NFATc1 regulates LAG3+CD8+ T cells in the spleen of mice infected with Plasmodium yoelii NSM.

Malaria, an infectious disease caused by Plasmodium, is primarily characterized by anemia and splenomegaly. CD8 ⁺ T cells are known to play a key role in anti-malaria immunity. Lymphocyte Activation Gene 3 (LAG3), a critical immune checkpoint molecule, is pivotal in CD8 ⁺ T cell-mediated anti-tumor responses. However, the role of LAG3 ⁺ CD8 ⁺ T cells in anti-malarial immunity and the regulatory factors governing LAG3 expression in CD8 ⁺ T cells remain unclear. In this study, C57BL/6 mice were subcutaneously infected with Plasmodium yoelii NSM. Splenic lymphocytes were isolated and analyzed using flow cytometry (FACs) and single-cell RNA sequencing (scRNA-seq). Results showed a significant upregulation of LAG3 expression in splenic CD8 ⁺ T cells post-infection. These LAG3 ⁺ CD8 ⁺ T cells displayed enhanced activation, responsiveness, proliferative capacity, and cytokine production. Additionally, activated nuclear factor of activated T cells 1 (NFATc1) was found to co-express with LAG3 in splenic CD8 ⁺ T cells from infected mice. Dual-fluorescence reporter gene assays in 293T cells identified NFATc1 as a key transcription factor that binds to the LAG3 promoter sequence. Knockdown of NFATc1 via small interfering RNA (siRNA) reduced LAG3 expression. In conclusion, our findings suggest that splenic LAG3 ⁺ CD8 ⁺ T cells in Plasmodium yoelii NSM-infected C57BL/6 mice display enhanced functionality and imply that NFATc1 could positively regulate LAG3 expression.