Establishment of minimal positive-control conditions to ensure brain safety during rapid development of emergency vaccines

Baek, Hyekyung; Kim, Kwang Ho; Park, Min Young; Kim, Kyeongryun; Ko, Bokyeong; Seo, Hyung Seok; Kim, Byoung Soo; Hahn, Tae-Wook; Yi, Sun Shin

The BBB mainly consists of capillary endothelial cells, pericytes, and astrocytes. Nutrients and oxygen in the bloodstream can permeate endothelial cells into the basal lamina through a variety of transport routes [9] . These endothelial cells are layered and form a barrier by their close proximity to each other and by tight junctions (TJs) located on cell membranes [3, 13] . TJs such as occludin, claudin, junctional adhesion molecule (JAM) and zonula occludens (ZO) are key structures of the BBB and significantly reduce permeation of some macromolecular and toxic solutes [11, 22] . Therefore, disruption of TJs leads to barrier disruption. Many previous reports have shown that LPS, a toxin from bacteria, combines with the toll-like receptor on the endothelial cell membrane to stimulate inflammation via signals from various cytokines including nuclear factor kappa B, tumor necrosis factor alpha, interleukin (IL)-1, IL-6, and IL-8 [2, 6, 12, 18, 20] . Under excessive inflammatory conditions, these cytokines can break down TJs, particularly occludin, which is sensitive to cytokines [6, 24] . Therefore, we thought it prudent to establish a positive-control protocol that involved injecting an appropriate dose of LPS to an animal model and observing the resultant damage to occludin and ZO-1 TJs.