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Lymphotoxin beta receptor signaling promotes tertiary lymphoid organogenesis in the aorta adventitia of aged ApoE-/- mice.

Gräbner R, Lötzer K, Döpping S, Hildner M, Radke D, Beer M, Spanbroek R, Lippert B, Reardon CA, Getz GS, Fu YX, Hehlgans T, Mebius RE, van der Wall M, Kruspe D, Englert C, Lovas A, Hu D, Randolph GJ, Weih F, Habenicht AJ - J. Exp. Med. (2009)

Bottom Line: These signals in turn trigger the development of elaborate bona fide adventitial aortic tertiary lymphoid organs (ATLOs) containing functional conduit meshworks, germinal centers within B cell follicles, clusters of plasma cells, high endothelial venules (HEVs) in T cell areas, and a high proportion of T regulatory cells.Treatment of apoE(-/-) mice with LTbetaR-Ig to interrupt LTbetaR signaling in SMCs strongly reduced HEV abundance, CXCL13, and CCL21 expression, and disrupted the structure and maintenance of ATLOs.Thus, the LTbetaR pathway has a major role in shaping the immunological characteristics and overall integrity of the arterial wall.

View Article: PubMed Central - PubMed

Affiliation: Institute for Vascular Medicine, Friedrich Schiller University of Jena, 07743 Jena, Germany.

ABSTRACT
Atherosclerosis involves a macrophage-rich inflammation in the aortic intima. It is increasingly recognized that this intimal inflammation is paralleled over time by a distinct inflammatory reaction in adjacent adventitia. Though cross talk between the coordinated inflammatory foci in the intima and the adventitia seems implicit, the mechanism(s) underlying their communication is unclear. Here, using detailed imaging analysis, microarray analyses, laser-capture microdissection, adoptive lymphocyte transfers, and functional blocking studies, we undertook to identify this mechanism. We show that in aged apoE(-/-) mice, medial smooth muscle cells (SMCs) beneath intimal plaques in abdominal aortae become activated through lymphotoxin beta receptor (LTbetaR) to express the lymphorganogenic chemokines CXCL13 and CCL21. These signals in turn trigger the development of elaborate bona fide adventitial aortic tertiary lymphoid organs (ATLOs) containing functional conduit meshworks, germinal centers within B cell follicles, clusters of plasma cells, high endothelial venules (HEVs) in T cell areas, and a high proportion of T regulatory cells. Treatment of apoE(-/-) mice with LTbetaR-Ig to interrupt LTbetaR signaling in SMCs strongly reduced HEV abundance, CXCL13, and CCL21 expression, and disrupted the structure and maintenance of ATLOs. Thus, the LTbetaR pathway has a major role in shaping the immunological characteristics and overall integrity of the arterial wall.

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ATLO conduits connect media SMCs with ATLO compartments and facilitate transport of small molecular weight molecules. (a) Conduits connect the media (M) with HEVs. ECM meshwork (ER-TR7; top left, open arrows) associated with (top left, asterisk) and enfolded by 8.1.1+ fibroblastic reticular cells (top right, filled arrows). Conduit pseudolumen (inset, top right). Conduits at the ATLO periphery (ER-TR7) connect the media with HEVs (bottom panels, arrow; Fig. S4 and Video 2; Fig. S5 and Video 3). (b) ATLO conduits transport low molecular weight molecules. 10 or 500 kD fluorescent dextran was injected i.v.; 15 min later, ATLOs were prepared as described in Materials and methods. Dotted lines indicate ATLO/media border. Note presence of 500 kD dextran in HEV (bottom right) and presence of 10 kD, but not 500 kD, dextran in media. Bars, 50 μm.
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fig5: ATLO conduits connect media SMCs with ATLO compartments and facilitate transport of small molecular weight molecules. (a) Conduits connect the media (M) with HEVs. ECM meshwork (ER-TR7; top left, open arrows) associated with (top left, asterisk) and enfolded by 8.1.1+ fibroblastic reticular cells (top right, filled arrows). Conduit pseudolumen (inset, top right). Conduits at the ATLO periphery (ER-TR7) connect the media with HEVs (bottom panels, arrow; Fig. S4 and Video 2; Fig. S5 and Video 3). (b) ATLO conduits transport low molecular weight molecules. 10 or 500 kD fluorescent dextran was injected i.v.; 15 min later, ATLOs were prepared as described in Materials and methods. Dotted lines indicate ATLO/media border. Note presence of 500 kD dextran in HEV (bottom right) and presence of 10 kD, but not 500 kD, dextran in media. Bars, 50 μm.

Mentions: Although gene expression patterns were distinct between the adventitia and plaques, the dependence of ATLOs on intimal lesion development suggested that the compartments communicate. Antigen reaches LNs via migration of antigen-loaded DCs or via directed diffusion through a specialized conduit system that connects afferent lymph vessels and HEVs (20–22). Conduits have not previously been studied in TLOs (23). Owing to their size, conduits cannot transport cells but form a reticular meshwork of fibers consisting of a rodlike core of collagen I wrapped by extracellular matrix sheaths enfolded by podoplanin-expressing fibroblastic reticular cells. Staining with ER-TR7 (unknown antigen) and 8.1.1 (podoplanin/gp38) revealed a reticular meshwork of cordlike structures (Fig. 5 a) in ATLOs. ER-TR7/8.1.1/DAPI staining confirmed colocalization of 8.1.1 with fibroblastic reticular cells adjacent to ER-TR7+ cords (Fig. 5 a, top). ATLO conduits were further identified by their small diameter (conduits, ∼2 μm; capillaries, ∼4 μm), the absence of MECA-32 staining, and the presence of a collagen I core (unpublished data). Because conduits near the adventitia-media border appeared denser, we examined whether they extend into the media. 3D reconstruction of high resolution laser scanning microscopy of stage III ATLOs revealed that ATLO conduits extended into the media gaining access to HEVs of ATLO T areas and other ATLO compartments (Fig. 5 a, bottom left; Fig. S6; Fig. S7 and Video 2; and Fig. S8 and Video 3, available at http://www.jem.org/cgi/content/full/jem.20080752/DC1). To explore the functionality of ATLO conduits in vivo we used fluorescent dextran particles. After i.v. application, 10 kD dextran, but not 500 kD dextran, particles were taken up by ATLO conduits similar to LN conduits (Fig. 5 b and not depicted). Thus, ATLO conduits resemble LN conduits in size, marker expression, and transport function and establish newly formed structures connecting the adventitia to the media.


Lymphotoxin beta receptor signaling promotes tertiary lymphoid organogenesis in the aorta adventitia of aged ApoE-/- mice.

Gräbner R, Lötzer K, Döpping S, Hildner M, Radke D, Beer M, Spanbroek R, Lippert B, Reardon CA, Getz GS, Fu YX, Hehlgans T, Mebius RE, van der Wall M, Kruspe D, Englert C, Lovas A, Hu D, Randolph GJ, Weih F, Habenicht AJ - J. Exp. Med. (2009)

ATLO conduits connect media SMCs with ATLO compartments and facilitate transport of small molecular weight molecules. (a) Conduits connect the media (M) with HEVs. ECM meshwork (ER-TR7; top left, open arrows) associated with (top left, asterisk) and enfolded by 8.1.1+ fibroblastic reticular cells (top right, filled arrows). Conduit pseudolumen (inset, top right). Conduits at the ATLO periphery (ER-TR7) connect the media with HEVs (bottom panels, arrow; Fig. S4 and Video 2; Fig. S5 and Video 3). (b) ATLO conduits transport low molecular weight molecules. 10 or 500 kD fluorescent dextran was injected i.v.; 15 min later, ATLOs were prepared as described in Materials and methods. Dotted lines indicate ATLO/media border. Note presence of 500 kD dextran in HEV (bottom right) and presence of 10 kD, but not 500 kD, dextran in media. Bars, 50 μm.
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fig5: ATLO conduits connect media SMCs with ATLO compartments and facilitate transport of small molecular weight molecules. (a) Conduits connect the media (M) with HEVs. ECM meshwork (ER-TR7; top left, open arrows) associated with (top left, asterisk) and enfolded by 8.1.1+ fibroblastic reticular cells (top right, filled arrows). Conduit pseudolumen (inset, top right). Conduits at the ATLO periphery (ER-TR7) connect the media with HEVs (bottom panels, arrow; Fig. S4 and Video 2; Fig. S5 and Video 3). (b) ATLO conduits transport low molecular weight molecules. 10 or 500 kD fluorescent dextran was injected i.v.; 15 min later, ATLOs were prepared as described in Materials and methods. Dotted lines indicate ATLO/media border. Note presence of 500 kD dextran in HEV (bottom right) and presence of 10 kD, but not 500 kD, dextran in media. Bars, 50 μm.
Mentions: Although gene expression patterns were distinct between the adventitia and plaques, the dependence of ATLOs on intimal lesion development suggested that the compartments communicate. Antigen reaches LNs via migration of antigen-loaded DCs or via directed diffusion through a specialized conduit system that connects afferent lymph vessels and HEVs (20–22). Conduits have not previously been studied in TLOs (23). Owing to their size, conduits cannot transport cells but form a reticular meshwork of fibers consisting of a rodlike core of collagen I wrapped by extracellular matrix sheaths enfolded by podoplanin-expressing fibroblastic reticular cells. Staining with ER-TR7 (unknown antigen) and 8.1.1 (podoplanin/gp38) revealed a reticular meshwork of cordlike structures (Fig. 5 a) in ATLOs. ER-TR7/8.1.1/DAPI staining confirmed colocalization of 8.1.1 with fibroblastic reticular cells adjacent to ER-TR7+ cords (Fig. 5 a, top). ATLO conduits were further identified by their small diameter (conduits, ∼2 μm; capillaries, ∼4 μm), the absence of MECA-32 staining, and the presence of a collagen I core (unpublished data). Because conduits near the adventitia-media border appeared denser, we examined whether they extend into the media. 3D reconstruction of high resolution laser scanning microscopy of stage III ATLOs revealed that ATLO conduits extended into the media gaining access to HEVs of ATLO T areas and other ATLO compartments (Fig. 5 a, bottom left; Fig. S6; Fig. S7 and Video 2; and Fig. S8 and Video 3, available at http://www.jem.org/cgi/content/full/jem.20080752/DC1). To explore the functionality of ATLO conduits in vivo we used fluorescent dextran particles. After i.v. application, 10 kD dextran, but not 500 kD dextran, particles were taken up by ATLO conduits similar to LN conduits (Fig. 5 b and not depicted). Thus, ATLO conduits resemble LN conduits in size, marker expression, and transport function and establish newly formed structures connecting the adventitia to the media.

Bottom Line: These signals in turn trigger the development of elaborate bona fide adventitial aortic tertiary lymphoid organs (ATLOs) containing functional conduit meshworks, germinal centers within B cell follicles, clusters of plasma cells, high endothelial venules (HEVs) in T cell areas, and a high proportion of T regulatory cells.Treatment of apoE(-/-) mice with LTbetaR-Ig to interrupt LTbetaR signaling in SMCs strongly reduced HEV abundance, CXCL13, and CCL21 expression, and disrupted the structure and maintenance of ATLOs.Thus, the LTbetaR pathway has a major role in shaping the immunological characteristics and overall integrity of the arterial wall.

View Article: PubMed Central - PubMed

Affiliation: Institute for Vascular Medicine, Friedrich Schiller University of Jena, 07743 Jena, Germany.

ABSTRACT
Atherosclerosis involves a macrophage-rich inflammation in the aortic intima. It is increasingly recognized that this intimal inflammation is paralleled over time by a distinct inflammatory reaction in adjacent adventitia. Though cross talk between the coordinated inflammatory foci in the intima and the adventitia seems implicit, the mechanism(s) underlying their communication is unclear. Here, using detailed imaging analysis, microarray analyses, laser-capture microdissection, adoptive lymphocyte transfers, and functional blocking studies, we undertook to identify this mechanism. We show that in aged apoE(-/-) mice, medial smooth muscle cells (SMCs) beneath intimal plaques in abdominal aortae become activated through lymphotoxin beta receptor (LTbetaR) to express the lymphorganogenic chemokines CXCL13 and CCL21. These signals in turn trigger the development of elaborate bona fide adventitial aortic tertiary lymphoid organs (ATLOs) containing functional conduit meshworks, germinal centers within B cell follicles, clusters of plasma cells, high endothelial venules (HEVs) in T cell areas, and a high proportion of T regulatory cells. Treatment of apoE(-/-) mice with LTbetaR-Ig to interrupt LTbetaR signaling in SMCs strongly reduced HEV abundance, CXCL13, and CCL21 expression, and disrupted the structure and maintenance of ATLOs. Thus, the LTbetaR pathway has a major role in shaping the immunological characteristics and overall integrity of the arterial wall.

Show MeSH
Related in: MedlinePlus