Role of major histocompatibility complex class II expression by non-hematopoietic cells in autoimmune and inflammatory disorders: facts and fiction.

It is well established that interactions between CD4(+) T cells and major histocompatibility complex class II (MHCII) positive antigen-presenting cells (APCs) of hematopoietic origin play key roles in both the maintenance of tolerance and the initiation and development of autoimmune and inflammatory disorders. In sharp contrast, despite nearly three decades of intensive research, the functional relevance of MHCII expression by non-hematopoietic tissue-resident cells has remained obscure. The widespread assumption that MHCII expression by non-hematopoietic APCs has an impact on autoimmune and inflammatory diseases has in most instances neither been confirmed nor excluded by indisputable in vivo data. Here we review and put into perspective conflicting in vitro and in vivo results on the putative impact of MHCII expression by non-hematopoietic APCs-in both target organs and secondary lymphoid tissues-on the initiation and development of representative autoimmune and inflammatory disorders. Emphasis will be placed on the lacunar status of our knowledge in this field. We also discuss new mouse models-developed on the basis of our understanding of the molecular mechanisms that regulate MHCII expression-that constitute valuable tools for filling the severe gaps in our knowledge on the functions of non-hematopoietic APCs in inflammatory conditions.

Volochinov en contexte : essai d'épistémologie historique

Valentin N. Volochinov (1895-1936), un des amis de Mikhaïl Bakhtine, a longtemps été considéré par certains chercheurs du domaine des études bakhtiniennes comme le prête-nom de ce dernier ; les oeuvres de Volochinov et de Bakhtine ont souvent été reçues comme émanant d'un seul et même projet scientifique. Ce livre donne de Volochinov une image radicalement nouvelle. D'une part, on montre en quoi il est un auteur totalement indépendant de Bakhtine. D'autre part, on analyse les sources de ses textes - livres et articles - en les replaçant dans le contexte, peu connu du public francophone, de la vie intellectuelle russe d'avant et après la Révolution d'Octobre. Sont étudiés le type de sociologie et de critique marxiste de l'idéologie qui s'est diffusé en Russie avec Lénine, Plékhanov, Bogdanov et Boukharine, la réception du Cours de linguistique générale de Saussure et de la psychanalyse de Freud, les apports de la psychologie expérimentale et des travaux de De Roberty et de Sorokine en sciences humaines, que l'on retrouve à l'origine des premières théories de l'interaction verbale et de la parole dans la vie quotidienne. On rend ainsi à Volochinov, outre l'originalité et la cohérence de sa pensée, l'énergie roborative de son engagement scientifique, qui culminera en 1929 avec Marxisme et philosophie du langage

Chirurgie endoscopique endonasale des tumeurs de la base du crane : historique, état de l'art et perspectives d'avenir [Shifting paradigm in skull base surgery: Roots, current state of the art and future trends of endonasal endoscopic approaches].

During the last two decades, endoscopic endonasal approach has completed the minimally invasive skull base surgery armamentarium. Endoscopic endonasal skull base surgery (EESBS) was initially developed in the field of pituitary adenomas, and gained an increasing place for the treatment of a wide variety of skull base pathologies, extending on the midline from crista galli process to the occipitocervical junction and laterally to the parasellar areas and petroclival apex. Until now, most studies are retrospective and lack sufficient methodological quality to confirm whether the endoscopic endonasal pituitary surgery has better results than the microsurgical trans-sphenoidal classical approach. The impressions of the expert teams show a trend toward better results for some pituitary adenomas with the endoscopic endonasal route, in terms of gross total resection rate and probably more comfortable postoperative course for the patient. Excepting intra- and suprasellar pituitary adenomas, EESBS seems useful for selected lesions extending onto the cavernous sinus and Meckel's cave but also for clival pathologies. Nevertheless, this infatuation toward endoscopic endonasal approaches has to be balanced with the critical issue of cerebrospinal fluid leaks, which constitutes actually the main limit of this approach. Through their experience and a review of the literature, the authors aim to present the state of the art of this approach as well as its limits.