Chronic Pain in Inflammatory Arthritis: Mechanisms, Metrology, and Emerging Targets-A Focus on the JAK-STAT Pathway

System-based pain groups are uniquely associated with sociodemographic and psychiatric correlates among those with posttraumatic stress disorder (PTSD)

OBJECTIVE

Chronic pain is a prevalent comorbidity among those with posttraumatic stress disorder (PTSD). Chronic pain can be divided into specific pain (i.e., involving a single body system) and complex pain (i.e., involving multiple body systems). We explored sociodemographic and psychiatric differences between pain groups among those with PTSD.

METHOD

Data came from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC-III, N = 36,309). Pain groups were determined through health professional confirmed self-report of chronic pain conditions within three body systems (musculoskeletal, nerve or digestive conditions). Psychiatric conditions were identified with the Alcohol Use Disorder and Associated Disabilities Interview Schedule for DSM-5; suicide attempts were assessed via self-report.

RESULTS

Among our PTSD sub-sample (n = 1779; 4.7%), 53.9% had no conditions, 25.6% endorsed specific pain, and 19.1% endorsed complex pain. Multinomial logistic regressions revealed increased odds of certain sociodemographic correlates (e.g., older age) common to both pain groups when compared to those with PTSD alone, as well as decreased odds (e.g., being non-White) unique to those with complex pain. Multivariable logistic regressions revealed both specific pain and complex pain were associated with increased odds of any lifetime personality disorder relative to the no pain group (AOR = 1.56 and 2.38, respectively). Complex pain was uniquely associated with increased odds of any past-year anxiety disorder, past-year tobacco use disorder, and lifetime suicide attempts (AOR range = 1.46-1.69) relative to PTSD alone.

CONCLUSION

Findings indicate that those with PTSD and pain conditions impacting multiple body systems represent a particularly vulnerable group.

Knowledge of the genetics of human pain gained over the last decade from next-generation sequencing

Next-generation sequencing (NGS) technologies have revolutionized pain research by providing comprehensive insights into genetic variation across the genome. Recent studies have expanded the known spectrum of mutations in genes such as SCN9A and NTRK1, which are commonly mutated in hereditary sensory neuropathies. NGS has uncovered critical alternative splicing events and facilitated single-cell transcriptomics, revealing cellular heterogeneity within tissues. An NGS-based classifier predicted extremely high opioid requirements with 80 % accuracy, highlighting the importance of tailoring opioid therapy based on genetic profiles. Key genes such as GDF5, COL11A1, and TRPV1 have been linked to osteoarthritis risk and pain sensitivity, while HLA-DRB1, TNF, and P2X7 play critical roles in inflammation and pain modulation in rheumatoid arthritis. Innovative tools, such as an atlas of the somatosensory system in neuropathic pain, have been developed based on NGS data, focusing on the dorsal root and trigeminal ganglia. This approach allows the analysis of cellular changes during the development of chronic pain. In the study of rare variants, NGS outperforms single nucleotide variant candidate studies and classical genome-wide association approaches. The complex data generated by NGS enables integrated multi-omics approaches, allowing deeper exploration of the molecular and cellular basis of pain perception. In addition, the characterization of non-coding RNAs has opened new therapeutic avenues. NGS-based pain research faces challenges related to complex data analysis and interpretation of rare genetic variants with unknown biological functions. Nevertheless, NGS offers significant potential for improving personalized pain management and highlights the need for interdisciplinary collaboration to translate findings into clinical practice.

Fibromyalgia and Inflammation: Unrevealing the Connection

Fibromyalgia represents a chronic pain pathology characterized by severe musculoskeletal pain, fatigue, disturbances in sleep, and cognitive issues. Despite its presence, the underlying mechanisms of fibromyalgia remain inadequately understood; however, recent investigations have suggested that inflammation could play a fundamental role in the pathophysiology of this condition. Several studies highlight elevated concentrations of pro-inflammatory cytokines, dysregulation of immune responses, and neuroinflammation in fibromyalgia patients. Furthermore, chronic low-grade inflammation has been proposed as a potential catalyst for the sensitization of pain pathways, which exacerbates the symptoms of fibromyalgia. Understanding the role of inflammation in this disease might open new avenues for therapeutic interventions while providing a more profound insight into the complex nature of this debilitating disorder. Although progress has been made, further research is needed to uncover the complexities involved. This review investigates the intricate relationship between inflammation and fibromyalgia, analyzing the evidence that supports the involvement of both peripheral and central inflammatory processes in the onset and persistence of the disorder.

Association between C-reactive protein and chronic pain in US adults: A nationwide cross-sectional study

BACKGROUND

Chronic pain has emerged as a significant global public health concern. Hence, it is imperative to acquire a more comprehensive comprehension of these characteristics in the adult population of the United States in order to facilitate the development of effective interventions. The objective of this study is to ascertain the prevalence of chronic pain among people in the United States and investigate its association with C-reactive protein (CRP) levels.

METHODS

The present study employed a cross-sectional design and utilized data from three cycles of the National Health and Nutrition Examination Survey (NHANES). The study aimed to investigate the relationship between chronic pain status, CRP levels, and potential confounding factors. The study incorporated individuals who successfully fulfilled chronic questionnaires and had CRP assays. Weighted univariate and multivariate logistic regression analyses were performed to examine the correlation between chronic pain and CRP levels. To explore the non-linear relationship, weighted restricted cubic spline (RCS) with three knots coupled with a weighted logistic regression model to assess the dose-response relationship between CRP (continuous variables) and chronic pain.

RESULTS

A total of 10,680 (Weighted 250,814,660.8) adult participants with complete information were included in the analysis and 2612 (Weighted 67978784.88, 27.1%) subjects met the definition of chronic pain. Compared with participants without chronic pain, those with chronic pain had a higher CRP level (P < 0.001). The results of the multivariable adjusted logistic regression model suggested that the highest CRP quartile (CRP >  0.52 mg/dL) was associated with a 32% increase in the risk of chronic pain compared with the lowest CRP quartile (CRP ≤  0.09 mg/dL). The RCS result showed that the OR of chronic pain and CRP displayed a linear relationship (P = 0.027, Non-linear P = 0.541).

CONCLUSIONS

The study found a significant correlation between CRP levels and the presence of chronic pain among people in the United States. Individuals exhibiting elevated levels of CRP demonstrated a heightened propensity for experiencing chronic pain in comparison to individuals with lower CRP levels. Additional investigation is necessary to explore the presence of a causal association between the two variables, as well as the potential underlying mechanisms.

Remote-Customized Telecontrol for Patients with Rheumatoid Arthritis: The iARPlus (Innovative Approach in Rheumatology) Initiative

Objective. Telecontrol approaches for rheumatoid arthritis (RA) management aim to enhance patient outcomes. This pilot study assessed whether the Rheumatoid Arthritis Impact of Disease (RAID) approach could be used during teleconsultations to monitor RA disease activity through a web-based platform called iARPlus (Innovative Approach in Rheumatology). Methods. Forty RA patients participated in two in-person visits (baseline and 12 months) and seven teleconsultations over 12 months, collected via the iARPlus portal and accessible through an internet browser. Disease activity, at baseline and follow-up, was measured using the Clinical Disease Activity Index (CDAI) and self-reported RAID scores throughout the study. The RAID approach, developed by the European Alliance of Associations for Rheumatology (EULAR), combines key patient-reported outcomes (PROs). Results. Nineteen patients (mean age: 49.3 years) were treated with Janus kinase inhibitors (JAKis), and 21 patients (mean age: 48.1 years) received adalimumab. All patients had active disease (mean CDAI 27.9 ± 4.8). Strong correlations were found between CDAI and RAID scores at baseline (ρ = 0.809, p < 0.0001) and at follow-up (ρ = 0.789, p < 0.0001). JAKi-treated patients showed greater reductions in RAID scores, pain relief, and higher rates of disease remission compared to adalimumab-treated patients. Conclusions. RAID scores were effective in teleconsultations for assessing RA disease activity. JAKi treatment resulted in better pain control and disease activity improvement compared to adalimumab. Further studies are needed to confirm the clinical and economic benefits of telecontrol for RA management.

A Mediation Appraisal of Neuropathic-like Symptoms, Pain Catastrophizing, and Central Sensitization-Related Signs in Adults with Knee Osteoarthritis-A Cross-Sectional Study

Objective. To investigate the relationships among neuropathic pain (NP), pain catastrophizing (PC), and central sensitization (CS) in relation to functional status and radiological damage in patients with knee osteoarthritis (OA). Methods. This cross-sectional study included knee OA patients derived from an observational cohort. The Spearman correlation test was used to analyze the relationship between the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the PainDetect Questionnaire (PDQ), Central Sensitization Inventory (CSI), and Pain Catastrophizing Scale (PCS). The Kruskal-Wallis test was employed to compare WOMAC scores according to CSI categories. A multivariate analysis was conducted to identify predictors of functional ability, with the WOMAC score as the dependent variable and the independent variables including pain-related indices such as PCS, PDQ, and CSI, along with Kellgren-Lawrence (K-L) grading and demographic characteristics. Results. This study included 149 patients (76.5% female; mean age 71.5 years; mean duration of pain 8.1 years). In total, 23.5% exhibited NP, 30.9% showed PC, and 33.6% had CS. Higher mean values of WOMAC were correlated with CSI categories (p < 0.0001). WOMAC showed a significant relationship with CSI (rho = 0.791; p < 0.0001), PDQ (rho = 0.766; p < 0.0001), and PCS (rho = 0.536; p < 0.0001). In the multiple regression analysis, WOMAC was independently associated with CSI (p < 0.0001), PDQ (p < 0.0001), and PC (p = 0.0001). No association was observed between the K-L grading and the other variables. Conclusions. A reduced functional capacity in patients with knee OA is correlated with the presence of NP, PC and CS, without being significantly associated with radiological damage.

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Pain in axial spondyloarthritis: role of the JAK/STAT pathway

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that is characterized by new bone formation in the axial musculoskeletal system, with X-ray discriminating between radiographic and non-radiographic forms. Current therapeutic options include non-steroidal anti-inflammatory drugs in addition to biological disease-modifying anti-rheumatic drugs that specifically target tumor necrosis factor-alpha (TNFα) or interleukin (IL)-17. Pain is the most critical symptom for axSpA patients, significantly contributing to the burden of disease and impacting daily life. While the inflammatory process exerts a major role in determining pain in the early phases of the disease, the symptom may also result from mechanical and neuromuscular causes that require complex, multi-faceted pharmacologic and non-pharmacologic treatment, especially in the later phases. In clinical practice, pain often persists and does not respond further despite the absence of inflammatory disease activity. Cytokines involved in axSpA pathogenesis interact directly/indirectly with the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling cascade, a fundamental component in the origin and development of spondyloarthropathies. The JAK/STAT pathway also plays an important role in nociception, and new-generation JAK inhibitors have demonstrated rapid pain relief. We provide a comprehensive review of the different pain types observed in axSpA and the potential role of JAK/STAT signaling in this context, with specific focus on data from preclinical studies and data from clinical trials with JAK inhibitors.

The role of Janus kinase signaling in the pathology of atopic dermatitis

Atopic dermatitis (AD) is a heterogeneous, chronic, relapsing, inflammatory skin disease associated with considerable physical, psychological, and economic burden. The pathology of AD includes complex interactions involving abnormalities in immune and skin barrier genes, skin barrier disruption, immune dysregulation, microbiome disturbance, and other environmental factors. Many of the cytokines involved in AD pathology, including IL-4, IL-13, IL-22, IL-31, thymic stromal lymphopoietin, and IFN-γ, signal through the Janus kinase (JAK)-signal transducer and activation of transcription (STAT) pathway. The JAK family includes JAK1, JAK2, JAK3, and tyrosine kinase 2; the STAT family includes STAT1, STAT2, STAT3, STAT4, STAT5A/B, and STAT6. Activation of the JAK-STAT pathway has been implicated in the pathology of several immune-mediated inflammatory diseases, including AD. However, the exact mechanisms of JAK-STAT involvement in AD have not been fully characterized. This review aims to discuss current knowledge about the role of the JAK-STAT signaling pathway and, specifically, the role of JAK1 in the pathology and symptomology of AD.

Role of JAK-STAT signaling pathway in pathogenesis and treatment of primary Sjögren's syndrome

ABSTRACT

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease with high prevalence and possible poor prognosis. Though the pathogenesis of pSS has not been fully elucidated, B cell hyperactivity is considered as one of the fundamental abnormalities in pSS patients. It has long been identified that Janus kinases-signal transducer and activator of transcription (JAK-STAT) signaling pathway contributes to rheumatoid arthritis and systemic lupus erythematosus. Recently, increasing numbers of studies have provided evidence that JAK-STAT pathway also has an important role in the pathogenesis of pSS via direct or indirect activation of B cells. Signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5 activated by various cytokines and ribonucleic acid contribute to pSS development, respectively or synergically. These results reveal the potential application of Janus kinase inhibitors for treatment of pSS, which may fundamentally improve the quality of life and prognosis of patients with pSS.

Exploring the Novel Dimension of Immune Interactions in Pain: JAK Inhibitors' Pleiotropic Potential

This review explores the link between immune interactions and chronic pain, offering new perspectives on treatment. It focuses on Janus kinase (JAK) inhibitors' potential in pain management. Immune cells' communication with neurons shapes neuroinflammatory responses, and JAK inhibitors' effects on pain pathways are discussed, including cytokine suppression and microglial modulation. This review integrates studies from rheumatoid arthritis (RA) pain and central sensitization to highlight connections between immune interactions and pain. Studies on RA joint pain reveal the shift from cytokines to sensitization. Neurobiological investigations into central sensitization uncover shared pathways in chronic pain. Clinical evidence supports JAK inhibitors' efficacy on pain-related outcomes and their effects on neurons and immune cells. Challenges and future directions are outlined, including interdisciplinary collaboration and dosing optimization. Overall, this review highlights JAK inhibitors' potential to target immune-mediated pain pathways, underscoring the need for more research on immune-pain connections.

Biopsychosocial factors should be considered when evaluating central sensitization in axial spondyloarthritis

To identify the determinants of central sensitization (CS) in patients with axial spondyloarthritis (axSpA). Central Sensitization Inventory (CSI) was used to determine CS frequency. Disease-related variables including Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS-CRP/-ESR), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Quality of Life Questionnaire (ASQoL) and Numeric Rating Scale (NRS)GLOBAL were assessed. Biopsychosocial variables were evaluated by the Multidimensional Scale of Perceived Social Support (MSPSS), Brief Illness Perception Questionnaire (B-IPQ), Hospital Anxiety and Depression Scale (HADS) and subscales for Anxiety (HADS-A) and Depression (HADS-D), and Jenkins Sleep Evaluation Scale (JSS). To determine the predictors of the development and severity of CS, multiple linear and logistic regression analyses were performed. The frequency of CS was 57.4% in the study population (n = 108). CSI score was correlated with the duration of morning stiffness, BASDAI, ASDAS-CRP, ASDAS-ESR, NRSGLOBAL, BASFI, MASES, ASOoL, JSS, HADS, and B-IPQ total scores (ρ ranged from 0.510 to 0.853). Multiple regression analysis indicated that BASDAI (OR: 10.44, 95% CI: 2.65-41.09), MASES (OR: 2.47, 95% CI: 1.09-5.56) and HADS-A (OR: 1.62, 95% CI: 1.11-2.37) were independent predictors of the development of CS. Additionally, higher NRSGLOBAL, JSS, HADS-D, and HADS-A scores appeared to determine the severity of CS. This study confirms that worse disease activity, more enthesal involvement, and anxiety independently predict the development of CS. Additionally, higher patient-perceived disease activity, sleep impairment and poor mental health significantly contribute to the severity of CS.

OASL knockdown inhibits the progression of stomach adenocarcinoma by regulating the mTORC1 signaling pathway

The present study investigated the effects of 2'-5' oligoadenylate synthetase-like (OASL) on the biological functions of stomach adenocarcinoma (STAD) cells and tumor formation in nude mice. The differential expression levels of OASL in the different cancer types from TCGA dataset were analyzed using gene expression profiling interactive analysis. Overall survival and the receiver operating characteristic were analyzed using the KM plotter and R, respectively. Furthermore, OASL expression and its effects on the biological functions of STAD cells were detected. The possible upstream transcription factors of OASL were predicted using JASPAR. The downstream signaling pathways of OASL were analyzed using GSEA. Tumor formation experiments were performed to evaluate the effect of OASL on tumor formation in nude mice. The results showed that OASL was highly expressed in STAD tissues and cell lines. OASL knockdown markedly inhibited cell viability, proliferation, migration, and invasion and accelerated STAD cell apoptosis. Conversely, OASL overexpression had the opposite effect on STAD cells. JASPAR analysis revealed that STAT1 is an upstream transcription factor of OASL. Furthermore, GSEA showed that OASL activated the mTORC1 signaling pathway in STAD. The protein expression levels of p-mTOR and p-RPS6KB1 were suppressed by OASL knockdown and promoted by OASL overexpression. The mTOR inhibitor, rapamycin, markedly reversed the effect of OASL overexpression on STAD cells. Additionally, OASL promoted tumor formation and increased tumor weight and volume in vivo. In conclusion, OASL knockdown suppressed the proliferation, migration, invasion, and tumor formation of STAD cells by inhibiting the mTOR signaling pathway.

Understanding the function of the GABAergic system and its potential role in rheumatoid arthritis

Rheumatoid arthritis (RA) is a highly disabling chronic autoimmune disease. Multiple factors contribute to the complex pathological process of RA, in which an abnormal autoimmune response, high survival of inflammatory cells, and excessive release of inflammatory factors lead to a severe chronic inflammatory response. Clinical management of RA remains limited; therefore, exploring and discovering new mechanisms of action could enhance clinical benefits for patients with RA. Important bidirectional communication occurs between the brain and immune system in inflammatory diseases such as RA, and circulating immune complexes can cause neuroinflammatory responses in the brain. The gamma-aminobutyric acid (GABA)ergic system is a part of the nervous system that primarily comprises GABA, GABA-related receptors, and GABA transporter (GAT) systems. GABA is an inhibitory neurotransmitter that binds to GABA receptors in the presence of GATs to exert a variety of pathophysiological regulatory effects, with its predominant role being neural signaling. Nonetheless, the GABAergic system may also have immunomodulatory effects. GABA/GABA-A receptors may inhibit the progression of inflammation in RA and GATs may promote inflammation. GABA-B receptors may also act as susceptibility genes for RA, regulating the inflammatory response of RA via immune cells. Furthermore, the GABAergic system may modulate the abnormal pain response in RA patients. We also summarized the latest clinical applications of the GABAergic system and provided an outlook on its clinical application in RA. However, direct studies on the GABAergic system and RA are still lacking; therefore, we hope to provide potential therapeutic options and a theoretical basis for RA treatment by summarizing any potential associations.

Identifying and Quantifying the Role of Inflammation in Pain Reduction for Patients With Psoriatic Arthritis Treated With Tofacitinib: A Mediation Analysis

INTRODUCTION

Pain is a multidimensional factor and core domain of psoriatic arthritis (PsA). This analysis aimed to quantify the role of potential inflammation-associated outcomes on pain reduction in patients with PsA receiving tofacitinib, using mediation modeling.

METHODS

Pooled data were from two phase 3 studies (OPAL Broaden and OPAL Beyond) of patients with active PsA treated with tofacitinib 5 mg twice daily or placebo. Mediation modeling was utilized to quantify the indirect effects (via Itch Severity Item [ISI], C-reactive protein [CRP] levels, swollen joint count [SJC], Psoriasis Area and Severity Index [PASI], and enthesitis [using Leeds Enthesitis Index]) and direct effects (representing all other factors) of tofacitinib treatment on pain improvement.

RESULTS

The initial model showed that tofacitinib treatment affects pain, primarily indirectly, via ISI, CRP, SJC, PASI, and enthesitis (overall 84.0%; P = 0.0009), with 16.0% (P = 0.5274) attributable to the direct effect. The model was respecified to exclude SJC and PASI. Analysis of the final model revealed that 29.5% (P = 0.0579) of tofacitinib treatment effect on pain was attributable to the direct effect, and 70.5% (P < 0.0001) was attributable to the indirect effect. ISI, CRP, and enthesitis mediated 37.4% (P = 0.0002), 15.3% (P = 0.0107), and 17.8% (P = 0.0157) of the tofacitinib treatment effect on pain, respectively.

CONCLUSIONS

The majority of the effect of tofacitinib on pain was collectively mediated by itch, CRP, and enthesitis, with itch being the primary mediator of treatment effect.

TRIAL REGISTRATION

NCT01877668, NCT01882439. GRAPHICAL PLS.

Effect of biological DMARDs and JAK inhibitors in pain of chronic inflammatory arthritis

INTRODUCTION

The advent of biological disease-modifying anti-rheumatic drugs (bDMARDs) and, more recently, of Janus kinase inhibitors (JAKi) has had a major impact on the long-term outcomes of chronic inflammatory arthritis (IA). However, the persistence of pain, even in patients with a complete pharmacological control of peripheral inflammation, represents an important clinical challenge in the treatment of IA.

AREAS COVERED

In this review, we provide an overview of possible mechanisms underlying pain in IA and its assessment, as well as the effects of bDMARDs and JAKi on pain management.

EXPERT OPINION

The overall data showed a good effect of bDMARDs and JAKi on pain, more pronounced for JAKi. However, it is challenging to distinguish the effect on the different types of pain (nociceptive, neuropathic, and nociplastic).

Interplay between exosomes and autophagy machinery in pain management: State of the art

Despite recent progress regarding inexpensive medical approaches, many individuals suffer from moderate to severe pain globally. The discovery and advent of exosomes, as biological nano-sized vesicles, has revolutionized current knowledge about underlying mechanisms associated with several pathological conditions. Indeed, these particles are touted as biological bio-shuttles with the potential to carry specific signaling biomolecules to cells in proximity and remote sites, maintaining cell-to-cell communication in a paracrine manner. A piece of evidence points to an intricate relationship between exosome biogenesis and autophagy signaling pathways at different molecular levels. A close collaboration of autophagic response with exosome release can affect the body's hemostasis and physiology of different cell types. This review is a preliminary attempt to highlight the possible interface of autophagy flux and exosome biogenesis on pain management with a special focus on neuropathic pain. It is thought that this review article will help us to understand the interplay of autophagic response and exosome biogenesis in the management of pain under pathological conditions. The application of therapies targeting autophagy pathway and exosome abscission can be an alternative strategy in the regulation of pain.

Role of N-Methyl-D-Aspartate Receptor NR2B Subunit in Inflammatory Arthritis-Induced Chronic Pain and Peripheral Sensitized Neuropathic Pain: A Systematic Review

Arthritis is a common clinical disease that affects millions of people in the world. The most common types of arthritis are osteoarthritis and rheumatoid arthritis. Inflammatory arthritis (IA), a chronic painful disease, is characterized by synovitis and cartilage destruction in the early stages. Pathologically, IA causes inflammatory changes in the joints and eventually leads to joint destruction. Pain is associated with inflammation and abnormal regulation of the nervous system pathways involved in pain promotion and inhibition. In addition, the occurrence of pain is associated with depression and anxiety. We found that there are many factors affecting pain, in addition to inflammatory factors, glutamate receptor may be the possible cause of long-term chronic pain caused by IA. N-methyl-d-aspartate receptor subunit 2B (NR2B) has been reported to involved in IA and nervous system diseases, especially peripheral neuropathic pain. In this review, we summarized the mechanisms of the NR2B subunit of the N-methyl-D-aspartate (NMDA) receptor in peripheral nerve sensitization during IA and chronic pain.

Janus kinase inhibitors in immunoinflammatory diseases: 10 years of clinical practice in rheumatology

Despite great advances in the diagnosis and treatment of Immune-mediated inflammatory diseases (IMIDs), which have led to a significant improvement in the prognosis in many patients, the central medical problems of this pathology – restoring the quality of life and reducing mortality to the population level – are far from being resolved. This served as a powerful stimulus for the study of new approaches to the pharmacotherapy of IMIDs, one of which is associated with the discovery of targets for small-molecule therapeutics that inhibit intracellular “signaling” molecules JAKs (Janus kinases). The current achievements, trends and recommendations regarding the use of JAK inhibitors in the treatment of IMIDs and also in the hyper-response phase of COVID-19 are reviewed.

Early response to JAK inhibitors on central sensitization and pain catastrophizing in patients with active rheumatoid arthritis

Objectives

To evaluate the effect of 4 weeks of treatment with Janus kinase inhibitors (JAKis) on central sensitization (CS) and pain catastrophizing, and to determine the pain-related variables predictive of disease activity improvement, in patients with active rheumatoid arthritis (RA).

Methods

Consecutive RA patients with active disease starting a JAKi have been enrolled in this prospective observational study. Patients have been assessed at baseline and after 4 weeks of treatment. The evaluation was comprehensive of disease activity [Simplified Disease Activity Index (SDAI) and ultrasonographic (US) score] and of questionnaires aimed at investigating primarily CS [Central Sensitization Inventory (CSI)] and pain catastrophizing [Pain Catastrophizing Scale (PCS)]. Differences (Δ values) between the final and baseline were studied with the t test, Δ values of the variables were correlated with each other using Pearson’s test, and predictor variables for improvement in SDAI were also investigated using multivariate regression analysis.

Results

A total of 115 patients were evaluated. Overall, all variables demonstrated significant improvement between baseline and final except the US score. In particular, CSI decreased from 36.73 to 32.57 (p < 0.0001), PCS decreased from 32.46 to 28.72 (p = 0.0001). ΔSDAI showed a significant correlation with both ΔPCS and ΔCSI (r = 0.466 and 0.386, respectively, p < 0.0001). ΔPCS was the only variable predictive of an improvement in SDAI (coefficient = 0.500, p = 0.0224).

Conclusion

JAKis would appear to have a positive effect on pain-related variables, particularly CS and pain catastrophizing, for the genesis of which extra-synovial mechanisms are responsible.

Toxic Effects of Endocrine Disruptor Exposure on Collagen-Induced Arthritis

Endocrine disruptors (EDs) are chemical substances capable of affecting endocrine system functioning and interfering with organ morphogenesis and physiological functions. The development and regeneration of bone tissues have a complex hormonal regulation, and therefore, bone tissue cells can be considered potential targets for endocrine disruptors. In that regard, the aim of this research was to investigate the impact of ED exposure on the inflammatory response and oxidative stress in an experimental model of collagen-induced arthritis (CIA). Arthritis was induced by an emulsion of type II collagen (CII) and complete Freund’s adjuvant, which was administered intradermally on days 0 and 21. Mice from day 21 to day 35 received the following EDs by oral gavage: cypermethrin (CP), diethyl phthalate (DEP), vinclozolin (VCZ), 17α-ethinylestradiol (EE), perfluorooctanesulfonic acid (PFOS) and atrazine (ATR). ED exposure caused worsening of clinical signs (erythema and edema in the hind paws), histological and radiographic changes, as well as behavioral deficits, induced by CII injections. Furthermore, ED exposure significantly increased the degree of inflammation and oxidative damage induced by arthritis; this upregulation was more evident after exposure to ATR than to other EDs. The results from our study suggest that exposure to EDs may play a deleterious role in the progression of RA; therefore, exposure to EDs should be limited.

Effect of upadacitinib on reducing pain in patients with active psoriatic arthritis or ankylosing spondylitis: post hoc analysis of three randomised clinical trials

Objective

Evaluate the effect of upadacitinib on pain outcomes in patients with active psoriatic arthritis (PsA) or ankylosing spondylitis (AS) across 3 randomised trials (SELECT-PsA 1 and 2 for PsA; SELECT-AXIS 1 for AS).

Methods

Patients were randomised to upadacitinib 15 mg once daily or placebo (all 3 studies), or adalimumab 40 mg every other week (SELECT-PsA 1 only). Pain outcomes included proportion of patients achieving ≥30%, ≥50% and ≥70% reduction from baseline in patient global assessment of pain and other end points.

Results

A higher proportion of patients receiving upadacitinib versus placebo achieved ≥30%, ≥50% and ≥70% reduction in pain end points as early as week 2; these improvements with upadacitinib were generally sustained or increased through year 1 (PsA 1/2 studies: 64%/48%, 58%/42% and 38%/22%, respectively; SELECT-AXIS 1 study: 76%, 72% and 54%). Results were similar with adalimumab in PsA 1 (59%, 49% and 32%). Patients who switched from placebo to upadacitinib 15 mg were able to reach a similar level of improvement as the continuous upadacitinib groups by year 1 (PsA 1/2 studies: 46%–60%, 35%–49% and 15%–34%; AS study: 83%, 72% and 46%). Results were similar with other pain end points.

Conclusion

Rapid and sustained improvements in pain outcomes across several end points were consistently shown with upadacitinib over 1 year in patients with active PsA or AS who had either inadequate response to prior non-biologic or biologic disease-modifying antirheumatic drugs (PsA studies) or were biologic-naïve with inadequate response to non-steroidal anti-inflammatory drugs (AS study).

Extra-Articular Manifestations and Comorbidities in Psoriatic Disease: A Journey Into the Immunologic Crosstalk

Psoriatic arthritis (PsA) is a chronic inflammatory disease primarily affecting peripheral and axial joints, with the possible presence of extra-articular manifestations (EAMs), such as psoriasis, uveitis, and inflammatory bowel disease. Recently, the concept of psoriatic disease (PsD) has been proposed to define a systemic condition encompassing, in addition to joints and EAMs, some comorbidities (e.g., metabolic syndrome, type II diabetes, hypertension) that can affect the disease outcome and the achievement of remission. EAMs and comorbidities in PsA share common immunopathogenic pathways linked to the systemic inflammation of this disease; these involve a broad variety of immune cells and cytokines. Currently, various therapeutics are available targeting different cytokines and molecules implicated in the inflammatory response of this condition; however, despite an improvement in the management of PsA, comprehensive disease control is often not achievable. There is, therefore, a big gap to fill especially in terms of comorbidities and EAMs management. In this review, we summarize the clinical aspects of the main comorbidities and EAMs in PsA, and we focus on the immunopathologic features they share with the articular manifestations. Moreover, we discuss the effect of a diverse immunomodulation and the current unmet needs in PsD.

Minocycline alleviates nociceptive response through modulating the expression of NR2B subunit of NMDA receptor in spinal cord of rat model of painful diabetic neuropathy

Background

It has been reported that neuropathic pain can be overcome by targeting the NR2B subunit of N-methyl-D-aspartate receptors (NR2B). This study aimed to investigate the effects of minocycline on phosphorylated and total expression of NR2B in the spinal cord of rats with diabetic neuropathic pain.

Methods

A total of 32 Sprague-Dawley male rats were randomly assigned into four groups (n = 8); control healthy, control diabetic (PDN), and PDN rats that received 80 µg or 160 µg intrathecal minocycline respectively. The rats were induced to develop diabetes and allowed to develop into the early phase of PDN for two weeks. Hot-plate and formalin tests were conducted. Intrathecal treatment of minocycline or normal saline was conducted for 7 days. The rats were sacrificed to obtain the lumbar enlargement region of the spinal cord (L4-L5) for immunohistochemistry and western blot analyses to determine the expression of phosphorylated (pNR2B) and total NR2B (NR2B).

Results

PDN rats showed enhanced flinching (phase 1: p < 0.001, early phase 2: p < 0.001, and late phase 2: p < 0.05) and licking responses (phase 1: p < 0.001 and early phase 2: p < 0.05). PDN rats were also associated with higher spinal expressions of pNR2B and NR2B (p < 0.001) but no significant effect on thermal hyperalgesia. Minocycline inhibited formalin-induced flinching and licking responses (phase 1: p < 0.001, early phase 2: p < 0.001, and late phase 2: p < 0.05) in PDN rats with lowered spinal expressions of pNR2B (p < 0.01) and NR2B (p < 0.001) in a dose-dependent manner.

Conclusion

Minocycline alleviates nociceptive responses in PDN rats, possibly via suppression of NR2B activation. Therefore, minocycline could be one of the potential therapeutic antinociceptive drugs for the management of neuropathic pain.

Baricitinib in the treatment of rheumatoid arthritis: clinical and ultrasound evaluation of a real-life single-centre experience

Background:

Ultrasound (US) is useful in monitoring RA patients, with the US7 score allowing grey-scale and power-Doppler (PD) semi-quantitative evaluation of synovitis and teno-synovitis. We evaluated real-life efficacy and safety of Baricitinib, an oral selective JAK1-2 inhibitor, in RA patients using clinical, clinimetric, and US assessments.

Methods:

Disease activity score in 28 joints calculated with C-reactive protein (DAS28-CRP), disease activity score in 28 joints calculated with erythrocyte sedimentation rate (DAS28-ESR), clinical disease activity index (CDAI), simplified disease activity index (SDAI), visual analogue scale (VAS)-pain, health assessment questionnaire (HAQ), COCHIN scale, adverse events (AE), concomitant medications, laboratory parameters, and US7 were performed/recorded at baseline, 1, 3, and 6 months in RA patients starting Baricitinib. Responder/non-responder status was determined according to the EULAR Response Criteria at 3 months. SDAI clinical remission or low disease activity (LDA) were calculated at 3 and 6 months.

Results:

In 43 enrolled patients, a significant improvement in disease activity and US7 components (except tendon PD) and a reduction of steroid dosage were observed. Responders at 3 months showed a significantly higher reduction of CDAI, SDAI, COCHIN scale, VAS-pain, and US7 synovialPD, compared with non-responders. At 3 and 6 months, remission/LDA was achieved by 12.8/53.8% and 21.6/51.3% patients, respectively. The csDMARD co-treatment was independently associated with remission/LDA at 3 months. Safety-related drop-outs were in line with literature data. The steroid dosage was associated with AE development at 6 months.

Conclusion:

The real-life data, also obtained with US evaluation, confirmed the Baricitinib efficacy in RA disease control, as well as the utility of assessment during the follow up of disease activity.

Recent Advances in Pain Management: Relevant Protein Kinases and Their Inhibitors

The purpose of this review is to underline the protein kinases that have been established, either in fundamental approach or clinical trials, as potential biological targets in pain management. Protein kinases are presented according to their group in the human kinome: TK (Trk, RET, EGFR, JAK, VEGFR, SFK, BCR-Abl), CMGC (p38 MAPK, MEK, ERK, JNK, ASK1, CDK, CLK2, DYRK1A, GSK3, CK2), AGC (PKA, PKB, PKC, PKMζ, PKG, ROCK), CAMK, CK1 and atypical/other protein kinases (IKK, mTOR). Examples of small molecule inhibitors of these biological targets, demonstrating an analgesic effect, are described. Altogether, this review demonstrates the fundamental role that protein kinase inhibitors could play in the development of new pain treatments.

Mechanisms and Mediators of Pain in Chronic Inflammatory Arthritis

Purpose of the review

Pain in chronic inflammatory joint diseases is a common symptom reported by patients. Pain becomes of absolute clinical relevance especially when it becomes chronic, i.e., when it persists beyond normal healing times. As an operational definition, pain is defined chronic when it lasts for more than 3 months. This article aims to provide a review of the main mechanisms underlying pain in patients with chronic inflammatory joint diseases, discussing in particular their overlap.

Recent findings

While it may be intuitive how synovial inflammation or enthesitis are responsible for nociceptive pain, in clinical practice, it is common to find patients who continue to complain of symptoms despite optimal control of inflammation. In this kind of patients at the genesis of pain, there may be neuropathic or nociplastic mechanisms.

Summary

In the context of chronic inflammatory joint diseases, multiple mechanisms generally coexist behind chronic pain. It is the rheumatologist’s task to identify the mechanisms of pain that go beyond the nociceptive mechanisms, to adopt appropriate therapeutic strategies, including avoiding overtreatment of patients with immunosuppressive drugs. In this sense, future research will have to be oriented to search for biomarkers of non-inflammatory pain in patients with chronic inflammatory joint diseases.

The changes of nociception and the signal molecules expression in the dorsal root ganglia and the spinal cord after cold water swimming stress in mice

Several studies have previously reported that exposure to stress provokes behavioral changes, including antinociception, in rodents. In the present study, we studied the effect of acute cold-water (4°C) swimming stress (CWSS) on nociception and the possible changes in several signal molecules in male ICR mice. Here, we show that 3 min of CWSS was sufficient to produce antinociception in tail-flick, hot-plate, von-Frey, writhing, and formalin-induced pain models. Significantly, CWSS strongly reduced nociceptive behavior in the first phase, but not in the second phase, of the formalin-induced pain model. We further examined some signal molecules' expressions in the dorsal root ganglia (DRG) and spinal cord to delineate the possible molecular mechanism involved in the antinociceptive effect under CWSS. CWSS reduced p-ERK, p-AMPKα1, p-AMPKα2, p-Tyk2, and p-STAT3 expression both in the spinal cord and DRG. However, the phosphorylation of mTOR was activated after CWSS in the spinal cord and DRG. Moreover, p-JNK and p-CREB activation were significantly increased by CWSS in the spinal cord, whereas CWSS alleviated JNK and CREB phosphorylation levels in DRG. Our results suggest that the antinociception induced by CWSS may be mediated by several molecules, such as ERK, JNK, CREB, AMPKα1, AMPKα2, mTOR, Tyk2, and STAT3 located in the spinal cord and DRG.

Post-mTBI Pain Interference in a U.S. Military Population: A Chronic Effects of Neurotrauma Consortium Study

INTRODUCTION

Chronic pain is a significant problem for service members and veterans with mild traumatic brain injury (mTBI). While the root cause of pain is not clearly understood, comorbidities may contribute to how their pain disrupts their functional status, a construct termed "pain interference." The purpose of this study is to examine the associations between mTBI, other comorbidities, and pain interference.

MATERIALS AND METHODS

The sample comprised participants with mTBI(s) from The Chronic Effects of Neurotrauma Consortium multicenter observational study. Potential concussive events were identified using a modified Ohio State University traumatic brain injury (TBI) Identification interview and then further with a structured interview. Pain interference was measured with the TBI quality-of-life pain interference score, which was categorized into insignificant, moderate, and high pain interference. Comorbidities of interest included anxiety, depression, post-traumatic stress disorder, insomnia, and arthritis. Multivariable relationships were analyzed using logistic regression.

RESULTS

The analysis sample included 346 participants with mTBI(s). In adjusted analysis, those with high pain interference were more likely to have history of ≥ 3 TBIs (odds ratio (OR) 3.1, 95% confidence interval [CI] 1.4, 6.9) and to have clinical levels of post-traumatic stress disorder (OR 5.4, 95% CI 1.9, 15.7), depression (OR 2.5, 95% CI, 1.0, 6.1), anxiety (OR 4.9, 95% CI, 2.0, 11.7), and sleep disturbances (OR 6.1, 95% CI 2.0, 19.0) versus those with insignificant pain interference.

CONCLUSION

These results identify clinical features of veterans and service members with mTBI(s) who are at highest risk for pain-related disability. These findings also demonstrate the need to consider mental health and sleep problems in their pain evaluation and treatment approach.

Early Life Nociception is Influenced by Peripheral Growth Hormone Signaling

A number of cellular systems work in concert to modulate nociceptive processing in the periphery, but the mechanisms that regulate neonatal nociception may be distinct compared with adults. Our previous work indicated a relationship between neonatal hypersensitivity and growth hormone (GH) signaling. Here, we explored the peripheral mechanisms by which GH modulated neonatal nociception under normal and injury conditions (incision) in male and female mice. We found that GH receptor (GHr) signaling in primary afferents maintains a tonic inhibition of peripheral hypersensitivity. After injury, a macrophage dependent displacement of injury-site GH was found to modulate neuronal transcription at least in part via serum response factor (SRF) regulation. A single GH injection into the injured hindpaw muscle effectively restored available GH signaling to neurons and prevented acute pain-like behaviors, primary afferent sensitization, and neuronal gene expression changes. GH treatment also inhibited long-term somatosensory changes observed after repeated peripheral insult. Results may indicate a novel mechanism of neonatal nociception.SIGNIFICANCE STATEMENT Although it is noted that mechanisms of pain development in early life are unique compared with adults, little research focuses on neonatal-specific peripheral mechanisms of nociception. This gap is evident in the lack of specialized care for infants following an injury including surgeries. This report evaluates how distinct cellular systems in the periphery including the endocrine, immune and nervous systems work together to modulate neonatal-specific nociception. We uncovered a novel mechanism by which muscle injury induces a macrophage-dependent sequestration of peripheral growth hormone (GH) that effectively removes its normal tonic inhibition of neonatal nociceptors to promote acute pain-like behaviors. Results indicate a possible new strategy for treatment of neonatal postsurgical pain.

Efficacy of tofacitinib in reducing pain in patients with rheumatoid arthritis, psoriatic arthritis or ankylosing spondylitis

Objective

To describe the efficacy of tofacitinib in reducing pain in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) or ankylosing spondylitis (AS) in a post-hoc analysis of randomised controlled trials.

Methods

Data were collected from patients in seven tofacitinib studies: six phase III (four RA, two PsA) and one phase II study (AS), and grouped into five analysis populations based on rheumatic disease diagnosis and category of prior inadequate response (IR) to treatment: conventional synthetic disease-modifying antirheumatic drugs-IR (RA and PsA), tumour necrosis factor inhibitors-IR (RA and PsA), or non-steroidal anti-inflammatory drugs-IR (AS). Only patients who received tofacitinib 5 or 10 mg twice daily or placebo were included. Pain assessments included: Patient’s Assessment of Arthritis Pain, Short-Form Health Survey 36v2 Question (Q)7 and Bodily Pain domain, Ankylosing Spondylitis Quality of Life Q9 and Q14, EuroQol Five Dimensions Pain/Discomfort dimension and Bath Ankylosing Spondylitis Disease Activity Index Q2 and Q3. Data were reported to month 6 (placebo to month 3) in the RA and PsA populations, and week 12 (tofacitinib and placebo) in the AS population.

Results

Overall, 3330 patients were included in this analysis. In the RA and PsA populations, pain improvements in tofacitinib-treated patients compared with placebo were observed at the earliest time point assessed and at month 3 (maintained to month 6). In the AS population, pain improvements compared with placebo were observed at week 12.

Conclusion

Tofacitinib was associated with rapid and sustained improvements across multiple pain measures in patients with inflammatory rheumatic musculoskeletal diseases.

Advances in imaging technologies for the assessment of peripheral neuropathies in rheumatoid arthritis

Peripheral neuropathy in patients with rheumatoid arthritis is associated with a maladaptive autoimmune response that may cause chronic pain and disability. Nerve conduction studies are the routine method performed when rheumatologists presume its presence. However, this approach is invasive, may not reveal subtle malfunctions in the early stages of the disease, and does not expose abnormalities in structures surrounding the nerves and muscles, limiting the possibility of a timely diagnosis. This work aims to present a narrative review of new technologies for the clinical assessment of peripheral neuropathy in Rheumatoid Arthritis. Through a bibliographic search carried out in five repositories, from 1990 to 2020, we identified three technologies that could detect peripheral nerve lesions and perform quantitative evaluations: (1) magnetic resonance neurography, (2) functional magnetic resonance imaging, and (3) high-resolution ultrasonography of peripheral nerves. We found these tools can overcome the main constraints imposed by the previous electrophysiologic methods, enabling early diagnosis.

An Investigation of the Molecular Mechanisms Underlying the Analgesic Effect of Jakyak-Gamcho Decoction: A Network Pharmacology Study

Herbal drugs have drawn substantial interest as effective analgesic agents; however, their therapeutic mechanisms remain to be fully understood. To address this question, we performed a network pharmacology study to explore the system-level mechanisms that underlie the analgesic activity of Jakyak-Gamcho decoction (JGd; Shaoyao-Gancao-Tang in Chinese and Shakuyaku-Kanzo-To in Japanese), an herbal prescription consisting of Paeonia lactiflora Pallas and Glycyrrhiza uralensis Fischer. Based on comprehensive information regarding the pharmacological and chemical properties of the herbal constituents of JGd, we identified 57 active chemical compounds and their 70 pain-associated targets. The JGd targets were determined to be involved in the regulation of diverse biological activities as follows: calcium- and cytokine-mediated signalings, calcium ion concentration and homeostasis, cellular behaviors of muscle and neuronal cells, inflammatory response, and response to chemical, cytokine, drug, and oxidative stress. The targets were further enriched in various pain-associated signalings, including the PI3K-Akt, estrogen, ErbB, neurotrophin, neuroactive ligand-receptor interaction, HIF-1, serotonergic synapse, JAK-STAT, and cAMP pathways. Thus, these data provide a systematic basis to understand the molecular mechanisms underlying the analgesic activity of herbal drugs.

The Jak/STAT pathway: A focus on pain in rheumatoid arthritis

Pain is a manifestation of rheumatoid arthritis (RA) that is mediated by inflammatory and non-inflammatory mechanisms and negatively affects quality of life. Recent findings from a Phase 3 clinical trial showed that patients with RA who were treated with a Janus kinase 1 (Jak1) and Janus kinase 2 (Jak2) inhibitor achieved significantly greater improvements in pain than those treated with a tumor necrosis factor blocker; both treatments resulted in similar changes in standard clinical measures and markers of inflammation. These findings suggest that Jak1 and Jak2 inhibition may relieve pain in RA caused by inflammatory and non-inflammatory mechanisms and are consistent with the overarching involvement of the Jak-signal transducer and activator of transcription (Jak/STAT) pathway in mediating the action, expression, and regulation of a multitude of pro- and anti-inflammatory cytokines. In this review, we provide an overview of pain in RA, the underlying importance of cytokines regulated directly or indirectly by the Jak/STAT pathway, and therapeutic targeting of the Jak/STAT pathway in RA. As highlighted herein, multiple cytokines directly or indirectly regulated by the Jak/STAT pathway play important roles in mediating various mechanisms underlying pain in RA. Having a better understanding of these mechanisms may help clinicians make treatment decisions that optimize the control of inflammation and pain.

Associations between Patient Global Assessment scores and pain, physical function, and fatigue in rheumatoid arthritis: a post hoc analysis of data from phase 3 trials of tofacitinib

Background

Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). We examined the degree to which Patient Global Assessment of Disease Activity (PtGA) was driven by patient-reported assessments of pain (Pain), physical function, and fatigue in patients receiving tofacitinib 5 mg twice daily or placebo, each with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs).

Methods

This post hoc analysis used data pooled from three randomized controlled trials in csDMARD-inadequate responder (csDMARD-IR) patients (ORAL Scan: NCT00847613; ORAL Standard: NCT00853385; ORAL Sync: NCT00856544). Using subgroup analysis from 2 × 2 tables, associations between PtGA and Pain, Health Assessment Questionnaire-Disability Index (HAQ-DI), and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) at month 3 were evaluated using Pearson’s Phi correlation coefficients. To support the main analysis, associations between select patient-reported outcomes (PROs) were also evaluated in csDMARD-naïve (ORAL Start; NCT01039688) and biologic (b)DMARD-IR (ORAL Step; NCT00960440) patients.

Results

Across csDMARD-IR treatment groups, low disease activity (defined as PtGA ≤ 20 mm), and moderate (≥ 30%) and substantial (≥ 50%) improvements from baseline in PtGA were associated with mild Pain (Visual Analog Scale score ≤ 20 mm), and moderate (≥ 30%) and substantial (≥ 50%) improvements from baseline in Pain; lack of Pain improvement was associated with little/no improvement in PtGA. In contrast, large proportions of csDMARD-IR patients who reported PtGA improvements did not report HAQ-DI or FACIT-F scores ≥ normative values (≤ 0.25 and ≥ 43.5, respectively) or changes in HAQ-DI or FACIT-F scores ≥ minimum clinically important difference (≥ 0.22 and ≥ 4.0, respectively). Generally, PtGA and Pain outcomes were moderately-to-strongly correlated at month 3 in csDMARD-IR patients, with weaker correlations evident between PtGA and HAQ-DI/FACIT-F outcomes. Similar findings were generally evident in csDMARD-naïve and bDMARD-IR patients.

Conclusions

This analysis supports the role of Pain as a key driver of PtGA in RA; physical function and fatigue play lesser roles in patients’ perceptions of disease activity. These findings corroborate the importance of improved PROs and attainment of low symptom states for optimizing patient care.

Trial registration

Clinicaltrials.gov: NCT00847613 (registered: February 19, 2009); NCT00853385 (registered: March 2, 2009); NCT00856544 (registered: March 5, 2009); NCT01039688 (registered: December 25, 2009); NCT00960440 (registered: August 17, 2009)

Pain and Neuropathic Pain in Rheumatic Diseases

Pain is a challenge to rheumatologists. Not only patients with active arthritis but also patients with a good therapeutic response and even in remission complain of persistent joint pain. It has been proposed that a chronic pain stimulus may have a greater impact in a chronic inflammatory state, and the process towards a pain condition may be influenced by individual predisposition for development of chronic pain. In addition, features of peripheral pain processing may be exacerbated by inflammation, and disturbed pain processing may be a feature contributing to widespread pain. Furthermore, a neuropathic component may be part of the total pain experience of our patients. There are many different strategies of pain therapy in patients with rheumatic diseases, such as pharmacological and non- pharmacological modalities.

Astrocytic NDRG2 is critical in the maintenance of neuropathic pain

Activation of astrocytes and abnormal synaptic glutamate metabolism are closely associated with the induction and maintenance of neuropathic pain (NP), but the exact mechanism underlying this association remains unclear. N-myc downstream-regulated gene 2 (NDRG2), a novel tumor-suppressor protein and stress-response gene, is involved in the pathogenesis of several neurodegenerative diseases. However, its role in nociceptive transduction has rarely been investigated. Here, we found that NDRG2, which was mainly expressed in the astrocytes in the central nervous system (CNS), was increased in the spinal cord of a spinal nerve ligation (SNL) rat model for NP. Suppression of NDRG2 by intrathecal injection of an NDRG2-RNAi-adenovirus significantly alleviated SNL-induced mechanical and thermal hypersensitivity, as well as elevated astrocytic glutamate transporter 1 (GLT-1) expression and downregulated pro-inflammatory cytokine levels, in the spinal dorsal horn of rats on Day 10 after SNL. Furthermore, in lipopolysaccharide (LPS)-stimulated primary astrocytic cultures derived from neonatal rats, inhibition of NDRG2 significantly reversed both the LPS-induced activation of astrocytes and decreased expression of GLT-1. By contrast, overexpression of NDRG2 by an adenoviral vector carrying NDRG2 resulted in astrocytic activation, aberrant glutamatergic neurotransmission, and spontaneous nociceptive responses in rats. Intrathecal injection of AG490, which is an inhibitor of the Janus tyrosine kinase and signal transducer and activator of the transcription 3 (JAK/STAT3) signaling pathway, significantly attenuated both mechanical and thermal hyperalgesia, as well as inhibited reactive astrocytes and restored normal expression levels of astrocytic GLT-1, in the spinal dorsal horn of NDRG2-overexpression rats. In conclusion, spinal astrocytic NDRG2 is critical in the maintenance of NP. Moreover, NDRG2 modulates astrocytic activation and inflammatory responses via regulating GLT-1 expression through the JAK/STAT3 signaling pathway. Our findings suggested that NDRG2 could be a novel therapeutic target for the treatment of NP.

JAK/STAT pathway in pathology of rheumatoid arthritis (Review)

Rheumatoid arthritis (RA) is classified as an inflammatory, chronic autoimmune and disabling disease based on the intricate interplay between environmental and genetic factors. With a prevalence ranging from 0.3 to 1%, RA is the most prevalent inflammatory joint disease observed in adults. Disruption of immune tolerance becomes evident when abnormal stimulation of the innate and adaptive immune system occurs. This cascade of events causes persistent joint inflammation, proliferative synovitis and, ultimately, damage of the underlying cartilage as well as the subchondral bone, leading to permanent joint destruction, deformity and subsequent loss of function. With cytokines being the key to a multitude of biological processes, including inflammation, hematopoiesis and overall immune response, one must inevitably look at the main pathways through which a significant number of those molecules exert their function. Janus kinase/signal transducers and activators of transcription (JAK/STATs) represent one such pathway and, recently, JAK inhibitors (JAKinibs) have shown promise in the treatment of several inflammatory diseases, including RA. This narrative review focuses on the intricate signaling pathways involved as well as on the clinical aspects and safety profiles of JAKinibs approved for the treatment of RA.

Patient-Centered Care in Psoriatic Arthritis-A Perspective on Inflammation, Disease Activity, and Psychosocial Factors

Psoriatic arthritis (PsA) is a seronegative spondyloarthropathy characterized by skin lesions, dactylitis, and enthesitis. Patients with PsA suffer from a variety of psychosocial difficulties and nonspecific symptoms early on in the disease course and continue to experience progressive disease due to delays in diagnosis and treatment. Symptoms initially viewed as somatization could lead to undertreatment and promote psychological distress, poor coping, and negative patient-provider relationships. Pain and fatigue are important complaints that affect the patient's perception and may need to be addressed with a multidisciplinary approach. Maladaptive cognitive responses can lead to a negative illness perception and impact patient beliefs and concerns over treatment, as well as nonadherence. An underlying inflammatory component in affective disorders has been examined, though whether and how it may interact mechanistically in PsA warrants interest. Cognitive behavioral therapy represents a nonpharmacological treatment modality that can be combined with cytokine-targeted therapy to address both somatic and psychological complaints. Future directions for research include: (1) Elucidating nonspecific manifestations (e.g., subclinical stage, differential with functional syndromes) of PsA and how they impact diagnosis and management; (2) characterizing immune-mediated components of mood disorders in PsA; and (3) whether a bidirectional approach with abrogating inflammation and psychotherapeutic support leads to improved outcomes.

JAK Inhibitors in Rheumatoid Arthritis: An Evidence-Based Review on the Emerging Clinical Data

Janus kinase (JAK) Inhibitors are the latest drug class of disease-modifying medication to emerge for the treatment of rheumatoid arthritis (RA). They are a small molecule-targeted treatment and are the first oral option to compare favourably to existing biologic disease-modifying anti-rheumatic drugs (DMARDs). Tofacitinib, baricitinib and upadacitinib are the first 3 JAK inhibitors to become commercially available in the field and are the core focus of this review. To date, they have demonstrated comparable efficacy to tumour necrosis factor (TNF) inhibitors in terms of American College of Rheumatology (ACR) response rates and disease activity (DAS28) scores with similar cost to the benchmark adalimumab. This narrative review article aims to synthesise and distil the key available trial data on JAK inhibitor efficacy and safety, along with their place in the ACR and European League Against Rheumatism (EULAR) guidelines for RA. The novel mechanism of action of the JAK/STAT pathway is highlighted along with the potential effects of modulating each pathway. The rapid onset of action, role in attenuation of central pain processing and effect on structural damage and radiographic progression are also all examined in detail. We also explore the latest meta-analyses and comparative performance of each of the 3 available JAKs in an effort to determine which is most efficacious and which has the most favourable safety profile. Post marketing concerns regarding thromboembolism risk and herpes zoster infection are also discussed. Additionally, we review the cost-benefit analyses of the available JAK inhibitors and address some of the pharmacoeconomic considerations for real-world practice in the UK and US by detailing the raw acquisition cost and the value they provide in comparison to the benchmark biologic adalimumab and the anchor DMARD methotrexate.

Peripheral mechanisms of arthritic pain: A proposal to leverage large animals for in vitro studies

Pain arising from musculoskeletal disorders such as arthritis is one of the leading causes of disability. Whereas the past 20-years has seen an increase in targeted therapies for rheumatoid arthritis (RA), other arthritis conditions, especially osteoarthritis, remain poorly treated. Although modulation of central pain pathways occurs in chronic arthritis, multiple lines of evidence indicate that peripherally driven pain is important in arthritic pain. To understand the peripheral mechanisms of arthritic pain, various in vitro and in vivo models have been developed, largely in rodents. Although rodent models provide numerous advantages for studying arthritis pathogenesis and treatment, the anatomy and biomechanics of rodent joints differ considerably to those of humans. By contrast, the anatomy and biomechanics of joints in larger animals, such as dogs, show greater similarity to human joints and thus studying them can provide novel insight for arthritis research. The purpose of this article is firstly to review models of arthritis and behavioral outcomes commonly used in large animals. Secondly, we review the existing in vitro models and assays used to study arthritic pain, primarily in rodents, and discuss the potential for adopting these strategies, as well as likely limitations, in large animals. We believe that exploring peripheral mechanisms of arthritic pain in vitro in large animals has the potential to reduce the veterinary burden of arthritis in commonly afflicted species like dogs, as well as to improve translatability of pain research into the clinic.

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.

BARICITINIB: NEW PHARMACOTHERAPY OPTIONS FOR RHEUMATOID ARTHRITIS AND OTHER IMMUNE-MEDIATED INFLAMMATORY RHEUMATIC DISEASES

Deciphering the mechanisms of the pathogenesis of immune-mediated inflammatory rheumatic diseases (IMIRDs) in conjunction with designing a wide range of biological agents is one of the major medical advances in the 21st century. A new promising area of pharmacotherapy for IMIRDs is associated with the design of the so-called targeted oral medications that primarily include Janus kinase (JAK) inhibitors. The review presents new data on the efficacy and safety of the new JAK inhibitor baricitinib in treating rheumatoid arthritis and other IMIRDs.

Unacceptable pain in the BARFOT inception cohort of patients with rheumatoid arthritis: a long-term study

Objectives: Pain is the most common and troublesome complaint in rheumatoid arthritis (RA). This study aimed to assess the prevalence and clinical implications of unacceptable pain in an inception cohort of patients with RA. Method: This study followed 477 patients from the BARFOT (Better Anti-Rheumatic FarmacOTherapy) early RA cohort for 15 years. Unacceptable pain was defined as ≥ 40 mm on a visual analogue scale for pain, while tolerable pain denoted no pain or pain below this cut-off, according to the patient acceptable symptom state concept. Results: Unacceptable pain was frequent. At the 15 year follow-up visit, 34% had unacceptable pain. Patients with unacceptable pain had, compared with patients with tolerable pain, significantly more disease activity, worse patient global assessment, and worse function on the Health Assessment Questionnaire and Signals of Functional Impairment, but the degree of joint destruction was similar. Disease-modifying anti-rheumatic drug treatment was similar, but patients with unacceptable pain were more often treated with corticosteroids. At 15 years, patients with unacceptable pain who were in remission (33%) had less inflammation and better function than those not in remission, suggesting the presence of non-inflammatory causes of pain. Conclusions: In this cohort of patients with RA, pain was frequent and severe, with negative effects on experienced health and function. Unacceptable pain was frequent and occurred also in patients in remission, indicating that pain in RA is multifactorial and should always be regarded as an important concern in itself. The cause of pain should be recognized and treated appropriately.

Chronotherapy targeting cytokine secretion attenuates collagen-induced arthritis in mice

OBJECTIVE

Diurnal variation of symptoms are observed in rheumatoid arthritis, especially in productions of cytokines that show peak concentrations during mid night. In contrast, cytokines of collagen-induced arthritis (CIA) mice increase in daytimes under Mid-light condition. By using chronotherapy, differences in drug efficacies according to administration time of Baricitinib, a wide ranged cytokine blocker, were examined in CIA mice.

METHODS

CIA mice were administered a dose of 3 mg/kg of Baricitinib once a day at zeitgeber time (ZT) 0 or ZT12 for 21 days. Arthritis scores, histopathology and factors related to joint destruction in sera were examined. Phosphorylation of STAT3 in liver, expressions of cytokines in spleen, and Interleukin (IL)-6 and tumor necrosis factor (TNF)-α in sera were measured.

RESULTS

In CIA mice, diurnal variations were observed both in expressions of cytokines and phosphorylation of STAT3. Arthritis scores of ZT0/12 group decreased from day3 as compared to untreated mice, and those of ZT0 group significantly decreased as compared to ZT12 group from day12. Pathological findings, immunohistochemistry of cytokines and Receptor activator of nuclear factor kappa-Β ligand (RANKL)/osteoprotegerin ratio in sera well reflected results of arthritis scores. Diurnal variation of STAT3 phosphorylation was suppressed in ZT0 group. At ZT2, expressions of IL-6/Interferon-γ/TNF/granulocyte-macrophage colony-stimulating factor in ZT0 group were significantly decreased as compared to untreated mice, though not in ZT12 group. In ZT0 group, IL-6 and TNF-α in sera were decreased for longer time than that in ZT12 group.

CONCLUSION

Chronotherapy using Baricitinib targeting cytokine secretions is effective in CIA mice. Clinical applications of chronotherapy can be expected to enhance the drug efficacy.

A Review on Chronic Pain in Rheumatoid Arthritis: A Focus on Activation of NR2B Subunit of N-Methyl-D-Aspartate Receptors

Chronic pain is a debilitating condition that occurs after tissue damage, which substantially affects the patient's emotional state and physical activity. The chronic pain in rheumatoid arthritis (RA) is the result of various autoimmune-induced inflammatory reactions in the joints. Both types of peripheral and central pain processing can lead to sensitisation. Non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs) can result in potent anti-inflammatory effect. However, these drugs are not able to suppress the pain from RA for a prolonged period. For years, researchers have examined the role of the N-methyl-D-aspartic acid receptor 2B (NR2B) subunit of N-methyl-D-aspartate receptors (NMDAR) in chronic and neuropathic pain models. This NMDAR subtype can be found in at the peripheral and central nervous system and it represents an effective therapy for RA pain management. This review focuses on the NR2B subunit of NMDAR and the different pathways leading to its activation. Furthermore, specific attention is given to the possible involvement of NR2B subunit in the peripheral and central pathogenesis of RA.