POS1019 DIPYRIDAMOLE, A COMPOUND THAT INCREASES EXTRACELLULAR ADENOSINE LEVELS, AS A THERAPEUTIC AGENT FOR RHEUMATOID SARCOPENIA

Abstract

BackgroundIn addition to joint damage, rheumatoid arthritis (RA) confers a higher risk of several comorbidities, including changes in body composition with reduced muscle mass and strenght (sarcopenia) with stable or increased fat mass. Adenosine and ATP are responsible for the maintenance of energy balance and activate cell signaling through selective receptors. Adenosine A2A receptor activation regulates bone turnover, targetting bone destruction in inflammatory diseases like RA. The use of dipyridamole (blocks adenosine uptaken by the cells increasing extracellular adenosine levels activating adenosine receptors) modulates the intracellular and extracellular levels of adenosine and ATP in murine C2C12 myoblasts, via activation of the adenosine A2B receptor, cAMP and AMPK pathways, counteracting deleterious effects on skeletal muscle differentiation.ObjectivesTo determine if dipyridamole prevents sarcopenia in arthritis murine model.Methods12-wk-old C57BL/6 male mice were injected with pooled K/BxN serum (100 μl, ip) on day 0 and 2. Dipyridamole 25mg/Kg was administered daily starting after the first serum injection. Clinical signs (joint swelling and thickness) were measured daily. DXA analysis and motor activity tests were performed prior to serum inoculation and at day 13. Mice were euthanized on day 16. Inflammatory cytokines and C-reactive protein (CPR) were measured in serum. Gastronemius was collected for protein and RNA extraction. Tibialis was frozen and embedded in OCT for histology.ResultsSerum transfer (RA mice) induced an increase in joint inflammation that was maximal 2wk after injection. Dipyridamole decreased the appearance of inflammation in the joints (clinical score of 5±3 vs 14±1 RA mice, p<0.005, n=7), and counteracted weight loss (p<0.01). Moreover, dipyridamole modulates the systemic inflammation found in RA mice promoting an signifficant increase on anti-inflammatory cytokines such as IL-10, and a signifficant reduction on pro-inflammatory citokines such as INFγ, IL1β, TNFα and IL6, with a non signifficant decrease in CRP. In motor tests, the RAmice had a reduced distance traveled when compared to healthy mice (sham) (830±37cm vs 1393±187cm Sham, p<0.001, n=4-7), as well as a reduce strength (22.4±7g vs 44.4±3g Sham, p<0.05, n=4-7) and endurance, while the rotarod test showed a loss of motor coordination with increase of latency to fall(43.3±5.4sec vs 75.9±3.3sec Sham, p<0.05, n=4-7). Dipyridamole treatment resulted in a revertion of physical development induced by serum transfer. Furthermore, RA mice had decreased lean mass, BMD and BMC, as well as an increased fat percentage, that were reverted in the presence of dipyridamole. RA mice muscle weights decreased when compared to sham mice, whereas dipyridamole reversed this effect. MHC protein expression was decreased in RA mice when compared to sham mice (60±7% vs 100% Sham, p<0.005, n=4-7) and reverted by dipyridamole (184±6%vs 60±7%RA mice, p<0.005,n=6-7), meanwhile PAX7 expression was enhanced by dipyridamole (274±11%dipyridamole,151±13% RA mice vs. 100%, p<0.005, n=6-7). AMPK activation decreased in RA mice (53±7% decreased vs Sham, p<0.05, n=4-7), whereas dipyridamole reversed this loss (152±5% dipyridamole vs 53±7% RA mice, p<0.001,n=6-7). Adenosine A2A and A2B receptors protein expression were decreased in RA mice (71±3% for A2A and 35±9% for A2B vs 100% Sham, p<0.005,n=4-7), been reverted by dipyridamole. Senescence markers p21and p16 were increased in RA mice (221±38% for p21 and 392±25% for p16 vs 100% Sham, p<0.001,n=4-7) and dipyridamole reduced their expression.ConclusionArthritic mice developed sarcopenia accompanied by a loss of motor activity, strong systemic inflammation and an increased muscle senescence. Dipyridamole counteracted both systemic and joint inflammation as well as muscle loss, enhancing muscle regeneration. This indicate that the use of agents that increase extracellular adenosine levels might be interesting as a therapeutically approach forinflammatory sarcopenia.AcknowledgementsThis work was supported by grants from Instituto de Salud Carlos III through the “Miguel Servet” program (CP15/00053, CPII20/00017), co-funded by Fondo Europeo de Desarrollo Regional (FEDER) and research grant from the Spanish Instituto de Salud Carlos III (PI19/00744).Disclosure of InterestsMiguel Marco-Bonilla: None declared, Maria Fresnadillo: None declared, Irene Sanchez: None declared, Raquel Largo Grant/research support from: Pfizer and ABF pharmaceuticals, Gabriel Herrero-Beaumont Grant/research support from: Pfizer, Aranzazu Mediero: None declared.