Sauchinone-loaded chitosan nanoparticles simultaneously suppress NF-κB-driven inflammation, activate the Nrf2/HO-1 axis, and restore sarcolemmal utrophin in a murine model of Duchenne muscular dystrophy.

Abstract

Duchenne muscular dystrophy (DMD) is driven by dystrophin loss, chronic NF-κB-dependent inflammation, impaired Nrf2 antioxidant signaling, and dystrophin-associated protein complex (DAPC) instability. Sauchinone has dual NF-κB-inhibitory and Nrf2-activating activity but poor oral bioavailability (<8%). We prepared sauchinone-encapsulated chitosan nanoparticles (SCE-NPs) by ionic gelation and evaluated their colloidal properties, pH-responsive release, biointerface activity, and efficacy in mdx mice. SCE-NPs were 159 ± 12 nm with PDI 0.178 ± 0.02, zeta potential + 28.4 ± 1.8 mV, encapsulation efficiency 84.7 ± 2.1%, and drug loading 10.1 ± 0.4%. The formulation released > 80% sauchinone at pH 5.5 within 24 h but ≈ 45% at pH 7.4 over 72 h. Six-week-old male mdx mice (n = 10/group) received oral treatment every other day for 12 weeks. High-dose SCE-NPs (30 mg/kg) improved grip strength (+34%; p < 0.001) and treadmill endurance (2.4-fold), reduced quadriceps fibrosis (-52%; Cohen's d = 2.41), suppressed nuclear NF-κB p65 (-68%), and increased nuclear Nrf2 (+3.1-fold), HO-1 (+2.8-fold), and NQO1 (+3.2-fold). Sarcolemmal utrophin rose 3.2-fold with partial DAPC restoration, macrophages shifted from M1-dominant (67.3%) to M2-enriched (46.8%), and RNA-seq identified 1847 differentially expressed genes. Preliminary safety endpoints (serum ALT, AST, BUN, creatinine) remained within reference ranges, although the safety panel was limited. SCE-NPs represent a mutation-agnostic nanoformulation candidate for multi-axis DMD modulation, though pharmacokinetic, biodistribution, and mechanistic studies are needed for translation.