Epigenetic profiling reveals M1 macrophages as the primary drivers of trained immunity in HSV-1 latently infected mice.

Authors

Ujjaldeep Jaggi, Shaohui Wang, Homayon Ghiasi

Published in

PLoS pathogens. Volume 22. Issue 9. Pages e1014598. Sep 09, 2026. Epub Sep 09, 2026.

Abstract

Macrophages play multifaceted and critical roles in controlling diverse pathogenic infections. Building on our recently published observations of macrophages exhibiting memory responses to HSV-1 infection, our current report investigates the macrophage subtype responsible for generating trained immunity against virus-induced immunopathogenesis. Using ATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing), an epigenetic profiling technique, we identified chromatin accessibility changes in both M1 and M2 macrophages associated with the acquisition of IRGM1, a marker of the trained phenotype. To conduct this study, we first generated M0, M1, and M2 macrophage subtypes from bone marrow (BM) derived macrophages isolated from HSV-1 latently infected wild type (WT) mice. ATAC-seq revealed that M1-generated macrophages displayed higher IRGM1-associated chromatin accessibility peaks compared to M2 and M0 subtypes, and this response was enhanced after stimulation with UV-inactivated virus. To further dissect this response, we analyzed memory responses in bone marrow-derived macrophages, spleen macrophages, corneal macrophages, and trigeminal ganglia (TG) of latently infected M1 and M2 macrophages. Flow cytometry and ATAC-seq data showed a significantly higher proportion of IRGM1 ⁺ macrophages in infected M2-/- mice, which are enriched in M1 macrophages. These findings indicate that M1 macrophages, but not M2 macrophages, undergo trained immunity in response to HSV-1 infection. This is also confirmed by the Luminex assay, in which M1 macrophages, after stimulation, then known as primed M1 macrophages, enhance the secretion of pro-inflammatory cytokine/chemokine response to secondary HSV-1 exposure. These results uncover a previously underappreciated role for macrophage-mediated trained immunity in antiviral defense against HSV-1 infection and offer new insights into potential therapeutic targets for modulating host immune responses during HSV-1 infection.

PMID:
42715287
Bibliographic data and abstract were imported from PubMed on 10 Sep 2026.

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