Endotoxin-Induced Uveitis in Rodents

Engineering a novel water-in-oil biocompatible microemulsion system for the ocular delivery of dexamethasone sodium phosphate in the treatment of acute uveitis

Due to their unique characteristics, microemulsions (ME) represent one of the most promising delivery systems which can conquer poor ocular drug bioavailability providing long residence time. Development of a ME system, relying on the use of a safe and non-irritant surfactant combination derived from sustainable resources and which can consolidate the small ME droplets, is the goal of this work. Herein, we report the design and characterization of a novel biocompatible, eco-friendly ME system loaded with the hydrophilic dexamethasone sodium phosphate (DEXP) using a novel surfactant mixture composed of D-α-tocopherol polyethylene glycol succinate (TPGS) and Plantacare® (coco-Glycosides). Capryol™ PGMC and double-distilled water were used as the respective oil and aqueous phases and the MEs were prepared by the water titration method, suitable for scaling up. Optimization of ME formulae was conducted by varying Plantacare® grades, TPGS to Plantacare® mass ratios and drug loading. The formulae were characterized in terms of physical appearance, droplet size (PS), size distribution (PDI), zeta potential (ZP), and stability. The optimized DEXP-loaded ME formula attained acceptable PS, PDI, and ZP values of 43 ± 5 nm, 0.35 ± 0.07, -12 ± 4 mV, respectively. TEM images confirmed a small PS ≤ 100 nm. The in vivo safety of ME was proved by the Draize test. The ME formula prompted excellent mucoadhesion and transcorneal permeation. The confocal studies showed deep penetration into the rabbits' corneas. In vivo studies using endotoxin-induced uveitis showed high ocular efficacy and a significant reduction in inflammatory cells, including interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). The obtained results elect the novel engineered ME system as a promising tool for the ocular delivery of hydrophilic moieties in the management of various ophthalmic diseases.

Slit2 suppresses endotoxin-induced uveitis by inhibiting the PI3K/Akt/IKK/NF-κB pathway

Uveitis is a devastating intraocular inflammatory disease. The secreted leucine-rich repeat protein slit homologue 2 (Slit2) has been found to be an essential regulator of inflammation. This study aimed to analyse the anti-inflammatory effects and the underlying mechanisms of Slit2 in an endotoxin-induced uveitis (EIU) rat model. In this study, rats with EIU pretreated recombinant human Slit2 (rhSlit2) or a control vehicle by intravitreal injection. The clinical scores were graded under a slit lamp. The protein concentrations and total number of cells in the aqueous humour (AqH) were examined, and the retinal expression of various inflammatory mediators was detected. The levels of nuclear factor-kappa B (NF-κB), phosphorylated NF-κB, IkappaB-a (IκB-a), phosphorylated IκB-a, IKK, phosphorylated IKK, PI3Kp85, phosphorylated PI3Kp85, Akt and phosphorylated Akt were evaluated by western blotting. Treatment with rhSlit2 dramatically diminished the clinical scores of EIU, with significant decreases in inflammatory cell infiltration, protein concentrations, cellulose-like exudates, the production of ICAM-1, MCP-1, TNF-α and IL-6 in the AqH; and adhesion of leucocytes. The PI3K/Akt/IKK/NF-κB pathway was found to be activated in EIU. However, the pre-treatment of rhSlit2 significantly inhibited the production of ICAM-1, MCP-1, TNF-α, and IL-6, and inhibited leucocyte adhesion by modulating the PI3K/Akt/IKK/NF-κB pathway. In conclusion, the intravitreal injection of rhSlit2 alleviated EIU-related inflammation in Sprague-Dawley rats by reducing the proinflammatory cytokines and leucocyte adhesion; in particular, rhSlit2 may inhibit LPS-induced inflammation by inhibiting the activation of PI3K/Akt/IKK/NF-κB signalling pathway. Therefore, rhSlit2 shows significant potential for effectively alleviating immune inflammatory responses in vivo.

Murine cytomegalovirus localization and uveitic cell infiltration might both contribute to trabecular meshwork impairment in Posner-Schlossman syndrome: Evidence from an open-angle rat model

As a special type of glaucoma, Posner-Schlossman syndrome (PSS) is characterized by elevated intraocular pressure (IOP) and anterior uveitis. Cytomegalovirus (CMV) anterior chamber infection has now been considered the leading cause of PSS. We used murine CMV (MCMV) intracameral injection to establish a rat model manifested in IOP elevation and mild anterior uveitis, much like PSS; viral localization and gene expression at various time points and inflammatory cell infiltration derived from innate and adaptive immunity were investigated, as well as pathogenetic changes of the trabecular meshwork (TM). The IOP and uveitic manifestations peaked at 24 h post-infection (p.i.) and returned to normal after 96 h; the iridocorneal angle remained open consistently. At 24 h p.i., leucocytes gathered at the chamber angle. Maximum transcription of MCMV immediate early 1 (IE1) was reached at 24 h in the cornea and 48 h in the iris and ciliary body. MCMV localized in aqueous humor outflow facilities and the iris from 24 h to 28 d p.i. and was detected by in situ hybridization, though it did not transcribe after 7 d p.i. TM and iris pigment epithelial cells harboring viral inclusion bodies and autophagosomes were present at 28 d p.i. These findings shed light on how and where innate and adaptive immunity reacted after MCMV was found and transcribed in a highly ordered cascade, as well as pathogenetic changes in TM as a result of virus and uveitis behaviors.

Morroniside Ameliorates Endotoxin-Induced Uveitis by Regulating the M1/M2 Polarization Balance of Macrophages

Background

Inflammation is closely associated with the pathogenesis of various ocular diseases. Uveitis is a condition characterized by the inflammation of the uvea and ocular tissues that causes extreme pain, decreases visual acuity, and may eventually lead to blindness. The pharmacological functions of morroniside, isolated from Cornus officinalis, are multifarious. Morroniside exerts various therapeutic effects, e.g., it ameliorates inflammation. However, the specific anti-inflammatory effect of morroniside on lipopolysaccharide-induced uveitis has not been reported widely. In this study, we investigated the anti-inflammatory effect of morroniside on uveitis in mice.

Methods

An endotoxin-induced uveitis (EIU) mouse model was constructed and treated with morroniside. The inflammatory response was observed using slit lamp microscopy, and histopathological changes were observed by hematoxylin-eosin staining. The cell count in the aqueous humor was measured using a hemocytometer. The concentrations of TNF-α, IL-6, and IL-1β in the ciliary body and retina were measured using ELISA kits. The expression of iNOS and Arg-1 in the ciliary body and retina was measured by immunofluorescence costaining, and western blotting was performed to measure the protein expression of JAK2, p-JAK2, STAT3, and p-STAT3 in the ciliary body and retina.

Results

Morroniside effectively ameliorated the inflammatory response in EIU mice. Furthermore, morroniside significantly reduced the concentrations of IL-1β, IL-6, and TNF-α in the ciliary body and retina. Morroniside treatment significantly reduced the expression of iNOS in the ciliary body and retinal tissues. It also significantly inhibited p-JAK2 and p-STAT3 expression and promoted Arg-1 expression. In addition, morroniside boosted the effect of JAK inhibitors on the above indices.

Conclusions

Collectively, these findings suggest that morroniside may protect against LPS-induced inflammation in uveitis by promoting M2 polarization through the inhibition of the JAK/STAT pathway.

Melatonin receptor agonist ramelteon alleviates experimental acute ocular inflammation via HIF-1Α/VEGF/E-NOS signaling

PURPOSE

Ramelteon (RML) is a potent, selective agonist of the high-affinity melatonin receptor 1 and 2 receptors. In addition, RML is known to have antioxidant and anti-inflammatory effects. In this study, we aimed to investigate the effects of RML on HIF-1α, VEGF and e-NOS signaling pathway in a rat model of endotoxin-induced uveitis (EIU).

METHODS

Twenty-eight Wistar albino rats were divided into 4 groups as controls, lypopolysaccharide (LPS) group (5 mg/kg i.p.), LPS  +  RML group (5 mg/kg i.p and 8 mg/kg orally, respectively) and RML group (8 mg/kg orally). EIU was induced by a single intraperitoneal LPS injection. Histopathological and genetical analyses were performed.

RESULTS

In histopathological analysis, LPS caused mild anterior uveitis characterized by increased surface area of iris leaflets and ciliary body due to edema, mild to moderate congestion, and inflammatory infiltrate 6 h following the injection. The pathological findings were reduced by RML. Higher inflammation levels seen in LPS group were significantly reduced in LPS  +  RML group. Also, HIF-1 α, eNOS and VEGF expressions increased in LPS and decreased in LPS  +  RML group.

CONCLUSION

RML treatment reversed the changes in the HIF-1α /eNOS/ VEGF signaling pathway in LPS-induced uveitis in rats, preventing the progression of the damage and showed positive effects.

Anti-Inflammatory Effects of GM1 Ganglioside on Endotoxin-Induced Uveitis in Rats

Exogenous ganglioside GM1 has been reported to exert an immunomodulatory effect. We investigated the anti-inflammatory effect of GM1 ganglioside on endotoxin-induced uveitis (EIU) in rats and RAW 264.7 macrophages. Methods: EIU was induced in Lewis rats by administering a subcutaneous injection of lipopolysaccharide (LPS). GM1 was injected intraperitoneally for three consecutive days prior to the LPS injection. Twenty-four hours after the LPS injection, the integrity of the blood-aqueous barrier was evaluated by determining the protein concentration and number of infiltrating cells in the aqueous humor (AqH). Immunohistochemical and Western blot analyses of the iris-ciliary body (ICB) were performed to evaluate the effect of GM1 on the LPS-induced expression of cyclooxygenase-2 (COX-2) and intercellular adhesion molecule-1 (ICAM-1). The effect of GM1 on proinflammatory mediators and signaling cascades was examined in LPS-stimulated RAW 264.7 cells using Western blotting and immunofluorescence staining to further clarify the underlying anti-inflammatory mechanism. Results: GM1 significantly reduced the protein concentration and number of infiltrating cells in the AqH of rats with EIU. GM1 also decreased the LPS-induced expression of the ICAM-1 and COX-2 proteins in the ICB. In RAW 264.7 cells, GM1 inhibited the proinflammatory mediators induced by LPS, including inducible nitric oxide synthase (iNOS), COX-2, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and this inhibitory effect was potentially mediated by suppressing transforming growth factor-β-activated kinase 1 (TAK1) and reactive oxygen species (ROS)-mediated activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs). Conclusions: Based on this study, GM1 may be a potential anti-inflammatory agent for ocular inflammatory diseases.

Anti-inflammatory Effects of GTE in Eye Diseases

Ocular inflammation is a common complication of various eye diseases with wide consequences from irritations to potentially sight-threatening complications. Green tea is a popular beverage throughout the world. One of the proven health benefits of consuming green tea extract (GTE) is anti-inflammation. Catechins are the biologically active constituents of GTE. In in vitro and in vivo studies, GTE and catechins present inhibition of inflammatory responses in the development of ocular inflammation including infectious, non-infectious or autoimmune, and oxidative-induced complications. Research on the ocular inflammation in animal models has made significant progress in the past decades and several key disease mechanisms have been identified. Here we review the experimental investigations on the effects of GTE and catechins on various ocular inflammation related diseases including glaucoma, age-related macular degeneration, uveitis and ocular surface inflammation. We also review the pharmacokinetics of GTE constituents and safety of green tea consumption. We discuss the insights and perspectives of these experimental results, which would be useful for future development of novel therapeutics in human.

Investigation of effect of nintedanib in experimental uveitis model

PURPOSE

This study aims to investigate the protective efficacy of nintedanib in experimental uveitis induced by endotoxins.

MATERIALS AND METHODS

In this study, 24 Wistar albino rats were randomly divided into three groups: Group I was the healthy control with no uveitis that did not receive any treatment, Group II (sham) group did not receive treatment, and Group III (nintedanib) received oral nintedanib for 10 days. On the 10th day, endotoxin-induced uveitis (EIU) was induced by lipopolysaccharide (LPS) injection in Groups II and III. The clinical activity score was evaluated in all groups at the 24th hour, when uveitis formation was thought to be the most intense after LPS injection. All rats were then killed via anaesthesia. Tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) levels were measured in their right eyes using the enzyme-linked immunosorbent assay (ELISA) method. Further, histopathological examinations were performed on their left eyes.

RESULTS

For Groups I, II, and III, the IL-6 levels were 30.88 ± 1.79, 36.77 ± 1.21, and 30.93 ± 3.96 mg/pr, respectively, and TNF-α levels were 50.20 ± 3.24, 59.87 ± 2.98, and 50.23 ± 4.83 mg/pr, respectively. IL-6, TNF-α levels and clinical activity score were higher in the sham group compared to the other groups, and it decreased significantly in the treatment group (p < 0.05). Intense inflammatory cell infiltration of the ciliary body, edema and hyperaemia were evident in the sham group compared to the healthy control group (p < 0.05). These pathological findings were significantly decreased in the treatment group compared to the sham group (p < 0.05).

CONCLUSION

Nintedanib may be preferable as a new agent for treating non-infectious uveitis. However, further studies are needed to evaluate its long-term effects, effects on other antiinflammatory pathways, side-effects, and ideal dose optimization.

Anti-Inflammatory Effect of Tacrolimus/Hydroxypropyl-β-Cyclodextrin Eye Drops in an Endotoxin-Induced Uveitis Model

Background: Uveitis is an infrequent disease which constitutes a major cause of ocular morbidity. Correct management is essential, being corticosteroids its cornerstone. In case of contraindication to corticosteroids or treatment failure, the use of topical tacrolimus (TAC) could be an alternative which has already demonstrated safety and effectiveness in other ocular pathologies. However, TAC eye drops are not marketed, thus their elaboration must be carried out in Hospital Pharmacy Departments (HPDs). Methods: 32 Sprague-Dawley rats were divided into 4 groups of 8 rats each: (a) untreated healthy rats (Healthy); (b) untreated Endotoxin-Induced Uveitis model-rats (EIU); (c) EIU-rats treated with standard treatment of dexamethasone ophthalmic drops (DXM) and (d) EIU-rats treated with TAC-hydroxypropyl-β-cyclodextrin eye drops previously developed by our group (TAC-HPβCD). The mRNA expression levels of IL-6, IL-8, MIP-1α and TNF-α, quantitative analysis of leucocytes in aqueous humor and histological evaluation were performed. Results: TAC-HPβCD eye drops demonstrated to reduce ocular inflammation, expression of IL-6, TNF-α, MIP-1α and leukocyte infiltration in aqueous humor. Conclusions: TAC-HPβCD eye drops showed beneficial effect in EIU model in rats, positioning as an alternative for uveitis treatment in case of corticosteroids resistance or intolerance.

Beta-adrenergic glaucoma drugs reduce lymphatic clearance from the eye: A sequential photoacoustic imaging study

Our study aims to determine whether the beta-adrenergic system is involved in the regulation of lymphatic drainage from the eye. For this purpose, we assessed the effect of 2 topical beta-adrenergic blockers, timolol and betaxolol, commonly used as glaucoma drugs, on lymphatic clearance of albumin from the aqueous humor to neck lymph nodes. Adult mice were treated with either topical timolol, a non-selective β-blocker, 0.5% (n = 8), or topical betaxolol, a selective β₁-adrenergic blocker, 0.5% (n = 6) twice daily for 14 days and compared to respective control groups (n = 5 and n = 7). Changes in lymphatic clearance from the eye were assessed using a quantitative in vivo photoacoustic imaging approach. In all subjects, right eye and neck lymph nodes were longitudinally assessed by sequential photoacoustic imaging just prior to near-infrared dye injection into the anterior chamber of the eye, and 20 min, 2 and 4 h after injection. Repeat measurements of mean pixel intensities (MPIs) of right eyes and nodes were performed at all timepoints. The areas under the curves (AUC) were calculated and the AUC of the treated-group was compared to that of controls using the Mann-Whitney U test. The slopes of MPI of each region of interest over time were compared using the linear mixed model after adjusting for IOP decrease after treatment and other parameters such as sex and body weight. In the timolol-treated group, right neck nodes showed significant decrease in AUC signal intensity compared with controls (P = 0.003), and significant decrease in slope of MPI compared with controls (P = 0.0025). In the betaxolol-treated group, right neck nodes showed significant decrease in AUC signal intensity compared with controls (P = 0.02), and significant decrease in slope of MPI compared with controls (P = 0.0069). Topical treatment with timolol and betaxolol reduced lymphatic clearance of albumin from the aqueous humor to the neck lymph nodes. This finding may be relevant for the management of secondary glaucomas and inflammatory eye disease in which the clearance of accumulated proteins and antigen from the eye is important to disease recovery and sight protection. This study suggests that the beta-adrenergic system plays a role in the regulation of lymphatic clearance from the eye.

Corneal Application of R9-SOCS1-KIR Peptide Alleviates Endotoxin-Induced Uveitis

Purpose

Uveitis is an ocular inflammation that can affect individuals of all ages and is a major cause of blindness. We have tested the therapeutic efficacy of a cell penetrating peptide from the kinase inhibitory region of suppressor of cytokine signaling 1, denoted as R9-SOCS1-KIR.

Methods

We stimulated J774A.1 cells with lipopolysaccharide (LPS) in the presence of R9-SOCS1-KIR or its inactive control peptide. Effect on inflammatory pathways was followed by the nuclear translocation of nuclear factor κB p65 subunit and phosphorylated-p38. Synthesis of inflammatory markers induced by LPS was tested by reverse transcriptase polymerase chain reaction, Western blot analysis, and ELISA of cell supernatants. We monitored effects on the barrier properties of a differentiated ARPE-19 monolayer treated with LPS. We treated C57BL/6 mice topically with either R9-SOCS1-KIR or vehicle and injected their eyes intravitreally with LPS. Eyes were analyzed by fundoscopy, fluorescein angiography, optical coherence tomography, histology, Western blotting, multiplex enzyme-linked immunosorbent assay, and flow cytometry.

Results

Treatment with R9-SOCS1-KIR resulted in suppression of signaling through nuclear factor κB and p-p38 pathways. R9-SOCS1-KIR suppressed the expression of inflammatory genes, the secretion of inflammatory makers such as nitric oxide, and IL-1β induced by LPS. Increased permeability of retinal pigment epithelial cell monolayers was prevented. Corneal administration of R9-SOCS1-KIR blocked the acute inflammation observed in LPS-injected mouse eyes.

Conclusions

Treatment with R9-SOCS1-KIR alleviated the inflammatory responses in cell culture. Topical delivery of this peptide on mouse eyes protected against LPS-induced damage.

Translational Relevance

Topical delivery of R9-SOCS1-KIR peptide allows the patient to self-administer the drug, while preventing any systemic effects on unrelated organs.

Polymer-free corticosteroid dimer implants for controlled and sustained drug delivery

Polymeric drug carriers are widely used for providing temporal and/or spatial control of drug delivery, with corticosteroids being one class of drugs that have benefitted from their use for the treatment of inflammatory-mediated conditions. However, these polymer-based systems often have limited drug-loading capacity, suboptimal release kinetics, and/or promote adverse inflammatory responses. This manuscript investigates and describes a strategy for achieving controlled delivery of corticosteroids, based on a discovery that low molecular weight corticosteroid dimers can be processed into drug delivery implant materials using a broad range of established fabrication methods, without the use of polymers or excipients. These implants undergo surface erosion, achieving tightly controlled and reproducible drug release kinetics in vitro. As an example, when used as ocular implants in rats, a dexamethasone dimer implant is shown to effectively inhibit inflammation induced by lipopolysaccharide. In a rabbit model, dexamethasone dimer intravitreal implants demonstrate predictable pharmacokinetics and significantly extend drug release duration and efficacy (>6 months) compared to a leading commercial polymeric dexamethasone-releasing implant.

Protective effect of filgotinib in rat endotoxin-induced uveitis model

PURPOSE

To investigate the protective effect of filgotinib in endotoxin-induced uveitis model in rats.

MATERIALS AND METHOD

This study used 24 Wistar Albino rats. Group I (control group) included the healthy controls; in Group II (sham group), only 300 µg/kg intraperitoneal (ip) lipopolysaccharide (LPS) was administered; and in Group III (treatment group), 3 mg/kg/day filgotinib was administered orally for 10 days followed by 300 µg/kg ip LPS. In all groups, clinical activity scores were evaluated after 24 h. Moreover, histopathological and immunological examinations were performed.

RESULTS

In Groups I, II, and III, the mean clinical activity and histopathological examination scores were 0.00, 3.25 ± 0.70, and 1.89 ± 0.60 and 0.00, 2.88 ± 1.12, and 1.44 ± 0.52, respectively. The clinical activity and histopathological examination scores were significantly increased in the sham group compared to the control group (p < 0.05); these findings were significantly reduced in the treatment group (p < 0.05). The mean TNF-α and IL-6 ELISA levels in all groups were 50.20 ± 3.24, 59.87 ± 2.98, and 54.34 ± 4.62 and 30.88 ± 1.79, 36.77 ± 1.21, and 33.66 ± 1.86, respectively. The TNF-α and IL-6 ELISA levels were significantly decreased in the treatment group compared to the sham group (p < 0.05); there was no significant difference between the treatment group and the control group (p = 0.105, p = 0.067, respectively) CONCLUSION: Filgotinib may be an alternative treatment option in preventing the development of noninfectious uveitis.

Drops of Lactiplantibacillus plantarum CRL 759 culture supernatant attenuates eyes inflammation induced by lipopolysaccharide

Anti-inflammatory effect of soluble secreted compounds of probiotic bacteria was widely demonstrated as therapy for different inflammatory diseases, but was not investigated in inflammatory eye disorders. The aim of this study was to determine whether Lactiplantibacillus plantarum CRL759 cell-free supernatant reduced inflammatory parameters and clinical signs in ocular inflammations. First, we evaluated the effect of L. plantarum CRL759 supernatant in vitro on human retinal cell line, ARPE-19 cells, stimulated with lipopolysaccharide (LPS). Then, we investigated in vivo its capacity to decrease inflammation by local administration on the eyes of mice with endotoxin induced inflammation. In vitro assays demonstrated that L. plantarum CRL759 supernatant reduced the production of interleukin (IL)-6, IL-8, nitric oxide and thiobarbituric acid reactive substances in LPS-stimulated ARPE-19 cells. Our in vivo data proved that L. plantarum supernatant significantly reduced the clinical score of endotoxin treated mice and diminished levels of tumour necrosis factor alpha, interferon gamma and protein concentration in aqueous humour. Histological examination showed reduction of infiltrating inflammatory cells in the posterior segment of the eyes. As far as we know, this is the first report showing that Lactobacillus spp. supernatant administered as drops reduces some parameters of ocular inflammation. This promising strategy is safe and could alleviate symptoms and signs of ocular inflammation in people that are refractories to the conventional therapies.

The Protective Effect of Low Dose of Lipopolysaccharide Pretreatment on Endotoxin-Induced Uveitis in Rats Is Associated with Downregulation of CSF-1 and Upregulation of LRR-1

Purpose

To observe the effect of low dose of lipopolysaccharide (LPS) pretreatment on the expression of CSF-1 and LRR-1 in rats with endotoxin-induced uveitis (EIU), and to explore the possible role of TLR4.

Method

EIU was induced by a single subcutaneous injection of 200 μg LPS. For the endotoxin tolerance group, the induction of EIU was preceded by a daily subcutaneous injection of 0.1 mg/kg LPS for five days. Clinical scores were graded at 24 h after EIU under a slit lamp microscope. HE stain was performed to observe the histopathology. The concentrations of IL-17, INF-γ, and IL-6 in aqueous humor were quantified with enzyme-linked immunosorbent assay. Real-time PCR, Western blot, and immunofluorescence analysis were used to determine the expression of NF-κB P65 and the activation of CSF-1, LRR-1.

Results

: Low dose of LPS pretreatment produced a suppressive effect by significantly reducing the inflammatory reaction of anterior segment as measured by slit lamp and histopathology. It also significantly reduced the concentrations of IL-17, INF-γ, and IL-6 in aqueous humor and the expression of CSF-1 and NF-κB P65, while increased the expression of LRR-1 compared to the EIU group.

Conclusions

Low dose of LPS pretreatment can ameliorate endotoxin-induced uveitis in rats. This protection may be associated with upregulation of LRR-1 and downregulation of CSF-1, which is regulated by TLR4 signaling pathway.

Age-related decline of lymphatic drainage from the eye: A noninvasive in vivo photoacoustic tomography study

We aim to determine whether lymphatic drainage from the eye changes with age. Using quantitative photoacoustic tomography, groups of young and older mice were studied in the live state. 10 CD-1 mice of 2-3 months (5M/5F) were studied in addition to 13 older mice of 12-13 months (6M/7F). In each of 23 mice, near-infrared tracer (a near-infrared dye, QC-1 conjugated with Bovine Serum Albumin) was injected into the right eye, and imaging of ipsilateral cervical lymph nodes was performed with laser pulses at 11 different wavelengths prior to and 20 min, 2, 4 and 6 h after injection. Mean pixel intensities (MPIs) of nodes were calculated at each imaging session. The areas under the curves (AUC) were calculated for both groups of mice and compared using the t-test. The slopes of MPI of each region of interest were compared using the linear mixed model before and after adjusting for sex, body weight and intraocular pressure of the right eye. The mean intraocular pressure of right eyes before injection was similar in older and younger groups (12.77 ± 2.01 mmHg and 12.90 ± 2.38 mmHg, respectively; p = 0.888). In each mouse, the photoacoustic signal was detected in the right cervical lymph nodes at the 2-h time point following tracer injection into the right eye. At the 4 and 6 h imaging times, a steady increase of tracer signal was observed. Areas under the curve in the right cervical nodes were decreased significantly in older mice compared to younger mice (p = 0.007). The slopes of MPI in the nodes were significantly decreased in old mice compared to young mice both before and after adjusting for sex, body weight and intraocular pressure of the right eye (p = 0.003). In conclusion, lymphatic drainage from the eye is significantly reduced in older eyes. This finding suggests that impaired lymphatic clearance of aqueous humor, proteins and antigens from the eye may contribute to age-related disease of the eye such as glaucoma and inflammatory eye disease.

Synthetic Glucocorticoid-Induced Leucine Zipper Peptide Inhibits Lipopolysaccharide-Induced Ocular Inflammation in Rats

PURPOSE

To demonstrate the anti-inflammatory action of a synthetic glucocorticoid-induced leucine zipper (GILZ98-134) peptide (GILZ-p) in a model of endotoxin-induced uveitis (EIU) in rats.

METHODS

The EIU model was induced in Sprague Dawley rats with an intravitreal injection of lipopolysaccharide (LPS). Synthetic GILZ-p was injected intravitreally 6 h after the LPS injection. To evaluate the anti-inflammatory effects of GILZ-p, the inflammatory response in the anterior chamber and iris of the rat eyes was evaluated with a slitlamp microscope on days 0, 1, 2, 3, and 4 after GILZ-p injection. The retinal expression of inflammatory cytokines was measured on days 0, 1, 2, 3, and 4 after GILZ-p injection. Müller cell gliosis was also detected at planned time points after GILZ-p injection.

RESULTS

Anterior segment inflammation peaked at 24 h after LPS injection in the EIU model. Compared with the controls, intravitreal GILZ-p significantly suppressed LPS-induced anterior segment inflammation in the EIU rats. The levels of retinal inflammatory factors IL-1β, TNF-α, MCP-1, and ICAM-1 were simultaneously reduced by the intravitreal GILZ-p injection. The expression of vimentin in the EIU retina was significantly reduced by GILZ-p, and the downregulated aquaporin 4 in the EIU retina was significantly restored by GILZ-p.

CONCLUSION

The synthetic GILZ-p inhibited the inflammatory reaction in the EIU model and may have utility in the treatment of inflammatory ocular disease.