Modulatory effects of photobiomodulation combined with resistance exercise on lymph node response during rheumatoid arthritis induction in Wistar rats.

OBJECTIVE: This study aimed to evaluate the effects of resistance exercise associated with photobiomodulation on the popliteal lymph nodes of Wistar rats subjected to an acute-phase experimental model of rheumatoid arthritis. METHODS: The study consisted of 64 male Wistar rats divided into eight groups (n=8), including control, physical exercise, and photobiomodulation groups. The arthritis groups were subjected to an induction protocol using Complete Freund's Adjuvant and underwent an acute inflammatory period of 7 days, during which they received resistance exercise and photobiomodulation according to their respective group assignments. RESULTS: There was a significant increase in the total lymph node area of the groups subjected to rheumatoid arthritis induction. A reduction in the number of lymphocytes and plasma cells in the medullary cord, as well as macrophages in the medullary sinuses, was observed in the groups treated with both resistance exercise and photobiomodulation. Additionally, a reduction in lymphocytes and reticular cells was observed in the groups treated with photobiomodulation alone. CONCLUSION: Treatment with resistance exercise or photobiomodulation was effective in modulating the immune response in the popliteal lymph node during the acute stage of the disease; however, combined therapy did not provide additional benefits compared with either treatment alone.