Cholesterol auxotrophy and intolerance to ezetimibe in mice with SREBP-2 deficiency in the intestine.

SREBP-2 activates transcription of all genes needed for cholesterol biosynthesis. To study SREBP-2 function in the intestine, we generated a mouse model (Vil-BP2-/- ) in which Cre recombinase ablates SREBP-2 in intestinal epithelia. Intestines of Vil-BP2-/- mice had reduced expression of genes required for sterol synthesis, in vivo sterol synthesis rates, and epithelial cholesterol contents. On a cholesterol-free diet, the mice displayed chronic enteropathy with histological abnormalities of both villi and crypts, growth restriction, and reduced survival that was prevented by supplementation of cholesterol in the diet. Likewise, SREBP-2-deficient enteroids required exogenous cholesterol for growth. Blockade of luminal cholesterol uptake into enterocytes with ezetimibe precipitated acutely lethal intestinal damage in Vil-BP2-/- mice, highlighting the critical interplay in the small intestine of sterol absorption via NPC1L1 and sterol synthesis via SREBP-2 in sustaining the intestinal mucosa. These data show that the small intestine requires SREBP-2 to drive cholesterol synthesis that sustains the intestinal epithelia when uptake of cholesterol from the gut lumen is not available, and provide a unique example of cholesterol auxotrophy expressed in an intact, adult mammal.

Cholesterol and egg intakes and the risk of type 2 diabetes: the Japan Public Health Center-based Prospective Study.

Limited and inconsistent associations between cholesterol and egg consumption and type 2 diabetes risk have been observed in Western countries. In the present study, the association of dietary cholesterol and egg intakes with type 2 diabetes risk was examined prospectively. The study subjects comprised 27, 248 men and 36,218 women aged 45-75 years who participated in the second survey of the Japan Public Health Center-based Prospective Study and had no histories of type 2 diabetes or other serious diseases. Dietary cholesterol and egg intakes were estimated using a validated 147-item FFQ. The OR of self-reported, physician-diagnosed type 2 diabetes over 5 years were estimated using multiple logistic regression. A total of 1165 newly diagnosed cases of type 2 diabetes were self-reported. Although dietary cholesterol intake was not associated with type 2 diabetes risk in men, it was found to be associated with a 23 % lower odds of type 2 diabetes risk in women in the highest quartile of intake, albeit not statistically significant, compared with those in the lowest quartile (P trend= 0·08). Such risk reduction was somewhat greater among postmenopausal women; the multivariable-adjusted OR for the highest quartile of cholesterol intake compared with the lowest quartile was 0·68 (95 % CI 0·49, 0·94; P trend= 0·04). No association between egg intake and type 2 diabetes risk was found in either men or women. In conclusion, higher intake of cholesterol or eggs may not be associated with an increased risk of type 2 diabetes in Japanese populations. The observed association between decreased type 2 diabetes risk and higher dietary cholesterol intake in postmenopausal women warrants further investigation.

Cholesterol- and lanolin-rich diets may protect against steroid-induced osteonecrosis in rabbits.

BACKGROUND AND PURPOSE: It remains controversial how hypercholesterolemia influences the development of steroid-induced osteonecrosis (ON). We investigated the role of hypercholesterolemia induced by a cholesterol-rich diet on the development of ON in rabbits. METHODS: 40 adult male Japanese white rabbits were randomly divided into 2 groups. 20 rabbits were maintained on a cholesterol-rich diet for 2 weeks before receiving steroid treatment (the CHOL group). The other 20 rabbits were maintained on a standard diet (the control (CTR) group). 2 weeks after the start of the study, all 40 rabbits were injected with methylprednisolone acetate (MPSL) into the right gluteus medius muscle (20 mg/kg body weight). 2 weeks after the steroid injection, both the femora and humeri were examined histopathologically for the presence of ON. Hematological analysis of the serum lipid levels was performed every week. Based on the same protocol, we also investigated the effects of lanolin, a primary component of a cholesterol-rich diet, in another group (the LA group). RESULTS: The incidence of ON in the CHOL group (3/20) was lower than that observed in the CTR group (15/20) (p < 0.001). During the whole experiment, the levels of total cholesterol and the ratio of low-density lipoprotein to high-density lipoprotein in the CHOL group were higher than those observed in the CTR group (p < 0.001). The LA group also had a lower incidence of ON (2/20), and the lipid levels in the LA group showed similar changes to those observed in the CHOL group. INTERPRETATION: Our findings suggest that preexisting hypercholesterolemia itself induced by a cholesterol-rich diet does not increase the risk of developing steroid-induced ON, but rather seems to diminish it. Lanolin may be the active anti-ON component of the cholesterol diet.

Treatment of Smith-Lemli-Opitz syndrome and other sterol disorders.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive genetic condition with a broad phenotype that results from deficiency of the final enzyme of the cholesterol synthesis pathway. This defect causes low or low-normal plasma cholesterol levels and increased 7- and 8-dehydrocholesterol (DHC) levels. Many therapies for SLOS and other disorders of sterol metabolism have been proposed, and a few of them have been undertaken in selected patients, but robust prospective clinical trials with validated outcome measures are lacking. We review the current literature and expert opinion on treatments for SLOS and other selected sterol disorders, including dietary cholesterol therapy, statin treatment, bile acid supplementation, medical therapies, and surgical interventions, as well as directions for future therapies and treatment research.

N-3 polyunsaturated fatty acid attenuates cholesterol gallstones by suppressing mucin production with a high cholesterol diet in mice.

BACKGROUND AND AIM: The increasing prevalence of cholesterol gallstone (CG) disease has become an economic burden to the healthcare system. Ursodeoxycholic acid (UDCA) is the only established medical agent used to dissolve gallstones. In investigating novel therapeutics for CG, we assessed the preventive effects of n-3 polyunsaturated fatty acids (n-3PUFA) on the formation of CG induced by feeding a lithogenic diet (LD) containing high cholesterol levels to mice. METHODS: Mice were divided into the following six groups: (A) regular diet (RD); (B) RD+n-3PUFA; (C) LD; (D) LD+n-3PUFA; (E) LD+UDCA; (F) LD+n-3PUFA+UDCA. After RD/LD feeding for 2 weeks, n-3PUFA or UDCA was administered orally and the diet maintained for 8 weeks. The levels of phospholipids and cholesterol in bile, CG formation, gallbladder wall thickness, MUC gene expression in gallbladder were analyzed. RESULTS: No stone or sludge was evident in the RD groups (Groups A, B). Mice in the n-3PUFA treatment (Groups D, F) showed significantly lower stone formation than the other LD groups (Groups C, E). The combination treatment of n-3PUFA and UDCA suppressed stone formation more than mono-therapy with n-3PUFA or UDCA. Bile phospholipid levels were significantly elevated in the Group F. Hypertrophy of the gallbladder wall was evident in mice fed LD. MUC 2, 5AC, 5B and 6 mRNA expression levels were significantly elevated in the LD-fed group, and this was suppressed by n-3PUFA with or without UDCA. CONCLUSIONS: N-3PUFA attenuated gallstone formation in mouse, through increasing the levels of bile phospholipids and suppressing bile mucin formation.

Therapy of Pelizaeus-Merzbacher disease in mice by feeding a cholesterol-enriched diet.

Duplication of PLP1 (proteolipid protein gene 1) and the subsequent overexpression of the myelin protein PLP (also known as DM20) in oligodendrocytes is the most frequent cause of Pelizaeus-Merzbacher disease (PMD), a fatal leukodystrophy without therapeutic options. PLP binds cholesterol and is contained within membrane lipid raft microdomains. Cholesterol availability is the rate-limiting factor of central nervous system myelin synthesis. Transgenic mice with extra copies of the Plp1 gene are accurate models of PMD. Dysmyelination followed by demyelination, secondary inflammation and axon damage contribute to the severe motor impairment in these mice. The finding that in Plp1-transgenic oligodendrocytes, PLP and cholesterol accumulate in late endosomes and lysosomes (endo/lysosomes), prompted us to further investigate the role of cholesterol in PMD. Here we show that cholesterol itself promotes normal PLP trafficking and that dietary cholesterol influences PMD pathology. In a preclinical trial, PMD mice were fed a cholesterol-enriched diet. This restored oligodendrocyte numbers and ameliorated intracellular PLP accumulation. Moreover, myelin content increased, inflammation and gliosis were reduced and motor defects improved. Even after onset of clinical symptoms, cholesterol treatment prevented disease progression. Dietary cholesterol did not reduce Plp1 overexpression but facilitated incorporation of PLP into myelin membranes. These findings may have implications for therapeutic interventions in patients with PMD.

Cholesterol diet leads to attenuation of ischemic preconditioning-induced cardiac protection: the role of connexin 43.

Cardioprotection by ischemic preconditioning (IP) was abolished in connexin 43 (Cx43)-deficient mice due to loss of Cx43 located in mitochondria rather than at the sarcolemma. IP is lost in hyperlipidemic rat hearts as well. Since changes in mitochondrial Cx43 in hyperlipidemia have not yet been analyzed, we determined total and mitochondrial Cx43 levels in male Wistar rats fed a laboratory chow enriched with 2% cholesterol or normal chow for 12 wk. Hearts were isolated and perfused according to Langendorff. After a 10-min perfusion, myocardial tissue cholesterol, superoxide, and nitrotyrosine contents were measured and Cx43 content in whole heart homogenate and a mitochondrial fraction determined. In the cholesterol-fed group, tissue cholesterol and superoxide formation was increased (P < 0.05), while total Cx43 content remained unchanged. Mitochondrial total and dephosphorylated Cx43 content decreased. Hearts were subjected to an IP protocol (3 × 5 min ischemia-reperfusion) or time-matched aerobic perfusion followed by 30-min global ischemia and 5-min reperfusion. IP reduced infarct size in normal but not in cholesterol-fed rats. At 5-min reperfusion following 30-min global ischemia, the total and dephosphorylated mitochondrial Cx43 content was increased, which was abolished by IP in both normal and high-cholesterol diet. In conclusion, loss of cardioprotection by IP in hyperlipidemia is associated with a redistribution of both sarcolemmal and mitochondrial Cx43.

Regulación de la absorción intestinal de colesterol: el papel protagonista de NPC1L1 y sus polimorfismos funcionales / Regulation of intestinal cholesterol absorption: the prominent role of NPC1L1 and its functional polymorphisms

No disponible

Dramatically increased intestinal absorption of cholesterol following hypophysectomy is normalized by thyroid hormone.

BACKGROUND & AIMS: Hypopituitarism is associated with dyslipidemia, and feeding hypophysectomized rats cholesterol induces severe hypercholesterolemia. This study aimed to unravel further how hypophysectomy alters cholesterol and bile acid metabolism. METHODS: Intact and hypophysectomized rats were studied during challenge with dietary cholesterol and ezetimibe and upon hormonal substitution with growth hormone, cortisone, and thyroid hormone. RESULTS: Five findings were established in hypophysectomized rats: (1) The intestinal absorption of cholesterol is doubled. (2) Treatment with ezetimibe abolishes the increases in serum and liver cholesterol. (3) Only thyroid hormone treatment normalizes the increased absorption of cholesterol. (4) The intestinal gene expression of cholesterol transporters NPC1L1 and ABCG5/G8 is unaltered, whereas the hepatic expression of ABCG5/G8 is diminished but strongly stimulated by thyroid hormone. The latter mechanism was supported by measurements of biliary cholesterol and of fecal neutral steroids. (5) The reduced hepatic expression of ABCG5/G8 and Cyp7a1 was normalized by cholesterol feeding, suggesting that other nonestablished mechanisms under pituitary control are important to maintain rats resistant to dietary cholesterol. CONCLUSIONS: The intestinal absorption of dietary cholesterol is under pituitary control largely exerted by thyroid hormone. Hepatic secretion of cholesterol and ABCG5/G8 expression are strongly stimulated in hypophysectomized rats during treatment with thyroid hormone.

Behavioral effects of dietary cholesterol in rats tested in experimental models of mild stress and cognition tasks.

Abnormalities in serum cholesterol levels of patients with mood disorders have been identified in epidemiological studies. However, evidence for an influence of dietary cholesterol on behavioral models is poor. Here, we investigated the behavioral changes of Wistar male rats fed a 2% cholesterol-enriched diet for 2 months in experimental models of depression and anxiety, such as the forced swim test (FST) paradigm and the novelty-induced grooming sampling test (NGT). The correlation between behavioral depression and impaired cognitive capacity was also examined testing rats in the Morris water maze (MWM) task one day after the FST. Different groups of rats fed various dietary regimens, were subjected to acute or repeated treatment (14 days) with clomipramine hydrochloride (50 or 25 mg/kg), diazepam (1 mg/kg) or with the peripheral benzodiazepine receptors (PBRs) antagonist, isoquinoline PK11195 (1 mg/kg) injected intraperitoneally (i.p.). Rats fed the cholesterol-enriched diet showed a significant decrease of grooming score in the NGT and of immobility time in the FST in comparison to animals fed a standard diet. Furthermore, the anxiolytic and antidepressant effects of diazepam and clomipramine were not affected by the different diets. Only after repeated treatment, PK11195 impaired the performance of animals fed a standard diet in the FST, and exhibited an anxiolytic-like profile in animals fed either the cholesterol-enriched or the standard diet. The improved performance in the FST was followed by a better learning performance in the acquisition phase of the MWM. These results suggest that effects of cholesterol-enriched diet on the behavioral reaction of rats in experimental models of mild stress may involve PBRs. They deserve attention in order to clarify the clinical correlation between plasma cholesterol levels and mood disorders in humans.

Endotelial dysfunction, lipid peroxidation and cholesterol level in rabbit arteries: relationship to progressive hypercholesterolemia / Endotelial dysfunction, lipid peroxidation and cholesterol level in rabbit arteries: relationship to progressive hypercholesterolemia

Objective. The aim of this study was to evaluate the influence of a gradual increase in the plasma total cholesterol concentration and of lipid peroxidation on endothelial function in rabbit arteries. Material and methods. Fifty male New Zealand white rabbits were fed a diet enriched with 0.5% cholesterol and 10% coconut oil and were allocated to one of nine groups (G2 to G10) based on sequential determinations of their plasma total cholesterol concentration (each group covered an interval of 100 mg/dL). The control group (G1) consisted of five rabbits fed a non-supplemented diet. The rabbits were killed at the end of the treatment and the total plasma cholesterol concentration, arterial wall cholesterol level and lipid peroxidation based on the quantification of malondialdehyde were determined using commercial kits. Endothelial function was assessed based on concentration-response curves to acetylcholine and sodium nitroprusside in aortic segments. Results: Treatment with a cholesterol-rich diet resulted in disproportional increases in the arterial wall cholesterol concentration, lipid peroxidation and a disproportional decrease in the maximum endothelium-dependent relaxations in relation to the plasma total cholesterol concentration. However, the maximum endothelium-dependent relaxations were proportional to the increase in the arterial wall content of malondialdehyde. Conclusions. These results show that the levels of arterial wall cholesterol, lipid peroxidation and endothelial dysfunction are not proportional to the degree of hypercholesterolemia, although endothelial dysfunction is proportional to the extent of lipid peroxidation in the vessel wall (AU)

Introducción. El objetivo de este estudio ha sido evaluar la influencia de un aumento gradual en la concentración de colesterol total plasmático y de la peroxidación lipídica sobre la función endotelial en arterias de conejo. Material y métodos. Cincuenta conejos macho New Zealand fueron alimentados con una dieta enriquecida en colesterol al 0,5% y un 10% de aceite de coco y fueron distribuidos en nueve grupos (G2 a G10) según las determinaciones secuenciales de sus concentraciones plasmáticas de colesterol (cada grupo cubrió un intervalo de 100 mg/dl). El grupo control (G1) estaba formado por 5 conejos alimentados con una dieta no suplementada. Los animales se sacrificaron al final del tratamiento y la concentración de colesterol total plasmático, los valores de colesterol de la pared arterial y la peroxidación lipídica basada en la cuantificación de los valores de malondialdehído se determinaron utilizando kits comerciales. La función endotelial se valoró utilizando curvas concentración-respuesta a la acetilcolina y a nitroprusiato sódico en segmentos de aorta. Resultados. El tratamiento con la dieta rica en colesterol causó un aumento desproporcionado en la concentración de colesterol en la pared arterial, la peroxidación lipídica y una reducción desproporcionada en las relajaciones máximas dependientes del endotelio en relación con la concentración plasmática de colesterol total. Sin embargo, las relajaciones máximas dependientes del endotelio fueron proporcionales al aumento en la pared arterial del contenido de malondialdehído. Conclusiones. Estos resultados muestran que los valores de colesterol de la pared arterial, la peroxidación lipídica y la función endotelial no son proporcionales al grado de hipercolesterolemia, aunque la disfunción endotelial es proporcional a la extensión de la de la peroxidación lipídica en la pared del vaso (AU)

Partial rescue of retinal function and sterol steady-state in a rat model of Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS) is the first-described in a growing family of hereditary defects in cholesterol biosynthesis, and presents with a spectrum of serious abnormalities, including multiple dysmorphologies, failure to thrive, cognitive and behavioral impairments, and retinopathy. Using a pharmacologically induced rat model of SLOS that exhibits key hallmarks of the disease, including progressive retinal degeneration and dysfunction, we show that a high-cholesterol diet can substantially correct abnormalities in retinal sterol composition, with concomitant improvement of visual function, particularly within the cone pathway. Although histologic degeneration still occurred, a high-cholesterol diet reduced the number of pyknotic photoreceptor nuclei, relative to animals on a cholesterol-free diet. These findings demonstrate that cholesterol readily crosses the blood-retina barrier (unlike the blood-brain barrier) and suggest that cholesterol supplementation may be efficacious in treating SLOS-associated retinopathy.

A case of Smith-Lemli-Opitz Syndrome, defect of cholesterol biosynthesis.

We report the case of a child with Smith-Lemli-Opitz Syndrome. The pregnancy was complicated by prenatal growth retardation. The baby was admitted to the Neonatal Intensive Care Unit of Chieti when she was five months old. She showed postnatal growth retardation, trouble sucking and swallowing, microcephaly and multiple major and minor malformations, including characteristic facial features and 2-3 syndactyly of the toes. We found correlations between multiple congenital malformations, failure to thrive and low plasmatic cholesterol measurement.

Intestinal absorption of cholesterol by patients with Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS) is a disorder of impaired cholesterol biosynthesis because of a deficiency of the enzyme 7-dehydrocholesterol-Delta(7)-reductase, in the last step in cholesterol biosynthesis. Dietary cholesterol has been proposed as a potential therapy for SLOS and is being tested currently. Because there is no information on cholesterol absorption in SLOS, we recruited 12 SLOS patients into the General Clinical Research Center for 1-wk periods for administration of test meals and for blood and stool collections. A test breakfast that contained tracer cholesterol-4-C(14) with egg yolk or with crystalline cholesterol in suspension was given subsequently. Twenty-four and 48-h blood and 1-wk stool samples then were collected. The radioactivities in these samples were analyzed to determine the absorption of cholesterol by these patients. In 11 patients who were given egg yolk cholesterol, cholesterol absorption was 27.3 +/- 6.7%. The absorption was slightly less at 20.5 +/- 10.3% but not significantly different for the six patients who were given crystalline cholesterol. There was a positive correlation between the absorption of isotopic cholesterol as measured by determination of radioactive cholesterol in stool and the amount of isotopic cholesterol in the plasma at 24 and 48 h after the meal. Our data indicated that SLOS patients absorb cholesterol from the diet. However, the percentage of absorption is lower than reported values for normal adults and for hypercholesterolemic children. The absorption of crystalline cholesterol in suspension was slightly lower than the absorption of cholesterol in egg yolk cholesterol by these patients. The absorption of cholesterol may ameliorate some of the biochemical and developmental deficits in SLOS patients.

Hypercholesterolemic diet applied to rat dams protects their offspring against cognitive deficits. Simulated neonatal anoxia model.

There is accumulating data suggesting a neuroprotective activity of cholesterol, especially in stroke and Alzheimer's disease (AD). In the present study, a protective activity of this lipid in simulated neonatal anoxia was investigated. Rats were subjected to high cholesterol by feeding their dams with a diet enriched with cholesterol. Half of these rats were subjected to anoxia. One and a half months later, the rats were tested for their ability to acquire a spatial memory, one group on the linear maze and the other on the Morris water maze. After these assessments, the level of total plasma cholesterol was measured. Rats from dams subjected to neonatal anoxia on standard diet performed worse than control rats in both types of behavioral experiments, whereas anoxic rats from dams were housed on hypercholesterolemic diet performed as control animals. It suggests that dietetic cholesterol applied by their dams protected rats against cognitive deficits elicited by neonatal anoxia. Furthermore, offspring of anoxic rats housed on standard diet had elevated levels of blood cholesterol in relation to control animals. Generally, anoxia affected the concentration of this lipid much stronger than hypercholesterolemic diet of their dams. It might mean that the anoxia-related rise of cholesterol could be involved in physiological phenomenon being an adaptive response to neurotoxic processes. This concept is discussed in relation to pathological mechanisms in AD.

Cholesterol supplementation does not improve developmental progress in Smith-Lemli-Opitz syndrome.

OBJECTIVE: Smith-Lemli-Opitz syndrome (SLOS) results in multiple malformations, growth deficiency, and mental retardation. Cholesterol supplementation has been used for several years to treat symptoms of SLOS. We assessed the developmental progress of children and adolescents with SLOS over a 6-year period. STUDY DESIGN: Patients with SLOS (n=14) received continuous cholesterol supplementation as part of a longitudinal study. Assessment of their developmental progress in the areas of cognitive, motor, and adaptive skills occurred every 6 to 12 months. The progress of each subject over time and the progress of the group as a whole were analyzed by using a repeated-measures design and multiple t tests. RESULTS: Developmental quotients did not improve over time for children with SLOS receiving cholesterol. In addition, baseline cholesterol levels, rather than age when supplementation began or increase in cholesterol levels, best predicted developmental outcome. CONCLUSIONS: These results suggest that cholesterol supplementation in its current form does not improve the developmental progress of children and adolescents with SLOS.

[Therapeutic effects of phytosterols and phytostanols in cholesterolemia]. / Efeitos terapêuticos dos fitosteróis e fitostanóis na colesterolemia.

Plant sterol and stanol esters are called "functional" compounds due to their hypocholesterolemic properties. The objective of this review is to update recent findings concerning the effect of phytosterols in the blood cholesterol, emphasizing the results from experimental and human studies. The hypocholesterolemic effect is observed with the intake of 2.5g/day of phytosterols or phytostanols. Daily intake, usually of stanols, for 4 weeks has shown to to be effective in lowering blood total- as well as LDL-cholesterol by about 10%. The mechanism of action in lowering blood cholesterol comes from their structural similarity to cholesterol, hence they act by competing with cholesterol at the luminal absorption site. The adverse effects of a high intake of phytosterols and phytostanols are the lower absorption of some liposoluble vitamins and antioxidants.