Matrix Rigidity Mechanoprimes Microglia for Inflammation Through Cytoskeletal-to-Nuclear Signaling and 3D Spatio-Epigenomic Remodeling.

Microglia play a pivotal role in modulating the pathophysiology of the central nervous system, including disease progression and injury repair. While the biochemical factors governing microglial activation are well understood, the impact of biophysical cues, such as extracellular matrix (ECM) mechanics, remains largely unexplored. Here, we demonstrate how matrix rigidity mechanoprimes microglia for inflammation through coordinated cytoskeletal-to-nuclear signaling and 3D spatio-epigenomic remodeling. In response to rigid matrices, microglia undergo progressive actin cytoskeletal remodeling, morphological adaptation, and nuclear deformation. ATAC-seq reveals that rigidity redistributes rather than globally increases chromatin accessibility: most differentially accessible regions lose accessibility, whereas a defined subset gains focal accessibility at inflammation-associated loci, establishing a permissive state for subsequent activation. Upon LPS challenge, rigidity amplifies inflammatory responses through NF-κB activation and cytoskeleton-dependent MRTF-A nuclear translocation. Integrating ChIP-seq and Hi-C identifies rigidity-responsive cis-regulatory elements (mechanoCREs) and shows that rigidity promotes long-range chromatin interactions linking distal mechanoCREs to inflammatory genes. Together, these findings establish ECM rigidity as a key regulator of microglial inflammation by coupling actin-mediated mechanotransduction to chromatin accessibility and higher-order genome organization, providing a mechanistic basis for mechanically amplified neuroinflammation.