Tumor-derived exosomes drive pre-metastatic niche formation in lung via modulating CCL1+ fibroblast and CCR8+ Treg cell interactions

  • Cancer Immunol Immunother. 2022 Nov;71(11):2717-2730. doi: 10.1007/s00262-022-03196-3.
Ming Wang   #  1 ,  Zhongyu Qin   #  2 ,  Jiajia Wan  3 ,  Yan Yan  3 ,  Xixi Duan  3 ,  Xiaohan Yao  3 ,  Ziming Jiang  4 ,  Wenqing Li  3 ,  Zhihai Qin  5  6
Affiliations
  • 1. Medical Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China. [email protected].
  • 2. Changzhi Medical College, Changzhi, 046000, Shanxi, China.
  • 3. Medical Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China.
  • 4. Department of Urology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, Henan, China.
  • 5. Medical Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China. [email protected].
  • 6. Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450052, Henan, China. [email protected].
  • # Contributed equally.
PMID: 35428909 DOI: 10.1007/s00262-022-03196-3
Abstract

Background: Since the lung is one of the most common sites for Cancer metastasis, it could provide a suitable microenvironment for pre-metastatic niche (PMN) formation to facilitate tumor cell colonization. Regulatory T cells (Tregs) are an immunosuppressive cell type found ubiquitously in tumors and may play a crucial role in PNM formation. In this study, we investigated tumor-derived exosome (TDE)-induced Treg differentiation in the lung PMN as well as the underlying mechanisms.

Methods: TDEs were isolated from the Lewis lung carcinoma cell line (LLC-exo) and their effects on mouse pulmonary fibroblasts was investigated in vitro as well as on lung tumor formation and metastasis in a pre-injected mouse model. Immune cell populations in the lung were analyzed by flow cytometry. Expression of CCL1 and CCR8 was evaluated by immunofluorescence staining, qRT-PCR and Western blot analyses. Cytokine expression was measured using mouse cytokine arrays and ELISA.

Results: The number of CD4+ FoxP3+ Tregs was significantly increased in lungs in a LLC-exo pre-injected mouse model. Lung fibroblasts secreted increased amounts of CCL1 after co-culture with LLC-exo, which induced Treg differentiation by activating its specific receptor CCR8, ultimately contributing to the establishment of an immunologically tolerant PMN. Moreover, inhibiting the release of LLC-exo by GW4869, or blocking the CCL1-CCR8 axis using AZ084, suppressed Tregs differentiation and tumor metastasis in the lung.

Conclusions: Collectively, our study provides a novel mechanism by which Tregs are activated to form an immunologically tolerant PMN and demonstrates a critical link among lung fibroblasts, Tregs and metastatic tumor cells.

Keywords
CCL1–CCR8; Fibroblasts; Metastasis; PMN; Tregs.
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