口服耐受对自身免疫性葡萄膜视网膜炎影响的实验研究

目的 观察口服牛视网膜S抗原对人S抗原多肽-35诱发的实验性自身免疫性葡萄膜视网膜炎(EAU)的影响.设计实验性对照研究.研究对象20只雌性纯种Lewis大鼠.方法 用人S抗原多肽-35诱发EAU,提纯牛视网膜S抗原诱导口服耐受,分高剂量组(2 mg/次)和低剂量组(0.2 mg/次),同时设实验对照组(胎牛血清蛋白).主要指标EAU发病情况和脾组织白介素-4(IL-4)和γ-干扰素(IFN-γ)的表达水平.结果 口服高剂量组的Lewis大鼠的EAU发病情况较实验对照组有显著减轻(P＜0.05),而且口服高剂量组Lewis大鼠脾组织IL-4的表达水平则高于实验对照组(F=4.214,P=0.017).结论 口服高剂量牛视网膜S抗原诱导的免疫耐受町以成功抑制人S抗原多肽-35诱发的实验性自身免疫性葡萄膜视网膜炎.(眼科,2008,17:250-253)     

口服免疫耐受预防实验性自身免疫性葡萄膜视网膜炎中细胞因子网络的研究

目的 观察口服免疫耐受预防大鼠实验性自身免疫性葡萄膜视网膜炎(EAU)过程中血清以及脾细胞培养上清液中的Th1类细胞因子干扰素（IFN）-γ、白细胞介素（IL）-2和Th2类细胞因子IL-4、IL-10表达水平。方法 Lewis大鼠72只随机分为EAU组、口服视网膜S抗原10、100μg组和1、10 mg组、对照组，每组各12只大鼠。其中，EAU组用视网膜S抗原50μg和弗氏完全佐剂免疫诱导EAU模型，口服10、100 μg组和1、10 mg组，分别插管喂饲视网膜S抗原10、100 μg，1、10 mg和1 mg胰蛋白酶抑制剂的混合液1 ml，隔日1次，共7次，然后按上述方法诱导EAU；对照组插管喂饲磷酸盐缓冲液和1 mg胰蛋白酶抑制剂的混合液1 ml，隔日1次，共7次，然后诱导EAU。观察每组大鼠眼部EAU的临床表现。在EAU高峰期取大鼠眼球，进行病理分级。同时取大鼠血清，分离脾细胞，培养后取上清液，用酶联免疫吸附试验(ELISA)检测血清以及脾细胞培养上清液中IFN-γ、IL-2、IL-4和IL-10细胞因子的水平。结果 100μg、1 mg组血清中Th1类细胞因子IFN-γ、IL-2浓度降低，Th2类细胞因子IL-4、IL-10的浓度增高，与EAU组和对照组比较，差异均有统计学意义（F=51.9, 68.8, 35.7,7.5,P＜0.01）；10 μg、10 mg组血清中Th1、Th2类细胞因子与EAU组和空白对照组比较，差异无统计学意义。与EAU组和空白对照组相比，100 μg、1 mg组大鼠脾细胞培养上清液中Th1类细胞因子IFN-γ和IL-2的浓度降低，Th2类细胞因子IL-4、IL-10的浓度增高，与EAU组和对照组比较，差异均有统计学意义（F=57.1,15.6,33.1,167.7, P＜0.01）；10 μg、10 mg组大鼠脾细胞培养上清液血清中Th1、Th2类细胞因子与EAU组和空白对照组比较，差异无统计学意义。结论 口服免疫耐受预防EAU过程中，Th1类细胞因子IFN-γ和IL-2的表达降低，而Th2类细胞因子IL-4、IL-10的表达增高。口服过高或过低剂量抗原不能预防EAU，细胞因子的表达水平也无明显改变。提示细胞因子在口服免疫耐受预防EAU的过程中起到重要作用。     

人视网膜S-AgP35诱发EAU动物模型的建立

目的 采用合成的人视网膜S-Ag多肽片断第35段抗原决定簇(HS-AgP35)在Lewis大鼠建立实验性葡萄膜炎(EAU)模型.方法 雌性Lewis大鼠30只,随机分成3组,每组10只.两实验组中HS-AgP35和BS-Ag分别与CFA混合,致敏Lewis大鼠,正常对照组不做处理.观察大鼠眼部体征和组织病理学改变;ELISA方法 检测大鼠血清中抗HS-AgP35/BS-Ag抗体水平;RT-PCR方法 检测大鼠脾组织内IL- 4和IFN-γ mRNA表达水平.结果 两种抗原均能致Lewis大鼠发生EAU,HS-AgP35组100%发病,BS-Ag组60%发病,两者比较差异无统计学意义(P＞0.05);HS-AgP35组大鼠发病早(P＜0.01),眼部体征和组织病理学改变严重(P＜0.01),持续时间长(P＜0.01).两实验组大鼠血清中抗BS-Ag/HS-AgP35抗体水平均高于正常对照组(P＜0.01),HS-AgP35组高于BS-Ag组(P＜0.05).两实验组大鼠脾组织中IFN-γ mRNA表达水平均高于正常对照组(P＜0.01);HS-AgP35组IL- 4 mRNA表达较高(P＜0.01),BS-Ag组无明显变化(P＞0.05).结论 抗原特异性高的HS-AgP35能诱导Lewis大鼠发生EAU,可建立具有典型眼部表现和组织病理学改变的动物模型.     

CD4＋CD25＋T细胞在实验性自身免疫性葡萄膜视网膜炎中的作用

背景实验性自身免疫性葡萄膜视网膜炎（EAU）已被证明是一种由T淋巴细胞介导的器官特异性自限性疾病。研究表明 CD4＋CD25＋T细胞可能参与了EAu的调控,但其作用机制尚有待研究。目的探讨EAU中 CD4＋CD25＋T细胞的表达变化。方法按照Caspi的方法提纯牛视网膜S抗原,与弗氏完全佐剂混合后,于24只Lewis大鼠右后足底部注射0．1ml制作EAU模型,4只未处理大鼠作为正常对照组。免疫后每日州裂隙灯显微镜观察大鼠眼部变化。造模后7、12、15、21d处死动物,取大鼠视网膜、引流淋巴结、脾脏,对大鼠眼组织切片进行苏木精一伊红染色前进行病理评分。对各时间点收集的大鼠视网膜、引流淋巴结、脾脏分别制备单细胞悬液,流式细胞仪检测各时间点3种组织中 CD4＋CD25＋T细胞的表达情7兄。结果造模7d后大鼠睫状充血,虹膜血管扩张;15d后炎症达高峰,前房大量炎性渗出;21d后炎症消退。眼部病理评分结果与临床所见一致,造模15d组病理评分与其他各组比较差异均有统计学意义（P=0．000）。正常对照组大鼠脾脏和淋巴结中有2．0％CD4＋T细胞表达CD25,造模组 CD4＋CD25＋T细胞表达增加,亓在EAU高峰期达最高,EAU消退期轻微下降,与正常对照组比较差异有统计学意义（P=0．000）。结论 CD4＋CD25＋T细胞在EAU动物模型炎症组织中表达的动态变化与炎症反应有关,提示 CD4＋CD25＋T细胞参与EAU的发生发展和消退过程。     

雷帕霉素对大鼠实验性自身免疫性葡萄膜炎的治疗作用

背景雷帕霉素不仅具有抗菌作用,而且是一种良好的免疫抑制剂,可用于多种自身免疫性疾病的治疗．对实验性自身免疫性葡萄膜炎（EAU）的治疗作用是目前研究的热点之一。目的研究雷帕霉素对EAU的治疗作用,并观察雷帕霉素对EAU各免疫细胞群炎性因子表达的影响。方法25只Lewis大鼠采用随机数字表法分为EAU组（20只）和正常对照组（5只）。光感受器间维生素A类结合蛋白（IRBP）R16肽段与完全氟氏佐剂充分乳化后于Lewis大鼠后足皮下注射以建立EAU模型,EAU模型鼠再按分层随机的原则分为模型对照组和雷帕霉素组,每组10只大鼠。雷帕霉素组造模后即应用O．2mg／（kg·d）雷帕霉素（0．4m1）腹腔内连续注射7d,模型对照组及正常对照组大鼠采用等体积的生理盐水进行腹腔内注射。造模后第4天开始每日裂隙灯下观察大鼠EAU的症状,造模后第14天制备大鼠视网膜切片,以苏木精-伊红染色法进行组织病理学观察,参照Caspi的标准对EAU症状及组织病理学分级进行评分。应用免疫组织化学染色法检测各组大鼠视网膜中炎性因子干扰素-γ（IFN-γ）、白细胞介素-17（IL-17）的表达情况。结果造模后6d模型对照组大鼠EAU炎症评分逐渐升高,12d达到高峰,然后逐渐下降。雷帕霉素组大鼠EAU炎症评分变化呈现相同的趋势,但各时间点EAU炎症评分均明显低于模型对照组,差异均有统计学意义（P〈0．01）。视网膜组织病理学研究表明,模型对照组大鼠视网膜结构紊乱,大量炎性细胞浸润,组织病理学评分为3．30±0．48,而雷帕霉素组视网膜结构接近正常,组织学评分为0．90±0．45,差异有统计学意义（t=16．541,P〈0．01）。雷帕霉素组IFN-γ、IL-17在大鼠视网膜中的表达量（A值）分别为21．16±4．23和49．86±6．59,明显低于模型对照组的62．14±7．32和124．85±6．33,差异均有统计学意义（q=33．334、q=56．923,P〈0．01）。结论雷帕霉素通过抑制EAU视网膜中IFN-γ、IL-17等炎性因子的表达而对EAU发挥治疗作用,其机制可能是通过抑制Th1、Th17细胞群来实现的。     

IRBPR16多肽的合成及其致葡萄膜视网膜炎活性的探讨

目的 探讨光感受器间维生素A类结合蛋白（IRBP）的R16多肽片段的致葡萄膜视网膜炎活性。设计实验研究。研究对象36只Lewis大鼠。方法应用Fmoc法合成并纯化牛IRBPR16多肽片段,以诱导实验性自身免疫性葡萄膜视网膜炎（EAU）模型,并对该模型进行临床观察和组织学检查。培养EAU大鼠的引流淋巴结细胞,测定淋巴细胞增殖反应。各实验同时建立单纯弗式完全佐剂（CFA）免疫组和空白对照组。主要指标多肽分析,视网膜形态学,淋巴细胞增殖反应。结果合成的IRBPR16多肽片段纯度为95．6％。应用IRBPR16多肽片段作为抗原免疫Lewis大鼠,可成功诱导出EAU模型。EAU的临床分级为（3．33±0．52）级,病理分级为（3．67±0．92）级;CFA组和空白对照组大鼠眼部均无异常改变。EAU组大鼠引流淋巴结中抗原特异性淋巴细胞增殖反应增强,为（33．27±7．24）×10^cpm,显著高于CFA组[（1．91±1．16）×10^3cpm]和空白对照组[（1．23±0．51）×10^3cpm]（P〈0．05）。结论IRBPR16多肽片段具有较强的致葡萄膜视网膜炎活性,引流淋巴结抗原特异性淋巴细胞增殖反应增强。IRBPR16多肽诱导的EAU为研究人类葡萄膜视网膜炎提供了一个重要的动物模型。     

大鼠的实验性自身免疫性葡萄膜视网膜炎的免疫致病机理

为了了解实验性自身免疫性葡萄膜视网膜炎(EAU)免疫致病机理,用Lewis鼠研究T淋巴细胞和肥大细胞的作用。用致敏的淋巴细胞特别是辅助性/诱异性T细胞亚群成功地转移给首次用来作实验的同系大鼠。接受了对S抗原致敏了的辅助性/诱导性T细胞的实验性自身免疫性葡萄膜视网膜炎(EAU)的大鼠充分表现了对此抗原的迟发型皮肤超敏反应但极轻微的Arthus反应。分析了环孢霉素、环磷酰胺,地塞米松等免疫抑制剂药物对S抗原免疫的鼠产生EAU的作用。通过选择性抑制对S抗原的迟发型皮肤超敏反应,说明仅有环孢霉素能完全抑制EAU的发生。这些资料说明T淋巴细胞在EAU致病机理中起主要的作用。根据在疾病发作以前,脉络膜的肥大细胞发生脱颗粒作用,说明除了淋巴细胞参与以外,脉络膜的肥大细胞也起了附带作用。     

视网膜S抗原的制备和提纯方法的改进

实验性自身免疫性葡萄膜炎(EAU)是由CD4+T淋巴细胞介导的器官特异性炎症,可由多种视网膜蛋白诱发,主要有视网膜可溶性抗原(S-Ag)、光感受器间维生素A类结合蛋白(IRBP)和视紫红质等,其中以S抗原诱发的葡萄膜炎更具有临床意义[1]。由于S抗原所致葡萄膜炎的活性与其纯度呈正相关,所以S抗原的纯化尤为重要。我们将Al-Mahdawi等[2]的方法进行改进简化,获得了较高纯度的牛视网膜S抗原,并免疫Lewis大鼠成功地复制出EAU模型。现将结果报告如下。1材料和方法冰浴下暗室解剖新鲜牛眼,沿角膜缘环行切开眼球,挤出晶状体和玻璃体,用毛笔刷轻取…     

溴隐亭对大鼠实验性自身免疫性葡萄膜视网膜炎的影响

目的 观察泌乳素(prolactin, PRL)释放抑制剂——溴隐亭(bromo criptine, BRC)阻断PRL对大鼠实验性自身免疫性葡萄膜视网膜炎（experimental autoimmune uveoretinitis，EAU）的治疗效果。 方法 24只Wistar大鼠用牛视网膜可溶性抗原免疫后，随机数字表法随机分为治疗组和对照组。治疗组每日给予BRC葡萄糖溶液 5 mg/(kg·d)经口灌服，对照组每日葡萄糖溶液50 g/L经口灌服，观察2组EAU发病情况。免疫15 d后评价大鼠迟发型变态反应（delayed type hypersensitivity，DTH）；免疫23 d后眼球摘除，行组织学检查。 结果 治疗组EAU发病率和组织学炎症评分均低于对照组，其差异均有显著性的意义(P＜0.05,P＜0.001)；2组之间DTH比较差异无显著性的意义 (P＞0.05)。 结论 在整体水平上，BRC干预能够抑制大鼠EAU的发生和减轻EAU的病情。 （中华眼底病杂志，2003，19：34-37）     

龙胆泻肝汤对实验性自身免疫性葡萄膜炎大鼠M1/M2巨噬细胞极化平衡的调控作用

目的 探讨龙胆泻肝汤(Longdan Xiegan decoction,LXD)对实验性自身免疫性葡萄膜炎(EAU)大鼠M1/M2巨噬细胞极化平衡的调控作用.方法 将48只雌性Lewis大鼠随机分为正常对照组、EAU模型组和LXD干预组,其中EAU模型组和LXD干预组大鼠首先诱导并建立EAU模型,LXD干预组大鼠每天给...     

视网膜抗原免疫联合内毒素诱导的新的EAU小鼠模型

背景 葡萄膜炎的发病机制和治疗仍是目前的研究热点,但多年来该领域的基础研究仍是沿用传统的造模方法制备相关的动物模型,与人类的葡萄膜炎自然病程有较大偏差. 目的 本研究用大肠杆菌内毒素,即脂多糖（LPS）替代百日咳毒素（PTX）作为主要诱发因素,建立更符合人类自然发病环境的新型实验性自身免疫性葡萄膜视网膜炎（EAU）的动物模型,并与传统的造模方法进行比较,为研究该病的发病机制和有效的治疗方案提供实验依据.方法 6～8周龄的无特定病原体级雌性C57BL/6（H-2b）小鼠20只,按随机数字表法分为正常对照组、单纯内毒素注射组（EIU组）、多肽＋完全弗氏佐剂（CFA）注射组（EAU组）、多肽＋CFA＋LPS组（LPS-EAU组）.LPS-EAU组先用人类光感受器间维生素A类结合蛋白（IRBP 1-20）＋CFA免疫小鼠,免疫后第7天小鼠足底注射LPS,诱发小鼠EAU模型.采用组织病理学损害、眼球组织病理学评分、迟发型过敏反应、特异性淋巴细胞增生反应等评价指标对动物模型进行鉴定,并与LPS诱导的EIU及IRBP 1-20＋ CFA免疫诱导的EAU进行比较.结果 正常对照组小鼠虹膜睫状体及视网膜组织结构未见异常;EIU组小鼠虹膜睫状体可见轻微血管扩张、蛋白及纤维素渗出,但玻璃体和视网膜组织内未见血管异常及炎症反应;EAU组小鼠虹膜睫状体未见血管扩张及炎性渗出,但可见视网膜轻微血管周围炎及神经纤维层肿胀;LPS-EAU组小鼠视网膜结构紊乱,可见较多的炎性细胞浸润、光感受器细胞损伤及视网膜全层破坏.正常对照组小鼠和EIU组小鼠病理评分均为0分,EAU组病理评分为0.5分,而LPS-EAU组小鼠病理评分为3.0分,显著高于EAU组,差异有统计学意义（U=16.246,P=0.001）.LPS-EAU组小鼠耳廓增厚值为（35.60±0.55） tm,显著高于EIU组小鼠的（12.60±0.55）μm,差异均有统计学意义（q=23.003,P＜0.01）;但与EAU组小鼠的（34.80±0.84）μm比较,差异无统计学意义（q=0.820,P＞0.05）.LPS-EAU组小鼠的脾细胞体外培养的克隆数显著增加,其3 HTdR掺入值（CPM）为（8 540.00±54.77）/min,而EAU组的cpm为（8 484.00±47.75）/min,差异无统计学意义（q=56.634,P=0.069）,但与EIU组的cpm（2 050.00±50.00）/min比较,LPS-EAU组明显升高,差异有统计学意义（q=195.683,P=0.000）. 结论 LPS可以成功诱发小鼠的EAU,该动物模型在模拟病因方面更符合人类自然发病环境,为研究人类EAU的病因和发病机制提供了一个可能更好的动物模型.     

Interphotoreceptor retinoid binding protein is a potent tolerogen in Lewis rat: suppression of experimental autoimmune uveoretinitis is retinal antigen specific

AIMS—Administration of unfractionated retinal antigen(s) (retinal extract, RE) suppresses RE induced experimental autoimmune uveoretinitis (EAU) and offers a potential therapeutic alternative to non-specific immunosuppressive therapies for posterior uveitis and autoimmune diseases. S-Ag and interphotoreceptor retinoid binding protein (IRBP) are two major autoantigens within soluble RE. It was aimed to assess, firstly, as has previously been shown with S-Ag, if IRBP can induce intranasal tolerance and, secondly, the contribution of both these major autoantigens to tolerance induction by whole RE.
METHODS—Animals were tolerised by intranasal administration with S-Ag or IRBP, either alone or in combination, or RE before immunisation with either IRBP or RE. Control animals were administered nasally either PBS or MBP. Daily clinical responses were recorded biomicroscopically and histological grades were obtained using a semiquantitative scoring system. Weekly serum antibody levels to retinal antigens were measured by ELISA and delayed hypersensitivity responses (DTH) were assessed by skin reactivity to intradermal inoculation with retinal or non-specific antigens.
RESULTS—Microgram doses of IRBP successfully suppressed both clinically and histologically IRBP induced EAU. This suppression was accompanied by reduced antigen specific DTH reactivity but maintained T cell dependent (IgG2a) antibody responses. Furthermore, combined S-Ag and IRBP administration afforded equal suppression of RE induced EAU when compared with RE therapy alone. Suppression of RE induced EAU was not achieved with administration of a non-retinal specific autoantigen, MBP. Although individually, both S-Ag and IRBP suppressed RE induced EAU, whole RE was unable to protect against IRBP induced disease.
CONCLUSIONS—Intranasal administration of IRBP suppressed IRBP induced EAU in the Lewis rat. S-Ag and IRBP are the major contributors to the tolerogenicity within RE, despite the known uveogenicity of other retinal antigens within RE and induction of tolerance was retinal antigen specific. Furthermore, suppression induced by single antigen administration is antigen specific although concomitant bystander suppression may also play a role. RE was unable to protect against IRBP induced disease despite tolerogenic levels of antigen within RE. Although this may be due in part to a dose effect of either tolerising or immunising antigen, further investigation into the possible antigen dominance of IRBP or mucosal processing of combinations of antigens is necessary so that the full efficacy of mucosal tolerance therapy can be assessed.

     

Nasal administration of retinal antigens suppresses the inflammatory response in experimental allergic uveoretinitis. A preliminary report of intranasal induction of tolerance with retinal antigens.

Current immunotherapy of posterior uveitis is non-specific and limited by drug toxicity and unpredictable relapses on therapy. Alternative modes of therapy being investigated using the rat model of experimental autoimmune uveoretinitis (EAU) have included the induction of tolerance with oral administration of milligram quantities of retinal antigens. In this preliminary report we demonstrate that tolerance to retinal antigens can be induced via the upper respiratory tract with microgram doses of antigen, preventing subsequent induction of EAU.     

Experimental autoimmune uveoretinitis (EAU) in rats: isolation of S-antigen, EAU susceptibility of rat strains, genetic control of EAU induction, and effects of cyclophosphamide and irradiation on EAU

Highly purified S-antigen was isolated from bovine retinas by high performance liquid chromatography (HPLC), and was used to induce experimental autoimmune uveoretinitis (EAU) in various rat strains. Studies were then made of the genetic control of EAU, the effects of cyclophosphamide or irradiation on EAU, and the correlation between the EAU incidence and the serum levels of antibody to S-antigen. Lewis rats were the most susceptible to EAU followed by Wistar rats. F344 rats and BN rats were resistant to EAU. (Lewis X BN)F1 rats and (LBNF1 X Lewis) rats were susceptible to EAU, while (LBNF1 X BN) rats were resistant. These results indicate that susceptibility to EAU was inherited as an autosomal dominant trait. Treatment of rats with cyclophosphamide or irradiation (200 rad/rat) on the day before immunization markedly suppressed EAU development. On the other hand, the same dose of irradiation 7 days after the immunization did not affect the disease induction, yet the antibody levels to S-antigen were very high in the rats. In addition, BN rats resistant to EAU exhibited very high levels of antibody to S-antigen. Therefore, the antibody to S-antigen seems to play a minor role, if any, in the immunopathogenic mechanisms of EAU.     

Inhibition of experimental autoimmune uveoretinitis with anti-macrophage migration inhibitory factor antibodies

PURPOSE: The role of macrophage migration inhibitory factor (MIF) in the regulation of ocular autoimmune disease was studied in experimental autoimmune uveoretinitis (EAU) in rats following immunization with a retinal antigen (Ag), interphotoreceptor retinoid-binding protein (IRBP). METHODS: LEW rats were immunized with a single injection of IRBP derived peptide, R16(ADGSSWEGVGVVPDV). A neutralizing monoclonal antibody (mAb, IgM) to MIF was injected intraperitoneally every second day from day 0 to day 6 (group A), or from day 8 to day 14 (group B). Control rats were treated with unrelated mouse IgM or PBS. T cell proliferative responses were measured 12 days after immunization. The occurrence and severity of EAU were observed and compared among experimental and control groups. RESULTS: T cell proliferative responses against R16 were inhibited in rats treated with anti-MIF mAb compared with the control rats. The development of EAU was delayed in the rats of group A in comparison with those of group B and the control group. The mean histological EAU score on day 18 in group A was 1.11 +/- 0. 11 and significantly lower than those of the group B (1.29 +/- 0.19) and the control (1.67 +/- 0.19). CONCLUSIONS: The present result suggests that MIF plays an important role in induction of EAU.     

Total dose and frequency of administration critically affect success of nasal mucosal tolerance induction

AIMS: Nasal tolerance induction with autoantigens can effectively protect against a variety of experimental models of autoimmune disease. The aims of this study were to characterise the dosage and kinetics of inhibition of experimental autoimmune uveoretinitis (EAU) via intranasal administration of the uveitogenic antigen interphotoreceptor retinal binding protein (IRBP) in the murine model of IRBP induced EAU. METHODS: B10RIII mice were tolerised by intranasal administration of IRBP either with a long term multiple low dose or a short term/high dosing regimen before subcutaneous immunisation with IRBP in complete Freund's adjuvant (CFA). On day 15 post-immunisation, mice were killed and eyes were removed for histological examination and quantification of inflammatory cell infiltration and degree of target organ (rod outer segment, ROS) destruction. RESULTS: Nasal administration of multiple low doses of IRBP (1 microg or 3 microg IRBP per mouse per day for 10 days) significantly protected mice from IRBP induced EAU. Short term/high dose regimens were only effective when given either as a single or, at most, as two consecutive doses (40 microg per dose). Multiple doses in the range of 45-120 microg over 3 days afforded no protection. CONCLUSIONS: These results indicate that both dose and frequency of intranasal antigen administration are pivotal to tolerance induction and subsequent suppression of T cell mediated autoimmune disease.     

Modulating phenotype and cytokine production of leucocytic retinal infiltrate in experimental autoimmune uveoretinitis following intranasal tolerance induction with retinal antigens.

BACKGROUND/AIM: Nasal administration of retinal antigens induces systemic tolerance which results in suppression of experimental autoimmune uveoretinitis (EAU) when subsequently exposed to antigen. The aim was to establish if tolerance induction alters retinal infiltrating leucocyte phenotype and cytokine profile in tolerised animals when there is significantly reduced tissue destruction despite immunisation with retinal antigen. METHODS: Female Lewis rats were tolerised by intranasal administration with retinal extract (RE) before immunisation with RE to induce EAU. Control animals were administered phosphate buffered saline (PBS) intranasally. Post immunisation, daily clinical responses were recorded and at the height of disease, retinas were removed and either infiltrating leucocytes isolated for flow cytometric phenotype assessment and intracellular cytokine production, or chorioretina processed for immunohistochemistry. Fellow eyes were assessed for cytokine mRNA by semiquantitative RT-PCR. RESULTS: Flow cytometric analysis showed that before clinical onset of EAU there is no evidence of macrophage infiltration and no significant difference in circulating T cell populations within the retina. By day 14 a reduced retinal infiltrate in tolerised animals was observed and in particular a reduction in numbers of "activated" (with respect to CD4 and MHC class II expression) macrophages. Immunohistochemistry confirmed these findings and additionally minimal rod outer segment destruction was observed histologically. Cytokine analysis revealed that both IL-10 mRNA and intracellular IL-10 production was increased in tolerised eyes 7 days post immunisation. Although by day 14 post immunisation, IL-10 production was equivalent in both groups, a reduced percentage of IFN-gamma + macrophages and IFN-gamma + CD4+ T cells with increased percentage of IL-4+ CD4+ T cells were observed in tolerised animals. CONCLUSIONS: Leucocytic infiltrate is not only reduced in number but its distinct phenotype compared with controls implies a reduced activation status of infiltrating monocyts to accompany increased IL-10 and reduced IFN-gamma production in tolerised animals. This modulation may in turn contribute towards protection against target organ destruction in EAU.