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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Categories: 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 5

Targeted antigen delivery using CHP nanogel improves the antigen-presenting activity of TAMs.

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Targeted antigen delivery using CHP nanogel improves the antigen-present...
(A) CMS5a tumor–bearing BALB/c mice were intravenously injected with rhodamine-CHP:LPA, and 1 hour or 6 hours later, tumors were removed. The distribution of rhodamine-CHP in the tumor was observed using confocal laser microscopy. Scale bars: 2 mm. (B) CMS5a tumor–bearing BALB/c mice were intravenously injected with the rhodamine-CHP:LPA complex, and 1 hour, 6 hours, or 18 hours later, immune cells including CD11b+F4/80+ macrophages, B cells, CD8+ T cells, and CD4+ T cells in the tumor or the tumor-draining lymph node were isolated (n = 4 per group). The uptake of labeled CHP:LPA in these cells was measured by flow cytometry. Histograms show representative data for CHP:LPA incorporation. *P < 0.05, by2-factor factorial ANOVA followed by Tukey-Kramer post hoc analysis.(C) CMS5a tumor–bearing BALB/c mice were intravenously injected with the CHP:FAM-LPA complex, and 18 hours later, the uptake of CHP:FAM-LPA in these cells was measured using flow cytometry (n = 3 mice per group). Histograms show representative data for CHP:LPA incorporation. *P < 0.05, by 2-factor factorial ANOVA followed by Tukey-Kramer post hoc analysis. The experiments were repeated 3 times with similar results. (D) CMS5a tumor–bearing BALB/c mice were treated as in A, and 6 hours later, cryosections of tumor were prepared. Incorporation of rhodamine-CHP:LPA into CD11b+F4/80+ TAMs was observed by immunohistochemistry. Scale bar: 100 μm. (E and F) The complex of CHP with 9m-containing LPA (50 μg) was intravenously injected with CpG ODN (50 μg) into BALB/c mice. After 1 hour, 6 hours, and 18 hours, TAMs were isolated and cocultured for 72 hours as antigen-presenting cells with DUC18 CD8+ T cells as responder cells. Antigen-dependent proliferation of DUC18 CD8+ T cells was measured using a CFSE dilution assay (n = 3 per group). Histograms show representative data, and the numbers shown in the histograms indicate the percentage of proliferating CD8+ T cells. Data represent the mean ± SD. *P < 0.05, by 2-factor factorial ANOVA followed by Tukey-Kramer post hoc analysis. The experiments were repeated 2 times with similar results.