Statin-Induced Necrotizing Autoimmune Myopathy: Case Report of a Patient under Chronic Treatment.

Introduction: 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) inhibitors are widely used worldwide to treat dyslipidaemia and prevent cardiovascular events. Statins can cause a wide variety of muscle injuries ranging from myalgia to severe rhabdomyolysis. In most cases, these symptoms are mild and self-limiting and do not require specific treatment besides drug withdrawal. Statin-induced autoimmune necrotizing myopathy (SINAM) is a rare but potentially fatal complication, characterized by the subacute onset of progressive proximal muscle weakness and considerably high creatine phosphokinase (CK) levels in patients exposed to statins. The diagnosis is supported by the presence of antibodies HMGCR, which allows the differentiation from other forms of necrotizing autoimmune myopathies. Symptoms usually progress even after statin discontinuation and can determine severe muscle damage. Summary. We describe the case of a 77-year-old man who developed SINAM after 5 years of statin use. He suffered from muscle functional impairment mainly involving proximal lower limb muscles which progressed to the point that he almost became bedridden. Initial treatment with prednisone alone was not effective, and he required a combination therapy with steroids, methotrexate, and intravenous immunoglobulins. After 5 months of therapy and rehabilitation, he showed complete laboratory response and muscle strength recovery. Conclusion: Recognizing SINAM is paramount in order to promptly start treatment and avoid permanent muscle damage. Using a combination therapy from the beginning could contribute to a better outcome. Prompt statin cessation, categorization of the muscle disease by autoantibody testing, imaging, and histology, exclusion of malignancy, and anti-inflammatory therapy with corticosteroids, antimetabolites, immunoglobulins, and in some cases rituximab are currently accepted approaches to this entity.

Acipimox reduces circulating levels of insulin and associated neutrophilic inflammation in metabolic syndrome.

Metabolic syndrome is a proatherosclerotic condition clustering cardiovascular risk factors, including glucose and lipid profile alterations. The pathophysiological mechanisms favoring atherosclerotic inflammation in the metabolic syndrome remain elusive. Here, we investigated the potential role of the antilipolytic drug acipimox on neutrophil- and monocyte-mediated inflammation in the metabolic syndrome. Acipimox (500 mg) was orally administered to metabolic syndrome patients (n = 11) or healthy controls (n = 8). Serum and plasma was collected before acipimox administration (time 0) as well as 2-5 h afterward to assess metabolic and hematologic parameters. In vitro, the effects of the incubation with metabolic syndrome serum were assessed on human neutrophil and monocyte migration toward the proatherosclerotic chemokine CCL3. Two to five hours after acipimox administration, a significant reduction in circulating levels of insulin and nonesterified fatty acid (NEFA) was shown in metabolic syndrome patients. At time 0 and 2 h after acipimox administration, metabolic syndrome serum increased neutrophil migration to CCL3 compared with healthy controls. No effect was shown in human monocytes. At these time points, serum-induced neutrophil migration positively correlated with serum levels of insulin and NEFA. Metabolic syndrome serum or recombinant insulin did not upregulate CCR5 expression on neutrophil surface membrane, but it increased intracellular JNK1/2 phosphorylation. Insulin immunodepletion blocked serum-induced neutrophil migration and associated JNK1/2 phosphorylation. Although mRNA expression of acipimox receptor (GPR109) was shown in human neutrophils, 5-500 µM acipimox did not affect insulin-induced neutrophil migration. In conclusion, results suggest that acipimox inhibited neutrophil proatherosclerotic functions in the metabolic syndrome through the reduction in circulating levels of insulin.

Systemic and intraplaque mediators of inflammation are increased in patients symptomatic for ischemic stroke.

BACKGROUND AND PURPOSE: The concept of "vulnerable plaque" has been extended to the more recent definition of the "cardiovascular vulnerable patient," in which "intraplaque" and "systemic" factors contribute to the cumulative risk of acute cardiovascular events. Thus, we investigated the possible role of systemic and intraplaque inflammation in patients asymptomatic versus symptomatic for ischemic stroke. METHODS: Regions upstream and downstream the blood flow were isolated from internal carotid plaques of patients asymptomatic (n=63) or symptomatic (n=18) for ischemic stroke. Specimens were analyzed for lipid, collagen, macrophage, lymphocyte, neutrophil, mast cell and smooth muscle cell content, and chemokine and cytokine mRNA expression. Chemokine receptors and adhesion molecules were assessed on circulating leukocytes by flow cytometry. Systemic inflammatory markers and biochemical parameters were measured on total blood, plasma, and serum. RESULTS: Tumor necrosis factor-alpha and CCL5 serum levels as well as intercellular adhesion molecule-1 expression on circulating neutrophils were increased in symptomatic as compared with asymptomatic patients. Collagen content and smooth muscle cell infiltration were decreased in symptomatic plaques. In upstream regions of symptomatic plaques, lipid content and lymphocyte infiltration were increased. In downstream regions of symptomatic plaques, macrophage, neutrophil, and mast cell infiltration were increased. Intraplaque collagen content was positively correlated with smooth muscle cell infiltration and inversely correlated with macrophages, neutrophils, or serum tumor necrosis factor-alpha. Collagen reduction in downstream regions and serum tumor necrosis factor-alpha were independently associated with the likelihood of being symptomatic. CONCLUSIONS: Inflammatory mediators are increased in ischemic stroke. Despite statistically significant, the correlation between tumor necrosis factor-alpha serum level and intraplaque vulnerability was weak and probably of limited biological importance.

Coronary artery calcification and cardiovascular risk: the role of RANKL/OPG signalling.

BACKGROUND: Coronary artery disease (CAD) represents the most relevant cause of death and morbidity in the adult population of developed and developing countries. During the last decades, a strong research effort has been performed to identify more selective markers and better assess the cardiovascular risk in both primary and secondary prevention. MATERIALS AND METHODS: This review updates current knowledge regarding the pathophysiological relevance as possible markers of coronary calcification of the receptor activator of nuclear factor-kappa ligand (RANKL)/osteoprotegerin (OPG) system. Furthermore, the potential clinical use of both RANKL/OPG and coronary calcium score (CAC) to assess cardiovascular vulnerability has been discussed. RESULTS: Emerging evidence indicates that atherosclerotic plaque calcification is positively correlated with vulnerability. Several inflammatory mediators have been shown to modulate arterial calcification, thus increasing the risk of plaque rupture. Among these factors, RANKL/OPG axis might be of particular interest as a promising biomarker of plaque vulnerability in subjects with diffuse coronary calcification. CONCLUSION: Together with clinical parameters of coronary calcification (such as CAC), circulating RANKL/OPG levels could contribute to better assess and predict cardiac events.

sHLA-I contaminating molecules as novel mechanism of ex vivo/in vitro transcriptional and posttranscriptional modulation of transforming growth factor-beta in CD8+ T lymphocytes and neutrophils after intravenous immunoglobulin treatment.

BACKGROUND: Numerous mechanisms have been proposed to explain the beneficial action of intravenous immune globulin (IVIG) in autoimmune and systemic inflammatory disorders. Among others' data, an in vitro increase of intracellular TGF-beta expression when culturing CD4+ T lymphocytes in the presence of IVIG has been reported. As IVIG infusion involves administration of soluble contaminants likewise all hemoderivative preparations, we hypothesized that, besides several other immunomodulatory proposed mechanisms, the clinical effects of IVIG therapy might be, at least partly, due to contaminating soluble HLA Class I (sHLA-I) molecules capable to exert pleiotropic immunomodulatory effects among which TGF-beta(1) modulation. STUDY DESIGN AND METHODS: Ex vivo and in vitro transcriptional and posttranscriptional modulation of TGF-beta(1) in CD8+ T lymphocytes and neutrophils after IVIG infusion was analyzed. RESULTS: Ex vivo analysis of cells drawn from 10 enrolled IVIG recipients pointed out a significant increase of TGF-beta(1) mRNA and intracellular TGF-beta(1) molecules in both leukotypes. In vitro comparable results were obtained incubating CD8+ T lymphocytes and neutrophils from healthy donors with IVIG. The immunodepletion of sHLA-I and/or soluble Fas ligand (sFasL) abolished TGF-beta(1) modulation in both leukotypes. Coculture with human immunoglobulin (Ig)M monoclonal antibody or chimeric IgG (MabThera, Roche), whose manufacturing excludes "contamination," did not exert any mRNA modulation. Finally, IgM or MabThera plus purified sHLA-I molecules enhanced TGF-beta(1) mRNA in both white blood cells to levels comparable to those obtained with IVIG incubation. CONCLUSION: On the whole, these data lead us to speculate that the ability of IVIG administration to modulate TGF-beta(1) might be related to the immunomodulatory activities of sHLA-I and sFasL molecules on activated CD8+ T lymphocytes and neutrophils.

Human mesenchymal stem cells inhibit neutrophil apoptosis: a model for neutrophil preservation in the bone marrow niche.

Mesenchymal stem cells (MSC) establish close interactions with bone marrow sinusoids in a putative perivascular niche. These vessels contain a large storage pool of mature nonproliferating neutrophils. Here, we have investigated the effects of human bone marrow MSC on neutrophil survival and effector functions. MSC from healthy donors, at very low MSC:neutrophil ratios (up to 1:500), significantly inhibited apoptosis of resting and interleukin (IL)-8-activated neutrophils and dampened N-formyl-l-methionin-l-leucyl-l-phenylalanine (f-MLP)-induced respiratory burst. The antiapoptotic activity of MSC did not require cell-to-cell contact, as shown by transwell experiments. Antibody neutralization experiments demonstrated that the key MSC-derived soluble factor responsible for neutrophil protection from apoptosis was IL-6, which signaled by activating STAT-3 transcription factor. Furthermore, IL-6 expression was detected in MSC by real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. Finally, recombinant IL-6 was found to protect neutrophils from apoptosis in a dose-dependent manner. MSC had no effect on neutrophil phagocytosis, expression of adhesion molecules, and chemotaxis in response to IL-8, f-MLP, or C5a. These results support the following conclusions: (a) in the bone marrow niche, MSC likely protect neutrophils of the storage pool from apoptosis, preserving their effector functions and preventing the excessive or inappropriate activation of the oxidative metabolism, and (b) a novel mechanism whereby the inflammatory potential of activated neutrophils is harnessed by inhibition of apoptosis and reactive oxygen species production without impairing phagocytosis and chemotaxis has been identified.

Oxaprozin-induced apoptosis on CD40 ligand-treated human primary monocytes is associated with the modulation of defined intracellular pathways.

The modulation of CD40L activity might represent a promising therapeutic target to reduce monocyte inflammatory functions in chronic diseases, such as rheumatoid arthritis. In the present study, we investigated the possible influence of nonsteroidal anti-inflammatory drugs (NSAIDs) on CD40L-induced monocyte survival. Monocytes were isolated from buffy coats by using Ficoll-Percoll gradients. Monocyte apoptosis was evaluated by fluorescence microscopy on cytopreps stained with acridine orange or using flow cytometry analysis of Annexin-V and Propidium Iodide staining. Akt and NF-kappaB activation was assessed using western blot. Caspase 3 activity was determined spectrophotometrically. Among different NSAIDs, only oxaprozin dose-dependently increased apoptosis of CD40L-treated monocytes. Oxaprozin pro-apoptotic activity was associated with the inhibition of CD40L-triggered Akt and NF-kappaB phosphorylation and the activation of caspase 3. In conclusion, our data suggest that oxaprozin-induced apoptosis in CD40L-treated human monocytes is associated with previously unknown cyclooxygenase (COX)-independent pathways. These intracellular proteins might be promising pharmacological targets to increase apoptosis in CD40L-treated monocytes.

Tumor necrosis factor-alpha (TNF-alpha) induces integrin CD11b/CD18 (Mac-1) up-regulation and migration to the CC chemokine CCL3 (MIP-1alpha) on human neutrophils through defined signalling pathways.

Strong evidence suggests that neutrophils may play an active role in acute and chronic inflammatory disorders, such as rheumatoid arthritis and atherosclerosis. Given the role of pro-inflammatory cytokine TNF-alpha in these inflammatory processes, we planned the present study to investigate the effect of short term incubation with TNF-alpha on neutrophil migration to CCL3, a chemokine produced in inflammatory sites and normally devoid of neutrophil chemotactic properties. We found that TNF-alpha primed neutrophils for migration to CCL3 via CCR5. TNF-alpha-induced migration was a consequence of the TNF-alpha-induced up-regulation of integrin CD11b/CD18 (Mac-1) on neutrophil surface. Furthermore, TNF-alpha activity was found to be strictly dependent on the activation of ERK 1/2 p44, cooperating with the intracellular pathways involving Src kinases, PI3K/Akt, p38 MAPK, well known as activated in response to classical chemoattractants (CXCL8) or priming agents (GM-CSF). On the contrary, the effect of TNF-alpha on neutrophil migration to CCL3 was not dependent on JNK 1/2. In conclusion, the present report shows that TNF-alpha unveils a previously unknown capacity of neutrophils to migrate to CCL3 through the intervention of Mac-1. TNF-alpha regulates Mac-1 up-regulation through signalling pathways, involving various kinases, but not JNK 1/2. Although highly speculative, ERK 1/2 p44 may represent a selective target for the pharmacologic manipulation of neutrophil-mediated adverse activities in TNF-alpha-mediated inflammatory states.

Antiproliferative and proapoptotic activities of a new class of pyrazole derivatives in HL-60 cells.

A series of N-substituted pyrazole derivatives have been synthesized and tested for their anticancer effect on the HL-60 leukaemia cell line. Four were active both in cell-growth inhibition and in inducing apoptosis. The inhibition of cell growth mainly reflects a compound-induced reduction in the number of cells in phases from S to M, whereas the induction of apoptosis involves inhibition of expression of Bcl-2 and enhanced expression of Bax with consequent reduced activation of the proapoptotic caspase 3. Finally, preliminary experiments carried out with tumor cells from myelogenous leukaemic patients showed that the compounds 4c, 4l, 4m, and 4n are indeed capable of inducing apoptosis.

Synthesis and biological evaluation of N-pyrazolyl-N'-alkyl/benzyl/phenylureas: a new class of potent inhibitors of interleukin 8-induced neutrophil chemotaxis.

Neutrophils chemotaxis is a complex multistep process that, if upregulated, causes acute inflammation and a number of autoimmune diseases. We report here the synthesis of a new N-(4-substituted)pyrazolyl-N'-alkyl/benzyl/phenylureas that are potent inhibitors of interleukin-8 (IL8)-induced neutrophil chemotaxis. The first series of compounds, obtained by functionalization with a urea moiety of the 5-amino-1-(2-hydroxy-2-phenylethyl)-1H-pyrazole-4-carboxylic acid ethyl ester 3, blocked the IL8-induced neutrophil chemotaxis, while they did not block N-formylmethionylleucylphenylalanine-mediated chemotaxis. The most active compounds, 3-benzyl- (4d), 3-(4-benzylpiperazinyl)- (4i), 3-phenyl- (4k) and 3-isopropylureido (4a) derivatives, showed an IC50 of 10, 14, 45, and 55 nM, respectively. Several different molecules were then synthesized to obtain more information for SAR study. Compounds 4a, 4d, and 4k were inactive in the binding assays on CXCR1 and CXCR2 (IL8 receptors), whereas they inhibited the phosphorylation of PTKs (protein tyrosine kinases) in the 50-70 kDa region. Moreover, in the presence of the same derivatives, we observed a complete block of F-actin rise and pseudopod formation.

Immune complexes induce monocyte survival through defined intracellular pathways.

Monocytes recruitment and survival at sites of inflammation are determinant for the persistence of inflammatory reactions. Immune-complexes (ICs), whose tissue deposition is involved in a variety of autoimmune diseases, activate monocytes through the interaction with Fcgamma-receptor triggering the secretion of several inflammatory modulators and favoring their tissue accumulation by inhibiting the apoptosis. To elucidate the intracellular pathways governing this process, on the basis of our previous findings regarding the dose-dependent inhibition of apoptosis in IC-activated monocytes, we have investigated the role of PI3K/Akt pathway, MAP kinases, nuclear factor-kappaB (NF-kappaB), and caspase 3, 8, and 9. Here we show that IC-activated monocytes underwent apoptosis at a rate comparable to that of resting monocytes in the presence of LY294002, a selective inhibitor of PI3K, as well in the presence of Akt inhibitor, PD98059 inhibitor of ERK1/2, and SB203580 inhibitor of p38. Moreover, IC-triggered phosphorylation of Akt, ERK1/2, and p38 MAP kinase was demonstrated on Western blot analysis. SN50, an inhibitor of NF-kappaB translocation and BMS345541, a specific inhibitor of IKK, also abolished the apoptosis protection conferred by ICs. In parallel, ICs induced an increase in NF-kappaB activation, as shown by EMSA, together with the expression of XIAP, as shown by Western blot, though indicating that in monocytes IC protection from apoptosis is NF-kappaB dependent. Finally, the activity of caspase 3, 8, and 9 resulted inhibited in IC-activated monocytes. These results disclose a signaling route triggered by ICs which can be involved in the pathophysiology of inflammatory diseases and can represent a target for therapy of IC-mediated diseases.

Sepsis by Pasteurella multocida in an Elderly Immunocompetent Patient after a Cat Bite.

Pasteurella multocida colonizes animal scratches and bites. This bacterium was described to cause sepsis or endocarditis mainly in immunocompromised patients. We report the case of a 92-year-old woman presenting at the Emergency Department with coma and fever a week after the bite of her cat. The cat bite was misdiagnosed at admission partly due to an underestimation of this event by the patient's relatives. An inflamed area localized at perimalleolar skin of the right leg was detected. Laboratory biomarkers of inflammation were elevated. The cerebral computed tomography (CT) scan with angiographic sequences showed a complete occlusion of right intracranial vertebral artery. Total body CT scan and abdominal echocardiography were negative for foci of infection. Three consecutive blood cultures were positive for Pasteurella multocida. A diagnosis of sepsis by Pasteurella multocida was made, and the patient recovered after a specific antimicrobial treatment. In order to confirm the animal transmission, the cat saliva was cultured and found positive for Pasteurella multocida with a similar antibiotic sensitivity to that isolated from the patient. In conclusion, the case of a patient with coma and fever after a cat bite was presented. The transmission of pathogens from pets has to be carefully considered as an important route of infection in immunocompetent patients.

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.

Insulin primes human neutrophils for CCL3-induced migration: crucial role for JNK 1/2.

The present article shows that a short-term exposure of purified human neutrophils to recombinant insulin conferred on these cells both the ability to migrate and the capacity to mobilize [Ca2+]i in response to CCL3, a chemokine per se ineffective with native neutrophils. Furthermore, the effects of recombinant insulin were reproduced by short-term incubation with sera from adult patients with metabolic syndrome, known to be characterized by a hyperinsulinemic state. A strict linear correlation (P<0.01) between sera insulin levels and sera's ability to induce neutrophil locomotion was indeed found. Our data also suggest that (i) insulin primed neutrophils for migration to CCL3 via the selective activation of JNK 1/2, as shown by the use of inhibitors and kinase activation assay; (ii) the activation of Src kinases was necessary but not sufficient for CCL3-induced locomotory activity; (iii) PI3K-Akt, ERK 1/2, and p38 MAPK were not involved in insulin-induced migratory competence. In summary, we provided evidence that the exposition of neutrophils to insulin, as it occurs in hyperinsulinemic conditions, confers the competence of the cells to migrate in response to CCL3, known to be generated near atherosclerotic plaques. As neutrophils have been recently suggested to be involved in breaking unstable atherosclerotic plaques, the present findings contribute to the understanding of the pathophysiology of plaque instability. Finally, biochemical analysis herein carried out raises the hypothesis of JNK 1/2 as an attractive therapeutic target.

Induction of neutrophil chemotaxis by leptin: crucial role for p38 and Src kinases.

Leptin is involved in energy homeostasis, hematopoiesis, inflammation, and immunity. Although hypoleptinemia characterizing malnutrition has been strictly related to increased susceptibility to infection, other hyperleptinemic conditions, such as end-stage renal disease (ESRD), are highly susceptible to bacterial infections. On the other hand, ESRD is characterized by neutrophil functional defects crucial for infectious morbidity, and several uremic toxins capable of depressing neutrophil functions have been identified. In the present study, we investigated leptin's effects on neutrophil function. Our results show that leptin inhibits neutrophil migration in response to classical chemoattractants. Otherwise, leptin 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 [Ca2+]i mobilization, oxidant production, or beta2-integrin upregulation. The results demonstrate that leptin is a pure chemoattractant devoid of secretagogue properties but capable of inhibiting neutrophil chemotaxis to classical neutrophilic chemoattractants. This effect is dependent on the activation of intracellular kinases involved in F-actin polymerization and neutrophil locomotion. Indeed, p38 mitogen-activated protein kinase (MAPK) and Src kinase, but not extracellular-regulated kinase (ERK), were activated by short-term incubation with leptin. Moreover, p38 MAPK inhibitor SB203580 and Src kinase inhibitor PP1, but not MEK inhibitor PD98059, blocked neutrophil chemotaxis toward leptin. Serum from patients with ESRD inhibits migration of normal neutrophils in response to N-formyl-methionine-leucyl-phenylalanine (FMLP) with a strict correlation between serum leptin levels and serum ability to suppress neutrophil locomotion. The serum inhibitory activity can be effectively prevented by immune-depletion of leptin. Taking into account the crucial role of neutrophils in host defense, we show that leptin-mediated ability of ERSD serum to inhibit neutrophil chemotaxis appears to be a mechanism contributing to neutrophil dysfunction in ESRD.

CCL3 (MIP-1alpha) 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.

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.

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.

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.