Lung eosinophilia is a hallmark of asthma, and eosinophils are believed to play a crucial role in the pathogenesis of allergic inflammatory diseases. Short-chain fatty acids (SCFAs), such as acetate, ...propionate, and butyrate, are produced in high amounts in the gastrointestinal tract by commensal bacteria and can be absorbed into the bloodstream. Although there is recent evidence that SCFAs are beneficial in allergic asthma models, the effect on eosinophils has remained elusive.
The role of SCFAs was investigated in human eosinophil function and a mouse model of allergic asthma.
Eosinophils were purified from self-reported allergic or healthy donors. Migration, adhesion to the endothelium, and eosinophil survival were studied in vitro. Ca2+ flux, apoptosis, mitochondrial membrane potential, and expression of surface markers were determined by using flow cytometry and in part by using real-time PCR. Allergic airway inflammation was assessed in vivo in an ovalbumin-induced asthma model by using invasive spirometry.
For the first time, we observed that SCFAs were able to attenuate human eosinophils at several functional levels, including (1) adhesion to the endothelium, (2) migration, and (3) survival. These effects were independent from GPR41 and GPR43 but were accompanied by histone acetylation and mimicked by trichostatin A, a pan–histone deacetylase inhibitor. In vivo butyrate ameliorated allergen-induced airway and lung eosinophilia, reduced type 2 cytokine levels in bronchial fluid, and improved airway hyperresponsiveness in mice.
These in vitro and in vivo findings highlight the importance of SCFAs, especially butyrate as a promising therapeutic agent in allergic inflammatory diseases.
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The directional migration of neutrophils towards inflammatory mediators, such as chemokines and cannabinoids, occurs via the activation of seven transmembrane G protein coupled receptors （7TM/GPCRs） ...and is a highly organized process. A crucial role for controlling neutrophil migration has been ascribed to the cannabinoid CBz receptor （CB2R）, but additional modulatory sites distinct from CB2R have recently been suggested to impact CB2R-mediated effector functions in neutrophils. Here, we provide evidence that the recently de-orphanized 7TM/GPCR GPR55 potently modulates CB2R-mediated responses. We show that GPR55 is expressed in human blood neutrophils and its activation augments the migratory response towards the CB2R agonist 2-arachidonoylglycerol （2-AG）, while inhib- iting neutrophil degranulation and reactive oxygen species （ROS） production. Using HEK293 and HL60 cell lines, along with primary neutrophils, we show that GPR55 and CB2R interfere with each other＇s signaling pathways at the level of small GTPases, such as Rac2 and Cdc42. This ultimately leads to cellular polarization and efficient migration as well as abrogation of degranulation and ROS formation in neutrophils. Therefore, GPR55 limits the tissueinjuring inflammatory responses mediated by CB2R, while it synergizes with CB2R in recruiting neutrophils to sites of inflammation.
Placental hypervascularization has been reported in pregnancy-related pathologies such as gestational diabetes mellitus (GDM). Nevertheless, the underlying causes behind this abnormality are not well ...understood. In this study, we addressed the expression of SUCNR1 (cognate succinate receptor) in human placental endothelial cells and hypothesized that the succinate-SUCNR1 axis might play a role in the placental hypervascularization reported in GDM. We measured significantly higher succinate levels in placental tissue lysates from women with GDM relative to matched controls. In parallel, SUCNR1 protein expression was upregulated in GDM tissue lysates as well as in isolated diabetic fetoplacental arterial endothelial cells (FpECAds). A positive correlation of SUCNR1 and vascular endothelial growth factor (VEGF) protein levels in tissue lysates indicated a potential link between the succinate-SUCNR1 axis and placental angiogenesis. In our in vitro experiments, succinate prompted hallmarks of angiogenesis in human umbilical vein endothelial cells (HUVECs) such as proliferation, migration and spheroid sprouting. These results were further validated in fetoplacental arterial endothelial cells (FpECAs), where succinate induced endothelial tube formation. VEGF gene expression was increased in response to succinate in both HUVECs and FpECAs. Yet, knockdown of SUCNR1 in HUVECs led to suppression of VEGF gene expression and abrogated the migratory ability and wound healing in response to succinate. In conclusion, our data underline SUCNR1 as a promising metabolic target in human placenta and as a potential driver of enhanced placental angiogenesis in GDM.
Abstract
Disruption of the blood-air barrier, which is formed by lung microvascular endothelial and alveolar epithelial cells, is a hallmark of acute lung injury. It was shown that alveolar ...epithelial cells release an unidentified soluble factor that enhances the barrier function of lung microvascular endothelial cells. In this study we reveal that primarily prostaglandin (PG) E
2
accounts for this endothelial barrier-promoting activity. Conditioned media from alveolar epithelial cells (primary ATI-like cells) collected from BALB/c mice and A549 cells increased the electrical resistance of pulmonary human microvascular endothelial cells, respectively. This effect was reversed by pretreating alveolar epithelial cells with a cyclooxygenase-2 inhibitor or by blockade of EP4 receptors on endothelial cells, and in A549 cells also by blocking the sphingosine-1-phosphate
1
receptor. Cyclooxygenase-2 was constitutively expressed in A549 cells and in primary ATI-like cells, and was upregulated by lipopolysaccharide treatment. This was accompanied by enhanced PGE
2
secretion into conditioned media. Therefore, we conclude that epithelium-derived PGE
2
is a key regulator of endothelial barrier integrity via EP4 receptors under physiologic and inflammatory conditions. Given that pharmacologic treatment options are still unavailable for diseases with compromised air-blood barrier, like acute lung injury, our data thus support the therapeutic potential of selective EP4 receptor agonists.
RNA interference systems depend on the synthesis of small RNA precursors whose sequences define the target spectrum of these silencing pathways. The
Drosophila
Heterochromatin Protein 1 (HP1) variant ...Rhino permits transcription of PIWI-interacting RNA (piRNA) precursors within transposon-rich heterochromatic loci in germline cells. Current models propose that Rhino’s specific chromatin occupancy at piRNA source loci is determined by histone marks and maternally inherited piRNAs, but also imply the existence of other, undiscovered specificity cues. Here, we identify a member of the diverse family of zinc finger associated domain (ZAD)-C
2
H
2
zinc finger proteins, Kipferl, as critical Rhino cofactor in ovaries. By binding to guanosine-rich DNA motifs and interacting with the Rhino chromodomain, Kipferl recruits Rhino to specific loci and stabilizes it on chromatin. In
kipferl
mutant flies, Rhino is lost from most of its target chromatin loci and instead accumulates on pericentromeric Satellite arrays, resulting in decreased levels of transposon targeting piRNAs and impaired fertility. Our findings reveal that DNA sequence, in addition to the H3K9me3 mark, determines the identity of piRNA source loci and provide insight into how Rhino might be caught in the crossfire of genetic conflicts.
The genes within our DNA encode the essentials of our body plan and how each task in the body is achieved. However, our genome also contains many repetitive regions of DNA that do not encode functional genes. Some of these regions are genetic parasites known as transposons that try to multiply and spread around the DNA of their host. To prevent transposon DNA from interfering with the way the body operates, humans and other animals have evolved elaborate defense mechanisms to identify transposons and prevent them from multiplying.
In one such mechanism, known as the piRNA pathway, the host makes small molecules known as piRNAs that have sequences complementary to those of transposons, and act as guides to silence the transposons. The instructions to make these piRNAs are stored in the form of transposon fragments in dedicated regions of host DNA called piRNA clusters. These clusters thereby act as genetic memory, allowing the host to recognize and silence specific transposons in other locations within the host’s genome. In fruit flies, a protein called Rhino binds to piRNA clusters that are densely packed to allow piRNAs to be made. However, it remained unclear how Rhino is able to identify and bind to piRNA clusters, but not to other similarly densely packed regions of DNA.
Baumgartner et al. used a combination of genetic, genomic, and imaging approaches to study how Rhino finds its way in the fruit fly genome. They found that another protein called Kipferl interacts with Rhino and is required for Rhino to bind to nearly all piRNA clusters. Since Kipferl can by itself bind to the sequences that Rhino needs to find, the results suggest that Kipferl acts to recruit and initiate Rhino binding within densely packed piRNA clusters. Further experiments found that, in flies lacking Kipferl, Rhino binds to regions of DNA called Satellite repeats, hinting that these selfish sequences may compete for Rhino for their own benefit.
The finding that Kipferl and Rhino work together to define the memory system of the piRNA pathway strongly advances our understanding of how a sequence-specific defense system based on small RNAs can be established.
Abstract Endothelial dysfunction is a hallmark of inflammatory conditions. We recently demonstrated that prostaglandin (PG)E2 enhances the resistance of pulmonary endothelium in vitro and counteracts ...lipopolysaccharide (LPS)-induced pulmonary inflammation in vivo via EP4 receptors. The aim of this study was to investigate the role of the EP1/EP3 receptor agonist 17-phenyl-trinor-(pt)-PGE2 on acute lung inflammation in a mouse model. In LPS-induced pulmonary inflammation in mice, 17-pt-PGE2 reduced neutrophil infiltration and inhibited vascular leakage. These effects were unaltered by an EP1 antagonist, but reversed by EP4 receptor antagonists. 17-pt-PGE2 increased the resistance of pulmonary microvascular endothelial cells and prevented thrombin-induced disruption of endothelial junctions. Again, these effects were not mediated via EP1 or EP3 but through activation of the EP4 receptor, as demonstrated by the lack of effect of more selective EP1 and EP3 receptor agonists, prevention of these effects by EP4 antagonists and EP4 receptor knock-down by siRNA. In contrast, the aggregation enhancing effect of 17-pt-PGE2 in human platelets was mediated via EP3 receptors. Our results demonstrate that 17-pt-PGE2 enhances the endothelial barrier in vitro on pulmonary microvascular endothelial cells, and accordingly ameliorates the recruitment of neutrophils, via EP4 receptors in vivo. This suggests a beneficial effect of 17-pt-PGE2 on pulmonary inflammatory diseases.
Prostaglandin (PG) D2 is substantially involved in allergic responses and signals through the 7 transmembrane–spanning/G protein–coupled receptors, chemoattractant receptor–homologous molecule ...expressed on TH2 cells (CRTH2), and D-type prostanoid (DP) receptor.
Although the proinflammatory function of CRTH2 is well recognized and CRTH2 is hence considered an important emerging pharmacotherapeutic target, the role of the DP receptor in mediating the biological effects of PGD2 in patients with allergic inflammation has remained unclear.
The cross-talk of CRTH2 and DP receptors was investigated by using both a recombinant HEK293 cell model and human eosinophils in Ca2+ mobilization assays, coimmunoprecipitation, Western blotting, radioligand binding, and immunofluorescence.
We show that CRTH2 and DP receptors modulate one another’s signaling properties and form CRTH2/DP heteromers without altering their ligand-binding capacities. We find that the DP receptor amplifies the CRTH2-induced Ca2+ release from intracellular stores and coincidentally forfeits its own signaling potency. Moreover, desensitization or pharmacologic blockade of the DP receptor hinders CRTH2-mediated signal transduction. However, CRTH2 internalization occurs independently of the DP receptor. In cells that express both receptors, pharmacologic blockade of Gαq/11 proteins abolishes the Ca2+ response to both CRTH2 and DP agonists, whereas inhibition of Gαi proteins selectively attenuates the CRTH2-mediated response but not the DP signal.
Our data demonstrate the capacity of DP receptors to amplify the biological response to CRTH2 activation. Therefore the CRTH2/DP heteromer might not only represent a functional signaling unit for PGD2 but also a potential target for the development of heteromer-directed therapies to treat allergic diseases.
Bronislaw Huberman (1882–1947), einer der großen Violinvirtuosen in der ersten Hälfte des 20. Jahrhunderts und bekannt als ein Künstler, der sich dem Nationalsozialismus entgegenstellte und bedrohten ...jüdischen Musikern zum Überleben verhalf, war auch ein bedeutender Vordenker und Botschafter eines vereinten Europa.
Diesem kaum bekannten Engagement Hubermans in der europäischen Einigungsbewegung nach dem Ersten Weltkrieg widmet sich dieses Buch. Es stellt anhand seiner Schriften und seines Briefverkehrs einen politisch weitsichtigen Künstler vor, der sich mit originellen Gedanken und unermüdlichem Elan für ein Vaterland Europa einsetzte.
Mehrere Kernelemente der Huberman’schen Europakonzeption haben nach dem Zweiten Weltkrieg maßgeblich den Einigungsprozess bestimmt: die politisch eingebettete Zollunion als Ausgangsprojekt, der Utilitarismus als Triebfeder und die Ökonomie als strategische Entwicklungsachse. Die heutige Europäische Union weist in einer Reihe wichtiger Politikfelder Integrationsleistungen auf, die Huberman ein knappes Jahrhundert zuvor beschrieben und gefordert hat. Auch lebt der normative Gehalt seiner auf Völkerfrieden und gesellschaftliche Wohlfahrt gerichteten Botschaften in gegenwärtigen Europa-Diskursen fort.
Der Brückenschlag zur heutigen Europäischen Union zeigt, wie aktuell Hubermans Denken in einer Zeit ist, in der in einem krisengeschüttelten Europa eine bedenkliche Geschichtsvergessenheit um sich greift.
This article examines the European Trade Union Federations’ (ETUFs) role within the European polity in representing the interests of their affiliates vis-à-vis decision-makers at European level. In ...order to influence processes at European level, however, ETUFs need to aggregate and coordinate the often heterogeneous interests of their affiliates. This dual focus of the ETUFs’ activities is captured in the article by using the concept of the ‘logic of membership’ and ‘logic of influence’ to investigate how changes in their internal and external environment have affected the ETUFs’ capacity to act within the institutional structures and decision-making processes that constitute the European polity. A key finding of the article is that the European Commission’s renewed focus on strengthening the social dimension in principle opens up new opportunities for ETUFs to increase their influence at European level. The analysis, however, also shows that this is only possible if the ETUFs manage to mobilise the support of their affiliates for joint European strategies. This in turn requires national trade unions to overcome their tendency to retreat to the national level to cope with transnational challenges.
European negotiations are a relatively new and dynamic phenomenon of company-level industrial relations. Research thus far has mainly focused on the employee and trade union side. This contribution ...deals with the role of management. Based on case study research, it analyses management’s motivations and negotiation strategies in initiating and implementing European company-level agreements. The research shows that only in very few cases is the employee side able to force central management to the European negotiation table by organizing effective transnationally coordinated collective action or protests. As a rule, negotiations at European company level are only possible if management itself has a manifest interest in regulating certain issues at European level. In these cases, management’s interest in negotiations opens up room for manoeuvre for the employee side as regards not only the content of the agreement, but also the negotiation process itself and its participants.
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