Targeting neuronal FKBP5 attenuates mechanical allodynia by suppressing NF-κB-mediated neuroinflammation in an NTG-induced chronic migraine mouse model.

Abstract

Background: Chronic migraine (CM) is a debilitating neurological disorder characterized by persistent trigeminovascular sensitization and neuroinflammation. While FK506-binding protein 51 (FKBP5) modulates spinal neuroinflammation in chronic pain, its specific role in trigeminovascular nociceptive processing and CM pathogenesis remains largely unknown.

Methods: We used a nitroglycerin (NTG)-induced CM mouse model. Following RNA-sequencing (RNA-seq) of total RNA isolated from trigeminal nucleus caudalis (TNC) tissue lysates, target expression was validated via reverse transcription quantitative PCR (RT-qPCR), Western blotting, and immunofluorescence. To establish causality, we used a neuron-specific CRISPR-Cas9 editing system for Fkbp5 knockout within the TNC, alongside pharmacological interventions using the specific FKBP5 antagonist SAFit2 and the nuclear factor kappa B (NF-κB) inhibitor PDTC. Migraine-like behaviors were evaluated using von Frey filaments, coupled with biochemical analyses of NF-κB cascade activation and trigeminovascular neuroinflammation.

Results: RNA-seq, RT-qPCR, Western blotting, and immunofluorescence consistently confirmed a marked upregulation of Fkbp5 mRNA and FKBP5 protein in the TNC of NTG-treated mice, predominantly localized to neurons. Concurrently, significant microglial and astrocytic activation was observed in the TNC. Both neuron-specific Fkbp5 knockout and pharmacological inhibition with SAFit2 significantly attenuated NTG-induced periorbital and hind paw mechanical allodynia. Furthermore, FKBP5 deficiency blunted the NTG-triggered phosphorylation of p65 and IκBα, effectively suppressing the downstream release of pro-inflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), as well as the upregulation of calcitonin gene-related peptide (CGRP) and c-Fos. Crucially, targeted blockade of the NF-κB cascade with PDTC recapitulated the protective behavioral and biochemical effects of FKBP5 deficiency.

Conclusions: We demonstrate that neuronal FKBP5 is significantly associated with CM pathogenesis. FKBP5 sustains mechanical allodynia by activating the NF-κB-mediated neuroinflammatory cascade. Consequently, targeting FKBP5 represents a promising therapeutic strategy for CM.