Targeting Nav1.5 with DKK678 attenuates NF-κB-driven inflammatory injury in skeletal muscle.

Skeletal muscle inflammation associated with sepsis has been identified as a critical pathological process contributing to metabolic dysfunction and poor clinical outcomes. Voltage-gated sodium channels (VGSCs) have been implicated in immune modulation; however, their specific roles in skeletal muscle inflammation remain poorly understood. In this study, the VGSC subtype Nav1.5 was investigated as a potential regulator of inflammation, and the therapeutic efficacy of a novel recombinant scorpion peptide, DKK678, was evaluated. An in vitro model using lipopolysaccharide (LPS)-stimulated C2C12 cells and an in vivo cecal ligation and puncture (CLP) model in septic mice were established. In both models, Nav1.5 expression was significantly upregulated in response to inflammatory stimuli, while Nav1.4 expression remained unchanged. The nuclear factor kappa B (NF-κB) signaling pathway was found to be activated, contributing to increased expression of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), adhesion molecules (VCAM-1), and gap junction proteins (Cx43). Suppression of VGSC activity using lidocaine resulted in the inhibition of NF-κB phosphorylation and downregulation of inflammatory markers, while the expression of interleukin-10 (IL-10) and interleukin-4 (IL-4) were restored. Tetrodotoxin (TTX) treatment did not replicate these effects, suggesting Nav1.5-specific involvement. DKK678 was developed through bioinformatic design and molecular docking simulations, which predicted a stronger binding affinity and structural stability with Nav1.5 compared to Nav1.4. These predictions were validated through functional experiments. In vitro, DKK678 treatment dose-dependently inhibited LPS-induced NF-κB pathway activation and reversed abnormal expression of VCAM-1 and Cx43. In vivo, DKK678 significantly ameliorated CLP-induced skeletal muscle damage, suppressed inflammatory cytokine production, and improved tissue histopathology. Furthermore, the structural integrity of immune organs such as the thymus and spleen was preserved in DKK678-treated septic mice, with partial restoration of lymphocyte populations and organ indices. Notably, Nav1.5 expression was downregulated by DKK678, while Nav1.4 expression remained unaffected. These results demonstrate that Nav1.5 serves as a critical inflammatory modulator in skeletal muscle and immune tissues. Its upregulation was shown to drive NF-κB pathway activation and inflammatory cytokine production. By targeting Nav1.5, DKK678 was able to exert dual protective effects on both skeletal muscle and immune organs under septic conditions. The therapeutic potential of DKK678 was found to be comparable to that of dexamethasone (DEX) at high doses, without altering Nav1.4 expression. In conclusion, the present study provides new mechanistic insight into the role of Nav1.5 in skeletal muscle inflammation and identifies DKK678 as a promising peptide therapeutic that targets Nav1.5 to suppress NF-κB-mediated inflammatory injury. These findings suggest that Nav1.5 inhibition represents a viable strategy for the treatment of sepsis-associated myositis and related inflammatory disorders.