Synergism between corticosteroids and Rapamycin for the treatment of intraocular inflammation

Therapeutic Effect of Rapamycin-Loaded Small Extracellular Vesicles Derived from Mesenchymal Stem Cells on Experimental Autoimmune Uveitis

Autoimmune uveitis is a major cause of vision loss and glucocorticoids are major traditional medications, which may induce serious complications. Rapamycin has been demonstrated to exhibit immunosuppressive effects and is promising to be used in treating uveitis by intravitreal injection. However, repeated and frequent intravitreal injections increase the risk of severe ocular complications, while the efficacy of subconjunctival injection of rapamycin is low since it is difficult for rapamycin to penetrate eyeball. Recently, small extracellular vesicles (sEVs) have attracted considerable research interest as natural drug delivery systems that can efficiently cross tissues and biological membranes. SEVs derived from mesenchymal stem cells (MSC-sEVs) also can exert immunosuppressive effect and ameliorate experimental autoimmune uveitis (EAU). The aim of this study was to construct a Rapamycin-loaded MSC-sEVs delivery system (Rapa-sEVs) and investigate its therapeutic effect on EAU by subconjunctival injection. Rapa-sEVs were prepared by sonication and characterized by nanoparticle tracking analysis, transmission electron microscopy, and western blotting. Clinical and histological scores were obtained to assess the treatment efficacy. Additionally, T cell infiltration was evaluated by flow cytometry. The results indicated that Rapa-sEVs could reach the retinal foci after subconjunctival injection. Compared to sEVs and rapamycin alone, Rapa-sEVs can produce a more marked therapeutic effect and reduce ocular inflammatory cell infiltration. Overall, MSC-sEVs have significant potential for the delivery of rapamycin to treat EAU. Subconjunctival injection of Rapa-sEVs may be contender for efficacious steroid-sparing immunomodulatory therapy.

TOR Inhibitors Synergistically Suppress the Growth and Development of Phytophthora infestans, a Highly Destructive Pathogenic Oomycete

Phytophthora infestans, one of most famous pathogenic oomycetes, triggered the Great Irish Famine from 1845 to 1852. The target of rapamycin (TOR) is well known as a key gene in eukaryotes that controls cell growth, survival and development. However, it is unclear about its function in controlling the mycelial growth, sporulation capacity, spore germination and virulence of Phytophthora infestans. In this study, key components of the TOR signaling pathway are analyzed in detail. TOR inhibitors, including rapamycin (RAP), AZD8055 (AZD), KU-0063794 (KU), and Torin1, inhibit the mycelial growth, sporulation capacity, spore germination, and virulence of Phytophthora infestans with AZD showing the best inhibitory effects on Phytophthora infestans. Importantly, compared with a combination of RAP + KU or RAP + Torin1, the co-application of RAP and AZD show the best synergistic inhibitory effects on P. infestans, resulting in the reduced dosage and increased efficacy of drugs. Transcriptome analysis supports the synergistic effects of the combination of RAP and AZD on gene expression, functions and pathways related to the TOR signaling pathway. Thus, TOR is an important target for controlling Phytophthora infestans, and synergism based on the application of TOR inhibitors exhibit the potential for controlling the growth of Phytophthora infestans.

Rapamycin ameliorates experimental autoimmune uveoretinitis by inhibiting Th1/Th2/Th17 cells and upregulating CD4+CD25+ Foxp3 regulatory T cells

AIM

To determine the effects of rapamycin on experimental autoimmune uveoretinitis (EAU) and investigate of role of rapamycin on T cell subsets in the disease.

METHODS

EAU was induced in rats using peptides 1169 to 1191 of the interphotoreceptor binding protein (IRBP). Rapamycin (0.2 mg/kg/d) was administrated by intraperitoneal injection for a consecutive 7d after immunization. Th1/Th2/Th17 cytokines, TGF-β1, and IL-6 produced by lymphocyteswere measured by ELISA, while Th17 cells and CD4+CD25+ regulatory T cells (Tregs) from rat spleen were detected by flow cytometry.

RESULTS

Intraperitoneal treatment immediately after immunization dramatically ameliorated the clinical course of EAU. Clinical responses were associated with reduced retinal inflammatory cell infiltration and tissue destruction. Rapamycin induced suppression of Th1/Th2/Th17 cytokines, including IFN-γ, IL-2, IL-17, IL-4, and IL-10 release from T lymphocytes of EAU rats, in vitro. Rapamycin also significantly increased TGF-β1 production but had no effect on IL-6 productionof T lymphocytes from EAU rats in vitro. Furthermore, rapamycin decreased the ratio of Th17 cells/CD4+T cells and upregulated Tregs in EAU, as detected by flow cytometry.

CONCLUSION

Rapamycin effectively interferes with T cell mediated autoimmune uveitis by inhibiting antigen-specific T cell functions and enhancing Tregs in EAU. Rapamycin is a promising new alternative as an adjunct corticosteroid-sparing agent for treating uveitis.