Normalization of low-density lipoprotein levels and disappearance of xanthomas during pregnancy in a woman with heterozygous familial hypercholesterolemia

The History of the WHHL Rabbit, an Animal Model of Familial Hypercholesterolemia (II) - Contribution to the Development and Validation of the Therapeutics for Hypercholesterolemia and Atherosclerosis

A number of effective drugs have been developed through animal experiments, contributing to the health of many patients. In particular, the WHHL rabbit family (WHHL rabbits and its advanced strains (coronary atherosclerosis-prone WHHL-CA rabbits and myocardial infarction-prone WHHLMI rabbits) developed at Kobe University (Kobe, Japan) contributed greatly in the development of cholesterol-lowering agents. The WHHL rabbit family is animal models for human familial hypercholesterolemia, coronary atherosclerosis, and coronary heart disease. At the end of breeding of the WHHL rabbit family, this review summarizes the contribution of the WHHL rabbit family to the development of lipid-lowering agents and anti-atherosclerosis agents. Studies using the WHHL rabbit family demonstrated, for the first time in the world, that lowering serum cholesterol levels or preventing LDL oxidation can suppress the progression and destabilization of coronary lesions. In addition, the WHHL rabbit family contributed to the development of various compounds that exhibit lipid-lowering and anti-atherosclerotic effects and has also been used in studies of gene therapeutics. Furthermore, this review also discusses the causes of the increased discrepancy in drug development between the results of animal experiments and clinical studies, which became a problem in recent years, and addresses the importance of the selection of appropriate animal models used in studies in addition to an appropriate study design.

ASPECTS OF DETECTING PATIENTS WITH FAMILY HYPERCHOLESTEROLEMIA

The review presents current data regarding the etiology and epidemiology of familial hypercholesterolemia (FH), algorithms for identifying patients with FH using clinical scales, genetic testing, cascade screening. The current tactics of treatment of family hypercholesterolemia, including in children and pregnant women, are given.

Pregnancy in a woman with homozygous familial hypercholesterolemia not on low-density lipoprotein apheresis

Pregnancy in women with homozygous familial hypercholesterolemia (FH) has been rarely reported and might pose risks on the mother and her fetus. Although most reported cases remained on low-density lipoprotein (LDL) apheresis, there are no clear guidelines regarding the management of this entity. We report the first case of an uncomplicated pregnancy in a 24-year-old homozygous FH woman who was not maintained on LDL apheresis. FH expresses a wide variability in the phenotype, and management of homozygous FH cases who desire to become pregnant should be individualized based on preconceptional assessment with frequent antenatal follow-up. Decisions on management should be made after weighing the risks versus benefits of LDL apheresis.

Effect of Gengnianchun Recipe on bone mineral density, bone biomechanical parameters and serum lipid level in ovariectomized rats

OBJECTIVE

To observe the effect of Gengnianchun Recipe (GNC) on bone mineral density (BMD), bone biomechanical parameters and serum lipid level in the bilaterally ovariectomized (OVX) rats and to explore the prophylactic and therapeutic action of GNC on ovariectomy induced osteoporosis and hyperlipidemia.

METHODS

OVX SD rats, 10 - 12 months old, were divided into different groups and fed with GNC 2 g/d, GNC 1 g/d and Nilestriol 0.125 mg/week, respectively for 4 months to observe the change of BMD and bone biomechanical parameters of the lumbar vertebrae, and the serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), and to compare the effect of the two drugs on the morphology of the uterus.

RESULTS

There was marked reduction in BMD and biomechanical parameters in lumbar vertebrae (P < 0.01) and increase of serum TC and LDL-C levels (P < 0.01) in rats after OVX. GNC or Nilestriol significantly improved the decreased BMD and biomechanical parameters of the lumbar vertebrae (P < 0.05 or P < 0.01), and reduced the serum TC and LDL-C levels (P < 0.01). In the Nilestriol group, the wet weight of uterus got increased obviously (P < 0.01), the number of uterine glands increased, uterine columnar epithelium thickened, and the mitotic figures in the epithelial stroma and myointimal cells augmented. But no such effect in wet weight and morphology of uterus was found in the GNC group.

CONCLUSION

GNC could increase the BMD and biomechanical parameters of the lumbar vertebrae, reduce the serum TC and LDL-C levels, yet produce no adverse reaction in stimulating proliferation and hypertrophy of uterus.

Pathogenesis, detection and treatment of Achilles tendon xanthomas

Tendon xanthomatosis often accompanies familial hypercholesterolaemia, but it can also occur in other pathologic states. Achilles tendons are the most common sites of tendon xanthomas. Low-density lipoprotein (LDL) derived from the circulation accumulates into tendons. The next steps leading to the formation of Achilles tendon xanthomas (ATX) are the transformation of LDL into oxidized LDL (oxLDL) and the active uptake of oxLDL by macrophages within the tendons. Although physical examination may reveal Achilles tendon xanthomas (ATX), there are several imaging methods for their detection. It is worth mentioning that ultrasonography is the method of choice in everyday clinical practice. Although several treatments for Achilles tendon xanthomas (ATX) have been proposed (LDL apheresis, statins, etc.), they target mostly in the treatment of the basic metabolic disorder of lipid metabolism, which is the main cause of these lesions. In this review we describe the formation, detection, differential diagnosis and treatment of ATX as well as the relationship between tendon xanthomas and atheroma.

Influence of bilateral oophorectomy upon lipid metabolism

OBJECTIVES

Reduction in serum level of estrogen has been thought to result in hyperlipidemia which triggers atherosclerosis, and even to lead to cardiovascular diseases, in postmenopausal women. The present study was designed to investigate the influence of bilateral oophorectomy (OPX), which induces as much reduction in serum estrogen level as menopause, upon lipid metabolism, especially the serum levels of total cholesterol.

METHODS

In 31 OPX subjects and 31 age- and body size-matched premenopausal controls, the serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein (VLDL-C), apoprotein-A1 (Apo-A1), apoprotein-B (Apo-B), lipoprotein lipase (LPL) and lipoprotein-a [LP(a)] were measured as indices of lipid metabolism and the index of arteriosclerosis was calculated.

RESULTS

TC level was significantly higher in the OPX group than in the premenopausal control group, being 8995 +/- 244 (mean +/- S.E.) mmol/l and 7757 +/- 228 mmol/l, respectively. LDL-C and Apo-B levels and the index of arteriosclerosis were all significantly higher in the OPX group than in the premenopausal control groups. However, there were no significant intergroup differences with regard to HDL-C, Apo-A1, LPL and LP(a).

CONCLUSIONS

The above results demonstrated that, in spite of no reduction in HDL-C, the blood levels of Apo-B, LDL-C and TC change due to OPX. These changes suggest OPX induces cardiovascular diseases and, therefore, follow-up of the changes in lipid metabolism is required, paying special attention to Apo-B and LDL-C.

A cholesterol-rich diet causes a greater hypercholesterolemic response in pregnant than in nonpregnant rats and does not modify fetal lipoprotein profile

To determine whether pregnancy modifies the hyperlipidemic response to a cholesterol-rich diet, pregnant and virgin rats were fed a semisynthetic diet supplemented (CRD) or not (CD) with 2% cholesterol and 1% cholic acid and studied at d 20 of treatment and/or gestation. Plasma triglycerides, free fatty acids and glycerol and liver triglycerides were greater in pregnant than in virgin rats fed CRD. The increase in both plasma and liver cholesterol caused by CRD did not differ in the two groups. In rats fed CD, hepatic lipase activity in liver was lower in pregnant than in virgin rats, while in those fed CRD, virgin rats had lower activity than those fed CD. Plasma VLDL-triglycerides were higher and LDL-triglycerides lower in pregnant than in virgin rats fed CD. Among those fed CRD, pregnant rats had a higher triglyceride concentration in VLDL and HDL than virgin rats. Cholesterol concentration was higher in VLDL and IDL and lower in HDL in both groups fed CRD than in those fed CD, while cholesterol level in LDL was higher only in pregnant rats fed CRD than in those fed CD. Whereas placental cholesterol concentration was higher in pregnant rats fed CRD than CD, maternal CRD intake did not modify fetal plasma lipoprotein concentrations, fetal body weight or litter size, indicating a lack of cholesterol transfer by the rat placenta. Results therefore show a greater responsiveness to CRD in pregnant than in virgin rats, and we propose that CRD promotes greater liver VLDL-production and lower LDL removal in pregnant than in virgin rats.

Pregnancy in a patient with homozygous familial hypercholesterolemia treated with long-term low-density lipoprotein apheresis

The pregnancy and delivery of a subject with homozygous familial hypercholesterolemia (FH) and coronary artery disease (CAD) were monitored closely for signs of maternal and fetal distress. Biweekly treatment with low-density lipoprotein (LDL) apheresis using dextran-sulfate cellulose columns was continued throughout the pregnancy, and lipid and lipoprotein levels were evaluated. During the course of the pregnancy and delivery, no signs of maternal coronary insufficiency developed. Serial ultrasonographic measurements of fetal growth indices and the blood flow velocity waveforms (FVWs) of the uterine and umbilical artery did not reveal any sign of fetal growth retardation or insufficiency of the uteroplacental circulation, respectively. During pregnancy, time-averaged concentrations of serum total cholesterol (TC), LDL cholesterol (LDL-C), apolipoprotein (apo) B, and lipoprotein(a) [Lp(a)] showed a gradual decline. Notwithstanding LDL apheresis, a gradual twofold increase of serum triglyceride (TG) levels was found. In the second and third trimester, high-density lipoprotein cholesterol (HDL-C) levels showed a 55% increase that coincided with a 75% reduction in hepatic lipase activity in postheparin plasma, normalizing after parturition. After delivery, lp(a) levels showed an almost twofold increase, which could not be explained by the interruption of LDL apheresis alone, and may be caused by changes in gonadal steroids. Histologic examination of the placenta and the umbilical arteries revealed no atherosclerotic changes, infarctions, or lipid deposits. In general, long-term LDL apheresis in homozygous FH can delay the onset and complications of severe CAD. In case of a pregnancy, LDL apheresis seems feasible and should be continued during the pregnancy to prevent superimposed hyperlipidemia and placental insufficiency.

Increase in hepatic low-density lipoprotein receptor activity during pregnancy in Watanabe heritable hyperlipidemic rabbits; an animal model for familial hypercholesterolemia

In homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits, the serum cholesterol level and serum low-density lipoprotein (LDL) level decreased from 562 +/- 76 (mean +/- S.E.) to 144 +/- 34 mg/dl and 410 +/- 56 to 90 +/- 25 mg/dl, respectively, during pregnancy, although the LDL receptor in this rabbit is genetically deficient. When Tyroxapol, which inhibits the degradation of very-low-density lipoprotein (VLDL), as well as Triton WR-1339, was injected into WHHL rabbits, the rate of the increase in serum cholesterol level in pregnant rabbits was not statistically different from that in non-pregnant rabbits. This result implied that the secretion rate of VLDL-cholesterol, the precursor of LDL-cholesterol, did not decrease during pregnancy. The amount of 125I-labeled LDL bound to LDL receptor was increased 1.8-fold in normal rabbits (from 29.3 +/- 4.3 to 52.3 +/- 4.6 ng/mg protein) and 12-fold in WHHL rabbits (from 0.5 +/- 0.2 to 6.0 +/- 0.7 ng/mg protein) during pregnancy. These results suggest that the decrease in serum cholesterol level in WHHL rabbits during pregnancy was associated with an increase in hepatic LDL receptor activity, which plays an important role in the regulation of serum cholesterol level.