Multiple pathways for glucose phosphate transport and utilization support growth of Cryptosporidium parvum

Cryptosporidium parvum is an obligate intracellular parasite with a highly reduced mitochondrion that lacks the tricarboxylic acid cycle and the ability to generate ATP, making the parasite reliant on glycolysis. Genetic ablation experiments demonstrated that neither of the two putative glucose transporters CpGT1 and CpGT2 were essential for growth. Surprisingly, hexokinase was also dispensable for parasite growth while the downstream enzyme aldolase was required, suggesting the parasite has an alternative way of obtaining phosphorylated hexose. Complementation studies in E. coli support a role for direct transport of glucose-6-phosphate from the host cell by the parasite transporters CpGT1 and CpGT2, thus bypassing a requirement for hexokinase. Additionally, the parasite obtains phosphorylated glucose from amylopectin stores that are released by the action of the essential enzyme glycogen phosphorylase. Collectively, these findings reveal that C. parvum relies on multiple pathways to obtain phosphorylated glucose both for glycolysis and to restore carbohydrate reserves

Cryptosporidium infection of human small intestinal epithelial cells induces type III interferon and impairs infectivity of Rotavirus

Cryptosporidiosis is a major cause of severe diarrheal disease in infants from resource poor settings. The majority of infections are caused by the human-specific pathoge

Cestode infections in non-human primates suggest the existence of zoonotic cycles in the area surrounding the Strasbourg primatology center

Background: Several cases of infections due to Echinococcus multilocularis, Taenia martis and Taenia crassiceps were recently described in various species of captive non-human primates (NHPs) harbored in the Strasbourg Primate Center (SPC). Furthermore, one of the first cases of human cysticercosis due to T. martis was described in the Strasbourg region. These data suggest the existence of zoonotic cycles of tapeworm infections in the direct environment of the SPC. The aim of our study was to assess the prevalence of larval cestode infections among intermediate and definitive hosts in the close neighborhood of the center. We analyzed carnivore mammal fecal samples as well as rodent carcasses, collected inside or near the SPC, using PCR. Furthermore, we performed serology for Echinococcus spp. and Taenia spp. on NHP sera. Results: We found that 14.5% (95% CI [8.6; 20.4]) of 138 carnivore feces were positive for E. multilocularis-DNA, as well as 25% (95% CI [5.5; 57.2]) of 12 rodent carcasses, and 5.1% (95% CI [1.4; 8.7]) for T. martis or T. crassiceps. Of all NHPs tested, 10.1% (95% CI [3.8; 16.4]) were seropositive for Echinococcus spp. and 8.2% (95% CI [1.3; 15.1]) for Taenia spp. Conclusions: Our data support the existence of zoonotic cycles of larval cestode infections in the direct environment of the primatology center affecting NHPs harbored in the SPC, potentially threatening the human population living in this area. Since this zoonotic risk is borne by local wildlife, and given the severity of these infections, it seems necessary to put in place measures to protect captive NHPs, and further studies to better assess the risk to human populations

Regulatory T-cell dysfunctions are associated with increase in tumor necrosis factor α in autoimmune hemolytic anemia and participate in Th17 polarization

Warm autoimmune hemolytic anemia (wAIHA) is a rare acquired autoimmune disease mediated by antibodies targeting red blood cells. The involvement of CD4 T-helper cells has been scarcely explored, with most findings extrapolated from animal models. Here, we performed quantification of both effector T lymphocytes (Teff) and regulatory T cells (Treg), associated with functional and transcriptomic analyses of Treg in human wAIHA. We observed a shift of Teff toward a Th17 polarization concordant with an increase in serum interleukin-17 concentration that correlates with red blood cell destruction parameters, namely lactate dehydrogenase and bilirubin levels. A decrease in circulating Treg, notably effector Treg, associated with a functional deficiency, as represented by their decrease capability to inhibit Teff proliferation, were also observed. Treg deficiency was associated with a reduced expression of Foxp3, the master transcription factor known to maintain the Treg phenotype stability and suppressive functions. Transcriptomic profiling of Treg revealed activation of the tumor necrosis facto (TNF)-α pathway, which was linked to increased serum TNF-α concentrations that were twice as high as in controls. Treg transcriptomic profiling also suggested that post-translational mechanisms possibly accounted for Foxp3 downregulation and Treg dysfunctions. Since TNF-α participates in the rupture of immune tolerance during wAIHA, its inhibition could be of interest. To this end, the effects of fostamatinib, a SYK inhibitor, were investigated in vitro, and we showed that besides the inhibition of erythrocyte phagocytosis by monocytes, fostamatinib is also able to dampen TNF-α production, thus appearing as a promising multitargeting therapy in wAIHA (clinicaltrials gov. Identifier: NCT02158195)

Interactions entre les cellules résidentes de la paroi vasculaire et les lymphocytes T au cours de l'artérite à cellules géantes

In the arterial media, vascular smooth muscle cells play a major role in the pathophysiology of giant cell arteritis (GCA) by their production of chemokines leading to the recruitment of T cells and monocytes in the vascular wall and by their capacity to migrate towards the intima and to differentiate into myofibroblasts (MF) which proliferate and synthesize extra-cellular matrix proteins participating in vascular remodelling. In this thesis work, we set up various experimental techniques such as the analysis of temporal artery sections in immunofluorescence, culture of MF from temporal artery sections, coculture of peripheral blood mononuclear cells (PBMC) and MF and ex vivo culture of temporal artery. This work provides new data on the involvement of MF during GCA, demonstrating that these cells are not only involved in vascular remodelling but also play a key role in the regulation of vascular inflammation by their ability to maintain Th1/Tc1 polarisation in injured arteries, participating in the initiation of an inflammatory amplification loop within the arterial wall, thus preventing the resolution of inflammation in GCA. These experimental techniques allow us to explore more precisely the mechanisms involved in GCA, with the aim of finding strategies to further target the polarising and vascular remodelling function mediated by MF to better treat patients.Les cellules musculaires lisses vasculaires présentes dans la média des artères jouent un rôle majeur dans la physiopathologie de l'artérite à cellules géantes (ACG) par leur production de chimiokines aboutissant au recrutement de lymphocytes T et de monocytes dans la paroi vasculaire mais aussi par leur capacité à migrer vers l'intima et se différencier en myofibroblastes (MF) qui prolifèrent et synthétisent des protéines de la matrice extra-cellulaire participant au remodelage vasculaire. Durant ce travail de thèse nous avons mis en place diverses techniques expérimentales comme l’analyse de sections d’artère temporale en immunofluorescence, l’obtention de lignées de MF en culture à partir de sections d’artère temporale, la coculture des cellules mononucléées du sang périphérique (PBMC) et des MF ainsi que la culture ex vivo d’artère temporale. Ce travail apporte des données nouvelles sur l’implication des MF au cours de l’ACG, démontrant que ces cellules ne sont pas seulement impliquées dans le remodelage vasculaire mais jouent également un rôle clé dans la régulation de l’inflammation vasculaire via notamment leur capacité à maintenir la polarisation Th1/Tc1 dans les artères lésées, participant à l'initiation d'une boucle d'amplification de la réponse inflammatoire au sein de la paroi artérielle, empêchant ainsi la résolution de l'inflammation au cours de l'ACG. Ces techniques expérimentales nous permettent aujourd’hui d’explorer plus précisément les mécanismes impliqués dans l’ACG, dans le but de trouver des stratégies ciblant les fonctions d’orientation de la polarisation des lymphocytes T et de remodelage vasculaire médiées par les MF, afin de mieux traiter les patients

Interactions entre les cellules résidentes de la paroi vasculaire et les lymphocytes T au cours de l'artérite à cellules géantes

In the arterial media, vascular smooth muscle cells play a major role in the pathophysiology of giant cell arteritis (GCA) by their production of chemokines leading to the recruitment of T cells and monocytes in the vascular wall and by their capacity to migrate towards the intima and to differentiate into myofibroblasts (MF) which proliferate and synthesize extra-cellular matrix proteins participating in vascular remodelling. In this thesis work, we set up various experimental techniques such as the analysis of temporal artery sections in immunofluorescence, culture of MF from temporal artery sections, coculture of peripheral blood mononuclear cells (PBMC) and MF and ex vivo culture of temporal artery. This work provides new data on the involvement of MF during GCA, demonstrating that these cells are not only involved in vascular remodelling but also play a key role in the regulation of vascular inflammation by their ability to maintain Th1/Tc1 polarisation in injured arteries, participating in the initiation of an inflammatory amplification loop within the arterial wall, thus preventing the resolution of inflammation in GCA. These experimental techniques allow us to explore more precisely the mechanisms involved in GCA, with the aim of finding strategies to further target the polarising and vascular remodelling function mediated by MF to better treat patients.Les cellules musculaires lisses vasculaires présentes dans la média des artères jouent un rôle majeur dans la physiopathologie de l'artérite à cellules géantes (ACG) par leur production de chimiokines aboutissant au recrutement de lymphocytes T et de monocytes dans la paroi vasculaire mais aussi par leur capacité à migrer vers l'intima et se différencier en myofibroblastes (MF) qui prolifèrent et synthétisent des protéines de la matrice extra-cellulaire participant au remodelage vasculaire. Durant ce travail de thèse nous avons mis en place diverses techniques expérimentales comme l’analyse de sections d’artère temporale en immunofluorescence, l’obtention de lignées de MF en culture à partir de sections d’artère temporale, la coculture des cellules mononucléées du sang périphérique (PBMC) et des MF ainsi que la culture ex vivo d’artère temporale. Ce travail apporte des données nouvelles sur l’implication des MF au cours de l’ACG, démontrant que ces cellules ne sont pas seulement impliquées dans le remodelage vasculaire mais jouent également un rôle clé dans la régulation de l’inflammation vasculaire via notamment leur capacité à maintenir la polarisation Th1/Tc1 dans les artères lésées, participant à l'initiation d'une boucle d'amplification de la réponse inflammatoire au sein de la paroi artérielle, empêchant ainsi la résolution de l'inflammation au cours de l'ACG. Ces techniques expérimentales nous permettent aujourd’hui d’explorer plus précisément les mécanismes impliqués dans l’ACG, dans le but de trouver des stratégies ciblant les fonctions d’orientation de la polarisation des lymphocytes T et de remodelage vasculaire médiées par les MF, afin de mieux traiter les patients

Une nouvelle approche de l’immunité innée lors de la toxoplasmose oculaire : le rôle méconnu des interférons de type I et III

Ocular toxoplasmosis (TO) is an inflammatory condition of the eye caused by infection with the protozoan parasite Toxoplasma gondii. The aim of this study was to explore the role of interferon-β (type I) and IFNs-λ (type III) during TO. Using in vitro models of human retinal cultures, we studied the expression of different cytokines, parasitic proliferation and permeability of retinal epithelium cell monolayers (RPEC) in response to stimulation by type I & III IFNs and infection. We show that most of the cells tested are reactive to stimulation by type I and type III IFNs, that infection with T. gondii induces the expression of type I and type III IFNs, that stimulation of RPEC by type I IFNs limits parasitic proliferation during the infection of these cells by T. gondii and that the IFNs-λ prevent the disjunction of the RPEC following infection by T. gondii.La toxoplasmose oculaire (TO) est une affection inflammatoire de l’œil consécutive à l’infection par le parasite protozoaire Toxoplasma gondii. L’objectif de cette étude était d’explorer le rôle de l’interféron-β (type I) et des IFNs-λ (type III) au cours de la TO. À l’aide de modèles in vitro de cultures rétiniennes humaines nous avons étudié l’expression de différentes cytokines, la prolifération parasitaire et la perméabilité de monocouches de cellules d’épithélium rétinien (RPEC) en réponse à la stimulation par des IFNs de type I et III et à l’infection. Nous montrons que la plupart des cellules testées sont réactives à la stimulation par des IFNs de type I et de type III, que l’infection par T. gondii induit l’expression d’IFNs de type I et de type III, que la stimulation de RPEC par des IFNs de type I limite la prolifération parasitaire lors de l’infection de ces cellules par T. gondii et que les IFNs-λ préviennent la disjonction des RPEC consécutive à l’infection par T. gondii

Interactions between resident cells of the vascular wall and T cells during giant cell arteritis

Les cellules musculaires lisses vasculaires présentes dans la média des artères jouent un rôle majeur dans la physiopathologie de l'artérite à cellules géantes (ACG) par leur production de chimiokines aboutissant au recrutement de lymphocytes T et de monocytes dans la paroi vasculaire mais aussi par leur capacité à migrer vers l'intima et se différencier en myofibroblastes (MF) qui prolifèrent et synthétisent des protéines de la matrice extra-cellulaire participant au remodelage vasculaire. Durant ce travail de thèse nous avons mis en place diverses techniques expérimentales comme l’analyse de sections d’artère temporale en immunofluorescence, l’obtention de lignées de MF en culture à partir de sections d’artère temporale, la coculture des cellules mononucléées du sang périphérique (PBMC) et des MF ainsi que la culture ex vivo d’artère temporale. Ce travail apporte des données nouvelles sur l’implication des MF au cours de l’ACG, démontrant que ces cellules ne sont pas seulement impliquées dans le remodelage vasculaire mais jouent également un rôle clé dans la régulation de l’inflammation vasculaire via notamment leur capacité à maintenir la polarisation Th1/Tc1 dans les artères lésées, participant à l'initiation d'une boucle d'amplification de la réponse inflammatoire au sein de la paroi artérielle, empêchant ainsi la résolution de l'inflammation au cours de l'ACG. Ces techniques expérimentales nous permettent aujourd’hui d’explorer plus précisément les mécanismes impliqués dans l’ACG, dans le but de trouver des stratégies ciblant les fonctions d’orientation de la polarisation des lymphocytes T et de remodelage vasculaire médiées par les MF, afin de mieux traiter les patients.In the arterial media, vascular smooth muscle cells play a major role in the pathophysiology of giant cell arteritis (GCA) by their production of chemokines leading to the recruitment of T cells and monocytes in the vascular wall and by their capacity to migrate towards the intima and to differentiate into myofibroblasts (MF) which proliferate and synthesize extra-cellular matrix proteins participating in vascular remodelling. In this thesis work, we set up various experimental techniques such as the analysis of temporal artery sections in immunofluorescence, culture of MF from temporal artery sections, coculture of peripheral blood mononuclear cells (PBMC) and MF and ex vivo culture of temporal artery. This work provides new data on the involvement of MF during GCA, demonstrating that these cells are not only involved in vascular remodelling but also play a key role in the regulation of vascular inflammation by their ability to maintain Th1/Tc1 polarisation in injured arteries, participating in the initiation of an inflammatory amplification loop within the arterial wall, thus preventing the resolution of inflammation in GCA. These experimental techniques allow us to explore more precisely the mechanisms involved in GCA, with the aim of finding strategies to further target the polarising and vascular remodelling function mediated by MF to better treat patients