Abstract
Purpose: :
Several (lymph-) angiogenic candidate genes were found to be differentially expressed between C57BL/6 and BALB/c or FVB mice with significantly more resting limbal vasculature in the former strain than the latter two. One of the candidate genes, TRAIL/Tnfsf10 was analyzed in greater detail to obtain insights into its effect on lymphatic endothelial cells.
Methods: :
Corneal RNA was isolated and cDNA synthesis was carried out with SuperScriptTM III First-Strand Synthesis SuperMix. The cDNA was used for real-time PCR analyses. Lymphatic endothelial cell proliferation was analysed using BrdU incorporation into newly synthesized DNA. Surface expression of a corresponding death receptor of TRAIL (TRAIL-R2/DR5) was assessed by FACS analysis and immunocytochemistry.
Results: :
Expression of TRAIL mRNA was increased 8.2-fold in BALB/c and 6.6-fold in FVB corneas compared to the C57BL/6 control corneas. This expression pattern corresponded with the decreased limbal vasculature in BALB/c and FVB compared to C57BL/6. Treatment of HMVECs with different concentrations of recombinant TRAIL in endothelial cell basal medium (containing 0.5 % FBS) resulted in a small, but significant inhibition of proliferation at a concentration of 1 ng/ml TRAIL. Flow cytometric analysis of surface expression of TRAIL-R2/DR5 (a corresponding death receptor of TRAIL) on HMVECs confirmed the presence of a ligand for TRAIL with an increased expression detectable after TNFα treatment (1 ng/ml and 100 ng/ml).
Conclusions: :
Corneal expression of TRAIL may play an inhibitory role in lymphatic endothelial cell biology. Further studies are needed to clarify the detailed function of TRAIL in lymphangiogenesis.
Keywords: cornea: clinical science • inflammation • immune tolerance/privilege