Gene expression profiling in pediatric meningococcal sepsis reveals dynamic changes in NK-cell and cytotoxic molecules

Objective. Meningococcal sepsis remains an important cause of childhood morbidity and mortality. Largely due to logistic complexities of research in young children with acute life-threatening disease, very little is known regarding differential expression kinetics and molecular regulation of immune response genes in leukocyte subsets. Materials and methods. In this prospective case-control study, six children with meningococcal sepsis were included. Blood was drawn at four time points (t=0, t=8, t=24 and t=72 h after admission to the paediatric intensive care unit). Blood was also collected from matched controls. Detailed immunophenotyping of leukocytes was performed; RNA isolated from whole blood, lymphocytes, monocytes, and granulocytes was used to perform Affymetrix micro-array gene expression analysis. Results and conclusion. There were no differences in total leukocyte count between patients and controls. In contrast to previous in vitro studies we observed an unexpected decrease in NK cell numbers, as well as downregulation of NK cell specific and cytotoxic T-cell related gene expression in patients with meningococcal septic shock. By contrast, expression of genes, involved in innate immunity and several other pathways, differed between the different leukocyte subpopulations in a dynamic fashion. Compared to previously reported gene expression profiles, it was possible to define a meningococcal sepsis specific expression profile. In this prospective case-control study, six children with meningococcal sepsis were included. Blood was drawn at four time points (t=0, t=8, t=24 and t=72 h after admission to the paediatric intensive care unit). Blood was also collected from matched controls. Detailed immunophenotyping of leukocytes was performed; RNA isolated from whole blood, lymphocytes, monocytes, and granulocytes was used to perform Affymetrix micro-array gene expression analysis. No replicates were performed. Table 4. Results of between-subject analyses. Source Time (h) ca co/ca at t=T Blood t0: ca:2 3, co: a b c; t8: 2; t24 :ca:1 2 3; t72: ca:1 2. Lym t0: ca:2 3, co:a b c d;t8: ca:1 3 4;t24: ca:1 2 3 4 6; t72: ca: 1 2. Mono t0:ca: 1 3 4 6, co: a b d; t8: ca:1 2 3; t24:ca: 1 2 3; t72: ca:1. Numbers represent the patient identification numbers. Characters represent the individual controls.