The Spinal Extracellular Matrix Modulates a Multi-level Protein Net and Epigenetic Inducers Following Peripheral Nerve Injury.

The extracellular matrix (ECM) of the central nervous system (CNS) plays a pivotal role in the pathogenesis of several neurodegenerative and neuroinflammatory disorders. Among the major factors, matrix metalloproteinases (MMPs) are actively involved in ECM remodeling and directly affect neuro-glial interactions. Since disease-related functional alterations mostly rely on the proteome, modulation of MMPs activity may be a strategy to correct mechanisms behind neurological disorders. We here investigated modifications of signaling components related to the central pathways in spinal maladaptive plasticity following spared nerve injury (SNI) of the sciatic nerve, and after treatment with the MMPs inhibitor GM6001 for 3 or 8 days. We found that GM6001 reduced the massive astrocytic and microglial activation indicative of reactive gliosis. Functional activity of GM6001 was paralleled by its significant effect on expression levels of the purinergic P2X4 receptor (P2X4R), the transcription factors NFκB and RPBJ, as well as levels of the nerve growth factor (NGF) receptor TrkA. Moreover, we showed that histone deacetylases 1 and 2 (HDAC1, HDAC2) were differentially modulated after SNI and GM6001 treatments for 3 or 8 days. Our data suggest a multi-level network of interactions across ECM and the neuroglial network involving MMPs, the neurotrophin system, intracellular signaling, and epigenetic modifications.