The role of soluble TNF receptors for TNF-alpha in uveitis

PURPOSE: To investigate the presence of soluble tumor necrosis factor receptors (sTNF-Rs) and TNF-alpha in the ocular fluids of patients with uveitis and the capacity of sTNF-Rs to affect TNF-alpha production by intraocular T cells. METHODS: Ocular fluid samples were collected from patients with active and inactive uveitis, as well as from control subjects without uveitis. The sTNF-Rs and TNF-alpha levels were measured by enzyme-linked immunosorbent assay (ELISA). T-cell clones (TCCs) were established from intraocular infiltrating cells, and the TCCs were cocultured with recombinant sTNF-Rs or TNF-alpha. The supernatants were measured by ELISA. The neutralization of sTNF-R production by TCCs was evaluated with an anti-human TNF-R antibody. RESULTS: Significantly higher amounts of sTNF-R1 and -R2 were present in the ocular fluids of patients with active uveitis than in the ocular fluids of those with inactive uveitis and in control subjects. Significantly higher amounts of TNF-alpha were present in the ocular fluids of patients with active uveitis than in those with inactive uveitis. Recombinant sTNF-Rs enhanced TNF-alpha production by TCCs in a dose-dependent manner. Similarly, recombinant TNF-alpha enhanced sTNF-Rs production by the TCCs, and production was neutralized with anti-human TNF-R antibody. CONCLUSIONS: sTNF-Rs are present in the ocular fluids of patients with uveitis. Intraocular levels of sTNF-Rs are significantly increased in patients with uveitis, particularly in those with active uveitis. The data suggest that intraocular sTNF-Rs may play a regulatory role in ocular inflammation such as occurs in uveitis.     

Capacity of ocular infiltrating T helper type 1 cells of patients with non-infectious uveitis to produce chemokines

BACKGROUND/AIMS: Chemokines are key molecules that initiate leucocyte infiltration to the inflammatory site. The involvement of chemokines in uveitis is well studied, yet the source of this molecule in the inflamed eye is not clearly identified. The possible sources of chemokines are ocular resident cells or the inflammatory cells infiltrated to the eye. Here the authors examined whether ocular infiltrating T cells of uveitis patients do produce chemokines. METHODS: T cell clones (TCCs) were established from ocular infiltrating cells of patients with non-infectious uveitis. TCCs were characterised using flow cytometry. Spontaneous production of chemokines by TCCs was evaluated by ELISA. RESULTS: TCCs from ocular infiltrating cells were revealed to be memory activated Th1 type CD4 positive cells. Those TCCs produced larger amounts of chemokines than TCCs from peripheral blood mononuclear cells of uveitis or healthy donors. CONCLUSIONS: The present data indicate that ocular infiltrating T cells of patients with non-infectious uveitis produce chemokines and recruit further infiltrating lymphoid cells. Such T cells may have roles in the prolonged/chronic state of non-infectious uveitis.     

Human corneal epithelial cells synthesize ELR(-)alpha-chemokines in response to proinflammatory mediators

The purpose of this study was to characterize the synthesis of alpha-chemokines IP-10, MIG, and I-TAC by human corneal epithelial cells (HCE) following exposure to proinflammatory mediators. Supernatants were collected from HCE cultures stimulated with individual or combinations of TNF-alpha, IL-1alpha, and IFN-gamma, and assayed for alpha-chemokines by ELISA. RT-PCR was used to detect IFN-gamma receptor mRNA. Activation of STAT 1 was determined by Western blotting. Stimulation of HCE with either IL-1alpha or TNF-alpha increased IP-10 protein synthesis up to 6-fold, whereas insignificant levels of MIG and I-TAC were induced. The epithelial cells were found to express IFN-gamma receptors constitutively. Exposure to the ligand resulted in STAT 1 phosphorylation and production of nanogram amounts of IP-10, I-TAC, and MIG. When HCE were stimulated with combinations of TNF-alpha and IFN-gamma, or IL-1alpha and IFN-gamma, the levels of IP-10 and I-TAC secreted were > 150-fold higher than that produced following exposure to a single cytokine. In contrast, MIG protein synthesis was not enhanced upon stimulation with cytokine combinations. The abundant production of ELR(-)alpha -chemokines following appropriate stimulation suggests that HCE may play an important role in the recruitment of effector cells such as activated T-lymphocytes to inflamed corneal tissue. The data also indicate that the synthesis of IP-10, I-TAC, and MIG are differentially regulated in HCE.     

Macrophage migration inhibitory factor in ocular fluids of patients with uveitis

AIMS: To investigate the levels of macrophage migration inhibitory factor (MIF) in intraocular fluids of uveitis patients, the capacity of intraocular infiltrating lymphocytes to produce MIF, and the correlation between MIF levels in the eye and intraocular inflammatory activity. METHODS: MIF levels were measured by enzyme linked immunosorbent assay (ELISA) using (1) aqueous humour (AH) of 12 uveitis patients and eight control patients with cataract, (2) vitreous fluid of 15 uveitis patients and eight control patients with idiopathic macular hole, and (3) culture supernatants of T cell clones (TCCs) established from intraocular fluids of uveitis patients. MIF expression on infiltrating cells was determined by a double staining immunofluorescence technique using a flow cytometry. RESULTS: Significant levels of MIF were detected from intraocular fluids of uveitis patients (4.0 (SD 3.0) ng/ml in AH and 16.5 (24.7) ng/ml in vitreous), whereas MIF levels in control groups were below the detectable levels. There was a significant correlation between MIF levels and vitreous inflammation (29.7 (30.0) ng/ml in active uveitis v 3.3 (2.6) ng/ml in inactive uveitis, p< 0.05). Significant levels of MIF were detected in culture supernatants of TCCs from ocular fluids of uveitis patients. MIF was expressed on infiltrating CD4+ lymphocytes from vitreous of uveitis patients. CONCLUSION: Significant levels of MIF are present in intraocular fluids of patients with uveitis. Lymphocytes infiltrating in the eye are capable of producing MIF. MIF levels in vitreous fluid are correlated with vitreous inflammation activity. These data thus indicate that MIF in the eye has a significant role in the pathophysiology of ocular inflammation.     

Characterization of Toxoplasma gondii-specific T cells recovered from vitreous fluid of patients with ocular toxoplasmosis.

PURPOSE: The mechanisms involved in reactivations of latent ocular Toxoplasma gondii (Tg) infections in immunocompetent patients are poorly understood. In view of the possible role of T cells in the immunopathogenesis of the disease, ocular infiltrating T cells obtained from patients with recurrent ocular toxoplasmosis were characterized phenotypically and functionally. METHODS: Ocular infiltrating T cells were recovered from vitreous fluid (VF) samples of 10 patients with active recurrent ocular toxoplasmosis. Two patients with uveitis of other origins were included as control subjects. T-cell lines (TCLs) were generated by mitogenic stimulation and tested for reactivity to Tg and human retinal protein extracts. The TCLs of three patients were cloned by limiting dilution. Tg-reactive T-cell clones (TCCs) were characterized with respect to their phenotype, T-cell receptor variable (TCR V)-beta gene usage, HLA restriction, and cytokine secretion profile. RESULTS: Reactivity to Tg could be detected only in the TCLs of patients with ocular toxoplasmosis. None of the TCLs showed reactivity to human retinal antigens. All tested intraocular Tg-specific TCCs (n = 23) were CD3+CD4+ and displayed differential TCR Vbeta usage. Twenty-one TCCs were HLA-DR restricted and two TCCs were restricted by HLA-DP. The majority of the intraocular Tg-specific TCCs showed a bias toward a T-helper (Th)0-Th2 cytokine profile. CONCLUSIONS: The data indicate that T cells specific for the triggering microorganism infiltrate the eye of patients with recurrent ocular toxoplasmosis. The functional characteristics of the VF-derived Tg-specific T cells and their presence at the site of inflammation suggest their involvement in the local inflammatory response of ocular toxoplasmosis.     

突变型Myocilin真核表达载体的构建及体外表达

目的:构建P370L突变型Myocilin真核表达载体及体外转染体系,为Myocilin功能研究提供实验基础。方法:应用定点诱变技术进行Myocilin基因第1131位氨基酸残基位点的定点突变,利用阳离子脂质体介导体外转染技术瞬时转染人小梁细胞,RT-PCR和WesternBlot检测Myocilin表达.结果:经克隆、测序证实获得突变基因,突变载体转染后人小梁细胞MyocilinmRNA和Myocilin蛋白质表达显著增加。结论:P370L突变型Myocilin真核表达载体成功构建,阳离子脂质体是人小梁细胞有效的体外转染体系。     

Role of IL-12 and IFN-gamma in Pseudomonas aeruginosa corneal infection

PURPOSE: In Pseudomonas aeruginosa ocular infection, T-helper cell 1-responsive mouse strains are susceptible (the cornea perforates), and neutralization of IFN-gamma before infection has been shown to delay the onset of perforation. IFN-gamma is the predominant cytokine induced by IL-12, and positive regulation of IL-12 by IFN-gamma, if unchecked, leads to excessive cytokine production and toxicity. Despite its potential importance, the role of IL-12 in ocular infection with P. aeruginosa remains unexplored and was the purpose of this study. METHODS: IL-12 knockout mice, histopathology, RT/PCR and ELISA analyses, immunocytochemistry, and quantitation of viable bacteria in cornea were used to examine the role of IL-12 in IFN-gamma production and the susceptibility phenotype. RESULTS: To directly test the effect of IL-12 on IFN-gamma production, IL-12 knockout and wild-type C57BL/6 mice were used. Both groups of mice were susceptible to infection, with corneal perforation seen at 5 to 7 days after infection. RT-PCR and ELISA analyses confirmed that IL-12 message and protein levels were elevated after infection only in the wild-type mouse cornea. Other differences between the two groups were detected. Knockout versus wild-type mice showed a significant decrease in IFN-gamma mRNA levels in the cornea and cervical lymph nodes and decreased TNF-alpha protein levels in cornea. Corneas of knockout mice also had a significant increase in bacterial load at 5 days after infection when compared with wild-type mice. CONCLUSIONS: These data provide evidence that IL-12 is important in IFN-gamma production and in the absence of the cytokine, both IFN-gamma and TNF-alpha levels in cornea are significantly decreased, resulting in unchecked bacterial growth and perforation.     

Identification of autoreactive T cells in Vogt-Koyanagi-Harada disease

PURPOSE: To determine the finer specificity and immunologic features of autoreactive T cells in Vogt-Koyanagi-Harada (VKH) disease. METHODS: T-cell clones (TCCs ) specific to tyrosinase family proteins were raised from the peripheral blood mononuclear cells (PBMCs) of patients with VKH disease, and the response of the TCCs to 30-mer peptides was determined. The TCCs that were reactive to the peptides with strong binding sites for HLA DRB1*0405 were initially tested. Then, a finer specificity of these TCCs against 12- to 14-mer peptides was determined. The cytokine production of these clones was measured by ELISA. RESULTS: A total of 62 stable TCCs were established from the PBMCs of five patients with VKH (28 clones against tyrosinase, 34 clones against tyrosinase-related protein [TRP]1). Five of 28 TCCs for tyrosinase and 2 of 34 for TRP1 were reactive to the 30-mer peptides with strong binding sites for HLA DRB1*0405. These seven clones showed proliferative responses to one or more of the 12- to 14-mer peptides that match the motif of the strong binding site for HLADRB1*0405. Five of seven of the TCCs may be T-helper (Th) type 1, one of the remaining TCCs may be Th0, and the other may be Th2. CONCLUSIONS: The autoreactive T cells against tyrosinase and/or TRP1 may contribute to the development of VKH disease.     

Participation of pigment epithelium of iris and ciliary body in ocular immune privilege. 2. Generation of TGF-beta-producing regulatory T cells

PURPOSE: To determine whether T cells exposed to cultured iris and ciliary body pigment epithelial (I/CB PE) cells acquire the capacity to modify the activation, differentiation, and effector functions of bystander T cells, and if so, to identify the mechanism. METHODS: T cells from naive BALB/c mice were cultured with I/CB PE cells, x-irradiated, and used as regulators (a) of T-cell activation in vitro and (b) of delayed hypersensitivity expression in vivo. Neutralizing anti-TGF-beta and -IL-10 antibodies were used to abolish regulatory function. T-cell activation was assessed for proliferation by [(3)H]thymidine incorporation and for IL-2, IFN-gamma, IL-4, and IL-10 production by semi-quantitative RT-PCR for mRNA and by supernatant analysis by ELISA. I/CB PE-exposed T cells were evaluated for mRNA content of IFN-gamma, IL-4, TNF-alpha, TGF-beta1, TGF-beta2, and IL-10, and their supernatants were analyzed for content of TGF-beta. RESULTS: T cells exposed to I/CB PE cells inhibited anti-CD3-driven activation of bystander naive T cells in vitro and suppressed the expression of delayed hypersensitivity in vivo. Bystander T cells cocultured with I/CB PE-exposed T cells failed to proliferate and secreted high levels of IL-4 and IL-10 but low amounts of IL-2 and IFN-gamma. Regulation of bystander T-cell activation was mediated via enhanced secretion of TGF-beta by I/CB PE-exposed T cells. CONCLUSIONS: T cells exposed to cultured I/CB PE cells were induced to secrete active and latent TGF-beta, which conferred on the T cells the capacity to inhibit the differentiation as well as the effector function of Th1-type cells.     

Cytokine Production by T Cells Infiltrating in the Eye of Uveitis Patients

The capacity of T cells to produce cytokines was investigated using T-cell clones (TCCs) established from infiltrating cells in the aqueous humor (AH) or peripheral blood mononuclear cells (PBMC) of patients with Vogt-Koyanagi-Harada (VKH) disease or sarcoidosis. The cytokines produced and tested in the study were interleukin (IL)-1α, IL-6, IL-8, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and granulocyte monocyte colony stimulating factor (GM-CSF). All TCCs (n = 9) from AH of VKH patients spontaneously produced significantly larger amounts of IL-6, IL-8, and IFN-γ than TCCs from healthy donor PBMC. All TCCs (n = 9) from AH of the sarcoidosis patient spontaneously produced significantly larger amounts of IL-1α, IL-6, and IL-8 than TCCs from healthy donor PBMC. In addition, the effects of antiinflammatory drugs on the cytokine production by the TCCs were investigated. Hydrocortisone significantly suppressed the production of IL-6, IL-8, and GM-CSF by TCCs from AH of VKH patients. Tacrolimus also significantly suppressed the production of IL-8 and GM-CSF by the TCCs. FTY720, an experimental drug, suppressed only GM-CSF production by TCCs from AH of VKH patients. Diclofenac failed to suppress the production of any cytokines by any TCCs. All tested drugs did not suppress the production of cytokines by TCCs from the sarcoidosis patient. These results thus suggest that cytokines produced by T cells infiltrating in the eye may play an important role in the pathogenesis of uveitis.     

Induction of tissue transglutaminase in the trabecular meshwork by TGF-beta1 and TGF-beta2

PURPOSE: To study whether human trabecular meshwork (HTM) cells are capable of expressing and secreting tissue transglutaminase (tTgase), an enzyme cross-linking extracellular matrix (ECM) proteins, and whether tTgase and synthesis of cross-linked fibronectin are increased after treatment of HTM cells with transforming growth factor (TGF)-beta1 or -beta2. METHODS: Anterior segments of six normal human eyes were stained with antibodies to tTgase. Tissues from three eyes were analyzed for tTgase using Western blot analysis. Monolayer cultures of HTM cells from eyes of five human donors were treated with 1.0 ng/ml TGF-beta1, -beta2, or 5 X 10(-7) M dexamethasone (DEX) for 12 to 96 hours. Induction of tTgase was investigated by Western and Northern blot analysis. External tTgase activity was measured by the ability to form polymerized fibronectin and the incorporation of biotinylated cadaverine into fibronectin. RESULTS: Labeling for tTgase was observed throughout the entire HTM. Cultured HTM cells expressed tTgase intra- and extracellularly. Treatment of cultured HTM cells with TGF-beta1 and -beta2 increased the tTgase mRNA and protein levels, whereas DEX had no effect. TGF-beta-treated HTM cells showed a significant increase in polymerized and unpolymerized fibronectin. Incorporation of biotinylated cadaverine was markedly increased when HTM cells were treated with TGF-beta for 24 hours before seeding. CONCLUSIONS: The enzyme tTgase is expressed in the HTM and is inducible by TGF-beta1 or -beta2 in cultured HTM cells. Extracellular tTgase is able to polymerize fibronectin. Increased levels of TGF-beta2 in the aqueous humor may lead to an increase of tTgase expression and activity in the HTM, causing an increase of irreversibly cross-linked ECM proteins. This mechanism might play a role for the increased outflow resistance seen in glaucomatous eyes.     

Ocular infiltrating CD4+ T cells from patients with Vogt-Koyanagi-Harada disease recognize human melanocyte antigens

PURPOSE: To determine whether patients with Vogt-Koyanagi-Harada (VKH) disease have immune responses specific to the melanocyte antigens tyrosinase and gp100. METHODS: T-cell clones (TCCs) were established from cells infiltrating the aqueous humor and from peripheral blood mononuclear cells (PBMCs) of patients with VKH. The target cells were LDR4-transfected cells (HLA-DRB1*0405). The TCCs were cocultured with LDR4 in the presence of tyrosinase (tyrosinase450-462: SYLQDSDPDSFQD), gp100 (gp100(44-59): WNRQLYPEWTEAQRLD), or a control peptide. The immune response was evaluated by cytokine production. The responding melanocyte peptide-specific VKH-TCCs were characterized by an immunofluorescence method with flow cytometry. A search was made for molecular mimicry among tyrosinase450-462, gp100(44-59), and exogenous antigens, such as viruses, by database screening. RESULTS: Cells infiltrating the eye and PBMCs in HLA-DR4+ (HLA-DRB1*0405, 0410) patients with VKH contained a population of CD4+ T lymphocytes that recognized tyrosinase and gp100 peptides and produced RANTES and IFN-gamma in response to the two peptides. The T cells were active memory Th1-type lymphocytes, and they recognized the tyrosinase peptide and produced IFN-gamma in response to HLA-DRB1*0405+ melanoma cells. Cytomegalovirus envelope glycoprotein H (CMV-egH290-302) had high amino acid homology with the tyrosinase peptide. In addition, some of the VKH-TCCs recognized CMV-egH290-302 peptide, as well as the tyrosinase peptides. CONCLUSIONS: In VKH there are tyrosinase and gp100 peptide-specific T cells that can mediate an inflammatory response. Such melanocyte antigen-specific T cells could be associated with the cause and pathology of VKH disease.     

IL-4 regulates chemokine production induced by TNF-α in keratocytes and corneal epithelial cells

BACKGROUND: Eosinophils are thought to play a major role in the pathogenesis of corneal lesions in ocular allergies. The regulation of chemokine production in corneal cells by the Th2 cytokine, interleukin 4 (IL-4), was examined in order to investigate its role in ocular allergies. METHODS: Pure cultures of human corneal epithelial cells and keratocytes were exposed to tumour necrosis factor alpha (TNF-alpha) and/or IL-4. 24 hours after exposure, culture supernatants were removed and concentrations of IL-8 and RANTES were quantified by ELISA assay. RESULTS: Simultaneous addition of IL-4 inhibited TNF-alpha induced IL-8 production in both corneal epithelial cells and keratocytes. TNF-alpha and IL-4 synergistically stimulated the production of RANTES in keratocytes. CONCLUSION: Differential regulation of chemokine production from corneal cells by IL-4 may play a role in the selective recruitment of predominantly eosinophils to the ocular surface in ocular allergies.