Cell Specific Expression & Pathway Analyses Reveal Novel Alterations in Trauma-Related Human T-Cell & Monocyte Pathways

Monitoring genome-wide, cell-specific responses to human disease, although challenging, holds great promise for medicine’s future. Patients with injury severe enough to develop multiple organ dysfunction syndrome (MODS) are known to have multiple immune derangements, including T-cell apoptosis and anergy combined with depressed monocyte antigen presentation. Genome-wide expression analysis of highly-enriched circulating leukocyte subpopulations, combined with cell-specific pathway analyses, offers a previously unavailable opportunity to discover novel leukocyte regulatory networks in critically injured patients. Severe injury induced significant changes in the T-cell, monocyte, and total leukocyte transcriptome, with only 12% of these genomic changes common to all three cell populations. T-cell-specific pathway analyses identified increased gene expression of several novel inhibitory receptors (PD-1, CD152, NRP-1, Lag3), and concomitant decreases in stimulatory receptors (CD28, CD4, IL-2Ralpha). Functional analysis of T-cells and monocytes confirmed reduced T-cell proliferation and increased cell surface expression of negative signaling receptors paired with decreased monocyte costimulation ligands. Thus, genome-wide expression from highly-enriched cell populations combined with knowledge-based pathway analyses leads to the identification of novel regulatory networks differentially expressed in injured patients. Importantly, application of cell separation, genome-wide expression, and cell specific pathway analyses can be used to discover novel pathway alterations in human disease. Keywords: Gene expression profiling of circulating total blood leukocytes, T-Cells, and Monocytes in severe trauma patients and healthy subjects. Type of experiment: Gene expression profiling of circulating total blood leukocytes, T-Cells, and Monocytes in severe trauma patients and healthy subjects. Experimental factors: Healthy subjects, 7 severely traumatized patients and 7 healthy subjects for transcriptome analysis. Venous blood samples were collected. Total blood leukocytes were isolated, and T-cell and monocyte populations were obtained from two subsequent aliquots of the leukocytes. Total leukocytes, enriched T-cells, and enriched monocytes were analyzed using Affymetrix GeneChip arrays. Number of hybridizations: 42 Human U133A GeneChip arrays (Affymetrix)