BUDESONIDE INHIBITS T-CELL-INITIATED EPITHELIAL PATHOPHYSIOLOGY IN ANIN-VITRO MODEL OF INFLAMMATION

Recognition of the therapeutic value of glucocorticosteroids in the tr eatment of inflammation has preceded awareness of the mechanism(s) of action of these drugs. We recently showed that coculture of human T84 epithelial monolayers for 2 days with anti-CD3 activated peripheral bl ood mononuclear cells (A-PBM) led to impaired ion transport responses and reduced barrier function. We tested the hypothesis that budesonide , as a member of the new generation of more topically selective steroi ds, could prevent these immune-mediated epithelial abnormalities. Bude sonide added to the coculture system dose-dependently inhibited the fo llowing functional T84 abnormalities measured in Ussing chambers: redu ced transport responses (decreased short-circuit current changes to ca rbachol (raises [Ca2+](i)) and forskolin (raises cAMP, cyclic adenosin e monophosphate(i)); and increased permeability (decreased resistance and increased fluxes of H-3-mannitol and Cr-51- EDTA). For the benefic ial effects of budesonide to be observed, PBM pretreatment (greater th an or equal to 3 hr) and daily addition (for 2 days) to the coculture system was necessary. Budesonide (10(-7) M) dramatically reduced A-PBM proliferation (measured by H-3-thymidine incorporation) and cytokine (IL-1 beta, IL-2, IL-6, IFN-gamma, TNF-alpha) production, but was not cytotoxic to immune cells. Budesonide treatment of T84 epithelial cell s alone did not directly affect epithelial physiology, nor did it prev ent epithelial abnormalities evoked by subsequent exposure to A-PBM or conditioned media from immune cells. Our studies showed that budesoni de prevents epithelial dysfunction in this model by inhibiting activat ion of both T cells and monocytes.