GDF3 promotes adipose tissue macrophage-mediated inflammation via altered chromatin accessibility during aging

Aging is characterized by amplified inflammation, including proinflammatory macrophages and increased susceptibility to endotoxemia. Here we uncover a mechanism by which macrophages maintain their inflammatory phenotype through autocrine GDF3-SMAD2/3 signaling, which ultimately exacerbates endotoxemia. We show that inflammatory adipose tissue macrophages display an age-dependent increase in GDF3, a TGFβ-family cytokine. Lifelong systemic or myeloid-specific Gdf3 deletion leads to reduced endotoxic inflammation. Using pharmacological interventions to modulate the GDF3-SMAD2/3 axis, we demonstrate its role in regulating the inflammatory adipose tissue macrophage phenotype and endotoxemia lethality in old mice. Mechanistically, single-cell RNA sequencing and assay for transposase-accessible chromatin with sequencing analyses suggest that GDF3 induces a shift toward an inflammatory state by limiting methylation-dependent chromatin compaction. Leveraging human adipose tissue samples and 11,084 participants from the atherosclerosis risk in communities study, we validate the relevance of GDF3 to aging in humans. These findings position the GDF3-SMAD2/3 axis as a critical driver of age-associated chromatin remodeling and a promising therapeutic target for mitigating macrophage-related inflammation in aging.