Role and regulation of IL-8 and MCP-1 in LPS-induced uveitis in rabbits

Role of CD4+ T cell-derived cytokines in the pathogenesis of uveitis

Uveitis refers to a diverse group of inflammatory diseases that affecting the uveal tract, comprising the iris, ciliary body, and choroid, with potential repercussions ranging from visual impairment to blindness. The role of autoimmunity in uveitis etiology is complex and still under investigation. CD4+ T cells intricately regulate immune responses in uveitis through their diverse subtypes: Th1, Th2, Th17, Treg (T regulatory), and Tfh (follicular T helper) cells. Each T cell subtype secretes specific cytokines with either pathogenic or protective implications in uveitis. Th1 cells, characterized by IFN-γ secretion and T-bet expression, drive type 1 immune responses against intracellular pathogens. Conversely, Th2 cells, which produce interleukin (IL)-4, IL-5, and IL-13 and express the transcription factor GATA3, mediate type 2 immune responses to larger extracellular threats like helminths. Th17 cells, generating IL-17 and IL-22 and controlled by RORγt, engage in type 3 immune responses against select pathogens. Tfh cells, releasing IL-21 and governed by Bcl6, aid B cell antibody production. Conversely, Tregs, identified by Foxp3, exert regulatory functions in immune homeostasis. This review delves into the roles of CD4+ T cell-derived cytokines in uveitis, emphasizing their intricate involvement in disease progression and resolution. Insight into these mechanisms might guide therapeutic approaches targeting CD4+ T cell responses in uveitis management.

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

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

Pre-Activated Granulocytes from an Autoimmune Uveitis Model Show Divergent Pathway Activation Profiles upon IL8 Stimulation In Vitro

In the pathophysiology of autoimmune-mediated uveitis, granulocytes have emerged as possible disease mediators and were shown to be pre-activated in equine recurrent uveitis (ERU), a spontaneous disease model. We therefore used granulocytes from ERU horses to identify early molecular mechanisms involved in this dysregulated innate immune response. Primary granulocytes from healthy and ERU horses were stimulated with IL8, and cellular response was analyzed with differential proteomics, which revealed significant differences in protein abundance of 170 proteins in ERU. Subsequent ingenuity pathway analysis identified three activated canonical pathways “PKA signaling”, “PTEN signaling” and “leukocyte extravasation”. Clustered to the leukocyte extravasation pathway, we found the membrane-type GPI-anchored protease MMP25, which was increased in IL8 stimulated ERU granulocytes. These findings point to MMP25 as a possible regulator of granulocyte extravasation in uveitis and a role of this molecule in the impaired integrity of the blood-retina-barrier. In conclusion, our analyses show a clearly divergent reaction profile of pre-activated granulocytes upon IL8 stimulation and provide basic information for further in-depth studies on early granulocyte activation in non-infectious ocular diseases. This may be of interest for the development of new approaches in uveitis diagnostics and therapy. Raw data are available via ProteomeXchange with identifier PXD013648.

Application of Disulfiram and its Metabolites in Treatment of Inflammatory Disorders

Disulfiram has been used clinically for decades as an anti-alcoholic drug. Recently, several studies have demonstrated the anti-inflammatory effects of disulfiram and its metabolism, which can alleviate the progression of inflammation in vivo and in vitro. In the current study, we summarize the anti-inflammatory mechanisms of disulfiram and its metabolism, including inhibition of pyroptosis by either covalently modifying gasdermin D or inactivating nod-like receptor protein 3 inflammasome, dual effects of intracellular reactive oxygen species production, and inhibition of angiogenesis. Furthermore, we review the potential application of disulfiram and its metabolism in treatment of inflammatory disorders, such as inflammatory bowel disease, inflammatory injury of kidney and liver, type 2 diabetes mellitus, sepsis, uveitis, and osteoarthritis.

Research Progress on the Mechanism of Natural Product Ingredients in the Treatment of Uveitis

Background

As the spectrum of ophthalmic diseases keeps changing, uveitis has gradually become one of the major blinding eye diseases in the world. In recent years, it has become a research hotspot to select effective components for uveitis treatment from natural drugs.

Methods

We searched PubMed and EMBASE databases for studies written in English as well as Chinese National Knowledge Infrastructure (CNKI), CQVIP, and Wan Fang database for studies written in Chinese (inception through 30 December 2020).

Results

Eight kinds of natural product ingredients were included in this article. They were found to not only regulate the expression of cytokines, proliferation, and differentiation of T help cells but also inhibit the damage of cytokines and inflammatory cells to uvea, blood aqueous barrier, and blood retinal barrier.

Conclusion

Natural product ingredients have their unique advantages in the treatment of uveitis. They have good anti-inflammatory effects without causing serious adverse reactions, which enables them to be promising choices for preventive and therapeutic strategy of uveitis.

Relationship between the higher inflammatory cytokines level in the aqueous humor of Fuchs uveitis syndrome and the presence of cataract

BACKGROUND

This study aims to compare the levels of intraocular cytokines between Fuchs uveitis syndrome (FUS) eyes and the senile cataract eyes. The association between inflammatory cytokine levels and cataract severity in FUS is evaluated to find the possible mechanism of cataract in FUS eyes.

METHODS

A retrospective study of 28 eyes with FUS was performed. Auxiliary examinations were performed, including ophthalmic examinations, laser flare-cell photometry, and levels of inflammatory cytokines in the aqueous humor were measured. The control group included 25 eyes with senile cataract. Data on the aqueous humor inflammatory cytokines were compared between the two groups. The association between the aqueous humor cytokine levels and severity of posterior subcapsular cataract was assessed.

RESULTS

There were 28 eyes with FUS in 27 patients. Unilateral involvement was noted in 26 patients (96.30%). Stellate keratic precipitates (KPs) were noted in 16 eyes (57.14%). Heterochromia was observed in 21.43% of affected eyes. Posterior subcapsular cataract (PSC) was observed in 16 of the 28 eyes. Eyes with FUS had significantly higher aqueous humor (AH) cytokine levels (VEGF, bFGF, IL-6, IL-8 and IL-10) compared with the control eyes (P < 0.05). There was a statistically significant positive correlation between the severity of cataract and IL-6 and IL-8 levels in the AH (τ = 0.664 and 0.634, respectively; P = 0.001, P = 0.002, respectively).

CONCLUSIONS

Expression of VEGF, bFGF, IL-6, IL-8 and IL-10 in the AH of FUS patients was significantly higher than in senile cataract eyes, and the aqueous humor levels of IL-6 and IL-8 were significantly positively associated with the severity of posterior subcapsular cataract. Our results imply that an inflammation mechanism may be involved in the early development of cataract in FUS.

Evaluation of His6-Metal Assemblies as a Drug Delivery Vehicle in the Treatment of Anterior Segment Disease Using a Corneal Inflammation Model

Keratitis is a common ophthalmological disease and also a common cause of blindness (second only to cataracts). This disease is routinely treated by topical administration of dexamethasone sodium phosphate (Dexp). However, due to the presence of anatomical and physiological barriers, frequent administration is needed, often resulting in poor patient compliance and diverse side effects. In this work, Dexp was in situ encapsulated into a His₆-metal assembly (HmA) to generate Dexp@HmA, which was utilized in the ocular delivery of Dexp. The physicochemical properties of HmA and Dexp@HmA particles were characterized in detail using various techniques such as dynamic light scattering (DLS), scanning electron microscopy (SEM), and UV-vis spectroscopy. Compared to commercial Eudragi and reported PLGA nanoparticles, HmA showed higher encapsulation efficiency (EE%) and higher loading capacity (LC wt %) of Dexp. Dexp@HmA displayed pH-dependent release; after 33 days at pH 5.8, 6.5, and 7.2, 100%, 65%, and 42% of Dexp, respectively, had been released. In addition, HmA and Dexp@HmA showed low cytotoxicity to macrophages and to all common ocular cell types tested. The effect of Dexp@HmA on corneal inflammation was evaluated using in vitro and in vivo models. Our results demonstrate that Dexp@HmA is much superior to free Dexp in both in vitro and in vivo models. These positive results suggest that HmA may represent a promising candidate nanocarrier for the treatment of various diseases of the anterior segment of the eye.

Aqueous cytokine levels in four common uveitis entities

To investigate aqueous cytokine profiles in acute anterior uveitis (AAU), Fuchs' syndrome, Vogt-Koyanagi-Harada (VKH) disease and Behcet's disease (BD), we assayed the concentrations of 17 cytokines by multiplex immunoassay in aqueous humor (AqH) collected during cataract surgery from 24 AAU, 29 Fuchs' syndrome, 29 VKH disease, 30 BD and 30 senile cataract control patients. Aqueous cytokine levels were compared between the five groups and analysed by logistic regression. Cytokine levels were then compared between uveitis patients who underwent cataract surgery within 3 months and those who underwent this surgery more than 3 months after complete control of intraocular inflammation. The results showed that aqueous levels of interferon (IFN)-γ, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1β and tumour necrosis factor (TNF)-α levels in AqH from patients with Fuchs' syndrome were significantly higher than those in the other four groups. Using multivariate analysis, MIP-1β was found to be significantly associated with Fuchs' syndrome. There was no difference in aqueous cytokine levels between cases having cataract surgery within 3 months compared to those after 3 months of complete control of their intraocular inflammation. The current study shows that Chinese patients with Fuchs' syndrome appear to have a specific cytokine profile. MIP-1β is an important chemokine in the intraocular environment of Fuchs' syndrome. Aqueous cytokine profiles support the performance of cataract surgery in uveitis within 3 months after intraocular inflammation control.

[Retinal transcriptome profile in mice following dexamethasone treatment for endotoxin-induced uveitis]

OBJECTIVE

To investigate the changes in retinal transcriptome profile of mice with endotoxin-induced uveitis (EIU)following dexamethasone (DEX) treatment and explore the mechanisms underlying the therapeutic effect of DEX.

METHODS

EIU was induced in BALB/c mice by intravitreal injection of 125 ng lipopolysaccharide (LPS), followed by topical applicationof DEX (0.1%) eye drops every 4 h for 24 h. The anterior chamber inflammation was examined with a slit lamp and the clinicalscores were assessed. The morphological changes in the eyes were assessed at 24 h after LPS injection. The retinas wereharvested for analysis of transcriptome profile using the next-generation sequencing (NGS)-based RNA sequencing (RNA-seq), and the expressions of the inflammatory cytokines and the differentially expressed genes (DEGs) were verified using real-timePCR.

RESULTS

DEX alleviated the inflammatory response and reduced the mRNA expressions of IL-6, TNF- a, MCP-1 andICAM-1 at 24 h after LPS injection. A total of 52 DEGs were identified by RNA-seq. Within these DEGs, 37 genes were upregulated and 15 genes were down-regulated in LPS group as compared with DEX+LPS group. No significantly enriched GeneOntology (GO) terms was noted. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed 6up-regulated and 2 down-regulated KEGG pathways. RIG-I-like receptor signaling pathway and several immune- andinflammation-related genes including Ifit1, H2-T24, Mx2 and Eif2ak2 were significantly down regulated by DEX. Verificationwith RT-PCR yielded results consistent with these findings.

CONCLUSIONS

DEX alleviates LPS-induced inflammatory response inthe retina of mice, and such protective effect is probably mediated by RIG-I like receptor signal pathway and the immune-andinflammation-related genes.

Supramolecular nanofibers of dexamethasone derivatives to form hydrogel for topical ocular drug delivery

The low bioavailability exhibits by conventional ocular formulation owing to rapid precorneal clearance and lower corneal permeability can be overcame by the application of the gelling system. In the present study, a prodrug supramolecular hydrogel derived from succinated dexamethasone (Dex-SA) was fabricated using a pH hydrolytic strategy and explored as a "self-delivery" system for ophthalmic drugs. The self-assembled Dex-SA supramolecular hydrogel exhibited a typical nano-fibrous microstructure and was thixotropic. Both dexamethasone (Dex) and Dex-SA prodrug sustainably released from Dex-SA supramolecular hydrogel in a period of 120 h in vitro release study, and the initial pH value of hydrogel significantly influence on the release ratio of Dex/Dex-SA. Furthermore, the lyophilized Dex-SA supramolecular hydrogel displayed long-term stability without causing any apparent hydrolysis of Dex-SA at -20 °C over 30 day and quickly re-formed a hydrogel after dissolving into aqueous solution. The formed Dex-SA supramolecular hydrogel had lower cytotoxicity than Dex at drug concentration up to 2.5 mM, and exhibited a comparable anti-inflammatory efficacy to a Dex sodium phosphate (Dexp) aqueous solution in lipopolysaccharide-activated RAW264.7 macrophages. Topical instillation of the Dex-SA supramolecular hydrogel showed excellent intraocular biocompatibility and it was not an irritant in rabbit eyes. More importantly, the Dex-SA supramolecular hydrogel provided a prolonged precorneal retention and significantly enhanced the ocular bioavailability over Dexp aqueous solution after topical instillation. Overall, this work illustrates an effective approach for the development of prodrug supramolecular hydrogels to extend the precorneal retention and enhance ocular bioavailability of drugs after topical instillation.

Malondialdehyde and Antioxidant Enzyme Levels in the Aqueous Humor of Rabbits in Endotoxin-Induced Uveitis

PURPOSE

To investigate the role of oxidative stress in endotoxin-induced uveitis.

METHODS

Lipopolysaccharide was injected intravitreally into the right eyes of rabbits. Sterile saline was injected intravitreally into the left eyes as a control. Inflammation was assessed according to clinical score, aqueous humor cell count, and protein levels. Malondialdehyde, superoxide dismutase, glutathione peroxidase, catalase, and nitrite levels were measured in the aqueous humor.

RESULTS

The clinical grade (p < 0.01), inflammatory cell count (p < 0.001), and protein content (p < 0.001) were significantly higher in the aqueous humor of eyes with uveitis than in that of controls. Malondialdehyde (p < 0.01) and nitrite (p < 0.001) levels in the aqueous humor of eyes with uveitis were significantly higher than in the control group. Superoxide dismutase (p < 0.001), glutathione peroxidase (p < 0.001), and catalase (p < 0.001) levels were significantly lower in the aqueous humor of eyes with uveitis than in that of the controls.

CONCLUSIONS

Oxygen free radicals may be implicated as a mediator of inflammation in endotoxin-induced uveitis. The increase in free radicals in the aqueous humor may play a role in the pathogenesis of endotoxin-induced uveitis.

Cytokine and chemokine profiles of aqueous humor and serum in horses with uveitis measured using multiplex bead immunoassay analysis

OBJECTIVE

To determine whether horses with clinically diagnosed Equine Recurrent Uveitis (ERU) and those with Leptospirosis infection have a specific cytokine profile in their aqueous humor (AH) and serum that differs from horses with uveitis secondary to other ocular inflammatory processes and from horses with normal eyes.

ANIMALS STUDIED

Twenty-five client-owned horses with uveitis that were presented to the North Carolina State University Ophthalmology Service, and four University-owned horses without history or clinical signs of ocular disease.

PROCEDURE

Samples of AH and serum were obtained from horses with ERU (n=13), acute or non-recurrent uveitis (UV; n=7), uveitis secondary to infectious keratitis (IK; n=5), and normal eyes (N; n=4). Cytokine levels in AH and serum were quantified using a multiplex bead immunoassay. Leptospiral antibody titers in serum and AH and PCR for Leptospiral DNA in AH were performed.

RESULTS

In the AH of horses with ERU, increased levels of IL-1a, IL-4, IL-6, IL-8, IL-12p70, FGF-2, G-CSF, and RANTES were measured compared to UV, IK and N eyes, but the differences were not significant. However, IL-10 was significantly higher in ERU eyes compared to IK and N (P=0.029; 0.013), and IP-10 in ERU eyes was significantly higher than in UV and N (P=0.004). Furthermore, MCP-1 was significantly higher in ERU than N (P=0.04). In the serum, increased levels of IL-1a, IL-4, IL-6, IL-8, IL-12p70, fractalkine, and G-CSF were measured in horses with ERU, but the levels were not significantly higher than those observed in UV, IK, or N horses. However, serum IP-10 levels in horses with ERU were significantly higher than in UV and N horses (P=0.005) and MCP-1 levels were significantly higher in ERU than N (P=0.03). Horses with marked ocular inflammation had significantly higher serum levels of G-CSF, IL-1a, fractalkine, IL-13, IL-4, IL-17a, IL-12p70, IFN-γ, and MCP-1. Elevated IL-10 in AH was significantly associated with disease chronicity, both overall and in ERU eyes (P=0.049), and in horses with positive ocular leptospiral titers or leptospiral PCR, significant elevations of IL-10 (P=0.0018; 0.0032) and IP-10 (P=0.0342; 0.043) were detected in the AH compared to leptospiral negative eyes.

CONCLUSIONS

The anti-inflammatory cytokine IL-10 and the pro-inflammatory cytokine IP-10 appear to play an important role in ERU. Further studies are needed to further clarify and characterize cytokine profiles of specific ocular inflammatory diseases, but multiplex bead immunoassay technology shows promise as a diagnostically valuable tool.

Effects of Lutein and Zeaxanthin on LPS-Induced Secretion of IL-8 by Uveal Melanocytes and Relevant Signal Pathways

The effects of lutein and zeaxanthin on lipopolysaccharide- (LPS-) induced secretion of IL-8 by uveal melanocytes (UM) were tested in cultured human UM. MTT assay revealed that LPS (0.01-1 μg/mL) and lutein and zeaxanthin (1-10 μM) did not influence the cell viability of cultured UM. LPS caused a dose-dependent increase of secretion of IL-8 by cultured UM. Lutein and zeaxanthin did not affect the constitutive secretion of IL-8. However, lutein and zeaxanthin decreased LPS-induced secretion of IL-8 in cultured UM in a dose-dependent manner. LPS significantly increased NF-κB levels in cell nuclear extracts and p-JNK levels in the cell lysates from UM, but not p-p38 MAPK and p-ERG. Lutein or zeaxanthin significantly reduced LPS-induced increase of NF-κB and p-JNK levels, but not p38 MAPK and ERG levels. The present study demonstrated that lutein and zeaxanthin inhibited LPS-induced secretion of IL-8 in cultured UM via JNK and NF-κB signal pathways. The anti-inflammatory effects of lutein and zeaxanthin might be explored as a therapeutic approach in the management of uveitis and other inflammatory diseases of the eye.

Constitutive and LPS-induced expression of MCP-1 and IL-8 by human uveal melanocytes in vitro and relevant signal pathways

PURPOSE

Melanocytes are one of the major cellular components in the uvea. Interleukin-8/CXCL8 and monocyte chemoattractant protein-1 (MCP-1/CCL2) are the two most important proinflammatory chemokines. We studied the constitutive and lipopolysaccharide (LPS)-induced expression of IL-8 and MCP-1 in cultured human uveal melanocytes (UM) and explored the relevant signal pathways.

METHODS

Conditioned media and cells were collected from UM cultured in medium with and without stimulation of LPS. Interleukin-8 and MCP-1 proteins and mRNAs were measured using an ELISA kit and RT-PCR, respectively. Nuclear factor (NF)-κB in nuclear extracts and phosphorylated p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases1/2 (ERK1/2), and c-Jun N-terminal kinase1/2 (JNK1/2) in cells cultured with and without LPS were measured by ELISA kits. Inhibitors of p38 (SB203580), ERK1/2 (UO1026), JNK1/2 (SP600125), and NF-κB (BAY11-7082) were added to the cultures to evaluate their effects.

RESULTS

Low levels of IL-8 and MCP-1 proteins were detected in the conditioned media in UM cultured without serum. Lipopolysaccharide (0.01-1 μg/mL) increased IL-8 and MCP-1 mRNAs and proteins levels in a dose- and time-dependent manner, accompanied by a significant increase of phosphorylated JNK1/2 in cell lysates and NF-κB in nuclear extracts. Nuclear factor-κB and JNK1/2 inhibitors significantly blocked LPS-induced expression of IL-8 and MCP-1.

CONCLUSIONS

This is the first report on the expression and secretion of chemokines by UM. The data suggest that UM may play a role in the pathogenesis of ocular inflammatory diseases.

Angiopoietin-like protein 2 mediates endotoxin-induced acute inflammation in the eye

Angiopoietin-like protein (Angptl) 2 is a key mediator linking obesity to chronic adipose-tissue inflammation and systemic insulin resistance, and increasing evidence has shown that Angptl2 is associated with various chronic inflammatory diseases such as cancer and dermatomyositis; however, it remains unclear that Angptl2 functions in acute inflammation. In this study, we investigate whether Angptl2 has a role in acute inflammation in the eye with endotoxin-induced uveitis (EIU). Angptl2 was widely expressed in the normal mouse retina, while Angptl2⁻/⁻ mice did not exhibit any changes in retinal cell marker expression and morphological analyses. Treatment with lipopolysaccharide (LPS) stimulated retinal Angptl2 mRNA expression in vivo and in vitro. We generated EIU in wild-type (C57BL/6) and Angptl2⁻/⁻ mice by injecting LPS intraperitoneally. Compared with wild-type animals, Angptl2⁻/⁻ mice significantly reduced various EIU-associated cellular and molecular parameters including leukocyte adhesion to the retinal vessels and infiltration into the vitreous cavity and retinal mRNA expression levels of monocyte chemotactic protein-1, intercellular adhesion molecule-1, interleukin (IL)-6, and tumor necrosis factor (TNF)-α, together with nuclear translocation of nuclear factor (NF)-κB p65 subunit. In vitro, antibody-based inhibition of α5β1 integrin, a receptor for Angptl2, significantly repressed LPS-induced expression of IL-6 and TNF-α, both of which are the major inflammatory cytokines derived from macrophages. The present findings indicate that Angptl2 mediates endotoxin-induced retinal inflammation through the activation of NF-κB signaling pathway and suggest a potential validity of Angptl2 as a new molecular target for the treatment of acute inflammation.

Native X-DING-CD4 protein secreted by HIV-1 resistant CD4+ T cells blocks activity of IL-8 promoter in human endothelial cells infected with enteric bacteria

Onsets of bacterial infections devastate the compromised immune system in AIDS patients. Damaged gut mucosa permits dissemination of bacterial toxins into deeper layers and hyper-activation of the immune system. We previously reported that the unfractionated supernatants of HIV-resistant CD4(+) T cells impeded the NF-κB/DNA binding in macrophages induced by either HIV-1 or LPS. The active component of this soluble material was identified as X-DING-CD4 (extracellular DING from CD4 T cells). We hypothesized that the anti-inflammatory effect of the X-DING-CD4 protein might extend to non-immune cells, for example endothelial cells, undergoing persistent endotoxin stimulation in the course of advanced HIV disease. To test this proposition, we evaluated the efficiency of NF-κB and Ap-1 binding to the IL-8 promoter in LPS-activated endothelial cells and control human macrophages exposed to native X-DING-CD4 protein. We found a deficiency of NF-κB- but not AP-1-DNA binding in the systems where cells were treated with native soluble X-DING-CD4 protein. The X-DING-CD4-mediated inhibition of the IL-8 promoter also resulted in a reduction of the soluble IL-8 protein in endothelial cells and human macrophages infected with a subset of enteric bacteria frequently causing diarrhea in progressive HIV disease. Bacterial endotoxin did not induce the endogenous X-DING-CD4 mRNA activity in human macrophages and transformed CD4(+)T cells, indicating that the reduction of LPS-mediated IL-8 promoter activation was not related to de novo X-DING-CD4 protein synthesis, but depended on function of the exogenous X-DING-CD4 protein. This study provides evidence that the X-DING-CD4 protein might be developed as a novel biotherapeutic to control LPS-mediated inflammation in advanced HIV disease.

Effects of a novel peptide derived from human thrombomodulin on endotoxin-induced uveitis in vitro and in vivo

Thrombomodulin (TM) is a single-transmembrane glycoprotein receptor for thrombin, which is best known as a cofactor for thrombin-mediated activation of anticoagulant protein C. C-type lectin-like domain (CTLD) of TM has distinct coagulation/fibrinolysis-independent anti-inflammatory properties. Here we found anti-inflammatory effects of a novel peptide (GC31) from CTLD of TM in endotoxin-induced uveitis, which was characterized by a reduction of leukocyte counts, protein concentration, tumor necrosis factor (TNF)-α and monocyte chemoattractant protein (MCP)-1 levels in aqueous humor. Through in vitro experiments, we further found that GC31 suppressed TNF-α and interleukin (IL)-6 expressions in lipopolysaccharide (LPS)-stimulated macrophage-like RAW264.7 cells and interrupted LPS-induced nuclear factor-κB (NF-κB) activation. These data indicate a beneficial role of peptide GC31 in preventing intraocular inflammatory response, especially uveitis.

Preventive effects of ethyl pyruvate on endotoxin-induced uveitis in rats

PURPOSE

Recent studies indicate that ethyl pyruvate (EP) exerts anti-inflammatory properties; however, the effect of EP on ocular inflammation is not known. The efficacy of EP in endotoxin-induced uveitis (EIU) in rats was investigated.

METHODS

EIU in Lewis rats was developed by the subcutaneous injection of lipopolysaccharide (LPS; 150 μg). EP (30 mg/kg body weight) or its carrier was injected intraperitoneally 1 hour before or 2 hours after lipopolysaccharide injection. Animals were killed after 3 and 24 hours followed by enucleation of eyes and collection of the aqueous humor (AqH). The number of infiltrating cells and levels of proteins in the AqH were determined. The rat cytokine/chemokine multiplex method was used to determine level of cytokines and chemokines in the AqH. TNF-α and phospho-nuclear factor kappa B (NF-κB) expression in ocular tissues were determined immunohistochemically. Human primary nonpigmented ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of EP on lipopolysaccharide-induced inflammatory response.

RESULTS

Compared to controls, AqH from the EIU rat eyes had a significantly higher number of infiltrating cells, total protein, and inflammatory cytokines/chemokines, and the treatment of EP prevented EIU-induced increases. In addition, EP also prevented the expression of TNF-α and activation of NF-κB in the ciliary bodies and retina of the eye. Moreover, in HNPECs, EP inhibited lipopolysaccharide-induced activation of NF-κB and expression of Cox-2, inducible nitric oxide synthase, and TNF-α.

CONCLUSIONS

Our results indicate that EP prevents ocular inflammation in EIU, suggesting that the supplementation of EP could be a novel approach for the treatment of ocular inflammation, specifically uveitis.

CXC chemokine expression profiles in aqueous humor of patients with different clinical entities of endogenous uveitis

Aqueous humor (AH) samples from patients with Behçet's disease (BD) (n=29), Vogt-Koyanagi-Harada (VKH) disease (n=21), and HLA-B27-associated uveitis (n=8), and 42 control patients were assayed for the neutrophil chemoattractants CXCL1/GRO-α and CXCL8/IL-8 and the lymphocyte chemoattractants CXCL9/MIG, CXCL10/IP-10 and CXCL12/SDF-1 with the use of a multiplex chemokine assay. Chemokine levels except SDF-1 were significantly higher in the 3 disease groups than in normal controls. Considering all patients, mean GRO-α levels were 15-fold higher than IL-8 levels and mean IP-10 levels were 22-fold higher than MIG levels. In patients with the same disease activity, AH levels of GRO-α and IP-10 were significantly higher in patients with BD than in patients with VKH disease and HLA-B27-associated uveitis (p=0.0474; p<0.001, respectively). These data suggest that GRO-α and IP-10 are the predominant CXC chemokines involved in neutrophil and activated T lymphocyte chemoattraction in endogenous uveitis, particularly in BD.

Calcium channel blocker nilvadipine, but not diltiazem, inhibits ocular inflammation in endotoxin-induced uveitis

PURPOSE

Calcium channel blockers (CCBs), widely used for hypertensive patients, have recently been shown to inhibit atherosclerosis by their antioxidative action. The aim of the present study was to examine whether the CCBs nilvadipine and diltiazem reduce ocular inflammation in endotoxin-induced uveitis (EIU).

METHODS

EIU was induced in male C57/B6 mice with a single intraperitoneal injection of lipopolysaccharide (LPS). The animals received intraperitoneal injections of either nilvadipine, diltiazem, or vehicle for 5 days before the LPS application. Twenty-four hours after EIU induction, adherent leukocytes to the retinal vasculature were counted with a concanavalin A lectin perfusion-labeling technique. The protein concentration in the aqueous humor was measured to assess blood-ocular barrier breakdown. Retinal levels of intercellular adhesion molecule (ICAM)-1 and monocyte chemotactic protein (MCP)-1 were analyzed by enzyme-linked immunosorbent assay. LPS-stimulated generation of superoxide in murine microvascular endothelial cells was examined with a nitroblue tetrazolium assay.

RESULTS

Compared to vehicle treatment, application of nilvadipine, but not diltiazem, led to significant suppression of EIU-associated retinal leukocyte adhesion, together with anterior-chamber protein leakage, retinal expression of ICAM-1 and MCP-1, and LPS-induced superoxide generation in vitro.

CONCLUSIONS

The CCB nilvadipine exercises an inhibitory effect on the pathogenesis of ocular inflammation through the suppression of inflammation-related molecules.

Mammalian telomeric DNA suppresses endotoxin-induced uveitis

Telomeric regions of mammalian chromosomes contain suppressive TTAGGG motifs that inhibit several proinflammatory and Th1-biased immune responses. Synthetic oligodeoxynucleotides (ODN) expressing suppressive motifs can reproduce the down-regulatory activity of mammalian telomeric repeats and have proven effective in the prevention and treatment of several autoimmune and autoinflammatory diseases. Endotoxin-induced uveitis (EIU) is an established animal model of acute ocular inflammation induced by LPS administration. Augmented expression of proinflammatory cytokines/chemokines such as TNFalpha, IL-6, and MCP1 and bactericidal nitric oxide production mediated by LPS contribute to the development of EIU. Suppressing these mediators using agents that are devoid of undesirable systemic side effects may help prevent the development of EIU. This study demonstrates the selective down-regulatory role of suppressive ODN after (i) local or (ii) systemic treatment in EIU-induced rabbits and mice. Our results indicate that suppressive ODN down-regulate at both the transcript and protein levels of several proinflammatory cytokines and chemokines as well as nitric oxide and co-stimulatory surface marker molecules when administrated prior to, simultaneously with, or even after LPS challenge, thereby significantly reducing ocular inflammation in both rabbit and mouse eyes. These findings strongly suggest that suppressive ODN is a potent candidate for the prevention of uveitis and could be applied as a novel DNA-based immunoregulatory agent to control other autoimmune or autoinflammatory diseases.

Rationally evolving MCP-1/CCL2 into a decoy protein with potent anti-inflammatory activity in vivo

Leukocyte recruitment from the blood into injured tissues during inflammatory diseases is the result of sequential events involving chemokines binding to their GPC receptors as well as to their glycosaminoglycan (GAG) co-receptors. The induction and the crucial role of MCP-1/CCL2 in the course of diseases that feature monocyte-rich infiltrates have been validated in many animal models, and several MCP-1/CCL2 as well as CCR2 antagonists have since been generated. However, despite some of them being shown to be efficacious in a number of animal models, many failed in clinical trials, and therapeutically interfering with the activity of this chemokine is not yet possible. We have therefore generated novel MCP-1/CCL2 mutants with increased GAG binding affinity and knocked out CCR2 activity, which were designed to interrupt the MCP-1/CCL2-related signaling cascade. We provide evidence that our lead mutant MCP-1(Y13A/S21K/Q23R) exhibits a 4-fold higher affinity toward the natural MCP-1 GAG ligand heparan sulfate and that it shows a complete deficiency in activating CCR2 on THP-1 cells. Furthermore, a significantly longer residual time on GAG ligands was observed by surface plasmon resonance. Finally, we were able to show that MCP-1(Y13A/S21K/Q23R) had a mild ameliorating effect on experimental autoimmune uveitis and that a marginal effect on oral tolerance in the group co-fed with Met-MCP-1(Y13A/S21K/Q23R) plus immunogenic peptide PDSAg was observed. These results suggest that disrupting wild type chemokine-GAG interactions by a chemokine-based antagonist can result in anti-inflammatory activity that could have potential therapeutic implications.

Chemokines – their role in immunotherapy for intraocular inflammation

Chemotactic cytokines are responsible for leukocyte migration and the immunopathogenesis of various inflammatory lesions. Together with other types of cytokines, chemokines play a major role in inducing/regulating inflammation and various immune responses. By targeting chemokines, immunotherapies could become another option for treating patients with uveitis. Indeed, a variety of chemokine-based therapies have been tested for their possible application for various pathological diseases, including intraocular inflammation. An example of chemokine-based therapy is anti-tumor necrosis factor (TNF)-alpha therapy, a very successful treatment. Chemokine- and cytokine-based therapies, therefore, appear to be a promising choice for the treatment of intraocular inflammation.

Effect of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) on IL-6, IL-8, and MCP-1 Expression in Human Retinal Pigment Epithelial Cell Line

PURPOSE

To examine pituitary adenylate cyclase-activating polypeptide (PACAP) receptors (PAC1, VPAC1, and VPAC2) mRNA and the effect of PACAP on interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) expression in human retinal pigment epithelial cell line (ARPE-19) stimulated with interleukin-1beta (IL-1beta).

METHODS

Expression of PACAP receptor mRNA was examined by reverse transcription polymerase chain reaction (RT-PCR). PACAP and IL-1beta were added to serum-free medium. IL-6, IL-8, and MCP-1 mRNA were measured by real-time PCR. IL-6, IL-8, and MCP-1 protein concentrations were measured using enzyme-linked immunosorbent assay. Nuclear factor kappaB (NF-kappaB) translocation was examined by immunofluorescence.

RESULTS

PAC1 and VCAP1 receptors mRNA were expressed in unstimulated cells. VCAP2 mRNA was expressed in cells stimulated with IL-1beta. IL-1beta stimulated IL-6, IL-8, and MCP-1 mRNA expression and protein levels. PACAP (10(- 7) to 10(- 6) M) inhibited IL-1beta -stimulated IL-6, IL-8, and MCP-1 mRNA and protein levels. Immunofluorescence of NF-kappaB in the nucleus was dense 30 min after stimulation with IL-1beta, and it was decreased by PACAP.

CONCLUSIONS

ARPE-19 cells had PACAP receptors mRNA. PACAP inhibited IL-6, IL-8, and MCP-1 expression and protein secretion. Possibly, the effect on cytokines may be via suppression of NF-kappaB translocation.

Increased vascular endothelial growth factor levels in aqueous humor and serum of patients with quiescent uveitis

PURPOSE

Vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) are angiogenic mediators that share a significant proinflammatory activity. Both substances have been suggested to play a key role in uveitis pathogenesis. The authors analyzed VEGF and IL-8 levels in the aqueous humor and serum of patients with different types of uveitis during a quiet phase of the disease.

METHODS

Thirteen patients with intermediate uveitis, uveitis associated with ankylosing spondylitis, Vogt-Koyanagi-Harada disease, Fuchs uveitis syndrome, idiopathic chronic anterior uveitis, or Behcet disease, as well as 10 normal matched subjects, were included in the study. VEGF and IL-8 concentrations were measured in aqueous humor and serum by enzyme-linked immunosorbent assay.

RESULTS

VEGF levels were significantly higher in both the aqueous humor and serum of patients with uveitis as compared with controls. IL-8 concentrations in aqueous humor were significantly higher in patients with uveitis with extraocular manifestations than in those with eye-limited disease.

CONCLUSIONS

These findings suggest that VEGF plays a role in uveitis pathogenesis even during inactive disease and that IL-8 levels are significantly influenced by the presence of uveitis-associated extraocular changes.

Serum cytokine levels in active uveitis and remission

Serum levels of interleukin(IL)-8, IL-6, and (TNF)-alpha were measured in 25 patients during active uveitis and uveitis in remission and compared to age-matched controls. Levels of IL-8 and IL-6 were significantly elevated in patients with active disease and were decreased during remission. IL-8 levels were highest in patients with anterior uveitis, with greatest difference between active disease and remission. No consistent pattern was observed for TNF-alpha. In conclusion, serum cytokine levels are elevated in active noninfectious uveitis. The rise in IL-8 may suggest innate immune mechanisms in the acute disease, while IL-6 participates in modulation of inflammation in the chronic disease.

The role of chemokines and their receptors in uveitis

T-cell-dependent immunological events are increasingly being regarded as extremely important in the pathogenesis of uveitis. Several studies have also shown that macrophages are major effectors of tissue damage in uveitis. Neutrophils are also thought to play a central role in the pathogenesis of Behçet's disease. Chemokines are a superfamily of 8 to 10-kDa secreted proteins that direct the recruitment of leukocytes to sites of inflammation. The specific biological effects of chemokines are mediated by a family of seven transmembrane-spanning G-protein-coupled receptors. Recent studies of animals and humans suggest that chemokines and their receptors play a key role in leukocyte recruitment into the eye in uveitis. A strategy for blocking chemokines or chemokine receptors could be a new approach for treatment of uveitis.

Effect of Berberine on Monocyte Chemotactic Protein-1 and Cytokine-Induced Neutrophil Chemoattractant-1 Expression in Rat Lipopolysaccharide-Induced Uveitis

PURPOSE

The aims of this study were to examine the in vivo effects of berberine, an alkaloid isolated from some medicinal herbs, on monocyte chemotactic protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant-1 (CINC-1) expression in rat lipopolysaccharide (LPS)-induced uveitis.

METHODS

LPS was injected intraperitoneally. Berberine was orally administered. MCP-1 mRNA and CINC-1 mRNA were measured by semiquantitative reverse-transcription polymerase chain reaction and real-time polymerase chain reaction. MCP-1 and CINC-1 protein concentration in the aqueous humor were measured by enzyme-linked immunosorbent assay. Histopathologic study was performed in the anterior ocular segments.

RESULTS

Berberine dose-dependently inhibited LPS-induced MCP-1 mRNA and CINC-1 mRNA expression of the iris-ciliary body. The alkaloid inhibited chemokines, protein and cell levels in the aqueous humor in rats stimulated with LPS. On histopathologic study, the inflammatory cell infiltration was diminished by the berberine treatment.

CONCLUSIONS

These findings indicate that berberine dose-dependently inhibited the expression of MCP-1 and CINC-1 induced by LPS and diminished the anterior uveitis.

Chemokine gene polymorphisms in idiopathic anterior uveitis

OBJECTIVES

The aim of this study was to determine whether there are any associations between single nucleotide polymorphisms of the chemokine genes IL-8, MCP-1, their corresponding receptors CXCR1 and CCR2 and disease outcome in patients with acute idiopathic anterior uveitis.

METHODS

60 Caucasian patients with idiopathic acute recurrent anterior uveitis together with 120 healthy Caucasian control subjects were tested for the presence of 16 bi-allelic polymorphisms and HLA-B27 using polymerase chain reaction in association with sequence-specific primers with mismatches at the 3' end. The genetic data was then compared between patients and controls, and within the patient group itself for association with clinical disease outcome.

RESULTS

As expected, the frequency of HLA-B27 was significantly higher in the patient group than the control group (63.33% versus 15.83%; Pearson's P<0.0001, Fisher's P<0.0001). In addition, the frequency of the T allele of MCP-1 63555 was found to be significantly higher in the control group when compared to the patient group (P=0.0160).

CONCLUSION

This study describes an association between acute anterior uveitis and MCP-1 63555 polymorphisms where the T allele may be a protective marker against the disease.

Suppressive effects of astaxanthin against rat endotoxin-induced uveitis by inhibiting the NF-kappaB signaling pathway

We investigated the effects of astaxanthin (AST), a carotenoid, on endotoxin-induced uveitis (EIU), and over the course of the disease measured the expression of inflammatory cytokines and chemokines in the presence or absence of AST. EIU was induced in male Lewis rats by footpad injection of lipopolysaccharide (LPS). The animals were randomly divided to 12 groups with eight animals in each. Immediately after the inoculation, AST (1, 10, or 100 mg kg(-1)) was injected intravenously. Aqueous humour was collected at 6, 12 and 24 hr after LPS inoculation and the number of infiltrating cells in the anterior chamber was counted. In addition, we assayed the concentration of protein, nitric oxide (NO), tumour necrosis factor-alpha (TNF-alpha) and prostaglandin E2 (PGE2). Immunohistochemical staining with a monoclonal antibody against activated NF-kappaB was performed in order to evaluate the effects of AST on NF-kappaB activation. Rats injected with AST showed a significant decrease in the number of infiltrating cells in the anterior chamber and additionally there was a significantly lower concentration of protein, NO, TNF-alpha and PGE2 in the aqueous humour. Moreover, even early stages of EIU were suppressed by injection of AST. The number of activated NF-kappaB-positive cells was lower in iris-ciliary bodies treated with 10 or 100 mg kg(-1) AST at 3 hr after LPS injection. These results suggest that AST reduces ocular inflammation in eyes with EIU by downregulating proinflammatory factors and by inhibiting the NF-kappaB-dependent signaling pathway.

Anti-inflammatory effects of alpha-melanocyte-stimulating hormone against rat endotoxin-induced uveitis and the time course of inflammatory agents in aqueous humor

PURPOSE

We examined the effects of the immunosuppressive neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) on rat endotoxin-induced uveitis, and to measure the expression of inflammatory cytokines and chemokines with and without the alpha-MSH treatment over the course of the disease.

METHODS

We injected Lewis rats once with Salmonella typhimurium lipopolysaccharide (LPS) to induce uveitis. The rats were given intravenous injections of 250, 500 or 1000 microg of alpha-MSH. The eyes were examined over the next 24 h for inflammation. Aqueous humor was collected 6, 12 and 24 h after endotoxin injections and the number of infiltrating cells were counted in anterior chamber. In addition, we assayed the concentration of protein, nitric oxide, TNF-alpha, IL-6, MCP-1 and MIP-2.

RESULTS

Rats injected with alpha-MSH showed a significant decrease in the number of infiltrating cells in anterior chamber. Moreover, alpha-MSH-treated rats with endotoxin-induced uveitis (EIU) showed significantly lower concentrations of protein, nitric oxide, proinflammatory cytokines and chemokines in their aqueous humor. Even the early stages of EIU were suppressed by the injection of alpha-MSH.

CONCLUSIONS

Our results demonstrate that the immunosuppressive neuropeptide alpha-MSH inhibits the early induction events of endotoxin-induced inflammation in the eye; therefore, suppresses the subsequent infiltration of cells and intraocular production of inflammatory cytokines and chemokines in eyes. alpha-MSH has a possibility of being a therapeutic strategy for anterior uveitis.

The activation of IL-8 receptors in cultured guinea pig Müller glial cells is modified by signals from retinal pigment epithelium

Interleukin 8 (IL-8, CXCL8) is a pro-inflammatory chemokine which attracts neutrophils to sites of inflammation via an activation of the G-protein-coupled receptors, CXCR1 and CXCR2. However, both IL-8 and IL-8 receptors are widely expressed in various tissues and cell types, and have been suggested to be involved in other functions such as angiogenesis, tumor growth, or brain pathology. We examined the expression of IL-8 and IL-8 receptors in highly enriched primary cultures of guinea pig Muller glial cells. Immunoreactivity for CXCL8, CXCR1 and CXCR2 was observed in all cultured Muller cells. The expression of CXCL8 was confirmed by PCR, and the secretion of the CXCL8 protein from Muller cells was revealed by ELISA. Western blots showed prominent bands at approximately 40 kDa by using antibodies specific for human CXCR1 and CXCR2, and the expression of a putative CXCR2 receptor in Muller cells was confirmed by PCR. Furthermore, cultured Muller cells responded to application of recombinant human IL-8 with an increase of the cytosolic Ca(2+) concentration. If supernatants of cultured human retinal pigment epithelium (RPE) cells were applied to the Muller cell cultures, no obvious changes were observed in the CXCL8, CXCR1 and CXCR2 expression but (i) Muller cell proliferation was stimulated, and (ii) there was an increased number of CXCL8-responsive Muller cells and the amplitudes of the evoked calcium responses were enhanced. It is concluded that Muller glial cells may participate in the inflammatory response(s) of the retina during ocular diseases, and that this contribution may be modified by interactions with RPE cells.

Ocular inflammation alters swelling and membrane characteristics of rat Müller glial cells

Ocular inflammation is a common cause of retinal edema that may involve swelling of Müller glial cells. In order to investigate whether endotoxin-induced ocular inflammation in rats alters the swelling and membrane characteristics of Müller cells, lipopolysaccharide (LPS; 0.5%) was intravitreally injected. At 3 and 7 days after treatment, hypotonic challenge induced swelling of Müller cell somata that was not observed in non-treated control eyes. Müller cells of LPS-treated eyes displayed a downregulation of inward K(+) currents and upregulation of A-type K(+) currents that was associated with a decreased expression of Kir4.1 protein in retinal slices. The data suggest that ocular inflammation induces alterations of both the swelling characteristics and the K(+) channel expression of Müller cells.

DNA microarray analysis of gene expression in iris and ciliary body of rat eyes with endotoxin-induced uveitis

The purposes of this study are to determine the genes that are up- or down-regulated in eyes with endotoxin-induced uveitis (EIU) by an oligonucleotide microarray system, and to determine the temporal and spatial changes in expression of selected genes that show strong up-regulation. EIU was induced by a footpad injection of lipopolysaccharide (LPS) in male Lewis rats. The expression of genes in the iris-ciliary body (ICB) at 2, 6, 12, and 24 hr after LPS injection was determined by oligonucleotide microarray analyses and compared to that in control rats. The microarray displayed 9911 genes and expressed sequence tags (ESTs). Cluster analysis was performed for highly up-regulated genes. Selected genes for cytokines (interleukin (IL)-1 beta and IL-6), chemokines (RANTES), and immediate early genes (Jun B, c-Fos, and c-Jun) were also studied by real-time polymerase chain reaction (PCR). Immunohistochemical studies were performed to localize the protein expression of some immediate early gene products. After LPS injection, the expression of 1930 genes were increased or decreased over 2-folds compared with normal controls by 24 hr. One hundred and seventeen genes were up-regulated over 10-fold, and these were classified into five clusters with similar expression pattern. The immediate early genes and transcription factors genes were included in one cluster of up-regulated genes peaking at 2 hr after the LPS injection. The expressions of cytokines, chemokines, and adhesion molecules were highly up-regulated. Real-time PCR analyses for selected genes showed similar expression changes as detected by the microarray analyses. Jun B immunoreactivity was found in the ICB cells at 3 and 6 hr after LPS injection. Gene expression changes after LPS injection were profiled by using an oligonucleotide microarray system. Our data suggest that the immediate early genes, such as Jun B, play an important role in inducing the inflammatory-related genes in the ICB.

Expression of chemokine and receptors in Lewis rats with experimental autoimmune anterior uveitis

The purpose of this study is to investigate the sequential expression of certain chemokines and chemokine receptors in the iris-ciliary body and popliteal lymph nodes of Lewis rats and, thus, to establish their roles in experimental autoimmune anterior uveitis. Uveitis was induced with the injection of melanin-associated antigen intraperitoneally and into the left foot. The clinical severity of the uveitis was scored. At defined time points, CC chemokines (monocyte chemoattractant protein-1, macrophage inflammatory protein-1, and regulated-upon-activation normal T-cell expressed and secreted), CXC chemokines (interferon gamma-inducible protein-10, stromal-derived factor-1, and interleukin-8), and receptor (CCR2, CCR3, CCR5, CXCR1, CXCR2, CXCR3, and CXCR4) mRNA expression were semiquantified by using a reverse-transcriptase reaction followed by polymerase chain reaction. The concentrations of macrophage inflammatory protein-1 and regulated-upon-activation normal T-cell expressed and secreted in aqueous humor were determined by means of enzyme-linked immunosorbent assay. Levels of monocyte chemoattractant protein-1, macrophage inflammatory protein-1 and interferon gamma-inducible protein-10 started increasing before the clinical onset of disease; these might have been involved in the initial recruitment of inflammatory cells. The level of regulated-upon-activation normal T-cell mRNA, however, started rising concurrently with the onset of clinical disease, suggesting that this chemokine may exert amplifying role in generating uveitis. Stromal-derived factor-1 exhibited an early and high level of expression with the increase of cognate receptor, CXCR4, indicating that stromal-derived factor-1 plays a role in either promoting angiogenesis or attracting for T-cells. Instead of upregulation like other chemokine receptors, interleukin-8 receptors, CXCR1and CXCR2, mRNA could not be detected in accord with the increase of interleukin-8. These findings appeared that downregulation of chemokine receptors on neutrophils may make themselves less respond to interleukin-8 and subsequently lead to decreased recruitment of neutrophils into the iris-ciliary body. In addition, the expression of chemokine receptors in popliteal lymph nodes were earlier than those in the iris-ciliary body. This sequence of expression may reflect the process of T lymphocytes maturation and differentiation. Monocyte chemoattractant protein-1 protein was immunohistologically detected in the ciliary epithelium and infiltrating leukocytes. The above results suggest that chemokines, which act on T cells and monocytes, are sequentially upregulated during the clinical course of experimental autoimmune anterior uveitis, and thus, may contribute to the pathogenesis of acute anterior uveitis.

Detection of neutrophils and possible involvement of interleukin-8 in diffuse lamellar keratitis after laser in situ keratomileusis

PURPOSE

To investigate the cell populations in diffuse lamellar keratitis (DLK) infiltration after laser in situ keratomileusis and the possible mechanism underlying the infiltration.

SETTING

Department of Ophthalmology, Tokyo Dental College, Chiba, Japan.

METHODS

To develop DLK in rabbit eyes, 25 microL of lipopolysaccharide (LPS) solution at a concentration of 50 microg/mL was applied to the stromal bed beneath corneal flaps. For control rabbits, phosphate-buffered saline was applied. Postoperative examination by slitlamp microscopy was performed for 3 days after surgery. Rabbit eyes were excised and examined for histopathology with hematoxylin and eosin staining. Immunohistochemical analysis for interleukin (IL)-8 was performed.

RESULTS

Diffuse lamellar keratitis-like inflammation composed mainly of neutrophils was reproduced by LPS instillation in rabbit eyes. In eyes with severe inflammation, IL-8 immunoreactivity was found in the stromal keratocytes and infiltrating neutrophils.

CONCLUSIONS

The major cell type in the DLK infiltration induced by LPS instillation in rabbit eyes was the neutrophil. Interleukin-8, a prototype of CXC chemokine produced by keratocytes and neutrophils, may contribute to the development of DLK.

Effects of baicalin, baicalein, and wogonin on interleukin-6 and interleukin-8 expression, and nuclear factor-kappab binding activities induced by interleukin-1beta in human retinal pigment epithelial cell line

The objective of the study was to investigate the effects of baicalin, baicalein, and wogonin (plant flavonoids) on interleukin-6 (IL-6) and interleukin-8 (IL-8) protein production, mRNA expression, and nuclear factor-kappaB (NF-kappaB) binding activities induced by interleukin-1beta (IL-1beta) in human retinal pigment epithelial cell line (ARPE-19) cells. To induce IL-6 and IL-8 mRNA expression and protein levels, IL-1beta was added to serum-free medium of ARPE-19 cells and incubated. The flavonoids were added to the medium. IL-6 and IL-8 in the media were measured using enzyme-linked immunosorbent assay. Both IL-6 and IL-8 mRNA were measured by semiquantitative reverse transcription polymerase chain reaction. The binding activities of the transcription factor NF-kappaB complexes to IL-6 and IL-8 were measured by electrophoretic mobility shift assay. IL-6 and IL-8 in the culture media of ARPE-19 cells were increased by IL-1beta in a dose-dependent manner. Baicalin did not suppress IL-1beta-induced IL-6 and IL-8 production, but dexamethasone, baicalein, and wogonin, significantly suppressed IL-6 and IL-8 production. Elevation of IL-6 and IL-8 mRNA was not suppressed by baicalin but was significantly suppressed by dexamethasone, baicalein, and wogonin. NF-kappaB binding activities were not suppressed by baicalin and baicalein, but was suppressed by wogonin. Wogonin and baicalein inhibited IL-1beta-induced IL-6 and IL-8 mRNA and protein production in ARPE-19 cells. The data suggest that wogonin may inhibit IL-6 and IL-8 mRNA expression via the suppression of NF-kappaB binding activities.

Tumor necrosis factor-alpha inhibition reduces CXCL-8 levels but fails to prevent fibrin generation and does not improve outcome in a rabbit model of endotoxic shock

The effects of a monoclonal antibody (mAb) to tumor necrosis factor-alpha (TNF-alpha) were examined in a rabbit model of endotoxic shock. Intravenous administration of lipopolysaccharide (100 microg/kg/hr) for 6 hours (n = 11) increased TNF-alpha levels. Fibrinogen was partially consumed, and fibrin deposits were seen in kidney and lungs at 24 hours. Mortality at 24 hours was 64%. Levels of interleukin-8 (aka CXCL-8) were notably increased. Mean arterial pressure (MAP) and leukocyte counts decreased, whereas creatinine levels were enhanced. The anti-TNF-alpha mAb (20 mg/kg i.v. bolus + 5 mg/kg/h i.v. for the first 90 minutes) (n = 10) efficiently inhibited the TNF-activity. Rabbits exhibited lower CXCL-8 levels; MAP improved, the decrease in leukocyte counts was partially prevented and creatinine levels were lower, but fibrinogen, fibrin deposits in kidneys and lungs and mortality, 55%, were similar to the LPS group. Rabbits that did not survive exhibited lower fibrinogen levels, more fibrin in kidneys and lungs and higher CXCL-8 and creatinine levels than survivors, while there were no differences in TNF-alpha, MAP and leukocytes. Thus, the inhibition of TNF-alpha, although beneficial through lowering CXCL-8 levels, is not enough to improve the outcome, which could be partly due to the inability to prevent the fibrin deposits formation in kidneys and lungs.

Involvement of CXC chemokine growth-related oncogene-alpha in monosodium urate crystal-induced arthritis in rabbits

Accumulation of neutrophils is a prominent feature of gouty arthritis in which CXC chemokines may play a role. Recently, we have shown that IL-8 (CXCL8) contributes to neutrophil influx in a rabbit model of gouty arthritis. Here, we demonstrate that growth-related oncogene-alpha (GROalpha) (CXCL1), a prototype of CXC chemokine, is also involved in this process. GROalpha level in the joints peaked at 2 hours after intra-articular injection of monosodium urate crystals, at a time before the neutrophil influx reached the maximal level (9 hours). Once decreased, the level increased and reached the second peak at 9 hours. The kinetics was comparable to that of IL-8. Administration of anti-GROalpha mAb attenuated the neutrophil influx at the same level as did the anti-IL-8 IgG, and combination of these antibodies enhanced the inhibition, resulting in a 33% reduction. Interaction of GROalpha with TNFalpha, IL-1beta, and IL-8 was next investigated by injecting antibodies or receptor antagonist with monosodium urate crystals. Administration of anti-TNFalpha mAb did not alter GROalpha level at 2 hours, but inhibited the levels 9 hours after the injection. Treatment with either IL-1 receptor antagonist or anti-IL-8 IgG resulted in decreased levels of GROalpha at 2 and 9 hours. Neutralization of GROalpha with anti-GROalpha mAb did not alter TNFalpha, IL-1beta, and IL-8 levels at their peak (2 hours), but decreased the second peak of IL-1beta (9 hours) and IL-8 (12 hours). These results provide evidence that GROalpha as well as IL-8 are involved ad eundem in the neutrophil infiltration in this model. IL-1 and IL-8, but not TNFalpha, are responsible in part for the initial phase of GROalpha, whereas these cytokines induce GROalpha in a late phase. GROalpha does not seem to initiate TNFalpha, IL-1beta, and IL-8 in an early phase, but induces IL-1beta and IL-8 in a late phase.

Expression of a chemokine by ciliary body epithelium in horses with naturally occurring recurrent uveitis and in cultured ciliary body epithelial cells

OBJECTIVE

To determine whether a chemokine (RANTES)-like protein expressed by ciliary epithelium plays a role in uveitis.

SAMPLE POPULATION

3 clinically normal horses intradermal, 5 eyes from 5 horses with recurrent uveitis, and 10 normal eyes from 5 age- and sex-matched horses.

PROCEDURE

Cross-reactivity and sensitivity of recombinant human (rh)-regulated upon activation, normal T-cell expressed and secreted (RANTES) protein were evaluated in horses by use of intradermal hypersensitivity reactions and a chemotaxis assay. Aqueous humor and ciliary body of eyes from clinically normal horses and horses with uveitis were examined for RANTES expression by use of an ELISA and reverse transcription-polymerase chain reaction (RT-PCR). Expression of RANTES mRNA and protein content of primary cultures of equine ciliary pigmented epithelial cells (RT-PCR) and culture supernatant (ELISA) were measured 6 or 24 hours, respectively, after cultures were stimulated with interleukin-1beta and tumor necrosis factor-alpha.

RESULTS

Strong reactions to intradermal hypersensitivity testing and significant chemotaxis of equine leukocytes to rh-RANTES wereas observed. Aqueous humor of eyes from horses with uveitis contained increased concentrations of rh-RANTES-like protein (mean +/- SD, 45.9+/-31.7 pg/ml), compared with aqueous humor from clinically normal horses (0 pg/ml). Ciliary body from horses with uveitis expressed RANTES mRNA, whereas ciliary body from clinically normal horses had low mRNA expression. Stimulated ciliary pigmented epithelial cells expressed increased amounts of rh-RANTES-like protein (506.1+/-298.3 pg/ml) and mRNA, compared with unstimulated samples.

CONCLUSIONS AND CLINICAL RELEVANCE

Ciliary epithelium may play a role in recruitment and activation of leukocytes through expression of RANTES.

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

BACKGROUND/AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

MCP-1 causes leukocyte recruitment and subsequently endotoxemic ileus in rat

Endotoxemia causes an inflammatory response within the intestinal muscularis and gastrointestinal dysmotility. We hypothesize that the resident macrophage-derived chemokine monocyte chemoattractant protein-1 (MCP-1) plays a significant role in the recruitment of leukocytes into the lipopolysaccharide (LPS)-stimulated rat intestinal muscularis. MCP-1 mRNA expression was investigated by RT-PCR. Leukocyte extravasation and MCP-1 protein localization were determined by immunohistochemistry. Contractile activity was assessed by using a standard organ bath in rats that were treated with saline, recombinant MCP-1, LPS, LPS + nonspecific antibody, or LPS + MCP-1 antibody. Endotoxemia caused a significant 280-fold increase in MCP-1 mRNA expression in the muscularis, peaking at 3 h. MCP-1 protein was immunohistochemically located to muscularis macrophages. LPS application caused significant leukocyte recruitment into the muscularis and a 51% decrease in muscle contractility. MCP-1 antibody treatment significantly averted leukocyte recruitment and significantly prevented muscle dysfunction. These parameters were not significantly altered by the nonspecific antibody. Results show that resident muscularis macrophage-derived MCP-1 plays a major role in the recruitment of monocytes during endotoxemia, which then subsequently secrete kinetically active substances that cause ileus.

Functional distinction between CXC chemokines, interleukin-8 (IL-8), and growth related oncogene (GRO)alpha in neutrophil infiltration

Interleukin-8 (IL-8: CXCL8) and growth related oncogene alpha (GROalpha: CXCL1) are members of the CXC chemokines. In the present study, we explored the functional distinction between these CXC chemokines in the regulation of neutrophil infiltration. Injection of either rabbit IL-8 or GROalpha (10 microg each) into rabbit knee joints resulted in a massive neutrophil infiltration in the joints. At their peak time point (6 hours), the number of neutrophils induced by IL-8 was more than that induced by GROalpha. Each chemokine induced the other chemokine in the joints. TNFalpha activity was induced in the joints after administration of GROalpha, but not IL-8. Treatment with anti-GROalpha mAb and/or anti-TNFalpha mAb failed to inhibit IL-8-induced neutrophil infiltration. In contrast, either anti-IL-8 IgG or anti-TNFalpha mAb decreased GROalpha-induced response, and the inhibition was further enhanced by coadministration of these antibodies. Thus, it appears that IL-8 acts directly, whereas GROalpha acts indirectly, in part, on neutrophil infiltration. The distinct difference in TNFalpha production between IL-8 and GROalpha was further investigated. In vitro, GROalpha induced TNFalpha activity in cultured synovial cells, the cells producing TNFalpha in the joints after GROalpha-injection. However, IL-8 failed to produce TNFalpha activity from the cells, although equivalent levels of the mRNA expression were induced by IL-8 as compared with GROalpha. When recombinant rabbit TNFalpha was incubated with synovial fluids obtained at 2 hours after IL-8 injection, the resultant TNFalpha activity was significantly decreased, an event that was completely restored by a serine protease inhibitor, phenylmethylsulphonyl fluoride (PMSF). Furthermore, TNFalpha activity was unveiled in the joints when IL-8 was intra-articularly injected with PMSF. These data suggest that TNFalpha is degraded by serine protease(s) in the case of IL-8. Taken together, the data clearly demonstrate the functional distinction between IL-8 and GROalpha, which may influence the inflammatory responses.

Bacterial endophthalmitis: epidemiology, therapeutics, and bacterium-host interactions

Endophthalmitis is a severe inflammation of the interior of the eye caused by the introduction of contaminating microorganisms following trauma, surgery, or hematogenous spread from a distant infection site. Despite appropriate therapeutic intervention, bacterial endophthalmitis frequently results in visual loss, if not loss of the eye itself. Although the pathogenicity of bacterial endophthalmitis has historically been linked with toxin production during infection, a paucity of information exists as to the exact mechanisms of retinal toxicity and the triggers for induction of the intraocular immune response. Recently, research has begun to examine the bacterial and host molecular and cellular events that contribute to ocular damage during endophthalmitis. This review focuses on the causative agents and therapeutic challenges of bacterial endophthalmitis and provides current data from the analysis of the role of bacterial virulence factors and host inflammatory interactions in the pathogenesis of eye infections. Based on these and related studies, a hypothetical model for the molecular pathogenesis of bacterial endophthalmitis is proposed. Identifying and understanding the basic mechanisms of these bacterium-host interactions will provide the foundation for which novel, information-based therapeutic agents are developed in order to prevent vision loss during endophthalmitis.

Cytokine modulation of liver annexin 1 expression during experimental endotoxemia

Annexin 1 (ANXA1) is a calcium-binding protein endowed with anti-inflammatory properties. Using an extra-hepatic system, we showed that interleukin (IL)-6 regulates ANXA1 expression at the transcriptional level. The purpose of this study was to determine whether ANXA1 synthesis was modulated by IL-6 during experimental inflammation. We have compared liver ANXA1 expression during systemic and localized inflammatory reaction, using lipopolysaccharide (LPS) and turpentine. LPS treatment strongly induced ANXA1 expression in the liver of wild-type (WT) animals (+600%) whereas a modest increase (+60%) was measured in IL-6 knockout (KO) animals. Turpentine treatment did not affect the expression of ANXA1 in either animal type. LPS enhanced serum corticosteroid levels equally in WT and IL-6 KO mice, whereas higher tumor necrosis factor (TNF)-alpha and IL-1beta levels were released in IL-6 KO animals. Injection of mouse recombinant IL-6 to IL-6 KO animals before LPS or TNF-alpha challenge, replenished ANXA1 liver synthesis to that of WT animals. Exogenous ANXA1 but not ANXA5, administered to IL-6 KO mice before LPS challenge inhibited TNF-alpha release. We propose that ANXA1 acts as a novel acute phase protein, which is controlled in the liver by TNF-alpha and IL-6, and which may contribute to the resolution of systemic endotoxemia through a negative feedback on TNF-alpha release.

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

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