Valerio Leoni

Publications (35) View all

• Article: Diagnostic Power of 24S-Hydroxycholesterol in Cerebrospinal Fluid: Candidate Marker of Brain Health.

  Valerio Leoni, Alina Solomon, Anita Lövgren-Sandblom, Lennart Minthon, Kaj Blennow, Oskar Hansson, Lars-Olof Wahlund, Miia Kivipelto, Ingemar Björkhem
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  ABSTRACT: We evaluated the diagnostic potential of 24S-hydroxycholesterol (24OHC) in cerebrospinal fluid. At a memory clinic, we investigated subjects with subjective cognitive impairment (SCI, n = 33), mild cognitive impairment (MCI) patients (n = 27), MCI patients with later progression into Alzheimer dementia at follow up (n = 10), and patients with AD (n = 24). We also had a control group of healthy volunteers who did not later develop cognitive problems (n = 13). The fraction of the population with pathological levels of 24OHC was 8% in controls, 34% in SCI, 37% in MCI, 80% in MCI with progression, and 42% in AD. The corresponding fractions for T-tau, P-tau, and Aβ42 were lower in the case of SCI and MCI but higher in the case of controls and AD. In case of MCI with progression, the fraction of pathological levels of 24OHC and Aβ42 were 80% and 63% respectively. We also studied a population of old healthy subjects age 75-99 years (n = 25). The fraction of individuals in this population with pathological levels of 24OHC was 0% whereas the fraction of individuals with pathological level of at least one of the other three biomarkers was 40%. The diagnostic power of 24OHC in cerebrospinal fluid seems to be similar to or lower than that of the established biomarkers T-tau, P-tau, and Aβ42 in the diagnosis of established AD. Our data suggest that 24OHC may be more sensitive than the classical biomarkers in an early phase of the neurodegenerative process and a better marker for "brain health" in old age.
  Journal of Alzheimer's disease: JAD 05/2013; · 3.74 Impact Factor
• Article: Cardioprotection by the TSPO ligand 4'-chlorodiazepam is associated with inhibition of mitochondrial accumulation of cholesterol at reperfusion.

  Stéphanie Paradis, Valerio Leoni, Claudio Caccia, Alain Berdeaux, Didier Morin
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  ABSTRACT: AIMS: The translocator protein(TSPO) is located on the outer mitochondrial membrane where it is responsible for the uptake of cholesterol into mitochondria of steroidogenic organs. TSPO is also present in the heart where its role remains uncertain. We recently showed that TSPO ligands reduced infarct size and improved mitochondrial functions after ischemia-reperfusion. This study thus sought to determine whether cholesterol could play a role in the cardioprotective effect of TSPO ligands.Methods and ResultsIn a model of 30&emsp14;min coronary occlusion/15&emsp14;min reperfusion in Wistar rat, we showed that reperfusion induced lipid peroxidation as demonstrated by the increase in conjugated diene and thiobarbituric acid reactive substance formation and altered mitochondrial function (decrease in oxidative phosphorylation and increase in the sensitivity of mitochondrial permeability transition pore opening) in ex-vivo isolated mitochondria. This was associated with an increase in mitochondrial cholesterol uptake (89.5±12.2 vs 39.9±3.51 nmoles/mg protein in controls, p<0.01) and a subsequent strong generation of auto-oxidized oxysterols, i.e. 7α- and 7β-hydroxycholesterol, 7-ketocholesterol, cholesterol-5α,6α-epoxide and 5β,6β-epoxide (+173%, +149%, +165%, +165% and +193% vs controls, respectively; p<0.01). Administration of the selective TSPO ligand 4'-chlorodiazepam inhibited oxidative stress, improved mitochondrial function, and abolished both mitochondrial cholesterol accumulation and oxysterol production. This was also observed with the new TSPO ligand TRO40303. CONCLUSIONS: These data suggest that 4'-chlorodiazepam inhibits oxidative stress and oxysterol formation by reducing the accumulation of cholesterol in the mitochondrial matrix at reperfusion and prevents mitochondrial injury. This new and original mechanism may contribute to the cardioprotective properties of TSPO ligands.
  Cardiovascular research 04/2013; · 5.80 Impact Factor
• Article: Plasma 24S-hydroxycholesterol correlation with markers of Huntington disease progression.

  Valerio Leoni, Jeffrey D Long, James A Mills, Stefano Di Donato, Jane S Paulsen
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  ABSTRACT: 24S-hydroxycholesterol (24OHC) is involved in the conversion of excess cholesterol in the brain, and its level in plasma is related to the number of metabolically active neuronal cells. Previous research suggests that plasma 24OHC is substantially reduced in the presence of neurodegenerative disease. Huntington disease (HD) is an inherited autosomal dominant neurodegenerative disorder caused by a cytosine-adenine-guanine (CAG) triplet repeat expansion in the coding region of the huntingtin (HTT) gene. The current study focused on the relative importance of 24OHC as a marker of HD progression. Using mass spectrometry methods, plasma 24OHC levels were examined in three groups of gene-expanded individuals (Low, Medium, High) characterized by their progression at entry into the parent PREDICT-HD study, along with a group of non-gene-expanded controls (total N=150). In addition, the correlation of 24OHC with a number of motor, cognitive, and imagining markers was examined, and effect sizes for group differences among the markers were computed for comparison with 24OHC. Results show a progression gradient as 24OHC levels decreased as the progression group increased (Low to High). The effect size of group differences for 24OHC was larger than all the other variables, except striatal volume. 24OHC was significantly correlated with many of the other key variables. The results are interpreted in terms of cholesterol synthesis and neuronal degeneration. This study provides evidence that 24OHC is a relatively important marker of HD progression.
  Neurobiology of Disease 04/2013; · 5.40 Impact Factor
• Article: Potential diagnostic applications of side chain oxysterols analysis in plasma and cerebrospinal fluid.

  Valerio Leoni, Claudio Caccia
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  ABSTRACT: The neurospecific cholesterol 24-hydroxylase converts excess brain cholesterol into 24S-hydroxycholesterol (24OHC) which, via the liver X receptor (LXR), can increase the expression and synthesis of astrocyte ApoE. 24OHC effluxes directly from brain into plasma where it is considered an indicator of brain cholesterol turnover. It is reduced in neurodegenerative disease states proportionally to the severity of disease and the degree of brain atrophy. In the early phases of active disease, a higher rate of turnover may result in transitory increases in plasma 24OHC. Less than 1% of the total brain excretion of 24OHC occurs via the cerebrospinal fluid (CSF) whereas almost all 27-hydroxycholesterol (27OHC) excretion is dependent on the function of the blood-cerebrospinal fluid barrier. Iincreased CSF oxysterols were found in patients with neurodegenerative and neuroinflammatory diseases in the presence of barrier dysfunction. In neurodegeneration, free cholesterol released from dying cells may engulf neurons. Cholesterol also increases Amyloid β (Aβ) deposition and tau pathology. ApoE, 24OHC, tau and soluble APP were correlated in Alzheimer disease (AD) samples. Excess of cholesterol converted into 24OHC may up-regulate ApoE synthesis which is a scavenger for Aβ and Tau. In AD this protective mechanism seems to be inefficient, probably due to the presence of high concentrations of 27OHC, microvascular dysfunction and the decreased efficiency of ApoE4 as lipid transporter and Aβ scavenger. 24OHC itself was cytotoxic. Analysis of side chain oxysterols in the CSF is likely to provided useful information about cholesterol metabolism and ApoE function in the pathogenesis of AD.
  Biochemical pharmacology 03/2013; · 4.25 Impact Factor
• Article: Differences in brain cholesterol metabolism and insulin in two subgroups of patients with different CSF biomarkers but similar white matter lesions suggest different pathogenic mechanisms.

  A Besga, A Cedazo-Minguez, I Kåreholt, A Solomon, I Björkhem, B Winblad, V Leoni, B Hooshmand, G Spulber, A Gonzalez-Pinto, M Kivipelto, L O Wahlund
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  ABSTRACT: Investigate possible associations of white matter hyperintensities (WMHs) with the metabolism of cholesterol and insulin in two subgroups of patients with memory complaints and different CSF Aβ42 and CSF tau levels. 59 patients from the memory clinic at Karolinska Hospital were included. Degree of WMHs was rated using the ARWMC scale and the following biomarkers were measured in CSF and plasma: insulin, cholesterol, lanosterol, lathosterol, and oxidized cholesterol metabolites. The WMHs in CSF control-like group correlated with increased brain cholesterol synthesis and reduced efflux of oxysterols and insulin in CSF. In the CSF AD-like group, the WMHs correlated with increased peripheral cholesterol metabolism. Despite having similar appearance on FLAIR images, the pathogenic mechanisms of WMHS are likely to be different in the two groups investigated.
  Neuroscience Letters 02/2012; 510(2):121-6. · 2.11 Impact Factor