Choroidal mast cells in retinal pathology: a potential target for intervention.

Mast cells are important in the initiation of ocular inflammation, but the consequences of mast cell degranulation on ocular pathology remain uncharacterized. We induced mast cell degranulation by local subconjunctival injection of compound 48/80. Initial degranulation of mast cells was observed in the choroid 15 minutes after the injection and increased up to 3 hours after injection. Clinical signs of anterior segment inflammation paralleled mast cell degranulation. With the use of optical coherence tomography, dilation of choroidal vessels and serous retinal detachments (SRDs) were observed and confirmed by histology. Subconjunctival injection of disodium cromoglycate significantly reduced the rate of SRDs, demonstrating the involvement of mast cell degranulation in posterior segment disorders. The infiltration of polymorphonuclear and macrophage cells was associated with increased ocular media concentrations of tumor necrosis factor-α, CXCL1, IL-6, IL-5, chemokine ligand 2, and IL-1ß. Analysis of the amounts of vascular endothelial growth factor and IL-18 showed an opposite evolution of vascular endothelial growth factor compared with IL-18 concentrations, suggesting that they regulate each other's production. These findings suggest that the local degranulation of ocular mast cells provoked acute ocular inflammation, dilation, increased vascular permeability of choroidal vessels, and SRDs. The involvement of mast cells in retinal diseases should be further investigated. The pharmacologic inhibition of mast cell degranulation may be a potential target for intervention.

Anti-vascular endothelial growth factor acts on retinal microglia/macrophage activation in a rat model of ocular inflammation.

PURPOSE: To evaluate whether anti-vascular endothelial growth factor (VEGF) neutralizing antibodies injected in the vitreous of rat eyes influence retinal microglia and macrophage activation. To dissociate the effect of anti-VEGF on microglia and macrophages subsequent to its antiangiogenic effect, we chose a model of acute intraocular inflammation. METHODS: Lewis rats were challenged with systemic lipopolysaccharide (LPS) injection and concomitantly received 5 µl of rat anti-VEGF-neutralizing antibody (1.5 mg/ml) in the vitreous. Rat immunoglobulin G (IgG) isotype was used as the control. The effect of anti-VEGF was evaluated at 24 and 48 h clinically (uveitis scores), biologically (cytokine multiplex analysis in ocular media), and histologically (inflammatory cell counts on eye sections). Microglia and macrophages were immunodetected with ionized calcium-binding adaptor molecule 1 (IBA1) staining and counted based on their differential shapes (round amoeboid or ramified dendritiform) on sections and flatmounted retinas using confocal imaging and automatic quantification. Activation of microglia was also evaluated with inducible nitric oxide synthase (iNOS) and IBA1 coimmunostaining. Coimmunolocalization of VEGF receptor 1 and 2 (VEGF-R1 and R2) with IBA1 was performed on eye sections with or without anti-VEGF treatment. RESULTS: Neutralizing rat anti-VEGF antibodies significantly decreased ocular VEGF levels but did not decrease the endotoxin-induced uveitis (EIU) clinical score or the number of infiltrating cells and cytokines in ocular media (interleukin [IL]-1ß, IL-6, tumor necrosis factor [TNF]-α, and monocyte chemoattractant protein [MCP]-1). Eyes treated with anti-VEGF showed a significantly decreased number of activated microglia and macrophages in the retina and the choroid and decreased iNOS-positive microglia. IBA1-positive cells expressed VEGF-R1 and R2 in the inflamed retina. CONCLUSIONS: Microglia and macrophages expressed VEGF receptors, and intravitreous anti-VEGF influenced the microglia and macrophage activation state. Taking into account that anti-VEGF drugs are repeatedly injected in the vitreous of patients with retinal diseases, part of their effects could result from unsuspected modulation of the microglia activation state. This should be further studied in other ocular pathogenic conditions and human pathology.

Microglia/macrophages migrate through retinal epithelium barrier by a transcellular route in diabetic retinopathy: role of PKCζ in the Goto Kakizaki rat model.

Diabetic retinopathy is associated with ocular inflammation, leading to retinal barrier breakdown, macular edema, and visual cell loss. We investigated the molecular mechanisms involved in microglia/macrophages trafficking in the retina and the role of protein kinase Cζ (PKCζ) in this process. Goto Kakizaki (GK) rats, a model for spontaneous type 2 diabetes were studied until 12 months of hyperglycemia. Up to 5 months, sparse microglia/macrophages were detected in the subretinal space, together with numerous pores in retinal pigment epithelial (RPE) cells, allowing inflammatory cell traffic between the retina and choroid. Intercellular adhesion molecule-1 (ICAM-1), caveolin-1 (CAV-1), and PKCζ were identified at the pore border. At 12 months of hyperglycemia, the significant reduction of pores density in RPE cell layer was associated with microglia/macrophages accumulation in the subretinal space together with vacuolization of RPE cells and disorganization of photoreceptors outer segments. The intraocular injection of a PKCζ inhibitor at 12 months reduced iNOS expression in microglia/macrophages and inhibited their migration through the retina, preventing their subretinal accumulation. We show here that a physiological transcellular pathway takes place through RPE cells and contributes to microglia/macrophages retinal trafficking. Chronic hyperglycemia causes alteration of this pathway and subsequent subretinal accumulation of activated microglia/macrophages.

Anti-retinal autoantibodies in experimental ocular and systemic toxoplasmosis.

BACKGROUND: Patients with ocular toxoplasmosis (OT) develop autoreactivity to several retinal antigens, including retinal S-antigen. By establishing an experimental rabbit model of systemic and of primary and secondary ocular toxoplasmosis, we wished to investigate the onset and development of humoral response to retinal S-antigen. METHODS: Of twelve infection-naïve rabbits, six were left untreated, and the other six were infected subcutaneously with 5,000 tachyzoites of the highly virulent, non-cyst-forming BK-strain of Toxoplasma gondii. Three months later, the left eye of each animal was infected transvitreally with 5,000 tachyzoites of the same strain. The right eye of each rabbit served as an uninfected control. Blood and aqueous humor were collected prior to infection, and up to 90 days thereafter. Using the ELISA technique, all samples were analyzed in parallel for total IgG, and antibodies against toxoplasmic, bovine retinal S-antigen and peptide 35 from human S-antigen. RESULTS: In infection-naïve rabbits Toxoplasma-specific antibodies were detected 10 to 15 days after systemic and ocular infection. Serum antibodies against retinal S-antigen and peptide 35 were not detected in response to systemic Toxoplasma infection. After ocular challenge, aqueous-humour levels of antibodies against retinal S-antigen and peptide 35 in the infected eye began to rise 10 to 15 days later in infection-naïve, but not in infection-immunized animals. During the early post-infection period, the concentrations of anti-retinal antibodies in the infected eye correlated with the severity of inflammatory tissue destruction, but returned to baseline later even though the inflammatory response persisted. In the uninfected partner eye, concentrations of anti-retinal and toxoplasmic antibodies did not correlate with each other. CONCLUSION: Our data afford no evidence of similarities between toxoplasmic and retinal antigens, nor of infection-induced humoral autoimmunity. They indicate rather that retinal autoantigens are liberated in the context of inflammatory tissue destruction due to ocular toxoplasmosis.

[Macular edema: Understand mechanisms to develop treatments]. / Les œdèmes maculaires - Mieux comprendre leurs mécanismes pour mieux les traiter.

Macular edema is an increase in volume of the central area of the retina, responsible for visual acuity. Visual symptoms handicap the lives of millions of patients with macular edema secondary to chronic and sometimes acute retinal disease. Proteins that neutralize the vascular endothelial growth factor (VEGF) pathway or glucocorticoids, at the cost of repeated intraocular injections over years, limit visual symptoms. A better understanding of why and how edema forms and how therapeutic molecules exert an anti-edematous effect will help prevent this disabling and blinding retinal complication from occurring.

Title: Les œdèmes maculaires - Mieux comprendre leurs mécanismes pour mieux les traiter. Abstract: L'œdème maculaire est une augmentation de volume de la macula, zone centrale de la rétine, responsable de l'acuité visuelle. Des symptômes visuels handicapent la vie de millions de patients atteints d'œdème maculaire secondaire à une maladie chronique et parfois aiguë de la rétine. Les protéines qui neutralisent la voie du facteur de croissance de l'endothélium vasculaire (VEGF) ou les glucocorticoïdes, au prix d'injections intraoculaires répétées pendant des années, limitent les symptômes visuels. Mieux comprendre pourquoi et comment l'œdème se forme et comment les molécules thérapeutiques exercent un effet anti-œdémateux permettra de mieux prévenir la survenue de cette complication rétinienne handicapante et cécitante.

Pathological aspects of spontaneous uveitis and retinopathy in HLA-A29 transgenic mice and in animal models of retinal autoimmunity: relevance to human pathologies.

PURPOSE: A major increased risk of developing birdshot chorioretinopathy is reported in humans who are HLA-A29-positive. To better characterize this disease, an animal model of HLA-A29-associated disease was developed and the pathology arising spontaneously in these transgenic mice was compared to animal models of autoimmune uveoretinitis and to human pathology. MATERIALS AND METHODS: HLA-A2902 cDNA (A29c) was obtained from a patient suffering from birdshot retinochoroidopathy and used for transgene construct to generate HLA-A29 transgenic mice. Histopathological examination of the animal cohort was performed up to 15 months of age. It was compared with the ocular pathology developed in C57BL/6 mice and in Lewis rats immunized with retinal autoantigens. RESULTS: Aging HLA-A29 transgenic mice spontaneously developed an ocular disease with resemblance to experimental retinal-Ag-induced autoimmune ocular disease and to human pathologies shown in birdshot retinochoroidopathy, Vogt-Koyanagi-Harada and sympathetic ophthalmia. Pathogenic mechanisms could possibly be shared by these conditions. CONCLUSION: Humanized models of ocular inflammation developed in HLA class I and class II transgenic mice will help better understand the mechanisms responsible for ocular inflammation. Local control of autoimmunity in HLA-A29-positive individuals would be an important option for new therapeutic strategies.

Primate model of uveoretinitis and vasculitis/experimental autoimmune uveoretinitis induced in cynomolgus monkeys by retinal s antigen.

PURPOSE: We aimed to describe the clinical and angiographic changes in an experimental model of autoimmune uveoretinitis and vasculitis in primates. METHODS: Six cynomolgus monkeys received a single subcutaneous immunization with 100 microg of human S antigen with complete Freund's adjuvant. RESULTS: All the animals had a bilateral long-term disease occurring usually in 1 eye approximately 4 weeks after immunization, the second eye being involved 1-5 weeks later. A cyclic course of the disease could be demonstrated by repeated fundus fluorescein angiograms. The initial and principal manifestation consisted in retinal vascular sheathing affecting veins and venules. The more severe forms showed areas of posterior uveoretinitis, dense vitritis and anterior uveitis. CONCLUSION: A single systemic injection of pure human retinal S antigen could induce a chronic and recurrent ocular disease similar to human retinal vasculitis.

Animal models of intraocular lymphomas.

Primary intraocular lymphoma is a high-grade non-Hodgkin lymphoma whose pathogenesis is still unclear. Few animal models exist in order to study this condition. Although intraocular lymphomas in humans are usually B cell lymphomas, most of these models are T cell lymphomas. Recently, a major step forward has been realized with the development of new models of intraocular B cell lymphoma. New therapeutic tools are being evaluated in these models of B cell lymphoma. We evaluate the contribution of the different animal models available to study intraocular lymphomas, and we discuss the new therapeutic strategies and their various targets in the tumor as well as in the environment, which are currently investigated through the development of these models.

Mechanisms of macular edema: Beyond the surface.

Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.

Downregulation of endotoxin-induced uveitis by intravitreal injection of vasoactive intestinal Peptide encapsulated in liposomes.

PURPOSE: To reestablish the immunosuppressive microenvironment of the eye, disrupted by ocular inflammation during endotoxin-induced uveitis (EIU), by means of intravitreal injection of vasoactive intestinal peptide (VIP) in saline or encapsulated in liposomes, to increase its bioavailability and efficiency. METHODS: EIU was induced in Lewis rats by subcutaneous injection of lipopolysaccharide (LPS). Simultaneously, animals were intravitreally injected with saline, saline/VIP, VIP-loaded liposomes (VIP-Lip), or unloaded liposomes. EIU severity and cellular infiltration were assessed by clinical examination and specific immunostaining. VIP concentration was determined in ocular fluids by ELISA. Ocular expression of inflammatory cytokine and chemokine mRNAs was detected by semiquantitative RT-PCR. Biodistribution of rhodamine-conjugated liposomes (Rh-Lip) was analyzed by immunohistochemistry in eyes and regional cervical lymph nodes (LNs). RESULTS: Twenty-four hours after intravitreal injection of VIP-Lip, VIP concentration in ocular fluids was 15 times higher than after saline/VIP injection. At that time, EIU clinical severity, ocular infiltrating polymorphonuclear leukocytes (PMNs), and, to a lesser extent, ED1(+) macrophages, as well as inflammatory cytokine and chemokine mRNA expression, were significantly reduced in VIP-Lip-injected rats compared with rats injected with saline/VIP, unloaded liposomes, or saline. Rh-Lip was distributed in vitreous, ciliary body, conjunctiva, retina, and sclera. It was internalized by macrophages and PMNs, and VIP colocalized with liposomes at least up to 14 days after injection. In cervical LNs, resident macrophages internalized VIP-Rh-Lip, and some adjacent lymphocytes showed VIP expression. CONCLUSIONS: VIP was efficient at reducing EIU only when formulated in liposomes, which enhanced its immunosuppressive effect and controlled its delivery to all tissues affected by or involved in ocular inflammation.

Impaired th1/tc1 cytokine production of tumor-infiltrating lymphocytes in a model of primary intraocular B-cell lymphoma.

PURPOSE: Primary intraocular lymphoma is a high-grade non-Hodgkin lymphoma with a pathogenesis that is still unclear. Microenvironment is known to be crucial in controlling tumor growth and maintenance. To study the immune microenvironment in intraocular lymphomas and to characterize the cytokine polarization of infiltrating T-lymphocytes, a new murine model of intraocular B-cell lymphoma was developed. METHODS: Immunocompetent adult mice were injected intravitreally with a syngeneic lymphomatous B-cell line. Clinical, histologic, and flow cytometric analyses were performed to characterize the tumoral invasion and the immune infiltration. Cytokine production of ocular cells was investigated by RT-PCR and fluorescent immunoassay, with or without stimulation by anti-CD3(+) anti-CD28 antibodies. RESULTS: Intraocular lymphoma developed in eyes injected by lymphomatous B-cells. At day 19, the retina and the vitreous cavity were infiltrated by tumor cells. Up to 15% of living cells were T-lymphocytes. Cytokine profile analysis of the supernatant of ocular cells cultured ex vivo demonstrated the presence of IL10, IL6, IFNgamma, and TNFalpha. Stimulation of ocular cells with anti-CD3(+) anti-CD28 antibodies increased the IFNgamma level and led to the induction of IL2 production, completing the type 1 (Th1/Tc1-like) pattern of cytokine expression observed. IL12p70 and IL4, potent Th1 or Th2 differentiating factors, were undetectable, even after stimulation. CONCLUSIONS: The results suggest that T-cells from intraocular B-lymphomas are characterized by a Th1/Tc1-like profile that could be partially inhibited in vivo. These data raise the possibility of a T-cell immunostimulation to reactivate the Th1/Tc1-lymphocytes and improve intraocular antitumoral immunity.

Tetracycline-inducible viral interleukin-10 intraocular gene transfer, using adeno-associated virus in experimental autoimmune uveoretinitis.

Members of the adeno-associated virus (AAV) family are good candidates for the treatment of ocular diseases because of their relative lack of pathogenicity. We studied the effect of intraocular injection of AAV2-viral IL-10 (vIL-10) on retinal S-antigen-induced experimental autoimmune uveoretinitis (EAU) in Lewis rats. We demonstrated that AAV2/2-GFP injected into the vitreous body transduced the iris and ciliary body, or anterior uvea, and the retina. We showed that intravitreal injection of the AAV2/2-tetON-vIL-10 construct achieved detectable levels of vIL-10 mRNA and protein within the eye and was effective in protecting the rat retina against destruction. This protection was dependent on the level of vIL-10 present in the aqueous humor/ vitreous body. Intravitreal injection of the same construct encased within an AAV5 shell, AAV2/5-tetONvIL- 10, did not confer any degree of protection. It appeared that the AAV2/5 vectors did not transduce the anterior uvea, the site at which inflammatory cells first localize in EAU, nor the ganglion cell layer; induced low expression of vIL-10 mRNA; and did not achieve detectable levels of transgene expression in the aqueous humor/vitreous body. Local treatment with AAV2/2-tetON-vIL-10 did not dampen the systemic immune response, as determined by S-antigen-specific lymphocyte proliferation. Our results show that local intravitreal injection of AAV2/2 is an effective means by which to deliver immunoregulatory molecules into the eye during uveitis, a chronic human ocular disease.

Cornea graft endothelial cells undergo apoptosis by way of an alternate (caspase-independent) pathway.

PURPOSE: To look for apoptosis pathways involved in corneal endothelial cell death during acute graft rejection and to evaluate the potential role of nitric oxide in this process. MATERIALS AND METHODS: Corneal buttons from Brown-Norway rats were transplanted into Lewis rat corneas. At different time intervals after transplantation, apoptosis was assessed by diamino-2-phenylindol staining and annexin-V binding on flat-mount corneas, and by terminal transferase dUTP nick end labeling (TUNEL), caspase-3 dependent and leukocyte elastase inhibitor (LEI)/LDNase II caspase-independent pathways on sections. Inducible nitric oxide synthase (NOS-II) expression and the presence of nitrotyrosine were assayed by immunohistochemistry. RESULTS: Graft endothelial cells demonstrated nuclear fragmentation and LEI nuclear translocation, annexin-V binding, and membranes bleb formation. Apoptosis associated with caspase-3 activity or TUNEL-positive reaction was not observed at any time either in the graft or in the recipient corneal endothelial cells. During 14 days posttransplantation, the recipient corneal endothelial cells remained unaltered and their number unchanged in all studied corneas. NOS-II was expressed in infiltrating cells present within the graft. This expression was closely associated with the presence of nitrotyrosine in endothelial and infiltrating cells. CONCLUSION: During the time course of corneal graft rejection, graft endothelial cells undergo apoptosis. Apoptosis is caspase 3 independent and TUNEL negative and is, probably, carried out by an alternative pathway driven by an LEI/L-Dnase II. Peroxynitrite formation may be an additional mechanism for cell toxicity and programmed cell death of the graft endothelial cells during the rejection process in this model.

Cytokines in immunotherapy of experimental uveitis.

A better understanding of the basic mechanisms of uveitis and of the role of cytokines in experimental ocular inflammation autoimmune diseases should allow us to define new approaches for therapy. Modulation of the cytokine network by either blocking cytokine activity or administration of regulatory Th2 cytokines has shown its efficacy in several experimental autoimmune diseases including uveitis. However, cytokines present pleiotropic activities and thus may exert different effects depending on the autoimmune diseases, making interventions on their production complex. Anti-cytokine therapy or a combination of anti-cytokine drugs, antibodies, and cytokine gene therapy to synergize the therapeutical effects of other treatments appear to be of interest. Improvements in drug delivery and in biotechnology will also allow us to elaborate new and safe immunomodulatory strategies.

The aldosterone-mineralocorticoid receptor pathway exerts anti-inflammatory effects in endotoxin-induced uveitis.

We have previously shown that the eye is a mineralocorticoid-sensitive organ and we now question the role of mineralocorticoid receptor (MR) in ocular inflammation. The endotoxin-induced uveitis (EIU), a rat model of human intraocular inflammation, was induced by systemic administration of lipopolysaccharide (LPS). Evaluations were made 6 and 24 hours after intraocular injection of aldosterone (simultaneous to LPS injection). Three hours after onset of EIU, the MR and the glucocorticoid metabolizing enzyme 11-beta hydroxysteroid dehydrogenase type 2 (11ß-HSD2) expression were down-regulated in iris/ciliary body and the corticosterone concentration was increased in aqueous humor, altering the normal MR/glucocorticoid receptor (GR) balance. At 24 hours, the GR expression was also decreased. In EIU, aldosterone reduced the intensity of clinical inflammation in a dose-dependent manner. The clinical benefit of aldosterone was abrogated in the presence of the MR antagonist (RU26752) and only partially with the GR antagonist (RU38486). Aldosterone reduced the release of inflammatory mediators (6 and 24 hours: TNF-α, IFN-γ, MIP-1α) in aqueous humor and the number of activated microglia/macrophages. Aldosterone partly prevented the uveitis-induced MR down-regulation. These results suggest that MR expression and activation in iris/ciliary body could protect the ocular structures against damages induced by EIU.

Protective effect of intravitreal administration of tresperimus, an immunosuppressive drug, on experimental autoimmune uveoretinitis.

PURPOSE: To test the efficiency of locally administrated tresperimus in experimental autoimmune uveoretinitis (EAU). METHODS: EAU was induced in Lewis rats by S-antigen (S-Ag) immunization. Three intravitreal injections of tresperimus (prevention or prevention/treatment protocols) were performed at different time points after immunization. The pharmacokinetics of tresperimus was evaluated in the ocular tissues and plasma. The in vitro effect of tresperimus was evaluated on macrophages. EAU was graded clinically and histologically. Blood ocular barrier permeability was evaluated by protein concentration in ocular fluids. Immune response to S-Ag was examined by delayed type hypersensitivity, the expression of inflammatory cytokines in lymph nodes, ocular fluids and serum by multiplex ELISA, and in ocular cells by RT-PCR. RESULTS: In vitro, tresperimus significantly reduced the production of inflammatory cytokines by lipopolysaccharide-stimulated macrophages. In vivo, in the treatment protocol, efficient tresperimus levels were measured in the eye but not in the plasma up to 8 days after the last injection. Tresperimus efficiently reduced inflammation, retinal damage, and blood ocular barrier permeability breakdown. It inhibited nitric oxide synthase-2 and nuclear factor κBp65 expression in ocular macrophages. IL-2 and IL-17 were decreased in ocular media, while IL-18 was increased. By contrast, IL-2 and IL-17 levels were not modified in inguinal lymph nodes draining the immunization site. Moreover, cytokine levels in serum and delayed type hypersensitivity to S-Ag were not different in control and treated rats. In the prevention/treatment protocol, ocular immunosuppressive effects were also observed. CONCLUSIONS: Locally administered tresperimus appears to be a potential immunosuppressive agent in the management of intraocular inflammation.

A peptide inhibitor of c-Jun N-terminal kinase for the treatment of endotoxin-induced uveitis.

PURPOSE: To evaluate the effect of XG-102 (formerly D-JNKI1), a TAT-coupled dextrogyre peptide that selectively inhibits the c-Jun N-terminal kinase, in the treatment of endotoxin-induced uveitis (EIU). METHODS: EIU was induced in Lewis rats by LPS injection. XG-102 was administered at the time of LPS challenge. The ocular biodistribution of XG-102 was evaluated using immunodetection at 24 hours after either 20 microg/kg IV (IV) or 0.2 microg/injection intravitreous (IVT) administrations in healthy or uveitic eyes. The effect of XG-102 on EIU was evaluated using clinical scoring, infiltration cell quantification, inducible nitric oxide synthase (iNOS) expression and immunohistochemistry, and cytokines and chemokines kinetics at 6, 24, and 48 hours using multiplex analysis on ocular media. Control EIU eyes received vehicle injection IV or IVT. The effect of XG-102 on c-Jun phosphorylation in EIU was evaluated by Western blot in eye tissues. RESULTS: After IVT injection, XG-102 was internalized in epithelial cells from iris/ciliary body and retina and in glial and microglial cells in both healthy and uveitic eyes. After IV injection, XG-102 was concentrated primarily in inflammatory cells of uveitic eyes. Using both routes of administration, XG-102 significantly inhibited clinical signs of EIU, intraocular cell infiltration, and iNOS expression together with reduced phosphorylation of c-Jun. The anti-inflammatory effect of XG-102 was mediated by iNOS, IFN-gamma, IL-2, and IL-13. CONCLUSIONS: This is the first evidence that interfering with the JNK pathway can reduce intraocular inflammation. Local administration of XG-102, a clinically evaluated peptide, may have potential for treating uveitis.

Protective effect of intravitreal injection of vasoactive intestinal peptide-loaded liposomes on experimental autoimmune uveoretinitis.

PURPOSE: The aim of this study was to investigate the effect of a single intravitreal (i.v.t.) injection of vasoactive intestinal peptide (VIP) loaded in rhodamine-conjugated liposomes (VIP-Rh-Lip) on experimental autoimmune uveoretinitis (EAU). METHODS: An i.v.t. injection of VIP-Rh-Lip, saline, VIP, or empty-(E)-Rh-Lip was performed simultaneously, either 6 or 12 days after footpad immunization with retinal S-antigen in Lewis rats. Clinical and histologic scores were determined. Immunohistochemistry and cytokine quantification by multiplex enzyme-linked immunosorbent assay were performed in ocular tissues. Systemic immune response was determined at day 20 postimmunization by measuring proliferation and cytokine secretion of cells from inguinal lymph nodes (ILNs) draining the immunization site, specific delayed-type hypersensitivity (DTH), and the serum concentration of cytokines. Ocular and systemic biodistribution of VIP-Rh-Lip was studied in normal and EAU rats by immunofluorescence. RESULTS: The i.v.t. injection of VIP-Rh-Lip performed during the afferent, but not the efferent, phase of the disease reduced clinical EAU and protected against retinal damage. No effect was observed after saline, E-Rh-Lip, or VIP injection. VIP-Rh-Lip and VIP were detected in intraocular macrophages and in lymphoid organs. In VIP-Rh-Lip-treated eyes, macrophages expressed transforming growth factor-beta2, low levels of major histocompatibility complex class II, and nitric oxide synthase-2. T-cells showed activated caspase-3 with the preservation of photoreceptors. Intraocular levels of interleukin (IL)-2, interferon-gamma (IFN-gamma), IL-17, IL-4, GRO/KC, and CCL5 were reduced with increased IL-13. At the systemic level, treatment reduced retinal soluble autoantigen lymphocyte proliferation, decreased IL-2, and increased IL-10 in ILN cells, and diminished specific DTH and serum concentration of IL-12 and IFN-gamma. CONCLUSIONS: An i.v.t. injection of VIP-Rh-Lip, performed during the afferent stage of immune response, reduced EAU pathology through the immunomodulation of intraocular macrophages and deviant stimulation of T-cells in ILN. Thus, the encapsulation of VIP within liposomes appears as an effective strategy to deliver VIP into the eye and is an efficient means of the prevention of EAU severity.

New formulation of vasoactive intestinal peptide using liposomes in hyaluronic acid gel for uveitis.

We evaluated the benefits of a novel formulation of vasoactive intestinal peptide (VIP) based on the incorporation of VIP-loaded rhodamine-conjugated liposomes (VIP-Rh-Lip) within hyaluronic acid (HA) gel (Gel-VIP-Rh-Lip) for the treatment of endotoxin-induced uveitis (EIU) in comparison with VIP-Rh-Lip alone. In vitro release study and rheological analysis showed that interactions between HA chains and liposomes resulted in increased viscosity and reinforced elasticity of the gel. In vivo a single intravitreal injection of Gel-VIP-Rh-Lip was performed in rats 7 days prior to uveitis induction by subcutaneous lipopolysaccharide injection. The maximal ocular inflammation occurs within 16-24 h in controls (VIP-Rh-Lip, unloaded-Rh-Lip). Whereas intraocular injection of VIP-Rh-Lip had no effect on EIU severity compared with controls, Gel-VIP-Rh-Lip reduced significantly the clinical score and number of inflammatory cells infiltrating the eye. The fate of liposomes, VIP and HA in the eyes, regional and inguinal lymph nodes and spleen was analyzed by immunostaining and fluorescence microscopy. Retention of liposomes by HA gel was observed in vitro and in vivo. Inflammation severity seemed to impact on system stability resulting in the delayed release of VIP. Thus, HA gel containing VIP-Rh-Lip is an efficient strategy to obtain a sustained delivery of VIP in ocular and lymph node tissues.