Effect of the abortive infection mechanism and type III toxin/antitoxin system AbiQ on the lytic cycle of lactococcus lactis phages

To survive in phage-containing environments, bacteria have evolved an array of antiphage systems. Similarly, phages have overcome these hurdles through various means. Here, we investigated how phages are able to circumvent the Lactococcus lactis AbiQ system, a type III toxin-antitoxin with antiviral activities. Lactococcal phage escape mutants were obtained in the laboratory, and their genomes were sequenced. Three unrelated genes of unknown function were mutated in derivatives of three distinct lactococcal siphophages: orf38 of phage P008, m1 of phage bIL170, and e19 of phage c2. One-step growth curve experiments revealed that the phage mutations had a fitness cost while transcriptional analyses showed that AbiQ modified the early-expressed phage mRNA profiles. The L. lactis AbiQ system was also transferred into Escherichia coli MG1655 and tested against several coliphages. While AbiQ was efficient against phages T4 (Myoviridae) and T5 (Siphoviridae), escape mutants of only phage 2 (Myoviridae) could be isolated. Genome sequencing revealed a mutation in gene orf210, a putative DNA polymerase. Taking these observations together, different phage genes or gene products are targeted or involved in the AbiQ phenotype. Moreover, this antiviral system is active against various phage families infecting Gram-positive and Gram-negative bacteria. A model for the mode of action of AbiQ is proposed

Etude de la réponse immunitaire T au cours de l'artérite à cellules géantes (Maladie de Horton)

The aim of this thesis was to investigate the T-cell immune response in the course of giant-cell arteritis (GCA) and polymyalgia rheumatica (PMR). Several studies conducted by our team allowed us to obtain blood samples from many patients affected by GCA (n=57) and PMR (n=28). Immunological studies were performed in INSERM U1098, University Of Burgundy, Dijon, France. We firstly demonstrated the implication of Th17 and CD4+CD161+ T cells in the pathogenesis of these two diseases, thus extending the knowledge in the plasticity mechanisms arising between Th1 and Th17 cell-immune responses in GCA and PMR. Furthermore, we investigated the regulatory T cell immune response in these two affections, demonstrating that although being functional, the percentage of circulating Treg was decreased in GCA and PMR patients. As interleukin-6 (IL-6) had been shown to control the Th17/Treg balance, we studied Th17 and Treg frequencies in rheumatoid arthritis patients treated with an anti-IL-6 receptor antibody (tocilizumab). We showed that the blockade of the IL-6 pathway was able to correct the Th17/Treg imbalance by decreasing the number of Th17 cells and simultaneously increasing that of Treg. Finally, we demonstrated for the first time the implication of CD8+ T cells in the pathogenesis of GCA and PMR. This thesis allowed us to progress in the knowledge of the pathogenesis of GCA making the pathogenesis model progress from a Th1/Th2 to a Th17/Treg imbalance model. Altogether, these data deciphering the immune response in the pathogenesis of GCA and PMR bring new knowledge which will lead to better targeted therapies.Ce travail de thèse a été axé sur l’étude de la réponse immunitaire T chez des patients atteints d’artérite à cellules géantes (ACG) et de pseudo-polyarthrite rhizomélique (PPR). Plusieurs études cliniques successives interrégionales ont permis d’inclure de nombreux patients (57 ACG et 27 PPR) des Centres Hospitaliers (CH) Universitaires et des CH de l’interrégion Est. Les échantillons sanguins ont été étudiés dans le laboratoire de l’unité INSERM U1098. Tout d’abord, nous avons confirmé l’implication des lymphocytes Th17 dans la pathogénie de l’ACG et avons montré pour la première fois leur implication au cours de la PPR. De plus, notre étude des lymphocytes T (LT) CD4+CD161+ a permis de mieux comprendre les mécanismes de plasticité entre les réponses Th1 et Th17 au cours de ces deux pathologies. Nous avons complété ces travaux par l’étude de la réponse T régulatrice en montrant qu’il existe un déficit quantitatif en Treg au cours de l’ACG et la PPR. Dans la suite de ce travail, nous avons mis en évidence, chez des patients atteints de polyarthrite rhumatoïde, que le blocage de la voie de signalisation de l’IL-6 par un anticorps monoclonal dirigé contre le récepteur de l’IL-6 permet de corriger le déséquilibre de la balance Th17/Treg, en diminuant la réponse Th17 et en augmentant simultanément la réponse T régulatrice, à l’inverse des corticoïdes qui diminuent le pourcentage de Th17 sans corriger le déficit en Treg. Enfin, dans la dernière partie de ce travail, nous avons montré pour la première fois que les LT CD8+ étaient également impliqués dans la pathogénie de l’ACG et la PPR. Ces résultats ont permis de progresser dans les connaissances physiopathologiques de l’ACG et la PPR en évoluant d’un modèle articulé autour d’un déséquilibre de la balance Th1/Th2 vers celui d’un déséquilibre de la balance Th17/Treg et permettent de proposer des thérapeutiques mieux ciblées pour l’ACG et la PPR

Cytotoxic dendritic cells generated from cancer patients.

International audienceKnown for years as professional APCs, dendritic cells (DCs) are also endowed with tumoricidal activity. This dual role of DC as killers and messengers may have important implications for tumor immunotherapy. However, the tumoricidal activity of DCs has mainly been investigated in animal models. Cancer cells inhibit antitumor immune responses using numerous mechanisms, including the induction of immunosuppressive/ tolerogenic DCs that have lost their ability to present Ags in an immunogenic manner. In this study, we evaluated the possibility of generating tumor killer DCs from patients with advanced-stage cancers. We demonstrate that human monocyte-derived DCs are endowed with significant cytotoxic activity against tumor cells following activation with LPS. The mechanism of DC-mediated tumor cell killing primarily involves peroxynitrites. This observed cytotoxic activity is restricted to immature DCs. Additionally, after killing, these cytotoxic DCs are able to activate tumor Ag-specific T cells. These observations may open important new perspectives for the use of autologous cytotoxic DCs in cancer immunotherapy strategies

Lifting the veil on the correction of double counting incidents in hybrid life cycle assessment

Life cycle assessment (LCA) and environmentally extended input–output analyses (EEIOA) are two techniques commonly used to assess environmental impacts of an activity/product. Their strengths and weaknesses are complementary, and they are thus regularly combined to obtain hybrid LCAs. A number of approaches in hybrid LCA exist, which leads to different results. One of the differences is the method used to ensure that mixed LCA and EEIOA data do not overlap, which is referred to as correction for double counting. This aspect of hybrid LCA is often ignored in reports of hybrid assessments and no comprehensive study has been carried out on it. This article strives to list, compare, and analyze the different existing methods for the correction of double counting. We first harmonize the definitions of the existing correction methods and express them in a common notation, before introducing a streamlined variant. We then compare their respective assumptions and limitations. We discuss the loss of specific information regarding the studied activity/product and the loss of coherent financial representation caused by some of the correction methods. This analysis clarifies which techniques are most applicable to different tasks, from hybridizing individual LCA processes to integrating complete databases. We finally conclude by giving recommendations for future hybrid analyses

Correcting remaining truncations in hybrid life cycle assessment database compilation

Hybrid life cycle assessment (HLCA) strives to combine process‐based life cycle assessment (PLCA) and environmentally extended input–output (EEIO) analysis to bridge gaps of both methodologies. The recent development of HLCA databases constitutes a major step forward in achieving complete system coverage. Nevertheless, current applications of HLCA still suffer from issues related to incompleteness of the inventory and data gaps: (1) hybridization without endogenizing the capital inputs of the EEIO database leads to underestimations, (2) the unreliability of price data hinders the application of streamlined HLCA for processes in some sectors, and (3) the sparse coverage of pollutants in multiregional EEIO databases limits the application of HLCA to a handful of impact categories. This paper aims at offering a methodology for tackling these issues in a streamlined manner and visualizing their effects on impact scores across an entire PLCA database and multiple impact categories. Data reconciliation algorithms are demonstrated on the PLCA database ecoinvent3.5 and the multiregional EEIO database EXIOBASE3. Instead of performing hybridization solely with annual product requirements, this hybridization approach incorporates endogenized capital requirements, demonstrates a novel hybridization methodology to bypass issues of price unavailability, estimates new pollutants to EXIOBASE3 environmental extensions, and thus yields improved inventories characterized in terms of 13 impact categories from the IMPACT World+ methodology. The effect of hybridization on the impact score of each process of ecoinvent3.5 varied from a few percentages to three‐fold increases, depending on the impact category and the process studied, displaying in which cases hybridization should be prioritized. This article met the requirements for a Gold—Gold JIE data openness badge described at http://jie.click/badges

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)

Effect of Audiovisual Training on Monaural Spatial Hearing in Horizontal Plane

The article aims to test the hypothesis that audiovisual integration can improve spatial hearing in monaural conditions when interaural difference cues are not available. We trained one group of subjects with an audiovisual task, where a flash was presented in parallel with the sound and another group in an auditory task, where only sound from different spatial locations was presented. To check whether the observed audiovisual effect was similar to feedback, the third group was trained using the visual feedback paradigm. Training sessions were administered once per day, for 5 days. The performance level in each group was compared for auditory only stimulation on the first and the last day of practice. Improvement after audiovisual training was several times higher than after auditory practice. The group trained with visual feedback demonstrated a different effect of training with the improvement smaller than the group with audiovisual training. We conclude that cross-modal facilitation is highly important to improve spatial hearing in monaural conditions and may be applied to the rehabilitation of patients with unilateral deafness and after unilateral cochlear implantation