Abstract 1129: Obesity-related Elevations in Soluble P-selectin are Derived From Endothelium and Dependent on Expression of Leukocyte P-selectin Glycoprotein Ligand-1

Abstract

Background : Obesity is associated with proinflammatory changes and an increased risk for vascular disease complications. The tissue source and mechanism by which soluble P-selectin (sPsel) is generated in obesity are unclear. Methods and Results : Soluble p-selectin (sPsel) levels were measured in the circulation from lean wild type and obese leptin receptor deficient mice (LepR−/−) at 4 and 10 weeks of age. In wild-type mice body weight increases from 13+/−2 to 20+/−3 grams over this time period while the body weight increases from 15+/−2 to 38+/−5 grams in LepR−/− mice. At 4 weeks of age sPsel levels were 103+/−8mg/mL in wild-type mice vs. 138+/−9 ng/mL in LepR−/− mice, p=0.048. By 10 wks of age sPsel increased to 112 +/− 2 in wild-type mice and 182 +/− 9 in LepR−/− mice, p=0.00005. In order to determine if the obesity-induced rise in sPsel is regulated by leukocyte Psgl-1, bone marrow transplantation was performed from Psgl+/+ or Psgl−/− donors into irradiated LepR−/−recipients. At 4 weeks post-transplant, sPsel levels were 166 +/−6 ng/mL in LepR−/− mice receiving Psgl+/+ marrow and 45 +/− 4 ng/mL in LepR−/− mice receiving Psgl−/− marrow, p=0.0000004. In order to determine if the sPsel in LepR−/− mice originated from the endothelium versus platelets, we transplanted Psel−/− bone marrow into irradiated LepR−/−mice. At 4 weeks post transplant, sPsel levels were 153 +/−3 ng/mL in LepR−/− mice receiving Psel−/− bone marrow and were not significantly different from LepR−/− mice receiving Psel+/+ bone marrow (166 +/−6 ng/mL, p=0.06). By 10 weeks post transplant, mice gained even more weight and levels were 377+/−51 ng/mL in LepR−/− mice receiving Psel+/+ bone marrow and 370+/−73 ng/mL in LepR−/− mice receiving Psel−/− bone marrow, p=0.87. Conclusions : These data suggest that the increase in sPsel observed in obesity is primarily derived from the endothelium and that this process is regulated by leukocyte Psgl-1.