Single-cell transcriptomic and m6A methylation analysis reveals platelet-mediated immune regulatory mechanisms in sepsis

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. Overall design: This study utilized the publicly available scRNA-seq dataset GSE167363, which includes peripheral blood mononuclear cell (PBMC) samples from 10 patients with Gram-negative sepsis (survivor group: n = 6; non-survivor group: n = 4) and 2 healthy controls (HCs). Additionally,PBMCs from six sepsis patients (survivor group: n = 3; non-survivor group: n = 3), recruited from the Department of Emergency Medicine, Tianjin Medical University General Hospital, were used for m6A methylation sequencing.