Ophiopogonin D induced Plet1+ macrophage differentiation to treat acute lung injury through blocking the interaction between NCOR1 and PPARγ.

Acute lung injury (ALI) remains a major public health challenge. Although Ophiopogonin D (OPD) possesses well-documented anti-inflammatory activity, its therapeutic efficacy and mechanisms in ALI remain elusive. In this study, we established an ALI model via lipopolysaccharide (LPS) challenge and treated mice with OPD. OPD significantly ameliorated multiple indices of lung injury. Using single-cell RNA sequencing (scRNA-seq), we identified the key cell types and pathways mediating OPD's protective effects. scRNA-seq revealed that OPD primarily corrected the M1/M2 macrophage imbalance. Both in vitro and in vivo, OPD suppressed M1 polarization and, more prominently, promoted the differentiation of Plet1+ macrophage, an M2-like subset. Mechanistically, OPD activated peroxisome proliferator-activated receptor gamma (PPARγ) to upregulate placenta-expressed transcript 1 (PLET1) expression; this effect was abolished by PPARγ inhibition. Thermal proteome profiling (TPP) coupled with subsequent validation identified nuclear receptor corepressor 1 (NCOR1) as a direct target of OPD. OPD disrupted the NCOR1-PPARγ interaction. Ncor1 knockdown phenocopied OPD's promotion of Plet1+ macrophage differentiation, whereas Ncor1 overexpression completely abrogated these effects. Collectively, OPD directly binds NCOR1 and disrupts the NCOR1-PPARγ interaction, thereby activating PPARγ and inducing Plet1+ macrophage differentiation to ameliorate LPS-induced ALI.