To confirm the safety and efficacy of a low-calorie mayonnaise supplemented with phytosterol esters (PEM) at a daily consumption dose of 884 mg given for 12 weeks with the goal of lowering serum low-density lipoprotein (LDL) cholesterol levels, we conducted a double-blind comparative study in healthy adults with marginally high serum levels of LDL cholesterol and total cholesterol using a mayonnaise without phytosterol esters supplementation (CM) as the control food. Serum LDL cholesterol levels decreased significantly in the PEM group as compared with the CM group during the 12-week intervention period (136.3 ± 16.4 vs. 145.0 ± 19.3 mg/dL at Week 8 (P < 0.05) and 135.0 ± 17.4 mg/dL vs. 144.9 ± 17.5 mg/dL at Week 12; P < 0.05). No observable adverse effects were observed due to the ingestion of PEM in this study. The safety of PEM was again confirmed by an additional clinical study in which healthy adult subjects ingested a 3-fold greater amount of PEM (2,652 mg of phytosterol esters as a daily dose) for 4 weeks. Thus, we concluded that PEM is effective in lowing serum levels of LDL cholesterol and is safe and well tolerated without any clinical problems.

LR11, also known as SorLA or SORL1, is a type-I membrane protein from which a large extracellular part, soluble LR11 (sLR11), is released by proteolytic shedding on cleavage with a disintegrin and metalloproteinase 17 (ADAM17). A shedding mechanism is presumed to have a key role in the functions of LR11, but the evidence for this has not yet been demonstrated. Tetraspanin CD9 has been recently shown to regulate the ADAM17-mediated shedding of tumor necrosis factor-alpha and intercellular adhesion molecule-1 on the cell surface. Here, we investigated the role of CD9 on the shedding of LR11 in leukocytes. LR11 was not expressed in THP-1 monocytes, but it was expressed and released in phorbol 12-myristate 13-acetate (PMA)-induced THP-1 macrophages (PMA/THP-1). Confocal microscopy showed colocalization of LR11 and CD9 proteins on the cell surface of PMA/THP-1. Ectopic neo-expression of CD9 in CCRF-SB cells, which are LR11-positive and CD9-negative, reduced the amount of sLR11 released from the cells. In contrast, incubation of LR11-transfected THP-1 cells with neutralizing anti-CD9 monoclonal antibodies increased the amount of sLR11 released from the cells. Likewise, the PMA-stimulated release of sLR11 increased in THP-1 cells transfected with CD9-targeted shRNAs, which was negated by treatment with the metalloproteinase inhibitor GM6001. These results suggest that the tetraspanin CD9 modulates the ADAM17-mediated shedding of LR11 in various leukemia cell lines and that the association between LR11 and CD9 on the cell surface has an important role in the ADAM17-mediated shedding mechanism.
ADAM Proteins/*metabolism ; Antigens, CD9/genetics/*metabolism ; Cell Line, Tumor ; Humans ; LDL-Receptor Related Proteins/genetics/*metabolism ; Leukocytes/*metabolism ; Macrophages/metabolism ; Membrane Transport Proteins/genetics/*metabolism ; Proteolysis