Activation of the aryl hydrocarbon receptor (AHR) by environmental xenobiotic toxic chemicals, fo... more Activation of the aryl hydrocarbon receptor (AHR) by environmental xenobiotic toxic chemicals, for instance 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), has been implicated in a variety of cellular processes such as embryogenesis, transformation, tumorigenesis and inflammation. But the identity of an endogenous ligand activating the AHR under physiological conditions in the absence of environmental toxic chemicals is still unknown. Here we identify the tryptophan (Trp) catabolite kynurenine (Kyn) as an endogenous ligand of the human AHR that is constitutively generated by human tumour cells via tryptophan-2,3-dioxygenase (TDO), a liver- and neuron-derived Trp-degrading enzyme not yet implicated in cancer biology. TDO-derived Kyn suppresses antitumour immune responses and promotes tumour-cell survival and motility through the AHR in an autocrine/paracrine fashion. The TDO-AHR pathway is active in human brain tumours and is associated with malignant progression and poor survival. Because Kyn is produced during cancer progression and inflammation in the local microenvironment in amounts sufficient for activating the human AHR, these results provide evidence for a previously unidentified pathophysiological function of the AHR with profound implications for cancer and immune biology.
HMG-CoA-reductase inhibitors (statins) influence lipid metabolism and have pleiotropic effects. S... more HMG-CoA-reductase inhibitors (statins) influence lipid metabolism and have pleiotropic effects. Several statins reduce various forms of pulmonary hypertension (PH) in animal models. The relationship between atorvastatin and expression of serotonin transporter protein (5-HTT) remains unknown. This study focused on the effects of atorvastatin on the course of monocrotaline (MCT)-induced PH and its relation to 5-HTT expression. Male Sprague-Dawley rats were challenged with MCT with or without subsequent daily oral treatment with 0.1, 1, and 10 mg/kg of atorvastatin for 28 days. Over the 4-wk course, the progression of PH was followed by transthoracic echocardiography [pulmonary artery pressure was assessed by pulmonary artery flow acceleration time (PAAT), an estimate reciprocal to pulmonary artery pressure], and, at the end of the 4-wk course, invasive right ventricular pressure, right ventricular weight, quantitative morphology, and 5-HTT expression were measured. MCT caused signific...
Although the effects of high concentrations of the carcinogen benzo[a]pyrene (B[a]P) have been st... more Although the effects of high concentrations of the carcinogen benzo[a]pyrene (B[a]P) have been studied extensively, little is known about its effects at subacute toxic concentrations, which are typical for environmental pollutants. We exposed murine Hepa1c1c7 cells to a toxic concentration (5 μM) and a subacute concentration (50 nM) of B[a]P over a period of 2-24 h to differentiate between acute and pseudochronic effects and conducted a time-course analysis of B[a]P-influenced protein expression by DIGE. In total, a set of 120 spots were found to be significantly altered due to B[a]P exposure of which 112 were subsequently identified by mass spectrometry. Clustering and principal component analysis were conducted to identify sets of proteins responding in a concerted manner to the exposure. Our results indicate an immediate response to the contaminant at the protein level and demonstrate that B[a]P exposure alters the cellular response by disturbing proteins involved in oxidative stress, cell cycle regulation, apoptosis, and cytoskeleton organization. Furthermore, network analysis of protein-protein interactions revealed a complex network of interacting, B[a]P-regulated proteins mostly belonging to the cytoskeleton organization and several signal transduction pathways.
T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium... more T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium and a common contaminant detectable in staple foods of cereal origin. In the present study the impact of this mycotoxin on the inflammatory response of the intestinal epithelial cell line Caco-2 was examined by measuring interleukin (IL)-8 secretion. A T-2 concentration dependent IL-8 up-regulation was detected in IL-1β stimulated and unstimulated Caco-2 cells. To elucidate the possible underlying molecular mechanism of this conditional T-2-provoked IL-8 induction, a possible involvement of the aryl hydrocarbon receptor (AHR) and the mitogen-activated protein kinase (MAPK) pathway was investigated. Like benzo-[a]-pyrene (B[a]P), a well known AHR ligand, T-2 led to cytochrome P450 1A1 (CYP1A1) mRNA expression in Caco-2 cells, which could be inhibited by the AHR antagonist resveratrol. However, resveratrol did not influence T-2-dependent IL-8 induction. Since T-2 did not lead to AHR-trans...
BACKGROUND: One of the most promising strategies to face the increasing asthma prevalence and to ... more BACKGROUND: One of the most promising strategies to face the increasing asthma prevalence and to prevent disease development might be an early contact with microbial compounds. However, little is known about an interaction between an early-life contact to microbial compounds leading to asthma protection in the offspring and a co-exposure to allergy-promoting pollutants. METHODS: Pregnant BALB/c mice were repeatedly exposed to aerosolized endotoxin (lipopolysaccharide, LPS). The offspring was further exposed to aerosolized LPS before allergen sensitization with ovalbumin (OVA). Some of the mice were co-exposed to mycotoxins or diesel exhaust particles (DEP) during pregnancy. The 6-week-old offspring was immunized with OVA and analyzed in a murine asthma model. RESULTS: While the offspring of naive mothers developed an asthma-like phenotype, the offspring of mice perinatally exposed to LPS was significantly protected. Co-exposure of mice to mycotoxins or DEP during pregnancy inhibited...
T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium... more T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium and a common contaminant detectable in staple foods of cereal origin. In the present study the impact of this mycotoxin on the inflammatory response of the intestinal epithelial cell line Caco-2 was examined by measuring interleukin (IL)-8 secretion. A T-2 concentration dependent IL-8 up-regulation was detected in IL-1β stimulated and unstimulated Caco-2 cells. To elucidate the possible underlying molecular mechanism of this conditional T-2-provoked IL-8 induction, a possible involvement of the aryl hydrocarbon receptor (AHR) and the mitogen-activated protein kinase (MAPK) pathway was investigated. Like benzo-[a]-pyrene (B[a]P), a well known AHR ligand, T-2 led to cytochrome P450 1A1 (CYP1A1) mRNA expression in Caco-2 cells, which could be inhibited by the AHR antagonist resveratrol. However, resveratrol did not influence T-2-dependent IL-8 induction. Since T-2 did not lead to AHR-trans...
Journal of physiology and pharmacology : an official journal of the Polish Physiological Society, 2007
Pretreatment with cyclosporine (CsA) decreases infarct size 24h after myocardial ischemia/reperfu... more Pretreatment with cyclosporine (CsA) decreases infarct size 24h after myocardial ischemia/reperfusion (I/R). The goal of this study was to determine effects of CsA pretreatment on long-term cardiac function after I/R-injury. Rats were randomly assigned to group-1: vehicle-only, group-2: CsA-5mg/kg/day, and group-3: CsA-12.5mg/kg/day given orally for three days prior to I/R-injury (30 min of left anterior descending coronary artery occlusion). Post-I/R survival and cardiac function were evaluated 14 days after I/R-injury by echocardiography and invasive hemodynamic measurements. Rats with I/R-injury showed increased left ventricular pressure (LVEDP) compared to rats without I/R-injury (p<0.005). Although CsA initially decreased infarct size, no differences of LVEDP were seen 14 days after I/R-injury (vehicle: 21.2+/-8.9 mmHg, CsA-5mg/kg/day: 21.5+/-0.7 mmHg, CsA-12.5mg/kg/day: 20.5+/-9.4 mmHg). Ejection fraction and fractional shortening were decreased compared to baseline, but sh...
Benzo[a]pyrene (B[a]P) is an environmental contaminant mainly studied for its toxic/carcinogenic ... more Benzo[a]pyrene (B[a]P) is an environmental contaminant mainly studied for its toxic/carcinogenic effects. For a comprehensive and pathway orientated mechanistic understanding of the effects directly triggered by a toxic (5 μM) or a subtoxic (50 nM) concentration of B[a]P or indirectly by its metabolites, we conducted time series experiments for up to 24 h to study the effects in murine hepatocytes. These cells rapidly take up and actively metabolize B[a]P, which was followed by quantitative analysis of the concentration of intracellular B[a]P and seven representative degradation products. Exposure with 5 μM B[a]P led to a maximal intracellular concentration of 1604 pmol/5 × 10(4) cells, leveling at 55 pmol/5 × 10(4) cells by the end of the time course. Changes in the global proteome (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;1000 protein profiles) and metabolome (163 metabolites) were assessed in combination with B[a]P degradation. Abundance profiles of 236 (both concentrations), 190 (only 5 μM), and 150 (only 50 nM) proteins were found to be regulated in response to B[a]P in a time-dependent manner. At the endogenous metabolite level amino acids, acylcarnitines and glycerophospholipids were particularly affected by B[a]P. The comprehensive chemical, proteome and metabolomic data enabled the identification of effects on the pathway level in a time-resolved manner. So in addition to known alterations, also protein synthesis, lipid metabolism, and membrane dysfunction were identified as B[a]P specific effects.
There is a clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have... more There is a clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have detrimental effects on the immune system, whereas the underlying mechanisms still remain elusive. Jurkat T cells share many properties with native T lymphocytes and therefore are an appropriate model to analyze the effects of environmental pollutants on T cells and their activation. Since environmental compounds frequently occur at low, not acute toxic concentrations, we analyzed the effects of two subtoxic concentrations, 50nM and 5μM, on non- and activated cells. B[a]P interferes directly with the stimulation process as proven by an altered IL-2 secretion. Furthermore, B[a]P exposure results in significant proteomic changes as shown by DIGE analysis. Pathway analysis revealed an involvement of the AhR independent Nrf2 pathway in the altered processes observed in unstimulated and stimulated cells. A participation of the Nrf2 pathway in the change of IL-2 secretion was confirmed by exposing cells to the Nrf2 activator tBHQ. tBHQ and 5μM B[a]P caused similar alterations of IL-2 secretion and glutamine/glutamate metabolism. Moreover, the proteome changes in unstimulated cells point towards a modified regulation of the cytoskeleton and cellular stress response, which was proven by western blotting. Additionally, there is a strong evidence for alterations in metabolic pathways caused by B[a]P exposure in stimulated cells. Especially the glutamine/glutamate metabolism was indicated by proteome pathway analysis and validated by metabolite measurements. The detrimental effects were slightly enhanced in stimulated cells, suggesting that stimulated cells are more vulnerable to the environmental pollutant model compound B[a]P.
Magnetic Resonance Materials in Physics, Biology and Medicine, 2007
The measurement of different urine components and their changes over time may provide comprehensi... more The measurement of different urine components and their changes over time may provide comprehensive and early information about perinatal metabolic processes and physiological changes. We hypothesized that (1) H-NMR-spectroscopy generating a complex spectral profile without pre-selection of urinary metabolites could identify metabolites determining the neonatal physiological status and discriminating between different metabolic states. We studied spot urine of three groups of neonates (healthy term-born, term-born with non-specific bacterial infections, and preterm neonates) for the first 6 days of life using (1) H-NMR-spectroscopy. In the group of healthy neonates metabolites changing were identified and their excretion patterns compared between groups. Six metabolites indicating physiological changes were identified: N-methylnicotinamide (NAD (+)-pathway), formate, hippurate, betaine (kidney development), taurine (neuronal development), and bile acids (hepatic clearance). While the dynamic changes over the first 6 days were the same for all metabolites in both groups of term-born neonates, the excretion of N-methylnicotinamide and taurine was significantly higher in preterm neonates compared to healthy term neonates and neonates with bacterial infections from the third day after birth (P &lt; 0.05). Urine analysis using (1) H-NMR-spectroscopy could identify markers for perinatal metabolic changes. Further studies have to clarify if the proposed physiological interpretation will correlate with long-term physiological development.
Activation of the aryl hydrocarbon receptor (AHR) by environmental xenobiotic toxic chemicals, fo... more Activation of the aryl hydrocarbon receptor (AHR) by environmental xenobiotic toxic chemicals, for instance 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), has been implicated in a variety of cellular processes such as embryogenesis, transformation, tumorigenesis and inflammation. But the identity of an endogenous ligand activating the AHR under physiological conditions in the absence of environmental toxic chemicals is still unknown. Here we identify the tryptophan (Trp) catabolite kynurenine (Kyn) as an endogenous ligand of the human AHR that is constitutively generated by human tumour cells via tryptophan-2,3-dioxygenase (TDO), a liver- and neuron-derived Trp-degrading enzyme not yet implicated in cancer biology. TDO-derived Kyn suppresses antitumour immune responses and promotes tumour-cell survival and motility through the AHR in an autocrine/paracrine fashion. The TDO-AHR pathway is active in human brain tumours and is associated with malignant progression and poor survival. Because Kyn is produced during cancer progression and inflammation in the local microenvironment in amounts sufficient for activating the human AHR, these results provide evidence for a previously unidentified pathophysiological function of the AHR with profound implications for cancer and immune biology.
HMG-CoA-reductase inhibitors (statins) influence lipid metabolism and have pleiotropic effects. S... more HMG-CoA-reductase inhibitors (statins) influence lipid metabolism and have pleiotropic effects. Several statins reduce various forms of pulmonary hypertension (PH) in animal models. The relationship between atorvastatin and expression of serotonin transporter protein (5-HTT) remains unknown. This study focused on the effects of atorvastatin on the course of monocrotaline (MCT)-induced PH and its relation to 5-HTT expression. Male Sprague-Dawley rats were challenged with MCT with or without subsequent daily oral treatment with 0.1, 1, and 10 mg/kg of atorvastatin for 28 days. Over the 4-wk course, the progression of PH was followed by transthoracic echocardiography [pulmonary artery pressure was assessed by pulmonary artery flow acceleration time (PAAT), an estimate reciprocal to pulmonary artery pressure], and, at the end of the 4-wk course, invasive right ventricular pressure, right ventricular weight, quantitative morphology, and 5-HTT expression were measured. MCT caused signific...
Although the effects of high concentrations of the carcinogen benzo[a]pyrene (B[a]P) have been st... more Although the effects of high concentrations of the carcinogen benzo[a]pyrene (B[a]P) have been studied extensively, little is known about its effects at subacute toxic concentrations, which are typical for environmental pollutants. We exposed murine Hepa1c1c7 cells to a toxic concentration (5 μM) and a subacute concentration (50 nM) of B[a]P over a period of 2-24 h to differentiate between acute and pseudochronic effects and conducted a time-course analysis of B[a]P-influenced protein expression by DIGE. In total, a set of 120 spots were found to be significantly altered due to B[a]P exposure of which 112 were subsequently identified by mass spectrometry. Clustering and principal component analysis were conducted to identify sets of proteins responding in a concerted manner to the exposure. Our results indicate an immediate response to the contaminant at the protein level and demonstrate that B[a]P exposure alters the cellular response by disturbing proteins involved in oxidative stress, cell cycle regulation, apoptosis, and cytoskeleton organization. Furthermore, network analysis of protein-protein interactions revealed a complex network of interacting, B[a]P-regulated proteins mostly belonging to the cytoskeleton organization and several signal transduction pathways.
T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium... more T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium and a common contaminant detectable in staple foods of cereal origin. In the present study the impact of this mycotoxin on the inflammatory response of the intestinal epithelial cell line Caco-2 was examined by measuring interleukin (IL)-8 secretion. A T-2 concentration dependent IL-8 up-regulation was detected in IL-1β stimulated and unstimulated Caco-2 cells. To elucidate the possible underlying molecular mechanism of this conditional T-2-provoked IL-8 induction, a possible involvement of the aryl hydrocarbon receptor (AHR) and the mitogen-activated protein kinase (MAPK) pathway was investigated. Like benzo-[a]-pyrene (B[a]P), a well known AHR ligand, T-2 led to cytochrome P450 1A1 (CYP1A1) mRNA expression in Caco-2 cells, which could be inhibited by the AHR antagonist resveratrol. However, resveratrol did not influence T-2-dependent IL-8 induction. Since T-2 did not lead to AHR-trans...
BACKGROUND: One of the most promising strategies to face the increasing asthma prevalence and to ... more BACKGROUND: One of the most promising strategies to face the increasing asthma prevalence and to prevent disease development might be an early contact with microbial compounds. However, little is known about an interaction between an early-life contact to microbial compounds leading to asthma protection in the offspring and a co-exposure to allergy-promoting pollutants. METHODS: Pregnant BALB/c mice were repeatedly exposed to aerosolized endotoxin (lipopolysaccharide, LPS). The offspring was further exposed to aerosolized LPS before allergen sensitization with ovalbumin (OVA). Some of the mice were co-exposed to mycotoxins or diesel exhaust particles (DEP) during pregnancy. The 6-week-old offspring was immunized with OVA and analyzed in a murine asthma model. RESULTS: While the offspring of naive mothers developed an asthma-like phenotype, the offspring of mice perinatally exposed to LPS was significantly protected. Co-exposure of mice to mycotoxins or DEP during pregnancy inhibited...
T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium... more T-2 toxin (T-2) is a secondary metabolite produced by various mould species of the genus Fusarium and a common contaminant detectable in staple foods of cereal origin. In the present study the impact of this mycotoxin on the inflammatory response of the intestinal epithelial cell line Caco-2 was examined by measuring interleukin (IL)-8 secretion. A T-2 concentration dependent IL-8 up-regulation was detected in IL-1β stimulated and unstimulated Caco-2 cells. To elucidate the possible underlying molecular mechanism of this conditional T-2-provoked IL-8 induction, a possible involvement of the aryl hydrocarbon receptor (AHR) and the mitogen-activated protein kinase (MAPK) pathway was investigated. Like benzo-[a]-pyrene (B[a]P), a well known AHR ligand, T-2 led to cytochrome P450 1A1 (CYP1A1) mRNA expression in Caco-2 cells, which could be inhibited by the AHR antagonist resveratrol. However, resveratrol did not influence T-2-dependent IL-8 induction. Since T-2 did not lead to AHR-trans...
Journal of physiology and pharmacology : an official journal of the Polish Physiological Society, 2007
Pretreatment with cyclosporine (CsA) decreases infarct size 24h after myocardial ischemia/reperfu... more Pretreatment with cyclosporine (CsA) decreases infarct size 24h after myocardial ischemia/reperfusion (I/R). The goal of this study was to determine effects of CsA pretreatment on long-term cardiac function after I/R-injury. Rats were randomly assigned to group-1: vehicle-only, group-2: CsA-5mg/kg/day, and group-3: CsA-12.5mg/kg/day given orally for three days prior to I/R-injury (30 min of left anterior descending coronary artery occlusion). Post-I/R survival and cardiac function were evaluated 14 days after I/R-injury by echocardiography and invasive hemodynamic measurements. Rats with I/R-injury showed increased left ventricular pressure (LVEDP) compared to rats without I/R-injury (p<0.005). Although CsA initially decreased infarct size, no differences of LVEDP were seen 14 days after I/R-injury (vehicle: 21.2+/-8.9 mmHg, CsA-5mg/kg/day: 21.5+/-0.7 mmHg, CsA-12.5mg/kg/day: 20.5+/-9.4 mmHg). Ejection fraction and fractional shortening were decreased compared to baseline, but sh...
Benzo[a]pyrene (B[a]P) is an environmental contaminant mainly studied for its toxic/carcinogenic ... more Benzo[a]pyrene (B[a]P) is an environmental contaminant mainly studied for its toxic/carcinogenic effects. For a comprehensive and pathway orientated mechanistic understanding of the effects directly triggered by a toxic (5 μM) or a subtoxic (50 nM) concentration of B[a]P or indirectly by its metabolites, we conducted time series experiments for up to 24 h to study the effects in murine hepatocytes. These cells rapidly take up and actively metabolize B[a]P, which was followed by quantitative analysis of the concentration of intracellular B[a]P and seven representative degradation products. Exposure with 5 μM B[a]P led to a maximal intracellular concentration of 1604 pmol/5 × 10(4) cells, leveling at 55 pmol/5 × 10(4) cells by the end of the time course. Changes in the global proteome (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;1000 protein profiles) and metabolome (163 metabolites) were assessed in combination with B[a]P degradation. Abundance profiles of 236 (both concentrations), 190 (only 5 μM), and 150 (only 50 nM) proteins were found to be regulated in response to B[a]P in a time-dependent manner. At the endogenous metabolite level amino acids, acylcarnitines and glycerophospholipids were particularly affected by B[a]P. The comprehensive chemical, proteome and metabolomic data enabled the identification of effects on the pathway level in a time-resolved manner. So in addition to known alterations, also protein synthesis, lipid metabolism, and membrane dysfunction were identified as B[a]P specific effects.
There is a clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have... more There is a clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have detrimental effects on the immune system, whereas the underlying mechanisms still remain elusive. Jurkat T cells share many properties with native T lymphocytes and therefore are an appropriate model to analyze the effects of environmental pollutants on T cells and their activation. Since environmental compounds frequently occur at low, not acute toxic concentrations, we analyzed the effects of two subtoxic concentrations, 50nM and 5μM, on non- and activated cells. B[a]P interferes directly with the stimulation process as proven by an altered IL-2 secretion. Furthermore, B[a]P exposure results in significant proteomic changes as shown by DIGE analysis. Pathway analysis revealed an involvement of the AhR independent Nrf2 pathway in the altered processes observed in unstimulated and stimulated cells. A participation of the Nrf2 pathway in the change of IL-2 secretion was confirmed by exposing cells to the Nrf2 activator tBHQ. tBHQ and 5μM B[a]P caused similar alterations of IL-2 secretion and glutamine/glutamate metabolism. Moreover, the proteome changes in unstimulated cells point towards a modified regulation of the cytoskeleton and cellular stress response, which was proven by western blotting. Additionally, there is a strong evidence for alterations in metabolic pathways caused by B[a]P exposure in stimulated cells. Especially the glutamine/glutamate metabolism was indicated by proteome pathway analysis and validated by metabolite measurements. The detrimental effects were slightly enhanced in stimulated cells, suggesting that stimulated cells are more vulnerable to the environmental pollutant model compound B[a]P.
Magnetic Resonance Materials in Physics, Biology and Medicine, 2007
The measurement of different urine components and their changes over time may provide comprehensi... more The measurement of different urine components and their changes over time may provide comprehensive and early information about perinatal metabolic processes and physiological changes. We hypothesized that (1) H-NMR-spectroscopy generating a complex spectral profile without pre-selection of urinary metabolites could identify metabolites determining the neonatal physiological status and discriminating between different metabolic states. We studied spot urine of three groups of neonates (healthy term-born, term-born with non-specific bacterial infections, and preterm neonates) for the first 6 days of life using (1) H-NMR-spectroscopy. In the group of healthy neonates metabolites changing were identified and their excretion patterns compared between groups. Six metabolites indicating physiological changes were identified: N-methylnicotinamide (NAD (+)-pathway), formate, hippurate, betaine (kidney development), taurine (neuronal development), and bile acids (hepatic clearance). While the dynamic changes over the first 6 days were the same for all metabolites in both groups of term-born neonates, the excretion of N-methylnicotinamide and taurine was significantly higher in preterm neonates compared to healthy term neonates and neonates with bacterial infections from the third day after birth (P &lt; 0.05). Urine analysis using (1) H-NMR-spectroscopy could identify markers for perinatal metabolic changes. Further studies have to clarify if the proposed physiological interpretation will correlate with long-term physiological development.
Uploads
Papers by Saskia Trump