95: Epigenetic Mechanisms of Glial Biomechanics and Extracellular Matrix Regulation

Topic: Basic Science
Subtopic: Non-specific to any diagnosis (including studies in healthy animals), Genetics and Epigenetics, Animal imaging (includes Ca2+ imaging, fluorescence microscopy)

Background and Aims: Cellular dynamics are shaped by the extracellular matrix (ECM), yet its role in sustaining chronic pain remains poorly understood. Microglia are "educated" by their environment to undergo lasting molecular adaptations; when dysregulated, they drive persistent inflammatory states. While these shifts are governed by epigenetic mechanisms, specifically histone post-translational modifications (PTMs), the biomechanical crosstalk between the ECM and glia remains a critical gap. We hypothesize that microglia cultured on varying substrate rigidities develop distinct epigenetic profiles. These states are predicted to directly regulate gene expression patterns involved in microglial inflammatory responses and synaptic remodeling in chronic pain.

Methods: To explore this, BV2 cells were cultured on collagen-coated PDMS substrates of varying stiffness (0.2, 2.0, 8, 16, 32, and 64 kPa). Phalloidin staining visualized actin organization as an indicator of cytoskeletal states influenced by chromatin regulation. Mass spectrometry of histone PTMs identified stiffness-dependent shifts, including H3K79me (transcriptional activation), H3K36ac (enhancer activity), H3K122ac (DNA damage), H1K25me (chromatin compaction), and rare modifications H3R49me and H3Q55me, indicating lasting chromatin alterations. Additionally, ELISA assays were used to quantify key microglial factors: heparanase (ECM remodeling), furin (protease activation), cathepsin S (immunomodulation), TNF-α (inflammation), and BDNF (neuroprotection). Data for ELISA targets are currently pending.

Results: Mass spectrometry revealed that increased ECM rigidity drives a distinct shift in the microglial histone code. We observed a pronounced increase in acetylation marks associated with transcriptional activation, specifically H3.1K36ac, H2BK120ac, H3K64ac, and H3K79ac. Parallel changes in methylation included enriched H3K79me2 and repressive H1.4K25me, alongside rare core modifications H3R49me2 and H3Q55me1. These data suggest that "mechanical memory" is encoded via a balance of activating acetyl-groups and repressive methyl-groups. ChIP-seq and ELISA assays are currently being completed to validate these epigenetic shifts and their impact on the secretion of functional factors like heparanase and cathepsin S.

Conclusions: This work establishes that ECM rigidity drives stiffness-dependent PTM remodeling, directly linking the brain’s physical scaffold to the epigenetic persistence of pain. By showing how the biomechanical environment stabilizes pathological microglial phenotypes, we identify the matrix-glial interface as a novel therapeutic target. These findings suggest that reversing "mechanical memories" at the epigenetic level could disrupt the maintenance of chronic pain. Future research will map this mechanome through DNA methylome sequencing and additional mechanotransduction pathways, providing a deeper understanding of how structural changes in the ECM encode the molecular blueprint for chronic pain.

References: 1. Nimmerjahn A, Kirchhoff F, Helmchen F. Resting microglial cells are highly dynamic surveillants of brain parenchyma in vivo. Science. 2005 May 27;308(5726):1314-8. doi: 10.1126/science.1110647. Epub 2005 Apr 14. PMID: 15831717.
2. Melo, P., Socodato, R., Silveira, M. S., Neves, M. A. D., Relvas, J. B., & Pinto, I. M. (2022). Mechanical actuators in microglia dynamics and function. European Journal of Cell Biology, 101(3), 151247.
3. Jiang W, Zhang LX, Tan XY, Yu P, Dong M. Inflammation and histone modification in chronic pain. Front Immunol. 2023 Jan 13;13:1087648. doi: 10.3389/fimmu.2022.1087648. PMID: 36713369; PMCID: PMC9880030.

Presenting Author: Vaneeza Kausar
Submitting Author: Vaneeza Kausar

Senior Author: Maral Tajerian

IASP 2026 Global Year theme of Neuropathic Pain: Yes

• Sebastian Alvarado: PhD - CUNY- Queens College
• Maral Tajerian: PhD - CUNY- Queens College