Gene expression profile at single cell level of tumor-infiltrating immune cells from mice treated with anti-PD-L1+E.colipBAD28 vs anti-PD-L1+E.colipApyr [CD45positive_TILs_scRNAseq]

The gut microbiota is essential for many aspects of host physiology, and locally generated secretory IgA (SIgA) modulates its function. Microbiota community determines the efficacy of immune checkpoint blockade (ICB) in cancer immunotherapy. Extracellular ATP (eATP) released by the microbiota restricts the SIgA repertoire by limiting T follicular helper (Tfh) cells activity in the Peyer's Patches (PPs) via stimulation of ionotropic P2X7 receptor. Here we show that SIgA amplification by oral administration of the ATP hydrolysing enzyme apyrase corrects enteropathic features of ICB and improves the therapeutic outcome. Overall design: CD45+ cells were immediately sorted from MC38 tumor-bearing mice treated with anti-PD-L1+E.colipBAD28 or anti-PD-L1+E.colipApyr at day 18 from tumor injection and analyzed using scRNA-seq

肠道菌群（gut microbiota）对宿主生理活动的诸多关键环节发挥不可或缺的作用，局部生成的分泌型免疫球蛋白A（secretory IgA, SIgA）可对其功能进行精准调控。菌群群落可直接决定癌症免疫治疗中免疫检查点阻断（immune checkpoint blockade, ICB）的疗效。菌群释放的胞外ATP（extracellular ATP, eATP）可通过刺激离子型P2X7受体（ionotropic P2X7 receptor），抑制派尔集合淋巴结（Peyer's Patches, PPs）内滤泡辅助性T细胞（T follicular helper, Tfh）的活性，进而限制SIgA的抗体库范围。本研究证实，通过口服ATP水解酶apyrase扩增SIgA水平，可纠正免疫检查点阻断治疗相关的肠病特征，并显著改善治疗结局。
实验整体设计：于肿瘤接种后第18天，从接受抗PD-L1+大肠杆菌pBAD28（E.colipBAD28）或抗PD-L1+大肠杆菌pApyr（E.colipApyr）处理的MC38荷瘤小鼠体内即刻分选CD45+细胞，采用单细胞RNA测序（scRNA-seq）开展分析。