Visualization of Intrapulmonary Lymph Vessels in Healthy and Inflamed Murine Lung Using CD90/Thy-1 as a Marker

Abstract

BackgroundLymphatic vessels play a pivotal role in fluid drainage and egress of immune cells from the lung. However, examining murine lung lymphatics is hampered by the expression of classical lymph endothelial markers on other cell types, which hinders the unambiguous identification of lymphatics. The expression of CD90/Thy-1 on lymph endothelium was recently described and we therefore examined its suitability to identify murine pulmonary lymph vessels under healthy and inflammatory conditions.Methodology/Principal FindingsImmunohistochemistry with a monoclonal antibody against CD90.2/Thy-1.2 on 200 µm thick precision cut lung slices labeled a vascular network that was distinct from blood vessels. Preembedding immunostaining and electron microscopy verified that the anti-CD90.2/Thy-1.2 antibody labeled lymphatic endothelium. Absence of staining in CD90.1/Thy-1.1 expressing FVB mice indicated that CD90/Thy-1 was expressed on lymph endothelium and labeling was not due to antibody cross reactivity. Double-labeling immunohistochemistry for CD90/Thy-1 and α-smooth muscle actin identified two routes for lymph vessel exit from the murine lung. One started in the parenchyma or around veins and left via venous blood vessels. The other began in the space around airways or in the space between airways and pulmonary arteries and left via the main bronchi. As expected from the pulmonary distribution of lymph vessels, intranasal application of house dust mite led to accumulation of T cells around veins and in the connective tissue between airways and pulmonary arteries. Surprisingly, increased numbers of T cells were also detected around intraacinar arteries that lack lymph vessels. This arterial T cell sheath extended to the pulmonary arteries where lymph vessels were located.Conclusions/SignificanceThese results indicate that CD90/Thy-1 is expressed on lymphatic endothelial cells and represents a suitable marker for murine lung lymph vessels. Combining CD90/Thy-1 labeling with precision cut lung slices allows visualizing the anatomy of the lymphatic system in normal and inflamed conditions.

Thy1+IL-7+lymphatic endothelial cells in iBALT provide a survival niche for memory T-helper cells in allergic airway inflammation

“…These LECs were the major IL-7-producing cells in the iBALT, and more than 90% of memory Th2 cells were in direct contact with the IL-7-producing LECs in the lung. Consistent with previous studies showing that LECs in the lung express Thy1 (28,29), and that IL-7 is produced by LECs (25), our data indicate that the majority of Podoplanin + PECAM1 + cells (i.e., LECs) are the IL-7-producing cells in the lung (Fig. 5D), and these cells specifically express Thy1 (Fig.…”

“…5F). Consistent with the previous reports that showed Thy1 is expressed on LECs in the lung (28,29), our data indicate that Thy1 can be used as a useful marker for IL-7-producing LECs in the lung. (1 x 10 7 )…”

Blockade of FLT4 suppresses metastasis of melanoma cells by impaired lymphatic vessels

“…Proliferating lymphatic vessels in the intratumoral region and peritumoral region were counted by Ki67 þ FLT4 þ co-staining. Lymphatic vessels are located between blood vessels and airways in connective tissues [21]. Both the intratumoral and peritumoral regions revealed that Ki67 þ FLT4 þ lymphatic endothelium was decreased in the MAZ51-injected group compared to that of melanoma-injected groups (Fig.…”

Lymphangiogenesis Is Induced by Mycobacterial Granulomas via Vascular Endothelial Growth Factor Receptor-3 and Supports Systemic T-Cell Responses against Mycobacterial Antigen

“…Additionally, we confirmed the specificity of LYVE-1 as a marker of lymphatic cells by staining with other and recently identified lymphatic markers such as CD90.2 (data not shown). 42,43 To show that resident mycobacterial-specific T cells, DCs, and BCG are in proximity to lymphatic vessels, we infected CD11c-eYFP mice. CD11c was expressed on liver-resident DCs, to a lesser extent on Kupffer cells, and on inflammatory DCs.…”