Label-free proteomic profiling identifies ECM-related alterations across regeneration states in human peripheral axonal neuropathies

Abstract

Understanding the multiple mechanisms underlying peripheral nerve regeneration in humans is crucial for developing effective therapies for peripheral axonal neuropathies. Although in vitro and in vivo studies have provided significant insights, human studies exploring the composition of proteome remain limited. The ECM plays a crucial role in nerve regeneration, influencing cell adhesion, proliferation, migration, and finally differentiation. In this study, we used a high-sensitivity, label-free liquid chromatography-mass spectrometry (LC-MS) method to investigate the global proteomic profile of human sural nerves aiming to identify molecular dynamics that promote or hinder nerve regeneration in well-characterized cohorts of patients with acute axonal injury, regenerating axonal neuropathy, and non-regenerating axonal neuropathy. Overall, 149 proteins were identified, of which 68 showed significant modulation across the groups. Proteins over-represented in regenerating nerves highlighted the multifactorial nature of regeneration, including immune modulation, debris clearance, cytoskeletal reorganization, axonal extension, and lipid transport. Conversely, structural myelin and neuronal proteins were significantly downregulated in non-regenerating nerves. Among the differentially expressed proteins, functional enrichment analysis revealed a significant overrepresentation of ECM-related components, providing compelling evidence that the ECM is not merely a passive scaffold, but an active driver of peripheral nerve regeneration. ECM remodeling contribute to / influence regenerative outcomes in human axonal neuropathies. Acutely injured nerves display enrichment in wound-response proteins, consistent with blood–nerve barrier disruption, and formation of a fibrin/fibronectin-rich ECM that supports repair. Regenerating nerves exhibit a dynamic ECM and a proteomic profile similar to those of controls, reflecting the restoration of a permissive regenerative environment. Non-regenerating nerves exhibit ECM accumulation and reduced levels of neuronal/myelin structural proteins, consistent with chronic regenerative failure.