Toll-Like Receptor Agonists Synergize with CD40L to Induce Either Proliferation or Plasma Cell Differentiation of Mouse B Cells

In a classical dogma, pathogens are sensed (via recognition of Pathogen Associated Molecular Patterns (PAMPs)) by innate immune cells that in turn activate adaptive immune cells. However, recent data showed that TLRs (Toll Like Receptors), the most characterized class of Pattern Recognition Receptors, are also expressed by adaptive immune B cells. B cells play an important role in protective immunity essentially by differentiating into antibody-secreting cells (ASC). This differentiation requires at least two signals: the recognition of an antigen by the B cell specific receptor (BCR) and a T cell co-stimulatory signal provided mainly by CD154/CD40L acting on CD40. In order to better understand interactions of innate and adaptive B cell stimulatory signals, we evaluated the outcome of combinations of TLRs, BCR and/or CD40 stimulation. For this purpose, mouse spleen B cells were activated with synthetic TLR agonists, recombinant mouse CD40L and agonist anti-BCR antibodies. As expected, TLR agonists induced mouse B cell proliferation and activation or differentiation into ASC. Interestingly, addition of CD40 signal to TLR agonists stimulated either B cell proliferation and activation (TLR3, TLR4, and TLR9) or differentiation into ASC (TLR1/2, TLR2/6, TLR4 and TLR7). Addition of a BCR signal to CD40L and either TLR3 or TLR9 agonists did not induce differentiation into ASC, which could be interpreted as an entrance into the memory pathway. In conclusion, our results suggest that PAMPs synergize with signals from adaptive immunity to regulate B lymphocyte fate during humoral immune response

Photon shot-noise limited transient absorption soft X-ray spectroscopy at the European XFEL

Femtosecond transient soft X-ray Absorption Spectroscopy (XAS) is a very promising technique that can be employed at X-ray Free Electron Lasers (FELs) to investigate out-of-equilibrium dynamics for material and energy research. Here we present a dedicated setup for soft X-rays available at the Spectroscopy & Coherent Scattering (SCS) instrument at the European X-ray Free Electron Laser (EuXFEL). It consists of a beam-splitting off-axis zone plate (BOZ) used in transmission to create three copies of the incoming beam, which are used to measure the transmitted intensity through the excited and unexcited sample, as well as to monitor the incoming intensity. Since these three intensity signals are detected shot-by-shot and simultaneously, this setup allows normalized shot-by-shot analysis of the transmission. For photon detection, the DSSC imaging detector, which is capable of recording up to 800 images at 4.5 MHz frame rate during the FEL burst, is employed and allows approaching the photon shot-noise limit. We review the setup and its capabilities, as well as the online and offline analysis tools provided to users.Comment: 11 figure

Contrôle de la prolifération et de la différenciation des lymphocytes B murins par des signaux de l'immunité innée et de l'immunité adaptative

La différenciation terminale des cellules B nécessite deux signaux : un signal provenant de la reconnaissance de l antigène par le récepteur des cellules B (BCR) spécifique et un signal fourni par l interaction de la molécule CD40 exprimée sur les cellules B avec son ligand CD40L exprimé par les cellules T activées. Mais récemment, il a été montré qu un troisième signal provenant de la reconnaissance du pathogène par les TLR (Toll-Like Receptor) pouvait être important voire même nécessaire pour le développement d une réponse immunitaire humorale. Ainsile rôle des TLR, mais également de deux NLR (NOD-Like Receptor), seuls ou associés à un signal de l immunité adaptative (CD40L + BCR) sur l activation et la différenciation des cellules Ba été évalué. Nous avons montré que tous les agonistes des TLR, à l exception des TLR3 et 9, induisent la prolifération, l activation et la différenciation des cellules B, et que l ajout d un signal de l immunité adaptative aux agonistes des TLR permettait d augmenter soit l activation et la prolifération des cellules B (TLR3, 4, 9) soit la différenciation de ces cellules en cellules sécrétrices d anticorps (TLR1/2, 2/6, 4, 7) soit le développement de cellules B mémoires. De plus, nous avons montré que le ligand de Nod1 n induit pas de différenciation des cellules B mais son association avec un signal CD40 permet de l augmenter.Ainsi, nous avons montré que les pathogènes seuls ou en association avec des signaux de l immunité adaptative peuvent déclencher et contrôler la réponse des cellules B. Ces différents stimuli peuvent induire le développement soit de plasmocytes soit de cellules B mémoires, ce qui pourrait être intéressant pour le développement de nouveaux vaccins.Terminal differentiation of B cells requires two signals: a signal deriving from the recognition of the antigen by the specific B cell receptor (BCR) and a signal provided by the interaction between the CD40 molecule expressed on B cells and its ligand CD40L expressed by activated T cells. Nevertheless, it has been recently shown that a third signal deriving from the pathogen recognition by Toll-Like Receptors (TLR) could be important and even necessary for the development of a humoral immune response.Thus the role of TLRs, but also of two NLR (NOD-Like Receptor), alone or combined with a signal of adaptive immunity (CD40L + BCR) on the activation and differentiation of B cells have been investigated.We have demonstrated that all TLR agonists, with the exception of TLR3 and 9, induce proliferation, activation and differentiation of B cells. Moreover, the addition of a signal from adaptive immunity to TLR agonists can increase B cell activation and proliferation (TLR3, 4, 9), differentiation of these cells into antibody secreting cells (TLR1/2, 2/6, 4, 7), and the development of memory B cells. Furthermore, we showed that the Nod1 ligand does not induce B cell differentiation but its association with a CD40 signal can enhance it.Thus, we have shown that pathogens alone or combined with signals of adaptive immunity can trigger and control the B cell response. These different stimuli can induce the development of either plasma cells or memory B cells, this could be an important asset for the development of new vaccines.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Structural dynamics during laser-induced ultrafast demagnetization

The mechanism underlying femtosecond laser-pulse-induced ultrafast magnetization dynamics remains elusive, despite two decades of intense research on this phenomenon. Most experiments focused so far on characterizing magnetization and charge carrier dynamics, while the first direct measurements of structural dynamics during ultrafast demagnetization were reported only very recently. We here present our investigation of the infrared laser-pulse-induced ultrafast demagnetization process in a thin Ni film, which characterizes simultaneously magnetization and structural dynamics. This is achieved by employing femtosecond time-resolved x-ray resonant magnetic reflectivity (tr-XRMR) as the probe technique. The experimental results reveal unambiguously that the subpicosecond magnetization quenching is accompanied by strong changes in nonmagnetic x-ray reflectivity. These changes vary with reflection angle, and changes up to 30% have been observed. By modeling the x-ray reflectivity of the investigated thin film, we can reproduce these changes by a variation of the apparent Ni layer thickness of up to 1%. Extending these simulations to larger incidence angles, we show that tr-XRMR can be employed to discriminate experimentally between currently discussed models describing the ultrafast demagnetization phenomenon.Funding from the European Community's Seventh Framework Programme under Grant Agreement No. 312284 (CALIPSO Project) is gratefully acknowledged, as well as financial support received from the following agencies: (i) The French “Agence National de la Recherche” (ANR) via the projects UMAMI, ANR-11-LABX-0058_NIE and the EQUIPEX UNION (ANR-10-EQPX-52), and (ii) the CNRS-PICS program

Bibliographie critique

Eisemann Pierre Michel, Boeglin-Naumovic Nicolas, Burgorgue-Larsen Laurence, Daudet Yves, Gérard Caroline, Jouannet Emmanuelle, Morosoli Anthony, Norodom Anne-Thida, Peyro Llopis Ana, Postelnicu-Reynier Anamaria, Richieri Hanania Lilian, Robert Sabrina, Smuclerova Martina, Tardieu Aurélie, Tigroudja Hélène, Verhoeven Joe. Bibliographie critique. In: Annuaire français de droit international, volume 49, 2003. pp. 821-877

Bibliographie critique

Eisemann P. M., Bismuth Regis, Boeglin-Naumovic Nicolas, Buzzi Alessandro, Cassella Sarah, Daudet Yves, Delabie Lucie, El Boudouhi Saïda, Gérard Caroline, Iovane Massimo, Jouannet Emmanuelle, Kouadri Myriam, Momtaz Djamchid, Norodom Anne-Thida, Robert Sabrina, Smuclerova Martina, Tardieu Aurélie, Tigroudja Hélène. Bibliographie critique. In: Annuaire français de droit international, volume 51, 2005. pp. 912-972

Bibliographie critique

Eisemann Pierre Michel, Boeglin-Naumovic Nicolas, Bastid-Burdeau Geneviève, Burgorgue-Larsen Laurence, Cassella Sarah, Cosnard Michel, Delabie Lucie, El Boudouhi Saïda, Gérard Caroline, Hamant Hélène, Jouannet Emmanuelle, Norodom Anne-Thida, Postelnicu-Reynier Anamaria, Richieri Hanania Lilian, Robert Sabrina, Smuclerova Martina, Tardieu Aurélie, Tigroudja Hélène. Bibliographie critique. In: Annuaire français de droit international, volume 50, 2004. pp. 985-1051

Bibliographie critique

Eisemann Pierre Michel, Boeglin-Naumovic Nicolas, Bastid-Burdeau Geneviève, Burgorgue-Larsen Laurence, Cassella Sarah, Cosnard Michel, Delabie Lucie, El Boudouhi Saïda, Gérard Caroline, Hamant Hélène, Jouannet Emmanuelle, Norodom Anne-Thida, Postelnicu-Reynier Anamaria, Richieri Hanania Lilian, Robert Sabrina, Smuclerova Martina, Tardieu Aurélie, Tigroudja Hélène. Bibliographie critique. In: Annuaire français de droit international, volume 50, 2004. pp. 985-1051