Showing papers by "Walter Malorni published in 2004"

Extra Virgin Olive Oil Biophenols Inhibit Cell-Mediated Oxidation of LDL by Increasing the mRNA Transcription of Glutathione-Related Enzymes

Abstract: It has been reported that oxidized LDL (oxLDL) are involved in the pathogenesis of atherosclerosis, and that macrophages as well as other cells of the arterial wall can oxidize LDL in vitro, depending on the balance between intracellular prooxidant generation and antioxidant defense efficiency. Because of their possible beneficial role in the prevention of atherosclerosis and other oxidative stress-associated diseases, phenolic compounds naturally occurring in vegetables, fruits, and beverages are receiving increased attention. In the present work, we investigated the mechanisms underlying the protective effect exerted by extra virgin olive oil biophenols, namely, protocatechuic acid and oleuropein, on LDL oxidation mediated by murine J774 A.1 macrophage-like cells. The biophenols were added to the cells with LDL and left in the medium during the entire experimental period, or for a period of 2 h and then removed from the medium before the addition of LDL. The effect of biophenols alone was also tested. In both experimental procedures, these antioxidants had the following effects: 1). completely prevented the J774 A.1-mediated oxidation of LDL; 2). counteracted the time-dependent variations in intracellular redox balance, inhibiting the production of O(2)(.-) and H(2)O(2) and the decrease in glutathione (GSH) content; 3). restored glutathione reductase (GR) and peroxidase (GPx) activities; and 4). restored the mRNA expression of gamma-glutamylcisteine synthetase (gammaGCS), GR, and GPx to control values. More importantly, we observed significant overtranscription and increased activities of two antioxidative enzymes, GPx and GR, compared with controls when the biophenols were present in the medium for 2 h and then removed before LDL exposure, or when the cells were exposed to the antioxidants alone for up to 24 h. Our findings suggest that the activation of mRNA transcription of GSH-related enzymes represents an important mechanism in phenolic antioxidative action.

Cell surface overexpression of Galectin-3 and the presence of its ligand 90k in the blood plasma as determinants in colon neoplastic lesions

Abstract: Galectins are a family of beta-galactoside binding molecules involved in cell--extracellular matrix adhesion processes. Specifically, Galectin-3 (Gal-3), one of the members of this family of molecules plays a role in cell adhesion processes as well as in cell survival or apoptosis. Gal-3 was also hypothesized to represent a useful tool in tumor characterization, for example, in thyroid tumors. We report herein the results obtained by evaluating Gal-3 expression of colon cells from human adenomas and adenocarcinomas with two different methodologies: immunohistochemistry and flow cytometry of living dispersed cells. We found that (1) the expression of Gal-3 was significantly increased on the surface of cells from adenomas with respect to normal mucosa from the same patient; (2) Gal-3 ligand, 90k molecule, was increased in the blood plasma from patients with both adenomatous and adenocarcinomatous lesions; and (3) Gal-3 overexpression was not related with the presence of K-ras mutation. Altogether these results clearly indicate that the evaluation of Gal-3 expression (and of its ligand, 90k) can be of interest in the characterization of nonmalignant and malignant colon cancers.

CD95/phosphorylated ezrin association underlies HIV-1 GP120/IL-2-induced susceptibility to CD95(APO-1/Fas)-mediated apoptosis of human resting CD4(+)T lymphocytes.

Abstract: CD95(APO-1/Fas)-mediated apoptosis of bystander uninfected T cells exerts a major role in the HIV-1-mediated CD4+ T-cell depletion. HIV-1 gp120 has a key role in the induction of sensitivity of human lymphocytes to CD95-mediated apoptosis through its interaction with the CD4 receptor. Recently, we have shown the importance of CD95/ezrin/actin association in CD95-mediated apoptosis. In this study, we explored the hypothesis that the gp120-mediated CD4 engagement could be involved in the induction of susceptibility of primary human T lymphocytes to CD95-mediated apoptosis through ezrin phosphorylation and ezrin-to-CD95 association. Here, we show that gp120/IL-2 combined stimuli, as well as the direct CD4 triggering, on human primary CD4(+)T lymphocytes induced an early and stable ezrin activation through phosphorylation, consistent with the induction of ezrin/CD95 association and susceptibility to CD95-mediated apoptosis. Our results provide a new mechanism through which HIV-1-gp120 may predispose resting CD4(+)T cell to bystander CD95-mediated apoptosis and support the key role of ezrin/CD95 linkage in regulating susceptibility to CD95-mediated apoptosis.

Maternally-inherited Leigh syndrome-related mutations bolster mitochondrial-mediated apoptosis.

Abstract: The key role of mitochondria in the apoptotic process is well understood, but not many data are available regarding the specific role of mitochondrial DNA mutations in determining cell fate. We investigated whether two mitochondrial DNA mutations (L217R and L156R) associated with maternally-inherited Leigh syndrome may play a specific role in triggering the apoptotic cascade. Considering that different nuclear genetic factors may influence the expression of mtDNA mutations, we used a 143BTK– osteosarcoma cell line deprived from its own mtDNA in order to insert mutated mtDNAs. Analysis of mitochondrial features in these cybrids indicated that both mitochondrial DNA mutations produced evidence of biochemical, functional and ultrastructural modifications of mitochondria, and that these modifications were associated with an increased apoptotic proneness. Cybrids were highly susceptible to two different apoptotic stimuli, tumour necrosis factor-α and Staurosporin. The mechanism involved was the mitochondrial ‘intrinsic’ pathway, i.e. the caspase 9-driven cascade. More importantly, our results also indicated that the polarization state of the mitochondrial membrane, i.e. a constitutive hyperpolarization detected in cybrid clones, played a specific role. Interestingly, the different effects of the two mutations in terms of susceptibility to apoptosis probably reflect the deeper bioenergetic defect associated with the L217R mutation. This work provides the first evidence that hyperpolarization of mitochondria may be a ‘risk factor’ for cells with a deep ATPase dysfunction, such as cells from patients with maternally-inherited Leigh syndrome.

Programmed cell death: beyond the frontiers of science

Abstract: Programmed Cell Death (PCD) is an emerging topic contributing actively to basic biology, and in the near future, we could expect practical applications improving human health and the productivity of our crops. Current results relate this complex and paradoxical process with the physiological development, stress response and diseases of plants and animals. With the aim of improving the exchange as a starting point to future cooperation in the field of PCD, the International Cell Death Society (ICDS) and the European Cell Death Organization (ECDO) organized in Havana on February 24th the International Seminar Programmed Cell Death in Plants: a challenge to the new millennium, sponsored by the Tobacco Research Institute of Havana. To this historical meeting, the first co-organized by the two most important organizations on PCD, were invited recognized scientists from Italy, USA, France, Belgium, Switzerland, Czech Republic and Cuba. Although the seminar was organized to deal with the basic aspects of cell death in plants, speeches referred frequently to animal models. Session chairs, Mauro Piacentini and Zahra Zakeri, presidents of ECDO and ICDS, respectively, guided thirty minute speeches of ten speakers. The opening words of Vladimir Andino, head of the Tobacco Research Institute of Havana, and Mauro Piacentini, were followed by the speech of Richard A Lockshin from the Department of Biological Science of St. John’s University, USA. He dealt with the historical origins of PCD research [1]. According with his speech, cell death as a normal, physiological process was recognized in the 19 Century. One hundred years later, many of these deaths (in animals) were described as programmed, deriving from the recognition that, in embryonic development and metamorphosis, cells died at predictable times and places. Thus the assumption was that cell death was genetic in origin, and not a random loss of control. Later, Kerr, Wyllie, and Currie [2] called attention to a common morphology of many cell deaths and coined the term \"apoptosis\" in order to assert its importance in homeostasis as opposite and equal to mitosis (Figure 1). Shortly thereafter, a group of researchers ultimately led by Horvitz [3] proved the existence of genes that controlled all cell deaths in the embryo of the nematode Caenorhabditis elegans. Their research led rapidly to the identification of these genes. These included genes that could turn on or off the activation of death, genes that produced products that could kill cells, inhibitors of those products-activation of death often consisted of release from inhibition of death-and genes involved in the scavenging of the remnants of the dead cells. Two profound arguments developed from these discoveries: First, that all cells carried within them1. Lockshin RA, Zakeri Z. (2001) Programmed cell death and apoptosis: origins of the theory. Nat. Rev. Mol. Cell. Biol. 2 (7):545-50.