Marina Del Puppo

Cholesterol Metabolism After Bariatric Surgery in Grade 3 Obesity: Differences between malabsorptive and restrictive procedures

OBJECTIVE Malabsorptive bariatric surgery (biliopancreatic diversion and biliointestinal bypass [BIBP]) reduces serum cholesterol levels more than restrictive surgery (adjustable gastric banding [AGB]), and this is thought to be due to greater weight loss. Our aim was to evaluate the changes of cholesterol metabolism induced by malabsorptive and restrictive surgery independent of weight loss. RESEARCH DESIGN AND METHODS In a nonrandomized, self-selected, unblinded, active-comparator, bicenter, 6-month study, glucose metabolism (blood glucose and serum insulin levels and homeostasis model assessment of insulin resistance [HOMA-IR] index) and cholesterol metabolism (absorption: serum campesterol and sitosterol levels; synthesis: serum lathosterol levels; catabolism: rate of appearance and serum concentrations of serum 7-α- and serum 27-OH-cholesterol after infusions of deuterated 7-α- and 27-OH-cholesterol in sequence) were assessed in grade 3 obesity subjects undergoing BIBP (n = 10) and AGB (n = 10). Evaluations were performed before and 6 months after surgery. RESULTS Subjects had similar values at baseline. Weight loss was similar in the two groups of subjects, and blood glucose, insulin levels, HOMA-IR, and triglycerides decreased in a similar way. In contrast, serum cholesterol, LDL cholesterol, non-HDL cholesterol, serum sitosterol, and campesterol levels decreased and lathosterol levels increased only in BIBP subjects, not in AGB subjects. A significant increase in 7-α-OH-cholesterol occurred only with BIBP; serum 27-OH-cholesterol decreased in both groups. CONCLUSIONS Malabsorptive surgery specifically affects cholesterol levels, independent of weight loss and independent of glucose metabolism and insulin resistance. Decreased sterol absorption leads to decreased cholesterol and LDL cholesterol levels, accompanied by enhanced cholesterol synthesis and enhanced cholesterol catabolism. Compared with AGB, BIBP provides greater cholesterol lowering.

Evaluation of cholesterol metabolism in cerebrotendinous xanthomatosis

BackgroundCerebrotendinous xanthomatosis (CTX) is a treatable bile acid disorder caused by mutations of CYP27A1. The pathogenesis of neurological damage has not been completely explained. Oral chenodeoxycholic acid (CDCA) can lead to clinical stabilization, but in a subgroup of patients the disease progresses despite treatment. In the present study, we aimed at clarifying cholesterol metabolism abnormalities and their response to CDCA treatment, in order to identify reliable diagnostic and prognostic markers and understand if differences exist between stable patients and those with neurological progression.MethodsWe enrolled 19 untreated CTX patients and assessed serum profile of bile acids intermediates, oxysterols, cholesterol, lathosterol, and plant sterols. Then we performed a long-term follow up during CDCA therapy, and compared biochemical data with neurological outcome.ResultsWe observed increase of cholestanol, 7α-hydroxy-4-cholesten-3-one (7αC4), lathosterol, and plant sterols, whereas 27-hydroxycholesterol (27-OHC) was extremely low or absent. CDCA treatment at a daily dose of 750xa0mg normalized all biochemical parameters except for 7αC4 which persisted slightly higher than normal in most patients, and 27-OHC which was not modified by therapy. Biochemical evaluation did not reveal significant differences between stable and worsening patients.DiscussionCholestanol and 7αC4 represent important markers for CTX diagnosis and monitoring of therapy. Treatment with CDCA should aim at normalizing serum 7αC4 as well as cholestanol, since 7αC4 better mirrors 7α-hydroxylation rate and is thought to be correlated with cholestanol accumulation in the brain. Assessment of serum 27-OHC is a very good tool for biochemical diagnosis at any stage of disease. Lathosterol and plant sterols should be considered as additional markers for diagnosis and monitoring of therapy. Further studies including long-term assessment of bile acid intermediates in cerebrospinal fluid are needed in patients who show clinical progression despite treatment.

Modulation of HMG-CoA reductase activity by pantetheine/pantethine

The ability of pantetheine/pantethine to modulate the activity of HMG-CoA reductase (EC 1.1.1.34) was determined in vitro with rat liver microsomes. The decay of the activity was obtained with pantethine in the 10(-5)-10(-4) M range, whereas stimulation by pantetheine occurred at 10(-3)-10(-2) M, as previously reported for GSSG and GSH, respectively. Inhibition of HMG-CoA by pantethine in isolated liver cells was also investigated by measuring the enzyme activity in microsomes isolated from hepatocytes incubated without or with 1 mM pantethine under conditions previously shown by us to induce inhibition of cholesterol synthesis from acetate. The enzyme amount was not modified by pantethine, but in cells treated with the disulphide, the relative amounts of the thiolic active forms of the enzyme, both phosphorylated and dephosphorylated, were decreased to about half compared to controls.

Oxysterols in bile acid metabolism.

Increasing body of evidence is available indicating that oxysterols are more much than intermediates of metabolic pathways. Oxysterols play a role in the regulation of cholesterol synthesis, transport and efflux. A scavenger effect of cholesterol 27-hydroxylase on elevated serum cholesterol levels is well demonstrated. Bile acid synthesis occurs through two main pathways, the classic and the alternative ones. Since plasma concentrations of 27-hydroxycholesterol were clearly shown to reflect its production rate the alternative pathway of bile acid synthesis can be easily explored. Conversely this was not true for 7α-hydroxycholesterol and also the direct evaluation of the classic pathway by kinetic studies is more difficult since the rate of plasma appearance during continuous infusion of deuterated isotopomers may not exactly measure its production rate. Hepatic cholesterol 7alpha-hydroxylase activity is absent during fetal life in humans and upregulates after birth. Both the classic and alternative pathways become mature after the age of 4 years. It has been clearly demonstrated that in patients with liver disease the classic pathway is impaired while the alternative one is preserved. Conversely, in obese patients, preliminary data suggest an increase of the production rate of 27-hydroxycholesterol, a possible mechanism to counteract the increase of atherosclerotic risk.

Effects of bile duct ligation and cholic acid treatment on fatty liver in two rat models of non-alcoholic fatty liver disease

BACKGROUNDnNon-alcoholic fatty liver disease, one of the most prevalent liver disorders in Western countries, is characterized by hepatic accumulation of triglycerides. Bile acids have long been known to affect triglyceride homeostasis through a not completely understood mechanism.nnnAIMnTo analyse the effects of two different manipulations of bile acid circulation on non-alcoholic fatty liver disease.nnnMETHODSnTwo animal models of non-alcoholic fatty liver disease were developed by either feeding rats with a choline deficient or with a high fat diet. After 4 weeks, rats were randomized to undergo either bile duct ligation, sham operation or cholic acid administration.nnnRESULTSnDuring cholestasis there was an increased CYP7A1 expression, the rate limiting enzyme in bile acid synthesis, and a reduction of hepatic concentration of oxysterols, ligands of the liver X receptors. Target genes of the liver X receptors, involved in fatty acid and triglyceride synthesis, were down-regulated in association with decreased hepatic triglyceride content and improvement of fatty liver. Administration of cholic acid, ligand of farnesoid X receptor, also had a beneficial effect on fatty liver in rats on choline deficient diet.nnnCONCLUSIONnThese results indicate that pharmacological approaches increasing the expression of CYP7A1 or stimulating farnesoid X receptor pathway could represent a promising treatment for non-alcoholic fatty liver disease.

Long-Term Bone Density Evaluation in Cerebrotendinous Xanthomatosis: Evidence of Improvement after Chenodeoxycholic Acid Treatment

Cerebrotendinous xanthomatosis (CTX) is known to be associated with osteoporosis and a higher incidence of bone fractures. However, the underlying pathogenesis is still unknown, and the effects of long-term replacement therapy with chenodeoxycholic acid (CDCA) on bone mineral density (BMD) have not been fully investigated. We studied 11 CTX patients aged 13–43xa0years. We performed dual-energy X-ray absorptiometry and assessed serum cholestanol and 25-hydroxyvitamin D (25-OHD) concentrations both at the time of diagnosis and after long-term treatment with CDCA. At baseline, we found low BMD in nine patients, cholestanol elevation in all subjects, and 25-OHD decrease in nine. After a mean follow-up time of 30xa0months (range 24–36), no substantial clinical changes including bone fractures occurred; and we detected a significant increase of both planar and volumetric BMD as well as normalization of plasma cholestanol levels and increase of serum 25-OHD. Densitometric improvement following CDCA introduction was not correlated to changes of biochemical parameters. Our study confirms the presence of low bone mass in CTX and demonstrates that long-term CDCA treatment increases bone mineral content. In this respect, improvement of vitamin D intestinal absorption secondary to bile acid restoration could play an important role. Moreover, our data strongly suggest the utility of periodic bone density evaluation in CTX patients.

Correlation between plasma levels of 7alpha-hydroxy-4-cholesten-3-one and cholesterol 7alpha-hydroxylation rates in vivo in hyperlipidemic patients.

BACKGROUND/AIMnHepatic bile acid synthesis is the main mechanism whereby the organism can degrade cholesterol. Plasma levels of 7alpha-hydroxy-4-cholesten-3-one have been reported to reflect bile acid synthesis and the expression or activity of the limiting enzyme of the main biosynthetic pathway, cholesterol 7alpha-hydroxylase. Aim of this study was to correlate the levels of this metabolite with the rates of cholesterol 7alpha-hydroxylation in vivo, a direct measurement of bile acid synthesis, in hyperlipidemic patients.nnnDESIGNnConcentrations of 7alpha-hydroxy-4-cholesten-3-one were assayed by gas-liquid chromatography: mass spectrometry in plasma samples obtained in 18 patients with primary hyperlipoproteinemia who previously underwent determination of cholesterol 7alpha-hydroxylation rates in vivo by tritium release analysis. Both determinations were performed in basal conditions and after treatment with hypolipidemic drugs (the fibric acid derivatives gemfibrozil and bezafibrate, cholestyramine alone or associated with simvastatin).nnnRESULTSnChanges in plasma 7alpha-hydroxy-4-cholesten-3-one profile closely reflected in vivo cholesterol 7alpha-hydroxylation rates during treatment with fibrates, cholestyramine and cholestyramine plus simvastatin. When plotting determinations from all studies (n=40), a very strict correlation was disclosed between plasma 7alpha-hydroxy-4-cholesten-3-one and cholesterol 7alpha-hydroxylation rates (r=0.81, P<0.001).nnnCONCLUSIONSnPlasma 7alpha-hydroxy-4-cholesten-3-one closely mirrors measurements of cholesterol 7alpha-hydroxylation rates in vivo in hyperlipidemic subjects and therefore stands as a reliable marker of global bile acid synthesis. In view of the correlation observed, these data may help to interpret changes of plasma levels of this metabolite in terms of cholesterol balance quantification.

Parkinsonism as neurological presentation of late-onset cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is an inherited multisystem lipid storage disease due to mutations of CYP27A1 gene resulting in sterol-27-hydroxylase enzyme deficiency and increased concentration of plasma and tissue cholestanol. The phenotype is characterized by bilateral cataract and diarrhea in infancy, whereas tendon xanthomas, osteoporosis and neurological involvement including behavioural and cognitive impairment, spastic paraparesis and cerebellar ataxia usually present in early adulthood [1]. Signal abnormalities of the dentate nuclei on magnetic resonance imaging (MRI) of the brain are considered a characteristic feature of the disease [2]. Replacement therapy with chenodeoxycholic acid (CDCA) suppresses abnormal bile acid synthesis and stabilizes clinical and laboratory parameters. Parkinsonism has been described in a few CTX cases. In these subjects, extrapyramidal signs were invariably associated with other neurological manifestations such as limb spasticity, cerebellar ataxia, neurobehavioral changes and epilepsy [3]. Here we report a patient with parkinsonism as the only neurological manifestation of CTX, presenting during the seventh decade of life. A 67 year-old Italian female patient was recently referred to our Unit for a five-year history of bradykinesia, gait unsteadiness and resting tremor, associated with mild cognitive impairment and depression. Long-term treatment with high-dose oral levodopa (600 mg/day for six months) had failed to improve clinical manifestations. Family history was unremarkable. She had worked as an employee up to the age of retirement. Severe osteoporosis and multiple bone fractureswere reported over the last tenyears. Moreover, small sized Achilles tendon xanthomas were observed since her fifties. Otherwise, clinical history was unremarkable. On admission, neurological examination showed mild bradykinesia, slight hypomimia, monotone speech, asymmetric resting tremor of hand and foot (right> left) with moderate amplitude and low frequency (5–7 Hz), resting tremor of the head with mild amplitude and low frequency (3–5 Hz), moderate impairment of hand movements andfinger taps (right> left). Unified Parkinson’s disease rating scale (UPDRS)motorexamination (part III) scorewas27.Minimental state examination (MMSE) score was 24/30. No visual impairment was reported. However, ophthalmological evaluation uncovered initial cataract bilaterally. Serum cholestanol level (0.618 mg/dl) was slightly higher than normal (0.337 0.155 mg/dl). Brain MRI revealed the presence of diffuse white matter lesions, cortical and cerebellar atrophy, and signal abnormalities of the substantia nigra bilaterally (Fig. 1). MR signal of the dentate nuclei was normal (Fig. 1). Single photon emission computed tomography (SPECT) of

Cerebrotendinous xanthomatosis with progressive cerebellar vacuolation

Dear Sir, Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid storage disease with deposition of cholestanol in many tissues causing both systemic and neurological involvement. CTX is due to mutations in the CYP27A1 gene leading to defective activity of sterol 27-hydroxylase. Therapy with chenodeoxycholic acid (CDCA) normalizes bile acids synthesis and prevents clinical deterioration. Brain magnetic resonance imaging (MRI) typically includes dentate nuclei hyperintensities on T2-weighted and FLAIR sequences, and has been reported to be substantially stable after treatment with CDCA [1, 2]. We report on a 33-year-old woman with gait unsteadiness since the age of 30 years. Her history revealed mental retardation, diarrhea and cataracts. Clinical examination disclosed dysarthria and ataxia. Tendon xanthomas were absent. Biochemical analysis revealed elevated plasma levels of cholestanol and 7α-hydroxy-4-cholesten-3-one, and decreased 27-hydroxycholesterol (27OHC) concentration. CYP27A1 gene analysis uncovered the 752C>A homozygous mutation. Therapy with CDCA was started and the patient periodically re-evaluated. Tendon xanthomas never emerged, and diarrhea disappeared. By contrast, ataxia worsened over time (Fig. 1a). A sharp reduction of cholestanol and 7α-hydroxy-4-cholesten-3-one serum levels was found (Fig. 1b, c), while 27OHC still showed very low concentrations without substantial changes from baseline. Brain MRI at 1.5 T was performed every 2 years until the age of 39 years together with clinical and biochemical follow-up. At baseline, T2-weighted and FLAIR hyperintensities in the dentate nuclei and surrounding white matter (WM) were evident. Areas of hypointensity on both T1-weighted and FLAIR images were found within cerebellar lesions. Computed tomography, and susceptibility weighted and T2*-weighted MRI ruled out the presence of calcifications. Six-year MRI follow-up showed on FLAIR images increase of the hypointense areas, which replaced hyperintensities suggesting vacuolation (Fig. 1d). MR spectroscopy (MRS) on the cerebellar hemispheres (Fig. 2) revealed the following: i) diffuse decrease of N-acetylaspartate (NAA)/creatine (Cr)01.58 (n.v. 2.27±0.29) and choline (Cho)/Cr00.53 (n.v. 0.78±0.04), and increased myoinositol (mI)/Cr ratio, mI/Cr00.43 (n.v. 0.27±0.03) in normal appearing areas; ii) lactate (Lac) and lipids (Lip) peaks in the voxels of the FLAIRhyperintense areas surrounding the FLAIR-hypointense lesions; and iii) very high Lac and Lip peaks and marked NAA/Cr decrease in the FLAIR-hypointense lesions. The serial evaluation of clinical, biochemical and MRI findings in this patient revealed that CDCA therapy was effective in decreasing serum levels of bile acids intermediates and stabilizing systemic manifestations, but failed to prevent worsening of neurological disturbances and brain lesions. The lack of correspondence between neurological and biochemical data is a crucial point, which remains open to a wide range of interpretations. A. Mignarri :M. T. Dotti (*) :G. N. Gallus :A. Giorgio Department of Neurological and Behavioural Sciences, University of Siena, Viale Bracci 2, 53100 Siena, Italy e-mail: dotti@unisi.it

Influence of breast- and formula-feeding on plasma cholesterol precursor sterols throughout the first year of life☆☆☆★★★

We evaluated endogenous cholesterol synthesis and plasma lipid profile longitudinally from birth to 1 year old in infants who were exclusively breast-fed (n = 19) or formula-fed (n = 19) for the first 4 months of life. At 1 and 4 months of age, breast-fed infants had higher plasma total and low-density lipoprotein cholesterol and apolipoprotein B levels than formula-fed infants, whereas plasma mevalonate and lanosterol levels were not different between the two study groups.