Reduced effect on apoptosis of 4-hydroxyhexenal and oxidized LDL enriched with n-3 fatty acids from postmenopausal women.

BACKGROUND: Oxidized low-density lipoprotein (oxLDL) promotes apoptosis in atherosclerotic plaques in the vascular wall, a process mediated through its oxidized lipids. 4-Hydroxynonenal (HNE) and 4-hydroxyhexenal (HHE), derived from oxidation of n-6 and n-3 fatty acids, respectively, are among the major oxidized products in oxLDL. HYPOTHESIS: This study hypothesized that eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA)-rich versus linoleic acid-rich oxLDL obtained from postmenopausal women and HNE versus HHE differentially influence apoptosis in U937 cells. EXPERIMENTAL DESIGN: Thirty healthy postmenopausal women were supplemented with 14 g/day safflower oil (SO), 7 g/day of both fish oil and SO (low dose LFO) or 14 g/day fish oil (high dose HFO) for 5 weeks. Low-density lipoprotein, obtained after supplementation, was oxidized with 5 microM CuSO(4) at 37 degrees C for 6 h. The concentration of cholesteryl ester hydroperoxides (CEOOH) and conjugated dienes was measured in the oxidized LDL (oxLDL). U937 cells were incubated with the oxLDL, 10 microM of HHE, 7 muM of HHE plus 3 microM of HNE, 5 microM of both HHE and HNE or 10 microM of HNE and the extent of apoptosis measured three ways. RESULTS: The concentration of CEOOH and conjugated dienes in oxLDL did not differ among the three treatment groups. The percent of apoptotic cells was approximately 40% lower when incubated with oxLDL obtained from the HFO-supplemented group than the SO-supplemented group measured by both the Annexin V and the DNA fragmentation assays (P = .04 and .004, respectively). Apoptosis of U937 cells was significantly lower in cells incubated with 10 microM of HHE, and mixtures of HHE and HNE than the 10 microM HNE when measured by the Annexin V, DNA fragmentation and 4,6-diamidino-2-phenylindole (DAPI) staining. CONCLUSIONS: These data suggest that the cardioprotective properties of n-3 fatty acids may derive in part from their less reactive oxidized lipid metabolites.

Dietary fish oil decreases C-reactive protein, interleukin-6, and triacylglycerol to HDL-cholesterol ratio in postmenopausal women on HRT.

BACKGROUND: Atherogenesis is a complex process involving both a low-grade inflammation and a disturbed lipid profile. Although dietary fish and fish oil improve the latter of these two risk factors, their impact on the former is less clear. OBJECTIVE: This study addressed the effect of supplementation with fish oil in doses achievable with diet on serum C-reactive protein (CRP), interleukin-6 (IL-6), and the lipid profile. METHODS AND RESULTS: Thirty healthy subjects taking HRT were randomly divided into three groups and supplemented for five weeks with 14 g/day safflower oil (SO), 7 g/day of both safflower oil and fish oil (LFO), or 14 g/day fish oil (HFO). Measurements included serum high-sensitivity CRP, IL-6 in plasma and in cell culture supernatant collected from 24-hr lipopolysaccharide (LPS)-stimulated whole blood, and lipid profile markers. CRP and IL-6 were adjusted for body mass index (BMI). Fish oil supplementation significantly decreased CRP and IL-6 compared to SO, with a greater effect in the LFO than HFO groups. Plasma triacylglycerol (TG) and the TG/HDL-C ratio were significantly lower in the HFO compared to the SO group. CONCLUSIONS: These results suggest that dietary fish oil may decrease the risk for cardiovascular disease through the modulation of both plasma lipids and inflammatory markers in healthy postmenopausal women.

Enrichment of LDL with EPA and DHA decreased oxidized LDL-induced apoptosis in U937 cells.

Oxidized LDL (oxLDL) may contribute to the accumulation of apoptotic cells in atherosclerotic plaques. Although it is well established in monophasic chemical systems that the highly unsaturated EPA and DHA will oxidize more readily than FA that contain fewer double bonds, our previous studies showed that enrichment of LDL, which has discrete polar and nonpolar phases, with these FA did not increase oxidation. The objective of this study was to compare the extent of apoptosis induced by EPA/DHA-rich oxLDL to that induced by EPA/DHA-non-rich oxLDL in U937 cells. LDL was obtained from one healthy subject three times before and after supplementation for 5 wk with 15 g/d of fish oil (FO), an amount easily obtainable from a diet that contains fatty fish. After supplementation, an EPA/DHA-rich LDL was obtained. Oxidative susceptibility of LDL, as determined by measuring the formation of conjugated dienes and the accumulation of cholesteryl ester hydroperoxides, was not higher in EPA/DHA-rich LDL. The oxLDL-induced cell apoptosis was detected by the activation of caspase-3, the translocation of PS to the outer surface of the plasma membrane using the Annexin V-fluorescein isothiocyanate binding assay, and the presence of chromatin condensation and nuclear fragmentation using the 4,6-diamidino-2-phenylindole staining assay. All three measures showed that after FO supplementation, EPA/DHA-rich oxLDL-induced cell apoptosis decreased. The decrease was not related to the concentration of lipid hydroperoxides. This study suggests that a possible protective effect of EPA/DHA-rich diets on atherosclerosis may be through lessening cell apoptosis in the arterial wall.