The exudation of neutrophils is the hallmark of a form of inflammatory response occurring after tissue colonization by invading bacteria or as an expression of various non-infectious diseases. All ...these diseases are characterized by a high risk of developing irreversible tissue injury. Neutrophil-endothelium interactions, activation-induced functional and structural changes of responding neutrophils, regulatory systems of neutrophil function, and oxidative-proteolytic pathways responsible for histotoxicity are reviewed here. Finally, perspectives for rational approaches to handle the development of tissue injury during neutrophilic inflammation are considered.
Objective. In synovial fluid (SF) from patients with rheumatoid arthritis (RA), neutrophils are exposed to proinflammatory mediators endowed with either anti‐apoptotic or pro‐apoptotic properties. We ...investigated neutrophil apoptosis in the presence of SF from 11 RA patients. Methods. SF was obtained from affected knees of 11 patients with RA. Human neutrophil apoptosis was evaluated by light microscopic examination and flow‐cytometric analysis of annexin V binding. Immune complex‐induced neutrophil activation was evaluated as superoxide anion production. Adenosine levels in SF were detected by chromatographic analysis and cytokine levels were studied by enzyme‐linked immunosorbent assay. Results. Spontaneous and immune complex‐triggered neutrophil apoptosis was reduced by SF from eight out of 11 patients. Immune complex‐induced neutrophil activation was unaffected by SF. The cytokines tested had no role in promoting the anti‐apoptotic activity of SF. On the contrary, the anti‐apoptotic activity of SF was found to depend on the presence of adenosine. Adenosine levels detected in the various samples of SF correlated significantly with the anti‐apoptotic activity of the fluids and with the number of apoptotic neutrophils detected in the articular exudate. Conclusion. The microenvironment of rheumatoid SF is a proinflammatory milieu responsible for the in loco persistence of activated and long‐surviving neutrophils. Adenosine plays a crucial role in this phenomenon, which is related to anti‐apoptotic activity.
Summary
1. Chlorhexidine digluconate has been used as a topical antiseptic in the treatment of acne vulgaris and periodontitis. The acute phase of these diseases involves neutrophilic infiltration. ...Neutrophil activation and recruitment to inflammatory sites are crucial in both protection against bacterial infection and the induction of hystotoxic damage. Activated neutrophils release several enzymes, including elastase and myeloperoxidase (MPO), which contribute to tissue injury via direct toxic actions, the generation of oxidants and inactivation of protective factors, such as α1‐antitrypsin (α1‐AT). In the present study, we investigated whether chlorhexidine can modulate neutrophil‐mediated histotoxicity.
2. Human primary neutrophils were isolated from healthy donors. Inactivation of α1‐AT by neutrophils or hypochlorous acid (HOCl) was evaluated by spectrophotometry and sodium dodecyl sulphate–polyacrylamide gel electrophoresis analysis of its capacity to complex with porcine pancreatic elastase (PPE). Neutrophil generation of HOCl, superoxide anion and MPO release were assessed spectrophometrically.
3. Chlorhexidine (0, 0.5, 1, 5 and 10 μmol/L) dose‐dependently prevented HOCl‐induced inactivation of α1‐AT and reduced HOCl recovery from phorbol myristate acetate (PMA)‐treated human neutrophils, but did not inhibit superoxide anion and MPO release. Chlorhexidine directly inhibited HOCl recovery from neutrophils and HOCl‐induced inactivation of α1‐AT in a cell‐free assay. Accordingly, chlorhexidine reversed HOCl‐mediated inhibition of α1‐AT capacity to complex with PPE.
4. These data suggest that chlorhexidine prevents neutrophil‐induced α1‐AT inactivation via a direct inhibitory action on HOCl. Although highly speculative, the present study indicates that chlorhexidine may protect inflamed tissues not only through its antimicrobial properties, but also via a direct anti‐inflammatory effect on neutrophil toxic products.
Background: Follicular center lymphoma displays widespread lymph node involvement at diagnosis. The chemoattractants that control the locomotion of follicular center lymphoma B cells have not been ...established. Stromal cell-derived factor-1 (SDF-1) is a CXC-class chemokine that enhances the migration of normal human B cells and is expressed in peripheral lymphoid tissues. Here we have investigated 1) whether SDF-1 stimulates the in vitro locomotion of follicular center lymphoma B cells and of their presumed normal counterparts (i.e., germinal center B cells) and 2) whether the same cells express SDF-1 transcripts. Methods: B cells were purified by immunomagnetic bead manipulation. Messenger RNA was detected by reverse transcription–polymerase chain reaction. Migration was assessed by the filter and collagen invasion assays. All P values were two sided. Results: Follicular center lymphoma B lymphocytes showed a statistically significant migratory response to 300 ng/mL SDF-1, both in the filter and in the collagen assays (P = .002 for each). Such response was mediated by the SDF-1 receptor, CXCR4. CD40 monoclonal antibody (MAb) and tonsillar germinal center B cells treated with CD40 MAb and recombinant interleukin 4, but not freshly isolated, migrated statistically significantly faster in the presence than in the absence of SDF-1 (P = .002 in both filter and collagen assays). Freshly isolated follicular center lymphoma and germinal center B cells expressed SDF-1 transcripts. Conclusions: This study shows that SDF-1 substantially enhances the migration of follicular center lymphoma B cells but not the migration of freshly purified germinal center B cells. This difference may be related to the extended survival of follicular center lymphoma versus germinal center B cells. SDF-1 produced in follicular center lymphoma lymph nodes may play a role in the local dissemination of tumor cells.
Chemokines are low molecular weight cytokines specialized in leukocyte recruitment. Recent studies have shown that tumor cells of hematopoietic and non hematopoietic origin express different ...chemokine receptors that may be involved in neoplastic cell growth, metastasis and angiogenesis. Human lymphoproliferative disorders arise from the malignant transformation of normal lymphoid cells frozen at discrete maturational stages. Studies performed with acute or chronic lymphoproliferative disorders have shown that CXCR4, the unique receptor for CXCL12, is up-regulated in many B and T cells malignancies and may be involved in metastatic localization of the neoplastic elements. Additional chemokine receptors are expressed in the individual lymphoproliferative disorders, but some of these are often non functional. Here we shall review the state of the art on chemokine receptor expression and function in human lymphoproliferative disorders, stressing the potential value of chemokines receptors as novel therapeutic targets. In this respect, small antagonistic peptides are being produced by pharmaceutical companies and hold great promise for clinical application.
In cancer patients, the ability to detect disseminated tumour cells in peripheral blood or bone marrow could improve prognosis and consent both early detection of metastatic disease and monitoring of ...the efficacy of systemic therapy. These objectives remain elusive mainly due to the lack of specific genetic markers for solid tumours. The use of surrogate tissue-specific markers can reduce the specificity of the assays and give rise to a clinically unacceptable false-positive rate. Mammaglobin (MAM) and maspin are two putative breast tissue-specific markers frequently used for detection of occult tumour cells in the peripheral blood, bone marrow and lymph nodes of breast cancer patients. In this study, it was evaluated whether MAM and maspin gene expression may be induced in the normal blood and bone marrow cells exposed to a panel of cytokines, including chemotactic factors (C5a, interleukin (IL)-8), LPS, proinflammatory cytokines (TNF-alpha, IL-1beta) and growth factors (IL-3, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor). The experimental data show that all cytokines included in the panel, except for IL-8, were able to induce maspin expression; on the contrary, MAM gene was never induced. These results suggest that MAM is more specific than maspin and that the possible interference of cytokines should be taken into account in interpreting molecular assays for detection of isolated tumour cells.
Summary
1
Neutrophils release several histotoxic molecules that cause tissue injury. Neutrophil apoptosis is a crucial process that governs the persistence of inflammatory disorders and tissue ...damage. Thus, in the present study, we investigated whether the anti‐inflammatory drug sulphasalazine (SSZ) affects neutrophil apoptosis in the presence of insoluble immune complex (IC).
2
Neutrophils were obtained from healthy donors. Neutrophils were resuspended in incubation medium and incubated for 2–12 h with or without 10, 30 or 100 μmol/L SSZ and 25 μg/mL IC. In some experiments, cells were co‐incubated with 20 μmol/L Z‐IETD‐fmk (a caspase 8 inhibitor) or 20 μmol/L Z‐LEHD‐fmk (a caspase 9 inhibitor). Apoptosis was evaluated morphologically on cytological preparations stained with May–Grünwald–Giemsa as well as by flow cytometry analysis of annexin V and propidium iodide staining. Caspase 3 activity was determined spectrophotometrically.
3
At 100 μmol/L, SSZ significantly accelerated IC‐induced neutrophil apoptosis. Treatment of neutrophils with 20 μmol/L of the caspase 8 or 9 inhibitors Z‐IETD‐fmk or Z‐LEHD‐fmk, respectively, demonstrated that the SSZ‐induced pro‐apoptotic effect was mediated by a caspase 8‐ but not caspase 9‐dependent pathway. The caspase 3 activity assay showed that treatment with 100 μmol/L SSZ increased caspase 3 activation.
4
In conlusion, the results of the present study indicate that it is possible that the molecular mechanism underlying SSZ protection against neutrophil‐mediated tissue injury inflammatory disorders, such as rheumatoid arthritis and inflammatory bowel diseases, involves a caspase 8‐dependent pathway.
The Largest Italian SMES Ottonello, L.; Canepa, G.; Albertelli, P. ...
IEEE transactions on applied superconductivity,
06/2006, Letnik:
16, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
The industrial prototype of a superconducting magnetic energy storage (SMES), sized to deliver 1 MW for 1 s, was designed and constructed as the result of a research project, partly funded by the ...Italian Ministry of Education, University and Research. After successfully undergoing factory tests, the SMES was installed at the Elettra Synchrotron Light facility in Trieste-I and is there under commissioning and testing as protecting device from temporary voltage dips and interruptions, the most frequent grid malfunctions causing faults of the beam magnetic confinement system. The innovative part of the prototype, which also includes several sophisticated power electronics items, is a 2.6 MJ stored energy magnet, wound with a new low-losses Nb Ti cable, cooled by liquid helium at 4.2 K and adopting an electric insulation design solution to withstand 8 kV and obtain very close contact between coolant and coil. New design hybrid current leads, made of a resistive copper stage and a high temperature superconducting one, cooperate together with a set of three cryocoolers and a multi-shield cryostat to keep the helium loss amount negligible. Electrical insulation of the most critical components and the quench detection system is extremely accurate, because the voltage at coil-ends rises up to 2.500 V. The experimental results obtained at Elettra during the beginning of the SMES commissioning phase are presented
Monocytes and macrophages play a key role in the initiation and persistence of inflammatory reactions. The possibility to interfere with the survival of these cells, once recruited and activated at ...sites of inflammation, is an attractive therapeutic option. Although resting monocytes are susceptible to pharmacologically induced apoptosis, no data are available about the possibility to modulate the survival of activated monocytes. The present work was planned to investigate if dexamethasone is able to promote apoptosis of human monocytes activated by immune complexes. When monocytes were cultured with immune complexes, a dose-dependent inhibition of apoptosis was observed. Dexamethasone stimulated apoptosis of resting and activated monocytes in a dose-dependent manner. Both the immune complex inhibitory activity and dexamethasone stimulatory properties depend on NF-kB/XIAP and Ras/MEK/ERK/CD95 pathways. In fact, the exposure of monocytes to immune complexes increased NF-kB activation and XIAP expression, which in turn were inhibited by dexamethasone. On the other hand, immune complex-stimulated monocytes displayed a reduced expression of CD95, which is prevented by dexamethasone, as well as by MEK inhibitor U0126. Furthermore, anti-CD95 ZB4 mAb prevented dexamethasone-induced apoptosis in immune complex-stimulated monocytes. Similarly, ZB4 inhibited dexamethasone-mediated augmentation of caspase 3 activity. The present findings suggest that Fc triggering by insoluble immune complexes result in the activation of two intracellular pathways crucial for the survival of monocytes: 1. Ras/MEK/ERK pathway responsible for the down-regulation of CD95 expression; 2. NF-kB pathway governing the expression of XIAP. Both the pathways are susceptible to inhibition by monocyte treatment with pharmacologic concentrations of dexamethasone.
Human neutrophilic polymorphonuclear leukocytes (neutrophils) are terminally differentiated cells that die by undergoing apoptosis. At present, the intracellular pathways governing this process are ...only partially known. In particular, although the adenylate cyclase-dependent generation of cyclic AMP (cAMP) has been implicated in the triggering of apoptosis in lymphoid cells, the role of the intracellular cAMP pathway in neutrophil apoptosis remains controversial. In the present study, we found that two cAMP-elevating agents, prostaglandin E2 (PGE2) and the phosphodiesterase type IV inhibitor RO 20-1724, inhibit neutrophil apoptosis without inducing cell necrosis. When administered in combination, PGE2 and RO 20-1724 displayed additive effects. Moreover, neutrophil apoptosis was inhibited by a membrane-permeable analog of cAMP, dibutyryl-cAMP, in a dose-dependent manner. Finally, treatment of neutrophils with the protein kinase A inhibitor H-89 prevented PGE2- and RO 20-1724-induced inhibition of cell apoptosis. In conclusion, taking into account that PGE2 and other cAMP-elevating agents are well known downregulators of neutrophil functions, our results suggest that conditions favoring a state of functional rest, such as intracellular cAMP elevation, prolong the life span of neutrophils by delaying apoptosis.
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