L-selectin expression is regulated by CXCL8-induced reactive oxygen species produced during human neutrophil rolling.

Neutrophils destroy invading microorganisms by phagocytosis by bringing them into contact with bactericidal substances, among which ROS are the most important. However, ROS also function as important physiological regulators of cellular signaling pathways. Here, we addressed the involvement of oxygen derivatives in the regulation of human neutrophil rolling, an essential component of the inflammatory response. Flow experiments using dihydroethidium-preloaded human neutrophils showed that these cells initiate an early production of intracellular ROS during the rolling phase of the adhesion cascade, a phenomenon that required cell rolling, and the interaction of the chemokine receptor CXCR2 with their ligand CXCL8. Flow cytometry experiments demonstrated that L-selectin shedding in neutrophils is triggered by ROS through an autocrine-paracrine mechanism. Preincubation of neutrophils with the NADPH oxidase complex inhibitor diphenyleniodonium chloride significantly increased the number of rolling neutrophils on endothelial cells. Interestingly, the same effect was observed when CXCL8 signaling was interfered using either a blocking monoclonal antibody or an inhibitor of its receptor. These findings indicate that, in response to CXCL8, neutrophils initiate ROS production during the rolling phase of the inflammatory response. This very early ROS production might participate in the modulation of the inflammatory response by inducing L-selectin shedding in neutrophils.

Impaired HDL cholesterol efflux capacity in systemic lupus erythematosus patients is related to subclinical carotid atherosclerosis.

OBJECTIVES: Lipid profiles appear to be altered in SLE patients due to disease activity and inflammation. Cholesterol efflux capacity (CEC) is the ability of high-density lipoprotein cholesterol to accept cholesterol from macrophages. CEC has been linked to cardiovascular events in the general population and is impaired in SLE patients. The aim of this study was to establish whether CEC is related to subclinical carotid atherosclerosis in SLE patients. METHODS: The present report is of a cross-sectional study that encompassed 418 individuals: 195 SLE patients and 223 controls. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed in patients and controls. Carotid intima-media thickness and carotid plaques were evaluated in SLE patients. A multivariable analysis was performed to study the relationship of CEC to SLE-related data, lipid profile and subclinical carotid atherosclerosis. RESULTS: CEC was downregulated in SLE patients [8.1 (4.2) % vs 16.9 (10.4) %, P = 0.004). This occurred independently of traditional cardiovascular risk factors, statin use or other variations in the lipid profile related to the disease. Traditional cardiovascular risk factors, both in patients and controls, and SLE-related data such as activity, severity or damage were not associated with CEC. After multivariable regression analysis including lipid profile-related molecules, CEC was inversely and independently associated with the presence of carotid plaques in SLE patients [odds ratio 0.87 (95% CI: 0.78, 0.97), P = 0.014]. CONCLUSION: CEC is impaired in SLE patients independently of other inflammation-related lipid profile modifications that occur during the disease. CEC is associated with carotid plaques in SLE patients.

Prevention of neutrophil extravasation by α2-adrenoceptor-mediated endothelial stabilization.

Adrenergic receptors are expressed on the surface of inflammation-mediating cells, but their potential role in the regulation of the inflammatory response is still poorly understood. The objectives of this work were to study the effects of α2-adrenergic agonists on the inflammatory response in vivo and to determine their mechanism of action. In two mouse models of inflammation, zymosan air pouch and thioglycolate-induced peritonitis models, the i.m. treatment with xylazine or UK14304, two α2-adrenergic agonists, reduced neutrophil migration by 60%. The α2-adrenergic antagonist RX821002 abrogated this effect. In flow cytometry experiments, the basal surface expression of L-selectin and CD11b was modified neither in murine nor in human neutrophils upon α2-agonist treatment. Similar experiments in HUVEC showed that UK14304 prevented the activation-dependent upregulation of ICAM-1. In contrast, UK14304 augmented electrical resistance and reduced macromolecular transport through a confluent HUVEC monolayer. In flow chamber experiments, under postcapillary venule-like flow conditions, the pretreatment of HUVECs, but not neutrophils, with α2-agonists decreased transendothelial migration, without affecting neutrophil rolling. Interestingly, α2-agonists prevented the TNF-α-mediated decrease in expression of the adherens junctional molecules, VE-cadherin, ß-catenin, and plakoglobin, and reduced the ICAM-1-mediated phosphorylation of VE-cadherin by immunofluorescence and confocal analysis and Western blot analysis, respectively. These findings indicate that α2-adrenoceptors trigger signals that protect the integrity of endothelial adherens junctions during the inflammatory response, thus pointing at the vascular endothelium as a therapeutic target for the management of inflammatory processes in humans.

PCR-based amplification of heterogeneous IS257-ileS2 junctions for molecular monitoring of high-level mupirocin resistance in staphylococci.

OBJECTIVES: Plasmids encoding the ileS2 gene are responsible for the wide spread of high-level mupirocin resistance in staphylococci, and consequent clinical and epidemiological problems. We investigated the location of insertion sequence IS257 flanking ileS2 in different plasmids and developed a method for molecular typing of the IS257-ileS2 spacer regions. METHODS: Nine ileS2-encoding plasmids (i.e. pPR1-pPR9) classified into distinct structural groups (i.e. S1-S4) were analysed. Complete DNA sequences between IS257s flanking ileS2 were determined. A PCR-based amplification scheme was designed for the simultaneous amplification of up- and down-stream IS257-ileS2 regions. The method was applied to a total of 90 high-level mupirocin-resistant clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). RESULTS: pPR1-pPR9 possessed IS257s flanking ileS2. Plasmids of each structural group showed a unique configuration of IS257-ileS2 spacer regions. The PCR-based method permitted accurate typing of the heterogeneous IS257-ileS2 up- and down-stream junctions, and the differentiation of plasmids of each group. The results obtained corresponded with previous plasmid typing based on restriction enzyme analyses and ileS2 locus hybridization polymorphs. The application of the PCR-based method to a diverse collection of MRSA isolates carrying ileS2-encoding plasmids demonstrated its versatility and revealed extraordinary heterogeneity in the IS257-ileS2 spacers. CONCLUSIONS: The devised PCR-based scheme offers a rapid, simple and effective approach for typing IS257-ileS2 configurations present on ileS2-encoding plasmids. Hopefully, it could serve as a useful molecular epidemiological tool to control high-level mupirocin resistance.

HDL cholesterol efflux capacity and lipid profile in patients with systemic sclerosis.

OBJECTIVE: It is well established that patients with systemic sclerosis (SSc) have a disrupted lipid profile and an increased cardiovascular risk. Cholesterol efflux capacity (CEC), the ability of high-density lipoprotein (HDL)-cholesterol to accept cholesterol from macrophages, has been linked to cardiovascular events. The aim of this study was to establish whether CEC and lipid profile were impaired in SSc patients with respect to controls and whether these changes were associated with disease-related data. METHODS: Cross-sectional study encompassed 188 individuals: 73 SSc patients and 115 controls. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed in patients and controls. A multivariable analysis was performed to study the differences in CEC between patients and controls, and if SSc-related data could explain such differences. RESULTS: The multivariable analysis adjusted for demographic characteristics, cardiovascular risk factors, and lipid-related molecules showed that total cholesterol (beta coefficient: - 22 [95%CI - 37 to - 7], p = 0.004), triglycerides (beta coefficient: 24 [95%CI 2-47], p = 0.033), lipoprotein A (beta coefficient: 22 [95%CI 2-43], p = 0.033), and CEC (beta coefficient: - 6 [95%CI - 10 to - 2]%,p = 0.002) were significantly different between patients and controls. Skin thickness, as assessed by modified Rodnan skin score, was independently associated with a lower CEC (beta coefficient: - 0.21 [95%CI - 0.37 to - 0.05]%, p = 0.011) after multivariable adjustment. CONCLUSION: SSc patients show an abnormal lipid profile with respect to controls including CEC. Skin thickness is independent and inversely associated with CEC in SSc patients.

Differences in Capacity of High-Density Lipoprotein Cholesterol Efflux Between Patients With Systemic Lupus Erythematosus and Rheumatoid Arthritis.

OBJECTIVE: Cholesterol efflux capacity (CEC) is the ability of high-density lipoprotein (HDL) cholesterol to accept cholesterol from macrophages. Lipid profiles and CEC appear to be altered in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) due to disease activity and inflammation. CEC has been linked to cardiovascular events in the general population and to subclinical atherosclerosis in SLE and RA patients. The aim of this study was to establish whether CEC varies between patients with SLE and those with RA. METHODS: The study encompassed 460 individuals (195 SLE patients and 265 patients with RA). CEC (using an in vitro assay) and concentrations of lipoprotein serum were assessed in both populations. A multivariable regression analysis was performed to study whether CEC differs between SLE patients and RA patients. RESULTS: Comparison of lipid patterns revealed that patients with RA have lower HDL cholesterol and higher apolipoprotein B serum levels than SLE patients. CEC was downregulated in SLE patients compared to patients with RA (ß -12 [95% confidence interval -13, -10], P < 0.001). It occurred independently of traditional cardiovascular risk factors, statin use, disease-related data, and other variations in the lipid profile related to the diseases. CONCLUSION: Patients with RA have a more proatherogenic lipid pattern compared to those with SLE. However, CEC seems to be more damaged in SLE patients than in RA patients.

HDL cholesterol efflux capacity is related to disease activity in psoriatic arthritis patients.

OBJECTIVE: Cholesterol efflux capacity (CEC) is the ability of high-density lipoprotein (HDL) cholesterol to accept cholesterol from macrophages. CEC is linked to cardiovascular events in the general population, and it has been shown to be disrupted in inflammatory states. The aim of this study was to establish whether CEC is impaired in PsA patients and if this could be explained by disease-related features like disease activity. METHODS: Case-control study that encompassed 105 individuals: 52 PsA patients and 53 controls. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed in patients and controls. Disease activity in patients with PsA was measured using the Disease Activity Index for Psoriatic Arthritis (DAPSA). Multivariate analysis was performed to study the differences between CEC in patients and controls, and the relation of CEC with PsA activity-related data and lipid profile. RESULTS: Total cholesterol, apolipoprotein A1, and LDL cholesterol serum levels were downregulated in PsA patients. CEC did not differ between controls and patients (17 ± 10 vs. 18 ± 2%, p = 0.15) after adjusting for traditional cardiovascular risk factors or other variations in the lipid profile related to the disease. Traditional cardiovascular risk factors, both in patients and controls, were not related to CEC. After multivariate regression analysis, the DAPSA score was inversely and independently associated with CEC (beta coefficient - 0.75 [95%CI - 1.39-- 0.11] %, p = 0.023). CONCLUSION: CEC is inversely associated with disease activity in PSA patients, reinforcing the role of disease activity as a key factor in the development of accelerated atherosclerosis in these patients.Key Points• Cholesterol efflux capacity is linked to cardiovascular events in the general population.• In patients with psoriatic arthritis, cholesterol efflux capacity is inversely associated with disease activity (beta coefficient - 0.75[95% CI - 1.39-- 0.11] %, p = 0.023).• This finding reinforces the role of disease activity as a key factor in increasing cardiovascular risk in psoriatic arthritis patients.

Role of CXCL13 and CCL20 in the recruitment of B cells to inflammatory foci in chronic arthritis.

BACKGROUND: B cells exert their pathogenic action in rheumatoid arthritis (RA) locally in the synovium. This study was undertaken to elucidate the chemokines responsible for the recruitment of B cells in the inflamed synovium, taking into account that the rich chemokine milieu present in the synovial tissue can fine-tune modulate discrete chemokine receptors. METHODS: Expression levels of chemokine receptors from the CC and CXC family, as well as CD27, were assessed by flow cytometry in CD20+ mononuclear cells isolated from the peripheral blood (PB) and synovial fluid (SF) of RA and psoriatic arthritis patients. Transwell experiments were used to study migration of B cells in response to a chemokine or in the presence of multiple chemokines. RESULTS: B cells from the SF of arthritis patients showed a significant increase in the surface expression of CCR1, CCR2, CCR4, CCR5 and CXCR4 with respect to PB. Conversely, SF B cells expressed consistently lower amounts of CXCR5, CXCR7 and CCR6, independent of CD27 expression. Analysis of permeabilized B cells suggested internalization of CXCR5 and CCR6 in SF B cells. In Transwell experiments, CCL20 and CXCL13, ligands of CCR6 and CXCR5, respectively, caused a significantly higher migration of B cells from PB than of those from SF of RA patients. Together, these two chemokines synergistically increased B-cell migration from PB, but not from SF. CONCLUSIONS: These results suggest that CXCL13 and CCL20 might play major roles in RA pathogenesis by acting singly on their selective receptors and synergistically in the accumulation of B cells within the inflamed synovium.

Differential Antigen-presenting B Cell Phenotypes from Synovial Microenvironment of Patients with Rheumatoid and Psoriatic Arthritis.

OBJECTIVE: To study the qualitative and quantitative phenotypic changes that occur in molecules involved in antigen presentation and costimulation in synovial B cells from rheumatoid arthritis (RA) and psoriatic arthritis (PsA). METHODS: The presence of HLA-DR, CD86, and CD40 in CD20+ cells was studied in RA synovium biopsies using immunohistochemistry and immunofluorescence. Expression was assessed by flow cytometry of the Class II molecules CD40, CD86, CD23, and CD27 on B cells from the synovial fluid (SF), with respect to peripheral blood, from 13 patients with RA and 15 patients with PsA. Expression of interferon-induced protein with tetratricopeptide repeats 4 (IFIT4) in immune-selected CD20+ cells from patients with RA was assessed by quantitative realtime PCR. RESULTS: Infiltrating synovial RA, B cells expressed HLA-DR, CD40, and CD86. Increased expression of CD86, HLA-DR, and HLA-DQ in B cells from SF was found in patients with RA and PsA. HLA-DP was also elevated in rheumatoid SF B cells; conversely, a significantly lower expression was observed in SF from patients with PsA. CD40 expression was increased in SF B cells from PsA, but not in patients with RA. Interestingly, CD20 surface expression level was significantly lower in SF B cells (CD19+, CD138-) from RA, but not in patients with PsA. CD27 upregulation and CD23 downregulation were observed in synovial B cells in both pathologies. Finally, a 4-fold increase in IFIT4 mRNA content was shown in B cells from SF in patients with RA. CONCLUSION: Synovial B cells from patients with RA and patients with PsA express different antigen-presenting cell phenotypes, suggesting that this cell type plays a dissimilar role in the pathogenesis of each disease.

Superoxide anion mediates the L-selectin down-regulation induced by non-steroidal anti-inflammatory drugs in human neutrophils.

UNLABELLED: Non-steroidal anti-inflammatory drugs (NSAIDs) induce the shedding of L-selectin in human neutrophils through a mechanism still not well understood. In this work we studied both the functional effect of NSAIDs on the neutrophils/endothelial cells dynamic interaction, and the potential involvement of reactive oxygen species (ROS) in the NSAIDs-mediated down-regulation of L-selectin. When human neutrophils were incubated with diclofenac, a significant reduction in the number of cells that rolled on activated endothelial cells was observed. Different NSAIDs (flufenamic acid, meclofenamic acid, diclofenac, indomethacin, nimesulide, flurbiprofen, meloxicam, phenylbutazone, piroxicam, ketoprofen and aspirin) caused variable increase in neutrophil intracellular ROS concentration, which was inversely proportional to the change produced in L-selectin surface expression. Pre-incubation of neutrophils with superoxide dismutase, but not with catalase, showed both a significant protective effect on the L-selectin down-regulation induced by several NSAIDs and a diminished effect of diclofenac on neutrophil rolling. Interestingly, diclofenac and flufenamic acid but not piroxicam significantly increased the extracellular superoxide anion production by neutrophils, and inhibition of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase activity with diphenyleneiodonium prevented the down-regulation of L-selectin by diclofenac. In accordance with these results, neutrophils from patients with chronic granulomatous disease, a hereditary disease in which neutrophils show a reduced capacity to form superoxide radicals, exhibited a lower down-regulation of L-selectin (IC50: 15.3 µg/ml) compared to normal controls (IC50: 5.6 µg/ml) in response to diclofenac. CONCLUSION: A group of NSAIDs is capable of interfering with the ability of neutrophils to interact with endothelial cells by triggering L-selectin-shedding through the NADPH-oxidase-dependent generation of superoxide anion at the plasma membrane.