beta-VLDL hypercholesterolemia relative to LDL hypercholesterolemia is associated with higher levels of oxidized lipoproteins and a more rapid progression of coronary atherosclerosis in rabbits

The accumulation of the oxidized apolipoprotein, apoB-100, containing lipoproteins in the arterial wall and the progression of coronary atherosclerotic lesions in rabbits with beta-VLDL and LDL hypercholesterolemia was compared. In New Zealand White (NZW) rabbits on a 0.125% cholesterol diet, LDL cholesterol levels increased from 14 +/- 1 mg/dL (mean +/- SEM; n = 9) to 170 +/- 34 mg/dL (n = 10, P = .0002). On 0.5% cholesterol, LDL cholesterol levels were similar, but beta-VLDL cholesterol levels increased from 60 +/- 4 mg/dL (n = 10) to 550 +/- 75 mg/dL (n = 8; P < .0001). In Watanabe heritable hyperlipidemic (WHHL) rabbits, LDL cholesterol levels were 2.3-fold higher (n = 13; P < .0001) than in NZW rabbits on 0.5% cholesterol, whereas their beta-VLDL cholesterol levels were 3.7-fold lower (P < .0001), resulting in similar total cholesterol levels. At 2 months, mean intimal areas of lesions in the coronary arteries of NZW rabbits on 0.125% cholesterol were 0.13 +/- 0.045 mm2 (n = 4; mean +/- SEM) and were 5.8-fold, (n = 4; P = .016) and 2.0-fold (n = 6; P = NS versus 0.125% cholesterol and P = .014 versus 0.5% cholesterol) higher in NZW rabbits on 0.5% cholesterol and in WHHL rabbits, respectively. At 5 months, mean intimal areas were 0.47 +/- 0.088 mm2 (n = 6) in NZW rabbits on 0.125% cholesterol and were 4.5-fold (n = 4; P = .0001) and 2.0-fold (n = 7; P = .012 and P = .0019) higher in rabbits on 0.5% cholesterol and in WHHL rabbits, respectively. Levels of oxidized apoB-100 containing lipoproteins (both beta-VLDL and LDL) in the lesions correlated with mean intimal area (r = .88; n = 31; P < .0001) of those lesions and with the plasma levels of total beta-VLDL/LDL (r = .72; P < .0001). Levels of oxidized apoB-100 containing lipoproteins in the arterial wall correlate with progression of hypercholesterolemia-induced coronary atherosclerotic lesions. Plasma levels of beta-VLDL relative to similar increases in LDL result in a more pronounced accumulation of oxidized apoB-100 containing lipoproteins in the arterial wall and in the plasma and a more rapid progression of coronary atherosclerosis.     

Reduced progression of atherosclerosis in apolipoprotein E-deficient mice following consumption of red wine, or its polyphenols quercetin or catechin, is associated with reduced susceptibility of LDL to oxidation and aggregation

The effect of consuming red wine, or its major polyphenol constituents catechin or quercetin, on the development of atherosclerotic lesions, in relation to the susceptibility of plasma LDL to oxidation and to aggregation, was studied in atherosclerotic apolipoprotein E deficient (E degree) mice. Forty E degree mice at the age of 4 weeks were divided into four groups, 10 mice in each group, and were supplemented for up to 6 weeks in their drinking water with placebo (1.1% alcohol); catechin or quercetin (50 micrograms/d per mouse), or red wine (0.5 mL/d per mouse). Consumption of catechin, quercetin, or red wine had no effect on plasma LDL or HDL cholesterol levels. The atherosclerotic lesion area was smaller in the treated mice by 39%, 46%, and 48%, respectively, in comparison with E degree mice that were treated with placebo. In accordance with these findings, cellular uptake of LDL derived after catechin, quercetin, or red wine consumption was found to be reduced by 31%, 40%, and 52%, respectively. These results were associated with reduced susceptibility to oxidation (induced by different modes such as copper ions, free radical generator, or macrophages) of LDL isolated after red wine or quercetin and, to a lesser extent after catechin consumption, in comparison with LDL isolated from the placebo group. Similar results were obtained when LDL was preincubated in vitro with red wine or with the polyphenols prior to its oxidation. Even in the basal oxidative state (not induced oxidation), LDL isolated from E degree mice that consumed catechin, quercetin, or red wine for 2 weeks was found to be less oxidized in comparison with LDL isolated from E degree mice that received placebo, as evidenced by 39%, 48%, and 49% reduced content of LDL-associated lipid peroxides, respectively. This effect could be related to enhanced serum paraoxonase activity in the polyphenol-treated mice. LDL oxidation was previously shown to lead to its aggregation. The present study demonstrated that the susceptibility of LDL to aggregation was reduced in comparison with placebo-treated mice, by 63%, 48%, or 50% by catechin, quercetin, and red wine consumption, respectively, and this effect could be shown also in vitro. The inhibition of LDL oxidation by polyphenols could be related, at least in part, to a direct effect of the polyphenols on the LDL, since both quercetin and catechin were found to bind to the LDL particle via the formation of an ether bond. We thus conclude that dietary consumption by E degree mice of red wine or its polyphenolic flavonoids quercetin and, to a lesser extent, catechin leads to attenuation in the development of the atherosclerotic lesion, and this effect is associated with reduced susceptibility of their LDL to oxidation and aggregation.     

T cell recognition of hypervariable region-1 from hepatitis C virus envelope protein with multiple class II MHC molecules in mice and humans: preferential help for induction of antibodies to the hypervariable region

Hypervariable region-1 (HVR1) from the hepatitis C virus (HCV) envelope protein is thought to be a target for neutralizing Abs. To explore HVR1 recognition by helper T cells, and their role in Ab responses, we attempted to generate helper T cells specific for HVR1 in mice of three MHC types, and with PBMC from HCV-infected HLA-diverse humans. In both species, HVR1 was presented by >1 class II MHC molecule to CD4+ helper T cells and showed surprising interisolate cross-reactivity. The epitope for two DR4+ patients was mapped to a more conserved C-terminal sequence containing a DR4 binding motif, possibly accounting for cross-reactivity. Strikingly, Abs to patients' own HVR1 sequences were found only in patients with T cell responses to HVR1, even though all had Abs to envelope protein, suggesting that induction of Abs to HVR1 depends on helper T cells specific for a sequence proximal to the Ab epitope. Thus, helper T cells specific for HVR1 may be functionally important in inducing neutralizing Abs to HCV. These results may be the first example of "T-B reciprocity," in which proximity of a helper T cell epitope determines Ab epitope specificity, in a human disease setting.     

The inflammatory response to nonfatal Sindbis virus infection of the nervous system is more severe in SJL than in BALB/c mice and is associated with low levels of IL-4 mRNA and high levels of IL-10-producing CD4+ T cells

SJL mice are susceptible to inflammatory autoimmune diseases of the central nervous system (CNS), while BALB/c mice are relatively resistant. To understand differences in immune responses that may contribute to autoimmune neurologic disease, we compared the responses of SJL and BALB/c mice to infection with Sindbis virus, a virus that causes acute nonfatal encephalomyelitis in both strains of mice. Clearance of virus was similar, but SJL mice developed a more intense inflammatory response in the brain and spinal cord and inflammation persisted for several weeks. Analysis of lymphocytes isolated from brains early after infection showed an absence of NK cells in SJL mice, while both strains of mice showed CD4+ and CD8+ T cells. During the second week after infection, CD4+ T cells increased in SJL mice and the proportion of CD8+ T cells decreased, while the opposite pattern was seen in BALB/c mice. Expression of IL-10 mRNA was higher and IL-4 mRNA was lower in the brains of infected SJL than in BALB/c mice, while expression of the mRNAs of IL-6, IL-1beta, TNFalpha, and the Th1 cytokines IL-2, IL-12, and IFN-gamma was similar. Lymphocytes isolated from the CNS of SJL mice produced large amounts of IL-10. CNS lymphocytes from both strains of mice produced IFN-gamma in response to stimulation with Sindbis virus, but not in response to myelin basic protein. These data suggest that IL-10-producing CD4+ T cells are differentially recruited to or regulated within the CNS of SJL mice compared with BALB/c mice infected with Sindbis virus, a characteristic that may be related to low levels of IL-4, and is likely to be involved in susceptibility of SJL mice to CNS inflammatory diseases.