58 research outputs found
Characterization of dendritic cell phenotype in allergic conjunctiva: increased expression of Fc epsilon RI, the high-affinity receptor for immunoglobulin E
No full textAbstract
PURPOSE:
Dendritic cells (DCs) express the high-affinity receptor for IgE (Fc(epsilon)RI) on their surface, which may enhance their ability to capture and internalize antigens for presentation to T-lymphocytes. The aim of this study was to determine if expression of Fc(epsilon)RI(+) DCs is increased in the conjunctivae of vernal keratoconjunctivitis (VKC) patients compared with those of normal controls.
METHODS:
Conjunctival biopsies were obtained from non-atopic and VKC patients. Double immunohistochemical staining was carried out using antibodies against Fc(epsilon)RI and the CD1a antigen, a DC marker. The double-positive cells were counted in five representative fields of view for each conjunctival sample.
RESULTS:
Fc(epsilon)RI(+) CD1a(+) cells were present in significantly higher numbers in VKC conjunctivae compared with normal controls (mean cell count of 21.3 in VKC vs5.0 in controls, P<0.005). In normal patients the Fc(epsilon)RI-expressing DCs tended to be confined to the epithelial layer or the superficial substantia propria, but in the VKC samples these Fc(epsilon)RI(+) cells were mainly concentrated in the deeper substantia propria.
CONCLUSIONS:
Fc(epsilon)RI(+) DC numbers are elevated in the conjunctivae of VKC patients, a finding consistent with the results of other studies focusing on atopic conditions. Elevated expression of Fc(epsilon)RI on DCs would facilitate antigen presentation and enhance T-cell priming, thereby contributing to ocular symptoms
Characterisation of the phenotype and function of monocyte-derived dendritic cells in allergic conjunctiva
No full textAbstract
BACKGROUND:
Dendritic cells (DCs) are the most potent antigen-presenting cells involved in initiating the immune response, presenting antigens to T cells and leading to T cell proliferation. In an immature state, DCs lack accessory signals required for T cell stimulation but are highly specialised to capture antigens. Full DC maturation changes the cell surface phenotype and facilitates stimulation of T cell proliferative responses. To examine the degree of DC maturity associated with vernal keratoconjunctivitis (VKC), the authors examined the phenotype and antigen-presentation capability of blood derived DCs from VKC patients and from normal controls.
METHODS:
Flow cytometry was used to identify the cell surface expression of markers of DC maturity (CD83, CD86, major histocompatibility complex class II) and mixed leucocyte reactions to assess DC induction of T cell proliferation.
RESULTS:
DCs derived from VKC patients were of a more mature phenotype than those from normal controls. However, these VKC DCs had reduced capability for induction of T cell proliferation compared with DCs from controls.
CONCLUSION:
The increased maturity of DCs in VKC patients correlates with the heightened immune responsiveness associated with this disorder. A number of mechanisms may underlie the impaired ability of DCs in atopy to stimulate T cell proliferation. This impairment of DC induction of T cell activation is likely to be one factor which contributes to the modified inflammatory response seen in VKC patients and the recognised susceptibility of these patients to viral infection
Gene therapy approaches to disease of the cornea and anterior chamber
No full textThe field of ocular gene therapy has become one of the most developed areas within the wider gene therapy field, however most work to date has focused upon the retina with the cornea, by comparison, having seen relatively little application of gene therapy. This thesis describes a program of work to further develop viral gene therapy approaches to the three cellular layers of the cornea, with particular emphasis upon the application of novel vector technologies and overcoming the various challenges presented by each layer. Gene therapy of the corneal endothelium has to date largely aimed to increase or maintain endothelial cell density to improve the quality of donor corneas for engraftment. Such a strategy however carries an inherent risk of oncogenesis and this study has therefore aimed to improve the safety profile of endothelial gene delivery methods. The transduction profile of various AAV serotypes within the corneal stroma was also investigated, and the most promising results applied in an augmentation gene therapy approach to prevent corneal neovascularisation. The selected methodology is shown to mediate high level transgene expression and, when delivering the antiangiogenic factor sFlt1, was highly effective in preventing haem (but not lymph) angiogenesis in a murine model of induced corneal neovascularisation. If long term gene delivery to the corneal epithelium is to be achieved it must be targeted to the limbal epithelial stem cells (LESCs) responsible for the continuous regeneration of the layer. This study has convincingly demonstrated gene delivery to these cells in vivo for the first time, with the methodology developed leading to a lasting transgene expression throughout the LESC daughter cell lineages that comprise the epithelium. In addition to potential application in the treatment of congenital epithelial dystrophies this technique may also provide new insights into LESC biology and the cellular dynamics of epithelial renewal
Regeneration of ocular tissues using gene transfer
No full textGene therapy of the eye has made huge advances in recent years, which led to first clinical trials. While these were aimed at replacing a defective gene in inherited disease, research is now expanding to using augmentation gene therapy where a gene is used to modulate the course of disease. We investigated the possibilities of gene transfer of cell cycle modulating genes to induce proliferation in two amitotic tissues essential for vision, the corneal endothelium and retinal pigment epithelium. Corneal endothelial cells (CEC) maintain the water content of the cornea and thereby its clarity. Low CEC density in corneal diseases causes blindness and requires corneal transplantation. Transfer of E2F2, a transcription factor regulating G1 to S phase progression, increases CEC density in human ex vivo cultivated corneas, but only when transferred by adenoviral vector, not lentiviral vector. Instead, lentiviral overexpression of ZONAB, a transcription factor normally inactivated by tight junction protein ZO-1, increased CEC density. Lentiviral downregulation of ZO-1, mimicking loss of cell-cell contacts and loss of contact inhibition, led to CEC proliferation. However, CEC density increase was only achieved in young corneas up to ~60 years-of-age, indicating loss of proliferative capacity with age. RPE loss, as seen in age related macular degeneration (AMD), causes photoreceptor loss and blindness. RPE proliferation could be induced using non-integrating lentiviral vectors delivering E2F2. We showed this in vitro and in vivo after subretinal injection of vector in normal RPE of wildtype mice. To a certain extent, the proliferative effect could also be seen in a transgenic mouse model with degenerated RPE. This concept of in situ regeneration by induction of proliferation could lead to new strategies for CEC loss, especially in donor corneas stored in eye banks. For the RPE, it could be used for treatment of early stages of AMD
Longitudinal Changes to Tight Junction Expression and Endothelial Cell Integrity in a Mouse Model of Sterile Corneal Inflammation
No full textPURPOSE: We previously reported that applying toll-like receptor (TLR) ligands to an injured cornea induces corneal edema at 24 hours, which subsides by 1 week. We tested the hypotheses that endothelial expression of the tight-junction protein, zonula occludens-1 (ZO-1), would be altered during experimental sterile corneal inflammation and that endothelial cell density (ECD) would remain unaffected.
METHODS: Anesthetized C57BL/6J mice received central 1-mm corneal abrasions followed by topical application of saline or cytosine-phosphate-guanosine oligodeoxynucleotide (CpG-ODN, TLR-9 agonist). At 24 hours, 1 week and 4 weeks post treatment, spectral-domain optical coherence tomography images were captured. Eyes were enucleated and processed for zonula occludens-1 (ZO-1) immunofluorescent staining. Corneal flatmounts were analyzed for endothelial ZO-1 expression, cell density, polymegethism, and polymorphism. Corneal stromal inflammatory cell infiltration was evaluated at 4 weeks by immunostaining for CD45.
RESULTS: Central corneal thickness (CCT) was increased in CpG-ODN treated eyes at 24 hours, had normalized by 1 week, but was again thickened by 4 weeks. In eyes with CpG-ODN, endothelial cell ZO-1 expression was reduced at 24 hours but returned to normal levels by 1 week. Endothelial cell density was not altered at 24 hours or 1 week. By 4 weeks, only CpG-ODN eyes showed relatively reduced ECD, as well as large numbers of CD45+ cells in the stroma. Changes to ECD correlated with CCT (r = −0.53, P < 0.01). Compared with naïve controls, more saline- and CpG-ODN–treated eyes exhibited polymegethism.
CONCLUSIONS: This study provides novel insights into the interplay between endothelial cell integrity, corneal edema, and chronic stromal leukocyte activation during sterile corneal inflammation in mice
Arginine depletion as a mechanism for the immune privilege of corneal allografts.
No full textThe cornea is an immune privileged tissue. Since arginase has been found to modulate T-cell function by depleting arginine, we investigated the expression of arginase in the cornea and its possible role in immune privilege using a murine transplant model. We found that both the endothelium and epithelium of murine corneas express functional arginase I, capable of down-regulating T-cell proliferation in an in vitro culture system. The administration of the specific arginase inhibitor N-hydroxy-nor-L-Arg to recipient mice resulted in an accelerated rejection of allogeneic C57BL/6 (B6) corneal grafts. In contrast, in vivo blockade of arginase activity had no effect in altering the course of rejection of primary skin grafts that express little, if any, arginase. In addition, the inhibition of arginase did not alter systemic T-cell proliferation. These data show that arginase is functional in the cornea and contributes to the immune privilege of the eye, and that modulation of arginase contributes to graft survival
Characteristics of endothelial corneal transplant rejection following immunisation with SARS-CoV-2 messenger RNA vaccine.
No full textAIM: We report two cases of endothelial corneal allograft rejection following immunisation with SARS-CoV-2 messenger RNA (mRNA) vaccine BNT162b2 and describe the implications for management of transplant recipients postvaccination for COVID-19. METHODS: A 66-year-old woman with Fuchs endothelial corneal dystrophy (FECD) and a unilateral Descemet's membrane endothelial keratoplasty (DMEK) transplant received COVID-19 mRNA vaccine BNT162b2 14 days post-transplant. Seven days later, she presented with symptoms and signs of endothelial graft rejection. An 83-year-old woman with bilateral DMEK transplants for FECD 3 and 6 years earlier developed simultaneous acute endothelial rejection in both eyes, 3 weeks post second dose of COVID-19 mRNA vaccine BNT162b2. Rejection in both cases was treated successfully with topical corticosteroids. CONCLUSIONS: We believe this is the first report of temporal association between corneal transplant rejection following immunisation against COVID-19 and the first report of DMEK rejection following any immunisation. We hypothesise that the allogeneic response may have been initiated by the host antibody response following vaccination. Clinicians and patients should be aware of the potential of corneal graft rejection associated with vaccine administration and may wish to consider vaccination in advance of planned non-urgent keratoplasties. Patients should be counselled on the symptoms and signs that require urgent review to allow early treatment of any confirmed rejection episode
The first successful full-thickness corneal transplant: a commentary on Eduard Zirm's landmark paper of 1906
No full text
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