Extension of the Color Glass Condensate Approach to Diffractive Reactions

We present an evolution equation for the Bjorken x dependence of diffractive dissociation on hadrons and nuclei at high energies. We extend the formulation of Kovchegov and Levin by relaxing the factorization assumption used there. The formulation is based on a technique used by Weigert to describe interjet energy flow. The method can be naturally extended to other exclusive observables

Generierung von Sphingosin-1-Phosphat durch apoptotische Zellen und dessen Einfluss auf die Polarisierung von Makrophagen während der Tumorentwicklung

The removal of apoptotic cells (AC) can be regarded as an integral component of the program to terminate inflammation. Clearance of AC by professional phagocytes such as macrophages induces an anti-inflammatory phenotype in the latter ones. Anti-inflammatory or M2 polarization is also observed in macrophages infiltrating certain human tumors. These tumor-associated macrophages (TAM) contribute actively to tumor progression by promoting immune evasion, angiogenesis and tumor cell survival. The aim of my Ph.D. thesis was to approach the mechanisms as well as the characteristics of macrophage phenotype alterations induced by AC, and to elucidate a possible connection between tumor cell apoptosis and TAM generation. In the first part of my studies, I investigated the impact of AC on macrophage viability. I could show that macrophage survival against pro-apoptotic agents increased after the interaction with AC. Protection of macrophages against cell death required activation of phosphatidylinositol-3 kinase (PI3K), extracellular signal-regulated kinase 1/2 (ERK1/2) and Ca2+ signaling, and correlated with Bcl-XL and Bcl-2 up-regulation as well as Ser136-Bad phosphorylation. Unexpectedly, neither phagocytosis nor binding of apoptotic debris to the phagocyte was necessary to induce protection. AC released the bioactive lipid sphingosine-1-phosphate (S1P), dependent on sphingosine kinase (SphK) 2, as a survival messenger. These data indicated an active role of AC in preventing cell destruction in their neighborhood. My next aim was to elucidate the mechanism of S1P production by AC. During cell death, SphK 2 was cleaved at its N-terminus by caspase-1. Thereupon, the truncated but enzymatically active fragment of SphK 2 was released from cells. This release was coupled to phosphatidylserine exposure, a hallmark of apoptosis and a crucial signal for the phagocyte/apoptotic cell interaction. Thus, I observed a link between common signaling events during apoptosis and the extracellular production of S1P, which is known to affect immune cell attraction and polarization as well as angiogenesis in cancer. In the next part of my studies, I asked for a correlation between tumor cell apoptosis and TAM polarization. During co-culture of human macrophages with human breast cancer carcinoma cells (MCF-7), the latter ones were killed, while macrophages acquired an alternatively activated phenotype. This was characterized by decreased tumor necrosis factor (TNF)-α; and interleukin (IL)-12-p70 production, but increased formation of IL-8 and IL-10. Alternative macrophage activation required tumor cell death, because a co-culture with apoptosis-resistant colon carcinoma cells (RKO) or Bcl-2-overexpressing MCF-7 cells failed to induce phenotype alterations. These phenotype alterations were also achieved with conditioned media from apoptotic tumor cells, which again argued for a soluble factor being involved. Knock-down of SphK2, but not SphK1, to attenuate S1P formation in MCF-7 cells, repressed the otherwise observed alternative macrophage polarization during co-culture. Furthermore, macrophage polarization achieved by tumor cell apoptosis or substitution of authentic S1P was characterized by suppression of pro-inflammatory nuclear factor (NF)-κB DNA binding. These findings suggested that tumor cell apoptosis-derived S1P contributes to the macrophage polarization present in human tumors. To validate these in vitro data, I used an in vivo tumor model to clarify the relevance of SphK2 and S1P in tumor development. The growth of, as well as blood vessel infiltration into SphK2 knock-down MCF-7 (MCF-7-siSphK2) xenografts in nude mice was markedly decreased in comparison to control MCF-7 xenografts. In contrast, macrophage infiltration was similar or even more pronounced. These data provided a first hint for an in vivo role of SphK2-derived S1P in macrophage polarization associated with tumor promotion. In summary, these data indicate a new mechanism how AC themselves shape macrophage polarization, which results in the termination of inflammatory responses and macrophage survival. Furthermore, my studies present evidence that human tumors may utilize this mechanism to foster growth via increased angiogenesis.Die Phagozytose apoptotischer Zellen (AZ) kann als ein integraler Bestandteil des Mechanismus zur Beendigung von Entzündungsreaktionen angesehen werden. Die Beseitigung von AZ induziert einen anti-inflammatorischen Phänotyp in Makrophagen. Ein ähnlicher Phänotyp (M2) ist auch für Makrophagen beschrieben, die in humane Tumore infiltrieren. Diese Tumor- assoziierten Makrophagen (TAM) tragen aktiv zur Tumorprogression bei, indem sie die Gefäßbildung und das Überleben von Tumorzellen fördern, aber auch das körpereigene Immunsystem ausschalten. Das Ziel meiner Doktorarbeit war es, die Mechanismen und Charakteristika der Makrophagenpolarisierung durch AZ besser zu verstehen, und eine mögliche Verbindung von Tumorzell-Apoptose und der Ausprägung des TAM-Phänotyps aufzuzeigen. Im ersten Teil meiner Studien untersuchte ich den Einfluss von AZ auf die Überlebensfähigkeit von Makrophagen. Diese war nach der Interaktion mit AZ erhöht. Der Schutz vor Zelltod benötigte die Aktivierung der Phosphatidylinositol-3 Kinase (PI3K), der Mitogen-aktivierten Proteinkinasen ERK1/2, sowie Calcium-Signale, und korrelierte mit vermehrter Expression von Bcl-2 und Bcl-XL, sowie mit Phosphorylierung von Bad an Ser136. Interessanterweise war der Schutzeffekt unabhängig von Phagozytose oder direkter Interaktion zwischen Makrophagen und AZ, sondern vielmehr von der Freisetzung des bioaktiven Lipids Sphingosin-1-Phosphat (S1P) aus AZ, generiert durch die Sphingosinkinase (SphK) 2. Mein nächstes Ziel war es den dafür verantwortlichen Mechanismus aufzuzeigen. Während des Zelltods fand eine Spaltung der SphK2 durch die Caspase-1 an deren N-Terminus statt, woraufhin ein enzymatisch aktives Fragment aus den AZ freigesetzt wurde. Diese Freisetzung war eng an die Exposition von Phosphatidylserin gekoppelt, welche ein Kennzeichen von Apoptose, und ein wichtiges Signal bei der Interaktion von Makrophagen und AZ ist. Somit konnte ich eine Verknüpfung zwischen allgemeinen Signalwegen der Apoptose und der extrazellulären Produktion von S1P nachweisen. Von letzterem ist bekannt, dass es sowohl die Polarisierung und das Anlocken von Immunzellen, als auch die Gefäßbildung im Tumor beeinflussen kann. Im nachfolgenden Teil meiner Studien untersuchte ich eine mögliche Verbindung zwischen Tumorzell-Apoptose und der TAM- Polarisierung. In einer Ko-Kultur von menschlichen Makrophagen mit MCF-7 Brustkrebszellen wurden letztere getötet, woraufhin die Makrophagen einen alternativ aktivierten Phänotyp annahmen. Dieser war durch verminderte Produktion des Tumor-Nekrose-Faktors (TNF)-α; und des Interleukins (IL)-12p70 sowie durch erhöhte Freisetzung der Interleukine 8 und 10 charakterisiert. Die alternative Aktivierung der Makrophagen in den Ko-Kulturen war Tumorzelltod-abhängig, da Apoptose-resistente Darmkrebszellen (RKO) oder Bcl-2 überexprimierende MCF-7 Zellen diese nicht auslösten. Dies war jedoch mit Zellkulturüberständen von apoptotischen Tumorzellen der Fall, was wiederum auf einen löslichen Faktor hindeutete. Das Ausschalten der SphK2, nicht jedoch der SphK1, was die S1P- Freisetzung von MCF-7 Zellen unterband, verhinderte die alternative Aktivierung von Makrophagen in den Ko-Kulturen. Ein weiteres Charakteristikum der Makrophagenpolarisierung durch apoptotische Tumorzellen und S1P war die Hemmung der DNA-Bindung des entzündungsfördernden Transkriptionsfaktors NF-κB. Um die Relevanz der SphK2 und von S1P in der Tumorentwicklung genauer zu untersuchen, führte ich ein in vivo Tumormodell durch. Tumorzell-Implantate von SphK2-defizienten MCF-7 Zellen in Nacktmäusen wiesen sowohl deutlich reduziertes Wachstum, als auch Blutgefäßbildung, im Vergleich zu Kontrollimplantaten (MCF-7) auf. Die Einwanderung von Makrophagen war jedoch nicht vermindert, sondern eher erhöht. Diese Daten lieferten einen ersten Hinweis auf eine Rolle von SphK2-abhängig freigesetztem S1P in der Makrophagenpolarisierung, in Verbindung mit einer Förderung der Tumorentwicklung. Zusammengefasst deuten meine Daten auf einen neuen Mechanismus hin, wie AZ die Makrophagenpolarisierung gestalten. Dieser Prozess resultiert letztlich in der Beendigung von Entzündungsreaktionen und erhöhter Überlebensfähigkeit von Makrophagen. Weiterhin weisen meine Studien darauf hin, dass Tumore eventuell diesen Mechanismus nutzen, um ihr Wachstum durch vermehrte Gefäßbildung zu sichern

Management of chronic immune thrombocytopenic purpura: targeting insufficient megakaryopoiesis as a novel therapeutic principle

Traditionally, anti-platelet autoantibodies accelerating platelet clearance from the peripheral circulation have been recognized as the primary pathopysiological mechanism in chronic immune thrombocytopenia (ITP). Recently, increasing evidence supports the co-existence of insufficient megakaryopoiesis. Inadequate low thrombopoietin (TPO) levels are associated with insufficient proliferation and differentiation of megakaryocytes, decreased proplatelet formation, and subsequent platelet release. Recently two novel activators of TPO receptors have been made available: romiplostim and eltrombopag. In several phase III studies, both agents demonstrated increase of platelet counts in about 80% of chronic ITP patients within 2 to 3 weeks. These agents substantially broaden the therapeutic options for patients with chronic ITP although long-term results are still pending. This review will provide an update on the current conception of underlying mechanisms in ITP and novel, pathophysiologically based treatment options

Plasma levels of leptin, omentin, collagenous repeat-containing sequence of 26-kDa protein (CORS-26) and adiponectin before and after oral glucose uptake in slim adults

BACKGROUND: Adipose tissue secreted proteins are collectively named adipocytokines and include leptin, adiponectin, resistin, collagenous repeat-containing sequence of 26-kDa protein (CORS-26) and omentin. Several of these adipocytokines influence insulin sensitivity and glucose metabolism and therefore systemic levels may be affected by oral glucose uptake. Whereas contradictory results have been published for leptin and adiponectin, resistin has not been extensively investigated and no reports on omentin and CORS-26 do exist. METHODS: Therefore the plasma levels of these proteins before and 120 min after an oral glucose load were analyzed in 20 highly-insulin sensitive, young adults by ELISA or immunoblot. RESULTS: Circulating leptin was reduced 2 h after glucose uptake whereas adiponectin and resistin levels are not changed. Distribution of adiponectin and CORS-26 isoforms were similar before and after glucose ingestion. Omentin is highly abundant in plasma and immunoblot analysis revealed no alterations when plasma levels before and 2 h after glucose intake were compared. CONCLUSION: Taken together our data indicate that only leptin is reduced by glucose uptake in insulin-sensitive probands whereas adiponectin and resistin are not altered. CORS-26 was demonstrated for the first time to circulate as high molecular weight form in plasma and like omentin was not influenced by oral glucose load. Omentin was shown to enhance insulin-stimulated glucose uptake but systemic levels are not correlated to postprandial blood glucose

iNOS expressing macrophages co-localize with nitrotyrosine staining after myocardial infarction in humans

IntroductionInducible nitric oxide synthase (iNOS) produces micromolar amounts of nitric oxide (NO) upon the right stimuli, whose further reactions can lead to oxidative stress. In murine models of myocardial infarction (MI), iNOS is known to be expressed in infiltrating macrophages, which at early onset enter the infarcted zone and are associated with inflammation. In contrast cardiac tissue resident macrophages are thought to enhance regeneration of tissue injury and re-establish homeostasis. Both detrimental and beneficial effects of iNOS have been described, still the role of iNOS in MI is not fully understood. Our aim was to examine cell expression patterns of iNOS and nitrotyrosine (NT) production in human MI.Material and MethodsWe examined in postmortem human MI hearts the iNOS mRNA expression by means of qPCR. Further we performed immunohistochemical stainings for cell type identification. Afterwards a distance analysis between iNOS and NT was carried out to determine causality between iNOS and NT production.ResultsiNOS mRNA expression was significantly increased in infarcted regions of human MI hearts and iNOS protein expression was detected in resident macrophages in infarcted human hearts as well as in controls hearts, being higher in resident macrophages in MI hearts compared to control. Furthermore in MI and in healthy human hearts cells showing signs of NT production peaked within 10–15 µm proximity of iNOS+ cells.DiscussionThese results indicate that, unexpectedly, resident macrophages are the main source of iNOS expression in postmortem human MI hearts. The peak of NT positive cells within 10–15 µm of iNOS+ cells suggest an iNOS dependent level of NT and therefore iNOS dependent oxidative stress. Our results contribute to understanding the role of iNOS in human MI

PPARγ1 attenuates cytosol to membrane translocation of PKCα to desensitize monocytes/macrophages

Recently, we provided evidence that PKCα depletion in monocytes/macrophages contributes to cellular desensitization during sepsis. We demonstrate that peroxisome proliferator–activated receptor γ (PPARγ) agonists dose dependently block PKCα depletion in response to the diacylglycerol homologue PMA in RAW 264.7 and human monocyte–derived macrophages. In these cells, we observed PPARγ-dependent inhibition of nuclear factor-κB (NF-κB) activation and TNF-α expression in response to PMA. Elucidating the underlying mechanism, we found PPARγ1 expression not only in the nucleus but also in the cytoplasm. Activation of PPARγ1 wild type, but not an agonist-binding mutant of PPARγ1, attenuated PMA-mediated PKCα cytosol to membrane translocation. Coimmunoprecipitation assays pointed to a protein–protein interaction of PKCα and PPARγ1, which was further substantiated using a mammalian two-hybrid system. Applying PPARγ1 mutation and deletion constructs, we identified the hinge helix 1 domain of PPARγ1 that is responsible for PKCα binding. Therefore, we conclude that PPARγ1-dependent inhibition of PKCα translocation implies a new model of macrophage desensitization

Lipopolysaccharide regulated protein expression is only partly impaired in monocytes from patients with type I diabetes

BACKGROUND: Monocytes play an important role in innate immunity and atherosclerosis. A disturbed secretion of cytokines in lipopolysaccharide (LPS) activated monocytes from type 1 diabetes (T1D) patients has been described and may contribute to the impaired inflammatory response in these individuals. In the present study the influence of LPS on five different proteins with a function in immunity and atherosclerosis was analyzed in monocytes from controls and T1D patients. METHODS: Monocytes were isolated from controls and T1D patients and the LPS-stimulated increase of IL-6, CXCL8, monocyte chemotactic protein 1 (CCL2, MCP-1) and superoxide dismutase (SOD 2), as well as the LPS-mediated decrease of apolipoprotein E (Apo E) in primary human monocytes from controls and T1D patients was determined. RESULTS: CCL2 and IL-6 secretion in response to LPS was found significantly reduced in monocytes from T1D patients when compared to controls whereas basal CCL2 release was similar in control and T1D cells. In contrast, CXCL8 and apolipoprotein E secretion and SOD 2 expression upon LPS stimulation is similar from T1D and control monocytes. CONCLUSION: These data indicate that LPS-mediated protein expression is only partly disturbed in monocytes from T1D patients. Reduced secretion of IL-6 and CCL2 in activated monocytes of these patients may contribute to an impaired inflammatory response and vascular disease

Impact of Enzymatic Degradation on the Material Properties of Poly(Ethylene Terephthalate)

With macroscopic litter and its degradation into secondary microplastic as a major source of environmental pollution, one key challenge is understanding the pathways from macro- to microplastic by abiotic and biotic environmental impact. So far, little is known about the impact of biota on material properties. This study focuses on recycled, bottle-grade poly(ethylene terephthalate) (r-PET) and the degrading enzyme PETase from Ideonella sakaiensis. Compact tension (CT) specimens were incubated in an enzymatic solution and thermally and mechanically characterized. A time-dependent study up to 96 h revealed the formation of steadily growing colloidal structures. After 96 h incubation, high amounts of BHET dimer were found in a near-surface layer, affecting crack propagation and leading to faster material failure. The results of this pilot study show that enzymatic activity accelerates embrittlement and favors fragmentation. We conclude that PET-degrading enzymes must be viewed as a potentially relevant acceleration factor in macroplastic degradation

Adiponectin-induced secretion of interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1, CCL2) and interleukin-8 (IL-8, CXCL8) is impaired in monocytes from patients with type I diabetes

BACKGROUND: Systemic adiponectin is reduced in patients with cardiovascular disease (CVD) and low adiponectin may contribute to the pathogenesis of atherosclerosis. However, circulating adiponectin is elevated in type 1 diabetes (T1D) patients, who have also a higher incidence to develop CVD. Because monocytes play an important role in atherosclerosis, we analysed the influence of adiponectin on cytokine and chemokine release in monocytes from T1D patients and controls. METHODS: Systemic adiponectin was determined in the plasma and the high-molecular weight (HMW) form of adiponectin was analysed by immunoblot. Monocytes were isolated from T1D patients and controls and the adiponectin-stimulated release of interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1, CCL2) and interleukin-8 (IL-8, CXCL8) was analysed. RESULTS: Systemic adiponectin was higher in T1D patients. Immunoblot analysis of the plasma indicate abundance of HMW adiponectin in T1D patients and controls. IL-6, CCL2 and CXCL8 secretion in response to adiponectin were found induced in monocytes from controls whereas only IL-6 was upregulated in T1D cells. The induction of IL-6 by adiponectin was abrogated by an inhibitor of the NFκB pathway. CONCLUSION: These data indicate that adiponectin-mediated induction of IL-6, CCL2 and CXCL8 is disturbed in monocytes from T1D patients and therefore elevated systemic adiponectin in T1D patients may be less protective when compared to controls