肿瘤微环境中肿瘤相关巨噬细胞极化的影响因素及其意义

肿瘤相关巨噬细胞（tumor-associated macrophages, TAMs）具有极高的可塑性，是肿瘤微环境（tumor microenvironment, TME）中含量最丰富的免疫细胞。各种TME成分（如细胞因子、趋化因子以及外泌体等）将TAMs招募到肿瘤区域内。随后，这些环境因子把TAMs诱导为抗肿瘤状态（M1样）或促肿瘤状态（M2样）之间的某一极化状态。另外，TAMs的极化过程是连续的，并且会随着肿瘤恶性进展而逐渐地朝向M2样状态，构成了一个有利于肿瘤生长和转移的正反馈环。因此，深入研究影响TAMs极化的各种因素和机制，有助于研发一种新的且可以与其他免疫治疗相结合的肺癌治疗策略。在既往的研究中已发现了许多可以促进TAMs的M2极化的分子和通路。然而，肿瘤细胞、间质细胞和TAMs之间这种复杂的串扰的潜在机制仍然难以研究清楚。在这篇综述中我们总结了促进TAMs向M2表型极化的各种因素，并进一步探讨了相关的分子机制。     

靶向肿瘤相关巨噬细胞治疗卵巢癌的研究进展

摘 要：肿瘤微环境对卵巢癌的进展具有重要的调控作用。肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）是肿瘤微环境重要的组成部分。众所周知,TAMs通过调节肿瘤微环境在肿瘤进展中发挥重要作用。目前关于TAMs与肿瘤相互作用的模式包括消耗TAMs,减少TAMs募集、削弱TAMs吞噬能力、诱导M2 TAMs凋亡和向M1样表型转化、抑制M2 TAMs的极化、调节TAMs极化等。靶向肿瘤相关巨噬细胞是改善免疫抑制性肿瘤微环境和提高肿瘤免疫治疗的一种有前景的策略。     

lncRNA通过肿瘤相关巨噬细胞极化影响肿瘤生长的机制研究进展

肿瘤的生长转移不仅取决于自身特性，还与其所处的肿瘤微环境（tumor microenvironment，TME）密切相关。肿瘤相关巨噬细胞（tumor-associated macrophages，TAMs)是存在于肿瘤微环境中的一类重要免疫细胞，多数为免疫抑制的极化M2型，少数为免疫激活的极化M1型，在肿瘤发生发展过程中发挥着重要作用，但其极化过程的调控机制仍不十分清楚。长链非编码RNA（long non-coding RNA，lncRNA）作为重要的非编码RNA，可直接影响肿瘤细胞的生长，近年来越来越多研究发现TAMs中或TAMs外的lncRNA可对TAMs极化产生影响，间接调控肿瘤的生长、血管形成、转移和代谢等。因此，针对lncRNA调控TAMs极化过程进行靶向干预，逆转M2极化，有望成为肿瘤治疗的新靶点，TAMs中lncRNA的表达谱也可成为肿瘤诊断或预后判定的重要生物学指标。     

肿瘤相关巨噬细胞在肺癌中的作用及研究进展

肿瘤相关巨噬细胞（TAMs）是肿瘤微环境中重要的炎性细胞。在各种不同刺激因子的作用下，TAMs可分化为经典活化型（M1）和交替活化型（M2）。M1-TAMs具有抑制恶性肿瘤活性的作用，M2-TAMs具有促进恶性肿瘤发展的作用。研究表明，肿瘤组织中的TAMs主要为M2型，可分泌多种趋化因子和细胞因子，从而促进肿瘤的增殖、侵袭转移、血管生成和耐药，并降低机体对肿瘤的免疫作用。本文将对TAMs的表型及其在肺癌中作用机制的新进展进行综述。     

TAMs为靶点的抗肿瘤治疗研究进展

肿瘤微环境与肿瘤细胞通过分子和细胞间的相互作用,在肿瘤的发生发展和转移扩散中具有重要意义。肿瘤相关巨噬细胞（TAMs）作为肿瘤微环境中数量最多的炎症细胞群之一,在肿瘤进展中起到重要作用。肿瘤细胞通过释放多种趋化因子、细胞因子和生长因子招募巨噬细胞,并使其向M2型巨噬细胞类似的特性发展。同时,巨噬细胞释放多种因子,促进肿瘤细胞的生长、血管新生、迁移、侵袭、侵入血管并最终形成远处转移。TAMs在肿瘤组织中的密度与肿瘤患者治疗失败和不良预后密切相关,以TAMs为靶点的抗肿瘤治疗相关研究近年来取得重大进展。在肿瘤发生发展中根据TAMs的作用机制,以TAMs为靶点的抗肿瘤治疗策略是抑制肿瘤微环境中巨噬细胞招募、TAMs生存能力、TAMs表型即由M2型转化为M1型的重塑。本文就TAMs为靶点的抗肿瘤治疗最新进展进行综述。      

肿瘤相关巨噬细胞在胃癌中的作用

巨噬细胞广泛参与固有免疫及适应性免疫,其表型和功能具有很大可塑性,在不同微环境中巨噬细胞可分化为经典活化（M1表型）和替代活化（M2表型）,其中M2表型有免疫调节作用,参与诱导Th2反应。肿瘤微环境浸润的巨噬细胞即肿瘤相关巨噬细胞（TAMs）多具M2表型,能促进肿瘤新生血管生成、肿瘤侵袭和转移。由此可见,TAMs对胃癌的发生发展具有重要的免疫调节作用,本文就此进行综述。      

肿瘤相关巨噬细胞糖代谢重编程及靶向治疗

肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）作为肿瘤微环境（tumor microenvironment,TME）中重要的免疫细胞,具有高度异质性及可塑性,在肿瘤细胞分泌的细胞因子刺激下,可发生表型、代谢及功能变化。TAMs代谢改变以糖代谢重编程为主,M1型TAMs有氧糖酵解、磷酸戊糖途径增强,三羧酸循环减弱,具有抗肿瘤功能;M2型TAMs具有完整的三羧酸循环,可促进肿瘤进展。而在TME作用下TAMs具有多种表现形式,其糖代谢重编程可影响肿瘤迁移、侵袭及血管生成,而具体作用机制尚不明确。本文旨在探讨TAMs糖代谢重编程作用机制及其与肿瘤免疫相关性,提示TME中TAMs糖代谢重编程对肿瘤发展和靶向治疗有重要意义,可为肿瘤治疗提供新思路。     

肿瘤相关巨噬细胞在结直肠癌中的研究进展

肿瘤的进展和转移不仅与肿瘤自身的特性有关, 还与肿瘤所处的微环境密不可分。肿瘤相关巨噬细胞(tumor-associated macrophages, TAMs)是肿瘤微环境中数量最多的肿瘤相关炎性细胞, 在不同的信号刺激下可分化成抗肿瘤的M1型巨噬细胞或促肿瘤的M2型巨噬细胞。在许多恶性肿瘤中, TAMs被证实参与了肿瘤的进展和转移, M2型巨噬细胞较多。然而在结直肠癌中, 大部分研究却得出了相反的结论, 认为TAMs促进了炎症的发展, 抑制了肿瘤的进展和转移。但一些体内和体外实验却发现TAMs促进了结肠癌的增殖和转移, M2型巨噬细胞居多。此外, 还有研究发现在结直肠癌中TAMs的功能随位置、肿瘤分期的不同而变化, 而且并不以单纯的M1或M2形式存在, 往往同时表现出M1和M2的一些特点。本文就TAMs在结直肠癌中的研究现状做一综述, 以期全面了解TAMs在结直肠癌中的作用, 为进一步深入研究二者的关系提供线索。      

肿瘤相关巨噬细胞：调节肿瘤微环境的新靶点

肿瘤相关巨噬细胞(tumor-associated macrophage,TAM)在肺癌免疫微环境中扮演着重要的角色。它们通过自身的表型和吞噬功能的变化,在肺癌的发生和进展中发挥作用,通过促进肺癌免疫抑制型微环境的形成和肿瘤异常血管的生长加速肺癌的侵袭和扩散。巨噬细胞在应对不同刺激时,可以极化为具有不同功能和特征的亚型,分为抗肿瘤M1型和促肿瘤的M2型。在肿瘤组织中,TAM通常极化为交替活化型的M2表型,表现出对肿瘤免疫的抑制作用。本文综述了抗血管生成药物在调节TAM表型方面的作用,它们可以通过将M2型TAM重编程为M1型来发挥抗肿瘤作用。同时,TAM的功能改变在抗血管生成治疗和免疫治疗策略中也起到重要作用。研究证实,TAM通过极化及功能改变可能成为调节肿瘤微环境的新靶点,开辟肺癌治疗的新途径。     

IL-8诱导的肿瘤相关巨噬细胞对肝细胞肝癌侵袭转移的影响

  目的  探究外源性IL-8对单核细胞的活化作用及IL-8活化后的肿瘤相关巨噬细胞（tumor-associated macrophages,TAMs）对肝细胞肝癌（hepatocellular carcinoma,HCC）侵袭转移的影响。  方法  外源性IL-8刺激THP-1细胞后检测M1、M2型TAMs的比例。IL-8活化的TAMs与HCC细胞共孵育,利用RT-PCR和Western blot法检测TAMs对HCC细胞上皮间质转化（epithelial-mesenchymal transition,EMT）的影响;利用划痕修复实验和Transwell侵袭实验探究TAMs对HCC细胞侵袭转移的影响;并在100例HCC样本中进行组织水平验证。  结果  外源性IL-8可诱导THP-1细胞的表型向M2型TAMs方向分化。IL-8体外诱导的TAMs可以反作用于HCC,促使其发生EMT,进而促进其侵袭转移。在HCC组织中证实IL-8与TAMs浸润呈明显的正相关（r=0.22,P < 0.05）,同时浸润的TAMs与神经细胞型钙黏蛋白（N-cadherin）的表达量呈正相关（r=0.20,P < 0.05）。  结论  在HCC中,IL-8可以趋化TAMs浸润并促进其活化,活化后的TAMs可促进HCC细胞EMT和侵袭转移。      

Metformin prevents cancer metastasis by inhibiting M2-like polarization of tumor associated macrophages

Accumulated evidence suggests that M2-like polarized tumor associated macrophages (TAMs) plays an important role in cancer progression and metastasis, establishing TAMs, especially M2-like TAMs as an appealing target for therapy intervention. Here we found that metformin significantly suppressed IL-13 induced M2-like polarization of macrophages, as illustrated by reduced expression of CD206, down-regulation of M2 marker mRNAs, and inhibition of M2-like macrophages promoted migration of cancer cells and endothelial cells. Metformin triggered AMPKα1 activation in macrophage and silencing of AMPKα1 partially abrogated the inhibitory effect of metformin in IL-13 induced M2-like polarization. Administration of AICAR, another activator of AMPK, also blocked the M2-like polarization of macrophages. Metformin greatly reduced the number of metastases of Lewis lung cancer without affecting tumor growth. In tumor tissues, the percentage of M2-like macrophage was decreased and the area of pericyte-coated vessels was increased. Further, the anti-metastatic effect of metformin was abolished when the animals were treated with macrophages eliminating agent clodronate liposome. These findings suggest that metformin is able to block the M2-like polarization of macrophages partially through AMPKα1, which plays an important role in metformin inhibited metastasis of Lewis lung cancer.     

Depletion of tumor-associated macrophages inhibits lung cancer growth and enhances the antitumor effect of cisplatin

In lung cancer, tumor-associated macrophages (TAMs), especially M2-like TAMs, represent the main tumor progression components in the tumor microenvironment (TME). Therefore, M2-like TAMs may serve as a therapeutic target. The purpose of this study was to investigate the effect of M2-like TAM depletion in the TME on tumor growth and chemotherapy response in lung cancer. The levels of secreted monocyte chemoattractant protein (MCP-1) and prostaglandin E2 (PGE2) in the supernatants of lung cancer cell lines A549 and LLC were evaluated via ELISA. Cell migration assays were performed to assess the recruitment ability of macrophage cell lines THP-1 and J774-1 cells. Differentiation of macrophages was assessed via flow cytometry. Immunohistochemical staining was performed to visualize M2-like TAMs in transplanted lung cancer in mouse. We used the COX-2 inhibitor nimesulide to inhibit the secretion of MCP-1 and PGE2, which promotes macrophage migration and M2-like differentiation. Nimesulide treatment decreased the secretion of MCP-1 and PGE2 from lung cancer cells. Nimesulide treatment suppressed the migration of macrophages by blocking MCP-1. Lung cancer supernatant induced the differentiation of macrophages toward the M2-like phenotype, and nimesulide treatment inhibited M2-like differentiation by blocking MCP-1 and PGE2. In the lung cancer mouse model, treatment with nimesulide depleted M2-like TAMs in the TME and enhanced the tumor inhibitory effect of cisplatin. Our results indicated that blocking the secretion of MCP-1 and PGE2 from tumor cells depleted M2-like TAMs in the TME and the combination therapy with cisplatin considerably suppressed tumor growth in the LLC mouse model.     

唑来膦酸通过NF-κB信号通路调控肺癌细胞的增殖和耐药

目的:探究唑来膦酸对肿瘤相关巨噬细胞（TAMs）表型转化和HGF表达的作用及对肺癌细胞增殖和耐药的影响。方法:通过Transwell系统将M2巨噬细胞与小鼠肺癌细胞Lewis共培养,得到M2型TAM(M2-TAMs)。采用不同浓度唑来膦酸作用于M2-TAMs,采用ELISA和RT-PCR检测M1型标记（IL-1β、TNFα、IL-6和iNOS）、M2型标记（HGF、EGF、IL-10和Arg1）的表达改变,采用Western blot检测NF-κB的表达。建立Transwell M2-TAMs-Lewis共培养模型,采用MTT方法检测肿瘤细胞的增殖和对吉非替尼耐药的影响;采用NF-κB特异性抑制剂PDCT作用唑来膦酸处理的TAMs,进一步检测TAMs M1/M2表型改变。结果:随着唑来膦酸浓度的增加,TAMs M1表型显著增强,M2表型逐渐减弱;与对照组相比,唑来膦酸处理的TAMs显著抑制了肺癌细胞的增殖,增强了其对吉非替尼的敏感性。在NF-κB特异性抑制剂（PDTC）的作用下,唑来膦酸处理的TAMs M1表型减弱,而M2表型增强。结论:唑来膦酸通过活化NF-κB信号通路促进肿瘤相关巨噬细胞M1表型转化并抑制肺癌细胞的增殖和耐药。     

乳腺癌微环境中巨噬细胞相关因子与环氧化酶-2的调节

肿瘤微环境中浸润的巨噬细胞(tumor-associated macrophages, TAMs)是近年来癌症治疗的新靶点。TAMs通过分泌大量促癌细胞因子如血管内皮生长因子、白细胞介素、基质金属蛋白酶等, 促进肿瘤细胞增殖、侵袭和转移。炎症因子环氧化酶-2(cyclooxygenase-2, COX-2)参与了微环境中血管形成和免疫调节, 加速肿瘤进程, 也是乳腺癌治疗的有力靶点。而COX-2抑制剂如塞来昔布, 在抑制TAMs活性和改善肿瘤微环境方面具有较大潜力。因此, 本文就乳腺癌微环境中TAMs分泌的重要细胞因子与COX-2的相互关系加以讨论, 分析其对应的拮抗剂单独或与COX-2抑制剂联合的使用价值, 旨在为选择多靶点联合阻断TAMs活性的研究提供理论基础, 也为乳腺癌的生物靶向治疗提供新方向。      

HRG inhibits tumor growth and metastasis by inducing macrophage polarization and vessel normalization through downregulation of PlGF

Polarization of tumor-associated macrophages (TAMs) to a proangiogenic/immune-suppressive (M2-like) phenotype and abnormal, hypoperfused vessels are hallmarks of malignancy, but their molecular basis and interrelationship remains enigmatic. We report that the host-produced histidine-rich glycoprotein (HRG) inhibits tumor growth and metastasis, while improving chemotherapy. By skewing TAM polarization away from the M2- to a tumor-inhibiting M1-like phenotype, HRG promotes antitumor immune responses and vessel normalization, effects known to decrease tumor growth and metastasis and to enhance chemotherapy. Skewing of TAM polarization by HRG relies substantially on downregulation of placental growth factor (PlGF). Besides unveiling an important role for TAM polarization in tumor vessel abnormalization, and its regulation by HRG/PlGF, these findings offer therapeutic opportunities for anticancer and antiangiogenic treatment.     

Cyclooxygenase-2 in tumor-associated macrophages promotes breast cancer cell survival by triggering a positive-feedback loop between macrophages and cancer cells

Tumor-associated macrophages (TAMs) play an important role in cancer cell survival, however, the mechanism of which remains elusive. In this study, we found that COX-2 was abundantly expressed in breast TAMs, which was correlated to poor prognosis in breast cancer patients. Ectopic over-expression of COX-2 in TAMs enhanced breast cancer cell survival both in vitro and in vivo. COX-2 in TAMs was determined to be essential for the induction and maintenance of M2-phenotype macrophage polarity. COX-2⁺ TAMs promoted breast cancer cell proliferation and survival by increasing Bcl-2 and P-gp and decreasing Bax in cancer cells. Furthermore, COX-2 in TAMs induced the expression of COX-2 in breast cancer cells, which in turn promoted M2 macrophage polarization. Inhibiting PI3K/Akt pathway in cancer cells suppressed COX-2⁺ TAMs-induced cancer cell survival. These findings suggest that COX-2, functions as a key cancer promoting factor by triggering a positive-feedback loop between macrophages and cancer cells, which could be exploited for breast cancer prevention and therapy.     

Role of tumor-associated macrophages at the invasive front in human colorectal cancer progression

Macrophages are an essential component of antitumor activity; however, the role of tumor-associated macrophages (TAMs) in colorectal cancer (CRC) remains controversial. Here, we elucidated the role of TAMs in CRC progression, especially at the early stage. We assessed the TAM number, phenotype, and distribution in 53 patients with colorectal neoplasia, including intramucosal neoplasia, submucosal invasive colorectal cancer (SM-CRC), and advanced cancer, using double immunofluorescence for CD68 and CD163. Next, we focused on the invasive front in SM-CRC and association between TAMs and clinicopathological features including lymph node metastasis, which were evaluated in 87 SM-CRC clinical specimens. The number of M2 macrophages increased with tumor progression and dynamic changes were observed with respect to the number and phenotype of TAMs at the invasive front, especially at the stage of submucosal invasion. A high M2 macrophage count at the invasive front was correlated with lymphovascular invasion, low histological differentiation, and lymph node metastasis; a low M1 macrophage count at the invasive front was correlated with lymph node metastasis. Furthermore, receiver operating characteristic curve analysis revealed that the M2/M1 ratio was a better predictor of the risk of lymph node metastasis than the pan-, M1, or M2 macrophage counts at the invasive front. These results suggested that TAMs at the invasive front might play a role in CRC progression, especially at the early stages. Therefore, evaluating the TAM phenotype, number, and distribution may be a potential predictor of metastasis, including lymph node metastasis, and TAMs may be a potential CRC therapeutic target.