References of "Desmet, Christophe"
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See detailMyeloid Hif1alpha counteracts allergic airway sensitization in mice through macrophage-mediated immunoregulation
Toussaint, Marie ULg; Fievez, Laurence ULg; Drion, Pierre ULg et al

in Abstract book of Keystone Symposium "Myeloid Cells: Regulation and Inflammation" (2013)

Hypoxia Inducible Factor (HIF) has important roles in promoting pro-inflammatory and bactericidal functions in myeloid cells. Conditional genetic ablation of its major subunit Hif1alpha in the myeloid ... [more ▼]

Hypoxia Inducible Factor (HIF) has important roles in promoting pro-inflammatory and bactericidal functions in myeloid cells. Conditional genetic ablation of its major subunit Hif1alpha in the myeloid lineage consequently results in decreased inflammatory responses in classical models of acute inflammation in mice. In contrast, we observed that mice conditionally deficient for Hif1alpha in myeloid cells display enhanced sensitivity to the development of airway allergy to the experimental allergen ovalbumin as well as to house dust mite antigens. Following allergen exposure, these mice indeed developed enhanced allergen-specific T cell responses due to augmented activation of lung dendritic cells. Further analyses supported the idea that upon allergen exposure, MyD88-dependent upregulation of Hif1alpha boosts the expression of the immunosuppressive cytokine Interleukin (IL)-10 by lung interstitial macrophages. Interstitial macrophage-derived IL-10 in turn counteracts allergen-induced lung dendritic cell activation, consequently preventing the development of allergen-specific T cell responses. Thus, this study supports that, in addition to its known pro-inflammatory activities, myeloid Hif1alpha possesses immunoregulatory functions implicated in the prevention of airway allergy. [less ▲]

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See detailMyeloid hypoxia-inducible factor 1alpha prevents airway allergy in mice through macrophage-mediated immunoregulation
Toussaint, Marie ULg; Fievez, Laurence ULg; Drion, Pierre ULg et al

in Mucosal Immunology (2013), 6(3), 485-97

Hypoxia-inducible factor (HIF) has important roles in promoting pro-inflammatory and bactericidal functions in myeloid cells. Conditional genetic ablation of its major subunit Hif1alpha in the myeloid ... [more ▼]

Hypoxia-inducible factor (HIF) has important roles in promoting pro-inflammatory and bactericidal functions in myeloid cells. Conditional genetic ablation of its major subunit Hif1alpha in the myeloid lineage consequently results in decreased inflammatory responses in classical models of acute inflammation in mice. By contrast, we report here that mice conditionally deficient for Hif1alpha in myeloid cells display enhanced sensitivity to the development of airway allergy to experimental allergens and house-dust mite antigens. We support that upon allergen exposure, MyD88-dependent upregulation of Hif1alpha boosts the expression of the immunosuppressive cytokine interleukin (IL)-10 by lung interstitial macrophages (IMs). Hif1alpha-dependent IL-10 secretion is required for IMs to block allergen-induced dendritic cell activation and consequently for preventing the development of allergen-specific T-helper cell responses upon allergen exposure. Thus, this study supports that, in addition to its known pro-inflammatory activities, myeloid Hif1alpha possesses immunoregulatory functions implicated in the prevention of airway allergy. [less ▲]

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See detailNeutrophil Extracellular Traps (NET) Entrap and Kill Borrelia burgdorferi sensu stricto Spirochetes and Are not Affected by Ixodes ricinus Tick Saliva.
MENTEN-DEDOYART, Catherine ULg; Faccinetto, Céline; Golovchenko, Maryna et al

in Journal of Immunology (2012), 189(11), 5393-5401

Lyme disease is a pathology caused by members of the Borrelia burgdorferi sensu lato (s.l.) complex, most often by B. burgdorferi sensu stricto (s.s.). They are transmitted mainly by Ixodes ricinus ticks ... [more ▼]

Lyme disease is a pathology caused by members of the Borrelia burgdorferi sensu lato (s.l.) complex, most often by B. burgdorferi sensu stricto (s.s.). They are transmitted mainly by Ixodes ricinus ticks. After a few hours of infestation, neutrophils massively infiltrate the bite site. They can kill Borrelia via phagocytosis, oxidative burst and hydrolytic enzymes. However, factors in tick saliva promote propagation of the bacteria in the host even in the presence of a large number of neutrophils. Neutrophil extracellular trap (NET) consists in the extrusion of the neutrophil’s own DNA, forming traps that can retain and kill bacteria. The production of reactive oxygen species (ROS) is apparently associated with the onset of NEtosis. Here we describe NETs formation at the tick bite site in vivo in mice. We show that Borrelia burgdorferi s.s. spirochetes become trapped and killed by NETs in humans and that the bacteria do not seem to release significant nucleases to evade this process. Saliva from I. ricinus did not affect NET formation by human neutrophiles or it stability. However, it strongly decreased neutrophil ROS production, suggesting that a strong decrease of hydrogen peroxide does not affect NET formation. Finally, round bodies were observed trapped in NETs, some of them staining as live cells. This observation could help contribute to a better explanation of erythema migrans. [less ▲]

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See detailInvestigation of the effect of exercise on the innate immunity in horses
Frellstedt, Linda ULg; Gosset, Philippe; Desmet, Christophe ULg et al

Poster (2012, October 19)

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See detailFra-1 target genes as drug targets for treating cancer
Peeper, Daniel Simon; Desmet, Christophe ULg; Reyal, Fabien

Patent (2012)

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See detailRelease and Innate detection of host cell DNA mediates the adjuvant effects of aluminum salts on adaptive responses
Marichal, Thomas ULg; Ohata, Keichii; Bedoret, Denis et al

in Proceedings of the 1St Winter School Immunology (2012, January)

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See detailL'ADN du soi, allie du systeme immunitaire pour la fonction adjuvante de l'alun
Marichal, Thomas ULg; Bureau, Fabrice ULg; Desmet, Christophe ULg

in Medecine Sciences : M/S (2012), 28(1), 31-3

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See detailResident CD11b(+)Ly6C(-) Lung Dendritic Cells Are Responsible for Allergic Airway Sensitization to House Dust Mite in Mice.
Mesnil, Claire ULg; Sabatel, Catherine ULg; Marichal, Thomas ULg et al

in PLoS ONE (2012), 7(12), 53242

Conventional dendritic cells (DCs) are considered to be the prime initiators of airway allergy. Yet, it remains unclear whether specific DC subsets are preferentially involved in allergic airway ... [more ▼]

Conventional dendritic cells (DCs) are considered to be the prime initiators of airway allergy. Yet, it remains unclear whether specific DC subsets are preferentially involved in allergic airway sensitization. Here, we systematically assessed the respective pro-allergic potential of individually sorted lung DC subsets isolated from house dust mite antigen (HDM)-treated donor mice, following transfer to naive recipients. Transfer of lung CD11c(+)CD11b(+) DCs, but not CD11c(+)CD11b(-)CD103(+) DCs, was sufficient to prime airway allergy. The CD11c(+)CD11b(+) DC subpopulation was composed of CD11c(+)CD11b(+)Ly6C(+) inflammatory monocyte-derived cells, whose numbers increase in the lungs following HDM exposure, and of CD11c(+)CD11b(+)Ly6C(-) DCs, which remain stable. Counterintuitively, only CD11c(+)CD11b(+)Ly6C(-) DCs, and not CD11c(+)CD11b(+)Ly6C(+) DCs, were able to convey antigen to the lymph nodes and induce adaptive T cell responses and subsequent airway allergy. Our results thus support that lung resident non-inflammatory CD11c(+)CD11b(+)Ly6C(-) DCs are the essential inducers of allergic airway sensitization to the common aeroallergen HDM in mice. [less ▲]

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See detailIncreased hypoxia-inducible factor 1alpha expression in lung cells of horses with recurrent airway obstruction.
Toussaint, Marie ULg; Fievez, Laurence ULg; Desmet, Christophe ULg et al

in BMC Veterinary Research (2012), 8(1), 64

ABSTRACT: BACKGROUND: Recurrent airway obstruction (RAO, also known as equine heaves) is an inflammatory condition caused by exposure of susceptible horses to organic dusts in hay. The immunological ... [more ▼]

ABSTRACT: BACKGROUND: Recurrent airway obstruction (RAO, also known as equine heaves) is an inflammatory condition caused by exposure of susceptible horses to organic dusts in hay. The immunological processes responsible for the development and the persistence of airway inflammation are still largely unknown. Hypoxia-inducible factor (Hif) is mainly known as a major regulator of energy homeostasis and cellular adaptation to hypoxia. More recently however, Hif also emerged as an essential regulator of innate immune responses. Here, we aimed at investigating the potential involvement of Hif1-alpha in myeloid cells in horse with recurrent airway obstruction. RESULTS: In vitro, we observed that Hif is expressed in equine myeloid cells after hay dust stimulation and regulates genes such as tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8) and vascular endothelial growth factor A (VEGF-A). We further showed in vivo that airway challenge with hay dust upregulated Hif1-alpha mRNA expression in myeloid cells from the bronchoalveolar lavage fluid (BALF) of healthy and RAO-affected horses, with a more pronounced effect in cells from RAO-affected horses. Finally, Hif1-alpha mRNA expression in BALF cells from challenged horses correlated positively with lung dysfunction. CONCLUSION: Taken together, our results suggest an important role for Hif1-alpha in myeloid cells during hay dust-induced inflammation in horses with RAO. We therefore propose that future research aiming at functional inactivation of Hif1 in lung myeloid cells could open new therapeutic perspectives for RAO. [less ▲]

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See detailNucleic acid sensing at the interface between innate and adaptive immunity in vaccination
Desmet, Christophe ULg; Ishii, Ken J.

in Nature Reviews. Immunology (2012), 12(7), 479-491

The demand is currently high for new vaccination strategies, particularly to help combat problematic intracellular pathogens, such as HIV and malarial parasites. In the past decade, the identification of ... [more ▼]

The demand is currently high for new vaccination strategies, particularly to help combat problematic intracellular pathogens, such as HIV and malarial parasites. In the past decade, the identification of host receptors that recognize pathogen-derived nucleic acids has revealed an essential role for nucleic acid sensing in the triggering of immunity to intracellular pathogens. This Review first addresses our current understanding of the nucleic acid-sensing immune machinery. We then explain how the study of nucleic acid-sensing mechanisms not only has revealed their central role in driving the responses mediated by many current vaccines, but is also revealing how they could be harnessed for the design of new vaccines. [less ▲]

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See detailMyeloid HIF-1alpha prevents airway allergy in mice by promoting macrophage-mediated immunosuppression
Toussaint, Marie ULg; Fievez, Laurence ULg; Lekeux, Pierre ULg et al

in Proceedings of the 1st Scientific Meeting of the Faculty of Veterinary Medicine (2011, December 09)

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See detailDNA released from dying host cells mediates aluminum adjuvant activity
Marichal, Thomas ULg; Ohata, Keiichi; Bedoret, Denis et al

in Nature Medicine (2011), 17

Aluminum-based adjuvants (alum) are widely used in human vaccination, although little is understood of their mechanisms of action. Here, we report that, in mice, alum causes the release of host cell DNA ... [more ▼]

Aluminum-based adjuvants (alum) are widely used in human vaccination, although little is understood of their mechanisms of action. Here, we report that, in mice, alum causes the release of host cell DNA, which acts as a potent endogenous immunostimulatory signal mediating alum adjuvant activity. Furthermore, we propose that host DNA signaling differentially regulates IgE and IgG1 production upon alum immunization. Indeed, we support that host DNA induces primary B cell responses, including IgG1 production, through Interferon Response Factor (Irf) 3-independent mechanisms, and 'canonical' type 2 T cell responses associated with IgE isotype switching and peripheral effector responses through Irf3-dependent mechanisms. The finding that host cell DNA is a damage-associated molecular pattern relaying alum adjuvant activity may thus help in the comprehension of the mechanisms of action of current vaccines and in the design of novel adjuvants. [less ▲]

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See detailInterferon Response Factor-3 is essential for house dust mite-induced airway allergy
Marichal, Thomas ULg; Bedoret Denis; Mesnil Claire et al

in Proceedings of the Belgian Thoracic Society Annual Meeting (2011, May 23)

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See detailIRF3 is essential for house dust mite-induced airway allergy in mice
Marichal, Thomas ULg; Bedoret, Denis; Mesnil, Claire ULg et al

in Proceedings GIGA-Day 2011 (2011, May)

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See detailSirtuin 1 Promotes Th2 Responses and Airway Allergy by Repressing Peroxisome Proliferator-Activated Receptor-γ Activity in Dendritic Cells
Legutko, Agnieszka; Marichal, Thomas ULg; Fievez, Laurence ULg et al

in Journal of Immunology (2011), 187(9), 4517-4529

Sirtuins are a unique class of NAD+-dependent deacetylases that regulate diverse biological functions such as aging, metabolism, and stress resistance. Recently, it has been shown that sirtuins may have ... [more ▼]

Sirtuins are a unique class of NAD+-dependent deacetylases that regulate diverse biological functions such as aging, metabolism, and stress resistance. Recently, it has been shown that sirtuins may have anti-inflammatory activities by inhibiting proinflammatory transcription factors such as NF-κB. In contrast, we report in this study that pharmacological inhibition of sirtuins dampens adaptive Th2 responses and subsequent allergic inflammation by interfering with lung dendritic cell (DC) function in a mouse model of airway allergy. Using genetic engineering, we demonstrate that sirtuin 1 represses the activity of the nuclear receptor peroxisome proliferator-activated receptor-γ in DCs, thereby favoring their maturation toward a pro-Th2 phenotype. This study reveals a previously unappreciated function of sirtuin 1 in the regulation of DC function and Th2 responses, thus shedding new light on our current knowledge on the regulation of inflammatory processes by sirtuins. [less ▲]

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See detailADAM-8, a metalloproteinase, drives acute allergen-induced airway inflammation
Paulissen, Geneviève ULg; Rocks, Natacha ULg; Guéders, Maud ULg et al

in European Journal of Immunology (2011), 41(2), 380-91

Asthma is a complex disease linked to various pathophysiological events including the activity of proteinases. The multifunctional A Disintegrin And Metalloproteinases (ADAMs) displaying the ability to ... [more ▼]

Asthma is a complex disease linked to various pathophysiological events including the activity of proteinases. The multifunctional A Disintegrin And Metalloproteinases (ADAMs) displaying the ability to cleave membrane-bound mediators or cytokines appear to be key mediators in various inflammatory processes. In the present study, we have investigated ADAM-8 expression and production in a mouse model of allergen-induced airway inflammation. In allergen-exposed animals, increased expression of ADAM-8 was found in the lung parenchyma and in dendritic cells purified from the lungs. The potential role of ADAM-8 in the development of allergen-induced airway inflammation was further investigated by the use of an anti-ADAM-8 antibody and ADAM-8 knock-out animals. We observed a decrease in allergen-induced acute inflammation both in BALF and the peribronchial area in anti-ADAM-8 antibody-treated mice and in ADAM-8 deficient mice (ADAM-8-/-) after allergen exposure. ADAM-8 depletion led to a significant decrease of the CD11c+ lung dendritic cells. We also report lower levels of CCL11 and CCL22 production in antibody-treated mice and ADAM-8-/- mice that might be explained by decreased eosinophilic inflammation and lower numbers of dendritic cells, respectively. In conclusion, ADAM-8 appears to favour allergen-induced acute airway inflammation by promoting dendritic cell recruitment and CCL11 and CCL22 production. [less ▲]

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