Hedgehog signaling promotes tumor-associated macrophage polarization to suppress intratumoral CD8+ T cell recruitment
Amy J. Petty, … , Xiaopei Huang, Yiping Yang
Amy J. Petty, … , Xiaopei Huang, Yiping Yang
Published October 22, 2019
Citation Information: J Clin Invest. 2019;129(12):5151-5162. https://doi.org/10.1172/JCI128644.
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Research Article Immunology

Hedgehog signaling promotes tumor-associated macrophage polarization to suppress intratumoral CD8+ T cell recruitment

Abstract

Tumor-associated macrophages (TAMs) usually display an antiinflammatory M2-like phenotype to facilitate tumor growth. However, what drives M2 polarization of TAMs and how TAMs suppress antitumor immunity within the tumor microenvironment (TME) remain largely undefined. Using several murine tumor models, we showed that hedgehog (Hh) signaling in myeloid cells is critical for TAM M2 polarization and tumor growth. We also found that tumor cells secrete sonic hedgehog (SHH), an Hh ligand, and that tumor-derived SHH drives TAM M2 polarization. Furthermore, Hh-induced functional polarization in TAMs suppresses CD8+ T cell recruitment to the TME through the inhibition of CXCL9 and CXCL10 production by TAMs. Last, we demonstrated that Krüppel-like factor 4 (Klf4) mediates Hh-dependent TAM M2 polarization and the immunosuppressive function. Collectively, these findings highlight a critical role for tumor-derived SHH in promoting TAM M2 polarization, a mechanism for TAM-mediated immunosuppression, and may provide insights into the design of new cancer immunotherapeutic strategies.

Authors

Amy J. Petty, Ang Li, Xinyi Wang, Rui Dai, Benjamin Heyman, David Hsu, Xiaopei Huang, Yiping Yang

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Figure 5

Loss of Hh signaling in TAMs promotes CD8+ T cell infiltration via CXCL9 and CXCL10.

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Loss of Hh signaling in TAMs promotes CD8+ T cell infiltration via CXCL9...
(A and B) Quantification of tumor-infiltrating CD8+ T cells by immunofluorescent staining in Hepa1-6 cells implanted s.c. into Smofl/fl and SmoΔM mice (A) and in the autochthonous HCC model (B). (C) Chemotaxis of CD8+ T cells toward macrophages treated with IFN-γ (control) and IFN-γ plus SHH. (D) Ccl3, Ccl4, Ccl5, Cxcl9, and Cxcl10 mRNA levels in macrophages treated with IFN-γ or with IFN-γ plus SHH were measured by qRT-PCR. Expression was normalized to Actb and compared with untreated. (E) Chemotaxis of CD8+ T cells toward macrophages treated with IFN-γ alone, IFN-γ plus CXCL9 and/or CXCL10-neutralizing antibodies, and IFN-γ plus SHH. (F and G) Expression of Cxcl9 and Cxcl10 in Smofl/fl or SmoΔM TAMs was measured by qRT-PCR (F) and ELISA (G). Expression of mRNAs was normalized to Actb and compared with that of Smofl/fl TAMs (F). (H) Tumor growth of Hepa1-6 in Smofl/fl and SmoΔM mice injected with CXCR3-blocking antibody or isotype control. (I) Percentage of tumor CD8+ T cell infiltration quantified by FACS. (J) Frozen tissue sections were stained for CD8+ T cells and quantified under high-power field (hpf). Values are the mean ± SEM of a minimum of 3 independent experiments. **P < 0.005; ***P < 0.0005. n = 8 biological replicates per group (A and B); n = 5 technical replicates per group (C and E); n = 5 biological replicates per group (D, F–J). Two-tailed Student’s t test (A–D, F, and G); 1-way ANOVA (E); Kruskal-Wallis test (H); 2-way ANOVA (I and J). α, anti.