Hypothesis: increasing dietary cholesterol in humans will increase visceral, but not subcutaneous adipocyte size, free cholesterol content, and inflammatory gene expression. Visceral and abdominal subcutaneous adipose tissue biopsies will be obtained from non-obese subjects undergoing elective abdominal surgery at Wake Forest Baptist Medical Center after 3 weeks of zero (control) or 1g dietary cholesterol supplementation. Blood samples will also be taken before and after 3 weeks of dietary supplementation (0 vs. 1g dietary cholesterol) to measure plasma lipids levels, and ex vivo monocyte chemotaxis. Blood will also be used to isolate CD14+ monocytes for RNA extraction and storage for future transcriptome studies. Measurements of adipocyte size, free cholesterol content, and inflammatory gene and protein expression in the adipose tissue biopsies to test the hypothesis. Adipocytes and the stromal vascular fraction will be isolated and evaluated for CD14+ macrophages for RNA extraction and storage for future transcriptome analysis.
A Wake Forest School of Medicine Clinical Research Unit-based pilot study will be conducted in which subjects scheduled to undergo elective intra-abdominal surgery at Wake Forest Baptist Medical Center (i.e., cholecystectomy, Nissen fundoplication, hernia repair, etc.) will be recruited. Subjects will be randomly and blindly assigned to receive daily treats (cookie, brownie, or muffin) containing either no added cholesterol (control) or 1g of cholesterol/day (\~0.4 mg/Kcal cholesterol) for 3 weeks prior to surgery. Three weeks for the length of cholesterol supplementation has been chosen because this is within the duration of human egg-consumption studies in which significant elevations in plasma LDL concentrations occurred. A blood sample will be taken from each participant at baseline before starting the supplementation period and after 3 weeks of 0 or 1g/day cholesterol supplementation, at the time of scheduled surgery. The blood samples will be used for measurement of lipid profile, ex vivo monocyte chemotaxis, and for monocyte RNA isolation. During surgery, abdominal wall subcutaneous adipose tissue and mesenteric (visceral) adipose tissue samples will be obtained. Aliquots of adipose tissue will be fixed overnight for histology and measurement of adipocyte size distribution and CD68 immunostaining, flash frozen and stored for cholesterol quantification by gas liquid chromatography, extracted to isolate RNA and protein for quantitative real time PCR and immunoblotting of inflammatory gene and protein expression, and collagenase digested to isolate adipocytes and stromal vascular cell fraction macrophages which will be used to extract and store RNA for future transcriptome analyses.
Study Type
Participants assigned to the added cholesterol group will receive snacks containing added cholesterol (1g/day) for 3 weeks prior to surgery.
Participants assigned to the no added cholesterol group will receive snacks containing no added cholesterol for 3 weeks prior to surgery.
Wake Forest Baptist Medical Center
Winston-Salem, North Carolina, United States
Plasma total
Plasma will be used to measure plasma total
Time frame: up to 6 weeks after surgery
Adipocyte size
Adipocyte size will be evaluated by histology by microscopic examination and morphometry.
Time frame: within 6 weeks after surgery
Lipoprotein cholesterol levels
Plasma will be used to measure lipoprotein cholesterol levels.
Time frame: up to 6 weeks after surgery
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INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE