Visualizing the stimulation of encephalitogenic T cells in gut associated lymphoid tissue as a trigger of autoimmunity

Fang, Ping (2018): Visualizing the stimulation of encephalitogenic T cells in gut associated lymphoid tissue as a trigger of autoimmunity. Dissertation, LMU München: Medizinische Fakultät

Abstract

Autoantigen-specific encephalitogenic T cells exist in the healthy immune repertoire. In case of CNS autoimmunity, such as multiple sclerosis (MS), cells penetrate into the central nervous system (CNS), where they get activated by local antigen presenting cells, and induce inflammation. However, the triggering mechanisms that provoke CNS infiltration of pre-existing autoreactive T cells are largely unknown. Recent studies have shown evidence that microbiota induce proliferation of encephalitogenic T cells in gut associated lymphatic tissues (GALT) before CNS infiltration in the spontaneous experimental autoimmune encephalomyelitis (EAE), an animal model of MS. In this study, the activation and subsequent behaviour of encephalitogenic T cells in the GALT are investigated. Myelin oligodendrocyte glycoprotein (MOG) specific T cells from transgenic mice are retrovirally transduced with FRET-based calcium activation sensors and adoptively transferred to recipient mice. T cells in the lamina propria and Peyer’s patches are imaged in vivo with two-photon microscopy and the calcium fluctuation is quantified to detect T cell activation. Moreover, migrating T cells in the efferent lymphatic vessels of GALT were analysed in order to elucidate phenotypic changes due to in vivo stimulation. Intravital imaging reveals that encephalitogenic T cells, but not polyclonal T cells, display continuous calcium signaling in the lamina propria. In contrast, encephalitogenic T cells in the Peyer’s patch show only brief calcium signaling. The continuous calcium signaling is diminished by administration of anti-MHC class II blocking antibody. This observation suggests that the calcium signaling of encephalitogenic T cells is mediated by antigen presenting cells. Additionally, the role of commensal microbiota is highlighted through the fact encephalitogenic T cells do not show continuous calcium signaling in germ free mice, which suggests the influence of microbiota. The increased number of IL17A and IFN producing T cells were detected in efferent lymph from mesenteric lymph nodes, further suggests the stimulation of T cells in the GALT. This phenotype, in addition to the enhanced number of CD44+ encephalitogenic T cells, suggests that microbiota induced stimulation in the GALT influences the migration of encephalitogenic T cells in CNS autoimmunity. In summary, the following study reveals pre-existing encephalitogenic T cells are capable of being stimulated in the lamina propria of ileum. The stimulation is dependent upon an intact gut microbiota compartment and may enhance migration of encephalitogenic T cells.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: encephalitogenic T cells, intravital imaging, small intestine, T cell stimulation
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 28. November 2018
• 1. Bericht­erstatter:in: Kawakami, Naoto