Abstract
Purpose: :
The naïve cornea is endowed with distinct populations of bone marrow (BM)-derived cells, whose number increases significantly during inflammation. To date, systematic in vivo studies have not been applied to study the recruitment mechanisms of BM-derived cells to the cornea. The purpose of this study was to develop an intravital imaging model to study the molecular mechanisms involved in immune cell recruitment to the cornea.
Methods: :
Epifluorescent Intravital Microscopy (Epi-IVM- 500 Mikron Instruments) with a 10x (Zeiss Achroplan, NA 0.3) water immersion lens was applied to study limbal and corneal microvessels. CD11c+ dendritic cells (DC) were isolated from the spleen of Ftl3 tumor BALB/c mice and stained with Calcein, AM. Epi- IVM was performed on naïve and neovascularized corneas, induced by stromal suture placement. Naïve DCs were injected into untreated hosts or hosts pre-treated with anti-P-Selectin, anti-E- Selectin or both. In addition anti-CD44-treated DCs were injected in untreated mice.
Results: :
Visualization of limbal vessels clearly demonstrated rolling and sticking of DCs along the vascular bed. The rolling fraction (RFx; rolling cells/total cells) was significantly (p<0.05) reduced by anti-P-Selectin and/or anti-E-Selectin. P-/E- Selectin blockade was more efficient than anti-P-Selectin alone, followed by anti-E-Selectin. Anti-CD44 treatment of DCs had only moderate effect on RF. Sticking Fraction (SFx- sticking cells/rolling cells) was not significantly affected in any group.
Conclusions: :
Intravital microscopy is feasible to demonstrate migration of DC to the corneal and enables the dissection of molecular mechanisms involved in immune cell homing to the cornea. The current data demonstrate that DC homing to the cornea is mediated by P- and E-Selectin.
Keywords: immunomodulation/immunoregulation • inflammation • cornea: basic science