Glycolytic activation of peritumoral monocytes fosters immune privilege via the PFKFB3-PD-L1 axis in human hepatocellular carcinoma.

Programmed cell death 1 ligand 1 (PD-L1) expression on antigen-presenting cells is essential for T cell impairment, and PD-L1-expressing macrophages may mechanistically shape and therapeutically predict the clinical efficacy of PD-L1 or programmed cell death 1 blockade. We aimed to elucidate the mechanisms underlying PD-L1 upregulation in human tumor microenvironments, which remain poorly understood despite the clinical success of immune checkpoint inhibitors. Monocytes/macrophages were purified from peripheral blood, non-tumor, or paired tumor tissues of patients with hepatocellular carcinoma (HCC), and their possible glycolytic switch was evaluated. The underlying regulatory mechanisms and clinical significance of metabolic switching were studied with both ex vivo analyses and in vitro experiments. We found that monocytes significantly enhanced the levels of glycolysis at the peritumoral region of human HCC. The activation of glycolysis induced PD-L1 expression on these cells and subsequently attenuated cytotoxic T lymphocyte responses in tumor tissues. Mechanistically, tumor-derived soluble factors, including hyaluronan fragments, induced the upregulation of a key glycolytic enzyme, PFKFB3, in tumor-associated monocytes. This enzyme not only modulated the cellular metabolic switch but also mediated the increased expression of PD-L1 by activating the nuclear factor kappa B signaling pathway in these cells. Consistently, the levels of PFKFB3+CD68+ cell infiltration in peritumoral tissues were negatively correlated with overall survival and could serve as an independent prognostic factor for survival in patients with HCC. Our results reveal a mechanism by which the cellular metabolic switch regulates the pro-tumor functions of monocytes in a specific human tumor microenvironment. PFKFB3 in both cancer cells and tumor-associated monocytes is a potential therapeutic target in human HCC. Programmed cell death 1 ligand 1 (PD-L1) expressed on antigen-presenting cells, rather than tumor cells, has been reported to play an essential role in checkpoint blockade therapy. A fundamental understanding of mechanisms that regulate the expression of PD-L1 on tumor-infiltrating monocytes/macrophages will undoubtedly lead to the possibility of developing novel PD-L1 blockade strategies with high specificity and efficiency. The current study unveils a novel mechanism by which metabolic switching links immune activation responses to immune tolerance in the tumor milieu, identifying potential targets for future immune-based anti-cancer therapies.

Chen DP ，Ning WR ，Jiang ZZ ，Peng ZP ，Zhu LY ，Zhuang SM ，Kuang DM ，Zheng L ，Wu Y ... -  《-》

IL-6 promotes PD-L1 expression in monocytes and macrophages by decreasing protein tyrosine phosphatase receptor type O expression in human hepatocellular carcinoma.

We have previously discovered a relationship between the low expression of protein tyrosine phosphatase, receptor type O (PTPRO) in tumor-infiltrating T cells and immunosuppression. The aim of the present study was to investigate the relationship between decreased PTPRO and increased programmed death ligand 1 (PD-L1) in both the peripheral monocytes and tumor-infiltrating macrophages of human hepatocellular carcinoma (HCC). The expression and correlation of all the indices were explored in monocytes and tumor-infiltrating macrophages within both human and mice HCC. The mechanic regulations were studied by using both in vitro and in vivo studies. We found a significant decrease in PTPRO in HCC peripheral monocytes that was associated with increased PD-L1 expression in peripheral monocytes and tumor-associated macrophages (TAMs) in HCC. Monocyte PD-L1 and PTPRO therefore could serve as valuable prognostic indicators for post-surgery patients with HCC and were associated with increased T-cell exhaustion (Tim3+T cells). A depletion of PTPRO promoted PD-L1 secretion in both monocytes and macrophages through the JAK2/STAT1 and JAK2/STAT3/c-MYC pathways. Increased IL-6 expression was associated with activation of JAK2/STAT3/c-MYC and with decreased PTPRO expression through the STAT3/c-MYC/miR-25-3 p axis. Monocytes and TAMs showed significantly increased miR-25-3 p expression, which could target the 3' untranslated region of PTPRO. The miR-25-3 p expression positively correlated with serum IL-6 levels, but inversely correlated with PTPRO in HCC monocytes. IL-6/STAT3/c-MYC activation enhanced in vitro miR-25-3 p transcription and decreased PTPRO, while further promoting PD-L1 secretion. Adoptive cell transfer of c-MYC/miR-25-3 p-modified monocytes promoted tumor growth by downregulating PTPRO and causing a PD-L1-induced immunosuppression in an orthotopic tumor transplantation model. Increased serum IL-6 downregulated PTPRO expression in HCC monocytes and macrophages by activating STAT3/c-MYC/miR-25-3 p and by further enhancing PD-L1 expression through JAK2/STAT1 and JAK2/STAT3/c-MYC signaling.

Zhang W ，Liu Y ，Yan Z ，Yang H ，Sun W ，Yao Y ，Chen Y ，Jiang R ... -  《Journal for ImmunoTherapy of Cancer》

Glycolytic activation of monocytes regulates the accumulation and function of neutrophils in human hepatocellular carcinoma.

Neutrophils are one of the most abundant components in human hepatocellular carcinoma (HCC) and have been shown to play important roles in regulating disease progression. However, neutrophils are very short-lived cells in circulation, and mechanisms regulating their accumulation and functions in HCC are not yet fully understood. Monocytes were purified from non-tumor or paired tumor tissues of patients with HCC, and their production of neutrophil-attracting chemokines was evaluated. Mechanisms regulating the expression of CXCL2/8 by tumor monocytes, and the role of tumor monocyte-derived chemokines and cytokines in modulating neutrophil accumulation and functions were studied with both ex vivo analyses and in vitro experiments. Monocyte-derived CXCL2 and CXCL8 were major factors in regulating the recruitment of neutrophils into tumor milieus. These chemokines, in addition to tumor-derived soluble factors, could inhibit apoptosis and sustain survival of neutrophils, thus leading to neutrophil accumulation in tumor tissues. Moreover, monocyte-derived TNF-α acted synergistically with tumor-derived soluble factors to induce the production of the pro-metastasis factor OSM by neutrophils. Further, the glycolytic switch in tumor-infiltrating monocytes mediated their production of CXCL2 and CXCL8 via the PFKFB3-NF-κB signaling pathway. Accordingly, levels of PFKFB3, CXCL2/CXCL8 production in monocytes and infiltration of OSM-producing neutrophils were positively correlated in human HCC tissues. Our results unveiled a previously unappreciated link between monocytes and neutrophils in human HCC, identifying possible targets that could be therapeutically exploited in the future. Neutrophils constitute a major but poorly understood component of human hepatocellular carcinoma (HCC). Herein, we unveil a novel mechanism by which metabolic switching in monocytes promotes the accumulation of neutrophils in the tumors of patients with HCC. Both monocyte-produced chemokines and signals from the tumor microenvironment promote the production of the pro-metastatic factor OSM by neutrophils. These data identify potential targets for immune-based anticancer therapies for HCC.

Peng ZP ，Jiang ZZ ，Guo HF ，Zhou MM ，Huang YF ，Ning WR ，Huang JH ，Zheng L ，Wu Y ... -  《-》

Disruption of tumour-associated macrophage trafficking by the osteopontin-induced colony-stimulating factor-1 signalling sensitises hepatocellular carcinoma to anti-PD-L1 blockade.

In the tumour microenvironment, critical drivers of immune escape include the oncogenic activity of the tumour cell-intrinsic osteopontin (OPN), the expression of programmed death ligand 1 (PD-L1) and the expansion of tumour-associated macrophages (TAMs). We investigated the feasibility of targeting these pathways as a therapeutic option in hepatocellular carcinoma (HCC) mouse models. We analysed the number of tumour-infiltrating immune cells and the inflammatory immune profiles in chemically induced liver tumour isolated from wild-type and OPNknockout (KO) mice. In vitro cell cocultures were further conducted to investigate the crosstalk between TAMs and HCC cells mediated by OPN, colony stimulating factor-1 (CSF1) and CSF1 receptor (CSF1R). The in vivo efficacy of anti-PD-L1 and CSF1/CSF1R inhibition was evaluated in OPN overexpressing subcutaneous or orthotopic mouse model of HCC. The numbers of TAMs, as well as the expression levels of M2 macrophage markers and PD-L1 were significantly decreased, but the levels of cytokines produced by T-helper 1 (Th1) cells were upregulated in tumour tissues from OPN KO mice compared with that from the controls. In addition, we observed a positive association between the OPN and PD-L1 expression, and OPN expression and TAM infiltration in tumour tissues from patients with HCC. We further demonstrated that OPN facilitates chemotactic migration, and alternative activation of macrophages, and promotes the PD-L1 expression in HCC via activation of the CSF1-CSF1R pathway in macrophages. Combining anti-PD-L1 and CSF1R inhibition elicited potent antitumour activity and prolonged survival of OPNhigh tumour-bearing mice. Histological, flow cytometric and ELISA revealed increased CD8+ T cell infiltration, reduced TAMs and enhanced Th1/Th2 cytokine balance in multiple mouse models of HCC. OPN/CSF1/CSF1R axis plays a critical role in the immunosuppressive nature of the HCC microenvironment. Blocking CSF1/CSF1R prevents TAM trafficking and thereby enhances the efficacy of immune checkpoint inhibitors for the treatment of HCC.

Zhu Y ，Yang J ，Xu D ，Gao XM ，Zhang Z ，Hsu JL ，Li CW ，Lim SO ，Sheng YY ，Zhang Y ，Li JH ，Luo Q ，Zheng Y ，Zhao Y ，Lu L ，Jia HL ，Hung MC ，Dong QZ ，Qin LX ... -  《-》

Characterization of the Immune Microenvironment in Hepatocellular Carcinoma.

Purpose: Hepatocellular carcinoma (HCC) often arises in the setting of chronic liver inflammation and may be responsive to novel immunotherapies.Experimental Design: To characterize the immune microenvironment in HCC, IHC staining was performed for CD8-positive T lymphocytes, PD-1-positive, and LAG-3-positive lymphocytes, CD163-positive macrophages, and PD-L1 expression in tumor and liver background from 29 cases of resected HCC.Results: Expression of CD8 was reduced in tumor, and expression of CD163 was reduced at the tumor interface. Positive clusters of PD-L1 expression were identified in 24 of 29 cases (83%), and positive expression of LAG-3 on tumor-infiltrating lymphocytes was identified in 19 of 29 cases (65%). The expression of both PD-L1 and LAG-3 was increased in tumor relative to liver background. No association between viral status or other clinicopathologic features and expression of any of the IHC markers investigated was noted.Conclusions: LAG-3 and PD-L1, two inhibitory molecules implicated in CD8 T-cell tolerance, are increased in most HCC tumors, providing a basis for investigating combinatorial checkpoint blockade with a LAG-3 and PD-L1 inhibitor in HCC. Clin Cancer Res; 23(23); 7333-9. ©2017 AACR.

Yarchoan M ，Xing D ，Luan L ，Xu H ，Sharma RB ，Popovic A ，Pawlik TM ，Kim AK ，Zhu Q ，Jaffee EM ，Taube JM ，Anders RA ... -  《-》