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See detailL'expérimentation animale ne se fait pas en dehors de tout contrôle (OPINION)
Muraille, Eric; de Kerchove d'Exaerde, Alban; Blanpain, Cedric et al

Article for general public (2018)

Proposer de réduire l'expérimentation animale pour raisons morales est louable. Mais ce choix de société ne doit pas être vendu au citoyen en lui laissant croire que la recherche conserverait la même ... [more ▼]

Proposer de réduire l'expérimentation animale pour raisons morales est louable. Mais ce choix de société ne doit pas être vendu au citoyen en lui laissant croire que la recherche conserverait la même qualité ou en serait améliorée. [less ▲]

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See detailThe lung microbiome in idiopathic pulmonary fibrosis: A promising approach for targeted therapies
Fastrès, Aline ULiege; Felice, Florence ULiege; Roels, Elodie ULiege et al

in International Journal of Molecular Sciences (2017), 18(12), 2735

This review focuses on the role of the lung microbiome in idiopathic pulmonary fibrosis. Although historically considered sterile, bacterial communities have now been well documented in lungs both in ... [more ▼]

This review focuses on the role of the lung microbiome in idiopathic pulmonary fibrosis. Although historically considered sterile, bacterial communities have now been well documented in lungs both in healthy and pathological conditions. Studies in idiopathic pulmonary fibrosis (IPF) suggest that increased bacterial burden and/or abundance of potentially pathogenic bacteria may drive disease progression, acute exacerbations, and mortality. More recent work has highlighted the interaction between the lung microbiome and the innate immune system in IPF, strengthening the argument for the role of both host and environment interaction in disease pathogenesis. Existing published data suggesting that the lung microbiome may represent a therapeutic target, via antibiotic administration, immunization against pathogenic organisms, or treatment directed at gastroesophageal reflux. Taken altogether, published literature suggests that the lung microbiome might serve in the future as a prognostic biomarker, a therapeutic target, and/or provide an explanation for disease pathogenesis in IPF. [less ▲]

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See detailCharacterization and regulation of the intestinal epithelial cell response to colitogenic triggers
El Abbas, Sophie ULiege; Beguin, C; Schyns, Joey ULiege et al

in Proceedings of Annual meeting of the French Society for Immunology (SFI) (2017, November 07)

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See detailRab guanine nucleotide exchange factor 1 (Rabgef1) restricts intestinal inflammation by limiting pro-inflammatory signals in Intestinal Epithelial Cells (IECs)
El Abbas, Sophie ULiege; Beguin, Charline ULiege; Schyns, Joey ULiege et al

in Proceedings: 4th FARAH-DAY (2017, October 13)

Rab guanine nucleotide exchange factor (GEF-)1 (Rabgef1), a multifunctional protein whose in vivo functions remained unknown until recently, is highly expressed in mouse and human epithelial cells. The ... [more ▼]

Rab guanine nucleotide exchange factor (GEF-)1 (Rabgef1), a multifunctional protein whose in vivo functions remained unknown until recently, is highly expressed in mouse and human epithelial cells. The aim of this study is to investigate the role of Rabgef1 in intestinal epithelial cells (IECs) and intestinal homeostasis in mice. We performed conditional deletion of Rabgef1 gene using the cre-lox system to obtain mice lacking Rabgef1 specifically in IECs (Rabgef1IEC-KO), under the wild-type (WT) or the colitis-prone Interleukin-10 (Il-10)-deficient background. In addition, we used the CRISPR-Cas9 technology to obtain a murine IEC line deficient in Rabgef1. Rabgef1IEC-KO mice under the WT background did not develop spontaneous intestinal abnormalities but exhibited an altered intestinal microbial composition associated with minor changes in IEC pro-inflammatory gene expression profile. Moreover, Rabgef1IEC-KO mice exhibited an increased susceptibility to inflammation in a dextran sodium sulfate (DSS)-induced model of colitis under the WT background, as well as in a constitutive model of colitis under the Il-10-¬deficient background. In vitro, we showed that mouse IECs lacking Rabgef1 significantly overexpressed several pro-inflammatory cytokines and chemokines as compared to control cells. Taken together, these results support that Rabgef1 acts as a regulator of intestinal homeostasis and inflammation, and that dysregulated Rabgef1 expression could contribute to intestinal barrier dysfunction in inflammatory conditions of the gut. [less ▲]

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See detailRelease of Neutrophils Extracellular Traps as a main trigger for asthma onset
Radermecker, Coraline ULiege; Sabatel, Catherine ULiege; Toussaint, Marie et al

Poster (2017, June 20)

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like ... [more ▼]

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like viral infections and exposition to low doses of lipopolysaccharide (LPS) strongly increase the risk of disease inception. Interestingly, these two particular risk factors both induce a strong recruitment of neutrophils into the lung. Recently, scientists highlighted the ability of neutrophils to form neutrophils extracellular traps (NETs) composed of a network of extracellular DNA associated to anti-microbial peptides. NETs release (or NETosis) is an important component in organism defence against pathogen invasion but has also been identified as initiator of pathophysiological conditions like erythematous systemic lupus, gout and diabetes. In this study, we investigated the role of NETs as potential asthma inducers in specific pro-Th2 environmental risk factors like respiratory viral infections and low LPS doses exposures (also known as hygiene hypothesis). First, we assessed the correlation between respiratory viral infection or low LPS exposure and NETosis using western blot and confocal microscopy analysis. An influenza A infection induced a strong NETs release between day three and seven after viral inoculation whereas exposition to low (100 ng LPS) but not to high (10 µg LPS) LPS doses also promoted NETosis within 24 hours following the exposition. Then we developed two mouse models, a virus-induced asthma model and a model of asthma promoted by exposition to low LPS doses. In these models, only previously infected mice or mice exposed to low LPS doses displayed all the characteristics of allergic asthma following sensitization and challenge to house dust mite (HDM). The role of NETs in asthma onset was then demonstrated using three NETosis inhibitors (DNAse, Cl-amidine and inhibitor of neutrophil elastase) in our models as infected or low LPS doses exposed mice exhibited strong decreased of all key asthma features when treated with NETs inhibitors compared to non-treated mice. Finally, to address how NETs could lead to a TH2 immune response, we analysed by flow cytometry the distinct subpopulations of lung dendritic cells (DCs) in our two mice models. We observed, during the NETs release phase, a recruitment of monocytic derived DCs (moDCs). In conclusion, we have demonstrated an unexpected role for NETs in asthma onset by recruiting lung moDCs. [less ▲]

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See detailLoss of transfer RNA U34 modifying enzymes impairs hematopoietic stem and progenitor cell differentiation and function
Rosu, Adeline ULiege; Bai, Qiang ULiege; Ramery, Eve ULiege et al

Poster (2017, February 03)

Hematopoietic stem and progenitor cells (HSPCs) require fine-tuned protein translation for their normal maintenance and function. Conserved modifications of the wobble uridine base (U34) in transfer RNAs ... [more ▼]

Hematopoietic stem and progenitor cells (HSPCs) require fine-tuned protein translation for their normal maintenance and function. Conserved modifications of the wobble uridine base (U34) in transfer RNAs catalyzed by the Elongator complex are required for optimal protein translation efficacy and fidelity, but their biological importance in mammalian stem and progenitor cells remains largely unexplored. Here, we studied the impact of loss of activity of the catalytic subunit Elp3 of Elongator on HSPC differentiation and function. Hematopoietic-cell-specific depletion of Elp3 in conditional knockout mice resulted in shortened lifespan associated with hematopoietic failure and lymphoma development. Elp3 deletion caused apoptosis of specific bone marrow multipotent progenitors and blocked differentiation of committed progenitors, resulting in blood and bone marrow pancytopenia. In contrast, Elp3-deficient hematopoietic stem cells (HSCs) expanded with age and did not exhaust throughout life, although they were defective in reconstituting hematopoiesis in competitive transplantation assays. Mechanistically, loss of Elp3 did not result in detectable alterations in global protein synthesis rates in any HSPC subset. Rather, Elp3-deficient HSPCs displayed enhanced activity of the stress integrator and apoptosis and cell cycle regulator p53. Thus, this study supports the notion that Elongator activity is required in distinct HSPC subsets to avoid aberrant p53 activation, which otherwise results in discrete loss of function phenotypes in HSCs and downstream progenitors. [less ▲]

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See detailRelease of Neutrophils Extracellular Traps as a main trigger for asthma onset
Radermecker, Coraline ULiege; Sabatel, Catherine ULiege; Toussaint, Marie et al

Conference (2017, January 24)

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like ... [more ▼]

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like viral infections and exposition to low doses of lipopolysaccharide (LPS) strongly increase the risk of disease inception. Interestingly, these two particular risk factors both induce a strong recruitment of neutrophils into the lung. Recently, scientists highlighted the ability of neutrophils to form neutrophils extracellular traps (NETs) composed of a network of extracellular DNA associated to anti-microbial peptides. NETs release (or NETosis) is an important component in organism defence against pathogen invasion but has also been identified as initiator of pathophysiological conditions like erythematous systemic lupus, gout and diabetes. In this study, we investigated the role of NETs as potential asthma inducers in specific pro-Th2 environmental risk factors like respiratory viral infections and low LPS doses exposures (also known as hygiene hypothesis). First, we assessed the correlation between respiratory viral infection or low LPS exposure and NETosis using western blot and confocal microscopy analysis. An influenza A infection induced a strong NETs release between day three and seven after viral inoculation whereas exposition to low (100 ng LPS) but not to high (10 µg LPS) LPS doses also promoted NETosis within 24 hours following the exposition. Then we developed two mouse models, a virus-induced asthma model and a model of asthma promoted by exposition to low LPS doses. In these models, only previously infected mice or mice exposed to low LPS doses displayed all the characteristics of allergic asthma following sensitization and challenge to house dust mite (HDM). The role of NETs in asthma onset was then demonstrated using three NETosis inhibitors (DNAse, Cl-amidine and inhibitor of neutrophil elastase) in our models as infected or low LPS doses exposed mice exhibited strong decreased of all key asthma features when treated with NETs inhibitors compared to non-treated mice. Finally, to address how NETs could lead to a TH2 immune response, we analysed by flow cytometry the distinct subpopulations of lung dendritic cells (DCs) in our two mice models. We observed, during the NETs release phase, a recruitment of monocytic derived DCs (moDCs). In conclusion, we have demonstrated an unexpected role for NETs in asthma onset by recruiting lung moDCs. [less ▲]

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See detailDevelopment and performance assessment of a luminex xMAP(R) direct hybridization assay for the detection and identification of indoor air fungal contamination.
Libert, Xavier; Packeu, Ann; Bureau, Fabrice ULiege et al

in PLoS ONE (2017), 12(3), 0173390

Considered as a public health problem, indoor fungal contamination is generally monitored using classical protocols based on culturing. However, this culture dependency could influence the ... [more ▼]

Considered as a public health problem, indoor fungal contamination is generally monitored using classical protocols based on culturing. However, this culture dependency could influence the representativeness of the fungal population detected in an analyzed sample as this includes the dead and uncultivable fraction. Moreover, culture-based protocols are often time-consuming. In this context, molecular tools are a powerful alternative, especially those allowing multiplexing. In this study a Luminex xMAP(R) assay was developed for the simultaneous detection of 10 fungal species which are most frequently in indoor air and that may cause health problems. This xMAP(R) assay was found to be sensitive, i.e. its limit of detection is ranging between 0.05 and 0.01 ng of gDNA. The assay was subsequently tested with environmental air samples which were also analyzed with a classical protocol. All the species identified with the classical method were also detected with the xMAP(R) assay, however in a shorter time frame. These results demonstrate that the Luminex xMAP(R) fungal assay developed in this study could contribute to the improvement of public health and specifically to the indoor fungal contamination treatment. [less ▲]

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See detailA gammaherpesvirus provides protection against allergic asthma by inducing the replacement of resident alveolar macrophages with regulatory monocytes.
Machiels, Bénédicte ULiege; Dourcy, Mickael ULiege; Xiao, Xue ULiege et al

in Nature Immunology (2017)

The hygiene hypothesis postulates that the recent increase in allergic diseases such as asthma and hay fever observed in Western countries is linked to reduced exposure to childhood infections. Here we ... [more ▼]

The hygiene hypothesis postulates that the recent increase in allergic diseases such as asthma and hay fever observed in Western countries is linked to reduced exposure to childhood infections. Here we investigated how infection with a gammaherpesvirus affected the subsequent development of allergic asthma. We found that murid herpesvirus 4 (MuHV-4) inhibited the development of house dust mite (HDM)-induced experimental asthma by modulating lung innate immune cells. Specifically, infection with MuHV-4 caused the replacement of resident alveolar macrophages (AMs) by monocytes with regulatory functions. Monocyte-derived AMs blocked the ability of dendritic cells to trigger a HDM-specific response by the TH2 subset of helper T cells. Our results indicate that replacement of embryonic AMs by regulatory monocytes is a major mechanism underlying the long-term training of lung immunity after infection. [less ▲]

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See detailHuman papillomavirus oncoproteins induce a reorganization of epithelial-associated gammadelta T cells promoting tumor formation.
Van hede, Dorien ULiege; Polese, Barbara ULiege; Humblet, Chantal ULiege et al

in Proceedings of the National Academy of Sciences of the United States of America (2017), 114(43), 9056-9065

It has been shown that gammadelta T cells protect against the formation of squamous cell carcinoma (SCC) in several models. However, the role of gammadelta T cells in human papillomavirus (HPV)-associated ... [more ▼]

It has been shown that gammadelta T cells protect against the formation of squamous cell carcinoma (SCC) in several models. However, the role of gammadelta T cells in human papillomavirus (HPV)-associated uterine cervical SCC, the third-leading cause of death by cancer in women, is unknown. Here, we investigated the impact of gammadelta T cells in a transgenic mouse model of carcinogenesis induced by HPV16 oncoproteins. Surprisingly, gammadelta T cells promoted the development of HPV16 oncoprotein-induced lesions. HPV16 oncoproteins induced a decrease in epidermal Skint1 expression and the associated antitumor Vgamma5+ gammadelta T cells, which were replaced by gammadelta T-cell subsets (mainly Vgamma6+ gammadeltalowCCR2+CCR6-) actively producing IL-17A. Consistent with a proangiogenic role, gammadelta T cells promoted the formation of blood vessels in the dermis underlying the HPV-induced lesions. In human cervical biopsies, IL-17A+ gammadelta T cells could only be observed at the cancer stage (SCC), where HPV oncoproteins are highly expressed, supporting the clinical relevance of our observations in mice. Overall, our results suggest that HPV16 oncoproteins induce a reorganization of the local epithelial-associated gammadelta T-cell subpopulations, thereby promoting angiogenesis and cancer development. [less ▲]

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See detailHomeostatic Eosinophils: Characteristics and Functions
Marichal, Thomas ULiege; Mesnil, Claire ULiege; Bureau, Fabrice ULiege

in Frontiers in medicine (2017), 4

Eosinophils are typically considered to be specialized effector cells that are recruited to the tissues as a result of T helper type 2 (Th2) cell responses associated with helminth infections or allergic ... [more ▼]

Eosinophils are typically considered to be specialized effector cells that are recruited to the tissues as a result of T helper type 2 (Th2) cell responses associated with helminth infections or allergic diseases such as asthma. Once at the site of injury, eosinophils release their cytotoxic granule proteins as well as preformed cytokines and lipid mediators, contributing to parasite destruction but also to exacerbation of inflammation and tissue damage. Accumulating evidence indicates that, besides their roles in Th2 responses, eosinophils also regulate homeostatic processes at steady state, thereby challenging the exclusive paradigm of the eosinophil as a destructive and inflammatory cell. Indeed, under baseline conditions, eosinophils rapidly leave the bloodstream to enter tissues, mainly the gastrointestinal tract, lungs, adipose tissue, thymus, uterus, and mammary glands, where they regulate a variety of important biological functions, such as immunoregulation, control of glucose homeostasis, protection against obesity, regulation of mammary gland development, and preparation of the uterus for pregnancy. This article provides an overview of the characteristics and functions of these homeostatic eosinophils. [less ▲]

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See detailThe Roles of Spinochromes in Four Shallow Water Tropical Sea Urchins and Their Potential as Bioactive Pharmacological Agents.
Brasseur, Lola; Hennebert, Elise; Fievez, Laurence ULiege et al

in Marine Drugs (2017), 15(6),

Spinochromes are principally known to be involved in sea urchin pigmentation as well as for their potentially interesting pharmacological properties. To assess their biological role in sea urchin ... [more ▼]

Spinochromes are principally known to be involved in sea urchin pigmentation as well as for their potentially interesting pharmacological properties. To assess their biological role in sea urchin physiology, experiments are undertaken on crude extracts from four species and on four isolated spinochromes in order to test their antibacterial, antioxidant, inflammatory and cytotoxic activities. First, the antibacterial assays show that the use of crude extracts as representatives of antibacterial effects of spinochromes are inaccurate. The assays on purified spinochromes showed a decrease in the growth of four strains with an intensity depending on the spinochromes/bacteria system, revealing the participation of spinochromes in the defense system against microorganisms. Secondly, in the 2,2-diphenyl-1-picrylhydrazyl antioxidant assays, spinochromes show an enhanced activity compared to the positive control. This latter observation suggests their involvement in ultraviolet radiation protection. Third, spinochromes present a pro-inflammatory effect on lipopolysaccharide-stimulated macrophages, highlighting their possible implication in the sea urchin immune system. Finally, cytotoxicity assays based on Trypan blue exclusion, performed in view of their possible future applications as drugs, show a weak cytotoxicity of these compounds against human cells. In conclusion, all results confirm the implication of spinochromes in sea urchin defense mechanisms against their external environment and reveal their potential for pharmacological and agronomical industries. [less ▲]

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See detailDiscrimination of three genetically close Aspergillus species by using high resolution melting analysis applied to indoor air as case study.
Libert, Xavier; Packeu, Ann; Bureau, Fabrice ULiege et al

in BMC Microbiology (2017), 17(1), 84

BACKGROUND: Indoor air pollution caused by fungal contamination is suspected to have a public health impact. Monitoring of the composition of the indoor airborne fungal contaminants is therefore important ... [more ▼]

BACKGROUND: Indoor air pollution caused by fungal contamination is suspected to have a public health impact. Monitoring of the composition of the indoor airborne fungal contaminants is therefore important. To avoid problems linked to culture-dependent protocols, molecular methods are increasingly being proposed as an alternative. Among these molecular methods, the polymerase chain reaction (PCR) and the real-time PCR are the most frequently used tools for indoor fungal detection. However, even if these tools have demonstrated their appropriate performance, some of them are not able to discriminate between species which are genetically close. A solution to this could be the use of a post-qPCR high resolution melting (HRM) analysis, which would allow the discrimination of these species based on the highly accurate determination of the difference in melting temperature of the obtained amplicon. In this study, we provide a proof-of-concept for this approach, using a dye adapted version of our previously developed qPCR SYBR(R)Green method to detect Aspergillus versicolor in indoor air, an important airborne fungus in terms of occurrence and cause of health problems. Despite the good performance observed for that qPCR method, no discrimination could previously be made between A. versicolor, Aspergillus creber and Aspergillus sydowii. METHODS: In this study, we developed and evaluated an HRM assay for the discrimination between A. versicolor, Aspergillus creber and Aspergillus sydowii. RESULTS: Using HRM analysis, the discrimination of the 3 Aspergillus species could be made. No false positive, nor false negatives were observed during the performance assessment including 20 strains of Aspergillus. The limit of detection was determined for each species i.e., 0.5 pg of gDNA for A. creber and A. sydowii, and 0.1 pg of gDNA for A. versicolor. The HRM analysis was also successfully tested on environmental samples. CONCLUSION: We reported the development of HRM tools for the discrimination of A. versicolor, A. creber and A. sydowii. However, this study could be considered as a study case demonstrating that HRM based on existing qPCR assays, allows a more accurate identification of indoor air contaminants. This contributes to an improved insight in the diversity of indoor airborne fungi and hence, eventually in the causal link with health problems. [less ▲]

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See detailHost DNA released by NETosis promotes rhinovirus-induced type-2 allergic asthma exacerbation.
Toussaint, Marie; Jackson, David J.; Swieboda, Dawid et al

in Nature Medicine (2017), 23

Respiratory viral infections represent the most common cause of allergic asthma exacerbations. Amplification of the type-2 immune response is strongly implicated in asthma exacerbation, but how virus ... [more ▼]

Respiratory viral infections represent the most common cause of allergic asthma exacerbations. Amplification of the type-2 immune response is strongly implicated in asthma exacerbation, but how virus infection boosts type-2 responses is poorly understood. We report a significant correlation between the release of host double-stranded DNA (dsDNA) following rhinovirus infection and the exacerbation of type-2 allergic inflammation in humans. In a mouse model of allergic airway hypersensitivity, we show that rhinovirus infection triggers dsDNA release associated with the formation of neutrophil extracellular traps (NETs), known as NETosis. We further demonstrate that inhibiting NETosis by blocking neutrophil elastase or by degrading NETs with DNase protects mice from type-2 immunopathology. Furthermore, the injection of mouse genomic DNA alone is sufficient to recapitulate many features of rhinovirus-induced type-2 immune responses and asthma pathology. Thus, NETosis and its associated extracellular dsDNA contribute to the pathogenesis and may represent potential therapeutic targets of rhinovirus-induced asthma exacerbations. [less ▲]

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See detailExposure to Bacterial CpG DNA Protects from Airway Allergic Inflammation by Expanding Regulatory Lung Interstitial Macrophages.
Sabatel, Catherine ULiege; Radermecker, Coraline ULiege; Fievez, Laurence ULiege et al

in Immunity (2017), 46(3), 457-473

Living in a microbe-rich environment reduces the risk of developing asthma. Exposure of humans or mice to unmethylated CpG DNA (CpG) from bacteria reproduces these protective effects, suggesting a major ... [more ▼]

Living in a microbe-rich environment reduces the risk of developing asthma. Exposure of humans or mice to unmethylated CpG DNA (CpG) from bacteria reproduces these protective effects, suggesting a major contribution of CpG to microbe-induced asthma resistance. However, how CpG confers protection remains elusive. We found that exposure to CpG expanded regulatory lung interstitial macrophages (IMs) from monocytes infiltrating the lung or mobilized from the spleen. Trafficking of IM precursors to the lung was independent of CCR2, a chemokine receptor required for monocyte mobilization from the bone marrow. Using a mouse model of allergic airway inflammation, we found that adoptive transfer of IMs isolated from CpG-treated mice recapitulated the protective effects of CpG when administered before allergen sensitization or challenge. IM-mediated protection was dependent on IL-10, given that Il10-/- CpG-induced IMs lacked regulatory effects. Thus, the expansion of regulatory lung IMs upon exposure to CpG might underlie the reduced risk of asthma development associated with a microbe-rich environment. [less ▲]

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