| 1. |
- Gardenier, Jason C., et al.
(författare)
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Diphtheria toxin-mediated ablation of lymphatic endothelial cells results in progressive lymphedema
- 2016
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Ingår i: JCI INSIGHT. - : American Society for Clinical Investigation. - 2379-3708. ; 1:15
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Tidskriftsartikel (refereegranskat)abstract
- Development of novel treatments for lymphedema has been limited by the fact that the pathophysiology of this disease is poorly understood. It remains unknown, for example, why limb swelling resulting from surgical injury resolves initially, but recurs in some cases months or years later. Finding answers for these basic questions has been hampered by the lack of adequate animal models. In the current study, we used Cre-lox mice that expressed the human diphtheria toxin receptor (DTR) driven by a lymphatic-specific promoter in order to noninvasively ablate the lymphatic system of the hind limb. Animals treated in this manner developed lymphedema that was indistinguishable from clinical lymphedema temporally, radiographically, and histologically. Using this model and clinical biopsy specimens, we show that the initial resolution of edema after injury is dependent on the formation of collateral capillary lymphatics and that this process is regulated by M2-polarized macrophages. In addition, we show that despite these initial improvements in lymphatic function, persistent accumulation of CD4(+) cells inhibits lymphangiogenesis and promotes sclerosis of collecting lymphatics, resulting in late onset of edema and fibrosis. Our findings therefore provide strong evidence that inflammatory changes after lymphatic injury play a key role in the pathophysiology of lymphedema.
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| 2. |
- Huang, Jung-Ju, et al.
(författare)
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Lymph Node Transplantation Decreases Swelling and Restores Immune Responses in a Transgenic Model of Lymphedema
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Secondary lymphedema is a common complication of cancer treatment and recent studies have demonstrated that lymph node transplantation (LNT) can decrease swelling, as well as the incidence of infections. However, although these results are exciting, the mechanisms by which LNT improves these pathologic findings of lymphedema remain unknown. Using a transgenic mouse model of lymphedema, this study sought to analyze the effect of LNT on lymphatic regeneration and T cell-mediated immune responses. Methods We used a mouse model in which the expression of the human diphtheria toxin receptor is driven by the FLT4 promoter to enable the local ablation of the lymphatic system through subdermal hindlimb diphtheria toxin injections. Popliteal lymph node dissection was subsequently performed after a two-week recovery period, followed by either orthotopic LNT or sham surgery after an additional two weeks. Hindlimb swelling, lymphatic vessel regeneration, immune cell trafficking, and T cell-mediated immune responses were analyzed 10 weeks later. Results LNT resulted in a marked decrease in hindlimb swelling, fibroadipose tissue deposition, and decreased accumulation of perilymphatic inflammatory cells, as compared to controls. In addition, LNT induced a marked lymphangiogenic response in both capillary and collecting lymphatic vessels. Interestingly, the resultant regenerated lymphatics were abnormal in appearance on lymphangiography, but LNT also led to a notable increase in dendritic cell trafficking from the periphery to the inguinal lymph nodes and improved adaptive immune responses. Conclusions LNT decreases pathological changes of lymphedema and was shown to potently induce lymphangiogenesis. Lymphatic vessels induced by LNT were abnormal in appearance, but were functional and able to transport antigen-presenting cells. Animals treated with LNT have an increased ability to mount T cell-mediated immune responses when sensitized to antigens in the affected hindlimb.
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| 3. |
- Martinez-Corral, Ines, et al.
(författare)
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Nonvenous Origin of Dermal Lymphatic Vasculature
- 2015
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Ingår i: Circulation Research. - 0009-7330 .- 1524-4571. ; 116:10, s. 1649-1654
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: The formation of the blood vasculature is achieved via 2 fundamentally different mechanisms, de novo formation of vessels from endothelial progenitors (vasculogenesis) and sprouting of vessels from pre-existing ones (angiogenesis). In contrast, mammalian lymphatic vasculature is thought to form exclusively by sprouting from embryonic veins (lymphangiogenesis). Alternative nonvenous sources of lymphatic endothelial cells have been suggested in chicken and Xenopus, but it is unclear whether they exist in mammals. Objective: We aimed to clarify the origin of the murine dermal lymphatic vasculature. Methods and Results: We performed lineage tracing experiments and analyzed mutants lacking the Prox1 transcription factor, a master regulator of lymphatic endothelial cell identity, in Tie2 lineage venous-derived lymphatic endothelial cells. We show that, contrary to current dogma, a significant part of the dermal lymphatic vasculature forms independently of sprouting from veins. Although lymphatic vessels of cervical and thoracic skin develop via sprouting from venous-derived lymph sacs, vessels of lumbar and dorsal midline skin form via assembly of non-Tie2-lineage cells into clusters and vessels through a process defined as lymphvasculogenesis. Conclusions: Our results demonstrate a significant contribution of nonvenous-derived cells to the dermal lymphatic vasculature. Demonstration of a previously unknown lymphatic endothelial cell progenitor population will now allow further characterization of their origin, identity, and functions during normal lymphatic development and in pathology, as well as their potential therapeutic use for lymphatic regeneration.
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| 4. |
- Martinez-Corral, Ines, et al.
(författare)
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Vegfr3-CreER (T2) mouse, a new genetic tool for targeting the lymphatic system
- 2016
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Ingår i: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 19:3, s. 433-445
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Tidskriftsartikel (refereegranskat)abstract
- The lymphatic system is essential in many physiological and pathological processes. Still, much remains to be known about the molecular mechanisms that control its development and function and how to modulate them therapeutically. The study of these mechanisms will benefit from better controlled genetic mouse models targeting specifically lymphatic endothelial cells. Among the genes expressed predominantly in lymphatic endothelium, Vegfr3 was the first one identified and is still considered to be one of the best lymphatic markers and a key regulator of the lymphatic system. Here, we report the generation of a Vegfr3-CreER (T2) knockin mouse by gene targeting in embryonic stem cells. This mouse expresses the tamoxifen-inducible CreER(T2) recombinase under the endogenous transcriptional control of the Vegfr3 gene without altering its physiological expression or regulation. The Vegfr3-CreER (T2) allele drives efficient recombination of floxed sequences upon tamoxifen administration specifically in Vegfr3-expressing cells, both in vitro, in primary lymphatic endothelial cells, and in vivo, at different stages of mouse embryonic development and postnatal life. Thus, our Vegfr3-CreER (T2) mouse constitutes a new powerful genetic tool for lineage tracing analysis and for conditional gene manipulation in the lymphatic endothelium that will contribute to improve our current understanding of this system.
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| 5. |
- Olmeda, David, et al.
(författare)
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Whole-body imaging of lymphovascular niches identifies pre-metastatic roles of midkine
- 2017
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 546:7660, s. 676-680
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Tidskriftsartikel (refereegranskat)abstract
- Cutaneous melanoma is a type of cancer with an inherent potential for lymph node colonization, which is generally preceded by neolymphangiogenesis(1-3). However, sentinel lymph node removal does not necessarily extend the overall survival of patients with melanoma(4,5). Moreover, lymphatic vessels collapse and become dysfunctional as melanomas progress(6,7). Therefore, it is unclear whether (and how) lymphangiogenesis contributes to visceral metastasis. Soluble and vesicle-associated proteins secreted by tumours and/or their stroma have been proposed to condition pre-metastatic sites in patients with melanoma(8-14). Still, the identities and prognostic value of lymphangiogenic mediators remain unclear(2,14). Moreover, our understanding of lymphangiogenesis (in melanomas and other tumour types) is limited by the paucity of mouse models for live imaging of distal pre-metastatic niches(15). Injectable lymphatic tracers have been developed(7), but their limited diffusion precludes whole-body imaging at visceral sites(16). Vascular endothelial growth factor receptor 3 (VEGFR3) is an attractive 'lymphoreporter' 17 because its expression is strongly downregulated in normal adult lymphatic endothelial cells, but is activated in pathological situations such as inflammation and cancer(17,18). Here, we exploit this inducibility of VEGFR3 to engineer mouse melanoma models for whole-body imaging of metastasis generated by human cells, clinical biopsies or endogenously deregulated oncogenic pathways. This strategy revealed early induction of distal pre-metastatic niches uncoupled from lymphangiogenesis at primary lesions. Analyses of the melanoma secretome and validation in clinical specimens showed that the heparin-binding factor midkine is a systemic inducer of neo-lymphangiogenesis that defines patient prognosis. This role of midkine was linked to a paracrine activation of the mTOR pathway in lymphatic endothelial cells. These data support the use of VEGFR3 reporter mice as a 'MetAlert' discovery platform for drivers and inhibitors of metastasis.
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| 6. |
- Sabine, Amelie, et al.
(författare)
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FOXC2 and fluid shear stress stabilize postnatal lymphatic vasculature
- 2015
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 125:10, s. 3861-3877
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Tidskriftsartikel (refereegranskat)abstract
- Biomechanical forces, such as fluid shear stress, govern multiple aspects of endothelial cell biology. In blood vessels, disturbed flow is associated with vascular diseases, such as atherosclerosis, and promotes endothelial cell proliferation and apoptosis. Here, we identified an important role for disturbed flow in lymphatic vessels, in which it cooperates with the transcription factor FOXC2 to ensure lifelong stability of the lymphatic vasculature. In cultured lymphatic endothelial cells, FOXC2 inactivation conferred abnormal shear stress sensing, promoting junction disassembly and entry into the cell cycle. Loss of FOXC2-dependent quiescence was mediated by the Hippo pathway transcriptional coactivator TAZ and, ultimately, led to cell death. In murine models, inducible deletion of Foxc2 within the lymphatic vasculature led to cell-cell junction defects, regression of valves, and focal vascular lumen collapse, which triggered generalized lymphatic vascular dysfunction and lethality. Together, our work describes a fundamental mechanism by which FOXC2 and oscillatory shear stress maintain lymphatic endothelial cell quiescence through intercellular junction and cytoskeleton stabilization and provides an essential link between biomechanical forces and endothelial cell identity that is necessary for postnatal vessel homeostasis. As FOXC2 is mutated in lymphedema-distichiasis syndrome, our data also underscore the role of impaired mechanotransduction in the pathology of this hereditary human disease.
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| 7. |
- Stanczuk, Lukas, et al.
(författare)
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cKit Lineage Hemogenic Endothelium-Derived Cells Contribute to Mesenteric Lymphatic Vessels
- 2015
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 10:10, s. 1708-1721
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Tidskriftsartikel (refereegranskat)abstract
- Pathological lymphatic diseases mostly affect vessels in specific tissues, yet little is known about organ-specific regulation of the lymphatic vasculature. Here, we show that the vascular endothelial growth factor receptor 3 (VEGFR-3)/p110 alpha PI3-kinase signaling pathway is selectively required for the formation of mesenteric lymphatic vasculature. Using genetic lineage tracing, we demonstrate that part of the mesenteric lymphatic vasculature develops from cKit lineage cells of hemogenic endothelial origin through a process we define as lymphvasculogenesis. This is contrary to the current dogma that all mammalian lymphatic vessels form by sprouting from veins. Our results reveal vascular-bed-specific differences in the origin and mechanisms of vessel formation, which may critically underlie organ-specific manifestation of lymphatic dysfunction in disease. The progenitor cells identified in this study may be exploited to restore lymphatic function following cancer surgery, lymphedema, or tissue trauma.
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