Efeito comparativo entre a terapia de fotobiomodulação local e vascular no processo inflamatório e no controle da dor, em modelo experimental de artrite reumatóide induzida

Abstract

Rheumatoid arthritis (RA) is classified as a chronic, autoimmune inflammatory disease with degenerative action on synovial joints, irreversibly destroying bone and cartilage. Locally applied photobiomodulation (LPBM) on the joint has shown a positive effect in controlling the inflammatory process, preventing its degradation and promoting tissue repair. However, there is a scarcity of studies using vascular photobiomodulation (VPBM) in the treatment of joint diseases. The aim of this study was to compare the effects of LPBM and VPBM therapy on the inflammatory process, through tissue organization by the total proportion of collagen and its relationship with mechanical resistance in pain control through allodynia, in an experimental model of induced RA. Methodology: 28 male, aged Wistar rats were distributed into 4 groups: Without RA (CTL) or with RA, without treatment (NT) or treated with PBM in the knee (LPBM) or in the caudal artery, for systemic effect (VPBM). The RA was induced through injections of Type II Collagen and Freud's adjuvant, at 3 different times and locations (2 intradermal injections at the base of the tail and back, and 1 intra-articular injection in both knees). The animals were treated twice a week for 21 days with PBM at the following parameters, LPBM: 808nm; 4 J/cm2; 100mW and VPBM: 808nm; 15 J/cm2; 100mW). Mechanical allodynia was performed once a week. At the end of treatment, the animals were euthanized, and the cartilage was recovered and stored for biomechanical and histological analyses. Results: All RA groups showed reduced resistance and deformation capacity (p<0.001) compared to the conventional collagen group (CTL). Both the LPBM and VPBM groups increased deformation capacity compared to the non-tissue (NT) group and maintained the proportion of total collagen compared to the CTL group (p<0.01). The VPBM group was the only one to show improvement in mechanical allodynia at all experimental times, while the LPBM group showed only temporary improvement compared to the NT group (p<0.01). Conclusion: Locally or vascularly irradiated PBM promotes maintenance of collagen ratio with improved tissue deformation capacity. VPBM also promotes a more consistent improvement in mechanical allodynia.