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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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Monocytes migrate across the endothelium via paracellular routes in association with ICAM-1 projections. Samples were prepared as in Fig. 1 with ICAM-1, LFA-1, and VE-cadherin (shown in A only) represented by green, red, and blue fluorescence, respectively. (A) Top view projection of all z-series sections of a representative monocyte transmigrating via a paracellular route. (B–D) Field in A was rendered as a series of three-dimensional projections, each representing successive rotation about both the x and z axis in 30° intervals for a total of 90° about each axis. (E) Side view projection of cross section of E in A depicting ICAM-1 projections (top) and linear LFA-1 clusters (bottom) separately. (F) Side view projection of cross section F in A. Apical (G), middle (H), or basal (I) z-axis sections, as indicated by brackets in F, are projected as top views. Bar, 5 μm.
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fig2: Monocytes migrate across the endothelium via paracellular routes in association with ICAM-1 projections. Samples were prepared as in Fig. 1 with ICAM-1, LFA-1, and VE-cadherin (shown in A only) represented by green, red, and blue fluorescence, respectively. (A) Top view projection of all z-series sections of a representative monocyte transmigrating via a paracellular route. (B–D) Field in A was rendered as a series of three-dimensional projections, each representing successive rotation about both the x and z axis in 30° intervals for a total of 90° about each axis. (E) Side view projection of cross section of E in A depicting ICAM-1 projections (top) and linear LFA-1 clusters (bottom) separately. (F) Side view projection of cross section F in A. Apical (G), middle (H), or basal (I) z-axis sections, as indicated by brackets in F, are projected as top views. Bar, 5 μm.

Mentions: At time periods of 10 min, significant numbers of all three classes of leukocytes were observed to be in the process of TEM. Remarkably, considerable fractions of TEM events were found to take place at sites clearly distinct from cell–cell junctions, demonstrating unambiguous use of the transcellular route of TEM (Fig. 1; Fig. S1, cell 2; Fig. S2, available at http://www.jcb.org/cgi/content/full/jcb.200404129/DC1). To analyze this statistically, at least 100 leukocytes in randomly selected fields from each of at least three separate experiments were imaged in all apical to basal planes. This revealed that 7 ± 1%, 5 ± 2%, and 11 ± 4% of the transmigrating monocytes, neutrophils, and lymphocytes, respectively, used transcellular routes. The remainder of leukocytes transmigrated at sites closely juxtaposed to endothelial cell–cell junctions, and were scored as paracellular TEM (Fig. 2; Fig. S1, cell 1; Fig. S2). Among the TEM events scored as paracellular, were many whose appearance was suggestive of a transcellular route, yet whose TEM passage was too close to endothelial cell–cell junctions for an unambiguous determination of transcellular TEM (Fig. S2 C).


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

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

Monocytes migrate across the endothelium via paracellular routes in association with ICAM-1 projections. Samples were prepared as in Fig. 1 with ICAM-1, LFA-1, and VE-cadherin (shown in A only) represented by green, red, and blue fluorescence, respectively. (A) Top view projection of all z-series sections of a representative monocyte transmigrating via a paracellular route. (B–D) Field in A was rendered as a series of three-dimensional projections, each representing successive rotation about both the x and z axis in 30° intervals for a total of 90° about each axis. (E) Side view projection of cross section of E in A depicting ICAM-1 projections (top) and linear LFA-1 clusters (bottom) separately. (F) Side view projection of cross section F in A. Apical (G), middle (H), or basal (I) z-axis sections, as indicated by brackets in F, are projected as top views. Bar, 5 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172560&req=5

fig2: Monocytes migrate across the endothelium via paracellular routes in association with ICAM-1 projections. Samples were prepared as in Fig. 1 with ICAM-1, LFA-1, and VE-cadherin (shown in A only) represented by green, red, and blue fluorescence, respectively. (A) Top view projection of all z-series sections of a representative monocyte transmigrating via a paracellular route. (B–D) Field in A was rendered as a series of three-dimensional projections, each representing successive rotation about both the x and z axis in 30° intervals for a total of 90° about each axis. (E) Side view projection of cross section of E in A depicting ICAM-1 projections (top) and linear LFA-1 clusters (bottom) separately. (F) Side view projection of cross section F in A. Apical (G), middle (H), or basal (I) z-axis sections, as indicated by brackets in F, are projected as top views. Bar, 5 μm.
Mentions: At time periods of 10 min, significant numbers of all three classes of leukocytes were observed to be in the process of TEM. Remarkably, considerable fractions of TEM events were found to take place at sites clearly distinct from cell–cell junctions, demonstrating unambiguous use of the transcellular route of TEM (Fig. 1; Fig. S1, cell 2; Fig. S2, available at http://www.jcb.org/cgi/content/full/jcb.200404129/DC1). To analyze this statistically, at least 100 leukocytes in randomly selected fields from each of at least three separate experiments were imaged in all apical to basal planes. This revealed that 7 ± 1%, 5 ± 2%, and 11 ± 4% of the transmigrating monocytes, neutrophils, and lymphocytes, respectively, used transcellular routes. The remainder of leukocytes transmigrated at sites closely juxtaposed to endothelial cell–cell junctions, and were scored as paracellular TEM (Fig. 2; Fig. S1, cell 1; Fig. S2). Among the TEM events scored as paracellular, were many whose appearance was suggestive of a transcellular route, yet whose TEM passage was too close to endothelial cell–cell junctions for an unambiguous determination of transcellular TEM (Fig. S2 C).

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