Characteristics of CD103+CD8+ T Cells in the Spleen of Plasmodium yoelii NSM-Infected Mice

Xingfei Pan^1*Feihu Shi^1,2Shanni Tang¹Meilin Liu¹Li Pan¹Guikuan Liang²Lu Li²Hongyan Xie²Shan Zhao^2*Jun Huang^2*

• ¹The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
• ²Guangzhou Medical University, Guangzhou, China

Background: CD8⁺ T cells play a critical role in controlling Plasmodium infection. CD103, an integrin composed of αE and β7 subunits, is widely recognized as a cell surface marker for tissue-resident memory T cells (TRM) and tumor-infiltrating lymphocytes (TIL). Methods: In this study, a Plasmodium infection model was constructed by intraperitoneally injecting 106 infected red blood cells (iRBCs) into C57BL/6 mice. CD45+ cells in the spleen of naive and infected mice were sorted and subjected to single-cell RNA sequencing (scRNA-seq). Content, activation, and function of CD103+CD8+ T cells were detected by flow cytometry. qPCR and dual-luciferase reporter assays were performed to find the key transcription factor. Results: Here, we identified a substantial subset of CD103⁺CD8⁺ T cells in the spleen of naive mice, whose proportion and count declined rapidly following Plasmodium yoelii NSM infection. Compared to CD103⁻CD8⁺ T cells, both in naive and infected mice, CD103⁺CD8⁺ T cells exhibited higher CD62L expression, lower levels of CD44, CD69, and TIGIT, and rarely secreted IFN-γ or granzyme B upon PI stimulation. Single-cell RNA sequencing revealed that differentially expressed genes (DEG) were enriched in pathways related to "cytoplasmic translation" and "ribosome biosynthesis", suggesting these cells are in a pre-activation preparatory state. Bioinformatics predictions and dual-luciferase reporter assays indicated that the transcription factor LEF1 might regulate Itgae transcription by binding to its promoter sequence. Conclusions: Collectively, our findings demonstrate that splenic CD103⁺CD8⁺ T cells express fewer activation and function-associated molecules, which may contribute to their limited role in the course of Plasmodium yoelii NSM infection in C57BL/6 mice, and implicates LEF1 in the regulation of CD103 expression.