Characterization of Prox1 and VEGFR-3 Expression and Lymphatic Phenotype in Normal Organs of Mice Lacking p50 Subunit of NF-κB

P>Objective: Inflammation and NF-kappa B are highly associated with lymphangiogenesis but the underlying mechanisms remain unclear. We recently established that activated NF-kappa B p50 subunit increases expression of the main lymphangiogenic mediators, VEGFR-3 and its transcriptional activator, Prox1. To elucidate the role of p50 in lymphatic vasculature, we compared LVD and phenotype in p50 KO and WT mice. Methods: Normal tissues from KO and WT mice were stained for LYVE-1 to calculate LVD. VEGFR-3 and Prox1 expressions were analyzed by immunofluorescence and qRT-PCR. Results: Compared with WT, LVD in the liver and lungs of KO mice was reduced by 39% and 13%, respectively. This corresponded to 25-44% decreased VEGFR-3 and Prox1 expression. In the MFP, LVD was decreased by 18% but VEGFR-3 and Prox1 expression was 80-140% higher than in WT. Analysis of p65 and p52 NF-kappa B subunits and an array of inflammatory mediators showed a significant increase in p50 alternative pathways in the MFP but not in other organs. Conclusions: These findings demonstrate the role of NF-kappa B p50 in regulating the expression of VEGFR-3, Prox1 and LVD in the mammary tissue, liver, and lung.