BACKGROUND- Alterations of cholesterol homeostasis in the central nervous system (CNS) have been associated to various neurodegenerative disorders, including Alzheimer's disease (AD). Cholesterol transport in the CNS is mediated by lipoproteins similar to plasma HDL, mainly containing apolipoprotein E, and undergoing biogenesis and maturation processes similar to that observed in plasma. Few published data, and preliminary results from the proponents, suggest that lipoprotein biogenesis, maturation, and cholesterol transport capacity might be altered in AD. No successful therapies are available to halt or reverse AD, thus the search for innovative therapeutic approaches is an urgent need.
OBJECTIVE AND SPECIFIC AIMS- The overall objective of AGAINST-AD is to investigate the relationship between brain cholesterol transport and the cognitive decline. We aim to test the hypothesis that the HDL-like particles detected in the cerebrospinal fluid (CFS) are altered in AD patients in terms of structure, composition, and function, and that such alterations may be detected since the early phases of the disease, representing helpful predictors of AD progression and new potential pharmacological targets. The overall goal will be pursued by an integration of ex vivo, in vitro, and in vivo evaluations.
In the main part of the study, AD patients will be stratified according to disease severity (mild, moderate and severe AD, according to CDR and MMSE), and mild cognitive impairment (MCI) patients with positive neurobiomarkers will be recruited as well. A cognitively-intact control group will be also recruited from patients undergoing to knee replacement surgery without history of neurological or psychiatric disorders and MMSE score >26.
The project is structured in three work packages (WP), each with specific aims: WP1. characterization of CSF and serum – by evaluating lipoprotein remodeling, cholesterol efflux capacity, and cholesterol esterification– of AD patients at different stages of the disease, to test the hypothesis that brain cholesterol transport is altered in AD. In parallel, serum HDL from the same patients will be characterized. The results obtained in CSF will be compared with those obtained in serum to point out possible correlations, in the search of less invasive and expensive blood-based biomarkers. Additional analyses will include the apoE phenotype, CSF/serum levels of PCSK9 and of the two oxysterols crossing the blood-brain barrier (BBB) 24-OH- and 27-OH-cholesterol. WP2. In vitro experiments with cellular models of neurons and astrocytes and with patient fibroblasts to test the hypothesis that the defect of cholesterol transport may also occur at cellular level. In these models it will be evaluated: the expression of receptors/transporters involved in cerebral cholesterol transport, cholesterol metabolism parameters, and Aß production. WP3. Animal experiments designed to test the hypothesis that the modulation of CNS lipoprotein-mediated cholesterol transport could be a valuable strategy in the treatment of AD. This aim will be pursued with two pharmacological approaches: small molecules modulator of LCAT, the enzyme responsible for lipoprotein maturation, and infusion of synthetic HDL.
ANTICIPATED OUTPUT - The information collected within the present project will (i) clarify the relation between CSF lipoprotein structure/function and cognitive decline, aimed at the identification of potential biomarkers of AD progression; (ii) define whether defects in brain cholesterol receptors/transporters contribute to the alteration of cholesterol transport in AD, and (iii) set the basis for the identification of novel therapeutic approaches.
FEASIBILITY - The AGAINST-AD project will be carried out by 3 Italian Research Units (RUs) and will be developed over a period of 36 months. The success of AGAINST-AD will be warranted by the strict collaboration among the involved investigators, that will take care of the proposed WPs in an integrated manner. A multidisciplinary team has been created on the basis of scientific excellence and willingness to collaborate. The team is ideally suited to investigate the various aspects of the HDL-mediated brain cholesterol transport and its association with AD in a complimentary and synergistic manner. The integration between the imperative availability of clinical parameters and biological human samples, the expertise on the structural and functional HDL evaluation, on cell cholesterol metabolism, on brain cell biology through in vitro and in vivo approaches, and the consolidated statistical and clinical data management expertise, will allow to perform for the first time a study aimed at identifying new parameters possibly associated with the risk of AD and new potential therapeutic targets.
OBJECTIVE AND SPECIFIC AIMS- The overall objective of AGAINST-AD is to investigate the relationship between brain cholesterol transport and the cognitive decline. We aim to test the hypothesis that the HDL-like particles detected in the cerebrospinal fluid (CFS) are altered in AD patients in terms of structure, composition, and function, and that such alterations may be detected since the early phases of the disease, representing helpful predictors of AD progression and new potential pharmacological targets. The overall goal will be pursued by an integration of ex vivo, in vitro, and in vivo evaluations.
In the main part of the study, AD patients will be stratified according to disease severity (mild, moderate and severe AD, according to CDR and MMSE), and mild cognitive impairment (MCI) patients with positive neurobiomarkers will be recruited as well. A cognitively-intact control group will be also recruited from patients undergoing to knee replacement surgery without history of neurological or psychiatric disorders and MMSE score >26.
The project is structured in three work packages (WP), each with specific aims: WP1. characterization of CSF and serum – by evaluating lipoprotein remodeling, cholesterol efflux capacity, and cholesterol esterification– of AD patients at different stages of the disease, to test the hypothesis that brain cholesterol transport is altered in AD. In parallel, serum HDL from the same patients will be characterized. The results obtained in CSF will be compared with those obtained in serum to point out possible correlations, in the search of less invasive and expensive blood-based biomarkers. Additional analyses will include the apoE phenotype, CSF/serum levels of PCSK9 and of the two oxysterols crossing the blood-brain barrier (BBB) 24-OH- and 27-OH-cholesterol. WP2. In vitro experiments with cellular models of neurons and astrocytes and with patient fibroblasts to test the hypothesis that the defect of cholesterol transport may also occur at cellular level. In these models it will be evaluated: the expression of receptors/transporters involved in cerebral cholesterol transport, cholesterol metabolism parameters, and Aß production. WP3. Animal experiments designed to test the hypothesis that the modulation of CNS lipoprotein-mediated cholesterol transport could be a valuable strategy in the treatment of AD. This aim will be pursued with two pharmacological approaches: small molecules modulator of LCAT, the enzyme responsible for lipoprotein maturation, and infusion of synthetic HDL.
ANTICIPATED OUTPUT - The information collected within the present project will (i) clarify the relation between CSF lipoprotein structure/function and cognitive decline, aimed at the identification of potential biomarkers of AD progression; (ii) define whether defects in brain cholesterol receptors/transporters contribute to the alteration of cholesterol transport in AD, and (iii) set the basis for the identification of novel therapeutic approaches.
FEASIBILITY - The AGAINST-AD project will be carried out by 3 Italian Research Units (RUs) and will be developed over a period of 36 months. The success of AGAINST-AD will be warranted by the strict collaboration among the involved investigators, that will take care of the proposed WPs in an integrated manner. A multidisciplinary team has been created on the basis of scientific excellence and willingness to collaborate. The team is ideally suited to investigate the various aspects of the HDL-mediated brain cholesterol transport and its association with AD in a complimentary and synergistic manner. The integration between the imperative availability of clinical parameters and biological human samples, the expertise on the structural and functional HDL evaluation, on cell cholesterol metabolism, on brain cell biology through in vitro and in vivo approaches, and the consolidated statistical and clinical data management expertise, will allow to perform for the first time a study aimed at identifying new parameters possibly associated with the risk of AD and new potential therapeutic targets.