The normal human choroid is endowed with a significant number of lymphatic vessel endothelial hyaluronate receptor 1 (LYVE-1)-positive macrophages.
OBJECTIVE
Lymphatic vessel endothelial hyaluronic acid receptor (LYVE-1) is a newly discovered lymphatic endothelium-specific marker that is also expressed by a subpopulation of macrophages. To date, there is no report on its expression in the posterior human uvea. The purpose of this study was to investigate the expression of LYVE-1 in normal human choroids.


METHODS
Eyes of body/cornea donors (55-89 years of age; 4-9 hours postmortem) were obtained. Choroids were dissected and prepared for cryosections followed by immunohistochemistry with anti-human LYVE-1 antiserum and immunogold labeling. In addition, anti-human antibodies against macrophage markers (CD68, MHC class II) and lymphatic (podoplanin) and blood vascular endothelium (CD31, vWF) were used. For documentation, light-, fluorescence-, confocal laser scanning-, and electron-microscopy were used.


RESULTS
The normal human choroidal stroma contained 274 +/- 86 LYVE-1 positive cells/mm(2). The cells displayed irregular shapes with a relatively uniform diameter of 32 mum. Costaining with CD68 and negativity for CD31, podoplanin, and melan-A/HMB45, as well as electron microscopic features, suggest these LYVE-1(+) cells to be macrophages. Besides that, no classic LYVE-1(+)/podoplanin(+) lymphatic vessels were detected within the normal adult human choroid.


CONCLUSIONS
The normal adult human choroid does not contain typical lymph vessels, but is endowed with a significant number of LYVE-1 positive macrophages. These cells may be involved in choroidal hyaluronic acid metabolism or contribute to temporary formation of lymphatic channels under inflammatory conditions.
Schroedl
Falk
F
Department of Anatomy I, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany. falk.schroedl@anatomie1.med.uni-erlangen.de
Brehmer
Axel
A
Neuhuber
Winfried L
WL
Kruse
Friedrich E
FE
May
C Albrecht
CA
Cursiefen
Claus
C
D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D015415:Biomarkers; D002829:Choroid / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D042601:Lymphatic Vessels / Q000502:physiology; D008264:Macrophages / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D014841:von Willebrand Factor / Q000378:metabolism; D000097382:CD68 Molecule; D000098853:Podoplanin
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; D000949:Histocompatibility Antigens Class II; D008562:Membrane Glycoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D033921:Vesicular Transport Proteins; D014841:von Willebrand Factor; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C119248:LYVE1 protein, human; C117468:PDPN protein, human; D000098853:Podoplanin