Lung epithelial barrier function and wound healing are decreased by IL-4 and IL-13 and enhanced by IFN-gamma.

To understand the effects of cytokines on epithelial cells in asthma, we have investigated the effects of interleukin (IL)-4, IL-13, and interferon (IFN)-gamma on barrier function and wound healing in Calu-3 human lung epithelial cells. IL-4 and IL-13 treatment of Calu-3 cells grown on Transwell filters resulted in a 70-75% decrease in barrier function as assessed by electrophysiological and [(14)C]mannitol flux measurements. In contrast, IFN-gamma enhanced barrier function threefold using these same parameters.

Interferon-gamma decreases barrier function in T84 cells by reducing ZO-1 levels and disrupting apical actin.

The effects of interferon-gamma (IFN-gamma) on tight junctions in T84 human intestinal epithelial cells were investigated. Treatment of T84 cells with IFN-gamma caused a dose- and time-dependent increase in monolayer permeability as assessed by transepithelial electrical resistance measurements. Examination of specific proteins associated with tight junctions by immunoblotting and confocal microscopy revealed changes in the expression levels and localization of some of these proteins after exposure of the cells to IFN-gamma.

Highly polarized HLA class II antigen processing and presentation by human intestinal epithelial cells.

The high concentration of foreign antigen in the lumen of the gastrointestinal tract is separated from the underlying lymphocytes by a single cell layer of polarized epithelium. Intestinal epithelial cells can express HLA class II antigens and may function as antigen-presenting cells to CD4(+) T cells within the intestinal mucosa. Using tetanus toxoid specific and HLA-DR-restricted T lymphocytes, we show that polarized intestinal epithelial cells directed to express HLA-DR molecules are able to initiate class II processing only after internalization of antigen from their apical surface.

Biological consequences of targeting beta 1,4-galactosyltransferase to two different subcellular compartments.

beta 1,4-galactosyltransferase is unusual among the glycosyltransferases in that it is found in two subcellular compartments where it performs two distinct functions. In the trans-Golgi complex, galactosyltransferase participates in oligosaccharide biosynthesis, as do the other glycosyltransferases. On the cell surface, however, galactosyltransferase associates with the cytoskeleton and functions as a receptor for extracellular oligosaccharide ligands.

Alteration of oligosaccharide biosynthesis by genetic manipulation of glycosyltransferases.

The alteration of oligosaccharide structures through genetic manipulation of glycosyltransferase activities is now a reality. It is apparent that this technique has greater consequences on oligosaccharide structure when an exogenous enzyme is introduced into cells, and in particular when this enzyme is responsible for a terminal glycosylation step. By contrast, only one study has examined the effects of overexpressing an endogenous glycosyltransferase, in which there was no detectable effect on glycosylation.