Single-cell transcriptomic and m6A methylation analyses reveal platelet-mediated immune regulatory mechanisms in sepsis

Weiwei Qian¹Yuanyuan Liu¹Xinyang Zhao²Yuxin Dong¹Zhou Jian³Songtao Shou^1*

• ¹Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, China
• ²Medical Records and Statistics Department, Tianjin Medical University General Hospital, Tianjin, China
• ³Department of Immunology, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China

Sepsis is a life-threatening syndrome characterized by a dysregulated host response to infection and systemic inflammation, with a highly heterogeneous and complex immunopathology. Immune imbalance plays a central role in its progression. In recent years, the immunomodulatory functions of platelets have garnered increasing attention, revealing roles beyond their classical functions in hemostasis and thrombosis. Concurrently, N6-methyladenosine (m6A)-the most prevalent internal modification in eukaryotic mRNA-has been implicated in the regulation of immune responses and cell fate decisions. However, its role in sepsis remains poorly understood. In this study, we integrated single-cell RNA sequencing (scRNA-seq) data from the GSE167363 dataset and m6A methylome profiles of peripheral blood mononuclear cells (PBMCs) from sepsis patients. Then, a comprehensive analysis of immune cell composition, developmental trajectories, intercellular communication, and epigenetic modifications across healthy controls, survivors, and non-survivors was conducted. Our findings revealed a progressive enrichment of platelets during sepsis progression, along with a potential phenotypic reprogramming of B cells, T cells, and Tregs toward platelet-like characteristics.Cell-cell communication analysis showed an overall weakening of immune cell interactions with disease severity, most notably a marked attenuation of the APP-CD74 signaling axis between platelets and B cells, suggesting impaired immune network coordination. m6A profiling further revealed the remodeling of m6A peaks and dysregulation of m6A-related enzymes in the nonsurvivor group. Through integrative analysis, we identified RPA1 as a key m6A-modified target gene highly correlated with APP expression and under the co-regulation of multiple m6A regulators.Collectively, our study uncovers disrupted immune cell communication, functional reprogramming of platelets, and a potential m6A-dependent regulatory mechanism in sepsis. These findings provide