Differences in the Quantity and Composition of Extracellular Vesicles in the Aqueous Humor of Patients with Retinal Neovascular Diseases.

Extracellular vesicles (EVs) are secreted by various cells in the body fluid system and have been found to influence vessel formation and inflammatory responses in a variety of diseases. However, which EVs and their subtypes are involved in vascular retinal diseases is still unclear. Therefore, the aim of this study was to explore the particle distribution of EVs in retinal neovascular diseases, including age-related macular degeneration, polypoidal choroidal vasculopathy, and central retinal vein occlusion. The aqueous humor was harvested from 20 patients with different retinal neovascular diseases and six patients with cataracts as the control group. The particle distribution was analyzed using nanoparticle tracking analysis (NTA) and transmitting electron microscopy (TEM). The results revealed that the disease groups had large amounts of EVs and their subtypes compared to the control group. After isolating exosomes, a higher expression of CD81+ exosomes was shown in the disease groups using flow cytometry. The exosomes were then further classified into three subtypes of exomeres, small exosomes, and large exosomes, and their amounts were shown to differ depending on the disease type. To the best of our knowledge, this is the first study to elucidate the dynamics of EVs in retinal neovascular diseases using clinical cases. Our findings demonstrated the possible functionality of microvesicles and exosomes, indicating the potential of exosomes in the diagnosis and therapy of retinal neovascular diseases.

Quercetin Alleviates the Accumulation of Superoxide in Sodium Iodate-Induced Retinal Autophagy by Regulating Mitochondrial Reactive Oxygen Species Homeostasis through Enhanced Deacetyl-SOD2 via the Nrf2-PGC-1α-Sirt1 Pathway.

Oxidative damage of retinal pigment epithelium (RPE) cells plays an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Quercetin, a bioactive flavonoid compound, has been shown to have a protective effect against oxidative stress-induced cell apoptosis and inflammation in RPE cells; however, the detailed mechanism underlying this protective effect is unclear. Therefore, the aim of this study was to investigate the regulatory mechanism of quercetin in a sodium iodate (NaIO3)-induced retinal damage. The clinical features of the mice, the production of oxidative stress, and the activity of autophagy and mitochondrial biogenesis were examined. In the mouse model, NaIO3 treatment caused changes in the retinal structure and reduced pupil constriction, and quercetin treatment reversed the oxidative stress-related pathology by decreasing the level of superoxide dismutase 2 (SOD2) while enhancing the serum levels of catalase and glutathione. The increased level of reactive oxygen species in the NaIO3-treated ARPE19 cells was improved by treatment with quercetin, accompanied by a reduction in autophagy and mitochondrial biogenesis. Our findings indicated that the effects of quercetin on regulating the generation of mtROS were dependent on increased levels of deacetyl-SOD2 through the Nrf2-PGC-1α-Sirt1 signaling pathway. These results demonstrated that quercetin may have potential therapeutic efficacy for the treatment of AMD through the regulation of mtROS homeostasis.

Protective Effect of Quercetin on Sodium Iodate-Induced Retinal Apoptosis through the Reactive Oxygen Species-Mediated Mitochondrion-Dependent Pathway.

Age-related macular degeneration (AMD) leads to gradual central vision loss and is the third leading cause of irreversible blindness worldwide. The underlying mechanisms for this progressive neurodegenerative disease remain unclear and there is currently no preventive treatment for dry AMD. Sodium iodate (NaIO3) has been reported to induce AMD-like retinal pathology in mice. We established a mouse model for AMD to evaluate the effects of quercetin on NaIO3-induced retinal apoptosis, and to investigate the pertinent underlying mechanisms. Our in vitro results indicated that quercetin protected human retinal pigment epithelium (ARPE-19) cells from NaIO3-induced apoptosis by inhibiting reactive oxygen species production and loss of mitochondrial membrane potential as detected by Annexin V-FITC/PI flow cytometry. We also evaluated the relative expression of proteins in the apoptosis pathway. Quercetin downregulated the protein expressions of Bax, cleaved caspase-3, and cleaved PARP and upregulated the expression of Bcl-2 through reduced PI3K and pAKT expressions. Furthermore, our in vivo results indicated that quercetin improved retinal deformation and increased the thickness of both the outer nuclear layer and inner nuclear layer, whereas the expression of caspase-3 was inhibited. Taken together, these results demonstrate that quercetin could protect retinal pigment epithelium and the retina from NaIO3-induced cell apoptosis via reactive oxygen species-mediated mitochondrial dysfunction, involving the PI3K/AKT signaling pathway. This suggests that quercetin has the potential to prevent and delay AMD and other retinal diseases involving NaIO3-mediated apoptosis.

Development of Nanosome-Encapsulated Honokiol for Intravenous Therapy Against Experimental Autoimmune Encephalomyelitis.

BACKGROUND: Honokiol has been reported to possess anti-inflammatory and neuroprotective activities. However, the poor aqueous solubility of honokiol limits its clinical application for systemic administration. PURPOSE: This study aims to develop a novel formulation of nanosome-encapsulated honokiol (NHNK) for intravenous therapy against mouse experimental autoimmune encephalomyelitis (EAE) that mimics human multiple sclerosis. METHODS: Nanosomes and NHNK were prepared by using an ultra-high pressure homogenization (UHPH) method. Mice were treated with NHNK or empty nanosomes during the peak phase of EAE symptoms. Symptoms of EAE were monitored and samples of the spinal cord were obtained for histopathological examinations. RESULTS: The stock of NHNK containing honokiol in the nanosome formulation, which showed the structure of single phospholipid bilayer membranes, was well formulated with the particle size of 48.0 ± 0.1 nm and the encapsulation efficiency 58.1 ± 4.2%. Intravenous administration of NHNK ameliorated the severity of EAE accompanied by a significant reduction of demyelination and inflammation in the spinal cord. Furthermore, NHNK decreased the number of IL-6+, Iba-1+TNF +, Iba-1+IL-12 p40+, and CD3+IFN-γ+ cells infiltrating the spinal cord. CONCLUSION: The UHPH method simplified the preparation of NHNK with uniformly distributed nanosize and high encapsulation efficiency. Intravenous administration of NHNK ameliorated the severity of EAE by suppressing the infiltration of activated microglia and Th1 cells into the spinal cord. Collectively, these results suggest that the formulation of NHNK is a prospective therapeutic approach for inflammatory CNS diseases, such as multiple sclerosis.

Systemic exposure to a single dose of ferucarbotran aggravates neuroinflammation in a murine model of experimental autoimmune encephalomyelitis.

BACKGROUND: Medicinal preparations of iron oxide nanoparticles (IONPs) have been used as MRI contrast agents for the diagnosis of hepatic tumors and the assessment of neuroinflammation and blood-brain barrier integrity. However, it remains mostly unclear whether exposure to IONPs affects neuroinflammation under disease conditions. The present study aims to investigate the impact of IONPs on autoimmune-mediated neuroinflammation using a murine model of experimental autoimmune encephalomyelitis (EAE) that mimics human multiple sclerosis. METHODS: Mice were either left untreated or immunized with myelin oligodendrocyte glyco-protein on day 0 followed by two injections of pertussis toxin for EAE induction. The EAE mice were intravenously administered with a single dose of the carboxydextran-coated IONPs, ferucarbotran (20 mg Fe/kg) and/or saline (as vehicle) on day 18. Symptoms of EAE were daily monitored until the mice were killed on day 30. Tissue sections of the brain and spinal cord were prepared for histopathological examinations. Iron deposition, neuron demyelination and inflammatory cell infiltration were examined using histochemical staining. The infiltration of microglial and T cells, and cytokine expression were examined by immunohistochemical staining and/or reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Iron deposition was detected in both the brain and spinal cord of EAE mice 3 days post-ferucarbotran treatment. The clinical and pathological scores of EAE, percentage of myelin loss and infiltration of inflammatory cells into the spinal cord were significantly deteriorated in EAE mice treated with ferucarbotran. Furthermore, ferucarbotran treatment increased the number of CD3+, Iba-1+, IL-6+, Iba-1+TNF-α+ and CD3+IFN-γ+ cells in the spinal cord of EAE mice. CONCLUSION: A single exposure to ferucarbotran exacerbated neuroinflammation and disease severity of EAE, which might be attributed to the enhanced activation of microglia and T cells. These results demonstrated that the pro-inflammatory effect of ferucarbotran on the central nervous system is closely associated with the deterioration of autoimmunity.

Iron oxide nanoparticles attenuate T helper 17 cell responses in vitro and in vivo.

Iron oxide nanoparticles (IONPs) have been shown to attenuate T helper (Th)1 and Th2 cell-mediated immunity in ovalbumin (OVA)-sensitized mice. The objective of this study is to investigate the effects of IONPs on the immune responses of Th17 cells, a subset of T cells involved in various inflammatory pathologies. For in vivo study, a murine model of delayed-type hypersensitivity (DTH) was employed. BALB/c mice received a single dose of IONPs (0.2-10 mg iron/kg) via the tail vein 1 h prior to ovalbumin (OVA) sensitization. Their footpads were subcutaneously challenged with OVA to induce DTH reactions. The expression of Th17 cell-related molecules in inflamed footpads were examined by immunohistochemistry. For in vitro study, OVA-primed splenocytes were directly exposed to IONPs (1-100 µg iron/mL), and then re-stimulated with OVA in culture. The expression of Th17 cell-related molecules were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. IONP administration attenuated the number of interleukin (IL)-6, IL-17, the transcription factor ROR-γ, and chemokine receptor 6 positive cells in OVA-challenged footpads, whereas the number of transforming growth factor-ß, IL-23 and chemokine (C-C motif) ligand 20 positive cells was not altered. Direct exposure of OVA-primed splenocytes to IONPs suppressed the production of IL-6 and IL-17, and the mRNA expression of IL-17 and ROR-γt. These data indicate that exposure to IONPs attenuates Th17 cell responses in vivo and in vitro.