CRALBP is a Highly Prevalent Autoantigen for Human Autoimmune Uveitis

Cellular retinaldehyde binding protein (CRALBP) is an autoantigen in spontaneous equine recurrent uveitis. In order to test whether CRALBP contributes to human autoimmune uveitis, the specificity of antibodies from human uveitis patient's sera was first evaluated in two-dimensional (2D) Western blot analysis. Subsequent identification of the immunoreactive proteins by mass spectrometry resulted in the identification of CRALBP as a putative autoantigen. Additionally, sera from human uveitis and control patients were by Western blot using purified human recombinant CRALBP. Anti-CRALBP autoantibodies occur more frequently (P<.01) in human uveitis patients than in normal controls. Thirty out of 56 tested uveitis patient's sera contained autoantibodies reactive against CRALBP, compared to only four out of 23 normal control subjects. The presence of CRALBP autoantibodies in 54% of tested uveitis patients supports CRALBP as a possible autoantigen in human autoimmune uveitis

Vasodilator Phosphostimulated Protein (VASP) Protects Endothelial Barrier Function During Hypoxia

The endothelial barrier controls the passage of solutes from the vascular space. This is achieved through active reorganization of the actin cytoskeleton. A central cytoskeletal protein involved into this is vasodilator-stimulated phosphoprotein (VASP). However, the functional role of endothelial VASP during hypoxia has not been thoroughly elucidated. We determined endothelial VASP expression through real-time PCR (Rt-PCR), immunhistochemistry, and Western blot analysis during hypoxia. VASP promoter studies were performed using a PGL3 firefly luciferase containing plasmid. Following approval by the local authorities, VASP−/− mice and littermate controls were subjected to normobaric hypoxia (8% O2, 92% N2) after intravenous injection of Evans blue dye. In in vitro studies, we found significant VASP repression in human microvascular and human umbilical vein endothelial cells through Rt-PCR, immunhistochemistry, and Western blot analysis. The VASP promoter construct demonstrated significant repression in response to hypoxia, which was abolished when the binding of hypoxia-inducible factor 1 alpha was excluded. Exposure of wild-type (WT) and VASP−/− animals to normobaric hypoxia for 4 h resulted in an increase in Evans blue tissue extravasation that was significantly increased in VASP−/− animals compared to WT controls. In summary, we demonstrate here that endothelial VASP holds significant importance for endothelial barrier properties during hypoxia