PubMed Health⌕ Search

Biomedical subjects

Adriano G Rossi

Publications and source records attributed to Adriano G Rossi.

32 records · Page 2Linked to original sources
PubMed2004

Golgi fragmentation during Fas-mediated apoptosis is associated with the rapid loss of GM130.

During apoptosis, the Golgi complex becomes fragmented and key proteins (e.g., GRASP65 and p115) are targets for caspase cleavage. GM130, an integral membrane protein, contributes to the maintenance of Golgi structure and facilitates membrane fusion with secretory vesicles. We show that GM130 levels decrease during Fas-induced apoptosis but not during staurosporine-induced apoptosis while in both models p115 levels remain unaffected. We conclude that GM130 is rapidly diminished during Fas-mediated apoptosis associated with Golgi fragmentation in contrast to previous studies which have suggested that loss of GM130 during apoptosis is a late event.

Apoptosis↗
PubMed2004

Interferon gamma suppresses glucocorticoid augmentation of macrophage clearance of apoptotic cells.

One of beneficial effects of glucocorticoids (GC) in inflammation may be the augmentation of macrophages' capacity for phagocytosis of apoptotic cells, a process that has a central role in resolution of inflammation. Here we define the phenotype of GC-treated monocyte-derived macrophages, comparing to IFN-gamma-treated and IL-4-treated monocyte-derived macrophages and combinatorial treatment. Our data indicate that the cytokine microenvironment at an inflammatory site will critically determine monocyte functional capacity following treatment with GC. In particular, whilst GC exert dominant regulatory effects over IFN-gamma in terms of cell surface receptor repertoire and morphology, the acquisition of a macrophage capacity for clearance of apoptotic cells is prevented by combined treatment. In terms of mechanism, GC augmentation of phagocytosis was reversed even when monocytes were pre-incubated with GC for the first 24 h of culture, a period that is critical for induction of a highly phagocytic macrophage phenotype. These findings have important implications for the effectiveness of GC in promoting acquisition of a pro-phagocytic macrophage phenotype in inflammatory diseases associated with high levels of IFN-gamma

Apoptosis↗
PubMed2003

Cigarette smoke prevents apoptosis through inhibition of caspase activation and induces necrosis.

Emphysema is characterized by enlargement of the distal airspaces in the lungs due to destruction of alveolar walls. Alveolar endothelial and epithelial cell apoptosis induced by cigarette smoke is thought to be a possible mechanism for this cell loss. In contrast, our studies show that cigarette smoke condensate (CSC) induces necrosis in alveolar epithelial cells and human umbilical vein endothelial cells. Furthermore, study of the cell death pathway in a model system using Jurkat cells revealed that in addition to inducing necrosis, CSC inhibited apoptosis induced by staurosporine or Fas ligation, with both effects prevented by the antioxidants glutathione and dithiothreitol. Time course experiments revealed that CSC inhibited an early step in the caspase cascade, whereby caspase-3 was not activated. Moreover, cell-free reconstitution of the apoptosome in cytoplasmic extracts from CSC-treated cells, by addition of cytochrome-c and dATP, did not result in activation of caspases-3 or -9. Thus, smoke treatment may alter the levels of pro- and antiapoptogenic factors downstream of the mitochondria to inhibit active apoptosome formation. Therefore, unlike previous studies, cell death in response to cigarette smoke by necrosis and not apoptosis may be responsible for the loss of alveolar walls and inflammation observed in emphysema.

Apoptosis↗
PubMed2003

A novel S-nitrosothiol causes prolonged and selective inhibition of platelet adhesion at sites of vascular injury.

OBJECTIVE: Platelet adhesion to areas of endothelial denudation following angioplasty is an important factor contributing to the limitations of this technique. Lipophilic S-nitrosothiols like S-nitroso-N-valerylpenicillamine (SNVP) are novel nitric oxide (NO) donor drugs with anti-platelet and vasodilator properties that are selective for areas of endothelial denudation. Here we assess the inhibitory effect of SNVP on platelet adhesion to angioplastied rabbit carotid arteries. METHODS: A rabbit model was used to measure adhesion of radiolabelled platelets to carotid arteries following balloon angioplasty. The effects of SNVP were compared to the conventional NO donor, nitroglycerin (NTG). Electron microscopy was used to visualize adhering platelets. RESULTS: Angioplasty resulted in endothelial denudation with only a modest reduction in vessel contractility. In vivo administration of NTG and SNVP (both 200 nmol) prevented the hyper-aggregability (approximately 20%) of circulating platelets caused by angioplasty. However, bolus NTG failed to inhibit adhesion of radiolabelled platelets 30 min after angioplasty, despite inducing a transient 30% reduction in systemic blood pressure. In contrast, equimolar SNVP had little effect on blood pressure but markedly inhibited platelet adhesion (62% compared to control; P=0.003). Platelet adhesion was confirmed with electron microscopy. CONCLUSION: The prolonged effects of SNVP at sites of endothelial damage suggest that novel S-nitrosothiols might offer a means of targeted delivery of an antiplatelet agent to areas of vascular injury.

Angioplasty, Balloon↗
PubMed2003

Role of leukotrienes in the regulation of human granulocyte behaviour: dissociation between agonist-induced activation and retardation of apoptosis.

1 Since most inflammatory mediators that stimulate granulocyte responsiveness also delay apoptosis, it is often assumed that activation and longevity are causally related. Using isolated human peripheral blood neutrophils and eosinophils, we examined this association by exploiting the proinflammatory lipid mediators, the leukotrienes (LTs), and investigated granulocyte function and apoptosis. 2 LTB(4) induced elevation of intracellular free Ca(2+) concentration ([Ca(2+)](i)), cell polarisation and retardation of neutrophil apoptosis, although the antiapoptotic effect occurred only at concentrations > or =300 nM. LTB(4)-induced activation was attenuated by CP-105,696, a BLT1-specific antagonist suggesting classical LTB(4) receptor BLT1 involvement. 3 Despite demonstrating the presence of the neutrophil intracellular LTB(4) receptor peroxisome-proliferator activator receptor-alpha (PPARalpha) in neutrophils, the selective PPARalpha agonist WY-14,643 did not mimic LTB(4)-induced prosurvival effects. 4 LTB(4)-induced survival, however, also appeared to be mediated by BLT1 since CP-105,696 inhibited the LTB(4)-mediated antiapoptotic effect. Furthermore, based on studies with CP-105,696 and 5-lipoxygenase inhibitors, lipopolysaccharide (LPS)-, granulocyte-macrophage colony-stimulating factor (GM-CSF)-, dexamethasone- and dibutyryl-cAMP (db-cAMP)-induced delay of neutrophil apoptosis did not involve autocrine production of LTB(4). 5 Although LTB(4) and LTD(4) induced human eosinophil [Ca(2+)](i) elevation and polarization, these LTs did not influence eosinophil apoptosis. Furthermore, LTB(4)- and LTD(4)-induced eosinophil activation was attenuated by CP-105,696 and the Cys-LT(1) receptor antagonist montelukast, respectively, highlighting specific receptor dependency. 6 Thus, mediator-triggered granulocyte activation and antiapoptotic pathways are distinct events that can be differentially regulated.

Acetates↗
PubMed2003

Apoptosis: future perspectives.

The field of apoptosis has expanded to include research in almost all subject areas of cell biology. Despite this growth, there are still many unanswered questions, some of which are fundamental to the development of therapeutic strategies. Most importantly, the underlying mechanisms involved in conferring specificity of apoptotic signals must be determined. This will allow the development of treatments to delete injured or transformed cells and minimize damage to other tissues. Such information is also necessary to combat degenerative diseases, to prevent critical loss of cells. In addition, it would be of therapeutic benefit to selectively induce apoptosis in specific cells where removal of unwanted cells is required (e.g. tumour cells in malignant tissue or inflammatory cells responsible for tissue damage in chronic inflammatory disease). Therefore we have to understand how the full complement of signalling pathways, and survival and apoptotic proteins determine the end effect of an apoptotic signal. Apoptotic cells are known to functionally influence phagocytes that ingest them, but little is known of the effect of apoptosis on neighbouring cells or of signals generated during the apoptotic process itself. Although the processes of mitosis and apoptosis would appear to be diametrically opposed, cell-cycle proteins are involved in apoptosis, and may be able to influence cell-death mechanisms; conversely, proliferation may be caspase-dependent in some cells. Further study is necessary to discover how these pathways are interlinked since such knowledge would be particularly useful in cancer treatment. The link between pathogen-survival strategies and apoptotic mechanisms will also reward further work. Viruses, in particular, exploit cellular survival and death pathways for replication purposes and may represent a targeting approach for specific treatments.

Apoptosis↗
PubMed2003

6th World Congress on Inflammation.

The 6th World Congress on Inflammation was held in the Vancouver Convention and Exhibition Center. This biennial meeting was organised by the Inflammation Research Association (USA) and Triangle 3 Ltd (UK), under the auspices of the International Association of Inflammation Societies. This meeting aimed to promote international cooperation amongst inflammation scientists and provide a communication network for various inflammation societies from around the world. The conference covered the most up-to-date concepts in inflammation, new drugs and treatments, and advances in cell biology. However, there were some topics which were either novel to many attendees or which provided links to a number of presentations, thus underlining their importance. The following is by no means an exhaustive review, but merely reflects the authors' interests.

Animals↗
PubMed2002

Sphingosine kinase: a point of convergence in the action of diverse neutrophil priming agents.

Neutrophils are a vital component of the early acute inflammatory response, but can cause profound tissue damage when activated to excess or prevented from undergoing apoptosis. However, much remains unknown about the intracellular signaling pathways regulating neutrophil activity. The structurally diverse neutrophil-priming agents platelet-activating factor, TNF-alpha, and the substance P analog [D-Arg(6), D-Trp(7,9),N(me)Phe(8)]-substance P(6-11) (SP-G) stimulated a rapid increase in sphingosine kinase activity in freshly isolated human neutrophils. This activity was blocked by preincubation with the sphingosine kinase inhibitor N,N-dimethylsphingosine (DMS). DMS also inhibited the increase in intracellular calcium concentration stimulated by platelet-activating factor, fMLP, and SP-G. This suggests that the increase in intracellular calcium concentration by these agents is dependent on sphingosine kinase activation and the generation of sphingosine-1-phosphate. Changes in cell polarization and the augmentation of the fMLP-induced superoxide anion generation, by all priming agents were also inhibited by DMS, while only the superoxide anion release was blocked by the phosphatidylinositol 3-kinase inhibitor LY294002. Moreover, SP-G and GM-CSF inhibited constitutive neutrophil apoptosis which was completely blocked by DMS. These results suggest a novel role for sphingosine kinase in the regulation of neutrophil priming.

Adult↗
PubMed2002

Novel role for low molecular weight plasma thiols in nitric oxide-mediated control of platelet function.

Nitric oxide (NO) is a powerful antiplatelet agent, but its notoriously short biological half-life limits its potential to prevent the activation of circulating platelets. Here we used diethylamine diazeniumdiolate (DEA/NO) as an NO generator to determine whether the antiplatelet effects of NO are prolonged by the formation of a durable, plasma-borne S-nitrosothiol reservoir. Preincubation of both platelet rich plasma (PRP) and washed platelets (WP) with DEA/NO (2 microm) for 1 min inhibited collagen-induced platelet aggregation by 82 +/- 5 and 91 +/- 2%, respectively. After 30 min preincubation with DEA/NO, NO was no longer detectable in either preparation, but aggregation remained markedly inhibited (72 +/- 7%) in PRP. In contrast, the inhibitory effect in WP was almost completely lost at this time (5 +/- 3%) but was partially restored (39 +/- 10%) in WP containing human serum albumin (1%) and fully restored by co-incubation with albumin and the low molecular weight (LMW) thiols, glutathione, (5 microm), cysteinyl-glycine (10 microm), or cysteine (10 microm). This NO-mediated effect was not seen with LMW thiols in the absence of albumin and was associated with S-nitrosothiol formation. Our results demonstrate that LMW thiols play an important role in both the formation and activation of an S-nitrosoalbumin reservoir that significantly prolongs the duration of action of NO.

Age Factors↗
PubMed2002

Prostaglandin D2 and its metabolites induce caspase-dependent granulocyte apoptosis that is mediated via inhibition of I kappa B alpha degradation using a peroxisome proliferator-activated receptor-gamma-independent mechanism.

Many inflammatory mediators retard granulocyte apoptosis. Most natural PGs studied herein (e.g., PGE(2), PGA(2), PGA(1), PGF(2 alpha)) either delayed apoptosis or had no effect, whereas PGD(2) and its metabolite PGJ(2) selectively induced eosinophil, but not neutrophil apoptosis. This novel proapoptotic effect does not appear to be mediated via classical PG receptor ligation or by elevation of intracellular cAMP or Ca(2+). Intriguingly, the sequential metabolites Delta(12)PGJ(2) and 15-deoxy-Delta(12,) Delta(14)-PGJ(2) (15dPGJ(2)) induced caspase-dependent apoptosis in both granulocytes, an effect that did not involve de novo protein synthesis. Despite the fact that Delta(12)PGJ(2) and 15dPGJ(2) are peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activators, apoptosis was not mimicked by synthetic PPAR-gamma and PPAR-alpha ligands or blocked by an irreversible PPAR-gamma antagonist. Furthermore, Delta(12)PGJ(2) and 15dPGJ(2) inhibited LPS-induced I kappa B alpha degradation and subsequent inhibition of neutrophil apoptosis, suggesting that apoptosis is mediated via PPAR-gamma-independent inhibition of NF-kappa B activation. In addition, we show that TNF-alpha-mediated loss of cytoplasmic I kappa B alpha in eosinophils is inhibited by 15dPGJ(2) in a concentration-dependent manner. The selective induction of eosinophil apoptosis by PGD(2) and PGJ(2) may help define novel therapeutic pathways in diseases in which it would be desirable to specifically remove eosinophils but retain neutrophils for antibacterial host defense. The powerful proapoptotic effects of Delta(12)PGJ(2) and 15dPGJ(2) in both granulocyte types suggest that these natural products control the longevity of key inflammatory cells and may be relevant to understanding the control and resolution of inflammation.

Apoptosis↗
PubMed2002

Inhibition of TCR-mediated shedding of L-selectin (CD62L) on human and mouse CD4+ T cells by metalloproteinase inhibition: analysis of the regulation of Th1/Th2 function.

The generation of a productive primary immune response is dependent on the ability of naïve T lymphocytes to recirculate through peripheral lymph organs to encounter specific antigen. The process of naïve CD4(+) T cell entry into lymph nodes correlates with cell surface expression of L-selectin (CD62L), which mediates early tethering and rolling events to endothelium prior to entry. Here, we demonstrate that surface expression of CD62L enhances CD4(+) T cell activation in vitro. The synthetic hydroxamate metalloproteinase inhibitor (BB-3103), specifically inhibits activation-induced shedding of CD62L from CD4(+) T cells by TCR cross-linking and lowers proliferation in part by reducing rapid tyrosine phosphorylation of zeta-associated protein 70 kDa (ZAP-70) and by increasing cytosolic free Ca(2+) concentration mobilization. BB-3103 also inhibited the proliferative response of both murine CD4(+) Th1 and Th2 subsets in vitro but the inhibitory effects were sustained only in Th2-type cells. Similarly, BB-3103 mediated prolonged inhibition of allergen-dependent peripheral T cell proliferation in atopic dermatitis patients but not in healthy controls. Analysis of CD62L expression on murine CD4(+) T cell subsets revealed that surface expression was maintained on Th1 cells but not Th2 cells. The differential effects of BB-3103 on primed effector CD4(+) T cells may provide new insights into generating therapeutic agents capable of redressing the Th2/Th1 imbalance in allergic diseases.

Animals↗
PubMed2002

Inhibition of nuclear factor-kappaB activation un-masks the ability of TNF-alpha to induce human eosinophil apoptosis.

Apoptosis renders eosinophils functionally effete and marks them for "silent" removal from inflamed sites by macrophages. We show, for the first time, that eosinophils exposed to TNF-alpha rapidly lose their cytoplasmic levels of IkappaBalpha, the inhibitory subunit of NF-kappaB. Consequently, TNF-alpha triggers NF-kappaB mobilization from the cytoplasm to the nucleus, as determined by tracking the NF-kappaB subunit p65 by immunofluorescence and Western blot analysis. Inhibition of TNF-alpha-mediated IkappaBalpha degradation and NF-kappaB activation by gliotoxin or the proteasome inhibitor MG-132 un-masks the caspase-dependent pro-apoptotic properties of TNF-alpha. In addition, cycloheximide similarly renders TNF-alpha pro-apoptotic, suggesting that NF-kappaB activation controls the production of a protein(s) that protects eosinophils from the cytotoxic effects of TNF-alpha. Evidence is presented suggesting that TNF-alpha triggered apoptosis is more susceptible to NF-kappaB inhibition than constitutive apoptosis, leading to the possibility of the specific targeting of apoptosis in eosinophil sub-populations. Prior to morphological signs of apoptosis, TNF-alpha-induced IL-8 synthesis is abrogated by inhibition of NF-kappaB. We propose that NF-kappaB activation plays a critical role in controlling eosinophil responsiveness and apoptosis, and speculate that selective inhibitors of eosinophil NF-kappaB activation may ultimately provide alternative therapeutic agents for the treatment of eosinophilic diseases, including asthma and allergic rhinitis.

Apoptosis↗