Involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist in LPS-induced rabbit uveitis

Nanophthalmos-Associated MYRF gene mutation facilitates intraocular inflammation in mice

PURPOSE

Patients with nanophthalmos might be prone to developing intraocular inflammation following an acute glaucoma attack. Here, we aimed to investigate the role of MYRF in intraocular inflammation by modeling the mutation in mice.

METHODS

Nanophthalmos frameshift mutation of Myrf was introduced into the mouse genome with the CRISPR-Cas9 system. Signaling pathways in eye tissues were delineated using RNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Intraocular inflammation was induced by a lipopolysaccharide (LPS) intravitreal injection. Dexamethasone (DEX) was administered systemically and locally a week before the LPS injection. The anterior segment clinical scores of the mice were examined 24 h after the LPS injection. Infiltrating inflammatory cells were evaluated with histopathology and immunofluorescence. The mRNA levels of inflammatory cytokines were quantified with reverse transcription-quantitative PCR (RT-qPCR) and the corresponding protein concentrations using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Many inflammation-associated signaling pathways were enriched in Myrf mut/+ mice ocular tissues. Clinical scores of Myrf mut/+ mice were significantly higher than those of Myrf +/+ mice 24 h after LPS administration. Histological examination demonstrated high inflammatory cell infiltration in the anterior and vitreous chambers in Myrf mut/+ mice, with numerous CD45+ and CD11b+ inflammatory cells. Moreover, enhanced expression of inflammatory cytokines MCP-1, TGF-β, and IL-1β in eyes and aqueous humor of Myrf mut/+ mice was detected. Remarkably, pretreating Myrf mut/+ mice with DEX relieved the intraocular inflammation.

CONCLUSION

Nanophthalmos-associated MYRF mutation renders mouse eyes more susceptible to inflammation. Dexamethasone treatment ameliorates the inflammatory response.

Inflammatory cytokines as mediators of retinal endothelial barrier dysfunction in non-infectious uveitis

Characterised by intraocular inflammation, non-infectious uveitis includes a large group of autoimmune and autoinflammatory diseases that either involve the eye alone or have both ocular and systemic manifestations. When non-infectious uveitis involves the posterior segment of the eye, specifically the retina, there is substantial risk of vision loss, often linked to breakdown of the inner blood-retinal barrier. This barrier is formed by non-fenestrated retinal vascular endothelial cells, reinforced by supporting cells that include pericytes, Müller cells and astrocytes. Across the published literature, a group of inflammatory cytokines stand out as prominent mediators of intraocular inflammation, with effects on the retinal endothelium that may contribute to breakdown of the inner blood-retinal barrier, namely tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, IL-17 and chemokine C-C motif ligand (CCL)2. This article reviews the function of each cytokine and discusses the evidence for their involvement in retinal endothelial barrier dysfunction in non-infectious uveitis, including basic laboratory investigations, studies of ocular fluids collected from patients with non-infectious uveitis, and results of clinical treatment trials. The review also outlines gaps in knowledge in this area. Understanding the disease processes at a molecular level can suggest treatment alternatives that are directed against appropriate biological targets to protect the posterior segment of eye and preserve vision in non-infectious uveitis.

Efficacy and Safety Evaluation of Mometasone Furoate in Treating Ocular Inflammation

Mometasone furoate (MF) is a medium-potency synthetic glucocorticosteroid with anti-inflammatory, antipruritic, and vasoconstrictive properties. However, its role in the treatment of ocular inflammation has not yet been explored. This work investigated the anti-inflammatory activity of MF in ocular tissues. First, the in vivo safety of the intravitreal (IVT) injection of MF (80, 160, and 240 µg) was evaluated via clinical examination (including the assessment of intraocular pressure), electroretinography (ERG), and histopathology. Second, MF was tested in an experimental model of bacillus Calmette-Guérin (BCG)-induced uveitis in Wistar rats. Intraocular inflammation was then evaluated via a slit-lamp and fundus examination, ERG, histopathology, and the quantification of pro-inflammatory markers. Intravitreal MF showed no toxicity in all the investigated doses, with 160 µg leading to attenuated disease progression and improvement in clinical, morphological, and functional parameters. There was a significant reduction in the levels of inflammatory markers (myeloperoxidase, interleukins 6 and 1β, CXCL-1, and tumor necrosis factor-alpha) when compared to the levels in untreated animals. Therefore, MF should be further investigated as a promising drug for the treatment of ocular inflammation.

Gene Delivery of a Caspase Activation and Recruitment Domain Improves Retinal Pigment Epithelial Function and Modulates Inflammation in a Mouse Model with Features of Dry Age-Related Macular Degeneration

Purpose: The NLRP3 inflammasome, a cytoplasmic signal transduction complex that regulates inflammation, has been implicated in the pathogenesis of age-related macular degeneration (AMD), the leading cause of visual impairment in industrialized countries. We tested the therapeutic effect of anti-inflammatory gene therapy, delivered preventively, in Liver-X-Receptor alpha knockout (LXRα^-/-) mice, which exhibit features of dry AMD. Methods:LXRα^-/- mice were treated with an adeno-associated virus (AAV) vector that delivers a secretable and cell-penetrating form of the caspase activation and recruitment domain (CARD). A sGFP-FCS-TatCARD-AAV or sGFP-FCS (control) vector was delivered intravitreally to 3-5 month-old, LXRα^-/- mice, who were then aged to 15-18 months (12-13 month treatment). Retinal function and morphology were assessed pre- and post-treatment. Results: TatCARD treated LXRα^-/- mice did not show improvement in rod and cone photoreceptor function, measured by dark adapted a- and b-wave amplitudes, and rod-saturated b-wave amplitudes. We found a sex-dependent, significant therapeutic effect in c-wave amplitudes in the TatCARD treated mice, which exhibited maintenance of amplitudes in comparison to the significant decline recorded in the control treated group, indicating a therapeutic effect mediated in part through retinal pigment epithelial (RPE) cells. Additionally, the retinas of the TatCARD treated mice exhibited a significant decline in the concentration of interleukin-1 beta (IL-1β) concomitant with modulation of several inflammatory cytokines in the retina and RPE-choroid tissues, as measured by ELISA and cytokine array, respectively. Conclusion: Collectively, these results support that anti-inflammatory gene constructs such as AAV-TatCARD may be considered for the treatment of inflammation in AMD and other ocular diseases of the posterior pole in which inflammation may play a role. Furthermore, our findings emphasize the need to carefully consider potential sex-different responses when assessing potential therapies in pre-clinical models.

Efficacy and Safety of Infliximab in HLA-B27-associated Ocular Inflammation Refractory or Intolerant to Conventional Immunomodulatory Therapy

Purpose

To determine the efficacy and safety of infliximab therapy in patients with HLA B-27-associated ocular inflammation resistant or intolerant to conventional immunomodulatory therapy.

Methods

This was a retrospective observational case series. All cases were uveitic patients with positive HLA-B27, confirmed through HLA testing, resistant or intolerant to conventional immunomodulatory therapy. The primary outcome of the study was to identify the efficacy of infliximab determined by the control of inflammation, duration of remission, and the ability to reduce conventional immunomodulatory therapy. The secondary outcome was an improvement of two or more lines of best-corrected visual acuity (BCVA) on the Snellen visual acuity chart.

Results

Twenty-four patients (38 eyes) were included in the study. All patients were followed for 24 months. Twenty-one (87.5%) patients completed 24 months of follow-up. Sixteen (66.7%) patients had active uveitis at the beginning of therapy. One patient out of these active patients had active inflammation at the end of follow-up period. Thirteen (87.5%) out of sixteen active patients were in steroid-free remission. The mean duration of treatment to induce remission was 16.5 months (range 6–24 months). Corticosteroid was stopped in 19 (90.5%) patients by the end of the study. At the end of the study, in patients who achieved remission, 14 (58.3%) patients were in remission on infliximab therapy and 6 (25%) patients were in remission off infliximab therapy. Of the 38 eyes, 8 (21.05%) showed improvement in BCVA (three eyes had successful cataract extraction with intraocular lens implantation during infliximab therapy with no subsequent inflammation), while 26 eyes (68.4%) had stable BCVA over the 24-month study period. The side effects included allergic reaction, fatigue, cellulitis, headache, restlessness, elevation of liver enzymes, and anemia. Two patients (n = 24, 8.3%) experienced severe adverse effects and the treatment was stopped prematurely in these two patients.

Conclusion

Infliximab might induce and maintain the steroid-free remission in HLA-B27-associated ocular inflammation in patients resistant or intolerant to conventional immunomodulatory therapy.

Innate immune response in retinal homeostasis and inflammatory disorders

Innate immune cells such as neutrophils, monocyte-macrophages and microglial cells are pivotal for the health and disease of the retina. For the maintenance of retinal homeostasis, these cells and immunosuppressive molecules in the eye actively regulate the induction and the expression of inflammation in order to prevent excessive activation and subsequent tissue damage. In the disease context, these regulatory mechanisms are modulated genetically and/or by environmental stimuli such as damage-associated molecular patterns (DAMPs), and a chronic innate immune response regulates or contributes to the formation of diverse retinal disorders such as uveitis, retinitis pigmentosa, retinal vascular diseases and retinal fibrosis. Here we summarize the recent knowledge regarding the innate immune response in both ocular immune regulation and inflammatory retinal diseases, and we describe the potential of the innate immune response as a biomarker and therapeutic target.

Systemic administration of an anti-tumor necrosis factor-alpha monoclonal antibody protects against endotoxin-induced uveitis in rats

OBJECTIVE

This study was to evaluate the effect of systemic injection of an anti-tumor necrosis factor alpha (TNF-α) monoclonal antibody (mAb) on endotoxin-induced uveitis (EIU).

MATERIALS AND METHODS

Fifty-six male Wistar rats (6-8 weeks old) were randomly divided into three groups: EIU, anti-TNF-α mAb + EIU, and control. EIU was induced by injecting Escherichia coli O55:B5 lipopolysaccharide (LPS) into the hind footpad of the rats (150 μg/rat). The anti-TNF-α mAb (1 μg/kg) was administrated 30 min before LPS injection through one-time intravenous injection. The onset time and peak time of EIU were recorded. The serum and aqueous humor (AH) TNF-α, interleukin (IL)-6, and IL-10 levels were measured by ELISA at 4, 24, and 72 h post-LPS injection. Clinical manifestations of EIU and eye histopathology were scored.

RESULTS

Compared with the EIU rats, anti-TNF-α mAb + EIU rats showed significantly delayed onset of uveitis (t = 7.41, P< 0.001), lower clinical scores and histopathological grades (t = 3.18/2.22, P< 0.001), reduced levels of TNF-α (F = 15.06/59.43, P< 0.001) and IL-6 (F = 99.63/14.92, P< 0.001), and increased levels of IL-10 (F = 24.94/8.99, P< 0.001) in the serum and AH. AH TNF-α, serum IL-6, and AH IL-6 levels are positively correlated, whereas serum IL-10 levels were negatively correlated with EIU activity.

CONCLUSION

Antagonizing TNF-α by system injection of the anti-TNF-α mAb protects against EIU in rats. Blocking TNF-α signaling could be a useful strategy for managing uveitis.

Gabapentin Attenuates Ocular Inflammation: In vitro and In vivo Studies

To investigate the effects of gabapentin, a structural analog of γ-amino butyric acid (GABA), on the inflammatory response of lipopolysaccharide (LPS)-stimulated rabbit corneal cells (SIRC) and on endotoxin-induced uveitis (EIU) in rabbits. We investigated the LPS-induced expression of several inflammatory mediators, such as TNF-α, IL-1β, cPLA₂, COX-2, and PGE₂ in the SIRC cells with or without gabapentin treatment. Gabapentin treatment significantly (p < 0.05) attenuated cytokines production, cPLA₂ activation, COX-2 expression, and PGE₂ levels in SIRC. EIU was induced by an intraocular injection of 0.1 μg of LPS in albino rabbit eye. After 7 and 24 h from LPS injection clinical signs of ocular inflammation were examined by slit lamp with or without topical treatment of 0.5% gabapentin. Tears, aqueous, cornea, conjunctiva, and iris-ciliary body were collected and inflammatory biomarkers assessed. Topical treatment with gabapentin significantly (p < 0.05) reduced clinical signs and biomarkers of inflammation compared with the LPS group both at 7 and 24 h. In conclusion, the results generated in the present study suggest that ophthalmic formulation based on gabapentin may be useful in the treatment of inflammatory conditions associated to ocular pain such as uveitis, and that clinical studies to evaluate this possibility may be warranted.

Profile of adalimumab and its potential in the treatment of uveitis

Uveitis refers to the presence of intraocular inflammation, and as a strict definition compromises the iris and ciliary body anteriorly and the choroid posteriorly (the uvea). Untreated, uveitis can lead to visual loss or blindness. The etiology of uveitis can include both infectious and noninfectious (usually immune-mediated) causes, the latter of which are often mediated predominantly by Th1 CD4⁺ T-cells that secrete proinflammatory cytokines. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine involved in the pathogenesis of uveitis, which at high concentrations can cause excess inflammation and tissue damage. Adalimumab is a recombinant human IgG1 monoclonal antibody specific for human TNF-α. Historically, corticosteroids and methotrexate were used to treat uveitis; however, newer biologic agents such as adalimumab have revolutionized therapy for noninfectious uveitis. Adalimumab has shown efficacy in treating refractory uveitis in multiple settings, including idiopathic disease, juvenile idiopathic arthritis, sarcoidosis, Behçets disease, and uveitis secondary to spondyloarthropathies, among several other noninfectious uveitis conditions. In this paper, we will review the profile of adalimumab, the role of TNF-α in uveitis, discuss safety data, and summarize key articles evaluating the efficacy of adalimumab in treating uveitis secondary to the most commonly associated autoimmune diseases.

LONG-TERM EFFICACY OF SYSTEMIC INFLIXIMAB IN RECALCITRANT RETINAL VASCULITIS

PURPOSE

To evaluate the efficacy of systemic infliximab for the induction of remission in patients with retinal vasculitis, inadequately responsive to other immunomodulatory therapy, based on fluorescein angiography grading for retinal vasculitis evaluation.

METHODS

We analyzed 60 patients with retinal vasculitis, from the Massachusetts Eye Research and Surgery Institution in Cambridge, MA. Response to therapy was based on analysis of serial fluorescein angiography and fundus photography, including a baseline angiogram before initiation of infliximab.

RESULTS

Sixty patients received infliximab therapy between July 2007 and July 2012 at Massachusetts Eye Research and Surgery Institution for a diagnosis of retinal vasculitis. All had previously showed a poor clinical response to other immunomodulatory regimens, or ceased therapy due to intolerable side effects. The initial dose of infliximab was 5 mg/kg in all patients and remained at this dose for the extent of treatment in 57 (95%) patients. At 6 months, 45 of 51 (88.23%) patients were maintaining remission with therapy, 5 (9.8%) were in partial remission, and 1 patient had failed. At 12 months, 39 of 39 (100%) patients were maintaining remission with therapy.

CONCLUSION

Infliximab is effective for the treatment of recalcitrant noninfectious retinal vasculitis, refractory to conventional immunomodulatory therapy.

Expression profile of IL-1 family cytokines in aqueous humor and sera of patients with HLA-B27 associated anterior uveitis and idiopathic anterior uveitis

The purpose of this study was to evaluate the cytokine expression profile of specific IL-1 family members in the aqueous humor and sera of patients with HLA-B27 associated acute anterior uveitis (AAU) and idiopathic AAU. Following informed consent, a total of 13 patients with HLA-B27 associated AAU, 12 patients with idiopathic AAU and 9 controls were recruited to this study from May 2013 to July 2014. Each individual received a complete ophthalmologic examination. Aqueous humor and sera samples were collected and 11 inflammation-related cytokines of the IL-1 family (IL-1α, IL-1β, IL-1 receptor antagonist [IL-1Ra], IL-18, IL-36 receptor antagonist [IL-36Ra], IL-33, IL-36α, IL-36β, IL-36γ, IL-37, IL-38) were quantitatively measured and analyzed for statistical significance between groups. The degree of inflammation, anterior chamber cell or flare, correlated with expression of IL-1β, IL-1Ra, and IL-18. The highest levels of IL-1β, IL-1Ra, IL-18, and IL-36Ra were seen in the aqueous of patients with HLA-B27 associated AAU and this was statically significant when compared to the controls, but not to idiopathic AAU. Expression of IL-18 was statistically higher in the aqueous of patients with HLA-B27 associated AAU in comparison to either idiopathic AAU or controls, but this may reflect greater inflammation in this patient group. In the sera only IL-1α was statistically higher in the HLA-B27 associated AAU in comparison to the control. Cytokine analysis reveals elevation of multiple IL-1 family members in the aqueous humor of patients with AAU as compared to controls. The specific signature of inflammation may potentially be useful in developing new future therapies for AAU.

Gene therapy with the caspase activation and recruitment domain reduces the ocular inflammatory response

Inflammation is a key component of chronic and acute diseases of the eye. Our goal is to test anti-inflammatory genes delivered by an adeno-associated virus (AAV) vector as potential treatments for retinal inflammation. We developed a secretable and cell penetrating form of the caspase activation and recruitment domain (CARD) from the apoptosis-associated speck-like protein containing a CARD (ASC) gene that binds caspase-1 and inhibits its activation by the inflammasome. The secretion and cell penetration characteristics of this construct were validated in vitro by measuring its effects on inflammasome signaling in a monocyte cell line and in an retinal pigmented epithelium (RPE) cell line. This vector was then packaged as AAV particles and tested in the endotoxin-induced uveitis mouse model. Gene expression was monitored one month after vector injection by fluorescence fundoscopy. Ocular inflammation was then induced by injecting lipopolysaccharide into the vitreous and was followed by enucleation 24 hours later. Eyes injected with the secretable and cell penetrating CARD AAV vector had both a significantly lower concentration of IL-1β as well as a 64% reduction in infiltrating cells detected in histological sections. These results suggest that anti-inflammatory genes such as the CARD could be used to treat recurring inflammatory diseases like uveitis or chronic subacute inflammations of the eye.

Effects of interleukin-1β on vascular reactivity after lipopolysaccharide-induced endotoxic shock in rabbits and its relationship with PKC and Rho kinase

Calcium desensitization plays a critical role in the occurrence of vascular hyporeactivity after shock. Interleukin (IL)-1β participates in the regulation of vascular reactivity via both nitric oxide (NO)-dependent and NO-independent mechanisms. However, the specific NO-independent pathway remains to be established. The issue of whether IL-1β modulates vascular reactivity via regulation of calcium sensitivity in the NO-independent mechanism is unclear. In the current study, effects of IL-1β on vascular calcium sensitivity and its relationship with PKC and Rho kinase were investigated in vivo and in vitro using a rabbit model of lipopolysaccharide (LPS)-induced endotoxic shock and superior mesenteric arteries (SMAs), respectively. The calcium sensitivity profile of SMAs displayed a biphasic change after LPS-induced endotoxic shock (significant increase at 0.5 hour and 1 hour after LPS administration and marked decrease after 2 hours) and was negatively related to changes in serum IL-1β. The IL-1 receptor antagonist, IL-1ra (4 μg/mL), partly reversed LPS-induced calcium desensitization. In vitro incubation with IL-1β (50-200 ng/mL) reduced the calcium sensitivity of SMAs and suppressed the activities of Rho kinase and PKC and the phosphorylation of 20-kDa myosin light chain. These effects of IL-1β were shown to be regulated by the PKC agonist, phorbol 12-myristate 13-acetate, and Rho kinase agonist and antagonist, angiotensin II, and Y-27632, respectively. Our results collectively suggest that IL-1β participates in vascular hyporeactivity after endotoxic shock via regulation of vascular calcium sensitivity. Moreover, this regulatory effect of IL-1β seems closely related to downregulation of the activities of PKC and Rho kinase.

Biologic agents in experimental autoimmune uveitis

Experimental uveitis models were developed in an effort to elucidate the pathogenesis of human uveitis. The therapeutic effects of numerous anti-inflammatory agents including corticosteroids and immunomodulatory agents including biologic response modifiers have been investigated in both experimental and human uveitis. Monoclonal antibodies to tumor necrosis factor alpha and anti-interleukins, among others, demonstrate efficacy and are employed in the treatment of uveitis refractory to conventional immunomodulatory agents.

Effects of proinflammatory cytokines on the claudin-19 rich tight junctions of human retinal pigment epithelium

PURPOSE

Chronic, subclinical inflammation contributes to the pathogenesis of several ocular diseases, including age-related macular degeneration. Proinflammatory cytokines affect tight junctions in epithelia that lack claudin-19, but in the retinal pigment epithelium claudin-19 predominates. We examined the effects of cytokines on the tight junctions of human fetal RPE (hfRPE).

METHODS

hfRPE was incubated with interleukin 1-beta (IL-1β), interferon-gamma (IFNγ), or tumor necrosis factor-alpha (TNFα), alone or in combination. Permeability and selectivity of the tight junctions were assessed using nonionic tracers and electrophysiology. Claudins, occludin, and ZO-1 were examined using PCR, immunoblotting, and confocal immunofluorescence microscopy.

RESULTS

Only TNFα consistently reduced transepithelial electrical resistance (TER) >80%. A serum-free medium revealed two effects of TNFα: (1) decreased TER was observed only when TNFα was added to the apical side of the monolayer, and (2) expression of TNFα receptors and inhibitors of apoptosis were induced from either side of the monolayer. In untreated cultures, tight junctions were slightly cation selective, and this was affected minimally by TNFα. The results were unexplained by effects on claudin-2, claudin-3, claudin-19, occludin, and ZO-1, but changes in the morphology of the junctions and actin cytoskeleton may have a role.

CONCLUSIONS

Claudin-19-rich tight junctions have low permeability for ionic and nonionic solutes, and are slightly cation-selective. Claudin-19 is not a direct target of TNFα. TNFα may protect RPE from apoptosis, but makes the monolayer leaky when it is presented to the apical side of the monolayer. Unlike other epithelia, IFNγ failed to augment the effect of TNFα on tight junctions.

Antioxidant properties of lutein contribute to the protection against lipopolysaccharide-induced uveitis in mice

BACKGROUND

Lutein is an important eye-protective nutrient. This study investigates the protective effects and mechanisms of lutein on lipopolysaccharides (LPS)-induced uveitis in mice.

METHODS

Lutein, suspended in drinking water at a final concentration of 12.5 and 25 mg/mL, was administered to mice at 0.1 mL/10 g body weight for five consecutive days. Control and model group received drinking water only. Uveitis was induced by injecting LPS (100 mg per mouse) into the footpad in the model and lutein groups on day 5 after the last drug administration. Eyes of the mice were collected 24 hours after the LPS injection for the detection of indicators using commercial kits and reverse transcription-polymerase chain reaction.

RESULTS

LPS-induced uveitis was confirmed by significant pathological damage and increased the nitric oxide level in eye tissue of BALB/C mice 24 hours after the footpad injection. The elevated nitric oxide level was significantly reduced by oral administration of lutein (125 and 500 mg/kg/d for five days) before LPS injection. Moreover, lutein decreased the malondialdehyde content, increased the oxygen radical absorbance capacity level, glutathione, the vitamin C contents and total superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. Lutein further increased expressions of copper-zinc SOD, manganese SOD and GPx mRNA. Conclusion The antioxidant properties of lutein contribute to the protection against LPS-induced uveitis, partially through the intervention of inflammation process.

Non-infectious pediatric uveitis: an update on immunomodulatory management

Pediatric non-infectious uveitis remains a rare but potentially sight-threatening group of diseases. However, early screening and treatment can improve outcomes. No single agent has proven to be efficacious in all cases. A wide variety of long-term immunomodulatory treatments are available; these agents differ in both their potency and side effect profiles. Corticosteroids remain an extremely valuable form of treatment in the short-term management of uveitis. Other major groups of immunomodulatory treatments include the calcineurin inhibitors and antimetabolites such as methotrexate, which is frequently used as the first-line agent. The biologics, including anti-tumor necrosis factor agents and interferons, are newer and potentially very useful therapies although side effects limit their use. Successful outcomes may be achieved with appropriate immunosuppressant therapy given early in the disease, although clinical trials are required to define the true efficacy of this strategy.

Etanercept (Enbrel)-Associated Inflammatory Eye Disease: Case Report and Review of the Literature

PURPOSE

To report a case of severe anterior uveitis flare following the administration of etanercept (Enbrel) for ankylosing spondylitis and to review the literature pertaining to inflammatory eye disease associated with the use of etanercept.

METHODS

Clinical data were collected from a 52-year-old female with chronic symptomatic ankylosing spondylitis. The relationship between etanercept administration and the patient's systemic and ocular inflammation was assessed. A review of the literature was conducted to identify additional reports.

RESULTS

A patient with a history of ankylosing spondylitis exhibited acute exacerbations of uveitis that were temporally related to etanercept injections. Re-challenge was associated temporally with a worsening of symptoms, and drug withdrawal, in concert with aggressive systemic steroid treatment, resulted in rapid resolution. Seventeen cases of inflammatory eye disease (uveitis, scleritis, orbital myositis) believed to be associated with etanercept therapy were found in the recent literature.

CONCLUSIONS

Ocular inflammation is paradoxically a potential adverse event following the use of etanercept in both previously uninvolved and inflamed eyes. Careful surveillance of patients on etanercept is warranted to assure that flares in ocular inflammation are not secondary to etanercept therapy.

NAD(P)H oxidase-dependent regulation of CCL2 production during retinal inflammation

PURPOSE

CCL2 plays an important role in vascular inflammation by inducing leukocyte recruitment and activation. The authors had previously found that the blockade of NAD(P)H oxidase in turn blocks leukocyte adhesion to retinal vessels during diabetes and uveitis. In this study, the role of NAD(P)H oxidase in CCL2 production was assessed.

METHODS

Studies were performed in three mouse models with lipopolysaccharide (LPS)-induced uveitis, ischemic retinopathy, and streptozotocin diabetes and in cytokine- and LPS-treated cells. CCL2 mRNA and protein expression were measured by quantitative PCR and ELISA. NF-kappaB activity was detected by reporter gene assay. Kinase phosphorylation was determined by immunoblotting.

RESULTS

Expression of CCL2 was increased in the retinas of all three mouse models. The effect was strongest in the LPS-treated mice, with a peak mRNA increase at 3 hours. This increase was abrogated by administration of the NAD(P)H oxidase inhibitor apocynin. Apocynin also blocked CCL2 production in endothelial cells (ECs), retinal microglia, and Müller cells stimulated with TNF-alpha, VEGF, or LPS. Studies using human ECs demonstrated that TNF-alpha-induced CCL2 production was also inhibited by the NAD(P)H oxidase inhibitor DPI, the antioxidant N-acetyl-L-cysteine, or the superoxide scavenger Tiron, further indicating that inhibition occurs through the NAD(P)H/ROS pathway. Analysis of downstream signals showed that inhibition of NAD(P)H oxidase partially inhibited NF-kappaB activation but did not reduce CCL2 mRNA stability or prevent TNF-alpha-induced phosphorylation of p38MAPK. However, TNF-alpha-induced Akt phosphorylation was blocked, and inhibiting Akt dramatically decreased CCL2 production.

CONCLUSIONS

NAD(P)H oxidase activity is required for CCL2 production during retinal vascular inflammation. Akt and NF-kappaB are involved in this signaling pathway.

Activation of NOD2 in vivo induces IL-1beta production in the eye via caspase-1 but results in ocular inflammation independently of IL-1 signaling

Nucleotide-binding and oligomerization domain 2 (NOD2) belongs to the emerging Nod-like receptor (NLR) family considered important in innate immunity. Mutations in NOD2 cause Blau syndrome, an inherited inflammation of eye, joints, and skin. Mutations in a homologous region of another NLR member, NALP3, cause autoinflammation, wherein IL-1beta plays a critical role. Here, we tested the hypothesis that IL-1beta is a downstream mediator of NOD2-dependent ocular inflammation. We used a mouse model of NOD2-dependent ocular inflammation induced by muramyl dipeptide (MDP), the minimal bacterial motif sensed by NOD2. We report that MDP-induced ocular inflammation generates IL-1beta and IL-18 within the eye in a NOD2- and caspase-1-dependent manner. Surprisingly, two critical measures of ocular inflammation, leukocyte rolling and leukocyte intravascular adherence, appear to be completely independent of IL-1 signaling effects, as caspase-1 and IL-1R1-deficient mice still developed ocular inflammation in response to MDP. In contrast to the eye, a diminished neutrophil response was observed in an in vivo model of MDP-induced peritonitis in caspase-1-deficient mice, suggesting that IL-1beta is not essential in NOD2-dependent ocular inflammation, but it is involved, in part, in systemic inflammation triggered by NOD2 activation. This disparity may be influenced by IL-1R antagonist (IL-1Ra), as we observed differential IL-1Ra levels in the eye versus plasma at baseline levels and in response to MDP treatment. This report reveals a new in vivo function of NOD2 within the eye yet importantly, distinguishes NOD2-dependent from NALP3-dependent inflammation, as ocular inflammation in mice occurred independently of IL-1beta.

High-dose infliximab prophylaxis in endotoxin-induced uveitis

PURPOSE

The aim of this study to analyze the preventive effect of high-dose infliximab in endotoxin-induced uveitis (EIU) in rabbits.

METHODS

An experimental study was conducted on 64 rabbits. Salmonella typhimurium lipopolysaccharide endotoxin was intravitreally injected. Infliximab was intravenously (i.v.) injected 24 h before the intravitreal injection (20 mg/kg). The animals were randomly assigned to five groups: group A, saline intravitreal injection; group B, Infliximab i.v. group C, infliximab + saline; group D, intravitreal endotoxin and group E, infliximab i.v. + intravitreal endotoxin. With two masked observers, a microscopic examination of aqueous humor (cells, tumor necrosis factor [TNF] alpha) and aqueous protein level were performed 24 h after an endotoxin injection and 48 h after an infliximab infusion.

RESULTS

Infliximab treatment, at a dose of 20 mg/kg, significantly improved all the parameters. Inflammatory cell infiltration was significantly reduced in the iris, ciliary body, and anterior chamber (U Mann-Whitney test, P = 0.01). Associated with a lower level of TNF-alpha and protein exudate in aqueous humor (U Mann-Whitney test, P = 0.01).

CONCLUSIONS

Infliximab, at a dose of 20 mg/kg, is effective in the prophylaxis of the EIU.

Inhibition of Hsp90 attenuates inflammation in endotoxin-induced uveitis

Heat shock protein (Hsp) 90 inhibitors, such as 17-allylamino-17-demethoxy-geldanamycin (17-AAG), constitute promising novel therapeutic agents. We investigated the anti-inflammatory activity of 17-AAG in endotoxin-induced uveitis (EIU) in rats. After the induction of EIU with a footpad injection of lipopolysaccharide (LPS), female Lewis rats received a single intraperitoneal. (i.p.) injection of 17-AAG or vehicle. Twenty-four hours later, the retinas were extracted and assayed for leukocyte adhesion; blood-retinal barrier breakdown; VEGF, TNF-alpha, IL-1beta, and CD14 protein levels; NF-kappaB and HIF-1alpha activity; hsp90 and 70 levels and expression and phosphorylation of the tight junction proteins ZO-1 and occludin. 17-AAG treatment significantly suppressed the LPS-induced increase in retinal leukocyte adhesion; vascular leakage; NF-kappaB, HIF-1alpha, p38, and PI-3K activity; and VEGF, TNF-alpha, and IL-1beta levels. 17-AAG also suppressed phosphorylation of ZO-1 and occludin by inhibiting their association with p38 and PI-3K. Although 17-AAG treatment did not reduce the LPS-induced increase in total CD14 levels in leukocytes, it significantly decreased membrane CD14 levels. These data suggest that Hsp90 inhibition suppresses several cardinal manifestations of endotoxin-induced uveitis in the rat. 17-AAG has demonstrated a favorable safety profile in clinical trials in cancer patients and represents a promising therapeutic agent for the treatment of inflammatory eye diseases.

Neutrophil accumulation correlates with type IV collagenase/gelatinase activity in endotoxin induced uveitis

BACKGROUND/AIM

Anterior uveitis is a common inflammatory ocular disease characterised by protein accumulation and leucocyte infiltration in the anterior chamber. The aim of this study was to determine the expression of gelatinases in the aqueous humour (AH) and uvea in an animal model of endotoxin induced uveitis (EIU).

METHODS

EIU was established in Lewis rats following an intraperitoneal injection of lipopolysaccharide (LPS). AH and ocular tissue were obtained from control animals and those with EIU over a 1 week time course and the samples analysed immunohistochemically and by gelatin zymography.

RESULTS

Matrix metalloproteinase (MMP) 2 and 9 levels were elevated in rat AH over a 1 week time course. MMP-2 and MMP-9 levels peaked at the time of maximum uveal inflammation, before returning to baseline levels as the inflammation subsided. MMP-9 was detected in the latent and functionally active form. Total protein extracted from inflamed rat uveal tissue displayed no significant gelatinolytic modulation throughout the time course of EIU. Anterior chamber neutrophils and ciliary body epithelial cells were the most abundant source of the gelatinases.

CONCLUSION

This study has revealed a correlation between infiltrating neutrophils and the presence of elevated gelatinases in EIU. The results suggest that these proteolytically active enzymes may be important mediators of the inflammatory response and contribute to matrix remodelling observed in uveitis. Furthermore, the excess production of MMPs may be a mechanism by which leucocytes, such as neutrophils, gain access to uveal tissue and AH. Therapeutic strategies aimed at reducing MMP activity may be of some benefit in the treatment of uveitis.

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.

Immune privilege persists in eyes with extreme inflammation induced by intravitreal LPS

Since immune privilege is believed to exist in the eye in order to suppress sight-destroying inflammation, we wondered whether eyes with intraocular inflammation retain the immune privileged state. Intraocular inflammation was induced by injection of lipopolysaccharide (LPS) into the vitreous cavity of BALB/c mouse eyes, which showed a peak in intensity at approximately 9 h. At this time point, inflamed eyes were examined for their capacity to afford immune privilege to injected allogeneic tumor cells, and to promote anterior chamber-associated immune deviation (ACAID) to antigens injected locally. In addition, aqueous humor (AqH) harvested from inflamed eyes was tested for its ability to suppress T cell activation. Surprisingly, eyes with acute, intense intraocular inflammation allowed allogeneic tumor cells to form progressively growing tumors, and these same eyes promoted ACAID. Moreover, AqH harvested from inflamed eyes strongly inhibited T cell activation. We conclude that the type of extreme, intraocular inflammation evoked by intravitreally injected LPS fails to abolish immune privilege in the eye. These findings are discussed in light of the effects of other types of inflammation on the integrity of ocular immune privilege, and with respect to the capacity of the eye to maintain immune privilege by more than one mechanism.

Corticosteroid-Sparing Effect of Etanercept in Idiopathic Panuveitis Resistant to Immunosuppressive Therapy

Uveitis, an inflammatory eye disease with varying immunopathogenic mechanisms, may be associated with autoimmune disorders, may be secondary to infection, or may be idiopathic. Response to treatment of uveitis is inconsistent. In this report we describe an adult with idiopathic panuveitis who attempted to lower his oral corticosteroid dose from intolerable levels but was unable to do so because of the reappearance of symptoms. His 8-year course was managed with ocular and systemic corticosteroids, methotrexate, and cyclosporine, which allowed only partially successful control of his ocular inflammation. Complete control was not achieved until the addition of etanercept. With this case report we are the first to describe the complete response of idiopathic panuveitis to etanercept. Our success with this patient strongly supports the critical role of tumor necrosis factor in the immunopathogenesis of some cases of idiopathic panuveitis. Furthermore, etanercept offers a relatively nontoxic, safe option in cases of panuveitis that are unresponsive to traditional immunosuppressive therapy.

Nociceptive and inflammatory effects of subcutaneous TNFalpha

Tumor necrosis factor alpha (TNF) is a potent pro-inflammatory cytokine that produces pain and hyperalgesia following injection. Its algesic effects are due to sensitizing actions on nociceptive primary afferents and to the upregulation of other pro-inflammatory and algesic proteins. In anesthetized rats, we investigated the effect of subcutaneously injected TNF on background activity and mechanical sensitivity of C nociceptors of the sural nerve, as well as its effects on cutaneous plasma extravasation. TNF sensitized C nociceptors dose-dependently; the optimal dose (5 ng) lowered threshold in 66.7% of the tested fibers. This sensitization occurred within 30 min and could last for 2 or more hours. Injected TNF had no effect on Abeta mechanoreceptive fibers. In addition, TNF evoked ongoing activity in 14% of C nociceptors and caused significant and dose-related increases in vascular permeability in glabrous skin. Our data suggest that TNF released during disease or after tissue injury participates in the generation of hyperalgesia and inflammation.

CXC chemokine GRO is essential for neutrophil infiltration in LPS-induced uveitis in rabbits

The purpose of this study was to investigate the role and regulation of the CXC chemokine GRO and the interaction between GRO and IL-8 in LPS-induced uveitis in rabbits. Uveitis was induced by intravitreal injection of 100 ng of LPS in rabbits. After the LPS injection, GRO was produced in aqueous humor and peaked at 24 hr. Immunohistochemistry showed that ciliary epithelial cells were responsible for production of GRO. Blocking the activity of GRO by anti-GRO serum reduced LPS-induced aqueous neutrophil counts by 80%, but did not reduce the mononuclear cell counts or protein levels or IL-8 levels. Regulation of GRO production by TNFalpha, IL-1 and IL-8 was studied. Anti-TNFalphamAb alone did not inhibit the 24 hr LPS induced GRO levels, whereas rrIL-1Ra inhibited the GRO production by 58%. The combination of anti-TNFalpha mAb and rrIL-1Ra inhibited 93% of GRO production. Although treatment with anti-IL-8 IgG inhibited the neutrophil infiltration by 66%, treatment with this antibody did not inhibit GRO production. Taken together, our results suggest that GRO is an essential mediator for neutrophil infiltration in LPS-induced uveitis in rabbits. Most of GRO production is mediated by TNFalpha and IL-1. GRO and IL-8 act in concert to mediate neutrophil infiltration.