48 research outputs found
MFGE8 does not influence chorio-retinal homeostasis or choroidal neovascularization in vivo
Purpose: Milk fat globule-epidermal growth factor-factor VIII (MFGE8) is necessary for diurnal outer segment phagocytosis and promotes VEGF-dependent neovascularization. The prevalence of two single nucleotide polymorphisms (SNP) in MFGE8 was studied in two exsudative or âwetâ Age-related Macular Degeneration (AMD) groups and two corresponding control groups. We studied the effect of MFGE8 deficiency on retinal homeostasis with age and on choroidal neovascularization (CNV) in mice.
Methods: The distribution of the SNP (rs4945 and rs1878326) of MFGE8 was analyzed in two groups of patients with âwetâ AMD and their age-matched controls from Germany and France. MFGE8-expressing cells were identified in Mfge8+/â mice expressing Ă-galactosidase. Aged Mfge8+/â and Mfge8â/â mice were studied by funduscopy, histology, electron microscopy, scanning electron microscopy of vascular corrosion casts of the choroid, and after laser-induced CNV.
Results: rs1878326 was associated with AMD in the French and German group. The Mfge8 promoter is highly active in photoreceptors but not in retinal pigment epithelium cells. Mfge8â/â mice did not differ from controls in terms of fundus appearance, photoreceptor cell layers, choroidal architecture or laser-induced CNV. In contrast, the Bruch's membrane (BM) was slightly but significantly thicker in Mfge8â/â mice as compared to controls.
Conclusions: Despite a reproducible minor increase of rs1878326 in AMD patients and a very modest increase in BM in Mfge8â/â mice, our data suggests that MFGE8 dysfunction does not play a critical role in the pathogenesis of AMD
Role of chemokines in monocyte mobilization during atherosclerosis
: LâathĂ©rosclĂ©rose est une maladie inflammatoire chronique des grosses artĂšres Ă localisation intimale. Elle est probablement la rĂ©sultante dâune rĂ©action inflammatoire mal contrĂŽlĂ©e ayant pour but initial dâĂ©liminer lâaccumulation anormale de lipides au niveau de lâintima. Cette Ă©limination est exercĂ© par les monocytes/macrophages, dont lâinfiltration et lâaccumulation au niveau des lĂ©sions sont une Ă©tape cruciale de lâinflammation chronique locale provoquant en particulier la production de cytokines.Les mĂ©canismes molĂ©culaires responsables de cette accumulation monocytaire impliquent notamment les chimiokines et leurs rĂ©cepteurs, acteurs clĂ©s de la mobilisation des leucocytes. Les souris gĂ©nĂ©tiquement invalidĂ©es pour certaines chimiokines comme CCL2 et CX3CL1 ou pour leurs rĂ©cepteurs respectifs sont partiellement protĂ©gĂ©es de lâathĂ©rosclĂ©rose. Par ailleurs, chez lâhomme, des variations gĂ©nĂ©tiques de CX3CR1 sont associĂ©es Ă une rĂ©duction du risque dâaccidents cardiovasculaires. Lâensemble de ces rĂ©sultats indiquent un rĂŽle clĂ© des chimiokines inflammatoires dans lâathĂ©rogenĂšse.Lâobjectif de cette thĂšse Ă©tait de tester lâutilisation dâinhibiteurs des rĂ©cepteurs de chimiokines comme outils thĂ©rapeutiques contre lâathĂ©rosclĂ©rose. Dans ce but, notre laboratoire a dĂ©veloppĂ© une molĂ©cule aux propriĂ©tĂ©s antagonistes du rĂ©cepteur CX3CR1, marqueur utilisĂ© pour la caractĂ©risation phĂ©notypique des monocytes. Nos travaux sur deux modĂšles murins dâathĂ©rosclĂ©rose mettent en Ă©vidence que le blocage de CX3CR1 par notre antagoniste rĂ©duit la taille des plaques dâathĂ©rosclĂ©rose formĂ©es sans modifier leur composition cellulaire ni le taux de cholestĂ©rol plasmatique circulant. Cette diminution est corrĂ©lĂ©e Ă une diminution du nombre dâune sous-population monocytaire circulante spĂ©cifique, ainsi quâĂ une diminution de leurs propriĂ©tĂ©s dâadhĂ©rence et de survie. Dâun point de vue curatif, lâantagoniste de CX3CR1 est capable de limiter la progression des plaques dâathĂ©rosclĂ©rose sans la prĂ©venir totalement.Lâutilisation dâun outil ciblant spĂ©cifiquement le rĂ©cepteur CX3CR1 nous Ă permis dâune part de mieux comprendre le rĂŽle de ce dernier dans les processus de monocytose et dâathĂ©rogenĂšse et dâautres part dâĂ©valuer la faisabilitĂ© dâapproches thĂ©rapeutiques visant Ă limiter le nombre de monocytes infiltrant les lĂ©sions dâathĂ©rosclĂ©rose. Les perspectives de ces travaux consistent dâune part Ă approfondir encore le rĂŽle de CX3CR1 dans la mobilisation monocytaire, notamment au niveau de la moelle osseuse, et dâautre Ă utiliser lâantagoniste testĂ© en association avec dâautres drogues ciblant les rĂ©cepteurs de chimiokines impliquĂ©s dans lâathĂ©rogenĂšse, tels que CCR2 et CCR5.Atherosclerosis account for nearly 30% of death in industrialized countries. It is a chronic inflammatory disease of the large arteries intima. It has been suggested that it is the result of an uncontrolled inflammatory reaction secondary to an abnormal accumulation of lipids in the intima. The lipid clearance is performed by monocytes / macrophages, Their infiltration and accumulation in atherosclerotic lesions is a critical step of a local chronic inflammation associated with an increased production of cytokines. The molecular mechanisms of the generation of atherosclerotic lesions involve monocytes, chemokines and their receptors which are key players controlling leukocytes mobilization. Mice genetically invalidated for chemokines such as CCL2 and/or CX3CL1 or their respective receptors are partially protected from atherosclerosis. Furthermore, in humans, genetic polymorphisms of CX3CR1 are associated with a reduced risk of cardiovascular events. Taken together, these results highlight a key role for inflammatory chemokines in atherogenesis. The aim of this thesis was to investigate wether inhibitors of chemokine receptors could play a role as therapeutic tools against atherosclerosis. To this end, our laboratory had developed an antagonist of CX3CR1, a crucial phenotypic and functional marker of monocytes. Our work, on two murine models of atherosclerosis, demonstrates that blocking CX3CR1 by our antagonist reduces the size of atherosclerotic lesions. This decrease is correlated with a lower number of circulating inflammatory monocytes, as well as a decrease in their adhesion and survival properties. Therefore, CX3CR1 antagonist coud be able to limit the progression of atherosclerotic plaques. Targeting CX3CR1 allowed us to understand the role of this receptor in the pathophysiology of atherogenesis by its effects on circulating inflammatory monocytes and to evaluate the feasibility of the use of this antagonist as a therapeutic tool to reduce atherosclerotic lesions. Perspectives of this work are firstly to deepen the role of CX3CR1 in monocyte mobilization, especially from the bone marrow, and secondly to test this antagonist in combination with others drugs targeting chemokine receptors involved in atherogenesis, such as CCR2 and CCR5 in order to better control the evolution of atherosclerotic lesions
RĂŽle des chimiokines dans la mobilisation monocytaire au cours de lâathĂ©rosclĂ©rose
Atherosclerosis account for nearly 30% of death in industrialized countries. It is a chronic inflammatory disease of the large arteries intima. It has been suggested that it is the result of an uncontrolled inflammatory reaction secondary to an abnormal accumulation of lipids in the intima. The lipid clearance is performed by monocytes / macrophages, Their infiltration and accumulation in atherosclerotic lesions is a critical step of a local chronic inflammation associated with an increased production of cytokines. The molecular mechanisms of the generation of atherosclerotic lesions involve monocytes, chemokines and their receptors which are key players controlling leukocytes mobilization. Mice genetically invalidated for chemokines such as CCL2 and/or CX3CL1 or their respective receptors are partially protected from atherosclerosis. Furthermore, in humans, genetic polymorphisms of CX3CR1 are associated with a reduced risk of cardiovascular events. Taken together, these results highlight a key role for inflammatory chemokines in atherogenesis. The aim of this thesis was to investigate wether inhibitors of chemokine receptors could play a role as therapeutic tools against atherosclerosis. To this end, our laboratory had developed an antagonist of CX3CR1, a crucial phenotypic and functional marker of monocytes. Our work, on two murine models of atherosclerosis, demonstrates that blocking CX3CR1 by our antagonist reduces the size of atherosclerotic lesions. This decrease is correlated with a lower number of circulating inflammatory monocytes, as well as a decrease in their adhesion and survival properties. Therefore, CX3CR1 antagonist coud be able to limit the progression of atherosclerotic plaques. Targeting CX3CR1 allowed us to understand the role of this receptor in the pathophysiology of atherogenesis by its effects on circulating inflammatory monocytes and to evaluate the feasibility of the use of this antagonist as a therapeutic tool to reduce atherosclerotic lesions. Perspectives of this work are firstly to deepen the role of CX3CR1 in monocyte mobilization, especially from the bone marrow, and secondly to test this antagonist in combination with others drugs targeting chemokine receptors involved in atherogenesis, such as CCR2 and CCR5 in order to better control the evolution of atherosclerotic lesions.: LâathĂ©rosclĂ©rose est une maladie inflammatoire chronique des grosses artĂšres Ă localisation intimale. Elle est probablement la rĂ©sultante dâune rĂ©action inflammatoire mal contrĂŽlĂ©e ayant pour but initial dâĂ©liminer lâaccumulation anormale de lipides au niveau de lâintima. Cette Ă©limination est exercĂ© par les monocytes/macrophages, dont lâinfiltration et lâaccumulation au niveau des lĂ©sions sont une Ă©tape cruciale de lâinflammation chronique locale provoquant en particulier la production de cytokines.Les mĂ©canismes molĂ©culaires responsables de cette accumulation monocytaire impliquent notamment les chimiokines et leurs rĂ©cepteurs, acteurs clĂ©s de la mobilisation des leucocytes. Les souris gĂ©nĂ©tiquement invalidĂ©es pour certaines chimiokines comme CCL2 et CX3CL1 ou pour leurs rĂ©cepteurs respectifs sont partiellement protĂ©gĂ©es de lâathĂ©rosclĂ©rose. Par ailleurs, chez lâhomme, des variations gĂ©nĂ©tiques de CX3CR1 sont associĂ©es Ă une rĂ©duction du risque dâaccidents cardiovasculaires. Lâensemble de ces rĂ©sultats indiquent un rĂŽle clĂ© des chimiokines inflammatoires dans lâathĂ©rogenĂšse.Lâobjectif de cette thĂšse Ă©tait de tester lâutilisation dâinhibiteurs des rĂ©cepteurs de chimiokines comme outils thĂ©rapeutiques contre lâathĂ©rosclĂ©rose. Dans ce but, notre laboratoire a dĂ©veloppĂ© une molĂ©cule aux propriĂ©tĂ©s antagonistes du rĂ©cepteur CX3CR1, marqueur utilisĂ© pour la caractĂ©risation phĂ©notypique des monocytes. Nos travaux sur deux modĂšles murins dâathĂ©rosclĂ©rose mettent en Ă©vidence que le blocage de CX3CR1 par notre antagoniste rĂ©duit la taille des plaques dâathĂ©rosclĂ©rose formĂ©es sans modifier leur composition cellulaire ni le taux de cholestĂ©rol plasmatique circulant. Cette diminution est corrĂ©lĂ©e Ă une diminution du nombre dâune sous-population monocytaire circulante spĂ©cifique, ainsi quâĂ une diminution de leurs propriĂ©tĂ©s dâadhĂ©rence et de survie. Dâun point de vue curatif, lâantagoniste de CX3CR1 est capable de limiter la progression des plaques dâathĂ©rosclĂ©rose sans la prĂ©venir totalement.Lâutilisation dâun outil ciblant spĂ©cifiquement le rĂ©cepteur CX3CR1 nous Ă permis dâune part de mieux comprendre le rĂŽle de ce dernier dans les processus de monocytose et dâathĂ©rogenĂšse et dâautres part dâĂ©valuer la faisabilitĂ© dâapproches thĂ©rapeutiques visant Ă limiter le nombre de monocytes infiltrant les lĂ©sions dâathĂ©rosclĂ©rose. Les perspectives de ces travaux consistent dâune part Ă approfondir encore le rĂŽle de CX3CR1 dans la mobilisation monocytaire, notamment au niveau de la moelle osseuse, et dâautre Ă utiliser lâantagoniste testĂ© en association avec dâautres drogues ciblant les rĂ©cepteurs de chimiokines impliquĂ©s dans lâathĂ©rogenĂšse, tels que CCR2 et CCR5
RÎle des chimiokines dans la mobilisation monocytaire au cours de l'athérosclérose
: L athérosclérose est une maladie inflammatoire chronique des grosses artÚres à localisation intimale. Elle est probablement la résultante d une réaction inflammatoire mal contrÎlée ayant pour but initial d éliminer l accumulation anormale de lipides au niveau de l intima. Cette élimination est exercé par les monocytes/macrophages, dont l infiltration et l accumulation au niveau des lésions sont une étape cruciale de l inflammation chronique locale provoquant en particulier la production de cytokines.Les mécanismes moléculaires responsables de cette accumulation monocytaire impliquent notamment les chimiokines et leurs récepteurs, acteurs clés de la mobilisation des leucocytes. Les souris génétiquement invalidées pour certaines chimiokines comme CCL2 et CX3CL1 ou pour leurs récepteurs respectifs sont partiellement protégées de l athérosclérose. Par ailleurs, chez l homme, des variations génétiques de CX3CR1 sont associées à une réduction du risque d accidents cardiovasculaires. L ensemble de ces résultats indiquent un rÎle clé des chimiokines inflammatoires dans l athérogenÚse.L objectif de cette thÚse était de tester l utilisation d inhibiteurs des récepteurs de chimiokines comme outils thérapeutiques contre l athérosclérose. Dans ce but, notre laboratoire a développé une molécule aux propriétés antagonistes du récepteur CX3CR1, marqueur utilisé pour la caractérisation phénotypique des monocytes. Nos travaux sur deux modÚles murins d athérosclérose mettent en évidence que le blocage de CX3CR1 par notre antagoniste réduit la taille des plaques d athérosclérose formées sans modifier leur composition cellulaire ni le taux de cholestérol plasmatique circulant. Cette diminution est corrélée à une diminution du nombre d une sous-population monocytaire circulante spécifique, ainsi qu à une diminution de leurs propriétés d adhérence et de survie. D un point de vue curatif, l antagoniste de CX3CR1 est capable de limiter la progression des plaques d athérosclérose sans la prévenir totalement.L utilisation d un outil ciblant spécifiquement le récepteur CX3CR1 nous à permis d une part de mieux comprendre le rÎle de ce dernier dans les processus de monocytose et d athérogenÚse et d autres part d évaluer la faisabilité d approches thérapeutiques visant à limiter le nombre de monocytes infiltrant les lésions d athérosclérose. Les perspectives de ces travaux consistent d une part à approfondir encore le rÎle de CX3CR1 dans la mobilisation monocytaire, notamment au niveau de la moelle osseuse, et d autre à utiliser l antagoniste testé en association avec d autres drogues ciblant les récepteurs de chimiokines impliqués dans l athérogenÚse, tels que CCR2 et CCR5.Atherosclerosis account for nearly 30% of death in industrialized countries. It is a chronic inflammatory disease of the large arteries intima. It has been suggested that it is the result of an uncontrolled inflammatory reaction secondary to an abnormal accumulation of lipids in the intima. The lipid clearance is performed by monocytes / macrophages, Their infiltration and accumulation in atherosclerotic lesions is a critical step of a local chronic inflammation associated with an increased production of cytokines. The molecular mechanisms of the generation of atherosclerotic lesions involve monocytes, chemokines and their receptors which are key players controlling leukocytes mobilization. Mice genetically invalidated for chemokines such as CCL2 and/or CX3CL1 or their respective receptors are partially protected from atherosclerosis. Furthermore, in humans, genetic polymorphisms of CX3CR1 are associated with a reduced risk of cardiovascular events. Taken together, these results highlight a key role for inflammatory chemokines in atherogenesis. The aim of this thesis was to investigate wether inhibitors of chemokine receptors could play a role as therapeutic tools against atherosclerosis. To this end, our laboratory had developed an antagonist of CX3CR1, a crucial phenotypic and functional marker of monocytes. Our work, on two murine models of atherosclerosis, demonstrates that blocking CX3CR1 by our antagonist reduces the size of atherosclerotic lesions. This decrease is correlated with a lower number of circulating inflammatory monocytes, as well as a decrease in their adhesion and survival properties. Therefore, CX3CR1 antagonist coud be able to limit the progression of atherosclerotic plaques. Targeting CX3CR1 allowed us to understand the role of this receptor in the pathophysiology of atherogenesis by its effects on circulating inflammatory monocytes and to evaluate the feasibility of the use of this antagonist as a therapeutic tool to reduce atherosclerotic lesions. Perspectives of this work are firstly to deepen the role of CX3CR1 in monocyte mobilization, especially from the bone marrow, and secondly to test this antagonist in combination with others drugs targeting chemokine receptors involved in atherogenesis, such as CCR2 and CCR5 in order to better control the evolution of atherosclerotic lesions.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF
Athérosclérose : sur la piste des chimiokines
En plus des troubles du mĂ©tabolisme des lipides bien connus, lâathĂ©rosclĂ©rose se
caractérise par une inflammation chronique des grosses artÚres qui se traduit notamment
par le recrutement des monocytes au sein de la paroi artérielle. à ce titre, de nombreux
travaux chez lâHomme et la souris, montrent que les chimiokines et leurs rĂ©cepteurs,
responsables de la redistribution tissulaire des leucocytes sanguins, sont trĂšs fortement
impliquĂ©s dans les Ă©tapes de mise en place et de progression de lâathĂ©rosclĂ©rose. Ainsi,
lâutilisation de modĂšles murins a notamment mis en Ă©vidence le rĂŽle pro-athĂ©rogĂšne des
couples récepteur/ligand CCR2/CCL2, CX3CR1/CX3CL1 et CCR5/CCL5 dans les différentes étapes
de lâathĂ©rogenĂšse et le rĂŽle athĂ©ro-protecteur dâautres couples comme CCR1/CCL5 et
CXCR6/CXCL16. LâintĂ©gration au niveau cellulaire des divers signaux du rĂ©seau
chimiokinique renforce la complexité des processus de recrutement des leucocytes dans la
zone lĂ©sionnelle. De plus, la capacitĂ© des chimiokines Ă moduler lâathĂ©rogenĂšse ne semble
pas exclusivement liée à leur propriété chimio-attractante mais aussi à leur action sur
lâhomĂ©ostasie leucocytaire. Ces molĂ©cules sont donc devenues des cibles thĂ©rapeutiques
contre lâathĂ©rosclĂ©rose et plus largement pour le traitement des pathologies
inflammatoires. Cette revue se centre principalement sur les chimiokines et leurs
récepteurs impliqués dans les toutes premiÚres étapes de recrutement des monocytes
sanguins et dresse un état des lieux de la recherche actuelle sur ces acteurs moléculaires
de lâinflammation
Targeted delivery of LXR-agonists to atherosclerotic lesions mediated by polydiacetylene micelles
International audienceWe report the development of compact and stabilized micelles incorporating a synthetic LXR agonist prodrug for the passive targeting of atherosclerotic lesions and therapeutic intervention. In vivo studies showed that..
In vivo imaging reveals a pioneer wave of monocyte recruitment into mouse skin wounds
The cells of the mononuclear phagocyte system are essential for the correct healing of adult skin wounds, but their specific functions remain ill-defined. The absence of granulation tissue immediately after skin injury makes it challenging to study the role of mononuclear phagocytes at the initiation of this inflammatory stage. To study their recruitment and migratory behavior within the wound bed, we developed a new model for real-time in vivo imaging of the wound, using transgenic mice that express green and cyan fluorescent proteins and specifically target monocytes. Within hours after the scalp injury, monocytes invaded the wound bed. The complete abrogation of this infiltration in monocyte-deficient CCR2(-/-) mice argues for the involvement of classical monocytes in this process. Monocyte infiltration unexpectedly occurred as early as neutrophil recruitment did and resulted from active release from the bloodstream toward the matrix through microhemorrhages rather than transendothelial migration. Monocytes randomly scouted around the wound bed, progressively slowed down, and stopped. Our approach identified and characterized a rapid and earlier than expected wave of monocyte infiltration and provides a novel framework for investigating the role of these cells during early stages of wound healing
CD8+ Tumor-Infiltrating T Cells Are Trapped in the Tumor-Dendritic Cell Network
Chemotherapy enhances the antitumor adaptive immune T cell response, but the immunosuppressive tumor environment often dominates, resulting in cancer relapse. Antigen-presenting cells such as tumor-associated macrophages (TAMs) and tumor dendritic cells (TuDCs) are the main protagonists of tumor-infiltrating lymphocyte (TIL) immuno-suppression. TAMs have been widely investigated and are associated with poor prognosis, but the immuno-suppressive activity of TuDCs is less well understood. We performed two-photon imaging of the tumor tissue to examine the spatiotemporal interactions between TILs and TuDCs after chemotherapy. In a strongly immuno-suppressive murine tumor model, cyclophosphamide-mediated chemotherapy transiently enhanced the antitumor activity of adoptively transferred ovalbumin-specific CD8+ T cell receptor transgenic T cells (OTI) but barely affected TuDC compartment within the tumor. Time lapse imaging of living tumor tissue showed that TuDCs are organized as a mesh with dynamic interconnections. Once infiltrated into the tumor parenchyma, OTI T cells make antigen-specific and long-lasting contacts with TuDCs. Extensive analysis of TIL infiltration on histologic section revealed that after chemotherapy the majority of OTI T cells interact with TuDCs and that infiltration is restricted to TuDC-rich areas. We propose that the TuDC network exerts antigen-dependent unproductive retention that trap T cells and limit their antitumor effectiveness
An engineered CX3CR1 antagonist endowed with anti-inflammatory activity
Chemokines are mainly involved in the recruitment of leukocytes into tissues, a key feature of inflammation. Through its unique receptor CX3CR1, the chemokine CX3CL1 participates in diverse inflammatory processes including arterial atherosclerosis and cerebral or renal inflammation. Using a phage display strategy, we engineered a hCX3CL1 analog (named F1) with a modified N terminus. F1 bound specifically to cells expressing hCX3CR1 and had a K(d) value close to that of native CX3CL1. F1 was not a signaling molecule and did not induce chemotaxis, calcium flux, or CX3CR1 internalization. However, it potently inhibited the CX3CL1-induced calcium flux and chemotaxis in CX3CR1-expressing primary cells of human and murine origin with an IC(50) of 5-50 nM. It also efficiently inhibited the cell adhesion mediated by the CX3CL1-CX3CR1 axis. Finally, in a noninfectious murine model of peritonitis, F1 strongly inhibited macrophage accumulation. These data reveal a prototype molecule that is the first bona fide antagonist of hCX3CR1. This molecule could be used as a lead compound for the development of a novel class of anti-inflammatory substances that act by inhibiting CX3CR1