Elevated expression of VEGFR-3 in lymphatic endothelial cells from lymphangiomas

<p>Abstract</p> <p>Background</p> <p>Lymphangiomas are neoplasias of childhood. Their etiology is unknown and a causal therapy does not exist. The recent discovery of highly specific markers for lymphatic endothelial cells (LECs) has permitted their isolation and characterization, but expression levels and stability of molecular markers on LECs from healthy and lymphangioma tissues have not been studied yet. We addressed this problem by profiling LECs from normal dermis and two children suffering from lymphangioma, and also compared them with blood endothelial cells (BECs) from umbilical vein, aorta and myometrial microvessels.</p> <p>Methods</p> <p>Lymphangioma tissue samples were obtained from two young patients suffering from lymphangioma in the axillary and upper arm region. Initially isolated with anti-CD31 (PECAM-1) antibodies, the cells were separated by FACS sorting and magnetic beads using anti-podoplanin and/or LYVE-1 antibodies. Characterization was performed by FACS analysis, immunofluorescence staining, ELISA and micro-array gene analysis.</p> <p>Results</p> <p>LECs from foreskin and lymphangioma had an almost identical pattern of lymphendothelial markers such as podoplanin, Prox1, reelin, cMaf and integrin-α1 and -α9. However, LYVE-1 was down-regulated and VEGFR-2 and R-3 were up-regulated in lymphangiomas. Prox1 was constantly expressed in LECs but not in any of the BECs.</p> <p>Conclusion</p> <p>LECs from different sources express slightly variable molecular markers, but can always be distinguished from BECs by their Prox1 expression. High levels of VEGFR-3 and -2 seem to contribute to the etiology of lymphangiomas.</p

Lymphotoxin expression in human and murine renal allografts

The kidney is the most frequently transplanted solid organ. Recruitment of inflammatory cells, ranging from diffuse to nodular accumulations with defined microarchitecture, is a hallmark of acute and chronic renal allograft injury. Lymphotoxins (LTs) mediate the communication of lymphocytes and stromal cells and play a pivotal role in chronic inflammation and formation of lymphoid tissue. The aim of this study was to assess the expression of members of the LT system in acute rejection (AR) and chronic renal allograft injury such as transplant glomerulopathy (TG) and interstitial fibrosis/tubular atrophy (IFTA). We investigated differentially regulated components in transcriptomes of human renal allograft biopsies. By microarray analysis, we found the upregulation of LT beta, LIGHT, HVEM and TNF receptors 1 and 2 in AR and IFTA in human renal allograft biopsies. In addition, there was clear evidence for the activation of the NF kappa B pathway, most likely a consequence of LT beta receptor stimulation. In human renal allograft biopsies with transplant glomerulopathy (TG) two distinct transcriptional patterns of LT activation were revealed. By quantitative RT-PCR robust upregulation of LTa, LT beta and LIGHT was shown in biopsies with borderline lesions and AR. Immunohistochemistry revealed expression of LT beta in tubular epithelial cells and inflammatory infiltrates in transplant biopsies with AR and IFTA. Finally, activation of LT signaling was reproduced in a murine model of renal transplantation with AR. In summary, our results indicate a potential role of the LT system in acute renal allograft rejection and chronic transplant injury. Activation of the LT system in allograft rejection in rodents indicates a species independent mechanism. The functional role of the LT system in acute renal allograft rejection and chronic injury remains to be determined

Detection, Isolation and Culture of Lymphatic Endothelial Cells

Lymphatic vessels are essential for the maintenance of normal tissue fluid balance and immune surveillance, but they also provide a pathway for metastasis in many types of cancers (reviewed in Alitalo and Carmeliet 2002). In spite of the importance of lymphatic vessels in medicine, the cell biology of this part of the vascular system has received little attention until recently. Only few lymphatic endothelial cell lines have been available for molecular biological studies, and these were mainly derived from lymphatic tumors. However, the identification of lymphatic specific markers during the past few years and the isolation and maintenance of primary cultures of lymphatic endothelial cells have enabled studies of the molecular properties of these cells

Plasmacytoid dendritic cell recruitment by immobilized CXCR3 ligands

Abstract Plasmacytoid dendritic cells (pDCs) recognize microbes, viruses in particular, and provide unique means of innate defense against them. The mechanism of pDC tissue recruitment remained enigmatic because the ligands of CXCR3, the cardinal chemokine receptor on pDCs, have failed to induce in vitro chemotaxis of pDCs in the absence of additional chemokines. In this study, we demonstrate that CXCR3 is sufficient to induce pDC migration, however, by a migratory mechanism that amalgamates the features of haptotaxis and chemorepulsion. To mediate “haptorepulsion” of pDCs, CXCR3 requires the encounter of its cognate ligands immobilized, optimally by heparan sulfate, in a form of a negative gradient. This is the first report of the absolute requirement of chemokine immobilization and presentation for its in vitro promigratory activity. The paradigmatic example of pDC haptorepulsion described here may represent a new pathophysiologically relevant migratory mechanism potentially used by other cells in response to other chemokines.</jats:p