Transcriptional profiles in human milk and whole blood after live attenuated and inactivated influenza vaccination

Breastfeeding protects against mucosal infections in infants. The underlying mechanisms through which immunity develops in human milk following maternal infection with mucosal pathogens are not well understood. We simulate mucosal influenza infection through live attenuated influenza vaccination (LAIV) and compared milk and blood immune responses to inactivated influenza vaccination (IIV). Transcriptomic analysis was performed on RNA extracted from human milk and whole blood. Differentially expressed genes (DEGs) and gene set enrichment analysis (GSEA) on days 1 and 7 post-vaccination were compared to pre-vaccination. We enrolled 78 (361 samples) lactating women during the months of influenza vaccine availability from 2011 to 2016. The mothers were post-partum for a median of 7.5 days at the time of influenza vaccination. None had received a prenatal influenza vaccine during the influenza season of participation until study enrollment. Gene expression profiles from blood (132 samples) and human milk (229 samples) were performed before (day 0) and day 1 and day 7 after vaccination. Influenza HA-specific HAI titers (sera) and IgA (milk) were evaluated at days 0, 30, 90, and 180.