Down-regulation of VEGFR-3 during acute skin inflammation. (A-B) TaqMan-based real-time RT-PCR analyses were performed on whole ear and back skin extracts after 2 days of oxazolone challenge (2-day oxa; n = 6-10 per group) or UVB irradiation (2-day UVB; n = 5-8 per group) and in untreated K14-VEGF-C, K14-VEGF-D Tg, and wild-type mice (n = 3-5 per group). VEGFR-3 was significantly up-regulated in untreated K14-VEGF-C and K14-VEGF-D Tg mouse ear (A) and back skin (B) compared with untreated wild-type mice. VEGFR-3 was significantly down-regulated at 2 days of oxazolone challenge (A) or UVB irradiation (B) in all 3 groups of mice compared with untreated mice of the same genotype. (C-D) Single-cell suspensions from the ear of normal and oxazolone challenged mice were analyzed by FACS. (C) CD31⁺/CD45⁻ cells represent endothelial cells, whereas CD31⁺/podoplanin⁺/CD45⁻ cells are lymphatic endothelial cells. (D) Cutaneous lymphatic endothelial cells from inflamed ears of wild-type mice (2 days after oxazolone challenge) showed a 5-fold decrease of VEGFR-3 mRNA transcript levels compared with lymphatic endothelial cells from untreated mice. (A-B,D) Data are mean ± SD. ‡‡‡P ≤ .001 versus untreated wild-type. ***P ≤ .001 versus untreated mice of the same genotype. (E-F) Double immunofluorescence analyses of VEGFR-3 (red) and LYVE-1 (green) stains demonstrated that VEGFR-3 was strongly down-regulated on LYVE-1⁺ lymphatic vessels at 2 days after oxazolone challenge (E) or UVB irradiation (F) in the ear and back skin of wild-type mice (arrows). The positive staining of LYVE-1 in the stratum corneum (E) is unspecific. Bars represent 100 μm.