Murine Neonatal Monocytes and Neutrophils Show Distinct Toll-Like Receptor Patterns at Baseline and during Influenza Infection

Introduction: Neonatal antiviral responses differ significantly from those of adults contributing to increased disease severity. Differences in Toll-like receptor (TLR) expression levels at baseline and in response to influenza may contribute to variations in viral clearance and pathogenesis. Method: Our study examined TLR expression differences during influenza infection between neonatal (5 days old) and adult mice (8–16 weeks old) by analysis of RNA sequencing of monocytes and neutrophils. Results: We found that neonatal mouse cells exhibited lower baseline TLR expression and decreased TLR upregulation in response to influenza compared to adult cells. Conclusion: Our research raises the question of whether the lower TLR expression affects neonatal vulnerability to influenza and sets the stage for future studies on TLR biology in the young.