Clinical and mechanistic relevance of high dimensionality analysis of the paediatric sepsis immunome

Dandan Pi¹Judith Ju Ming Wong^2,3*Katherine Nay Yaung³Nicholas Khoo³Su Li Poh³Martin Wasser³Pavanish Kumar³Thaschawee Arkachaisri²Feng Xu¹Herng Lee Tan²Yee Hui Mok²Joo Guan Yeo^2,3Salvatore Albani^2,3

• ¹Children‘s Hospital of Chongqing Medical University, Chongqing, Chongqing Municipality, China
• ²KK Women's and Children's Hospital, Singapore, Singapore
• ³Translational Immunology Institute, SingHealth Duke-NUS Global Health Institute, Singapore, Singapore

Background. By employing a high dimensionality approach, this study aims to identify mechanistically relevant cellular immune signatures that predict poor outcomes. Methods. This prospective study recruited 39 children with sepsis admitted to the intensive care unit and 19 healthy age-matched children. Peripheral blood mononuclear cells were studied with mass cytometry. Unique cell subsets were identified in the pediatric sepsis immunome and depicted with t-distributed Stochastic Neighbor Embedding (tSNE) plots. Network analysis was performed to quantify interactions between immune subsets. Enriched immune subsets were included in a model for distinguishing sepsis and validated by flow cytometry in an independent cohort. Results. The median (interquartile range) age and pediatric sequential organ failure assessment (pSOFA) score in this cohort was 5.6（2.0, 11.3） years and 8 (6, 11), respectively. High dimensionality analyses of the immunome in sepsis revealed a loss of coordinated communication between immune subsets, particularly, a loss of regulatory/inhibitory interaction between cell types, fewer interactions between cell subsets and fewer negatively correlated edges than controls. Four independent immune subsets (CD45RA-CX3CR1+CTLA4+CD4+ T cells, CD45RA-17A+CD4+ T cells CD15+CD14+ monocytes and Ki67+ B cells), were increased in sepsis and provide a predictive model for diagnosis with area under the Receiver Operating Characteristic curve, AUC 0.90 (95% confidence interval, CI 0.82-0.98) in the discovery cohort and AUC 0.94 (95% CI 0.83-1.00) in the validation cohort. Conclusion. The sepsis immunome is deranged with loss of regulatory/inhibitory interactions. Four immune subsets increased in sepsis could be used in a model for diagnosis and prediction of poor outcomes.