Nanotechnology-enabled M2 macrophage polarization and ferroptosis inhibition for targeted inflammatory bowel disease...

Transforming macrophages into the anti-inflammatory M2 phenotype could markedly strengthen inflammatory bowel disease (IBD) treatment, which is considered as a promising strategy. However, the high ferroptosis sensitivity of M2 macrophages, which decreases their activity, is a major stumbling block to this strategy. Therefore, promoting M2 polarization while simultaneously inhibiting ferroptosis to tackle this challenge is indispensable. Herein, a calcium‑carbonate (CaCO₃) mineralized liposome encapsulating a ferroptosis inhibitor (Fer-1) was developed (CaCO₃@Lipo@Fer-1, CLF). The CaCO₃ mineralized coating shields the liposomes to prevent the release of Fer-1 in circulation, while releasing Ca²⁺ in the acidic-inflammatory environment. This released Ca²⁺ promotes M2 polarization through the CaSR/AKT/β-catenin pathway. The subsequently released Fer-1 effectively upregulates GSH and GPX4, scavenges reactive oxygen species, and inhibits ferroptosis in M2 macrophages. In vivo, CLF improved the targeting efficiency of IBD lesions (about 4.17-fold) through the epithelial enhanced permeability and retention (eEPR) effect and enhanced IBD therapy by increasing the M2/M1 macrophage ratio and inhibiting ferroptosis. We demonstrate that the synergistic regulation of macrophage polarization and ferroptosis sensitivity by this mineralized nanoinhibitor is a viable strategy for IBD therapy.