A novel co-culture model for investigation of the effects of LPS-induced macrophage-derived cytokines on brain endothelial cells.

In order to study effects of macrophage-derived inflammatory mediators associated with systemic inflammation on brain endothelial cells, we have established a co-culture system consisting of bEnd.3 cells and LPS-activated Raw 264.7 cells and performed its cytokine profiling. The cytokine profile of the co-culture model was compared to that of mice treated with intraperitoneal LPS injection. We found that, among cytokines profiled, eight cytokines/chemokines were similarly upregulated in both in vivo mouse and in vitro co-culture model. In contrast to the co-culture model, the cytokine profile of a common mono-culture system consisting of only LPS-activated bEnd.3 cells had little similarity to that of the in vivo mouse model. These results indicate that the co-culture of bEnd.3 cells with LPS-activated Raw 264.7 cells is a better model than the common mono-culture of LPS-activated bEnd.3 cells to investigate the molecular mechanism in endothelial cells, by which systemic inflammation induces neuroinflammation. Moreover, fibrinogen adherence both to bEnd.3 cells in the co-culture and to brain blood vessels in a LPS-treated animal model of Alzheimer's disease increased. To the best of our knowledge, this is the first to utilize bEnd.3 cells co-cultured with LPS-activated Raw 264.7 cells as an in vitro model to investigate the consequence of macrophage-derived inflammatory mediators on brain endothelial cells.