70 research outputs found
Culture, expansion, and flow-cytometry-based functional analysis of pteropid bat MR1-restricted unconventional T cells
No full textSummary: Bats harbor viruses of global public health significance. Understanding bat immune systems may provide intervention strategies to prevent zoonotic disease transmission and identify therapeutic targets. This protocol describes how to culture and expand pteropid bat unconventional T cells, restricted by the MHC-I-related protein 1 (MR1), an MHC-I-like protein. Using multicolor flow-cytometry-based techniques, we examine pteropid MR1T cell functionality, including proliferative capacity, cytotoxicity, and cytokine production. This protocol can be adapted to aid immunological research in other bat species.For complete details on the use and execution of this protocol, please refer to Leeansyah et al. (2020b
Role of MAIT cells in human antimicrobial immunity
No full textMucosa-associated invariant T (MAIT) cells are a relatively recently discovered subset of unconventional T cells. In humans, MAIT cells are predominantly CD8+CD4- (CD8+) with a smaller CD8-CD4- (double-negative, DN) subset, and they are abundant in the peripheral blood, liver, and mucosal tissues. MAIT cells recognize riboflavin metabolites produced by a wide range of bacteria and fungi, and presented by the evolutionarily conserved major histocompatibility complex (MHC) class I-related (MR1) protein. Given the novelty of MAIT cells, this thesis had the overall aim of advancing the knowledge of their immunobiology and antimicrobial immune responses.In this thesis, we first established experimental platforms to study functions of MAIT cells in vitro, including activation, cytokine production, proliferation, cytotoxicity, as well as their ability to kill target cells. The established methodologies are versatile and can be adapted to answer a wide variety of MAIT cell-related questions. We next applied these experimental platforms to study MAIT cell responses to distinct riboflavin biosynthesis-competent microbes, and found them to differ in quality and quantity with the type and dose of microbe. We demonstrated that the TCR β chain composition and the expression of certain natural killer (NK)-cell associated receptors on MAIT cells shape their responses to TCR and innate cytokine stimulation, respectively, and thereby contribute to the functional compartmentalization of this cell population. In the third study, we dissected differences between CD8+ and DN MAIT cells with the aim of understanding the relationship between these subsets. CD8+ MAIT cells display superior functional capacity, consistent with their higher basal levels of co-stimulatory and cytotoxic molecules, and of classical effector transcription factors when compared with DN MAIT cells. Furthermore, DN MAIT cells accumulate during fetal development and their adult Vβ repertoire is a subset of that of CD8+ MAIT cells, suggesting that DN MAIT cells may derive from CD8+ MAIT cells in vivo. In the fourth study, we investigated MAIT cells in chronic hepatitis delta virus (HDV) infection. We found that MAIT cells are severely depleted from the peripheral blood of HDV-infected patients in comparison with chronic hepatitis B virus (HBV)-infected patients and healthy controls, and that MAIT cell loss is associated with the severity of liver fibrosis. Residual MAIT cells are activated, exhausted, and functionally impaired in response to TCR stimulation.Altogether, the findings in this thesis advance our understanding of human MAIT cells as functionally heterogeneous T cells that display differential response patterns to microbes and to innate cytokines, and that are markedly affected in hepatitis delta. At the same time, these findings have given rise to numerous new questions to be addressed in the rapidly expanding field of MAIT cell research in the years to come.List of scientific papersI. Human MAIT-cell responses to Escherichia coli: activation, cytokine production, proliferation, and cytotoxicity. Joana Dias, Michał J. Sobkowiak, Johan K. Sandberg, and Edwin Leeansyah. Journal of Leukocyte Biology. 2016, 100: 233-240. https://doi.org/10.1189/jlb.4TA0815-391RR II. Multiple layers of heterogeneity and subset diversity in human MAIT cell responses to distinct microorganisms and to innate cytokines. Joana Dias, Edwin Leeansyah, and Johan K. Sandberg. Proceedings of the National Academy of Sciences of the U S A. 2017, 114: E5434-E5443. https://doi.org/10.1073/pnas.1705759114 III. Human CD8-negative MAIT cells are functionally distinct from CD8-positive MAIT cells. Joana Dias, Jean-Baptiste Gorin, Caroline Boulouis, Robin H. G. A. van den Biggelaar, Anna Gibbs, Liyen Loh, Douglas F. Nixon, Kristina Broliden, Annelie Tjernlund, Johan K. Sandberg, and Edwin Leeansyah. [Manuscript]IV. Chronic hepatitis delta virus infection drives severe loss and functional exhaustion of MAIT cells. Joana Dias, Julia Hengst, Edwin Leeansyah, Sebastian Lunemann, David F. G. Malone, Svenja Hardtke, Tiphaine Parrot, Lena Berglin, Thomas Schirdewahn, Michael P. Manns, Markus Cornberg, Hans-Gustaf Ljunggren, Heiner Wedemeyer, Johan K. Sandberg, and Niklas K. Björkstrom. [Manuscript]</p
Extensive Phenotypic Analysis, Transcription Factor Profiling, and Effector Cytokine Production of Human MAIT Cells by Flow Cytometry
No full textMultiple layers of heterogeneity and subset diversity in human MAIT cell responses to distinct microorganisms and to innate cytokines
No full textSignificance
Mucosa-associated invariant T (MAIT) cells are a large subset of unconventional T cells in humans, recognizing microbial riboflavin metabolites presented by the monomorphic MR1 molecule. The extraordinary level of conservation of MR1 and the limited diversity of riboflavin-derived antigens have suggested that MAIT cells are homogeneous, and their functional specialization has not been thoroughly investigated. Here, we show that MAIT cell responses against two distinct riboflavin biosynthesis-competent microorganisms display microbe-specific response patterns with multiple layers of heterogeneity. Furthermore, a set of natural killer cell-associated receptors define a subset with enhanced capacity to respond to innate cytokine stimulus. Thus, MAIT cells harbor multiple layers of functional heterogeneity and can adapt their antimicrobial responses to the type of microbial stimuli.</jats:p
The Mechanism Underlying Defective Fcγ Receptor-Mediated Phagocytosis by HIV-1-Infected Human Monocyte-Derived Macrophages
No full textEmerging Role for MAIT Cells in Control of Antimicrobial Resistance
No full text10.1016/j.tim.2020.11.008Trends in Microbiology296504-51
Will loss of your mucosa-associated invariant T cells weaken your HAART?
No full textMucosa-associated Invariant T (MAIT) cells are an evolutionarily conserved innate-like T cell subset that recognizes antigens presented by MR1 molecules. These antigens include vitamin B derivatives shared by many potentially pathogenic microbes, including Mycobacterium tuberculosis and Candida albicans. It was recently discovered that MAIT cells decay numerically and functionally in HIV-1 infection, and that they fail to recover despite several years of effective suppression of viral replication by antiretroviral therapy (ART). Here, we briefly discuss the roles of MAIT cells and their loss in HIV immunopathogenesis. We furthermore propose that the persistence of MAIT cell loss on ART needs to be taken into account when assessing the immunological response to treatment, and when treatment should commence. The importance of this T cell subset in HIV-1 infection needs further study, and interventions to restore the MAIT cell compartment should be considered
Bacterial deception of MAIT cells in a cloud of superantigen and cytokines.
No full textThe bacterium Staphylococcus aureus is an important cause of the life-threatening condition toxic shock syndrome in humans. Bacterial toxins known as superantigens (SAgs) generate this illness by acting as broad activators of a substantial fraction of all T lymphocytes, bypassing the normally highly stringent T-cell receptor antigen specificity to cause a systemic inflammatory cytokine storm in the host. In a new study, Shaler et al. found that immune cells called mucosa-associated invariant T (MAIT) cells make an unexpectedly large contribution to the SAg response in a largely T-cell receptor-independent, cytokine-driven manner. Subsequent to such activation, the MAIT cells remain unresponsive to stimulation with bacterial antigen. Thus, S. aureus hijacks MAIT cells in the cytokine storm and leaves them functionally impaired. This work provides new insight into the role of MAIT cells in antibacterial immunity and opens new avenues of investigation to understand and possibly treat bacterial toxic shock and sepsis
- …
