Anti-Delta-like 4 monoclonal antibody, clone INE5-2

PURPOSE. This study evaluated the effects of BIBF1120, a novel triple angiokinase inhibitor against pathological retinal neovascularization. METHODS. BIBF1120 effect on development of the normal retinal vasculature was evaluated in Sprague-Dawley rat pups. Two models of ischemic oxygen-induced retinopathy (OIR) and the aortic ring assay were used to assess the antiangiogenic effects of BIBF1120. In the vaso-obliteration model (VO), rat pups were exposed to 80% O-2 from postnatal day (P) 5 to P10. In the preretinal neovascularization (NV) model, rat pups were exposed to cycling O-2 (50% and 10%) from P1 to P14, followed by room air until P18. Animals were intravitreally or orally treated with BIBF1120. Retinal vasculature, VO, and NV were evaluated in retinal flat mounts. Retinal expression of VEGF, Delta-like ligand 4 (Dll4), Netrin-1, Ephrin-B2, and EphB4 was analyzed by quantitative PCR and Western blot analysis. RESULTS. BIBF1120 interfered with normal retinal vascular development and microvessel branching in the aortic assay. However, in VO model BIBF1120 did not accrue VO. On the contrary, in the NV model BIBF1120 accelerated normal retinal vascularization and robustly diminished preretinal neovascularization compared to vehicle (by similar to 80%). The expression levels of VEGF negative regulator Dll4 and repulsive cues EphrinB2 and EphB4 mRNA in the retina of vehicle-treated OIR animals were markedly increased compared to normoxia, but were normalized by BIBF1120. CONCLUSIONS. Data reveal efficacy of BIBF1120 on preretinal neovascularization and, of greater interest, on acceleration of normal vascularization, consistent with interference of major repulsive cues expressed in the retina during OIR. Accordingly, BIBF1120 appears to exhibit preferable properties compared to anti-VEGF therapies for the treatment of ischemic retinopathies.

Regulatory T (Treg) cells establish tolerance, prevent inflammation at mucosal surfaces, and regulate immunopathology during infectious responses. Recent studies have shown that Delta-like ligand 4 (Dll4) was upregulated on APC after respiratory syncytial virus (RSV) infection, and its inhibition leads to exaggerated immunopathology. In the present study, we outline the role of Dll4 in T-reg cell differentiation, stability, and function in RSV infection. We found that Dll4 was expressed on CD11b(+) pulmonary dendritic cells in the lung and draining lymph nodes in wild-type BALB/c mice after RSV infection. Dll4 neutralization exacerbated RSV-induced disease pathology, mucus production, group 2 innate lymphoid cell infiltration, IL-5 and IL-13 production, as well as IL-17A(+) CD4 T cells. Dll4 inhibition decreased the abundance of CD62L(hi) CD44(lo) Foxp3(+) central T-reg cells in draining lymph nodes. The RSV-induced disease was accompanied by an increase in Th17-like effector phenotype in Foxp3(+) T-reg cells and a decrease in granzyme B expression after Dll4 blockade. Finally, Dll4-exposed induced T-reg cells maintained the CD62L(hi) CD44(lo) central Treg cell phenotype, had increased Foxp3 expression, became more suppressive, and were resistant to Th17 skewing in vitro. These results suggest that Dll4 activation during differentiation sustained T-reg cell phenotype and function to control RSV infection.