Mechanisms of epigenomic and functional convergence between glucocorticoid- and IL4-driven macrophage programming
Dinesh K. Deochand, Marija Dacic, Michael J. Bale, Andrew W. Daman, Vidyanath Chaudhary, Steven Z. Josefowicz, David J. Oliver, Yurii Chinenov, Inez Rogatsky
Abstract
Macrophages adopt distinct phenotypes in response to environmental cues, with type-2 cytokine interleukin-4 promoting a tissue-repair homeostatic state (M2IL4). Glucocorticoids (GC), widely used anti-inflammatory therapeutics, reportedly impart a similar phenotype (M2GC), but how such disparate pathways may functionally converge is unknown. We show using integrative functional genomics that M2IL4 and M2GC transcriptomes share a striking overlap mirrored by a shift in chromatin landscape in both common and signal-specific gene subsets. This core homeostatic program is enacted by transcriptional effectors KLF4 and the glucocorticoid receptor, whose genome-wide occupancy and actions are integrated in a stimulus-specific manner by the nuclear receptor cofactor GRIP1. Indeed, many of the M2IL4:M2GC-shared transcriptomic changes were GRIP1-dependent. Consistently, GRIP1 loss attenuated phagocytic activity of both populations in vitro and macrophage tissue-repair properties in the murine colitis model in vivo. These findings provide a mechanistic framework for homeostatic macrophage programming by distinct signals, to better inform anti-inflammatory drug design. IL4 and glucocorticoids elicit a homeostatic phenotype in macrophages. Here the authors show that these disparate stimuli yield converging epigenomic and transcriptomic changes, enacted by transcription factors KLF4 and the glucocorticoid receptor, and integrated by their shared coregulator GRIP1.