Cachectin: a novel polypeptide induces uveitis in the rabbit eye

Psoriatic Eye Manifestations

The relationship between the eye and psoriasis has been recognized for decades, but the precise eye manifestations in patients with psoriasis and psoriatic arthritis are only recently coming to light. Psoriatic eye findings may include conjunctivitis, dry eye, episcleritis, and uveitis, all of which may precede articular changes. Uveitis, seen in 7% to 25% of psoriatic arthritis patients, may be recognized by the presence of conjunctival injection, photophobia, pain, lid swelling, or otherwise unexplained visual changes. Early recognition is paramount because its natural course may lead to vision loss. Immunopathogenesis has shown evidence for T-helper cell (Th) type 1 (Th1) and Th17 involvement in the pathogenesis of uveitis according to the murine experimental autoimmune uveitis model. Corticosteroids are the primary treatment modality; however, increasing emphasis has been placed on immunomodulators and biologics for more intractable cases. Referral to an ophthalmologist is essential for definitive diagnosis and treatment.

Tumor necrosis factor antagonists: preliminary evidence for an emerging approach in the treatment of ocular inflammation

The anti-tumor necrosis factor (TNF) monoclonal antibody infliximab and the soluble TNF receptor etanercept inhibit the pleiotropic actions of TNF and are widely used for the treatment of rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), spondyloarthropathies (SpA), Crohn's disease, and psoriasis with an acceptable safety profile. A pathogenetic role of TNF in ocular inflammatory conditions has recently emerged from small trials reporting preliminary results on the efficacy of these agents in patients with noninfectious uveitis, regardless of the origin of the disease. The authors review the published experience, derived mostly from investigator-sponsored trials and uncontrolled case series, on the use of TNF antagonists in approximately 280 patients with various ocular conditions who were inadequately controlled on currently available therapy. These reports suggest that TNF antagonists, mainly infliximab, which may have better efficacy than etanercept, are useful in the treatment of ocular inflammation associated with Adamantiades-Behçet's disease, RA, JIA, SpA, Crohn's, sarcoidosis, and Graves' disease ophthalmopathy. Infliximab was also beneficial in small numbers of patients with idiopathic uveitis or scleritis, birdshot retinochoroiditis, uveitic and diabetic cystoid macular edema, and age-related macular degeneration. The currently available data are nonrandomized and thus preliminary, providing the foundation and justification for randomized trials to assess efficacy and safety. Until such results are available, knowledge regarding the use of anti-TNF regimens in ophthalmology is incomplete. However, the preliminary evidence points to a growing optimism for targeting TNF in patients with ocular inflammation.

Favorable response to high-dose infliximab for refractory childhood uveitis

OBJECTIVE

Uveitis in children most commonly is associated with juvenile idiopathic arthritis. In addition to topical glucocorticoids, treatment may include systemic immunosuppressive agents. Tumor necrosis factor alpha (TNF-alpha) has been implicated in the pathogenesis of uveitis; therefore, TNF-alpha blockade seems to be a reasonable therapeutic option to investigate. We report successful treatment of children with uveitis using infliximab.

STUDY DESIGN

A retrospective study of our complete experience using infliximab for the treatment of childhood uveitis was conducted.

PARTICIPANTS

Seventeen children (14 females, 3 males) with chronic uveitis were administered high-dose infliximab (10-20 mg/kg/dose).

MAIN OUTCOME MEASURES

Our main outcome measure was the ability to eliminate all signs of intraocular inflammation.

RESULTS

All 17 patients demonstrated a dramatic, rapid response, with no observed inflammation in 13 patients after the second infusion, and 4 patients requiring 3 to 7 infusions to achieve disease quiescence. Additional immunosuppressives and topical glucocorticoids were tapered when patients achieved no intraocular inflammation.

CONCLUSIONS

In this series, high-dose infliximab was a rapidly effective, well-tolerated therapeutic agent for the treatment of chronic, medically refractory, noninfectious uveitis.

Vitreous intercellular adhesion molecule 1 in uveitis complicated by retinal detachment

AIMS

The vitreous levels of soluble intercellular adhesion molecule 1 (sICAM-1) were investigated in uveitic eyes undergoing vitrectomy for retinal detachment (RD) or other complications, and the presence of this molecule was related to disease activity and vitreous levels of the cytokine tumour necrosis factor alpha (TNF alpha), known to upregulate ICAM-1 expression on various cells.

METHODS

Vitreous and serum samples from 23 patients with either active or quiescent uveitis undergoing retinal surgery were examined for the levels of immunoreactive sICAM-1 and TNF alpha by ELISA methods, and for the presence of biologically active TNF alpha. Vitreous from non-uveitic eyes with rhegmatogenous retinal detachment (RRD), macular holes or cadaveric eyes were used as controls.

RESULTS

As a whole, vitreous from uveitic eyes complicated or uncomplicated by RRD contained significantly higher levels of sICAM-1 than vitreous from non-uveitic eyes with RRD alone (p < 0.0005), eyes with macular holes (p < 0.0001), or normal cadaveric vitreous (p < 0.0001). The proportion of vitreous containing > 20 ng/ml sICAM-1 (> four times the normal values) was significantly higher in eyes with uveitis complicated by RRD than in those eyes without RRD (Fisher's test, p = 0.02), and although levels of sICAM-1 were higher in eyes with active uveitis than in those with quiet disease (p < 0.02), this could not be dissociated from the increase caused by RRD. There was a relation between the vitreous levels of sICAM-1 and those of immunoreactive TNF alpha (Spearman's correlation coefficient; r = 0.601, p = 0.006), but not between the vitreous levels of sICAM-1 and those of biologically active TNF alpha.

CONCLUSION

Increased vitreous sICAM-1 levels and the association of this molecule with the presence of immunoreactive TNF alpha in uveitic eyes confirm the operation of cytokine mediated vascular reactions at the blood-retinal barrier during the development of this condition. The persistence of high vitreous levels of sICAM-1 in eyes with uveitis complicated by RRD despite previous immunosuppression may indicate a low rate of clearance of inflammatory molecules from the vitreous cavity and an exacerbation of the existing inflammatory process by the retinal detachment itself.

IL-12 inhibits endotoxin-induced inflammation in the eye

Interleukin-12 (IL-12) is a heterodimeric cytokine that induces interferon (IFN)-gamma production and an increased generation of Th1 cells. Both IL-12 and IL-12 antagonists are being studied for the treatment of allergic reactions, autoimmune disease and malignancy. The goal of the present experiments was to examine the importance of IL-12 in endotoxin-induced ocular inflammation. The number of inflammatory cells infiltrating eyes with endotoxin-induced uveitis (EIU) was significantly increased in animals treated with intraperitoneal anti-IL-12 antibody when compared to control animals, but there was no difference in infiltrating inflammatory cells in the eyes of animals treated with IL-12 when compared to controls. In contrast, intraocular injection of IL-12 significantly inhibited the development of endotoxin-induced intraocular inflammation. The infiltrating inflammatory cells were reduced in the eyes of animals receiving intraocular IL-12 when compared to controls. Cytokine analysis of the aqueous humor obtained from eyes with EIU showed increased levels of IFN-gamma and decreased levels of IL-6 in eyes receiving intraocular IL-12. These data show that IL-12 has an inhibitory effect on endotoxin-induced inflammation in the eye and suggest that IL-12 can have an immunoregulatory function in some forms of inflammatory disease.

Systemic anti-tumor necrosis factor antibody treatment exacerbates endotoxin-induced uveitis in the rat

Tumor necrosis factor is released in the circulation and aqueous humor during endotoxin-induced uveitis, and induces acute uveitis when injected intraocularly in rats. To elucidate the role of tumor necrosis factor in the development of endotoxin-induced uveitis we analysed the effect of neutralizing anti-tumor necrosis factor antibodies and of pentoxifylline, a drug that inhibits tumor necrosis factor synthesis. Lewis rats were treated with: (a) a single intracardial injection of polyclonal rabbit anti-murine tumor necrosis factor antiserum prior to foot pad injection of 200 micrograms lipopolysaccharide; (b) an intraperitoneal injection of 10 mg pentoxifylline 1 hr before, at the time of, and 3 hr after foot pad injection of lipopolysaccharide; or (c) an intravitreal injection of 20 to 500 micrograms pentoxifylline together with 1 microgram lipopolysaccharide. The ocular inflammation was examined by slit-lamp and evaluated for the presence of hyperemia, flare, miosis, infiltrating cells or hypopyon. Levels of tumor necrosis factor in serum and aqueous samples were determined using a bioassay. Systemic treatment with either anti-tumor necrosis factor antibodies or pentoxifylline resulted in a significant inhibition, 90 and 70% respectively, of serum tumor necrosis factor activity at 3 to 4 hr after lipopolysaccharide injection. Systemic pentoxifylline treatment had no influence on the severity of uveitis. Anti-tumor necrosis factor antibody treatment, in contrast, caused an exacerbation of endotoxin-induced uveitis at t = 20 hr; mean uveitis score 3.9 vs. 1.4 in controls; P < 0.01. Intraocular administration of pentoxifylline together with lipopolysaccharide also had an aggravating effect on uveitis, that was associated with increased levels of intraocular tumor necrosis factor. The results show that inhibition of serum tumor necrosis factor activity does not block the development of endotoxin-induced uveitis. In fact, anti-tumor necrosis factor antibody treatment exacerbates the intraocular inflammation. These findings suggest that tumor necrosis factor may have other than proinflammatory properties in this uveitis model.

Effects of topical FK506 on endotoxin-induced uveitis (EIU) in the Lewis rat

FK506 is a macrolide antibiotic and a potent immunosuppressant. To investigate the effect of topical FK506 on acute ocular inflammation, we evaluated its action on the development of endotoxin-induced uveitis (EIU). At two different concentrations of 0.05% and 0.3%, topical FK506 was applied to Lewis rats with EIU. In aqueous, the mean number of inflammatory cells per microliter +/- SEM was 2,389 +/- 1,277, 1,571 +/- 1,562, 898 +/- 882, and 69 +/- 152 for rats treated with vehicle alone, 0.05%, 0.3% FK506, and 1% prednisolone acetate. The median of histological grades was 2, 1.5, 0.8, and 0.5 for animals treated with these 4 different regimens respectively. Analysis of aqueous protein showed a small reduction in FK506-treated animals. Mean blood levels of FK506 were low in rats treated with topical FK506 (0.05%, 0.84 ng/ml; 0.3%, 2.0 ng/ml) suggesting that its therapeutic effect was not secondary to the systemic absorption of the drug. Although FK506 is not as effective as prednisolone, 0.3% FK506 produced significant decreases in the mean aqueous inflammatory cell number and histological inflammatory score as compared to control vehicle alone. We conclude that topical FK506 can suppress EIU in a dose-dependent fashion and may be an alternative medication for patients with anterior uveitis and contra-indication to topical steroid.

Mediators of the ocular inflammatory response to interleukin-1 beta plus tumor necrosis factor-alpha

BACKGROUND

Intravitreal injection of marginally inflammatory doses of interleukin-1 beta and tumor necrosis factor-alpha (IL-1 beta/TNF alpha) has been shown to produce intraocular inflammation distinctly different from that induced by higher intravitreal doses of either IL-1 or TNF alpha. Since cyclooxygenase inhibitors and platelet-activating factor (PAF)-receptor antagonists can reduce IL-1- or TNF alpha-induced uveitis, the present investigation was undertaken to determine whether cyclooxygenase metabolites of arachidonic acid and PAF are important mediators of IL-1 beta/TNF alpha-induced uveitis.

METHODS

The cyclooxygenase inhibitor indomethacin and two structurally dissimilar PAF-receptor antagonists, SRI 63-441 and WEB 2086, were used to investigate the importance of cyclooxygenase metabolites and PAF in IL-1 beta/TNF alpha-induced uveitis.

RESULTS

Based upon the effectiveness of indomethacin, the anterior uveitis induced by IL-1 beta/TNF alpha could be divided into two phases; a primary phase dependent upon generation of cyclooxygenase metabolites (the first 24 h) and a secondary phase largely independent of cyclooxygenase metabolite production (24-48 h). Posterior uveitis was also apparent at 48 h and was reduced by indomethacin. SRI 63-441 reduced the anterior uveitis at 24 h and to a lesser extent at 48 h; it also reduced the posterior uveitis at 48 h. However, although WEB 2086 was as effective as SRI 63-441 in reducing PAF-induced platelet aggregation, ex vivo, it did not significantly reduce IL-1 beta/TNF alpha-induced uveitis.

CONCLUSIONS

Although the findings do not support an important role for PAF in TNF alpha/IL-1 beta-induced uveitis, it cannot be ruled out that more intensive treatment with a specific and long-acting PAF-receptor antagonist might yield more positive results.

Tumour necrosis factor-induced uveitis in the Lewis rat is associated with intraocular interleukin 6 production

Lewis rats were injected with recombinant murine tumour necrosis factor-alpha either intravitreally (0.08-50 ng) or intracardially (1 microgram). The intraocular inflammatory response induced by tumour necrosis factor was examined by slit-lamp and protein extravasation into aqueous humor was determined. The phenotype of the inflammatory cells in the eye was analysed by immunohistochemistry. In addition, the kinetics of intraocular interleukin 6 production were determined. At 24 hr after intravitreal injection, a significant clinical uveitis was observed only in rats injected with 50 ng of tumour necrosis factor, when compared to saline-treated controls (P < 0.05). Maximal clinical uveitis and blood-aqueous barrier breakdown were already present at 4 hr after tumour necrosis factor injection. The uveitis was characterized by a massive cellular infiltrate in the anterior segment, consisting predominantly of polymorphonuclear cells and macrophages/monocytes, and to a lesser extent of T lymphocytes. Intraocular interleukin 6 mRNA expression and elevated levels of interleukin 6 in aqueous humor were detected 1 hr after tumor necrosis factor injection, reached a maximum at 3 to 4 hr after injection, and had declined again at 2 hr. Although intracardial injection of 1 microgram of tumour necrosis factor in Lewis rats induced a rise of circulating interleukin 6, it did not produce uveitis. The results obtained with intravitreally injected tumour necrosis factor indicate that intraocular TNF may play a pivotal role in the induction of uveitis in the rat. The transient intraocular production of interleukin 6 early during tumour necrosis factor-induced uveitis suggests that this cytokine may participate in the response induced by tumour necrosis factor.

Inflammation induced changes in adenosine 3',5'-cyclic monophosphate production by ciliary epithelial cell bilayers

Despite extensive evidence implicating the cytokines interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF alpha) in the intraocular inflammatory response, little is known about their effects on signal transduction in anterior uveal tissue. Since these cytokines have been shown to alter the adenylyl cyclase system in nonocular tissues, we tested the hypothesis that IL-1 beta and TNF alpha affect the anterior uvea by altering production of the intracellular second messenger adenosine 3',5'-cyclic monophosphate (cAMP) in ciliary epithelial bilayers. This was accomplished by measuring the levels of cAMP in bilayers ex vivo, following intraocular inflammation induced by intravitreal injection of IL-1 beta, TNF alpha or bacterial endotoxin, and in vitro, following exposure to IL-1 beta, TNF alpha or bacterial endotoxin. Although cAMP production was enhanced in bilayers from IL-1 beta-, TNF alpha- or endotoxin-inflamed eyes, ex vivo, exposure of normal bilayers to IL-1 beta (15 U ml-1), TNF alpha (20 U ml-1), or a low concentration of endotoxin (0.01 microgram ml-1) for 4 hr, in vitro, had no effect on cAMP production. The inability of IL-1 beta, TNF alpha, or the low concentration of endotoxin to increase cAMP production by bilayers, in vitro, suggests that the enhanced cAMP production observed with inflamed bilayers, ex vivo, was not due to a direct action of these inflammatory agonists on the ciliary epithelial bilayer. Although direct exposure to cytokines or endotoxin did not change cAMP production, treatment with IL-1 beta, TNF alpha, or a higher concentration of endotoxin (1 microgram ml-1) did affect signal transduction mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intraperitoneal and topic sodium diclofenac on the arachidonic acid metabolism in endotoxin-induced uveitis in the rabbit

Endotoxin-induced uveitis (EIU) was produced in albino rabbits by intravitreal injection in the right eye of 10 ng of salmonella endotoxin in 5 ± l of saline solution by a Hamilton syringe. PGE2 and LTB4 were measured in the aqueous humor by the R.I.A. method 24 hours after endotoxin injection in order to examine the activity of the arachidonic acid metabolism. The authors have used seven groups of 12 animals each. The control group was injected with saline (5 ± l) and the endotoxin group (ET) with 10 ng of endotoxin. One experimental group was injected with the same amount of ET and treated with three intraperitoneal injections (-2h, 0h, 12h) of DFNa (32 mg/kg). Another group (ET+S) was injected with ET and treated with saline intraperitoneally (-2h, 0h, 12h). The topically treated groups received ET and topic DFNa (0.1%) every 6h, 4h and 2h respectively. Mean aqueous PGE2 concentration of the negative control group (0.03 ± 0.02 ng/ml) was significantly lower (p < 0.01) than in the ET group (7.26 ± 4.16). All the treated groups showed a statistical difference as compared to the ET group (p < 0.01, Student test). Mean LTB4 concentration of the negative control group (4.44 ± 0.33 ng/ml) was also significantly lower (p<0.01) than in the ET group (5.10 ± 0.61). Treatment with DFNa did not result in a decrease of the aqueous LTB4 levels. It is concluded that topical DFNa results in a decrease of aqueous PGE(2), without affecting LTB levels. To the best of our knowledge, such an effect of topical DFNa has not been reported previously.

The antiinflammatory effect of nordihydroguaiaretic acid in endotoxin induced uveitis in rabbits

The authors evaluated the anti-inflammatory effect of nordihydroguaiaretic acid (NDGA) and dexamethasone on an endotoxin induced uveitis (EIU) model, in rabbits. Six groups of 12 rabbits were formed. In groups II to V a uveitis was induced by an intravitreal injection of 5 ul of saline, containing 10 ng of endotoxin of Salmonella typhi. In group I, which is considered as the control, an intravitreal injection of 5 ul of saline was given. Each group received a different treatment and the inflammatory reaction was evaluated after 24 hours, quantifying the following parameters: clinical scoring, cells, proteins, PGE2, LTB4 in the aqueous and histopathological scoring. Compared to group II (non treated), group VI (treated with intraperitoneal 2 mg/kg dexamethasone) showed a decrease of 61% of proteins and LTB4, and a decrease of more than 90% of the other parameters studied. All these differences are statistically significant (p < 0.001). In groups III (intraperitoneal NDGA 10 mg/kg), IV and V (NDGA 1% topically every two and four hours respectively), the proteins showed a change of less than 5.5% and the PGE2 was reduced to around 50% compared to group II; these changes are not statistically significant (p > 0.05). The authors observed an important and significant decrease of the other parameters when compared to group II (p < 0.001). It can be concluded that at the doses given here, NDGA shows an effective action on the lipoxygenase pathway without an increase of the production of PGE2.

Ocular inflammatory effects of intravitreally injected tumor necrosis factor-alpha and endotoxin

Intravitreal injection of human recombinant tumor necrosis factor-alpha (TNF) induced inflammation in the rabbit eye characterized by dilation of blood vessels in the iris, disruption of the blood-ocular barriers, infiltration of inflammatory cells into the anterior chamber, and accumulation of prostaglandin E in intraocular fluids. Inflammation first appeared on day 1, increased on day 2, and remained elevated on day 7. The inflammatory cell infiltrate in the anterior segment of the eye was largely monocytic on days 1 and 2; by day 7 large numbers of lymphocytes were also present. TNF-induced ocular inflammation therefore differed from that reported for intravitreally injected endotoxin in terms of time course and the types of inflammatory cells in the aqueous humor. In a series of experiments in which combinations of TNF and endotoxin were used, intravitreal injection of TNF, 24 h after a low dose of Escherichia coli endotoxin, produced no more inflammation than that produced by TNF following an injection of endotoxin vehicle. However, if TNF was injected 24 h before endotoxin, the resulting inflammation was greater than that observed in animals given TNF followed by endotoxin vehicle.

Cytokines and intraocular inflammation

Although new endogenous mediators of inflammatory and immune responses are reported almost on a monthly basis, the cytokines IL-1, TNF, and IL-6 have emerged as the primary regulators of local inflammation in man. In this paper, uveitogenic and other properties of these particular cytokines are discussed and attention is payed to the possible involvement of a cytokine-network in the development of uveitis.