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Dietmar Fuchs

Publications and source records attributed to Dietmar Fuchs.

At least 73 records · Page 4Linked to original sources
PubMed2004

Possible role of cytokine-induced tryptophan degradation in anaemia of inflammation.

Anaemia of inflammation (AI) is a frequent complication in patients suffering from chronic inflammatory disorders including infections, autoimmune and malignant disease. Cytokine imbalance with a shift towards T-helper (Th)1-type immune response seems to be important in the pathogenesis of this type of anaemia. Interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha may affect the growth and differentiation of erythroid progenitor cells. In macrophages, IFN-gamma strongly induces indoleamine (2,3)-dioxygenase, an enzyme which degrades tryptophan (trp) to kynurenine (kyn). Trp availability is rate limiting for protein biosynthesis and thus cell growth, including erythropoiesis. In this study, trp and kyn concentrations and their relationship to haemoglobin concentrations and to immune activation was examined in 22 patients with AI. Patients with AI presented with lower trp concentrations than healthy controls of similar age, and a significantly higher kyn to trp ratio, suggesting enhanced trp degradation and, because of a positive correlation with neopterin, immune activation. The kyn to trp ratio was inversely correlated to haemoglobin levels. Thus, the limitation of trp availability to erythroid progenitors may be a key mechanism in cytokine-mediated inhibition of erythropoiesis, and the therapeutic modulation of indoleamine (2,3)-dioxygenase and trp levels may be promising targets for AI therapy.

Aged↗
PubMed2004

Cerebrospinal fluid and plasma HIV-1 RNA levels and lopinavir concentrations following lopinavir/ritonavir regimen.

Our objective was to study the effect of lopinavir/ritonavir on cerebrospinal fluid (CSF) viral load as part of an antiretroviral combination treatment for HIV-1 infected individuals, and to determine the steady-state concentrations of lopinavir in CSF in relationship to plasma concentrations. Paired CSF and plasma samples from 12 antiretroviral-naïve HIV-1 infected patients starting combination therapy containing lopinavir/ritonavir were collected at baseline, and during treatment at a first follow-up at median 3.0 months (range 2.6-6.0 months), and at a second follow-up at median 12.1 months (range 6.0-16.5 months). Levels of HIV-1 RNA, CD4+ T-cell count, beta2-microglobulin, neopterin, and lopinavir concentration were analysed. In addition, CSF and plasma lopinavir concentrations in 4 patients already on combination therapy including lopinavir/ritonavir were analysed. Nine of 11 patients had undetectable viral load in CSF and 5/11 in plasma at the first follow-up. At the second follow-up 7/7 had undetectable viral load in CSF and 9/9 in plasma. Intrathecal immunoactivation, measured by neopterin and beta2-microglobulin, decreased significantly both in CSF and serum. The total CSF concentrations of lopinavir were of the same order of magnitude as the unbound concentrations in plasma. Lopinavir mean (+/-SD) concentrations were 42.1 (+/-31.5) nM in CSF and 52.7 (+/-25.2) nM unbound in plasma. We found that antiretroviral combination therapy including lopinavir/ritonavir substantially decreases the viral load, both in CSF and plasma, as well as the intrathecal immunoactivation, measured by beta2-microglobulin and neopterin. CSF concentrations of lopinavir were low, but probably sufficient to have a virological effect.

Adult↗
PubMed2004

Cerebrospinal fluid viral load, virus isolation, and intrathecal immunoactivation in HIV type 2 infection.

Four patients with HIV-2 infection were followed longitudinally with cerebrospinal fluid (CSF) analyses. Two patients had positive CSF HIV-2 isolations. These two patients had CD4 cell count below 200 x 10(6)/liter and maximum CSF HIV-2 RNA viral loads above 4000 copies/ml. Intrathecal immune activation was demonstrated by elevated CSF neopterin concentrations (14-18 nmol/liter). No opportunistic infections were diagnosed. After antiretroviral treatment CSF viral counts decreased to below 125 copies/ml and CSF neopterin concentrations decreased. In two other patients who had CD4 counts within the normal range CSF virus isolations were repeatedly negative and viral CSF loads were below 125 copies/ml. However, a slightly elevated CSF neopterin concentration in one sample and pleocytosis in another might also be caused by HIV-2 in these patients. Before antiretroviral treatment HIV-2 isolations from blood were positive in all four patients. Maximum HIV-2 RNA viral loads were higher in blood than in CSF. Treatment failure in one patient with increasing viral loads in blood did not result in viral rebound in CSF.

Adult↗
PubMed2004

Plasma homocysteine and immune activation in patients with malignant melanoma undergoing treatment with IFN-alpha.

Immune activation and cell proliferation may contribute to the development of increased homocysteine concentrations in patients with malignant diseases. In this study, we investigated the effect of interferon-alpha (IFN-alpha) on plasma homocysteine concentrations in patients being treated for malignant melanoma. In parallel, neopterin formation and tryptophan degradation were monitored to assess the capacity of IFN-alpha to activate macrophages. Plasma concentrations of homocysteine, folate, and vitamin B(12) were determined in 15 patients with malignant melanoma during 12 weeks of high-dose IFN-alpha therapy. Concurrently, concentrations of neopterin, tryptophan, and kynurenine were measured, and the kynurenine/tryptophan ratio (kyn/trp) was calculated. Homocysteine and folate concentrations during treatment with IFN-alpha did not differ from baseline. In contrast, significant increases in neopterin formation and tryptophan degradation were apparent during IFN-alpha therapy. Plasma concentrations of vitamin B(12) and cysteine also increased. These results indicate that IFN-alpha directly activates macrophages to release neopterin and to degrade tryptophan, but obviously treatment with INF-alpha did not affect homocysteine metabolism.

Adult↗
PubMed2004

Alveolar granulocyte colony-stimulating factor and alpha-chemokines in relation to serum levels, pulmonary neutrophilia, and severity of lung injury in ARDS.

OBJECTIVES: To determine granulocyte colony-stimulating factor (G-CSF), epithelial neutrophil-activating peptide (ENA)-78, and interleukin (IL)-8 in BAL fluid (BALF), epithelial lining fluid (ELF), and serum for establishing the concentration gradient of G-CSF, ENA-78, and IL-8 between the blood and the alveolar space in ARDS and acute lung injury (ALI); and to evaluate the relationship of G-CSF, IL-8, and ENA-78 to pulmonary neutrophilia and severity of lung injury. DESIGN: Prospective study. SETTING: An adult trauma/surgical ICU. PATIENTS: Nineteen patients with ARDS and 10 patients with ALI. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: BAL and blood sampling simultaneously within 12 h and 24 h after onset of ARDS/ALI; G-CSF was detected in BALF in 18 of 19 patients with ARDS, in 7 of 10 patients with ALI, and in all serum samples. G-CSF in BALF and serum was significantly higher in ARDS than in ALI. ENA-78 was detected in BALF in 14 of 19 patients with ARDS, in 8 of 10 patients with ALI, and in serum of all patients. Levels in BALF and serum were not different between ARDS and ALI. IL-8 was detected in all patients; concentrations in BALF in ARDS were significantly higher than in ALI. Concentrations of G-CSF, ENA-78, and IL-8 in ELF were significantly higher than in serum. G-CSF in BALF and serum and IL-8 in BALF correlated positively with pulmonary neutrophilia. G-CSF in serum and IL-8 in BALF correlated negatively with PaO(2)/fraction of inspired oxygen (FIO(2)) ratio. However, ENA-78 did not show a correlation with neutrophil count or with PaO(2)/FIO(2) ratio. CONCLUSIONS: G-CSF may be pathophysiologically important for accumulation and activation of neutrophils in ARDS. Local G-CSF production is the likely driving force for neutrophils rather than elevation of circulating levels. In comparison to ENA-78, IL-8 seems to be the predominant neutrophil chemoattractant in the early phase of ARDS.

Adult↗
PubMed2004

St. John's wort (Hypericum perforatum) counteracts cytokine-induced tryptophan catabolism in vitro.

St. John's wort (Hypericum perforatum) is an ancient folk remedy that has antiviral and antibacterial properties. Anti-inflammatory effects of the plant have been described and the application of H. perforatum extract as an effective antidepressant is well established. In this study we assayed the effect of H. perforatum extract on cytokine-induced tryptophan degradation in human peripheral blood mononuclear cells. Simultaneously, changes in the production of the immune activation marker neopterin were monitored. Both these biochemical pathways are triggered by interferon-gamma. Our results show that extracts of H. perforatum strongly down-regulate mitogen-mediated tryptophan degradation in a dose-dependent manner. This effect seems to be based on a suppressive activity of H. perforatum on activated immunocompetent cells, resulting in a diminished production of interferon-gamma. In line with this finding, neopterin synthesis was strongly down-regulated by the plant extract. Our results suggest that the reduction of tryptophan degradation by H. perforatum might be important in the action of the plant as an antidepressant.

Cell Survival↗
PubMed2003

Interferon-alpha-induced changes in tryptophan metabolism. relationship to depression and paroxetine treatment.

BACKGROUND: Tryptophan (TRP) degradation into kynurenine (KYN) by the enzyme, indoleamine-2,3-dioxygenase, during immune activation may contribute to development of depressive symptoms during interferon (IFN)-alpha therapy. METHODS: Twenty-six patients with malignant melanoma were randomly assigned in double-blind fashion to receive either placebo or paroxetine, beginning 2 weeks before IFN-alpha treatment and continuing for the first 12 weeks of IFN-alpha therapy. At treatment initiation and at 2, 4, and 12 weeks of IFN-alpha treatment, measurements of TRP, KYN, and neopterin (a marker of immune activation), were obtained, along with structured assessments of depression, anxiety, and neurotoxicity. RESULTS: Regardless of antidepressant treatment status, all patients exhibited significant increases in KYN, neopterin, and the KYN/TRP ratio during IFN-alpha therapy. Among antidepressant-free patients, patients who developed major depression exhibited significantly greater increases in KYN and neopterin concentrations and more prolonged decreases in TRP concentrations than did nondepressed, antidepressant-free patients. Moreover, in antidepressant-free patients, decreases in TRP correlated with depressive, anxious, and cognitive symptoms, but not neurovegetative or somatic symptoms. No correlations were found between clinical and biological variables in antidepressant-treated patients. CONCLUSIONS: The results suggest that reduced TRP availability plays a role in IFN-alpha-induced depressive symptoms, and paroxetine, although not altering the KYN or neopterin response to IFN-alpha, attenuates the behavioral consequences of IFN-alpha-mediated TRP depletion.

Adult↗
PubMed2003

Influence of neopterin on the generation of reactive oxygen species in human neutrophils.

Neopterin is synthesized by human monocyte-derived macrophages primarily upon stimulation with the cytokine interferon-gamma. We studied the influence of neopterin on the generation of reactive oxygen species (ROS) in human peripheral blood neutrophils. Radical formation was measured using a biochemiluminometer. Neutrophils were isolated from peripheral blood of healthy donors. The generation of ROS by neutrophils suspended in Earl's solution (pH=7.4) at 37 degrees C was investigated by monitoring of chemiluminescence using luminol and lucigenin as light emitters. Neopterin induced chemiluminescence in suspensions of neutrophils in the presence of luminol, but not of lucigenin. Neopterin affected only adhesive cells. Addition of neopterin into the suspension of the cells involving D-mannitol, L-histidine and diazabicyclo[2.2.2]octane (DABCO) decreased luminol-dependent chemiluminescence (LDCL) of the neutrophils. The action of superoxide dismutase (SOD) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) reduced neopterin-induced LDCL of neutrophils. Data suggest that neutrophils respond on exposure to neopterin with additional generation of singlet oxygen, hydroxyl radical and nitric oxide by nicotinamide adenine dinucleotide phosphate (NADPH)-independent pathways.

Cyclic N-Oxides↗
PubMed2003

Interaction of sertraline with Candida species selectively attenuates fungal virulence in vitro.

This study investigated whether the interaction between isolates of Candida albicans (n=7), Candida parapsilosis (n=3), Candida krusei (n=2), Candida dubliniensis (n=1) and sertraline, a typical selective serotonin reuptake inhibitor, alters candidal virulence. Sertraline treatment of Candida spp. significantly (P<0.05) affected hyphal elongation, phospholipase activity, production of secreted aspartyl proteinases and fungal viability. In addition, monocyte-derived macrophages (MDMs) treated with sertraline reduced inhibition of blastoconidia germination in comparison to MDMs alone. In conclusion, our findings suggest that the interaction between sertraline and Candida spp. may also diminish the virulence properties of this fungal pathogen in vivo.

Aspartic Acid Endopeptidases↗
PubMed2003

Longitudinal study of tryptophan degradation during and after pregnancy.

In mice, activation of indoleamine-2,3-dioxygenase (IDO), an enzyme converting tryptophan to N-formyl-kynurenine, was found to be necessary requirement to achieve immunotolerance against the fetus and thus uncomplicated pregnancy. In plasma from 20 healthy pregnant women with singleton pregnancies we consecutively analyzed kynurenine and tryptophan concentrations during pregnancy (1 specimen at each trimester of gestation) and postpartum (week 6). None of the women had any signs of infection at the time of plasma sampling, but the study population was otherwise unselected. The kynurenine to tryptophan ratio (kyn/trp) was calculated as an estimate of IDO activity, and data were compared to concentrations of neopterin and 55kD soluble tumor necrosis factor receptor (sTNF-R55), two indicators of immune activation, and to alanineaminotransferase (ALT) levels. Increasing kynurenine and decreasing tryptophan concentrations were found during pregnancy, data suggesting significant degradation of tryptophan. In parallel, increasing concentrations of immune activation markers neopterin and sTNF-R55 were observed, correlating significantly to kyn/trp. The data point to an involvement of cytokine-induced IDO activation in the degradation of tryptophan observed during pregnancy. After pregnancy, sTNF-R55 and also neopterin concentrations declined, whereas tryptophan concentrations increased, indicating that immune activation and activation-induced tryptophan degradation returned to baseline. By contrast, still increased kynurenine concentrations and also increased kyn/trp point to continuing catabolism of tryptophan. Postpartum elevation of liver enzyme ALT may suggest that increased activity of hepatic tryptophan pyrrolase could be involved in increased conversion of tryptophan despite low degree of immune activation. We conclude that IDO is activated in pregnancy and that the decrease of tryptophan might be related to immune activation phenomena. Sustained increase of kynurenine postpartum seems independent from immune activation process.

Adult↗
PubMed2003

Prognostic value of tryptophan load test followed by serum kynurenine determination. Its comparison with pyridoxal-5-phosphate, kynurenine, homocysteine and neopterin amounts.

Tryptophan load test followed by serum kynurenine determination at fasting state and after L-tryptophan loading, as well as serum pyridoxal-5-phosphate (P-5-P), homocysteine and neopterin concentrations at fasting state have been examined in 30 healthy individuals and 87 patients with coronary heart disease (CHD), verified by coronary angiography. Received results have shown that low serum P-5-P concentration as well as P-5-P deficiency identified by tryptophan load test have been found in 78% of CHD patients, while increased homocysteine concentration above 15 micromol/L in 31.8%, and elevated neopterin concentration above 8.7 nmol/L in 32.1% of cases. It allows to conclude that a lot of CHD patients have P-5-P deficiency. Moreover P-5-P deficiency is an earlier indicator of CHD than increased homocysteine level above 15 micromol/L. Elevated serum neopterin concentration above 8.7 nmol/L may be a marker of coronary disease activity rather than a marker of the presence of CHD.

Biomarkers↗
PubMed2003

Effective antiretroviral therapy reduces degradation of tryptophan in patients with HIV-1 infection.

Activation of indoleamine-(2,3)-dioxygenase (IDO), an enzyme converting tryptophan to N-formyl-kynurenine, was found to be critical for induction of T-cell tolerance. In 45 HIV-seropositive patients we measured plasma tryptophan and kynurenine before and 6 months post-initiation of ART. Before ART, patients had decreased tryptophan and increased kynurenine levels compared to controls. During ART, average tryptophan concentrations increased, kynurenine decreased. Tryptophan degradation correlated with neopterin levels and with viral load but not with CD4 cell counts. The data support the concept that immune activation is the common background of IDO activation and could represent an important factor underlying T-cell hyporesponsiveness in HIV infection.

Adult↗