Neutrophil-targeted liposomal inhibition of PAD4-mediated NETosis in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disease characterized by a broad range of clinical manifestations. The lack of disease-specific therapies presents important challenges in the treatment of this disease. Targeted drug delivery systems can enhance the selectivity and specificity of drug administration to the intended cells, thereby improving treatment effectiveness and minimizing side effects associated with therapeutic agents. The formation of neutrophil extracellular traps, known as NETosis, plays a critical role in the pathogenesis of SLE. Peptidylarginine Deiminase 4, a key regulator of NETosis, represents a promising therapeutic target in SLE, as its inhibition can reduce histone citrullination, NET release, and downstream autoimmune activation. Here, through extensive formulation refinement and structure-function analysis, we designed neutrophil-targeted liposomes for delivering a PAD4 inhibitor. Targeting was evaluated by ELISA and surface plasmon resonance, and cell-based assays, whereas in vivo studies assessed biodistribution, pharmacokinetics, and therapeutic efficacy. While in vitro studies demonstrated effective targeting in cells overexpressing LOX-1, the in vivo multiple-dose efficacy study showed no significant difference between targeted and control liposomes. Notably, both liposomal formulations resulted in an improved therapeutic outcomes compared with the free drug, while targeted liposomes showed a more favorable tolerability profile. These findings highlight the benefit of liposomal encapsulation while questioning the improvement of a selective targeting approach in vivo.