Inhibition of transforming growth factor-beta production in brain pericytes contributes to cyclosporin A-induced dysfunction of the blood-brain barrier.

: 1. The present study was designed to clarify whether brain pericytes and pericyte-derived transforming growth factor-beta1 (TGF-beta1) participate in cyclosporin A (CsA)-induced dysfunction of the blood-brain barrier (BBB).2. The presence of brain pericytes markedly aggravated CsA-increased permeability of MBEC4 cells to sodium fluorescein and accumulation of rhodamine 123 in MBEC4 cells.3. Exposure to CsA significantly decreased the levels of TGF-beta1 mRNA in brain pericytes in pericyte co-cultures. Treatment with TGF-beta1 dose-dependently inhibited CsA-induced hyperpermeability and P-glycoprotein dysfunction of MBEC4 cells in pericyte co-cultures.4. These findings suggest that an inhibition of brain pericyte-derived TGF-beta1 contributes to the occurrence of CsA-induced dysfunction of the BBB.