Siebrits, Michaela NicoleFisher, DavidWillemse, ChontrelleMakhathini, Khayelihle Brian2026-09-092026-09-092026Siebrits, M.N., Fisher, D., Willemse, C. and Makhathini, K.B., 2026. The effects of methylprednisolone on non-inflamed and inflamed In vitro brain endothelial cells. Toxicology Mechanisms and Methods, pp.1-18.https://doi.org/10.1080/15376516.2026.2714946https://hdl.handle.net/10566/25377The blood-brain barrier (BBB) is primarily regulated by highly selective endothelial cells. Inflammation of the brain capillaries can compromise the BBB’s functioning. Methylprednisolone (M-Pred), a synthetic glucocorticoid, is clinically prescribed to treat systemic inflammation; however, little is known about its effect on both non-inflamed and inflamed brain capillaries. This study evaluated the effectiveness of M-Pred in ameliorating the lipopolysaccharide (LPS)-induced inflammatory response using the in vitro BBB model (bEnd.3). Cultured brain endothelial cells (BECs) were exposed to LPS (500, 1000, 2000 ng/ml) and co-treated with selected concentrations of M-Pred (10, 20, 40 µM). Cell proliferation, quantification of pro-inflammatory cytokines TNF-α and IL-1β (ELISA), and monolayer permeability (Transendothelial Electrical Resistance) were investigated. LPS decreased live cell number, increased dead cell number, and increased cell monolayer permeability; LPS increased pro-inflammatory cytokine secretion. These data confirmed the experimental functionality of the in vitro inflammatory BBB model. In the absence of inflammation, M-Pred decreased bEnd.3 cell monolayer permeability and pro-inflammatory cytokine secretion. M-Pred failed to alleviate LPS-induced inflammation across all tested concentrations. Chronic M-Pred treatment in the absence of inflammation proved detrimental to bEnd.3 cells’ physiology.enBlood-brain barrierinflammationLipopolysaccharideMethylprednisolonepermeabilityArticle