Uveitis In Rabbits Research Articles

Evaluation of a Prednisolone Acetate-Loaded Subconjunctival Implant for the Treatment of Recurrent Uveitis in a Rabbit Model

AimTo assess the efficacy of a biodegradable, prednisolone acetate implant in a rabbit uveitis model.MethodsRandomized, controlled study of biodegradable microfilms preloaded with prednisolone acetate (PA) in a rabbit uveitis model. Experimental uveitis was induced by unilateral intravitreal injection of Mycobacterium tuberculosis H37Ra antigen (50 ug; 1 ug/uL) in preimmunized rabbits. PA-loaded poly[d,l-lactide-co-ε-caprolactone] (PLC) microfilms (n = 10) and blank microfilms (n = 6) were implanted subconjunctivally. An estimate of PA release in vivo was calculated from measured residual PA amounts in microfilms after the rabbits were sacrificed. The eyes were clinically monitored for ocular inflammation for 28 days. Histopathological examination of the enucleated eyes was performed at the end of the study period.Results In vitro studies revealed that sandwich PA-loaded microfilm formulations exhibited higher release kinetic compared to homogenous PA-loaded microfilms. The 60–40–60% microfilm released an average of 0.034 mg/day of PA over the period of 60 days in vitro; and we found that approximately 0.12 mg/day PA was released in vivo. Animals implanted with the PA-loaded microfilms exhibited significantly lowered median inflammatory scores when compared against the control group in this model for recurrent uveitis (P<0.001). The implants were clinically well tolerated by all the animals. Histology results showed no significant scarring or inflammation around the PA-loaded microfilms.ConclusionOur pilot study demonstrated that a subconjunctival PA-loaded implant is effective in suppressing inflammation in the rabbit model of uveitis, by providing therapeutic levels of PA that attenuated the inflammatory response even after a rechallenge. Longer term studies are now needed to establish the therapeutic potential of such a delivery system for treatment of ocular inflammation.

Evaluations of therapeutic efficacy of intravitreal injected polylactic-glycolic acid microspheres loaded with triamcinolone acetonide on a rabbit model of uveitis

Conventional treatments of uveitis are not ideal because of the short period of therapeutic efficacy. In the present study, biodegradable polylactic-glycolic acid microspheres loaded with triamcinolone acetonide (TA) were prepared to achieve sustained drug release and their therapeutic efficacy was investigated on a rabbit model of uveitis. TA-loaded microspheres (TA-MS) were prepared by the solvent evaporation method and characterized for encapsulation efficiency, particle size, morphology and in vitro release. The therapeutic efficacy was studied on the rabbit experimental uveitis model based on scoring of the inflammation, aqueous leukocyte counting, aqueous protein determination and histological examination. The TA-MS exhibited smooth and intact surfaces with an average diameter of 50.87 μm. The drug-loading coefficient and encapsulation efficiency were 15.2 ± 0.6 % and 91.24 ± 3.77 %, respectively. The drug release from TA-MS lasted up to 87 days, but only 46 days for TA suspension. The change in surface morphology also showed sustained drug release from TA-MS. TA-MS exhibited improved therapeutic efficacy in lipopolysaccharide -induced uveitis compared to TA suspension, especially in regard to the inhibition of inflammation. The TA-MS had a longer-term therapeutic effect on intraocular inflammation in LPS-induced uveitis in rabbits compared to TA suspension. The results suggested that TA-MS can be developed as a potential sustained-release system for the treatment of uveitis.

A new drug delivery system inhibits uveitis in an animal model after cataract surgery

Cataract surgery is a common ocular surgical procedure consisting in the implantation of an artificial intraocular lens (IOL) to replace the ageing, dystrophic or damaged natural one. The management of postoperative ocular inflammation is a major challenge especially in the context of pre-existing uveitis. The association of the implanted IOL with a drug delivery system (DDS) allows the prolonged intraocular release of anti-inflammatory agents after surgery. Thus IOL-DDS represents an "all in one" strategy that simultaneously addresses both cataract and inflammation issues. Polymeric DDS loaded with two model anti-inflammatory drugs (triamcinolone acetonide (TA) and cyclosporine A (CsA)) were manufactured in a novel way and tested regarding their efficiency for the management of intraocular inflammation during the 3 months following surgery. The study involved an experimentally induced uveitis in rabbits. Experimental results showed that medicated DDS efficiently reduced ocular inflammation (decrease of protein concentration in aqueous humour, inflammatory cells in aqueous humour and clinical score). Additionally, more than 60% of the loading dose remained in the DDS at the end of the experiment, suggesting that the system could potentially cover longer inflammatory episodes. Thus, IOL-DDS were demonstrated to inhibit intraocular inflammation for at least 3 months after cataract surgery, representing a potential novel approach to cataract surgery in eyes with pre-existing uveitis.

Mucoadhesive Chitosan-Coated Cationic Microemulsion of Dexamethasone for Ocular Delivery: In Vitro and In Vivo Evaluation

ABSTRACTPurpose: Dexamethasone (DXN) is an effective anti-inflammatory drug in the treatment of acute and chronic eye disease such as uveitis. However, its low aqueous solubility limits its clinical usefulness. The purpose of this study was to investigate the mucoadhesive chitosan-coated cationic microemulsions (CH-MEs) for ophthalmic delivery of DXN to treat uveitis.Materials and methods: The pseudo-ternary phase diagrams were developed and various MEs were prepared using isopropyl myristate as oil, Tween 80 as a surfactant, propylene glycol as a co-surfactant and distilled water. MEs were prepared and coated with chitosan by the dropwise addition of chitosan solution in the ME dispersion. Physicochemical parameters (globule size, zetapotential, drug content, viscosity, refractive index and pH), mucoadhesive properties and the in vitro release of MEs were studied. The in vivo efficacy of prepared formulations and the marketed drug solution were studied by administering them topically to endotoxin-induced uveitis rabbit model.Results: All formulations displayed an average globule size less than 200 nm and a positive surface charge. The developed CH-MEs showed acceptable physico-chemical behavior, good mucoadhesive properties, good stability for three months and exhibited sustained drug release. In vivo studies in rabbit eye showed a marked improvement in the anti-inflammatory activity of mucoadhesive CH-ME-treated eye compared with a marketed suspension formulation in a uveitis-induced rabbit eye model.Conclusion: The developed CH-MEs are a viable alternative to conventional eye drops for its ability to enhance bioavailability through its longer precorneal residence time and its ability to sustain the release of the drug.

Traditional Japanese Herbal (Kampo) Medicines and Treatment of Ocular Diseases: A Review

Herbal medicines have been used clinically in Eastern Asia, and traditional Japanese herbal (Kampo) formulas are approved as ethical drugs. The Kampo formulas are mixtures of the crude extracts of several herbs, each of which contains multiple components. Numerous investigators have reported that some herbal medicines are efficacious for treating several human diseases. We reviewed the literature on traditional herbal medicines and treatment of ocular diseases. Oral Orengedoku-to and Kakkon-to inhibit postoperative uveitis in humans. Oral Goshajinki-gan improved ocular surface disorders in patients with type 1 diabetes mellitus. Oral Hachimijio-gan increased retinal blood flow. Keishi-bukuryo-gan Sho might be associated with vitreoretinopathy in patients with type 2 diabetes mellitus. Oral Hachimijio-gan and Goshajinki-gan delayed lens opacification in rats and mice. Oral Sairei-to, Orengedoku-to, Senkanmeimoku-to, Scutellariae radix extract, Gardeniae fructus extract, topical Liguisticum wallichii rhizoma extract, and intravenous injection of tetramethylpyrazine, baicalin, baicalein, wogonin, and crocetin inhibited some forms of experimental uveitis in rabbits. Topical glycyrrhizinate improved allergic conjunctivitis in humans and rats. Oral crocetin improved eyestrain in humans. Oral berberine diminished experimental uveitis in rats. Baicalein, wogonin, berberine, and berberrubine inhibited in vitro expression of several cytokines in cultured retinal pigment epithelial cells. Some Kampo formulas are efficacious for treating several ocular diseases in humans and animals. Some herbal extracts and their components inhibit some forms of experimental uveitis.

Model of uveitis in rabbit

Abstract Purpose To develop a long‐term experimental model of uveitis using a new easier method for animals. Methods A suspension of desiccated Mycobacterium tuberculosis H37RA was mixed with TiterMax® Gold Adjuvant to produce a water‐in‐oil emulsion. Pigmented rabbits were pre‐sensitized with a s.c. multisite injection (400 ul) of emulsion. Two challenges were performed by intravitreal injection of 100 ul of M. tuberculosis H37RA suspension, under systemic and topical anesthesia. Clinical examinations and aqueous humors punctures under systemic anesthesia were regularly performed till day 71. Hyperemia, chemosis, edema and secretion were clinically scored from 0 to 3. Ocular inflammation was assessed by: a) the clinical score mean (sum of individual scores divided by 4), b) the number of inflammatory cells in aqueous humor (AH) and c) the protein concentration in AH. Results Rabbits presented a nodule at the sites of pre‐sensitization injection. Clinical score of inflammation reached a maximum 3 days after the first intravitreal challenge. The AH contained 835 cells/ ul and protein concentration in AH was 30 mg /ml. During the following days, inflammatory cell number and protein concentration in AH significantly decreased, whereas the clinical score returned to zero. The second intravitreal challenge induced an inflammation; six days after this challenge, 3800 cells/ul and 30 mg of proteins /ml were counted in AH. Inflammation remained high to moderate over 21 days at least. Conclusion We developed a new model of experimental uveitis, whose schedule was simple. The use of TiterMax® Gold Adjuvant showed advantages over other adjuvants. And uveitis could be maintained during 21 days at least.

Biodegradable Intrascleral Implant of Triamcinolone Acetonide in Experimental Uveitis

To evaluate the efficacy of a biodegradable intrascleral implant of triamcinolone acetonide (TA) in a rabbit model of experimental uveitis. A disc-shaped TA implant (1 x 3 mm, containing 6.4 mg of TA), which is made by poly(D,L-lactide) (PLA) and TA, was intrasclerally implanted into eight albino rabbits after a subcutaneous injection of tuberculin antigen. Control animals (n = 8) received sham devices. Uveitis was induced with an intravitreal injection of tuberculin antigen. To induce chronic inflammation, all eyes were reinjected with intravitreal antigen on day 14 and were observed for 1 month. Aqueous protein concentrations and cell counts were determined on days 7, 14, and 28. Inflammation of the anterior chamber (AC) and vitreous opacity were graded clinically and retinal functions were evaluated electroretinographically and histologically. Anterior chamber cells, flare, and vitreous opacity scores showed significantly less inflammation in treated eyes than in untreated eyes (P < 0.05). Quantitative analyses of aqueous cell counts and protein concentrations showed significant decreases in treated eyes (P < 0.05). Histopathologic examinations showed less severe inflammation and tissue disorganization in treated eyes. The biodegradable intrascleral TA implant was found to be effective at suppressing the inflammation induced by experimental uveitis in rabbits for at least 4 weeks.

The Anti-inflammatory Effects ofCurcuma longaandBerberis aristatain Endotoxin-Induced Uveitis in Rabbits

To investigate the anti-inflammatory effect of topical application of Curcuma longa (C. longa) and Berberis aristata (B. aristata) aqueous extracts on experimental uveitis in the rabbit. Anterior uveitis was induced in rabbits by intravitreal injection of lipopolysaccharide from Escherichia coli after pretreatment with C. longa and B. aristata aqueous extracts. Subsequently, the anti-inflammatory activity of C. longa and B. aristata was evaluated by grading the clinical signs and histopathologic changes and estimating the inflammatory cell count, protein, and TNF-alpha levels in the aqueous humor. The anterior segment inflammation in the control group was significantly higher than in both the extract-treated groups, as observed by clinical and histopathologic grading. The inflammatory cell count in the control group was 30.75 +/- 7.33 x 10(5) cells/mL, whereas it was 2.39 +/- 0.59 x 10(5) (P < 0.001 vs. control) and 11.56 +/- 2.44 x 10(5) (P = 0.001 vs. control) cells/mL in the C. longa- and B. aristata-treated groups, respectively. The protein content of the aqueous humor was 18.14 +/- 4.98, 3.16 +/- 0.55 (P < 0.001 vs. control), and 8.24 +/- 1.42 (P < 0.01 vs. control) mg/mL in the control, C. longa-, and B. aristata-treated groups, respectively. The aqueous TNF-alpha level in the control group was 976.29 +/- 66.38 pg/mL and was 311.96 +/- 28.50 (P < 0.0001 vs. control) and 654.09 +/- 47.66 (P < 0.001vs. control) pg/mL in the C. longa- and B. aristata-treated groups, respectively. Topical instillation of aqueous extracts of C. longa and B. aristata showed potent anti-inflammatory activity against endotoxin-induced uveitis in rabbits.

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

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

Model of immunogenic uveitis in rabbits

Six models of experimental immunogenic uveitis induced by injection of normal horse serum were tried in rabbits. A convenient working variant of the model was developed characterized by high activity and long duration of the inflammatory process in the eye. Creation of this model requires pre-sensitization (subcutaneous injection of 5 ml normal horse serum) followed by intravitreal injection of the resolving dose of horse serum on day 9. An adapted improved model of experimental immunogenic uveitis in rabbits is proposed.

Therapeutic and Toxicological Evaluations of Cyclosporine A Microspheres as a Treatment Vehicle for Uveitis in Rabbits

This study was undertaken to investigate the therapeutic efficacy and the toxicity of the intravitreal biodegradable poly(dl-lactide-co-glycolide)co-polymer microspheres containing cyclosporin A (CsA-PLGA-MS) on experimental uveitis in rabbits. CsA-PLGA-MS that had been prepared by a solvent evaporation approach were characterized for morphology, particle size, entrapment efficiency, and in vitro release profile of CsA-PLGA-MS. Therapeutic efficacy of the CsA-PLGA-MS was evaluated by scoring of the inflammation, aqueous leukocyte counting, aqueous protein determination, and histological examination in the experimental rabbits with artificial uveitis induced by the injection of lipopolysaccharide. The toxicity was investigated by slit-lamp examination, indirect ophthalmoscopy, and electroretinography (ERG) in the noninflamed rabbit eye. The CsA-PLGA-MS were spherical in shape, with an average particle size of nearly 50 microm and an entrapment efficiency of more than 80%. The compositions of the formulation that was most effective in the in vivo studies included CsA, PLGA, and 3% Pluronic F68. In vitro released cyclosporine A from the optimized microspheres was approximately 25% during the 60-day incubation at 37 degrees C. It was demonstrated that the intravitreal injection of the optimized CsA-PLGA-MS decreased significantly the severity of the inflammatory signs, cellular infiltrate, aqueous leukocyte counts, and protein levels in the eyes of experimental rabbits with uveitis, compared to other formulations. Also, the preparation did not cause obvious toxicity in the noninflamed eyes of rabbits, except that the ERG b-wave amplitude for the test eyes was reversibly depressed, compared to those of the control eyes at 2 weeks, which almost recovered at the end of 6 weeks. The CsA-PLGA-MS preparation might be useful in the treatment of patients with severe chronic posterior uveitis who cannot tolerate systemic or periocular therapy.

Intraocular implantation of cyclosporine A drug delivery system in the treatment of experimental uveitis

To investigate the effects and safety of cyclosporine A drug delivery system (CsA DDS) implanted into vitreous cavity on the treatment of experimental rabbit uveitis. A model of uveitis was established in 30 New Zealand white rabbits (30 eyes). The rabbits were randomized into control group (group A, 6 eyes), intravitreal non-medicated DDS group (group B, 6 eyes), oral CsA group (group C, 6 eyes) and intravitreal CsA DDS group (group D, 12 eyes). The inflammatory parameters such as floating cells, flaring and exudation in anterior chamber were graded. The cells infiltration and degree of opacity in vitreous were scored as well. The electroretinography and histopathological examination in eye, liver and kidney were recorded. In addition, CsA level in vitreous cavity was measured by HPLC in another 13 New Zealand white rabbits that received intravitreal implantation of CsA DDS. Uveitis was successfully induced in the 30 eyes. The inflammation in groups A, B and C was more severe than group D. There was no significant difference between groups D and A or B (P < 0.05). The electroretinography showed more significant b-wave depression in groups A and B than group D (P < 0.05). A large amount of inflammatory cells infiltration and marked tissue disorganization were found at ciliary body and retina in groups A and B. The mean drug level in vitreous cavity ws (491.0 +/- 481.6) ng/ml at 4 weeks, (575.2 +/-0373.2) ng/ml at 8 weeks and (301.5 +/- 128.5) ng/ml at 12 weeks. No toxicity could be detected in histological examination by light microscopy. Sustained therapeutic drug level could be achieved by implanting CsA DDS into vitreous cavity. It may effectively reduce the ocular inflammation in the rabbit model of uveitis.

The Efficacy of Hyperbaric Oxygen for the Treatment of Experimental Uveitis Induced in Rabbits

Objective: The aim of the present study was to examine the efficacy of hyperbaric oxygen (HBO) therapy in the treatment of experimental uveitis induced in rabbits. It was hypothesized that HBO therapy improves the regression of experimental uveitis induced in rabbits. Research design and methods: An experimental animal study was conducted on 48 rabbits (48 right eyes of these rabbits) to evaluate the effects of HBO therapy on endotoxin-induced acute anterior uveitis in rabbits. To induce acute anterior uveitis, Salmonella typhimurium lipopolysaccharide endotoxin (LPS) was intravitreally injected into the right eyes of the rabbits. The animals were randomly assigned to five groups. No treatment was given to the rabbits in Group A. Prednisolone acetate was topically administered to the rabbits in Group B. Methylprednisolone acetate was administered by anterior subtenon injection to the rabbits in Group C four hours after LPS application. HBO therapy was administered to the rabbits in Group D. Both HBO therapy and anterior subtenon injection of methylprednisolone therapy were administered to the rabbits in Group E. To compare the effects of the different therapies on the progression of endotoxin-induced uveitis, examinations including clinical scoring of anterior uveitis, microscopic examination of aspirated aqueous humor for inflammatory responses, and aqueous protein level assessment were performed once a day after LPS injection. Results: There was a statistically significant difference between the control group (Group A) and other groups (Groups B–E) with respect to the number of inflammatory cells and protein levels in the aqueous one and three days after LPS injection (p < 0.05), indicating that the treatments resulted in less inflammation in Groups B–E compared to Group A. Moreover, there was no statistically significant difference between Groups B and C, Groups B and D, Groups B and E, Groups C and D, and Groups C and E with regard to the number of inflammatory cells in the aqueous at Day 1 after LPS injection (p > 0.05). In addition, Groups B and C and Groups B and D were comparable with regard to cell counts at Day 3 (p > 0.05), showing that HBO was comparable to corticosteroids in reducing inflammation. The differences between Groups B and E and Groups C and E were significant with regard to aqueous cell counts at Day 3 (p < 0.05), showing that HBO plus steroid was more effective than steroids alone. Conclusion: The intensity of ocular inflammation in the group receiving HBO therapy combined with anterior subtenon injection of methylprednisolone therapy was lower than in the other groups. We also demonstrated that HBO therapy was an effective therapeutic modality for the treatment of experimental uveitis induced in rabbits with an efficacy comparable to that of corticosteroids. Moreover, HBO plus steroid was superior to steroids alone in reducing 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 TNFα, IL-1 and IL-8 was studied. Anti-TNFαmAb alone did not inhibit the 24 hr LPS induced GRO levels, whereas rrIL-1Ra inhibited the GRO production by 58%. The combination of anti-TNFα 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 TNFα and IL-1. GRO and IL-8 act in concert to mediate neutrophil infiltration.

Blood Flow Velocity in the Central Retinal Artery of Exotoxin-Induced Uveitis in Rabbits

Purpose: Exotoxin-induced uveitis in rabbit eyes was established by intravitreal inoculation of staphylococcal enterotoxin B (SEB). Association between findings of pulsed Doppler assessments and histological features were evaluated. Materials and Methods: Eyes of rabbits were unilaterally inoculated with 50 ng/kg of intravitreal SEB. Pupil diameter, blood flow velocity in the central retinal artery in both eyes and heart rate were measured using an ultrasonic diagnostic apparatus after inoculation. Results: The pupil diameter and the mean blood flow velocity in central retinal arteries decreased and reached a trough 3–5 hours after the inoculation, then increased. Pulsatility index showed reciprocal fluctuations. Histological features at the early phase after inoculation revealed lymphocytic, plasmacytic, and polynuclear leukocytic infiltrations around the anterior chamber, limbal conjunctivae, ciliary body, and nerve fiber layer of the retina, followed by recovery after about 5 days. At the late phase, recurrent inflammations in the ciliary body and intravitreal space were observed in addition to invasion into the rod and cone layer. Conclusion: Early and late phase uveitis was established by intravitreal SEB. It is considered that the uveitis may be caused by two different regulatory mechanisms.

Effect of Propolis on Endotoxin-Induced Uveitis in Rabbits

Purpose: To test the anti-inflammatory effect of propolis, a natural bee-produced compound, and compare it with corticosteroids for the treatment of endotoxin-induced uveitis (EIU). Methods: EIU was produced in all rabbits by unilateral intravitreal injection of 2,000 ng Salmonella typhimurium endotoxin. The animals were then divided randomly into three groups as follows: group A received no treatment (control); group B received methylprednisolone (5 mg/0.1 mL) (positive control); and group C received propolis (5 mg/0.16 mL) by anterior sub-Tenon injection at the time of uveitis induction and at 4 and 8 hours after induction. Inflammation was evaluated by clinical manifestations and by measuring the protein concentration and inflammatory cell content of the aqueous humor. Results: The clinical grade, cell count, and protein levels in the aqueous humor were: control group (6.0 ± 0.8, 2,519 ± 470 cells/μL, 32.9 ± 2.4 mg/mL); methylprednisolone group (1.8 ± 0.7, 572 ± 137 cells/μL, 15.2 ± 1.8 mg/mL); and propolis group (2.3 ± 0.5, 503 ± 124 cells/μL, 13.8 ± 1.5 mg/mL). Statistically significant differences were recorded in the treatment groups when compared to the control group ( P < .001). The effects of methylprednisolone and propolis on EIU were similar ( P > .05). Conclusions: Propolis showed significant anti-inflammatory effects on EIU in rabbits. The mechanism of its action warrants further investigation.

Role and Regulation of IL-8 and MCP-1 in LPS-induced Uveitis in Rabbits

Intravitreal injection of lipopolysaccharide (LPS) induces leukocyte infiltration and protein leakage into the aqueous humor. In the present study, we investigated the role of IL-8 and MCP-1 and regulation of these chemokines by TNFα and IL-1 in LPS-induced uveitis in rabbits. After intravitreal injection of LPS, generation of IL-8 in the aqueous humor showed a biphasic pattern with the first peak at 12 hr and the second one at 24 hr, while MCP-1 was produced in a monophasic pattern and peaked at 24 hr. Immunohistochemistry showed that ciliary epithelial cells and infiltrating leukocytes were the producing cells of IL-8 and MCP-1. Administration of anti-IL-8 IgG suppressed by 66% the peak levels of LPS-induced aqueous neutrophil counts at 24 hr but did not suppress aqueous mononuclear cell counts or protein levels. anti-MCP-1 IgG inhibited aqueous mononuclear cell counts by 41% and protein levels by 28%, but did not inhibit aqueous neutrophil counts.The levels of LPS-induced aqueous IL-8 and MCP-1 at 12 hr were inhibited by anti-TNFα mAb but not by an IL-1 receptor antagonist (IL-1Ra), while concentrations of the two chemokines at 24 hr were inhibited by both anti-TNFα mAb and IL-1Ra. A combination of anti-TNFα mAb and rrIL-1Ra had an additive effect on the 24 hr-chemokine levels and inhibited up to 90% chemokine production.Taken together, our results show that IL-8 mediates neutrophil infiltration, while MCP-1 mediates mononuclear cell infiltration and protein leakage in LPS-induced uveitis in rabbits. Levels of aqueous IL-8 and MCP-1 at 12 hr are regulated by TNFα, while levels at 24 hr are regulated by TNFα and IL-1.

Involvement of TNF α, IL-1β and IL-1 Receptor Antagonist in LPS-induced Rabbit Uveitis

The objective of the study was to investigate involvement of TNFα, IL-1β 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 TNFα (230±37 pg ml-1, at 9 hr) and IL-1β (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 (12239±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 TNFα, IL-1β and IL-1Ra. Intravitreal injection of homologous TNFα (0.1–1.5 μg) or IL-1β (0.5–5 ng) reproduced a rapid leukocyte infiltration and protein leakage. Administration of anti-TNFα mAb (10 μg) 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 μg) 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 TNFα and IL-1β are the principal mediators of LPS-induced uveitis. Our observations also suggest that endogenous IL-1Ra may down-regulate inflammatory reactions.

Additive effect of nitric oxide and prostaglandin-E2 synthesis inhibitors in endotoxin-induced uveitis in the rabbit

The involvement of nitric oxide (NO) and prostaglandin E2 (PGE2) was investigated in a model of intraocular inflammation induced by intravitreal injection of endotoxin (lipopolysaccharide, LPS, 10 ng) in rabbits. The severity of uveitis, the myeloperoxidase (MPO) activity in iris-ciliary body, and the protein concentration in aqueous humor were determined. Nitric oxide synthase (NOS) and cyclooxygenase (COX) activities were assessed respectively by nitrite and PGE2 levels in aqueous humor. Treatment with inhibitors of NOS (NG-nitro-L-arginine methyl ester, L-NAME, 50 mg/kp i.p.) or COX (diclofenac, 30 micrograms, topically), alone or in combination, were compared to a saline-treated group. Diclofenac or L-NAME alone reduced or delayed the intensity of uveitis, and partially decreased the protein concentration in aqueous humor; diclofenac, but not L-NAME, partially reduced the polymorphonuclear leukocyte infiltration in the iris ciliary body as indicated by the MPO activity. Treatment with both inhibitors in combination diminished the clinical uveitis, the disruption of the blood-aqueous barrier and the MPO activity in the iris-ciliary body. We conclude that NO and PGE2 have additive effects in endotoxin-induced uveitis in rabbits, and that the inhibition of both pathways would improve the therapeutical management of uveitis.