Background: Rheumatoid arthritis (RA) confers a higher risk of several comorbidities including changes in body composition with reduced muscle mass and strength (sarcopenia) and with increased fat mass levels. It is well described that RA patients have insulin resistance, altered glucose and lipidic metabolism, a metabolic switch induced by the immune microenvironment of RA, both in immune cells and stromal cells, which leads to dysfunction and imbalance of immune homeostasis [1]. We have demonstrated that the use of dipyridamole (a compound which increases extracellular adenosine levels) prevents inflammation, fat mass gain, and muscle loss in KBx/N induced RA model, via adenosine A2B receptor activation. These changes in body composition suggest differences in energy manage as well as a metabolic reprogramming in muscle cells.

Objectives: Therefore, we aim to determine if dipyridamole prevents rheumatoid cachexia due to changes in muscle metabolism and mitochondrial dynamics.

Methods: 12-wk-old C57BL/6J male mice were injected with K/BxN serum (100 μl, intraperitoneal) on days 0 and 2. 25mg/kg/day dipyridamole was administered daily for 2 weeks. Insulin and glucose tests were performed on day 13. Mice were euthanized on day 14 (highest point of inflammation). Gastrocnemius was collected for mitochondrial biogenesis studies (TFAM, Nrf1, PGC1α), TMRM studies, Mitotracker, and lipid/glucose metabolism (CPT1, FABP3, PDK4), as well as expression of mitochondrial complexes. Tomm20, a mitochondrial control gene expressed in the outer membrane, was analyzed via western blot. Tibialis anterior was frozen and OCT embedded for oil red staining. C2C12 myoblast cells were treated with IL-6 2.5 µg/ml and dipyridamole 1µM, and protein and RNA were collected at 24h and 4 days of differentiation. The same proteins and genes studied in the in vivo model were analyzed.

Results: RA mice developed insulin resistance two weeks after serum administration that was prevented with the use of dipyridamole as well as the decrease in muscular Glut4. Concomitant with a decrease in glucose uptake, RA mice showed an accumulation of triglycerides in muscle fibers that was prevented in the presence of dipyridamole. Dipyridamole increased mitochondrial biogenesis gene expression (TFAM, Nrf1, PGC1α) and Tomm20 expression, in contrast to the low levels in RA mice. In addition, the fatty acids uptake by the mitochondria in RA mice was promoted, increasing CPT1 and FABP3 gene expression. Also, in RA mice energy production by glycolytic pathways was inhibited with an increase in PDK4 gene expression. In contrast, dipyridamole stimulated energy production by glucose and pyruvate. The expression of mitochondrial complexes II and V was decreased in RA group and dipyridamole prevented this situation. Similar results were observed in C2C12 cells. TMRM showed a decrease in mitochondrial membrane potential activity in cells treated with IL-6 that is recovered in the presence of dipyridamole. MitoTracker showed similar mitochondrial mass in all cases.

Conclusion: RA causes a metabolic switch, with insulin resistance and altered glucose control, translating fatty acids as the main source of energy in muscle. Treatment with dipyridamole prevented this metabolic state promoting glucose use.

REFERENCES: [1] Wei-Wei Cai, Yun Yu, Shi-Ye Zong, Fang Wei. Metabolic reprogramming as a key regulator in the pathogenesis of rheumatoid arthritis. Inflamm Res 2020 Nov;69(11):1087-1101. doi: 10.1007/s00011-020-01391-5.

Acknowledgements: This study was performed in the Bone and Joint Research Unit of the IIS-Fundación Jiménez Díaz. This work was supported by grants from Instituto de Salud Carlos III through the “Miguel Servet” program (CP15/00053, CPII20/00017) co-funded by Union Europea, and a research grant from the Spanish Instituto de Salud Carlos III (PI19/00744, PI22/00347) and RICOR-RD21/0002/0025.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.