Synthesis and regulation of accessory/proinflammatory cytokines by intestinal epithelial cells.
Intestinal epithelial cells (IEC) have been shown to act as antigen-presenting cells (APC) in vitro and may have this capacity in vivo. In order to determine whether IEC, like other APC, are able to produce accessory cytokines which may play a role in T cell activation, we assessed the accessory cytokine profile of IEC constitutively or after stimulation. We measured expression, production and regulation of accessory cytokines (IL-1 beta, IL-6, tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) by the presence of mRNA as well as secreted protein. Freshly isolated IEC from surgical specimens were cultured in the presence or absence of lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), IL-1 beta or TNF-alpha. mRNA was assessed by a specific RNAse protection assay which controlled for contaminating cell populations while protein secretion was measured by ELISA (IL-1) or bioassay (TNF and IL-6). Neither IL-1 beta nor TNF-alpha were detectable in cultured IEC supernatants, supporting the lack of macrophage contamination. All IEC spontaneously secreted IL-6 at levels comparable to those of macrophages. IEC IL-6 mRNA also increased approximately 200-fold during the first 24 h of culture. LPS, IFN-gamma or TNF-alpha had no effect on spontaneous IL-6 production, and neither resulted in the secretion of IL-1 beta or TNF-alpha. However, IL-1 beta up-regulated IL-6 synthesis by 6-7-fold. IEC express a profile of cytokine mRNAs distinct from conventional APC (low level constitutive IL-6 expression but no detectable IL-1 beta, TGF-beta or TNF-alpha), adding to their uniqueness as APC.
Panja
A
A
Division of Clinical Immunology, Mount Sinai Medical Centre, New York, NY, USA.
Siden
E
E
Mayer
L
L
D016207:Cytokines / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000235:genetics / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000494:pharmacology
D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha