Associations between chronic widespread pain, pressure pain thresholds, leptin, and metabolic factors in individuals with knee pain

Health-related quality of life, lifestyle habits and chronic pain in individuals with knee pain - a 2-year follow-up study

INTRODUCTION

Knee pain increases the risk of developing chronic widespread pain (CWP) and knee osteoarthritis (KOA). The prevalence of CWP and KOA has increased, and there is a need for early prevention. Therefore, the aim was to examine the associations of health-related quality of life (HRQoL) and lifestyle habits with chronic pain at a two-year follow-up in individuals with knee pain.

METHODS

A two-year longitudinal cohort study including 251 individuals aged 30-60 years reporting knee pain at baseline. HRQoL was measured via the Short-Form General Health Survey (SF-36), and lifestyle habits included questions on overweight, physical activity, diet, alcohol and tobacco use. Pain was assessed with a pain mannequin. Differences in health status and lifestyle habits over time in groups with unchanged no chronic pain (NCP), transitioned to less and more pain, and unchanged CWP were analysed using Wilcoxon's, McNemar's and Friedman's tests. Multinominal regression analysis was performed to study associations with reporting chronic pain at follow-up.

RESULTS

Reporting better HRQoL across various SF-36 concepts and normal weight at baseline was associated with reporting NCP after two years. A few changes were made regarding HRQoL and lifestyle habits over the course of two years, but an increase in general health was associated with transitioning to less pain.

CONCLUSIONS

During primary care visits for knee pain with a combination of overweight or lower HRQoL, individuals should receive comprehensive attention to prevent the development of CWP. Future studies should investigate the associations further.

Large-Scale Plasma Proteomics to Profile Pathways and Prognosis of Chronic Pain

While increasing peripheral mechanisms related to chronic pain, the plasma proteomics profile associated with it and its prognosis remains elusive. This study utilizes 2923 plasma proteins and chronic pain of 51 644 participants from UK Biobank and finds 474 proteins linked to chronic pain in six sites: head, neck or shoulder, back, stomach or abdominal, hip, and knee, with 11 proteins sharing across pain sites. The identified proteins are largely enriched in immune and metabolic pathways and highly expressed in tissues like lungs and small intestines. Phenome-wide analysis highlights the significance of pain-related proteome on diverse facets of human health, and in-depth Mendelian randomization validates 10 proteins (CD302, RARRES2, TNFRSF1B, BTN2A1, TNFRSF9, COL18A1, TNF, CD74, TNFRSF4, and BTN2A1) as markers of chronic pain. Furthermore, protein sets capable of classifying pain patients and healthy participants, particularly performing best in hip pain (area under curve, AUC = 0.725), are identified. Interestingly, the prediction of pain spreading over ten years achieves an AUC of 0.715, with leptin identified as a crucial predictor. This study delineates proteins associated with various pain conditions and identifies proteins capable of classifying pain and predicting pain spreading, offering benefits for both research and clinical practice.

Association between pain and incident arrhythmias in 422,654 individuals: evidence from the UK Biobank cohort

AIMS

Pain is associated with cardiovascular disease; however, its association with incident arrhythmias is unclear. We assessed associations between different pain characteristics (pain type, chronic pain, chronic widespread pain [chronic widespread pain], chronic musculoskeletal pain [chronic musculoskeletal pain], and number of chronic pain and chronic musculoskeletal pain sites) and incident cardiac arrhythmias, overall and by subtype.

METHODS

The study included 422,654 UK Biobank participants. Pain was ascertained via a touchscreen questionnaire. The outcomes were incident arrhythmias: all cardiac arrhythmias, atrial fibrillation (AF), other (non-AF) cardiac arrhythmias, bradyarrhythmias, and ventricular arrhythmias. Multivariable Cox-proportional regression was used to investigate the associations.

RESULTS

Over a mean (SD) follow-up of 13.19 (1.96) years, 36,860 (8.72%) participants developed arrhythmia. Compared with those without pain, those with chronic localized pain and chronic widespread pain had increased risk of all cardiac arrhythmias (hazard ratio [HR] 1.13, 95% confidence interval [CI], 1.10-1.17; 1.34, 1.19-1.51), AF (1.09, 1.05-1.14; 1.33, 1.15-1.55), and other cardiac arrhythmias (1.17, 1.12-1.22; 1.41, 1.20-1.66). There was evidence of a dose-relationship between number of chronic pain sites and risk of all cardiac arrhythmias, AF and bradyarrhythmias. Effect estimates were significantly larger among participants aged <60 years than those aged ≥60 years, and larger in women than men.

CONCLUSIONS

Chronic pain was associated with cardiac arrhythmias. Whilst causation cannot be assumed in any observational study, there was evidence of both a temporal relationship and dose-relationship. These findings reinforce the need for pain management approaches that include a broad assessment of individuals' risk factors, wider health status, and appropriate vigilance for emerging conditions.

High leptin levels in blood are associated with chronic widespread pain in rheumatoid arthritis

BACKGROUND

High body mass index (BMI) has been shown to have an association with chronic widespread pain (CWP), both in Rheumatoid arthritis (RA) and in other pain conditions such as fibromyalgia. Research on the adipose tissue and it's adipokines, for example the well described leptin, is emerging. The objective of this study was to determine if there is an association between leptin levels in blood and CWP in patients with RA.

METHODS

In this cross-sectional study 334 patients with RA filled in a questionnaire including a pain mannequin and questions on weight, length and waist circumference. Data from the pain mannequin was used to calculate CWP. The subjects also submitted blood samples to a biobank that were used for this study to determine leptin levels using an ELISA-method.

RESULTS

Patients fulfilling the 2019 criteria for CWP in this study had significantly higher leptin levels, waist circumferences and BMI. There was a significant association between leptin levels and CWP, odds ratio (OR) 1.014 (95% confidence interval (CI) 1.007-1.020), p < 0.001. The association remained after adjusting for BMI, gender and age OR 1.008 (95% CI 1.000-1.017), p 0.046. When leptin was divided into quartile groups a trend could be observed where higher leptin values gave higher OR for CWP.

CONCLUSIONS

This study showed an increased occurrence of CWP in RA-patients with high leptin levels. The association between leptin and CWP remained after adjusting for gender, age and BMI or waist circumference. This suggests that not just production of leptin in the adipose tissue, but also other factors such as leptin resistance may play a role. The association between leptin and CWP was strongest in the patients with the highest leptin levels.

TRIAL REGISTRATION

This study is a cross-sectional study without intervention and the cohort used was initiated prior to the implementation of mandatory registration requirements, therefore it is not registered.

Clinical Features and Disease Activity in Psoriatic Arthritis: A Sex-Related Perspective on Leptin and Comorbidity

Background/Objectives: Many studies have addressed the sex differences in patients with psoriatic arthritis, although these are aimed more at describing the phenotype than at investigating the causes underlying these differences. The aims of our study were to assess the presence of clinical features in relation to sex, and to measure the effect on disease activity of different comorbidities in each sex. Methods: This was a cross-sectional study in which the following factors were measured: the clinical features of the disease, disease activity, the physical function and the disease impact. We measured serum leptin levels, to eliminate the effect of obesity on leptin levels, and a leptin/BMI ratio was calculated. The comorbid conditions evaluated included anxiety and depression, and sleep quality. Results: A total of 203 patients participated in this study. The mean age was 54.6 ± 11.3, and 46.8% of the patients were women. Women less frequently presented axial involvement (8% vs. 28%; p < 0.001) and more commonly had enthesitis (2 vs. 0.3; p < 0.001). They also had higher DAPSA (16.4 vs. 13.4; p < 0.001) and PsAID12 scores (4.1 vs. 2.9; p < 0.001), worse HAQ results (0.8 vs. 0.5; p < 0.001), and greater FACIT-F scores (32.7 vs. 38.1; p < 0.001). As for the comorbid conditions, women presented a higher leptin/BMI ratio (0.8 vs. 0.2; p < 0.001), higher levels of HADS-A (6.9 vs. 4.7; p < 0.001) and HADS-D (4.9 vs. 3.4; p < 0.001), and poorer ISI (9.3 vs. 7.0; p < 0.001). By sex, pain affecting women was associated with the leptin/BMI ratio (β: 0.29; p < 0.004; 95%CI: 0.3-1.6) and sleep quality (β: 0.31; p < 0.004; 95%CI: 0.04-0.25; R2: 0.26). The leptin/BMI ratio was not associated with pain in men (p = 0.46). Conclusions: Sex was associated with several clinical manifestations. Leptin/BMI ratio levels were associated with pain in women, but not in men.

IL-6 from cerebrospinal fluid causes widespread pain via STAT3-mediated astrocytosis in chronic constriction injury of the infraorbital nerve

BACKGROUND

The spinal inflammatory signal often spreads to distant segments, accompanied by widespread pain symptom under neuropathological conditions. Multiple cytokines are released into the cerebrospinal fluid (CSF), potentially inducing the activation of an inflammatory cascade at remote segments through CSF flow. However, the detailed alteration of CSF in neuropathic pain and its specific role in widespread pain remain obscure.

METHODS

A chronic constriction injury of the infraorbital nerve (CCI-ION) model was constructed, and pain-related behavior was observed on the 7th, 14th, 21st, and 28th days post surgery, in both vibrissa pads and hind paws. CSF from CCI-ION rats was transplanted to naïve rats through intracisternal injection, and thermal and mechanical allodynia were measured in hind paws. The alteration of inflammatory cytokines in CCI-ION's CSF was detected using an antibody array and bioinformatic analysis. Pharmacological intervention targeting the changed cytokine in the CSF and downstream signaling was performed to evaluate its role in widespread pain.

RESULTS

CCI-ION induced local pain in vibrissa pads together with widespread pain in hind paws. CCI-ION's CSF transplantation, compared with sham CSF, contributed to vibrissa pad pain and hind paw pain in recipient rats. Among the measured cytokines, interleukin-6 (IL-6) and leptin were increased in CCI-ION's CSF, while interleukin-13 (IL-13) was significantly reduced. Furthermore, the concentration of CSF IL-6 was correlated with nerve injury extent, which gated the occurrence of widespread pain. Both astrocytes and microglia were increased in remote segments of the CCI-ION model, while the inhibition of astrocytes in remote segments, but not microglia, significantly alleviated widespread pain. Mechanically, astroglial signal transducer and activator of transcription 3 (STAT3) in remote segments were activated by CSF IL-6, the inhibition of which significantly mitigated widespread pain in CCI-ION.

CONCLUSION

IL-6 was induced in the CSF of the CCI-ION model, triggering widespread pain via activating astrocyte STAT3 signal in remote segments. Therapies targeting IL-6/STAT3 signaling might serve as a promising strategy for the widespread pain symptom under neuropathological conditions.