Targeting tumor-associated macrophages and granulocytic myeloid-derived suppressor cells augments PD-1 blockade in cholangiocarcinoma
Emilien Loeuillard, Jingchun Yang, EeeLN Buckarma, Juan Wang, Yuanhang Liu, Caitlin Conboy, Kevin D. Pavelko, Ying Li, Daniel O’Brien, Chen Wang, Rondell P. Graham, Rory L. Smoot, Haidong Dong, Sumera Ilyas
Emilien Loeuillard, Jingchun Yang, EeeLN Buckarma, Juan Wang, Yuanhang Liu, Caitlin Conboy, Kevin D. Pavelko, Ying Li, Daniel O’Brien, Chen Wang, Rondell P. Graham, Rory L. Smoot, Haidong Dong, Sumera Ilyas
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Research Article Gastroenterology Oncology

Targeting tumor-associated macrophages and granulocytic myeloid-derived suppressor cells augments PD-1 blockade in cholangiocarcinoma

Abstract

Immune checkpoint blockade (ICB) has revolutionized cancer therapeutics. Desmoplastic malignancies, such as cholangiocarcinoma (CCA), have an abundant tumor immune microenvironment (TIME). However, to date, ICB monotherapy in such malignancies has been ineffective. Herein, we identify tumor-associated macrophages (TAMs) as the primary source of programmed death–ligand 1 (PD-L1) in human and murine CCA. In a murine model of CCA, recruited PD-L1+ TAMs facilitated CCA progression. However, TAM blockade failed to decrease tumor progression due to a compensatory emergence of granulocytic myeloid-derived suppressor cells (G-MDSCs) that mediated immune escape by impairing T cell response. Single-cell RNA sequencing (scRNA-Seq) of murine tumor G-MDSCs highlighted a unique ApoE G-MDSC subset enriched with TAM blockade; further analysis of a human scRNA-Seq data set demonstrated the presence of a similar G-MDSC subset in human CCA. Finally, dual inhibition of TAMs and G-MDSCs potentiated ICB. In summary, our findings highlight the therapeutic potential of coupling ICB with immunotherapies targeting immunosuppressive myeloid cells in CCA.

Authors

Emilien Loeuillard, Jingchun Yang, EeeLN Buckarma, Juan Wang, Yuanhang Liu, Caitlin Conboy, Kevin D. Pavelko, Ying Li, Daniel O’Brien, Chen Wang, Rondell P. Graham, Rory L. Smoot, Haidong Dong, Sumera Ilyas

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Figure 2

Host PD-L1 contributes to CCA progression.

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Host PD-L1 contributes to CCA progression. (A) Immunoblot analysis of PD...
(A) Immunoblot analysis of PD-L1 in mouse CCA cells (SB) and normal mouse cholangiocytes (NMC). (B–F) Tumor growth of 28 days after orthotopic implantation of 1 × 106 SB cells in WT or Pd-l1–/– mouse livers. (B) Average tumor weights in mg of WT or Pd-l1–/– mice (n ≥ 23). (C) Representative photographs of livers from B. (D) Percentage of CD206+ TAMs (left panel) and CD206+PD-L1+ TAMs (right panel) of F4/80int TAMs (CD45+ CD11b+F4/80in) in Pd-l1–/– normal liver (from mice without tumors) and tumors from WT and Pd-l1–/– mice (n ≥ 8). (E) Percentage of CD8+CD3+ T CTLs of CD45+ cells in Pd-l1–/– normal liver and tumors from WT and Pd-l1–/– mice (n ≥ 12). (F) Percentage of CD8+CD11a+ reactive CTLs of CD45+CD3+ cells in Pd-l1–/– normal liver and tumors from WT and Pd-l1–/– mice (n ≥ 12). (G) Percentage of PD-L1+ F4/80+ BMDMs after 72 hours of coculture in vitro with SB cells (ratio 1:1). BMDMs were isolated from WT mice (n = 4). (H) Percentage of PD-L1+F4/80+ BMDMs after 24 hours of treatment with conditioned medium (CM) from SB cells (1 mL). BMDMs were isolated from WT mice (n = 4). (I) Concentration (pg/mL) of soluble PD-L1 in conditioned medium of SB cells after 24 hours of culture (n = 8). (J) Percentage of INF-γ+ T cells and Ki67+ T cells after 24 hours of treatment with conditioned medium from SB cells (1 mL) with IgG or anti–PD-L1 neutralizing antibody (SB-CM/IgG or SB-CM/anti–PD-L1). T cells were isolated from WT mice (n ≥ 5). Data are represented as mean ± SD. Unpaired Student’s t test (B and G–I) and 1-way ANOVA with Bonferroni’s post hoc test (D–F and J) were used. *P < 0.05; **P < 0.01; ***P < 0.001.