Figure 6. TDO2⁺ myofibroblasts mediate T cell suppression.

(A) Representative images (Pt14_Ca) (left) and quantitative analyses (right) showing the spatial distribution and the proportions of Foxp3⁺CD4⁺ T cells (light blue) around TDO2⁺ (red) and TDO2^– (green) myofibroblasts (radius <50 μm). Scale bars: 50 μm. (B) Representative images (Pt14_Ca) showing the spatial distribution of PD-1⁺TIM-3⁺CD8⁺ T cells around TDO2⁺ myofibroblasts. Scale bars: 50 μm and 10 μm (enlarged inset). (C) Schematic diagram depicting the coculture strategy for control myofibroblasts (si-NC) and TDO2-knockdown myofibroblasts (si-TDO2) with CD4⁺ or CD8⁺ T cells. (D–F) Representative images of flow cytometry (left) and statistical results (right) showing the proportions of (D) Foxp3⁺CD4⁺ T cells, (E) PD-1⁺, and (F) GZMB⁺CD8⁺ T cells for the control group (si-NC) and the TDO2-knockdown groups (si-TDO2-1 and si-TDO2-2). (G–I) Representative flow cytometry (left) and statistical results (right) showing the proportion of (G) Foxp3⁺ T cells, (H) PD-1⁺, and (I) GZMB⁺CD8⁺ T cells after 3 days of coculturing with TDO2^– or TDO2⁺ myofibroblasts or with TDO2⁺ myofibroblasts plus the TDO2 inhibitor LM10. (J) Representative IHC images of TMAs. The H scores of representative TDO2^hi and TDO2^lo images were 141.9 and 68.0, respectively. Scale bars: 400 μm (left) and 50 μm (right). (K) OS curve between TDO2^hi (n = 71) and TDO2^lo (n = 71) cohorts of patients with OSCC according to the staining intensity of IHC images. P < 0.0001, by log-rank test. (A and D–I) *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 1-way ANOVA followed by Bonferroni’s multiple-comparison test.