Characterization of Peripheral Blood Mononuclear Cells Gene Expression Profiles of Pediatric Staphylococcus aureus Persistent and Non-Carriers

Defects 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 with Staphylococcus aureus, innate immune responses in pediatric S. aureus nasal persistent carriers (n=3) and non-carriers (n=3) were profiled by RNAseq. We stimulated previously frozen peripheral blood mononuclear cells (PBMCs) from these subjects with i) live S. aureus (a mixture of all carriage isolates), or ii) heat-killed S. aureus.PBMC gene expression profiles differed between persistent and non-S. aureus carriers following stimulation with either live or dead S. aureus. These observations suggest that individuals susceptible to persistent carriage with S. aureus may possess differences in their live/dead bacteria recognition pathway and that innate pathway signaling is different between persistent and non-carriers of S. aureus. Pediatric patients from the Northwest Assistance Ministries Clinic, Houston, TX, were eligible for participation in the current study if they were participants of a prior parent study investigating pediatric S. aureus nasal carriage (n=438). In the parent study (unpublished results), we established nasal carriage phenotypes (persistent, intermittent, or non-carriers) based on the identification of S. aureus on 2 consecutive nasal swabs collected 12-17 days apart. Participants in the parent study testing positive for S. aureus on both swabs were classified as persistent carriers. Non-carriers were S. aureus negative at both time points. PBMCs from pediatric S. aureus nasal persistent carriers (n =3, age 4 (M), 5 (F), and 10 (F) years) and non-carriers (n=3, age 2 (F), 4(M), and 11(F)),