Fig 2: ADSCs-ExosIFN−γ+TNF−α promoted immune escape of TNBC cells by transporting UCHL1. ADSCs were treated with 10 ng/mL IFN-γ and TNF-α, and transfected with si-NC or si-UCHL1. The exosomes were extracted from the supernatant. TNBC cells were treated with 10 μg/mL of the ADSCs-CM and different exosomes for 24 h, and then co-cultured with THP-1 cells for 48 h or with T cells for 16 h. A UCHL1 protein levels in TNBC cells in the indicated groups. B Viability of TNBC cells in the indicated groups. C Representative images showing Ki-67 expression in TNBC cells in the indicated groups. Scale bar = 100/25 μm. D Representative images showing migration of TNBC cells in the indicated groups. Scale bar = 100 μm. *P < 0.05 vs. MDA-MB-231 or MDA-MB-468. #P < 0.05 vs. Exos + MDA-MB-231 or Exos + MDA-MB-468. &P < 0.05 vs. ExosIFN−γ+TNF−α+con + MDA-MB-231 or ExosIFN−γ+TNF−α+con + MDA-MB-468. E The proportion of CD68+CD206+ THP-1 cells in the indicated groups. F Arg-1, CD206, TNF-α, and iNOS expression in THP-1 cells. *P < 0.05 vs. THP-1. #P < 0.05 vs. MDA-MB-231 + THP-1 or MDA-MB-468 + THP-1. &P < 0.05 vs. Exos + THP-1. @P < 0.05 vs. ExosIFN−γ+TNF−α+con + THP-1. G The proportion of CD3+CD8+ T cells in the indicated groups. H Perforin and GZMB levels in T cells. *P < 0.05 vs. T cells. #P < 0.05 vs. MDA-MB-231 + T cells or MDA-MB-468 + T cells. &P < 0.05 vs. Exos + T cells. @P < 0.05 vs. ExosIFN−γ+TNF−α+con + T cells

Fig 3: PC abolishes the cytotoxic effect of CD8 T cells on MM cells by inhibiting GZMB expression through exosomal Sb9 derived from MM cells via LPA.a Level of exosomal Sb9 derived from KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. b Representative images of the flow cytometric analysis for CD8 T cells cultured with PKH67-labeled exosomes (green) derived from WT or Sb9 KO KAS-6/1 and U266 cells treated with or without PC and LPA. c Sb9 protein levels in CD8 T cells cultured with PKH67-labeled exosomes (green) derived from WT or Sb9 KO KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. d GZMB mRNA levels in CD8 T cells cultured with exosomes derived from WT or Sb9 KO KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. e Released GZMB level in CD8 T cells cultured with exosomes derived from WT or Sb9 KO KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. f Representative images of the flow cytometric analysis and quantification of the rate of RFP-labeled KAS-6/1 and U266 cells co-cultured with WT or Sb9-overexpressed CD8 T cells. Mean± SD, n = 3 biological replicates, data represent two independent experiments. Sb9 SerpinB9, PC phosphatidylcholine, LPA lysophosphatidic acid, GZMB granzyme B, KO knockout, OE overexpression, WT wild type. All statistical tests were two-sided. Statistical significance was assessed using one-way ANOVA followed by post-hoc Tukey’s test except for (b). Adjustments were made for multiple comparisons. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. Source data are provided as a Source Data file.

Fig 4: Schematic diagram of molecular mechanisms for the current study.Lachnospiraceae and PC are critical differentiators between MM patients and healthy individuals. Besides, Lachnospiraceae inhibits PC production from MM cells. In addition, Lachnospiraceae enhances whereas PC hinders the cytotoxic effect of CD8 T cells on MM cells via Sb9. Mechanistically, PC promotes Sb9 mRNA maturation and expression in MM cells through LIN28A/B via LPA. Moreover, PC inhibits the cytotoxic effect of CD8 T cells on MM cells by reducing GZMB expression in CD8 T cells by exosomal Sb9 derived from MM cells via LPA. Furthermore, Sb9 reduces GZMB expression by inhibiting TP53 expression by suppressing TP53 UFMylation via competitive binding of TP53 with UFC1 in CD8 T cells. Sb9 SerpinB9, PC phosphatidylcholine, LPA lysophosphatidic acid, MMmultiple myeloma, GZMB granzyme B, UFC1 ubiquitin-fold modifier conjugating enzyme 1.

Fig 5: PC elevates Sb9 expression in MM cells to suppress the cytotoxic effect of CD8 T cells on MM cells by reducing GZMB expression via LPA.a LPA level of KAS-6/1 and U266 cells treated with or without PC. Mean± SD, n = 3 biological replicates, data represent two independent experiments. b The correlation heatmap between Lachnospiraceae abundance or blood PC and PC levels and the rate of GZMB + CD8 T cells in MM patients. c Sb9 mRNA level in KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. d Sb9 protein level in KAS-6/1 and U266 cells treated with or without PC and LPA. Mean± SD, n = 3 biological replicates, data represent two independent experiments. e Representative images of the flow cytometric analysis and quantification of the rate of GZMB + CD8 T cells in CD8 T cells co-cultured with WT or Sb9 KO KAS-6/1 and U266 cells. Mean± SD, n = 3 biological replicates, data represent two independent experiments. f Released GZMB level in CD8 T cells co-cultured with WT or Sb9 KO KAS-6/1 and U266 cells. Mean± SD, n = 3 biological replicates, data represent two independent experiments. g Representative images of the flow cytometric analysis and quantification of the rate of RFP-labeled WT or Sb9 KO KAS-6/1 and U266 cells co-cultured with CD8 T cells plus PC or LPA treatment. Mean± SD, n = 3 biological replicates, data represent two independent experiments. Sb9 SerpinB9, GZMB granzyme B, KO knockout, PC phosphatidylcholine, LPA lysophosphatidic acid, WT wild type. All statistical tests were two-sided. Statistical significance was assessed using one-way ANOVA followed by post hoc Tukey’s test except for (b). Adjustments were made for multiple comparisons. *P < 0.05; **P < 0.01; ****P < 0.0001. Source data are provided as a Source Data file.