Showing papers by "Marcello Pinti published in 2010"

Interfering with ROS Metabolism in Cancer Cells: The Potential Role of Quercetin

Abstract: A main feature of cancer cells, when compared to normal ones, is a persistent pro-oxidative state that leads to an intrinsic oxidative stress. Cancer cells have higher levels of reactive oxygen species (ROS) than normal cells, and ROS are, in turn, responsible for the maintenance of the cancer phenotype. Persistent ROS stress may induce adaptive stress responses, enabling cancer cells to survive with high levels of ROS and maintain cellular viability. However, excessive ROS levels render cancer cells highly susceptible to quercetin, one of the main dietary flavonoids. Quercetin depletes intracellular glutathione and increases intracellular ROS to a level that can cause cell death.

Viral strategies for the evasion of immunogenic cell death.

Abstract: Viral strategies for the evasion of immunogenic cell death (Symposium). J Intern Med 2010; 267: 526-542. Driven by co-evolutionary forces, viruses have refined a wide arsenal of strategies to interfere with the host defences. On one hand, viruses can block/retard programmed cell death in infected cells, thereby suppressing one of the most ancient mechanisms against viral dissemination. On the other hand, multiple viral factors can efficiently trigger the death of infected cells and uninfected cells from the immune system, which favours viral spreading and prevents/limits an active antiviral response, respectively. Moreover, several viruses are able to inhibit the molecular machinery that drives the translocation of calreticulin to the surface of dying cells. Thereby, viruses block the exposure of an engulfment signal that is required for the efficient uptake of dying cells by dendritic cells and for the induction of the immune response. In this review, we discuss a variety of mechanisms by which viruses interfere with the cell death machinery and, in particular, by which they subvert immunogenic cell death.

Cytotoxic granule release dominates gag-specific CD4+ T-cell response in different phases of HIV infection.

Abstract: Background The activity of virus-specific T lymphocytes, among which those capable of a polyfunctional response against the viral protein gag, is crucial to control HIV infection. Objective The objective of this study is to investigate the polyfunctionality of gag-specific T cells in different phases of HIV infection, analyzing markers related to T-helper cell 1 (Th1) and degranulation/cytotoxicity, and the production of Th1 cytokines in peripheral blood lymphocytes from patients experiencing an acute primary infection, long-term nonprogressors, patients naive for antiretroviral drugs, and patients taking HAART. Materials and methods Cells were stimulated with a pool of gag-derived peptides or with a superantigen (staphylococcal enterotoxin B). Using eight-color polychromatic flow cytometry, we analyzed the expression of interleukin-2, interferon-gamma, CD154, and CD107a by CD4 and CD8 T cells. Results The main finding was that in all HIV-positive patients, about half gag-specific CD4 T cells were CD107a, that is, able to degranulate. CD4CD154 cells unable to produce Th1 cytokines were the second most represented population. Truly polyfunctional CD4 T cells were very rare and present only in a few long-term nonprogressors. Superantigen stimulation showed that CD4 T lymphocytes from all patients displayed a typical Th response, including interleukin-2 and interferon-gamma production, lacking CD107a expression. Conclusion In all the aforementioned phases of HIV infection, the large majority of gag-specific CD4 T lymphocytes cannot be identified by the sole expression of interleukin-2 and interferon-gamma, which is early impaired. Degranulation and helper functions other than Th1 cytokine production are the predominant features of HIV-specific CD4 lymphocytes.

Upregulation of nuclear-encoded mitochondrial LON protease in HAART-treated HIV-positive patients with lipodystrophy: implications for the pathogenesis of the disease.

Abstract: Background: HAART can provoke metabolic changes and body fat redistribution, resulting in lipodystrophy, a side effect significantly involving mitochondrial function. Mitochondrial DNA (mtDNA) depletion caused by nucleosidic reverse transcription inhibitors is supposed to be a crucial mechanism in the pathogenesis of mitochondrial damages.Methods: In adipose tissue from 22 HIV-positive patients with lipodystrophy and 20 healthy controls, we analyzed gene expression by microarray analysis and real-time PCR. The most upregulated gene was further studied in the human adipocytic cell line SW872 by real-time PCR, western blot, transient transfection assays and flow cytometry.Results: We identified 18 genes differently expressed between lipodystrophy patients and controls, and focused our attention on the nuclear-encoded mitochondrial protease LON, essential in mtDNA maintenance. In SW872 cells, treatment with stavudine (d4T) doubled LON levels, in parallel with mtDNA depletion. As d4T increased reactive oxygen species (ROS) intracellular content, we measured LON in presence of deoxyribose, which causes oxidative stress but not mtDNA depletion, and observed LON upregulation. Ethidium bromide, which markedly depletes mtDNA, did not alter LON levels. The antioxidant glutathione inhibited the increase of intracellular ROS and the increase in LON caused by d4T or deoxyribose.Conclusion: LON upregulation was due to d4T-induced ROS production, rather than due to mtDNA depletion, and represents a response to an oxidative stress. Other mechanisms than mtDNA depletion thus exist that explain nucleosidic reverse transcription inhibitors toxicity. This observation provides a rationale for possible therapeutic interventions aimed at reducing intracellular ROS content in patients assuming HAART. (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins

Mitochondrial changes during D-drug-containing once-daily therapy in HIV-positive treatment-naive patients.

Abstract: BackgroundAntiviral drugs of the category of nucleoside reverse transcriptase inhibitors (NRTIs), largely used for the treatment of HIV infection, can have toxic effects on mitochondria. We perform...

T cell homeostasis in centenarians: from the thymus to the periphery.

Abstract: The immune system undergoes a process of profound remodelling during aging, referred to as immunosenescence, and characterized by complex modifications of several components. In this review, we discuss recent developments and observations regarding the generation of T cells in the thymus during aging and longevity, and the regulation and maintenance of peripheral blood lymphocytes. The generation of new T cells is indeed crucial to maintain a functional immune system, and is a fundamental step to avoid unsuccessful aging, thus reaching longevity in good health. Mechanisms will be described that are related to the production and maintenance of those lymphocytes defined "recent thymic emigrants", and to the detection of the so called "T cell receptor rearrangement excision circles (TREC)", along with the presence in the periphery of naive and memory T cells, that can be influenced and regulated by several different mechanisms. Several strategies aimed at improving thymic functionality are currently receiving a growing interest, and some of them are based on molecules that are produced by, and/or act on immune cells. Data on the possible use of these molecules, including cytokines like interleukin (IL)-7, IL-15 and keratinocyte growth factor, to restore thymic function are reviewed and discussed.

Predictive value of intracellular HIV-1 DNA levels during CD4-guided treatment interruption in HIV+ patients.

Abstract: The amount of HIV-1 DNA within peripheral blood mononuclear cells is an important marker of viral activity. We studied intracellular HIV-1 DNA content in purified CD4+ T cells from 28 chronically HIV-1–infected adults with sustained CD4+ T cell counts (>500 cells/μl) and undetectable plasma viral load (<50 copies/ml), who underwent CD4-guided treatment interruption (TI). Patients were followed up for 18 months during TI, and for 6 months after treatment resumption (TR). Six naive HIV+ patients starting therapy were also enrolled and followed up for 6 months. All patients were studied every 2 months; HIV-1 DNA copy number was quantified with real-time PCR. Considering all patients remaining off-treatment, in the first 18 months of TI, intracellular HIV-1 DNA levels (expressed as Log10 copies/million cells) remained stable (mean, 3.82 and 3.77 at time 0 and after 18 months, respectively). Similarly, HIV-1 DNA values, either in patients who restarted treatment after TI (time 0, 4.90) or in naive pat...

Changes in CD4+ cells’ miRNA expression following exposure to HIV-1

Abstract: Background: Micro RNAs (miRNAs) inhibit HIV-1 expression by either modulating host innate immunity or by directly interfering with viral mRNAs. Here, we investigated the miRNA profile that discriminates different classes of HIV-1-infected patients from multiple-exposed uninfected individuals. Methods: The expression levels of 377 miRNAs were selectively analysed in CD4+ cells isolated from whole blood of HIV-1 elite LTNP (eLTNP), naive, and multiply exposed uninfected individuals (MEUs). MiRNA extraction was performed by the mir Vana™ miRNA Isolation Kit (Ambion), and their expression was subsequently examined by real-time PCR-based arrays. The expression of miRNAs was also determined in primary culture of CD4+ T cells and monocyte-macrophages infected in vitro by R5 strains. Expression of Dicer and Drosha was evaluated by real-time PCR. Results: We only considered miRNAs that were expressed in the 70% of patients of at least one class and varied by at least one log10 from healthy controls. Out of 377 miRNAs, 26 were up-regulated, while 88 were down-regulated. Statistical analysis showed that 21 miRNAs significantly differentiated eLTNP from MEU and 23 miRNAs distinguished naive from MEU, while only one (miR-155) discriminated eLTNP from naive. By hierarchical clustering of the miRNAs according to patient class, eLTNP clustered with naive, whereas all MEU subjects grouped together. The Dicer and Drosha expression in the patient classes correlated with miRNA profile changes. Among miRNAs differentially expressed in patient classes, 32 were detected in the in vitro infection model: most of the up-regulated miRNAs were expressed in monocyte-macrophages, whereas most of the down-regulated miRNAs were expressed in T lymphocytes. Conclusions: These findings support the consideration that the miRNA profile could be the result not only of a productive infection, but also of the exposure to HIV products that leave a signature in immune cells. These data provide some intriguing issues relative to the development of HIV vaccines targeting viral proteins. Supplement: Workshop Report and Abstracts “Towards a Cure”: HIV Reservoirs and Strategies to Control Them Shirin Heidari, Marie-Capucine Penicaud, Celine Cheng, International AIDS Society http://www.biomedcentral.com/content/pdf/1758-2652-13-S3-info.pdf Conference: International AIDS Society’s Workshop “Towards a Cure”: HIV Reservoirs and Strategies to Control Them 16–17 July 2010 Vienna, Austria (Published: 4 November 2010) doi:10.1186/1758-2652-13-S3-O11 Cite this article as: Bignami et al.: Changes in CD4+ cells’ miRNA expression following exposure to HIV-1. Journal of the International AIDS Society 2010 13(Suppl 3):O11. Full text: PubMed Central: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2999381/