Search results for "Arginase"

Arginase induction represses gall development during clubroot infection in Arabidopsis.

2012

Arginase induction can play a defensive role through the reduction of arginine availability for phytophageous insects. Arginase activity is also induced during gall growth caused by Plasmodiophora brassicae infection in roots of Arabidopsis thaliana; however, its possible role in this context has been unclear. We report here that the mutation of the arginase-encoding gene ARGAH2 abrogates clubroot-induced arginase activity and results in enhanced gall size in infected roots, suggesting that arginase plays a defensive role. Induction of arginase activity in infected roots was impaired in the jar1 mutant, highlighting a link between the arginase response to clubroot and jasmonate signaling. C…

The prognostic value of the myeloid-mediated immunosuppression marker Arginase-1 in classic Hodgkin lymphoma

2016

// Alessandra Romano 1 , Nunziatina Laura Parrinello 1 , Calogero Vetro 1 , Daniele Tibullo 1 , Cesarina Giallongo 1 , Piera La Cava 1 , Annalisa Chiarenza 1 , Giovanna Motta 1 , Anastasia L. Caruso 1 , Loredana Villari 2 , Claudio Tripodo 3 , Sebastiano Cosentino 4 , Massimo Ippolito 4 , Ugo Consoli 5 , Andrea Gallamini 6 , Stefano Pileri 7 , Francesco Di Raimondo 1 1 Division of Hematology, AOU “Policlinico - Vittorio Emanuele”, University of Catania, Catania, Italy 2 Division of Pathology, AOU “Policlinico - Vittorio Emanuele”, Catania, Italy 3 Tumor Immunology Unit, Department of Health Science, University of Palermo, Palermo, Italy 4 Nuclear Medicine Center, Azienda Ospedaliera Cannizz…

Human-based evidence for the therapeutic potential of arginase inhibitors in cardiovascular diseases

2020

Arginase is a ubiquitous enzyme that regulates polyamine- and nitric-oxide-requiring vascular functions. It is well-established that, in mammals, arginase overactivation contributes to endothelial dysfunction, a hallmark of cardiovascular diseases. The pharmacological potential of arginase inhibition for improving vascular function is largely supported by a wide range of data from animal studies. However, caution is required before extrapolating animal data to humans because interspecies differences in arginase expression and localization have been observed. For this reason, this review presents the existing arguments from human data in favor of a role of arginase in cardiovascular diseases…

2016

One of the key immunological characteristics of active visceral leishmaniasis (VL) is a profound immunosuppression and impaired production of Interferon-γ (IFN-γ). However, recent studies from Bihar in India showed using a whole blood assay, that whole blood cells have maintained the capacity to produce IFN-γ. Here we tested the hypothesis that a population of low-density granulocytes (LDG) might contribute to T cell responses hyporesponsiveness via the release of arginase. Our results show that this population is affected by the anticoagulant used to collect blood: the frequency of LDGs is significantly lower when the blood is collected with heparin as compared to EDTA; however, the antico…

Myeloid-Derived Suppressor Cells Specifically Suppress IFN-γ Production and Antitumor Cytotoxic Activity of Vδ2 T Cells.

2018

γδ T cells represent less than 5% of circulating T cells; they exert a potent cytotoxic function against tumor or infected cells and secrete cytokines like conventional αβ T cells. As αβ T cells γδ T cells reside in the typical T cell compartments (the lymph nodes and spleen), but are more widely distributed in tissues throughout the body. For these reasons, some investigators are exploring the possibility of immunotherapies aimed to expand and activate Vδ2 T cells, or using them as Chimeric Antigen Receptor carriers. However, the role of immunosuppressive microenvironment on Vδ2 T cells during infections and cancers has not been completely elucidated. In particular, the effects of myeloid-…

Phenotypic Alteration of Neutrophils in the Blood of HIV Seropositive Patients

2013

We have recently identified a novel population of activated low-density granulocytes (LDGs) in peripheral blood mononuclear cells of HIV seropositive patients. LDGs have a similar morphology to normal density granulocytes (NDGs), but are phenotypically different. Here we measured the expression levels of different phenotypic markers of granulocytes in the blood of HIV seropositive patients at different stages of HIV infection to determine whether the phenotype of NDGs and LDGs are affected by disease severity. Our results reveal that the phenotype of NDGs, but not that of LDGs, varies according to the severity of the disease.

Granulocyte functions are independent of arginine availability.

2014

Abstract Arginine depletion via myeloid cell arginase is critically involved in suppression of the adaptive immune system during cancer or chronic inflammation. On the other hand, arginine depletion is being developed as a novel anti-tumor metabolic strategy to deprive arginine-auxotrophic cancer cells of this amino acid. In human immune cells, arginase is mainly expressed constitutively in PMNs. We therefore purified human primary PMNs from healthy donors and analyzed PMN function as the main innate effector cell and arginase producer in the context of arginine deficiency. We demonstrate that human PMN viability, activation-induced IL-8 synthesis, chemotaxis, phagocytosis, generation of RO…

Cytotoxicity of tumor antigen specific human T cells is unimpaired by arginine depletion.

2013

Tumor-growth is often associated with the expansion of myeloid derived suppressor cells that lead to local or systemic arginine depletion via the enzyme arginase. It is generally assumed that this arginine deficiency induces a global shut-down of T cell activation with ensuing tumor immune escape. While the impact of arginine depletion on polyclonal T cell proliferation and cytokine secretion is well documented, its influence on chemotaxis, cytotoxicity and antigen specific activation of human T cells has not been demonstrated so far. We show here that chemotaxis and early calcium signaling of human T cells are unimpaired in the absence of arginine. We then analyzed CD8(+) T cell activation…

Characterization of a novel population of low-density granulocytes associated with disease severity in HIV-1 infection

2012

The mechanisms resulting in progressive immune dysfunction during the chronic phase of HIV infection are not fully understood. We have previously shown that arginase, an enzyme with potent immunosuppressive properties, is increased in HIV seropositive (HIV+) patients with low CD4(+) T cell counts. Here we show that the cells expressing arginase in peripheral blood mononuclear cells of HIV+ patients are low-density granulocytes (LDGs) and that whereas these cells have a similar morphology to normal-density granulocyte, they are phenotypically different. Importantly, our results reveal that increased frequencies of LDGs correlate with disease severity in HIV+ patients.

Gliadin-mediated production of polyamines by RAW264.7 macrophages modulates intestinal epithelial permeability in vitro

2015

AbstractCeliac disease (CD) is an immune-mediated enteropathy sustained by dietary gluten in susceptible individuals, and characterized by a complex interplay between adaptive and innate responses against gluten peptides (PTG). In a recent contribution we have demonstrated that the treatment with PTG induces the expression and activity of arginase in both murine macrophages and human monocytes from healthy subjects, thus suggesting a role for arginine and its metabolites in gluten-triggered response of these cells. Here we further explore this field, by addressing the effects of PTG on polyamine synthesis and release in murine RAW264.7 macrophages, and how they affect epithelial permeabilit…