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 7

Disruption of VETC formation by inhibiting the Angpt2/Tie2 signaling relieves the immunosuppression in the tumor microenvironment.

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Disruption of VETC formation by inhibiting the Angpt2/Tie2 signaling rel...
(A) Disruption of the Angpt2/Tie2 axis by shAngpt2 or Rebastinib disrupted VETC formation in Hepa1-6 allografts. Rebastinib, Tie2 inhibitor. (B) The levels of TGF-β1 in TECs. (C) The number of Tregs. (D) The ratio of Treg/CD8+ T cells. (E and F) The proportions of TNFRSF4+ Tregs (E) and Ki67+ Tregs (F). (G) The proportion of PD1+CD8+ T cells. (H) The number of CD8+ T cells. (I) The proportion of GZMB+ or GZMK+CD8+ T cells. For (A–I), left panels: shNC, Hepa-shNC allografts (negative control, n = 11); shAngpt2, Hepa-shAngpt2 allografts with stable silencing of Angpt2 (n = 6). Right panels: Ctrl, Hepa1-6 allografts in mice treated with control solution (n = 6); Rebastinib, Hepa1-6 allografts in mice treated with Rebastinib (n = 8). Data are shown as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001, by Mann-Whitney U test (A, left panel; B; E right panel; F left panel; H left panel), 2-tailed Student’s t test (A, right panel; C; D; E, left panel; F, right panel; G; H, right panel; I).