Adventitial lymphatics and atherosclerosis.

Lymphatic vessels are important in reversecholesterol transport and play a crucial rolein regression of atherosclerotic plaque inexperimental animal models. Therefore, weattempted to analyze adventitial microcirculationincluding lymphatic vessels andadventitial macrophages in large humanarteries in various stages of atherosclerosis.Eighty-one arterial segments of large arteries(iliac arteries and abdominal aortas) wereobtained from deceased organ donors.Lymphatic vessels were identified using anti-LYVE-1 and anti-D2-40/ podoplaninimmunohistochemical staining. Adventitialblood vessels and macrophages were visualizedusing anti-CD-31 and anti-CD-68. Intimalthickness was measured under 100xmagnification with an Olympus BX 41 lightmicroscope using the visual mode analySIS3.2 software. Lymphatic vessels were countedin each cross section of the examined arteries,and adventitial blood vessels (CD31+) werecounted using the “hot spot” method.Statistical analysis was performed withStatistica 9.1 PL software (StatSoft, Cracow,Poland). Mann-Whitney, F-Cox, Chi-square,and Spearman’s correlation tests wereperformed and the differences were consideredsignificant at p<0.05. Lymphatic and bloodvessels in the adventitia of examined arterieswere identified and quantified. Significantpositive correlations were found between thenumber of adventitial lymphatics (LYVE-1 +)and intimal thickness (r=0.37; p<0.05) as wellas with age of the subjects (r=0.3; p<0.05).Thus, lymphatic vessels are present in theadventitia of large arteries in humans and thenumber of adventitial lymphatic vesselsincreases with progression of atherosclerosisas assessed by intimal thickness.