Loss of blood-retinal barrier (BRB) properties induced by vascular endothelial growth factor (VEGF) and other factors is an important cause of diabetic macular edema. Previously, we found that the presence of plasmalemma vesicle-associated protein (PLVAP) in retinal capillaries associates with loss of BRB properties and correlates with increased vascular permeability in diabetic macular edema. In this study, we investigated whether absence of PLVAP protects the BRB from VEGF-induced permeability. We used lentiviral-delivered shRNA or siRNA to inhibit PLVAP expression. The barrier properties of in vitro BRB models were assessed by measuring transendothelial electrical resistance, permeability of differently sized tracers, and the presence of endothelial junction complexes. The effect of VEGF on caveolae formation was studied in human retinal explants. BRB loss in vivo was studied in the mouse oxygen-induced retinopathy model. The inhibition of PLVAP expression resulted in decreased VEGF-induced BRB permeability of fluorescent tracers, both in vivo and in vitro. PLVAP inhibition attenuated transendothelial electrical resistance reduction induced by VEGF in BRB models in vitro and significantly increased transendothelial electrical resistance of the nonbarrier human umbilical vein endothelial cells. Furthermore, PLVAP knockdown prevented VEGF-induced caveolae formation in retinal explants but did not rescue VEGF-induced alterations in endothelial junction complexes. In conclusion, PLVAP is an essential cofactor in VEGF-induced BRB permeability and may become an interesting novel target for diabetic macular edema therapy.

To gain insight into determinants that define the duration of the asymptomatic period preceding AIDS, groups of long-term asymptomatic (LTA) person (> 7 years of follow-up) and slow and rapid progressors of human immunodeficiency virus infection were studied. LTAs had no clinical manifestations of AIDS or immunologic abnormalities in 7 years of follow-up. RNA copy numbers, gag- and env-specific, and neutralizing antibody titers in serum were determined 1 and 5 years after seroconversion or entry into the cohort. Early in infection, before immunologic markers or clinical manifestations allowed group discrimination, subjects who were later classified as LTAs had significantly less serum viral RNA than progressors. No significant increase in virus load was found in progressors, indicating that the initial load defines clinical outcome. In slow progressors, high virus load was associated with high p24-specific antibody titers, suggesting that delay of clinical manifestations of AIDS may be related to the presence of high levels of p24-specific but not V3-specific antibodies.

Despite adequate glycemic control, pregnancy outcome of women with type 1 diabetes (T1D) is still unfavorable as compared to healthy women. In a rat-model of T1D under normoglycemic conditions, adverse pregnancy outcome was also observed, which was associated with aberrant immunological adaptations to pregnancy. Because similar processes may occur in women with T1D we studied the systemic immune response in non-pregnant and pregnant women with and without T1D. The systemic immune response was assessed by using flow cytometry to evaluate the number and activational status of subpopulations of lymphocytes, Natural Killer cells and monocytes in peripheral blood of non-pregnant and pregnant women with and without T1D. An increased white blood cell count, an increased Th1/Th2 ratio, increased Natural Killer cell expression of CD335 and enhanced activation of intermediate and non-classical monocytes was observed in pregnant women with T1D vs. healthy pregnant women. Also, the pregnancy outcome (i.e. incidence of preterm delivery and macrosomia) of women with T1D was unfavorable as compared to healthy women. This study showed that in T1D, the immunological adaptations to pregnancy are disturbed. In addition to hyperglycemia, these different immunological adaptations may be responsible for the greater frequency of complications in pregnant women with T1D.

Histatins are multifunctional histidine-rich peptides secreted by the salivary glands and exclusively present in the saliva of higher primates, where they play a fundamental role in the protection of the oral cavity. Our previously published results demonstrated that histatin-1 (Hst1) promotes cell-substrate adhesion in various cell types and hinted that it could also be involved in cell-cell adhesion, a process of fundamental importance to epithelial and endothelial barriers. Here we explore the effects of Hst1 on cellular barrier function. We show that Hst1 improved endothelial barrier integrity, decreased its permeability for large molecules, and prevented translocation of bacteria across epithelial cell layers. These effects are mediated by the adherens junction protein E-cadherin (E-cad) and by the tight junction protein zonula occludens 1, as Hst1 increases the levels of zonula occludens 1 and of active E-cad.