Figure 6.

Hypercholesterolemia in apoE^−/− mice is associated with abnormal collecting vessels. Immunostaining for LYVE-1, podoplanin, and smooth muscle actin (SMA) in ear skin whole mounts was performed to identify collecting vessels in wild-type (WT) and apoE^−/− mice at 4 to 6 (A) or 16 to 33 weeks of age maintained on a chow or high-fat diet (B, C). As observed in age-matched wild-type mice, LYVE-1 expression remained high in initial lymphatics of 4- to 6-week-old apoE^−/− mice (A), and LYVE-1 was down-regulated or abrogated on podoplanin-positive collecting vessels, which were covered with smooth muscle cells (arrows). As expected, the coverage with smooth muscle actin-expressing cells of lymphatic vessel was sparser (arrows) than in the blood vessels (arrowheads). In contrast, podoplanin-positive lymphatic vessels in 16- to 33-week-old apoE^−/− mice fed a chow or high-fat diet failed to down-regulate LYVE-1 marker (B) and had a reduced smooth muscle cell coverage (B, C). For each group, n = 2 to 4. Scale bars, 250 μm (A, B, C, top panel); 25 μm (C, bottom panel).