Targeting mucus hyperproduction in COPD using siRNA-loaded switchable lipid nanoparticles to silence SPDEF

Mucus hyperproduction is a key component of chronic obstructive pulmonary disease (COPD), participating to airflow limitation and associated with an increased all-cause mortality. SAM-pointed domain-containing ETS transcription factor (SPDEF) is an intracellular transcription factor required for goblet cell differentiation. Downregulating SPDEF expression using siRNA is a therapeutic option to reduce mucus hyperproduction. However, several biological barriers such as mucus penetration and epithelial delivery still hamper the efficacy of RNA therapies for lung diseases. Here, using switchable lipid nanoparticles (LNP) to deliver SPDEF siRNA, we aim at evaluating the potential of targeting SPDEF in an air-liquid interface (ALI) model. Bronchial epithelial cells derived from pulmonary samples were collected after thoracic surgery of COPD and non-COPD patients and cultivated at the ALI. The size, charge and encapsulation efficiency of LNP were characterized. siRNA uptake was evaluated by flow cytometry and confocal imaging after 4h of exposure. Silencing efficiency was assessed by RT-qPCR and western blot. The siRNA-LNP were able to efficiently penetrate into differentiated cells in ALI culture. Confocal imaging confirmed that siRNA have penetrated within the cytoplasm of epithelial cells. SPDEF silencing was achieved 5 and 10 days after siRNA-LNPs exposure at the RNA and protein level, respectively. The uptake and silencing effects entry were similar in ALI derived from non-COPD subjects and patients with COPD. These results highlight the potential of this switchable lipid nanoparticle formulation to carry out siRNA drugs for COPD treatment.