Yiguo Qiu

Activation of liver X receptor alleviates ocular inflammation in experimental autoimmune uveitis.

PURPOSE To investigate whether a synthetic LXR agonist TO901317 (TO90) ameliorates ocular inflammation in a mouse model of experimental autoimmune uveitis (EAU) and to explore its underlying mechanism. METHODS EAU was induced with subcutaneous injection of IRBP161-180 peptide (SGIPYIISYLHPGNTILHVD) in B10.RIII mice. TO90 (50 mg/kg/d) or vehicle was administrated orally for successive 16 days or 8 days as prevention or effector phase, respectively. The severity of EAU was evaluated with clinical and histological scores. The levels of LXRs, NF-κB subunit p65, and an LXR target gene ABCA1 in the retina were detected with real-time PCR and Western blotting. The expressions of proinflammatory genes, including TNF-α, IL-1β, IL-6, MCP-1, IFN-γ, and IL-17, were detected by real-time PCR. IRBP-specific lymphocyte proliferation was detected by MTT. Intracellular IFN-γ and IL-17 in CD4(+) T cells were measured by flow cytometry. RESULTS We found both LXRα and LXRβ were expressed in mouse retina. After administering TO90 orally to B10.RIII mice, the expression of LXRα but not LXRβ was upregulated in the naïve mice. Compared with naïve mice, LXRα expression was increased in vehicle and TO90-treated EAU mice, but the LXRβ expression was unchanged. The protein level of ABCA1 was enhanced in TO90-treated naïve and EAU mice but was unchanged in vehicle-treated EAU mice, suggesting activation of LXRα by TO90 is ligand dependent. TO90-mediated activation of LXRα improved the clinical and morphological scores in EAU mice. Meanwhile, activation of LXRα decreased the expressions of proinflammatory cytokines, including TNF-α, IL-1β, IL-6, MCP-1, IFN-γ, and IL-17 in the retina. TO90 treatment inhibited IRBP-specific immune responses. The proportions of Th1 and Th17 expressing IFN-γ and IL-17 were reduced in TO90-treated EAU mice in both prevention and effector phases. Furthermore, TO90 significantly downregulated the expressions of an NF-κB subunit p65 at the protein and mRNA levels. CONCLUSIONS TO90 activates LXRα and potently attenuates ocular inflammation in EAU. Alleviation of ocular inflammation could partially result from inhibition of the NF-κB signaling pathway. TO90 reduces IFN-γ and IL-17 expression in both prevention and treatment scenarios. Our data suggest that the LXR agonist may become a novel class of therapeutic agent for autoimmune uveitis.

Downregulating p22phox ameliorates inflammatory response in Angiotensin II-induced oxidative stress by regulating MAPK and NF-κB pathways in ARPE-19 cells

Oxidative stress and inflammation are two interrelated biological events implicated in the pathogenesis of many diseases. Reactive oxygen species (ROS) produced under oxidative stress play a key role in pathological conditions. Inhibition of p22phox, an indispensable component of the NADPH oxidase (NOX) complex comprising the main source of ROS, plays a protective role in many ocular conditions by inhibiting the activation of NOXs and the generation of ROS. However, little is understood regarding the role of p22phox in oxidative stress-related inflammation in the eye. We used a p22phox small interfering RNA (siRNA) to transfect the retinal pigment epithelium (RPE)-derived cell line ARPE-19, and human primary RPE (hRPE) cells, then stimulated with Ang II. We observed a potent anti-inflammatory effect and studied the underlying mechanism. Downregulating p22phox resulted in decreased ROS generation, a reduction of NOXs (NOX1, 2, 4) and a decrease in inflammatory cytokine. In addition, p22phox downregulation reduced the activation of the MAPK and NF-κB signaling pathways. We conclude that inhibition of p22phox has an anti-inflammatory effect in Ang II-induced oxidative stress. Suppressing the MAPK and NF-κB pathways is involved in this protective effect. These results suggest that p22phox may provide a promising therapeutic target for oxidative stress-induced ocular inflammation

Effects of Three Commonly Used Anesthetics on Intraocular Pressure in Mouse

Abstract Purpose: To investigate the effects of three commonly used general anesthetics on intraocular pressure (IOP) in mouse. Methods: Fifteen 2–3-month-old C57BL/6J mice were randomly divided into three groups (each group, n = 5). A non-invasive TonoLab tonometer (Icare LAB, Icare Finland Oy, Espoo, Finland) was used to measure IOP at 0, 5, 10, 15, 20, 30 min after mice were anesthetized, respectively, by intraperitoneal injection of sodium pentobarbital (150 mg/kg), chloral hydrate (500 mg/kg) and a mixture of ketamine and xylazine (75 mg/kg and 13.6 mg/kg). IOP were obtained in the daytime and nighttime. Anterior segment was photographed and palpebral fissure height was measured offline. Results: Immediately after anesthesia, the averaged IOPs in the three groups were 17.2 ± 1.5, 16.7 ± 1.4 and 17.3 ± 2.4 mmHg in the daytime and 19.3 ± 2.1, 21.3 ± 1.1 and 21.7 ± 1.5 mmHg in the nighttime. Thereafter, the averaged IOPs in sodium pentobarbital and chloral hydrate groups showed a trend of decline. Then IOPs became stable at 10–15 min after anesthesia. In contrast, the IOPs of ketamine and xylazine injected group increased to 23.7–25.1 mmHg at 10–15 min in the daytime and 26.1–27.7 mmHg in the nighttime. Compared to chloral hydrate and sodium pentobarbital treated mice (2.4 ± 0.1 mm, 1.7 ± 0.0 mm), ketamine and xylazine injected animals had significantly increased palpebral fissure height (3.6 ± 0.3 mm, p < 0.01). Conclusion: General anesthetics have a large impact on mouse IOP. Sodium pentobarbital and chloral hydrate reduce but the ketamine and xylazine mixture increases mouse IOP. IOP levels become stabilized at 10 to 15 min after anesthesia. The ketamine and xylazine cocktail mediated elevation of palpebral fissure height may be associated with an increasing of intraorbital pressure. Measurement performs at 10–15 min after anesthesia may obtain more reliable IOPs.

AAV8-Mediated Angiotensin-Converting Enzyme 2 Gene Delivery Prevents Experimental Autoimmune Uveitis by Regulating MAPK, NF-κB and STAT3 Pathways.

Renin angiotensin system (RAS) is a key hormonal system which regulates the cardiovascular function and is implicated in several autoimmune diseases. With the discovery of the angiotensin-converting enzyme 2 (ACE2), a protective axis of RAS namely ACE2/Ang-(1–7)/Mas that counteracts the deleterious ACE/AngII/AT1R axis has been established. This axis is emerging as a novel target to attenuate ocular inflammation. However, the underlying molecular mechanisms remain unclear. We investigated the hypothesis that enhancing the activity of the protective axis of RAS by subretinal delivery of an AAV8 (Y733F)-ACE2 vector would protect against the ocular inflammation in experimental autoimmune uveitis (EAU) mice through regulating the local immune responses. Our studies demonstrated that increased ACE2 expression exerts protective effects on inflammation in EAU mouse by modulating ocular immune responses, including the differentiation of Th1/Th17 cells and the polarization of M1/M2 macrophages; whereas the systemic immune responses appeared not affected. These effects were mediated by activating the Ang-(1–7)/Mas and inhibiting the MAPK, NF-κB and STAT3 signaling pathways. This proof-of-concept study suggests that activation of ocular ACE2/Ang-(1–7)/Mas axis with AAV gene transfer modulates local immune responses and may be a promising, long-lasting therapeutic strategy for refractory and recurrent uveitis, as well as other inflammatory eye diseases.

Amelioration of amyloid β-induced retinal inflammatory responses by a LXR agonist TO901317 is associated with inhibition of the NF-κB signaling and NLRP3 inflammasome

Amyloid β (Aβ) is a pathogenic peptide associated with many neurodegenerative diseases such as Alzheimers disease and Parkinsons disease. The retinal inflammation in response to Aβ is implicated in the pathogenesis of several ocular diseases including age-related macular degeneration, Alzheimers-related optic neuropathy and glaucoma. In the present study, we found that a single intravitreal injection of oligomeric Aβ1-40 in mouse activated the NLRP3 inflammasome and the NF-κB signaling, induced the production of inflammatory cytokines including TNF-α and IL-6. In addition, Aβ1-40 caused retinal function impairment while no noticeable morphological changes were observed under light microscope. Furthermore, immunohistochemical results showed that Aβ1-40 enhanced the number of Iba1-positive cells in the inner retina. The mRNA expressions of LXRα and LXRβ decreased in the neuroretina of the Aβ1-40-injected mice. No significant difference was found on the protein expressions of LXRs and ABCA1 in both neuroretina and RPE/choroid complex between the Aβ1-40-injected group and the control group. A synthetic LXR ligand, TO901317 (TO90), enhanced the expressions of LXRα and ABCA1 at both mRNA and protein levels in the Aβ1-40-injected mice, while the LXRβ expression was unchanged. TO90 preserved ERG a- and b-wave amplitudes and reduced the number of Iba1-positive cells in the Aβ1-40-treated retina. Furthermore, TO90 down-regulated the mRNA levels of TNF-α and IL-6, as well as the expressions of p-IκBα, NLRP3, caspase-1 and IL-1β in the Aβ1-40-injected animals. We suggest that activation of LXRα and its target gene ABCA1 exerts potent anti-inflammatory effect on the Aβ-treated retina.

Hypermethylation of Interferon Regulatory Factor 8 (IRF8) Confers Risk to Vogt-Koyanagi-Harada Disease

Aberrant methylation change of IRF8 confers risk to various tumors, and abnormal expression of IRF8 is involved in many autoimmune diseases, including ocular Behcet’s disease. However, whether the methylation change of IRF8 is associated with Vogt-Koyanagi-Harada (VKH) disease remains unknown. In the present study, we found a decreased IRF8 mRNA expression in association with a higher methylation level in monocyte-derived dendritic cells (DCs) from active VKH patients compared with the normal and inactive subjects. DCs incubated with cyclosporin a (CsA) or dexamethasone (DEX) showed a lower methylation and higher mRNA expression of IRF8 in active VKH patients. A demethylation reagent, 5-Aza-2′-deoxycytidine (DAC) showed a notable demethylation effect as evidenced by increasing the mRNA expression and reducing the methylation level of IRF8. It also suppressed the Th1 and Th17 responses through down-regulating the expression of co-stimulatory molecules (CD86, CD80, CD40), and reducing the production of pro-inflammatory cytokines (IL-6, IL-1β, IL-23, IL-12) produced by DCs. These findings shows that hypermethylation of IRF8 in DCs confers risk to VKH disease. Demethylation of IRF8 may offer a novel therapeutic strategy protect against VKH disease.

A safety study of high concentration and high frequency intravitreal injection of conbercept in rabbits

The novel anti-VEGF drug conbercept has been used in the treatment of several retinal neovascular diseases. Owning to the alteration of the structure, the newest drug is capable of combining more molecular targets and present higher affinity to the angiogenesis promoting factors. However, it is unknown whether it will cause any unwanted effects like other anti-VEGF agents. We studied the short-term safety of high concentration and high frequency intravitreal injection of conbercept in rabbits. Intraocular pressure, fundus-photography, ERGs were applied. Retinal morphology, the amount of apoptotic cells and protein levels of IL-6, IL-8 and TNF-α in the aqueous humor were determined. Retinal proteomics was detected using tandem mass tags (TMTs) quantitative mass spectrometry. The difference of IOP, ERGs, protein levels of inflammatory factors among rabbits received conbercept and PBS was not significant (P > 0.05). Fundus photographs and retinal morphology of animals in the conbercept-injected groups mimic those observed in the PBS-injected groups. No TUNEL-positive cell was seen in the retinal ganglion cell layer in the conbercept-injected groups. Proteomics did not show significant changes of inflammation or apoptosis associated proteins in the conbercept-injected eyes. We conclude that intravitreal injection of high concentration and high frequency conbercept is well tolerated at least in a short-term in rabbits.

Promoter Hypermethylation of GATA3, IL-4, and TGF-β Confers Susceptibility to Vogt-Koyanagi-Harada Disease in Han Chinese

Purpose We investigated the role of promoter methylation of transcriptional and inflammatory factors, including TBX21, GATA3, RORγt, FOXP3, IFN-γ, IL-4, IL-17A, and TGF-β in the development of Vogt-Koyanagi-Harada (VKH) disease. Methods The promoter methylation levels were detected by the Sequenom MassARRAY system in CD4+ T cells that were separated from 20 healthy individuals and 32 VKH patients (20 in the active stage without medication, 12 in inactive stage with medication). The mRNA expression level of GATA3, IL-4, and TGF-β in CD4+ T cells was analyzed by real-time RT-PCR. Results The promoter methylation levels of GATA3, IL-4, and TGF-β were significantly higher in active VKH patients than in healthy individuals (P < 0.05). A decreased mRNA expression of GATA3 and TGF-β was found in active VKH patients, which was correlated negatively with the DNA methylation of these factors. Treatment with systemic corticosteroid and cyclosporin A (CsA) decreased the methylation level of GATA3 and TGF-β in association with an increased mRNA expression of molecules and reduced disease activity. Conclusions Our findings suggest that promoter hypermethylation of GATA3 and TGF-β in CD4+ T cells confers risk to VKH disease in Han Chinese.

Overexpression of Angiotensin-Converting Enzyme 2 Ameliorates Amyloid β-Induced Inflammatory Response in Human Primary Retinal Pigment Epithelium

Purpose Amyloid-β (Aβ) is a major constituent of drusen, which is a hallmark of early AMD. The purpose of this study was to investigate whether enhancement of ACE2, an important component of the protective angiotensin-converting enzyme 2 (ACE2)/Ang-(1-7)/Mas axis of the renin angiotensin system (RAS), ameliorates Aβ-induced inflammatory response in human RPE cells. Methods Annexin-V FITC/propidium iodide assay for detecting apoptosis rate was used to determine the optimum concentration and incubation time of Aβ1-42. ACE2 plasmid was transfected into primary cultured human RPE (hRPE) and ARPE-19 cells for 6 hours followed by stimulation with Aβ1-42 at the concentration of 1 μM for 48 hours. Gene expression was detected by real-time PCR and protein levels were determined by Western blotting or ELISA. A779, an antagonist of Ang-(1-7), was used to further confirm the involvement of ACE2/Ang-(1-7)/Mas axis. Results Flow cytometry showed that the optimal concentration of Aβ1-42 was 1 μM and the optimal incubation time was 48 hours. Aβ1-42 upregulated the expression of IL-1β and monocyte chemoattractant protein-1. ACE2 plasmid significantly upregulated the expression of ACE2 and Ang-(1-7) in hRPE and ARPE-19 cells. Activation of ACE2 reduced the overproduction of inflammatory cytokines at both mRNA and protein levels in hRPE and ARPE-19 cells stimulated with Aβ1-42. Furthermore, an antagonist of Ang-(1-7), A779 reversed the anti-inflammatory effect of ACE2. Conclusions Overexpression of ACE2 ameliorates Aβ-induced inflammatory response by activating the ACE2/Ang-(1-7)/Mas axis in human RPE cells. Our data suggest that ACE2/Ang-(1-7)/Mas axis may be a promising target for developing novel therapies for inflammation response in AMD.

Ocular Behcet’s disease is associated with aberrant methylation of interferon regulatory factor 8 (IRF8) in monocyte-derived dendritic cells

Aberrant methylation of interferon regulatory factor 8 (IRF8) has been noted in various tumors. IRF8 has also been reported to be involved in many autoimmune diseases, including Behcets disease (BD). However, the methylation status of IRF8 in BD has not been reported. To address this issue, we investigated whether the degree of methylation of IRF8 in dendritic cells (DCs) plays a role in the development of BD. We found a lower mRNA expression and a higher methylation level of IRF8 in active ocular BD patients as compared to normal subjects and inactive patients. Treatment with a demethylation agent, 5-Aza-2’-deoxycytidine (DAC) resulted in an increase of mRNA expression and a reduction of the IRF8 methylation level. It also down-regulated the expression of the co-stimulatory molecules CD86, CD80, CD40, and reduced the production of IL-6, IL-1β, IL-23 and IL-12. An inhibition of Th1/Th17 responses was observed as evidenced by a decreased production of IFN-γ, IL-17, and a reduction of IFN-γ/IL-17- producing CD4+ T cells following treatment with DAC. This study shows that active ocular BD patients have an aberrant IRF8 methylation status. These findings suggest that epigenetic control of IRF8 expression may offer a future target in the treatment of ocular BD.