Sérgio Honório, Priscila Barbosa Carvalho, Regiane Cristine de Souza Almeida, Allan Evangelista Alves Costa, Jacqueline de Fátima Jacysyn, Márcia Kiyomi Koike, Fernando Russo Costa do [UNIFESP] Bomfim, Edna Frasson de Souza Montero
Acute rejection remains a significant challenge in organ transplantation. Photobiomodulation (PBM) has demonstrated anti-inflammatory and regenerative properties, suggesting potential benefits in modulating immune responses. This study aimed to evaluate the effects of PBM on fetal intestinal transplantation in mice. The study was conducted in two phases. In the first phase, 77 mice were utilized to assess histological outcomes. Fetal intestines from pregnant C57BL/6 mice were transplanted into BALB/c recipients, forming allogeneic groups (ALLO-GTx) with or without PBM (ALLO-GTxPBM), and syngeneic controls (RG). PBM was applied transcutaneous at the graft site immediately post-surgery (660 nm, 40 J/cm², 1.5 J). Grafts were collected on postoperative days 3, 5, and 7 for hematoxylin-eosin staining and evaluated using Aubert's criteria. In the second phase, spleens from 30 transplanted mice were analyzed on day 7 via flow cytometry for lymphocyte activation markers (CD4+, CD8+, CD44, CD69, CD54, CD62L). PBM significantly reduced rejection scores on days 5 (3.5 [3-9] vs. 12 [10-13.8]; p = 0.0006) and 7 (p = 0.0096), and enhanced graft development (p = 0.0079). Flow cytometry revealed decreased activation of CD4 + CD44+CD69+ (9.08% to 3.15%) and CD8 + CD44+CD69+ (1.53% to 0.90%) T cells in PBM-treated animals. Additionally, lower expression levels of CD62L + and CD54 were observed, indicating immunomodulatory effects. PBM improved graft viability and mitigated acute rejection in fetal intestinal transplantation in mice. These findings support further investigation into PBM as a therapeutic strategy to modulate immune responses in transplantation.