Sun, Lijuan, Liu, Bodu, Zhao, Yixin, Egeblad, Mikala (November 2024) MPLA plus IFNg-activated tumor-associated macrophages alter fibroblast composition. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer, 2024 Nov 17-20, Boston, Massachusetts.
Abstract
In a previous study, we developed a strategy to reprogram tumor-associated macrophages (TAMs) and induce a collaborative innate-adaptive immune response by combining monophosphoryl lipid A (MPLA) with IFNγ. However, we also observed downregulation of extracellular matrix (ECM)-associated genes in MPLA+IFNγ-treated mammary tumors, indicating that the combination treatment impacts the tumor microenvironment beyond just the immune cells. In this study, we investigated how MPLA+IFNg treatment modulates the tumor ECM, with a particular focus on fibroblasts-the major ECM-producing cells. Using scRNA-seq to profile mammary carcinomas, we identified six macrophage populations (C1q+, Ccr2+, Spp1+, Lyz+, mt+ and ki67+ TAMs) and two fibroblast populations (Cd34+ and a-SMA+ fibroblasts) in MMTV-PyMT tumor. MPLA+IFNγ treatment increased the numbers and percentages of Lyz+ TAMs and Cd34+ fibroblasts, while the numbers and percentages of Spp1+ TAMs and α-SMA+ fibroblasts were decreased by the treatment. Thus, MPLA+IFNγ treatment induced significant changes in both macrophage and fibroblast populations. Further analysis revealed an unusual gene expression pattern in Lyz+ TAMs. Mgst1 and Gng12 expression was detected in Lyz+ TAMs at levels comparable to those in fibroblasts, despite these genes typically being expressed in fibroblasts but not in macrophages of normal human tissues. However, to our surprise, MPLA+IFNγ treatment did not significantly increase Mgst1 and Gng12 expression of mono-cultured TAMs or bone marrow-derived macrophages, suggesting that these genes were not directly upregulated by MPLA+IFNγ treatment. Instead, the Mgst1 and Gng12 transcripts may have originated from engulfed fibroblasts. In addition, following MPLA+IFNγ treatment, more iNOS+ macrophages (which we previously identified as tumoricidal macrophages) were found in very close proximity to α-SMA+ fibroblasts. To directly test whether MPLA+IFNg-treated TAMs kill and engulf fibroblasts, we performed ex vivo co-cultures of TAMs and fibroblasts. Following MPLA+IFNγ treatment, TAMs effectively killed and engulfed the fibroblasts, whereas minimal fibroblast engulfment was observed in the control co-cultures. Our data suggest that tumoricidal MPLA+IFNγ-treated TAMs can regulate the ECM of tumors by targeting and eliminating the major ECM-producing cells, the fibroblasts. Ongoing studies are determining the functional consequences of the TAM-mediated regulation of fibroblasts and ECM composition.
| Item Type: | Conference or Workshop Item (Paper) |
|---|---|
| Subjects: | diseases & disorders > cancer diseases & disorders |
| CSHL Authors: | |
| Communities: | CSHL labs > Egeblad lab CSHL labs > Siepel lab CSHL labs > Spector lab |
| SWORD Depositor: | CSHL Elements |
| Depositing User: | CSHL Elements |
| Date: | 17 November 2024 |
| Date Deposited: | 28 Jan 2025 14:52 |
| Last Modified: | 28 Jan 2025 14:52 |
| Related URLs: | |
| URI: | https://repository.cshl.edu/id/eprint/41782 |
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