Limits...
The adhesion molecule L1 regulates transendothelial migration and trafficking of dendritic cells.

Maddaluno L, Verbrugge SE, Martinoli C, Matteoli G, Chiavelli A, Zeng Y, Williams ED, Rescigno M, Cavallaro U - J. Exp. Med. (2009)

Bottom Line: In agreement with these findings, L1 was expressed in cutaneous DCs that migrated to draining lymph nodes, and its ablation reduced DC trafficking in vivo.Within the skin, L1 was found in Langerhans cells but not in dermal DCs, and L1 deficiency impaired Langerhans cell migration.Our results implicate L1 in the regulation of DC trafficking and shed light on novel mechanisms underlying transendothelial migration of DCs.

View Article: PubMed Central - PubMed

Affiliation: The FIRC Institute of Molecular Oncology, 20139 Milan, Italy.

ABSTRACT
The adhesion molecule L1, which is extensively characterized in the nervous system, is also expressed in dendritic cells (DCs), but its function there has remained elusive. To address this issue, we ablated L1 expression in DCs of conditional knockout mice. L1-deficient DCs were impaired in adhesion to and transmigration through monolayers of either lymphatic or blood vessel endothelial cells, implicating L1 in transendothelial migration of DCs. In agreement with these findings, L1 was expressed in cutaneous DCs that migrated to draining lymph nodes, and its ablation reduced DC trafficking in vivo. Within the skin, L1 was found in Langerhans cells but not in dermal DCs, and L1 deficiency impaired Langerhans cell migration. Under inflammatory conditions, L1 also became expressed in vascular endothelium and enhanced transmigration of DCs, likely through L1 homophilic interactions. Our results implicate L1 in the regulation of DC trafficking and shed light on novel mechanisms underlying transendothelial migration of DCs. These observations might offer novel therapeutic perspectives for the treatment of certain immunological disorders.

Show MeSH

Related in: MedlinePlus

L1 is required for DC transendothelial migration and trafficking tolymph nodes. (A) For apical-to-basal transmigration assays,SV-LEC (left) or 1G11 cells (right) were seeded on the upper side ofgelatin-coated Transwell filters and allowed to form dense monolayers.For basal-to-apical migration assays (middle), SV-LECs were cultured onthe bottom side of the filters. ECs were pretreated with TNF-αbefore transmigration assays. CFSE-labeled bone marrow–derivedDCs from L1floxed andTie2-Cre;L1floxed mice were added tothe upper chamber of Transwell inserts. After 3 h, DC transmigration wasmeasured as described in Materials and methods. Data represent the means± SD of representative experiments performed in triplicatewith DCs from five mice for each genotype. *, P < 0.05;**, P < 0.005 (relative toL1floxed DCs). (B) FITC skin paintingwas performed on the abdomen of L1floxed orTie2-Cre;L1floxed mice. After 24 h,inguinal lymph nodes were excised and subjected to FACS analysis forFITC and CD11c. Data are expressed as the percentage of FITC-positivecells and represent the means ± SD of a representativeexperiment (six mice per group) out of three performed. *, P< 0.05 (relative to relative toL1floxed mice). (C) FITC-positive cells ininguinal lymph nodes (left) were gated and analyzed for L1 and CD11cexpression (right).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2664975&req=5

fig3: L1 is required for DC transendothelial migration and trafficking tolymph nodes. (A) For apical-to-basal transmigration assays,SV-LEC (left) or 1G11 cells (right) were seeded on the upper side ofgelatin-coated Transwell filters and allowed to form dense monolayers.For basal-to-apical migration assays (middle), SV-LECs were cultured onthe bottom side of the filters. ECs were pretreated with TNF-αbefore transmigration assays. CFSE-labeled bone marrow–derivedDCs from L1floxed andTie2-Cre;L1floxed mice were added tothe upper chamber of Transwell inserts. After 3 h, DC transmigration wasmeasured as described in Materials and methods. Data represent the means± SD of representative experiments performed in triplicatewith DCs from five mice for each genotype. *, P < 0.05;**, P < 0.005 (relative toL1floxed DCs). (B) FITC skin paintingwas performed on the abdomen of L1floxed orTie2-Cre;L1floxed mice. After 24 h,inguinal lymph nodes were excised and subjected to FACS analysis forFITC and CD11c. Data are expressed as the percentage of FITC-positivecells and represent the means ± SD of a representativeexperiment (six mice per group) out of three performed. *, P< 0.05 (relative to relative toL1floxed mice). (C) FITC-positive cells ininguinal lymph nodes (left) were gated and analyzed for L1 and CD11cexpression (right).

Mentions: We next asked whether the loss of L1 also affected the migration of DCs across alymphatic endothelial barrier. Both basal-to-apical and apical-to-basaldirections were tested to mimic intra- and extravasation of DCs, respectively.By analogy to cell adhesion, the migration rate of L1-deficient DCs through alymphatic endothelial monolayer was markedly lower than that of control cells(Fig. 3 A). L1 was required for bothapical-to-basal and basal-to-apical DC transmigration (Fig. 3 A, left and middle). Moreover, becausetransendothelial migration of DCs also occurs across the wall of blood vessels(12), we included blood vascularECs in our transmigration assays, using the mouse EC line 1G11 (15). As in the case of LECs, the loss ofL1 resulted in the impairment of DC migration through 1G11 monolayers (Fig. 3 A, right), implicating L1 in thetrafficking of DCs across both lymphatic and blood vessel walls. Very similarresults were obtained when the transendothelial migration of either immature ormature DCs across lymphatic or blood vessel ECs was stimulated by the chemokinesCCL3 or CCL19, respectively (Fig. S4 A). Notably, L1 deficiency by itself didnot affect the migratory ability of DCs, as neither the chemotactic migrationtoward the CCL3 or CCL19 chemokines (Fig. S4 B) nor the motility of DCs withinthree-dimensional collagen type I matrix (not depicted) were affected inTie2-Cre;L1floxed DCs. This argued against acell autonomous effect of L1 on DC motility and further supported its specificinvolvement in DC–EC interactions.


The adhesion molecule L1 regulates transendothelial migration and trafficking of dendritic cells.

Maddaluno L, Verbrugge SE, Martinoli C, Matteoli G, Chiavelli A, Zeng Y, Williams ED, Rescigno M, Cavallaro U - J. Exp. Med. (2009)

L1 is required for DC transendothelial migration and trafficking tolymph nodes. (A) For apical-to-basal transmigration assays,SV-LEC (left) or 1G11 cells (right) were seeded on the upper side ofgelatin-coated Transwell filters and allowed to form dense monolayers.For basal-to-apical migration assays (middle), SV-LECs were cultured onthe bottom side of the filters. ECs were pretreated with TNF-αbefore transmigration assays. CFSE-labeled bone marrow–derivedDCs from L1floxed andTie2-Cre;L1floxed mice were added tothe upper chamber of Transwell inserts. After 3 h, DC transmigration wasmeasured as described in Materials and methods. Data represent the means± SD of representative experiments performed in triplicatewith DCs from five mice for each genotype. *, P < 0.05;**, P < 0.005 (relative toL1floxed DCs). (B) FITC skin paintingwas performed on the abdomen of L1floxed orTie2-Cre;L1floxed mice. After 24 h,inguinal lymph nodes were excised and subjected to FACS analysis forFITC and CD11c. Data are expressed as the percentage of FITC-positivecells and represent the means ± SD of a representativeexperiment (six mice per group) out of three performed. *, P< 0.05 (relative to relative toL1floxed mice). (C) FITC-positive cells ininguinal lymph nodes (left) were gated and analyzed for L1 and CD11cexpression (right).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2664975&req=5

fig3: L1 is required for DC transendothelial migration and trafficking tolymph nodes. (A) For apical-to-basal transmigration assays,SV-LEC (left) or 1G11 cells (right) were seeded on the upper side ofgelatin-coated Transwell filters and allowed to form dense monolayers.For basal-to-apical migration assays (middle), SV-LECs were cultured onthe bottom side of the filters. ECs were pretreated with TNF-αbefore transmigration assays. CFSE-labeled bone marrow–derivedDCs from L1floxed andTie2-Cre;L1floxed mice were added tothe upper chamber of Transwell inserts. After 3 h, DC transmigration wasmeasured as described in Materials and methods. Data represent the means± SD of representative experiments performed in triplicatewith DCs from five mice for each genotype. *, P < 0.05;**, P < 0.005 (relative toL1floxed DCs). (B) FITC skin paintingwas performed on the abdomen of L1floxed orTie2-Cre;L1floxed mice. After 24 h,inguinal lymph nodes were excised and subjected to FACS analysis forFITC and CD11c. Data are expressed as the percentage of FITC-positivecells and represent the means ± SD of a representativeexperiment (six mice per group) out of three performed. *, P< 0.05 (relative to relative toL1floxed mice). (C) FITC-positive cells ininguinal lymph nodes (left) were gated and analyzed for L1 and CD11cexpression (right).
Mentions: We next asked whether the loss of L1 also affected the migration of DCs across alymphatic endothelial barrier. Both basal-to-apical and apical-to-basaldirections were tested to mimic intra- and extravasation of DCs, respectively.By analogy to cell adhesion, the migration rate of L1-deficient DCs through alymphatic endothelial monolayer was markedly lower than that of control cells(Fig. 3 A). L1 was required for bothapical-to-basal and basal-to-apical DC transmigration (Fig. 3 A, left and middle). Moreover, becausetransendothelial migration of DCs also occurs across the wall of blood vessels(12), we included blood vascularECs in our transmigration assays, using the mouse EC line 1G11 (15). As in the case of LECs, the loss ofL1 resulted in the impairment of DC migration through 1G11 monolayers (Fig. 3 A, right), implicating L1 in thetrafficking of DCs across both lymphatic and blood vessel walls. Very similarresults were obtained when the transendothelial migration of either immature ormature DCs across lymphatic or blood vessel ECs was stimulated by the chemokinesCCL3 or CCL19, respectively (Fig. S4 A). Notably, L1 deficiency by itself didnot affect the migratory ability of DCs, as neither the chemotactic migrationtoward the CCL3 or CCL19 chemokines (Fig. S4 B) nor the motility of DCs withinthree-dimensional collagen type I matrix (not depicted) were affected inTie2-Cre;L1floxed DCs. This argued against acell autonomous effect of L1 on DC motility and further supported its specificinvolvement in DC–EC interactions.

Bottom Line: In agreement with these findings, L1 was expressed in cutaneous DCs that migrated to draining lymph nodes, and its ablation reduced DC trafficking in vivo.Within the skin, L1 was found in Langerhans cells but not in dermal DCs, and L1 deficiency impaired Langerhans cell migration.Our results implicate L1 in the regulation of DC trafficking and shed light on novel mechanisms underlying transendothelial migration of DCs.

View Article: PubMed Central - PubMed

Affiliation: The FIRC Institute of Molecular Oncology, 20139 Milan, Italy.

ABSTRACT
The adhesion molecule L1, which is extensively characterized in the nervous system, is also expressed in dendritic cells (DCs), but its function there has remained elusive. To address this issue, we ablated L1 expression in DCs of conditional knockout mice. L1-deficient DCs were impaired in adhesion to and transmigration through monolayers of either lymphatic or blood vessel endothelial cells, implicating L1 in transendothelial migration of DCs. In agreement with these findings, L1 was expressed in cutaneous DCs that migrated to draining lymph nodes, and its ablation reduced DC trafficking in vivo. Within the skin, L1 was found in Langerhans cells but not in dermal DCs, and L1 deficiency impaired Langerhans cell migration. Under inflammatory conditions, L1 also became expressed in vascular endothelium and enhanced transmigration of DCs, likely through L1 homophilic interactions. Our results implicate L1 in the regulation of DC trafficking and shed light on novel mechanisms underlying transendothelial migration of DCs. These observations might offer novel therapeutic perspectives for the treatment of certain immunological disorders.

Show MeSH
Related in: MedlinePlus