Plasma kinetics of an LDL-like non-protein nanoemulsion and transfer of lipids to high-density lipoprotein (HDL) in patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a systemic inflammatory disease associated with cardiovascular risk, but with normal plasma lipids. OBJECTIVE: The aim was to investigate low-density lipoprotein (LDL) and high-density lipoprotein (HDL) metabolism in RA patients using radioactive nanoemulsions resembling an LDL lipid structure (LDE) as metabolic probes. METHODS: Thirty patients with RA, 16 in remission and 14 in high activity, and 30 healthy controls were studied. LDE labeled with (14)C-cholesteryl ester ((14)C-CE) and (3)H-unesterified cholesterol ((3)H-UC) was intravenously injected followed by 24-hour plasma sampling. Fractional clearance rates (FCR, h(-1)) were calculated by compartmental analysis. Lipid transfers to HDL were assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids; % lipids transferred to HDL were quantified after chemical precipitation. RESULTS: LDL cholesterol, triglycerides, unesterified cholesterol, and oxidized LDL were equal in RA and controls, and HDL cholesterol was even higher in RA. Compared with controls, apolipoprotein B was lower, apolipoprotein A1 was equal, and apolipoprotein E was higher in RA. Decay curves of LDE labels were faster in RA patients than in controls ((14)C-CE: 0.072 ± 0.066 and 0.038 ± 0.027, P = .0115; (3)H-UC: 0.066 ± 0.042 and 0.035 ± 0.039; P < .0044). FCRs were equal in 2 RA subgroups. Transfer of UC, triglycerides, and phospholipids to HDL was equal between RA and controls, but CE transfer was lower in RA. HDL size was smaller in RA patients than in controls (8.5 ± 0.5 nm; 9.2 ± 0.8 nm, P < .0001). CONCLUSION: RA patients were more efficient in removing atherogenic LDL from plasma, as indicated by higher CE and UC FCR, with in lower apolipoprotein B. This was unexpected because of the higher cardiovascular risk in RA.

Plasma kinetics of chylomicron-like emulsion and lipid transfers to high-density lipoprotein (HDL) in lacto-ovo vegetarian and in omnivorous subjects.

PURPOSE: Previously, it was showed that vegan diet improves the metabolism of triglyceride-rich lipoproteins by increasing the plasma clearance of atherogenic remnants. The aim of the current study was to investigate this metabolism in lacto-ovo vegetarians whose diet is less strict, allowing the ingestion of eggs and milk. Transfer of lipids to HDL, an important step in HDL metabolism, was tested in vitro. METHODS: Eighteen lacto-ovo vegetarians and 29 omnivorous subjects, all eutrophic and normolipidemic, were intravenously injected with triglyceride-rich emulsions labeled with ¹4C-cholesterol oleate and ³H-triolein. Fractional clearance rates (FCR, in min⁻¹) were calculated from samples collected during 60 min. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids. RESULTS: LDL cholesterol was lower in vegetarians than in omnivores (2.1 ± 0.8 and 2.7 ± 0.7 mmol/L, respectively, p < 0.05), but HDL cholesterol and triglycerides were equal. Cholesteryl ester FCR was greater in vegetarians than in omnivores (0.016 ± 0.012, 0.003 ± 0.003, p < 0.01), whereas triglyceride FCR was equal. Cholesteryl ester transfer to HDL was lower in vegetarians than in omnivores (2.7 ± 0.6, 3.5 ± 1.5 %, p < 0.05), but free cholesterol, triglyceride and phospholipid transfers and HDL size were equal. CONCLUSION: Similarly to vegans, lacto-ovo vegetarian diet increases remnant removal, as indicated by cholesteryl oleate FCR, which may favor atherosclerosis prevention, and has the ability to change lipid transfer to HDL.