Immune System Response to Pediatric Respiratory Infections

Findings from the new study acute respiratory tract infections (ARTI) are the leading global cause of death in early childhood. Lower respiratory tract infections, including bronchiolitis and viral and bacterial pneumonia, take a toll on children's health and causing much of pediatric hospital admissions for infectious diseases. A better understanding of how early infections influence the long-term immune response has important implications for the diagnosis and treatment of young patients suffering from acute respiratory infections.

CD8 T cells prepare the body to fight off foreign viruses by altering its own gene expression after detecting alarm signals generated by cells in the lungs in response to pathogens of the acute respiratory tract. In this study, gene expression of CD8 T cells in pediatric patients with influenza-like illness was different from patients with other viral pathogens, such as rhinovirus. In general, the "genomic circuits" of cell clusters of genes similar to electrical circuits that affect the expression of each vary according to the type of pathogen.

Using blood samples of 29, the researchers found that different viruses specifically cause different immune responses; different patterns of genomic circuits in CD8 T cells. In addition, the researchers found that differences in the severity of ARF, asthma, sex and age also influence the immune response in an individual child. For example, the genetic circuits of CD8 T cells from younger children were different from those of older children, which correlated with whether the younger child was exposed to the flu virus or not at a younger age.

From the collected immune information, the team developed a Pediatric Inflammatory Signature (IPS) consisting of a small set of genes that consistently increased or decreased expression on CD8 T cells from patients with acute influenza infection. 

Researchers are optimistic that by combining the basic science of immune cell gene expression with the actual cases seen in a high volume pediatric ED, it will identify the key pathways involved in host-pathogen interactions and help improve treatments for children with severe flu symptoms.