Skeletal muscle properties in rheumatoid arthritis patients

Nano-platform Strategies of Herbal Components for the Management of Rheumatoid Arthritis: A Review on the Battle for Next-Generation Formulations

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that initially affects small joints and then spreads to the bigger joints. It also affects other organs of the body such as lungs, eyes, kidneys, heart, and skin. In RA, there is destruction of cartilage and joints, and ligaments and tendons become brittle. Damage to the joints leads to abnormalities and bone degradation, which may be quite painful for the patient.

METHOD

The nano-carriers such as liposomes, phytosomes, nanoparticles, microcapsules, and niosomes are developed to deliver the encapsulated phytoconstituents to targeted sites for the better management of RA.

RESULTS

The phytoconstituents loaded nano-carriers have been used in order to increase bioavailability, stability and reduce the dose of an active compound. In one study, the curcumin-loaded phytosomes increase the bioavailability of curcumin and also provides relief from RA symptoms. The drug-loaded nano-carriers are the better option for the management of RA.

CONCLUSION

In conclusion, there are many anti-arthritic herbal and synthetic medicine available in the market that are currently used in the treatment of RA. However, chronic use of these medications may result in a variety of side effects. Because therapy for RA is frequently necessary for the rest of ones life. The use of natural products may be a better option for RA management. These phytoconstituents, however, have several disadvantages, including limited bioavailability, low stability, and the need for a greater dosage. These problems can be rectified by using nano-technology.

Ultrasound and magnetic resonance imaging as diagnostic tools for sarcopenia in immune-mediated rheumatic diseases (IMRDs)

Sarcopenia is characterized by loss of muscle mass, altered muscle composition, fat and fibrous tissue infiltration, and abnormal innervation, especially in older individuals with immune-mediated rheumatic diseases (IMRDs). Several techniques for measuring muscle mass, strength, and performance have emerged in recent decades. The portable dynamometer and gait speed represent the most frequently used tools for the evaluation of muscle strength and physical efficiency, respectively. Aside from dual-energy, X-ray, absorptiometry, and bioelectrical impedance analysis, ultrasound (US) and magnetic resonance imaging (MRI) techniques appear to have a potential role in evaluating muscle mass and composition. US and MRI have been shown to accurately identify sarcopenic biomarkers such as inflammation (edema), fatty infiltration (myosteatosis), alterations in muscle fibers, and muscular atrophy in patients with IMRDs. US is a low-cost, easy-to-use, and safe imaging method for assessing muscle mass, quality, architecture, and biomechanical function. This review summarizes the evidence for using US and MRI to assess sarcopenia.

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.

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.

Morphological Parameters in Quadriceps Muscle Were Associated with Clinical Features and Muscle Strength of Women with Rheumatoid Arthritis: A Cross-Sectional Study

Background: Rheumatoid arthritis (RA) is an autoimmune, inflammatory and chronic disease that may lead to loss of muscle mass, muscle strength and decreased functionality. Our objectives are to assess the quadriceps muscle morphology by ultrasound (MU) and verify its associations with clinical features, muscle strength and physical function in RA patients. Methods: In this cross-sectional study, RA women (≥18 years) were included. Morphological parameters in quadriceps muscle consisted of the muscle thickness and pennation angle of rectus femoris (RF), vastus intermedius (VI) and vastus lateralis (VL). RA activity was measured by a 28-joint disease activity score (DAS28), muscle strength by handgrip and chair stand tests, and physical function by health assessment questionnaire (HAQ), timed-up-and-go (TUG) test and short physical performance battery (SPPB). Results: Fifty-five patients were included (age: 56.73 ± 9.46 years; DAS28: 3.08 ± 1.29). Muscle thickness in RF, VI and VL were negatively associated with age (RF, p < 0.001; VI, p = 0.013; VL, p = 0.002) and disease duration (RF, p < 0.001; VI, p = 0.005; VL, p = 0.001), and were positively associated with handgrip strength (RF, p = 0.015; VI, p = 0.022; VL, p = 0.013). In addition, decreased muscle thickness in VI (p = 0.035) and a smaller pennation angle in RF (p = 0.030) were associated with higher DAS-28 scores. Conclusion: Quadriceps muscle morphology by ultrasound appears to be affected by age, disease duration, disease activity and muscle strength in patients with RA. MU can be a useful method to evaluate the impact of the disease on skeletal muscle.

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.

Rheumatoid cachexia: the underappreciated role of myoblast, macrophage and fibroblast interplay in the skeletal muscle niche

Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexia, which occurs in up to a third of patients, is relatively neglected as research focus, despite its significant contribution to decreased quality of life in patients. A better understanding of the cellular and molecular processes involved in rheumatoid cachexia, as well as its potential treatment, is dependent on elucidation of the intricate interactions of the cells involved, such as myoblasts, fibroblasts and macrophages. Persistent RA-associated inflammation results in a relative depletion of the capacity for regeneration and repair in the satellite cell niche. The repair that does proceed is suboptimal due to dysregulated communication from the other cellular role players in this multi-cellular environment. This includes the incomplete switch in macrophage phenotype resulting in a lingering pro-inflammatory state within the tissues, as well as fibroblast-associated dysregulation of the dynamic control of the extracellular matrix. Additional to this endogenous dysregulation, some treatment strategies for RA may exacerbate muscle wasting and no multi-cell investigation has been done in this context. This review summarizes the most recent literature characterising clinical RA cachexia and links these features to the roles of and complex communication between multiple cellular contributors in the muscle niche, highlighting the importance of a targeted approach to therapeutic intervention.

Quadriceps muscle properties in rheumatoid arthritis: insights about muscle morphology, activation and functional capacity

BACKGROUND

Rheumatoid arthritis (RA) is an inflammatory and chronic autoimmune disease that leads to muscle mass loss and functional capacity impairment, potentiated by physical inactivity. Despite evidences demonstrate neuromuscular impairments in RA patients, aging effects may have masked the results of similar previous studies. The aim of study was to verify (i) the effects of RA on functional capacity and muscle properties in middle-aged patients and (ii) the association between age, clinical characteristics, quadriceps muscle properties and functional capacity.

METHODS

Thirty-five RA women and 35 healthy age-matched women were compared with the following outcomes: (i) physical activity level through the International Physical Activity Questionnaire (IPAQ); (ii) timed-up and go (TUG) test; (iii) isometric knee extensor muscular strength; and (iv) vastus lateralis muscle activation and muscle architecture (muscle thickness, pennation angle and fascicle length) during an isometric test. An independent Student t-test and partial correlation (controlled by physical activity levels) were performed, with p < 0.05.

RESULTS

Compared with healthy women, RA presented (i) lower physical activity level (- 29.4%; p < 0.001); (ii) lower isometric knee extensor strength (- 20.5%; p < 0.001); (iii) lower TUG performance (- 21.7%; p < 0.001); (iv) smaller muscle thickness (- 23.3%; p < 0.001) and pennation angle (- 14.1%; p = 0.011). No differences were observed in muscle activation and fascicle length. Finally, the correlation demonstrated that, with exception of TUG, muscle strength and muscle morphology were not associated with age in RA, differently from healthy participants.

CONCLUSION

Middle-aged RA patients' impairments occurred due to the disease independently of the aging process, except for functional capacity. Physical inactivity may have potentiated these losses.

miR‑760 regulates skeletal muscle proliferation in rheumatoid arthritis by targeting Myo18b

MicroRNAs serve an important role in the development of several diseases. Numerous genes regulate the skeletal muscle differentiation of C2C12 myoblasts. The role of miR-760 in rheumatoid arthritis (RA) has not been reported, to the best of our knowledge. Therefore, the aim of the present study was to examine the role of miR-760 in regulating skeletal muscle proliferation in RA. Potential genes functionally involved in the tarsal joint of a collagen-induced RA model were identified using Gene Expression Omnibus. Reverse transcription-quantitative PCR and western blot analyses were performed to determine the mRNA and protein expression levels. The proliferation, cell cycle progression and migration of C2C12 myoblasts were detected using Cell Counting Kit-8, flow cytometry and wound-healing assays, respectively. TargetScan was used to predict the potential target genes of miR-760, and this was verified using a dual-luciferase reporter assay. In the present study, myosin-18b (Myo18b) expression was determined to be downregulated in the RA model. Silencing Myo18b decreased the proliferation, abrogated the cell cycle progression, and reduced the migration and differentiation of C2C12 myoblasts. Expression levels of cyclin-dependent kinase 2, cyclin D1, matrix metalloproteinase (MMP)-2, MMP-9, myogenin and myosin heavy chain 6 were all decreased when Myo18b was silenced. Furthermore, overexpression of Myo18b induced opposing effects on C2C12 myoblasts. It was shown that Myo18b was a target gene of miRNA-760. Overexpression of miR-760 decreased proliferation, cell cycle progression, migration and differentiation in C2C12 myoblasts, and decreased the expression of Myo18b. The opposite results were observed when miR-760 was downregulated. In conclusion, miR-760 inhibited proliferation and differentiation by targeting Myo18b in C2C12 myoblasts. The results of the present study may contribute to understanding the mechanisms underlying RA skeletal muscle proliferation, and miR-760/Myo18b may serve as potential targets for treating patients with RA.

Dose-Response Relationship Between Neuromuscular Electrical Stimulation and Muscle Function in People With Rheumatoid Arthritis

BACKGROUND

Neuromuscular electrical stimulation (NMES) is a viable intervention for improving impaired muscle function in individuals with rheumatoid arthritis (RA). However, there is limited evidence about the dose-response relationship between NMES and muscle function in these individuals.

OBJECTIVE

The objectives of this study were to investigate the dose-response relationship between NMES and muscle function in individuals with RA and to establish the minimal NMES training intensity for promoting improvements.

DESIGN

This study was a secondary analysis of data obtained before and after an NMES intervention in a randomized study.

METHODS

The study took place at a research clinic. Only adults diagnosed with RA were included. The intervention consisted of 36 NMES treatment sessions for the quadriceps muscles over 16 weeks. Muscle function was measured before and after the intervention; quadriceps cross-sectional area and muscle quality were assessed using computed tomography, and strength was measured with an isokinetic dynamometer. NMES training intensity was calculated as a percentage by dividing NMES-elicited quadriceps muscle torque by the maximum voluntary isometric contraction. Improvements in muscle function were calculated using paired-sample t tests. The dose-response relationship was determined using curve estimation regression statistics. The minimum NMES training intensity was defined as that sufficient to significantly improve all muscle function measures.

RESULTS

Twenty-four people (48 legs) participated (75% women; mean [SD] age = 58 [8] years; mean body mass index = 32 [7] kg/m2). Quadriceps cross-sectional area, muscle quality, and strength improved after the intervention. Associations between NMES training intensity and muscle quality (r2 = 0.20) and strength (r2 = 0.23) were statistically significant, but that between NMES training intensity and muscle cross-sectional area was not (r2 = 0.02). The minimum NMES training intensity necessary to improve all measures of muscle function ranged from 11% to 20% of the maximum voluntary isometric contraction.

LIMITATIONS

The relatively small sample size was a limitation.

CONCLUSIONS

The minimum NMES training intensity for significant gains in muscle function was ∼15%. Higher NMES intensities may promote better muscle quality and strength in individuals with RA.

Linear Logistic Regression for Estimation of Lower Limb Muscle Activations

This paper addresses a technique to estimate the muscle activity from the movement data. Statistical models, such as linear regression (LR) models and artificial neural networks (ANNs), are good candidate estimation techniques. Although an ANN has a high estimation capability, it is frequently in the clinical application that a very small amount of data leads to performance deterioration. Conversely, an LR model needs fewer data, while its generalization performance is limited. In this paper, therefore, a muscle activity estimation method is proposed that uses a linear logistic regression model to improve the generalization performance. The proposed method was compared with an LR model and an ANN in verification experiments with several different conditions. The results suggest that the proposed method has a higher generalization performance than the conventional methods.

Hand grip endurance moderating the effect of grip force on functional ability and disease activity in rheumatoid arthritis patients: a cross-sectional study

To examine the effect of endurance on the relationship between grip force and measures of functional capacity and disease activity, we performed a cross-sectional study at the University Department of Rheumatology, Physical medicine and Rehabilitation from January 2017 to August 2018. Functional capacity of the hand was measured by ABILHAND-RA questionnaire and disease activity was assessed by the Disease Activity Score (DAS-28-CRP). All participants underwent dynamometric measurements of maximal grip force and hand grip endurance during repeated gripping. We analyzed the data from 34 RA patients at the median (IQR) age of 57 (51-61), 31 (91%) of them women, and 44 healthy participants at the age of 55 (50-59), 39 (89%) of them women. The moderating effect of endurance on the correlation between maximum grip force and the ABILHAND-RA score was not significant in healthy participants (b = 0.000, 95% CI - 0.005-0.004, p = 0.862), but it was in RA patients (b = 0.003, 95% CI 0.000-0.005, p = 0.027). In RA patients, the effect of maximum grip force on the ABILHAND-RA score increased with the increase in hand grip endurance. In RA patients, the interaction between endurance and grip force significantly explained the 15% more variance of the disease activity than main effects of these two measures, age, gender and body mass index alone. Hand grip endurance during repeated gripping affects the correlation between maximum grip force and the ABILHAND-RA score in a pattern that differs in RA patients and in the healthy population. In RA patients, hand grip endurance significantly moderates the correlation between maximum grip force and the DAS-28-CRP.

Perceived Versus Performance Fatigability in Patients With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory disease that affects 1% of the general population. Fatigue is a common complaint of patients with RA, however their perceived fatigue may be more exacerbated than objective measures of fatigue may indicate. The assessment of fatigue is made complex due to inconsistent and vague terms used to define fatigue, and the task dependence of fatigability. Fatigue is defined as a state of exhaustion and decreased strength, while fatigability indicates an individual's susceptibility to fatigue. In order to offer some clarity to the manifestation of fatigue in clinical populations, in this review we outline that fatigue should be described with subsections that are related to the symptom, such as: perceived fatigability and performance fatigability. Where perceived fatigability indicates the subjective state of the individual and thus involves the individual's subjective measure of fatigue, performance fatigability would be measured through clinical and laboratory-based assessments that quantify the functional decline in performance. This review describes RA and the various neuromuscular changes associated with the disease that can lead to alterations in both perceived and performance fatigue. From there, we discuss fatigue and RA, how fatigue can be assessed, effects of exercise interventions on RA symptoms and fatigue, and recommendations for future studies investigating subjective and objective measures of fatigability.

Decreasing muscle performance associated with increasing disease activity in patients with rheumatoid arthritis

OBJECTIVES

Increasing evidence suggests that inflammation has a detrimental effect on muscle strength. Our objective was to analyse the association between muscle performance and different disease activity levels in patients with rheumatoid arthritis (RA).

METHOD

A total of 199 consecutive outpatients were subject to cross-sectional assessment. Measurements of grip strength, endurance of the upper and lower limbs and trunk strength were combined as a muscle performance composite score (MPCS), using a standardised method. The disease activity for 28 joints (DAS28), radiographs of small joints (Larsen score), rheumatoid factor, body mass index (BMI), comorbidities and anti-rheumatic drugs were verified. Patients' questionnaires included sociodemographic information, pain level, global disease activity, the Beck Depression Inventory, the mental and physical component scores of Short Form-36 and physical activity level.

RESULTS

Of the 199 patients, 36%, 17% and 47% patients had remission, low/moderate and high DAS28, respectively. The patients in remission had significantly shorter disease duration, better parameters in terms of pain, physician's assessment, Larsen, Beck or physical component score of Short Form-36, and they were more physically active than other patients. After adjustments for age, sex, RA duration, radiographs and BMI, the decreasing MPCS associated linearly with the increasing DAS28 activity levels (linearity, P <0.001).

CONCLUSION

Poorer MPCS is clearly associated with higher disease activity in patients with RA. Muscle performance is a modifiable risk factor. The findings suggest evaluating muscle performance in clinical practice as a part of patient care.

Tight control of disease activity fails to improve body composition or physical function in rheumatoid arthritis patients

OBJECTIVE

RA typically features rheumatoid cachexia [loss of muscle mass (MM) and excessive total fat mass (TFM), especially trunk FM], which contributes to physical disability. Since rheumatoid cachexia is driven by inflammation, it would be anticipated that the success of tight control of disease activity, such as treat-to-target (T2T), in attenuating inflammation would benefit body composition and physical function. This aim of this cross-sectional study was to assess the impact of T2T on body composition and objectively assessed function in RA patients.

METHODS

A total of 82 RA patients exclusively treated by T2T, were compared with 85 matched sedentary healthy controls (HCs). Body composition was estimated by DXA, with appendicular lean mass the surrogate measure of total MM. Physical function was assessed by knee extensor strength, handgrip strength, 30 s sit-to-stands, 8' up and go, and 50' walk (tests which reflect the ability to perform activities of daily living).

RESULTS

Although generally well treated (mean DAS28 = 2.8, with 49% in remission), RA patients had ∼10% proportionally less appendicular lean mass and were considerably fatter (by ∼27%), particularly in the trunk (∼32%), than HCs. All measures of function were 24-34% poorer in the RA patients relative to HC.

CONCLUSIONS

Despite marked improvements in disease control (most patients achieving or approaching remission), the relative loss of MM and increased adiposity in RA patients compared with matched HCs was similar to that observed pre-T2T. Additionally, performance of objective function tests was unchanged from that reported by our group for pre-T2T RA patients. Thus T2T, even in responsive RA patients, did not attenuate rheumatoid cachexia or improve objectively assessed function.

Preserved skeletal muscle protein anabolic response to acute exercise and protein intake in well-treated rheumatoid arthritis patients

Introduction

Rheumatoid arthritis (RA) is often associated with diminished muscle mass, reflecting an imbalance between protein synthesis and protein breakdown. To investigate the anabolic potential of both exercise and nutritional protein intake we investigated the muscle protein synthesis rate and anabolic signaling response in patients with RA compared to healthy controls.

Methods

Thirteen RA patients (age range 34–84 years; diagnosed for 1–32 years, median 8 years) were individually matched with 13 healthy controls for gender, age, BMI and activity level (CON). Plasma levels of C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were measured using enzyme-linked immunosorbent assay (ELISA) in resting blood samples obtained on two separate days. Skeletal muscle myofibrillar and connective tissue protein fractional synthesis rate (FSR) was measured by incorporation of the amino acid ¹³C₆-phenylalanine tracer in the overnight fasted state for 3 hours (BASAL) and 3 hours after intake of whey protein (0.5 g/kg lean body mass) alone (PROT, 3 hrs) and in combination with knee-extensor exercise (EX) with one leg (8 × 10 reps at 70 % of 1RM; PROT + EX, 3 hrs). Expression of genes related to inflammatory signaling, myogenesis and muscle growth/atrophy were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

Results

CRP was significantly higher in the RA patients (2.25 (0.50) mg/l) than in controls (1.07 (0.25) mg/l; p = 0.038) and so was TNF-α (RA 1.18 (0.30) pg/ml vs. CON 0.64 (0.07) pg/ml; p = 0.008). Muscle myofibrillar protein synthesis in both RA patients and CON increased in response to PROT and PROT + EX, and even more with PROT + EX (p < 0.001), with no difference between groups (p > 0.05). The gene expression response was largely similar in RA vs. CON, however, expression of the genes coding for TNF-α, myogenin and HGF1 were more responsive to exercise in RA patients than in CON.

Conclusions

The study demonstrates that muscle protein synthesis rate and muscle gene expression can be stimulated by protein intake alone and in combination with physical exercise in patients with well-treated RA to a similar extent as in healthy individuals. This indicates that moderately inflamed RA patients have maintained their muscle anabolic responsiveness to physical activity and protein intake.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0758-3) contains supplementary material, which is available to authorized users.

Evaluation of muscle quality reliability and racial differences in body composition of overweight individuals

The purpose of this study was to evaluate the reliability of ultrasound measures of muscle cross-sectional area (mCSA) and echo intensity (EI) in overweight subjects. A secondary purpose was to evaluate racial differences in EI, mCSA and body composition. In 33 overweight subjects, mCSA and EI were determined from a panoramic ultrasound scan of the vastus lateralis. Body composition was determined using dual-energy X-ray absorptiometry (DXA). Reliability of mCSA and EI was calculated from the intra-class correlation coefficient (ICC), standard error of the measurement (SEM) and minimal difference (MD). The ICC, SEM and MD for mCSA and EI were 0.87, 2.12, 5.89 and 0.74, 4.58, 12.69, respectively. There were no significant racial differences in body composition (p > 0.05); however, EI was significantly lower for black subjects (p = 0.018). These results suggest ultrasound measures of mCSA and EI are reliable in overweight subjects, and EI may provide additional muscle composition evaluations, beyond DXA measures.

Temporal development of muscle atrophy in murine model of arthritis is related to disease severity

BACKGROUND

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease of unknown etiology, affecting mainly the joint but also other tissues. RA patients usually present weakness and muscle atrophy, nonarticular manifestations of the disease. Although causing great impact, the understanding of muscle atrophy, its development, and the mechanisms involved is still very limited. The objective of this study is to evaluate the development of muscle atrophy in skeletal muscle of a murine model of arthritis.

METHODS

The experimental murine model of collagen-induced arthritis (CIA) was used. DBA/1J mice were randomly divided into three groups: control (CO, n = 25), sham arthritis (SA, n = 25), and arthritis (CIA, n = 28), analyzed in different time points: 25, 35, and 45 days after the induction of arthritis. The arthritis development was followed by clinical scores and hind paw edema three times a week. The spontaneous exploratory locomotion and weight were evaluated weekly. In all time points, serum was collected before the death of the animals for cytokine analysis, and myofiber cross-sectional areas (CSA) of gastrocnemius (GA) and tibialis anterior (TA) skeletal muscles were evaluated.

RESULTS

The clinical parameters of arthritis progressively increased in CIA in all experimental times, demonstrating the greatest difference from other groups at 45 days after induction (clinical score: CO, 00 ± 00; SA, 1.00 ± 0.14; CIA, 3.28 ± 0.41 p > 0.05). The CIA animals had lower weights during all the experimentation periods with a difference of 6 % from CO at 45 days (p > 0.05). CIA animals also demonstrated progressive decrease in distance walked, with a reduction of 54 % in 35 and 74 % at 45 days. Cytokine analysis identified significant increase in IL-6 serum levels in CIA than CO and SA in all experimental times. CSA of the myofiber of GA and TA was decreased 26 and 31 % (p > 0.05) in CIA in 45 days after the induction of disease, respectively. There was significant and inverse correlation between the disease clinical score and myofiber CSA in 45 days (GA: r = -0.71; p = 0.021).

CONCLUSION

Our results point to a progressive development of muscle wasting, with premature onset arthritis. These observations are relevant to understand the development of muscle loss, as well as for the design of future studies trying to understand the mechanisms involved in muscle wasting. As far as we are concerned, this is the first study to evaluate the relation between disease score and muscle atrophy in a model of arthritis.

Patellar tendon properties and lower limb function in rheumatoid arthritis and ankylosing spondylitis versus healthy controls: a cross-sectional study

Objective. Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) lead to inflammation in tendons and peritendinous tissues, but effects on biomechanical tendon function are unknown. This study investigated patellar tendon (PT) properties in stable, established RA and AS patients. Methods. We compared 18 RA patients (13 women, 59.0 ± 2.8 years, mean ± SEM) with 18 age- and sex-matched healthy controls (58.2 ± 3.2 years), and 12 AS patients (4 women, 52.9 ± 3.4 years) with 12 matched controls (54.5 ± 4.7 years). Assessments with electromyography, isokinetic dynamometry, and ultrasound included quadriceps muscle force and cross-sectional area (CSA), PT stiffness, and PT CSA. Additionally, measures of physical function and disease activity were performed. Results. PT stiffness and physical function were lower in RA and AS patients compared to healthy controls, without a significant difference in force production. PT CSA was significantly larger leading to reduction in Young's modulus (YM) in AS, but not in RA. Conclusion. The adverse changes in PT properties in RA and AS may contribute to their impaired physical function. AS, but not RA, leads to PT thickening without increasing PT stiffness, suggesting that PT thickening in AS is a disorganised repair process. Longitudinal studies need to investigate the time course of these changes and their response to exercise training.

Reliability study of tibialis posterior and selected leg muscle EMG and multi-segment foot kinematics in rheumatoid arthritis associated pes planovalgus

OBJECTIVE

To determine within- and between-day reliability characteristics of electromyographic (EMG) activity patterns of selected lower leg muscles and kinematic variables in patients with rheumatoid arthritis (RA) and pes planovalgus.

METHODS

Five patients with RA underwent gait analysis barefoot and shod on two occasions 1 week apart. Fine-wire (tibialis posterior [TP]) and surface EMG for selected muscles and 3D kinematics using a multi-segmented foot model was undertaken barefoot and shod. Reliability of pre-determined variables including EMG activity patterns and inter-segment kinematics were analysed using coefficients of multiple correlation, intraclass correlation coefficients (ICC) and the standard error of the measurement (SEM).

RESULTS

Muscle activation patterns within- and between-day ranged from fair-to-good to excellent in both conditions. Discrete temporal and amplitude variables were highly variable across all muscle groups in both conditions but particularly poor for TP and peroneus longus. SEMs ranged from 1% to 9% of stance and 4% to 27% of maximum voluntary contraction; in most cases the 95% confidence interval crossed zero. Excellent within-day reliability was found for the inter-segment kinematics in both conditions. Between-day reliability ranged from fair-to-good to excellent for kinematic variables and all ICCs were excellent; the SEM ranged from 0.60° to 1.99°.

CONCLUSION

Multi-segmented foot kinematics can be reliably measured in RA patients with pes planovalgus. Serial measurement of discrete variables for TP and other selected leg muscles via EMG is not supported from the findings in this cohort of RA patients. Caution should be exercised when EMG measurements are considered to study disease progression or intervention effects.

Kinematic analysis of sit to stand by persons with rheumatoid arthritis supported by a service dog

PURPOSE

The objective of this study was to quantify the kinesiological effect of the assistance provided by service dogs on transferring from sit to stand in persons with rheumatoid arthritis (RA).

METHODS

Twenty-four participants performed a total of eight experimental transfers of sit to stand, including unassisted transfers, transfers with a cane and transfers with assistance from a service dog. We analysed movements at the lower extremity joints using a three-dimensional kinematics system and two force plates.

RESULTS

At the hip joints, the range of motion changes and energy expenditure with a cane and with the service dog were smaller than that of the unassisted transfers. Transfers with a service dog resulted in less joint movement and less energy used in movements at the knee and ankle joints; participants also scored themselves as requiring less effort on a self-rating scale than in the other conditions.

CONCLUSION

A service dog provides benefits in assisting with transfers from sit to stand by persons with RA. Future studies should consider training the service dogs to assume correct positions and use appropriate timing to support their partners during these transfers.

Fatigue in systemic lupus erythematosus: an association with reduced physical fitness

Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterized by fatigue; however, little research has been performed to identify non-pharmacological strategies, such as physical exercise, that can be employed in the prevention and treatment of fatigue in patients with SLE. Moreover, it is not clear whether physical fitness (defined here as cardiovascular fitness and muscle strength) and functional capacities are related to SLE-associated fatigue. Here, we review the studies, mechanisms and results that relate to SLE-associated fatigue. The main findings indicate that SLE patients have lower cardiovascular capacity than healthy subjects. Physical fitness, muscle strength and functional capacity are also lower in patients with SLE than in healthy individuals. The effects of exercise programs in reducing symptoms of fatigue in SLE patients remain unclear.

Benefits of exercise in rheumatoid arthritis

This paper aims to highlight the importance of exercise in patients with rheumatoid arthritis (RA) and to demonstrate the multitude of beneficial effects that properly designed exercise training has in this population. RA is a chronic, systemic, autoimmune disease characterised by decrements to joint health including joint pain and inflammation, fatigue, increased incidence and progression of cardiovascular disease, and accelerated loss of muscle mass, that is, “rheumatoid cachexia”. These factors contribute to functional limitation, disability, comorbidities, and reduced quality of life. Exercise training for RA patients has been shown to be efficacious in reversing cachexia and substantially improving function without exacerbating disease activity and is likely to reduce cardiovascular risk. Thus, all RA patients should be encouraged to include aerobic and resistance exercise training as part of routine care. Understanding the perceptions of RA patients and health professionals to exercise is key to patients initiating and adhering to effective exercise training.