© 2000 American Heart Association, Inc.
Integrative Physiology |
Maternal Hypercholesterolemia Enhances Atherogenesis in Normocholesterolemic Rabbits, Which Is Inhibited by Antioxidant or Lipid-Lowering Intervention During Pregnancy
An Experimental Model of Atherogenic Mechanisms in Human Fetuses
From the Department of Medicine (C.N., J.L.W., F.C., W.P.), University of California San Diego, La Jolla, Calif, and Department of Medicine (C.N., F.d.N.), Federico II University of Naples, Naples, Italy.
Correspondence to Wulf Palinski, MD, and Claudio Napoli, MD, Department of Medicine, 0682, University of California, San Diego, 9500 Gilman Dr, MTF 110, La Jolla, CA 92093. E-mail wpalinski{at}ucsd.edu/cnapoli@ucsd.edu
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Abstract |
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Abstract—Maternal hypercholesterolemia during pregnancy is associated with a marked increase in aortic fatty streak formation in human fetuses and faster progression of atherosclerosis during normocholesterolemic childhood. However, the mechanisms responsible are unknown, and the contribution of genetic differences is difficult to assess in humans. The goal of this study was to determine whether maternal hypercholesterolemia per se may cause enhanced fatty streak formation in offspring and whether interventions during pregnancy can reduce it. During pregnancy, 1 group of New Zealand White rabbits was fed control chow and 8 groups were fed hypercholesterolemic diets Chol 1 (yielding plasma cholesterol of 153 mg/dL) or Chol 2 (yielding 359 mg/dL) without or with cholestyramine, vitamin E, or both. Offspring (n=15 to 25 per group) were killed at birth. Maternal hypercholesterolemia enhanced mean lesion size in the aorta of their offspring at birth from 44±18x103 µm2 per section in controls to 85±26x103 in Chol 1 and 156±49x103 in Chol 2 groups (P<0.0001 for both). Cholestyramine or vitamin E treatment of mothers significantly reduced atherosclerosis at birth by up to 39% compared with controls on the same diet. Oxidized fatty acids and malondialdehyde in aortic atherosclerotic lesions and plasma were similarly affected by diets and treatment as atherosclerosis. Our results establish the causal role of hypercholesterolemia and peroxidation in fetal atherogenesis and demonstrate that both lipid-lowering and antioxidant interventions during pregnancy can reduce it. If it can be established that interventions in mothers also affect progression of lesions after birth, this may indicate a novel approach for the prevention of atherosclerosis.
Key Words: atherosclerosis • cholestyramine • vitamin E • oxidation • prevention
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The atherogenic process in humans already begins in fetuses, and pathogenic events occurring during fetal development profoundly influence the progression of atherosclerosis later in life.1 2 3 4 5 In the past, atherogenesis was thought to begin during late childhood, even though fatty streaks had been observed in younger children.6 7 However, morphometric analysis of cross sections through the aorta of premature human fetuses showed that fatty streaks, the earliest stages of atherosclerotic lesions, already occur in fetal aortas and that their distribution reflects that of more advanced lesions in adults.1 Remarkably, the number and size of fatty streaks were much greater in fetuses of hypercholesterolemic mothers, including those in whom hypercholesterolemia was limited to pregnancy.
Although animal experiments and human studies had indicated
that the placenta is relatively impermeable to large,
cholesterol-carrying
lipoproteins,8 9
hypercholesterolemia-induced events seemed to be a likely cause of
lesion formation in fetuses. Fetal plasma cholesterol levels correlated
significantly with maternal ones in fetuses younger than 6 months (but
not thereafter). This indicated that maternal hypercholesterolemia
itself contributes to enhanced fetal atherogenesis. However, we also
observed a striking inverse correlation between fetal age and fetal
plasma cholesterol, with very high levels in all younger fetuses (see
Reference 11 , Figure 3B
). Thus, it was conceivable that fetal lesions
would regress when cholesterol levels decrease toward the end of
pregnancy or under normocholesterolemic conditions after
birth.
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The Fate of Early Lesions in Children (FELIC) study, designed to investigate the potential influence of fetal lesion formation on later atherogenesis, showed that fetal fatty streaks regress only partially (and not uniformly throughout the aorta) and that maternal hypercholesterolemia was associated with accelerated progression of atherosclerosis during childhood and adolescence.3 In this study, normocholesterolemic children who died mainly of trauma were divided into two groups, depending on whether their mother had been normocholesterolemic or hypercholesterolemic during pregnancy. In each group, atherosclerosis in the aortic arch and abdominal aorta increased linearly with age, but progression of atherosclerosis was much faster in children of hypercholesterolemic mothers. All children had normal lipid profiles, and multiple regression analysis indicated that none of 13 risk factors determined in children and their mothers could account for this difference. We hypothesized that fetal lesion formation and enhanced susceptibility to atherosclerosis later in life were induced, at least in part, by maternal hypercholesterolemia and ensuing enhanced lipid oxidation.10 11 A corollary of this hypothesis is that lipid-lowering or antioxidant interventions in mothers during pregnancy may constitute a new approach to reducing atherosclerosis.3 4 5 However, direct experimental evidence for this hypothesis is still outstanding, and differences in the genetic background of normocholesterolemic and hypercholesterolemic mothers may also provide an explanation for both the fetal onset and the enhanced progression of the disease.
We now provide evidence for the causal role of maternal hypercholesterolemia in fetal atherogenesis by showing that in a genetically more homogeneous animal model, the New Zealand White (NZW) rabbit, diet-induced maternal hypercholesterolemia during pregnancy is sufficient to markedly enhance lesions in their offspring at birth. We also demonstrate the involvement of lipid oxidation and establish, in principle, that lipid-lowering and antioxidant interventions during pregnancy are effective in reducing the fetal onset of atherogenesis.
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Materials and Methods |
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Rabbits
Seventy-seven female NZW rabbits (Harlan-Nossan), age 4.6±1.1 months, were divided into 9 groups (n=8 to 9) (Table
).
One group (control) was fed regular chow (4% fat, 18% protein, 60%
carbohydrate, and 4% fibers). Four groups each were fed
cholesterol-enriched diets Chol 1 or Chol 2 (Teklad adjusted calories
diet; 9% fat, 19% protein, 55% carbohydrate, and 4% fibers, to
which cholesterol dissolved in ether was added) to achieve total plasma
cholesterol (TC) levels of about 150 and 350 mg/dL, respectively (in
the absence of lipid-lowering drugs). Diets were started 2 weeks before
mating and continued until 2 weeks postpartum. On the basis of
preliminary experiments, the cholesterol content of the diet given to
the Chol 1 group ranged from 0.132% to 0.156% (depending on each
animal’s initial TC level), whereas animals of the Chol 2 group
received 0.168% to 0.221% cholesterol. One group (Chol 1) received
only the diet. A second group (Chol 1+CH) received Chol 1 diet plus a
dose of cholestyramine (1% to 1.4%) (SIGMA) that was individually
adjusted to match the average TC level of the chow-fed rabbits (
80
mg/dL). A third group (Chol 1+vitamin E) was fed Chol 1 plus 100 IU/d
of vitamin E (
-tocopherol; SIGMA), and a fourth group (Chol
1+CH+vitamin E) was fed the diet together with both cholestyramine and
vitamin E. The four groups fed Chol 2 received the same supplements,
except that the dose of cholestyramine (1.8% to 3%) was adjusted to
achieve the average TC level of the Chol l group. Cholestyramine was
chosen as hypocholesterolemic drug because of the virtual absence of
side effects during
pregnancy.5 Vitamin E
treatment did not result in any adverse effects in mothers or their
offspring. The
Table
provides a summary of experimental conditions. After 2 weeks on the
diet, females were bred with untreated males. TC levels were determined
at week 2 and 3 of pregnancy by standard enzymatic
method.1 About half
of each litter were killed at birth (n=19 to 25 per group), and the
remaining littermates were killed at age 4 months, after about 3 months
on regular chow (n=15 to 18). Experimental groups contained roughly
equal numbers of males and females, and data for both genders were
analyzed together, because previous studies in human fetuses and
children had not indicated significant differences between
sexes.1 3
All experiments were carried out under approved institutional animal
protocols.
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Tissue Preparation and
Quantification of Atherosclerosis
Lesion sizes were determined by computer-assisted
image analysis of 30 equidistant frozen oil red O–stained sections
each from the aortic arch, thoracic, and abdominal aorta. Additional
sections were pooled as lesion or nonlesion tissue. The rationale and
methods for tissue preparation and analysis were identical to those
previously used for arteries of human
fetuses.1 2
Results are reported as cumulative lesion area per section (ie, the
mean area of all lesions in each of the 90 aortic
sections).
Immunocytochemistry
Additional sections (n=10) from each aortic segment
were formaldehyde fixed and immunostained with 1:500 dilutions of NA59,
a murine monoclonal antibody (MAb) against oxidation-specific
4-hydroxynonenal-lysine
epitopes12 ;
EO6, a natural MAb cloned from atherosclerotic apolipoprotein
E–deficient mice that recognizes oxidized phospholipid
epitopes13 14 ;
NP1539, a MAb to human apolipoprotein B that also recognizes rabbit LDL
(Boehringer Mannheim); and RAM11, a MAb against rabbit monocyte and
macrophages (DAKO). Epitopes recognized by the primary antibody were
detected by an avidin-biotin-peroxidase
method.1 3
Peroxidative End
Products
Fatty acids (FAs) were isolated from plasma or aortic
homogenates, as
described.15
Concentrations of 10-OH oleic acid, 12-OH linoleic acid, and 10-OH
arachidonic acid were determined by a combination of gas chromatography
and mass
spectrometry.15
Results are presented as absolute amount of individual oxidized
FAs.15 The
concentration of oxidized FAs in atherosclerotic lesions of each rabbit
was determined by comparison of pooled normal and lesion tissue. The
concentration of oxidized FA in plasma of different dietary groups was
compared after 
-differentiation of FA
spectra.16 Plasma
malondialdehyde (MDA) content was measured as thiobarbituric
acid–reactive
substances.12 In
maternal plasma, these parameters were measured at the 2nd and 3rd week
of pregnancy and in their offspring, plasma and aortic measurements
were performed when they were killed.
Statistical Analysis
Data were analyzed by ANOVA and comparisons between
groups by unpaired Student’s t test. Fifteen
comparisons were done for each parameter: control versus Chol 1 versus
Chol 2 and 6 comparisons each between groups on the same diet. All
significances were Bonferroni-corrected. Correlations were tested by
linear regression analysis. Results are presented as
mean±SEM.
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Results |
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Mothers
Maternal plasma cholesterol levels are shown in Figure 1
. As expected, Chol 1 and Chol 2 diets raised the
average maternal TC levels during pregnancy to 157 and 359 mg/dL,
respectively, compared with 58 mg/dL in controls. Cholestyramine, but
not vitamin E treatment, significantly reduced TC in both groups to 77
and 171 mg/dL, respectively (P<0.001). Plasma
triglycerides were significantly raised only in the Chol 2 group
compared with the control group (132.8±41.3 versus 48.5±6.2 mg/dL;
P<0.05); triglycerides in the Chol 1 group were
72.0±26.4 mg/dL (P=0.083). No significant differences
were observed in all other plasma analyses. None of the diets
significantly affected maternal body weights during pregnancy.
Peroxidative compounds are shown in the
Table
.
Groups with increased plasma cholesterol consistently showed
significant increases in plasma MDA. When data for all groups not
receiving vitamin E were pooled, maternal plasma cholesterol showed a
significant correlation with plasma MDA (r=0.755,
P<0.0001). Vitamin E reduced plasma MDA levels to
normal levels in both diet groups, even though the TC level of the Chol
2+vitamin E group was much higher than that of the control group.
Although cholestyramine normalized TC level in rabbits fed Chol 1 and
markedly reduced it in rabbits fed Chol 2, it only achieved a marginal
decrease in MDA level in the latter. In analogy, the increase in
principal oxidized FAs associated with either hypercholesterolemic diet
(eg, 10-OH oleic acid and 12-OH linoleic acid) was completely prevented
by vitamin E but not cholestyramine. Absolute 10-OH arachidonic acid
levels were low but generally behaved similarly (data not shown).
Combinations of cholestyramine and vitamin E yielded lower oxidized FA
levels than vitamin E only groups, but the differences generally were
not significant.
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Effect of Hypercholesterolemia and
Interventions During Pregnancy on Atherosclerosis in Offspring at
Birth
Morphometric assessment of aortic cross sections
revealed microscopic fatty streaks even in the control group
(Figure 2). Maternal hypercholesterolemia during pregnancy
increased lesion sizes by 94% in the Chol 1 group
(P<0.0001). Treatment with cholestyramine decreased
atherosclerosis by 22% (not significant [NS]), but lesion sizes
remained greater than in the control group, even though maternal plasma
cholesterol levels of both groups were similar
(Figure 1). Offspring of mothers with more marked
hypercholesterolemia (Chol 2 group) showed a 253% increase in lesions
(P<0.0001) and a powerful antiatherogenic effect of
cholestyramine (-30%; P<0.01). Again, lesion sizes
in the Chol 2+cholestyramine group significantly exceeded those in the
Chol 1 group, which had similar maternal TC levels
(Figure 1). Treatment of mothers with vitamin E, which did
not lower their cholesterol, significantly reduced atherosclerosis in
the Chol 2 group (-39%; P<0.0005) but missed
significance in the Chol 1 group (-19%). Combination of
cholestyramine with vitamin E resulted in modest, not significant
additional reduction of atherogenesis.
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Effect on Plasma
Cholesterol and Lipid Oxidation in Offspring at Birth
All groups examined at birth had normal TC levels
(48±2.3 to 58±1.5 mg/dL; NS)
(Figure 3A), indicating that at the end of a regular
pregnancy, the placenta is impermeable to maternal LDL and VLDL. Plasma
triglycerides were also normal in all groups (32.8±6.3 to 42.1±8.5
mg/dL; NS). However, plasma concentrations of peroxidative end
products, such as 10-OH oleic acid
(Figure 3B), 12-OH linoleic acid
(Figure 3C), and 10-OH arachidonic acid (data not shown), as
well as plasma MDA levels
(Figure 3D), were significantly increased in the offspring of
mothers fed hypercholesterolemic diets, particularly in those fed Chol
2. Treatment of either diet group with vitamin E significantly reduced
peroxidation
(Figures 3B through 3D), whereas cholestyramine caused only a
much smaller reduction of oxidation.
Effect on Aortic Lipid
Oxidation and Lesion Composition at Birth
Concentrations of oxidized oleic and linoleic acids
(Figures 4A and 4B) and arachidonic acid (not shown) in early
atherosclerotic lesions of the aorta were markedly elevated in rabbits
of the Chol 1 and Chol 2 groups. Maternal treatment with vitamin E was
associated with a highly significant reduction of oxidized FAs in the
Chol 2 group. A reduction was also seen in the Chol 1 group, but this
was significant only for linoleic acid. As in plasma, offspring of
cholestyramine-treated mothers also showed significant reductions in
oxidized FAs in early aortic lesions, and no additional significant
reduction was achieved by combination therapy. Immunocytochemical
detection of typical components of early lesions, ie,
oxidation-specific epitopes such as 4-hydroxynonenal-lysines detected
by NA59
(Figure 4C) and oxidized phospholipid epitopes detected by
EO6
(Figure 4D), as well as LDL (apolipoprotein B)
(Figure 4E), and macrophages and foam cells
(Figure 4F), showed similar protective effects of antioxidant
and lipid-lowering interventions during pregnancy. As expected, aortic
concentrations of nonoxidized linoleic, oleic, and arachidonic acids
were also increased by hypercholesterolemic diets (data not
shown).
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Correlation Between Maternal Plasma
Cholesterol Levels and Atherosclerosis at Birth
The above results suggested that the marked increase in
atherosclerosis in the Chol 1 and Chol 2 groups was a direct result of
maternal hypercholesterolemia. Indeed, linear regression analysis of
all data indicated a correlation between the average maternal plasma
cholesterol level during pregnancy and the size of lesions in their
offspring at birth
(Figure 5). Data of the cholestyramine-treated groups also
were consistent with the assumption that the reduction of lesions was
mainly attributable to the reduction of TC. However, only 37% of
atherosclerosis could be explained by the maternal cholesterol levels.
Furthermore, treatment with vitamin E was associated with a marked
reduction in lesion size
(Figures 2 and 5) but did not affect cholesterol levels. When
data from groups receiving vitamin E were excluded, the correlation
coefficient increased to r=0.78. The size of
atherosclerotic lesions also significantly correlated with maternal
plasma MDA, particularly when only groups not receiving vitamin E were
analyzed (r=0.62,
P<0.0001).
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Effects of Hypercholesterolemia and
Interventions During Pregnancy at Age 4 Months
To detect whether fetal lesions progress in the absence
of postnatal hypercholesterolemia, some of the offspring were fed
regular chow and examined at age 4 months
(Figure 6). Atherogenesis in the Chol 1 and Chol 2 groups was
greater than in the chow group by 224% and 323%, respectively.
However, absolute lesion sizes in all groups tended to be smaller than
those in their siblings at birth, even though their aortas were much
larger. This was particularly the case in the control, Chol 2, and
Chol2+CH groups (P<0.0001). Thus, lesions formed
during fetal development regress, rather than progress, under the
extremely low cholesterol levels found in chow-fed NZW rabbits (49±2.1
to 58±1.6 mg/dL; NS). As expected, plasma concentrations of
peroxidative end products at 4 months were much lower than at birth
in
absolute terms, and significant decreases in treatment groups were only
seen for 10-OH oleic acid and MDA and only in the Chol 2 groups (data
not shown). In contrast, concentrations of peroxidative end products in
aortic lesions were only slightly lower than those at birth (NS).
Significant treatment effects persisted for 10-OH oleic acid (eg,
P<0.05 in all Chol 1 treatment groups) and
oxidation-specific epitopes (eg, P<0.001 to
P<0.01 in all Chol 1 treatment groups for
EO6-positive sections), whereas aortic levels of
nonoxidized FAs were similar in all groups.
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An additional experiment following the same protocol showed that lesions and some differences between treatment groups still persisted at age 7 months. But, again, this did not indicate progression (data not shown).
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Discussion |
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We previously showed that atherogenesis in human offspring of hypercholesterolemic mothers was more extensive at fetal age and progressed faster during childhood and adolescence.3 The present study investigated the mechanisms responsible for the formation of early lesions during pregnancy using an inbred rabbit model, in which genetic differences are far less prevalent than in humans. It provides two main findings. The first is that temporary induction of maternal hypercholesterolemia in NZW rabbits by dietary intervention enhances fatty streak formation in their offspring. This demonstrates that increased early lesion formation similar to that seen in human fetuses can be caused by events associated with maternal hypercholesterolemia and does not necessarily require genetic differences that are likely to exist between normocholesterolemic and hypercholesterolemic human mothers (and fathers). The fact that cholestyramine lowered cholesterol levels in mothers during pregnancy and decreased lesions in their offspring strongly supports a causal role of maternal hypercholesterolemia in fetal atherogenesis. The second main finding is that intervention with vitamin E during pregnancy also markedly reduced fetal lesion sizes. This provides evidence for the causal role of processes influenced by lipid oxidation in fetal atherogenesis. Together, these data demonstrate, in principle, that hypolipidemic and antioxidant interventions during pregnancy may constitute a novel approach to prevention of atherosclerosis.
In our study, maternal plasma cholesterol in the Chol 1 and
Chol 2 groups was raised from a normal level of 58 mg/dL to 153 and 359
mg/dL, respectively
(Figure 1). Both dietary and plasma cholesterol
concentrations were much lower than those conventionally used to induce
atherosclerosis in NZW rabbits. Therefore, it is not surprising that
the average lesion area in the aorta at birth was very small in
absolute terms. Our experimental conditions were designed to achieve
cholesterol levels comparable to those of human mothers in the
hypercholesterolemic groups of our previous studies (280 and 460 mg/dL;
see Reference 44 , Figure 7). However, it should be kept in mind that
both human and rabbit cholesterol levels reported here represent
averages of several determinations throughout pregnancy and that a
significant increase of cholesterol toward the end of pregnancy occurs
even in otherwise normocholesterolemic
women.9 17
Maternal hypercholesterolemia of NZW rabbits resulted in
marked increases in aortic lesion sizes in their offspring at term
birth, which was greatest in the group exposed to the highest
cholesterol levels (Chol 2)
(Figure 2). Cholestyramine consistently reduced both maternal
cholesterol and lesion sizes in offspring, indicating a direct
correlation between the two parameters. Linear regression analysis of
all groups not receiving antioxidants confirmed a substantial influence
of the maternal cholesterol on lesion sizes
(Figure 5). However, the extent of atherosclerosis in the
cholestyramine groups was not quite reduced to that of untreated groups
with matching cholesterol levels
(Figures 1 and 4), indicating involvement of atherogenic
mechanisms other than hypercholesterolemia. Although maternal
hypercholesterolemia thus plays a major role in fetal atherogenesis, it
remains unclear whether this means an increased transplacental passage
of maternal LDL and VLDL, increased transfer of
FAs,16 or increase
passage of oxidized FAs, oxidized FA fragments, or other transducers or
end effectors.
One of the potential mechanisms contributing to the
atherogenic effect of maternal hypercholesterolemia is an increase of
peroxidative end products in both mother and fetus. LDL oxidation not
only occurs in atherosclerotic lesions of the adult animals and
humans,10 but also
in fatty streaks of human
fetuses.1 Several
pathways by which OxLDL may promote atherogenesis have been
identified. These include accelerated foam cell formation by enhanced
macrophage uptake of OxLDL via scavenger receptors and the recruitment
of monocytes and T-cells into the
intima.1 11
Oxidation also influences nuclear receptor pathways, such as nuclear
factor-
B and peroxisome proliferator-activated receptor 
, which
regulate expression of adhesion molecules, growth factors, and
proinflammatory genes, and affect cell cycle and
apoptosis.19 20 21 22 23
Regulation of vasotonus by nitric oxide is also impaired by
OxLDL.24 Finally,
OxLDL has profound immunological consequences that modulate
atherogenesis.25
Extensive evidence indicates that hypercholesterolemia is accompanied
by increased plasma levels of peroxidative
products.26 27 28
(Conversely, in our study the cholestyramine-induced reduction of
maternal TC was associated with a decrease of peroxidative end products
in plasma and, more importantly, in early atherosclerotic lesions.) We
had postulated, therefore, that oxidation-sensitive mechanisms play an
important role in lesion formation associated with maternal
hypercholesterolemia.
Antioxidant intervention during pregnancy markedly reduced early atherogenesis. The fact that this was not associated with a decrease in plasma cholesterol strongly supports the pathogenic role of oxidation, but we cannot rule out unrelated effects of vitamin E in the arterial wall.29 As expected, peroxidative end products, such as oxidized FAs and MDA, were markedly reduced in early lesions and plasma of vitamin E–treated groups. Cholestyramine also reduced lipid oxidation, albeit to a lesser extent, suggesting that substrate availability is a major determinant. However, shifts in placental passage of specific FAs resulting from the hypocholesterolemic intervention may also have played a role.30 Combinations of cholestyramine and vitamin E tended to be even more protective than cholestyramine or vitamin E alone, in particular in rabbits fed Chol 2, but failed to completely abolish the increase in lesion formation compared with normocholesterolemic controls, probably because of insufficient protection achieved under the present experimental conditions.
The present results demonstrate the role of maternal hypercholesterolemia in early atherogenesis in offspring and the efficacy of interventions with vitamin E or cholestyramine. The results also establish an experimental model of human fetal atherogenesis, but additional studies are needed to determine whether fetal hypercholesterolemia and lipid peroxidation also accelerate the progression of atherosclerosis and whether interventions in mothers affect this. Our first exploratory experiment indicated that fetal lesions and therapeutic effects persist for a prolonged time but could not test its long-term consequences in the absence of lesion progression. The absence of atherogenesis or regression of fetal lesions is probably attributable to the fact that cholesterol levels in chow-fed NZW rabbits are extremely low compared with what is considered normal in humans. This may be overcome in future experiments by exposing rabbits to a mildly hypercholesterolemic diet after birth. Nevertheless, the lack of progression suggests that other risk factors of atherosclerosis, including differences in genetic background, may be required for the faster progression of atherosclerosis seen in children of hypercholesterolemic mothers.3
If it can be established that fetal lesion formation influences the rate of progression of atherosclerosis later in life, our results would indicate novel approaches for prevention. Dietary intervention in pregnant women may be one way to lower cholesterol.31 Cholestyramine also seems to be safe during pregnancy and is commonly used in pruritus associated with cholestasis.5 32 33 Antioxidant interventions significantly reduced atherosclerosis in experimental models but had only mixed success in preventing recurrent cardiovascular events in patients with preexisting coronary heart disease.34 However, it is possible that antioxidant protection is most effective in early stages of atherosclerosis and, therefore, may offer greater benefits to fetuses than to adults. We chose vitamin E and cholestyramine because of their safety during pregnancy and to prove, in principle, that lipid-lowering and antioxidant intervention may be beneficial, but more powerful hypolipidemic drugs and antioxidants may offer greater benefits. Finally, by demonstrating the role of maternal hypercholesterolemia, our results support the inclusion of maternal hypercholesterolemia during pregnancy among the risk factors that determine the need for more intense monitoring in children than currently recommended.4 5 35
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Acknowledgments |
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This work was supported by National Heart, Lung, and Blood Institute grant HL56989, ISNIH grant 56980/99, and MURST 96.40%. We thank Dr F.P. D’Armiento and Dr P. Somma for participation in quantification of atherosclerosis.
Received August 1, 2000; revision received September 7, 2000; accepted September 8, 2000.
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