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 in 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.

Adhesion Molecule Targeted Therapy for Non-Infectious Uveitis

“…The expression of VLA-4 (α4β1 integrin), the ligand to VCAM-1, has been reported mostly in non-CD4 + T cells and rarely (2%) on uveitogenic CD4 + T cells during the early stages of EAU in C57BL/6 mice [ 28 ]. Our data demonstrated that at peak classical EAU in B10.RIII mice, there was an equal expression (30~40%) of VLA-4 by both Th1 and Th17 cells [ 35 ]. The increase in VLA-4 expression by CD4 + T cells was confined to the draining lymph nodes and the eye, but not the peripheral blood, suggesting that pathogenic leukocytes expressing VLA-4 are only present at local sites of inflammation [ 35 , 36 ].…”

“…Our data demonstrated that at peak classical EAU in B10.RIII mice, there was an equal expression (30~40%) of VLA-4 by both Th1 and Th17 cells [ 35 ]. The increase in VLA-4 expression by CD4 + T cells was confined to the draining lymph nodes and the eye, but not the peripheral blood, suggesting that pathogenic leukocytes expressing VLA-4 are only present at local sites of inflammation [ 35 , 36 ]. This is supported by an in vitro study showing that antibody to VCAM-1 does not affect activated non-uveitogenic Th1 and Th17 cell migration [ 32 ].…”

“…Targeting VLA-4 is able to block the recruitment and migration of uveitogenic T cells and monocytes across the blood–retinal barrier (BRB), which ameliorates EAU development without affecting systemic immunity. A recent study reported that a small molecule inhibiting VLA-4 ameliorated the clinical signs of EAU by preferentially suppressing Th17 cell and inflammatory monocyte transmigration across the eye [ 35 ]. In addition, the effects of targeting VLA-4 and LFA-1 were reported to be transient and continuous treatment is needed [ 33 ].…”

Myeloid cells in retinal and brain degeneration

“…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].…”

“…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+ monocyte/macrophages crossed the BRB, resulting in reduced clinical disease severity [153]. Repeated exposure to systemic LPS also led to BRB breakdown, retinal microglia proliferation and activation, and macrophage infiltration [161].…”