Analysis of corneal inflammation induced by cauterisation in CCR2 and MCP-1 knockout mice

AIM: To elucidate the role of CCR2/MCP-1 in corneal inflammation. METHODS: A cauterisation induced corneal inflammation model was used. The corneas were cauterised with silver nitrate in CCR2 knockout (KO) mice, MCP-1 KO mice, and control mice. Clinical signs such as corneal oedema and opacity were examined 96 hours after cauterisation and the phenotypes of the cells infiltrating the cornea were analysed by flow cytometry. Corneal inflammation in neutrophil depleted mice was also analysed. RESULTS: After cauterisation both CCR2 KO and MCP-1 KO mice showed the same levels of corneal oedema and opacity as control mice. Flow cytometry revealed that in control mice most of the infiltrating cells were neutrophils and macrophages, whereas in both CCR2 KO mice and MCP-1 KO mice, the number of macrophages infiltrating the cornea were markedly reduced. However, prominent infiltrates of neutrophils were still observed in the cornea in CCR2 KO mice and MCP-1 KO mice. The depletion of neutrophils significantly reduced the oedema and opacity induced in the cornea by cauterisation. CONCLUSION: The CCR2 and MCP-1 molecules are not essential for cauterisation induced corneal inflammation. Neutrophils, rather than migrated macrophages, are the final effector cells involved in inducing inflammation in this model.     

Linkage of IL-6 with neutrophil chemoattractant expression in virus-induced ocular inflammation

PURPOSE: Herpes simplex virus (HSV)-1 infection of the murine cornea is known to stimulate a vigorous interleukin (IL)-6 response, but whether this pleiotropic cytokine is an essential participant in corneal inflammation is unclear. This study was designed to compare the early inflammatory response in IL-6 gene-deficient mice to that in wild-type hosts. METHODS: Gene knockout and wild-type mice (C57BL/6 background) were infected intracorneally with HSV-1 (strain RE) and observed through clinical examination and immunohistochemistry for the development of corneal opacity. Virus corneal titers were determined by standard plaque assay on Vero cells. Cytokine and chemokine levels in corneal lysates were measured with commercial ELISA kits. RESULTS: Corneal opacity in IL-6(-/-) mice was substantially diminished in comparison with IL-6(+/+) hosts 24 to 48 hours after intracorneal viral infection, and corneal levels of (MIP)-2 and MIP-1alpha were significantly reduced. Local administration of IL-6 at the time of infection restored corneal opacity and chemokine levels to that of wild-type hosts. Antibody neutralization of endogenous IL-6 in IL-6(+/+) animals reduced corneal opacity scores and MIP-2 levels to that of IL-6(-/-) mice. Ex vivo studies with excised corneal buttons revealed that uninfected IL-6(-/-) corneas injected with IL-6 produced MIP-2 and MIP-1alpha at levels comparable to that seen in IL-6(+/+) hosts. CONCLUSIONS: Collectively, these results suggest that IL-6 promotes corneal inflammation by acting in an autocrine-paracrine fashion to induce resident corneal cells to make MIP-2 and MIP-1alpha, which in turn recruit neutrophils to the virus infection site.     

Participation of T lymphocyte in corneal edema in the early stage of herpetic stromal keratitis

The participation of T lymphocytes in the immunopathogenesis of corneal opacity in herpetic stromal keratitis was investigated. In BALB/c mice infected intracorneally with herpes simplex virus type 1, corneal opacity was manifested 10 days after infection, while in athymic mice corneas remained almost clear. Histologically, all opaque corneas revealed stromal edema accompanied by the diffuse presence of polymorphonuclear cells and lymphocytes. When complement (C')-treated immune spleen cells were adoptively transferred into athymic mice 6 or 72 h after corneal infection, stromal keratitis with mild opacity was observed 10 days after transfer. The athymic mice given anti-Thy 1.2+C'-treated immune spleen cells failed to develop corneal opacity. The difference, as revealed by light and electron microscopy, was the presence or absence of lymphocytic infiltration and edema in the posterior third layers of the stroma and endothelial lesions. The endothelium was infiltrated by lymphocytes or macrophages and showed various stages of destruction. The main cause of corneal opacity in the early stage of herpetic stromal keratitis is thought to be stromal edema due to an adverse effect on the endothelium by immune T lymphocytes.     

α-GalCer活化的自然杀伤T细胞对高危角膜移植后排斥反应的防治作用

背景 角膜移植排斥反应是导致角膜移植手术失败的主要原因,抑制角膜移植排斥反应的各种药物均有不良反应.研究发现自然杀伤T(NKT)细胞可致器官移植患者免疫耐受,但目前有关NKT细胞用于治疗高危角膜移植免疫反应的研究较少. 目的 探讨体外α-GalCer活化的NKT细胞在防治大鼠高危角膜移植免疫排斥反应中的作用. 方法 无菌条件下取Lewis大鼠脾脏淋巴细胞,加入质量浓度为100 mg/L的α-GalCer,在RPMI 1640培养基培养1周后,流式细胞仪分选出NKT细胞(密度为5×106个/ml).取10只Fisher 344大鼠为供体,20只Lewis大鼠为受体,受体角膜移植前1周角膜缝线诱导角膜新生血管(CNV).将受体大鼠按照随机数字表法随机分为NKT细胞组和生理盐水组,每组各10只.Lewis大鼠行穿透角膜移植.NKT细胞组在手术结束时球后注射0.1 ml NKT细胞液,生理盐水组注射相同体积的生理盐水.术后裂隙灯下观察记录角膜植片的反应情况并按照Holland的标准进行评分.术后第14天,两组各获取3只大鼠角膜植片行组织病理学检测,采用免疫组织化学法检测角膜植片中CD4+和CD8+T淋巴细胞的浸润情况.结果 生理盐水组角膜植片平均存活时间为(7.90±1.37)d,NKT细胞组为(14.70±1.49)d,差异有统计学意义(t=10.61,P=0.00).术后2周,生理盐水组角膜植片重度混浊水肿,大量炎性细胞浸润,新生血管长入植片,而NKT细胞组角膜植片仅轻度混浊、水肿,炎性细胞明显少于生理盐水组.免疫组织化学检测可见,生理盐水组角膜植片中大量CD4+和CD8+T淋巴细胞浸润,NKT细胞组中CD4+和CD8+T淋巴细胞明显减少.流式细胞仪检查结果表明,NKT细胞组大鼠脾脏中NKT细胞百分数为(5.67±0.25)％,明显高于生理盐水组的(1.21±0.19)％,差异有统计学意义(t=8.43,P=0.00).结论 α-GalCer活化的NKT细胞球后注射可以明显延长大鼠高危角膜移植植片的存活时间,为角膜移植排斥反应的防治提供了新的手段.     

IL-17在单纯疱疹性角膜基质炎小鼠中表达的变化

目的:研究IL-17在小鼠单纯疱疹性角膜基质炎模型中的表达。方法:将1.0×106空斑单位的单纯疱疹病毒1型KOS毒株接种于BALB/c鼠的角膜上,建立HSK动物模型。免疫组织化学染色观察IL-17在角膜中的表达。分别取正常小鼠及接种病毒后的第1～3,7,10,14,21,28d,用毛细管取小鼠的左眼眼眶静脉窦血1mL,分离淋巴细胞,行荧光抗体染色,用流式细胞仪检测IL-17阳性的CD4+T细胞的表达。在裂隙灯显微镜下观察角膜的变化,检查角膜的组织学病理改变。结果:实验组中,角膜和外周血均有IL-17表达。实验组角膜基质内炎性细胞、角膜混浊程度非常严重。IL-17的表达与HSK小鼠炎症表现的严重程度成正相关(r=0.609,P<0.01)。结论:IL-17在HSK小鼠模型中呈高表达,且IL-17在HSK的发病过程中起一定作用。     

The role of the polymorphonuclear leukocyte in the induction of corneal edema

Corneal inflammation is frequently associated with the development of corneal edema. It has been suggested the development of corneal edema might in some way be related to the presence of polymorphonuclear leukocytes (PMNLs) within inflamed corneas. In the present studies, it was found that corneal thickness markedly increased after experimental infection with Pseudomonas aeruginosa, but in guinea pigs made neutropenic by whole body irradiation, significantly less of an increase in corneal thickness occurred. Furthermore, corneas from non-neutropenic animals experimentally infected with P. aeruginosa consistently showed a greater increase in water content than did infected corneas from neutropenic animals. Over the first 48 hr of infection, the increase in corneal water was directly proportional to the corneal ingress of radiolabelled PMNLs. Corneal inflammation induced by intracorneal injection of the PMNL chemotactic agents phorbol myristate acetate (PMA) or endotoxin was also associated with a significant increase in corneal water compared with neutropenic animals. These data strongly suggest that activated PMNLs in the cornea are responsible for the induction of corneal edema in infected corneas.     

Plasminogen kringle 5 inhibits alkali-burn-induced corneal neovascularization

PURPOSE: Plasminogen kringle 5 (K5) is a potent angiogenic inhibitor. The purpose of the present study was to evaluate the therapeutic effect of K5 on alkali-burn-induced corneal neovascularization (NV) and to investigate its mechanism of action. METHODS: Corneal NV was induced in rabbits by NaOH. The rabbits received eye drops containing K5 or vehicle alone, four times per day. Corneal NV and inflammation were monitored every other day with a slit lamp microscope, and the length of the vessels in the cornea and the area of NV were measured. Vascular endothelial growth factor (VEGF) was determined by immunohistochemical and Western blot analyses. The TUNEL assay was used to assess the apoptosis of endothelial cells. The effects of K5 on primary bovine aortic endothelial cells (BAECs) were determined by MTT assay, flow cytometry, transmission electron microscopy, and DNA fragmentation assay. RESULTS: Alkali-burn-induced progressive corneal NV and inflammation in the cornea. K5 delayed the onset of corneal NV (P < 0.05) and decreased NV areas (P < 0.05) in a dose-dependent manner. K5 treatment, after the formation of corneal NV, induced regression of newly formatted vessels in the cornea. K5 decreased the inflammatory index in the corneas at different time points after the alkali burn. Corneal VEGF levels were reduced by K5 treatment. K5 inhibits proliferation and induces apoptosis in BAECs. CONCLUSIONS: Topical application of K5 may have therapeutic potential for the chemical burn-induced corneal NV and inflammation. The inhibitory effect of K5 on corneal NV may be by downregulation of VEGF expression.     

Immune privilege and immunogenicity reside among different layers of the mouse cornea

PURPOSE: To determine the extent to which each layer of the mouse cornea displays alloimmunogenicity or immune privilege. METHODS: Intact corneas or individual or combined layers of corneas from normal or cauterized eyes of BALB/c, C57BL/6, and CD95L-deficient B6-gld mice were grafted beneath the kidney capsule of normal BALB/c, B10.D2, BALB.B mice or of BALB/c mice presensitized to donor antigens. Graft fate was assessed clinically and histologically and acquisition of donor-specific delayed hypersensitivity (DH) was assessed at selected intervals after grafting. RESULTS: Full-thickness allogeneic corneas induced vigorous DH and were rejected acutely. Similar results were obtained with allografts of corneal epithelium alone (if supported by syngeneic viable stroma), allografts of epithelium from cauterized corneas (containing Langerhans' cells), and stromal allografts deprived of endothelium. Grafts comprised of stroma plus endothelium (without epithelium) were not rejected, nor did they induce DH unless the graft had no CD95L expression. If stroma-endothelium grafts had no CD95L expression, DH directed against major histocompatibility complex (MHC), but not minor histocompatibility, alloantigens was induced. Moreover, CD95L expressed on stroma-endothelium grafts protected endothelial cells, but not stromal cells, from rejection in presensitized recipients. CONCLUSIONS: When grafted to a heterotopic site, the alloimmunogenicity of the normal cornea resides within its epithelial and stromal layers, whereas immune privilege arises from the endothelium. In normal mice, CD95L-expressing endothelium can inhibit the stroma from inducing immunity directed at MHC alloantigens, but in presensitized mice the endothelium can protect itself only from immune rejection.     

Avastin对大鼠角膜新生血管的抑制及超微结构的影响

目的:探讨Avastin对角膜新生血管形成及角膜内血管内皮生长因子(VEGF)的影响及其超微结构的影响。方法:Wistar大鼠96只随机分3组,采用碱烧伤的方法制备大鼠角膜新生血管模型;正常不烧伤组4只。烧伤后隔日球结膜下注射0.1mL生理盐水组32只,烧伤后隔日球结膜下注射Avastin0.1mL组32只,烧伤后隔日球结膜下注射地塞米松0.1mL组32只。碱烧伤术后在裂隙灯显微镜下观察大鼠角膜混浊度;宏观测量新生血管长度;组织病理切片HE染色作微血管计数;透射电镜观察超微结构的改变;免疫组化检测角膜VEGF的蛋白表达情况;CD34标记新生血管,显微镜下微血管计数方法研究角膜新生血管形成及抑制情况。结果:治疗组在3,7,10,14d较对照组角膜混浊程度轻(P<0.05);14d形成的新生血管数量较对照组少(P<0.05)。实验组新生血管微血管数量减少,VEGF蛋白表达下降,具有统计学差异。VEGF主要表达在角膜受损区的感染细胞胞质内,其出现时间与位置与角膜新生血管一致。Avastin和地塞米松均可有效抑制角膜新生血管,减少角膜内VEGF表达,两者无统计学差异,结膜下注射Avastin和地塞米松后,大鼠角膜超微结构无除烧伤后其它显著改变。结论:Avastin和地塞米松可抑制角膜新生血管,减少角膜内VEGF表达,对角膜的超微结构均无显著毒性。     

Expression of integrins and MMPs during alkaline-burn-induced corneal angiogenesis

PURPOSE: To determine in a corneal alkaline burn model of angiogenesis whether the expression of integrins and MMPs is consistent with a VEGF-induced angiogenic response. METHODS: Neovascularization in female Sprague-Dawley rats was induced by alkaline cauterization of the central cornea. RT-PCR for integrins alpha(1), alpha(2), beta(3), and beta(5); the endothelial marker CD31; and metalloproteinases MMP-2 and MT1-MMP was performed on naive corneas and on cauterized corneas 72 and 288 hours after cautery. Analyses of protein and MMP expression were conducted on naive corneas and on cauterized corneas 24, 72, 120, and 168 hours after cautery by immunofluorescence microscopy and gelatin zymography. RESULTS: RT-PCR indicated a correlation between the induced angiogenic response and the expression of alpha(1) and beta(3) integrin subunits and MT1-MMP. Immunohistochemical analysis indicated that alpha(1), alpha(2), alpha(5), and beta(5) integrins and MMP-2 and MT1-MMP were expressed on the newly developing vasculature. The beta(3) integrin was preferentially expressed on platelets. CONCLUSIONS: Integrin expression during neovascularization of rat corneas in response to alkaline injury correlates with an angiogenic response that uses the VEGF/alpha(v)beta(5) pathway. MMP-2 and MT1-MMP, but not MMP-9, are expressed in a pattern consistent with their involvement in the angiogenic response.     

A Hypothalamic-Controlled Neural Reflex Promotes Corneal Inflammation

PurposeTo test whether an acute corneal injury activates a proinflammatory reflex, involving corneal sensory nerves expressing substance P (SP), the hypothalamus, and the sympathetic nervous system.MethodsC57BL6/N (wild-type [WT]) and SP-depleted B6.Cg-Tac1tm1Bbm/J (TAC1-KO) mice underwent bilateral corneal alkali burn. One group of WT mice received oxybuprocaine before alkali burn. One hour later, hypothalamic neuronal activity was assessed in vivo by magnetic resonance imaging and ex vivo by cFOS staining. Some animals were followed up for 14 days to evaluate corneal transparency and inflammation. Tyrosine hydroxylase (TH), neurokinin 1 receptor (NK1R), and neuronal nitric oxide synthase (nNOS) expression was assessed in brain sections. Sympathetic neuron activation was evaluated in the superior cervical ganglion (SCG). CD45⁺ leukocytes were quantified in whole-mounted corneas. Noradrenaline (NA) was evaluated in the cornea and bone marrow.ResultsAlkali burn acutely induced neuronal activation in the trigeminal ganglion, paraventricular hypothalamus, and lateral hypothalamic area (PVH and LHA), which was significantly lower in TAC1-KO mice (P < 0.05). Oxybuprocaine application similarly reduced neuronal activation (P < 0.05). TAC1-KO mice showed a reduced number of cFOS⁺/NK1R⁺/TH⁺ presympathetic neurons (P < 0.05) paralleled by higher nNOS expression (P < 0.05) in both PVH and LHA. A decrease in activated sympathetic neurons in the SCG and NA levels in both cornea/bone marrow and reduced corneal leukocyte infiltration (P < 0.05) in TAC1-KO mice were found. Finally, 14 days after injury, TAC1-KO mice showed reduced corneal opacity and inflammation (P < 0.05).ConclusionsOur findings suggest that stimulation of corneal sensory nerves containing SP activates presympathetic neurons located in the PVH and LHA, leading to sympathetic activation, peripheral release of NA, and corneal inflammation.     

Rapid ocular angiogenic control via naked DNA delivery to cornea

PURPOSE: To determine the efficacy and safety of naked plasmid gene therapy to the corneal stroma and epithelium. METHODS: Naked plasmid DNA was injected under pressure into the cornea of mice. The expression of genes coding for beta galactosidase (beta-gal), enhanced green fluorescent protein (EGFP), vascular endothelial growth factor (VEGF), and soluble Flt-1 (s-Flt) was recorded and measured with regard to dose, time course, and bioactivity. RESULTS: LacZ gene expression of the protein beta-gal was demonstrated as early as 1 hour, with expression persisting for 10 days. Plasmid-injected corneas remained clear and free of inflammation. EGFP was bicistronically expressed with VEGF to demonstrate the practicality of simultaneous in vivo analysis of gene expression and growth factor bioactivity. Corneal injection of a plasmid containing VEGF cDNA induced corneal and anterior chamber neovascularization. Moreover, corneal injection of plasmid containing the cDNA for the soluble form of the VEGF receptor Flt-1 effectively prevented corneal neovascularization. CONCLUSIONS: The cornea is readily accessible for gene therapy in the laboratory and in the clinic. The method described is safe, effective, titratable, and easily monitored. Naked DNA delivery to the cornea has the potential to alter the treatment of a wide variety of corneal and anterior segment diseases.     

Upregulation of CD4+ NKT cells is important for allograft survival in staphylococcal-enterotoxin-B-treated rats after high-risk corneal transplantation

OBJECTIVE: To study the role of CD4+ natural killer T (NKT) cells in staphylococcal-enterotoxin-B (SEB)-treated rats after high-risk corneal transplantation. METHOD: Fisher 344 donor corneas were transplanted into Lewis recipients. Corneal neovascularization was induced by sutures. All the recipients were randomly divided into 3 groups. The SEB group was intraperitoneally injected with SEB at a concentration of 75 microg/kg. The drug combination group received SEB and dexamethasone at a concentration of 5 mg/ml. The control group received saline buffer. All transplants were evaluated for 30 days. Ten days after transplantation, 3 recipients in each group were sacrificed for immunological study. RESULT: The survival time of the allografts in the SEB group was 12.50 +/- 1.41 days, much longer than in the control group (7.30 +/- 0.67 days) and the drug combination group (10.38 +/- 3.07 days). The lymphocyte proliferation ability was the weakest and the percentage of CD4+ NKT cells in both the spleen and the mandibular lymph nodes was the highest in the SEB group, while the percentage of CD4+ and CD8+ cells was the lowest in the drug combination group. IL-2 in the aqueous humor and the serum was lower while IL-10 was higher in the SEB group than in the other 2 groups. CONCLUSION: SEB prolongs allograft survival in rat high-risk corneal transplantation. This effect seems to be mediated by the upregulation of CD4+ NKT cells.     

EntransterTM纳米载体介导大鼠角膜CD25siRNA转染的效果及安全性评估

背景 基因转染是多种眼病基因治疗的有效方法,理想的非病毒载体是研究角膜基因治疗的关键因素,选择高转染率、基因高表达、低毒性的非病毒载体是成功实施基因治疗的前提. 目的 探讨EntransterTM、脂质体非病毒载体对正常SD大鼠角膜转染CD25 siRNA的转染率和安全性,筛选角膜基因转染的最佳载体.方法 应用随机数字表法将80只雄性SPF级成年SD大鼠随机分为EntransterTM-CD25 siRNA 组、脂质体-CD25 siRNA组、单纯CD25 siRNA组和生理盐水组,每组20只,均以右眼作为实验眼.实验眼眼表麻醉后刮除角膜上皮,按照分组不同分别用EntransterTM-CD25 siRNA、脂质体-CD25 siRNA、单纯CD25siRNA和生理盐水各50μl点眼.于点眼后12h、24 h、3d和7d在裂隙灯显微镜下观察大鼠眼表组织反应,检查各组大鼠角膜表面绿色荧光个数.分别于上述时间点处死各组大鼠各4只并获取角膜组织,采用苏木精-伊红染色法行角膜组织病理学检查;采用罗丹明染色行荧光检测,评估各组大鼠角膜基因转染的转染率;采用TUNEL染色法检测实验眼角膜细胞的凋亡情况以评估各种转染载体的安全性;采用免疫荧光技术检测角膜组织中CD11b的表达. 结果 EntransterTM-CD25 siRNA组大鼠角膜表面的荧光染色数量及强度明显高于脂质体-CD25 siRNA组,单纯CD25 siRNA组大鼠角膜荧光染色出现早,但转染后24 h角膜荧光染色消失.角膜组织病理学检查显示,各组大鼠行基因转染后脂质体-CD25 siRNA组大鼠角膜上皮水肿和角膜炎性细胞浸润程度较EntransterTM-CD25 siRNA组、单纯CD25 siRNA组和生理盐水组严重,角膜基质层和内皮层未发现异常,脂质体-CD25 siRNA组大鼠角膜炎性细胞数明显多于EntransterTM-CD25 siRNA组、单纯CD25 siRNA组和生理盐水组,差异均有统计学意义(均P=0.00).TUNEL检测发现,基因转染后12h和3d,脂质体-CD25siRNA组大鼠角膜细胞凋亡数明显多于EntransterTM-CD25 siRNA组、单纯CD25 siRNA组和生理盐水组,差异均有统计学意义(均P=0.00).免疫荧光检测显示,CD11b荧光主要分布于角膜上皮层和角膜基质层,随着基因转染后时间的延长,脂质体-CD25 siRNA组大鼠角膜组织中CD11b的表达量逐渐增加,基因转染后24 h时荧光强度达峰,随后逐渐减弱,至转染后第7天仍可见弱荧光.EntransterTM-CD25 siRNA组、单纯CD25siRNA组和生理盐水组大鼠角膜组织中均未发现CD11b的荧光表达. 结论 EntransterTM纳米材料作为载体转染CD25 siRNA于正常SD大鼠角膜具有转染效率高、毒性低、不引起角膜免疫反应的特点,可作为角膜疾病基因治疗的合适载体.     

Suppression of alkali burn-induced corneal neovascularization by dendritic cell vaccination targeting VEGF receptor 2

PURPOSE: To investigate whether the induction of cytotoxic T lymphocytes (CTLs) targeting VEGF receptor 2 inhibits corneal neovascularization caused by alkali injury. METHODS: H-2Db-restricted peptide corresponding to amino acids 400 to 408 of VEGF receptor 2 (VEGFR2(400-408)) was used as an epitope peptide. Dendritic cells (DCs) were harvested from bone marrow progenitors of C57BL/6 mice. Six-week-old C57BL/6 mice received subcutaneous injections of VEGFR2(400-408)- or gp70-pulsed mature DCs three times at 6-day intervals. After the third immunization, corneal neovascularization was induced by alkali injury. Two weeks after the injury, the corneal vascularized area was evaluated by lectin angiography. To confirm the peptide-specific CTL activities in C57BL/6 mice, CD8(+) T cells from immunized mice were subjected to ELISA for interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production and (51)Cr-release cytotoxicity assay. To determine the in vivo effector T cells, the immunized mice were intraperitoneally injected with an anti-CD4 or -CD8 depletion antibody. RESULTS: Corneal neovascularization was significantly attenuated in mice immunized with VEGFR2(400-408) compared with those not immunized or immunized with gp70. VEGFR2(400-408) or gp70, but not beta-gal(96-103), application led to dose-dependent induction of IFN-gamma and TNF-alpha in the CD8(+) T cells cocultured with stimulator cells. Cytotoxicity assays showed the specific lysis of major histocompatibility complex-matched cells expressing VEGFR2, but not beta-gal(96-103). In vivo depletion of CD8(+), but not CD4(+), T cells significantly reversed the suppressive effect of VEGFR2(400-408) immunization on corneal neovascularization to the level observed in nonimmunized or gp70-immunized animals. CONCLUSIONS: These results indicate the possibility of DC vaccination targeting VEGFR2 as a novel therapeutic strategy for corneal chemical injury.     

Quantitative evaluation of the corneal endothelium in the mouse after grafting

BACKGROUND/AIM: Corneal graft survival depends critically on the quality of the endothelium. In this study the authors aimed to evaluate corneal endothelium in mice at different times after transplantation and to correlate endothelial integrity with corneal graft survival. METHODS: Syngeneic and allogeneic corneal grafts at various times (days 0-60) after engraftment were examined in flat mount preparation by confocal microscopy, by evaluating the hexagonal pattern of the endothelial monolayer using actin staining of the cell cortex. Corneas from untreated mice and from mice, who were grafted after removal of draining lymph nodes served as controls. RESULTS: In control corneas, more than 90% of the posterior surface was covered by endothelium. Syngeneic grafts were always covered by 54-99% of endothelium. In contrast, the posterior surface of corneal allografts showed great variation in the degree of endothelial cell coverage (0-98%). In addition, clinical opacity grading measure was not a reliable predictor of endothelial coverage. CONCLUSION: In corneal allografts there is progressive loss of endothelium over time, unlike with syngeneic grafts. However, in the early stages of allograft rejection, the grade of graft opacity does not accurately reflect the degree of endothelial cell coverage. Although corneal opacity grade is considered the main determinant of graft rejection, the data suggest that both the grade of corneal opacity plus a sufficient post-graft time duration (>8 weeks in the mouse) are required for the diagnosis of irreversible graft rejection.     

基于流式细胞术快速定量分析小鼠角膜组织中嗜中性粒细胞方法的建立

目的:建立一种基于流式细胞术快速定量分析小鼠角膜组织中嗜中性粒细胞的技术和方法。方法:选取6～8周龄SPF级雌性C57BL/6小鼠15只,使用高尔夫样刀机械性刮除小鼠角膜上皮细胞层,生成直径2 mm的创面,在创伤后18 h切除带有完整角膜缘的小鼠角膜,采用胶原酶I和DNA酶联合消化法获得单细胞悬液,采用FACSCant...     

Development of new lymphatic vessels in alkali‐burned corneas

Purpose: Corneal lymphangiogenesis provides an exit route for antigen‐presenting cells to regional lymph nodes, inducing immune response. The purpose of this study was to examine the development of corneal lymphatic vessels in alkali‐burned corneas. Methods: Corneal lymphatic vessels were examined by electron microscopy, 5′‐nase‐alkaline phosphatase (5′‐NA‐ALP) double enzyme‐histochemistry and whole mount immunofluorescence at 6 hr, 1 day, 3 days, and 1, 2, 3, 4, 5, 6, 7 and 8 weeks after rat corneal alkali injury. The expression of vascular endothelial growth factor‐C (VEGF‐C) protein and mRNA was examined 1, 3, 5, 7, 9, 11 and 14 days after the injury. Results: Corneal lymphangiogenesis developed 3 days after alkaline burns, reached its peak 2 weeks after the injury, decreased gradually and disappeared at the end of the fifth week. The expression of VEGF‐C in burned corneas increased dramatically on the third day but disappeared the 14th day after the injury. Conclusion: Corneal lymphatic vessels develop after alkaline burns and VEGF‐C may play an important role in corneal lymphangiogensis.     

The role of PDGF receptor inhibitors and PI3-kinase signaling in the pathogenesis of corneal neovascularization

PURPOSE: Corneal neovascularization remains an unsolved therapeutic problem. Platelet-derived growth factor (PDGF) is directly linked to vessel formation and stabilization. This study was undertaken to elucidate the mechanisms by which PDGF exerts its effects on corneal angiogenesis. METHODS: Corneal neovascularization was induced in C57 mice by removal of the limbal epithelium. When mature vessels appeared after 7 days, mice were treated with the PDGF receptor-beta inhibitor AG 1296 or the phosphatidylinositol 3-kinase (PI3-K)-inhibitors wortmannin and LY294002, respectively, using an intraperitoneally implanted miniosmotic pump. At day 14 after scraping, corneas of treated and untreated (control) mice were dissected and immunostained with FITC-CD31 antibody for endothelial cells and with Cy3-SMA (smooth muscle actin) for pericytes. VEGF (vascular endothelial growth factor), ang1/2 (angiopoietin 1 and 2), and PDGF mRNA levels of treated and untreated corneas were determined by real-time RT-PCR. RESULTS: Mice treated with the PDGF inhibitor AG 1296 showed an inhibition of corneal neovascularization of 21.1% and a reduction of pericytes of 52% in the newly formed vessels compared with untreated animals. VEGF, ang1, ang2, and PDGF mRNA expression was reduced in the corneas of AG 1296-treated mice compared with the respective control. Treatment with the PI3-K inhibitors wortmannin and LY29002 had similar effects, inducing a decrease in corneal neovascularization and a reduction of VEGF, ang1, ang2, and PDGF mRNA levels. CONCLUSIONS: Inhibition of the PDGF signal pathway results in loss of pericytes and a reduction in vessel density in the neovascularized cornea that correlates with reduced expression of PDGF, ang1/2, and VEGF mRNA. Furthermore, PI3-K was shown to be involved in the regulation of VEGF, ang1, and PDGF, as the PI3-K inhibitors wortmannin or LY294002 had similar effects. Because PDGF is a known stimulus for PI3-K activation, it can be postulated that the observed decrease in VEGF, ang1/2, and PDGF mRNA levels on administration of the PDGF inhibitor is caused by the decreased activation of the PI3-K signaling cascade.