Fumonisin B1 exposure and its selective effect on porcine jejunal segment: sphingolipids, glycolipids and trans-epithelial passage disturbance.

Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium verticillioides, the cause of Fusarium kernel rot in maize. FB(1) is toxic in domestic and laboratory animals, including pigs. This study investigated the effects of a seven-days-exposure of 1.5mg/kg b.w. FB(1) on the porcine intestinal epithelium. Statistically significant increases in the ratio of sphinganine to sphingosine, as well as alterations of the glycolipid distribution were observed in the jejunum. Using a porcine intestinal epithelial cell line (IPEC-1) derived from jejunum and ileum, we tested the effect of FB(1)in vitro in a time- and dose-dependent fashion. A significant increase in sphinganine concentration was observed after 2 days of FB(1) exposure at concentrations >100 microM, or from 6 days of FB(1) exposure at concentration >20 microM. We were also able to show that FB(1) exposure at 200 microM during 16 days increased the intestinal trans-epithelial flux of FB(1). These data indicate that, in pigs, this mycotoxin acts selectively on jejunum cells as follows: (i) FB(1) affects sphingolipid metabolism, as demonstrated by an increase of the amount of free sphingoid bases in a time- and dose-dependent manner, (ii) a depletion of the glycolipids in plasma membranes is observed, and (iii) an increase occurs in the trans-epithelial flux.

The intestine as a possible target for fumonisin toxicity.

Fumonisins constitute a family of toxic and carcinogenic mycotoxins produced by Fusarium verticillioides (formerly F. moniliforme), a common fungal contaminant of corn. Contamination with fumonisin B(1) (FB(1)) is of concern as this mycotoxin causes various animal diseases. The gastrointestinal tract represents the first barrier against ingested chemicals, food contaminants, and natural toxins. Following ingestion of fumonisin-contaminated food or feed, intestinal epithelial cells could be exposed to a high concentration of toxin. In this review, we have summarized the data dealing with the impact of FB(1) on the intestine. Although FB(1 )is poorly absorbed and metabolized in the intestine, it induces intestinal disturbances (abdominal pain or diarrhea) and causes extra-intestinal organ pathologies (pulmonary edema, leukoencephalomalacia, or neural tube defects). The main toxicological effect of FB(1) reported in vivo and in vitro is the accumulation of sphingoid bases associated with the depletion of complex sphingolipids. This disturbance of the sphingolipid biosynthesis pathway could explain the other observed toxicological effects such as an alteration in intestinal epithelial cell viability and proliferation, a modification of cytokine production, and a modulation of intestinal physical barrier function.

Mycotoxin fumonisin B1 selectively down-regulates the basal IL-8 expression in pig intestine: in vivo and in vitro studies.

Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium verticillioides and F. proliferatum, common contaminants of maize. FB(1) causes toxicological effects in laboratory and domestic animals including pigs. The gastrointestinal tract represents a barrier encountered by exogenous food compounds. The purpose of our study was to determine FB(1) effects on intestinal immune response. Nine recently weaned piglets orally received 0.5 mg of purified toxin/kg of body weight/day for 7 days, while eight other animals were kept as controls. After necropsy, ileal samples were analyzed for five pro-inflammatory cytokines mRNA expression by RT-PCR. No difference was observed for IL-1beta, IL-6, IL-12 and TNF-beta mRNA levels between control and FB(1)-treated animals. In contrast, FB(1) treatment induced a significant down-regulation of the expression of IL-8 mRNA in the pig ilea. The effect of FB(1) on the IL-8 expression was also examined in the porcine intestinal epithelial cell line IPEC-1. FB(1) decreases the expression of IL-8, both at the mRNA and protein levels, in a dose-dependant manner. Taken together, our data demonstrate that FB(1) alters the intestinal immune response by decreasing the level of IL-8. This may contribute to the increased intestinal colonization by pathogenic Escherichia coli that was observed in FB(1)-treated pigs and may have implications for humans/animals consuming FB(1)-contaminated food/feed.

Mycotoxin fumonisin B1 alters the cytokine profile and decreases the vaccinal antibody titer in pigs.

Fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, may contaminate feed and food. In the present study, we investigated the effect of FB1 on the modulation of the cytokine profile and on the establishment of a vaccinal antibody response. In vitro investigations on pig peripheral blood mononuclear cells (PBMC) indicate that FB1 decreased interleukin-4 (IL-4) and increased interferon-gamma (IFN-gamma) synthesis at both the protein and mRNA levels. A short in vivo exposure (7 days) of weanling piglets to 1.5 mg/kg body weight of purified FB1 altered the cytokine balance in mesenteric lymph nodes and spleen similarly to the in vitro PBMC results. We also investigated the effect of FB1 on the antibody response during a vaccination process. A prolonged in vivo exposure (28 days) of weanling piglets to feed contaminated with 8 mg FB1/kg significantly decreased the expression of IL-4 mRNA by porcine whole blood cells and diminished the specific antibody titer after vaccination against Mycoplasma agalactiae. By contrast, ingestion of the contaminated feed had no effect on the serum concentration of the immunoglobulin subset (IgG, IgA, and IgM). Taken together, our data suggest that FB1 alters the cytokine profile and decreases the specific antibody response built during a vaccination protocol. These results may have implications for humans or animals eating contaminated food or feed.

Oral exposure to culture material extract containing fumonisins predisposes swine to the development of pneumonitis caused by Pasteurellamultocida.

Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium verticillioides and F. proliferatum that commonly occurs in maize. In swine, consumption of contaminated feed induces liver damage and pulmonary edema. Pasteurella multocida is a secondary pathogen, which can generate a respiratory disorder in predisposed pigs. In this study, we examined the effect of oral exposure to fumonisin-containing culture material on lung inflammation caused by P. multocida. Piglets received by gavage a crude extract of fumonisin, 0.5mg FB(1)/kg body weight/day, for 7 days. One day later, the animals were instilled intratracheally with a non toxin producing type A strain of P. multocida and followed up for 13 additional days. Pig weight and cough frequency were measured throughout the experiment. Lung lesions, bronchoalveolar lavage fluid (BALF) cell composition and the expression of inflammatory cytokines were evaluated at the autopsy. Ingestion of fumonisin culture material or infection with P. multocida did not affect weight gain, induced no clinical sign or lung lesion, and only had minimal effect on BALF cell composition. Ingestion of mycotoxin extract increased the expression of IL-8, IL-18 and IFN-gamma mRNA compared with P. multocida infection that increased the expression of TNF-alpha. The combined treatment with fumonisin culture material and P. multocida delayed growth, induced cough, and increased BALF total cells, macrophages and lymphocytes. Lung lesions were significantly enhanced in these animals and consisted of subacute interstitial pneumonia. TNF-alpha, IFN-gamma and IL-18 mRNA expression was also increased. Taken together, our data showed that fumonisin culture material is a predisposing factor to lung inflammation. These results may have implications for humans and animals consuming FB(1) contaminated food or feed.

The effects of mycotoxins, fungal food contaminants, on the intestinal epithelial cell-derived innate immune response.

Mycotoxins are structurally diverse fungal metabolites that can contaminate a variety of dietary components consumed by animals and humans. It is considered that 25% of the world crop production is contaminated by mycotoxins. The clinical toxicological syndromes caused by ingestion of moderate to high amounts of mycotoxins and their effect on the immune system have been well characterized. However, no particular attention has been focused on the effects of mycotoxins on the local intestinal immune response. Because of their location, intestinal epithelial cells (IECs) could be exposed to high doses of mycotoxins. As a component of the innate local immune response, intestinal epithelial cells have developed a variety of mechanisms which act to reduce the risk of infection by microorganisms or intoxication by toxic compounds. This review summarises the innate immune response developed by intestinal epithelial cells and reports the literature concerning the effects of mycotoxins on them. Particularly, the effects of mycotoxins on the maintenance of a physical barrier by epithelial cells will be discussed together with their effect on extrinsic protective components of the innate intestinal immunity: mucus secretion, antimicrobial peptide generation, IgA and pro-inflammatory cytokine release.

The mycotoxin fumonisin B1 alters the proliferation and the barrier function of porcine intestinal epithelial cells.

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides (formerly F. moniliforme), a fungus that commonly contaminates maize. FB1 causes toxicological effects in laboratory and domestic animals including pigs. Because the gastrointestinal tract represents the first barrier met by exogenous food compounds, the purpose of this study was to investigate the effects of FB1 on IPEC-1, a porcine intestinal epithelial cell line. We first verified that low concentrations of FB1 did not exert any cytotoxic effect on IPEC-1. Indeed, significant LDH release was only observed for FB1 concentrations greater than 50 and 700 microM on proliferating and nonproliferating cells, respectively. We then demonstrated that FB1 inhibits proliferation of IPEC-1. Fluorescence-activated cell sorting (FACS) analysis of the cell cycle indicated that FB1 blocks the proliferation of intestinal cells in the G0/G1 phase. Similar results were obtained with LLC-PK1, a renal porcine epithelial cell line, which is considered to be a good model for studying FB1 in vitro effects. We have also assessed the effects of FB1 on the integrity of the barrier formed by the intestinal epithelium. We demonstrated that FB1 decreases the transepithelial electrical resistance (TEER) of IPEC-1 in a time- and dose-dependent manner. This effect was only noticed after a long exposure (8-12 days of treatment). FB1 induced the TEER decrease independently of the cell differentiation stage, and this effect was partially reversible. Taken together, our data indicate that FB1 alters the proliferation and the barrier function of intestinal cells. These results may have implications for humans and animals consuming FB1-contaminated food or feed.

The IFNgamma-induced STAT1-CBP/P300 association, required for a normal response to the cytokine, is disrupted in Brucella-infected macrophages.

To develop intracellularly within phagocytes and cause chronic infection, Brucella must overcome different steps of the host immune responses. IFNgamma is a key mediator of the innate and adaptive responses produced during Brucella infection. Therefore, Brucella would control host defenses by impairing macrophage responses to IFNgamma. We first showed that in infected human macrophages (VD3-differentiated THP-1 cells) Brucella escaped the microbicidal environment generated by IFNgamma. We then analyzed the IFNgamma-mediated signaling in Brucella-infected cells. We observed no decrease in STAT1 tyrosine or serine phosphorylation, or in dimerization of phosphorylated STAT1 (P-STAT1) and P-STAT1 translocation to the nucleus or in P-STAT1 binding to GAS, a minimal IFNgamma-response DNA sequence. In contrast, immuno-precipitation experiments indicated that the IFNgamma-mediated association of P-STAT1 with CBP/P300 transactivators was markedly reduced in infected macrophages, demonstrating that P-STAT1 was unable to normally recruit these transactivators. The host cell cAMP pathway triggered by Brucella could be responsible for this defect, CBP/P300 mobilization by phosphorylated CREB (P-CREB) disrupting the IFNgamma-induced STAT1-CBP/P300 association, required for a normal response of macrophages to IFNgamma. In any case, the inhibition of an essential protein-protein interaction probably lead to a deteriorated response to IFNgamma and thus participated in the pathogen's establishment within its host.

Pathophysiological changes occurring during Escherichia coli endotoxin and Pasteurella multocida challenge in piglets: relationship with cough and temperature and predicitive value for intensity of lesions.

The aims of this study were (1) to correlate cough and body temperature (BT) with the severity of bronchopneumonia in pigs, (2) to determine whether these clinical signs can be used to early diagnose bronchopneumonia and (3) to assess the predictive values of cough and BT regarding lung lesions. Bronchopneumonia was induced by administering E. coli endotoxin (LPS) combined with Pasteurella multocida type A (PmA) in the trachea of 13 piglets. Saline-instilled negative controls (n = 8), PmA inoculated (n = 6) and LPS instilled (n = 5) groups were also constituted. Cough and BT were recorded daily while the bronchopneumonia severity was assessed using bronchoalveolar lavage fluid (BALF) cytology, cytokines and measurement of lung lesion volume. Changes in expiratory breathing pattern were also measured (Penh). The combination of LPS and PmA induced a subacute bronchopneumonia characterised by macrophage, neutrophil, and lymphocyte infiltration, changes in Penh and an increase in the mRNA level of IFN-gamma while IL8, IL-18 and TNF-alpha mRNA levels remained unchanged. The daily body weight gain of infected animals was significantly reduced. Cough and BT changes were proportional to the intensity of the lung inflammatory process, functional respiratory changes and to the extent of macroscopic lesions. When comparing the individual values of cough and BT to thresholds defined for both parameters, an early diagnosis of pneumonia was possible. Considering the pooled data of each group, it was possible to define thresholds allowing an early segregation between the groups of diseased and healthy piglets. The daily values of cough and BT were predictive for the volume of lung lesions recorded at the end of the trial. In conclusion, cough and BT appear as potential indicators for the intensity and the evolution of the respiratory disease. They also seem to be good predictors for the magnitude of lung lesions and weight gain recorded at the study endpoint.