H3K27me3 modulates trained immunity of monocytes in HDM-allergic diseases

Monocytes have been confirmed to increase in persistently food-allergic children. A phenomenon of innate immune memory, called trained immunity, has also been observed in monocytes from allergic children. However, the underlying mechanism remains poorly understood.

We enrolled a cohort of HDM-allergic children alongside age-matched healthy controls and established an HDM-sensitized allergic mouse model. Flow cytometric analyses were conducted to quantify monocyte frequencies in clinical cohorts and experimental animals. We performed integrated transcriptomic profiling via RNA-seq combined with chromatin occupancy analysis using CUT&Tag technology in parallel human and murine samples to elucidate the molecular mechanisms.

In our study, we demonstrated a reduced H3K27me3 methylation level accompanied by an increased proportion and a proinflammatory transcriptional memory in monocytes from house dust mite (HDM)-allergic human subjects. The same transcriptional and epigenetic phenotype was also confirmed in HDM-sensitized mice. Finally, the administration of GSK-J4, which upregulates H3K27me3 level in murine monocytes, attenuated the inflammatory response in vitro and in vivo.

Our study confirms that H3K27me3 methylation modulates the trained immunity in monocytes and regulates HDM-allergic diseases through an inflammatory-dependent mechanism.