Celli S, Albert ML, Bousso P.Visualizing the innate and adaptive immune responses underlying allograft rejection by two-photon microscopy. Nat Med 17:744-749

Institut Pasteur, Unité des Dynamiques des Réponses Immunes, Département d'Immunologie, Paris, France.
Nature medicine (Impact Factor: 27.36). 06/2011; 17(6):744-9. DOI: 10.1038/nm.2376
Source: PubMed


Transplant rejection involves a coordinated attack of the innate and the adaptive immune systems of the host. To investigate this dynamic process and the contributions of both donor and host cells, we developed an ear skin graft model suitable for intravital imaging. We found that donor dermal dendritic cells (DCs) migrated rapidly from the graft and were replaced by host CD11b(+) mononuclear cells. The infiltrating host cells captured donor antigen, reached the draining lymph node and cross-primed graft-reactive CD8(+) T cells. Furthermore, we defined the mechanisms by which host T cells target graft cells. We found that primed T cells entered the graft from the surrounding tissue and localized selectively at the dermis-epidermis junction. Later, CD8(+) T cells disseminated throughout the graft and many became arrested. These results provide insights into the antigen presentation pathway and the stepwise progression of CD8(+) T cell activity, thereby offering a framework for evaluating how immunotherapy might abrogate the key steps in allograft rejection.

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Available from: Susanna Celli, Jul 10, 2014
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    • "During disease progression, activated T cells spread to the CNS parenchyma. In another study, the step-wise host tissue destruction was studied in a mouse model of allograft rejection, where ear skin grafts were imaged using intravital 2P microscopy (100). Donor dermal DCs were destroyed within 3–5 days after transplant. "
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    ABSTRACT: Mounting a protective immune response is critically dependent on the orchestrated movement of cells within lymphoid tissues. The structure of secondary lymphoid organs regulates immune responses by promoting optimal cell–cell and cell–extracellular matrix interactions. Naïve T cells are initially activated by antigen presenting cells in secondary lymphoid organs. Following priming, effector T cells migrate to the site of infection to exert their functions. Majority of the effector cells die while a small population of antigen-specific T cells persists as memory cells in distinct anatomical locations. The persistence and location of memory cells in lymphoid and non-lymphoid tissues is critical to protect the host from re-infection. The localization of memory T cells is carefully regulated by several factors including the highly organized secondary lymphoid structure, the cellular expression of chemokine receptors and compartmentalized secretion of their cognate ligands. This balance between the anatomy and the ordered expression of cell surface and soluble proteins regulates the subtle choreography of T cell migration. In recent years, our understanding of cellular dynamics of T cells has been advanced by the development of new imaging techniques allowing in situ visualization of T cell responses. Here, we review the past and more recent studies that have utilized sophisticated imaging technologies to investigate the migration dynamics of naïve, effector, and memory T cells.
    Frontiers in Immunology 07/2014; 5. DOI:10.3389/fimmu.2014.00363
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    • "Neutrophils are also found in large numbers in allografts undergoing acute rejection and are associated with graft inflammation [64, 65]. Neutrophils have been shown to contribute to allograft rejection in various preclinical models [66–68]. "
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    ABSTRACT: Alloimmune inflammation damages the microvasculature of solid organ transplants during acute rejection. Although immunosuppressive drugs diminish the inflammatory response, they do not directly promote vascular repair. Repetitive microvascular injury with insufficient regeneration results in prolonged tissue hypoxia and fibrotic remodeling. While clinical studies show that a loss of the microvascular circulation precedes and may act as an initiating factor for the development of chronic rejection, preclinical studies demonstrate that improved microvascular perfusion during acute rejection delays and attenuates tissue fibrosis. Therefore, preservation of a functional microvasculature may represent an effective therapeutic strategy for preventing chronic rejection. Here, we review recent advances in our understanding of the role of the microvasculature in the long-term survival of transplanted solid organs. We also highlight microvessel-centered therapeutic strategies for prolonging the survival of solid organ transplants.
    Journal of Molecular Medicine 06/2014; 92(8). DOI:10.1007/s00109-014-1173-y · 5.11 Impact Factor
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    • "Treg cells have been shown to both impede function and chemotaxis of CD8+ effector cells in skin [24]. Several in vivo studies have described T cell arrest in tissues in direct proportion to the amount of antigen present [7], [25], [26]. The function of these arrested cells is not clear. "
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    ABSTRACT: Cytotoxic lymphocytes (CTL) have been reported to show a range of motility patterns from rapid long-range tracking to complete arrest, but how and whether these kinematics affect their ability to kill target cells is not known. Many in vitro killing assays utilize cell lines and tumour-derived cells as targets, which may be of limited relevance to the kinetics of CTL-mediated killing of somatic cells. Here, live-cell microscopy is used to examine the interactions of CTL and primary murine skin cells presenting antigens. We developed a qualitative and quantitative killing assay using extended-duration fluorescence time-lapse microscopy coupled with large-volume objective software-based data analysis to obtain population data of cell-to-cell interactions, motility and apoptosis. In vivo and ex vivo activated antigen-specific cytotoxic lymphocytes were added to primary keratinocyte targets in culture with fluorometric detection of caspase-3 activation in targets as an objective determinant of apoptosis. We found that activated CTL achieved contact-dependent apoptosis of non-tumour targets after a period of prolonged attachment - on average 21 hours - which was determined by target cell type, amount of antigen, and activation status of CTL. Activation of CTL even without engagement of the T cell receptor was sufficient to mobilise cells significantly above baseline, while the addition of cognate antigen further enhanced their motility. Highly activated CTL showed markedly increased vector displacement, and velocity, and lead to increased antigen-specific target cell death. These data show that the inherent kinematics of CTL correlate directly with their ability to kill non-tumour cells presenting cognate antigen.
    PLoS ONE 05/2014; 9(5):e95248. DOI:10.1371/journal.pone.0095248 · 3.23 Impact Factor
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