Peripheral and Central Sensitization of Pain in Individuals With Hand Osteoarthritis and Associations With Self-Reported Pain Severity

Hand osteoarthritis: A fresh look

Hand osteoarthritis (OA) has been the subject of numerous publications in recent years, particularly in the fields of imaging and therapeutics. The imaging studies revealed a good correlation between the presence of synovitis and/or subchondral edema and arthritic joint pain. Several randomized controlled trials (RCTs) have assessed the efficacy of biologics and conventional DMARDs in patients with symptomatic hand OA. No less than six RCTs have evaluated the symptomatic and, in some cases, structural efficacy of anti-IL-1, anti-TNF or anti-IL-6 drugs. Overall, the results of these trials were disappointing - none of them demonstrated superiority over placebo. There were also two negative trials with hydroxychloroquine. In the end, the only trial that was positive evaluated 10mg oral prednisone versus placebo for 6 weeks in patients with flares of hand OA and synovitis visible on ultrasound. While that trial confirms the role of inflammation in hand OA, it should obviously not encourage the long-term use of corticosteroids as a symptomatic treatment.

Hand osteoarthritis phenotypes based on a biopsychosocial approach, and their associations with cross-sectional and longitudinal pain

OBJECTIVE

Hand osteoarthritis (OA) pain is characterized as heterogeneous and multifactorial. Differences in pain may be explained by underlying phenotypes, which have not been previously explored DESIGN: Latent class analysis determined classes of participants with hand OA from the Nor-Hand study baseline examination (2016-17) based on a biopsychosocial framework. Outcomes were hand and overall bodily pain intensity (Numeric Rating Scale, 0-10) at baseline and follow-up (2019-21), The relations of the classes to pain outcomes at baseline, follow-up, and change over time were analysed in separate models by linear regression, using the overall healthiest class as reference.

RESULTS

Five classes differing in radiographic hand OA burden and OA burden in the lower extremities by ultrasound, demographic factors, psychosocial burden and pain sensitization was identified. Persons with the least severe OA but higher burden of biopsychosocial factors reported the most hand pain (beta 3.65, 95% CI 2.53, 4.75). Pain was less pronounced in persons with the most severe hand OA but low burden of biopsychosocial factors (beta 1.03, 95% CI 0.41, 1.65). Results were similar for overall bodily pain and at follow-up. Changes in pain were small, but the association between a separate class defined by higher levels of biopsychosocial burden and pain changes was significant.

CONCLUSION

The five hand OA phenotypes were associated with pain at baseline and 3.5 years later. The phenotype with the least OA severity, but higher burden of biopsychosocial factors reported more pain than the phenotype with the most severe OA, reflecting the symptom-structure discordance of the hand OA pain experience.

Myostatin and CXCL11 promote nervous tissue macrophages to maintain osteoarthritis pain

Pain is the most debilitating symptom of knee osteoarthritis (OA) that can even persist after total knee replacement. The severity and duration of pain do not correlate well with joint tissue alterations, suggesting other mechanisms may drive pain persistence in OA. Previous work identified that macrophages accumulate in the dorsal root ganglia (DRG) containing the somas of sensory neurons innervating the injured knee joint in a mouse OA model and acquire a M1-like phenotype to maintain pain. Here we aimed to unravel the mechanisms that govern DRG macrophage accumulation and programming. The accumulation of F4/80+iNOS+ (M1-like) DRG macrophages was detectable at day 3 after mono-iodoacetate (MIA)-induced OA in the mouse. Depletion of macrophages prior to induction of OA resolved pain-like behaviors by day 7 without affecting the initial development of pain-like behaviors. Analysis of DRG transcript identified CXCL11 and myostatin. CXCL11 and myostatin were increased at 3 weeks post OA induction, with CXCL11 expression partially localized in satellite glial cells and myostatin in sensory neurons. Blocking CXCL11 or myostatin prevented the persistence of OA pain, without affecting the initiation of pain. CXCL11 neutralization reduced the number of total and F4/80+iNOS+ DRG macrophages, whilst myostatin inhibition diminished the programming of F4/80+iNOS+ DRG macrophages. Intrathecal injection of recombinant CXCL11 did not induce pain-associated behaviors. In contrast, intrathecal myostatin increased the number of F4/80+iNOS+ DRG macrophages concurrent with the development of mechanical hypersensitivity that was prevented by macrophages depletion or CXCL11 blockade. Finally, myostatin inhibition during established OA, resolved pain and F4/80+iNOS+ macrophage accumulation in the DRG. In conclusion, DRG macrophages maintain OA pain, but are not required for the induction of OA pain. Myostatin is a key ligand in neuro-immune communication that drives the persistence of pain in OA through nervous tissue macrophages and represent a novel therapeutic target for the treatment of OA pain.

Quantitative sensory testing, psychological profiles and clinical pain in patients with psoriatic arthritis and hand osteoarthritis experiencing pain of at least moderate intensity

BACKGROUND

Chronic pain is the hallmark symptom of joint diseases. This study examined the differences in quantitative sensory testing between patients with psoriatic arthritis (PsA), hand osteoarthritis (hand-OA) and a pain-free control group and differences between patients with and without concomitant fibromyalgia (cFM).

METHODS

All patients and pain-free controls were assessed using pressure pain thresholds (PPT), temporal summation of pain (TSP), conditioned pain modulation (CPM) and clinical pain intensities. Psychological distress was assessed with the Hospital Anxiety and Depression Scale, Pain Catastrophizing Scale, and Pittsburgh Sleep Quality Index. Disability was assessed with the Health Assessment Questionnaire and pain quality with the painDETECT questionnaire. cFM was identified using the revised 2016 American College of Rheumatology diagnostic criteria.

RESULTS

Patients with hand-OA (n = 75) or PsA (n = 58) had statistically significant lower PPTs and CPM, greater TSP, and higher scores of psychological distress (p < 0.05) than controls (n = 20). Patients with cFM (58%) had higher scores of depression (p = 0.001), anxiety (p = 0.004), catastrophizing (p = 0.012), disability (p < 0.001), higher painDETECT score (p = 0.001), TSP (p = 0.027), and reduced sleep quality (p = 0.021) when compared to patients without cFM.

CONCLUSION

Patients with hand-OA and PsA exhibited signs of pain sensitization and a higher degree of psychological distress and disability than pain-free individuals. Patients with cFM had greater TSP, painDETECT score, disability, catastrophizing, and reduced sleep quality, than patients without, indicating greater degree of pain sensitization, psychological burden, and disability.

STATEMENT OF SIGNIFICANCE

This paper shows that a significant proportion of patients with hand osteoarthritis and psoriatic arthritis with moderate pain intensity have significantly increased signs of pain sensitization and markers of psychological distress. A large proportion of these patients fulfil the criteria for concomitant fibromyalgia and these patients show even greater propensity towards pain sensitization and psychological distress.

A Secondary Analysis: Comparison of Experimental Pain and Psychological Impact in Individuals with Carpometacarpal and Knee Osteoarthritis

Purpose

Evaluate sensory and psychological differences in individuals with thumb carpometacarpal (CMC) and/or knee osteoarthritis (OA) pain. This secondary analysis focuses on comparing the effects of OA at large and small joints in community-dwelling adults.

Patients and Methods

A total of 434 individuals were recruited from communities in Gainesville, FL and Birmingham, AL. Each participant completed health and clinical history questionnaires, quantitative sensory testing, and physical functional tests. Participants were divided into four groups based on their pain ("CMC pain" (n = 33), "knee pain" (n = 71), "CMC + knee pain" (n = 81), and "pain-free" controls (n = 60)). ANCOVAs were performed to identify significant differences in experimental pain and psychological variables across groups.

Results

The "CMC + knee pain" group had lower pressure pain thresholds (lateral knee site, p < 0.01) and higher temporal summation of mechanical pain (knee, p < 0.01) when compared to "CMC pain" and "pain-free" groups. The "knee pain" group had lower heat pain tolerance at the forearm site (p = 0.02) and higher mechanical pain (p < 0.01) at both tested sites in comparison to the "CMC pain" group. Lastly, the "CMC + knee pain" group had the highest self-reported pain (p < 0.01) and disability (p < 0.01) compared to all other groups.

Conclusion

Results suggest knee OA compounded with CMC OA increases disease impact and decreases emotional health compared to OA at either the CMC or knee joint alone. Results also support a relationship between the number of painful joints and enhanced widespread pain sensitivity. Measuring pain at sites other than the primary OA location is important and could contribute to more holistic treatment and prevention of OA progression.

Associations between pain sensitization and measures of physical function in people with hand osteoarthritis: Results from the Nor-Hand study

OBJECTIVE

To examine whether pain sensitization is associated with hand and lower extremity function in people with hand osteoarthritis (OA) in the Nor-Hand study.

DESIGN

Pain sensitization was assessed by pressure pain thresholds (PPTs) and temporal summation (TS). Hand function was assessed by Australian/Canadian Osteoarthritis Hand Index (AUSCAN) (range: 0-36), grip strength and Moberg pick-up test, and lower extremity function was assessed by Western Ontario and McMaster Universities Osteoarthritis Index (range: 0-68), 30-s chair stand test, and 40-m walk test. We examined whether sex-standardized PPT and TS values were cross-sectionally associated with measures of physical function using linear regression analyses. Beta coefficients were presented per sex-specific standard deviation of PPT and TS. The mediating effect of pain was examined by causal-inference based mediation analysis.

RESULTS

In 206 participants, higher PPTs at/near the hand, indicative of less peripheral and/or central pain sensitization, were associated with greater grip strength and better self-reported hand function (beta for PPT at finger joint on AUSCAN function: -1.41, 95% CI -2.40, -0.42). Higher PPTs at/near the hand, near the knee and at trapezius were associated with lower extremity function, although not statistically significant for all outcomes. Self-reported pain severity mediated the effect of PPT on self-reported function. TS was not associated with hand or lower extremity function.

CONCLUSION

Peripheral sensitization, and possibly central sensitization, was associated with impaired function. Effects of PPTs on self-reported function were mediated by self-reported pain, whereas there might be a direct effect of sensitization or effects through other mediators on performance-based function.

Determination and characterization of patient subgroups based on pain trajectories in hand osteoarthritis

OBJECTIVES

To investigate pain, pain trajectories and their determinants in hand osteoarthritis (OA).

METHODS

Data from the HOSTAS (Hand OSTeoArthritis in Secondary care) consisting of consecutive hand OA patients were used. Australian Canadian Osteoarthritis Hand Index (AUSCAN) pain was measured yearly for four years. Patients with complete AUSCAN at ≥2 time points were eligible for longitudinal analysis. Associations between variables of interest and baseline AUSCAN pain were investigated with linear regression. Development of pain over time was modelled using latent class growth analysis (LCGA). Associations of LCGA classes with variables of interest were analysed using multinomial logistic regression adjusted for baseline pain.

RESULTS

A total of 484/538 patients [mean (s.d.) age 60.8 (8.5) years, 86% women, mean (s.d.) AUSCAN pain 9.3 (4.3)] were eligible for longitudinal analysis. Sex, marital and working status, education, disease duration and severity, anxiety and depression scores, lower health-related quality of life (HR-QoL), specific illness perceptions and coping styles were associated with baseline pain. LCGA yielded three classes, characterized by average pain levels at baseline; average pain remained stable over time within classes. Classes with more pain were positively associated with BMI, tender joint count, symptom duration, hand function scores and depression scores, negatively with physical HR-QoL, and education level.

CONCLUSION

Baseline pain was associated with patient and disease characteristics, and psychosocial factors. LCGA showed three pain trajectories in hand OA patients, with different baseline pain levels and stable pain over time. Classes were distinguished by BMI, education level, disease severity, depression and HR-QoL.

Comorbidities in people with hand OA and their associations with pain severity and sensitization: Data from the longitudinal Nor-Hand study

Objective

To determine whether the comorbidity burden and co-existing comorbidities are cross-sectionally and/or longitudinally associated with pain and pain sensitization in a cohort study of people with hand OA.

Design

We examined whether comorbidity burden and individual comorbidities based on the self-administered Comorbidity Index (range: 0-42) at baseline were associated with pain outcomes at baseline and 3 years follow-up. Pain outcomes included hand and overall bodily pain (range: 0-10) as well as pressure pain thresholds at the tibialis anterior muscle (kg/cm²) and temporal summation (distal radioulnar joint) as measures of central pain sensitization. We performed linear regression analyses adjusted for age, sex, body mass index, physical exercise and education.

Results

We included 300 and 196 participants in cross-sectional and longitudinal analyses, respectively. Using baseline data, the burden of comorbidities was associated with greater pain in hands (beta ​= ​0.61, 95% CI 0.37, 0.85) and overall body (beta ​= ​0.60, 95% CI 0.37, 0.87). Similar strength of associations was found between comorbidity burden (baseline) and follow-up pain. Among the individual comorbidities, back pain and depression were associated with nearly one unit higher pain score in hands and overall body at both baseline and follow-up. Only back pain was related to lower pressure pain thresholds at follow up (beta ​= ​-0.24, 95% CI -0.50, -0.001).

Conclusion

People with hand OA and greater comorbidity burden, co-existing back pain or depression reported greater pain severity than their counterparts, also 3 years later. These results acknowledge the relevance of accounting for comorbidities in the pain experience in people with hand OA.

An update on the use of conventional and biological disease-modifying anti-rheumatic drugs in hand osteoarthritis

Osteoarthritis (OA) is a highly prevalent condition worldwide associated with pain, progressive disability, reduced participation in social activities, and impaired quality of life. Despite its growing burden, the therapeutic options are still limited and almost exclusively addressed to symptoms' management, while no disease-modifying OA drugs able to prevent or retard disease progression are actually available. For these reasons, in the last decades, relevant efforts to find new potential therapeutic targets in OA have been made and a number of existing conventional and biological disease-modifying anti-rheumatic drugs (DMARDs), including hydroxychloroquine (HCQ), methotrexate (MTX), tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 inhibitors, commonly used to treat inflammatory rheumatic diseases, have been repurposed for the treatment of OA and explored also in hand osteoarthritis (HOA). The current narrative review was aimed to provide a comprehensive and updated understanding of the possibilities and the criticisms related to the treatment of HOA with conventional and biological DMARDs. Unfortunately, therapy with conventional and biologic drugs in HOA has not achieved the expected success, despite a rationale for their use exists. Thus, our findings outline the urgent need to enhance the exploration of HOA basic molecular mechanisms to find new potential therapeutic targets, personalized for each patient, and appropriate for the different subsets of HOA and for the different phases of disease.

Neurotransmitter receptor densities are associated with changes in regional Cerebral blood flow during clinical ongoing pain

Arterial spin labelling (ASL) plays an increasingly important role in neuroimaging pain research but does not provide molecular insights regarding how regional cerebral blood flow (rCBF) relates to underlying neurotransmission. Here, we integrate ASL with positron emission tomography (PET) and brain transcriptome data to investigate the molecular substrates of rCBF underlying clinically relevant pain states. Two data sets, representing acute and chronic ongoing pain respectively, were utilised to quantify changes in rCBF; one examining pre-surgical versus post-surgical pain, and the second comparing patients with painful hand Osteoarthritis to a group of matched controls. We implemented a whole-brain spatial correlation analysis to explore associations between change in rCBF (ΔCBF) and neurotransmitter receptor distributions derived from normative PET templates. Additionally, we utilised transcriptomic data from the Allen Brain Atlas to inform distributions of receptor expression. Both datasets presented significant correlations of ΔCBF with the μ-opioid and dopamine-D2 receptor expressions, which play fundamental roles in brain activity associated with pain experiences. ΔCBF also correlated with the gene expression distributions of several receptors involved in pain processing. Overall, this is the first study illustrating the molecular basis of ongoing pain ASL indices and emphasises the potential of rCBF as a biomarker in pain research.

Neuropathic‐like pain symptoms in inflammatory hand osteoarthritis lower quality of life and may not decrease under prednisolone treatment

Background

Pain is common in hand osteoarthritis (OA) and multiple types may occur. We investigated the prevalence, associated patient characteristics, influence on health‐related quality of life (HR‐QoL) and response to anti‐inflammatory treatment of neuropathic‐like pain in inflammatory hand OA.

Methods

Data were analysed from a 6‐week, randomized, double‐blind, placebo‐controlled trial investigating prednisolone treatment in 92 patients with painful inflammatory hand OA. Neuropathic‐like pain was measured with the painDETECT questionnaire. Associations between baseline characteristics and baseline neuropathic‐like pain were analysed with ordinal logistic regression, association of baseline neuropathic‐like pain symptoms with baseline HR‐QoL with linear regression, painDETECT and visual analogue scale (VAS) change from baseline to week 6 and interaction of painDETECT with prednisolone efficacy on VAS pain change from baseline to week 6 with generalized estimating equations (GEE).

Results

Of 91 patients (79% female, mean age 64) with complete painDETECT data at baseline, 53% were unlikely to have neuropathic‐like pain, 31% were indeterminate and 16% were likely to have neuropathic‐like pain. Neuropathic‐like pain was associated with female sex, less radiographic damage and more comorbidities. Patients with neuropathic‐like pain had lower HR‐QoL (PCS‐6.5 [95% CI −10.4 to −2.6]) than those without. Neuropathic‐like pain symptoms remained under prednisolone treatment and no interaction was seen between painDETECT and prednisolone efficacy on VAS pain.

Conclusions

In this study, 16% of inflammatory hand OA patients had neuropathic‐like pain. They were more often female, had more comorbidities and had lower QoL than those without. Neuropathic‐like pain symptoms remained despite prednisolone treatment and did not seem to affect the outcome of prednisolone treatment.

Significance

Pain is the dominant symptom in hand OA, with an unclear aetiology. In this study, we found that neuropathic‐like pain may play a role in hand OA, that it showed associations with female sex, younger age and more comorbidities and that it lowered health‐related quality of life in hand OA. Neuropathic‐like pain in hand OA seems resistant to prednisolone therapy but did not seem to interfere with the treatment of inflammatory pain with prednisolone.

Associations between joint pathologies and central sensitization in persons with hand osteoarthritis: results from the Nor-Hand study

OBJECTIVE

Pain sensitization is associated with pain severity in persons with hand OA. What contributes to pain sensitization is unclear. This study explores whether hand OA pathologies and symptom duration are related to central sensitization.

METHOD

Participants with hand OA in the Nor-Hand study underwent bilateral hand radiography and US examination. Central sensitization was assessed with pressure pain thresholds (PPT) at remote sites (wrist, trapezius and tibialis anterior muscles) and temporal summation. We examined whether hand OA pathologies, independent of each other, including structural severity (Kellgren-Lawrence sum score, presence of erosive hand OA), inflammatory severity (greyscale synovitis and power Doppler activity sum scores) and symptom duration, were related to central sensitization, adjusting for age, sex, BMI, comorbidities and OA-severity of knee/hip.

RESULTS

In 291 participants (88% women, median age 61 years, interquartile range 57-66 years) Kellgren-Lawrence, greyscale synovitis and power Doppler activity sum scores were not associated with lower PPTs at remote sites. Persons with erosive hand OA had lower PPTs at the wrist (adjusted beta -0.75, 95% CI -1.32, -0.19) and tibialis anterior (adjusted beta -0.82, 95% CI -1.54, -0.09) and had greater temporal summation (adjusted beta 0.56, 95% CI 0.12, 1.01) compared with persons with non-erosive disease. No associations were found for symptom duration.

CONCLUSIONS

A person's overall amount of structural or inflammatory hand OA pathologies was not associated with central sensitization. Although persons with erosive hand OA showed greater signs of central sensitization, the small differences suggest that central sensitization is mainly explained by factors other than joint pathologies.

Associations of pain sensitisation with tender and painful joint counts in people with hand osteoarthritis: results from the Nor-Hand study

Objective

To examine associations of pain sensitisation with tender and painful joint counts and presence of widespread pain in people with hand osteoarthritis (OA).

Methods

Pressure pain thresholds (PPT) at a painful finger joint and the tibialis anterior muscle, and temporal summation (TS) were measured in 291 persons with hand OA. We examined whether sex-standardised PPT and TS values were associated with assessor-reported tender hand joint count, self-reported painful hand and total body joint counts and presence of widespread pain using linear and logistic regression analyses adjusted for age, sex, body mass index, education and OA severity.

Results

People with lower PPTs at the painful finger joint (measure of peripheral and/or central sensitisation) had more tender and painful hand joints than people with higher PPTs. PPT at tibialis anterior (measure of central sensitisation) was associated with painful total body joint count (beta=−0.82, 95% CI −1.28 to –0.35) and presence of widespread pain (OR=0.57, 95% CI 0.43 to 0.77). The associations between TS (measure of central sensitisation) and joint counts in the hands and the total body were statistically non-significant.

Conclusion

This cross-sectional study suggested that pain sensitisation (ie, lower PPTs) was associated with joint counts and widespread pain in hand OA. This knowledge may be used for improved pain phenotyping of people with hand OA, which may contribute to better pain management through more personalised medicine. Further studies are needed to assess whether a reduction of pain sensitisation leads to a decrease in tender and painful joint counts.

Quantitative sensory testing: identifying pain characteristics in patients with osteoarthritis

OBJECTIVE

This review outlines the most commonly used quantitative sensory tests to identify pain sensitization. We examine cross-sectional associations between quantitative sensory testing (QST) measures and OA symptoms and severity, along with longitudinal associations between QST findings and response to surgical and non-surgical treatments for OA.

DESIGN

We conducted a search in PubMed for English language papers including 'osteoarthritis' and 'quantitative sensory testing' as search terms. Papers that did not pertain specifically to OA or QST were excluded.

RESULTS

Pressure Pain Threshold (PPT), Conditioned Pain Modulation (CPM), and Temporal Summation (TS) are the QST measures used most frequently to identify pain sensitization. Findings indicate that persons with knee OA often exhibit lower PPT thresholds, inefficient CPM, and facilitated TS as compared with controls who do not have OA, supporting the discriminant validity of QST. Pre-treatment QST has shown some success in identifying persons who experience less pain relief from surgical and non-surgical treatments for knee OA. Post-treatment QST has shown that sometimes PPT and CPM can normalize (PPT thresholds increase, and CPM becomes efficient) in patients for whom joint replacement is successful. Recent studies indicate that QST measures are more closely associated with pain severity than OA radiographic severity, suggesting that sensitization may be a trait rather than a state.

CONCLUSIONS

QST may have a role in identifying persons who are susceptible to chronic pain and may offer an opportunity for personalized, more effective treatment of OA.

Sensory characteristics according to chronic diseases and chronic pain in adults: cross-sectional study

Aim: To investigate somatosensory, gustative and olfactory characteristics of subjects according to their chronic diseases and the presence of chronic pain complaints. Materials & methods: A total of 254 chronic pain patients and 52 healthy subjects were evaluated with a clinical and sensory systematized evaluation. Statistical analysis consisted of Fisher's exact, Student's t-tests, Pearson's co-efficient and multivariate nonlinear/logistic regressions. Results: Patients had more chronic diseases (p < 0.001) than healthy subjects. Chronic pain was associated with vibratory hypoesthesia (p = 0.047) and sour hypergeusia (p = 0.001) and several chronic diseases correlated with sensory features. Hyposmia was strongly associated with chronic pain symptoms, chronic diseases and cardiovascular disease. Conclusion: The sensory findings observed suggest the need for further investigation about the overlap between the olfactory function, pain chronification, chronic diseases and cognitive impairment in these patients.

Febuxostat mitigates IL-18-induced inflammatory response and reduction of extracellular matrix gene

BACKGROUND

Osteoarthritis (OA) is a disease commonly diagnosed in the elderly population. It is reported that the reduction of extracellular matrix and infiltrated inflammation are two main factors responsible for the pathogenesis of OA. This investigation aims to explore the potential protective effects of Febuxostat against IL-18-induced insults in chondrocytes, as well as the possible mechanism.

MATERIALS AND METHODS

The viability of chondrocytes was evaluated using the MTT assay. QRT-PCR and ELISA were used to measure the expressions and concentrations of IL-6, TNF-α, and CCL5, respectively. The accumulation of glycosaminoglycans (GAGs) was measured using Alcian blue assay. The chondrocytes were transfected with siRNA against Sox-9 in order to establish the Sox-9 knock-down chondrocytes. The expressions of iNOS, Col2a1, Acan, and Sox-9 were measured using qRT-PCR. The production of NO was measured using Diaminofluorescein-FM diacetate (DAF-FM DA) staining.

RESULTS

The up-regulated expressions of IL-6, TNF-α, CCL5, iNOS, and NO stimulated by IL-18 were down-regulated by the introduction of Febuxostat. The expressions of Col2a1, Acan, and Sox-9 were significantly reduced by IL-18 but greatly promoted by Febuxostat. The increased gene expressions of Col2a1 and Acan induced by Febuxostat were abolished by knocking down Sox-9 in the chondrocytes.

CONCLUSION

Febuxostat might mitigate IL-18-induced inflammatory response and reduction of the extracellular matrix gene mediated by Sox-9.

β-ecdysterone alleviates osteoarthritis by activating autophagy in chondrocytes through regulating PI3K/AKT/mTOR signal pathway

PURPOSE

To investigate the therapeutic effects of β-ecdysterone on osteoarthritis (OA) and the underlying mechanism.

METHODS

OA model was established on rats by injecting MIA. ELSA was used to determine the concentration of IL-1β, IL-6, NO and TNF-α in the chondrocytes and cartilage tissues. Immunofluorescence assay was used to determine the expression of collagen II in the chondrocytes. The survival rate of chondrocytes was evaluated by MTT assay. The apoptosis of chondrocytes was checked by AO/PI staining and flow cytometry assay. The expression level of Atg7, PI3K and caspase-3 was evaluated by qRT-PCR. Western Blot was used determine the expression of PI3K, p-AKT1, AKT1, p-mTOR, mTOR, p70S6K, p-p70S6K, LC3I, LC3II and caspase-3. HE staining was used to check the pathological state of cartilage tissues.

RESULTS

Chondrocytes were tolerable to rapamycin, 3-methyladenine and β-ecdysterone at the concentration of 10 mM, 100 nM and 40 μM, respectively. The apoptosis of chondrocytes was inhibited by rapamycin and β-ecdysterone, and induced by 3-methyladenine. PI3K, p-AKT1, p-mTOR, p-p70S6K and caspase-3 were down-regulated by rapamycin and β-ecdysterone, and up-regulated by 3-methyladenine in both the chondrocytes and the cartilage tissues. The expression of Atg7 and LC3II/LC3I were regulated in a opposite way. The inflammation state was improved by rapamycin and β-ecdysterone both the chondrocytes and the cartilage tissues. HE staining results showed that the pathological state of cartilage tissues was alleviated by β-ecdysterone.

CONCLUSION

β-ecdysterone might alleviate osteoarthritis by activating autophagy in chondrocytes through regulating PI3K/AKT/mTOR signal pathway.

Emerging pharmaceutical therapies for osteoarthritis

The prevalence of osteoarthritis (OA) and the burden associated with the disease are steadily increasing worldwide, representing a major public health challenge for the coming decades. The lack of specific treatments for OA has led to it being recognized as a serious disease that has an unmet medical need. Advances in the understanding of OA pathophysiology have enabled the identification of a variety of potential therapeutic targets involved in the structural progression of OA, some of which are promising and under clinical investigation in randomized controlled trials. Emerging therapies include those targeting matrix-degrading proteases or senescent chondrocytes, promoting cartilage repair or limiting bone remodelling, local low-grade inflammation or Wnt signalling. In addition to these potentially disease-modifying OA drugs (DMOADs), several targets are being explored for the treatment of OA-related pain, such as nerve growth factor inhibitors. The results of these studies are expected to considerably reshape the landscape of OA management over the next few years. This Review describes the pathophysiological processes targeted by emerging therapies for OA, along with relevant clinical data and discussion of the main challenges for the further development of these therapies, to provide context for the latest advances in the field of pharmaceutical therapies for OA.

Efficacy of tocilizumab in patients with hand osteoarthritis: double blind, randomised, placebo-controlled, multicentre trial

OBJECTIVE

To evaluate the efficacy of tocilizumab, an antibody against IL-6 receptor, in patients with hand osteoarthritis.

METHODS

This was a multicentre, 12-week, randomised, double-blind, placebo-controlled study from November 2015 to October 2018. Patients with symptomatic hand osteoarthritis (pain ≥40 on a 0-100 mm visual analogue scale (VAS) despite analgesics and non-steroidal anti-inflammatory drugs; at least three painful joints, Kellgren-Lawrence grade ≥2) were randomised to receive two infusions 4 weeks apart (weeks 0 and 4) of tocilizumab (8 mg/kg intravenous) or placebo. The primary endpoint was changed in VAS pain at week 6. Secondary outcomes included the number of painful and swollen joints, duration of morning stiffness, patients' and physicians' global assessment and function scores.

RESULTS

Of 104 patients screened, 91 (45 to tocilizumab and 46 to placebo; 82% women; mean age 64.4 (SD 8.7) years) were randomly assigned and 79 completed the 12-week study visit. The mean change between baseline and week 6 on the VAS for pain (primary outcome) was -7.9 (SD 19.4) and -9.9 (SD 20.1) in the tocilizumab and placebo groups (p=0.7). The groups did not differ for any secondary outcomes at weeks 4, 6, 8 or 12. Overall, adverse events were slightly more frequent in the tocilizumab than placebo group.

CONCLUSION

Tocilizumab was no more effective than placebo for pain relief in patients with hand osteoarthritis.

Roflumilast prevents lymphotoxin α (TNF-β)-induced inflammation activation and degradation of type 2 collagen in chondrocytes

BACKGROUND AND PURPOSE

Osteoarthritis (OA) is a chronic disease accompanied by severe inflammation. The inflammation activation in the chondrocytes and the degradation of the extracellular matrix were reported to be involved in the progress of OA. Roflumilast is a selective PDE4 inhibitor used for treating chronic obstructive pulmonary disease (COPD) and exerts significant anti-inflammation effects. The present study aims to investigate the effects of Roflumilast on tumor necrosis factor-β (TNF-β)-induced inflammation activation and degradation of type 2 collagen in chondrocytes.

METHODS

TNF-β was used to establish the in-vitro inflammation model on ATDC5 chondrocytes. Quantitative real-time polymerase chain reaction (QRT-PCR) and western blot were used to determine the expression level of tumor necrosis factor receptor 2 (TNFR2), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), matrix metalloproteinase 3 (MMP-3), matrix metalloproteinase 13 (MMP-13), type 2 collagen and nuclear factor kappa B (NF-κB) p65. The release of prostaglandin E2 (PGE₂), MMP-3, and MMP-13 were evaluated by ELISA. The production of NO was determined by DAF-FM DA staining and the function of the NF-κB promoter was evaluated by Luciferase activity assay.

RESULTS

TNFR2 and COX-2 were upregulated and the release of PGE₂ was promoted by TNF-β stimulation, which were all inhibited by Roflumilast. Roflumilast suppressed the promoted iNOS expression and NO production induced by TNF-β. MMP-3 and MMP-13 were up-regulated, and type 2 collagen was down-regulated by TNF-β stimulation, which were all reversed by Roflumilast. Roflumilast inhibited the promoted releasing of Interleukin-8 (IL-8) and Interleukin-12 (IL-12), expression of up-regulated NF-κB, and activation of NF-κB transcriptional activity induced by TNF-β.

CONCLUSION

Roflumilast may prevent TNF-β-induced inflammation activation and degradation of type 2 collagen in chondrocytes.

The Valued Life Activities Scale (VLAs): linguistic validation, cultural adaptation and psychometric testing in people with rheumatic and musculoskeletal diseases in the UK

Background

The Valued Life Activities Scale (VLAs) measures difficulty in daily activities and social participation. With various versions involving a different number of items, we have linguistically and culturally adopted the full VLAs (33-items) and psychometrically tested it in adults with rheumatic and musculoskeletal diseases in the United Kingdom.

Methods

Participants with Rheumatoid Arthritis, Ankylosing Spondylitis, Chronic Pain/ Fibromyalgia, Chronic Hand/ Upper Limb Conditions, Osteoarthritis, Systemic Lupus, Systemic Sclerosis and Primary Sjogren’s Syndrome were recruited from out-patient clinics in National Health Service Hospitals, General Practice and patient organisations in the UK. Phase1 involved linguistic and cultural adaptation: forward translation to British English; synthesis; expert panel review and cognitive debriefing interviews. In Phase2 participants completed postal questionnaires to assess internal construct validity using (i) Confirmatory Factor Analysis (CFA) (ii) Mokken scaling and (iii) Rasch model.

Results

Responders (n = 1544) had mean age of 59 years (SD13.3) and 77.2% women. A CFA failed to support a total score from the 33-items (Chi Square 3552:df 464: p < 0.0001). Mokken scaling indicated a strong non-parametric association between items. Fit to the Rasch model indicated that the VLAs was characterised by multidimensionality and item misfit, which may have been influenced by clusters of residual item correlations. An item banking approach resolved a 25-item calibrated set whose application could accommodate the ‘does not apply to me’ response option.

Conclusions

The UK version of the VLAs failed to satisfy classical and modern psychometric standards for complete item sets. However, as the scale is not usually applied in complete format, an item bank approach calibrated 25 items with fit to the Rasch model. Suitable Computer Adaptive Testing (CAT) software could implement the item set, giving patients the choice of whether an item applies to them, or not.

Associations Between Radiographic and Ultrasound-Detected Features in Hand Osteoarthritis and Local Pressure Pain Thresholds

OBJECTIVE

Pain sensitization contributes to the complex osteoarthritis (OA) pain experience. The relationship between imaging features of hand OA and clinically assessed pain sensitization is largely unexplored. This study was undertaken to examine the association of structural and inflammatory features of hand OA with local pressure pain thresholds (PPTs) in the Nor-Hand study.

METHODS

The cross-sectional relationship of severity of structural radiographic features of hand OA (measured according to the Kellgren/Lawrence scale [grade 0-4] and the absence or presence of erosive joint disease) as well as ultrasound-detected hand joint inflammation (assessed by gray-scale synovitis [grade 0-3] and the absence or presence of power Doppler activity) to the PPTs of 2 finger joints was examined by multilevel regression analyses adjusted for age, sex, and body mass index, using beta values with 95% confidence intervals (95% CIs).

RESULTS

A total of 570 joints in 285 participants included in the Nor-Hand study were assessed. Greater structural and inflammatory severity was associated with lower PPTs, with adjusted beta values of -0.5 (95% CI -0.6, -0.4) per Kellgren/Lawrence grade increase, -1.4 (95% CI -1.8, -0.9) for erosive versus non-erosive joints, -0.7 (95% CI -0.9, -0.6) per gray-scale synovitis grade increase, and -1.5 (95% CI -1.8, -1.1) for joints with power Doppler activity on ultrasound versus those without.

CONCLUSION

Greater severity of structural pathologic features and hand joint inflammation was associated with lower PPTs in the finger joints of patients with hand OA, indicating pain sensitization. Our results indicate that pain sensitization might be driven by structural and inflammatory pathology in hand OA.

Modulation of sensitization processes in the management of pain and the importance of descending pathways: a role for tapentadol?

Objective: This paper presents and discusses recent evidence on the pathophysiological mechanisms of pain. The role of tapentadol - an opioid characterized by an innovative mechanism of action (i.e. µ-opioid receptor [MOR] agonism and inhibition of noradrenaline [NA] reuptake [NRI]) - in the modulation of pain, and the most recent pharmacological evidence on this molecule (e.g. the µ-load concept) are also presented and commented upon.Methods: Narrative review.Results: Solid evidence has highlighted the importance of central sensitization in the transition from acute to chronic pain. In particular, the noradrenergic system holds a major role in limiting central sensitization and the progression to chronic pain. Therefore, pharmacological modulation of the noradrenergic system appears to be a well-grounded strategy for the control of chronic pain. Tapentadol is characterized by a to-date-unique mechanism of action, since it acts both as a MOR agonist and as an inhibitor of NA reuptake. The synergistic interaction of these two mechanisms allows a strong analgesic effect by acting on both ascending and descending pathways. Of note, the reduced µ-load of tapentadol limits the risk of opioid-related adverse events, such as gastrointestinal disturbances. Moreover, the NA component becomes predominant, at least, in some types of pain, with consequent specific clinical efficacy in the treatment of neuropathic and chronic pain.Conclusions: According to these characteristics, tapentadol appears suitable in the treatment of severe uncontrolled chronic pain characterized by both a nociceptive and a neuropathic component, such as osteoarthritis or back pain.

Modulation of sensitization processes in the management of pain and the importance of descending pathways: a role for tapentadol?

Objective: This paper presents and discusses recent evidence on the pathophysiological mechanisms of pain. The role of tapentadol - an analgesic molecule characterized by an innovative mechanism of action (i.e. µ-opioid receptor [MOR] agonism and inhibition of noradrenaline [NA] reuptake [NRI]) - in the modulation of pain, and the most recent pharmacological evidence on this molecule (e.g. the µ-load concept) are also presented and commented upon.Methods: Narrative review.Results: Solid evidence has highlighted the importance of central sensitization in the transition from acute to chronic pain. In particular, the noradrenergic system holds a major role in limiting central sensitization and the progression to chronic pain. Therefore, pharmacological modulation of the noradrenergic system appears to be a well-grounded strategy for the control of chronic pain. Tapentadol is characterized by a to-date-unique mechanism of action since it acts both as a MOR agonist and as an inhibitor of NA reuptake. The synergistic interaction of these two mechanisms allows a strong analgesic effect by acting on both ascending and descending pathways. Of note, the reduced µ-load of tapentadol has two important consequences: first, it limits the risk of opioid-related adverse events, as well as the risk of dependence; second, the NA component becomes predominant at least in some types of pain with consequent specific clinical efficacy in the treatment of neuropathic and chronic pain.Conclusions: According to these characteristics, tapentadol appears suitable in the treatment of chronic pain conditions characterized by both a nociceptive and a neuropathic component, such as osteoarthritis or back pain.

Understanding the Molecular Mechanisms Underlying the Pathogenesis of Arthritis Pain Using Animal Models

Arthritis, including osteoarthritis (OA) and rheumatoid arthritis (RA), is the leading cause of years lived with disability (YLD) worldwide. Although pain is the cardinal symptom of arthritis, which is directly related to function and quality of life, the elucidation of the mechanism underlying the pathogenesis of pain in arthritis has lagged behind other areas, such as inflammation control and regulation of autoimmunity. The lack of therapeutics for optimal pain management is partially responsible for the current epidemic of opioid and narcotic abuse. Recent advances in animal experimentation and molecular biology have led to significant progress in our understanding of arthritis pain. Despite the inherent problems in the extrapolation of data gained from animal pain studies to arthritis in human patients, the critical assessment of molecular mediators and translational studies would help to define the relevance of novel therapeutic targets for the treatment of arthritis pain. This review discusses biological and molecular mechanisms underlying the pathogenesis of arthritis pain determined in animal models of OA and RA, along with the methodologies used.

Splinting for the carpometacarpal joint relieves experimental basal thumb pain and loss of pinch strength

BACKGROUND

Splinting is a quite common intervention for the first carpometacarpal (CMC) osteoarthritis, however, underlying mechanisms of biomechanical and analgesic effects has not been fully investigated. The aim of this study was to develop an experimental basal thumb pain model and to elucidate the effects of CMC splinting on the pain profile and motor function.

METHODS

In 14 healthy subjects, experimental basal thumb pain was induced by hypertonic saline injection into the dorsal radial ligament located on base of the first metacarpal bone. Isotonic saline was injected contralaterally as a control. Two experimental sessions with or without CMC splinting were conducted. Before, during and after injections, tip pinch strength was measured and surface electromyography of the abductor pollicis brevis (APB), first dorsal interosseous (FDI) and extensor pollicis longus (EPL) during tip pinch were evaluated in each session.

RESULTS

Hypertonic saline induced significantly greater pain compared with baseline and isotonic saline (p < 0.01). Following hypertonic saline injection, the tip pinch strength decreased compared with baseline, concomitant with reduction of electromyographical activity of APB and FDI, but not of EPL (p < 0.05). The CMC splinting significantly improved the experimental pain, loss of pinch strength and inhibited intrinsic muscle activity compared with bare hand (p < 0.05).

CONCLUSIONS

A novel experimental model mimicking the first CMC joint pain was developed. The CMC splinting relieved the basal thumb pain and augmented pinch strength as well as intrinsic muscle activity. This study provides new insights into the pain relief and pinch strength improvement by splinting for painful CMC joint disorders.

SIGNIFICANCE

Newly developed experimental basal thumb pain model decreased tip pinch strength approximately 50%, concomitant with the reduction of intrinsic muscle activities. Splinting for the first carpometacarpal joint significantly improved experimental pain, loss of pinch strength and inhibited intrinsic muscle activity compared with bare hand.