Vessels encapsulating tumor clusters promote noninvasive metastasis of hepatocellular carcinoma by shaping an immunosuppressive microenvironment
Bi-Yu Huang, Zheng-Qi Mi, Xiao-Yu Zhang, Yu-Chen Ji, Meng-Zhi Wu, Zi-Feng Cheng, Chen Xie, Shuai He, Jing Zhu, Jian-Hong Fang, Chong Wu, Bin-Kui Li, Yun-Fei Yuan, Limin Zheng, Shi-Mei Zhuang
Bi-Yu Huang, Zheng-Qi Mi, Xiao-Yu Zhang, Yu-Chen Ji, Meng-Zhi Wu, Zi-Feng Cheng, Chen Xie, Shuai He, Jing Zhu, Jian-Hong Fang, Chong Wu, Bin-Kui Li, Yun-Fei Yuan, Limin Zheng, Shi-Mei Zhuang
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Research Article Hepatology Immunology Vascular biology

Vessels encapsulating tumor clusters promote noninvasive metastasis of hepatocellular carcinoma by shaping an immunosuppressive microenvironment

Abstract

Vessels encapsulating tumor clusters (VETC), a distinct vascular pattern in hepatocellular carcinoma (HCC), facilitates noninvasive metastasis in whole clusters. The interaction between VETC and the tumor microenvironment requires exploration. Here, we found that, compared with human non-VETC-HCCs, VETC-tumors exhibited more PD1+CD8+ T cells and Tregs, especially TNFRSF4+ Tregs and Ki67+ Tregs, which showed increased immunosuppressive and proliferative activity. Such immunosuppressive status was also detected in tumor emboli of VETC-HCCs, and Treg density in emboli was positively associated with metastatic cell proliferation. VETC-HCCs revealed abundance correlation, closer spatial proximity, and stronger immunosuppressive ligand-receptor interactions between TNFRSF4+ Tregs/Ki67+ Tregs and PD1+CD8+ T cells. Depleting Tregs in mice reduced PD1+CD8+ T cells in primary lesions, tumor emboli, and metastatic foci of VETC-allografts, and attenuated allograft metastasis. TGF-β1 levels were upregulated in endothelial cells of VETC-HCCs and associated with TNFRSF4+ Tregs/Ki67+ Tregs enrichment. Disrupting VETC formation decreased endothelial TGF-β1 expression and reduced TNFRSF4+ Tregs, Ki67+ Tregs, PD1+CD8+ T cells, and Treg/CD8+ T cell ratios. Collectively, VETC may enhance Treg activity via TGF-β1, while Tregs promote and sustain CD8+ T cell exhaustion through immune inhibitory ligand-receptor interaction, thereby shaping the immunosuppressive microenvironment and enabling tumor clusters to retain such niche to disseminate. These findings disclose mechanisms of tumor immune microenvironment formation and provide rationales for precision medicine.

Authors

Bi-Yu Huang, Zheng-Qi Mi, Xiao-Yu Zhang, Yu-Chen Ji, Meng-Zhi Wu, Zi-Feng Cheng, Chen Xie, Shuai He, Jing Zhu, Jian-Hong Fang, Chong Wu, Bin-Kui Li, Yun-Fei Yuan, Limin Zheng, Shi-Mei Zhuang

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Figure 4

Tumor emboli in human VETC HCCs retain an immunosuppressive niche similar to their primary lesions.

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Tumor emboli in human VETC HCCs retain an immunosuppressive niche simila...
(A) The number of Tregs in MVI+ and MVI– HCC tissues. MVI+ non-VETC, MVI– non-VETC, MVI+ VETC, MVI– VETC tumors: n = 35, 29, 69, 14. MVI+, presence of microvascular invasion. MVI–: absence of microvascular invasion. (B) The number of Tregs in tumor emboli. (C and D) The proportions of TNFRSF4+ Tregs (C) or Ki67+ Tregs (D) in tumor emboli. (E) The number of CD8+ T cells in tumor emboli. (F) The ratio of Treg/CD8+ T cells in tumor emboli. (G and H) Positive association between the number of Tregs (G) or CD8+ T cells (H) in the tumor emboli and in the primary tumor of VETC HCCs. (I and J) Positive association between the number of Tregs and the fraction of Ki67+ cells in both primary tumor (I) and tumor emboli (J) of VETC HCCs. For G–J, R represents the Pearson correlation coefficient. (K) The proportion of Ki67+ cells in tumor emboli. (L) The area of tumor emboli. For B–H and J–L, only the largest embolus was evaluated for those sections with more than one embolus. For B–D, white dashed lines outline tumor emboli. For B and D, representative images in non-VETC group, derived from adjacent sections of the same non-VETC HCC emboli with different stainings. non-VETC HCCs, n = 9 (B and E), 5 (C), 6 (D), 8 (F),7 (K), 17 (L); VETC HCCs: n = 35 (B and E), 29 (C, G, and H), 28 (D), 32 (F), 56 (I), 31 (J and K), 40 (L). Scale bars: 200 μm. Data are shown as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001, by 2-way ANOVA followed by Šidák’s post hoc test (A), Mann-Whitney U test (B–F and L), 2-tailed Student’s t test (K) and Pearson’s correlation test (G–J).