Characterization of Peripheral Blood Mononuclear Cells Gene Expression Profiles of PediatricStaphylococcus aureusPersistent and Non-Carriers Using a Targeted Assay

AbstractDefects in innate immunity affect many different physiologic systems and several studies of patients with primary immunodeficiency disorders demonstrated the importance of innate immune system components in disease prevention or colonization of bacterial pathogens. To assess the role of the innate immune system on nasal colonization withStaphylococcus aureus, innate immune responses in pediatricS. aureusnasal persistent carriers (n=15) and non-carriers (n=15) were profiled by analyzing co-clustered gene sets (modules) identified through large-scale transcriptome data analysis as the basis for the development of a targeted assay. We stimulated previously frozen peripheral blood mononuclear cells (PBMCs) from these subjects with i) a panel of TLR ligands, ii) liveS. aureus(either a mixture of strains or stimulation with respective carriage isolates), or iii) heat-killedS. aureus. We found no difference in responses between carriers and non-carriers when PBMCs were stimulated with a panel of TLR ligands. However, PBMCs stimulated with liveS. aureuselicited a significantly different response that also differed from the response elicited following stimulation with deadS. aureus. Furthermore, we observed a distinct stimulation profile for PBMCs isolated from persistent carriers stimulated with their respective live or dead carriage strains compared to responses observed for PBMCs isolated from non-carriers that were similar regardless of whether or not the bacteria were alive or not. These data suggested that innate pathway signaling is different between persistent and non-carriers ofS. aureus.