Two additive mechanisms impair the differentiation of 'substrate-selective' p38 inhibitors from classical p38 inhibitors in vitro

<p>Abstract</p> <p>Background</p> <p>The success of anti-TNF biologics for the treatment of rheumatoid arthritis has highlighted the importance of understanding the intracellular pathways that regulate TNF production in the quest for an orally-available small molecule inhibitor. p38 is known to strongly regulate TNF production via MK2. The failure of several p38 inhibitors in the clinic suggests the importance of other downstream pathways in normal cell function. Recent work has described a 'substrate-selective' p38 inhibitor that is able to preferentially block the activity of p38 against one substrate (MK2) versus another (ATF2). Using a combined experimental and computational approach, we have examined this mechanism in greater detail for two p38 substrates, MK2 and ATF2.</p> <p>Results</p> <p>We found that in a dual (MK2 and ATF2) substrate assay, MK2-p38 interaction reduced the activity of p38 against ATF2. We further constructed a detailed kinetic mechanistic model of p38 phosphorylation in the presence of multiple substrates and successfully predicted the performance of classical and so-called 'substrate-selective' p38 inhibitors in the dual substrate assay. Importantly, it was found that excess MK2 results in a stoichiometric effect in which the formation of p38-MK2-inhibitor complex prevents the phosphorylation of ATF2, despite the preference of the compound for the p38-MK2 complex over the p38-ATF2 complex. MK2 and p38 protein expression levels were quantified in U937, Thp-1 and PBMCs and found that [MK2] > [p38].</p> <p>Conclusion</p> <p>Our integrated mechanistic modeling and experimental validation provides an example of how systems biology approaches can be applied to drug discovery and provide a basis for decision-making with limited chemical matter. We find that, given our current understanding, it is unlikely that 'substrate-selective' inhibitors of p38 will work as originally intended when placed in the context of more complex cellular environments, largely due to a stoichiometric excess of MK2 relative to p38.</p

Arzneistofftarget-5-Lipoxygenase : ein neuer Enzymaktivierungsweg mit Einfluss auf die Wirksamkeit von Inhibitoren

Leukotriene (LT) sind bioaktive Lipidmediatoren, die in einer Vielzahl von Entzündungskrankheiten wie z.B. Asthma, Psoriasis, Arthritis oder allergische Rhinitis involviert sind. Des Weiteren spielen LT in der Pathogenese von Erkrankungen wie Krebs, Osteoarthritis oder Atherosklerose eine Rolle. Die 5-Lipoxygenase (5-LO) ist das Enzym, das für die Bildung von LT verantwortlich ist. Aufgrund der physiologischen Eigenschaften der LT, ist die Entwicklung von potentiellen Arzneistoffen, welche die 5-LO als Zielstruktur besitzen, von erheblichem Interesse. Die Aktivität der 5-LO wird in vitro durch Ca2+, ATP, Phosphatidylcholin und Lipidhydroperoxide (LOOH) und durch die p38-abhängige MK-2/3 5-LO bestimmt. Inhibitorstudien weisen darauf hin, dass der MEK1/2-Signalweg ebenfalls in vivo an der 5-LO Aktivierung beteiligt ist. Hauptziel dieser Arbeit war es zu untersuchen, welche Rolle der MEK1/2-Signalweg bei der Aktivierung der 5-LO besitzt und welchen Einfluss der 5-LO Aktivierungsweg auf die Wirksamkeit potentieller Inhibitoren hat. „In gel kinase“ und „In vitro kinase“ Untersuchungen zeigten, dass die 5-LO ein Substrat für die Extracellular signal-regulated kinase (ERK) und MK-2/3 darstellt. Der Zusatz von mehrfach ungesättigten Fettsäuren (UFA), wie AA oder Ölsäure, verstärkte den Phosphorylierungsgrad der 5-LO sowohl durch ERK1/2 als auch durch MK-2/3. Die genannten Kinasen sind demnach auch für die 5-LO Aktivierung durch natürliche Stimuli verantwortlich, die den zellulären Ca2+-Spiegel kaum beeinflussen. Daraus ist ersichtlich, dass die Phosphorylierung der 5-LO durch ERK1/2 und/oder MK-2/3 einen alternativen Aktivierungsmechanismus neben Ca2+ darstellt. Ursprünglich wurden Nonredox-5-LO-Inhibitoren als kompetitive Wirkstoffe entwickelt, die mit AA um die Bindung an die katalytische Domäne der 5-LO konkurrieren. Vertreter dieser Inhibitoren, wie ZM230487 und L-739,010, zeigen eine potente Hemmung der LT-Biosynthese in verschiedenen Testsystemen. Sie scheiterten jedoch in klinischen Studien. In dieser Arbeit konnten wir zeigen, dass die Wirksamkeit dieser Inhibitoren vom Aktivierungsweg der 5-LO abhängig ist. Verglichen mit 5-LO Aktivität, die durch den unphysiologischen Stimulus Ca2+-Ionophor induziert wird, erfordert die Hemmung zellstress-induzierter Aktivität eine 10- bis 100-fach höhere Konzentration der Nonredox-5-LO-Inhibitoren. Die nicht-phosphorylierbare 5-LO Mutante (Ser271Ala/Ser663Ala) war wesentlich sensitiver gegenüber Nonredox-Inhibitoren als der Wildtyp, wenn das Enzym durch 5-LO Kinasen aktiviert wurde. Somit zeigen diese Ergebnisse, dass, im Gegensatz zu Ca2+, die 5-LO Aktivierung mittels Phosphorylierung die Wirksamkeit der Nonredox-Inhibitoren deutlich verringert. Des Weiteren wurde das pharmakologische Profil des neuen 5-LO Inhibitors CJ-13,610 mittels verschiedener in vitro-Testsysteme charakterisiert. In intakten PMNL, die durch Ca2+-Ionophor stimuliert wurden, hemmte die Substanz die 5-LO Produktbildung mit einem IC50 von 70 nM. Durch Zugabe von exogener AA, wird die Wirkung vermindert und der IC50 des Inhibitors steigt an. Dies deutet auf eine kompetitive Wirkweise hin. Wie die bekannten Nonredox-Inhibitoren, verliert auch CJ-13,610 seine Wirkung bei erhöhtem zellulärem Peroxidspiegel. Der Inhibitor CJ-13,610 zeigt jedoch keine Abhängigkeit vom Aktivierungsweg der 5-LO. Grundsätzlich ist es also von fundamentaler Bedeutung bei der Entwicklung von neuen Arzneistoffen, die zellulären Zusammenhänge, insbesondere die Regulierung der Aktivität von Enzymen, zu kennen. Wie in dieser Arbeit gezeigt, hat die Phosphorylierung der 5-LO einen starken Einfluss auf die Regulation der 5-LO Aktivität und eine elementare Wirkung auf die Hemmung des Enzyms durch verschiedene Wirkstoffe

Molecular regulation of hormone secretion, growth and apoptosis of GLP-1-producing cells

Type 2 diabetes (T2D) spreads like an epidemic in today’s society, and there is a great need for new and improved treatments. T2D is characterized by hyperglycemia, resulting from impaired insulin production and insulin resistance in peripheral tissues. Incretin hormones, such as glucagon-like peptide-1 (GLP-1), secreted from L-cells dispersed along the intestinal tract, potentiate meal-stimulated insulin secretion in a glucose-dependent manner. Defective GLP-1 secretion has been indicated in T2D and administration of GLP-1 to T2D patients restores glucose-induced insulin secretion and normalizes glycemia, making stable analogs of GLP-1 among the best available treatments for T2D today. However, enhancing endogenous GLP-1 production/secretion by direct stimulation of GLP-1 secretion/promotion of growth and viability of L-cells may be a novel and more physiological option in incretin-based diabetes therapy. The aim of this work was to determine the effect of diabetic conditions and anti-diabetic agents on GLP-1-producing cells, in order to unravel some of the mechanisms regulating growth, survival and function of this cell type. Studies I-III were performed in vitro using the murine GLUTag cell line as a model. In study I, direct effects of metformin on apoptosis, and function of GLP-1-secreting cells were determined. Simulated diabetic hyperlipidemia resulted in increased caspase-3 activity and DNA fragmentation, indicating lipoapoptosis. Metformin treatment significantly decreased this lipoapoptosis in conjunction with increased phosphorylation of AMPK. In addition, metformin treatment stimulated GLP-1 secretion. In study II, we determined molecular mechanisms mediating lipotoxicity and metformininduced lipoprotection in GLP-1-secreting cells. Diabetic hyperlipidemia was simulated in this cell system by addition of the fatty acid palmitate. Palmitate increased ROS production in GLP- 1-secreting cells, and the lipotoxic effects of palmitate were abolished in the presence of the antioxidant Trolox. Further, palmitate phosphorylated p38 MAPK and inhibition of this enzyme significantly reduced lipoapoptosis. Pre-incubation with metformin further increased palmitate- induced ROS production, while significantly reducing the expression of p38 MAPK. Study III focused on direct effects of insulin and exendin-4/GLP-1 on lipoapoptosis and function of GLP-1-secreting cells. The GLP-1R was found to be expressed in the GLUTag cells, and diabetic lipotoxicity was partially inhibited by pre-incubation with insulin or the stable GLP-1 analog exendin-4. The lipoprotective effect of exendin-4 was GLP-1R-dependent, while independent of PKA activity. In addition, both insulin and exendin-4 significantly stimulated acute and long term GLP-1 secretion in the presence of glucose. In study IV, we investigated if a high fat diet (HFD) reduces the number of enteroendocrine GLP-1-secreting Lcells in C57/Bl6 mice. We also determined the effects of a HFD on GLP-1 plasma levels and possible effects on these parameters by metformin treatment. A HFD rapidly induced a diabetic phenotype with increased HbA1c levels, as well as fasting plasma insulin levels in conjunction with reduced oral glucose tolerance – indicating the manifestation of insulin resistance. A 14 day oral administration of metformin reduced HbA1c, fasting insulin and prandial FFA levels. The number of L-cells was significantly reduced after 12 weeks on a HFD, while -- in contrast - - there was a clear trend toward increased prandial plasma GLP-1 levels despite reduced food intake in HFD-fed mice. These findings may be of pathogenic significance not only in understanding mechanisms of the impaired incretin response characterizing T2D patients, but may also be harnessed to therapeutic advantage in efforts to enhance endogenous GLP-1 production. Such an approach has hitherto received little attention but may be superior to contemporary incretin-based antidiabetic therapy, which does not faithfully mimick physiologic GLP-1 release in for instance terms of secretory pattern (e.g. pulsatility) and actions on topographically adjacent hormone receptors (e.g. in the portal vein)

Biosynthesis of Promatrix Metalloproteinase-9/Chondroitin Sulphate Proteoglycan Heteromer Involves a Rottlerin-Sensitive Pathway

BACKGROUND: Previously we have shown that a fraction of the matrix metalloproteinase-9 (MMP-9) synthesized by the macrophage cell line THP-1 was bound to a chondroitin sulphate proteoglycan (CSPG) core protein as a reduction sensitive heteromer. Several biochemical properties of the enzyme were changed when it was bound to the CSPG. METHODOLOGY/PRINCIPAL FINDINGS: By use of affinity chromatography, zymography, and radioactive labelling, various macrophage stimulators were tested for their effect on the synthesis of the proMMP-9/CSPG heteromer and its components by THP-1 cells. Of the stimulators, only PMA largely increased the biosynthesis of the heteromer. As PMA is an activator of PKC, we determined which PKC isoenzymes were expressed by performing RT-PCR and Western Blotting. Subsequently specific inhibitors were used to investigate their involvement in the biosynthesis of the heteromer. Of the inhibitors, only Rottlerin repressed the biosynthesis of proMMP-9/CSPG and its two components. Much lower concentrations of Rottlerin were needed to reduce the amount of CSPG than what was needed to repress the synthesis of the heteromer and MMP-9. Furthermore, Rottlerin caused a minor reduction in the activation of the PKC isoenzymes δ, ε, θ and υ (PKD3) in both control and PMA exposed cells. CONCLUSIONS/SIGNIFICANCE: The biosynthesis of the proMMP-9/CSPG heteromer and proMMP-9 in THP-1 cells involves a Rottlerin-sensitive pathway that is different from the Rottlerin sensitive pathway involved in the CSPG biosynthesis. MMP-9 and CSPGs are known to be involved in various physiological and pathological processes. Formation of complexes may influence both the specificity and localization of the enzyme. Therefore, knowledge about biosynthetic pathways and factors involved in the formation of the MMP-9/CSPG heteromer may contribute to insight in the heteromers biological function as well as pointing to future targets for therapeutic agents

MKP-1 발현 증가를 통해 항염증 활성을 갖는 CMDD8299의 항동맥경화 기전 규명

학위논문 (박사)-- 서울대학교 대학원 자연과학대학 지구환경과학부, 2017. 8. 강헌중.Atherosclerosis is known as a chronic inflammatory disease and numerous attempts to improve atherosclerosis by anti-inflammatory molecules were conducted. Marine sponges are rich sources of anti-inflammatory natural products. To find the anti-atherosclerotic molecule, anti-inflammatory effects of marine natural products against cytokines such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β) were evaluated. I identified several marine natural products including phorbaketal A, which showed anti-inflammatory effects. Phorbaketal A is a marine sponge-derived bioactive sesterterpenoid, which isolated from Phorbas sp. and Monanchora sp. Byun MR et al. demonstrated that phorbaketal A stimulates osteogenic differentiation and inhibits adipogenic differentiation through activation of transcriptional coactivator with PDZ-binding motif (TAZ) and extracellular signal-regulated kinase (ERK) in C3H10T1/2 and human mesenchymal stem cell. In the present study, phorbaketal A significantly reduced IL-6, TNF-α and IL-1β mRNA expression in lipopolysaccharide (LPS)-induced raw 264.7 macrophages and inhibited IL-6 and TNF-α secretion. Phorbaketal A reduced nitric oxide (NO) secretion through inhibition of inducible nitric oxide synthase (iNOS) expression. In addition, pre-incubation of human umbilical vein endothelial cells (HUVECs) with phorbaketal A abrogated TNF-α-induced expression of VCAM-1 and MCP-1. To demonstrate anti-atherogenic effect of phorbaketal A in vivo, 5 mg/kg of phorbaketal A administered to three types of atherosclerosis in vivo models with atherogenic diet (21% fat, 1.25% cholesterol). The severity of atherosclerosis was analyzed by en face staining of aorta. Phorbaketal A treated mice had less atherosclerotic lesions than control group in progression models. MAPKs regulate numerous fundamental cellular processes especially inflammation and immune response. TLR agonists activate MAPKs signals in innate immune cells and contribute to pathogenesis of atherosclerosis. To identify the molecular mechanisms of phorbaketal A, effects of phorbaketal A on MAPK activation were estimated. Phorbaketal A inhibited LPS-induced phosphorylation of p38 MAPK but it has no effect on ERK or JNK phosphorylation in raw264.7 macrophage. In addition, phorbaketal A abrogated p38 phosphorylation in TNF-α stimulated HUVECs. The inhibitory effect of phorbaketal A recovered by MAPK phosphatase 1 (MKP-1) inhibitor, triptolide. MKP-1 is known to inhibit inadequate inflammatory response through negative feedback of MAPKs, especially p38 and JNK. Phorbaketal A induced MKP-1 mRNA and protein expression in concentration-dependent manners. Transcription factors which regulate MKP-1 expression, such as cAMP response element binding protein (CREB) and activating transcription factor 2 (ATF-2) were phosphorylated at early time (5 min) by phorbaketal A. The phosphorylation of ERK pathway signaling molecules were suppressed by U0126 (ERK inhibitor). These suggest that phorbaketal A induced MKP-1 through ERK-activated CREB and ATF-2 signals. In this study, I identified a novel mechanism of phorbaketal A, and demonstrated its anti-atherogenic effects on model of atherosclerosis in vitro and in vivo. These results suggest that phorbaketal A could be a drug candidate for treatment of inflammatory disease, such as atherosclerosis.Chapter 1. Introduction 1 1.1 Atherosclerosis 1 1.2 Inflammation in atherosclerosis 3 1.3 MAPK phosphatase 1 (MKP-1) 5 1.4 Aim of study 6 Chapter 2. Materials and Methods 7 2.1 Reagents and Antibodies 7 2.2 Cell Culture 7 2.3 Animal Experiment 8 2.4 En face Staining 9 2.5 Cell Viability 9 2.6 Total RNA Preparation and Quantitative Real-time PCR 10 2.7 miR101-PCR 12 2.8 Western Blotting 13 2.9 ELISA 13 2.10 Nitrite Assay 14 2.11 Statistical analysis 14 Chapter 3. Results 15 3.1 Phorbaketal A 15 3.2 Phorbaketal A inhibited nitric oxide production by suppression of inducible nitric oxide synthase expression in LPS-activated raw264.7 19 3.3 Phorbaketal A inhibited production of pro-inflammatory cytokines in LPS-activated raw264.7 21 3.4 Phorbaketal A differentially inhibited adhesion molecules expression in TNF-α stimulated HUVEC 24 3.5 Phorbaketal A abrogated MCP-1 expression in TNF-α induced HUVEC 26 3.6 Effects of phorbaketal A on apoE knockout mice lesion formation 28 3.6.1 Progression model-1 lesion analysis 28 3.6.2 Progression model-2 lesion analysis 31 3.6.3 Regression model lesion analysis 34 3.7 Effects of phorbaketal A on apoE knockout mice aortic inflammatory gene expression 37 3.8 Phorbaketal A activated MAPK phosphorylation 42 3.9 Phorbaketal A abrogated p38 phosphorylation in LPS-activated raw264.7 47 3.10 Phorbaketal A induced MKP-1 expression 49 3.11 MKP-1 stabilized by Phorbaketal A 52 3.12 Phorbaketal A suppressed p38 phosphorylation by MKP-1 54 3.13 Phorbaketal A upregulated MKP-1 expression through the ERK in raw264.7 58 3.14 Effects of phorbaketal A on MAPK in TNF-α stimulated HUVEC 65 Chapter 4. Discussion 70 References 81 국문 초록 101Docto

Cytokines and epigenetic regulation of matrix metalloproteinases in tuberculosis

Tuberculosis (TB) remains a leading cause of death globally. Some of the morbidity and mortality associated with TB arises from excessive or inappropriate immune activation in response to infection. In pulmonary TB tissue destruction, cavitation and fibrosis drive disease transmission and chronic lung dysfunction. The matrix metalloproteinases (MMPs) are host enzymes controlling extracellular matrix turnover, immune cell recruitment and activation, and they play a key role in the pathology of TB. This project explores the regulatory mechanisms controlling MMP expression in TB using a tissue culture model of respiratory epithelial cell and macrophage responses to Mycobacterium tuberculosis (Mtb). The major human collagenase MMP-1 and its activator MMP-3 are expressed in response to Mtb stimulation. The influence of exogenously added cytokines IL-4, IL-10, IL-13, TGFβ and IFNγ on MMP expression is investigated to examine how immunopathology is driven by acquired immune responses. Epigenetic mechanisms regulating MMP expression in response to Mtb are examined using inhibitors of histone deacetylases (HDACs) and histone acetyltransferases, HDAC siRNA and chromatin immunoprecipitation assays. Mtb-induced collagenase expression by epithelial cells and macrophages is selectively inhibited by the Th2 cytokines IL-4 and IL-13, but unaffected by IL-10. TGFβ enhances epithelial cell MMP secretion but does not affect macrophage MMP expression. IFNγ has divergent effects, driving epithelial cell MMP secretion but inhibiting MMP-1 and -3 expression in macrophages. The intracellular pathways mediating these effects are explored. Mtb-driven MMP expression is sensitive to HDAC and HAT inhibition, and altered HDAC expression is observed in Mtb-stimulated cells. Chromatin immunoprecipitation reveals changes in histone acetylation at the MMP-1 promoter in Mtb-stimulated epithelial cells. In pulmonary TB, production of matrix-degrading MMPs by epithelial cells and macrophages is modulated by Th2 cytokines and IFNγ. Key MMPs implicated in pulmonary immunopathology are subject to epigenetic regulatory mechanisms, which may represent potential targets for selective MMP inhibition.Open Acces

Regulation of cancer cell viability by p38 MAPK

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 17-06-201

Pharmakologische Wirkmechanismen und Zielstrukturen von Boswelliasäuren in humanen Leukozyten und Thrombozyten

Boswellia serrata gum resin extracts (frankincense) have been used for centuries in folk medicine in Asia and Africa. They have shown beneficial therapeutic effects, particularly in the treatment of chronic inflammatory diseases. Clinical studies on humans confirmed an anti-inflammatory and anti-cancer potential of Frankincense preparations. Boswellic acids (BAs) are the major ingredients, responsible for the pharmacological action of the extracts. Molecular and cellular studies with BAs revealed a number of targets including 5-lipoxygenase (LO), topoisomerases and the NF-&#954;B pathway. Since there is little information on the modulation of cellular physiology by BAs, this work was designed to provide a detailed investigation of the cellular and molecular effects of BAs in several cell types related to inflammation. We report that 11-keto-BAs are potent activators of functional responses in human neutrophils, a type of leukocytes mediating acute inflammatory processes. Neutrophil activation by 11-keto-BAs is reflected by enhanced generation of oxygen radicals, release of arachidonic acid (AA) and the subsequent transformation of AA to pro-inflammatory eicosanoids. Investigation of the participating signalling pathways identified Ca2+, phosphoinositide-3 kinase, and members of the MAP kinase family (ERKs) as mediators. Second, we present a detailed study of the modulation of human platelet physiology and intracellular signalling events by BAs. Intriguingly, we discovered an inverse structure-activity relationship of BAs regarding platelet activation, with 11-methylene-BAs being superior over 11-keto-BAs. Thus, 11-methylene-BAs stimulated platelet Ca2+ mobilisation, MAP kinase and Akt activation, AA release, 12-LO and cyclooxygenase product formation, and thrombin generation. Novel Ca2+-independent activation pathways of platelet lipid metabolism were discovered. In contrast, 11-keto-BAs were inactive but found to inhibit platelet (p)12-LO directly. Interaction with p12-LO was confirmed in a pulldown assay using immobilised BAs as bait. Finally, BAs were shown to attenuate the activation of monocytes, a cell type responsible for the maintenance of chronic inflammatory states. Impairment of Ca2+ homeostasis is likely conferred by inhibition of Ca2+ influx channels. Taken together, our results shed light on the modulation of intracellular physiology of inflammatory cells by BAs, contributing to a better understanding of the anti-inflammatory effects exerted by frankincense preparations.Extrakte aus dem Harz von Boswellia serrata (Weihrauch) werden seit Jahrhunderten erfolgreich in der asiatischen und afrikanischen Naturmedizin zur Behandlung von chronisch entzündlichen Erkrankungen eingesetzt. Klinische Studien am Menschen bestätigen ein Potenzial von Weihrauchpräparaten in Entzündungs- und Krebserkrankungen. Boswelliasäuren (BAs) sind die Hauptinhaltsstoffe der Extrakte und verantwortlich für ihre pharmakologische Wirkung. Molekulare und zelluläre Studien mit BAs führten zur Entdeckung mehrerer Targets von BAs, darunter die 5-Lipoxygenase (LO), Topoisomerasen, und die NF-kappaB-Route. In der vorliegenden Arbeit wurden die zellulären und molekularen Effekte von BAs detailliert untersucht. 11-Keto-BAs wurden als potente Aktivatoren von humanen Neutrophilen identifiziert. Dies spiegelt sich in der verstärkten Bildung von Sauerstoffradikalen, Freisetzung von Arachidonsäure (AA) und nachfolgender Umwandlung zu pro-entzündlichen Eikosanoiden wider. Ca2+, Phosphoinositid-3-Kinase und Mitglieder der MAP-Kinase-Familie (ERKs) sind Mediatoren dieser Signale. Weiterhin wurde die Modulierung der Physiologie und der intrazellulären Signalwege in humanen Thrombozyten eingehend beleuchtet. 11-Methylen-BAs stimulierten in Blutplättchen die Ca2+-Mobilisierung, MAP-Kinase- und Akt-Aktivierung, AA-Freisetzung, p12-LO- und Cyclooxygenase-Produktbildung sowie die Thrombin-Generierung. Neue, Ca2+-unabhängige Aktivierungswege für den Lipidmetabolismus wurden entdeckt. Dagegen waren 11-Keto-BAs eher inaktiv, zeichneten sich aber durch direkte Hemmung der p12-LO von Thrombozyten aus. Diese Wechselwirkung wurde in einem Pulldown-Experiment bestätigt, in dem immobilisierte BAs als „Köder“ dienten. Im letzten Abschnitt wird die Hemmung der Monozyten-Aktivierung durch BAs beschrieben. Monozyten/ Makrophagen sind an der Aufrechterhaltung von chronischen Entzündungen beteiligt. Die Beeinträchtigung der Ca2+-Homöostase kommt vermutlich durch die Hemmung von Ca2+-Einstrom-Kanälen zustande. Insgesamt werfen diese Ergebnisse ein neues Licht auf die Modulierung der intrazellulären Physiologie entzündungsrelevanter Zellen durch BAs, die zu einem erweiterten Verständnis der anti-entzündlichen Effekte von Weihrauchextrakten beitragen