Curcumin-loaded nanoemulsion for acute lung injury treatment via nebulization: Formulation, optimization and in vivo studies.

Introduction: Curcumin, a polyphenolic bioactive molecule, exhibits potent anti-inflammatory and antioxidant properties by reducing cytokine levels such as IL-6, TNF-α, and TGF-β. It regulates IL-17A and modulates key signaling pathways, including PI3K/AKT/mTOR, NF-κB and JAK/STAT. However, its clinical application is hindered by rapid metabolism, poor solubility, and chemical instability.

Method: Using the Box-Behnken design, this study developed and optimized a curcumin-loaded turmeric oil-based nanoemulsion system. The effects of turmeric oil, Tween 80 and sonication cycles on particle size (PS), polydispersity index (PDI), and encapsulation efficiency were analyzed. The optimized nanoemulsion was characterized by zeta potential, PDI, PS, morphology, loading efficiency, EE, and antioxidant activity (DPPH assay). In vitro cytotoxicity was evaluated using A549 cells, while in vivo efficacy was assessed in BALB/c mice through histological analysis, bronchoalveolar lavage fluid analysis, and TNF-α and IL-1β estimation via enzyme-linked immunosorbent assay.

Results: The optimized nanoemulsion had high entrapment efficiency (92.45±2.4 %), a PS of 130.6 nm, a PDI of 0.151, and a zeta potential of -1.7±0.6 mV. Nanoparticle tracking analysis confirmed a mean PS of 138.3±1.6 nm with a concentration of 3.78×10¹² particles/mL. Transmission electron microscopy imaging confirmed spherical morphology. The IC ₅₀ value was 25.65 μg/mL. The nanoemulsion remained stable for three months at 4±1 and 25±2 °C/ 60±5 % relative humidity. The optimized formulation significantly reduced BALF total cell count, alveolar wall thickening, and TNF-α and IL-1β levels (p < 0.001).

Conclusion: Overall, the optimized formulation significantly lowered levels of pro-inflammatory cytokines in the acute lung injury /acute respiratory distress syndrome mouse model.