Biomimetic fucoidan nanoparticles with regulation of macrophage polarization for targeted therapy of acute lung injury.

Acute lung injury (ALI) is a complex acute respiratory illness with a high mortality rate. Reactive oxygen species (ROS) play a pivotal role in ALI, inducing cellular damage, inflammation, and oxidative stress, thereby exacerbating the severity of the injury. In this study, inspired by the "subtractive" strategy, we developed a fucoidan-based macrophage membrane bio-nanosystem, abbreviated as MF@CB, designed as an anti-inflammatory and antioxidant agent to alleviate lipopolysaccharide (LPS)-induced inflammation in ALI. MF@CB coated with macrophage membrane for effective targeting and accumulation in ALI lesions. In addition, MF@CB activates Nrf2 transcriptional activity in macrophages, inhibiting ROS synthesis at its origin while effectively removing ROS already present in the ALI. This dual-pronged approach demonstrates robust antioxidant properties and restores the macrophage antioxidant defense barrier. In the LPS-induced ALI mouse model, MF@CB significantly mitigated lung inflammatory damage by modulating lung macrophage polarization and inhibiting the over-secretion of pro-inflammatory cytokines by activated immune cells. More importantly, unlike most surface modification strategies because it remove the molecule, this approach is easier to apply and potentially safer and may provide useful insights into the development of more effective therapeutic strategies for ALI.