Marcel Jenny

The Role of Neopterin in Atherogenesis and Cardiovascular Risk Assessment

Neopterin is produced by human and primate monocyte/macrophages upon activation by pro-inflammatory stimuli like Th1-type cytokine interferon-gamma. Neopterin has pro-oxidative properties, which have been demonstrated in vitro in physicochemical and cell culture studies and also in in vivo experiments, e.g. the Langendorff perfusion model of rat hearts. In the past several years, the measurement of neopterin concentrations in body fluids including serum, urine and cerebrospinal fluid has revealed a potential role of this molecule in the prediction of long-term prognosis in both patients with cancer and those with systemic infections such as HIV-1 infection. Moreover, elevated neopterin concentrations have been reported in patients with coronary disease compared to controls and in recent years it has become apparent that increased neopterin concentrations are an independent marker for cardiovascular disease and a predictor of future cardiovascular events in patients with coronary artery disease. Current data suggest that the diagnostic performance of neopterin testing is comparable to that of well established biomarkers such as C-reactive protein and cholesterol plasma levels. The present article reviews the role of neopterin in the pathogenesis of cardiovascular disease and as a marker of coronary artery disease progression.

2-benzoxazolyl and 2-benzimidazolyl hydrazones derived from 2-acetylpyridine: A novel class of antitumor agents

Here we describe the effects of novel benzoxazol‐2‐yl and benzimidazol‐2‐yl hydrazones derived from 2‐pyridinecarbaldehyde and 2‐acetylpyridine. The IC50 values for inhibition of cell proliferation in KB‐3‐1, CCRF‐CEM, Burkitts lymphoma, HT‐29, HeLa, ZR‐75 and MEXF276L by most of the novel compounds are in the nanomolar range. In colony‐forming assays with human tumor xenografts the compounds 2‐actylpyridine benzoxazol‐2‐ylhydrazone (EPH52), 2‐acetylpyridine benzoimidazol‐2‐ylhydrazone (EPH61) and 2‐acetylpyridine 1‐methylbenzoimidazol‐2‐ylhydrazone (EPH116) exhibited above‐average inhibition of colon carcinoma (IC50 = 1.3–4.56 nM); EPH52 and EPH116 also exhibited above‐average inhibition of melanoma cells. As shown with human liver microsomes, EPH116 is only moderately metabolized. The compound inhibited the growth of human colon cancer xenografts in nude mice in a dose‐dependent manner. Thiosemicarbazones derived from 2‐formylpyridines have been shown to be inhibitors of ribonucleotide reductase (RR). The following results show that RR is not the target of the novel compounds: cells overexpressing the M2 subunit of RR and resistant to the RR inhibitor hydroxyurea are not cross‐resistant to the novel compounds; inhibition of RR occurs at 6‐ to 73‐fold higher drug concentrations than that of inhibition of cell proliferation; the pattern of cell cycle arrest in S phase induced by the RR inhibitor hydroxyurea is not observed after treatment with the novel compounds; and a COMPARE analysis with the related compounds 2‐acetylpyrazine benzothiazol‐2‐ylhydrazone (EPH95) and 3‐acetylisoquinoline benzoxazol‐2‐ylhydrazone (EPH136) showed that the pattern of these compounds is not related to any of the standard antitumor drugs. Therefore, these novel compounds show inhibition of colon cancers and exhibit a novel mechanism of action.

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.

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.

AKT1/PKBα is recruited to lipid rafts and activated downstream of PKC isotypes in CD3-induced T cell signaling

Protein kinase (PK) Cθ and Akt/PKBα cooperate in T cell receptor/CD28‐induced T cell signaling. We here demonstrate the recruitment of endogenous Akt1 and PKCθ to lipid rafts in CD3‐stimulated T cells. Further we show that Myr‐PKCθ mediates translocation of endogenous Akt1 to the plasma membrane as well as to lipid rafts, most likely explained by the observed complex formation of both protein kinases. In addition, in peripheral mouse T cells, the PKC inhibitor Gö6850 could partially block Akt1 activation in CD3‐induced signaling, placing PKC isotype(s) upstream of Akt1. However, T cells derived from PKCθ knockout mice were not impaired in CD3‐ or phorbol ester‐induced Akt1 activity. Taken together, the results of this study give new insights into the functional link of Akt1 and PKCθ in T cell signaling, demonstrating the co‐recruitment of the two kinases and showing a novel pathway leading to Akt1 transactivation where PKC isotype(s) are involved but PKCθ is not essential.

Food additives such as sodium sulphite, sodium benzoate and curcumin inhibit leptin release in lipopolysaccharide-treated murine adipocytes in vitro

Obesity leads to the activation of pro-inflammatory pathways, resulting in a state of low-grade inflammation. Recently, several studies have shown that the exposure to lipopolysaccharide (LPS) could initiate and maintain a chronic state of low-grade inflammation in obese people. As the daily intake of food additives has increased substantially, the aim of the present study was to investigate a potential influence of food additives on the release of leptin, IL-6 and nitrite in the presence of LPS in murine adipocytes. Leptin, IL-6 and nitrite concentrations were analysed in the supernatants of murine 3T3-L1 adipocytes after co-incubation with LPS and the food preservatives, sodium sulphite (SS), sodium benzoate (SB) and the spice and colourant, curcumin, for 24 h. In addition, the kinetics of leptin secretion was analysed. A significant and dose-dependent decrease in leptin was observed after incubating the cells with SB and curcumin for 12 and 24 h, whereas SS decreased leptin concentrations after 24 h of treatment. Moreover, SS increased, while curcumin decreased LPS-stimulated secretion of IL-6, whereas SB had no such effect. None of the compounds that were investigated influenced nitrite production. The food additives SS, SB and curcumin affect the leptin release after co-incubation with LPS from cultured adipocytes in a dose- and time-dependent manner. Decreased leptin release during the consumption of nutrition-derived food additives could decrease the amount of circulating leptin to which the central nervous system is exposed and may therefore contribute to an obesogenic environment.

Activation of PKCzeta and PKMzeta in the Nucleus Accumbens Core Is Necessary for the Retrieval, Consolidation and Reconsolidation of Drug Memory

One of the greatest challenges in the treatment of substance dependence is to reverse the control that drug-associated stimuli have gained over the addicts behavior, as these drug-associated memories increase the risk of relapse even after long periods of abstinence. We report here that inhibition of the atypical protein kinase C isoform PKCzeta and its constitutively active isoform PKMzeta with the pseudosubstrate inhibitor ZIP administered locally into the nucleus accumbens core reversibly inhibited the retrieval of drug-associated memory and drug (remifentanil) seeking, whereas a scrambled ZIP peptide or staurosporine, an effective inhibitor of c/nPKC-, CaMKII-, and PKA kinases that does not affect PKCzeta/PKMzeta activity, was without effect on these memory processes. Acquisition or extinction of drug-associated memory remained unaffected by PKCzeta- and PKMzeta inhibition.

LPS-induced NF-κB expression in THP-1Blue cells correlates with neopterin production and activity of indoleamine 2,3-dioxygenase

Neopterin production is induced in human monocyte-derived macrophages and dendritic cells upon stimulation with Th1-type cytokine interferon-gamma (IFN-gamma). In parallel, IFN-gamma induces the tryptophan-(trp)-degrading enzyme indoleamine 2,3-dioxygenase (IDO) and triggers the formation of reactive oxygen species (ROS). Translocation of the signal transduction element nuclear factor-kappaB (NF-kappaB) is induced by ROS and accelerates the pro-inflammatory response by activation of other pro-inflammatory pathways. Therefore, a close relationship between NF-kappaB expression, the production of neopterin and the degradation of trp can be assumed, although this has not been demonstrated so far. In the present in vitro study we compared the influence of lipopolysaccharide (LPS) on NF-kappaB activation, neopterin formation and the degradation of trp in THP-1Blue cells, which represent the human myelomonocytic cell line THP-1 stably transfected with an NF-kappaB inducible reporter system. In cells stimulated with LPS, a significant induction of NF-kappaB was observed, and this was paralleled by an increase of kynureunine (kyn) and neopterin concentrations and a decline of trp. The increase of the kyn to trp quotient indicates accelerated IDO activity. Higher LPS concentrations and longer incubation of cells were associated with higher activities of all three biochemical pathways and significant correlations existed between NF-kappaB activation, neopterin release and trp degradation (all p<0.001). We conclude that there is a parallel induction of NF-kappaB, neopterin formation and trp degradation in monocytic THP-1 cells, which is elicited by pro-inflammatory triggers like LPS during innate immune responses.

Δ9-Tetrahydrocannabinol and cannabidiol modulate mitogen-induced tryptophan degradation and neopterin formation in peripheral blood mononuclear cells in vitro

Nanomolar concentrations of Delta9-tetrahydrocannabinol or cannabidiol are demonstrated to enhance mitogen-induced degradation of tryptophan in human peripheral blood mononuclear cells in dependence of CB1- or CB2-receptor activation. In contrast, suppression of this pathway by cannabinoids in the micromolar concentration range was achieved independent of cannabinoid receptor activation. Both cannabinoids also suppressed tryptophan degradation in myelomonocytic THP-1 cells stimulated with lipopolysaccharide. We conclude, that suppression of tryptophan degradation by cannabinoids via indoleamine-2,3-dioxygenase, which is independent of cannabinoid receptor activation, might enhance the availability of tryptophan for serotonin biosynthesis and consequently can be important in the action of cannabinoids to improve mood disturbances.

Atypical Protein Kinase C ζ Exhibits a Proapoptotic Function in Ovarian Cancer

Intracellular signaling governed by serine/threonine kinases comprises the molecular interface between cell surface receptors and the nuclear transcriptional machinery. The protein kinase C (PKC) family members are involved in the control of many signaling processes directing cell proliferation, motility, and survival. Here, we examined a role of different PKC isoenzymes in protein phosphatase 2A (PP2A) and HRSL3 tumor suppressor–dependent cell death induction in the ovarian carcinoma cell line OVCAR-3. Phosphorylation and activity of PKC isoenzymes were measured in response to PP2A or phosphoinositide 3-kinase inhibition or HRSL3 overexpression. These experiments indicated a regulation of PKCθ, ϵ, ζ, and ι through PP2A and/or HRSL3, but not of PKCα and β. Using isoform-specific peptide inhibitors and overexpression approaches, we verified a contribution to PP2A- and HRLS3-dependent apoptosis only for PKCζ, suggesting a proapoptotic function of this kinase. We observed a significant proportion of human ovarian carcinomas expressing high levels of PKCζ, which correlated with poor prognosis. Primary ovarian carcinoma cells isolated from patients also responded to okadaic acid treatment with increased phosphorylation of PKCζ and apoptosis induction. Thus, our data indicate a contribution of PKCζ in survival control in ovarian carcinoma cells and suggest that upregulation or activation of tyrosine kinase receptors in this tumor might impinge onto apoptosis control through the negative regulation of the atypical PKCζ. Mol Cancer Res; 8(6); 919–34. ©2010 AACR.