STUDY OF THE DENDRITIC CELLS DURING THE AGING AND IN HTLV-1 INFECTION IN MICE

Introduction: Immunosenescence changes the cellular profile and functionality of the immune system during aging. Chronic viral infections may contribute to an immunosenescent state (Signal Transduct Target Ther. (2024)7(1):391, 2022). Infection with the human T-cell lymphotropic virus type 1 (HTLV-1) is related to a chronic inflammatory demyelinating disease. However, the effects of immunosenescence on the course of HTLV-1 infection are poorly known. Dendritic cells (DCs) are essential for antiviral responses, and a significant decrease in circulating DCs was detected during the aging (Hum Immunol. (2024)70(10):777, 2009). Thus, we aimed to explore the functional changes in DCs subsets caused by senescence, and its impacts on HTLV-1-associated diseases. Methods and Results: Spleen bone marrow and blood cells from C57BL/6J mice were stained by flow cytometry in order to compare frequency and activation status of DCs in young and aged mice (CEUA: 090/24). Preliminary results showed a lower percentage of DCs in elderly mice spleen and bone marrow cells. In contrast, expression of MCH-II was increased in splenic DCs of aged mice compared to young ones. Blood circulating DCs were comparable in numbers and activation markers between the young and aged group. Additionally, young Balb/C mice were infected with MT-2 cells (HTLV-1 lineage) (CEUA: 080/24). Spleen cells were stained by flow cytometry to compare the frequency and activation of DCs in chronic infection. We observed lower percentage of DCs in infected mice’s splenocytes compared to non-infected ones. Furthermore, we observed higher percentage of activation markers, like CD80. Conclusion: Together these results indicate a reduction in the frequency of DCs both in the spleen of elderly mice and of mice infected with HTLV-1, which causes chronic infection. In contrast, DCs display higher levels of activation markers. These findings will shed light into the phenotype of senescent DCs.