BACKGROUND AND AIMS: Patients suffering from inflammatory bowel disease show increased levels of the mast cell products histamine and tumour necrosis factor alpha (TNF-alpha). Treating these patients with antibodies against TNF-alpha diminishes the symptoms of diarrhoea. In this study, the effect of TNF-alpha on ion secretion induced by the mast cell mediator histamine in HT29cl.19A cells and mouse distal colon was investigated and the possible second messengers involved were studied. METHODS: Electrophysiology of filter grown HT29cl.19A cells and isolated mouse distal colon was used to monitor the secretory response to histamine with and without prior exposure to TNF-alpha for 3-24 hours. Phospholipase D (PLD) activity and phosphatidic acid levels were analysed by 32P(i) labelling of HT29cl.19A cells. RESULTS: In both experimental systems TNF-alpha was found to potentiate ion secretion induced by histamine. Phospholipid analysis of HT29cl.19A cells revealed that histamine activates the PLD pathway. Furthermore, TNF-alpha pretreated cells were found to have decreased phosphatidic acid levels, the intermediate product of the PLD pathway, which indicates upregulation of the enzyme phosphatidic acid phosphatase. CONCLUSIONS: The mast cell products TNF-alpha and histamine synergistically stimulate ion secretion in intestinal epithelium via upregulation of the PLD pathway.
BACKGROUND AND AIMS: Patients suffering from inflammatory bowel disease show increased levels of the mast cell products histamine and tumour necrosis factor alpha (TNF-alpha). Treating these patients with antibodies against TNF-alpha diminishes the symptoms of diarrhoea. In this study, the effect of TNF-alpha on ion secretion induced by the mast cell mediator histamine in HT29cl.19A cells and mouse distal colon was investigated and the possible second messengers involved were studied. METHODS: Electrophysiology of filter grown HT29cl.19A cells and isolated mouse distal colon was used to monitor the secretory response to histamine with and without prior exposure to TNF-alpha for 3-24 hours. Phospholipase D (PLD) activity and phosphatidic acid levels were analysed by 32P(i) labelling of HT29cl.19A cells. RESULTS: In both experimental systems TNF-alpha was found to potentiate ion secretion induced by histamine. Phospholipid analysis of HT29cl.19A cells revealed that histamine activates the PLD pathway. Furthermore, TNF-alpha pretreated cells were found to have decreased phosphatidic acid levels, the intermediate product of the PLD pathway, which indicates upregulation of the enzyme phosphatidic acid phosphatase. CONCLUSIONS: The mast cell products TNF-alpha and histamine synergistically stimulate ion secretion in intestinal epithelium via upregulation of the PLD pathway.
Authors: Xiaojia Ren; Jeriel T R Keeney; Sumitra Miriyala; Teresa Noel; David K Powell; Luksana Chaiswing; Subbarao Bondada; Daret K St Clair; D Allan Butterfield Journal: Free Radic Biol Med Date: 2018-12-26 Impact factor: 7.376