Kostimulatorische Rezeptoren in der Aktivierung humaner neutrophiler Granulozyten

Neutrophile Granulozyten spielen eine wichtige Rolle in der ersten Phase der Inflammation. Sie infiltrieren den Infektionsort um den eingedrungenen Erreger zu bekämpfen und Ihre Effektor Funktion auszuführen. Neben den Mustererkennenden Rezeptoren des angeborenen Immunsystems (pattern recognition receptors) werden weitere Rezeptoren auf der Oberfläche von neutrophilen Granulozyten exprimiert, welche zur Aktivierung der Zelle beitragen können. In dieser arbeit wurden der Herpes Virus Entry Mediator (HVEM) und Triggering Receptor expressed on Myeloid Cells-1 (TREM-1) auf neutrophilen untersucht. Für HVEM konnte eine synergistische Aktivierung von neutrophilen Granulozyten im Zusammenspiel mit Toll like Rezeptor (TLR) Liganden nachgewiesen werden. Für TREM-1 konnte ein Vorhandensein eines Liganden auch Thrombozyten beschrieben. Es wurden weiterhin Mechanismen untersucht und beschrieben, welche für die synergistische Aktivierung von neutrophilen Granulozyten verantwortlich sind, welche nach TREM-1 und TLR Stimulation erkennbar ist.Polymorphnuclear neutrophil granulocytes (PMN) are of importance in the first line of defense in the inflammatory response. They infiltrate the side of infection and exert their Effektor function against pathogens. Beside the pattern recognition receptors of the innate immun system PMN also express receptors on their surface which contributes to the activation of PMN. Examined were the Herpes Virus Entry Mediator (HVEM) and Triggering Receptor Expressed on Myeloid cells 1 (TREM-1). Stimulation of HVEM was co stimulatory in the activation of PMN together with Toll like Receptor (TLR) ligands. A TREM-1 ligand was described to be expressed on platelets and mechanisms for the synergy in activation of PMN after TREM-1 and TLR stimulation could be described

216 Inhibition of brutons tyrosine kinase (BTK) prevents inflammatory macrophage differentiation: a potential role in SLE

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Soluble Triggering Receptor Expressed on Myeloid Cells 1 Is Released in Patients with Stable Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is increasingly recognized as a systemic disease that is associated with increased serum levels of markers of systemic inflammation. The triggering receptor expressed on myeloid cells 1 (TREM-1) is a recently identified activating receptor on neutrophils, monocytes, and macrophage subsets. TREM-1 expression is upregulated by microbial products such as the toll-like receptor ligand lipoteichoic acid of Gram-positive or lipopolysaccharides of Gram-negative bacteria. In the present study, sera from 12 COPD patients (GOLD stages I–IV, FEV1 51 ± 6%) and 10 healthy individuals were retrospectively analyzed for soluble TREM-1 (sTREM-1) using a newly developed ELISA. In healthy subjects, sTREM-1 levels were low (median 0.25 ng/mL, range 0–5.9 ng/mL). In contrast, levels of sTREM-1 in sera of COPD patients were significantly increased (median 11.68 ng/mL, range 6.2–41.9 ng/mL, P<.05). Furthermore, serum levels of sTREM-1 showed a significant negative correlation with lung function impairment. In summary, serum concentrations of sTREM-1 are increased in patients with COPD. Prospective studies are warranted to evaluate the relevance of sTREM-1 as a potential marker of the disease in patients with COPD

211 Identifying lupus patient subsets and specific pharmacodynamic changes through immune cell deconvolution of gene expression data in atacicept-treated patients in the APRIL-SLE study

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O37 M5049, a novel potent and selective inhibitor of toll-like receptors 7 and 8 (TLR 7/8)

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Kostimulatorische Rezeptoren in der Aktivierung humaner neutrophiler Granulozyten

Neutrophile Granulozyten spielen eine wichtige Rolle in der ersten Phase der Inflammation. Sie infiltrieren den Infektionsort um den eingedrungenen Erreger zu bekämpfen und Ihre Effektor Funktion auszuführen. Neben den Mustererkennenden Rezeptoren des angeborenen Immunsystems (pattern recognition receptors) werden weitere Rezeptoren auf der Oberfläche von neutrophilen Granulozyten exprimiert, welche zur Aktivierung der Zelle beitragen können. In dieser arbeit wurden der Herpes Virus Entry Mediator (HVEM) und Triggering Receptor expressed on Myeloid Cells-1 (TREM-1) auf neutrophilen untersucht. Für HVEM konnte eine synergistische Aktivierung von neutrophilen Granulozyten im Zusammenspiel mit Toll like Rezeptor (TLR) Liganden nachgewiesen werden. Für TREM-1 konnte ein Vorhandensein eines Liganden auch Thrombozyten beschrieben. Es wurden weiterhin Mechanismen untersucht und beschrieben, welche für die synergistische Aktivierung von neutrophilen Granulozyten verantwortlich sind, welche nach TREM-1 und TLR Stimulation erkennbar ist.Polymorphnuclear neutrophil granulocytes (PMN) are of importance in the first line of defense in the inflammatory response. They infiltrate the side of infection and exert their Effektor function against pathogens. Beside the pattern recognition receptors of the innate immun system PMN also express receptors on their surface which contributes to the activation of PMN. Examined were the Herpes Virus Entry Mediator (HVEM) and Triggering Receptor Expressed on Myeloid cells 1 (TREM-1). Stimulation of HVEM was co stimulatory in the activation of PMN together with Toll like Receptor (TLR) ligands. A TREM-1 ligand was described to be expressed on platelets and mechanisms for the synergy in activation of PMN after TREM-1 and TLR stimulation could be described

An Essential Role for ras in LPS Mediated Amplification of TREM-1 Induced Neutrophil Activation.

Abstract The triggering receptor expressed on myeloid cells 1 (TREM-1) is constitutively expressed on polymorphonuclear neutrophils (PMN), monocytes and macrophage subsets and has been recently identified as an important player in the innate inflammatory response to microbial infections and sepsis. Expression of TREM-1 and activation of PMN and monocytes is regulated in concert with microbial products via the recognition of Toll-like receptor (TLR) ligands such as bacterial lipopolysaccaride (LPS). However, it is currently unclear how the amplification of the inflammatory responses by TREM-1 and TLR agonists is mediated on an intracellular level. To this end, we were interested to identify signalling events leading to the synergistic activation of PMN upon TREM-1 and TLR ligation. Using pharmacologic inhibitors and western blot analyses we demonstrate that PI3 kinase, PLC-g and p38 MAP kinase are essential for the initiation of the respirator burst as an important and immediate effector mechanism of human PMN. Furthermore, the phosphorylation of PKB/Akt and MAP kinase ERK show a biphasic pattern upon TREM-1/TLR4 coligation indicating distinct activation mechanisms for these receptors. Interestingly, the TLR4, but not TREM-1 mediated respiratory burst was dependent on the activation of ras leading downstream to an augmented calcium flow and subsequently synergistic burst activity. Taken together, we provide a new mechanism how TREM-1 and TLR interact in PMN mediating enhanced activation. These results shed a new light on our understanding how the innate inflammatory responses are regulated and might contribute to the development of future concept for the treatment of a dysregulated immune response in severe inflammatory conditions such as sepsis.</jats:p

Mechanisms of Synergy Between Toll-Like Receptor 4 and Triggering Receptor Expressed on Myeloid Cells-1 in Human Neutrophils

Abstract The triggering receptor expressed on myeloid cells 1 (TREM-1) is an important player in the innate inflammatory response to microbial infections. Activation and expression of TREM-1 by polymorphonuclear neutrophils (PMN) occurs in concert with Toll-like receptors (TLR) such as TLR4 for bacterial lipopolysaccharide. However, it is currently unclear how this is mediated on a molecular level. Using pharmacologic inhibitors and western blot analysis we demonstrate that phosphatidyl inositide 3-kinase, phospholipase C and the mitogen activated kinase p38 are essential for the TREM-1 and TLR4 mediated respiratory burst of human PMN. The down stream phosphorylation of protein kinase B and extracellular signal related kinase show characteristic phosphorylation patterns upon single or co-ligation indicating individual activation pathways of both receptors. TREM-1, but not TLR4 mediated respiratory burst depended on calcium flow via store operated calcium entry channels, while transient receptor potential channels were important for TLR and TREM-1. Taken together, we provide new insights on the mechanisms how TREM-1 and TLR interact creating synergistic activation in PMN. These results shed a new light on our understanding how the innate inflammatory responses are regulated and might contribute to the development of future concepts for the treatment of severe inflammatory conditions such as sepsis.</jats:p

Inhibition of Bruton’s tyrosine kinase interferes with pathogenic B-cell development in inflammatory CNS demyelinating disease

Abstract Anti-CD20-mediated B-cell depletion effectively reduces acute multiple sclerosis (MS) flares. Recent data shows that antibody-mediated extinction of B cells as a lasting immune suppression, harbors the risk of developing humoral deficiencies over time. Accordingly, more selective, durable and reversible B-cell-directed MS therapies are needed. We here tested inhibition of Bruton’s tyrosine kinase (BTK), an enzyme centrally involved in B-cell receptor signaling, as the most promising approach in this direction. Using mouse models of MS, we determined that evobrutinib, the first BTK inhibiting molecule being developed, dose-dependently inhibited antigen-triggered activation and maturation of B cells as well as their release of pro-inflammatory cytokines. Most importantly, evobrutinib treatment functionally impaired the capacity of B cells to act as antigen-presenting cells for the development of encephalitogenic T cells, resulting in a significantly reduced disease severity in mice. In contrast to anti-CD20, BTK inhibition silenced this key property of B cells in MS without impairing their frequency or functional integrity. In conjunction with a recent phase II trial reporting that evobrutinib is safe and effective in MS, our mechanistic data highlight therapeutic BTK inhibition as a landmark towards selectively interfering with MS-driving B-cell properties.EMD Serono http://dx.doi.org/10.13039/10000475

Inhibition of Bruton’s tyrosine kinase interferes with pathogenic B-cell development in inflammatory CNS demyelinating disease

AbstractAnti-CD20-mediated B-cell depletion effectively reduces acute multiple sclerosis (MS) flares. Recent data shows that antibody-mediated extinction of B cells as a lasting immune suppression, harbors the risk of developing humoral deficiencies over time. Accordingly, more selective, durable and reversible B-cell-directed MS therapies are needed. We here tested inhibition of Bruton’s tyrosine kinase (BTK), an enzyme centrally involved in B-cell receptor signaling, as the most promising approach in this direction. Using mouse models of MS, we determined that evobrutinib, the first BTK inhibiting molecule being developed, dose-dependently inhibited antigen-triggered activation and maturation of B cells as well as their release of pro-inflammatory cytokines. Most importantly, evobrutinib treatment functionally impaired the capacity of B cells to act as antigen-presenting cells for the development of encephalitogenic T cells, resulting in a significantly reduced disease severity in mice. In contrast to anti-CD20, BTK inhibition silenced this key property of B cells in MS without impairing their frequency or functional integrity. In conjunction with a recent phase II trial reporting that evobrutinib is safe and effective in MS, our mechanistic data highlight therapeutic BTK inhibition as a landmark towards selectively interfering with MS-driving B-cell properties.</jats:p