Triggered human mucosal T cells release tumour necrosis factor-alpha and interferon-gamma which kill human colonic epithelial cells

Abstract

SUMMARYTcell activation can lead to local tissueinjury in organ culture studies of human fetal jejunum, either directly throughcytotoxicity or indirectly by the release of cytotoxic cytokines. The goal of this study was to establish in vitro whether cyiotoxic cytokines can be released by isolated colonic T cells and what cytokine interactions are required for killing of human colonic epithelial cells. Cytokinecontaining supernatants were induced by incubating un.separated lamina propria tymphocyies (LPL) or mucosai Tcell subpopulations (separated by indirect panning) wilh anti-C'D3 and/or K562 target cells for 18 hat 37 C. Cytokines were measured by cytotoxicity assays using 1.929 (murine tibroblast) and HT-29 (human colonic tumour) lines as target cells in combination wilh blocking anti-cytokine antibodies. Supernatanls derived from unseparaled, CD4* (>95% pure) and CD8 ' (>90% pure) LPL were cytotoxic to L929 targets (350 U/ml, 230 U/ml and 100 U/m! tumournecrosis factor-alpha, respectively). All or nearly all of the cylotoxicity was due lo the presence of lumour necrosis facioralpha (little or no lumour necrosis factor-bcla was delected). These same supernatanls were cyiotoxic (up to 32% lysis at 1/4 dilution) to HT-29 targets in a 48-h '"In release assay. Recombinant tumour necrosis factor-alpha and interferon-gamma alone produced minimal killing of HT-29. bul together killed the HT-29 target cells. Anii-tumour necrosis factor-alpha or anu-iiucrfcron-pamma alone blocked killing of HT-29 target cells by LPL-derived supernatants. although anti-tumour necrosis factor-beta had no effect upon killing of HT-29. These results demonstrate thai human LPL T cells, triggered by addition of anti-CD3 and target cells, produce tumour necrosis factor-alpha and interferon-gamma, both of which are required for optimal killing of HT-29. Simultaneous release of these cytokines in the vicinity of epithelial cells during immune responses could play an important role in the mucosai damage in chronic inflammatory slates such as inflammatory bowel disca.se.

The changing immunological paradigm in coeliac disease

“…This cytokine is most likely a major factor in the increased epithelial expression of secretory component (polymeric Ig receptor; pIgR) and HLA-DR seen in the flat lesion [23]. Especially together with tumour necrosis factor (TNF)-␣ [24], IFN-␥ may also contribute to increased epithelial permeability [25] and expansion of mucosal plasma cells (PCs) as discussed later. An additional feature of active humoral immunity is constituted by subepithelial complement deposition, which may represent an early innate pathogenic insult on the mucosa [26].…”

Mucosal IL-10 and TGF-β play crucial roles in preventing LPS-driven, IFN-γ–mediated epithelial damage in human colon explants

“…We then showed that IL-10 depletion led to an inflammatory response, monitored by the expression of TNF-α and IFN-γ. We chose these Th1-type cytokines because (a) both are part of the mucosal immune response in the spontaneous colitis in IL-10 -/-mice (5); (b) TNF-α is a major cytokine involved in the perpetuation of inflammation during inflammatory bowel diseases (32-34); and (c) both are known to induce epithelial barrier disruption either independently or in combination (30,(35)(36)(37)(38)(39)(40)(41). We found a modest increase in TNF-α mRNA and protein levels in IL-10-depleted mucosa explant cultures at 48 h, in line with the partial downregulation of BCL3 levels.…”

TNFalpha and IL-10 Gene Polymorphisms in Inflammatory Bowel Disease. Association of -1082 AA Low Producer IL-10 Genotype with Steroid Dependency

“…Production of TNFα by circulating neutrophils was higher in IBD patients compared to controls (11) and there is evidence of increased mucosal TNFα production in CD patients (12). This cytokine is probably responsible for tissue damage due to its ability to kill colonic epithelial cells (13), as well as for causing epithelial barrier disruption (14). The production of IL-10 and TNFα presents important interindividual variations, with high hereditability regulated by gene polymorphisms at their promoter regions.…”