Impact of astrocyte and lymphocyte interactions on the blood-brain barrier in multiple sclerosis

Objective. - This study was designed to investigate the impact of astrocyte and lymphocyte (LC) interactions in the blood-brain barrier (BBB) on the pathogenesis of multiple sclerosis (MS). Methods. - Primary rat brain microvascular endothelial cells (rBMECs) and astrocytes isolated from Sprague-Dawley rats were used to establish in vitro BBB models. Transendo-thelial electrical resistance (TEER) and permeability were compared between rBMEC monocultures and rBMEC/astrocyte co-cultures to evaluate the validity of each as a BBB cell model. rBMEC/LC co-cultures and rBMEC/astrocyte/LC tri-cultures were established to evaluate inflammatory responses in MS by measuring the gene expression levels of nerve growth factor (NGF), matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 9 (MMP-9), interleukin 17 (IL-17), interferon gamma (IFN-gamma), and forkhead box P3 (Foxp3). Results. - The rBMEC/astrocyte co-cultures exhibited higher TEER values and lower lymphocyte permeabilities than those of rBMEC monocultures. Compared to the rBMEC monocultures, the rBMEC/astrocyte/LC tri-cultures showed significantly decreased NGF, IL-17, and IFN-gamma and increased MMP-2 and Foxp3 expression. Furthermore, the tri-cultures exhibited decreased NGF, IL-17, and IFN-gamma expression compared to the rBMEC/astrocyte co-cultures, and increased MMP-2 expression compared to that shown by the rBMEC/LC cocultures. MMP-9 expression did not vary significantly between the four established BBB cell models. Conclusion. - These results suggest that the synergistic effect between astrocytes and LCs may increase the expression of MMP-2 and decrease that of IL-17 and IFN-gamma at the BBB. Furthermore, the use of rBMEC/astrocytes/LC tri-cultures enabled us to test the synergistic effect between astrocytes and LCs and their roles in MS pathogenesis. (C) 2019 Published by Elsevier Masson SAS.