Harald Schennach

Tyrol Prostate Cancer Demonstration Project: early detection, treatment, outcome, incidence and mortality

To evaluate the effectiveness of a well‐controlled programme of early detection and treatment of prostate cancer in the population of Tyrol, Austria, where such a programme of early detection and treatment was initiated in 1988 and where prostate‐specific antigen (PSA) testing was offered for free to all men aged 45–75u2003years from 1993.

Monocyte-derived dendritic cells release neopterin

Increased neopterin concentrations in body fluids are found in diseases associated with activated, cell‐mediated immunity including infections, autoimmune diseases, and certain malignancies. Monocytes/macrophages are known to secrete large amounts of neopterin upon stimulation with interferon‐γ (IFN‐γ). Ontogenetically, the major part of dendritic cells (DC) belongs to the myeloid lineage. Therefore, we investigated whether cultured monocyte‐derived DC can elaborate neopterin. Cells were treated with cytokines in the presence or absence of monocyte‐conditioned medium as a maturation stimulus. DC secreted an average 3.5 nmol/l neopterin. In response to IFN‐γ, cells significantly increased their output of neopterin. In distinction to monocytes/macrophages, neopterin production in DC was highly sensitive to IFN‐α and IFN‐β. Further, lipopolysaccharides (LPS) enhanced neopterin synthesis, whereas tumor necrosis factor α, interleukin (IL)‐1β, IL‐2, IL‐10, and IL‐18 were ineffective. Simultaneously, tryptophan degradation by induction of indoleamine (2,3)‐dioxygenase (IDO) was tested in stimulated cells. Our results showed that IFN‐γ as well as LPS are inducers of IDO in DC.

Atorvastatin suppresses interferon-γ-induced neopterin formation and tryptophan degradation in human peripheral blood mononuclear cells and in monocytic cell lines

Inhibitors of 3‐hydroxy‐3methylglutaryl‐co‐enzyme A (HMG‐CoA) reductase, so‐called statins, are used in medical practice because of their lipid‐lowering effect and to reduce the risk of coronary heart disease. Recent findings indicate that statins also have anti‐inflammatory properties and can modulate the immune response. In vitro, we investigated the effect of atorvastatin on the T cell/macrophage system in peripheral blood mononuclear cells (PBMC) and in the human monocytic cell lines THP‐1 and MonoMac6. We monitored neopterin production and tryptophan degradation in PBMC after treatment with 10u2003µm and 100u2003µm atorvastatin in the presence or absence of 100u2003U/ml IFN‐γ, 10u2003µg/ml phytohaemagglutinin (PHA) or 10u2003µg/ml concanavalin A (ConA) and in monocytic cell lines THP‐1 and MonoMac6 with or without stimulation with 100u2003U/ml IFN‐γ or 10u2003ng/ml to 1u2003µg/ml lipopolysaccharide (LPS). In stimulated PBMC 100u2003µm atorvastatin inhibited neopterin formation and tryptophan degradation completely, whereas 10u2003µm atorvastatin was only partially effective. Also in monocytic cell lines THP‐1 and MonoMac6, atorvastatin was able to suppress IFN‐γ‐ and LPS‐induced formation of neopterin and degradation of tryptophan. Our data from PBMC agree well with previous investigations that statins inhibit T cell activation within the cellular immune response. In addition we demonstrate that atorvastatin directly inhibits IFN‐γ‐mediated pathways in monocytic cells, suggesting that both immunoreactivity of T cells and of monocyte‐derived macrophages are down‐regulated by this statin.

Regulatory Interactions between Iron and Nitric Oxide Metabolism for Immune Defense against Plasmodium falciparum Infection

Iron chelation therapy of Plasmodium falciparum infection alleviates the clinical course of cerebral malaria in children. This study assessed the underlying mechanisms of this therapy. Cytokine stimulation of human (intestinal cell line DLD-1) or murine cells (murine macrophage cell line RAW 264.7) resulted in increased nitric oxide (NO) formation and decreased survival of plasmodia within cocultured human erythrocytes. The addition of desferrioxamine (DFO) before cytokine treatment increased both NO formation and parasite killing but had no effect in the presence of the inhibitor of NO formation, L-N6-(1-iminoethyl)-lysine. Moreover, peroxynitrite, which is formed after chemical reaction of NO with superoxide, appears to be the principal effector molecule for macrophage-mediated cytotoxicity toward P. falciparum, and interferon-gamma is a major regulatory cytokine for this process. The effect of DFO on the clearance of plasmodia appears to be due to enhanced generation of NO, rather than to limitation of iron availability to the parasite.

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.

Aqueous extracts of Crinum latifolium (L.) and Camellia sinensis show immunomodulatory properties in human peripheral blood mononuclear cells

In Vietnamese and Chinese traditional medicine, hot aqueous extract of Crinum latifolium is used because of its antitumor activity. The genus Crinum is thought to possess antiviral and immunostimulative properties. Green and black tea derived from Camellia sinensis have similar qualities. A growing body of evidence suggests that moderate consumption of green and black tea may protect, e.g., against several forms of cancer, cardiovascular diseases, and bacterial infections. In this study, the immunomodulatory property of C. latifolium (L.) extracts should further be investigated and compared to those of black and green tea. Human peripheral mononuclear cells were cultured in the presence of tea extracts with or without mitogens or interferon-gamma. The effect of plant extracts on cultured cells was assayed by neopterin production, a sensitive marker reflecting the activation of cell-mediated immunity. Our experiments showed that extracts of C. latifolium (L.) slightly enhance neopterin production in unstimulated peripheral mononuclear cells, whereas an effective reduction of neopterin formation in cells stimulated with concanavalin A (Con A), phytohemagglutinin (PHA), or interferon-gamma (IFN-gamma) was observed. Green and black tea extracts displayed similar immunomodulatory properties in our in vitro system, whereas C. latifolium (L.) extracts seemed to be more effective in reducing neopterin formation in stimulated cells.

In vitro testing for anti-inflammatory properties of compounds employing peripheral blood mononuclear cells freshly isolated from healthy donors.

IntroductionInflammation is crucially involved in a variety of diseases like autoimmune syndromes, cardiovascular and neurodegenerative disorders, cancer, sepsis and allograft rejection.MethodsFreshly isolated human peripheral blood mononuclear cells (PBMCs) are used as a screening assay for anti-inflammatory properties of compounds. Determinations of neopterin production by ELISA and of tryptophan degradation by HPLC are used as read-outs. Results are compared with further markers of immune response and oxidative stress.ResultsPhytohaemagglutinin induced significant tryptophan degradation and neopterin formation in PBMC, which correlated with IFN-γ, TNF-α, soluble cytokine receptors and isoprostane-8. Addition of vitamin C and E suppressed the responses dose-dependently.DiscussionThe determination of tryptophan degradation and neopterin production in PBMC reflects various pro- and anti-inflammatory cascades that are of relevance also in patients. It constitutes a robust and reliable approach to screen anti-inflammatory or immunosuppressive drugs and may improve throughput, speed and cost-effectiveness in drug discovery.

Moderate Hyperhomocysteinemia and Immune Activation

Moderate hyperhomocysteinemia is associated with an increased risk of atherosclerosis, thrombosis and neurodegenerative diseases. Homocysteine accumulation in the blood can be due to many underlying causes, which may interact with each other, e.g. genetic disposition and B-vitamin status. The role of the sulfur-containing amino acid homocysteine in the pathogenesis of diseases remains unclear, even if many studies suggest a causal relationship between homocysteine-mediated processes like oxidative stress, NO-inactivation and endothelial deficiency and atherogenesis. Proposed mechanisms of action of homocysteine are discussed, and the question is addressed, whether effects that are attributed to homocysteine, are not rather the consequence of folate and vitamin B12-deficiency. Deficiency of these B-vitamins in parallel with moderate hyperhomocysteinemia is often found in patients with enhanced activation of the cellular immune system, like Alzheimers disease, rheumatoid arthritis and also vascular diseases. In patients with these diseases an association between homocysteine metabolism, oxidative stress and immune activation exists. On the one hand proliferation of immunocompetent cells having an enhanced demand for B-vitamins leads to the accumulation of homocysteine. On the other hand macrophages stimulated by TH1-type cytokine interferon-gamma form reactive oxygen species (ROS), which oxidize antioxidants, lipoproteins and oxidation-sensitive B-vitamins. Thereby Th1-type immune response could contribute importantly to the development of hyperhomocysteinemia, and may also be a major determinant of disease progression.

Cross-Linking of CD32 Induces Maturation of Human Monocyte-Derived Dendritic Cells Via NF-κB Signaling Pathway

Dendritic cells (DC) represent a unique set of APCs that initiate immune responses through priming of naive T cells. Maturation of DC is a crucial step during Ag presentation and can be induced by triggering a broad spectrum of DC surface receptors. Although human DC express several receptors for the Fc portion of IgG which were described to play an important role in Ag internalization, little is known about the effects of IgG or immune complexes on DC maturation. In this study, we show that cross-linking of FcγR-type II (CD32) with immobilized IgG (imIgG) can induce maturation of human monocyte-derived DC via the NF-κB signaling pathway. IgG-mediated maturation was accompanied by a moderate increase of IL-10 secretion, whereas no IL-12 production was observed. Involvement of CD32 was further supported by experiments with the anti-CD32 mAb, which blocked IgG-triggered DC maturation and cytokine secretion significantly. Furthermore, DC cultivated in the presence of imIgG induced allogeneic T cell proliferation. Because this imIgG-induced maturation was considerably impaired in monocyte-derived DC from systemic lupus erythematosus patients, we suggest that DC, which matured in the presence of immune complexes, may contribute to prevention of pathological immune responses.

Food preservatives sodium benzoate and propionic acid and colorant curcumin suppress Th1-type immune response in vitro

Food preservatives sodium benzoate and propionic acid and colorant curcumin are demonstrated to suppress in a dose-dependent manner Th1-type immune response in human peripheral blood mononuclear cells (PBMC) in vitro. Results show an anti-inflammatory property of compounds which however could shift the Th1-Th2-type immune balance towards Th2-type immunity.