Abstract
Purpose: :
To investigate the expression of lymphendothelial (LEC) markers in tissues of the anterior eye chamber (AC).
Methods: :
Sections of human ACs from 10 eyes from 10 donors (37-100 years) were stained by immunofluorescence for Vegf-R3, Prox-1, Lyve-1 and Pdpn. Pdpn localization was additionally analyzed by immunogoldlabeling on ultrathin sections of 5 eyes. Expression of LEC markers, chemokine receptor (CCR) 7 and its ligands (CCL) 19 and 21 was analyzed by RT-PCR in iris tissue, trabecular meshwork (TM) tissue obtained from 5 eyes and 10 different human TM (hTM) cell cultures.
Results: :
For Vegf-R3 and Prox-1 no signals were obtained in the AC. Lyve-1 stained single dendriform cells in the iris, the ciliary body (CB) and in the TM. Pdpn stained all trabecular endothelial cells, but not the endtohelium of Schlemm’s canal. They reacted to a podocalyxin antibody, a marker for vascular capillaries. Cells of the trabeculum ciliare and the perimysium cells in the most anterior part of the ciliary muscle (CM), but not the CM cells, were Pdpn+. Within the iris stroma single dendriform cells were stained, at the anterior surface almost all cells were Pdpn+. Expression of Pdpn and Lyve-1 in the iris, and Pdpn but not Lyve-1 in the TM was confirmed by PCR. Expression of Prox-1 was additionally detected in both tissues. Both tissues and hTM cells expressed CCL19 and CCL21, CCR7 was found in the iris only.
Conclusions: :
. Pdpn expression in the TM and the anterior iris surface toghether with concurrent expression of the CCR7 ligands CCL19 and CCL21 suggests the existence of an active guidance mechanism directing the migration of APCs in the AC. Binding of CCL1 to Pdpn could constitute a gradient towards (i) the anterior iris surface were APCs enter the AC and (ii) towards the TM, were APCs can leave the AC.
Keywords: antigen presentation/processing • outflow: trabecular meshwork • cytokines/chemokines