The effect of specific caspase inhibitors on TNF-alpha and butyrate-induced apoptosis of intestinal epithelial cells.
Tumour necrosis factor-alpha (TNF-alpha)-induced intestinal epithelial cell apoptosis may contribute to mucosal injury in inflammatory bowel disease. Inhibition of TNF-alpha-induced apoptosis, using specific caspase inhibitors could, therefore, be of benefit in the treatment of disease. In vitro, CaCo-2 colonic epithelial cells are refractory to apoptosis induced by TNF-alpha alone; however, TNF-alpha can act synergistically with the short-chain fatty acid (SCFA) and colonic fermentation product, butyrate, to promote apoptosis. TNF-alpha/butyrate-induced apoptosis was characterised by nuclear condensation and fragmentation and caspase-3 activation. Inhibitors of caspase-8 (z-IETD.fmk) and caspase-10 (z-AEVD.fmk) significantly reduced TNF-alpha/butyrate-induced apoptosis, based on nuclear morphology and terminal deoxynucleotide transferase-mediated dUTP-biotin nick-end labelling (TUNEL), although caspase inhibition was associated with a significant increase in cells demonstrating atypical nuclear condensation. Inclusion of atypical cells in calculations of total cell death, still demonstrated that z-IETD.fmk and z-AEVD.fmk (in combination) significantly reduced cell death. Reduction in cell death was associated with maintenance of viable cell number. Transmembrane resistance was also used a measure of the ability of caspase inhibitors to prevent TNF-alpha/butyrate-mediated damage to epithelial monolayers. TNF-alpha/butyrate resulted in a significant fall in transmembrane resistance, which was prevented by pre-treatment with z-IETD.fmk, but not z-AEVD.fmk. In conclusion, synthetic caspase inhibitors can reduce the apoptotic response of CaCo-2 colonic epithelial cells to TNF-alpha/butyrate, improve the maintenance of viable cell numbers and block loss of transmembrane resistance. We hypothesise that caspase inhibition could be a useful therapeutic goal in the treatment of inflammatory bowel conditions, such as ulcerative colitis.
Jones
Sarah A
SA
Research Centre for Gastroenterology, Institute of Cell and Molecular Sciences, Barts and The London, Queen Mary School of Medicine and Dentistry, University of London, London EC1A 7BE, UK.
Butler
Ross N
RN
Sanderson
Ian R
IR
Wilson
James W
JW
D017209:Apoptosis / Q000187:drug effects*; D002087:Butyrates / Q000494:pharmacology*; D018938:Caco-2 Cells; D053455:Caspase 10; D053148:Caspase 3; D053181:Caspase 8; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D004357:Drug Synergism; D004789:Enzyme Activation; D006801:Humans; D020287:In Situ Nick-End Labeling; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002087:Butyrates; D061945:Caspase Inhibitors; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053455:Caspase 10; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; C506438:CASP10 protein, human