Secondary Analysis of Existing Datasets to Define the Neutrophil Transcriptomic Response to Parenchymal Damage - PROJECT SUMMARY/ABSTRACT Background: Multiple organ failure is associated with a persistent systemic inflammatory response. Neutrophils, the most abundant leukocytes in blood, are important effectors of this response. Our preliminary data identified gene expression changes in human neutrophils common to patients with 1) septic shock due to an intraparenchymal infectious source (such as pneumonia and abdominal abscess); and 2) sterile vasoplegic shock after major surgery requiring cardiopulmonary bypass. This included increased levels of genes important for leukocyte extravasation and migration through tissues. Importantly, these changes were not seen in neutrophils from patients with sepsis from primary bloodstream and urinary tract infections, that is, from patients without parenchymal injury. Similar changes have been reported in patients after traumatic injury. Hypothesis: We hypothesize that neutrophils responding to diverse inflammatory insults causing parenchymal damage display a common, pro-invasive gene expression program. Methods: In Aim 1, we will use existing whole-transcriptome RNA-seq human neutrophil data from our laboratory to define the gene expression signature common to septic shock with intraparenchymal source; multiple organ failure after major surgery; and traumatic injury. Upstream regulators of key gene modules will be investigated as well as relevant biological pathways. In Aim 2, we will validate the gene expression signature in secondary analysis of 11 published human neutrophil and leukocyte transcriptome datasets. These datasets include microarray, bulk RNAseq, and single cell RNAseq data from septic patients with intraparenchymal versus non-intraparenchymal source, surgical patients, and patients with traumatic injury. In both Aim 1 and Aim 2, we will compare differences in dynamic expression between patients who developed multiple organ failure, versus those who recovered without complications. Expected Results: We expect to identify and validate a targeted neutrophil gene expression program specific to parenchymal damage; to define the dynamic expression of this program in the development of multiple organ failure versus good recovery; and to identify candidate upstream regulators for future investigation. Impact and Long-Term Goals: This study will address current gaps in understanding of the specificity of the systemic inflammatory response and its relationship to multiple organ failure.
