Die Rolle der TRPM7-Kinase im Mausmodell der Multiplen Sklerose

Jacob, Katharina Susanne (2023): Die Rolle der TRPM7-Kinase im Mausmodell der Multiplen Sklerose. Dissertation, LMU München: Medizinische Fakultät

Abstract

The transient receptor potential channel subfamily M member 7, is a ubiquitously expressed cation channel with a c-terminal fused serine/threonine kinase. It has been associated with a numerous of important cellular functions like proliferation, differentiation, activation and survival. In addition, it strongly linked to immunity and seems to be an important signaling molecule in lymphocytes. Recently it has been shown that the TRPM7 kinase activity promotes Graft versus Host Disease in Mice. In the GvHD, T-helper 17 (TH17) cells differentiated from the transplanted donor cells act against the host in a pro-inflammatory manner. In other pro-inflammatory diseases such as Multiple Sclerosis (MS), TH17 cells are also significantly involved in the development of the disease. MS is a chronic autoimmune disease affecting the central nervous system and is characterized by progressive disease with loss of the myelin sheath of nerve cells. In this thesis, using an animal model of MS, Experimental Autoimmune Encephalomyelitis (EAE), we evaluated whether and to what extent the TRPM7 kinase plays a role in the development and progression of MS. Therefore, we utilized an established mouse model with a point mutation at the active site of the kinase, K1646R (Trpm7R/R). In active EAE, immunization with pertussis toxin was shown to strongly stimulate the IL-1β signaling pathway. This overrides the anti-inflammatory influence of Trpm7R/R, animals become equally ill regardless of their genotype. These observations were confirmed by in vitro differentiations into TH17 cells of Trpm7+/+ and Trpm7R/R CD4+ T cells. Trpm7R/R cells can be differentiated into TH17 cells with IL-1ß similarly well as Trpm7+/+ cells. Trpm7+/+ cells differentiate equally well into TH17 cells independent of IL-1β. Without the addition of IL-1β, significantly fewer Trpm7R/R cells differentiate into TH17 cells. Interestingly, when the strong additional stimulus of the IL-1β pathway is circumvented by inducing EAE via passive immunization, we can show that the loss of kinase activity leads to a lower incidence of EAE. Significantly fewer animals became ill, compared to Trpm7+/+. In the Trpm7R/R animals that did became ill, the course of the disease was milder than in their Trpm7+/+ littermates. In addition, we could show that there was an increased migration of Treg cells into the CNS of the diseased Trpm7R/R, which is associated with a good prognosis for remyelination of the damaged nerve fibers. Furthermore, no TH17 cells had migrated into the CNS of non-diseased Trpm7R/R, but they had migrated into the CNS of non-diseased Trpm7+/+. Moreover, we found that the activity of the kinase also affects chemokine expression by T-lymphocytes. Trpm7R/R cells that were differentiated without the addition of IL-1β expressed significantly more Ccl3, Ccl4, Ccl5, Ccl9, and Cxcr1 and avoided downregulation of S1pr1. Interestingly, in combination, Cxcr1, Ccl3, Ccl4, and Ccl5 are known to primarily promote a pro-inflammatory phenotype. Considering individually, however, there is evidence for a particular recruitment potential of Treg cells. Our results suggest that the additional combination with Ccl9 and S1pr1 leads to an anti-inflammatory signal, which results in an increased migration of Treg cells and consequently less animals get sick. In conclusion, the inactivation of kinase activity constitutes a promising therapeutic strategy in the treatment of MS and requires further research to elucidate the exact processes and signaling pathways underlying.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: EAE, Multiple Sklerose, TRPM7, Autoimmunität
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Deutsch
• Datum der mündlichen Prüfung: 25. Oktober 2023
• 1. Bericht­erstatter:in: Zierler, Susanna