Remodeling of Histone 3 Lysine 18 lactylation (H3K18lac) in monocytes-to-macrophage differentiation and induction of Trained Immunity by BCG in vitro

Trained immunity is the phenomenon whereby innate immune cells such as monocytes or macrophages undergo functional reprogramming after exposure to certain microbial components, altering their responses to future exposures. This study profiled the distribution of the active histone modification (H3K18lac) in human monocytes responding to the BCG vaccine and during monocyte-to-macrophage differentiation. Overall design: Human monocytes from 3 donors were differentiated to naive or trained macrophages. Primary human monocytes were differentiated to macrophages after a 6 days in vitro culture.Trained immunity was induced by initial exposure of primary human monocytes to BCG vaccine for 24 hours, followed by removal of stimulus and differentiation to macrophages for an additional 5 days. Cells were fixed for chromatin collection at baseline (day 0), 24 hours, and 6 days.