Comprehensive single-cell analysis deciphered the immunoregulatory mechanism of TPPU in alleviating sepsis-related acute liver injury

Introduction: Sepsis-related acute liver injury involves complex immune dysfunctions. Epoxyeicosatrienoic acids (EETs), bioactive molecules derived from arachidonic acid (AA) via cytochrome P450 (CYP450) and rapidly hydrolyzed by soluble epoxide hydrolase (sEH), possess anti-inflammatory properties. Nevertheless, the impact of the sEH inhibitor TPPU on sepsis-related acute liver injury remains uncertain. Objectives: This study utilized comprehensive single-cell analysis to investigate the immunoregulatory mechanism of TPPU in alleviating sepsis-related acute liver injury. Methods: Hepatic bulk RNA sequencing and proteomics analyses were employed to investigate the mechanisms underlying sepsis-related acute liver injury induced by cecal ligation and puncture in mice. Cytometry by time-of-flight and single-cell RNA sequencing were conducted to thoroughly examine the immunoregulatory role of TPPU at single-cell resolution. Results: Downregulation of AA metabolism and the CYP450 pathway was observed during sepsis-related acute liver injury, and TPPU treatment reduced inflammatory cytokine production and mitigated sepsis-related hepatic inflammatory injury. Comprehensive single-cell analysis revealed that TPPU promotes the expansion of anti-inflammatory CD206+CD73+ M2-like macrophages and PDL1-CD39-CCR2+ neutrophils, reprogramming liver neutrophils to an anti-inflammatory CAMP+NGP+CD177+ phenotype. Additionally, TPPU inhibits the CCL6-CCR1 signaling mediated by M2-like macrophages and CAMP+NGP+CD177+ neutrophils, altering intercellular communication within the septic liver immune microenvironment. Conclusion: This study demonstrated TPPU's protective efficacy against sepsis-related acute liver injury, underscoring its vital role in modulating liver macrophages and neutrophils and enhancing prospects for personalized immunomodulatory therapy.