Age-driven lipid remodeling promotes reciprocal ferro-inflammation response via TLR4 signaling to impair nerve regeneration

The regenerative capacity of peripheral nerves declines significantly with age because of unresolved neuroinflammation and metabolic dysregulation. However, the precise intercellular crosstalk driving this pathological microenvironment remains elusive. Multi-omics (LC–MS/MS lipidomics, proteomics, and transcriptomics) were integrated using sciatic nerve crush models in young and aged mice. The mechanistic signaling axis was dissected through in vitro Schwann cells (SCs)-macrophage co-culture systems and in vivo interventions using the ferroptosis inhibitor Liproxstatin-1 (Lip-1) or the TLR4 antagonist TAK-242. The resulting ferro-inflammatory cascade and regenerative phenotypes were evaluated via integrated biochemical and morphological analyses. Delayed remyelination and persistent local inflammation were exhibited by aged sciatic nerves post-injury. A distinctive accumulation of oxidized lipids (specifically PC 16:0/18:2-OOH) was identified in aged nerve stumps via multi-omics integration. Mechanistically, ferroptosis was undergone by SCs subjected to ischemic stress, and lipid danger-associated molecular patterns (DAMPs) were released, by which macrophages were polarized toward a pro-inflammatory phenotype. The TLR4/NF-κB axis was pinpointed by RNA-seq profiling as the master transcriptional hub driving this process. The reciprocal injury response was effectively dismantled by targeted interruption of this signaling—either by quenching upstream SCs lipid peroxidation (Lip-1) or blocking downstream macrophage TLR4 signaling (TAK-242). Pro-inflammatory cytokine secretion (IL-1β, TNF-α, IL-6, and CCL2) was robustly suppressed, and a permissive microenvironment for axonal regeneration was restored both in vitro and in vivo. Age-driven lipidomic remodeling orchestrates a detrimental and reciprocal ferroptosis-inflammation response via the TLR4/NF-κB axis, fundamentally crippling peripheral nerve remyelination. Targeted disruption of this specific lipid-immune crosstalk provides a promising therapeutic paradigm for rejuvenating peripheral nerve repair in the aging population.