analysis showed lower blood levels of tryptophan (p < .001; very low quality of evidence) and higher blood levels of serotonin (p < .001; very low-quality evidence) in patients with generalized musculoskeletal pain, when compared to pain-free individuals. In local chronic musculoskeletal pain, there were higher blood levels of serotonin (p=.251; very low quality of evidence) compared to pain-free individuals. Regarding kynurenine, the studies reported both higher and lower blood levels in generalized chronic musculoskeletal pain compared to pain-free individuals.

CONCLUSIONS

The blood levels of tryptophan and its metabolites serotonin and kynurenine seem to influence chronic musculoskeletal pain.

Brain-Derived Neurotrophic Factor, Nociception, and Pain

This article examines the involvement of the brain-derived neurotrophic factor (BDNF) in the control of nociception and pain. BDNF, a neurotrophin known for its essential role in neuronal survival and plasticity, has garnered significant attention for its potential implications as a modulator of synaptic transmission. This comprehensive review aims to provide insights into the multifaceted interactions between BDNF and pain pathways, encompassing both physiological and pathological pain conditions. I delve into the molecular mechanisms underlying BDNF's involvement in pain processing and discuss potential therapeutic applications of BDNF and its mimetics in managing pain. Furthermore, I highlight recent advancements and challenges in translating BDNF-related research into clinical practice.

COMT and SCN9A gene variants do not contribute to chronic low back pain in Mexican-Mestizo patients

BACKGROUND

Chronic low back pain (CLBP) is a complex condition in which genetic factors play a role in its susceptibility. Catechol-O-methyltransferase (COMT) and sodium channel NaV1.7 (SCN9A) genes are implicated in pain perception. The aim is to analyze the association of COMT and SCN9A with CLBP and their interaction, in a Mexican-Mestizo population.

METHODS

A case-control study was conducted. Cases corresponded to adults of both sexes with CLBP. Controls were adults with no CLBP. Variants of SCN9A and COMT were genotyped. Allelic and genotypic frequencies and Hardy-Weinberg equilibrium (HWE) were calculated. Association was tested under codominant, dominant, and recessive models. Multifactor dimensionality reduction was developed to detect epistasis.

RESULTS

Gene variants were in HWE, and there was no association under different inheritance models in the whole sample. In women, in codominant and dominant models, a trend to a high risk was observed for AA of rs4680 of COMT (OR = 1.7 [0.5-5.3] and 1.6 [0.7-3.4]) and for TT of rs4633 (OR = 1.6 [0.7-3.7] and 1.6 [0.7-3.4]). In men, a trend to low risk was observed for AG genotype of rs4680 in the same models (OR = 0.6 [0.2-1.7] and 0.7 [0.3-1.7]), and for TC genotype of rs4633 in the codominant model (OR = 0.6 [0.2-1.7]). In the interaction analysis, a model of the SCN9A and COMT variants showed a CVC of 10/10; however, the TA was 0.4141.

CONCLUSION

COMT and SCN9A variants are not associated with CLBP in the analyzed Mexican-Mestizo population.

Depressive Symptoms in Patients with Fibromyalgia: Current Evidence and Preventive Approaches

Fibromyalgia is a chronic inflammatory disease characterized by multifocal pain, fatigue, and cognitive impairment [...].

Personality construct as a biomarker in fibromyalgia: A narrative review from an autonomic rehabilitation perspective

BACKGROUND

The heterogeneity of symptoms and ineffective treatment raise questions about the current diagnostic criteria of fibromyalgia (FM). Misdiagnosis of FM often leads to less than efficacious treatment and poor quality of life.

OBJECTIVE

This article reviews relevant evidence-based literature on personality traits in FM patients with an autonomic dysfunction perspective based on a hierarchical model to explain the utility of considering the personality trait in FM diagnosis.

METHODS

A narrative review of articles concerning chronic pain, FM, and personality traits with respect to autonomic dysfunction in FM was conducted after extensive relevant literature searches.

RESULTS

Reports discussing the predisposing factors, including coping styles, anger, suicide risk, a lack of physical activity and social support, in maintaining persistent pain in FM exist. Relationships between pain duration and severity and personality traits like neuroticism and extraversion have been reported. Coexisting clinical manifestations of FM like sleep disorders, anxiety, and intestinal irritability indicate autonomic dysfunction.

CONCLUSIONS

This article lays out a constructive framework for individualized and personalized medicine for the effective rehabilitation of FM patients. The quest to find a definitive diagnosis of FM should include personality biomarkers that might translate into personalized medicine. An individualistic approach may bank upon artificial intelligence algorithms for both diagnostic as well as prognostic purposes in FM.

Lack of Association between (AAT)n Polymorphism of the CNR1 Gene Encoding the Cannabinoid Receptor (CB1) and Patient’s Quality of Life

Genetic factors may predispose persons to decreased pain excitability. One of the interesting modulators affecting pain perception may be polymorphisms of the cannabinoid receptor type 1 (CNR1) gene. In this study, we examined the association between three-nucleotide repeats (AAT) polymorphism located in the 3′UTR non-translational region of CNR1 and the patient’s quality of life after total hip arthroplasty. Our study examined the degree of pain sensation, hip function, and the patient’s performance at defined intervals after elective hip replacement due to degenerative changes. The study included 198 patients (128 women and 70 men). The average age was 67 years. PCR genotyping assay was used to identify the (AAT)n triplet repeat polymorphism in the CNR1 gene. The (AAT)n repeat number was determined by sequencing using a standard sequencing protocol. Our study found no statistically significant association between the degree of pain, hip function, and the change in the degree of disability and the (AAT)n polymorphism in the CNR1 gene, no statistically significant correlations between clinical symptoms, the patient’s age, and the number of AAT repeats, no association between the length of the allele and the degree of pain, hip function, and the change in disability.

Uncovering a Genetic Polymorphism Located in Huntingtin Associated Protein 1 in Modulation of Central Pain Sensitization Signaling Pathways

Fibromyalgia syndrome (FMS) is characterized by widespread pain and increased sensitivity to nociceptive stimulus or tenderness. While familial aggregation could suggest a potential hereditary component in FMS development, isolation of genetic determinants has proven difficult due to the multi-factorial nature and complexity of the syndrome. Central sensitization is thought to be one of the key mechanisms leading to FMS in a subset of patients. Enhanced central pain signaling can be measured using the Nociceptive Flexion Reflex (NFR) or RIII threshold. We performed a genome-wide association study (GWAS) using an array to genotype 258,756 human genetic polymorphisms in 225 FMS patients and 77 healthy volunteers and searched for genetic variants associated with a lowered NFR threshold. We have identified a potential association between a single nucleotide polymorphism resulting in a common non-synonymous coding mutation in the Huntingtin associated protein 1 (HAP1) gene (rs4796604, MAF = 0.5) and the NFR threshold (p = 4.78E−06). The Hap1 protein is involved in trafficking and is particularly enriched in neurons. Our results suggest a possible involvement of the neuronal trafficking protein HAP1 in modulating pain signaling pathways and thus participate in the establishment of the NFR threshold.

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.