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 7

TAM blockade facilitates accumulation of G-MDSC subsets with survival and immunosuppressive properties.

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TAM blockade facilitates accumulation of G-MDSC subsets with survival an...
(A–D) Tumor growth of 28 days after orthotopic implantation of 1 × 106 SB (murine CCA) cells in WT mice. Mice were treated from day 14 to day 28 after implantation with control IgG isotype or anti-CSF1R (AFS98). (A) Violin plots of expression levels for differentially expressed genes (Apoe, Ctsb, Ctsd, and S100a4) compared between control and anti-CSF1R–treated tumors. Colors indicate control and anti-CSF1R–treated samples. P values indicate significance of expression differences between control and treatment. (B) Percentage of Annexin V+7AAD+ G-MDSCs in control or anti-CSF1R–treated tumors (n ≥ 3). Representative flow plots show expression of Annexin V and 7AAD in G-MDSCs. (C) Violin plot of expression levels for differentially expressed genes (Stat1 and Nfkbia) compared between control and anti-CSF1R–treated tumors. P values indicate significance of expression differences between control and treatment. (D) Percentage of Ki67+ cells of CD8+ T cells (CD3+CD8+) (left panel) and percentage of INF-γ+ cells of CD8+ T cells (CD3+CD8+) (right panel) after 48 hours of coculture with G-MDSCs. (E) Hyperion multiplexed images show several immune cell markers using formalin-fixed, paraffin-embedded tissues from human CCA. Pseudo-colored raw ion images representing the markers of immune cells detected in the region of interest. Left panel shows pan-keratin (green), a CCA marker, and CD45 (red), a leukocyte marker. Right panel shows CD14 (yellow), a monocyte marker; CD68 (green), a macrophage marker; CD8 (red), a CTL marker; CD11b-CD15 (blue), G-MDSC markers. White arrowheads indicate CD8+ T cell (red) and G-MDSC (blue) interaction. Scale bars: 10 μm. (F) Flow plots show expression of CD15–CD14+ G-MDSCs in human CCA. Data are represented as mean ± SD. Unpaired Student’s t test (A–C) and 1-way ANOVA with Bonferroni’s post hoc test (D) were used. *P < 0.05; **P < 0.01; ***P < 0.001.