TNFα counteracts interleukin-10 anti-inflammatory pathway through the NOX2-Lyn-SHP-1 axis in human monocytes.

TNFα-mediated signaling pathways play a pivotal role in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA) and inflammatory bowel disease (IBD) by promoting phagocyte inflammatory functions, notably cytokine release and reactive oxygen species (ROS) production by NOX2. In contrast, interleukin-10 (IL-10), a powerful anti-inflammatory cytokine, potently shuts down phagocyte activation, making IL-10 an attractive therapeutic candidate. However, IL-10 therapy has shown limited efficacy in patients with inflammatory diseases. Here, we report that TNFα blocks IL-10 anti-inflammatory pathways in human monocytes, thereby prolonging inflammation. TNFα decreased IL-10-induced phosphorylation of STAT3 and consequently IL-10-induced expression of the major anti-inflammatory factor, SOCS3. Decreased STAT3 phosphorylation was due to a SHP1/2 phosphatase, as NSC-87877, a SHP1/2 inhibitor, restored STAT3 phosphorylation and prevented the TNFα-induced inhibition of IL-10 signaling. TNFα activated only SHP1 in human monocytes and this activation was NOX2-dependent, as diphenyleneiodonium, a NOX2 inhibitor, suppressed SHP1 activation and STAT3 dephosphorylation triggered by TNFα. ROS-induced activation of SHP1 was mediated by the redox-sensitive kinase, Lyn, as its inhibition impeded TNFα-induced SHP1 activation and STAT3 dephosphorylation. Furthermore, H2O2 recapitulated TNFα-inhibitory activity on IL-10 signaling. Finally, NSC-87877 dampened collagen antibody-induced arthritis (CAIA) in mice. These results reveal that TNFα disrupts IL-10 signaling by inducing STAT3 dephosphorylation through a NOX2-ROS-Lyn-SHP1 axis in human monocytes and that inhibition of SHP1/2 in vivo protects against CAIA. These new findings might explain the poor efficacy of IL-10 therapy in patients with inflammatory diseases and suggest that anti-TNFα agents and SHP1/2 inhibitors could improve the therapeutic use of IL-10.

Metformin Inhibits ROS Production by Human M2 Macrophages via the Activation of AMPK.

Metformin (1,1-dimethylbiguanide hydrochloride) is the most commonly used drug to treat type II diabetic patients. It is believed that this drug has several other beneficial effects, such as anti-inflammatory and anticancer effects. Here, we wanted to evaluate the effect of metformin on the production of reactive oxygen species (ROS) by human macrophages. Macrophages are generated in vivo from circulating monocytes depending on the local tissue environment. In vitro proinflammatory macrophages (M1) and anti-inflammatory macrophages (M2) can be generated by culturing monocytes in the presence of different cytokines, such as GM-CSF or M-CSF, respectively. We show that metformin selectively inhibited human monocyte differentiation into proinflammatory macrophages (M1) without inhibiting their differentiation into anti-inflammatory macrophages (M2). Moreover, we demonstrate that, in response to LPS, M2 macrophages produced ROS, which could be very harmful for nearby tissues, and metformin inhibited this process. Interestingly, metformin with LPS induced activation of the adenosine-monophosphate-activated protein kinase (AMPK) and pharmacological activation of AMPK by AICAR, a known AMPK activator, decreased ROS production, whereas the deletion of AMPK in mice dramatically enhanced ROS production in different types of immune cells. These results suggest that metformin exhibits anti-inflammatory effects by inhibiting the differentiation of human monocytes into M1 macrophages and by limiting ROS production by macrophages via the activation of AMPK.

Impaired p47phox phosphorylation in neutrophils from patients with p67phox-deficient chronic granulomatous disease.

Superoxide production by the phagocyte reduced NAD phosphate (NADPH) oxidase is essential for innate immunity as shown in chronic granulomatous disease (CGD), an immunodeficiency disease resulting from mutations in 1 of its genes. The NADPH oxidase is composed of 2 membrane proteins (gp91phox/NOX2 and p22phox) and 4 cytosolic proteins (p47phox, p67phox, p40phox, and Rac1/2). The phosphorylation of p47phox is required for NADPH oxidase activation in cells. As p47phox and p67phox can form a tight complex in cells, we hypothesized that p67phox could regulate p47phox phosphorylation. To investigate this hypothesis, we used phospho-specific antibodies against 5 major p47phox-phosphorylated sites (Ser304, Ser315, Ser320, Ser328, and Ser345) and neutrophils from healthy donors and from p67phox-/- CGD patients. Results showed that formyl-methionyl-leucyl-phenylalanine and phorbol myristate acetate induced a time- and a concentration-dependent phosphorylation of p47phox on Ser304, Ser315, Ser320, and Ser328 in healthy human neutrophils. Interestingly, in neutrophils and Epstein-Barr virus-transformed B lymphocytes from p67phox-/- CGD patients, phosphorylation of p47phox on serine residues was dramatically reduced. In COSphox cells, the presence of p67phox led to increased phosphorylation of p47phox. In vitro studies showed that recombinant p47phox was phosphorylated on Ser304, Ser315, Ser320, and Ser328 by different PKC isoforms and the addition of recombinant p67phox alone or in combination with p40phox potentiated this process. Thus, p67phox and p40phox are required for optimal p47phox phosphorylation on Ser304, Ser315, Ser320, and Ser328 in intact cells. Therefore, p67phox and p40phox are novel regulators of p47phox-phosphorylation.

Outcome of SARS-CoV-2 infection is linked to MAIT cell activation and cytotoxicity.

Immune system dysfunction is paramount in coronavirus disease 2019 (COVID-19) severity and fatality rate. Mucosal-associated invariant T (MAIT) cells are innate-like T cells involved in mucosal immunity and protection against viral infections. Here, we studied the immune cell landscape, with emphasis on MAIT cells, in cohorts totaling 208 patients with various stages of disease. MAIT cell frequency is strongly reduced in blood. They display a strong activated and cytotoxic phenotype that is more pronounced in lungs. Blood MAIT cell alterations positively correlate with the activation of other innate cells, proinflammatory cytokines, notably interleukin (IL)-18, and with the severity and mortality of severe acute respiratory syndrome coronavirus 2 infection. We also identified a monocyte/macrophage interferon (IFN)-α-IL-18 cytokine shift and the ability of infected macrophages to induce the cytotoxicity of MAIT cells in an MR1-dependent manner. Together, our results suggest that altered MAIT cell functions due to IFN-α-IL-18 imbalance contribute to disease severity, and their therapeutic manipulation may prevent deleterious inflammation in COVID-19 aggravation.

Effects of venoms on neutrophil respiratory burst: a major inflammatory function

Neutrophils play a pivotal role in innate immunity and in the inflammatory response. Neutrophils are very motile cells that are rapidly recruited to the inflammatory site as the body first line of defense. Their bactericidal activity is due to the release into the phagocytic vacuole, called phagosome, of several toxic molecules directed against microbes. Neutrophil stimulation induces release of this arsenal into the phagosome and induces the assembly at the membrane of subunits of the NAPDH oxidase, the enzyme responsible for the production of superoxide anion that gives rise to other reactive oxygen species (ROS), a process called respiratory burst. Altogether, they are responsible for the bactericidal activity of the neutrophils. Excessive activation of neutrophils can lead to extensive release of these toxic agents, inducing tissue injury and the inflammatory reaction. Envenomation, caused by different animal species (bees, wasps, scorpions, snakes etc.), is well known to induce a local and acute inflammatory reaction, characterized by recruitment and activation of leukocytes and the release of several inflammatory mediators, including prostaglandins and cytokines. Venoms contain several molecules such as enzymes (phospholipase A2, L-amino acid oxidase and proteases, among others) and peptides (disintegrins, mastoporan, parabutoporin etc.). These molecules are able to stimulate or inhibit ROS production by neutrophils. The present review article gives a general overview of the main neutrophil functions focusing on ROS production and summarizes how venoms and venom molecules can affect this function.(AU)

Apocynin prevents GM-CSF-induced-ERK1/2 activation and -neutrophil survival independently of its inhibitory effect on the phagocyte NADPH oxidase NOX2.

Neutrophils are key cells in innate immunity and inflammation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to enhance many neutrophil functions such as reactive oxygen species (ROS) production, degranulation and cell survival via the activation of the ERK1/2 pathway. ERK1/2 pathway activation is redox sensitive and could be modulated by ROS. In order to investigate whether NADPH oxidase NOX2-derived ROS could contribute to GM-CSF-induced ERK1/2 phosphorylation, we tested the effect of two selective NOX2 inhibitors, diphenylene iodonium (DPI) and apocynin. Results showed that, while both DPI and apocynin strongly inhibited neutrophil ROS production, only apocynin, but not DPI, inhibited GM-CSF-induced ERK1/2 phosphorylation, suggesting that ROS are not involved in this process. Apocynin did not affect GM-CSF-induced p38MAPKinase phosphorylation, another redox sensitive kinase. Interestingly, apocynin inhibited GM-CSF-induced MEK1/2 and AKT phosphorylation without affecting fMLF-induced phosphorylation of these proteins. GM-CSF is known to inhibit neutrophils apoptosis and to promote cell survival via the AKT-ERK1/2 pathway. In this regard, we found that apocynin also inhibited GM-CSF-induced anti-apoptotic effect in neutrophils. These results suggest that NADPH oxidase NOX2-derived ROS are not involved in GM-CSF-induced ERK1/2 phosphorylation and that apocynin inhibits GM-CSF-induced ERK1/2 phosphorylation pathway independently of its inhibitory action on NADPH oxidase NOX2. Thus, apocynin can exert an anti-inflammatory effect not only by limiting neutrophil ROS production but also by decreasing neutrophil survival at inflammatory site.

Neutrophil Degranulation of Azurophil and Specific Granules.

Neutrophils play a pivotal role in innate immunity and in the inflammatory reactions. Upon activation, neutrophils release several toxic molecules directed against microbial pathogens into the phagosome. These molecules include reactive oxygen species (ROS), myeloperoxidase, glucosidases, proteases, and antibacterial peptides. In resting cells these proteins and the enzyme responsible for ROS production (NOX2) are stored inside or at the membranes of different granules called azurophil or primary, specific or secondary, gelatinase or tertiary, and the secretory vesicles. Each granule has a specific density, content, and markers. Myeloperoxidase (MPO) is the azurophil granule marker, and the neutrophil-gelatinase-associated lipocalin (NGAL) is the specific granule marker. After cell activation by different stimuli, granule contents are released into the phagosome or in the extracellular space through a process called degranulation. Also during this process, membrane granules fuse with the phagosome and plasma membrane allowing expression of new markers at the cell surface. The degranulation can be assessed by measuring either the release of different proteins by neutrophils or the expression of granule markers at the plasma membrane. In this chapter, we describe the techniques used to measure degranulation of azurophil and specific neutrophil granules using different approaches such as measurement of MPO enzymatic activity and detection of MPO and NGAL proteins by SDS-PAGE and Western blot.

The Prolyl Isomerase Pin1 Controls Lipopolysaccharide-Induced Priming of NADPH Oxidase in Human Neutrophils.

Production of superoxide anion and other reactive oxygen species (ROS) by neutrophils has a vital role in host defense against microbes. However, over-production can induce cell injury participating to inflammation. Superoxide anion is produced by the phagocyte NADPH oxidase/NOX2, a multicomponent enzyme system consisting of six proteins: two trans-membrane proteins (gp91 phox and p22 phox ) and four soluble cytosolic proteins (p40 phox , p67 phox , p47 phox , and the small G-proteins, Rac1/2). Phosphorylation of p47 phox on several serines regulates NADPH oxidase activation. LPS released by gram negative bacteria can enhance or prime neutrophil superoxide production in combination with other agonists such as the bacterial peptide formyl-Met-Leu-Phe (fMLP). Since the pathways involved in LPS-induced priming are not completely understood, we investigated the role of the prolyl cis/trans isomerase Pin1 in this process. Two different Pin1 inhibitors, PiB, and Juglone are able to block LPS-induced priming of ROS production by human neutrophils in a concentration dependent manner. PiB and Juglone did not inhibit LPS-induced CD11b translocation neither CD62L shedding. LPS induced an increase of Pin1 activity in neutrophils similar to TNFα and fMLP. Since the phosphorylation of p47 phox on Ser345 is critical for NADPH oxidase up-regulation, we investigated the effect of LPS on this process. Results show that LPS induced the phosphorylation of p47 phox mainly on serine 345 and induced the activation of p38MAPKinase and ERK1/2. These results suggest that the prolyl cis/trans isomerase Pin1 may control LPS-induced priming of superoxide production in human neutrophils. Pharmacological targeting of Pin1 could be a valuable approach in sepsis.

Cytosolic PCNA interacts with p47phox and controls NADPH oxidase NOX2 activation in neutrophils.

Neutrophils produce high levels of reactive oxygen species (ROS) by NADPH oxidase that are crucial for host defense but can lead to tissue injury when produced in excess. We previously described that proliferating cell nuclear antigen (PCNA), a nuclear scaffolding protein pivotal in DNA synthesis, controls neutrophil survival through its cytosolic association with procaspases. We herein showed that PCNA associated with p47phox, a key subunit of NADPH oxidase, and that this association regulated ROS production. Surface plasmon resonance and crystallography techniques demonstrated that the interdomain-connecting loop of PCNA interacted directly with the phox homology (PX) domain of the p47phox. PCNA inhibition by competing peptides or by T2AA, a small-molecule PCNA inhibitor, decreased NADPH oxidase activation in vitro. Furthermore, T2AA provided a therapeutic benefit in mice during trinitro-benzene-sulfonic acid (TNBS)-induced colitis by decreasing oxidative stress, accelerating mucosal repair, and promoting the resolution of inflammation. Our data suggest that targeting PCNA in inflammatory neutrophils holds promise as a multifaceted antiinflammatory strategy.

[Usefulness of free light chain measurement in monoclonal gammopathy, other haematological malignancies and autoimmune diseases]. / Intérêt du dosage des chaînes légères libres dans le cadre de gammapathies monoclonales, autres hémopathies malignes et maladies auto-immunes.

Immunoglobulin light chains are called free when they are not linked with heavy chains to form a whole immunoglobulin. Quantification of free light chains is a part of the French national authority for health guidelines for diagnostic and follow-up of light chain, oligo or non-secretory myeloma and AL amyloidosis. Most recently, the World health organisation had included free light chains quantification in prognostic criteria for monoclonal gammopathy of undetermined significance. However the literature bring to light some other potential indications of this analysis in the exploration of monoclonal gammopathy, also in lymphoid malignancies and some autoimmune diseases such as diabetes, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis and Sjögren syndrome.

NOX1-derived ROS drive the expression of Lipocalin-2 in colonic epithelial cells in inflammatory conditions.

Inflammatory bowel disease (IBD) is characterized by severe and recurrent inflammation of the gastrointestinal tract, associated with altered patterns of cytokine synthesis, excessive reactive oxygen species (ROS) production, and high levels of the innate immune protein, lipocalin-2 (LCN-2), in the mucosa. The major source of ROS in intestinal epithelial cells is the NADPH oxidase NOX1, which consists of the transmembrane proteins, NOX1 and p22PHOX, and the cytosolic proteins, NOXO1, NOXA1, and Rac1. Here, we investigated whether NOX1 activation and ROS production induced by key inflammatory cytokines in IBD causally affects LCN-2 production in colonic epithelial cells. We found that the combination of TNFα and IL-17 induced a dramatic upregulation of NOXO1 expression that was dependent on the activation of p38MAPK and JNK1/2, and resulted into an increase of NOX1 activity and ROS production. NOX1-derived ROS drive the expression of LCN-2 by controlling the expression of IκBζ, a master inducer of LCN-2. Furthermore, LCN-2 production and colon damage were decreased in NOX1-deficient mice during TNBS-induced colitis. Finally, analyses of biopsies from patients with Crohn's disease showed increased JNK1/2 activation, and NOXO1 and LCN-2 expression. Therefore, NOX1 might play a key role in mucosal immunity and inflammation by controlling LCN-2 expression.

NADPH oxidase activation in neutrophils: Role of the phosphorylation of its subunits.

Neutrophils are key cells of innate immunity and during inflammation. Upon activation, they produce large amounts of superoxide anion (O2 -. ) and ensuing reactive oxygen species (ROS) to kill phagocytized microbes. The enzyme responsible for O2 -. production is called the phagocyte NADPH oxidase. This is a multicomponent enzyme system that becomes active after assembly of four cytosolic proteins (p47phox , p67phox , p40phox and Rac2) with the transmembrane proteins (p22phox and gp91phox , which form the cytochrome b558 ). gp91phox represents the catalytic subunit of the NADPH oxidase and is also called NOX2. NADPH oxidase-derived ROS are essential for microbial killing and innate immunity; however, excessive ROS production induces tissue injury and prolonged inflammatory reactions that contribute to inflammatory diseases. Thus, NADPH oxidase activation must be tightly regulated in time and space to limit ROS production. NADPH oxidase activation is regulated by several processes such as phosphorylation of its components, exchange of GDP/GTP on Rac2 and binding of p47phox and p40phox to phospholipids. This review aims to provide new insights into the role of the phosphorylation of the NADPH oxidase components, that is gp91phox , p22phox , p47phox , p67phox and p40phox , in the activation of this enzyme.

NOX5 and p22phox are 2 novel regulators of human monocytic differentiation into dendritic cells.

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells and are key cells of the immune system, acquiring different phenotypes in accordance with their localization during the immune response. A subset of inflammatory DCs is derived from circulating monocytes (Mo) and has a key role in inflammation and infection. The pathways controlling Mo-DC differentiation are not fully understood. Our objective was to investigate the possible role of nicotinamide adenine dinucleotide phosphate reduced form oxidases (NOXs) in Mo-DC differentiation. In this study, we revealed that Mo-DC differentiation was inhibited by NOX inhibitors and reactive oxygen species scavengers. We show that the Mo-DC differentiation was dependent on p22phox, and not on gp91phox/NOX2, as shown by the reduced Mo-DC differentiation observed in chronic granulomatous disease patients lacking p22phox. Moreover, we revealed that NOX5 expression was strongly increased during Mo-DC differentiation, but not during Mo-macrophage differentiation. NOX5 was expressed in circulating myeloid DC, and at a lower level in plasmacytoid DC. Interestingly, NOX5 was localized at the outer membrane of the mitochondria and interacted with p22phox in Mo-DC. Selective inhibitors and small interfering RNAs for NOX5 indicated that NOX5 controlled Mo-DC differentiation by regulating the JAK/STAT/MAPK and NFκB pathways. These data demonstrate that the NOX5-p22phox complex drives Mo-DC differentiation, and thus could be critical for immunity and inflammation.

TLR8, but not TLR7, induces the priming of the NADPH oxidase activation in human neutrophils.

Neutrophils play a key role in host defense against invading pathogens by releasing toxic agents, such as ROS and antimicrobial peptides. Human neutrophils express several TLRs that recognize a variety of microbial motifs. The interaction between TLR and their agonists is believed to help neutrophils to recognize and to kill pathogens efficiently by increasing their activation, a process called priming. However, excessive activation can induce tissue injury and thereby, contribute to inflammatory disorders. Agonists that activate TLR7 and TLR8 induce priming of neutrophil ROS production; however, which receptor is involved in this process has not been elucidated. In this study, we show that the selective TLR8 agonist, CL075 (3M002), induced a dramatic increase of fMLF-stimulated NOX2 activation, whereas the selective TLR7 agonist, loxoribine, failed to induce any priming effect. Interestingly, CL075, but not loxoribine, induced the phosphorylation of the NOX2 cytosolic component p47phox on several serines and the phosphorylation of p38MAPK and ERK1/2. The inhibitor of p38MAPK completely blocked CL075-induced phosphorylation of p47phox Ser345. Moreover, CL075, but not loxoribine, induced the activation of the proline isomerase Pin1, and juglone, a Pin1 inhibitor, prevented CL075-mediated priming of fMLF-induced superoxide production. These results indicate that TLR8, but not TLR7, is involved in priming of human neutrophil ROS production by inducing the phosphorylation of p47phox and p38MAPK and that Pin1 is also involved in this process.

Reversal of Arthritis by Human Monomeric IgA Through the Receptor-Mediated SH2 Domain-Containing Phosphatase 1 Inhibitory Pathway.

OBJECTIVE: Rheumatoid arthritis (RA), one of the most frequent chronic inflammatory rheumatic disorders, is characterized by the presence of autoantibodies and joint infiltration by activated immune cells, leading to cartilage and bone destruction. IgA occurs predominantly as monomers (mIgA) in plasma and regulates many cell responses through interaction with the Fcα receptor type I (FcαRI). FcαRI targeting by anti-FcαRI Fab inhibits activating receptors by inducing an inhibitory immunoreceptor tyrosine-based activation motif (ITAMi) configuration through SH2 domain-containing phosphatase 1 (SHP-1) recruitment. The aim of this study was to investigate the potential utility of mIgA for the treatment of arthritis by acting as an inducer of ITAMi signaling. METHODS: The effect of plasma-derived human mIgA on inhibition of multiple heterologous receptors was evaluated on FcαRI+ cell transfectants, blood phagocytes from healthy individuals, and synovial cells from RA patients. FcαRI-transgenic mice and wild-type mice treated with mIgA were studied in models of collagen antibody-induced arthritis (CAIA) and collagen-induced arthritis (CIA). The mice were assessed for development of arthritis using an arthritis score, and joint tissue samples were evaluated for the extent of leukocyte infiltration and expression of phosphatase. RESULTS: Treatment with mIgA impaired cell activation in an FcαRI-FcRγ-dependent manner, involving ITAMi signaling. Human mIgA or anti-FcαRI Fab were strongly effective in either preventing or attenuating CAIA or CIA in FcαRI-transgenic mice. Administration of mIgA markedly inhibited the recruitment of leukocytes to the inflamed joints of mice, which was associated with induction of SHP-1 phosphorylation in joint tissue cells. Moreover, mIgA reversed the state of inflammation in the synovial fluid of RA patients by inducing an ITAMi configuration. CONCLUSION: These results demonstrate a therapeutic potential of human mIgA in experimental arthritis. The findings support future clinical exploration of mIgA for the treatment of RA.

Pulmonary manifestations in adult patients with chronic granulomatous disease.

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by failure of superoxide production in phagocytic cells. The disease is characterised by recurrent infections and inflammatory events, frequently affecting the lungs. Improvement of life expectancy now allows most patients to reach adulthood. We aimed to describe the pattern of pulmonary manifestations occurring during adulthood in CGD patients. This was a retrospective study of the French national cohort of adult patients (≥16 years old) with CGD. Medical data were obtained for 67 adult patients. Pulmonary manifestations affected two-thirds of adult patients. Their incidence was significantly higher than in childhood (mean annual rate 0.22 versus 0.07, p=0.01). Infectious risk persisted despite anti-infectious prophylaxis. Invasive fungal infections were frequent (0.11 per year per patient) and asymptomatic in 37% of the cases. They often required lung biopsy for diagnosis (10 out of 30). Noninfectious respiratory events concerned 28% of adult patients, frequently associated with a concomitant fungal infection (40%). They were more frequent in patients with the X-linked form of CGD. Immune-modulator therapies were required in most cases (70%). Respiratory manifestations are major complications of CGD in adulthood. Noninfectious pulmonary manifestations are as deleterious as infectious pneumonia. A specific respiratory monitoring is necessary.

Identification of secreted phosphoprotein 1 gene as a new rheumatoid arthritis susceptibility gene.

OBJECTIVE: To evaluate the contribution of the SPP1 rs11439060 and rs9138 polymorphisms, previously reported as autoimmune risk variants, in the rheumatoid arthritis (RA) genetic background according to anti-citrullinated protein antibodies (ACPAs) status of RA individuals. METHODS: We analysed a total of 11,715 RA cases and 26,493 controls from nine independent cohorts; all individuals were genotyped or had imputed genotypes for SPP1 rs11439060 and rs9138. The effect of the SPP1 rs11439060 and rs9138 risk-allele combination on osteopontin (OPN) expression in macrophages and OPN serum levels was investigated. RESULTS: We provide evidence for a distinct contribution of SPP1 to RA susceptibility according to ACPA status: the combination of ≥3 SPP1 rs11439060 and rs9138 common alleles was associated mainly with ACPA negativity (p=1.29×10(-5), ORACPA-negative 1.257 (1.135 to 1.394)) and less with ACPA positivity (p=0.0148, ORACPA-positive 1.072 (1.014 to 1.134)). The ORs between these subgroups (ie, ACPA-positive and ACPA-negative) significantly differed (p=7.33×10(-3)). Expression quantitative trait locus analysis revealed an association of the SPP1 risk-allele combination with decreased SPP1 expression in peripheral macrophages from 599 individuals. To corroborate these findings, we found an association of the SPP1 risk-allele combination and low serum level of secreted OPN (p=0.0157), as well as serum level of secreted OPN correlated positively with ACPA production (p=0.005; r=0.483). CONCLUSIONS: We demonstrate a significant contribution of the combination of SPP1 rs11439060 and rs9138 frequent alleles to risk of RA, the magnitude of the association being greater in patients negative for ACPAs.

Increased reactive oxygen species production and p47phox phosphorylation in neutrophils from myeloproliferative disorders patients with JAK2 (V617F) mutation.

Myeloproliferative disorders are associated with increased risk of thrombosis and vascular complications. The pathogenesis of these complications is not completely known. Reactive oxygen species produced by the neutrophil NADPH oxidase could have a role in this process. The aim of this study was to evaluate reactive oxygen species production by neutrophils of myeloproliferative disorder patients. Patients with or without the JAK2 V617F mutation were characterized. Reactive oxygen species production was assessed by chemiluminescence, and phosphorylation of the NADPH oxidase subunit p47phox was analyzed by Western blots. In a comparison of controls and myeloproliferative disorder patients without the JAK2 V617F mutation, reactive oxygen species production by neutrophils from patients with the JAK2 V617F mutation was dramatically increased in non-stimulated and in stimulated conditions. This increase was associated with increased phosphorylation of the p47phox on Ser345 and of the uspstream kinase ERK1/2. In neutrophils from healthy donors, JAK2 can be activated by GM-CSF. GM-CSF-induced p47phox phosphorylation and priming of reactive oxygen species production are inhibited by the selective JAK2 inhibitors AG490 and lestaurtinib (CEP-701), supporting a role for JAK2 in the upregulation of NADPH oxidase activation. These findings show an increase in reactive oxygen species production and p47phox phosphorylation in neutrophils from myeloproliferative disorder patients with the JAK2 V617F mutation, and demonstrate that JAK2 is involved in GM-CSF-induced NADPH oxidase hyperactivation. As neutrophil hyperactivation could be implicated in the thrombophilic status of patients with myeloproliferative disorders, aberrant activation of JAK2 V617F, leading to excessive neutrophil reactive oxygen species production might play a role in this setting.

Gene- and exon-expression profiling reveals an extensive LPS-induced response in immune cells in patients with cirrhosis.

BACKGROUND & AIMS: Lipopolysaccharide (LPS)-expressing bacteria cause severe inflammation in cirrhotic patients. The global gene response to LPS is unknown in cirrhotic immune cells. METHODS: Gene-expression profiling using Affymetrix Human Exon Array analyzed the expression of 14,851 genes in LPS-stimulated peripheral blood mononuclear cells (PBMCs) from 4 patients with cirrhosis and 4 healthy subjects. We performed validation studies using RT-qPCR in LPS-stimulated PBMCs from 52 patients and 9 healthy subjects and investigated the association of gene induction with mortality in 26 patients. RESULTS: Gene-expression profiling of LPS-stimulated cirrhotic cells showed 509 upregulated genes and 1588 downregulated genes. In LPS-stimulated "healthy" cells, 952 genes were upregulated and 838 genes downregulated. The 741 LPS-regulated genes shared by cirrhotic and "healthy" cells were involved in cytokine production/activity and induction of "immune paralysis". Comparison of functions associated with the 1356 genes, specifically regulated by LPS in cirrhotic cells, to functions of the 1049 genes, specifically regulated in "healthy" cells, allowed to define a cirrhosis-specific phenotype. Unlike in "healthy" cells, LPS failed to induce an interferon-mediated program in cirrhotic cells. In cirrhotic PBMCs, LPS specifically induced certain molecules involved in apoptosis and downregulated molecules involved in endocytic trafficking. RT-qPCR experiments showed that LPS-stimulated cirrhotic PBMCs had an enhanced induction of certain proinflammatory cytokines and chemokines. In the prognosis study, higher ex vivo LPS-induction of the inflammatory genes IL6 and CXCL5 was a significant predictor of mortality. CONCLUSIONS: Our results show that LPS-stimulated cirrhotic PBMCs exhibit an extensive and often unexpected transcriptional response.