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A transmigratory cup in leukocyte diapedesis both through individual vascular endothelial cells and between them.

Carman CV, Springer TA - J. Cell Biol. (2004)

Bottom Line: We provide definitive evidence for transcellular (i.e., through individual endothelial cells) diapedesis in vitro and demonstrate that virtually all, both para- and transcellular, diapedesis occurs in the context of a novel "cuplike" transmigratory structure.Disruption of projections was highly correlated with inhibition of transmigration.These findings suggest a novel mechanism, the "transmigratory cup", by which the endothelium provides directional guidance to leukocytes for extravasation.

View Article: PubMed Central - PubMed

Affiliation: The CBR Institute for Biomedical Research, Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
The basic route and mechanisms for leukocyte migration across the endothelium remain poorly defined. We provide definitive evidence for transcellular (i.e., through individual endothelial cells) diapedesis in vitro and demonstrate that virtually all, both para- and transcellular, diapedesis occurs in the context of a novel "cuplike" transmigratory structure. This endothelial structure was comprised of highly intercellular adhesion molecule-1- and vascular cell adhesion molecule-1-enriched vertical microvilli-like projections that surrounded transmigrating leukocytes and drove redistribution of their integrins into linear tracks oriented parallel to the direction of diapedesis. Disruption of projections was highly correlated with inhibition of transmigration. These findings suggest a novel mechanism, the "transmigratory cup", by which the endothelium provides directional guidance to leukocytes for extravasation.

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At early stages of TEM ICAM-1 projections encircle the endothelial migration passage. Monocytes were incubated with TNF-α–activated, MCP-1–pretreated HUVECs for 10–20 min and then fixed and stained for ICAM-1 (IC1/11-488, green), LFA-1 (CBR-LFA1/7-Cy3, red), and VE-cadherin (55-7H1-Cy5, blue) and imaged by confocal microscopy. (A) All sections, the basal sections or the apical sections of a representative monocyte at an early stage of transcellular TEM-1. (B) A representative monocyte at a late stage of paracellular TEM-1. Dotted, dashed, and solid lines shown in the bottom panels indicate the edges of the sub-endothelial leukocyte membrane, the perimeter of the ICAM-1 projections and the TEM passage, respectively. Note that the TEM passage resides within the perimeter established by the ICAM-1 projections. Bars, 5 μm.
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fig7: At early stages of TEM ICAM-1 projections encircle the endothelial migration passage. Monocytes were incubated with TNF-α–activated, MCP-1–pretreated HUVECs for 10–20 min and then fixed and stained for ICAM-1 (IC1/11-488, green), LFA-1 (CBR-LFA1/7-Cy3, red), and VE-cadherin (55-7H1-Cy5, blue) and imaged by confocal microscopy. (A) All sections, the basal sections or the apical sections of a representative monocyte at an early stage of transcellular TEM-1. (B) A representative monocyte at a late stage of paracellular TEM-1. Dotted, dashed, and solid lines shown in the bottom panels indicate the edges of the sub-endothelial leukocyte membrane, the perimeter of the ICAM-1 projections and the TEM passage, respectively. Note that the TEM passage resides within the perimeter established by the ICAM-1 projections. Bars, 5 μm.

Mentions: To investigate the localization of other relevant endothelial adhesion molecules, ICAM-1 was visualized concomitantly with β2 integrin and either VCAM-1, ICAM-2, PECAM-1, or VE-cadherin. VCAM-1 was highly coenriched with ICAM-1 in the endothelial projections surrounding both adherent (not depicted) and transmigrating leukocytes (Fig. 6, A and C; Video 1, available at http://www.jcb.org/cgi/content/full/jcb.200404129/DC1). Conversely, VE-cadherin was localized to endothelial cell–cell junctions and was absent from projections (Fig. 6 B and Fig. S4 C). Interestingly, although in the majority of the paracellular TEM events VE-cadherin staining was interrupted and absent at the site of diapedesis (Fig. 7 B; Fig. S2, A and B; Fig. S4 C), in many cases the VE-cadherin was continuous and arched around one side of the TEM passage (Fig. 2, 6B, Fig. S1, cell 1). ICAM-2 and PECAM-1 exhibited only modest localization to the endothelial projections (Fig. S4, A and B). Functional roles for these molecules in this context cannot be excluded.


A transmigratory cup in leukocyte diapedesis both through individual vascular endothelial cells and between them.

Carman CV, Springer TA - J. Cell Biol. (2004)

At early stages of TEM ICAM-1 projections encircle the endothelial migration passage. Monocytes were incubated with TNF-α–activated, MCP-1–pretreated HUVECs for 10–20 min and then fixed and stained for ICAM-1 (IC1/11-488, green), LFA-1 (CBR-LFA1/7-Cy3, red), and VE-cadherin (55-7H1-Cy5, blue) and imaged by confocal microscopy. (A) All sections, the basal sections or the apical sections of a representative monocyte at an early stage of transcellular TEM-1. (B) A representative monocyte at a late stage of paracellular TEM-1. Dotted, dashed, and solid lines shown in the bottom panels indicate the edges of the sub-endothelial leukocyte membrane, the perimeter of the ICAM-1 projections and the TEM passage, respectively. Note that the TEM passage resides within the perimeter established by the ICAM-1 projections. Bars, 5 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172560&req=5

fig7: At early stages of TEM ICAM-1 projections encircle the endothelial migration passage. Monocytes were incubated with TNF-α–activated, MCP-1–pretreated HUVECs for 10–20 min and then fixed and stained for ICAM-1 (IC1/11-488, green), LFA-1 (CBR-LFA1/7-Cy3, red), and VE-cadherin (55-7H1-Cy5, blue) and imaged by confocal microscopy. (A) All sections, the basal sections or the apical sections of a representative monocyte at an early stage of transcellular TEM-1. (B) A representative monocyte at a late stage of paracellular TEM-1. Dotted, dashed, and solid lines shown in the bottom panels indicate the edges of the sub-endothelial leukocyte membrane, the perimeter of the ICAM-1 projections and the TEM passage, respectively. Note that the TEM passage resides within the perimeter established by the ICAM-1 projections. Bars, 5 μm.
Mentions: To investigate the localization of other relevant endothelial adhesion molecules, ICAM-1 was visualized concomitantly with β2 integrin and either VCAM-1, ICAM-2, PECAM-1, or VE-cadherin. VCAM-1 was highly coenriched with ICAM-1 in the endothelial projections surrounding both adherent (not depicted) and transmigrating leukocytes (Fig. 6, A and C; Video 1, available at http://www.jcb.org/cgi/content/full/jcb.200404129/DC1). Conversely, VE-cadherin was localized to endothelial cell–cell junctions and was absent from projections (Fig. 6 B and Fig. S4 C). Interestingly, although in the majority of the paracellular TEM events VE-cadherin staining was interrupted and absent at the site of diapedesis (Fig. 7 B; Fig. S2, A and B; Fig. S4 C), in many cases the VE-cadherin was continuous and arched around one side of the TEM passage (Fig. 2, 6B, Fig. S1, cell 1). ICAM-2 and PECAM-1 exhibited only modest localization to the endothelial projections (Fig. S4, A and B). Functional roles for these molecules in this context cannot be excluded.

Bottom Line: We provide definitive evidence for transcellular (i.e., through individual endothelial cells) diapedesis in vitro and demonstrate that virtually all, both para- and transcellular, diapedesis occurs in the context of a novel "cuplike" transmigratory structure.Disruption of projections was highly correlated with inhibition of transmigration.These findings suggest a novel mechanism, the "transmigratory cup", by which the endothelium provides directional guidance to leukocytes for extravasation.

View Article: PubMed Central - PubMed

Affiliation: The CBR Institute for Biomedical Research, Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
The basic route and mechanisms for leukocyte migration across the endothelium remain poorly defined. We provide definitive evidence for transcellular (i.e., through individual endothelial cells) diapedesis in vitro and demonstrate that virtually all, both para- and transcellular, diapedesis occurs in the context of a novel "cuplike" transmigratory structure. This endothelial structure was comprised of highly intercellular adhesion molecule-1- and vascular cell adhesion molecule-1-enriched vertical microvilli-like projections that surrounded transmigrating leukocytes and drove redistribution of their integrins into linear tracks oriented parallel to the direction of diapedesis. Disruption of projections was highly correlated with inhibition of transmigration. These findings suggest a novel mechanism, the "transmigratory cup", by which the endothelium provides directional guidance to leukocytes for extravasation.

Show MeSH
Related in: MedlinePlus