Deoxynivalenol alters circulating and splenic leukocytes and cell migration markers in interaction with time course and sex in young and old BALB/c mice

Deoxynivalenol (DON), produced by Fusarium graminearum and Fusarium culmorum , is commonly found in wheat, corn, oats and barley. We hypothesize DON exposure could change leukocyte subset number and their migration potential in peripheral blood with interaction of age and sex, which could be sensitive biomarkers to predict DON exposure for human epidemiological screening. The first mouse study was done in 6-7 week old BALB/c mice. Peripheral blood (PB) and splenic leukocytes were stained and detected by flow cytometry. The results showed the percentage of B cells (CD19+) in PB was reduced in both sexes at 1.0 and 2.0 ppm at 14 d, with no reduction of B cells after 28 d. Monocytes (CD11b+) in PB and macrophage cells (CD11b+) in spleen were decreased in female BALB/c mice at 1.0 and 2.0 ppm after 28 d, which suggested sex hormones interacted with DON immunotoxicity. No toxicity was observed at doses 0.5 ppm or less. The second mouse study was done in 2-3 month old and 16 month old BALB/c mice. Granulocytes in both ages and sexes were increased at 1.0 and 2.0 ppm DON at 14 d, but normalized after 28 d. Percentage of T helper cells in PB was decreased in young female mice fed 2.0 ppm DON after 14 d, not after 28 d. Percentage of CXCR5+ B cells was decreased in old female mice fed 2.0 ppm DON after 14 d, but not after 28 d. CD29+CD11a+ neutrophils were increased at 1.0 and 2.0 ppm DON in old male mice after 14 d, but no difference was observed after 28 d. CCR9+ T cytotoxic cells were increased in old male mice fed 2.0 ppm DON after 28 d. Taken together, these results suggested DON inhibited T helper cells in young female mice and interrupted B cell, neutrophil and T cytotoxic cell migration potentials in old mice. Most DON toxicity was transient, and interacted with age and sex. In conclusion, the surface markers of leukocytes in PB were changed in BALB/c mice fed 1.0 ppm and 2.0 ppm DON. Age and sex interacted with DON exposure. Most of the effects of DON were temporary, which suggested BALB/c mice adapted to DON exposure

Synthesis and characterization of deoxynivalenol glucuronide : its comparative immunotoxicity with deoxynivalenol

Deoxynivalenol (DON) is a mycotoxin commonly contaminating corn, wheat and barley. DON glucuronide (DONGLU) was synthesized with rat liver microsomes, uridine-5\u27-dephosphoglucuronic acid (UDPGA) and DON. DONGLU was purified with a Sephadex LH-20 column and HPLC (revere phase column, UV at 220 nm). [Beta]- glucuronidase hydrolysis formed a product with retention time and UV spectrum identical with DON. HPLC chromatography of DONGLU reaction mix with/without UDPGA or with/without microsomes showed that only in the complete reaction mix was there a peak more hydrophilic than DON but with similar UV spectrum, putatively DONGLU. DONGLU was further identified by mass spectrometry in negative ionization mode and NMR. The molecular mass (M-1) was 471g/mol, in agreement with DONGLU\u27s expected molecular weight of 472 g/mol. [Beta]- glucuronidase hydrolysis, MS and NMR indicated that the glucuronide moiety was conjugated with the carbon- 3 -hydroxyl group of DON. The cytotoxicity of DON and DONGLU were compared in cell culture using human erythroleukemia cell line K562. 50% inhibition of cell proliferation was observed with a DON concentration of 1.31 [Mu]M using CellTitre96 detection, whereas no significant cytotoxicity was observed for DONGLU at up to 270[Mu]M. DONGLU did not influence DON toxicity at low, medium and high concentration combinations (0.5 [Mu]M, 1.3 [Mu]M and 8.4 [Mu]M) of each compound. These data show that DONGLU is a detoxification product of DON, and that measuring DON without DONGLU in human urine or plasma would be a suitable biomarker of DON exposure and toxicity

Metabolism of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) atropisomers in tissue slices from phenobarbital or dexamethasone-induced rats is sex-dependent.

1. Chiral polychlorinated biphenyls (PCBs) such as PCB 136 enantioselectively sensitize the ryanodine receptor (RyR). In light of recent evidence that PCBs cause developmental neurotoxicity via RyR-dependent mechanisms, this suggests that enantioselective PCB metabolism may influence the developmental neurotoxicity of chiral PCBs. However, enantioselective disposition of PCBs has not been fully characterized. 2. The effect of sex and cytochrome P450 (P450) enzyme induction on the enantioselective metabolism of PCB 136 was studied using liver tissue slices prepared from naïve control (CTL), phenobarbital (PB; CYP2B inducer) or dexamethasone (DEX; CYP3A inducer) pretreated adult Sprague-Dawley rats. PCB 136 metabolism was also examined in hippocampal slices derived from untreated rat pups. 3. In liver tissue slices, hydroxylated PCB (OH-PCB) profiles depended on sex and inducer pretreatment, and OH-PCB levels followed the rank orders male > female and PB > DEX > CTL. In contrast, the enantiomeric enrichment of PCB 136 and its metabolites was independent of sex and inducer pretreatment. Only small amounts of PCB 136 partitioned into hippocampal tissue slices and no OH-PCB metabolites were detected. 4. Our results suggest that enantioselective metabolism, sex and induction status of P450 enzymes in the liver may modulate the neurotoxic outcomes of developmental exposure to chiral PCBs

Synthesis and characterization of deoxynivalenol glucuronide : its comparative immunotoxicity with deoxynivalenol

Deoxynivalenol (DON) is a mycotoxin commonly contaminating corn, wheat and barley. DON glucuronide (DONGLU) was synthesized with rat liver microsomes, uridine-5'-dephosphoglucuronic acid (UDPGA) and DON. DONGLU was purified with a Sephadex LH-20 column and HPLC (revere phase column, UV at 220 nm). [Beta]- glucuronidase hydrolysis formed a product with retention time and UV spectrum identical with DON. HPLC chromatography of DONGLU reaction mix with/without UDPGA or with/without microsomes showed that only in the complete reaction mix was there a peak more hydrophilic than DON but with similar UV spectrum, putatively DONGLU. DONGLU was further identified by mass spectrometry in negative ionization mode and NMR. The molecular mass (M-1) was 471g/mol, in agreement with DONGLU's expected molecular weight of 472 g/mol. [Beta]- glucuronidase hydrolysis, MS and NMR indicated that the glucuronide moiety was conjugated with the carbon- 3 -hydroxyl group of DON. The cytotoxicity of DON and DONGLU were compared in cell culture using human erythroleukemia cell line K562. 50% inhibition of cell proliferation was observed with a DON concentration of 1.31 [Mu]M using CellTitre96 detection, whereas no significant cytotoxicity was observed for DONGLU at up to 270[Mu]M. DONGLU did not influence DON toxicity at low, medium and high concentration combinations (0.5 [Mu]M, 1.3 [Mu]M and 8.4 [Mu]M) of each compound. These data show that DONGLU is a detoxification product of DON, and that measuring DON without DONGLU in human urine or plasma would be a suitable biomarker of DON exposure and toxicity.</p

Deoxynivalenol alters circulating and splenic leukocytes and cell migration markers in interaction with time course and sex in young and old BALB/c mice

Deoxynivalenol (DON), produced by Fusarium graminearum and Fusarium culmorum , is commonly found in wheat, corn, oats and barley. We hypothesize DON exposure could change leukocyte subset number and their migration potential in peripheral blood with interaction of age and sex, which could be sensitive biomarkers to predict DON exposure for human epidemiological screening. The first mouse study was done in 6-7 week old BALB/c mice. Peripheral blood (PB) and splenic leukocytes were stained and detected by flow cytometry. The results showed the percentage of B cells (CD19+) in PB was reduced in both sexes at 1.0 and 2.0 ppm at 14 d, with no reduction of B cells after 28 d. Monocytes (CD11b+) in PB and macrophage cells (CD11b+) in spleen were decreased in female BALB/c mice at 1.0 and 2.0 ppm after 28 d, which suggested sex hormones interacted with DON immunotoxicity. No toxicity was observed at doses 0.5 ppm or less. The second mouse study was done in 2-3 month old and 16 month old BALB/c mice. Granulocytes in both ages and sexes were increased at 1.0 and 2.0 ppm DON at 14 d, but normalized after 28 d. Percentage of T helper cells in PB was decreased in young female mice fed 2.0 ppm DON after 14 d, not after 28 d. Percentage of CXCR5+ B cells was decreased in old female mice fed 2.0 ppm DON after 14 d, but not after 28 d. CD29+CD11a+ neutrophils were increased at 1.0 and 2.0 ppm DON in old male mice after 14 d, but no difference was observed after 28 d. CCR9+ T cytotoxic cells were increased in old male mice fed 2.0 ppm DON after 28 d. Taken together, these results suggested DON inhibited T helper cells in young female mice and interrupted B cell, neutrophil and T cytotoxic cell migration potentials in old mice. Most DON toxicity was transient, and interacted with age and sex. In conclusion, the surface markers of leukocytes in PB were changed in BALB/c mice fed 1.0 ppm and 2.0 ppm DON. Age and sex interacted with DON exposure. Most of the effects of DON were temporary, which suggested BALB/c mice adapted to DON exposure.</p

Hepatic metabolism affects the atropselective disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) in mice.

To understand the role of hepatic vs extrahepatic metabolism in the disposition of chiral PCBs, we studied the disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) and its hydroxylated metabolites (HO-PCBs) in mice with defective hepatic metabolism due to the liver-specific deletion of cytochrome P450 oxidoreductase (KO mice). Female KO and congenic wild type (WT) mice were treated with racemic PCB 136, and levels and chiral signatures of PCB 136 and HO-PCBs were determined in tissues and excreta 3 days after PCB administration. PCB 136 tissue levels were higher in KO compared to WT mice. Feces was a major route of PCB metabolite excretion, with 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol being the major metabolite recovered from feces. (+)-PCB 136, the second eluting PCB 136 atropisomers, was enriched in all tissues and excreta. The second eluting atropisomers of the HO-PCBs metabolites were enriched in blood and liver; 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol in blood was an exception and displayed an enrichment of the first eluting atropisomers. Fecal HO-PCB levels and chiral signatures changed with time and differed between KO and WT mice, with larger HO-PCB enantiomeric fractions in WT compared to KO mice. Our results demonstrate that hepatic and, possibly, extrahepatic cytochrome P450 (P450) enzymes play a role in the disposition of PCBs

Hepatic metabolism affects the atropselective disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) in mice.

To understand the role of hepatic vs extrahepatic metabolism in the disposition of chiral PCBs, we studied the disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) and its hydroxylated metabolites (HO-PCBs) in mice with defective hepatic metabolism due to the liver-specific deletion of cytochrome P450 oxidoreductase (KO mice). Female KO and congenic wild type (WT) mice were treated with racemic PCB 136, and levels and chiral signatures of PCB 136 and HO-PCBs were determined in tissues and excreta 3 days after PCB administration. PCB 136 tissue levels were higher in KO compared to WT mice. Feces was a major route of PCB metabolite excretion, with 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol being the major metabolite recovered from feces. (+)-PCB 136, the second eluting PCB 136 atropisomers, was enriched in all tissues and excreta. The second eluting atropisomers of the HO-PCBs metabolites were enriched in blood and liver; 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol in blood was an exception and displayed an enrichment of the first eluting atropisomers. Fecal HO-PCB levels and chiral signatures changed with time and differed between KO and WT mice, with larger HO-PCB enantiomeric fractions in WT compared to KO mice. Our results demonstrate that hepatic and, possibly, extrahepatic cytochrome P450 (P450) enzymes play a role in the disposition of PCBs

Atropselective Disposition of 2,2\u27,3,4\u27,6-Pentachlorobiphenyl (PCB 91) and Identification of Its Metabolites in Mice with Liver-specific Deletion of Cytochrome P450 Reductase

Cytochrome P450 enzymes oxidize chiral polychlorinated biphenyls (PCBs) to hydroxylated metabolites. Here we investigated the role of an impaired hepatic metabolism in the disposition of PCB 91 (CASRN 68194-05-8) in mice with a liver-specific deletion of the cpr gene (KO mice). KO mice and wild type (WT) mice were exposed to racemic PCB 91. Levels and enantiomeric fractions of PCB 91 and its metabolites were determined in tissues 3-days after PCB exposure. PCB 91 were higher in KO compared to WT mice. The liver of KO mice accumulated PCB 91 due to the high fat content in the liver of KO mice. 2,2\u27,3,4\u27,6-Pentachlorobiphenyl-5-ol was the major metabolite detected in all samples. PCB 91 and its metabolites displayed a genotype-dependent atropisomeric enrichment. These differences in atropselective disposition of PCB 91 and its metabolites are consistent with slower metabolism of PCB 91 in KO than WT mice and the accumulation of the parent PCB in the fatty liver of KO mice.<br /