The complement regulator CD46 induces a regulatory Tr1 phenotype, characterized by large amounts ... more The complement regulator CD46 induces a regulatory Tr1 phenotype, characterized by large amounts of IL-10 secretion. Secretion of IL-10 upon CD46 activation is largely impaired in T cells from patients with multiple sclerosis (MS). Vitamin D has an immunomodulatory role and may be beneficial in several pathologies, including MS. Herein, we show that, upon CD46 costimulation, Vitamin D strongly increased the IL-10:IFNγ ratio, characteristic of the CD46-induced Tr1 phenotype. This was correlated with the modulation of several markers known to control T cell activation. Vitamin D strongly promoted the expression level of CD28, CD25 and CTLA-4 on CD46-activated T cells, while it concomitantly decreased CD46 expression. Importantly, addition of Vitamin D could restore the defective IL-10 production observed in T cells from patients with MS. Hence, Vitamin D promotes anti-inflammatory responses by mainly acting on CD46, and might be beneficial for T cell responses in MS.
Le mecanisme de production des rfcgammaiia solubles humains liberes par les cellules de langerhan... more Le mecanisme de production des rfcgammaiia solubles humains liberes par les cellules de langerhans, les plaquettes et les lignees megacaryocytaires a ete etudie. Une partie de ces recepteurs solubles sont directement secretes du fait de l'absence de la region transmembranaire due a un mecanisme d'epissage alternatif de l'exon codant pour cette region. Ils ont ete appeles rfcgammaiia2, par opposition a la forme membranaire designee sous le nom de rfcgammaiia1. Alors que les cellules de langerhans secretent des molecules solubles comprenant l'integralite des regions extra- et intra- cellulaires du rfcgammaiia2, les plaquettes et les cellules de la lignee megacaryocytaire dami liberent en majorite des molecules solubles ne possedant plus une partie de l'extremite c- terminale de la region intracytoplasmique, a la suite d'un clivage proteolytique. De telles molecules sont aussi retrouvees dans le serum humain. Le clonage de l'adnc codant pour le rfcgammaiia2 dans des vecteurs d'expression eucaryote ou procaryote nous a permis de montrer que ces molecules sont capables d'entrer en competition avec le recepteur membranaire equivalent pour la fixation d'immunscomplexes. Ils pourraient aussi agir directement sur des lignees cellulaires humaines n'exprimant pas d'igg a leur surface, ce qui suggere l'existence de recepteur(s) autre(s) que les igg membranaires
Naïve T cells get activated upon encounter with their cognate antigen and differentiate into a sp... more Naïve T cells get activated upon encounter with their cognate antigen and differentiate into a specific subset of effector cells. These T cells are themselves plastic and are able to re-differentiate into another subset, changing both phenotype and function. Differentiation into a specific subset depends on the nature of the antigen and of the environmental milieu. Notably, certain nutrients, such as vitamins A and D, sodium chloride, have been shown to modulate T cell responses and influence T cell differentiation. Parasite infection can also skew Th differentiation. Similarly, the gut microbiota regulates the development of immune responses. Lastly, the key role of metabolism on T cells has also been demonstrated. This series of articles highlights some of the multiple links existing between environmental factors and T cell responses
Integrin crosslinking on human B cells induces tyrosine phosphorylation of a set of proteins rang... more Integrin crosslinking on human B cells induces tyrosine phosphorylation of a set of proteins ranging from 105 to 130 kDa, among which is the focal adhesion kinase p125FAK. Here we show that the c-CBL protooncogene product p120c-CBL is a component of these substrates. beta 1 integrin stimulation of p120c-CBL phosphorylation was observed in both transformed and normal human B cells, and was inhibited by prior treatment of cells with cytochalasin B, which disrupts the actin network. In contrast, tyrosine phosphorylation of p120c-CBL following crosslinking of the B cell antigen receptor (BCR) was not affected by cytochalasin B. Integrin stimulation of the promegakaryocytic cell line MO7e also led to a cytoskeleton-dependent tyrosine phosphorylation of p120c-CBL. In MO7e cells, this stimulation was induced by ligation of either beta 1 or beta 2 integrin, whereas only by ligation of beta 1 integrin in B cells. Tyrosine phosphorylation of p120c-CBL links phosphatidylinositol-3 kinase (PI-3...
T‐cell activation requires engagement of the T‐cell receptor and of at least one costimulatory mo... more T‐cell activation requires engagement of the T‐cell receptor and of at least one costimulatory molecule. The key role of CD28 in inducing T‐cell activation was reported several decades ago and the molecular mechanisms involved have now been well described. The complement regulator CD46 also acts as a costimulatory molecule for T cells but, in contrast to CD28, has the ability to drive T‐cell differentiation from producing some IFNγ to secreting some potent anti‐inflammatory IL‐10, acquiring a so‐called Type I regulatory phenotype (Tr1). Proteolytic cleavage of CD46 occurs upon costimulation and is important for T‐cell activation and IL‐10 production. The observation that CD46 cleavage was reduced when PBMCs were costimulated compared with purified CD4+ T cells led us to hypothesize that interactions between different cell types within the PBMCs were able to modulate the CD46 pathway. We show that CD46 downregulation is also reduced when CD4+ T cells are cocultured with autologous mo...
The complement regulator CD46 is a costimulatory molecule for human T cells that induces a regula... more The complement regulator CD46 is a costimulatory molecule for human T cells that induces a regulatory Tr1 phenotype, characterized by large amounts of IL-10 secretion. Secretion of IL-10 upon CD46 costimulation is largely impaired in T cells from patients with multiple sclerosis (MS). Vitamin D can exert a direct effect on T cells, and may be beneficial in several pathologies, including MS. In this pilot study, we examined whether active vitamin D (1,25(OH)2D3 or calcitriol) could modulate the CD46 pathway and restore IL-10 production by CD46-costimulated CD4+ T cells from patients with MS. In healthy T cells, calcitriol profoundly affects the phenotype of CD46-costimulated CD4+ T cells, by increasing the expression of CD28, CD25, CTLA-4 and Foxp3 while it concomitantly decreased CD46 expression. Similar trends were observed in MS CD4+ T cells except for CD25 for which a striking opposite effect was observed: while CD25 was normally induced on MS T cells by CD46 costimulation, addit...
Persistent neutrophilic inflammation drives host damage in autoimmune diseases that are character... more Persistent neutrophilic inflammation drives host damage in autoimmune diseases that are characterized by abundant immune complexes. Insoluble immune complexes (iICs) potently activate pro-inflammatory neutrophil effector functions. We and others have shown that iICs also promote resolution of inflammation via stimulation of neutrophil apoptosis. We demonstrate here that iICs trigger FcγRIIa-dependent neutrophil macropinocytosis, leading to the rapid uptake, and subsequent degradation of iICs. We provide evidence that concurrent iIC-induced neutrophil apoptosis is distinct from phagocytosis-induced cell death. First, uptake of iICs occurs by FcγRII-stimulated macropinocytosis, rather than phagocytosis. Second, production of reactive oxygen species, but not iIC-internalization is a pre-requisite for iIC-induced neutrophil apoptosis. Our findings identify a previously unknown mechanism by which neutrophils can remove pro-inflammatory iICs from the circulation. Together iIC clearance an...
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), in... more Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), in which T-cell migration into the CNS is key for pathogenesis. Patients with MS exhibit impaired regulatory T cell populations, and both Foxp3+ Tregs and type I regulatory T cells (Tr1) are dysfunctional. MS is a multifactorial disease and vitamin D deficiency is associated with disease. Herein, we examined the impact of 1,25(OH)2D3 on CD4+ T cells coactivated by either CD28 to induce polyclonal activation or by the complement regulator CD46 to promote Tr1 differentiation. Addition of 1,25(OH)2D3 led to a differential expression of adhesion molecules on CD28- and CD46-costimulated T cells isolated from both healthy donors or from patients with MS. 1,25(OH)2D3 favored Tr1 motility though a Vitamin D-CD46 crosstalk highlighted by increased VDR expression as well as increased CYP24A1 and miR-9 in CD46-costimulated T cells. Furthermore, analysis of CD46 expression on T cells from a cohort of ...
The complement regulator CD46 induces a regulatory Tr1 phenotype, characterized by large amounts ... more The complement regulator CD46 induces a regulatory Tr1 phenotype, characterized by large amounts of IL-10 secretion. Secretion of IL-10 upon CD46 activation is largely impaired in T cells from patients with multiple sclerosis (MS). Vitamin D has an immunomodulatory role and may be beneficial in several pathologies, including MS. Herein, we show that, upon CD46 costimulation, Vitamin D strongly increased the IL-10:IFNγ ratio, characteristic of the CD46-induced Tr1 phenotype. This was correlated with the modulation of several markers known to control T cell activation. Vitamin D strongly promoted the expression level of CD28, CD25 and CTLA-4 on CD46-activated T cells, while it concomitantly decreased CD46 expression. Importantly, addition of Vitamin D could restore the defective IL-10 production observed in T cells from patients with MS. Hence, Vitamin D promotes anti-inflammatory responses by mainly acting on CD46, and might be beneficial for T cell responses in MS.
Le mecanisme de production des rfcgammaiia solubles humains liberes par les cellules de langerhan... more Le mecanisme de production des rfcgammaiia solubles humains liberes par les cellules de langerhans, les plaquettes et les lignees megacaryocytaires a ete etudie. Une partie de ces recepteurs solubles sont directement secretes du fait de l'absence de la region transmembranaire due a un mecanisme d'epissage alternatif de l'exon codant pour cette region. Ils ont ete appeles rfcgammaiia2, par opposition a la forme membranaire designee sous le nom de rfcgammaiia1. Alors que les cellules de langerhans secretent des molecules solubles comprenant l'integralite des regions extra- et intra- cellulaires du rfcgammaiia2, les plaquettes et les cellules de la lignee megacaryocytaire dami liberent en majorite des molecules solubles ne possedant plus une partie de l'extremite c- terminale de la region intracytoplasmique, a la suite d'un clivage proteolytique. De telles molecules sont aussi retrouvees dans le serum humain. Le clonage de l'adnc codant pour le rfcgammaiia2 dans des vecteurs d'expression eucaryote ou procaryote nous a permis de montrer que ces molecules sont capables d'entrer en competition avec le recepteur membranaire equivalent pour la fixation d'immunscomplexes. Ils pourraient aussi agir directement sur des lignees cellulaires humaines n'exprimant pas d'igg a leur surface, ce qui suggere l'existence de recepteur(s) autre(s) que les igg membranaires
Naïve T cells get activated upon encounter with their cognate antigen and differentiate into a sp... more Naïve T cells get activated upon encounter with their cognate antigen and differentiate into a specific subset of effector cells. These T cells are themselves plastic and are able to re-differentiate into another subset, changing both phenotype and function. Differentiation into a specific subset depends on the nature of the antigen and of the environmental milieu. Notably, certain nutrients, such as vitamins A and D, sodium chloride, have been shown to modulate T cell responses and influence T cell differentiation. Parasite infection can also skew Th differentiation. Similarly, the gut microbiota regulates the development of immune responses. Lastly, the key role of metabolism on T cells has also been demonstrated. This series of articles highlights some of the multiple links existing between environmental factors and T cell responses
Integrin crosslinking on human B cells induces tyrosine phosphorylation of a set of proteins rang... more Integrin crosslinking on human B cells induces tyrosine phosphorylation of a set of proteins ranging from 105 to 130 kDa, among which is the focal adhesion kinase p125FAK. Here we show that the c-CBL protooncogene product p120c-CBL is a component of these substrates. beta 1 integrin stimulation of p120c-CBL phosphorylation was observed in both transformed and normal human B cells, and was inhibited by prior treatment of cells with cytochalasin B, which disrupts the actin network. In contrast, tyrosine phosphorylation of p120c-CBL following crosslinking of the B cell antigen receptor (BCR) was not affected by cytochalasin B. Integrin stimulation of the promegakaryocytic cell line MO7e also led to a cytoskeleton-dependent tyrosine phosphorylation of p120c-CBL. In MO7e cells, this stimulation was induced by ligation of either beta 1 or beta 2 integrin, whereas only by ligation of beta 1 integrin in B cells. Tyrosine phosphorylation of p120c-CBL links phosphatidylinositol-3 kinase (PI-3...
T‐cell activation requires engagement of the T‐cell receptor and of at least one costimulatory mo... more T‐cell activation requires engagement of the T‐cell receptor and of at least one costimulatory molecule. The key role of CD28 in inducing T‐cell activation was reported several decades ago and the molecular mechanisms involved have now been well described. The complement regulator CD46 also acts as a costimulatory molecule for T cells but, in contrast to CD28, has the ability to drive T‐cell differentiation from producing some IFNγ to secreting some potent anti‐inflammatory IL‐10, acquiring a so‐called Type I regulatory phenotype (Tr1). Proteolytic cleavage of CD46 occurs upon costimulation and is important for T‐cell activation and IL‐10 production. The observation that CD46 cleavage was reduced when PBMCs were costimulated compared with purified CD4+ T cells led us to hypothesize that interactions between different cell types within the PBMCs were able to modulate the CD46 pathway. We show that CD46 downregulation is also reduced when CD4+ T cells are cocultured with autologous mo...
The complement regulator CD46 is a costimulatory molecule for human T cells that induces a regula... more The complement regulator CD46 is a costimulatory molecule for human T cells that induces a regulatory Tr1 phenotype, characterized by large amounts of IL-10 secretion. Secretion of IL-10 upon CD46 costimulation is largely impaired in T cells from patients with multiple sclerosis (MS). Vitamin D can exert a direct effect on T cells, and may be beneficial in several pathologies, including MS. In this pilot study, we examined whether active vitamin D (1,25(OH)2D3 or calcitriol) could modulate the CD46 pathway and restore IL-10 production by CD46-costimulated CD4+ T cells from patients with MS. In healthy T cells, calcitriol profoundly affects the phenotype of CD46-costimulated CD4+ T cells, by increasing the expression of CD28, CD25, CTLA-4 and Foxp3 while it concomitantly decreased CD46 expression. Similar trends were observed in MS CD4+ T cells except for CD25 for which a striking opposite effect was observed: while CD25 was normally induced on MS T cells by CD46 costimulation, addit...
Persistent neutrophilic inflammation drives host damage in autoimmune diseases that are character... more Persistent neutrophilic inflammation drives host damage in autoimmune diseases that are characterized by abundant immune complexes. Insoluble immune complexes (iICs) potently activate pro-inflammatory neutrophil effector functions. We and others have shown that iICs also promote resolution of inflammation via stimulation of neutrophil apoptosis. We demonstrate here that iICs trigger FcγRIIa-dependent neutrophil macropinocytosis, leading to the rapid uptake, and subsequent degradation of iICs. We provide evidence that concurrent iIC-induced neutrophil apoptosis is distinct from phagocytosis-induced cell death. First, uptake of iICs occurs by FcγRII-stimulated macropinocytosis, rather than phagocytosis. Second, production of reactive oxygen species, but not iIC-internalization is a pre-requisite for iIC-induced neutrophil apoptosis. Our findings identify a previously unknown mechanism by which neutrophils can remove pro-inflammatory iICs from the circulation. Together iIC clearance an...
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), in... more Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), in which T-cell migration into the CNS is key for pathogenesis. Patients with MS exhibit impaired regulatory T cell populations, and both Foxp3+ Tregs and type I regulatory T cells (Tr1) are dysfunctional. MS is a multifactorial disease and vitamin D deficiency is associated with disease. Herein, we examined the impact of 1,25(OH)2D3 on CD4+ T cells coactivated by either CD28 to induce polyclonal activation or by the complement regulator CD46 to promote Tr1 differentiation. Addition of 1,25(OH)2D3 led to a differential expression of adhesion molecules on CD28- and CD46-costimulated T cells isolated from both healthy donors or from patients with MS. 1,25(OH)2D3 favored Tr1 motility though a Vitamin D-CD46 crosstalk highlighted by increased VDR expression as well as increased CYP24A1 and miR-9 in CD46-costimulated T cells. Furthermore, analysis of CD46 expression on T cells from a cohort of ...
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Papers by Anne L Astier