Regulatory T cell intravitreal delivery using hyaluronan methylcellulose hydrogel improves therapeutic efficacy in experimental autoimmune uveitis.

Autoimmune uveitis refers to several intraocular inflammation conditions, which are mediated by autoreactive T cells. Regulatory T cells (Tregs) are immunosuppressive cells that have shown potential for resolving various autoimmune diseases, including uveitis. However, poor donor cell dispersion distal to the injection site and plasticity of Treg cells in an inflammatory microenvironment can present obstacles for this immunotherapy. We assessed the use of a physical blend of hyaluronan and methylcellulose (HAMC) as immunoprotective and injectable hydrogel cell delivery system to improve the efficacy of Treg-based therapy in treating experimental autoimmune uveitis (EAU). We demonstrated that the Treg-HAMC blend increased both the survival and stability of Tregs under proinflammatory conditions. Furthermore, we found that the intravitreal HAMC delivery system resulted in a two-fold increase in the number of transferred Tregs in the inflamed eye of EAU mice. Treg-HAMC delivery effectively attenuated ocular inflammation and preserved the visual function of EAU mice. It significantly decreased the number of ocular infiltrates, including the uveitogenic IFN-γ+CD4+ and IL-17+CD4+ T cells. In contrast, intravitreal injection of Treg cells without HAMC only achieved marginal therapeutic effects in EAU. Our findings suggest that HAMC may become a promising delivery vehicle for human uveitis Treg therapy.

Induction of antigen-specific Treg cells in treating autoimmune uveitis via bystander suppressive pathways without compromising anti-tumor immunity.

BACKGROUND: Induction of autoantigen-specific Treg cells that suppress tissue-specific autoimmunity without compromising beneficial immune responses is the holy-grail for immunotherapy to autoimmune diseases. METHODS: In a model of experimental autoimmune uveitis (EAU) that mimics human uveitis, ocular inflammation was induced by immunization with retinal antigen interphotoreceptor retinoid-binding protein (IRBP). Mice were given intraperitoneal injection of αCD4 antibody (Ab) after the onset of disease, followed by administration of IRBP. EAU was evaluated clinically and functionally. Splenocytes, CD4+CD25- and CD4+CD25+ T cells were sorted and cultured with IRBP or αCD3 Ab. T cell proliferation and cytokine production were assessed. FINDINGS: The experimental approach resulted in remission of ocular inflammation and rescue of visual function in mice with established EAU. Mechanistically, the therapeutic effect was mediated by induction of antigen-specific Treg cells that inhibited IRBP-driven Th17 response in TGF-ß and IL-10 dependent fashion. Importantly, the Ab-mediated immune tolerance could be achieved in EAU mice by administration of retinal autoantigens, arrestin but not limited to IRBP only, in an antigen-nonspecific bystander manner. Further, these EAU-suppressed tolerized mice did not compromise their anti-tumor T immunity in melanoma model. INTERPRETATION: We successfully addressed a specific immunotherapy of EAU by in vivo induction of autoantigen-specific Treg cells without compromising host overall T cell immunity, which should have potential implication for patients with autoimmune uveitis. FUNDING: This study was supported by the Natural Science Foundation of Guangdong Province and the Fundamental Research Fund of the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center.

Crocetin and Its Glycoside Crocin, Two Bioactive Constituents From Crocus sativus L. (Saffron), Differentially Inhibit Angiogenesis by Inhibiting Endothelial Cytoskeleton Organization and Cell Migration Through VEGFR2/SRC/FAK and VEGFR2/MEK/ERK Signaling Pathways.

Crocetin and crocin are two important carotenoids isolated from saffron (Crocus sativus L.), which have been used as natural biomedicines with beneficial effects for improving the suboptimal health status associated with abnormal angiogenesis. However, the anti-angiogenic effects and underlying mechanisms of the effects of crocetin and crocin have not been investigated and compared. The anti-angiogenic effects of crocetin and crocin were tested on human umbilical vein endothelial cells (HUVECs) in vitro, and in zebrafish in vivo. In vivo, crocetin (20 µM) and crocin (50 and 100 µM) significantly inhibited subintestinal vein vessels formation, and a conversion process between them existed in zebrafish, resulting in a difference in their effective concentrations. In the HUVEC model, crocetin (10, 20 and 40 µM) and crocin (100, 200 and 400 µM) inhibited cell migration and tube formation, and inhibited the phosphorylation of VEGFR2 and its downstream pathway molecules. In silico analysis further showed that crocetin had a higher ability to bind with VEGFR2 than crocin. These results suggested that crocetin was more effective than crocin in inhibiting angiogenesis through regulation of the VEGF/VEGFR2 signaling pathway. These compounds, especially crocetin, are potential candidate natural biomedicines for the management of diseases associated with abnormal blood vessel growth, such as age-related macular degeneration.