A Novel Single Cell RNA-seq Analysis of Circulating Immune Cells in Late Sepsis

With the successful implementation of guidelines from the Surviving Sepsis Campaign, in-hospital mortality to sepsis continues to decrease. However, this is has not lead to completely improved outcomes after sepsis. Up to 1/3 of sepsis survivors continue to have dismal long-term outcomes and 1-year mortality. Although the pathobiology of the dismal outcomes after sepsis remains undefined, it is thought that late after sepsis individuals enter a state of pathologic myeloid activation, inducing suboptimal lymphopoiesis and erythropoiesis, with many of the downstream immune cells being dysfunctional. The goal of this study was to use single-cell RNA sequencing to perform a detailed transcriptomic analysis of non-myeloid cells to better understand the pathology of late sepsis. Our findings highlight the unique transcriptomic pattern that circulating non-myeloid cells display 14 days after sepsis. Non-myeloid leukocytes in particular reveal an endotype of inflammation, immunosuppression and dysfunction. Immunomodulatory therapies at this late time point in sepsis may be feasible through precision medicine. A mixture of whole blood myeloid-enriched and Ficoll-enriched peripheral blood mononuclear cells from four late septic patients (post-sepsis day 14-21, RAP n=1 and CCI n=3) and five healthy subjects underwent Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq).

随着拯救脓毒症运动（Surviving Sepsis Campaign）指南的成功落地，脓毒症患者的院内死亡率持续下降。然而这并未完全改善脓毒症患者的远期预后：多达三分之一的脓毒症幸存者仍面临极差的长期结局与1年死亡率。尽管脓毒症后不良预后的病理生物学机制仍未明确，但学界认为脓毒症后期个体将进入病理性髓系激活状态，引发淋巴细胞生成与红细胞生成功能低下，且大量下游免疫细胞出现功能失调。本研究旨在通过单细胞RNA测序（single-cell RNA sequencing）对非髓系细胞开展详细的转录组分析，以深入阐明脓毒症后期的病理机制。本研究结果揭示了脓毒症后14天时循环非髓系细胞所呈现的独特转录组特征，尤其是非髓系白细胞，其炎症、免疫抑制与功能失调的免疫内型（endotype）特征显著。在此脓毒症后期节点，基于精准医学的免疫调节治疗或具备可行性。本研究采集了4名脓毒症后期患者（脓毒症后14~21天，其中RAP 1例、CCI 3例）与5名健康受试者的样本，将全血髓系富集组分与菲科（Ficoll）富集的外周血单个核细胞混合后，开展了转录组与表位测序细胞索引技术（Cellular Indexing of Transcriptomes and Epitopes by Sequencing，CITE-seq）检测。