Effects of oxidized low-density lipoprotein on leukocyte-endothelial interactions in the rat mesenteric microcirculation during pregnancy

Objective: The accumulation of evidence implicates oxidized lipoproteins in atherosclerosis. Treatment of endothelial cells with these lipoproteins stimulates monocyte binding and the production of chemotactic factors that contribute to inflammation and endothelial injury and dysfunction. In preeclampsia, circulating low-density lipoprotein particles, which are susceptible to oxidation, are increased. We studied leukocyte-endothelial interactions that were related to oxidized lipoproteins in pregnant rats. Study design: We examined oxidized low-density lipoprotein-induced leukocyte behavior and uptake of fluorescent-labeled oxidized low-density lipoprotein in rat mesenteric venules during pregnancy, with the use of intravital microscopy with a video imager. Results: The administration of oxidized low-density lipoprotein significantly reduced rolling velocities of leukocytes in venules and increased the numbers of leukocytes that adhered to endothelium in both nonpregnant and pregnant rats. These interactions were attenuated in pregnancy, when uptake of labeled oxidized low-density lipoprotein into leukocytes and endothelial cells also was decreased. Conclusion: Pregnancy may be associated with antioxidant effects. (C) 2004 Elsevier Inc. All rights reserved.