Regulation of alpha1-proteinase inhibitor release by proinflammatory cytokines in human intestinal epithelial cells.
alpha1-Proteinase inhibitor (alpha1-PI) is the main serine proteinase inhibitor in human plasma. Apart from its synthesis in the liver, this anti-inflammatory protein is also synthesized by and excreted from human intestinal epithelial cells. Antiinflammatory actions of alpha1-PI are thought to be of relevance in the pathogenesis of inflammatory bowel disease. To investigate the role of macrophage-derived cytokines on alpha1-PI secretion from intestinal epithelial cells, we cultured Caco-2 cells until differentiation (14 days in culture) on permeable filter supports. Monolayers of differentiated Caco-2 cells were then co-cultured with human peritoneal macrophages, grown on plastic in the basolateral chamber. Under these conditions, alpha1-PI secretion from Caco-2 cells was enhanced by 45%, probably by a direct action of macrophage-derived cytokines on Caco-2 cells. To extend this observation further, we treated differentiated Caco-2 cells with macrophage-derived proinflammatory cytokines (IL-1beta, IL-8, TNF-alpha), as well as with lymphocyte-derived cytokines IL-2, IL-6 and IFN-gamma. As early as after 24h treatment, IL-2 and IL-8 induced a significant and dose-dependent increase of alpha-1-PI secretion into cell culture medium; this effect was completely reversed after immunoneutralization by the antibodies against IL-2 and IL-8 alpha1-PI secretion was only slightly decreased after treatment with IFN-gamma, while IL-1beta, IL-6 and TNF-alpha had no effect. alpha1-PI secretion correlated well with the expression of this protein in differentiated Caco-2 cells after cytokine treatment, as confirmed by Western blot. Our data imply that, in vitro, alpha1-PI secretion in enterocyte-like Caco-2 cells is up-regulated by IL-2 and IL-8. Our results suggest that both lymphocyte- and macrophage-derived cytokines regulate secretion of the anti-inflammatory protein alpha1-PI in intestinal epithelial cells.
Faust
D
D
2nd Department of Medicine, Johann Wolfgang Goethe-University, Frankfurt/Main, Germany. D.Faust@em.uni-frankfurt.de
Raschke
K
K
Hormann
S
S
Milovic
V
V
Stein
J
J
D018938:Caco-2 Cells; D002450:Cell Communication / Q000276:immunology; D018920:Coculture Techniques; D016207:Cytokines / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D018928:Immunity, Mucosal; D015212:Inflammatory Bowel Diseases / Q000209:etiology / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000276:immunology / Q000378:metabolism*
D016207:Cytokines; D000515:alpha 1-Antitrypsin