Eduarda Correa Freitas

Pristane-induced lupus: considerations on this experimental model

Systemic lupus erythematosus (SLE) is a multifactorial, autoimmune inflammatory disease with pleomorphic clinical manifestations involving different organs and tissues. The etiology of this disease has been associated with a dysfunctional response of B and T lymphocytes against environmental stimuli in individuals genetically susceptible to SLE, which determines an immune response against different autoantigens and, consequently, tissue damage. The study of different murine models has provided a better understanding of these autoimmune phenomena. This review primarily focuses on that has been learned from the pristane-induced lupus (PIL) model and how this model can be used to supplement recent advances in understanding the pathogenesis of SLE. We also consider both current and future therapies for this disease. The PubMed, SciELO, and Embase databases were searched for relevant articles published from 1950 to 2016. PIL has been shown to be a useful tool for understanding the multiple mechanisms involved in systemic autoimmunity. In addition, it can be considered an efficient model to evaluate the environmental contributions and interferon signatures present in patients with SLE.

Muscle wasting in osteoarthritis model induced by anterior cruciate ligament transection

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.

Collagen-induced arthritis as an animal model of rheumatoid cachexia: CIA as an animal model of RA

Rheumatoid arthritis is characterized by chronic polyarticular synovitis and presents systemic changes that impact quality of life, such as impaired muscle function, seen in up to 66% of the patients. This can progress to severely debilitating state known as rheumatoid cachexia—without loss of fat mass and body weight—for which there is little consensus in terms of diagnosis or treatment. This study aims to evaluate whether the collagen‐induced arthritis (CIA) animal model also develops clinical and functional features characteristic of rheumatoid cachexia.

AB0135 Aerobic Exercise in Inclined Treadmill Reduce Fatigue in Collagen-Induced Arthritis

Background Rheumatoid arthritis (RA) patients suffer from joint pain and decreased physical capacity, like muscle wasting and fatigue. Fatigue is a clinical manifestation reported by 40-80% of patients with RA and is regarded as an important feature of the disease. Aerobic exercise may be beneficial for treating this feature in RA patients, however the mechanisms involved are still unclear. Objectives To evaluate the effect of aerobic exercise training on the endurance exercise performance in collagen-induced arthritis (CIA) mice. Methods Male DBA1/J mice with CIA [1] were randomly divided into 3 groups: wildtype with exercise (WT-EXE, n=4), CIA exercised (CIA-EXE, n=5) and CIA non-exercised (CIA, n=4). Endurance exercise performance test (fatigue) was analyzed in all groups prior to booster injection and each 15 days after protocol started. Eighteen days after the disease induction (booster), WT and CIA-EXE were submitted to training on an inclined treadmill (θ=5°), 45 minutes a day, 5 days per week for 6 weeks at 60% of their own endurance exercise performance. Variables analyzed were disease score, hindpaw nociception, body weight (g), fatigue (by endurance exercise performance in min) and relative muscle weight (muscle weight in mg divided by total animal weight in g). Data was analyzed with ANOVA Two-Way followed by Bonferroni and independent sample t-test and p<0.05 was considered significant. All data are represented as Mean ± SEM. Results Body weight was significantly higher in WT-EXE compared with CIA after 4 and 6 weeks of exercise. At week 6 of exercise, CIA-EXE had higher body weight than CIA. Fatigue test at 4 and 6 weeks of experiment was significantly different among all experimental groups; WT-EXE and CIA had, respectively, the highest and the lowest fatigue velocity. Gastrocnemius muscle weight was significantly heavier in control group than in CIA-EXE and CIA. Nociception and clinical score of arthritis did not differ between CIA-EXE and CIA. Conclusions Inclined aerobic exercise appears as an interesting intervention in RA to treat decreased physical capacity. Collagen-induced arthritis animals demonstrated decreased endurance, and consequently increased fatigue, characteristics of a good animal model to study fatigue. The exercise protocol used in this study was able to improve this feature, demonstrating that interventions used to treat physical disabilities in RA are also valid in this model. Further studies are necessary to clarify the mechanisms behind fatigue, especially when combining exercise training and common treatments of RA. References Rosloniec EF, et al. Curr Protoc Immunol 2010; Chapter 15: Unit 15.5.1-25. Acknowledgements Financial support: CAPES, CNPq, FAPERGS, FIPE-HCPA. Disclosure of Interest None declared

AB0117 Collagen-Induced Arthritis in Mice as a Model of Rheumatoid Cachexia

Background Rheumatoid arthritis (RA) extra-articular features frequently involved metabolism alterations which in a context are known as rheumatoid cachexia. Loss of lean muscle mass, reduction of grip strength and fatigue are the most common signs in RA. Loss of body weight and reduction in food intake are not usually part of human rheumatoid cachexia, but have been demonstrated before in animal models of arthritis. Recently, Evans et al1 published a definition for cachexia that seems to fulfil rheumatoid condition. Therefore a better elucidation of rheumatoid cachexia is needed and an animal model that mimics human condition may be useful. Objectives To explored the possibility of using collagen-induced arthritis in mice as an animal model of cachexia. Methods 8-12 weeks male DBA/1J mice were separated in two groups: control (CO) and collagen-induced arthritis (CIA). CIA animals were immunized by intradermal injection of bovine type II collagen with complete Freunds adjuvant followed by a booster. Immunization protocol and clinical signs (arthritis score and paw edema) evaluation occur as previous described by Brand et al 20072. Animals were followed by 65 days with evaluations made in day zero and at 18, 25, 35, 45, 55 and 65 days after immunization. Rheumatoid cachexia was evaluated by body weight change (%), food intake (g), fatigue (by endurance exercise performance in minutes), grip strength (g), locomotion (cm) and relative muscle weight (muscle weight in mg divided by total animal weight g). Statistical analysis includes repeated measures analysis of variance (ANOVA) for variables with variation between time and group and t-test for variables with variation only between groups. Difference was assumed when p value were lower than 0.05. Results Arthritis score and paw edema confirm disease in CIA group. Fatigue was higher in CIA group (lower time in endurance exercise) at the same time that grip strength and locomotion was lower (after 35 days until the end of the experiment). Relative gastrocnemius muscle weight was also lower in CIA group 3.9±0.57mg/g vs 5.0±0.61mg/g (CO). Body weight change and food intake were not statistical different within groups, however in days 25 and 35 CIA animals lost more weight than CO animals. Conclusions These data demonstrate firstly that CIA animals show metabolic extra articular events that mimics human pathophysiology arthritis. Even though there were no difference in body weight change and food intake it reinforces the similarity among CIA animal model and human RA once this variables have the same behavior in humans. Also considering the lack of studies involving rheumatoid cachexia and the obstacle that involve this study design in humans it is essential to have a solid animal model to evaluate prospectively mechanism of rheumatoid cachexia. References Evans WJ, et al. 2008. Cachexia: a new definition. Clinical Nutrition 27(6):793-9. Brand DD, Latham KA, Rosloniec EF. 2007. Collagen-induced arthritis. Nature protocols 2(5):1269-75. Disclosure of Interest None declared

AB0094 Histopathological Muscle Findings in Experimental Osteoarthritis

Background Osteoarthritis (OA) is a chronic joint disease characterized by progressive loss of articular cartilage and abnormal bone formation. Furthermore, there are changes in periarticular muscles, such as loss of muscle mass, strength and function. These features may contribute to functional impairment among patients. Objectives To study the effects of OA induced by anterior cruciate ligament transection (ACLT) on muscle histopathology in rat. Methods Female Wistar rat underwent ACLT surgery (n=9) or sham surgery (n=8) (1) on the right knee only. Body weight and spontaneous exploratory locomotion were evaluated weekly. Twenty weeks after the surgery, animals were euthanized. Joints from the right knee were collected for histological analyses. Gastrocnemius muscles from the right paw were collected for weighing and histological and molecular analyses. Data were analyzed with ANOVA Two-Way followed by Bonferroni and independent samples t-test and p<0.05 was considered significant. Results Body weight and spontaneous exploratory locomotion were not statistically different between groups, during the experimental period. Histological evaluation of the right knee joint proved the development of OA in animals which underwent ACLT surgery (p<0,01), accordingly to OARSI histologic scoring system (2). The weight of gastrocnemius muscle was not statistically different between groups at the end of the experimental period (p<0,14). Histological evaluation of gastrocnemius muscle fiber cross-sectional area (CSA) (3) showed a reduction in muscle fiber CSA in ACLT animals (p=0,0006). Conclusions ACLT induced chronic degenerative articular changes and muscle fiber CSA reduction in rats. It is yet to be studied what factors are related to atrophy, evaluating the expression of muscle factors related to muscle growth, differentiation, and mass regulation. References Elsaid KA, Machan JT, Waller K, Fleming BC, Jay GD. The Impact of Anterior Cruciate Ligament Injury on Lubricin Metabolism and the Effect of Inhibiting Tumor Necrosis Factor alpha on Chondroprotection in an Animal Model. Arthritis and Rheumatism. 2009;60(10):2997-3006. Gerwin N, Bendele AM, Glasson S, Carlson CS. The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the rat. Osteoarthritis and Cartilage. 2010;18:S24-S34. Filippin LI, Teixeira VN, Viacava PR, Lora PS, Xavier LL, Xavier RM. Temporal development of muscle atrophy in murine model of arthritis is related to disease severity. Journal of Cachexia Sarcopenia and Muscle. 2013;4(3):231-8. Acknowledgements Financial support: CAPES, FIPE-HCPA. Disclosure of Interest None declared

AB0086 Food preferences in rats with collagen induced arthritis

Background Rheumatoid arthritis (RA) is an inflammatory disease with autoimmune manifestations characterized by chronic inflammation of the joints associated with systemic complications [1]. Systemic inflammation of RA causes metabolic changes and deregulation of leptin, adiponectin and insulin, leading to anorexia, changes in normal food intake and weight loss [2]. However, observational with human subjects have many potential bias and animal models can be a good alternative for studies on the effect of chronic arthritis in metabolic changes and feeding preferences. Objectives To evaluate the feeding preferences of rats with type II collagen induced arthritis (CIA). Methods Female Wistar rats were separated in two groups: control (CO) and collagen-induced arthritis (CIA) performed accordingly to Rosloniec et al. [3] with modifications (without booster). Arthritis clinical score (0-16) of animals was registered three times a week for analysis of the development of the disease [3]. All animals were offered four different diets at the same time: control diet (standard ration - CD), high calorie diet (addition of 5% of saccharose – HCD), high protein diet (addition of 5% of albumin – HPD) and high fat diet (addition of 5% of soybean oil – HFD). The animals and ration leftovers were weighted every three days for 14 days before and 25 days after the induction of arthritis. Comparison between groups was performed by two-way ANOVA followed by Tukey post-hoc test. Results The first signs of arthritis appeared by 14 days after induction (score 2.7±3.1) and the inflammatory peak appeared to be around day 17 to day 22 (score 9.8±4.1). Food consumption of control and CIA rats before the onset of arthritis was: 45% of HCD (51.9±6.4 g), 36% of HFD (41.6±9.7 g), 13% of HPD (15.3±5.1 g) and 7% of CD (7.5±5.8 g). During the peak of arthritis, CIA rats had a significant weight loss (-14.7±8.5 g) while CO group maintained their weight (-0.2±4.6 g, p<.01). At the same time, CIA had reduced total food intake (72.3 ± 8.6 g) compared to CO (107.3±5.7 g, p<.01). Besides that, CIA changed the food preference, increasing the intake of HPD to 20% (16.3±5.3 g, p<.05) and reducing the ingestion of the HCD to 27% (22.6±7.8 g, p<.05) compared to CO (10.0±1.5 g and 58.3±21.3 g, respectively). Conclusions CIA animals demonstrated changes in their food intake, especially during the inflammatory peak of arthritis, with concomitant reduction in weight. These changes include decreased total food consumption and different food preferences, like increased intake of high-protein diet and reduced intake of high-calorie diet, results never reported before. There is still needed more studies about the feeding preferences and intake, but CIA model could be a good model to study altered food consumption caused by arthritis and hereafter correlate these findings with alterations in RA patients. References Mc Innes IB, et al. Engl J Med, 2011. 365(23):2205-19. Argilés JM, et al. J. Biocel, 2005. 37(10):2036-46. Rosloniec EF, et al. Curr Protoc Immunol, 2010. Chapter 15: Unit 15.5 1-25. Acknowledgements FIPE-HCPA, CAPES, CNPq Disclosure of Interest None Declared