胚胎来源巨噬细胞的起源及其在肝脏中功能的研究进展

王咪咪， 王艳红

复旦大学附属中山医院肝内科，上海 200032

巨噬细胞是机体免疫系统的重要组成部分，其表型和功能具有高度异质性[1-2]。组织定居巨噬细胞长期存在于机体各组织器官，如肝脏中的枯否细胞、肺组织中的肺泡巨噬细胞、表皮中的朗格汉斯细胞、骨组织中的破骨细胞等，参与机体的免疫监视、免疫防御、免疫自稳，具有组织特异性。早期研究认为，组织定居巨噬细胞来源于成体骨髓单核细胞；而最新研究发现，大部分组织的定居巨噬细胞是在胚胎时期由胚胎前体细胞分化而来的，这种胚胎来源巨噬细胞(EDMs)可以通过自我增殖维持数量和功能稳定[3]。这一发现给巨噬细胞领域提供了新的研究方向。因此，本文将对肝脏中胚胎来源的组织定居巨噬细胞的起源和功能进行综述，并由此思考和讨论目前巨噬细胞靶向治疗的不足和发展方向。

1 组织定居巨噬细胞的起源

组织定居巨噬细胞一直被认为是由成体骨髓单核细胞分化而来的，即骨髓中的造血干细胞分化为单核细胞，后者通过血液循环按照不同的周期进入不同的组织器官，分化为组织定居巨噬细胞。随着细胞发育制图技术[4]等新技术的研究应用，对组织定居巨噬细胞的起源有了新的认识。一般认为，在出生之前，胚胎前体细胞就已分化形成组织定居巨噬细胞，称为EDMs。这种细胞的发育途径主要分为3个连续的造血波[5]，分别命名为原始造血、暂时决定性造血和决定性造血，分别起源于中胚层背侧板胚外卵黄囊中的血岛、卵黄囊生血内皮细胞和胚胎内生血内皮细胞在主动脉旁脏壁层区域产生的未成熟的造血干细胞，分别产生卵黄囊巨噬细胞、胎肝单核细胞来源的巨噬细胞和胎肝单核细胞。它们都可在机体出生前迁移至器官组织中直接增殖或分化为组织定居巨噬细胞。

2 EDMs的自我更新与稳态维持

“自我更新”是广泛应用于干细胞的概念，即在长期不断的增殖过程中，子细胞仍能保留母细胞特性[3]。静息状态下，大部分组织器官(肠、皮肤、心脏、胰腺等)中EDMs无法单独通过局部自我增殖以维持数量，需要骨髓造血干细胞的分化补充[5]。因此，大部分组织定居巨噬细胞群由EDMs和骨髓单核细胞来源的巨噬细胞共同构成。而肝组织定居巨噬细胞的来源中，EDMs占绝大多数，并通过局部自我更新和增殖维持数量，而不依赖于骨髓单核细胞的补充。有研究[6]报道，肝EDMs的自我更新功能在肝脏微环境稳态下可以长期保持，不随年龄增长而逐渐消失。但当其离开肝脏微环境，就会丧失自我更新功能[7]。

当机体遇到刺激后，EDMs会发生不同程度的坏死，严重时候数量甚至会降至为0(消失期)[8-9]，再通过局部自我增殖恢复数量。由于刺激因素的种类、强度、时间的不同，其恢复水平和能力会有所变化。研究显示，非基因毒性刺激(如白喉毒素、氯磷酸二钠脂质体或寄生虫感染)下，EDMs可局部自我增殖，并在IL-4的作用下极化为M2型，此时不需要骨髓单核细胞的分化补充[10-11]；而基因毒性(如致死性放射、骨髓移植[11])，李斯特菌、沙门杆菌等胞内菌感染，病毒感染等刺激下，坏死的巨噬细胞可通过分泌CCL2等趋化因子，诱导单核细胞浸润肝组织，从而代替EDMs，形成新的组织定居巨噬细胞[8-9,12-13]，此后，肝脏定居巨噬细胞池的构成比例发生变化，维持稳态的能力下降。另外，动物实验[14]表明，如果调整刺激强度(细菌载量或放射剂量)，肝脏内会出现EDMs与骨髓来源的巨噬细胞嵌合的状态。以上3种情况显示，一旦稳态被打破，巨噬细胞池的构成将根据微环境的不同而发生变化，进而导致不同表现的炎症反应。

3 EDMs介导炎症反应

在肝脏中，EDMs位于肝血窦内，黏附于肝血窦内皮细胞上，直接暴露在血液中，是对损伤或刺激产生反应的一线细胞[15]，较骨髓单核系统来源的巨噬细胞能够更快速更有效地吞噬衰老细胞、细菌、病毒等。EDMs通过其强大的吞噬功能，控制有害物质播散[16-18]，减少过度炎症反应对肝脏造成的损伤[16]。

病毒、细菌和坏死的肝细胞均能释放损伤相关分子模式(DAMPs)、病原体相关分子模式(PAMPs)，后者通过与清道夫受体(SPs)、toll样受体(TLRs)、髓细胞触发受体-1(TREM-1)[19]等模式受体结合激活EDMs，使其极化为M1型巨噬细胞，并分泌白细胞介素1(IL-1)、IL-6、肿瘤坏死因子-α(TNF-α)和粒细胞-巨噬细胞集落刺激因子(GM-CSF)等促炎因子[20]。此外，一些胞内菌(如李斯特菌、沙门杆菌)、X线照射或N-乙酰对氨基苯酚[21]等会导致EDMs大量坏死进而激发单核细胞、中性粒细胞的浸润[8,22]，介导炎症反应的发生。

随着炎症反应的进展，EDMs会介导抗炎症反应。EDMs可通过分泌TNF，促进中性粒细胞的凋亡，进而吞噬凋亡的中性粒细胞[23]。对凋亡中性粒细胞的吞噬又可促进EDMs产生脂质介质如脂氧素[24]等，抑制中性粒细胞的进一步浸润，从而控制过度炎症反应。此外，坏死的EDMs可通过产生IL-1β诱导肝细胞分泌IL-33，进而刺激嗜酸性粒细胞分泌IL-4；而IL-4能诱导单核来源的巨噬细胞从M1型转化为M2型[8]，同时可作用于尚存的EDMs，使其局部增殖并分化为M2型巨噬细胞，后者通过分泌IL-10，活化精氨酸酶，进而刺激单核细胞来源的M1型巨噬细胞的凋亡[25]。M2型巨噬细胞能通过分泌大量抗炎因子，如TGF-β、IL-10等，削弱炎症反应，介导免疫耐受[26]。

总之，及时、适度的炎症有利于清除病原体、凋亡坏死的细胞以及细胞碎片等，而过度的炎症反应或者持续的慢性炎症则是恶性病变的重要危险因素[27-29]。EDMs在平衡炎症反应和免疫恢复中发挥举足轻重的作用，能够有效避免病变的发生。

4 EDMs影响HCC和循环肿瘤细胞在肝脏中的生长

炎症与肿瘤息息相关，巨噬细胞是炎症相关的重要细胞[30]。其中，位于肿瘤组织内或肿瘤周围组织的肿瘤相关性巨噬细胞(TAMs)[31-34]是一类分化终末期的巨噬细胞[35]。TAMs显示与M2型相似的分子功能谱[36-37]，在HCC的发展和转移过程中起至关重要的作用[38-40]。有文献[41-42]认为，TAMs是由骨髓单核细胞分化并在肿瘤微环境内极化为M2型的髓系巨噬细胞。关于肿瘤组织中EDMs的功能的相关报道不多。有实验[43]显示，HCC微环境中，EDMs的抗原递呈功能下降、CD86和主要组织相容性复合体Ⅱ分子(MHC-Ⅱ)表达下降、细胞程序死亡配体1(PD-L1)表达上升。肿瘤中髓系来源的抑制细胞(MDSCs)作用于EDMs，抑制其分泌CCL2和IL-18，而促进其分泌IL-10和IL-1β，并使其表面正性和负性共刺激分子失平衡，从而促进HCC的发展。

虽然EDMs在肿瘤发展后期呈现促进肿瘤生长和转移的作用。但作为一线免疫细胞又具有抵抗循环肿瘤细胞进入肝脏的作用[44-48]。其机制主要有：直接吞噬作用[44-50]，降低肿瘤细胞对肝窦的黏附[45]；通过释放一氧化氮和活性氧来上调死亡因子配体(FASL)，诱导肿瘤细胞的凋亡[51]；通过分泌细胞因子如IL-1、IL-6、IL-8、TNF-α、γ-干扰素(IFN-γ)，或趋化因子MIP-2、IP-10、KC/GRO、MIP-1α、MCP-1等，激活自然杀伤细胞(NK)[52]和中性粒细胞[51]，进而杀死循环肿瘤细胞。

然而，转移灶或预转移龛的微环境可以抑制EDMs吞噬杀伤循环肿瘤细胞的功能。研究[53-54]报道，在结直肠肿瘤肝转移中，当骨髓髓系细胞被募集到转移灶时，此时预转移龛、肿瘤微环境已经开始建立，大部分单核细胞不能分化为巨噬细胞，滞留为MDSCs，后者通过上调EDMs表面的负性T细胞共刺激分子PD-L1[53-54]，抑制其吞噬效能[46]。

5 EDMs靶向治疗的挑战

目前靶向巨噬细胞的多种抗肿瘤药物[55-57]已被逐渐研发，有些已经进入临床试验阶段，表现出良好的临床效果。这些药物的作用靶点及机制有减少单核细胞浸润、抑制单核来源巨噬细胞的增殖、控制单核细胞的分化成熟、消融巨噬细胞、增强巨噬细胞吞噬功能、调控巨噬细胞的极化方向、对促进肿瘤发展的巨噬细胞进行再教育。

上述策略大多针对单核细胞及其来源的巨噬细胞，不适用于EDMs。EDMs表面不表达CXCR3和CCR2[58]，阻断CCL2-CCR2并不影响EDMs的局部增殖。两种来源的巨噬细胞有相互补充的现象。当阻断CCL2/CCR2[59]或CSF1/CSF1R信号通路后，循环系统无法及时供给足够的巨噬细胞，肝脏定居的EDMs可通过自我增殖补充巨噬细胞池，从而构造免疫抑制的肿瘤微环境，削弱这条机制靶向的抗肿瘤作用。因此，对两种来源的巨噬细胞同时进行消融、极化和再教育将是巨噬细胞靶向药的研究方向。

此外，多种治疗性单克隆抗体通过抗体依赖细胞介导的细胞毒作用(ADCC)介导巨噬细胞吞噬，可以有效地杀伤肿瘤细胞[60-61]。提高巨噬细胞吞噬功能的抗肿瘤药物也在动物研究中取得了显著效果，如抗CD47抗体[62-64]。

然而，这些研究忽略了巨噬细胞的来源，而不同来源的巨噬细胞的吞噬功能不同。研究[48]指出，EDMs具有独特的Dectin-2依赖的吞噬活性。淋巴细胞脉络丛脑膜炎病毒(LCMV)感染的动物模型的研究[65]结果显示，EDMs的吞噬水平保持稳态，而单核细胞的吞噬功能则显著受损。EDMs能更有效地吞噬乙酰化的低密度脂蛋白，而对细菌的吞噬能力则不如单核细胞来源巨噬细胞[14]。最新研究[66]发现，免疫检查点抑制剂通过拮抗TAMs表面的PD-1，加强其对肿瘤细胞的吞噬，而这些TAMs经实验证实属于单核细胞来源，而非胚胎来源。因而，对不同来源巨噬细胞吞噬功能的深入探索可为抗体治疗和免疫治疗提供更广阔的视野。

6 小 结

肝脏定居巨噬细胞占非实质细胞的35%，占全身组织定居巨噬细胞的80%～90%[23]。因此，巨噬细胞是肝脏维持稳态、参与炎症反应、调控生理和病理变化的重要成员。近年来，对于肝脏EDMs的起源、维持稳态以及介导炎症反应等生理或病理功能的研究有了一定的进展，但对于其在HCC微环境中的表型和功能仍有待进一步的探索。阐明EDMs在各种不同的生理或病理状态下的反应和功能，不仅可以为靶向巨噬细胞治疗提供新的思路，也有利于临床对肝脏相关疾病病因认识的提高和治疗方法的改进。

[ 1 ] AVADANEI E R, WIERZBICKI P M, GIUSCA S E, et al. Macrophage profile in primary versus secondary liver tumors[J]. Folia Histochem Cytobiol, 2014,52(2):112-123.

[ 2 ] KITAMURA T, QIAN B Z, POLLARD J W. Immune cell promotion of metastasis[J]. Nat Rev Immunol, 2015,15(2):73-86.

[ 3 ] SIEWEKE M H, ALLEN J E. Beyond stem cells: self-renewal of differentiated macrophages[J]. Science, 2013,342(6161):1242974.

[ 4 ] JUNG S, ALIBERTI J, GRAEMMEL P, et al. Analysis of fractalkine receptor CX(3)CR1 function by targeted deletion and green fluorescent protein reporter gene insertion[J]. Mol Cell Biol, 2000,20(11):4106-4114.

[ 5 ] GINHOUX F, GUILLIAMS M. Tissue-resident macrophage ontogeny and homeostasis[J]. Immunity, 2016,44(3):439-449.

[ 6 ] LAVINE K J, EPELMAN S, UCHIDA K, et al. Distinct macrophage lineages contribute to disparate patterns of cardiac recovery and remodeling in the neonatal and adult heart[J]. Proc Natl Acad Sci U S A, 2014,111(45):16029-16034.

[ 7 ] VAN DE LAAR L, SAELENS W, DE PRIJCK S, et al. Yolk sac macrophages, fetal liver, and adult monocytes can colonize an empty niche and develop into functional tissue-resident macrophages[J]. Immunity, 2016,44(4):755-768.

[ 8 ] BLERIOT C, DUPUIS T, JOUVION G, et al. Liver-resident macrophage necroptosis orchestrates type 1 microbicidal inflammation and type-2-mediated tissue repair during bacterial infection[J]. Immunity, 2015,42(1):145-158.

[ 9 ] MOLAWI K, SIEWEKE M H. Monocytes compensate Kupffer cell loss during bacterial infection[J]. Immunity, 2015,42(1):10-12.

[10] JENKINS S J, RUCKERL D, COOK P C, et al. Local macrophage proliferation, rather than recruitment from the blood, is a signature of TH2 inflammation[J]. Science, 2011,332(6035):1284-1288.

[11] HASHIMOTO D, CHOW A, NOIZAT C, et al. Tissue-resident macrophages self-maintain locally throughout adult life with minimal contribution from circulating monocytes[J]. Immunity, 2013,38(4):792-804.

[12] DAVIES L C, ROSAS M, JENKINS S J, et al. Distinct bone marrow-derived and tissue-resident macrophage lineages proliferate at key stages during inflammation[J]. Nat Commun, 2013,4:1886.

[13] MURRAY P J, WYNN T A. Protective and pathogenic functions of macrophage subsets[J]. Nat Rev Immunol, 2011,11(11):723-737.

[14] BEATTIE L, SAWTELL A, MANN J, et al. Bone marrow-derived and resident liver macrophages display unique transcriptomic signatures but similar biological functions[J]. J Hepatol, 2016,65(4):758-768.

[15] MAYORAL M R, JOHNSON A M, OSBORN O, et al. Distinct hepatic macrophage populations in lean and obese mice[J]. Front Endocrinol (Lausanne), 2016,7:152.

[16] LANG P A, RECHER M, HONKE N, et al. Tissue macrophages suppress viral replication and prevent severe immunopathology in an interferon-I-dependent manner in mice[J]. Hepatology, 2010,52(1):25-32.

[17] XU L, YIN W, SUN R, et al. Kupffer cell-derived IL-10 plays a key role in maintaining humoral immune tolerance in hepatitis B virus-persistent mice[J]. Hepatology, 2014,59(2):443-452.

[18] BOLTJES A, MOVITA D, BOONSTRA A, et al. The role of Kupffer cells in hepatitis B and hepatitis C virus infections[J]. J Hepatol, 2014,61(3):660-671.

[19] WU J, LI J, SALCEDO R, et al. The proinflammatory myeloid cell receptor TREM-1 controls Kupffer cell activation and development of hepatocellular carcinoma[J]. Cancer Res, 2012,72(16):3977-3986.

[20] SICA A, INVERNIZZI P, MANTOVANI A. Macrophage plasticity and polarization in liver homeostasis and pathology[J]. Hepatology, 2014,59(5):2034-2042.

[21] ZIGMOND E, SAMIA-GRINBERG S, PASMANIK-CHOR M, et al. Infiltrating monocyte-derived macrophages and resident kupffer cells display different ontogeny and functions in acute liver injury[J]. J Immunol, 2014,193(1):344-353.

[22] TOSELLO-TRAMPONT A C, LANDES S G, NGUYEN V, et al. Kuppfer cells trigger nonalcoholic steatohepatitis development in diet-induced mouse model through tumor necrosis factor-alpha production[J]. J Biol Chem, 2012,287(48):40161-40172.

[23] JENNE C N, KUBES P. Immune surveillance by the liver[J]. Nat Immunol, 2013,14(10):996-1006.

[24] SOEHNLEIN O, LINDBOM L. Phagocyte partnership during the onset and resolution of inflammation[J]. Nat Rev Immunol, 2010,10(6):427-439.

[25] WAN J, BENKDANE M, TEIXEIRA-CLERC F, et al. M2 Kupffer cells promote M1 Kupffer cell apoptosis: a protective mechanism against alcoholic and nonalcoholic fatty liver disease[J]. Hepatology, 2014,59(1):130-142.

[26] ZHANG M, XU S, HAN Y, et al. Apoptotic cells attenuate fulminant hepatitis by priming Kupffer cells to produce interleukin-10 through membrane-bound TGF-beta[J]. Hepatology, 2011,53(1):306-316.

[27] BRENNER C, GALLUZZI L, KEPP O, et al. Decoding cell death signals in liver inflammation[J]. J Hepatol, 2013,59(3):583-594.

[28] TOSELLO-TRAMPONT A C, LANDES S G, NGUYEN V, et al. Kuppfer cells trigger nonalcoholic steatohepatitis development in diet-induced mouse model through tumor necrosis factor-alpha production[J]. J Biol Chem, 2012,287(48):40161-40172.

[29] SERHAN C N. Pro-resolving lipid mediators are leads for resolution physiology[J]. Nature, 2014,510(7503):92-101.

[30] GONDA T A, TU S, WANG T C. Chronic inflammation, the tumor microenvironment and carcinogenesis[J]. Cell Cycle, 2009,8(13):2005-2013.

[31] DONG P, MA L, LIU L, et al. CD86+/CD206+, diametrically polarized tumor-associated macrophages, predict hepatocellular carcinoma patient prognosis[J]. Int J Mol Sci, 2016,17(3):320.

[32] CAPECE D, FISCHIETTI M, VERZELLA D, et al. The inflammatory microenvironment in hepatocellular carcinoma: a pivotal role for tumor-associated macrophages[J]. Biomed Res Int, 2013,2013:187204.

[33] WAN S, ZHAO E, KRYCZEK I, et al. Tumor-associated macrophages produce interleukin 6 and signal via STAT3 to promote expansion of human hepatocellular carcinoma stem cells[J]. Gastroenterology, 2014,147(6):1393-1404.

[34] FAN Q M, JING Y Y, YU G F, et al. Tumor-associated macrophages promote cancer stem cell-like properties via transforming growth factor-beta1-induced epithelial-mesenchymal transition in hepatocellular carcinoma[J]. Cancer Lett, 2014,352(2):160-168.

[35] POLLARD J W. Trophic macrophages in development and disease[J]. Nat Rev Immunol, 2009,9(4):259-270.

[36] BISWAS S K, GANGI L, PAUL S, et al. A distinct and unique transcriptional program expressed by tumor-associated macrophages (defective NF-kappaB and enhanced IRF-3/STAT1 activation)[J]. Blood, 2006,107(5):2112-2122.

[37] MANTOVANI A, SICA A. Macrophages, innate immunity and cancer: balance, tolerance, and diversity[J]. Curr Opin Immunol, 2010,22(2):231-237.

[38] RUFFELL B, AFFARA N I, COUSSENS L M. Differential macrophage programming in the tumor microenvironment[J]. Trends Immunol, 2012,33(3):119-126.

[39] YEUNG O W, LO C M, LING C C, et al. Alternatively activated (M2) macrophages promote tumour growth and invasiveness in hepatocellular carcinoma[J]. J Hepatol, 2015,62(3):607-616.

[40] AMBADE A, SATISHCHANDRAN A, SAHA B, et al. Hepatocellular carcinoma is accelerated by NASH involving M2 macrophage polarization mediated by hif-1alphainduced IL-10[J]. Oncoimmunology, 2016,5(10):e1221557.

[41] KANG T W, YEVSA T, WOLLER N, et al. Senescence surveillance of pre-malignant hepatocytes limits liver cancer development[J]. Nature, 2011,479(7374):547-551.

[42] LI X, YAO W, YUAN Y, et al. Targeting of tumour-infiltrating macrophages via CCL2/CCR2 signalling as a therapeutic strategy against hepatocellular carcinoma[J]. Gut, 2017,66(1):157-167.

[43] LACOTTE S, SLITS F, ORCI L A, et al. Impact of myeloid-derived suppressor cell on Kupffer cells from mouse livers with hepatocellular carcinoma[J]. Oncoimmunology, 2016,5(11):e1234565.

[44] TANAKA K, MORIMOTO Y, TOIYAMA Y, et al. Intravital dual-colored visualization of colorectal liver metastasis in living mice using two photon laser scanning microscopy[J]. Microsc Res Tech, 2012,75(3):307-315.

[45] MATSUMURA H, KONDO T, OGAWA K, et al. Kupffer cells decrease metastasis of colon cancer cells to the liver in the early stage[J]. Int J Oncol, 2014,45(6):2303-2310.

[46] GUL N, BABES L, SIEGMUND K, et al. Macrophages eliminate circulating tumor cells after monoclonal antibody therapy[J]. J Clin Invest, 2014,124(2):812-823.

[47] PASCHOS K A, MAJEED A W, BIRD N C. Role of Kupffer cells in the outgrowth of colorectal cancer liver metastases[J]. Hepatol Res, 2010,40(1):83-94.

[48] KIMURA Y, INOUE A, HANGAI S, et al. The innate immune receptor Dectin-2 mediates the phagocytosis of cancer cells by Kupffer cells for the suppression of liver metastasis[J]. Proc Natl Acad Sci U S A, 2016,113(49):14097-14102.

[49] TIMMERS M, VEKEMANS K, VERMIJLEN D, et al. Interactions between rat colon carcinoma cells and Kupffer cells during the onset of hepatic metastasis[J]. Int J Cancer, 2004,112(5):793-802.

[50] GRANDJEAN C L, MONTALVAO F, CELLI S, et al. Intravital imaging reveals improved Kupffer cell-mediated phagocytosis as a mode of action of glycoengineered anti-CD20 antibodies[J]. Sci Rep, 2016,6:34382.

[51] VAN DEN EYNDEN G G, MAJEED A W, ILLEMANN M, et al. The multifaceted role of the microenvironment in liver metastasis: biology and clinical implications[J]. Cancer Res, 2013,73(7):2031-2043.

[52] TIMMERS M, VEKEMANS K, VERMIJLEN D, et al. Interactions between rat colon carcinoma cells and Kupffer cells during the onset of hepatic metastasis[J]. Int J Cancer, 2004,112(5):793-802.

[53] HAM B, WANG N, D′COSTA Z, et al. TNF receptor-2 facilitates an immunosuppressive microenvironment in the liver to promote the colonization and growth of hepatic metastases[J]. Cancer Res, 2015,75(24):5235-5247.

[54] KRUGER A. Premetastatic niche formation in the liver: emerging mechanisms and mouse models[J]. J Mol Med (Berl), 2015,93(11):1193-1201.

[55] DONG P, MA L, LIU L, et al. CD86+/CD206+, diametrically polarized tumor-associated macrophages, predict hepatocellular carcinoma patient prognosis[J]. Int J Mol Sci, 2016,17(3):320.

[56] ZHANG Q, ZHU B, LI Y. Resolution of cancer-promoting inflammation: a new approach for anticancer therapy[J]. Front Immunol, 2017, 8:71.

[57] DIAKOS C I, CHARLES K A, MCMILLAN D C, et al. Cancer-related inflammation and treatment effectiveness[J]. Lancet Oncol, 2014,15(11):e493-e503.

[58] GEISSMANN F, JUNG S, LITTMAN D R. Blood monocytes consist of two principal subsets with distinct migratory properties[J]. Immunity, 2003,19(1):71-82.

[59] TENG K Y, HAN J, ZHANG X, et al. Blocking the CCL2-CCR2 axis using CCL2-neutralizing antibody is an effective therapy for hepatocellular cancer in a mouse model[J]. Mol Cancer Ther, 2017,16(2):312-322.

[60] FURNESS A J, VARGAS F A, PEGGS K S, et al. Impact of tumour microenvironment and Fc receptors on the activity of immunomodulatory antibodies[J]. Trends Immunol, 2014,35(7):290-298.

[61] PARK S, JIANG Z, MORTENSON E D, et al. The therapeutic effect of anti-HER2/neu antibody depends on both innate and adaptive immunity[J]. Cancer Cell, 2010,18(2):160-170.

[62] LO J, LAU E Y, SO F T, et al. Anti-CD47 antibody suppresses tumour growth and augments the effect of chemotherapy treatment in hepatocellular carcinoma[J]. Liver Int, 2016,36(5):737-745.

[63] LO J, LAU E Y, CHING R H, et al. Nuclear factor kappa B-mediated CD47 up-regulation promotes sorafenib resistance and its blockade synergizes the effect of sorafenib in hepatocellular carcinoma in mice[J]. Hepatology, 2015,62(2):534-545.

[64] XIAO Z, CHUNG H, BANAN B, et al. Antibody mediated therapy targeting CD47 inhibits tumor progression of hepatocellular carcinoma[J]. Cancer Lett, 2015,360(2):302-309.

[65] MOVITA D, VAN DE GARDE M D, BIESTA P, et al. Inflammatory monocytes recruited to the liver within 24 hours after virus-induced inflammation resemble Kupffer cells but are functionally distinct[J]. J Virol, 2015,89(9):4809-4817.

[66] GORDON S R, MAUTE R L, DULKEN B W, et al. PD-1 expression by tumour-associated macrophages inhibits phagocytosis and tumour immunity[J]. Nature, 2017,545(7655):495-499.