Interaktion von Listeria monocytogenes mit dem humanen Immunsystem

Das Bakterium Listeria monocytogenes kann in immunsupprimierten Personen sowie, in der Schwangerschaft, beim ungeborenen Kind, die lebensbedrohende Listeriose hervorrufen. Experimente in der Maus haben gezeigt, daß Listerien im Wirt einen intrazellulären Infektionszyklus durchlaufen, wodurch sie vor Antikörpern geschützt sind. Für eine erfolgreiche Bekämpfung des Erregers sind in diesem Modell zelluläre Abwehrmechnismen verantwortlich. Die vorliegende Arbeit war in drei Teile gegliedert, in denen Aspekte der Interaktion von Listeria monocytogenes mit dem humanen Immunsystem bearbeitet wurden: die spezifische humorale Immunantwort, die Interaktion mit der Antigen-Prozessierung und die Induktion CD1-restringierter DN T-Zellen. Die humorale Immunantwort gesunder Spender mit Kontakt zu Listerien wurde mit der in Listeriose-Patienten verglichen. Im Serum gesunder Personen wurden hauptsächlich Antikörper gegen zwei sekretierte Virulenzfaktoren, Listeriolysin O (LLO) und Internalin-related Protein A (IrpA) gefunden. Listeriose-Patienten besaßen darüberhinaus Antikörper gegen membrangebundene Virulenzfaktoren. In der Maus ist L. monocytogenes in der Lage, mit Hilfe des Virulenzfaktors LLO die Antigen-Präsentation in einer Weise zu verändern, die zu einer gezielten Inaktivierung spezifischer CD4-T-Zellen führt. Im Human-System zeigten sich deutliche Unterschiede zum Mausmodell. So stört LLO im Menschen zwar generell die Antigen-Prozessierung durch bestimmte APC (PBMC und Monozyten), Hinweise auf eine gezielte Inaktivierung spezifischer CD4+ T-Zellen wurden jedoch nicht gefunden. Darüberhinaus erwiesen sich humane dendritische Zellen als überaus resistent gegen die Störung der Antigen-Prozessierung durch LLO oder lebende Listerien und präsentierten sowohl exogene als auch durch L. m. im Phagosom produzierte Proteine in normaler Weise. Die Resistenz dieser APC, die eine zentrale Position in der Stimulation spezifischer T-Zellen bei Infektionen einnehmen, könnte eThe intracellular pathogen Listeria monocytogenes causes listeriosis, a life-threatening disease particularly dangerous for immunocompromised persons as well as the unborn child. Experiments in the mouse model have shown that listeria follow an intracellular infection cycle, thus being protected from specific antibodies. For successful clearance of the infection, cellular immune mechanisms are necessary. The work presented here is divided into three parts dealing with aspects of the interaction of L. monocytogenes with the human immune system: the specific humoral response, the interaction with antigen processing, and the induction of CD1-restricted DN T cells. The humoral immune response of healthy individuals with suspected contact to Listeria and Listeriosis patients were compared. In sera of healthy donors antibodies specific for two secreted virulence factors, Listeriolysin O (LLO) and Internalin-related protein A (IrpA) were detected. Additionally, in Listeriosis patients antibodies specific for membrance-bound virulence factors were found. In mice, the virulence factor LLO interferes with antigen presentation in a way that leads to inactivation of Listeria-specific CD4 T cells. In the human system, though, major differences to the experimental mouse model were found. Although LLO generally inhibits the antigen processing by certain APC (PBMC and monocytes) this did not lead to Antigen-specific inactivation of CD4 T cells. Furthermore, the antigen presentation by dendritic cells was not inhibited by LLO or live L. monocytogenes. Both exogenous proteins and proteins produced by Listeria inside the phagosome were normally presented. As dendritic cells play a central role in the stimulation of specific T cells, their resistance to the inhibitory effects of LLO might be one reason why healthy individuals are relatively safe from listerial infections. Finally, the role of CD1-restricted DN T cells during the immune response against L. monocytogenes

Ets-1, a functional cofactor of T-bet, is essential for Th1 inflammatory responses

To mount an effective type 1 immune response, type 1 T helper (Th1) cells must produce inflammatory cytokines and simultaneously suppress the expression of antiinflammatory cytokines. How these two processes are coordinately regulated at the molecular level is still unclear. In this paper, we show that the proto-oncogene E26 transformation–specific-1 (Ets-1) is necessary for T-bet to promote interferon-γ production and that Ets-1 is essential for mounting effective Th1 inflammatory responses in vivo. In addition, Ets-1–deficient Th1 cells also produce a very high level of interleukin 10. Thus, Ets-1 plays a crucial and unique role in the reciprocal regulation of inflammatory and antiinflammatory Th responses

Ets-1 is a negative regulator of Th17 differentiation

IL-17 is a proinflammatory cytokine that plays a role in the clearance of extracellular bacteria and contributes to the pathology of many autoimmune and allergic conditions. IL-17 is produced mainly by a newly characterized subset of T helper (Th) cells termed Th17. Although the role of Th17 cells in the pathology of autoimmune diseases is well established, the transcription factors regulating the differentiation of Th17 cells remain poorly characterized. We report that Ets-1–deficient Th cells differentiated more efficiently to Th17 cells than wild-type cells. This was attributed to both low IL-2 production and increased resistance to the inhibitory effect of IL-2 on Th17 differentiation. The resistance to IL-2 suppression was caused by a defect downstream of STAT5 phosphorylation, but was not caused by a difference in the level of RORγt. Furthermore, Ets-1–deficient mice contained an abnormally high level of IL-17 transcripts in their lungs and exhibited increased mucus production by airway epithelial cells in an IL-17–dependent manner. Based on these observations, we report that Ets-1 is a negative regulator of Th17 differentiation

a randomized double blind placebo controlled phase 1 study of multiple ascending doses of subcutaneous m1095 an anti interleukin 17a f nanobody in moderate to severe psoriasis

Background Interleukin 17 is involved in the pathogenesis of psoriasis, a chronic debilitating disease. Objectives To evaluate the safety/tolerability, immunogenicity, pharmacokinetics/pharmacodynamics, and efficacy of M1095, an anti–interleukin 17A/F nanobody, in moderate-to-severe plaque psoriasis. Methods This multicenter, double-blind, placebo-controlled dose escalation phase 1 study randomized 44 patients 4:1 to treatment with subcutaneous M1095 (30, 60, 120, or 240 mg) or placebo biweekly for 6 weeks, in 4 ascending dose cohorts. Results The most frequent treatment-emergent adverse events with M1095 were pruritus (n = 4) and headache (n = 3); 2 patients withdrew owing to adverse events (injection site reaction and elevated liver enzyme levels). The terminal half-life of M1095 was 11 to 12 days. The area under the curve/maximum concentration was dose proportional. Of 10 M1095-treated patients positive for antidrug antibodies, 5 showed treatment-emergent antidrug antibody responses. There was no effect on M1095 exposure. Marked decreases in psoriasis inflammatory markers were observed with M1095. By day 85, 100% and 56% of patients receiving M1095, 240 mg, achieved psoriasis area and severity index 90 and 100, respectively. Improvements in static Physician's Global Assessment and affected body surface area were also seen. Limitations Interpretation of efficacy data is limited by the small sample size. Conclusion Multiple subcutaneous doses of M1095 showed a favorable safety profile with dose-dependent improvements in psoriasis

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

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Efficient Recruitment of Lymphocytes in Inflamed Brain Venules Requires Expression of Cutaneous Lymphocyte Antigen and Fucosyltransferase-VII

Abstract Lymphocyte migration into the brain represents a critical event in the pathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). However, the mechanisms controlling the recruitment of lymphocytes to the CNS via inflamed brain venules are poorly understood, and therapeutic approaches to inhibit this process are consequently few. In this study, we demonstrate for the first time that human and murine Th1 lymphocytes preferentially adhere to murine inflamed brain venules in an experimental model that mimics early inflammation during EAE. A virtually complete inhibition of rolling and arrest of Th1 cells in inflamed brain venules was observed with a blocking anti-P-selectin glycoprotein ligand 1 Ab and anti-E- and P-selectin Abs. Th1 lymphocytes produced from fucosyltransferase (FucT)-IV−/− mice efficiently tethered and rolled, whereas in contrast, primary adhesion of Th1 lymphocytes obtained from FucT-VII−/− or Fuc-VII−/−FucT-IV−/− mice was drastically reduced, indicating that FucT-VII is critical for the recruitment of Th1 cells in inflamed brain microcirculation. Importantly, we show that Abs directed against cutaneous lymphocyte Ag (CLA), a FucT-VII-dependent carbohydrate modification of P-selectin glycoprotein ligand 1, blocked rolling of Th1 cells. By exploiting a system that allowed us to obtain Th1 and Th2 cells with skin- vs gut-homing (CLA+ vs integrin β7+) phenotypes, we observed that induced expression of CLA on Th cells determined a striking increase of rolling efficiency in inflamed brain venules. These observations allow us to conclude that efficient recruitment of activated lymphocytes to the brain in the contexts mimicking EAE is controlled by FucT-VII and its cognate cell surface Ag CLA

Btk inhibition treats TLR7/IFN driven murine lupus.

ABSTRACTBruton's tyrosine kinase (Btk) is expressed in a variety of immune cells and previous work has demonstrated that blocking Btk is a promising strategy for treating autoimmune diseases. Herein, we utilized a tool Btk inhibitor, M7583, to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon. In BXSB-Yaa lupus mice, Btk inhibition reduced autoantibodies, nephritis, and mortality. In the pristane-induced DBA/1 lupus model, Btk inhibition suppressed arthritis, but autoantibodies and the IFN gene signature were not significantly affected; suggesting efficacy was mediated through inhibition of Fc receptors. In vitro studies using primary human macrophages revealed that Btk inhibition can block activation by immune complexes and TLR7 which contributes to tissue damage in SLE. Overall, our results provide translational insight into how Btk inhibition may provide benefit to a variety of SLE patients by affecting both BCR and FcR signaling

The transcription factor Ets1 is important for CD4 repression and Runx3 up-regulation during CD8 T cell differentiation in the thymus

The transcription factor Ets1 contributes to the differentiation of CD8 lineage cells in the thymus, but how it does so is not understood. In this study, we demonstrate that Ets1 is required for the proper termination of CD4 expression during the differentiation of major histocompatability class 1 (MHC I)–restricted thymocytes, but not for other events associated with their positive selection, including the initiation of cytotoxic gene expression, corticomedullary migration, or thymus exit. We further show that Ets1 promotes expression of Runx3, a transcription factor important for CD8 T cell differentiation and the cessation of Cd4 gene expression. Enforced Runx3 expression in Ets1-deficient MHC I–restricted thymocytes largely rescued their impaired Cd4 silencing, indicating that Ets1 is not required for Runx3 function. Finally, we document that Ets1 binds at least two evolutionarily conserved regions within the Runx3 gene in vivo, supporting the possibility that Ets1 directly contributes to Runx3 transcription. These findings identify Ets1 as a key player during CD8 lineage differentiation and indicate that it acts, at least in part, by promoting Runx3 expression

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

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