RT Journal Article
SR Electronic
T1 Non-pathogenic bacteria elicit a differential cytokine response by intestinal epithelial cell/leucocyte co-cultures
JF Gut
JO Gut
FD BMJ Publishing Group Ltd and British Society of Gastroenterology
SP 79
OP 87
DO 10.1136/gut.47.1.79
VO 47
IS 1
A1 D Haller
A1 C Bode
A1 W P Hammes
A1 A M A Pfeifer
A1 E J Schiffrin
A1 S Blum
YR 2000
UL http://gut.bmj.com/content/47/1/79.abstract
AB BACKGROUND AND AIM Intestinal epithelial cells (IEC) are thought to participate in the mucosal defence against bacteria and in the regulation of mucosal tissue homeostasis. Reactivity of IEC to bacterial signals may depend on interactions with immunocompetent cells. To address the question of whether non-pathogenic bacteria modify the immune response of the intestinal epithelium, we co-cultivated enterocyte-like CaCO-2 cells with human blood leucocytes in separate compartments of transwell cultures.METHODS CaCO-2/PBMC co-cultures were stimulated with non-pathogenic bacteria and enteropathogenic Escherichia coli. Expression of tumour necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-8, monocyte chemoattracting protein 1 (MCP-1), and IL-10 was studied by enzyme linked immunosorbent assays (cytokine secretion) and by semiquantitative reverse transcription-polymerase chain reaction.RESULTS Challenge of CaCO-2 cells with non-pathogenic E coli andLactobacillus sakei induced expression of IL-8, MCP-1, IL-1β, and TNF-α mRNA in the presence of underlying leucocytes. Leucocyte sensitised CaCO-2 cells produced TNF-α and IL-1β whereas IL-10 was exclusively secreted by human peripheral blood mononuclear cells. CaCO-2 cells alone remained hyporesponsive to the bacterial challenge. Lactobacillus johnsonii, an intestinal isolate, showed reduced potential to induce proinflammatory cytokines but increased transforming growth factor beta mRΝA in leucocyte sensitised CaCO-2 cells. TNF-α was identified as one of the early mediators involved in cellular cross talk. In the presence of leucocytes, discriminative activation of CaCO-2 cells was observed between enteropathogenicE coli and non-pathogenic bacteria.CONCLUSION The differential recognition of non-pathogenic bacteria by CaCO-2 cells required the presence of underlying leucocytes. These results strengthen the hypothesis that bacterial signalling at the mucosal surface is dependent on a network of cellular interactions.IECintestinal epithelial cellsPBMCperipheral blood mononuclear cellsTNF-αtumour necrosis factor alphaIL-1βinterleukin 1 betaIELintraepithelial lymphocytesPBLperipheral blood lymphocytesLPLlamina propria lymphocytesRT-PCRreverse transcription-polymerase chain reactionTGF-βtransforming growth factor betaPBSphosphate buffered salineTEERtransepithelial electrical resistanceLPSlipopolysaccharidebpbase paircfucolony forming unitsMCP-1monocyte chemoattracting protein 1mAbmonoclonal antibodyIBDinflammatory bowel disease