Effect of Inhibiting Interleukin‐1β with Neutralizing Antibody on Tight Junction Protein Expression after Brain Ischemia in Ovine Fetus

Abstract

We tested the hypothesis that inhibiting interleukin-1β (IL-1β) with neutralizing monoclonal antibody (mAb) alters tight junction (TJ) protein expression after brain ischemia-reperfusion (I/R) in the ovine fetus. Ovine fetuses at 85% gestation were studied after 30 min of ischemia and 24 h of reperfusion. Ovine IL-1β mAb has been generated, and showed high sensitivity, specificity, and neutralizing effects to IL-1β protein in vitro. Intravenous placebo (PL) or IL-1β mAb (5 mg/kg) infusions were given to the fetuses 15 min and 4 h after brain ischemia. Occludin (Occl), claudin-1 (CL-1), and CL-5 protein expression were determined by Western immunoblot in non-ischemic (sham, n=5), I/R+PL (n=6), and I/R+IL-1β mAb-treated (n=7) groups in the cerebral cortex, caudate nucleus, cerebellum, and medulla. Results are expressed as ratio to an internal control protein. In the medulla, Occl expression decreased and CL-5 expression increased after I/R+IL-1β mAb treatment compared to the sham group (Fig., M ± SD, P<0.05), but CL-1 expression did not change. Similar patterns of TJ expression were not observed in the cerebral cortex, cerebellum or caudate nucleus (data not shown). Treatment with IL-1β mAb affects I/R-related transmembrane TJ protein expression in some, but not all brain regions studied. Alterations in BBB function after I/R and IL-1β mAb treatment may not be directly regulated by changes in transmembrane TJ proteins in the fetus. NIH-HD-057100