iNKT cells exacerbate Sepsis-associated acute lung injury through IFN-γ-mediated promotion of macrophage apoptosis

Sepsis is a lethal systemic inflammatory syndrome, frequently progresses to acute lung injury (ALI). This study integrates transcriptomics and Mendelian randomization to identify invariant natural killer T (iNKT) cells as pivotal regulators of sepsis-associated ALI. Analysis of the GSE26378 dataset (|Log2FC| > 0.5, p < 0.05) with functional enrichment revealed immune dysregulation pathways. Bidirectional MR using FinnGen (R12_O15) and GWAS immune cell datasets (n = 731) confirmed iNKT's central role. In LPS-induced ALI models, CD1d-/- mice exhibited reduced pulmonary macrophage apoptosis and inflammation versus wild-type controls. In vitro, iNKT cell line DN32·D3 co-cultured with bone marrow-derived macrophages under LPS/α-Galcer stimulation demonstrated IFN-γ-dependent exacerbation of apoptosis and TNF-α/IL-6 releasing. IFN-γ neutralization attenuated these effects. Transcriptomic profiling of activated iNKT cells identified apoptosis-associated speck-like protein (ASC) as a key mediator, with Western Blotting validation showing its marked upregulation in sepsis. Mechanistically, iNKT-IFN-γ axis activation potentiates macrophage apoptotic susceptibility through ASC-driven pathways, amplifying cytokine storms that aggravate ALI. Therapeutic interventions targeting iNKT depletion or IFN-γ blockade significantly mitigated lung injury metrics in both murine models and cellular systems. These findings establish iNKT cells as critical hubs linking innate and adaptive immune dysregulation in sepsis, with ASC serving as a novel regulatory node. The study provides a multi-omics framework for sepsis immunopathology, proposing targeted immunomodulation of the iNKT-IFN-γ-Macrophages axis as a promising therapeutic strategy for ALI management.