When the cornea is inflamed, blood and lymphatic vessels grow into it. But the cornea is typically an avascular area. In a new study appearing in the September 1 print issue of The Journal of Clinical Investigation, Joan Streilein and colleagues from the Schepens Eye Institute examine which cells generate these new lymphatic vessels in the cornea. The authors find that innate immune cells, in particular macrophages, contribute to this vessel formation during abnormal corneal conditions, and that bone marrow derived macrophages express lymphatic markers under conditions of corneal inflammation. These findings suggest a new mechanism of the formation of lymph vessels, where macrophages are responsible during inflammation.
In a related commentary, Dontscho Kerjaschki writes, "these findings add yet another facet to the plasticity of macrophages, which are already known to transform from na´ve monocytes into VEGF-producing cells. Thus, macrophages support lymphangiogenesis in 2 different ways, either by transdifferentiating and directly incorporating into the endothelial layer or by stimulating division of preexistent local lymphatic endothelial cells."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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