Dexamethasone -induced apoptosis of human monocytes exposed to immune complexes. Intervention of CD95- and XIAP-dependent pathways

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-kappaB/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-kappaB pathway governing the expression of XIAP. Both the pathways are susceptible to inhibition by monocyte treatment with pharmacologic concentrations of dexamethasone.

Chemokine receptor expression and function in childhood acute lymphoblastic leukemia of B-lineage

Scanty information is available on chemokine receptor expression and function in childhood B-lineage acute lymphoblastic leukemia (ALL). Thirteen pro-B, 17 early pre-B, 12 pre-B, and 9 B-ALL/Burkitt lymphoma (BL) pediatric cases were tested for CXCR1 to CXCR5 and CCR1 to CCR7 expression. CXCR2, CXCR3, and CXCR4 were expressed in the majority of cases, while the other receptors were variably expressed or absent. CXCR4 mediated chemotaxis of all leukemic cell subtypes. Freshly isolated CCR7(+) early pre-B-ALL cells migrated to CCL19, whereas CCR7(+) pro-B- and pre-B-ALL cells were attracted by CCL19 only following culture with soluble recombinant CD40 ligand.

Effect of different cytokines on mammaglobin and maspin gene expression in normal leukocytes: possible relevance to the assays for the detection of micrometastatic breast cancer

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-α, IL-1β) 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.

A review of the emerging profile of the anti-inflammatory drug oxaprozin

Oxaprozin is a nonsteroidal anti-inflammatory drug characterised by a propionic acid-based structure. It is able to diffuse easily into inflamed synovial tissues after oral administration. Although discovered > 20 years ago, it is now under intensive investigation because of its unusual pharmacodynamic properties. Other than being a nonselective cyclooxygenase inhibitor, the drug is capable of inhibiting both anandamide hydrolase in neurons (median inhibitory concentration [IC50] = 85 micromol/l), with consequent potent analgesic activity, and NF-kappaB activation in inflammatory cells (IC50 = 50 micromol/l). Moreover, oxaprozin induces apoptosis of activated monocytes in a dose-dependent manner, with the effect being detectable at a concentration of 5 micromol/l and reaching the maximum activity at 50 micromol/l. As monocyte-macrophages and NF-kappaB pathways are crucial for synthesis of proinflammatory and histotoxic mediators in inflamed joints, oxaprozin appears to be endowed with pharmacodynamic properties exceeding those presently assumed as markers of classical nonsteroidal anti-inflammatory drug.

CCL3 (MIP-1α) induces in vitro migration of GM-CSF-primed human neutrophils via CCR5-dependent activation of ERK 1/2

CCL3 (MIP-1alpha), a prototype of CC chemokines, is a potent chemoattractant toward human neutrophils pre-treated with GM-CSF for 15 min. GM-CSF-treated neutrophils migrate also to the selective CCR5 agonist CCL4 (MIP-1beta). CCL3- and CCL4-triggered migration of GM-CSF-primed neutrophils was inhibited by the CCR5 antagonist TAK-779. Accordingly, freshly isolated neutrophils express CCR5. Extracellular signal-regulated kinases (ERK)-1/2 and p38 mitogen-activated protein kinase (MAPK) inhibitors blocked CCL3-induced migration of GM-CSF-primed neutrophils. When the activation of ERK-1/2 and p38 MAPK by CCL3 and the classical neutrophilic chemokine CXCL8 (IL-8) were compared, both the chemokines were capable of activating p38 MAPK. On the contrary, whereas both ERK-1 and ERK-2 were activated by CXCL8, no ERK-1 band was detectable after CCL3 triggering. Finally, neutrophil pre-treatment with GM-CSF activated both ERK-1 and ERK-2. This suggests that by activating ERK-1, GM-CSF renders neutrophils rapidly responsive to CCL3 stimulation throughout CCR5 which is constitutively expressed on the cell surface.

Leptin as a uremic toxin interferes with neutrophil chemotaxis

Leptin is a pleiotropic molecule involved in energy homeostasis, hematopoiesis, inflammation, and immunity. Hypoleptinemia characterizing starvation has been strictly related to increased susceptibility to infection secondary to malnutrition. Nevertheless, ESRD is characterized by high susceptibility to bacterial infection despite hyperleptinemia. Defects in neutrophils play a crucial role in the infectious morbidity, and several uremic toxins that are capable of depressing neutrophil functions have been identified. Only a few and contrasting reports about leptin and neutrophils are available. This study provides evidence that leptin inhibits neutrophil migration in response to classical chemoattractants. Moreover, serum from patients with ESRD inhibits migration of normal neutrophils in response to N-formyl-methionyl-leucyl-phenylalanine with a strict correlation between serum leptin levels and serum ability to suppress neutrophil locomotion. Finally, the serum inhibitory activity can be effectively prevented by immune depletion of leptin. The results also show, however, that leptin by itself is endowed with chemotactic activity toward neutrophils. The two activities-inhibition of the cell response to chemokines and stimulation of neutrophil migration-could be detected at similar concentrations. On the contrary, neutrophils exposed to leptin did not display detectable [Ca(2+)](i) mobilization, oxidant production, or beta(2)-integrin upregulation. The results demonstrate that leptin is a pure chemoattractant devoid of secretagogue properties that are capable of inhibiting neutrophil chemotaxis to classical neutrophilic chemoattractants. Taking into account the crucial role of neutrophils in host defense, the leptin-mediated ability of ERSD serum to inhibit neutrophil chemotaxis appears as a potential mechanism that contributes to the establishment of infections in ERSD.

In vitro inhibition of human neutrophil histotoxicity by ambroxol: evidence for a multistep mechanism

Neutrophils are major culprits for the protease/antiprotease imbalance during various lung diseases, that is, chronic obstructive pulmonary disease, cystic fibrosis, idiopathic pulmonary fibrosis and adult respiratory distress syndrome. Thus, these cells are presently considered an ideal target for the pharmacologic control of tissue injury during these diseases. This study was planned in order to investigate if ambroxol and its precursor bromhexine are actually capable of preventing alpha-1-antitrypsin (A1AT) inactivation by stimulated neutrophils and possibly to look into the mechanisms underlying this event. Ambroxol inhibited the production of superoxide anion by activated neutrophils, whereas bromhexine had no inhibitory effect. Ambroxol decreased the production of hypochlorous acid (HOCl) from activated neutrophils with high efficiency, whereas bromhexine had a modest activity. Ambroxol and bromhexine were capable of limiting the chlorination of monochlorodimedon by HOCl, displaying the capacity of directly scavenging the oxidant. Ambroxol decreased the release of elastase and myeloperoxidase from activated neutrophils, whereas bromhexine was ineffective. Ambroxol prevented the A1AT inactivation by neutrophils, whereas bromhexine was completely ineffective. Among drugs currently available for in vivo use in humans, ambroxol is unique by virtue of its ability to prevent neutrophil-mediated A1AT inactivation via inhibition of HOCl production as well as HOCl scavenging. Also taking into account its capacity for curbing elastase release, the drug displays the potential to lessen the burden of oxidants/proteases and to increase the antiprotease shield at the site of inflammation. Thus, ambroxol appears to be a good candidate for raising attempts to develop new therapeutic histoprotective approaches to inflammatory bronchopulmonary diseases.

Synthesis and biological evaluation of neutrophilic inflammation inhibitors

In several non-infectious human diseases, such as ulcerous colitis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), the extravasal recruitment of neutrophils plays a crucial role in the development of tissue damage, which, when persistent, can lead to the irreversible organ dysfunction. The neutrophil activation is controlled by a number of intracellular pathways, particularly by a cAMP-dependent protein kinase A (PKA) which also acts on phosphodiesterase IV (PDE4) gene stimulating the synthesis of this enzyme, able to transform cAMP to inactive AMP. PDE4 inhibitors enhance intracellular cAMP and decrease inflammatory cell activation. Several 3-cyclopentyloxy-4-methoxybenzaldehyde and 3-cyclopentyloxy-4-methoxybenzoic acid derivatives were synthesized and studied by us to evaluate their ability to inhibit the superoxide anion production in human neutrophils. These compounds were found able to inhibit the neutrophil activation and some of them increased the cAMP level on tumor necrosis factor-alpha-stimulated neutrophils. Moreover, they also inhibited selectively the human PDE4 enzyme, although they are less potent than the reference compound Rolipram. We report here synthesis, biological studies and some SAR considerations concerning the above mentioned compounds.

CCL19 and CXCL12 Trigger in Vitro Chemotaxis of Human Mantle Cell Lymphoma B Cells

PURPOSE

Few data are available in the literature on chemokine receptor expression and migratory capability of mantle cell lymphoma (MCL) B cells. Information on these issues may allow us to identify novel mechanisms of chemokine-driven tumor cell migration.

EXPERIMENTAL DESIGN

The research was designed to investigate: (a) expression of CCR1 to CCR7 and CXCR1 to CXCR5 chemokine receptors; and (b) chemotaxis to the respective ligands in MCL B cells and in their normal counterparts, i.e., CD5+ B cells.

RESULTS

Malignant B cells from MCL patients and normal counterparts displayed similar chemokine receptor profiles. MCL B cells were induced to migrate by CXCL12 and CCL19, whereas normal CD5+ B cells migrated to the former, but not the latter chemokine. Overnight culture of MCL B cells and their normal counterparts with CXCL12 cross-sensitized other chemokine receptors to their ligands in some tumor samples but not in CD5+ B cells.

CONCLUSIONS

CCR7 and CXCR4 ligands may play a key role in tumor cell migration and spreading in vivo. CXCL12 may additionally contribute by sensitizing MCL B cells to respond to the ligands of other chemokine receptors.

Oxidative Stress Mediates Apoptotic Changes Induced by Hyperglycemia in Human Tubular Kidney Cells

Reactive oxygen species (ROS) are important mediators for several biologic responses, including apoptosis. The present study evaluated the time course of changes in intracellular ROS production and apoptosis-related proteins, as well as apoptotic changes in human tubular proximal cells (HK-2 cells) exposed to hyperglycemia. Apoptosis (annexin V binding), ROS formation (fluorescence probe dichlorofluorescin diacetate and FACScan flow cytometry), and X chromosome-linked protein (XIAP; Western blot) were studied in HK-2 cells grown in a medium containing normal (NG) or high glucose (HG) concentrations (5.5 or 30 mM, respectively) for 18 to 48 h. HG promoted an increase (65% at 18 h and 73% at 24 h; P < 0.05 versus NG) in intracellular ROS generation. At 18 h, the NF-kB binding activity (evaluated by electrophoretic mobility-shift assay) was suppressed by HG. At the same time, the expression of NF-kB-induced antiapoptotic XIAP was reduced in HG-treated cells. Apoptotic changes were observed at 48 h (34 +/- 7% in HG versus 10 +/- 3% in NG; P < 0.001). Changes in ROS production at 24 h predicted changes in the apoptotic index at 48 h (r = 0.96, P < 0.0001). These results suggest that hyperglycemia induces apoptotic changes in human tubular cells via an increase in oxidative stress and that a downregulation of antiapoptotic protein XIAP is a component of this response.

Monoclonal LYM-1 antibody-dependent cytolysis by human neutrophils exposed to GM-CSF: auto-regulation of target cell attack by cathepsin G

Murine monoclonal antibody (mAb) Lym-1 is an immunoglobulin G2a specific for certain human leukocyte antigen-DR variants expressed on the surface of malignant B cells. It has been proposed for serotherapy in patients with B lymphomas. We have previously shown that mAb Lym-1 synergizes with granulocyte macrophage-colony stimulating factor to promote Raji B-lymphoid cell lysis by human neutrophils via the intervention of neutrophil Fc receptors type II and D-mannose-inhibitable interactions between CD11b-CD18 integrins and CD66b glycoproteins. Here, we provide evidence that the process is oxygen-independent by inference related to the release of primary granules and is regulated by cathepsin G activity. The lysis was indeed reproduced by replacing normal neutrophils with cells from three patients suffering from chronic granulomatous disease, i.e., neutrophils genetically incapable of generating oxidants. Moreover, the lysis was inhibited by the serine protease inhibitor 3,4-dichloroisocoumarin and by Z-glycyl-leucyl-phenyl-chloromethyl ketone (Z-Gly-Leu-Phe-CMK), which blocks cathepsin G. Conversely, the lysis was unaffected by N-methoxysuccinyl-alanyl-alanyl-prolyl-alanyl-CMK (MeOSuc-Ala-Ala-Pro-Ala-CMK; elastase inhibitor) and MeOSuc-Ala-Ala-Pro-valine (Val)-CMK, which inhibits elastase and proteinase 3. The ability of neutrophils, engaged in cytolysis, to release cathepsin G was proved by detecting this enzymatic activity spectrophotometrically and immunocytochemically. Moreover, inhibition of cathepsin G activity by concentrations of Z-Gly-Leu-Phe-CMK, incapable of affecting elastase activity, was found to reduce the release of elastase and myeloperoxidase from neutrophils under conditions similar to those used for cytolytic assays. These findings suggest that neutrophils auto-regulate their lytic efficiency by controlling the exocytosis of primary granules via their cathepsin G activity.

Transforming growth factor-beta1 in supernatants from stored red blood cells inhibits neutrophil locomotion

Studies comparing transfusion and nontransfusion patients suggest an increased risk of postoperative infections in transfusion groups. Supernatants of blood components have been shown to affect the function of T lymphocytes and natural killer cells. Here, we found that supernatants from stored red blood cells (RBCs) inhibit human neutrophil migration in response to formyl peptides and stimulate neutrophil locomotion. These effects can be observed with high dilutions of RBC supernatants, such as 1:5 x 106 (vol/vol), able to trigger locomotion as well as desensitization of the cells to alternative chemoattractants. The phenomenon might be mediated by chemoattractants present in the supernatants. As RBC supernatants failed to mobilize intracellular free calcium, the chemoattractants should belong to the group of pure chemoattractants, that is, soluble Fas ligand (sFasL) and transforming growth factor-beta1 (TGF-beta1), known to act without increasing calcium levels. Recombinant TGF-beta1, but not sFasL, was found to reproduce the ability of RBC supernatants to both inhibit neutrophil response to formyl peptides and stimulate neutrophil locomotion. Moreover, TGF-beta1-immunodepleted supernatants did not display neutrophil-directed activities. Finally, RBC supernatants from RBCs stored after depletion of leukocytes were incapable of affecting neutrophil function. With neutrophils acting as a first-line antimicrobial defense, the ability, shown here, of high dilutions of RBC supernatants to inhibit neutrophil chemotaxis through TGF-beta1 may be a relevant determinant of infections in the postoperative period for transfusion patients. Consistently, the neutrophil chemotactic response to formyl peptide was inhibited by the plasma obtained from 5 transfusion patients.

Effect of clotting factors concentrates on lymphocyte and neutrophil function in vitro

Immunological abnormalities have been reported in haemophiliacs. Although infections with HIV, hepatitis and other viruses may contribute to these abnormalities, immune defects are detectable also in HIV seronegative haemophiliacs. It is likely that chronic exposure to extraneous proteins in clotting factor concentrates (CFCs) may play a role in immunomodulation, but the underlying mechanisms remain unclear. The results of the present paper show that: a) soluble HLA class I (sHLA-I), soluble Fas-ligand (sFas-L) and transforming growth factor beta 1 (TGF-beta1) are detectable in plasma derived but not in recombinant CFCs; b) the level of sHLA-I and sFas-L is proportional to the grade of CFCs purity whereas TGF-beta1 showed very variable levels; c) soluble molecules detected in CFCs exert immunomodulatory effects in vitro like apoptosis induction in Jurkat cells and inhibition of mixed lymphocyte reaction response, antigen-specific lymphocyte cytotoxic activity and neutrophil chemotaxis.

Taurine prevents apoptosis induced by high ambient glucose in human tubule renal cells

BACKGROUND

Hyperglycemia selectively triggers apoptosis in tubule and endothelial cells. Taurine, a conditionally essential amino acid, is abundant in several tubule segments, but its role has not been defined fully. It can serve as an osmolyte or as an endogenous antioxidant. Taurine metabolism is altered in diabetes mellitus, with extracellular and intracellular pools reduced. It is still unknown whether taurine can play a role as a protective agent in apoptosis induced by high glucose in tubular cells.

METHODS

Apoptosis (by annexin V binding and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling method), cellular reactive oxygen species (ROS) formation (by fluorescent probe 2'-7' dichlorofluorescin diacetate and FACScan flow cytometry), and Bcl-2 and Bax proteins (by immunostaining) were studied in a human proximal tubular cell line (HK-2) grown in a medium with physiologic (5.5 mM) or high (30 mM) glucose concentrations for 48 hours. In separate experiments, taurine (3-24 mM) was added to the media.

RESULTS

The exposure of human tubule cells to 30 mM glucose for 48 hours resulted in a significant increase in apoptosis compared with 5.5 mM glucose (35 +/- 8% vs. 6 +/- 3%, p < 0.001). Thirty mM mannitol failed to induce the effects of high glucose. High glucose-mediated apoptosis was associated with a decrease in the expression of Bcl-2 (-87%) and a twofold increase in the expression of Bax protein. Taurine had a dose-dependent effect in preventing high-glucose-induced apoptosis (-78%, p < 0.001 at 24 mM). Moreover, with taurine, intracellular ROS decreased by 34% (p < 0.05), and changes in intracellular ROS formation induced by taurine at 24 hours predicted the variations in the apoptotic index at 48 hours (r = 0.87, p < 0.02). Other antioxidants, such as glutathione and N-acetylcysteine, also attenuated the high glucose-induced apoptosis.

CONCLUSION

These results demonstrate that taurine attenuates hyperglycemia-induced apoptosis in human tubular cells via an inhibition of oxidative stress. Taurine might act as an endogenous antioxidant in tubule cells and could exert a beneficial effect in preventing tubulointerstitial injury in diabetic nephropathy.

Synovial fluid from patients with rheumatoid arthritis inhibits neutrophil apoptosis: role of adenosine and proinflammatory cytokines

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.

Chemotaxis of human tonsil B lymphocytes to CC chemokine receptor (CCR) 1, CCR2 and CCR4 ligands is restricted to non-germinal center cells

We have investigated the effects of nine CC chemokines, i.e. macrophage inflammatory protein (MIP)-1alpha/CCL3, MIP-1beta/CCL4, MIP-3alpha/CCL20, MIP-5/CCL15, monocyte chemotactic protein (MCP)-1/CCL2, MCP-2/CCL8, MCP-3/CCL7, eotaxin/CCL11 and macrophage-derived chemokine (MDC)/CCL22 on the locomotion of human tonsil B lymphocytes and their subsets. Upon isolation, B cells were poorly responsive, but, following short-term culture, they displayed statistically significant chemotactic responses (P < 0.001) to MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC. CC chemokine receptor (CCR) 1 to CCR6 were up-regulated after culture. MIP-1beta, MIP-3alpha and eotaxin did not stimulate B cell migration. Scattered information is available on B cell subset responses to chemokines. Therefore, we investigated the effects of MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC on the in vitro locomotion of non-germinal center (GC) (CD38(-)) and GC (CD38(+)) B cells. All chemokines enhanced significantly (P < 0.001) the migration of the former, but not of the latter, cells. CCR1, CCR2 and CCR4 were detected by flow cytometry on non-GC (i.e. naive and memory) B cells, whereas they were absent (CCR1 and CCR2) or poorly expressed (CCR4) on GC B cells.

Differential regulation of spontaneous and immune complex-induced neutrophil apoptosis by proinflammatory cytokines. Role of oxidants, Bax and caspase-3

Neutrophil apoptosis represents a crucial step in the mechanisms governing the resolution of neutrophilic inflammation. Several soluble mediators of inflammation modulate neutrophil survival, retarding their apoptosis, whereas neutrophil activation by immune complexes (IC) results in the acceleration of apoptosis. To investigate neutrophil fate at the site of inflammation, we studied the effects of interleukin (IL)-2, IL-6, IL-8, IL-15, GM-CSF, and fMLP on spontaneous and IC-induced neutrophil apoptosis and the mechanisms regulating the survival of these cells. Spontaneous apoptosis was inhibited by GM-CSF, IL-6, and IL-15, but only GM-CSF overturned IC-induced apoptosis. No role of oxidants on the modulation of IC-dependent apoptosis was found. Indeed, fMLP or GM-CSF augmented the IC-dependent oxidative response, whereas the other compounds were ineffective. CGD neutrophils showed low levels of spontaneous apoptosis, but when exposed to IC, underwent a sharp increment of the apoptotic rate in a GM-CSF-inhibitable manner. Conversely, the expression of the proapoptotic protein Bax in 18-h aged neutrophils was down-regulated by GM-CSF, IL-6, and IL-15. Furthermore, IC induced a nearly threefold Bax up-regulation, which was completely reversed only by GM-CSF. Accordingly, the spontaneous activity of caspase-3 was inhibited by GM-CSF, IL-6, and IL-15. Furthermore, IC induced a sharp increment of enzymatic activity, and only GM-CSF inhibited the IC-dependent acceleration. Our results show that apoptosis of resting and IC-activated neutrophils is regulated differently, GM-CSF being the most potent neutrophil antiapoptotic factor. The results also unveil the existence of an oxidant-independent, Bax- and caspase-3-dependent, intracellular pathway regulating neutrophil apoptosis.

Delayed neutrophil apoptosis induced by synovial fluid in rheumatoid arthritis: role of cytokines, estrogens, and adenosine

The fate of neutrophils at sites of inflammation, where these cells are likely exposed to both anti- and proapoptotic influences, needs to be clarified. To investigate this issue, we studied the survival of neutrophils in the presence of articular fluids from RA joints before and after immune complex activation. Eight of eleven samples of RA synovial fluid studied were found to inhibit spontaneous and immune complex-stimulated neutrophil apoptosis. No relationships were found between GM-CSF and TNF-alpha concentrations measured on each sample of synovial fluid studied and the levels of neutrophil apoptosis detectable in the presence of the same synovial fluid. Furthermore, no activity on neutrophil survival was observed at either physiologic or pharmacologic concentrations of estradiol. On the contrary, the synovial fluid anti-apoptotic activity correlates (r(2) = 0.8818, p < 0.0001) with the adenosine detected at concentrations in each sample ranging from 18.7 to 52.4 microM. Finally, synovial fluids were incapable of interfering with neutrophil activation evaluated as superoxide anion production. Our results suggest that the microenvironment of rheumatoid synovial fluid is a proinflammatory milieu responsible for the in loco persistence of activated and long-surviving neutrophils.

Chimaeric Lym-1 monoclonal antibody-mediated cytolysis by neutrophils from G-CSF-treated patients: stimulation by GM-CSF and role of Fc gamma -receptors

Chimaeric Lym-1 (chLym-1) is a monoclonal antibody generated by fusing the variable region genes of murine Lym-1 to human gamma1 and kappa constant regions. Owing to its selectivity and avidity for human malignant B cells, it is an attractive candidate for developing immune-interventions in B-lymphomas. In the attempt to identify rational bases for optimizing potential chLym-1 related therapeutic approaches, we studied the ability of this ch-mAb to trigger neutrophil-mediated Raji cell cytolysis in cooperation with two neutrophil-related cytokines, G-CSF and GM-CSF. ChLym-1 triggered low levels of cytolysis by normal neutrophils but induced consistent cytolysis in neutrophils from individuals treated with G-CSF. When exposed to GM-CSF, neutrophils from subjects treated with G-CSF became potent effectors, also leading to 75% lysis. By using mAbs specific for distinct FcgammaRs, normal neutrophils were inhibited by mAb IV.3, suggesting the intervention of FcgammaRII, constitutively expressed on the cells. On the other hand, neutrophils from patients treated with G-CSF were inhibited by mAb IV.3 plus mAb 197, a finding consistent with a cooperative intervention of FCgammaRII and G-CSF-induced FcgammaRI. The anti-FcgammaRIII mAb 3G8 promoted significant enhancement of the neutrophil cytolytic efficiency. Therefore, neutrophil FcgammaRIII behaves as a down-regulator of the cytolytic potential. The present findings suggest new attempts to develop mAb-based and G-CSF/GM-CSF combined immune-interventions in B lymphomas.

HPLC determination of adenosine in human synovial fluid

A high-performance liquid chromatographic method has been developed for the quantitative determination of adenosine in human synovial fluid. The method is simple, rapid and, overall, selective. No interference with the components of the biological matrix was observed in these chromatographic conditions. An ODS (250 x 4.6 mm) 5 microm column was used with an isocratic elution of a phosphate buffer-acetonitrile mobile phase. Detection was carried out on a UV detector at 260 nm. Calibration curve was found to be linear in the 0.7--70 microg ml(-1) range. Linear regression analysis of the data demonstrates the efficacy of the method in terms of precision and accuracy. The precision of this method, calculated as the relative standard deviation (RSD) of the recoveries (1.57--2.21%), was excellent. The limits of quantitation (LOQ) and detection (LOD) were respectively 0.7 and 0.2 microg ml(-1). The method was applied to some samples of synovial effusion from patients affected by rheumatoid arthritis. The concentrations of adenosine which were found were included in the range of the calibration curve.