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4 Publications visible to you, out of a total of 4
Mitochondrial calcium uniporter complex controls T-cell-mediated immune responses

Abstract (Expand)

Abstract T-cell receptor (TCR)-induced Ca 2+ signals are essential for T-cell activation and function. In this context, mitochondria play an important role and take up Ca 2+ to support elevated …xt, mitochondria play an important role and take up Ca 2+ to support elevated bioenergetic demands. However, the functional relevance of the mitochondrial-Ca 2+ -uniporter (MCU) complex in T-cells was not fully understood. Here, we demonstrate that TCR activation causes rapid mitochondrial Ca 2+ ( m Ca 2+ ) uptake in primary naive and effector human CD4 + T-cells. Compared to naive T-cells, effector T-cells display elevated m Ca 2+ and increased bioenergetic and metabolic output. Transcriptome and proteome analyses reveal molecular determinants involved in the TCR-induced functional reprogramming and identify signalling pathways and cellular functions regulated by MCU. Knockdown of MCUa (MCUa KD ), diminishes m Ca 2+ uptake, mitochondrial respiration and ATP production, as well as T-cell migration and cytokine secretion. Moreover, MCUa KD in rat CD4 + T-cells suppresses autoimmune responses in an experimental autoimmune encephalomyelitis (EAE) multiple sclerosis model. In summary, we demonstrate that m Ca 2+ uptake through MCU is essential for proper T-cell function and has a crucial role in autoimmunity. T-cell specific MCU inhibition is thus a potential tool for targeting autoimmune disorders.

Authors: Magdalena Shumanska, Dmitri Lodygin, Christine S Gibhardt, Christian Ickes, Ioana Stejerean-Todoran, Lena C M Krause, Kira Pahl, Lianne J H C Jacobs, Andrea Paluschkiwitz, Shuya Liu, Angela Boshnakovska, Niels Voigt, Tobias J Legler, Martin Haubrock, Miso Mitkovski, Gereon Poschmann, Peter Rehling, Sven Dennerlein, Jan Riemer, Alexander Flügel, Ivan Bogeski

Date Published: 2nd Dec 2024

Publication Type: Journal Article

TFEB activation hallmarks antigenic experience of B lymphocytes and directs germinal center fate decisions

Abstract (Expand)

Abstract Ligation of the B cell antigen receptor (BCR) initiates humoral immunity. However, BCR signaling without appropriate co-stimulation commits B cells to death rather than to differentiation into …fferentiation into immune effector cells. How BCR activation depletes potentially autoreactive B cells while simultaneously primes for receiving rescue and differentiation signals from cognate T lymphocytes remains unknown. Here, we use a mass spectrometry-based proteomic approach to identify cytosolic/nuclear shuttling elements and uncover transcription factor EB (TFEB) as a central BCR-controlled rheostat that drives activation-induced apoptosis, and concurrently promotes the reception of co-stimulatory rescue signals by supporting B cell migration and antigen presentation. CD40 co-stimulation prevents TFEB-driven cell death, while enhancing and prolonging TFEB’s nuclear residency, which hallmarks antigenic experience also of memory B cells. In mice, TFEB shapes the transcriptional landscape of germinal center B cells. Within the germinal center, TFEB facilitates the dark zone entry of light-zone-residing centrocytes through regulation of chemokine receptors and, by balancing the expression of Bcl-2/BH3-only family members, integrates antigen-induced apoptosis with T cell-provided CD40 survival signals. Thus, TFEB reprograms antigen-primed germinal center B cells for cell fate decisions.

Authors: Matthias Münchhalfen, Richard Görg, Michael Haberl, Jens Löber, Jakob Willenbrink, Laura Schwarzt, Charlotte Höltermann, Christian Ickes, Leonard Hammermann, Jan Kus, Björn Chapuy, Andrea Ballabio, Sybille D. Reichardt, Alexander Flügel, Niklas Engels, Jürgen Wienands

Date Published: 14th Aug 2024

Publication Type: Journal Article

Myelin insulation as a risk factor for axonal degeneration in autoimmune demyelinating disease

Abstract (Expand)

Abstract Axonal degeneration determines the clinical outcome of multiple sclerosis and is thought to result from exposure of denuded axons to immune-mediated damage. Therefore, myelin is widely considered … widely considered to be a protective structure for axons in multiple sclerosis. Myelinated axons also depend on oligodendrocytes, which provide metabolic and structural support to the axonal compartment. Given that axonal pathology in multiple sclerosis is already visible at early disease stages, before overt demyelination, we reasoned that autoimmune inflammation may disrupt oligodendroglial support mechanisms and hence primarily affect axons insulated by myelin. Here, we studied axonal pathology as a function of myelination in human multiple sclerosis and mouse models of autoimmune encephalomyelitis with genetically altered myelination. We demonstrate that myelin ensheathment itself becomes detrimental for axonal survival and increases the risk of axons degenerating in an autoimmune environment. This challenges the view of myelin as a solely protective structure and suggests that axonal dependence on oligodendroglial support can become fatal when myelin is under inflammatory attack.

Authors: Erik Schäffner, Mar Bosch-Queralt, Julia M. Edgar, Maria Lehning, Judith Strauß, Niko Fleischer, Theresa Kungl, Peter Wieghofer, Stefan A. Berghoff, Tilo Reinert, Martin Krueger, Markus Morawski, Wiebke Möbius, Alonso Barrantes-Freer, Jens Stieler, Ting Sun, Gesine Saher, Markus H. Schwab, Christoph Wrede, Maximilian Frosch, Marco Prinz, Daniel S. Reich, Alexander Flügel, Christine Stadelmann, Robert Fledrich, Klaus-Armin Nave, Ruth M. Stassart

Date Published: 29th Jun 2023

Publication Type: Journal Article

The lung microbiome regulates brain autoimmunity.

Abstract (Expand)

Lung infections and smoking are risk factors for multiple sclerosis, a T-cell-mediated autoimmune disease of the central nervous system(1). In addition, the lung serves as a niche for the disease-inducing … T cells for long-term survival and for maturation into migration-competent effector T cells(2). Why the lung tissue in particular has such an important role in an autoimmune disease of the brain is not yet known. Here we detected a tight interconnection between the lung microbiota and the immune reactivity of the brain. A dysregulation in the lung microbiome significantly influenced the susceptibility of rats to developing autoimmune disease of the central nervous system. Shifting the microbiota towards lipopolysaccharide-enriched phyla by local treatment with neomycin induced a type-I-interferon-primed state in brain-resident microglial cells. Their responsiveness towards autoimmune-dominated stimulation by type II interferons was impaired, which led to decreased proinflammatory response, immune cell recruitment and clinical signs. Suppressing lipopolysaccharide-producing lung phyla with polymyxin B led to disease aggravation, whereas addition of lipopolysaccharide-enriched phyla or lipopolysaccharide recapitulated the neomycin effect. Our data demonstrate the existence of a lung-brain axis in which the pulmonary microbiome regulates the immune reactivity of the central nervous tissue and thereby influences its susceptibility to autoimmune disease development.

Authors: L. Hosang, R. C. Canals, F. J. van der Flier, J. Hollensteiner, R. Daniel, A. Flugel, F. Odoardi

Date Published: 25th Feb 2022

Publication Type: Journal Article

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