title: Chylomicrons produced by Caco-2 cells contained ApoB-48 with diameter of 80-200 nm.
abstract: The small intestine generally transports dietary fats to circulation in triglyceride (TG)-rich lipoproteins. The two main intestinal lipoproteins are chylomicron (CM) and very low-density lipoprotein (VLDL). Unfortunately, studies on the CM biogenesis and intestinal transport of dietary fats have been hampered by the lack of an adequate in vitro model. In this study, we investigated the possible factors that might increase the efficiency of CM production by Caco-2 cells. We utilized sequential NaCl gradient ultracentrifugation to isolate the CMs that were secreted by the Caco-2 cells. To confirm the successful isolation of the CMs, we performed Fat Red 7B staining, TG reading, apolipoprotein B (ApoB) measurement, and transmission electron microcopy (TEM) analysis. We then tested the effects of cell differentiation, oleic acid, mono-olein, egg lecithin, incubation time, and collagen matrix on CM secretion. We found that cell differentiation, oleic acid, and lecithin were critical for CM secretion. Using the Transwell system, we further confirmed that the CMs produced by our Caco-2 cells contained significant amount of TGs and ApoB-48 such that they could be detected without the use of isotope labeling. In conclusion, when fully differentiated Caco-2 were challenged with oleic acid, lecithin, and sodium taurocholate, 21% of their total number of lipoproteins were CMs with the diameter of 80-200 nm.
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, California Northstate University, Elk Grove, California.
authors.forename: Andromeda M
authors.initials: AM
authors.lastname: Nauli
authors.affiliation: Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, Tennessee.
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee.
authors.forename: Judy D
authors.initials: JD
authors.lastname: Whittimore
authors.affiliation: Department of Internal Medicine, Division of Allergy and Clinical Immunology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee.
authors.forename: Seif
authors.initials: S
authors.lastname: Atyia
authors.affiliation: Department of Internal Medicine, Division of Allergy and Clinical Immunology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee.
authors.forename: Guha
authors.initials: G
authors.lastname: Krishnaswamy
authors.affiliation: Department of Pharmacology, College of Pharmacy, and Medicine, The University of Toledo, Toledo, Ohio.
authors.forename: Surya M
authors.initials: SM
authors.lastname: Nauli
keywords: Absorption; digestion; enterocytes; gastrointestinal; lipid