Antigen delivery targeted to tumor-associated macrophages overcomes tumor immune resistance
Daisuke Muraoka, … , Naozumi Harada, Hiroshi Shiku
Daisuke Muraoka, … , Naozumi Harada, Hiroshi Shiku
Published March 1, 2019; First published January 10, 2019
Citation Information: J Clin Invest. 2019;129(3):1278-1294. https://doi.org/10.1172/JCI97642.
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Research Article Immunology

Antigen delivery targeted to tumor-associated macrophages overcomes tumor immune resistance

Abstract

Immune checkpoint inhibitors and adoptive transfer of gene-engineered T cells have emerged as novel therapeutic modalities for hard-to-treat solid tumors; however, many patients are refractory to these immunotherapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. By comparing the tumor microenvironment of checkpoint inhibition–sensitive and –resistant murine solid tumors, we observed that the resistant tumors had low immunogenicity. We identified antigen presentation by CD11b+F4/80+ tumor–associated macrophages (TAMs) as a key factor correlated with immune resistance. In the resistant tumors, TAMs remained inactive and did not exert antigen-presenting activity. Targeted delivery of a long peptide antigen to TAMs by using a nano-sized hydrogel (nanogel) in the presence of a TLR agonist activated TAMs, induced their antigen-presenting activity, and thereby transformed the resistant tumors into tumors sensitive to adaptive immune responses such as adoptive transfer of tumor-specific T cell receptor–engineered T cells. These results indicate that the status and function of TAMs have a significant impact on tumor immune sensitivity and that manipulation of TAM functions would be an effective approach for improving the efficacy of immunotherapies.

Authors

Daisuke Muraoka, Naohiro Seo, Tae Hayashi, Yoshiro Tahara, Keisuke Fujii, Isao Tawara, Yoshihiro Miyahara, Kana Okamori, Hideo Yagita, Seiya Imoto, Rui Yamaguchi, Mitsuhiro Komura, Satoru Miyano, Masahiro Goto, Shin-ichi Sawada, Akira Asai, Hiroaki Ikeda, Kazunari Akiyoshi, Naozumi Harada, Hiroshi Shiku

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Figure 3

TAMs remain inactive in the resistant CMS5a tumor.

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TAMs remain inactive in the resistant CMS5a tumor. (A) Tumor tissue from...
(A) Tumor tissue from CT26-, CMS7-, CMS5a/NY-, or CMS5a tumor–bearing mice was collected 7 days after inoculation and subjected to microarray analysis. (B) Subsequent GSEA identified the downregulation of 2 indicated gene sets in resistant CMS5a tumors. (C) TAMs from the CT26-, CMS7-, CMS5a/NY-, or CMS5a tumor–bearing mice were collected, and total RNA from these TAMs was subjected to microarray analysis. Subsequent GSEA identified the downregulation of 2 indicated gene sets in TAMs from CMS5a tumors. (D) TAMs were isolated from each tumor 7 days after inoculation and were tested by flow cytometry for the expression of PD-L1, CD40, CD86, CD80, and MHC class II (n = 6 tumors per group). MFI, mean fluorescence intensity. *P < 0.05, by 2-factor factorial ANOVA followed by Tukey-Kramer post hoc analysis. The experiments were repeated 3 times with similar results. (E) PD-L1 and MHC class II expression was also analyzed by immunohistochemistry. Scale bars: 200 μm. (F) TAMs isolated from CMS5a tumor–bearing mice on day 7 were cocultured for 72 hours as antigen-presenting cells with 9m-specific DUC18 CD8+ T cells as responder cells. Antigen-dependent proliferation of DUC18 CD8+ T cells and production of IFN-γ were measured by CFSE dilution assay (n = 3–4 per group) or ELISA (n = 8–9 per group), respectively. Histograms show representative data, and the numbers shown in the histograms indicate the percentage of proliferating cells. *P < 0.05, by 2-tailed Student’s t test. Data represent the mean ± SD. The experiments were repeated 2 times with similar results.