小胶质细胞对肿瘤的免疫监视作用

视网膜是中枢神经系统（CNS）的一部分,视网膜小胶质细胞与脑的小胶质细胞在功能上有很多相似之处。小胶质细胞在CNS和视网膜中参与多种炎症性疾病和变性过程。小胶质细胞在CNS肿瘤和视网膜母细胞瘤（RB）中也存在,并且分泌各种细胞因子和生长因子来帮助肿瘤逃避免疫监视,促进肿瘤生长和浸润。对小胶质细胞功能的深入研究有助于开发CNS肿瘤和RB的免疫治疗。就小胶质细胞在CNS和视网膜中对肿瘤进行免疫监视方面的功能进行综述。     

视网膜修复中干细胞的应用

视网膜疾病由于其不可逆转的致盲性而影响人类生存质量.随着对干细胞研究的深入,基于干细胞移植的细胞替代疗法为视网膜疾病的治疗开辟了新的途径.近年来眼组织来源的视网膜干细胞或祖细胞、非眼组织来源的间充质干细胞、造血干细胞、神经干细胞、胚胎干细胞以及诱导多能干细胞在视网膜损伤疾病中的应用取得了很多突破性进展,它们不仅可以被诱导分化为各种视网膜神经元细胞、胶质细胞,而且移植到体内可以整合到损伤视网膜,甚至可以发挥正常视网膜神经元细胞功能.     

小胶质细胞与Müller细胞间的交互作用机制在缺血性视网膜病变中的研究进展

缺血性视网膜病变会导致微血管损伤、炎症进展和新生血管出现,是造成视力损伤的重要原因。在这些病理过程中,视网膜胶质细胞的作用不容忽视,它们用途广泛,与各类细胞相互作用,共同维持视网膜内环境稳定并限制疾病进展。因此,胶质细胞的活化和增生几乎是所有视网膜疾病中普遍存在的反应。其中,小胶质细胞和Müller细胞作为两种主要的内源性视网膜胶质细胞,彼此影响、共同作用甚至相互依存,能够通过不同反应发生形态及功能转换,决定视网膜的损伤程度。这些反应不仅关乎疾病进展程度,也对维持神经元及光感受器存活至关重要。了解缺血性视网膜病变中小胶质细胞与Müller细胞间可能存在的交互作用,有望为寻找更具有针对性的早期治疗靶点提供思路。     

激活的小胶质细胞在大鼠视网膜缺血再灌损伤模型中的作用

目的探讨活化的小胶质细胞在视网膜缺血再灌注损伤过程中的作用。方法前房灌注法建立视网膜缺血再灌注动物模型,在损伤发生后2 h、12 h、24 h、48 h、72 h,采用免疫组织化学染色方法检测特异性抗原标志物CD68的表达,观察活化小胶质细胞的分布、活化程度等,同时观察相应时间点的视网膜超微结构变化。结果对照组中视网膜小胶质细胞主要位于神经节细胞层。缺血再灌注损伤后2 h组视网膜小胶质细胞的分布部位、表达量等基本与对照组相同;缺血再灌注损伤后12 h组视网膜中CD68+细胞表达增多,内丛状层可见阳性细胞。缺血再灌注损伤后24 h组CD68+细胞表达明显增多,部分向视网膜外层迁移。缺血再灌注损伤后48 h组进入视网膜外层的CD68+细胞多数出现于视网膜内丛状层、内核层、外丛状层。缺血再灌注损伤后72 h组活化小胶质细胞数量达到最高水平。视网膜超微结构显示:缺血再灌注损伤后12 h组开始出现损伤表现,视网膜神经节细胞间隙扩大、光感受器细胞外节膜盘疏松变形、可见散在小胶质细胞;缺血再灌注损伤后24 h组病变继续加重,小胶质细胞数量明显增多;缺血再灌注损伤后72 h组病变继续加重,视网膜神经节细胞数量明显减少,细胞核膜肿胀溶解,细胞器溶解,大鼠视网膜神经节细胞层内可见凋亡小体、小胶质细胞,证明了小胶质细胞对光感受器的损伤作用。结论视网膜缺血再灌注损伤出现明显小胶质细胞活化,活化的小胶质细胞在视网膜超微结构的损伤中发挥着重要作用。     

CX3CR1及小胶质细胞在视网膜退行性疾病中的研究进展

视网膜退行性疾病如视网膜色素变性、年龄相关性黄斑变性等是临床主要一类致盲性眼病，病因复杂并对视力造成不可逆性损伤。CX3CR1是趋化因子CX3CL1的特异性受体，二者通过对机体免疫系统的调控参与全身各项生理功能及病理变化。近年来研究指出CX3CR1调节视网膜小胶质细胞的活性及功能，二者在视网膜退行性疾病过程中发挥重要作用。本文就趋化因子受体CX3CR1的结构功能及其与小胶质细胞在视网膜退行性疾病中的作用研究进行综述，为今后此类疾病研究及治疗提供思路及方向。     

小胶质细胞在视网膜血管生成中的作用机制研究进展

视网膜小胶质细胞作为视网膜的常驻免疫细胞,不断监测其周围环境的变化,并通过与其他视网膜细胞的信号传导维持稳态。视网膜小胶质细胞不仅在视网膜血管系统的发育和生理过程中发挥重要作用,而且在病理性新生血管形成中也起着至关重要的作用。在某些视网膜病变中,活化的小胶质细胞通过神经血管耦联,促进异常血管生成,从而造成不可逆的损伤,但具体的作用机制尚不明确。本文简要综述小胶质细胞与视网膜新生血管生成的相关性,并讨论了参与该过程的细胞和分子信号机制,旨在为视网膜新生血管性疾病的预防和治疗提供新的有效的策略。     

糖尿病视网膜病变中小胶质细胞的应答-从神经血管单元角度探讨小胶质细胞的异常改变

糖尿病视网膜病变是糖尿病最严重的微血管慢性并发症之一，其发病机制复杂。越来越多的证据表明小胶质细胞在糖尿病视网膜病变的发生发展中发挥重要作用，视网膜中持续活化的小胶质细胞引起视网膜神经元损伤和血一视网膜屏障破坏。本文回顾了近年来有关小胶质细胞在生理条件和糖尿病时在视网膜中的分布、形态、表面标志分子谱构成和生物学功能的变化等方面的研究进展，探讨生理条件下神经血管单元中小胶质细胞的功能、调节及其参与糖尿病视网膜病变的可能机制。     

青光眼疾病中视网膜胶质细胞的作用

青光眼是一种视网膜视神经的退行性病变,以视网膜神经节细胞(RGCs)的凋亡为基本病理基础,但其凋亡的具体机制尚未完全阐明.目前,大量在体及体外研究发现,视网膜胶质细胞,如Müller胶质细胞、星形胶质细胞和小胶质细胞与青光眼的发生和发展,特别是RGCs的损伤密切相关.胶质细胞上存在众多神经递质受体、离子通道、表面标志物及效应分子,同时也可释放活性因子,因此胶质细胞除了传统认为的具有对神经元的支持营养作用外,还积极参与神经元之间的信息传递过程.在青光眼条件下,胶质细胞可被激活并产生许多生理、生化及形态学改变,一方面可释放神经保护因子,启动神经保护程序;另一方面在胶质细胞过度激活时也会影响其正常生理功能或释放有害因子,加重视网膜神经元的损伤.这2种作用在青光眼中常常并存,但目前这些作用的潜在机制和相关信号通路尚不十分清楚,因而青光眼神经元损伤后胶质细胞是如何重建或进一步破坏神经元功能需要进行更多的研究.本文对视网膜Müller细胞、星形胶质细胞及小胶质细胞的基本生理特征,以及在青光眼病理过程中各自的功能变化进行综述.     

视网膜小胶质细胞与眼科疾病

视网膜内九层主要由排列有序的神经元及围绕在其周围的胶质细胞组成,后者又分为大胶质细胞(星形胶质细胞,Muller细胞)和小胶质细胞。视网膜小胶质细胞在结构、特性和细胞谱系等方面,有其特殊性,是视网膜固有的抗原递呈细胞,成为视网膜免疫应答的始动者,并且在糖尿病视网膜病变、青光眼、原发性视网膜色素变性等眼科疾病中发挥重要作用。本文就这领域的研究进展作一综述。     

小胶质细胞在视网膜血管发育及新生血管发生中的调控作用

小胶质细胞是中枢神经系统特化的组织巨噬细胞,对维持视网膜的正常形态和功能至关重要.近年研究提示,小胶质细胞在中枢血管系统建立之前已经移行进入大脑.除了具有调控炎症反应的免疫活性作用外,小胶质细胞在中枢神经系统发育期血管塑形以及病理状态下血管重塑中也发挥重要作用.小胶质细胞与生长期血管接触,促进出芽的血管融合;而且与血管内皮细胞存在双向的交互作用.在细胞间传递信息的外泌体以及Notch信号在这种交互作用中扮演重要角色.小胶质细胞在视网膜血管生成中的作用目前尚未得到重视,深入的基础研究有望为视网膜新生血管疾病的治疗提供帮助.本文就小胶质细胞的来源及其如何与血管内皮细胞进行交互作用,从而参与视网膜血管发育及新生血管的发生进行综述.     

小胶质细胞的特征及其在视网膜疾病中的作用

小胶质细胞是组织定居的免疫监控细胞,可感知大脑和视网膜的神经微环境,在视网膜神经元变性和凋亡时迅速激活,是许多视网膜疾病的共同标志物。小胶质细胞还参与发育期直至成熟期的神经回路的重塑以及新生血管的生成。本文归纳小胶质细胞的来源和特征,综述其参与视网膜免疫防御以及多种疾病发生机制的研究进展。     

小胶质细胞极化在青光眼视神经损伤发病机制及治疗中的研究进展

青光眼是多因素介导的以视网膜神经节细胞凋亡、视神经萎缩和视野缺损为特征的神经退行性眼病,发病机制尚不明确.小胶质细胞是视网膜内常驻的免疫细胞,它可分为经典激活M1型和替代激活M2型,随着眼压改变以及视网膜神经节细胞损伤修复过程的进展,小胶质细胞的极性呈现动态变化,可产生多种具有神经毒性或神经保护作用的细胞因子.近年来,...     

Heterogeneous populations of microglia/macrophages in the retina and their activation after retinal ischemia and reperfusion injury

Activation of Microglia/macrophages has been observed in ischemia-reperfusion injury of the brain. This study was undertaken to investigate the different subpopulations of microglia/macrophages in the normal rat retina and their activation after retinal ischemia. Retinal ischemia was induced by elevation of intraocular pressure to 120 mmHg for 60 min. Microglia/macrophages were identified on frozen retinal sections by four antibodies, namely OX42, 5D4, OX6 and ED1. In the normal retina, there were heterogeneous populations of resident microglia/macrophages as characterized by their differences in morphology, antigen expression and distribution. OX42+ cells had delicate processes and were located in the inner layers of the retina, while 5D4+ cells were highly ramified and mostly scattered in the inner plexiform layer (IPL) and the outer plexiform layer. Few amoeboid ED1+ cells were also seen in the ganglion cell layer and IPL. OX6+ (MHC-II antigen presenting) cells were not detected in the normal retinas. Double labeling with OX42 and 5D4 antibodies on normal retinal sections showed few microglia exhibited positive labeling with both OX42 and 5D4, while the majority of the microglia were labeled with either OX42 or 5D4 antibodies. After retinal ischemia single labeling with these antibodies showed increased number of these antigen-expressing cells, disappearance of normal cellular processes, and rounding or amoeboid like appearance of the cell bodies. At 1 day after ischemia, there was a significant infiltration of round OX42+, ED1+ and OX6+ cells with loss of the cellular processes in the inner retina. From 3 to 14 days, all subpopulations of microglia/macrophages differentiated cellular processes and became dendritic again. Double labeling on retinas after 1 day of recovery showed OX42+ cells were co-labeled with ED1+ or OX6+ cells, but not with 5D4+ cells. Scattered amoeboid OX42+, 5D4+, and ED1+ cells were noted in the subretinal space 3-14 days after ischemia. In summary, there were heterogeneous populations of resident microglia/macrophages in the normal inner retina and they were activated early after ischemia-reperfusion injury and exhibited different antigenic expression which were further altered in the recovery phase.     

常见眼病患者视力康复情况

目的：了解严重影响视力的５种眼疾的视力康复情况。 方法统计分析１８６例 ２２７眼白内障、视网膜脱离、角膜炎、青光眼和眼外伤的视力康复情况。 结果白内障、视网膜脱离、角膜炎、青光眼和眼外伤的视力康复率分别为４４．０％、５８．１％、６８．８％、１４．７％和２４．３％。白内障、视网膜脱离、角膜炎的视力康复率无显著性差异（Ｐ＞０．０５）；青光眼和眼外伤的视力康复率亦无明显差异（Ｐ＞０．０５）；前三者视力康复率明显高于后二者，有显著性差异（Ｐ＜０．０１）。 结论白内障、视网膜脱离、角膜炎临床疗效较好；而青光眼重在早期发现、早期治疗；眼外伤则重在防护。     

Activated microglia in human retinitis pigmentosa,late-onset retinal degeneration,and age-related macular degeneration

Many gaps exist in our knowledge of human retinal microglia in health and disease. We address the hypothesis that primary death of rod photoreceptors leads to activation of resident microglia in human retinas with retinitis pigmentosa (RP), late-onset retinal degeneration (L-ORD), or age-related macular degeneration (AMD). Regions of ongoing photoreceptor cell death were studied by immunocytochemistry with microglia- and other retinal cell-specific markers. In normal human retinas, quiescent microglia were small, stellate cells associated with inner retinal blood vessels. In retinas with RP, L-ORD, or AMD, numerous activated microglia were present in the outer nuclear layer in regions of ongoing rod cell death. These microglia were enlarged, amoeboid cells that contained rhodopsin-positive cytoplasmic inclusions. We conclude that activated microglia migrate to the outer nuclear layer and remove rod cell debris. In other central nervous system diseases such as stroke, activated microglia phagocytose debris from the primary injury and also secrete molecules that kill nearby normal neurons. By analogy with these diseases, we suggest that microglia activated by primary rod cell death may kill adjacent photoreceptors. Activated microglia may be a missing link in understanding why initial rod cell death in the human diseases RP, L-ORD, and AMD leads to death of the cones that are critical for high acuity daytime vision.     

Lipopolysaccharide/interferon-gamma and not transforming growth factor beta inhibits retinal microglial migration from retinal explant

BACKGROUND:/aims: The retina possesses a rich network of CD45(+) positive myeloid derived cells that both surround inner retinal vessels and lie within the retina (microglia). Microglia migrate and accumulate in response to neurodegeneration and inflammation. Although microglia express MHC class II, their role remains undefined. The aims of this study are to investigate changes in human microglia phenotype, migration, and activation status in response to pro-inflammatory and anti-inflammatory stimulation. METHODS: Donor eyes were obtained from the Bristol Eye Bank with consent and whole retina was removed. 5 mm retinal trephines were cultured in glucose enhanced RPMI on cell culture insert membranes for up to 72 hours. The effects of lipopolysaccharide/interferon-gamma (LPS/IFNgamma) and transforming growth factor beta inhibits (TGFbeta) stimulation, alone or in combination, on migration, phenotype, and activation status (iNOS expression) of microglia were studied using immunofluorescence and cytokine analysis by ELISA. RESULTS: CD45(+) MHC class II(+) retinal microglia were observed within retinal explants, and in culture microglia readily migrated, adhered to culture membrane, downregulated MHC class II expression, and produced interleukin 12 (IL-12) and tumour necrosis factor alpha (TNFalpha). Following LPS/IFNgamma stimulation microglia remained MHC class II(-) iNOS(-), and secreted IL-10. Migration was suppressed and this could be reversed by neutralising IL-10 activity. TGFbeta did not affect ability of microglia to migrate and was unable to reverse LPS/IFNgamma induced suppression. CONCLUSIONS: Microglia readily migrate from retinal explants and are subsequently MHC class II(-), iNOS(-), and generate IL-12. In response to LPS/IFNgamma microglia produce IL-10, which inhibits both their migration and activation. TGFbeta was unable to counter LPS/IFNgamma effects. The data infer that microglia respond coordinately, dependent upon initial cytokine stimulation, but paradoxically respond to classic myeloid activation signals.     

Heterogeneous populations of microglia/macrophages in the retina and their activation after retinal ischemia and reperfusion injury

Activation of Microglia/macrophages has been observed in ischemia-reperfusion injury of the brain. This study was undertaken to investigate the different subpopulations of microglia/macrophages in the normal rat retina and their activation after retinal ischemia. Retinal ischemia was induced by elevation of intraocular pressure to 120 mmHg for 60 min. Microglia/macrophages were identified on frozen retinal sections by four antibodies, namely OX42, 5D4, OX6 and ED1. In the normal retina, there were heterogeneous populations of resident microglia/macrophages as characterized by their differences in morphology, antigen expression and distribution. OX42+ cells had delicate processes and were located in the inner layers of the retina, while 5D4+ cells were highly ramified and mostly scattered in the inner plexiform layer (IPL) and the outer plexiform layer. Few amoeboid ED1+ cells were also seen in the ganglion cell layer and IPL. OX6+ (MHC-II antigen presenting) cells were not detected in the normal retinas. Double labeling with OX42 and 5D4 antibodies on normal retinal sections showed few microglia exhibited positive labeling with both OX42 and 5D4, while the majority of the microglia were labeled with either OX42 or 5D4 antibodies. After retinal ischemia single labeling with these antibodies showed increased number of these antigen-expressing cells, disappearance of normal cellular processes, and rounding or amoeboid like appearance of the cell bodies. At 1 day after ischemia, there was a significant infiltration of round OX42+, ED1+ and OX6+ cells with loss of the cellular processes in the inner retina. From 3 to 14 days, all subpopulations of microglia/macrophages differentiated cellular processes and became dendritic again. Double labeling on retinas after 1 day of recovery showed OX42+ cells were co-labeled with ED1+ or OX6+ cells, but not with 5D4+ cells. Scattered amoeboid OX42+, 5D4+, and ED1+ cells were noted in the subretinal space 3–14 days after ischemia. In summary, there were heterogeneous populations of resident microglia/macrophages in the normal inner retina and they were activated early after ischemia-reperfusion injury and exhibited different antigenic expression which were further altered in the recovery phase.     

视网膜缺血-再灌注损伤中小胶质细胞对微循环的破坏作用

目的　探讨视网膜缺血-再灌注损伤(retinal ischemia-reperfusion injury,RIRI)中小胶质细胞活化与视网膜微循环损伤的关系及作用机制。方法　160只雄性C57BL/6小鼠右眼均采用前房灌注建立RIRI模型为RIRI组，左眼不作处理为正常对照组。在损伤后24 h、48 h、72 h分别进行视网膜冰冻切片、视网膜铺片免疫荧光染色检测小胶质细胞的活化情况，检测相关缺氧因子及炎症因子的表达，与正常对照组比较，研究小胶质细胞的激活状态与微循环损伤的关系，并初步分析其作用机制。结果　视网膜微循环结构损伤观察结果显示，与正常对照组相比，RIRI后24 h组大部分血管仍呈正常形态；RIRI后48 h组，闭塞的血管数量增多；RIRI后72 h组，血管损伤明显加重。浅层毛细血管密度正常对照组，RIRI后24 h、48 h、72 h组间两两比较差异均无统计学意义（均为P>0.05）。而深层血管网毛细血管密度RIRI后72 h组与其余3组相比明显减少，差异均有统计学意义（均为P<0.05），其余3组间差异均无统计学意义（均为P>0.05）。视网膜冰冻切片检测显示，RIRI后24 h组与正常对照组各层视网膜中抗离子钙接头蛋白（ionized calcium bindingadaptor molecule-1，Iba-1）阳性细胞数差异无统计学意义（P>0.05）。RIRI后48 h组各层中Iba-1阳性细胞数与正常对照组及24 h组差异均有统计学意义（均为P<0.05）。RIRI后72 h组各层中Iba-1阳性细胞数与正常对照组、24 h组、48 h组差异均有统计学意义（均为P<0.05）。视网膜铺片结果显示，RIRI后48 h组和72 h组活化的小胶质细胞数明显增加，与正常对照组和RIRI后24 h组在两个层次毛细血管中差异均有统计学意义（均为P<0.05），而72 h组小胶质细胞的活化达到高峰值，与其余组差异均有统计学意义（均为P<0.05）。RT-PCR检测结果显示:血管内皮生长因子和缺氧诱导因子-1α的缺血缺氧因子，肿瘤坏死因子-α和白细胞介素-1β的炎症因子在正常对照组与RIRI后24 h组、48 h组、72 h组，组间比较差异均有统计学意义（均为P<0.05）。结论　激活的小胶质细胞在RIRI中发挥了对微循环的破坏作用，损伤早期抑制小胶质细胞的活化可能成为此类疾病治疗的新思路。     

Human retinal microglia express candidate receptors for HIV-1 infection

BACKGROUND/AIMS: Microglia are the primary antigen presenting cells in the central nervous system and the retina, and can harbour viral antigens that may damage neural tissue via the release of neurotoxins. All cells bearing CD4 molecules and co-receptors (members of the chemokine receptor and Fcgamma receptor families) are potential targets for the human immunodeficiency virus (HIV). In this study, retinal microglia (in vitro and in situ) were investigated for the expression of candidate HIV-1 binding receptors. METHODS: Cultured human retinal microglia and frozen sections of human retinas were used. Immunohistochemistry was used to investigate expression of cell surface receptors necessary for HIV-1 infection: CD4, CC chemokine receptor 5 (CCR5), and Fcgamma receptors. RESULTS: Human retinal microglia expressed detectable levels of CD4, CD16, CD64, and CCR5 in vitro and Fcgamma receptor I (CD64) in situ. CONCLUSIONS: Human retinal microglia express several candidate receptors required for viral binding and as such may be a potential reservoir for HIV-1 infection.