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Self-reported disability is potentially influenced by many factors in patients with rheumatoid arthritis (RA). In this sense, we evaluated the association between self-reported disability and (1) clinical features, (2) muscle strength and (3) physical performance over time among patients with RA from two distinct patient cohorts. Two independent prospective RA cohorts were analyzed. The Health Assessment Questionnaire (HAQ), Disease Activity Score in 28 Joints (DAS28), handgrip test, chair stand test, timed-up-and-go (TUG) test and Short Physical Performance Battery (SPPB) were performed at baseline and in follow-up. T test for independent samples, Mann-Whitney U test, Spearman correlation coefficients and linear regression with generalized estimating equations were performed to assess associations between individual constructs at baseline and over time. A total of 205 total RA patients were included [North American Cohort (n = 115); Brazilian Cohort (n = 90)]. At enrollment, Brazilian men had better HAQ than North American men (p<0.001). Brazilian patients overall had lower muscle strength than North American patients (p<0.05). HAQ was associated with DAS28, handgrip test, chair stand test, TUG and SPPB (p<0.001) in both cohorts. Worsening of the DAS28 and chair stand test were each associated with worsening in HAQ in longitudinal analysis over time. Worsening of handgrip was also associated in with worsening HAQ in both cohorts (p<0.05). A worse TUG test was associated with worsening in HAQ in Brazilian cohort (p<0.05) and a worse SPPB was associated with worsening in HAQ in North American cohort (p<0.05). Greater disability measured by HAQ is closely associated with disease activity, pain, muscle strength, and physical performance among RA. Worsening in self-reported disability correlate with worsening clinical factors including objectively-observed physical function.

This study aimed to investigate the molecular pathways involved in muscle wasting in an animal model of osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT) in rats. Reduction of protein syntheses, increased proteolysis and impaired muscle regeneration are important pathways related to muscle wasting, and myogenin, MyoD, myostatin and MuRF-1 are some of their markers. Female Wistar rats were allocated into two groups: OA (submitted to the ACLT) and SHAM (submitted to surgery without ACLT). Nociception, spontaneous exploratory locomotion and body weight of animals were evaluated weekly. Twelve weeks after the disease induction, animals were euthanized, and the right knee joints were collected. Gastrocnemius muscle of the right hind paw were dissected and weighed. Gastrocnemius was used for evaluation of muscle atrophy and expression of IL-1β, TNF-α, Pax7, myogenin, MyoD, myostatin and MuRF-1. Histopathology of the knee confirmed the development of the disease in animals of OA group. Gastrocnemius of OA animals showed a reduction of about 10% in area and an increased IL-1β expression compared to animals of SHAM group. Expression of myostatin was increased in OA group, while myogenin expression was decreased. TNF-α, Pax7, MuRF-1 and MyoD expression was similar in both OA and SHAM groups. Nociception was significantly elevated in OA animals in the last two weeks of experimental period. Spontaneous exploratory locomotion, body weight and weight of gastrocnemius showed no difference between OA and SHAM groups. Gastrocnemius atrophy in OA induced by ACLT involves elevated expression of IL-1β within the muscle, as well as increased expression of myostatin and decreased expression of myogenin. Therefore, muscle wasting may be linked to impaired muscle regeneration.

BackgroundThe myokines irisin and myostatin participate in bone and skeletal muscle homeostasis and may characterize the clinical status of these tissues. The study aimed to evaluate the association of myokines serum levels with one-year radiographic progression and lean mass in individuals with rheumatoid arthritis (RA).MethodsForty female individuals with RA, aged ≥ 18 years who met 2010 American College of Rheumatology criteria, and 30 individuals without RA and any chronical disease, matched by sex and body mass index (BMI) were included. Serum levels of irisin and myostatin were determined by immune assay. RA subjects had their radiographs of hands and feet evaluated by Sharp/van der Heijde score (SHS) at two timepoints, baseline and after one year. At baseline, disease activity was calculated by Disease Activity Score 28-C reactive protein (DAS28-CRP), body composition was evaluated using dual X-ray absorptiometry (DXA), muscle strength was assessed by handgrip test and chair rising test (CRT), and physical function was assessed by Health Assessment Questionnaire-Disability Index (HAQ-DI) and timed up and go (TUG) test.ResultsMean age of individuals was 56 ± 7.8 years, mean DAS28-CRP was 3.3 ± 1.3, mean disease duration was 11.2 ± 9.2 years, and mean BMI was 28.1 ± 5.1 kg/m2. Rapid radiographic progression and low lean mass were present in 17.5% and 14.8% of the RA individuals, respectively, and showed no correlation with irisin and myostatin. Myostatin was significantly lower in RA than in controls (3021.7 ± 1217.2 vs. 4049.0 ± 1610.0 pg/ml; p = 0.011), and individuals treated with biologic disease-modifying antirheumatic drugs (bDMARDs) showed higher irisin levels than individuals non-treated with bDMARDs (31.7 ± 7.6 vs. 25.7 ± 6.8 ng/ml; p = 0.033). RA duration was correlated with baseline SHS (r = 0.563; p = 0.001) and appendicular lean mass index (ALMI; r= -0.451; p = 0.004), and irisin levels were positively correlated with TUG (r = 0.338; p = 0.35) in RA.ConclusionsLong-term RA was related with higher SHS and lower ALMI, and the late disease stage of included individuals possibly masked the association of myokines with one-year radiographic progression or low lean mass. Otherwise, bDMARDs treatment influenced myokines circulating levels, specifically irisin.

BackgroundSarcopenia is a muscle disease characterized by reduction of muscle strength and muscle mass. In RA, 25.9 to 43.3% of the patients present sarcopenia. The loss of muscle mass observed in RA patients occurs either by activation of catabolic pathways or by inhibition of anabolic pathways. Despite having a list of drugs capable of treating RA inflammation, their effect on muscle is unclear. Our objective was to evaluate the tofacitinib effect on the muscle mass of collagen-induced arthritis (CIA) mice.MethodsCIA was induced in male DBA/1J mice by subcutaneous injection of Type 2 Collagen plus Freund Adjuvant. Animals were randomized into 3 groups: CIA + tofacitinib; CIA + vehicle; and healthy controls. Treatment was administered twice a day, between days 18 and 45 after induction. Clinical score, edema, and body weight were evaluated during the experimental period. After euthanasia, tibiotarsal joints were collected for assessment of disease histopathological score, and tibialis anterior (TA) and gastrocnemius (GA) muscles were weighed to assess muscle mass. Muscle atrophy was evaluated by measurement of TA myofiber cross-sectional area (CSA). Protein expression was evaluated by western blot using GA homogenates. Serum inflammatory markers were evaluated by ELISA. Statistical analysis included ANOVA followed by Tukey’s or with Kruskal-Wallis. The statistical difference was assumed for p < 0.05.ResultsTofacitinib treatment decreased arthritis severity by reducing clinical score, and hind paw edema in comparison with the vehicle group. Tofacitinib showed weight gain, higher TA and GA weights, and increased CSA compared to the vehicle group. On day 45, Tofacitinib presented increased muscle strength compared to the vehicle group, however, no difference was found in muscle fatigue. Pax7 expression was unchanged, while MyoD expression showed an increasing trend, and myogenin expression was significantly increased in Tofacitinib compared to vehicle and control groups. The treatment didn’t modify Murf-1 expression. Tofacitinib mice showed decreased serum levels of TNF and increased IL-6 serum levels.ConclusionTofacitinib attenuated muscle loss in arthritic mice, increased muscle weight and muscle CSA. Activation of satellite cell regeneration, based on the increased expression of myogenin, is a potential mechanism involved in tofacitinib action against muscle loss.

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial inflammation, fibroblast-like synoviocytes (FLS) activation and joint destruction. Fasciola hepatica is a platyhelminth that releases excretory-secretory immunomodulatory products capable of suppressing the Th1 immune response. Despite the effectiveness of available treatments for inducing disease remission, current options are not successful in all patients and may cause side effects. Thus, we evaluated the therapeutic potential of F. hepatica extract on FLS from RA patients and arthritis models.MethodsFLS were isolated from synovial fluid of RA patients, cultured, and exposed to F. hepatica extract (60, 80, and 100 µg/ml) for different time points to assess cell viability, adherence, migration and invasion. For in vivo experiments, mice with antigen (AIA) and collagen (CIA) induced arthritis received a 200 µg/dose of F. hepatica extract daily. Statistical analysis was performed by ANOVA and Student's t-test using GraphPad Prism 6.0.ResultsIn vitro assays showed that extract decreased FLS cell viability at concentration of 100 µg/ml (83.8% ± 5.0 extract vs. 100.0% ± 0.0 control; p < 0.05), adherence in 20% (92.0 cells ± 5.8 extract vs. 116.3 cells ± 7.9 control; p < 0.05), migratory potential (69.5% ± 17.6 extract vs. 100.0% control; p < 0.05), and cell invasiveness potential through the matrigel (76.0% ± 8.4 extract vs. 100.0% control; p < 0.01). The extract reduced leukocyte migration by 56% (40 × 104 leukocytes/knee ± 19.00) compared to control (90.90 × 104 leukocytes/knee ± 12.90) (p < 0.01) and nociception (6.37 g ± 0.99 extract vs. 3.81 g ± 1.44 control; p < 0.001) in AIA and delayed clinical onset of CIA (11.75 ± 2.96 extract vs. 14.00 ± 2.56 control; p = 0.126).ConclusionOur results point out a potential immunomodulatory effect of F. hepatica extract in RA models. Therefore, the characterization of promising new immunomodulatory molecules should be pursued, as they can promote the development of new therapies.Trial registration Collection of synovial liquid and in vitro procedures were approved by the Ethics Committee with Certificate of Presentation of Ethical Appreciation in Plataforma Brasil (CAAE: 89044918.8.0000.5327; date of registration: 26/07/2018).