ABSTRACT

Human physiology requires selective compartmentation so that

distinct physiological functions can be effectively regulated. Central

to organ compartments are barriers composed of specialized

polarized epithelial cells. Epithelial and endothelial cells have

several features that promote barrier function, including apical-

basolateral polarity and intercellular junctions called tight junctions.

Cells also mediate a selective barrier through the cytoplasm of cells

via transcytotic pathways. Each of these elements can be targeted

to alter barrier function. Insights from pathogens that interact with

cells to decrease barrier function provide clues to pharmacologic

agents that can have similar effect to promote drug delivery.