[Show abstract][Hide abstract] ABSTRACT: Inflammation is a component of tumour progression mechanisms. Neutrophils are a common inflammatory infiltrate in many tumours, but their regulation and functions in neoplasia are not understood. We recently demonstrated that pro-inflammatory IL-17-producing cells recruited blood neutrophils into the peritumoural stroma of hepatocellular carcinoma by epithelium-derived CXC chemokines. Here we show that a substantial population of neutrophils accumulates in the peritumoural stroma of hepatocellular, cervical, colorectal, and gastric carcinomas, and that this correlates with metastases in hepatocellular and gastric carcinomas. Exposure of neutrophils to culture supernatants from several types of solid tumour cells (TSN) resulted in sustained survival and pro-tumourigenic effects of cells. Kinetic experiments reveal that, shortly after exposure to TSN, neutrophils began to provoke activation and then produced significant inflammatory cytokines and expressed more anti-apoptotic Mcl-1 but less pro-apoptotic Bax. These long-lived neutrophils effectively enhanced the cancer cell motility via a contact-dependent mechanism; this effect, together with early activation and subsequent longevity of TSN-exposed neutrophils, could be reversed by blocking the activation of PI3K/Akt signalling in neutrophils. Moreover, we found that hyaluronan (HA) fragments constitute a common factor produced by various tumours that mimics the effect of TSN to induce long-lived neutrophils and subsequent malignant cell migration. The effects of TSN were inhibited by function blocking interactions between HA and its receptor TLR4 on neutrophils, suggesting that this is a key signalling pathway involved. These results indicate that HA derived from malignant cells educates neutrophils to adopt an activated phenotype, and in that way stimulates the metastasis of malignant cells, which represents a positive regulatory loop between tumours and their stroma during neoplastic progression.
Preview · Article · Nov 2011 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: Substantial evidence indicates that inflammation is a critical component of tumor progression. Hepatocellular carcinoma (HCC) is usually derived from inflamed cirrhotic liver with extensive leukocyte infiltration. Neutrophils are the common inflammatory infiltrate in tumors, but their nature and regulation in human cancers remain elusive.
A total of 238 HCC patients were enrolled randomly. Immunohistochemistry and SuperArray Real-Time PCR were used to analyze the distribution and clinical relevance of neutrophils in different microanatomical areas. The regulation and function of neutrophils were assessed by both in vitro and in vivo studies.
Neutrophils were enriched predominantly in peritumoral stroma of HCC tissues and their levels could serve as a powerful predictor for poor survival in HCC patients. Proinflammatory IL-17 is a critical mediator of the recruitment of neutrophils into peritumoral stroma of HCC tissues by epithelial cell-derived CXC chemokines. The accumulated peritumoral neutrophils were the major source of matrix metalloproteinase-9 in HCC tissues; this secreted protein stimulated proangiogenic activity in hepatoma cells. Accordingly, high infiltration of peritumoral neutrophils was positively correlated with angiogenesis progression at tumor-invading edge of HCC patients. Furthermore, we found that selective depletion of neutrophils effectively inhibited tumor angiogenesis and growth, in vivo.
These data provide direct evidence supporting the critical role of neutrophils in human tumor progression and reveal a fine-tuned collaborative action between cancer cells and immune cells in distinct tumor milieu, which reroutes the inflammatory response into a tumor-promoting direction.
Preview · Article · Nov 2010 · Journal of Hepatology
[Show abstract][Hide abstract] ABSTRACT: The proinflammatory IL-17-producing CD8(+) T cells (Tc17 cells) have recently been detected in tumors, but the nature and regulation of these cells in human tumors are presently unknown. We have recently found that IL-17(+) cells are accumulated in human hepatocellular carcinomas (HCC), where they promote disease progression by fostering angiogenesis. In this study, we showed that Tc17 cells constitute a remarkable portion of IL-17-producing cells in human HCC. Although most circulating Tc17 cells were negative for IFN-gamma, >80% of Tc17 cells in HCC tissues were positive for IFN-gamma, and they were enriched predominantly in invading tumor edge. Most CD68(+) cells located in invading tumor edge exhibited an activated phenotype and, accordingly, the activated monocytes isolated from HCC tissues were significantly superior to those isolated from nontumor tissues in inducing expansion of Tc17 cells in vitro with phenotypic features similar to those isolated from tumors. Compared with IL-17(-)IFN-gamma(+)CD8(+) cells, these IFN-gamma(+)Tc17 cells have significantly higher expression of proinflammatory cytokines (IL-2, IL-22, and TNF-alpha), but reduced expression of granzyme B and perforin. Moreover, we found that tumor-activated monocytes secreted a set of key cytokines (IL-1beta, IL-6, and IL-23) to trigger the proliferation of Tc17 cells. These data reveal an intriguing mechanism in which human Tc17 cells are generated by a fine-tuned collaborative action between different types of immune cells in distinct tumor microenvironments.
Preview · Article · Aug 2010 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Although cancer patients exhibit a generalized immunosuppressive status, substantial evidence indicates that the inflammatory reaction at a tumor site can promote tumor growth and progression. Hepatocellular carcinoma (HCC) is usually derived from inflamed cirrhotic liver with extensive leukocyte infiltration. We recently found that proinflammatory T helper (Th)17 cells are accumulated in HCC tissue, where they promote disease progression by fostering angiogenesis. Here we show that interleukin (IL)-17-producing cells were enriched predominantly in peritumoral stroma of HCC tissues, and their levels were well correlated with monocyte/macrophage density in the same area. Most peritumoral CD68(+) cells exhibited an activated phenotype. Accordingly, tumor-activated monocytes were significantly superior to the suppressive tumor macrophages in inducing expansion of Th17 cells from circulating memory T cells in vitro with phenotypic features similar to those isolated from HCCs. Moreover, we found that tumor-activated monocytes secreted a set of key proinflammatory cytokines that triggered proliferation of functional Th17 cells. Inhibition of monocytes/macrophages inflammation in liver markedly reduced the level of tumor-infiltrating Th17 cells and tumor growth in vivo. CONCLUSION: The proinflammatory Th17 cells are generated and regulated by a fine-tuned collaborative action between different types of immune cells in distinct HCC microenvironments, and allows the inflammatory response of activated monocytes to be rerouted in a tumor-promoting direction. Selectively modulating the "context" of inflammatory response in tumors might provide a novel strategy for anticancer therapy.
[Show abstract][Hide abstract] ABSTRACT: Macrophages (Mphi) are prominent components of solid tumors and exhibit distinct phenotypes in different microenvironments. We have recently found that tumors can alter the normal developmental process of Mphi to trigger transient activation of monocytes in peritumoral stroma. We showed that a fraction of monocytes/Mphi in peritumoral stroma, but not in cancer nests, expresses surface PD-L1 (also termed B7-H1) molecules in tumors from patients with hepatocellular carcinoma (HCC). Monocytes activated by tumors strongly express PD-L1 proteins with kinetics similar to their activation status, and significant correlations were found between the levels of PD-L1(+) and HLA-DR(high) on tumor-infiltrating monocytes. Autocrine tumor necrosis factor alpha and interleukin 10 released from activated monocytes stimulated monocyte expression of PD-L1. The PD-L1(+) monocytes effectively suppressed tumor-specific T cell immunity and contributed to the growth of human tumors in vivo; the effect could be reversed by blocking PD-L1 on those monocytes. Moreover, we found that PD-L1 expression on tumor-infiltrating monocytes increased with disease progression, and the intensity of the protein was associated with high mortality and reduced survival in the HCC patients. Thus, expression of PD-L1 on activated monocytes/Mphi may represent a novel mechanism that links the proinflammatory response to immune tolerance in the tumor milieu.
Preview · Article · Jun 2009 · Journal of Experimental Medicine