肿瘤相关巨噬细胞在肿瘤浸润转移过程中的作用

肿瘤相关巨噬细胞(tumor-associated macrophages,TAMs)是肿瘤免疫微环境中重要组成部分,主要分为M1、M2两种表型。在多数肿瘤组织中肿瘤相关巨噬细胞以M2型为主,其可与肿瘤细胞相互作用,促进肿瘤生长和转移,且具有抗肿瘤潜能和潜在的治疗价值。因此,深入了解肿瘤相关巨噬细胞,有助于更进一步探索其临床价值。本文从肿瘤相关巨噬细胞的起源和特点,以及对肿瘤发生发展作用作一综述。     

组织定居巨噬细胞在肿瘤微环境中的作用

肿瘤相关巨噬细胞(tumor-associated macrophages,TAMs)是肿瘤微环境中最主要的免疫细胞群之一,在肿瘤生长、血管生成和治疗等各环节发挥重要作用。以往研究认为肿瘤微环境中TAMs主要来源于循环单核细胞,但近期研究证实,起源于胚胎卵黄囊及胎肝的组织定居巨噬细胞也可以在肿瘤微环境中分化为TAMs,...     

肿瘤相关巨噬细胞研究进展

单核巨噬细胞是一种多功能细胞,对不同的微环境信号应答表现出不同的功能.而极化的M1和M2巨噬细胞是巨噬细胞功能表现的两个极端.其中侵润到肿瘤组织的巨噬细胞受肿瘤诱导产生的细胞因子的影响使巨噬细胞表现出巨噬细胞M2型表型,这些极化的巨噬细胞在破坏适应性免疫反应和促进肿瘤生长与进展方面具有重要作用.肿瘤相关巨噬细胞(TAM)可以促进肿瘤进展包括促进肿瘤生长、侵润、转移,促进血管生长和免疫抑制等,因而研究TAM具有重要意义.     

肿瘤相关巨噬细胞研究进展

单核巨噬细胞是一种多功能细胞,对不同的微环境信号应答表现出不同的功能.而极化的M1和M2巨噬细胞是巨噬细胞功能表现的两个极端.其中侵润到肿瘤组织的巨噬细胞受肿瘤诱导产生的细胞因子的影响使巨噬细胞表现出巨噬细胞M2型表型,这些极化的巨噬细胞在破坏适应性免疫反应和促进肿瘤生长与进展方面具有重要作用.肿瘤相关巨噬细胞(TAM)可以促进肿瘤进展包括促进肿瘤生长、侵润、转移,促进血管生长和免疫抑制等,因而研究TAM具有重要意义.     

肿瘤相关巨噬细胞参与肿瘤免疫调节的研究进展

肿瘤相关巨噬细胞(tumor-associated macrophage,TAM)是肿瘤微环境(tumor microenvironment,TME)中一种重要的炎症细胞,依据功能表型不同,大致分为M1型和M2型。TAMs分泌多种细胞因子,趋化因子和蛋白酶等,促进细胞外基质重塑,肿瘤细胞生长、转移,肿瘤血管、淋巴管新生及免疫抑制。TAMs的主要致病活性是免疫抑制反应,其在肿瘤的进展中起重要的作用,目前肿瘤免疫学进展也揭示了免疫抑制细胞TAMs的重要性,本文主要综述TAMs参与免疫抑制的机制及相关的细胞因子,及靶向这些因子免疫治疗的研究进展。     

xCT和促血管生成因子在胶质瘤组织中肿瘤相关巨噬细胞的表达及意义

目的：探讨xCT和促血管生成因子在胶质瘤组织中肿瘤相关巨噬细胞（TAMs）中的表达，以及TAMs对胶质瘤进展的影响。方法：分离并培养人新鲜胶质瘤和正常脑组织中的TAMs。采用荧光实时定量（RT-PCR）技术检测M2表型标记物CD14和CD86,促血管生成因子Arg-1和CD209，以及 xCT-mRNA表达水平。组织冰冻切片免疫荧光染色检测CD68和xCT在胶质瘤中的表达。结果：xCT和CD68在胶质母细胞瘤(WHO°Ⅳ)中的表达明显高于WHO°Ⅱ胶质瘤和正常脑组织，且xCT和CD68共同表达于小胶质细胞中。xCT mRNA在分化程度差的胶质瘤中表达明显增高。此外，小胶质细胞M2表型标记物表达水平(CD14和CD86)、活化状态的TAMs数目和促血管生成因子(Arg-1和CD209)与肿瘤分级相关。结论：TAMs能够通过xCT过表达，促炎症因子和促血管生成因子促进胶质瘤的发展。肿瘤中M2表型的TAMs募集与脑胶质瘤的不良预后相关。     

肿瘤相关巨噬细胞与肿瘤的发生发展

本文主要综述了肿瘤组织中的巨噬细胞不同类型(M型和M2型)对肿瘤细胞的所产生的不同作用,M1型巨噬细胞可通过多种途径杀伤肿瘤细胞,而M2型巨噬细胞却参与了肿瘤的发生、生长、侵袭和转移的过程,常常表现为促进肿瘤细胞生长、肿瘤血管生成以及肿瘤细胞迁移等作用.大量研究显示,存在于肿瘤组织中的肿瘤相关巨噬细胞(TAM)大部分表现出M2样的表型,且与肿瘤的治疗和预后密切相关.因此,基于TAM促肿瘤作用,通过抑制M2型巨噬细胞的作用或调控TAM表型的靶向治疗药物研究已取得相应成果.     

肿瘤相关巨噬细胞研究进展

巨噬细胞是肿瘤组织中存在的主要免疫细胞之一。随着巨噬细胞分为经典激活型或替代激活型这一重要生物学特征逐渐被揭示,肿瘤相关巨噬细胞(TAMs)的作用开始被阐明。TAMs一般称为"促肿瘤巨噬细胞",可促进肿瘤细胞的发生和转移,抑制T细胞介导的抗肿瘤免疫反应,促进肿瘤血管生成,进而导致肿瘤进展。随着TAMs与恶性肿瘤之间的关系越来越清楚,TAMs开始被作为肿瘤治疗的靶点。本文就TAMs在恶性肿瘤中的起源、极化、功能及其如何在临床中用于肿瘤治疗的靶点进行阐述。     

肿瘤相关巨噬细胞作为抗肿瘤靶点的研究进展

肿瘤相关巨噬细胞（TAMs）是肿瘤间质的重要成分,受肿瘤微环境影响表现出强烈的可塑性,在肿瘤的增殖、侵袭、转移、血管生成等方面发挥重要作用。近年来调控肿瘤微环境、靶向TAMs已成为肿瘤免疫治疗中重要的研究方向,本文系统地介绍了TAMs的促肿瘤作用及靶向TAMs治疗的研究进展。     

肿瘤相关巨噬细胞的极化及其对肿瘤治疗的影响

可塑性和多样性是巨噬细胞的重要特征,根据其功能不同,巨噬细胞被分为经典活化型即M1型,替代活化型即M2型。诱导M1和M2型巨噬细胞分化的条件不同,M1和M2型巨噬细胞的表型及功能也存在差异。在多数肿瘤微环境中存在M2型的巨噬细胞,该细胞通过产生多种细胞因子及蛋白酶参与肿瘤血管形成,并促进肿瘤的增殖及转移。因此,靶向抑制M2型巨噬细胞分化、清除M2型巨噬细胞等措施已成为肿瘤治疗研究的重要领域。本文主要对巨噬细胞的极化、肿瘤微环境对肿瘤相关巨噬细胞极化的影响及靶向肿瘤相关巨噬细胞的治疗策略进行综述。     

Tumor necrosis factor-alpha-converting enzyme activities and tumor-associated macrophages in breast cancer

The role of the tumor microenvironment especially of tumor-associated macrophages (TAMs) in the progression and metastatic spread of breast cancer is well established. TAMs have primarily a M2 (wound-healing) phenotype with minimal cytotoxic activities. The mechanisms by which tumor cells influence TAMs to display a pro-tumor phenotype are still debated although the key roles of immunomodulatory cytokines released by tumor cells, including colony-stimulating factor 1, tumor necrosis factor (TNF) and soluble TNF receptors 1/2, soluble vascular cell adhesion molecule 1, soluble interleukin 6 receptor and amphiregulin, have been demonstrated. Importantly, these factors are released through ectodomain shedding by the activities of the tumor necrosis factor-alpha-converting enzyme (TACE/ADAM17). The role of TACE activation leading to autocrine effects on tumor progression has been extensively studied. In contrast, limited information is available on the role of tumor cell TACE activities on TAMs in breast cancer. TACE inhibitors, currently in clinical trials, will certainly affect TAMs and subsequently treatment outcomes based on the substrates it releases. Furthermore, whether targeting a subset of the molecules shed by TACE, specifically those leading to TAMs with altered functions and phenotype, holds greater therapeutic promises than past clinical trials of TACE antagonists’ remains to be determined. Here, the potential roles of TACE ectodomain shedding in the breast tumor microenvironment are reviewed with a focus on the release of tumor-derived immunomodulatory factors shed by TACE that directs TAM phenotypes and functions.     

Oral squamous cell carcinoma suppressed antitumor immunity through induction of PD-L1 expression on tumor-associated macrophages

Oral squamous cell carcinoma (OSCC) is the most common solid tumor in the oral cavity. Development and progression of OSCC is associated with the elevated presence of inhibitory M2 type tumor-associated macrophages (TAMs). However, the underlying mechanism leading to the enrichment of M2 TAMs and the pathway through which TAMs foster tumor progression are still unclear. In this study, we harvested TAMs and tumor cells from primary OSCC resections of stage II and stage III patients. We showed that compared to peritumoral macrophages, TAMs presented upregulated expression of PD-L1 and elevated capacity in inducing T cell apoptosis. The level of PD-L1 expression directly correlated with the level of T cell apoptosis. Interestingly, peripheral blood monocytes with low initial PD-L1 level had upregulated PD-L1 expression and acquired the ability to induce T cell apoptosis, after incubation with primary tumor cells from OSCC patients. The PD-L1 expression by monocytes depended on interleukin 10 (IL-10), since blockade of IL-10 in the tumor-monocyte coculture abrogated PD-L1 upregulation. IL-10 mRNA expression in tumor cells and monocytes also preceded PD-L1 mRNA expression in monocytes. Furthermore, the IL-10 concentration in the tumor microenvironment directly correlated with the PD-L1 level on TAMs. Together, these results suggest that OSCC could directly suppress antitumor T cell immunity through conditioning TAMs.     

The role of tumor-associated macrophages in primary hepatocellular carcinoma and its related targeting therapy

Liver macrophages consist of ontogenically distinct populations termed Kupffer cells and monocyte-derived macrophages. Tumor-associated macrophages (TAMs) inhepatocellularcarcinoma (HCC) play a prominent role in tumormicroenvironment by presenting M1(induced by IFN γ along with LPS) and M2(induced by IL-4 and IL13) polarization. Although TAMs are involved in tumor immune surveillance during the course of HCC, they contribute to tumour progression at different levels by inhibiting the anti-tumor immune response, promoting the generation of blood vessels and lymphatic vessels, and supporting the proliferation and survival of tumor cells. In this paper, the multiple functions of TAMs in HCC were reviewed to provide assistance for future researches about therapeutic approaches.     

Expression of galectin-3 in the tumor immune response in colon cancer

The role of tumor-associated macrophages (TAMs) is controversial. Although most studies on different cancer types associate them with a poorer prognosis, interestingly in colon cancer, most articles indicate that TAMs prevent tumor development; patients with high TAMs have better prognosis and survival rate. M1-polarized macrophages produce high level of tumor necrosis factor-alpha, interleukin-1 beta or reactive oxygen species, which can effectively kill susceptible tumor cells. In contrast, M2-polarized macrophages can secrete different factors that promote tumor cell growth and survival or favor angiogenesis and tissue invasion. Considering the beneficial role of TAMs in colon cancer, we speculated that they may not display the M2 polarization commonly observed in tumor microenvironment, but rather develop M1 properties. Therefore, we used an in vitro model to analyze the effects of supernatants from M1-polarized macrophages on DLD-1 colon cancer cells. Our data indicate that the conditioned medium from LPS-activated macrophages (CM-LAM) contains a high level of granulocyte-macrophage colony-stimulating factor, interleukins-1 beta, -6, -8 and tumor necrosis factor-alpha, and that it exerts a marked growth inhibitory activity on DLD-1 cells. Prolonged exposure to CM-LAM results in cell death by apoptosis. Such exposure to CM-LAM leads to the modulation of gal-3 expression: we observed a marked downregulation of gal-3 mRNA and protein expression following CM-LAM treatment. We also describe that the knockdown of gal-3 sensitizes DLD-1 cells to CM-LAM. These data suggest an involvement of gal-3 in the response of colon cancer cells to proinflammatory stimuli, such as the conditioned medium from activated macrophages.     

Diffuse large B cell lymphoma-derived extracellular vesicles educate macrophages to promote tumours progression by increasing PGC-1β

Tumour-associated macrophages (TAMs) comprise an important part of the tumour microenvironment and play a key role in malignant tumours progression. Tumour-derived extracellular vesicles (EVs) modulated TAMs polarization and reprogrammed TAMs to influence the progression of various tumours. Here, we hypothesized that diffuse large B cell lymphoma (DLBCL)-derived EVs can regulate macrophages polarization and thus contribute to tumour progression. Our results demonstrated that EVs, released from DLBCL, augment the M2 polarization effects of macrophages. Moreover, conditional medium derived from macrophages by DLBCL-derived EVs stimulation revealed the superior effects of promoting tumour proliferation, migration and invasion. Further analysis demonstrated that DLBCL-derived EVs regulated the metabolism of macrophages by increasing the expression of PGC-1β protein, thereby reprogramming the macrophage phenotype of promoting tumour progression. In conclusion, our findings signify that the DLBCL-derived EVs mediated the increasing of functional PGC-1β protein in macrophages to promote the tumour progression.     

Role of tumor‐associated macrophages in human malignancies: friend or foe?

Tumor‐associated macrophages (TAMs) play a pivotal role in tumor growth in human malignancies. Published studies have analyzed the relationship between TAM infiltration and the prognosis of patients for many human tumors. Most studies reported a positive correlation between TAM density and a poor prognosis. Studies focusing on macrophage phenotypes emphasized the protumor role of M2 anti‐inflammatory macrophages in many types of human tumors. However, TAMs influence tumor progression in various ways that depend on differences in tumor sites, histology, and microenvironments. In this review, we summarize the function of TAMs in various human malignancies by reviewing the data provided in studies of TAMs in human malignancies.     

Tumor-Associated Macrophages as Target for Antitumor Therapy

It is well known that the microenvironment of solid tumors is rich in inflammatory cells that influence tumor growth and development. Macrophages, called tumor-associated macrophages (TAMs), are the most abundant immune cell population present in tumor tissue. Several studies have demonstrated that the density of TAMs is associated with a poor prognosis and positively correlates with tumor growth. Several studies have proved that TAMs may activate and protect tumor stem cells, stimulate their proliferation as well as promote angiogenesis and metastasis. Furthermore, TAMs-derived cytokines and other proteins, such as CCL-17, CCL-22, TGF-β, IL-10, arginase 1, and galectin-3, make a significant contribution to immunosuppression. Since TAMs influence various aspects of cancer progression, there are many attempts to use them as a target for immunotherapy. The numerous studies have shown that the primary tumor growth and the number of metastatic sites can be significantly decreased by decreasing the population of macrophages in tumor tissue, for example, by blocking recruitment of monocytes or eliminating TAMs already present in the tumor tissue. Moreover, there are attempts at reprogramming TAMs into proinflammatory M1 macrophages or neutralizing the protumoral products of TAMs. Another approach uses TAMs for anticancer drug delivery into the tumor environment. In this review, we would like to summarize the clinical and preclinical trials that were focused on macrophages as a target for anticancer therapies.

     

Macrophage infiltration predicts a poor prognosis for human ewing sarcoma

Ewing sarcoma-primitive neuroectodermal tumor (EWS) is associated with the most unfavorable prognosis of all primary musculoskeletal tumors. The objective of the present study was to investigate whether tumor-associated macrophages (TAMs) affect the development of EWS. TAMs were isolated from mouse xenografts using CD11b magnetic beads and examined for their cytokine expression and osteoclastic differentiation. To evaluate the role of TAMs in xenograft formation, liposome-encapsulated clodronate was used to deplete TAMs in mice. Macrophage infiltration and tumor microvascular density were histologically evaluated in 41 patients with EWS, and association with prognosis was examined using Kaplan-Meier survival analysis. In mouse EWS xenografts, TAMs expressed higher concentrations of cytokines including interleukin-6, keratinocyte-derived chemokine, and monocyte chemotactic protein-1. TAMs were more capable than normal monocytes of differentiating into tartrate-resistant acid phosphatase-positive giant cells. Depleting macrophages using liposome-encapsulated clodronate significantly inhibited development of EWS xenografts. In human EWS samples, higher levels of CD68-positive macrophages were associated with poorer overall survival. In addition, enhanced vascularity, increase in the amount of C-reactive protein, and higher white blood cell counts were also associated with poor prognosis and macrophage infiltration. TAMs seem to enhance the progression of EWS by stimulating both angiogenesis and osteoclastogenesis. Further investigation of the behavior of TAMs may lead to development of biologically targeted therapies for EWS.