American Association for Cancer Research
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Supplementary Data from Regulatory T-cell Depletion Alters the Tumor Microenvironment and Accelerates Pancreatic Carcinogenesis

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posted on 2023-04-03, 22:23 authored by Yaqing Zhang, Jenny Lazarus, Nina G. Steele, Wei Yan, Ho-Joon Lee, Zeribe C. Nwosu, Christopher J. Halbrook, Rosa E. Menjivar, Samantha B. Kemp, Veerin R. Sirihorachai, Ashley Velez-Delgado, Katelyn Donahue, Eileen S. Carpenter, Kristee L. Brown, Valerie Irizarry-Negron, Anna C. Nevison, Alekya Vinta, Michelle A. Anderson, Howard C. Crawford, Costas A. Lyssiotis, Timothy L. Frankel, Filip Bednar, Marina Pasca di Magliano

Supplementary Methods

Funding

Cancer Moonshot Initiative

NIH

NCI

University of Michigan Cancer

American Cancer Society

Cancer Center

Association of Academic Surgery Joel Roslyn

University of Michigan Medical School

History

ARTICLE ABSTRACT

Regulatory T cells (Treg) are abundant in human and mouse pancreatic cancer. To understand the contribution to the immunosuppressive microenvironment, we depleted Tregs in a mouse model of pancreatic cancer. Contrary to our expectations, Treg depletion failed to relieve immunosuppression and led to accelerated tumor progression. We show that Tregs are a key source of TGFβ ligands and, accordingly, their depletion reprogramed the fibroblast population, with loss of tumor-restraining, smooth muscle actin–expressing fibroblasts. Conversely, we observed an increase in chemokines Ccl3, Ccl6, and Ccl8 leading to increased myeloid cell recruitment, restoration of immune suppression, and promotion of carcinogenesis, an effect that was inhibited by blockade of the common CCL3/6/8 receptor CCR1. Further, Treg depletion unleashed pathologic CD4+ T-cell responses. Our data point to new mechanisms regulating fibroblast differentiation in pancreatic cancer and support the notion that fibroblasts are a heterogeneous population with different and opposing functions in pancreatic carcinogenesis. Here, we describe an unexpected cross-talk between Tregs and fibroblasts in pancreatic cancer. Treg depletion resulted in differentiation of inflammatory fibroblast subsets, in turn driving infiltration of myeloid cells through CCR1, thus uncovering a potentially new therapeutic approach to relieve immunosuppression in pancreatic cancer.See related commentary by Aykut et al., p. 345.This article is highlighted in the In This Issue feature, p. 327