Etanercept treatment in the endotoxin-induced uveitis of rats

This study was conducted to investigate therapeutic value of a soluble tumor necrosis factor-alpha (TNF-alpha) receptor, etanercept, in a rat model of endotoxin-induced uveitis (EIU). Forty-two inbred male Lewis rats were divided into seven equal groups. 200 microg of Escherichia coli 055:B55 lipopolysaccharide (LPS) was injected in one hind footpad of the Groups 2, 3, 4, 5, 6, and 7 rats. Group 5, 6, and 7 rats also received subcutaneous etanercept 24 hr prior to LPS injection at a dose of 0.4 mg kg(-1). Group 1 rats were used as controls. Eight, 24, and 48 hr after treatment clinical uveitis scores (miosis, iris hyperemia, and hypopyon) were assessed by a masked observer and the rats were euthanized. Neutrophil leukocytes, CD8+, CD4+, and CD45RO+ cells in the anterior uveal tissue were counted either after hematoxylin-eosin or monoclonal antibody staining. TNF-alpha levels were also measured in the aqueous humor samples by an ELISA method. Etanercept treatment significantly improved clinical uveitis scores at all examination points compared to the LPS injected animals. The improvement was almost complete expect for the miosis score, since no significant difference was detected between the controls and LPS + Etanercept treated animals at all examination points. Cell counts were also at significantly lower levels in LPS + Etanercept treated animals at all examination points, except for CD8+ and CD45RO+ cell counts at 24 hr examination point. There was no significant difference between the controls and LPS + Etanercept treated animals at all examination points as with CD4+ and CD45RO+ cell counts at 48 hr. Our data showed that etanercept had a definite effect on the treatment of EIU. Further studies should clarify its efficacy on clinical uveitis conditions.     

内因性葡萄膜炎患者的T淋巴细胞亚群改变

目的 旨在了解内因性葡萄膜炎患者的外周血Ｔ淋巴细胞亚群改变。方法 应用碱性磷酸酶抗碱性磷酸酶法（ＡＰＡＡＰ法）检测４５例内因性葡萄膜炎患者的外周血Ｔ淋巴细胞亚群,同期收集３２例健康对照者的外周血作为对照。结果 ４５例葡萄膜炎患者葡萄膜炎患者外周血ＣＤ３＋、ＣＤ８＋细胞数目下降,ＣＤ４＋升高,ＣＤ４＋／ＣＤ８＋比值升高。不同类型的葡萄膜炎患者的Ｔ淋巴细胞亚群数目改变不明显。经局部和／或全身皮质类固醇药物治疗后,部分患者的Ｔ淋巴细胞亚群数目有轻度改变。结论 葡萄膜炎患者体内免疫功能异常,这也为免疫治疗的观察提供了一定依据。     

The effect of thalidomide and supidimide on endotoxin-induced uveitis in rats

Background: Endotoxin-induced uveitis (EIU) is an animal model of ocular inflammation, produced by footpad injection of endotoxin (lipopolysaccharide, LPS) to mimic the human disease of acute anterior uveitis, that is useful for testing new anti-inflammatory therapy. The purpose of this study was to test the anti-inflammatory effect on EIU of thalidomide and one of its derivatives, supidimide. Methods: EIU was produced in rats by hind footpad injection of LPS (100 g/animal). Animals were killed 20 h after LPS injection. Inflammation was evaluated by anterior chamber determination of proteins and cells. Results: A dosage of 400 mg/kg per day of thalidomide was efficient in reducing inflammation whether given in three doses (at – 24 h, – 4 h and + 4 h relative to LPS challenge = THAL-1; p < 0.001 for proteins and cells), in two doses (–4 h and +4 h = THAL-2; p < 0.001 for proteins, p < 0.012 for cells) or in one dose (at +4 h=late THAL; p < 0.001 for proteins, p0.02 for cells). A dosage of 300 mg/kg per day of thalidomide was still efficient (p0.023 for proteins, p0.06 for cells), but 150 mg/kg per day had no effect on inflammation. Supidimide (400 mg/kg per day) had some anti-inflammatory effect (p 0.053 for proteins, p < 0.06 for cells). Conclusion: High-dose thalidomide had a potent anti-inflammatory effect in EIU, but lower doses were not sufficient to reduce inflammation. At similar high doses, supidimide had some effect on EIU but was less effective than thalidomide.These data were presented in part at the first annual ECORA meeting, 4–6 October, 1993, Bonn, Germany     

Recurrent intraocular inflammation in endotoxin-induced uveitis

PURPOSE: Endotoxin-induced uveitis (EIU) in rats and mice peaks 24 hours after endotoxin injection and is commonly assumed to be a monophasic disease. This study examined intraocular inflammation at later time points to determine whether endotoxin injection can induce recurrent intraocular inflammation in strains of mice with high or moderate levels of susceptibility to EIU. METHODS: EIU was elicited in two mouse strains with high (C3H/HeN) and moderate (FVB/N) susceptibility, by means of intraperitoneal injections of Salmonella typhimurium endotoxin. Inflammatory cells in the anterior and posterior segments of the eye were counted by a masked observer on histologic sections of eyes from 1 to 17 days after endotoxin injection. RESULTS: A bimodal distribution of inflammatory cell infiltration was noted in eyes from C3H/HeN mice. As previously reported, inflammation peaked at 24 hours after endotoxin injection. However, a second, more pronounced peak of intraocular inflammation occurred approximately 5 days after endotoxin injection. FVB/N mice had a single peak of intraocular inflammation 4 days after injection. CONCLUSIONS: Endotoxin injection in C3H/HeN elicits recurrent intraocular inflammation. The previously unrecognized second peak of inflammation is more severe than the initial inflammatory disease. Studies on this second inflammatory peak may be useful in determining the pathogenesis of recurrent uveitis in humans.     

运用流式细胞计测定急性前部葡萄膜炎患者外周血中T淋巴细胞亚群

目的探讨急性前部葡萄膜炎的发病机制。方法运用流式细胞计检测了28名急性前部葡萄膜炎患者（28只眼）外周血中CD3^＋，CD4^＋和CD8^＋淋巴细胞的水平，并与正常对照值进行了比较。结果28名急性前部葡萄膜炎患者外周血中CD3^＋淋巴细胞平均值为68．32％，CD4^＋细胞的平均值为34．19％，CD4＋／CD8^＋的平均值为1．68，其含量与对照组相比差异无显著性；而CD8^＋细胞的平均值为20．37％，其含量明显低于对照组（P〈0．01）。结论急性前部葡萄膜炎患者体内免疫系统的平衡受到损害。     

The effect of chlorpromazine on endotoxin-induced uveitis in the Lewis rat.

Chlorpromazine (CPZ) has been used extensively in the treatment of psychiatric disorders, and has recently been shown to possess systemic anti-inflammatory properties as well. To investigate the potential effects of CPZ on ocular inflammation, we evaluated its action on endotoxin-induced uveitis (EIU) in Lewis rats. At three different dosage levels, CPZ produced highly significant reductions in the mean aqueous aspirate inflammatory cell counts and histological inflammatory scores as compared to controls treated with vehicle only. Analysis of aqueous fluid demonstrated a similar decrease in protein concentration and phospholipase A2 (PLA-2) activity in the treated animals. The ability of CPZ to inhibit the development of EIU may be related to its properties as a calcium channel blocker and inhibitor of the enzyme phospholipase A2.     

Analysis of interleukin-6 in endotoxin-induced uveitis

The mechanisms underlying the induction of intraocular inflammation in the rat model of endotoxin-induced uveitis (EIU) and the subsequent development of tolerance after repeated endotoxin injections are poorly understood. Interleukin-6 (IL-6) was measured in the aqueous humor and serum of Lewis rats after single and repeated injections of endotoxin into the footpad. After a single injection, a rise in serum and aqueous-humor levels of IL-6 was seen after 2 and 16 hr, respectively. The highest aqueous-humor level of IL-6 was seen 20 hr postinjection and was tenfold that seen in the serum sample taken at the same time, suggesting intraocular synthesis of this cytokine. Four hours later the most active uveitis and the highest total aqueous-humor protein level were observed. Repeated injection of endotoxin still resulted in a moderate but significant systemic release of IL-6 but no detectable IL-6 in the aqueous humor and the absence of uveitis. Intravitreal injection of endotoxin-free human recombinant IL-6 (10-10(5) U) in rats resulted in uveitis, resembling the ocular response to endotoxin. There appeared to be a prozone effect regarding the total aqueous-humor protein concentration. The largest amount of aqueous-humor protein was seen in the eyes injected with 10(2) U of IL-6, but increasing concentrations of intravitreal IL-6 showed a corresponding decrease in protein levels. In the fellow saline-injected eyes, a clear consensual response was observed with regard to the extravasation of protein, although the uveitic grade in these eyes was low or zero. Repeated intravitreal injection of IL-6 resulted in ocular unresponsiveness in nine of 11 rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Thalidomide inhibits leukocyte-endothelium interaction in endotoxin-induced uveitis

To investigate the effects of thalidomide on leukocyte-endothelium interaction in iris vessels of rats with an endotoxin-induced uveitis (EIU), intravital fluorescence microscopy was used to quantify leukocyte adhesion to the vascular endothelium of iris venules in Lewis rats at 2, 4, 8 and 24 h after induction of EIU. Animals (n = 84) received a single intraperitoneal dose of either thalidomide (80 mg/kg body weight) or prednisolone (10 mg/kg body weight). Both drugs significantly reduced firm adhesion of leukocytes at 4, 8 and 24 h. Thalidomide caused earlier suppression of leukocyte rolling than prednisolone (4 vs. 8 h). TNF-alpha plasma levels peaked at 2 h and were not significantly reduced in any group compared with controls. Cell count and protein concentration in aqueous humor were significantly reduced by prednisolone and thalidomide at 24 h (p < 0.05). Thalidomide exerts its anti-inflammatory effects by an inhibition of leukocyte-endothelium interaction. Compared with prednisolone, thalidomide shows earlier inhibition of leukocyte rolling, indicating modulation of adhesion molecule expression and/or function.     

Anti-inflammatory effect of angiotensin type 1 receptor antagonist on endotoxin-induced uveitis in rats

Background Angiotensin II type 1 (AT1) receptor-antagonists are widely used for treatment of hypertension. Recent studies have demonstrated a protective effect of renin angiotensin system (RAS) antagonism against immune-mediated inflammatory diseases such as myocarditis, chronic allograft rejection, antiglomerular basement membrane nephritis, colitis, and arthritis. However, only a few reports have demonstrated the effect of RAS in ocular inflammatory conditions. The purpose of this study was to investigate the anti-inflammatory effect of a selective AT1 receptor antagonist, losartan, on endotoxin-induced uveitis (EIU) and compare the effect on experimental autoimmune uveoretinitis (EAU). Methods To induce EIU, 7-week-old Lewis rats were injected subcutaneously with 200 μg lipopolysaccharide (LPS). Losartan was administered intravenously at the same time. The aqueous humor was collected from eyes 24 h after LPS injection. The number of infiltrating cells, protein concentration, and levels of tumor necrosis factor (TNF)-α and monocyte chemoattractant protein-1 (MCP-1) in the aqueous humor were determined. The collected eyes were immunohistochemically stained with monoclonal antibody for activated nuclear factor (NF)-κB. To induce EAU, C57BL/6 mice (6–8 weeks old) were immunized with human interphotoreceptor retinoid binding protein (hIRBP)-derived peptide emulsified in complete Freund’s adjuvant (CFA) and concomitantly injected with purified Bordetella pertussis toxin (PTX). Clinical severity of EAU and T cell proliferative response were analyzed. Results Losartan significantly suppressed the development of EIU. Numbers of aqueous cells of control EIU rats, those from EIU rats treated with 1 or 10 mg/kg of losratan were 75.3 ± 45.6 × 10⁵, 27.9 ± 8.1 × 10⁵, or 41.3 ± 30.9 × 10⁵ cells/ml respectively (p < 0.01 vs control). Aqueous protein, TNF-α, and MCP-1 levels were also significantly decreased in a manner dependent on the amount of losartan administered (p < 0.01). Treatment of EIU rats with losartan suppressed activation of NF-κB at the iris ciliary body. Thus, the suppressive effect of losartan on ocular inflammation in EIU appeared to result from down-regulation of NF-κB activation and reduction of inflammatory cytokine production. On the other hand, in the EAU model, neither the clinical score nor the antigen-specific T cell proliferative response was significantly influenced by the treatment with losartan. Conclusions The present findings indicate that RAS may be involved in the acute inflammation of the eye, but not in T cell-dependent ocular autoimmunity. Antagonism of the RAS may be a potential prophylactic strategy for treatment of the human acute ocular inflammation.     

Immunopharmacological analysis of endotoxin-induced uveitis in the rat

Footpad injection of endotoxin causes exclusive ocular inflammation in the rat. In order to clarify its physiopathologic mechanism, we studied the effect of different treatments on endotoxin-induced uveitis (EIU). Salmonella endotoxin was injected into the footpads of Lewis rats. 18 hr later, inflammation was assessed by evaluating proteins and cells in the anterior chamber; arachidonic acid (AA) metabolites, prostaglandin E2 and leukotriene B4, as well as substance P were measured by radioimmunoassay, and Ia-(MHC class II)-antigen expression in ciliary body was assessed by immunohistochemistry. The effect of inhibitors of phospholipase A2 (EPC), of lipoxygenase (azelastine) and of cyclo-oxygenase (diclofenac), as well as dexamethasone, cyclosporine (CsA) and anti-Ia antibody, were evaluated on these parameters. Phospholipase A2 inhibitor EPC and dexamethasone were most effective on inflammation: they also reduced AA metabolites very effectively and prevented Ia-expression. Lipoxygenase and cyclo-oxygenase inhibitors were partially effective on inflammation and on AA metabolites but failed to prevent Ia-expression. Immunosuppressive treatments (CsA and anti-Ia-antibody) also reduced inflammation. Our findings suggest that inflammation mediators initiate inflammation in EIU. Ia-Ag-expression is secondarily produced by mediators leading to additional inflammation due to immune mediated mechanisms.     

Captopril suppresses inflammation in endotoxin-induced uveitis in rats

Captopril is an inhibitor of angiotensin-converting enzyme (ACE) that is largely used in the treatment of cardiovascular diseases. Several previous studies have demonstrated that captopril exhibits a wide variety of biological activities, including an anti-inflammatory action, on which we focused our attention. The aim of the present study was to investigate the efficacy of captopril on endotoxin induced uveitis (EIU) in rats. We investigated its effect upon cellular infiltration and protein leakage, as well as on the concentration of tumor necrosis factor-alpha (TNF-alpha), nitric oxide (NO), prostaglandin E2 (PGE2), monocyte chemoattractant protein-1 (MCP-1) in the anterior chamber. In addition, we checked its effect on activation of nuclear factor kappa B (NF-kappaB) in iris and ciliary body (ICB) cells in vivo. EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). One hour after the LPS inoculation, either 1mg/kg, 10mg/kg or 100mg/kg captopril were injected intravenously. 24h later, the aqueous humor was collected from both eyes, and the number of infiltrating cells and protein concentration in the aqueous humor were determined. Levels of TNF-alpha, PGE2, NO and MCP-1 were determined by enzyme-linked immunosorbent assay. On some eyes, after enucleation, immunohistochemical staining with a monoclonal antibody against activated NF-kappaB was performed. Captopril treatment significantly decreased the inflammatory cells infiltration, the level of protein, concentrations of TNF-alpha, PGE2, NO and MCP-1 in the aqueous humor. The number of activated NF-kappaB-positive cells was lower in ICB of the rats treated with captopril 3h after the LPS injection. The present results indicate that captopril suppresses the inflammation in EIU by inhibiting the NF-kappaB-dependent pathway and the subsequent production of pro-inflammatory mediators.     

内毒素诱导的葡萄膜炎发病机制的研究进展

葡萄膜炎是常见眼病,也是主要致盲原因之一.其发病机制复杂,目前尚未完全明确.内毒素诱导的葡萄膜炎动物模型,为了解葡萄膜炎的确切发病机制及开拓新的防治措施奠定了重要的实验基础.内毒素介导炎症性细胞的激活和组织损伤,Toll样受体4是内毒素脂多糖识别和细胞激活的初级信号受体,其信号转导通路的活化在内毒素诱导的葡萄膜炎发病中起关键作用,并最终导致相关炎症性细胞因子的活化及眼前节炎症病理反应.本文就内毒素诱导的葡萄膜炎模型的建立、病理特点、炎症发生及阻断机制等的研究状况进行综述,以期对人类葡萄膜炎的研究提供重要的理论依据.     

Inhibitory effect of aminoimidazole carboxamide ribonucleotide (AICAR) on endotoxin-induced uveitis in rats

PURPOSE. To investigate the anti-inflammatory effect of aminoimidazole carboxamide ribonucleotide (AICAR), an analog of adenosine monophosphate (AMP), in endotoxin-induced uveitis (EIU). METHODS. EIU was induced by subcutaneous injection of lipopolysaccharide (LPS) (200 μg) in Lewis rats. AICAR (50 mg/kg, intraperitoneally) was given 6 hours prior and at the same time as LPS injection. Clinical uveitis scores, number of anterior chamber (AC) infiltrating cells, anterior chamber protein concentration, retinal vessel leukocyte adhesion, and protein leakage were measured 24 hours later. Protein levels of C-C chemokine ligand-2 (CCL-2)/monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-α (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) in aqueous humor and retina and nuclear translocation of nuclear factor-κB (NF-κB) in the retina were determined by enzyme-linked immunosorbent assay (ELISA). Both mRNA and protein levels of CD14 in peripheral blood mononuclear cells were also measured. RESULTS. AICAR treatment significantly reduced EIU clinical severity as well as inflammatory cell infiltration and protein concentration in aqueous humor. Similarly, the number of retinal vessel-adherent leukocytes and protein leakage were decreased by AICAR treatment. Protein levels of TNF-α, CCL-2/MCP-1, and ICAM-1 in aqueous humor and CCL-2/MCP-1 and ICAM-1 levels in retina were suppressed with AICAR treatment. AICAR also reduced NF-κB translocation and CD14 expression. CONCLUSIONS. AICAR reduces systemic LPS susceptibility and attenuates intraocular inflammation in a rat EIU model by limiting infiltration of leukocytes, suppressing inflammatory mediators, and inhibiting the NF-κB pathway.     

A cholinergic agonist attenuates endotoxin-induced uveitis in rats

PURPOSE: Investigation of physiological anti-inflammatory mechanisms can contribute to the treatment of inflammatory disorders. The purpose of the present study was to investigate the effect of nicotine, a selective cholinergic agonist, on endotoxin-induced uveitis (EIU) in rats and the underlying molecular mechanism. METHODS: Lipopolysaccharide (LPS; endotoxin) and nicotine were injected intraperitoneally. Clinical scores were evaluated by slit lamp. Intracameral protein content and the number of cells were determined. Immunohistochemical reactivity of alpha7 nicotine acetylcholine receptor (alpha7nAChR) was examined in the iris and ciliary body (ICB). mRNA and protein levels of cytokines and chemokines were measured by real-time PCR and enzyme-linked immunosorbent assay. RESULTS: After LPS injection, clinical scores, as well as protein content and number of cells in the aqueous humor increased during 18 to 36 hours. Nicotine inhibited the endotoxin-induced elevation of these levels. mRNA and protein of alpha7nAChR expression levels were significantly increased by LPS and/or nicotine injection. Nicotine showed no effects on endotoxin-induced elevation of mRNA levels in ICB. However, nicotine decreased the endotoxin-induced elevation of interleukin (IL)-6, IL-1beta, tumor necrosis factor (TNF)-alpha, cytokine-induced neutrophil chemoattractant (CINC)-1, and monocyte chemotactic protein (MCP)-1, but did not affect IL-10 in the serum and aqueous humor. CONCLUSIONS: Nicotine attenuated endotoxin-induced uveitis through directly decreasing the levels of multiple cytokines and chemokines in the aqueous humor, but did not affect the mRNA levels of these factors. The findings suggest that the nicotinic anti-inflammatory pathway may be involved in the pathogenesis of EIU.     

Aldose reductase inhibition prevents endotoxin-induced uveitis in rats

PURPOSE: The purpose of the present study was to elucidate the role of the polyol pathway enzyme aldose reductase (AR) in the mediation of ocular inflammation in a rat model of endotoxin-induced uveitis (EIU). METHODS: EIU was induced by a subcutaneous injection of 200 microg lipopolysaccharide (LPS) in male Lewis rats treated with the AR inhibitor, zopolrestat (25 mg/kg body weight, intraperitoneally) or its carrier. The rats were killed 24 hours after LPS injection, the eyes were enucleated immediately, and aqueous humor (AqH) was collected. The number of infiltrating cells, protein concentration, and levels of nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and prostaglandin E(2) (PGE(2)) in the AqH were determined. Immunohistochemical analysis was performed in paraformaldehyde-fixed eye sections by staining with antibodies against iNOS, COX-2, TNF-alpha, NF-kappaB, and AR. The levels of reactive oxygen species (ROS) in rat eye sections were determined by dihydroethidium (hydroethidine) fluorescence staining. RESULTS: In the EIU rat eye AqH, both the number of infiltrating cells and protein concentrations of the inflammatory markers, TNF-alpha, NO, and PGE(2) were significantly higher than in the control rats, and inhibition of AR by zopolrestat suppressed the LPS-induced increases. The LPS-induced increased expression of AR, TNF-alpha, iNOS, and COX-2 proteins in the ciliary body, corneal epithelium, and retinal wall was also significantly inhibited by zopolrestat. Furthermore, AR inhibition prevented the LPS-induced increased levels of ROS and activation of NF-kappaB in the ciliary body, corneal epithelium, and retinal wall of the rat eye. AR inhibition also prevented the LPS-induced activation of NF-kappaB and expression of COX-2 and iNOS in the human monocyte cell line U-937. CONCLUSIONS: The results indicate that AR inhibition suppresses the inflammation in EIU by blocking the expression and release of inflammatory markers in ocular tissues, along with the attenuation of NF-kappaB activation. This finding suggests that AR inhibition could be a novel therapeutic target for the treatment of uveitis and associated ocular inflammation.