Small-Molecule Antagonist of VLA-4 (GW559090) Attenuated Neuro-Inflammation by Targeting Th17 Cell Trafficking across the Blood-Retinal Barrier in Experimental Autoimmune Uveitis

Abstract

Background: The integrin VLA-4 (α4β1) plays an important role in leukocyte trafficking. This study investigated the efficacy of a novel topical α4β1 integrin inhibitor (GW559090, GW) in a mouse model for non-infectious posterior uveitis (experimental autoimmune uveitis; EAU) and its effect on intraocular leukocyte subsets.Methods: Mice (female; B10.RIII or C57Bl/6; aged 6-8 weeks) were immunized with specific interphotoreceptor retinoid-binding protein (IRBP) peptides to induce EAU. Topically administered GW (3, 10, and 30 mg/ml) were given twice daily either therapeutically once disease was evident, or prophylactically, and compared with vehicle-treated (Veh) and 0.1% dexamethasone-treated (Dex) controls. Mice were sacrificed at peak disease. The retinal T cell subsets were investigated by immunohistochemistry and immunofluorescence staining. The immune cells within the retina, blood and draining lymph nodes (dLNs) were phenotyped by flow cytometry. The effect of GW559090 on non-adherent, adherent and migrated CD4+ T cell subsets across a central nervous system (CNS) endothelium was further assayed in vitro and quantitated by flow cytometry.Results: There was a significant reduction in clinical and histological scores in GW10 and Dex treated groups as compared to controls either administered therapeutically or prophylactically. There were fewer CD45+ leukocytes infiltrating the retinae and vitreous fluids in the treated GW10 group (P < 0.05). Immunofluorescence staining and flow cytometry data identified decreased levels of retinal Th17 cells (P ≤ 0.001) in the GW10 treated eyes, leaving systemic T cell subsets unaffected. In addition, fewer Ly6C+ inflammatory monocyte/macrophages (P = 0.002) and dendritic cells (P = 0.017) crossed the BRB following GW10 treatment. In vitro migration assays confirmed that Th17 cells were selectively suppressed by GW559090 by adhering to endothelial monolayers.Conclusions: This α4β1 integrin inhibitor may exert a modulatory effect in EAU progression by selectively blocking Th17 cell migration across the blood-retinal barrier without affecting systemic CD4+ T cell subsets. Local α4β1 integrin-directed inhibition could be clinically relevant in treating a Th17-dominant form of uveitis.

Myeloid cells in retinal and brain degeneration

“…Interestingly, several common themes arise from the comparison of these diseases. Macrophage infiltration, either from a compromised BRB or from the ONH, which serves as a reservoir for myeloid cells, plays an important inciting role in ocular diseases such as glaucoma, AMD, and posterior uveitis [73,74,119,120,128,132,[153][154][155]160,268]. Corroboratively, elevated levels of MCP-1, a major chemokine in macrophage recruitment, are associated with pathogenesis and disease progression in animal models of glaucoma, AMD, RP, and AD [72,118,127,128,140,141,147,161,196].…”

“…Microglia have been shown to be essential for inducing the retinal inflammatory response in experimental autoimmune uveitis (EAU) [150]. EAU is a T‐cell‐mediated mouse model of chorioretinitis whereby inflammation is induced by immunization with retinal antigens [153]. Microglial ablation prior to the development of EAU was sufficient to block the inflammatory response [150].…”

“…In EAU, CD4+ T cells and macrophage/microglia have been shown in the retina both perivascularly and in tertiary lymphoid clusters [154,160]. When EAU mice were given an inhibitor to integrin VLA-4, an adhesion molecule implicated in CD4+ T-cell recruitment, fewer Th17+ subset of T cells, and Ly6C+ monocytes/macrophages crossed the BRB, resulting in reduced clinical disease severity [153]. Repeated exposure to systemic LPS also led to BRB breakdown, retinal microglial proliferation and activation, and macrophage infiltration [161].…”