• Angiogenesis and nerve growth factor at the osteochondral junction in rheumatoid arthritis and osteoarthritis

      Walsh, David A (Rheumatology (Oxford), 2010-10)
      Objectives. The osteochondral junction can be a source of pain in both RA and OA. Growth of blood vessels and nerves from the subchondral bone into articular cartilage may mediate the association between joint pathology and symptoms. We have investigated associations between angiogenesis, inflammation and neurovascular growth factor expression at the osteochondral junction in human arthritis. Methods. Osteochondral junctions from medial tibial plateaux of patients undergoing arthroplasty for RA (n = 10) or OA (n = 11), or from non-arthritic post-mortem controls (n = 11) were characterized by immunohistochemistry for CD34 and smooth muscle α-actin (blood vessels), CD68 (macrophages), CD3 (lymphocytes), proliferating cell nuclear antigen, vascular endothelial, platelet-derived and nerve growth factor (NGF). Results. Osteochondral angiogenesis was demonstrated as increased endothelial cell proliferation and vascular density in non-calcified articular cartilage, both in RA and OA. Osteochondral angiogenesis was associated with subchondral bone marrow replacement by fibrovascular tissue expressing VEGF, and with increased NGF expression within vascular channels. RA was characterized by greater lymphocyte infiltration and PDGF expression than OA, whereas chondrocyte expression of VEGF was a particular feature of OA. NGF was observed in vascular channels that contained calcitonin gene-related peptide-immunoreactive sensory nerve fibres. Conclusions. Osteochondral angiogenesis in RA and OA is associated with growth factor expression by cells within subchondral spaces, vascular channels and by chondrocytes. NGF expression and sensory nerve growth may link osteochondral angiogenesis to pain in arthritis.
    • Angiogenesis and the persistence of inflammation in a rat model of proliferative synovitis

      Walsh, David A (Arthritis and Rheumatism, 2010-07)
      Objective: To determine whether blood vessel growth at the onset of resolving synovitis leads to its subsequent persistence and whether inhibiting this angiogenesis at the onset of persistent inflammation leads to its subsequent resolution. Methods: Inflammation and angiogenesis were induced by injection of 0.03% carrageenan and/or 6 pmoles of fibroblast growth factor 2 (FGF-2) into rat knees. A brief treatment with the angiogenesis inhibitor PPI-2458 (5 mg/kg orally on alternate days) was administered 1 day before and up to 3 days after synovitis induction. Controls comprised naive and vehicle-treated rats. Synovial angiogenesis was measured using the endothelial cell proliferation index, and inflammation was determined by measuring joint swelling and macrophage percentage area. Data are presented as the geometric mean (95% confidence interval). Results: Intraarticular injection of 0.03% carrageenan into rat knees produced acute synovitis, which was not associated with synovial angiogenesis and which resolved within 29 days. Injection of FGF-2 (6 pmoles) induced synovial angiogenesis without significant synovitis. Stimulation of angiogenesis with FGF-2 at the time of carrageenan injection was followed by synovitis that persisted for 29 days. Persistence of carrageenan/FGF-2-induced synovitis was prevented by systemic administration of 3 doses of the angiogenesis inhibitor PPI-2458 during the acute phase. Conclusion: Our findings indicate that conversion of acute inflammation to chronic inflammation may be due to the stimulation of angiogenesis, and brief antiangiogenic treatment during the acute phase of synovitis may prevent its subsequent progression. Clinical studies will be needed to determine whether brief antiangiogenic treatment may reduce the burden of inflammatory joint diseases such as rheumatoid arthritis by facilitating the resolution of early synovitis.
    • Angiogenesis in the synovium and at the osteochondral junction in osteoarthritis

      Walsh, David A (Osteoarthritis and Cartilage, 2007-07)
      Objectives: We hypothesised that osteochondral and synovial angiogenesis in osteoarthritis (OA) are independent processes. We investigated whether indices of osteochondral and synovial angiogenesis display different relationships with synovitis, disease severity and chondrocalcinosis in patients with OA. Design: Synovium and medial tibial plateaux were obtained from 62 patients undergoing total knee joint replacement for OA (18 [29%] had chondrocalcinosis) and from 31 recently deceased people with no evidence of joint pathology post-mortem (PM). Vascular endothelium, proliferating endothelial cells (ECs) and macrophages were quantified by immunohistochemistry for CD34, CD31/Ki67 and CD14, respectively. Grades were assigned for radiographic and histological OA disease severity, clinical disease activity and histological synovitis (based on cellular content of the synovium). Results: Blood vessels breached the tidemark in 60% of patients with OA and 20% of PM controls. Osteochondral vascular density increased with increasing cartilage severity and clinical disease activity scores, but not with synovitis. Synovial EC proliferation, inflammation and macrophage infiltration were higher in OA than in PM controls. Synovial angiogenesis indices increased with increasing histological synovitis, but were not related to osteochondral vascular density or other indices of OA disease severity. OA changes were more severe in patients with concurrent chondrocalcinosis. Chondrocalcinosis was not associated with increased angiogenesis or histological synovitis beyond that seen in OA alone. Conclusion: Osteochondral and synovial angiogenesis appear to be independent processes. Osteochondral vascularity is associated with the severity of OA cartilage changes and clinical disease activity, whereas synovial angiogenesis is associated with histological synovitis. Modulation of osteochondral and synovial angiogenesis may differentially affect OA disease.
    • Angiogenesis in two animal models of osteoarthritis

      Walsh, David A (Osteoarthritis and Cartilage, 2008-01)
      Objective: We have previously described angiogenesis at the osteochondral junction and in synovium of knees from patients with osteoarthritis (OA), but little is known about how closely animal models of OA resemble human disease with respect to vascular growth. This study aimed to characterise two animal models of knee OA with particular respect to osteochondral and synovial angiogenesis. Method: We examined the spontaneous Dunkin-Hartley (DH) guinea pig and medial meniscal transection (MNX) rat models of OA. Vessels at the osteochondral junction and in the synovium were identified by lectin immunohistochemistry and quantified by computer-assisted image analysis. Disease severity was assessed using a scoring system. Results: Blood vessels crossed the osteochondral junction in juvenile rats and guinea pigs, with higher densities in the lateral than medial tibial plateau, the number decreasing with maturation in the absence of other OA changes. In the rat model, increased vascular density was observed both at the osteochondral junction and in the synovium, whilst osteochondral vascularity in control rats decreased with maturation, OA rats showed a persistence of blood vessels at the osteochondral junction. In rat synovium, blood vessel fractional area was increased in the hypertrophied synovium 14 days after surgery, then decreased to control levels by day 28. Significant differences in vascularity were not observed between affected (medial) and spared (lateral) compartments of guinea pig knees. Conclusion: The rat meniscal transection model of OA reproducibly displays both osteochondral and synovial angiogenesis comparable to our previous observations in human knee OA. DH guinea pigs, by contrast, display low vascularity throughout their protracted course of OA development. Changes in vascularisation occur early during the development of OA in the rat, and may contribute to the pathogenesis of OA.
    • The anti-NGF antibody muMab 911 both prevents and reverses pain behaviour and subchondral osteoclast numbers in a rat model of osteoarthritis pain

      Walsh, David A (Osteoarthritis and Cartilage, 2016-09)
      Objective: Nerve growth factor (NGF) has a pivotal role in peripheral hyperalgesia and inflammation; anti-NGF antibodies attenuate pain responses in inflammatory pain models, and in people with osteoarthritis (OA) or low back pain. The aim of this study was to characterise the peripheral mechanisms contributing to the analgesic effects of anti-NGF antibody treatment in an established model of joint pain, which mimics key clinical features of OA. Design: Effects of preventative vs therapeutic treatment with an anti-NGF antibody (monoclonal antibody 911: muMab 911 (10 mg/kg, s.c.)) on pain behaviour (weight bearing asymmetry and hindpaw withdrawal thresholds (PWT)), cartilage damage, synovitis and numbers of subchondral osteoclasts were investigated in the monosodium iodoacetate (MIA) model. Potential direct effects of NGF on receptor activator of nuclear factor kappa-B ligand (RANKL) mediated osteoclastogenesis were investigated in cultured human osteoclasts. Results: Intra-articular MIA injection resulted in significant pain behaviour, cartilage damage, synovitis and increased numbers of subchondral osteoclasts. Both preventative and therapeutic treatment with muMab 911 significantly prevented, or reversed, MIA-induced pain behaviour, but did not alter cartilage or synovial pathology quantified at the end of the treatment period. NGF did not facilitate RANKL driven osteoclast differentiation in vitro, but preventative or therapeutic muMab 911 reduced numbers of TRAP positive osteoclasts in the subchondral bone. Conclusions: We demonstrate that anti-NGF antibody treatment attenuates OA pain behaviour despite permitting cartilage damage and synovitis. Indirect effects on subchondral bone remodelling may contribute to the analgesic effects of NGF blockade.
    • Association between rheumatoid arthritis disease activity, progression of functional limitation and long-term risk of orthopaedic surgery: Combined analysis of two prospective cohorts supports EULAR treat to target DAS thresholds.

      Walsh, David A (2016-12)
      bjectives: To examine the association between disease activity in early rheumatoid arthritis (RA), functional limitation and long-term orthopaedic episodes. Methods: Health Assessment Questionnaire (HAQ) disability scores were collected from two longitudinal early RA inception cohorts in routine care; Early Rheumatoid Arthritis Study and Early Rheumatoid Arthritis Network from 1986 to 2012. The incidence of major and intermediate orthopaedic surgical episodes over 25 years was collected from national data sets. Disease activity was categorised by mean disease activity score (DAS28) annually between years 1 and 5; remission (RDAS<2.6), low (LDAS>2.6-3.2), low-moderate (LMDAS>3.2-4.19), high-moderate (HMDAS 4.2-5.1) and high (HDAS>5.1). Results: Data from 2045 patients were analysed. Patients in RDAS showed no HAQ progression over 5 years, whereas there was a significant relationship between rising DAS28 category and HAQ at 1 year, and the rate of HAQ progression between years 1 and 5. During 27 986 person-years follow-up, 392 intermediate and 591 major surgeries were observed. Compared with the RDAS category, there was a significantly increased cumulative incidence of intermediate surgery in HDAS (OR 2.59 CI 1.49 to 4.52) and HMDAS (OR 1.8 CI 1.05 to 3.11) categories, and for major surgery in HDAS (OR 2.48 CI 1.5 to 4.11), HMDAS (OR 2.16 CI 1.32 to 3.52) and LMDAS (OR 2.07 CI 1.28 to 3.33) categories. There was no significant difference in HAQ progression or orthopaedic episodes between RDAS and LDAS categories. Conclusions: There is an association between disease activity and both poor function and long-term orthopaedic episodes. This illustrates the far from benign consequences of persistent moderate disease activity, and supports European League Against Rheumatism treat to target recommendations to secure low disease activity or remission in all patients.
    • Association between ultrasound-detected synovitis and knee pain: a population-based case-control study with both cross-sectional and follow-up data.

      Walsh, David A (Arthritis Research and Therapy, 2017-12)
      Background: An important role for synovial pathology in the initiation and progression of knee osteoarthritis has been emphasised recently. This study aimed to examine whether ultrasonography-detected synovial changes associate with knee pain (KP) in a community population. Methods: A case-control study was conducted to compare people with early KP (n = 298), established KP (n = 100) or no KP (n = 94) at baseline. Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) between groups adjusted for radiographic osteoarthritis (ROA) severity and other confounding factors. After 1 year, 255 participants with early and established KP completed the follow-up questionnaire for changes in KP. Logistic regression with adjustment was used to determine predictors of KP worsening. Results: At baseline, effusion was associated with early KP (OR 2.64, 95% CI 1.57-4.45) and established KP (OR 5.07, 95% CI 2.74-9.38). Synovial hypertrophy was also associated with early KP (OR 5.43, 95% CI 2.12-13.92) and established KP (OR 13.27, 95% CI 4.97-35.43). The association with effusion diminished when adjusted for ROA. Power Doppler signal was uncommon (early KP 3%, established KP 2%, controls 0%). Baseline effusion predicted worsening of KP at 1 year (OR 1.95, 95% CI 1.05-3.64). However, after adjusting for ROA, the prediction was insignificant (adjusted OR 0.95, 95% CI 0.44-2.02). Conclusions: Ultrasound effusion and synovial hypertrophy are associated with KP, but only effusion predicts KP worsening. However, the association/prediction is not independent from ROA. Power Doppler signal is uncommon in people with KP. Further study is needed to understand whether synovitis is directly involved in different types of KP.
    • The association of obesity with disease activity, functional ability and quality of life in early rheumatoid arthritis: data from the Early Rheumatoid Arthritis Study/Early Rheumatoid Arthritis Network UK prospective cohorts.

      Walsh, David A (Rheumatology, 2018-07)
      Objectives To examine associations between BMI and disease activity, functional ability and quality of life in RA. Methods Data from two consecutive, similarly designed UK multicentre RA inception cohorts were used: the Early RA Study (ERAS) and the Early RA Network (ERAN). Recruitment figures/median follow-up for the ERAS and ERAN were 1465/10 years (maximum 25 years), and 1236/6 years (maximum 10 years), respectively. Standard demographic and clinical variables were recorded at baseline and annually. Multilevel piecewise longitudinal models with a change point at 2 years were used with the 28-joint DAS (DAS28), ESR, HAQ and 36-item Short Form Health Survey (SF-36) physical (PCS) and mental (MCS) components as dependent variables. BMI was examined in separate models as both continuous and categorical variables (based on World Health Organization definitions) and up to 5 years from disease onset. Results BMI data from 2386 newly diagnosed RA patients (11 348 measures) showed an increase in BMI of 0.27 U annually (95% CI 0.21, 0.33). Baseline obesity was associated with a significant reduction in the odds of achieving a low year 2 DAS28 [OR 0.52 (95% CI 0.41, 0.650)]. At year 2, HAQ and SF-36 PCS scores were significantly worse but not at year 5 in patients obese at baseline. Obesity at year 2 was associated with higher DAS28 scores at year 2, but not at year 5, and also associated with significantly higher HAQ and SF-36 PCS scores at years 2 and 5. Conclusion Obesity prevalence is rising in early RA and associates with worse disease activity, function and health-related quality of life, with a significant negative impact on achieving a low DAS28. The data argue strongly for obesity management to become central to treatment strategies in RA.
    • Associations of symptomatic knee Osteoarthritis with histopathologic features in subchondral bone.

      Walsh, David A; Wilson, Deborah; Hill, Roger (2019-01-21)
      OBJECTIVES: Subchondral bone and the osteochondral junction are thought to contribute to osteoarthritis (OA) knee pain. We aimed to identify osteochondral pathologies specifically associated with symptomatic human knee OA. METHODS: Two groups of medial tibial plateau (n=31 per group) were matched for macroscopic chondropathy scores. One group had undergone total knee replacement for OA knee pain (symptomatic chondropathy). The other had not sought help for knee pain and died from unrelated illness (asymptomatic chondropathy). OA histopathology, immunoreactivity for nerve growth factor (NGF) and CD68 (macrophages), tartrate resistant acid phosphatase (TRAP)-positive subchondral osteoclasts and synovitis were compared between groups. RESULTS: Mankin score, subchondral bone density and subchondral CD68-immunoreactive macrophage infiltration were similar between the 2 groups. NGF-like immunoreactivity was in subchondral mononuclear cells and osteoclasts, as well as in chondrocytes. NGF in osteochondral channels, and osteoclast densities in subchondral bone were higher in symptomatic than in asymptomatic chondropathy groups (NGF; p<0.01, TRAP; p=0.02), as also were synovitis scores (p<0.01). Osteochondral pathology was not significantly associated with synovitis score. The differences in NGF expression and in osteoclast density remained significant after adjusting for age and synovitis score (NGF; p=0.01, TRAP; p=0.04). Osteochondral NGF and osteoclast densities, together with synovitis scores, explained approximately 28% of sample allocation to symptomatic or asymptomatic groups. CONCLUSION: Subchondral pathology was associated with symptomatic knee OA independently of chondropathy and synovitis. Increased NGF expression in osteochondral channels, and osteoclast density appear be key features associated with bone pain in knee OA.
    • Augmented pain behavioural responses to intra-articular injection of nerve growth factor in two animal models of osteoarthritis

      Walsh, David A (Annals of the Rheumatic Diseases, 2014-09)
      Objectives: Nerve growth factor (NGF) is a promising analgesic target, particularly in osteoarthritis (OA) where existing therapies are inadequate. We hypothesised that pain responses to NGF are increased in OA joints. Here, NGF-evoked pain behaviour was compared in two rodent models of OA, and possible mechanisms underlying altered pain responses were examined. Methods: OA was induced in rat knees by meniscal transection (MNX) or intra-articular monosodium iodoacetate injection (MIA). Once OA pathology was fully established (day 20), we assessed pain behaviour (hindlimb weight-bearing asymmetry and hindpaw mechanical withdrawal thresholds) evoked by intra-articular injection of NGF (10 µg). Possible mechanisms underlying alterations in NGF-induced pain behaviour were explored using indomethacin pretreatment, histopathological evaluation of synovitis, and rtPCR for NGF receptor (tropomyosin receptor kinase (Trk)-A) expression in dorsal root ganglia (DRG). Results: Both the MIA and MNX models of OA displayed reduced ipsilateral weight bearing and hindpaw mechanical withdrawal thresholds, mild synovitis and increased TrkA expression in DRG. NGF injection into OA knees produced a prolonged augmentation of weight-bearing asymmetry, compared to NGF injection in non-osteoarthritic knees. However, hindpaw mechanical withdrawal thresholds were not further decreased by NGF. Pretreatment with indomethacin attenuated NGF-facilitated weight-bearing asymmetry and reversed OA-induced ipsilateral TrkA mRNA up-regulation. Conclusions: OA knees were more sensitive to NGF-induced pain behaviour compared to non-osteoarthritic knees. Cyclo-oxygenase products may contribute to increased TrkA expression during OA development, and the subsequent increased NGF sensitivity. Treatments that reduce sensitivity to NGF have potential to improve OA pain.
    • Baseline factors predicting change from the initial DMARD treatment during the first 2 years of rheumatoid arthritis: experience in the ERAN inception cohort

      Walsh, David A (2013-05)
      BACKGROUND: Outcomes in early Rheumatoid Arthritis (RA) may be improved by rapidly establishing a stable and effective disease modifying anti-rheumatic drug (DMARD) treatment regimen. We aimed to investigate whether baseline factors and initial treatment strategies are associated with changes to the first DMARD treatment, due to either Lack of Efficacy (LoE) or Adverse Drug Reaction (ADR) within 2 years of presentation. METHODS: Reasons for changes from initial DMARD therapy within 2 years of baseline, and associated factors, were examined using logistic regression in data from the Early RA Network (ERAN) inception cohort. RESULTS: Data were available for 766 participants. 410 (54%) changed their initial DMARD regime within 2 years, including 230 (56%) due to Lack of Efficacy (LoE) and 139 (34%) due to Adverse Drug Reaction (ADR). The first DMARD was recorded as methotrexate monotherapy in 336 (44%), sulphasalazine monotherapy in 273 (36%), or combined methotrexate/sulphasalazine/hydroxychlorquine in 52 (7%).Baseline predictors of changing DMARD (for all reasons) were HAQ-disability (aOR 1.44, 95% CI 1.12 - 1.86), poor mental health (aOR 1.44, 95% CI 1.16 - 1.78) and extra-articular disease (aOR 1.78, 95% CI 1.00 - 3.16). In this model, the triple combination therapy also predicted lower likelihood of DMARD change (aOR 0.30, 95% CI 0.12 - 0.79).Subgroup analyses showed that MTX monotherapy was associated with lower risk of change due to ADR. Combination therapy conferred lower risk of change due to LoE. Poor mental health was associated with change due to ADR, and extra-articular disease, HAQ-disability at baseline, and younger age predicted LoE. CONCLUSIONS: Our findings suggest that non-pharmacological interventions to improve disability and mental health, may reduce initial DMARD treatment failure.
    • Baseline self-report 'central mechanisms' trait predicts persistent knee pain in the Knee Pain in the Community (KPIC) cohort

      Walsh, David A (2019-12)
      Objectives: We investigated whether baseline scores for a self-report trait linked to central mechanisms predict 1 year pain outcomes in the Knee Pain in the Community cohort. Method: 1471 participants reported knee pain at baseline and responded to a 1-year follow-up questionnaire, of whom 204 underwent pressure pain detection thresholds (PPTs) and radiographic assessment at baseline. Logistic and linear regression models estimated the relative risks (RRs) and associations (β) between self-report traits, PPTs and pain outcomes. Discriminative performance for each predictor was compared using receiver-operator characteristics (ROC) curves. Results: Baseline Central Mechanisms trait scores predicted pain persistence (Relative Risk, RR = 2.10, P = 0.001) and persistent pain severity (β = 0.47, P < 0.001), even after adjustment for age, sex, BMI, radiographic scores and symptom duration. Baseline joint-line PPTs also associated with pain persistence (RR range = 0.65 to 0.68, P < 0.02), but only in univariate models. Lower baseline medial joint-line PPT was associated with persistent pain severity (β = -0.29, P = 0.013) in a fully adjusted model. The Central Mechanisms trait model showed good discrimination of pain persistence cases from resolved pain cases (Area Under the Curve, AUC = 0.70). The discrimination power of other predictors (PPTs (AUC range = 0.51 to 0.59), radiographic OA (AUC = 0.62), age, sex and BMI (AUC range = 0.51 to 0.64), improved significantly (P < 0.05) when the central mechanisms trait was included in each logistic regression model (AUC range = 0.69 to 0.74). Conclusion: A simple summary self-report Central Mechanisms trait score may indicate a contribution of central mechanisms to poor knee pain prognosis. (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)
    • Beliefs about the causes and consequences of pain in patients with chronic inflammatory or noninflammatory low back pain and in pain-free individuals

      Walsh, David A (Spine, 2008-04)
      Study design: Case control study including 2 groups of patients with low back pain (LBP, inflammatory and noninflammatory) and a pain-free community control group. Objective: We explored whether pain beliefs differ between patients with chronic LBP attributed to inflammatory or noninflammatory medical diagnoses, and between patients with chronic LBP and pain-free controls. Summary of background data: Beliefs strongly influence patients' engagement in and response to treatments for chronic LBP. It is unclear, however, whether unhelpful beliefs held by patients with chronic LBP are predominantly associated with diagnosis, or with other aspects of the patient's pain experience. Methods: Patients and controls completed the pain beliefs questionnaire addressing beliefs about the causes and consequences of pain. Patients also completed questionnaires addressing catastrophizing (Coping Strategies Questionnaire), physical disability and bodily pain (SF-36 Health Survey), and psychological distress (Spielberger State-Trait Anxiety Inventory Short Form and Cognitive Depression Index). Variance analysis and chi2 test were used as appropriate, adjusting for effects of covariates and multiple comparisons. Linear regression and logistic regression were used to adjust for confounding factors. Results: Patients with noninflammatory LBP more strongly endorsed organic pain beliefs (e.g., that pain necessarily indicates damage), and catastrophizing (e.g., that the pain is never going to get better), than did patients with inflammatory LBP (P < 0.01). Patients with inflammatory LBP, in turn, more strongly endorsed organic pain beliefs than did pain-free controls (P < 0.05). Endorsement of organic pain beliefs was associated with catastrophizing. Conclusion: Organic pain beliefs are associated with increased catastrophizing in patients with chronic LBP, and addressing these beliefs may help patients to manage their pain and disability. Meanings attributed to inflammatory and noninflammatory diagnostic labels may contribute to the different pain beliefs held by different patient groups.
    • Bidirectional association between disturbed sleep and neuropathic pain symptoms: a prospective cohort study in post-total joint replacement participants

      Walsh, David A (Journal of Pain Research, 2018-06)
      Background: Disturbed sleep is strongly correlated with chronic pain. The aim of this study was to examine the association between sleep disturbance and incident joint pain focusing on neuropathic-like pain symptoms. Methods: A total of 423 individuals who had undergone total joint replacement (TJR) for osteoarthritis were assessed at the mean time of 3.6 years post-surgery and again at 5.9 years post-TJR, using the Medical Outcomes Survey sleep subscale, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and painDETECT questionnaire instruments. Cox hazard ratios (HRs) and 95% confidence intervals (CIs) were computed adjusting for age, body mass index, sex, and use of hypnotic and analgesic medication. Results: The presence of neuropathic pain symptoms predicted incidence of disturbed sleep after adjustment for covariates and pain severity (adjusted HR [aHR] 2.01, 95% CI: 1.00–4.10; p<0.05). There was no association between joint pain and incidence of disturbed sleep when individuals with neuropathic pain symptoms at the baseline visit were excluded (aHR 1.11, 95% CI: 0.47–2.67). Disturbed sleep at baseline predicted incident neuropathic joint pain symptoms (aHR 2.75, 95% CI: 1.21–6.26; p<0.016) but had no effect on incidence of joint pain when all types of pain were considered together (aHR 0.63, 95% CI: 0.30–1.39). Conclusion: These data suggest a causal bidirectional link between sleep disturbance and joint pain with neuropathic features but not with other types of joint pain.
    • Blocking the Tropomyosin receptor kinase A (TrkA) receptor inhibits pain behaviour in two rat models of osteoarthritis

      Walsh, David A (Annals of the Rheumatic Diseases, 2016-06)
      Objectives: Tropomyosin receptor kinase A (TrkA) mediates nociceptor sensitisation by nerve growth factor (NGF), but it is unknown whether selective TrkA inhibition will be an effective strategy for treating osteoarthritis (OA) pain. We determined the effects of a TrkA inhibitor (AR786) on pain behaviour, synovitis and joint pathology in two rat OA models. Methods: Knee OA was induced in rats by intra-articular monosodium-iodoacetate (MIA) injection or meniscal transection (MNX) and compared with saline-injected or sham-operated controls. Pain behaviour was assessed as weight-bearing asymmetry and paw withdrawal threshold to punctate stimulation. Oral doses (30 mg/kg) of AR786 or vehicle were administered twice daily in either preventive (day -1 to -27) or treatment (day 14-28) protocols. Effect maintenance was evaluated for 2 weeks after treatment discontinuation. Alterations in knee structure (cartilage, subchondral bone and synovium) were examined by macroscopic visualisation of articular surfaces and histopathology. Results: Preventive AR786 treatment inhibited pain behaviour development and therapeutic treatment attenuated established pain behaviour. Weight-bearing asymmetry increased 1 week after treatment discontinuation, but remained less than in vehicle-treated arthritic rats, whereas paw withdrawal thresholds returned to levels of untreated rats within 5 days of treatment discontinuation. AR786 treatment reduced MIA-induced synovitis and did not significantly affect osteochondral pathology in either model. Conclusions: Blocking NGF activity by inhibiting TrkA reduced pain behaviour in two rat models of OA. Analgesia was observed both using preventive and treatment protocols, and was sustained after treatment discontinuation. Selective inhibitors of TrkA therefore hold potential for OA pain relief.
    • Bone sialoprotein as a potential key factor implicated in the pathophysiology of osteoarthritis

      Walsh, David A (Osteoarthritis and Cartilage, 2014-04)
      Objective: We previously identified an association between bone sialoprotein (BSP) and osteoarthritic (OA) chondrocyte hypertrophy but the precise role of BSP in ostearthritis (OA) has not been extensively studied. This study aimed to confirm the association between BSP and OA chondrocyte hypertrophy, to define its effect on molecules produced by chondrocytes and to analyse its association with cartilage degradation and vascular density at the osteochondral junction. Method: Human OA chondrocytes were cultivated in order to increase hypertrophic differentiation. The effect of parathyroid hormone-related peptide (PTHrP), interleukin (IL)-1β or tumour necrosis factor (TNF)-α on BSP was analysed by real-time reverse transcription polymerase chain reaction (RT-PCR) and western blot. The effects of BSP on OA chondrocytes production of inflammatory response mediators (IL-6, nitric oxide), major matrix molecule (aggrecan), matrix metalloprotease-3 and angiogenic factors (vascular endothelial growth factor, basic fibroblast growth factor, IL-8, and thrombospondin-1) were investigated. BSP was detected by immunohistochemistry and was associated with cartilage lesions severity and vascular density. Results: PTHrP significantly decreased BSP, confirming its association with chondrocyte hypertrophy. In presence of IL-1β, BSP stimulated IL-8 synthesis, a pro-angiogenic cytokine but decreased the production of TSP-1, an angiogenesis inhibitor. The presence of BSP-immunoreactive chondrocytes in cartilage was associated with the severity of histological cartilage lesions and with vascular density at the osteochondral junction. Conclusion: This study supports the implication of BSP in the pathology of OA and suggests that it could be a key mediator of the hypertrophic chondrocytes-induced angiogenesis. To control chondrocyte hypertrophic differentiation is promising in the treatment of OA.
    • Can Rheumatologists Predict Eventual Need for Orthopaedic Intervention in Patients with Rheumatoid Arthritis? Results of a Systematic Review and Analysis of Two UK Inception Cohorts.

      Walsh, David A (2017-03)
      Purpose of Review: The structural damage caused by rheumatoid arthritis (RA) can often be mitigated by orthopaedic surgery in late disease. This study evaluates the value of predictive factors for orthopaedic intervention. Methods: A systematic review of literature was undertaken to identify papers describing predictive factors for orthopaedic surgery in RA. Manuscripts were selected if they met inclusion criteria of cohort study design, diagnosis of RA, follow-up duration/disease duration ≥3 years, any orthopaedic surgical interventions recorded, and then summarised for predictive factors. A separate predictive analysis was performed on two consecutive UK Early RA cohorts, linked to national datasets. Recent Findings: The literature search identified 15 reports examining predictive factors for orthopaedic intervention, 4 inception, 5 prospective and 6 retrospective. Despite considerable variation, acute phase, x-ray scores, women and genotyping were the most commonly reported prognostic markers. The current predictive analysis included 1602 procedures performed in 711 patients (25-year cumulative incidence 26%). Earlier recruitment year, erosions and lower haemoglobin predicted both intermediate and major surgery (P<0.05). Studies report variations in type of and predictive power of clinical and laboratory parameters for different surgical interventions suggesting specific contributions from different pathological and/or patient-level factors. Our current analysis suggests that attention to non-inflammatory factors in addition to suppression of inflammation is needed to minimise the burden of orthopaedic surgery.
    • Cannabinoid CB2 receptors regulate central sensitization and pain responses associated with osteoarthritis of the knee joint.

      Walsh, David A (PLoS One, 2013-11)
      Osteoarthritis (OA) of the joint is a prevalent disease accompanied by chronic, debilitating pain. Recent clinical evidence has demonstrated that central sensitization contributes to OA pain. An improved understanding of how OA joint pathology impacts upon the central processing of pain is crucial for the identification of novel analgesic targets/new therapeutic strategies. Inhibitory cannabinoid 2 (CB2) receptors attenuate peripheral immune cell function and modulate central neuro-immune responses in models of neurodegeneration. Systemic administration of the CB2 receptor agonist JWH133 attenuated OA-induced pain behaviour, and the changes in circulating pro- and anti-inflammatory cytokines exhibited in this model. Electrophysiological studies revealed that spinal administration of JWH133 inhibited noxious-evoked responses of spinal neurones in the model of OA pain, but not in control rats, indicating a novel spinal role of this target. We further demonstrate dynamic changes in spinal CB2 receptor mRNA and protein expression in an OA pain model. The expression of CB2 receptor protein by both neurones and microglia in the spinal cord was significantly increased in the model of OA. Hallmarks of central sensitization, significant spinal astrogliosis and increases in activity of metalloproteases MMP-2 and MMP-9 in the spinal cord were evident in the model of OA pain. Systemic administration of JWH133 attenuated these markers of central sensitization, providing a neurobiological basis for analgesic effects of the CB2 receptor in this model of OA pain. Analysis of human spinal cord revealed a negative correlation between spinal cord CB2 receptor mRNA and macroscopic knee chondropathy. These data provide new clinically relevant evidence that joint damage and spinal CB2 receptor expression are correlated combined with converging pre-clinical evidence that activation of CB2 receptors inhibits central sensitization and its contribution to the manifestation of chronic OA pain. These findings suggest that targeting CB2 receptors may have therapeutic potential for treating OA pain.
    • Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA): protocol for a prospective observational study

      Wilson, Deborah; Walsh, David A (2021-06)
      Background: Pain and fatigue are persistent problems in people with rheumatoid arthritis. Central sensitisation (CS) may contribute to pain and fatigue, even when treatment has controlled inflammatory disease. This study aims to validate a self-report 8-item questionnaire, the Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA) questionnaire, developed to measure central pain mechanisms in RA, and to predict patient outcomes and response to treatment. A secondary objective is to explore mechanisms linking CS, pain and fatigue in people with RA. Methods/design: This is a prospective observational cohort study recruiting 250 adults with active RA in secondary care. The CAP-RA questionnaire, demographic data, medical history, and patient reported outcome measures (PROMs) of traits associated with central sensitization will be collected using validated questionnaires. Quantitative sensory testing modalities of pressure pain detection thresholds, temporal summation and conditioned pain modulation will be indices of central sensitization, and blood markers, swollen joints and ultrasound scans will be indices of inflammation. Primary data collection will be at baseline and 12 weeks. The test-retest reliability of CAP-RA questionnaire will be determined 1 week after the baseline visit. Pain and fatigue data will be collected weekly via text messages for 12 weeks. CAP-RA psychometric properties, and predictive validity for outcomes at 3 months will be evaluated. Discussion: This study will validate a simple self-report questionnaire against psychophysical indices of central sensitization and patient reported outcome measures of traits associated with CS in a population of individuals with active RA. The application of this instrument in the clinical environment could provide a mechanism-based stratification tool to facilitate the provision of targeted therapy to individuals with pain and fatigue in RA, alongside treatments that target joint inflammation.
    • The Central Aspects of Pain in the Knee (CAP-Knee) questionnaire; a mixed-methods study of a self-report instrument for assessing central mechanisms in people with knee pain

      Walsh, David A (2021-06)
      Pain is the prevailing symptom of knee osteoarthritis. Central sensitisation creates discordance between pain and joint pathology. We previously reported a Central Pain Mechanisms trait derived from eight discrete characteristics: Neuropathic-like pain, Fatigue, Cognitive-impact, Catastrophising, Anxiety, Sleep disturbance, Depression, and Pain distribution. We here validate and show that an 8-item questionnaire, Central Aspects of Pain in the Knee (CAP-Knee) is associated both with sensory- and affective- components of knee pain severity.