免疫抑制的微环境富含调节性CD4+T淋巴细胞（Tregs），促进肺腺癌（LUAD）的进展。本研究旨在探索LUAD免疫抑制微环境形成的细胞机制。收集不同病理分期LUAD患者的LUAD样本（n=12）和正常肺组织样本（n=3）。进行单细胞RNA测序来分类细胞组分，分析转录组，包括转录因子/靶基因和趋化因子配体/受体，然后进行生物信息学研究，如伪时钟分析。肿瘤和正常肺组织中，髓样细胞和T细胞是最丰富的细胞类型，浸润性腺癌（IA）中，肿瘤相关巨噬细胞叶酸受体2（TAM-FOLR2）和CD4+核受体亚家族4A成员3（NR4A3）表达显著增加。IA中TAM-FOLR2的富集可能来自肺泡驻留巨噬细胞抗抗菌肽（ARM-RETN）转化和树突状细胞（DCs）和其他巨噬细胞的招募，这一点在趋化因子配体/受体的时序轨迹和差异表达谱上有证据。IA和DCs中观察到CCL17/19/22的高表达，以及TAM-FOLR2与DCs的强相互作用。伪时钟分析结果表明，CD4+NR4A3可能可以转化为CD4+FOXP3，这一点得到了CD4+FOXP3细胞中NR4A3靶基因高表达的支持。本研究提供了从前侵袭到浸润的LUAD的单细胞转录组图谱，并揭示了在LUAD发病过程中ARM-RETN/TAM-FOLR2/DCs/CD4+NR4A3/CD4+FOXP3的潜在轨迹塑造免疫抑制微环境。©2023. 作者。

An immunosuppressive microenvironment enriched with regulatory CD4+ T lymphocytes (Tregs) facilitates the progression of lung adenocarcinoma (LUAD). This study aims to investigate the cellular mechanism underlying the formation of the immunosuppressive microenvironment in LUAD. LUAD samples (n = 12) and normal lung samples (n = 3) were obtained from patients with different pathological stages of LUAD. Single-cell RNA sequencing was performed to classify cellular components and analyze the transcriptomes, including transcription factors/targets and chemokine ligands/receptors, followed by bioinformatics study such as pseudotime analysis. Myeloid cells and T cells were the most abundant cell types in tumors and normal lung tissues, while tumor-associated macrophage-folate receptor 2 (TAM-FOLR2) and CD4+ nuclear receptor subfamily 4 group A member 3 (NR4A3) exhibited sharp increases in invasive adenocarcinoma (IA). The enrichment of TAM-FOLR2 in IA might result from alveolar resident macrophage-resistin (ARM-RETN) transformation and recruitment of dendritic cells (DCs) and other TAMs, as evidenced by temporal trajectories and differential expression profiles of chemokine ligands/receptors versus those in the early stages of tumors. High expression of CCL17/19/22 was observed in IA as well as in DCs, along with the strong interaction of TAM-FOLR2 with DCs. The results of pseudotime analysis suggested that CD4+NR4A3 might potentially convert to CD4+FOXP3, further supported by the high expression of NR4A3 target genes in CD4+FOXP3 cells. This study provides a single-cell transcriptome atlas from preinvasive to invasive LUAD and reveals a potential ARM-RETN/TAM-FOLR2/DCs/CD4+NR4A3/CD4+FOXP3 trajectory in shaping the immune suppressive microenvironment along the pathogenesis of LUAD.© 2023. The Author(s).