Deoxynivalenol and intestinal inflammation : an in vitro assessment

Deoxynivalenol (DON, vomitoxin), the most prevalent trichothecene mycotoxin worldwide, contaminates numerous food items from cereal origin. DON adversely affects animal health with symptoms going from reduced nutritional efficiency and weight gain upon chronic low dose exposure, to emesis, leukocytosis and haemorrhage upon acute high level ingestion. Also human toxicoses related to DON ingestion have been reported. The gastro-intestinal tract is the primary site of DON exposure in terms of timing and amount, and could constitute both a target of and a barrier to DON toxicity. The objective of this research was to determine the impact of DON exposure on inflammatory parameters in human intestinal epithelial cells in vitro. Proliferating and differentiated Caco-2 cells, respectively representative of young/immature, and adult/mature human enterocytes were exposed to realistic intestinal concentrations of DON (50 to 5000 ng/ml) during 24h. The induction of intracellular inflammatory signalling pathways was observed through the activation of the Mitogen Activated Protein Kinases (ERK1/2, JNK and p38) and the transcription factor Nuclear Factor (NF)- κB. DON dose-dependently upregulated the production of the inflammatory mediators IL-8 and PGE-2. These phenomena occurred similarly in proliferating and differentiated cells and were dependent on ERK1/2, JNK and NF-κB activation. The simultaneous exposure to a mixture of inflammatory mediators (IL-1β, TNF-α, IFN-γ and LPS) representative of an acute inflammatory reaction caused synergic increases in IL-8 secretion. Continuous incubation with DON (50 ng/ml) during 21 days increased basal level of IL-8 and PGE-2 production. DON exposure furthermore caused a dose-dependent increase of the paracellular permeability of the Caco-2 monolayer together with a decrease in protein synthesis, with a possible link between these events being the diminished synthesis of the tight junction protein claudin-4. Also intestinal alkaline phosphatase expression, a marker of cellular differentiation, was reduced. The results of this research allow to conclude that DON induces inflammatory parameters in the intestinal epithelium, together with causing a weakening of the monolayer structure and functioning. These observations could be important for human health hazard evaluation regarding DON exposure.(BIOL 3) -- UCL, 200

Deoxynivalenol and intestinal inflammation : an in vitro assessment

Deoxynivalenol (DON, vomitoxin), the most prevalent trichothecene mycotoxin worldwide, contaminates numerous food items from cereal origin. DON adversely affects animal health with symptoms going from reduced nutritional efficiency and weight gain upon chronic low dose exposure, to emesis, leukocytosis and haemorrhage upon acute high level ingestion. Also human toxicoses related to DON ingestion have been reported. The gastro-intestinal tract is the primary site of DON exposure in terms of timing and amount, and could constitute both a target of and a barrier to DON toxicity. The objective of this research was to determine the impact of DON exposure on inflammatory parameters in human intestinal epithelial cells in vitro. Proliferating and differentiated Caco-2 cells, respectively representative of young/immature, and adult/mature human enterocytes were exposed to realistic intestinal concentrations of DON (50 to 5000 ng/ml) during 24h. The induction of intracellular inflammatory signalling pathways was observed through the activation of the Mitogen Activated Protein Kinases (ERK1/2, JNK and p38) and the transcription factor Nuclear Factor (NF)- κB. DON dose-dependently upregulated the production of the inflammatory mediators IL-8 and PGE-2. These phenomena occurred similarly in proliferating and differentiated cells and were dependent on ERK1/2, JNK and NF-κB activation. The simultaneous exposure to a mixture of inflammatory mediators (IL-1β, TNF-α, IFN-γ and LPS) representative of an acute inflammatory reaction caused synergic increases in IL-8 secretion. Continuous incubation with DON (50 ng/ml) during 21 days increased basal level of IL-8 and PGE-2 production. DON exposure furthermore caused a dose-dependent increase of the paracellular permeability of the Caco-2 monolayer together with a decrease in protein synthesis, with a possible link between these events being the diminished synthesis of the tight junction protein claudin-4. Also intestinal alkaline phosphatase expression, a marker of cellular differentiation, was reduced. The results of this research allow to conclude that DON induces inflammatory parameters in the intestinal epithelium, together with causing a weakening of the monolayer structure and functioning. These observations could be important for human health hazard evaluation regarding DON exposure.(BIOL 3) -- UCL, 200

Influence of deoxynivalenol on NF-kappa B activation and IL-8 secretion in human intestinal Caco-2 cells

Deoxynivalenol (DON) is the most prevalent trichothecene mycotoxin in crops in Europe and North America. In human intestinal Caco-2 cells, DON activates the mitogen-activated protein kinases (MAPKs). We hypothesized a link between DON ingestion and intestinal inflammation, and used Caco-2 cells to assess the effects of DON, at plausible intestinal concentrations (250- 10,000 ng/ml), on inflammatory mediators acting downstream the MAPKs cascade i.e. activation of nuclear factor-kappa B (NF-kappa B) and interleukin-8 (IL-8) secretion. In addition, Caco-2 cells were co-exposed to pro-inflammatory stimuli in order to mimic an inflamed intestinal epithelium. Dose-dependent increases in NF-kappa B activity and IL-8 secretion were observed, reaching 1.4- and 7.6-fold, respectively using DON at 10 mu g/ml. Phosphorylation of inhibitor-kappa B (I kappa B) increased (1.6-fold) at DON levels <0.5 mu g/ml. Exposure of Caco-2 cells to pro-inflammatory agents, i.e. 25 ng/ml interleukin-1 beta, 100 ng/ml tumor necrosis factor-alpha or 10 mu g/ml lipopolysaccharides, activated NF-kappa B and increased IL-8 secretion. Synergistic interactions between these stimuli and DON were observed. These data show that DON induces NF-kappa B activation and IL-8 secretion dose-dependently in Caco-2 cells, and this effect was accentuated upon pro-inflammatory stimulation, suggesting DON exposure could cause or exacerbate intestinal inflammation. (C) 2008 Elsevier Ireland Ltd. All rights reserved

Inflammatory parameters in Caco-2 cells: Effect of stimuli nature, concentration, combination and cell differentiation

Enterocytes regulate gut maintenance and defence by secreting and responding to inflammatory mediators and by modulating the intestinal epithelial permeability. In order to develop an in vitro model of the acute phase of intestinal inflammation, Caco-2 cells were exposed to the inflammatory mediators IL-1 beta, TNF-alpha, IFN-gamma and LPS, and the importance of several experimental parameters, i.e. cell differentiation, stimulus nature, concentration and combination on the inflammatory response was assessed by measuring the production of IL-6, IL-8, PGE-2 and NO and by evaluating the monolayer permeability. A maximal increase in IL-8, IL-6 and PGE-2 production and monolayer permeability was observed when using the cytokines simultaneously at their highest level, but this relied mainly on IL-1 beta. The effects of TNF-alpha on IL-8 and IL-6 or NO production were stronger upon combination with IL-1 beta or IFN-gamma, respectively, whereas cells were unaffected by the presence of LPS. Although NO production, induced by IFN-gamma-containing combinations, was observed only in differentiated cells, general inflammatory response was higher in proliferating cells. The use of a mixture of IL-1 beta, TNF-alpha and IFN-gamma thus accurately mimics intestinal inflammatory processes, but cell differentiation and stimuli combination are important parameters to take into account for in vitro studies on intestinal inflammation. (C) 2010 Published by Elsevier Ltd