Plasmacytoid dendritic cells in the eye.

Plasmacytoid dendritic cells (pDCs) are a unique subpopulation of immune cells, distinct from classical dendritic cells. pDCs are generated in the bone marrow and following development, they typically home to secondary lymphoid tissues. While peripheral tissues are generally devoid of pDCs during steady state, few tissues, including the lung, kidney, vagina, and in particular ocular tissues harbor resident pDCs. pDCs were originally appreciated for their potential to produce large quantities of type I interferons in viral immunity. Subsequent studies have now unraveled their pivotal role in mediating immune responses, in particular in the induction of tolerance. In this review, we summarize our current knowledge on pDCs in ocular tissues in both mice and humans, in particular in the cornea, limbus, conjunctiva, choroid, retina, and lacrimal gland. Further, we will review our current understanding on the significance of pDCs in ameliorating inflammatory responses during herpes simplex virus keratitis, sterile inflammation, and corneal transplantation. Moreover, we describe their novel and pivotal neuroprotective role, their key function in preserving corneal angiogenic privilege, as well as their potential application as a cell-based therapy for ocular diseases.

An immune response to the avascular lens following wounding of the cornea involves ciliary zonule fibrils.

The lens and central cornea are avascular. It was assumed that the adult lens had no source of immune cells and that the basement membrane capsule surrounding the lens was a barrier to immune cell migration. Yet, microfibril-associated protein-1 (MAGP1)-rich ciliary zonules that originate from the vasculature-rich ciliary body and extend along the surface of the lens capsule, form a potential conduit for immune cells to the lens. In response to cornea debridement wounding, we find increased expression of MAGP1 throughout the central corneal stroma. The immune cells that populate this typically avascular region after wounding closely associate with this MAGP1-rich matrix. These results suggest that MAGP1-rich microfibrils support immune cell migration post-injury. Using this cornea wound model, we investigated whether there is an immune response to the lens following cornea injury involving the lens-associated MAGP1-rich ciliary zonules. Our results provide the first evidence that following corneal wounding immune cells are activated to travel along zonule fibers that extend anteriorly along the equatorial surface of the lens, from where they migrate across the anterior lens capsule. These results demonstrate that lens-associated ciliary zonules are directly involved in the lens immune response and suggest the ciliary body as a source of immune cells to the avascular lens.

Blood Vessels and Lymphatic Vessels in the Cornea and Iris After Penetrating Keratoplasty.

PURPOSE: To detect early growth of blood and lymphatic vessels in the mouse cornea and iris after penetrating keratoplasty. METHODS: Penetrating keratoplasty was performed with C57BL/6 mice as donors and BALB/c mice as recipients. Graft transparency and neovascularization were examined by slit-lamp microscopy. Whole mounts of the cornea and iris were processed for detection of the outgrowth of blood and lymph vessels. RESULTS: On day 3 after surgery, all corneal grafts were slightly edematous, and blood vessels in the corneoscleral limbus dilated. LYVE-1 lymphatic vessels and CD31 blood vessels were distributed in the peripheral cornea. In the iris, the density of blood vessels increased, and LYVE-1 cells nearly vanished. On day 7, the grafts became opaque, and blood vessels grew into the recipient bed. A great quantity of lymph vessels invaded the cornea. LYVE-1 arborescent cells were found around the lymphatic vessels. In the iris, blood vessels became bulky and stiff, and arborescent LYVE-1 cells increased in number. On day 14, corneal neovascular regression and graft clarity were found. Lymphatic vessels regressed more slowly than blood vessels in the cornea. In the iris, blood vessels remained coarse. Increasing arborescent LYVE-1 cells were also noted in the ciliary body. CONCLUSIONS: Our findings suggest that the iris-ciliary body could amplify immune signals and in part promote initiation of immune rejection after keratoplasty by providing a pathway for macrophages, which might participate in corneal lymphangiogenesis.

[HLA-B27 Positive Acute Anterior Uveitis - A Translational Perspective]. / HLA-B27-positive akute anteriore Uveitis ­ eine translationale Perspektive.

Background HLA-B27 positive acute anterior uveitis is the most common type of uveitis, and it is an autoimmune disease that can be triggered by infections. The precise mechanism of the interaction between involved microbes (mostly gram negative bacteria) and the host immune system is not clear. The disease probably results from an imbalance between pro- and anti-inflammatory components. Project description This article gives a compact overview about the current knowledge of the clinic and the etiopathogenesis of acute anterior uveitis as a basis for future research approaches. The goal of the current research is to classify the cellular and molecular pathogenetic factors in acute anterior uveitis. In this regard, a project on uveitis within the clinical research unit FOR 2240 "(Lymph)Angiogenesis and Cellular Immunity in Inflammatory Diseases of the Eye", examines the hypothesis that dysregulation of regulatory cell populations and anti-inflammatory cytokines, such as interleukin-10 (IL-10), might contribute to the development of ocular autoimmunity following infections. The goal is to establish new markers for individual susceptibility in the risk group of the HLA-B27 positive population, because only about 1% of the HLA-B27 positive population will eventually develop acute anterior uveitis. Conclusions Translational research approaches to identify predisposed risk groups from the HLA-B27 population could improve patient care both on a prophylactic and a therapeutic level.

Immunological Characterization of Intraocular Lymphoid Follicles in a Spontaneous Recurrent Uveitis Model.

PURPOSE: Recently, formation of tertiary lymphoid structures was demonstrated and further characterized in the R161H mouse model of spontaneous autoimmune uveitis. In the horse model of spontaneous recurrent uveitis, intraocular lymphoid follicle formation is highly characteristic, and found in all stages and scores of disease, but in depth analyses of immunologic features of these structures are lacking to date. METHODS: Paraffin-embedded eye sections of cases with equine spontaneous recurrent uveitis (ERU) were characterized with immunohistochemistry to gain insight into the distribution, localization, and signaling of immune cells in intraocular tertiary lymphoid tissues. RESULTS: Ectopic lymphoid tissues were located preferentially in the iris, ciliary body, and retina at the ora serrata of horses with naturally-occurring ERU. The majority of cells in the tertiary lymphoid follicles were T cells with a scattered distribution of B cells and PNA+ cells interspersed. A fraction of T cells was additionally positive for memory cell marker CD45RO. Almost all cells coexpressed CD166, a molecule associated with activation and transmigration of T cells into inflamed tissues. Several transcription factors that govern immune cell responses were detectable in the tertiary lymphoid follicles, among them Zap70, TFIIB, GATA3, and IRF4. A high expression of the phosphorylated signal transducers and activators of transcription (STAT) proteins 1 and 5 were found at the margin of the structures. CONCLUSIONS: Cellular composition and structural organization of these inflammation-associated tertiary lymphoid tissue structures and the expression of markers of matured T and B cells point to highly organized adaptive immune responses in these follicles in spontaneous recurrent uveitis.

Interleukin-23-Dependent γ/δ T Cells Produce Interleukin-17 and Accumulate in the Enthesis, Aortic Valve, and Ciliary Body in Mice.

OBJECTIVE: The spondyloarthritides (SpA) are a group of rheumatic diseases characterized by ossification and inflammation of entheseal tissue, the region where tendon attaches to bone. Interleukin-23 (IL-23) is involved in the pathogenesis of SpA by acting on IL-23 receptor (IL-23R) expressed on enthesis-resident lymphocytes. Upon IL-23 binding, CD3+CD4-CD8- tissue-resident lymphocytes secrete IL-17A and IL-22, leading to inflammation, bone loss, and ossification. Knowledge about enthesis-resident lymphocytes remains fragmentary, and the contribution of entheseal γ/δ T cells in particular is not clear. This study was undertaken to investigate the presence of γ/δ T cells in the enthesis. METHODS: We used 2-photon microscopy and flow cytometry to analyze entheseal lymphocytes from C57BL/6, Tcrd-H2BeGFP, Rorc-GFP, and IL-23R-eGFP mice. To analyze entheseal γ/δ T cells in IL-23-induced inflammation, Tcrd-H2BeGFP mice were crossed with mice of the susceptible B10.RIII background. Hydrodynamic injection of IL-23 minicircle DNA was performed for overexpression of IL-23 and induction of inflammation. Light-sheet fluorescence microscopy was used to visualize arthritic inflammation. RESULTS: Activated Vγ6+CD27- γ/δ T cells were abundant in uninflamed entheseal tissue and constituted the large majority of retinoic acid receptor-related orphan nuclear receptor γt (RORγt)+IL-23R+ enthesis-resident lymphocytes. Fetal thymus-dependent γ/δ T cells were the main source of IL-17A at the enthesis. Under inflammatory conditions, γ/δ T cells increased in number at the Achilles tendon enthesis, aortic root, and adjacent to the ciliary body. CONCLUSION: Entheseal γ/δ T cells are derived from fetal thymus and are maintained as self-renewing tissue-resident cells. As main IL-17A producers within tissues exposed to mechanical stress including enthesis, γ/δ T cells are key players in the pathogenesis of IL-23-induced local inflammation.

Expression of MicroRNAs in the Eyes of Lewis Rats with Experimental Autoimmune Anterior Uveitis.

Purpose. This study aimed to determine the dynamic changes of NF-κB-related microRNAs (miRNAs) and cytokines over the course of experimental autoimmune anterior uveitis (EAAU) and elucidate the possible immunopathogenesis. Materials and Methods. Uveitis was induced in Lewis rats using bovine melanin-associated antigen. The inflammatory activity of the anterior chamber was clinically scored, and leukocytes in the aqueous humor were quantified. RNA was extracted from the iris/ciliary bodies and popliteal lymph nodes to reveal the dynamic changes of eight target miRNAs (miR-155-5p, miR-146a-5p, miR-182-5p, miR-183-5p, miR-147b, miR-21-5p, miR-9-3p, and miR-223-3p) and six cytokine mRNAs (IFN-γ, IL-17, IL-12A, IL-1ß, IL-6, and IL-10). In situ hybridization of miRNA and enzyme-linked immunosorbent assay quantification of cytokines were performed to confirm the results. Results. Disease activity and leukocyte quantification were maximum at day 15 after immunization. The profiling of miRNA revealed downregulation of miR-146a-5p, miR-155-5p, miR-223-3p, and miR-147b and upregulation of miR-182-5p, miR-183-5p, and miR-9-3p. Cytokine analysis revealed IFN-γ, IL-17, IL-12A, IL-1ß, and IL-6 overexpression, with IL-10 downregulation. Conclusions. Dynamic changes of miRNAs were observed over the course of EAAU. By initiating NF-κB signaling, the expressions of downstream cytokines and effector cells from the Th17 and Th1 lineages were sequentially activated, contributing to the disease.

Human cytokines activate JAK-STAT signaling pathway in porcine ocular tissue.

BACKGROUND: The JAK/STAT (Janus Tyrosine Kinase, Signal Transducers and Activators of Transcription) pathway is associated with cytokine or growth factor receptors and it is critical for growth control, developmental regulation and homeostasis. The use of porcine ocular cells as putative xenotransplants appears theoretically possible. The aim of this study was to investigate the response of various porcine ocular cells in vitro to human cytokines in regard to the activation of JAK-STAT signaling pathways. METHODS: Porcine lens epithelial cells, pigmented iris epithelial cells and pigmented ciliary body cells were used in this study. These cells were isolated from freshly enucleated porcine eyes by enzymatic digestion. Cultured cells between passages 3-8 were used in all experiments. Electromobility shift assay (EMSA), proliferation assay, immunofluorescence staining and flow cytometry were used to evaluate the JAK-STAT signaling pathway in these cells. RESULTS: JAK/STAT signaling pathways could be activated in porcine pigmented epithelial ciliary body cells, in pigmented iris epithelial cells and in lens epithelial cells in response to porcine and human interferons and cytokines. All cells showed very strong STAT1 activation upon stimulation with porcine interferon-gamma. Porcine ocular cells also respond to human cytokines; IFN-alpha induced strong activation of STAT1 in EMSA, flow cytometry and immunofluorescence experiments whereas activation of STAT3 was less strong in EMSA, but strong in flow cytometry and immunofluorescence. Human recombinant IL-6 activated STAT3 and human IL-4 activated STAT6. With the help of immunofluorescence assay and flow cytometry we observed nuclear localization of STAT proteins after activation of porcine ocular cells with cytokines and interferons. Human IFN-α had an inhibitory effect on porcine ocular cells in proliferation assays. CONCLUSION: Our study demonstrated that some types of human cytokines and interferon activate intracellular JAK-STAT signaling pathways in porcine ocular cells. We hypothesize that direct stimulation of the JAK-STAT pathway in porcine cells in response to human cytokines will lead to complications or failure, if pig-to-human ocular tissue xenotransplantation were to be carried out. For successful xenotransplantation among other obstacles there must be new approaches developed to regulate signaling pathways.

Infiltrating macrophages in extratumoural tissues after brachytherapy of uveal melanoma.

PURPOSE: To compare distribution of macrophages in extratumoural ocular tissues in enucleated eyes with irradiated and nonirradiated uveal melanomas to find out how irradiation affects distribution of macrophages so as to gain insight into their potential routes of migration and changes in local inflammatory responses. METHODS: Thirty-four matched pairs of primarily enucleated nonirradiated and secondarily enucleated irradiated eyes with choroidal and ciliary body melanoma were stained with mAb PG-M1, and the extratumoural immunopositive elements were counted under the microscope. Main outcome variables were the number of macrophages in the sclera underlying the tumour, in the choroid adjacent to the tumour, and in the ciliary body. The number of macrophage aggregates in the anterior ipsi- and contralateral episclera adjacent to the limbus was also counted. RESULTS: Macrophages were more numerous within the sclera under the tumour in irradiated eyes when compared to primarily enucleated eyes (median 1514 versus 619/mm², p = 0.0001), and more aggregates of episcleral macrophages adjacent to the limbus were found after irradiation (ipsilateral side, median 132 versus 0, p = 0.0034; contralateral side, median 79 versus 0, p = 0.014). In primarily enucleated eyes, increasing numbers of tumour-infiltrating macrophages were associated with presence of higher numbers of macrophages in the ciliary body (p = 0.003) and the adjacent choroid (p = 0.044), whereas in the irradiated eyes, increasing numbers of tumour-infiltrating macrophages (p = 0.010) and increasing extent of necrosis (p < 0.001) were associated with higher numbers of intrascleral macrophages underlying the tumour. CONCLUSIONS: Resident macrophages are present in extratumoural tissues in eyes with uveal melanoma. Brachytherapy may alter their route of migration and increase the number of macrophages in the sclera and episclera. Histopathologically detectable episcleral aggregates of macrophages adjacent to the limbus are detected predominantly after irradiation, a population of which is clinically visible as episcleral deposits after irradiation.

Investigation of the differential potentials of TLR agonists to elicit uveitis in mice.

TLRs are critical for host defense and innate immunity. Emerging evidence also supports a role for TLRs in many chronic inflammatory diseases, including inflammatory eye disease, known as uveitis. The activation of TLR4 by endotoxin induces a standard model of murine uveitis. How activation of additional TLRs influences the onset and/or severity of anterior uveitis has not been examined. We sought to elucidate the potential of TLRs (TLR1/2, TLR2/6, TLR3, TLR4, TLR5, TLR7/8, and TLR9) to trigger uveitis in mice. Directly stimulated iris/ciliary body explants demonstrated a marked increase in production of inflammatory cytokines TNF-α, IL-6, IP-10/CXCL10, MCP-1, and KC with relatively little production of IFN-γ, IL-10, IL-12p40, IL-12p70, IL-17, IL-1ß, IL-4, or RANTES. The cytokine-response profiles were comparable amongst the TLR agonists, albeit some differences were noted, such as greater IP-10 production following TLR3 activation. Intra-ocular injection of TLR agonists increased leukocyte interactions with the endothelium of the iris vasculature and resulted in chemotaxis into the iris tissue. Assessment of leukocytic responses by ivt videomicroscopy and histology revealed quantitative differences amongst responses to the TLR agonists with respect to the timing and numbers of rolling, adhering, iris-infiltrating, and aqueous humor-infiltrating cells, along with cytokine levels in vivo. Our data demonstrate the eye's responsiveness to a diverse array of microbial products, which activates TLRs, and reveal differences in relative cellular response among the various TLR agonists in vivo.

Ocular immune privilege sites.

The eye is one of the immune privilege sites of the body that is consequently protected from the detrimental and potentially blinding influences of immunologic inflammation. Within the eye, the anterior chamber has been recognized for its immune privilege property for many years now; however, a similar property detectable in the subretinal space has only recently been appreciated. These ocular sites are not only equipped with specialized mechanisms that barricade local inflammatory responses, but also induce systemic regulatory immune response. Numerous studies have characterized molecular and cellular mechanisms involved in conferring both these sites with an immune privilege status. Pigmented epithelial cells lining the anterior chamber in the iris and ciliary body area as well as those in the retina are endowed with immunomodulatory properties that contribute to ocular immune privilege. These cells, via expression of either soluble factors or membrane molecules, inhibit inflammatory T cell activation and promote the generation of regulatory T cells. In the anterior chamber resident antigen-presenting cells, influenced by the various immunosuppressive factors present in the aqueous humor, capture ocular antigens and present them in the spleen to T cells in association with NKT cells and marginal zone B cells. Immunomodulatory microenvironment created by these cells helps generate regulatory T cells, capable of interrupting the induction as well as expression of inflammatory responses. Furthermore, neural regulation of both intraocular and systemic regulatory mechanisms also contributes to ocular immune privilege.

Nrf2 is a critical modulator of the innate immune response in a model of uveitis.

Uveitis is an inflammatory condition that can lead to blindness. It is therefore important to understand the pathophysiology against which to develop targeted therapy. Herein, we tested whether the oxidant-responsive transcription factor Nrf2 is involved in regulating the innate immune response and oxidative damage in the LPS uveitis model. As shown by dihydroethidium staining, intraperitoneally injected LPS increased reactive oxygen species in the retina and iris-ciliary body of Nrf2+/+ and Nrf2-/- mice. After LPS injection, ICAM-1, IL-6, TNF-alpha, COX-2, iNOS, and MCP-1 mRNAs were increased more in the retina and iris-ciliary body of Nrf2-/- than in those of Nrf2+/+ mice. NQO-1 and GCLM, two Nrf2-responsive antioxidant enzymes, had reduced expression in Nrf2+/+ retinas after LPS injection, but no change in expression in Nrf2-/- mice. The number of FITC-Con A-labeled leukocytes adherent to the retinal vascular endothelium increased after LPS treatment in both Nrf2+/+ and Nrf2-/- mice compared to control injections, with more adherent leukocytes in Nrf2-/- than in Nrf2+/+ mice. Pretreatment with the Nrf2 activator 1-(2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl)imidazole increased antioxidant gene expression in the retina, reduced inflammatory mediator expression, and reduced leukocyte adherence to retinal vasculature after LPS treatment in Nrf2+/+ mice, but had no effect on Nrf2-/- mice. Treatment targeting the Nrf2 pathway may be a new therapy for uveitis.

Effects of the immunomodulator, VGX-1027, in endotoxin-induced uveitis in Lewis rats.

BACKGROUND AND PURPOSE: VGX-1027 is a novel, low molecular weight, immunomodulatory compound that has shown efficacy against a variety of immuno-inflammatory disease models in animals including autoimmune diabetes in NOD mice, collagen-induced arthritis and chemically induced inflammatory colitis. Here, we have studied the effects of VGX-1027 on the development of endotoxin-induced uveitis (EIU) in male Lewis rats, as a model of inflammatory ocular diseases in humans. EXPERIMENTAL APPROACH: EIU was induced by a single footpad injection of 200 microg lipopolysaccharide (LPS). Groups of rats were treated with either VGX-1027 (25 mg kg(-1)) or its vehicle at different time points (30 min, 6 h or 12 h) after the challenge with LPS or, as positive control, with dexamethasone. The rats were killed within 16 h after LPS challenge, and the eyes and aqueous humor were collected to study serological, immunological and histological signs of EIU. KEY RESULTS: The rats treated with VGX-1027 within 6 h after LPS challenge exhibited milder clinical, histological and laboratory signs of EIU than those treated with vehicle. CONCLUSION AND IMPLICATIONS: This study provides the first evidence that systemic treatment with VGX-1027 counteracts the uveitis-inducing effect of LPS in rats and suggests that this drug may have potential in the treatment of immuno-inflammatory conditions of the eye in humans.

Immunohistochemical study of chronic nongranulomatous anterior uveitis in juvenile idiopathic arthritis.

PURPOSE: To provide a detailed immunohistochemical analysis of juvenile idiopathic arthritis (JIA)-associated anterior uveitis. DESIGN: Interventional case report. PARTICIPANT: One patient. INTERVENTION: A 12-year-old patient had recurrent pauciarticular JIA and smoldering anterior uveitis in the right eye. Despite treatment with local and systemic corticosteroids and an anti-tumor necrosis factor agent, the right eye became hypotonous and painful and eventually was enucleated. The clinical history and histopathologic and immunohistochemical analyses of the enucleated globe were reviewed. MAIN OUTCOME MEASURES: Histopathologic and immunohistochemical features of JIA-associated anterior uveitis. RESULTS: The iris and ciliary body showed nongranulomatous chronic inflammation predominantly made up of plasma cells, Russell bodies, and plasmacytoid lymphocytes. The ciliary processes and pars plana ciliaris showed focal aggregates of CD20-positive cells with several CD3- and CD8-positive cells and occasional CD4- and CD68-positive cells. Pancytokeratin stain showed ciliary epithelial proliferation admixed with lymphocytes. The iris revealed kappa-positive cells within the stroma and lambda-positive cells on the surface. The iris infiltrate primarily was made up of immunoglobulin (Ig) G-positive cells with occasional IgA- and IgM-positive cells. The anterior chamber exudate was mainly positive for IgG and IgA. CONCLUSIONS: The immunohistochemical findings suggest that JIA-associated nongranulomatous iridocyclitis is a primarily B-cell-infiltrative process.

LruA and LruB antibodies in sera of humans with leptospiral uveitis.

Uveitis can be a serious complication of leptospirosis. Previous studies indicated that the leptospiral lipoproteins LruA and LruB are expressed in the eyes of uveitic horses and that antibodies directed against those proteins show in vitro cross-reactivity with components of equine lens, ciliary body, and/or retina. We now demonstrate that sera from a significant proportion of humans who have leptospiral uveitis also contain antibodies against LruA and LruB. Different categories of nonleptospiral uveitis and autoimmune uveitis were also screened; patients diagnosed with Fuchs uveitis or Behçet's syndrome produced antibodies that cross-reacted with LruA and LruB, suggesting similarities of the autoimmune responses in those diseases with those of leptospiral uveitis.

[Murine ciliary body pigment epithelial cells inhibit activation of T cells].

PURPOSE: Pigment epithelial(PE) cells cultured from the eye possess the novel property of suppressing T cells in vitro. Although cultured iris PE (IPE) and retinal PE (RPE) achieve suppression, the function of ciliary body PE (CBPE) is still unknown. We investigated whether CBPE can suppress the activation of T cells in vitro. METHODS: CBPE, IPE and RPE cells(controls) were established from normal C57BL/6 mice. T-cell activation was assessed by proliferative response and cytokine production, by ELISA. The expression of candidate genes on ocular PE was evaluated with on oligonucleotide microarray, and PE proliferation and PE morphology were also evaluated. RESULTS: CBPE significantly suppressed T cell activation in vitro. Cell division of CBPE was much greater than in other PE, and the cells were confluent from on early phase. Microarray analysis showed that the expression of candidate genes in CBPE is similar to the expression in other PE cells. CONCLUSIONS: CBPE fully suppress T cell activation. Thus, ocular pigment epithelial cells display inhibitory function in the immune privileged site.

Retinal and ciliary body pigment epithelium suppress activation of T lymphocytes via transforming growth factor beta.

The ocular microenvironment is immunosuppressive and anti-inflammatory. Pigment epithelial (PE) cells isolated from the eye possess a new property of suppressing T cell receptor-dependent activation of T cells in vitro. This property depends on their capacity to produce cell-surface and soluble inhibitory molecules. The iris pigment epithelia (IPE) do so through direct cell-to-cell contact with naïve T cells, and this suppressive contact is mediated by interactions between B7 and membrane-bound TGFbeta that are expressed constitutively on IPE. We have now examined whether other ocular PE cells, e.g., retinal pigment epithelia (RPE) and ciliary body pigment epithelia (CBPE), have a similar suppressive property by a similar process. We have found that RPE and CBPE significantly suppress the activation of bystander T cells via soluble inhibitory factors. RPE and CBPE secrete different soluble inhibitory factors including TGFbeta1 and TGFbeta2. Although IPE cells suppress the activation of bystander T cells by membrane-bound TGFbeta, the RPE and CBPE do so by soluble forms of active TGFbeta through mechanisms independent of cell contact. These ocular PE cells are capable modifying T cell function by enhancing production of regulatory cytokines including TGFbeta. We propose that this mechanism of suppression via TGFbeta ensures that soluble active TGFbeta is released into the ocular microenvironment in order to create the immune privilege of the posterior segment of the eye.

Suppressive effects of astaxanthin against rat endotoxin-induced uveitis by inhibiting the NF-kappaB signaling pathway.

We investigated the effects of astaxanthin (AST), a carotenoid, on endotoxin-induced uveitis (EIU), and over the course of the disease measured the expression of inflammatory cytokines and chemokines in the presence or absence of AST. EIU was induced in male Lewis rats by footpad injection of lipopolysaccharide (LPS). The animals were randomly divided to 12 groups with eight animals in each. Immediately after the inoculation, AST (1, 10, or 100 mg kg(-1)) was injected intravenously. Aqueous humour was collected at 6, 12 and 24 hr after LPS inoculation and the number of infiltrating cells in the anterior chamber was counted. In addition, we assayed the concentration of protein, nitric oxide (NO), tumour necrosis factor-alpha (TNF-alpha) and prostaglandin E2 (PGE2). Immunohistochemical staining with a monoclonal antibody against activated NF-kappaB was performed in order to evaluate the effects of AST on NF-kappaB activation. Rats injected with AST showed a significant decrease in the number of infiltrating cells in the anterior chamber and additionally there was a significantly lower concentration of protein, NO, TNF-alpha and PGE2 in the aqueous humour. Moreover, even early stages of EIU were suppressed by injection of AST. The number of activated NF-kappaB-positive cells was lower in iris-ciliary bodies treated with 10 or 100 mg kg(-1) AST at 3 hr after LPS injection. These results suggest that AST reduces ocular inflammation in eyes with EIU by downregulating proinflammatory factors and by inhibiting the NF-kappaB-dependent signaling pathway.

Involvement of inflammation, degradation, and apoptosis in a mouse model of glaucoma.

Glaucoma is a common cause of blindness affecting at least 66 million people worldwide. Pigmentary glaucoma is one of the most common forms of secondary glaucoma, and its pathogenesis remains unclear. Interleukin-18 (IL-18) is an important regulator of innate and acquired immune responses and plays an important role in inflammatory/autoimmunity diseases. Using the DBA/2J mouse as an animal model of human pigmentary glaucoma, we demonstrated for the first time that the expression of the IL-18 protein and gene in the iris/ciliary body and level of IL-18 protein in the aqueous humor of DBA/2J mice are dramatically increased with age. This increase precedes the onset of clinical evidence of pigmentary glaucoma, implying a pathogenic role of inflammation/immunity in this disease. We also observed that activated NF-kappaB and phosphorylated MAPK are increased in the iris/ciliary body of DBA/2J mice, suggesting that both signaling pathways may be involved in IL-18 mediated pathogenesis of pigmentary glaucoma in the eyes of DBA/2J mice. In addition, matrix metalloproteinase-2 (MMP-2) expression in the iris/ciliary body and the activity of MMP-2 in the aqueous humor are increased whereas tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) expression in the iris/ciliary body is decreased, indicating that the degradation process is involved in this mouse model of pigmentary glaucoma. Furthermore, the expressions of apoptosis-related genes, caspase-8, Fas, FADD, FAP, and FAF, and the activity of caspase-3 are increased in the iris/ciliary body of DBA/2J mice. Elucidation of biochemical and molecular mechanisms of IL-18 participation in the pathogenesis of pigmentary glaucoma should provide approaches for developing improved and targeted treatments to ameliorate this blinding disease. The possibility that altered IL-18 expression in the eye of DBA/2J mice initiates and/or amplifies the pathogenesis of pigmentary glaucoma requires further investigation.

Effects of pyrrolidine dithiocarbamate, an NF-kappaB inhibitor, on cytokine expression and ocular inflammation in experimental autoimmune anterior uveitis.

AIMS: The aim of this study was to investigate the effects of pyrrolidine dithiocarbamate (PDTC), a nuclear factor (NF)-kappaB inhibitor, on cytokine expression and suppression of anterior chamber inflammation in experimental autoimmune anterior uveitis. Uveitis was induced in the Lewis rats with the injection of a melanin-associated antigen into the peritoneum and footpad. At defined time points, cytokine mRNA expressions in the iris and ciliary body were measured by using a semiquantitative polymerase chain-reaction method. RESULTS: We found that interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF)-alpha mRNA expression peaked during the active phase of uveitis, whereas interleukin (IL)-10 mRNA increased during the disease resolution. In a separate experiment, PDTC (100 and 200 mg/kg/day) was administrated intraperitoneally daily after immunization. We found that PDTC (100 and 200 mg/kg/day) effectively suppressed ocular inflammation, as indicated by reduced clinical scores and inflammatory cells infiltration in aqueous humor and the iris and ciliary body. CONCLUSIONS: The inhibitory effects of PDTC are mainly resulted from inhibiting the expression of proinflammatory cytokines, TNF-alpha and IFN-gamma but augmenting anti-inflammatory cytokines, IL-10 expression. These findings suggest that the application of NF-kappaB inhibitors may be a potential therapeutic method for the treatment of acute anterior uveitis.