Gene Expression Analysis in Critically Ill Patients

Abstract

Nosocomial infections are associated with increased morbidity and mortality in intensive care units (ICUs) and remain an important target for intervention. Several studies have explored bovine lactoferrin as a potential tool for preventing infection and modulating the immune response. One clinical trial, the PREVAIL study, investigated the efficacy of lactoferrin in preventing nosocomial infections in critically ill, mechanically ventilated patients. A subset of patients in this study had blood samples collected at up to 6 different time points during their stay in the ICU, which were used to extract RNA for gene expression profiling. The resulting gene expression data were analyzed to determine the impact of lactoferrin on gene expression. Differential expression analysis was performed using both a single-gene approach and weighted gene co-expression network analysis (WGCNA). A single-gene analysis revealed that there was an increased number of differentially expressed genes in the lactoferrin group at all time points, including genes associated with the inflammatory response. Results from WGCNA revealed that groups of genes associated with innate immunity and defence response to virus were significantly differentially expressed over time in the lactoferrin group. These results contribute to our understanding of critical illness at the molecular level and provide evidence that lactoferrin has a biological effect.