Studies on intraocular inflammation produced by intravitreal human interleukins in rabbits

Intracameral dexamethasone injection in the treatment of cataract surgery induced inflammation: design, development, and place in therapy

Cataract surgery is one of the most commonly performed surgeries worldwide, with nearly 20 million cases annually. Appropriate prophylaxis after cataract surgery can contribute to a safe and quick visual recovery with high patient satisfaction. Despite being the current standard of care, the use of multiple postoperative eye drops can create a significant burden on these patients, contributing to documented and significant non-adherence to the postoperative regimen. Over the past 25 years, there have been a few studies analyzing the use of intracameral dexamethasone (DXM) in controlling inflammation following cataract surgery. This review explores various drug delivery approaches for managing intraocular inflammation after cataract surgery, documenting the strengths and weaknesses of these options and examining the role of intracameral DXM (among these other strategies) in controlling postoperative intraocular inflammation. Intracameral DXM has a particular advantage over topical steroids in possibly decreasing postoperative inflammatory symptoms and objective anterior cell and flare scores. Compared to topical steroids, there may be a slightly less theoretical risk of significant intraocular pressure spikes and systemic absorption. In addition, surveys indicate patients prefer an intraoperative intracameral injection over a self-administered postoperative eye drop regimen. However, there are several adverse effects associated with intracameral DXM delivery that are not seen with the noninvasive topical approach. Although it is unlikely that intracameral DXM will replace topical medications as the standard management for postoperative inflammation, it is seemingly another safe and effective strategy for controlling postoperative inflammation after routine cataract surgery.

Intraocular pharmacokinetics of intravenously administered marbofloxacin in rabbits with experimentally induced acute endophthalmitis

OBJECTIVE

To compare penetration of IV administered marbofloxacin in intraocular fluids of healthy and inflamed eyes in rabbits with endotoxin-induced endophthalmitis.

ANIMALS

35 pigmented rabbits.

PROCEDURES

Endophthalmitis was induced in the right eye via intravitreal administration of Escherichia coli endotoxin. The left eye was a control eye. After 24 hours, a single dose of marbofloxacin (4 mg/kg, IV) was administered. Groups of rabbits (n = 5/group) were euthanized 0.5, 1, 2, 4, 6, 10, and 18 hours later, and blood and ocular fluids were collected. Marbofloxacin concentrations were determined via reverse-phase high-performance liquid chromatography, and pharmacokinetic analysis of the data was performed with a mono-compartmental model.

RESULTS

Mean area under the aqueous concentration-time curve was significantly lower in control eyes (1.64 +/- 0.07 microg*h/mL) than in inflamed eyes (3.31 +/- 0.11 microg*h/mL). Similarly, drug penetration into aqueous humor was 33% and 65% for control eyes and inflamed eyes, respectively. Mean area under the vitreous humor concentration-time curve for control eyes(1.75 +/- 0.05 microg*h/mL) was significantly less than for inflamed eyes (2.39 +/- 0.16 microg*h/mL). In the vitreous humor, corresponding penetrations were 34% and 47%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Penetration of marbofloxacin into the aqueous and vitreous humor after IV administration was significantly enhanced by intraocular inflammation, suggesting a role for this antimicrobial in the prophylaxis or treatment of bacterial endophthalmitis caused by susceptible pathogens.

Direct, real-time, simultaneous monitoring of intravitreal nitric oxide and oxygen in endotoxin-induced uveitis in rabbits

Nitric oxide (NO) plays a critical role in the pathogenesis of endotoxin-induced uveitis (EIU). Since NO is a labile free radical, it is difficult to examine the dynamics of NO directly in vivo. In this study, we established a system for direct monitoring of the dynamics of NO and partial pressure of oxygen (pO(2)) in EIU in rabbits. The currents (calculated concentrations) of NO and pO(2) in the vitreous were monitored after the intravitreal injection of lipopolysaccharide (LPS). In addition, the protein concentrations and nitrite levels in the aqueous humor were analyzed. The eyes were enucleated, and a histologic study was performed on their posterior segments. The tissue slices were also immunostained with anti-nitrotyrosine as a marker of peroxinitrite and/or nitrogen-related oxidants. The NO level decreased temporarily after LPS injection and then increased from 1 to 7 h. pO(2) increased temporarily for about 30 min after LPS injection. The change in NO current was inversely proportional to pO(2) after LPS injection and vice versa. The protein concentration and nitrite level after LPS injection increased significantly. These changes were suppressed by pretreatment with N(G)-nitro-l-arginine-methyl-ester. Immunohistochemical study showed enhanced immunoreactivity of nitrotyrosine in the inflamed retina. Since nitrotyrosine was detected, it appears that NO readily reacts with oxygen to produce cytotoxic species, peroxynitrite, and/or nitrogen-related oxidants. This process may be related to the retinal injury in EIU. This monitoring system can provide useful information on dynamic changes in intravitreal NO and pO(2) for understanding EIU.

Ocular penetration of caspofungin in a rabbit uveitis model

BACKGROUND

Little is known about the ocular penetration of echinocandin antifungals. We studied the ocular distribution of systemically administered caspofungin in a rabbit uveitis model.

METHODS

Caspofungin (1 mg/kg per day) was given intravenously to rabbits as a single dose or as repeated daily doses on 7 days starting 24 h after induction of unilateral uveitis by intravitreal endotoxin injection. Caspofungin concentrations were determined by high-performance liquid chromatography in the cornea, aqueous humor, vitreous humor, and serum 4, 8, 16, and 24 h after administration of a single dose and 24 h after the last of seven doses.

RESULTS

The mean caspofungin concentration in the aqueous of the inflamed eye 4 and 8 h after single-dose administration was 1.30 +/- 0.39 microg/ml and 1.12 +/- 0.34 microg/ml, respectively. Drug concentrations decreased to 0.24 +/- 0.09 microg/ml at 16 h and 0.26 +/- 0.14 microg/ml at 24 h. In the vitreous of inflamed eyes drug levels were undetectable at all time points. No drug was found in the aqueous of inflamed eyes 24 h after the last of seven repeated doses, and the vitreous only contained trace amounts. In the corneas of inflamed eyes concentrations reached 1.64 +/- 0.48 microg/g at 4 h, peaked at 2.16 +/- 1.14 microg/g at 8 h, and declined to 1.87 +/- 0.52 microg/g and 1.49 +/- 0.48 microg/g at 16 and 24 h, respectively. After repeated dosing, corneal concentrations of caspofungin were 0.8 and 1.0 microg/g and below the limit of detection in two of four animals. In non-inflamed eyes no drug was detectable in the aqueous and vitreous humor, and the corneas at any time point.

CONCLUSIONS

In our model, caspofungin reached therapeutically relevant levels in the aqueous and cornea but not in the vitreous humor of inflamed eyes. Intraocular drug deposition was critically dependent on a disrupted blood-eye barrier. These findings suggest a limited role for caspofungin in the treatment of fungal endophthalmitis.

Transcription Factors NF-κB and C/EBPδ and IL-1-Induced Expression of Surfactant Protein A in Lung Explants during the Perinatal Period

Interleukin-1 (IL-1) increases the expression of surfactant protein A (SP-A) in rabbit, lamb and human fetal lung. The upregulation disappears towards term. Among the transcription factors, IL-1 activates nuclear factor kappaB (NF-kappaB) and CCAAT/enhancer-binding protein delta (C/EBPdelta). NF-kappaB presumably has a role in IL-1-induced upregulation of SP-A. Also, C/EBPdelta may regulate SP-A expression. The aim was to study the role of these transcription factors in the induced effect of IL-1 on SP-A expression. Explants from fetal and neonatal rabbit lung were cultured in vitro followed by studies using immunohistochemistry, electrophoretic mobility shift assay and Northern analysis. We found gestation-dependent changes in IL-1-induced immunoreactivities of NF-kappaB and C/EBPdelta in the nuclei of alveolar cells. This increase in nuclear transcription factors correlated with IL-1-induced SP-A expression levels. As studied in the explants from fetal and newborn lung, the SP-A mRNA expression additionally associated with C/EBPdelta mRNA and with the binding of nuclear extracts from the lung explants to the C/EBP consensus probe. On the basis of the present and previous studies, we propose that NF-kappaB and C/EBPdelta have potential mediator roles in IL-1-induced upregulation of SP-A in immature lung.

Corneal Concentrations following Systemic Administration of Amphotericin B and Its Lipid Preparations in a Rabbit Model

BACKGROUND

Amphotericin B (AmB) and various lipid formulations of AmB are available for the treatment of fungal infections of the eye. Currently, the recommended route of administration for the treatment of fungal keratitis is by topical application. Nevertheless, because of the risk of a difficult to treat exogenous fungal endophthalmitis, a combined topical and systemic treatment is frequently given when treating deep fungal keratitis. To date, little is known about the pure corneal availability of these drugs following systemic treatment. In this study, the corneal concentration following 7 daily doses of parenteral AmB lipid complex (ABLC) or liposomal AmB (L-AmB) was compared to that of AmB deoxycholate (D-AmB) in a rabbit model.

METHODS

Following induction of uveitis in one rabbit eye by intravitreal injection of endotoxin, daily doses of D-AmB (1 mg/kg), ABLC (5 mg/kg) or L-AmB (5 mg/kg) were given intravenously on 7 consecutive days. Five or more rabbits per treatment were used. AmB concentrations were determined by high-performance liquid chromatography (HPLC) in corneas collected at autopsy 24 h after the 7th and final dose. Data were analyzed using the Mann-Whitney U test.

RESULTS

After 7 days of treatment, mean corneal concentrations of AmB in the inflamed eyes were significantly higher (2.38 +/- 1.47 microg/g; p < 0.01) following treatment with L-AmB compared with ABLC (<0.1 microg/g) and D-AmB (0.46 +/- 0.2 microg/g). No AmB could be detected in the corneas of the non-inflamed eyes.

CONCLUSION

In our rabbit model, AmB penetration into the cornea was significantly higher after systemic administration of L-AmB compared with conventional D-AmB or ABLC.

Inflammatory and anti-inflammatory responsiveness of surfactant proteins in fetal and neonatal rabbit lung

Spontaneous preterm birth due to intrauterine infection is associated with increased concentrations of cytokines in amniotic fluid and in the airways at birth. Intra-amniotic IL-1 induces fetal lung maturity, consistent with the decrease in the incidence of respiratory distress syndrome (RDS) in intrauterine inflammation. On the other hand, antenatal corticosteroid decreases the incidence of RDS in infants born prematurely. The aim of the present study was to investigate the interaction between IL-1 and glucocorticoid in the expression of the surfactant proteins SP-A, -B, and -C. Lung explants from rabbit fetuses at 22 (immature), 27 (transitional), and 30 (mature) d of gestation (term, 30-31 d) and on d 1 after term birth were cultured with dexamethasone (Dx), IL-1alpha, or vehicle in the presence or absence of actinomycin D. According to the present results, IL-1alpha and Dx additively increased the expression of SP-A and SP-B on d 22. Later in gestation, SP-B and SP-C were suppressed by IL-1, whereas glucocorticoid tended to increase the expression of SP-B and SP-C and prevented the IL-1-induced suppression of SP. IL-1alpha and steroid interactively increased the stability of SP mRNA compared with the single agonist, possibly explaining the additive effects on the SP mRNA levels. The present results reveal beneficial additive effects of glucocorticoid and cytokine on lung surfactant. They may explain some of the acute beneficial effects of glucocorticoid therapy in chorioamnionitis before premature birth and in inflammatory lung disease after birth.

Transforming growth factor-beta2 inhibition of corneal endothelial proliferation mediated by prostaglandin

PURPOSE

To determine the influence of Prostaglandin (PG) E2 on transforming growth factor (TGF)-beta2-mediated inhibitory effects on the proliferation of corneal endothelial cells (CE).

METHODS

The PGE2 and cell proliferation assays were performed using cultured rabbit corneal endothelium. A PGE2-specific enzyme immunoassay was used to check PGE2 synthesis in supernatants of cells cultured with and without added TGF-beta2 and/or indomethacin. To evaluate the inhibitory effects of PGE2 and TGF-beta2 on CE proliferation, the number of cells grown with exogenous PGE2, or TGF-beta2 with or without indomethacin pretreatment was determined.

RESULTS

TGF-beta2, 0.5 to 50 ng/ml, increased the PGE2 secretion of CE dose-dependently in a time-dependent manner. Indomethacin (> or =0.1 microg/ml) inhibited this PGE2 secretion to a low level (around 5-10 ng/ml) in the presence or absence of exogenous TGF-beta2. Both exogenous TGF-beta2 and PGE2 inhibited CE proliferation dose-dependently over a wide range of concentrations. Indomethacin reversed the inhibitory effects of TGF-beta2 but not those of exogenous PGE2. In the medium supplemented with indomethacin, even in the presence of 50 ng/ml of TGF-beta2, CE growth did not differ from control cultures.

CONCLUSIONS

TGF-beta2 stimulates PGE2 synthesis in CE and inhibits CE proliferation in a dose-dependent manner. Indomethacin extinguishes the inhibitory effects of TGF-beta2 on CE proliferation but not the effect of exogenous PGE2. These data suggest that the antiproliferative effects of TGF-beta2 on CE may be possibly due to TGF-beta2-induced synthesis of PG, most likely PGE2.

SUMMARY

Inhibition of endogenous prostaglandins synthesis by indomethacin extinguished the inhibitory effects of Transforming Growth Factor-beta2 on corneal endothelium proliferation but not exogenous prostaglandin E2. It suggesting that TGF-beta2-induced autocrine synthesis of PGs, most likely PGE2, may be responsible for the anti-proliferative effects of TGF-beta2 on corneal endothelium.

Ocular distribution of intravenously administered lipid formulations of amphotericin B in a rabbit model

Little is known about the ocular penetration of amphotericin B (AMB) and its lipid formulations, the current drug of choice in fungal endophthalmitis. The ocular distribution of AMB lipid complex (ABLC), liposomal AMB (L-AMB), and AMB deoxycholate (D-AMB) was studied in a rabbit model. D-AMB (1 mg/kg of body weight/day), ABLC (5 mg/kg/day), or L-AMB (5 mg/kg/day) was given intravenously to rabbits as a single dose or as repeated daily doses on 7 consecutive days after induction of unilateral uveitis by intravitreal injection of endotoxin. AMB concentrations in aqueous humor, vitreous humor, and plasma were determined by high-pressure liquid chromatography 16 h after administration of a single dose or 24 h after the last of seven doses. After single-dose administration, L-AMB achieved at least eightfold-higher AMB concentrations in the aqueous of inflamed eyes than ABLC or D-AMB (1.21 +/- 0.58 micro g/ml versus 0.14 +/- 0.04 and 0.11 +/- 0.09 micro g/ml, respectively). At that time point no drug was detectable in the vitreous. After 7 days of treatment, the concentration of AMB in the vitreous was higher after treatment with L-AMB (0.47 +/- 0.21 micro g/ml) than after treatment with ABLC (0.27 +/- 0.18 micro g/ml) and D-AMB (0.16 +/- 0.04 micro g/ml). Similarly, AMB concentration in the aqueous was higher after repeated doses of L-AMB (0.73 +/- 0.43 micro g/ml) than after repeated doses of ABLC (0.03 +/- 0.02 micro g/ml) or D-AMB (0.13 +/- 0.06 micro g/ml). No AMB was detected in noninflamed eyes. Following systemic administration, AMB distribution to the eye is inflammation dependent and occurs sequentially, first to the aqueous and then to the vitreous. Compared to D-AMB and ABLC, L-AMB reaches higher drug concentrations in both ocular compartments.

Regulation of surfactant proteins by LPS and proinflammatory cytokines in fetal and newborn lung

Intra-amniotic lipopolysaccharide (LPS) and cytokines may decrease respiratory distress syndrome (RDS) and increase chronic lung disease in the newborn. The aim was to identify the primary inflammatory mediators regulating the expression of surfactant proteins (SP) in explants from immature (22-day-old fetus) and mature (30-day term fetus and 2-day-old newborn) rabbits. In immature lung, interleukin (IL)-1alpha and IL-1beta upregulated the expression of SP-A and SP-B. These effects of IL-1 were diminished, and SP-C mRNA was suppressed additively in the presence of tumor necrosis factor (TNF)-alpha and either LPS or interferon (IFN)-gamma. LPS, TNF-alpha, or IFN-gamma had no effect alone. In explants from the term fetus and the newborn, LPS, IL-1alpha, and TNF-alpha additively suppressed the SPs. LPS acutely induced IL-1alpha in alveolar macrophages in mature lung but not in the immature lung. IFN-gamma that generally has low expression in intrauterine infection decreased the age dependence of the other agonists' effects on SPs. The present study serves to explain the variation of the pulmonary outcome after an inflammatory insult. We propose that IL-1 from extrapulmonary sources induces the SPs in premature lung and is responsible for the decreased risk of RDS in intra-amniotic infection.

Disruption of the blood-aqueous barrier following retinal laser photocoagulation and cryopexy in pigmented rabbits

Disruption of the blood-aqueous barrier (BAB) induced by retinal photocoagulation and cryopexy in pigmented rabbits was evaluated by laser flare photometry. A significant increase in flare values after retinal photocoagulation was measured from the 1st postoperative day, with values returning to baseline levels by day 7. Cryopexy induced consistently high flare values for 14 days. Intravitreal injection of interleukin (IL) 1, IL-6 and prostaglandin (PG) E(2) induced a significant increase in flare values. Following these treatments, introduction of a PG synthetase inhibitor can partially ameliorate BAB disruption. IL-1, IL-6 and PGE(2) may be involved in BAB disruption following retinal photocoagulation and cryopexy.

Vasoactive intestinal peptide (VIP) exacerbates endotoxin-induced uveitis (EIU) in mice

PURPOSE

We have previously shown that inhibition of the proinflammatory cytokine tumor necrosis factor- (TNF)-alpha exacerbates the inflammatory process of EIU. To further examine this paradoxic phenomenon, we investigated here the effect on EIU of VIP, a neuropeptide that inbibits TNF-alpha production.

METHODS

VIP was injected concurrently with endotoxin at doses that induce EIU or lethality in mice. Severity of EIU was measured by counting infiltrating cells in eye sections, at 1 or 5 days post endotoxin injection. Survival of mice was monitored periodically, while serum levels of TNF-alpha, interleukin-(IL)-1beta and IL-10 were determined by caputure ELISA.

RESULTS

Treatment with VIP exacerbated EIU but provided partial protection from the lethal endotoxin effect. VIP treatment also reduced serum levels of TNF-alpha and IL-1beta, but increased levels of IL-10.

CONCLUSION

This study further established the paradoxical observation that EIU is exacerbated by lowering the levels of circulating pro-inflammatory cytokines, in particular TNF-alpha.

Degree of lung maturity determines the direction of the interleukin-1- induced effect on the expression of surfactant proteins

Intra-amniotic interleukin (IL)-1 increases surfactant components in immature fetal lung, whereas high IL-1 after birth is associated with surfactant dysfunction. Our aim was to investigate whether the fetal age influences the responsiveness of surfactant proteins (SPs) to IL-1. Rabbit lung explants from fetuses at 19, 22, 27, and 30 d of gestation and 1-d-old newborns were cultured in serum-free medium in the presence of recombinant human (rh) IL-1alpha or vehicle. The influence of IL-1alpha on SP-A, -B, and -C messenger RNA (mRNA) content was dependent on the conceptional age. In very immature lung on Day 19, rhIL-1alpha (570 ng/ml for 20 h) increased SP-A, -B, and -C mRNA by 860+/-15%, 314+/-108%, and 64+/-17%, respectively. The increase in SP-A mRNA was evident within 4 to 6 h. IL-1alpha increased the SP-A concentration in alveolar epithelial cells and in the culture medium within 20 h. In contrast, at 27 to 30 d of gestation and in newborns, IL-1alpha decreased SP-C, -B, and -A mRNA by means of 64 to 67%, 48 to 59%, and 12 to 15%, respectively. SP-B protein decreased by 45 to 60%. The decrease in mRNA became evident within 8 to 12 h and was dependent on IL-1 concentration. On Day 27, IL-1alpha accelerated the degradation of SP-B mRNA in the presence of actinomycin D. IL-1 did not increase the degradation rate of SP-A mRNA unless both actinomycin D and cycloheximide were added to the explants. The present findings may explain some of the contrasting associations between inflammatory cytokines and lung diseases during the perinatal period. The determinants of the direction of the IL-1 effect on the expression of SPs remain to be identified.

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

The objective of the study was to investigate involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist (IL-1Ra) in lipopolysaccharide (LPS)-induced uveitis. Intravitreal injection of LPS (100 ng) to rabbits induced a massive leukocyte infiltration and protein leakage into the aqueous humor. Aqueous leukocyte counts and protein levels reached a peak 24 hr after this injection. The peak concentrations of aqueous TNF alpha (230 +/- 37 pg ml-1, at 9 hr) and IL-1 beta (185 +/- 80 pg ml-1, at 18 hr) preceded peak levels of aqueous leukocyte counts and protein levels. In contrast, the levels of aqueous IL-1Ra peaked at 48 hr (12,239 +/- 1964 pg ml-1) and a fairly high concentration of IL-1Ra remained when the inflammatory reactions subsided. Immunohistochemistry and leukocyte-depletion studies showed that infiltrating leukocytes were the major cellular sources of aqueous TNF alpha, IL-1 beta and IL-1Ra. Intravitreal injection of homologous TNF alpha (0.1-1.5 micrograms) or IL-1 beta (0.5-5 ng) reproduced a rapid leukocyte infiltration and protein leakage. Administration of anti-TNF alpha mAb (10 micrograms) suppressed the number of LPS-induced infiltrating neutrophils by 50%, mononuclear cells by 58%, and protein leakage by 42%. Administration of rabbit IL-1Ra (10 micrograms) also suppressed neutrophil influx by 78%, however, neither mononuclear cell influx nor protein leakage was inhibited by rabbit IL-1Ra. Co-administration of the two inhibitors enhanced inhibition of neutrophil infiltration to 88%, and protein leakage to 64%. We conclude that TNF alpha and IL-1 beta are the principal mediators of LPS-induced uveitis. Our observations also suggest that endogenous IL-1Ra may down-regulate inflammatory reactions.

Induction of arachidonic acid metabolite release by human fibroblasts in proliferative vitreoretinopathy

Proliferative vitreoretinopathy is a severe ocular disorder characterized by unwanted proliferation of cells and excessive production of fibrous tissue, which leads to the formation of cellular membranes on the surface of the retina and in the vitreous. Proliferative vitreoretinopathy is the most common cause of failure in retinal reattachment surgery, approximately occurring in one out of ten operated eyes. Proliferation of retinal pigment epithelial cells and fibroblasts is a cornerstone in the pathogenesis of proliferative vitreoretinopathy. An in vitro-proliferation assay showed previously that intraocular fluid from patients with proliferative vitreoretinopathy is potently effective in stimulating proliferation of human fibroblasts. Here we show that exposure of human fibroblasts to vitreous fluids from patients with proliferative vitreoretinopathy causes a rapid and sustained increase in arachidonic acid metabolite release as measured by competitive enzyme-immunoassay. The findings implicate prostaglandin E2 as a contributor to enhanced intraocular fibrosis in proliferative vitreoretinopathy. As prostaglandin E2 is a mediator of continuous aqueous-blood retinal barrier breakdown in this severe disease, cycclooxygenase inhibitors such as acetylsalicylic acid, which was successfully used in this study for blocking the effect of intraocular fluid, may be useful agents in targeting the progression of intraocular fibrosis.

Cyclooxygenase-2 inhibitors: a new approach to the therapy of ocular inflammation

Prostaglandins (PGs) can be synthesized through the activities of two cyclooxygenase (COX) isoforms. COX-1 is constitutively expressed in most tissues and its activity provides for the relative small amounts of PGs required for the mediation and modulation of normal physiological functions. In inflammatory conditions, COX-2 is rapidly induced by cytokines, growth factors and bacterial endotoxin, and its enzymatic activity accounts for the large amounts of PGs produced during inflammation. The currently used nonsteroidal anti-inflammatory drugs (NSAIDs) are nonselective inhibitors of both COX isoforms. Inhibition of COX-2 leads to the therapeutically desired inhibition of the synthesis of pro-inflammatory PGs, but at the same time produces side effects associated with inhibition of COX-1 and the consequent suppression of the production of PGs necessary for normal cellular functions. Selective inhibition of COX-2 expression explains, at least in part, the potent anti-inflammatory activity of corticosteroids. However, the systemic and ocular side effects of these steroids have greatly limited their use, especially their long-term use for the management of chronic inflammatory conditions. The current effort to develop highly selective nonsteroidal COX-2 inhibitors for the treatment of arthritis and other inflammatory diseases can also be expected to yield a new approach to the treatment of uveitis and other ocular inflammatory conditions. This new class of NSAIDs will provide anti-inflammatory and analgesic activity while circumventing the most serious side effects of the current available NSAIDs, resulting from their inhibition of the physiologically required COX-1 activity.

Effect of interleukin 1 receptor antagonist on the blood-aqueous barrier after intraocular lens implantation

Interleukin 1 (IL-1) possesses as an intercellular signal a wide spectrum of inflammatory, metabolic, haematopoetic, immunological, and reparative properties and can be a mediator not only of host defence but also of disease. Reduction of IL-1 can decrease the inflammatory host response. A human recombinant IL-1 receptor antagonist (IL-1ra) was used to block IL-1 after intraocular lens implantation in rabbits. Seventeen rabbits underwent intercapsular phacoemulsification and posterior chamber lens implantation. A 100 micrograms dose (0.1 ml) of IL-1ra (1 mg/ml) was injected into the anterior chamber at the end of surgery in seven rabbits. The 10 rabbits serving as the controls received no IL-1ra. Postoperatively, all rabbits were observed with a slit-lamp, and the aqueous flare intensity was measured with a laser flare cell meter at 12 hours, 1, 2, 3, and 4 days and thereafter at 1, 2, 3, and 4 weeks. Aqueous flare intensity was significantly lower on days 2 and 3, and fibrin deposition much less marked in the eyes treated with IL-1ra, compared with the controls. The results suggest that IL-1 is involved in the postoperative inflammation that occurs after intraocular lens implantation and the use of the IL-1ra would be valuable for reducing this problem.

Prevention and treatment of ocular inflammation with a new class of non-steroidal anti-inflammatory agents

New non-steroidal anti-inflammatory agents (NSAIAs) were tested on lens protein-, endotoxin- and interleukin-1-induced ocular inflammation. It was found that most NSAIAs, including REV 5901, mefenamic acid, indomethacin, CK-17 and CK-102, inhibited lens protein-induced inflammation. Endotoxin induced inflammation indirectly through the release of IL-1 which was inhibited by fewer agents, including CK-17, CK-102 and prednisolone. However, the direct effect of IL-1 can only be suppressed by CK-17 and prednisolone. Therefore, CK-17 could become an important NSAIA which acts similarly to corticosteroids yet produces no steroidal side effects. CK-17 was different from most NSAIAs as it affected little, if any, arachidonate metabolism. Most importantly, CK-17 was found to be 2-fold more potent than prednisolone in inhibiting IL-1-induced uveitis, while no side effects were noted at doses tested to date.

Ocular inflammatory effects of intravitreally injected interleukin-2

The primary, known physiologic effect of interleukin-2 (IL-2) is to act as a T lymphocyte growth factor. We investigated the potential contribution of IL-2 to intraocular inflammation by studying the inflammation resulting from the intravitreal injection of recombinant, human IL-2 in New Zealand white rabbits. Serial slit lamp observations indicated that 40 microgram of intravitreally injected IL-2 induced an anterior uveitis which was maximal 5 days after the injection. Inflammation was less marked but still significant with amounts of IL-2 as low as 400 ng. Direct examination of aqueous humor confirmed elevations of protein, prostaglandin E2, and mononuclear cells which correlated with the clinical observations. The kinetics of the response to intravitreal IL-2 distinguished it from the responses to other intravitreally injected cytokines such as interleukins 1, 6, or 8 as well as tumor necrosis factor. Intramuscular injection of cyclosporine A significantly reduced the protein extravasation associated with IL-2 injection, but cyclosporine had no effect on inflammation secondary to an intravitreal injection of interleukin-1. These observations implicate IL-2 as a potential contributor to uveitis. In addition, the studies with cyclosporine indicate the heterogeneity of inflammation such that pharmacologic agents which affect one cause of uveitis are not necessarily efficacious in another model.