Abstract
The inconsistent immunotherapy response among lesions in patients with multiple primary lung cancer (MPLC) remains poorly understood, presenting a significant challenge for effective treatment. In this study, we conducted a comprehensive multiomics analysis of all lesions from a patient with MPLC who exhibited varied responses to neoadjuvant chemoimmunotherapy. Further verification was conducted through external single-cell data and multiplex immunohistochemistry of three cases of MPLC.Notably, tertiary lymphoid structures (TLSs) were observed across all nodules, regardless of response, suggesting possible TLS impairment in non-responsive nodules. Cell neighborhood (CN) analysis revealed that type II alveolar epithelial cell (AT2) cell-positive CNs were prevalent in non-responsive nodules, while AT2-negative CNs appeared in responsive nodules, strongly associating AT2 cell presence with a reduced therapeutic response. Spatial colocalization analysis further showed that AT2 cells surrounding TLSs upregulated immunosuppressive markers on B cells within TLSs. The mechanism of this suppressive effect was further unveiled that macrophage migration inhibitory factor (MIF), secreted by AT2 cells, binds to sialic acid acetylesterase (SIAE) receptors on B cells by single-cell RNA sequencing analysis, which were validated in four additional non-responsive nodules from three other patients with MPLC. Multiomics analysis revealed AT2 cells exert immunosuppressive effects by inhibiting B cells within TLS through MIF-SIAE signaling axis in patients with MPLC. These findings offered new perspectives for tailored immunotherapy for patients with MPLC.