Prevalence of rheumatoid cachexia in rheumatoid arthritis: a systematic review and meta-analysis

Cachexia in preclinical rheumatoid arthritis: Longitudinal observational study of thigh magnetic resonance imaging from osteoarthritis initiative cohort

BACKGROUND

Preclinical rheumatoid arthritis (Pre-RA) is defined as the early stage before the development of clinical RA. While cachexia is a well-known and potentially modifiable complication of RA, it is not known if such an association exists also in the Pre-RA stage. To investigate such issue, we aimed to compare the longitudinal alterations in the muscle composition and adiposity of participants with Pre-RA with the matched controls.

METHODS

In this observational cohort study, the Osteoarthritis Initiative (OAI) participants were categorized into Pre-RA and propensity score (PS)-matched control groups. Pre-RA was retrospectively defined as the absence of RA from baseline to year-2, with progression to physician-diagnosed clinical RA between years 3-8 of the follow-up period. Using a validated deep learning algorithm, we measured MRI biomarkers of thigh muscles and adiposity at baseline and year-2 follow-ups of the cohort. The outcomes were the differences between Pre-RA and control groups in the 2-year rate of change for thigh muscle composition [cross-sectional area (CSA) and intramuscular adipose tissue (Intra-MAT)] and adiposity [intermuscular adipose tissue (Inter-MAT) and subcutaneous adipose tissue (SAT)]. Linear mixed-effect regression models were used for comparison.

RESULTS

After 1:3 PS-matching of the groups for confounding variables (demographics, risk factors, co-morbidities, and knee osteoarthritis status), 408 thighs (102 Pre-RA and 306 control) of 322 participants were included (age mean ± SD: 61.7 ± 8.9 years; female/male: 1.8). Over a 2-year period, Pre-RA was associated with a larger decrease in total thigh muscle CSA [estimate, 95% confidence interval (CI): -180.13 mm2/2-year, -252.80 to -107.47, P-value < 0.001]. Further examination of thigh muscle composition showed that the association of the presence of Pre-RA with a larger decrease in muscle CSA over 2 years was noticeable in the quadriceps, flexors, and sartorius muscle groups (P-values < 0.05). Comparison of changes in total adipose tissue showed no difference between Pre-RA and control participants (estimate, 95% CI: 48.48 mm2/2-year, -213.51 to 310.47, P-value = 0.691). However, in the detailed analysis of thigh adiposity, Pre-RA presence was associated with a larger increase in Inter-MAT (estimate, 95% CI: 150.55 mm2/2-year, 95.58 to 205.51, P-value < 0.001).

CONCLUSIONS

Preclinical rheumatoid arthritis is associated with a decrease in muscle cross-sectional area and an increase in intermuscular adipose tissue, similar to rheumatoid cachexia in clinical rheumatoid arthritis. These findings suggest the presence of cachexia in the preclinical phase of rheumatoid arthritis. Given that cachexia, which can exacerbate health outcomes, is potentially modifiable, this study emphasizes the importance of early identification of patients in their preclinical phase.

Considerations for the use of biological therapies in elderly patients with rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease that primarily affects middle-aged individuals but is increasingly prevalent among the elderly due to longer life expectancies. Treating elderly onset RA (EORA) is challenging for clinicians because of unique disease characteristics, comorbidities, polypharmacy, age-related physiological changes, and limited studies on the safety and efficacy of biological therapies in this population. This review aims to evaluate the use of various biological therapies in elderly RA patients.

AREAS COVERED

This narrative review examines various aspects of RA in the elderly using published literature, randomized control trials, meta-analyses, and recommendations from the National Institute for Health and Care Excellence (NICE) and The European Alliance of Associations for Rheumatology (EULAR).

EXPERT OPINION

In EORA patients, the initiation of biological therapy is often delayed. Methotrexate remains the first-line treatment for both EORA and young onset RA (YORA). The combination of methotrexate and biological treatment shows comparable safety and efficacy in both EORA and YORA, except for rituximab, which is less effective in patients over 75. For elderly RA patients, biological (b-) disease-modifying antirheumatic drugs (DMARDs) are preferred as the first advanced therapy over targeted synthetic (ts-) DMARDs due to their superior safety profile.

Development and validation of a predictive model assessing the risk of sarcopenia in rheumatoid arthritis patients

Background

Sarcopenia is linked to an unfavorable prognosis in individuals with rheumatoid arthritis (RA). Early identification and treatment of sarcopenia are clinically significant. This study aimed to create and validate a nomogram for predicting sarcopenia risk in RA patients, providing clinicians with a reliable tool for the early identification of high-risk patients.

Methods

Patients with RA diagnosed between August 2022 and January 2024 were included and randomized into training and validation sets in a 7:3 ratio. Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis and multifactorial logistic regression analysis were used to screen the risk variables for RA-associated muscle loss and to create an RA sarcopenia risk score. The predictive performance and clinical utility of the risk model were evaluated by plotting the receiver operating characteristic curve and calculating the area under the curve (AUC), along with the calibration curve and clinical decision curve (DCA).

Results

A total of 480 patients with RA were included in the study (90% female, with the largest number in the 45-59 age group, about 50%). In this study, four variables (body mass index, disease duration, hemoglobin, and grip strength) were included to construct a nomogram for predicting RA sarcopenia. The training and validation set AUCs were 0.915 (95% CI: 0.8795-0.9498) and 0.907 (95% CI: 0.8552-0.9597), respectively, proving that the predictive model was well discriminated. The calibration curve showed that the predicted values of the model were basically in line with the actual values, demonstrating good calibration. The DCA indicated that almost the entire range of patients with RA can benefit from this novel prediction model, suggesting good clinical utility.

Conclusion

This study developed and validated a nomogram prediction model to predict the risk of sarcopenia in RA patients. The model can assist clinicians in enhancing their ability to screen for RA sarcopenia, assess patient prognosis, make early decisions, and improve the quality of life for RA patients.

Effect of dietary interventions on nutritional status in patients with rheumatoid arthritis and spondyloarthritis - A systematic review and meta-analysis

BACKGROUND & AIM

Patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) have an increased risk of developing altered body composition, such as low muscle mass, and an increased risk of developing cardiovascular diseases (CVD). Thus, investigating how to improve body composition and CVD risk factors is a relevant topic to improve management of RA and SpA. The aim of this study was to identify dietary interventions that can improve body composition, as well as reduce CVD risk factors in RA and SpA.

METHODS

We searched the databases Medline, Embase and Cochrane. Duplicates were removed using Endnote and records were screened through Rayyan. The primary outcomes were muscle mass (kg) and fat mass (kg). Secondary outcomes were body weight (kg), body mass index (BMI: kg/m2), waist circumference (cm) and lipid profile (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, mmol/L).

RESULTS

A total of 4965 articles were identified, and 17 articles were included in this review, of which 15 were suitable for meta-analysis. We found a reduction in TC and LDL-C, (Mean difference, [95%CI]: -0.36, [-0.63, -0.10], I2 = 43%, and -0.20, [-0.35, -0.05], I2 = 0% respectively). Otherwise, no other significant effect was seen in either primary or secondary outcomes. The evidence was graded as moderate for TC and low for LDL-C.

CONCLUSION

Dietary interventions might reduce the levels of blood lipids, and consequently, the risk of cardiovascular diseases. However, body composition did not change significantly after a 2-4 month dietary intervention. Both short intervention period and lack of reliable methods to assess body composition are possible explanations for this finding. Further studies of longer duration are needed.

The Effect of Rheumatoid Arthritis on Features Associated with Sarcopenia: A Mendelian Randomization Study

Previous epidemiological evidence suggests rheumatoid arthritis is associated with sarcopenia-related features. However, most of the current evidence is from cross-sectional studies, and the causal link of this association is still to be determined. Therefore, this study was committed to a two-sample Mendelian randomization analysis to assess the causal effect of rheumatoid arthritis on sarcopenia-related features. In this two-sample Mendelian randomization study, instrumental variables for rheumatoid arthritis were obtained from the Non-Cancer Disease Study, and data for the five relevant characteristics of sarcopenia were pooled from UKBiobank. Inverse variance weighting is the primary analysis method for assessing causal effects. MR-Egger regression and weighted median are complementary analysis methods for causal effects. Leave-one-out analysis, horizontal pleiotropy test, and Heterogeneity test are applied as a sensitivity analysis to assess the robustness of causal effect estimates. The inverse variance weighted results for the five characteristics associated with sarcopenia and rheumatoid arthritis were: hand grip strength (right) (beta = - 2.309, se = 0.206, p = 3.340E-29), hand grip strength (left) (beta = - 2.046, se = 0.205, p = 2.166E-23), whole body lean mass (beta = - 0.843, se = 0.135, p = 4.67E-10), appendicular lean mass (beta = - 2.444, se = 0.208, p = 6.069E-32), Usual walking pace (OR 0.340, 95% CI (0.238, 0.484), p = 2.471E-09). The sensitivity analyses did not support that horizontal pleiotropy distorted causal effect estimates. The beta coefficient quantifies the number of standard deviations of the continuous outcome variables (hand grip strength, whole body lean mass, and appendicular lean mass) that change on average with each increase in the standard deviation of the binary exposure variable (rheumatoid arthritis). The odds ratios indicate the increased risk of the binary outcome variable (usual walking pace) per rheumatoid arthritis standard deviation increase. This study has demonstrated a negative causal effect of rheumatoid arthritis with five major sarcopenia-related features in a European population.

Consensus statement on the management of late-onset rheumatoid arthritis

OBJECTIVES

Late-onset rheumatoid arthritis (LORA), which has been increasing in recent years, lacks evidence for initial treatment. Japanese rheumatology experts recognized this gap and addressed it by developing consensus statements on the first clinical application of LORA.

METHODS

These statements were created following an introductory discussion about treatment fundamentals, which included a review of existing literature and cohort data. The steering committee created a draft, which was refined using a modified Delphi method that involved panel members reaching a consensus. The panel made decisions based on input from geriatric experts, clinical epidemiologists, guideline developers, patient groups, and the LORA Research Subcommittee of the Japan College of Rheumatology.

RESULTS

The consensus identified four established facts, three basic approaches, and six expert opinions for managing LORA. Methotrexate was recommended as the primary treatment, with molecular-targeted agents being considered if treatment goals cannot be achieved. An emphasis was placed on assessing the lives of older patients due to challenges in risk management and methotrexate accessibility caused by comorbidities or cognitive decline.

CONCLUSIONS

The experts substantiated and refined 13 statements for the initial treatment of LORA. To validate these claims, the next is to conduct a registry study focusing on new LORA cases.

Increased contractile activity and dilation of popliteal lymphatic vessels in the TNF-α-overexpressing TNFΔARE/+ arthritic mouse

AIMS

TNF-α acute treatment has been found to disrupt lymphatic drainage in the setting of arthritis through the NF-kB-iNOS- signaling pathway. We examined whether popliteal lymphatic vessels (pLVs) contractile activity was altered in 12- and 24- week-old females of an arthritic mouse model overexpressing TNF-α (TNFΔARE/+).

MAIN METHODS

pLVs were prepared for intravital imaging to measure lymph flow speed, and ex vivo functional responses to a stepwise increase in transmural pressure in the absence or presence of the non-selective NOS inhibitor (L-NNA) or the selective iNOS inhibitor (1400W) were compared between TNFΔARE/+ and WT mice. Total eNOS (t-eNOS) and eNOS phosphorylated at ser1177 (p-eNOS) were evaluated by western blotting.

KEY FINDINGS

In vivo imaging revealed a significantly increase in lymph flow speed in TNFΔARE/+ mice in comparison to WT at both ages. Pressure myography showed an increase in contraction frequency, diameters and fractional pump flow at both ages, whereas amplitude and ejection fraction were significantly decreased in older TNFΔARE/+ mice. Additionally, contraction frequency was increased in the presence of 1400W, and systolic diameter was abolished with L-NNA in TNFΔARE/+ mice compared to WT. Significant increases in p-eNOS expression and neutrophil recruitment (MPO activity) were observed in TNFΔARE/+ mice compared to WT.

SIGNIFICANCE

Our data reveal functional changes in pLVs, especially in advanced stage of arthritis. These alterations may be related to eNOS and iNOS response, which can affect drainage of the inflammatory content from the joints.

Tumor Necrosis Factor Alpha Inhibitors and Cardiovascular Risk in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by an increased risk of cardiovascular events, due to the complex interplay between traditional and disease-related risk factors. Chronic inflammation and persistent disease activity are the key determinants of this risk, but despite great improvement in the disease management and prognosis, cardiovascular events are still the main cause of morbidity and mortality in RA cohorts1. In the last decades, the advent of new biological and targeted-synthetic DMARDs was accompanied by an improvement in disease activity control, but the role of each class of drugs on CVD risk is still a matter a debate. Since their approval for RA treatment, tumor necrosis factor alpha (TNFα) inhibitors have been widely investigated to better understand their effects on cardiovascular outcomes. The hypothesis that the reduction of chronic inflammation with any treatment may reduce the cardiovascular risk has been recently confuted by the direct comparison of TNFα-inhibitors and JAK inhibitors in patients with RA and coexisting risk factors for cardiovascular disease. The aim of this literature review is to add to the available evidence to analyze the relationship between TNFα-inhibitors and CVD risk in patients with RA and also provide some clinical scenarios to better explain the treatment dilemmas. In particular, while data on major cardiovascular events and thromboembolism seem consistent with an inflammation-mediated benefit with TNFα-inhibitors, there remain concerns about the use of this class of bDMARDs in patients with chronic heart failure.

Effects of Aerobic and Resistive Exercise on Muscle Measurements and Body Composition in Female Patients With Rheumatoid Arthritis

OBJECTIVE

This study aimed to show the effects of different exercise types on disease activity, pain, functional status, and quality of life in female patients with rheumatoid arthritis with low disease activity or in remission and supported these findings with body composition and muscle measurements.

DESIGN

This randomized controlled prospective study screened female patients aged 20-50 years with rheumatoid arthritis. The patients were randomized into 12-wk resistance exercise, aerobic exercise, and control groups.

RESULTS

The mean age of the 66 patients was 42.5 ± 5.6 yrs. In the resistance and aerobic exercise groups compared with the control group, a positive significant difference was found in the pain, disease activity, several subparameters of quality of life, M. gastrocnemius, and M. biceps femoris muscle thickness measurements, and fat mass in the lower limbs before and after treatment ( P < 0.05). Compared with the other groups, the resistance exercise group showed a significant improvement in M. rectus femoris and M. vastus intermedius muscle thickness measurements, whole body fat mass, whole body and lower extremity lean body mass, and timed up and go test when comparing before and after treatment ( P < 0.05).

CONCLUSIONS

In rheumatoid arthritis patients, resistance exercises led to a significant increase in muscle thickness, functional status, lean body mass compared with other exercises; resistance exercises also resulted in a significant reduction in pain and disease activity.

Cachexia Prevalence in a Population of Moroccan Women with Rheumatoid Arthritis

Objective

To assess body composition in women with rheumatoid arthritis (RA) compared to healthy controls, to calculate the prevalence of rheumatoid Cachexia (RC), and to identify the associated factors.

Methods

We conducted a case-control study on 112 female patients with RA according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA; and 224 age-matched healthy women. Body composition (BC) and bone mineral density (BMD) scans were obtained using Dual-energy X-ray absorptiometry (DXA). RC was defined by a fat-free mass index (FFMI) below the 10th percentile and a fat mass index (FMI) above the 25th percentile compared with the control group. We conducted a comparison between RA patients and healthy controls then a multiple regression analysis was conducted where the dependant variable is the presence of RC.

Results

RC prevalence was 42.85% while the mean body mass index (BMI) was the same in both groups. RA patients had a higher FM and lower FFM comparing to healthy controls. In our population, 78.60% of patients were on methotrexate and 12.50% on anti TNF therapy. Comparison between patients with and without RC showed that patients with RC have a higher proportion of erosive arthritis and of active disease. Regression logistic analysis showed that RC was significantly associated to erosive arthritis and active disease (OR at 33.31 (8.42-131.70) and 8.98 (1.64-49.20) respectively), independently of age, erythrocyte sedimentation rate, C-reactive protein, disease duration, steroid cumulative dose and biologic Disease-Modifying Anti-Rheumatic Drugs(bDMARDs) use.

Conclusion

Our study showed that almost half of our RA patients have RC, even with a high BMI.

Effect of Filgotinib on Body Mass Index (BMI) and Effect of Baseline BMI on the Efficacy and Safety of Filgotinib in Rheumatoid Arthritis

INTRODUCTION

This post hoc analysis of the phase 3 rheumatoid arthritis (RA) filgotinib clinical trial program assessed the effect of filgotinib on body mass index (BMI) in patients with RA and the impact of BMI on the efficacy and safety of filgotinib.

METHODS

FINCH 1-3 were randomized, double-blind, active- or placebo-controlled phase 3 trials of filgotinib 100 and 200 mg in patients with RA (N = 3452). BMI assessments included the mean change from baseline in BMI and the proportion of patients whose BMI increased by incremental thresholds. Efficacy measures included American College of Rheumatology (ACR) 20/50/70 response and low disease activity/remission according to Disease Activity Score 28 using C-reactive protein. The exposure-adjusted incident rate (EAIR) of adverse events (AEs) was assessed by baseline BMI, using integrated data from the FINCH 1-4 and the phase 2 DARWIN 1-3 studies (total filgotinib exposure = 8085 patient-years).

RESULTS

Mean change from baseline in BMI over time was similar across treatment arms. In most patients, BMI increased by ≤ 1 or 2 kg/m2 at both weeks 12 and 24, regardless of treatment group or baseline BMI; few patients had increases of ≥ 4 kg/m2. For most efficacy measures, filgotinib 200 mg was more efficacious than filgotinib 100 mg or active comparators or placebo across BMI subgroups. For the higher filgotinib dose, the EAIR of serious treatment-emergent AEs, venous thrombotic and embolic events, and major adverse cardiovascular events increased with increasing BMI.

CONCLUSIONS

Filgotinib did not lead to substantial changes in BMI, and BMI did not appear to affect the efficacy of filgotinib.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02889796, NCT02873936, NCT02886728, NCT03025308, NCT01888874, NCT01894516, NCT02065700.

Metabolic Syndrome and Rheumatoid Arthritis Activity: An Analysis of Clinical, Laboratory, and Ultrasound Parameters

(1) Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease associated with an increased incidence of metabolic syndrome (MetS). The aim of this study was to determine if there is an association between MetS and parameters of RA activity, as well as between metabolic parameters and indices of RA activity. (2) Methods: This study involved 65 patients with RA. MetS was diagnosed according to the 2009 IDF/AHA/NHLBI criteria. The comparative analysis was conducted between RA patients with MetS (RA (MetS (+)) and without MetS (RA (MetS (-)). The activity of RA was assessed using clinical, laboratory, and ultrasound (US) parameters. (3) Results: Compared with RA MetS (-) patients, RA MetS (+) patients were characterized by higher disease activity, according to Disease Activity Score (DAS28), Simplified Disease Activity Index (SDAI), and Clinical Disease Activity Index (CDAI). RA MetS (+) patients had significantly higher tender and swollen joint counts, and values of erythrocyte sedimentation rate, C-reactive protein, and US parameters (grey-scale (GSUS), power Doppler (PDUS)). Significant correlations were found between metabolic parameters (waist circumference, cholesterol and glucose concentrations) and indices of RA activity. (4) Conclusion: The results of this study show that, in patients with RA, the presence of MetS is associated with higher disease activity, based on several clinical, laboratory, and US parameters.

Diagnosis and outcomes of cachexia in Asia: Working Consensus Report from the Asian Working Group for Cachexia

Chronic diseases often lead to metabolic disorders, causing anabolic resistance and increased energy consumption, which result in cachexia. Cachexia, in turn, can lead to major clinical consequences such as impaired quality of life, shortened life expectancy, and increased healthcare expenditure. Existing international diagnostic criteria for cachexia employ thresholds derived from Western populations, which may not apply to Asians due to differing body compositions. To address this issue, the Asian Working Group for Cachexia (AWGC) was initiated. The AWGC comprises experts in cachexia research and clinical practice from various Asian countries and aims to develop a consensus on diagnostic criteria and significant clinical outcomes for cachexia in Asia. The AWGC, composed of experts in cachexia research and clinical practice from several Asian countries, undertook three-round Delphi surveys and five meetings to reach a consensus. Discussions were held on etiological diseases, essential diagnostic items for cachexia, including subjective and objective symptoms and biomarkers, and significant clinical outcomes. The consensus highlighted the importance of multiple diagnostic factors for cachexia, including chronic diseases, either or both weight loss or low body mass index, and at least one of the following: anorexia, decreased grip strength (<28 kg in men and <18 kg in women), or elevated C-reactive protein levels (>5 mg/L [0.5 mg/dL]). The AWGC proposed a significant weight change of 2% or more over a 3-6 month period and suggested a tentative cut-off value of 21 kg/m2 for low body mass index in diagnosing cachexia. Critical clinical outcomes were determined to be mortality, quality of life as assessed by tools such as EQ-5D or the Functional Assessment of Anorexia/Cachexia Therapy, and functional status as measured by the Clinical Frailty Scale or Barthel Index, with significant emphasis on patient-reported outcomes. The AWGC consensus offers a comprehensive definition and user-friendly diagnostic criteria for cachexia, tailored specifically for Asian populations. This consensus is set to stimulate future research and enhance the multidisciplinary approach to managing cachexia. With plans to develop further guidelines for the optimal treatment, prevention, and care of cachexia in Asians, the AWGC criteria are expected to drive research across chronic co-morbidities and cancer in Asia, leading to future refinement of diagnostic criteria.

Effects of Tofacitinib on Muscle Remodeling in Experimental Rheumatoid Sarcopenia

Sarcopenia is a frequent comorbidity of rheumatoid arthritis (RA). Clinical trials have shown that JAK inhibitors (JAKi) produce an asymptomatic increase in serum creatine kinase (CK) in RA, suggesting an impact on muscle. We evaluated the effect of JAKi in muscle remodeling in an experimental RA model. Antigen-induced arthritis (experimental RA, e-RA) was performed in 14 rabbits. Seven rabbits received tofacitinib (TOFA, orally 10 mg/kg/day). Animals were euthanized one day after the last ovalbumin injection, and muscles were prepared for histology, RT-PCR, and WB. C-reactive protein (CRP) and Myostatin (MSTN) serum concentration were determined by ELISA. Creatine and creatine kinase (CK) were analyzed. An increase in body weight as well as tibialis anterior cross-sectional area and diameter was observed in e-RA+TOFA vs. e-RA. e-RA decreased type II fibers and increased the myonuclei number, with all reverted by TOFA. TOFA did not modify CRP levels, neither did MSTN. TOFA significantly reduced IL-6, atrogin-1, and MuRF-1 compared with e-RA. e-RA+TOFA showed higher CK and lower creatine levels compared with e-RA. No differences in PAX-7 were found, while TOFA prevented the increase in MyoD1 in e-RA. Our model reflects the features of rheumatoid sarcopenia in RA. JAKi increased muscle mass through attenuating IL-6/JAK/STAT activation, decreasing atrogenes, and restoring muscle differentiation markers. These data together with an increase in CK support the role of CK as a valuable marker of muscle gain following JAKi treatment.

Effects of Exercise on Body Composition and Physical Function in Rheumatoid Arthritis Patients: Scoping Review

Background

In rheumatoid arthritis (RA) patients, an adverse change in body composition, which usually results in muscle wasting and increased fat mass, is high, contributing to increased functional disability. There are indications that resistance and dynamic exercise interventions could improve body composition and functional capacity in RA patients and should be recommended to manage RA.

Purpose

The scoping literature review aimed to analyze available literature about the effects of exercise on body composition in RA patients. Secondly to identify the contribution of exercise to improve physical function in RA patients, thirdly to identify gaps in the literature about physical exercises and health outcomes in RA patients, and make recommendations for future research.

Methods

A scoping literature review design was employed following the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) guidelines. A systematic search of three databases (PubMed, CINAHL, and Scopus) for studies published from 2012 to 2022 was conducted. The words searched include "exercise intervention" AND "body fat" OR "muscle wasting" OR "lean body mass" AND "functional ability" OR "health assessments". The search strategy was limited to studies published in English on RA patients and exercise interventions.

Results

This search yielded 2693 studies, of which 11 met the inclusion criteria and were selected for review. The findings showed significant, positive effects of exercise interventions on RA patients' body composition and functional capacity, with exercise being highly beneficial. It is evident that high-intensity resistance exercise, as a stand-alone intervention, is feasible and safe for managing RA conditions.

Conclusion

Physical exercises, following scientific guidelines, should be included as an integrated approach to managing RA conditions.

Novel aspects of muscle involvement in immune-mediated inflammatory arthropathies and connective tissue diseases

Myalgia, myopathy and myositis are the most important types of muscle impairment in immune-mediated inflammatory arthropathies and connective tissue diseases. Multiple pathogenetic and histological changes occur in the striated muscles of these patients. Clinically, the most important muscle involvement is the one that causes complaints to the patients. In everyday practice, insidious symptoms present a serious problem for the clinician; in many cases, it is difficult to decide when and how to treat the muscle symptoms that are often present only subclinically. In this work, authors review the international literature on the types of muscle problems in autoimmune diseases. In scleroderma histopathological picture of muscle shows a very heterogeneous picture, necrosis and atrophy are common. In rheumatoid arthritis and systemic lupus erythematosus, myopathy is a much less defined concept, further studies are needed to describe it. According to our view, overlap myositis should be recognized as a separate entity, preferably with distinct histological and serological characteristics. More studies are needed to describe muscle impairment in autoimmune diseases which may help to explore this topic more in depth and be of clinical use.

A Mendelian randomization study on causal effects of leisure sedentary behaviour on the risk of rheumatoid arthritis

BACKGROUND

The causal inference between leisure sedentary behaviour (LSB) and rheumatoid arthritis (RA) is still controversial because of potential residual confounding and reverse causality.

METHODS

The present study used publicly available large-scale genome-wide association studies (GWAS) of LSB (television watching, computer use, and driving) and RA to perform a two-sample Mendelian randomization (MR) study to evaluate the causal effect of LSB on the risk of RA. We detected significant causal associations using the multiplicative random effects-inverse variance weighted (MRE-IVW) method, the maximum likelihood, robust adjusted profile scores, the weighted median, MR-Egger regression, and several complementary sensitivity analyses. Risk factor analysis was also conducted to further investigate potential mediators linking causal inference.

RESULTS

Increased genetic liability to leisure television watching was significantly associated with a higher risk of RA (MRE-IVW method; OR = 2.46, 95% CI 1.77-3.41; p = 8.35 × 10^-8 ). MR estimates indicated that prolonged leisure computer use was causally associated with a lower risk of RA (MRE-IVW method; OR = 0.23, 95% CI 0.12-0.46; p = 2.19 × 10^-5 ). However, we found no evidence for a causal effect of leisure driving on the risk of RA (MRE-IVW method; OR = 0.59, 95% CI 0.10-3.41; p = 0.557). No pleiotropy was detected by the sensitivity analysis.

CONCLUSIONS

This study supports a causal association between prolonged leisure television watching and an increased risk of RA. Additionally, prolonged computer use might be a protective factor for RA.

Rheumatoid cachexia in early rheumatoid arthritis: prevalence and associated variables

OBJECTIVE

Rheumatoid cachexia (RC) is prevalent among patients with established rheumatoid arthritis (RA). Although changes in muscle mass and fat mass have been reported in early RA, these findings have not been classified according to existing RC definitions. This study aimed to describe the prevalence of RC and associated variables in patients with early RA.

METHOD

This cross-sectional study included 87 patients. Body composition was evaluated with dual-energy X-ray absorptiometry after a median disease duration of 15 months. RC was defined as a fat-free mass index < 10th percentile and fat mass index > 25th percentile. We also assessed the erythrocyte sedimentation rate (ESR), C-reactive protein, Disease Activity Score in 28 joints, aerobic capacity, physical activity, traditional cardiovascular disease risk factors, functional disability, and sociodemographic data. Associations between RC and the independent variables were determined with logistic regression analyses.

RESULTS

The prevalence of RC was 24%. RC was significantly associated [odds ratio (95% confidence interval)] with aerobic capacity [0.28 (0.09-0.89), p = 0.030], low-intensity physical activity [0.77 (0.60-0.99), p = 0.048], body mass index [0.78 (0.70-0.92), p = 0.002], waist circumference [0.96 (0.92-0.99), p = 0.023], body weight [0.94 (0.90-0.98), p = 0.004], and ESR at the time of diagnosis [1.02 (1.00-1.05), p = 0.033]. All of these associations remained significant after adjusting for age and gender.

CONCLUSION

RC was highly prevalent in early RA. Patient outcome may be improved by detecting this condition early and applying treatments for improving inflammation, aerobic capacity, physical activity, and body composition.

Cachexia measured by bioelectrical impedance vector analysis and risk of infection in women with rheumatoid arthritis

Rheumatoid arthritis (RA) patients have a higher frequency of infections than the healthy population. The reason has yet to be explained but involves several factors, of which body composition and rheumatoid cachexia are often overlooked. This study aimed to evaluate whether patients with cachexia, measured by bioelectrical impedance vector analysis, are at an increased risk of developing infections compared with patients without cachexia. A secondary analysis of 186 women with RA enrolled in a randomized trial (ClinicalTrials.gov ID: NCT02900898, September 14, 2016) was completed. Medical records and phone calls were used to record infectious events diagnosed and treated during follow-up. Hazard ratios were calculated using Cox proportional hazard regression analysis, and a predictive model of infection was created. After 36 months of follow-up, 62 patients (26.7% non-cachectic and 44.3% cachectic, p < 0.01) developed at least one infectious event. The most common site of was the urinary tract, followed by the lungs and respiratory tract. The presence of cachexia (HR 1.90, 95% CI 1.15-3.13) and the use of glucocorticoids (HR 1.77, 95% CI 1.01-3.09) were associated with infection in univariate and multivariate models. Body mass index (BMI), smoking, and methotrexate use were not associated with a higher frequency of infections. The presence of cachexia and the use of glucocorticoids were identified as predictors of infections in a cohort of female RA patients. More extensive measurements of body composition should be performed beyond BMI in RA patients to better understand its impact and to prevent additional comorbidities and complications. Key Points • The presence of cachexia measured by bioelectrical impedance vector analysis was associated with infectious events in women with rheumatoid arthritis, whereas body mass index did not show an association. • Glucocorticoids were the only drug associated with a higher frequency of infection. None of the disease-modifying antirheumatic drugs, including methotrexate, showed an association.

A Scoping Review of the Use of Pioglitazone in the Treatment of Temporo-Mandibular Joint Arthritis

Thiazolidinediones (TZDs) are a group of diabetes medications currently being investigated for anti-arthritis effectiveness, one of which is pioglitazone. The purpose of this scoping review is to evaluate the potential use of pioglitazone in the treatment of temporomandibular joint (TMJ) arthritis. The criteria of eligibility were studies with the diagnosis of arthritis and pioglitazone treatment with a change in any inflammation index as an outcome. Of the 1169 records initially identified following the selection process, two animal studies and four clinical studies were included in the review. Improvements from the baseline were observed in each treatment group for each inflammation indicator. The results of the animal studies on the temporomandibular joints and on patients with rheumatoid and psoriatic arthritis indicate that the drug in question may have potential to treat arthritis, including within the temporomandibular joint.

Targeting cancer cachexia: Molecular mechanisms and clinical study

Cancer cachexia is a complex systemic catabolism syndrome characterized by muscle wasting. It affects multiple distant organs and their crosstalk with cancer constitute cancer cachexia environment. During the occurrence and progression of cancer cachexia, interactions of aberrant organs with cancer cells or other organs in a cancer cachexia environment initiate a cascade of stress reactions and destroy multiple organs including the liver, heart, pancreas, intestine, brain, bone, and spleen in metabolism, neural, and immune homeostasis. The role of involved organs turned from inhibiting tumor growth into promoting cancer cachexia in cancer progression. In this review, we depicted the complicated relationship of cancer cachexia with the metabolism, neural, and immune homeostasis imbalance in multiple organs in a cancer cachexia environment and summarized the treatment progress in recent years. And we discussed the molecular mechanism and clinical study of cancer cachexia from the perspective of multiple organs metabolic, neurological, and immunological abnormalities. Updated understanding of cancer cachexia might facilitate the exploration of biomarkers and novel therapeutic targets of cancer cachexia.

Combination Therapy of Carnosic Acid and Methotrexate Effectively Suppressed the Inflammatory Markers and Oxidative Stress in Experimental Arthritis

Background: Combination therapy with methotrexate (MTX) is the most common therapeutic strategy used for the treatment of patients with rheumatoid arthritis (RA). In this study, we combined the natural compound carnosic acid (CA) with MTX to reduce inflammation and oxidative stress in adjuvant arthritis (AA). Methods: AA was induced in 6–8 rats per group. MTX was administrated twice a week at a dose of 0.3 mg/kg b.w., while CA was administered daily at a dose of 100 mg/kg both in monotherapy and in combination with MTX. Plasma samples were collected on the 14th, 21st, and 28th day. Body weight and hind paw volume were measured once a week. Results: We found that, mainly, the CA + MTX combination significantly reduced the hind paw swelling, the levels of IL-17A, MMP-9, and MCP-1 in plasma, and GGT activity in joint homogenates. The mRNA expression of HO-1, catalase, and IL-1β in the liver were significantly improved by CA + MTX only. Our results indicate that adding CA to MTX treatment could be a good therapeutic option for patients suffering from RA. Conclusions: The addition of CA to methotrexate treatment significantly improved its efficacy in decreasing the development of AA by inhibiting the markers of inflammation and oxidative stress.

Frailty in people with rheumatoid arthritis: a systematic review of observational studies

Background: Frailty, an age-related decline in physiological reserve, is an increasingly important concept in the management of chronic diseases. The implications of frailty in people with rheumatoid arthritis are not well understood. We undertook a systematic review to assess prevalence of frailty in people with rheumatoid arthritis, and the relationship between frailty and disease activity or clinical outcomes. Methods: We searched four electronic databases (January 2001 to April 2021) for observational studies assessing the prevalence of frailty (any frailty measure) in adults (≥18 years) with rheumatoid arthritis, or analysing the relationship between frailty and disease activity or clinical outcomes (e.g. quality of life, hospitalisation or mortality) in people with rheumatoid arthritis. Study quality was assessed using an adapted Newcastle-Ottawa Scale. Screening, quality assessment and data extraction were performed independently by two reviewers. We used narrative synthesis. Results: We identified 17 analyses, from 14 different populations. 15/17 were cross-sectional. Studies used 11 different measures of frailty. Frailty prevalence ranged from 10% (frailty phenotype) to 36% (comprehensive rheumatologic assessment of frailty) in general adult populations with rheumatoid arthritis. In younger populations (<60 or <65 years) prevalence ranged from 2.4% (frailty phenotype) to 19.9% (Kihon checklist) while in older populations (>60 or >65) prevalence ranged from 31.2% (Kihon checklist) to 55% (Geriatric 8 tool). Frailty was cross-sectionally associated with higher disease activity (10/10 studies), lower physical function (7/7 studies) and longer disease duration (2/5 studies), and with hospitalization and osteoporotic fractures (1/1 study, 3.7 years follow-up). Conclusion: Frailty is common in rheumatoid arthritis, including those aged <65 years, and is associated with a range of adverse features. However, these is heterogeneity in how frailty is measured. We found few longitudinal studies making the impact of frailty on clinical outcomes over time and the extent to which frailty is caused by rheumatoid arthritis unclear.

Frailty in people with rheumatoid arthritis: a systematic review of observational studies

Background: Frailty, an age-related decline in physiological reserve, is an increasingly important concept in the management of chronic diseases. The implications of frailty in people with rheumatoid arthritis are not well understood. We undertook a systematic review to assess prevalence of frailty in people with rheumatoid arthritis, and the relationship between frailty and disease activity or clinical outcomes. Methods: We searched four electronic databases (January 2001 to April 2021) for observational studies assessing the prevalence of frailty (any frailty measure) in adults (≥18 years) with rheumatoid arthritis, or analysing the relationship between frailty and disease activity or clinical outcomes (e.g. quality of life, hospitalisation or mortality) in people with rheumatoid arthritis. Study quality was assessed using an adapted Newcastle-Ottawa Scale. Screening, quality assessment and data extraction were performed independently by two reviewers. We used narrative synthesis. Results: We identified 17 analyses, from 14 different populations. 15/17 were cross-sectional. Studies used 11 different measures of frailty. Frailty prevalence ranged from 10% (frailty phenotype) to 36% (comprehensive rheumatologic assessment of frailty) in general adult populations with rheumatoid arthritis. In younger populations (<60 or <65 years) prevalence ranged from 2.4% (frailty phenotype) to 19.9% (Kihon checklist) while in older populations (>60 or >65) prevalence ranged from 31.2% (Kihon checklist) to 55% (Geriatric 8 tool). Frailty was cross-sectionally associated with higher disease activity (10/10 studies), lower physical function (7/7 studies) and longer disease duration (2/5 studies), and with hospitalization and osteoporotic fractures (1/1 study, 3.7 years follow-up). Conclusion: Frailty is common in rheumatoid arthritis, including those aged <65 years, and is associated with a range of adverse features. However, these is heterogeneity in how frailty is measured. We found few longitudinal studies making the impact of frailty on clinical outcomes over time and the extent to which frailty is caused by rheumatoid arthritis unclear.

Time to Deal with Rheumatoid Cachexia: Prevalence, Diagnostic Criteria, Treatment Effects and Evidence for Management

Cachexia is an early result of rheumatoid arthritis (RA) (rheumatoid cachexia, RC), characterised mainly by involuntary loss of fat-free mass. RC is apparent in 1-67% of patients with RA, depending on the diagnostic criteria applied and the method used for the assessment of body composition. RC is associated with increased inflammation and disability, lower health perception, and greater mortality risk. These changes in body composition are driven by the inflammation process, the low levels of physical activity, the underlying testosterone deficiency and hypogonadism, and the pharmacotherapy required for RA. Chronic inflammation enhances resting energy expenditure as a response to stress, inducing an energy deficit, further propelling protein turnover. The use of corticosteroids and tumour necrosis factor α (TNF-α) inhibitors tend to increase fat accumulation, whereas other disease-modifying antirheumatic drugs (DMARDs) appear to induce increments in fat-free mass. The present review presents all information regarding the prevalence of RC, diagnostic criteria, and comorbidities, as well as the effects of pharmacotherapy and medical nutrition therapy on body composition of patients with RA.

Effect of Saffron Extract, Astaxanthin, and Carnosic Acid on the Levels of Matrix Metalloproteinase-9 and on Body Weight Changes in Arthritis Experiments

AIM

The aim of this study was to explore the potential effect of natural compounds and their combination with methotrexate (M) on levels of matrix metalloproteinase-9 (MMP-9) as a key biochemical parameter in rat adjuvant arthritis. Further change of body weight was selected as one of clinical parameters monitored in this animal model.

MATERIALS AND METHODS

Adjuvant arthritis (AA) was induced in Lewis rats. Methotrexate (M) was administrated twice a week in a dose of 0.3 mg/kg b.w. The saffron extract was administrated daily in two doses: 25 mg/kg b.w. (SF1) and 50 mg/kg b.w. (SF2). Both doses were administrated alone and in combination with M. Astaxanthin was administrated also daily in two doses: 1 mg/kg b.w. (AS1) and 5 mg/kg b.w. (AS2) only as monotherapy. Carnosic acid was administrated daily in one dose: 100 mg/kg (C) in monotherapy and in combination with M. All compounds and M were administrated orally. Plasma samples were collected on the 21st experimental day and used for ELISA determination. The 21st experimental day was used also for the analysis of body weight changes.

RESULTS

We observed a significant decrease of MMP-9 plasmatic levels in SF1 and SF2 monotherapy in AA animal groups. The decrease in levels of MMP-9 in combined therapy of SF1 and M had higher significance than the effect of M only in AA. The same decreasing effect on the levels of MMP-9 was observed in the combined therapy of C and M. Astaxanthin and saffron extract had a very similar effect on clinical parameters and the change in body weight: both have significantly increased body weight in monotherapy in both doses used. The combined therapy of M and saffron extract doses showed no significant difference from M itself. Carnosic acid did not affect the change of body weight, and the combination of C with M reached the same level as M alone.

CONCLUSION

Astaxanthin in monotherapy and saffron extract in monotherapy and in combined therapy with M have significantly decreased plasmatic levels of MMP-9 and increased body weight in animals suffering from AA. Lower doses were more efficient for both experiments: astaxanthin and saffron extract. Carnosic acid has no effect in monotherapy in both parameters, but a combination with M has a significant effect with respect to the improvement of cachexia as well as the inhibition of inflammation.

Therapeutic Benefit in Rheumatoid Cachexia Illustrated Using a Novel Primary Human Triple Cell Coculture Model

Background

The loss of muscle mass in rheumatoid arthritis (RA), termed rheumatoid cachexia, is predicted to result from the complex interactions between different cell types involved in the maintenance of skeletal muscle mass, namely, myoblasts, fibroblasts, and macrophages. The complexity within the muscle is further highlighted by the incidence of nonresponsiveness to current RA treatment strategies.

Method

This study aimed at determining differences in the cellular responses in a novel human primary cell triple coculture model exposed to serum collected from nonarthritic controls (NC), RA treatment naïve (RATN), and RA treatment-nonresponding (RATNR) patients. Bone morphogenetic protein-7 (BMP-7) was investigated as a treatment option.

Results

Plasma analysis indicated that samples were indeed representative of healthy and RA patients—notably, the RATNR patients additionally exhibited dysregulated IL-6/IL-10 correlations. Coculture exposure to serum from RATNR patients demonstrated increased cellular growth (p < 0.001), while both hepatocyte growth factor (p < 0.01) and follistatin (p < 0.001) were reduced when compared to NC. Furthermore, decreased concentration of markers of extracellular matrix formation, transforming growth factor-β (TGF-β; p < 0.05) and fibronectin (p < 0.001), but increased collagen IV (p < 0.01) was observed following RATNR serum exposure. Under healthy conditions, BMP-7 exhibited potentially beneficial results in reducing fibrosis-generating TGF-β (p < 0.05) and fibronectin (p < 0.05). BMP-7 further exhibited protective potential in the RA groups through reversing the aberrant tendencies observed especially in the RATNR serum-exposed group.

Conclusion

Exposure of the triple coculture to RATN and RATNR serum resulted in dysregulated myoblast proliferation and growth, and ECM impairment, which was reversed by BMP-7 treatment.

Pharmacotherapy in Cachexia: A Review of Endocrine Abnormalities and Steroid Pharmacotherapy

Cachexia is a state of increased metabolism associated with high morbidity and mortality. Dysregulation of cytokines and hormone activity causes reduced protein synthesis and excessive protein breakdown. various treatments are available, depending on the primary disease and the patient's state. Besides pharmacological treatment, crucial is nutritional support as well as increasing physical activity. The main purpose of pharmacological treatment is to diminish inflammation, improve appetite and decrease muscle wasting. Therefore a lot of medications aim at proinflammatory cytokines such as Interferon-α or Tumor Necrosis Factor-β, but because of the complicated mechanism of cachexia, the range of targets is very wide. in cachexia treatment, use of corticosteroids is common, which improve appetite, diminish inflammation, inhibit prostaglandin metabolism, Interleukin-1 activity. They can also decrease protein synthesis and increase protein degradation, which can be prevented by resveratrol. Estrogen analogs, progesterone analogs, testosterone analogs, Selective Androgen Receptor Modulators (SARM), Angiotensin-Converting-Enzyme Inhibitors (ACEI), Nonsteroidal anti-inflammatory drugs (NSAIDs), thalidomide, melatonin, Growth Hormone Releasing Peptide-2 (GHRP-2) may play important role in wasting syndrome treatment as well. However, for the usage of some of them, evidence-based recommendations are not available. This review highlights current therapeutic options for cachexia with a specific focus on steroid therapy.

Effect of biological disease-modifying antirheumatic drugs on body composition in patients with rheumatoid arthritis: a systematic review and meta-analysis

Background

Rheumatoid arthritis (RA) generates an inflammatory profile that predisposes to total and visceral fatty accumulation and reduced fat free mass (FFM). This metabolic disorder contributes to poor functionality, increased cardiovascular risk and higher mortality. This study aimed to address a systematic review with meta-analysis to determine the effect of biological and targeted synthetic disease-modifying antirheumatic drugs (bDMARDs and tsDMARDs) on body composition (BC) of patients with RA.

Methods

The search was conducted at the electronic databases PubMed, Cochrane Library, Embase, Lilacs and grey literature. This investigation was carried until July 2021. Outcomes of interest were total weight, body mass index (BMI), fat mass (FM) and FFM. A meta-analysis comparing these outcomes in RA patients under bDMARD treatment versus controls was performed.

Results

Out of 137 studies reviewed, 18 were selected: fifteen prospective cohorts, two retrospective cohorts, and one cross-sectional study. The studies comprised 1221 patients, 778 on bDMARD treatment and 443 controls, which included RA patients under conventional synthetic DMARD (csDMARD). No study addressing BC analysis in patients using tsDMARD was found. The mean age and duration of the disease was 56.7 years and 6.77 years, respectively. Ten studies demonstrated a significant increase of total weight in 88.2% of patients and 42.3% for BMI. In studies that analyzed BC by double X-ray absorptiometry (DXA), the increase in total weight and BMI correlated positively to the increase in FFM. The meta-analysis carried out in five studies showed no significant difference of the mean difference for total weight 0.12 kg (95% CI − 5.58, 5.82), BMI 0.08 kg/m2 (95% CI − 1.76, 1.92), FM − 0.08 kg (95% IC − 5.31, 5.14), and FFM − 2.08 kg (95% CI − 7.37, 3.21).

Conclusion

This systematic review suggests a possible impact of bDMARDs on BC of RA patients, even though, the meta-analysis carried out in a small part of these studies was not able to confirm significant variation in BC components.

Trial registration: PROSPERO code: CRD42020206949.

Myostatin Levels and the Risk of Myopenia and Rheumatoid Cachexia in Women with Rheumatoid Arthritis

Background

Myostatin is a regulator of muscle size. To date, there have been no published studies focusing on the relation between myostin levels and myopenia in rheumatoid arthritis (RA).

Objective

Evaluate the value of serum myostatin as a biomarker of cachexia and low skeletal muscle mass (LSMM) in RA patients, along with whether high serum myostatin is associated to these conditions after adjusting for potential confounders.

Methods

This cross-sectional study included 161 female RA patients and 72 female controls. In the RA group, we assessed several potential risk factors for LSMM and rheumatoid cachexia. Dual-energy X-ray absorptiometry was used to quantify the skeletal muscle mass index (SMMI) (considering LSMM ≤ 5.5 kg/m²) and the presence of rheumatoid cachexia (a fat-free mass index ≤ 10 percentile and fat mass index ≥ 25 percentile of the reference population). Serum myostatin concentrations were determined by ELISA. To identify a cut-off for high serum myostatin levels, we performed ROC curve analysis. Multivariable logistic regression analysis was used to identify the risk factors for LSMM and rheumatoid cachexia. The risk was expressed as odds ratios (ORs) and their 95% confidence intervals (95% CIs).

Results

Compared to the controls, the RA group had a higher proportion of LSMM and exhibited high serum myostatin levels (p < 0.001). ROC curve analysis showed that a myostatin level ≥ 17 ng/mL was the most efficient cut-off for identifying rheumatoid cachexia (sensitivity: 53%, specificity: 71%) and LSMM (sensitivity: 43%, specificity: 77%). In the multivariable logistic regression, RA with high myostatin levels (≥17 ng/mL) was found to increase the risk of cachexia (OR = 2.79, 95% CI: 1.24-6.29; p = 0.01) and LSMM (OR = 3.04, 95% CI: 1.17-7.89; p = 0.02).

Conclusions

High serum myostatin levels increase the risk of LSMM and rheumatoid cachexia. We propose that high myostatin levels are useful biomarkers for the identification of patients in risk of rheumatoid cachexia and myopenia.

A Review of Metabolomic Profiling in Rheumatoid Arthritis: Bringing New Insights in Disease Pathogenesis, Treatment and Comorbidities

Metabolomic analysis provides a wealth of information that can be predictive of distinctive phenotypes of pathogenic processes and has been applied to better understand disease development. Rheumatoid arthritis (RA) is an autoimmune disease with the establishment of chronic synovial inflammation that affects joints and peripheral tissues such as skeletal muscle and bone. There is a lack of useful disease biomarkers to track disease activity, drug response and follow-up in RA. In this review, we describe potential metabolic biomarkers that might be helpful in the study of RA pathogenesis, drug response and risk of comorbidities. TMAO (choline and trimethylamine oxide) and TCA (tricarboxylic acid) cycle products have been suggested to modulate metabolic profiles during the early stages of RA and are present systemically, which is a relevant characteristic for biomarkers. Moreover, the analysis of lipids such as cholesterol, FFAs and PUFAs may provide important information before disease onset to predict disease activity and treatment response. Regarding therapeutics, TNF inhibitors may increase the levels of tryptophan, valine, lysine, creatinine and alanine, whereas JAK/STAT inhibitors may modulate exclusively fatty acids. These observations indicate that different disease modifying antirheumatic drugs have specific metabolic profiles and can reveal differences between responders and non-responders. In terms of comorbidities, physical impairment represented by higher fatigue scores and muscle wasting has been associated with an increase in urea cycle, FFAs, tocopherols and BCAAs. In conclusion, synovial fluid, blood and urine samples from RA patients seem to provide critical information about the metabolic profile related to drug response, disease activity and comorbidities.

Long-term weight changes and risk of rheumatoid arthritis among women in a prospective cohort: a marginal structural model approach

OBJECTIVE

To examine the association of long-term weight change with RA risk in a large prospective cohort study.

METHODS

The Nurses' Health Study II started in 1989 (baseline); after exclusions, we studied 108 505 women 25-42 years old without RA. Incident RA was reported by participants and confirmed by medical record review. Body weight was reported biennially through 2015. We investigated two time-varying exposures: weight changes from baseline and from age 18; change was divided into five categories. We used a marginal structural model approach to account for time-varying weight change and covariates.

RESULTS

Over 2 583 266 person-years, with a median follow-up time of 25.3 years, 541 women developed RA. Compared with women with stable weight from baseline, weight change was significantly associated with increased RA risk [weight gain 2-<10 kg: RR = 1.98 (95% CI 1.38, 2.85); 10-<20 kg: RR = 3.28 (95% CI 2.20, 4.89); ≥20 kg: RR = 3.81 (95% CI 2.39, 6.07); and weight loss >2 kg: RR = 2.05 (95% CI 1.28, 3.28)]. Weight gain of 10 kg or more from age 18 compared with stable weight was also associated with increased RA risk [10-< 20 kg: RR = 2.12 (95% CI 1.37, 3.27), ≥20 kg: RR = 2.31 (95% CI 1.50, 3.56)]. Consistent findings were observed for seropositive and seronegative RA.

CONCLUSION

Long-term weight gain was strongly associated with increased RA risk in women, with weight gain of ≥20 kg associated with more than a three-fold increased RA risk. Maintenance of healthy weight may be a strategy to prevent or delay RA.

Challenges in the management of older patients with inflammatory rheumatic diseases

The rise in the number of people aged 65 years and older living with inflammatory rheumatic diseases such as rheumatoid arthritis is causing considerable challenges for clinicians. As patients get older, they are at an increased risk of multiple chronic diseases, a situation termed multimorbidity. Multimorbidity inevitably drives polypharmacy, where by a patient requires treatment with multiple medications. In addition, advancing age, multimorbidity and polypharmacy all place a patient at an increased risk of developing geriatric syndromes, which are clinical conditions in older people that do not fit into disease categories and include malnutrition, sarcopenia and frailty. Geriatric syndromes further increase the risk of adverse outcomes, including the accrual of additional morbidity, nursing home admission and mortality. Patients with inflammatory rheumatic diseases are especially prone to developing geriatric syndromes. Some predisposing risk factors for geriatric syndromes, such as joint swelling and functional limitations, are also inherent to rheumatic inflammatory disease itself. The frequent coexistence of multimorbidity, polypharmacy and geriatric syndromes in this patient group requires individually tailored interventions to preserve patient independence and overall functioning. To prepare for the changing demography, rheumatologists should gain more insight into the implications of multimorbidity, polypharmacy and geriatric syndromes for the management of older patients with inflammatory rheumatic diseases.

Improvements in Body Composition after a Proposed Anti-Inflammatory Diet Are Modified by Employment Status in Weight-Stable Patients with Rheumatoid Arthritis, a Randomized Controlled Crossover Trial

Rheumatoid Arthritis (RA) is an autoimmune disease affecting peripheral joints. Chronic activation of inflammatory pathways results in decreased function and the development of comorbidities, such as loss of lean mass while retaining total body mass. The objective of this report was to assess whether dietary manipulation affects body composition in patients with RA as a secondary outcome. Fifty patients were included in a randomized controlled crossover trial testing a proposed anti-inflammatory Mediterranean-style diet compared to a Western diet. Body composition was measured by bioelectrical impedance spectroscopy in patients without implants (n = 45). Regardless of treatment, fat-free mass increased and fat mass percentage decreased during weight stability, but no differences between intervention and control in the whole group (n = 42, all p > 0.20) were found. Interaction analysis revealed that participants who were non-employed (n = 15) significantly decreased in fat mass (−1.767 kg; 95% CI: −3.060, −0.475, p = 0.012) and fat mass percentage (−1.805%; 95% CI: −3.024, −0.586, p = 0.008) from the intervention compared to the control period. A Mediterranean-style diet improved body composition in non-employed participants (n = 15). The group as a whole improved regardless of dietary allocation, indicating a potential to treat rheumatoid cachexia by dietary manipulation.

Physical exercise at the crossroad between muscle wasting and the immune system: implications for lung cancer cachexia

Cachexia is a syndrome characterized by involuntary weight loss and wasting of skeletal muscle mass. It is associated with worse overall survival and quality of life. The cancer-induced systemic inflammation and the consequent host derived catabolic stimuli, trigger cachexia by inhibiting muscle protein synthesis and enhancing muscle catabolism. The muscle itself may further promote chronic inflammation, introducing a vicious catabolic circle. Nutritional support alone plays a limited role in the treatment of cancer cachexia and should be combined with other interventions. Physical exercise lowers systemic inflammation and promotes muscle anabolism. It also attenuates the age-related physical decline in elderly and it might counteract the muscle wasting induced by the cancer cachexia syndrome. This review describes how cancer-induced systemic inflammation promotes muscle wasting and whether physical exercise may represent a suitable treatment for cancer-induced cachexia, particularly in patients with non-small cell lung cancer. We summarized pre-clinical and clinical studies investigating whether physical exercise would improve muscle performance and whether this improvement would translate in a clinically meaningful benefit for patients with cancer, in terms of survival and quality of life. Moreover, this review describes the results of studies investigating the interplay between physical exercise and the immune system, including the role of the intestinal microbiota.

Interaction effect of systemic inflammation and modifiable rheumatoid cachexia risk factors on resting energy expenditure in patients with rheumatoid arthritis

Background

In rheumatoid cachexia (RC), high resting energy expenditure (REE) is associated with loss of muscle mass driven by proinflammatory cytokines. The objectives of this study were to investigate parameters associated with RC, and the interaction between systemic inflammation and modifiable risk factors for RC on REE.

Methods

Thirty-five rheumatoid arthritis (RA) and nineteen non-RA controls comparable in age, sex, race and BMI underwent measures of REE by indirect calorimetry. Clinical, dietary, body composition and physical function data were collected. Homeostasis model assessment for insulin resistance (HOMA-IR) and serum interleukin-6 (IL-6) were used as parameters of IR and systemic inflammation, respectively. Regression models tested association between REE and dependent variables, including pre-specified interaction tests involving HOMA-IR and IL-6 and dietary intake of protein per weight (PPW) and IL-6.

Results

RA subjects were mostly women (94%) and had a median age of 54 years (50.5, 70) and BMI of 30.5 kg/m2 (26.1, 36.9). We observed a significant interaction effect between PPW and serum IL-6 on REE among RA subjects in the multiple regression model among RA. The upper tertile of PPW demonstrated a significant negative correlation between REE and IL-6 (β=-19.97, 95% CI [-35.41, -4.54], p=0.01). The lower tertile of PPW demonstrated a significant positive correlation between REE and IL-6 (β=42.24, 95% CI [4.25, 80.23], p=0.03).

Conclusions

While IR can lead to muscle catabolism, IR was not significantly associated with REE in RA individuals. Higher dietary protein intake could attenuate the effect of systemic inflammation on REE in RA patients.

Skeletal muscle wasting: the estrogen side of sexual dimorphism

The importance of defining sex differences across various biological and physiological mechanisms is more pervasive now than it has been over the past 15-20 years. As the muscle biology field pushes to identify small molecules and interventions to prevent, attenuate, or even reverse muscle wasting, we must consider the effect of sex as a biological variable. It should not be assumed that a therapeutic will affect males and females with equal efficacy or equivalent target affinities under conditions where muscle wasting is observed. With that said, it is not surprising to find that we have an unclear or even a poor understanding of the effects of sex or sex hormones on muscle wasting conditions. Although recent investigations are beginning to establish experimental approaches that will allow investigators to assess the impact of sex-specific hormones on muscle wasting, the field still needs rigorous scientific tools that will allow the community to address critical hypotheses centered around sex hormones. The focus of this review is on female sex hormones, specifically estrogens, and the roles that these hormones and their receptors play in skeletal muscle wasting conditions. With the overall review goal of assembling the current knowledge in the area of sexual dimorphism driven by estrogens with an effort to provide insights to interested physiologists on necessary considerations when trying to assess models for potential sex differences in cellular and molecular mechanisms of muscle wasting.

Assessment of Intramuscular Fat and Correlation with Body Composition in Patients with Rheumatoid Arthritis and Spondyloarthritis: A Pilot Study

Rheumatoid arthritis (RA) and spondyloarthritis (SpA) are associated with changes in body composition. Ectopic intramuscular fat (IMAT) may alter muscle function and contribute to cardiometabolic disorders. In a pilot study, we analyzed IMAT in the calf with peripheral quantitative computed tomography (pQCT) and examined correlations between IMAT quantity and body composition parameters. In 20 patients with active RA and 23 with active SpA, IMAT was correlated with visceral fat (VAT; r = 0.5143 and 0.6314, respectively; p < 0.05) and total lean mass (r = 0.5414 and 0.8132, respectively; p < 0.05), but not with whole body fat mass. Total lean mass mediated 16% and 33% of the effects of VAT on IMAT in RA and SpA, respectively. In both RA and SpA, calf muscle area was correlated with total lean mass (r = 0.5940 and r = 0.8597, respectively; p < 0.05) and fat area was correlated with total body fat (r = 0.6767 and 0.5089, respectively; p < 0.05) and subcutaneous fat (r = 0.6526 and 0.5524, respectively; p < 0.05). Fat area was inversely correlated with handgrip and walking tests, and it was associated with disease activity and disability. We showed that ectopic IMAT, measured with pQCT, was correlated with VAT, but not with total body fat, in RA and SpA. This result suggests that metabolically active fat was specifically associated with IMAT.

Albumin/Globulin Ratio as Yin-Yang in Rheumatoid Arthritis and Its Correlation to Inflamm-Aging Cytokines

Purpose

Inflamm-aging is a novel-concept in rheumatoid arthritis (RA) with accelerating aging process. We try to find a correlation between serum albumin/globulin (A/G) ratio and clinical biochemical parameters, incidence of aging-related diseases (ARDs) as well as inflammaging-related molecules.

Patients and Methods

Healthy controls (HC) and RA patients were compared with their clinical biochemical parameters including albumin and globulin levels, A/G ratio, and levels of serum lipids. Incidence of ARDs in RA was compared with A/G ratio, having a cut off value of 1.2. Expression levels of leptin and Trf2 genes in PBMCs, and inflammatory factors like IL-1β, IL-6, IL-8 and TNF-ɑ between HC and RA patients were compared, and correlated with the A/G ratio.

Results

Compared to HC, RA patients had decreased levels of albumin, while globulin levels were found to be increased, which led to a significantly lower A/G ratio in RA patients. A/G ratio rather than ESR and CRP had significant correlation with dyslipidemia in RA patients. Patients with A/G <1.2 had a higher risk of ARDs than patients with A/G >1.2. The RR was 2.48 (95% CI: 1.79 to 3.64, p <0.0001). In addition, A/G ratio has positively correlated to leptin and Trf2 expression, while an inverse correlation was observed with the levels of inflamm-aging related cytokines like IL-6, IL-8 and TNF-ɑ.

Conclusion

A decreased A/G ratio in RA patients has significantly correlated with dyslipidemia and ARDs, as well as inflammaging- related adipokine and pro-inflammatory cytokines. Thus, A/G ratio could be a reliable marker for evaluating the inflammaging process during clinical management in ARDs.

Unresolved intramuscular inflammation, not diminished skeletal muscle regenerative capacity, is at the root of rheumatoid cachexia: insights from a rat CIA model

Rheumatoid arthritis targets numerous organs in patients, including the skeletal muscle, resulting in rheumatoid cachexia. In the muscle niche, satellite cells, macrophages, and myofibroblasts may be affected and the factors they release altered. This study aimed to assess these cell types, cytokines, and growth factors and their relationships to muscle fiber size and number in a rodent collagen-induced arthritis (CIA) model, in order to identify new therapeutic targets. Fiber cross-sectional area (CSA) was 57% lower in CIA than controls (p < 0.0001), thus smaller but more fibers visible per field of view. Immunostaining indicated the increased presence of satellite cells, macrophages, myofibroblasts, and myonuclei per field of view in CIA (p < 0.01), but this finding was not maintained when taking fiber number into consideration. Western blots of gastrocnemius samples indicated that tumor necrosis factor-α was significantly elevated (p < 0.01) while interleukin-10 (IL-10) was decreased (p < 0.05) in CIA. This effect was maintained (and heightened for IL-10) when expressed per fiber number. Myogenic regulatory factors (MyoD and myogenin), transforming growth factor-β and inhibitor of differentiation were significantly elevated in CIA muscle and levels correlated significantly with CSA. Several of these factors remained elevated, but bone morphogenetic protein-7 decreased when considering fiber number per area. In conclusion, CIA-muscle demonstrated a good regenerative response. Myoblast numbers per fiber were not elevated, suggesting their activity results from the persistent inflammatory signaling which also significantly hampered maintenance of muscle fiber size. A clearer picture of signaling events at cellular level in arthritis muscle may be derived from expressing data per fiber.

Sustained microglial activation in the area postrema of collagen-induced arthritis mice

Background

Central nervous system (CNS)-mediated symptoms, such as fatigue, depression, and hyperalgesia, are common complications among patients with rheumatoid arthritis (RA). However, it remains unclear how the peripheral pathology of RA spreads to the brain. Accumulated evidence showing an association between serum cytokine levels and aberrant CNS function suggests that humoral factors participate in this mechanism. In contrast to the well-known early responses of microglia (CNS-resident immune cells) in the area postrema [AP; a brain region lacking a blood–brain barrier (BBB)] to experimental inflammation, microglial alterations in the AP during chronic inflammation like RA remain unclear. Therefore, to determine whether microglia in the AP can react to persistent autoimmune-arthritis conditions, we analyzed these cells in a mouse model of collagen-induced arthritis (CIA).

Methods

Microglial number and morphology were analyzed in the AP of CIA and control mice (administered Freund’s adjuvant or saline). Immunostaining for ionized calcium-binding adaptor molecule-1 was performed at various disease phases: “pre-onset” [post-immunization day (PID) 21], “establishment” (PID 35), and “chronic” (PID 56 and 84). Quantitative analyses of microglial number and morphology were performed, with principal component analysis used to classify microglia. Interleukin-1β (IL-1β) mRNA expression was analyzed by multiple fluorescent in situ hybridization and real-time polymerase chain reaction. Behavioral changes were assessed by sucrose preference test.

Results

Microglia in the AP significantly increased in density and exhibited changes in morphology during the establishment and chronic phases, but not the pre-onset phase. Non-subjective clustering classification of cell morphology (CIA, 1,256 cells; saline, 852 cells) showed that the proportion of highly activated microglia increased in the CIA group during establishment and chronic phases. Moreover, the density of IL-1β-positive microglia, a hallmark of functional activation, was increased in the AP. Sucrose preferences in CIA mice negatively correlated with IL-1β expression in brain regions containing the AP.

Conclusions

Our findings demonstrate that microglia in the AP can sustain their activated state during persistent autoimmune arthritis, which suggests that chronic inflammation, such as RA, may affect microglia in brain regions lacking a BBB and have various neural consequences.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02657-x.

Frequent injections of high-dose human umbilical cord mesenchymal stem cells slightly aggravate arthritis and skeletal muscle cachexia in collagen-induced arthritic mice

A single injection of low-dose human umbilical cord-derived mesenchymal stem cells (UC-MSCs) has been previously demonstrated to relieve synovitis and bone erosion in animal models of arthritis, but whether frequent injections of high-dose UC-MSCs relieve arthritis and inhibit loss of muscle mass has remained elusive. In the present study, DBA/1 mice were randomly divided into three groups: Normal (wild-type mice; n=11), collagen-induced arthritis (CIA; n=12) and CIA treated with UC-MSCs (n=11; 5x10⁶ UC-MSCs per week for 3 weeks). Arthritis and skeletal muscle cachexia were evaluated until the end of the experiment on day 84. It was indicated that both the CIA and UC-MSC groups had lower body weights compared with the normal mice. Clinical arthritis scores, hind ankle diameters, synovitis and bone erosion progressively increased and were similar between the CIA and UC-MSC groups. Although there was no difference in food intake among the three groups, the normalized food intake of normal group was significantly higher than CIA group and UC-MSC group from day 42 onwards; there was no significance on day 77 but this could be neglected. Furthermore, gastrocnemius muscle weight in the UC-MSC group was significantly reduced compared with that in the CIA and normal groups. The UC-MSC group had higher levels of proinflammatory cytokines, such as TNF-α, IL-6 and IL-1β than those in the CIA group. However, the other cytokines assessed and the fibrosis indices in the CIA and UC-MSC groups were not different from those in the control group and there was no inflammatory cell infiltration. Thus, frequent injections of high-dose UC-MSCs slightly aggravated synovitis and muscle cachexia in the murine CIA model and should therefore be avoided in the treatment of arthritis.

Sarcopenic Obesity in Rheumatoid Arthritis: Prevalence and Impact on Physical Functioning

OBJECTIVE

We determined the prevalence of sarcopenic obesity in patients with rheumatoid arthritis (RA) using multiple methods and assessed associations with physical functioning.

METHODS

This study evaluated data from three RA cohorts. Whole-body dual-energy absorptiometry (DXA) measures of appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI) were converted to age, sex, and race-specific Z-Scores and categorized using a recently validated method and compared it to a widely-used existing method. The prevalence of body composition abnormalities in RA was compared with two reference populations. In the RA cohorts, associations between body composition and change in the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB) in follow-up were assessed using linear and logistic regression, adjusting for age, sex, race, and study.

RESULTS

The prevalence of low lean mass and sarcopenic obesity were higher in patients with RA (14.2; 12.6%, respectively) compared with the reference population cohorts (7-10%; 4-4.5%, respectively, all p< 0.05). There was only moderate agreement among methods of sarcopenic obesity categorization (Kappa 0.45). The recently validated method categorized fewer subjects as obese, and many of these were categorized as low lean mass only. Low lean mass, obesity, and sarcopenic obesity were each associated with higher HAQ and lower SPPB at baseline and numerically greater worsening.

CONCLUSION

RA patients had higher rates of low lean mass and sarcopenic obesity than the general population. The recently validated methods characterized body composition changes differently from traditional methods and were more strongly associated with physical function.

Lifestyle factors in patients with rheumatoid arthritis-a cross-sectional study on two Scandinavian cohorts

INTRODUCTION

The risk for cardiovascular diseases and other comorbidities increases with the number of unhealthy lifestyle factors in the general population. However, information on the combined number of unhealthy lifestyle factors in people with rheumatoid arthritis (RA) is scarce.

OBJECTIVES

To study lifestyle factors and the association between disease impact and two or more unhealthy lifestyle factors in two Scandinavian cohorts with RA.

METHODS

We analysed data from two cohorts, Danish (n = 566; mean age 61.82 (SD 11.13) years; 72% women) and Swedish (n = 955; mean age 66.38 (SD 12.90) years; 73% women). Lifestyle factors (tobacco use, BMI, alcohol consumption and physical activity) were dichotomised as healthy vs. unhealthy (range 0-4 unhealthy factors). The association between disease impact and two or more unhealthy lifestyle factors was analysed using logistic regression.

RESULTS

Sixty-six percent of Danish and 47% of Swedish respondents reported two or more unhealthy lifestyle factors, most commonly, being overweight/obese and physical inactivity. For Danish participants, two or more unhealthy lifestyle factors were associated with (OR and 95% CI) male gender (1.86; 1.21-2.85), cardiovascular diseases (1.90; 1.28-2.82) and disease duration (0.97; 0.95-0.99). Corresponding findings for the Swedish cohort were male gender (1.42; 1.07-1.89), pain (1.10; 1.04-1.15), fatigue (1.09; 1.04-1.15), physical functioning (1.64; 1.28-2.10) and quality of life (0.35; 0.20-0.60).

CONCLUSION

Many patients, most often male, in both cohorts had two or more unhealthy lifestyle factors. The number of unhealthy lifestyle factors indicates a multifaceted relationship with disease impact.

Linalyl acetate as a potential preventive agent against muscle wasting in rheumatoid arthritis rats chronically exposed to nicotine

Cigarette smoking has detrimental effects on rheumatoid arthritis (RA), characterized by muscle wasting. Linalyl acetate (LA), the main component of Lavandula angustifolia Mill (lavender) oil, has anti-inflammatory properties. We investigated the detrimental effects of chronic nicotine exposure in rats with RA, as well as the abilities of lavender oil and LA to prevent muscle wasting. Rats with RA induced by type II collagen were exposed to nicotine for 22 days from day 1. Lavender oil or LA was administered twice a week during the experiment. Compared with control, collagen-induced arthritis (CIA) and chronic nicotine exposure plus CIA (NicoCIA) showed increases in hind paw thickness and serum interleukin (IL)-6 and decreases in body weight and serum insulin-like growth factor (IGF)-1 levels. Moreover, weight and fiber cross-sectional area of the gastrocnemius muscle were much lower, and mitochondrial membrane potential of the gastrocnemius muscle was higher, in the NicoCIA than in the CIA. These alterations in the NicoCIA were prevented by lavender oil and LA. Importantly, LA showed greater activity than lavender oil in preventing IGF-1 reduction in the NicoCIA. These findings suggest that lavender oil and LA may have preventive benefit in RA by counteracting muscle wasting associated with chronic nicotine exposure.

Adiposity Is Related to Inflammatory Disease Activity in Juvenile Idiopathic Arthritis

OBJECTIVE

To identify factors associated with the higher proportion of fatty tissue and overweight/obesity observed in patients with juvenile idiopathic arthritis (JIA).

PATIENTS AND METHODS

We performed a cross-sectional study of 80 JIA patients aged 4-15 years with 80 age- and sex-matched healthy controls. Body composition was assessed using dual-energy x-ray absorptiometry. The 27-joint Juvenile Arthritis Disease Activity score (JADAS27) was calculated. Two multivariate models were constructed to identify factors associated with overweight/obesity and fat mass index (FMI).

RESULTS

No differences were found between cases and controls in body mass index (BMI) or body composition. However, compared with controls, patients with a high inflammatory activity (JADAS27 > 4.2 for oligoarticular JIA or >8.5 for polyarticular disease) had higher values for BMI (p = 0.006); total fat mass (p = 0.003); FMI (p = 0.001); and fat in the legs (p = 0.001), trunk (p = 0.001), and arms (p = 0.002). The factors associated with overweight/obesity in patients were the duration of therapy with biological drugs, measured in months (OR [95% CI] = 1.12 [1.02-1.04]; p = 0.037), and physical activity (OR [95% CI] = 0.214 [0.07-0.68]; p = 0.010), while the factors associated with FMI were age (β [95% CI] = 0.30 [0.17-1.41]; p = 0.014), JADAS27 (β [95% CI] = 0.45 [0.16-1.08]; p = 0.009), and physical activity (β [95% CI] = -0.22 [-5.76 to 0.29]; p = 0.031).

CONCLUSION

Our study revealed no differences between JIA patients with well-controlled disease and low disability and the healthy population in BMI or body composition. Furthermore, the association observed between inflammatory activity and adiposity could be responsible for poorer clinical course.

Metabolomic Biomarker Candidates for Skeletal Muscle Loss in the Collagen-Induced Arthritis (CIA) Model

There is no consensus for diagnosis or treatment of RA muscle loss. We aimed to investigate metabolites in arthritic mice urine as biomarkers of muscle loss. DBA1/J mice comprised collagen-induced arthritis (CIA) and control (CO) groups. Urine samples were collected at 0, 18, 35, 45, 55, and 65 days of disease and subjected to nuclear magnetic resonance spectroscopy. Metabolites were identified using Chenomx and Birmingham Metabolite libraries. The statistical model used principal component analysis, partial least-squares discriminant analysis, and partial least-squares regression analysis. Linear regression and Fisher's exact test via the MetaboAnalyst website were performed (VIP-score). Nearly 100 identified metabolites had CIA vs. CO and disease time-dependent differences (p < 0.05). Twenty-eight metabolites were muscle-associated: carnosine (VIPs 2.8 × 10²) and succinyl acetone (VIPs 1.0 × 10) showed high importance in CIA vs. CO models at day 65; CIA pair analysis showed histidine (VIPs 1.2 × 10²) days 55 vs. 65, histamine (VIPs 1.1 × 10²) days 55 vs. 65, and L-methionine (VIPs 1.1 × 10²) days 0 vs. 18. Carnosine was fatigue- (0.039) related, creatine was food intake- (-0.177) and body weight- (-0.039) related, and both metabolites were clinical score- (0.093; 0.050) and paw edema- (0.125; 0.026) related. Therefore, muscle metabolic alterations were detected in arthritic mice urine, enabling further validation in RA patient's urine, targeting prognosis, diagnosis, and monitoring of RA-mediated muscle loss.

Metabolomic Biomarker Candidates for Skeletal Muscle Loss in the Collagen-Induced Arthritis (CIA) Model

There is no consensus for diagnosis or treatment of RA muscle loss. We aimed to investigate metabolites in arthritic mice urine as biomarkers of muscle loss. DBA1/J mice comprised collagen-induced arthritis (CIA) and control (CO) groups. Urine samples were collected at 0, 18, 35, 45, 55, and 65 days of disease and subjected to nuclear magnetic resonance spectroscopy. Metabolites were identified using Chenomx and Birmingham Metabolite libraries. The statistical model used principal component analysis, partial least-squares discriminant analysis, and partial least-squares regression analysis. Linear regression and Fisher’s exact test via the MetaboAnalyst website were performed (VIP-score). Nearly 100 identified metabolites had CIA vs. CO and disease time-dependent differences (p < 0.05). Twenty-eight metabolites were muscle-associated: carnosine (VIPs 2.8 × 102) and succinyl acetone (VIPs 1.0 × 10) showed high importance in CIA vs. CO models at day 65; CIA pair analysis showed histidine (VIPs 1.2 × 102) days 55 vs. 65, histamine (VIPs 1.1 × 102) days 55 vs. 65, and L-methionine (VIPs 1.1 × 102) days 0 vs. 18. Carnosine was fatigue- (0.039) related, creatine was food intake- (−0.177) and body weight- (−0.039) related, and both metabolites were clinical score- (0.093; 0.050) and paw edema- (0.125; 0.026) related. Therefore, muscle metabolic alterations were detected in arthritic mice urine, enabling further validation in RA patient’s urine, targeting prognosis, diagnosis, and monitoring of RA-mediated muscle loss.

Activation of hypothalamic AMPK ameliorates metabolic complications of experimental arthritis

OBJECTIVE

To investigate whether thermogenesis and the hypothalamus may be involved in the physiopathology of experimental arthritis (EA).

METHODS

EA was induced in Lewis male rats by intradermal injection of Freund's complete adjuvant (FCA). Food intake, body weight, plasma cytokines, thermographic analysis, gene and protein expression of thermogenic markers in brown (BAT) and white (WAT) adipose tissue and hypothalamic AMP-activated protein kinase (AMPK) were analyzed. Virogenetic activation of hypothalamic AMPK was performed.

RESULTS

We first demonstrate that EA is associated with increased BAT thermogenesis and browning of subcutaneous WAT (sWAT) leading to elevated energy expenditure. Moreover, rats suffering EA show inhibition of hypothalamic AMPK, a canonical energy sensor modulating energy homeostasis at central level. Notably, specific genetic activation of AMPK in the ventromedial nucleus of the hypothalamus (VMH; a key site modulating energy metabolism) reverses the effect of EA on energy balance, brown fat and browning, as well as promoting an amelioration of the inflammatory status.

CONCLUSION

Overall, these data indicate that EA promotes a central catabolic state that can be targeted and reversed by the activation of hypothalamic AMPK. This might open new therapeutic alternatives to treat rheumatoid arthritis (RA)-associated metabolic comorbidities, improving RA-patients overall prognosis.