BIOMARKERS OF BLOOD-BRAIN BARRIER DYSFUNCTION

Abstract

A method for determining whether a subject has an impaired blood-brain barrier (BBB) or is at risk of developing an impaired blood-brain barrier (BBB) comprising determining the level of one or more biomarkers in one or more samples obtained from the subject, wherein the one or more biomarkers comprise serum amyloid A (SAA).

Claims

1. A method for determining whether a subject has an impaired blood-brain barrier (BBB) or is at risk of developing an impaired blood-brain barrier (BBB) comprising determining the level of one or more biomarkers in one or more samples obtained from the subject, wherein the one or more biomarkers comprise serum amyloid A (SAA).

2. A method for determining whether a subject is at risk of developing a cognitive impairment comprising determining the level of one or more biomarkers in one or more samples obtained from the subject, wherein the one or more biomarkers comprise serum amyloid A (SAA).

3. The method of claim 2, wherein the cognitive impairment is selected from the group consisting of Alzheimer's disease, vascular cognitive impairment and vascular dementia, Parkinson's disease, age-related cognitive decline and traumatic brain injury.

4. The method of claim 1, wherein the SAA is selected from the group consisting of SAA1, SAA2 and SAA4.

5. The method of claim 1, wherein the method further comprises determining the level of macrophage-derived chemokine (MDC) in a sample from the subject.

6. The method of claim 1, wherein the method further comprises determining the level of one or more biomarkers selected from the group consisting of soluble inter-cellular adhesion molecule-1 (sICAM-1), vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8), in one or more samples obtained from the subject.

7. The method of claim 1, wherein the method comprises determining the level of SAA, MDC, sICAM-1, VEGF and IL-8 in one or more samples obtained from the subject.

8. The method of claim 1, wherein the method comprises determining a blood-brain barrier (BBB) impairment score (S) using the formula:
S=A+B(IL-8)+C(MDC)+D(SAA)+E(sICAM-1)+F(VEGF)+G(Gender) wherein A, B, C, D, E, F and G are coefficients.

9. The method of claim 1, wherein the levels of SAA, MDC, sICAM-1, VEGF and/or IL-8 are determined in one or more cerebrospinal fluid and/or serum samples.

10. The method of claim 1, wherein the subject is a human over the age of 55 years old.

11. A method of treating or preventing blood-brain barrier (BBB) impairment comprising the steps: (a) determining whether a subject has an impaired blood-brain barrier (BBB) or is at risk of developing an impaired blood-brain barrier (BBB) comprising determining the level of one or more biomarkers in one or more samples obtained from the subject, wherein the one or more biomarkers comprise serum amyloid A (SAA); and (b) applying an intervention capable of improving blood-brain barrier (BBB) function to a subject identified to be in need thereof.

12. (canceled)

13. The method of claim 11, wherein the intervention is a dietary intervention.

14. The method of claim 13, wherein the dietary intervention comprises increasing vitamin B intake by the subject.

15. The method of claim 13, wherein the dietary intervention comprises increasing omega-3 fatty acid intake by the subject.

16. The method of claim 2, wherein the SAA is selected from the group consisting of SAA1, SAA2 and SAA4.

17. The method of claim 2, wherein the method further comprises determining the level of macrophage-derived chemokine (MDC) in a sample from the subject.

18. The method of claim 2, wherein the method further comprises determining the level of one or more biomarkers selected from the group consisting of soluble inter-cellular adhesion molecule-1 (sICAM-1), vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8), in one or more samples obtained from the subject.

19. The method of claim 2, wherein the method comprises determining the level of SAA, MDC, sICAM-1, VEGF and IL-8 in one or more samples obtained from the subject.

20. The method of claim 2, wherein the method comprises determining a blood-brain barrier (BBB) impairment score (S) using the formula:
S=A+B(IL-8)+C(MDC)+D(SAA)+E(sICAM-1)+F(VEGF)+G(Gender) wherein A, B, C, D, E, F and G are coefficients.

21. The method of claim 2, wherein the levels of SAA, MDC, sICAM-1, VEGF and/or IL-8 are determined in one or more cerebrospinal fluid and/or serum samples.

Description

DESCRIPTION OF THE DRAWINGS

[0078] FIG. 1

[0079] Cerebrospinal fluid (CSF) inflammatory signature of blood-brain barrier (BBB) impairment in older adults. Receiver operating characteristic (ROC) curves for diagnosis of blood-brain barrier (BBB) impairment for Reference (labelled REF ref) and Best models (labelled neuro). For the Reference model the area under the curve (AUC) is 0.80 whereas for the Best model the area under the curve (AUC) is 0.95. The variables selected in the Best model are: Gender and 5 CSF biomarkers (IL-8, sICAM-1, VEGF, SAA, and MDC).

[0080] FIG. 2

[0081] Correlation in the concentrations of serum amyloid A (SAA) measured both in CSF and serum in the cohort under study. Concentrations (in pg/mL) are log-transformed. R is 0.7083, R2 is 0.5017 and p<1 e-5.

DETAILED DESCRIPTION OF THE INVENTION

[0082] Various preferred features and embodiments of the present invention will now be described by way of non-limiting examples.

[0083] The practice of the present invention will employ, unless otherwise indicated, conventional techniques of chemistry, biochemistry, molecular biology, microbiology and immunology, which are within the capabilities of a person of ordinary skill in the art. Such techniques are explained in the literature. See, for example, Sambrook, J., Fritsch, E. F. and Maniatis, T. (1989) Molecular Cloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor Laboratory Press; Ausubel, F. M. et al. (1995 and periodic supplements) Current Protocols in Molecular Biology, Ch. 9, 13 and 16, John Wiley & Sons; Roe, B., Crabtree, J. and Kahn, A. (1996) DNA Isolation and Sequencing: Essential Techniques, John Wiley & Sons; Polak, J. M. and McGee, J. O'D. (1990) In Situ Hybridization: Principles and Practice, Oxford University Press; Gait, M. J. (1984) Oligonucleotide Synthesis: A Practical Approach, IRL Press; and Lilley, D. M. and Dahlberg, J. E. (1992) Methods in Enzymology: DNA Structures Part A: Synthesis and Physical Analysis of DNA, Academic Press. Each of these general texts is herein incorporated by reference.

[0084] Blood-Brain Barrier (BBB)

[0085] The blood-brain barrier (BBB) is a selective barrier that separates circulating blood from the brain. The BBB is comprised of a monolayer of endothelial cells bonded by tight junction proteins that form the small cerebral blood vessel lumen. In addition, astrocytes (in particular, projections from those cells termed astrocytic feet) and pericytes contribute to the structure and function of the BBB.

[0086] The BBB governs entry of all peripherally circulating factors such as water diffusion, some gases and lipid-soluble molecules, and selective transport of other substances, such as glucose, amino acids, and micronutrients that are crucial to neuronal function. Conversely, the BBB protects the brain from the passage of toxic substances that may place the central nervous system (CNS) at risk.

[0087] The term impaired blood-brain barrier (BBB) refers to a BBB that is not functioning correctly as a selective barrier between circulation and the brain. As used herein, the term impaired blood-brain barrier (BBB) may be equated with dysfunctional blood-brain barrier (BBB).

[0088] One example, is the case where certain larger proteins that are more abundant in circulation begin to penetrate the BBB (leak) and infiltrate the cerebrospinal fluid (CSF) would be a case of impaired BBB.

[0089] An impaired BBB may occur, for example, in a subject having a higher than normal CSF-to-serum albumin ratio, for example a CSF-to-serum albumin ratio greater than or equal to 5, 6, 7, 8, or 9, preferably greater than or equal to 9.

[0090] Cognitive Impairment

[0091] A number of studies have observed BBB dysfunction with all forms of dementia, including Alzheimer's disease. For example, post-mortem analyses have demonstrated BBB damage in Alzheimer's disease patients. In addition, neuroimaging studies have shown the accumulation of iron and microbleeds in Alzheimer's disease patients, which suggests subtle haemorrhage or rupture of small vessels in the brain at some point across the lifespan. Further studies have shown that cerebrospinal fluid (CSF)-to-serum ratios of blood-derived albumin are higher in all dementia patients (including those suffering from Alzheimer's disease) when compared against age-matched controls. Indeed, this measure of BBB function associates with accelerated Alzheimer's disease progression independent of age and other Alzheimer's disease risk factors.

[0092] BBB dysfunction therefore appears to be a significant risk factor for the development of cognitive impairments, such as Alzheimer's disease, and their progression.

[0093] The term cognition refers to the set of mental thinking abilities and domains of attention and processing speed, short and long term memory, working memory, executive functions of planning and flexibility, decision making, judgment and evaluation, reasoning and computation, problem solving, comprehension and language. Cognitive impairment refers to a deterioration in one or more these domains of cognition.

[0094] Levels of and improvements in cognition can be readily assessed by the skilled person using any of a number of validated neuropsychological tests standardized to assess, for example, speed of information processing, executive function and memory.

[0095] Suitable example tests include Mini Mental State Examination (MMSE), Clinical Dementia Rating (CDR), Cambridge Neuropsychological Test Automated Battery (CANTAB), Alzheimer's Disease Assessment Scale-cognitive test (ADAScog), Wisconsin Card Sorting Test, Verbal and Figural Fluency Test and Trail Making Test.

[0096] In addition, medical imaging of the brain provides an assessment of brain function. Examples of medical imaging techniques used for assessment of brain function include electroencephalography (EEG), magnetoencephalography (MEG), Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), Magnetic Resonance Imaging (MRI), functional Magnetic Resonance Imaging (fMRI), computerised tomography and long-term potentiation. Dynamic gadolinium enhanced MRI can also be used to assess blood brain barrier (BBB) function.

[0097] EEG, a measure of electrical activity of the brain, is accomplished by placing electrodes on the scalp at various landmarks and recording greatly amplified brain signals. MEG is similar to EEG in that it measures the magnetic fields that are linked to electrical fields. MEG is used to measure spontaneous brain activity, including synchronous waves in the nervous system.

[0098] PET provides a measure of oxygen utilisation and glucose metabolism. In this technique, a radioactive positron-emitting tracer is administered, and tracer uptake by the brain is correlated with brain activity. These tracers emit gamma rays which are detected by sensors surrounding the head, resulting in a 3D map of brain activation. As soon as the tracer is taken up by the brain, the detected radioactivity occurs as a function of regional cerebral blood flow. During activation, an increase in cerebral blood flow and neuronal glucose metabolism can be detected within seconds.

[0099] Suitable analysis can also be based on neuropsychological testing, general and neurological examinations and individual complaints of cognitive decline (e.g. subjective memory loss).

[0100] Cognitive impairment may be, for example, interpreted as a statistically significant difference in performance at any time point in a suitable test.

[0101] Alzheimer's Disease (AD)

[0102] Alzheimer's disease is caused by atrophy of areas of the brain. Although it is not known what initiates the atrophy, studies have found amyloid plaques, neurofibrillary tangles and acetylcholine imbalances in the brains of Alzheimer's patients. Vascular damage in the brain, which may damage healthy neurons, is also common in Alzheimer's patients.

[0103] Alzheimer's disease is a progressive condition that affects multiple brain functions. Early signs of the disease usually include minor memory problems, for example forgetting recent events or the names of places and objects. As the disease progresses, memory problems become more severe and additional symptoms can develop, such as confusion, disorientation, difficulty making decisions, problems with speech and language, and personality changes.

[0104] Vascular Dementia

[0105] Vascular dementia results from reduced blood flow to the brain, which damages brain cells. The reduced blood flow can occur for a number of reasons, including narrowing of the blood vessels in the brain (subcortical vascular dementia), stroke (single-infarct dementia) and numerous small strokes (multi-infarct dementia). The reduced blood flow may additionally be caused by Alzheimer's disease, a combination referred to as mixed dementia.

[0106] Early symptoms of vascular dementia include slowness of thought, difficulty with planning, difficulty with language, problems with attention and concentration, and behavioural changes. The symptoms typically worsen in steps, with intervening stable periods of months or years.

[0107] Parkinson's Disease (PD)

[0108] Parkinson's disease is a condition in which nerve cells in the substantia nigra become progressively damaged. Nerve cells in this area of the brain produce dopamine, which acts as a messenger between the parts of the brain and nervous system that control body movement. Damage to these nerve cells results in a reduction in the amount of dopamine produced in the brain, which has the effect of reducing function in the part of the brain controlling movement.

[0109] Symptoms of the Parkinson's disease include tremors, slow movement, and stiff and inflexible muscles. Parkinson's disease patients may also experience additional symptoms, including depression, constipation, insomnia, anosmia and memory problems.

[0110] Age-Related Cognitive Decline

[0111] Age-related cognitive decline is the normal, non-pathological reduction in cognitive function that is associated with ageing. Although certain mental functions exhibit little age-related decline (e.g. language, reading and vocabulary skills, some numerical abilities and general knowledge) others decline from middle age (e.g. episodic memory, executive functions, speed of processing and reasoning). The extent to which subjects are affected by age-related cognitive decline varies between individuals.

[0112] Age-related cognitive decline usually is not considered severe enough to meet criteria for mild-cognitive impairment. Mild cognitive impairment (MCI) is considered to be objective assessment of cognitive deficit in at least one cognitive domain (age and gender adjusted) that does not impair activities of daily living. In contrast, probable Alzheimer's disease diagnosis requires impairment in at least two cognitive domains and impairment of activities of daily living.

[0113] Traumatic Brain Injury (TBI)

[0114] Traumatic brain injury is a non-congenital insult to the brain from an external mechanical force, possibly leading to permanent or temporary impairment of cognitive, physical, and psychosocial functions, with an associated diminished or altered state of consciousness.

[0115] Biomarkers

[0116] Serum Amyloid A (SAA)

[0117] Serum amyloid A (SAA) proteins are apolipoproteins that are associated with high-density lipoprotein (HDL) in plasma and are mainly produced by the liver.

[0118] In one embodiment, the SAA is human SAA.

[0119] A number of isoforms of human SAA are known. In one embodiment, the SAA is SAA1, SAA2 or SAA4, preferably SAA1.

[0120] An example amino acid sequence of SAA1 is the sequence deposited under NCBI Accession No. NP_000322.2.

[0121] A further example amino acid sequence of SAA1 is:

TABLE-US-00001 (SEQIDNO:1) MKLLTGLVFCSLVLGVSSRSFFSFLGEAFDGARDMWRAYSDMREANYIGS DKYFHARGNYDAAKRGPGGVWAAEAISDARENIQRFFGHGAEDSLADQAA NEWGRSGKDPNHFRPAGLPEKY

[0122] A further example amino acid sequence of SAA1 is:

TABLE-US-00002 (SEQIDNO:2) MKLLTGLVFCSLVLGVSSRSFFSFLGEAFDGARDMWRAYSDMREANYIGS DKYFHARGNYDAAKRGPGGAWAAEVISDARENIQRFFGHGAEDSLADQAA NEWGRSGKDPNHFRPAGLPEKY

[0123] SAA1 may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of SAA1 is:

TABLE-US-00003 (SEQIDNO:3) RSFFSFLGEAFDGARDMWRAYSDMREANYIGSDKYFHARGNYDAAKRGPG GAWAAEVISDARENIQRFFGHGAEDSLADQAANEWGRSGKDPNHFRPAGL PEKY

[0124] SAA2 has two splice variants. An example amino acid sequence of SAA2 is the sequence deposited under NCBI Accession No. NP_110381.2.

[0125] A further example amino acid sequence of SAA2 is:

TABLE-US-00004 (SEQIDNO:4) MKLLTGLVFCSLVLSVSSRSFFSFLGEAFDGARDMWRAYSDMREANYI GSDKYFHARGNYDAAKRGPGGAWAAEVISNARENIQRLTGRGAEDSLA DQAANKWGRSGRDPNHFRPAGLPEKY

[0126] SAA2 may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of SAA2 is:

TABLE-US-00005 (SEQIDNO:5) RSFFSFLGEAFDGARDMWRAYSDMREANYIGSDKYFHARGNYDAAKRG PGGAWAAEVISNARENIQRLTGRGAEDSLADQAANKWGRSGRDPNHFR PAGLPEKY

[0127] A further example amino acid sequence of SAA2 is the sequence deposited under NCBI Accession No. NP 001120852.1.

[0128] A further example amino acid sequence of SAA2 is:

TABLE-US-00006 (SEQIDNO:6) MKLLTGLVFCSLVLSVSSRSFFSFLGEAFDGARDMWRAYSDMREANYI GSDKYFHARGNYDAAKRGPGGAWAAEVISLFSAEL

[0129] SAA2 may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of SAA2 is:

TABLE-US-00007 (SEQIDNO:7) RSFFSFLGEAFDGARDMWRAYSDMREANYIGSDKYFHARGNYDAAKRG PGGAWAAEVISLFSAEL

[0130] An example amino acid sequence of SAA4 is the sequence deposited under NCBI Accession No. NP_006503.2.

[0131] A further example amino acid sequence of SAA4 is:

TABLE-US-00008 (SEQIDNO:8) MRLFTGIVFCSLVMGVTSESWRSFFKEALQGVGDMGRAYWDIMISNHQ NSNRYLYARGNYDAAQRGPGGVWAAKLISRSRVYLQGLIDCYLFGNSS TVLEDSKSNEKAEEWGRSGKDPDRFRPDGLPKKY

[0132] SAA4 may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of SAA4 is:

TABLE-US-00009 (SEQIDNO:9) ESWRSFFKEALQGVGDMGRAYWDIMISNHQNSNRYLYARGNYDAAQRG PGGVWAAKLISRSRVYLQGLIDCYLFGNSSTVLEDSKSNEKAEEWGRS GKDPDRFRPDGLPKKY

[0133] Macrophage-Derived Chemokine (MDC)

[0134] The macrophage-derived chemokine (MDC) protein is secreted by dendritic cells and macrophages. MDC interacts with cell surface chemokine receptors, such as CCR4, to elicit effects on target cells and it may be involved in the trafficking of activated/effector T lymphocytes to inflammatory sites.

[0135] MDC is also known as C-C motif chemokine 22 (CCL22).

[0136] In one embodiment, the MDC is human MDC.

[0137] An example amino acid sequence of MDC is the sequence deposited under NCBI Accession No. NP_002981.2.

[0138] A further example amino acid sequence of MDC is:

TABLE-US-00010 (SEQIDNO:10) MDRLQTALLVVLVLLAVALQATEAGPYGANMEDSVCCRDYVRYRLPLR VVKHFYWTSDSCPRPGVVLLTFRDKEICADPRVPWVKMILNKLSQ

[0139] MDC may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of MDC is:

TABLE-US-00011 (SEQIDNO:11) GPYGANMEDSVCCRDYVRYRLPLRVVKHFYWTSDSCPRPGVVLLTFRD KEICADPRVPWVKMILNKLSQ

[0140] Soluble Inter-Cellular Adhesion Molecule-1 (sICAM-1)

[0141] Soluble inter-cellular adhesion molecule-1 (sICAM-1) is a member of the soluble cell adhesion molecule (sCAM) class of cell surface binding proteins. In particular, sICAM-1 is a soluble form of the iCAM-1 cell adhesion molecule.

[0142] In one embodiment, the sICAM-1 is human sICAM-1. An example of human sICAM-1 is:

TABLE-US-00012 (SEQ.IDNo.12) ESVTVTRDLEGTYLCRARSTQGEVTREPPGMRLSSSLW

[0143] Vascular Endothelial Growth Factor (VEGF)

[0144] Vascular endothelial growth factor (VEGF) is a signalling protein, which stimulates vasculogenesis and angiogenesis.

[0145] In one embodiment, the VEGF is human VEGF.

[0146] In one embodiment, the VEGF is VEGF-A, VEGF-B, VEGF-C, VEGF-D or placenta growth factor (PGF), preferably the VEGF is VEGF-A.

[0147] An example amino acid sequence of VEGF is the sequence deposited under NCBI Accession No. NP_001165094.1.

[0148] A further example amino acid sequence of VEGF is:

TABLE-US-00013 (SEQIDNO:13) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSV RGKGKGQKRKRKKSRYKSWSVYVGARCCLMPWSLPGPHPCGPCSERRK HLFVQDPQTCKCSCKNTDSRCKARQLELNERTCRCDKPRR

[0149] VEGF may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of VEGF is:

TABLE-US-00014 (SEQIDNO:14) APMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVDIFQEYPDEIEYIFK PSCVPLMRCGGCCNDEGLECVPTEESNITMQIMRIKPHQGQHIGEMSF LQHNKCECRPKKDRARQEKKSVRGKGKGQKRKRKKSRYKSWSVYVGAR CCLMPWSLPGPHPCGPCSERRKHLFVQDPQTCKCSCKNTDSRCKARQL ELNERTCRCDKPRR

[0150] Further examples of amino acid sequence VEGF-A isoform are:

TABLE-US-00015 (SEQIDNO:15) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSV RGKGKGQKRKRKKSRYKSWSVYVGARCCLMPWSLPGPHPCGPCSERRK HLFVQDPQTCKCSCKNTDSRCKARQLELNERTCRCDKPRR (SEQIDNO:16) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSV RGKGKGQKRKRKKSRYKSWSVPCGPCSERRKHLFVQDPQTCKCSCKNT DSRCKARQLELNERTCRCDKPRR (SEQIDNO:17) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSV RGKGKGQKRKRKKSRPCGPCSERRKHLFVQDPQTCKCSCKNTDSRCKA RQLELNERTCRCDKPRR (SEQIDNO:18) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCG PCSERRKHLFVQDPQTCKCSCKNTDSRCKARQLELNERTCRCDKPRR (SEQIDNO:19) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCG PCSERRKHLFVQDPQTCKCSCKNTDSRCKM (SEQIDNO:20) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSV RGKGKGQKRKRKKSRYKSWSVCDKPRR (SEQIDNO:21) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCG PCSERRKHLFVQDPQTCKCSCKNTDSRCKARQLELNERTCRSLTRKD (SEQIDNO:22) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKCDK PRR (SEQIDNO:23) MNFLLSWVHWSLALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQ RSYCHPIETLVDIFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVP TEESNITMQIMRIKPHQGQHIGEMSFLQHNKCECRCDKPRR (SEQIDNO:24) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCGPCSERRKHLFVQ DPQTCKCSCKNTDSRCKARQLELNERTCRCDKPRR (SEQIDNO:25) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKCDKPRR (SEQIDNO:26) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSVRGKGKGQKRKRK KSRYKSWSVPCGPCSERRKHLFVQDPQTCKCSCKNTDSRCKARQLELN ERTCRCDKPRR (SEQIDNO:27) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSVRGKGKGQKRKRK KSRYKSWSVYVGARCCLMPWSLPGPHPCGPCSERRKHLFVQDPQTCKC SCKNTDSRCKARQLELNERTCRCDKPRR (SEQIDNO:28) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCGPCSERRKHLFVQ DPQTCKCSCKNTDSRCKARQLELNERTCRSLTRKD (SEQIDNO:29) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQEKKSVRGKGKGQKRKRK KSRPCGPCSERRKHLFVQDPQTCKCSCKNTDSRCKARQLELNERTCRC DKPRR (SEQIDNO:30) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRPKKDRARQENPCGPCSERRKHLFVQ DPQTCKCSCKNTDSRCKM (SEQIDNO:31) MTDRQTDTAPSPSYHLLPGRRRTVDAAASRGQGPEPAPGGGVEGVGAR GVALKLFVQLLGCSRFGGAVVRAGEAEPSGAARSASSGREEPQPEEGE EEEEKEEERGPQWRLGARKPGSWTGEAAVCADSAPAARAPQALARASG RGGRVARRGAEESGPPHSPSRRGSASRAGPGRASETMNFLLSWVHWSL ALLLYLHHAKWSQAAPMAEGGGQNHHEVVKFMDVYQRSYCHPIETLVD IFQEYPDEIEYIFKPSCVPLMRCGGCCNDEGLECVPTEESNITMQIMR IKPHQGQHIGEMSFLQHNKCECRCDKPRR FurtherexamplesofVEGF-Bisoformare: (SEQIDNO:32) MSPLLRRLLLAALLQLAPAQAPVSQPDAPGHQRKVVSWIDVYTRATCQ PREVVVPLTVELMGTVAKQLVPSCVTVQRCGGCCPDDGLECVPTGQHQ VRMQILMIRYPSSQLGEMSLEEHSQCECRPKKKDSAVKPDRAATPHHR PQPRSVPGWDSAPGAPSPADITHPTPAPGPSAHAAPSTTSALTPGPAA AAADAAASSVAKGGA (SEQIDNO:33) MSPLLRRLLLAALLQLAPAQAPVSQPDAPGHQRKVVSWIDVYTRATCQ PREVVVPLTVELMGTVAKQLVPSCVTVQRCGGCCPDDGLECVPTGQHQ VRMQILMIRYPSSQLGEMSLEEHSQCECRPKKKDSAVKPDSPRPLCPR CTQHHQRPDPRTCRCRCRRRSFLRCQGRGLELNPDTCRCRKLRR (SEQIDNO:34) MHLLGFFSVACSLLAAALLPGPREAPAAAAAFESGLDLSDAEPDAGEA TAYASKDLEEQLRSVSSVDELMTVLYPEYWKMYKCQLRKGGWQHNREQ ANLNSRTEETIKFAAAHYNTEILKSIDNEWRKTQCMPREVCIDVGKEF GVATNTFFKPPCVSVYRCGGCCNSEGLQCMNTSTSYLSKTLFEITVPL SQGPKPVTISFANHTSCRCMSKLDVYRQVHSIIRRSLPATLPQCQAAN KTCPTNYMWNNHICRCLAQEDFMFSSDAGDDSTDGFHDICGPNKELDE ETCQCVCRAGLRPASCGPHKELDRNSCQCVCKNKLFPSQCGANREFDE NTCQCVCKRTCPRNQPLNPGKCACECTESPQKCLLKGKKFHHQTCSCY RRPCTNRQKACEPGFSYSEEVCRCVPSYWKRPQMS

[0151] An example of VEGF-C isoform is:

[0152] An example of VEGF-D isoform is:

TABLE-US-00016 (SEQIDNO:35) MYREWVVVNVFMMLYVQLVQGSSNEHGPVKRSSQSTLERSEQQIRAAS SLEELLRITHSEDWKLWRCRLRLKSFTSMDSRSASHRSTRFAATFYDI ETLKVIDEEWQRTQCSPRETCVEVASELGKSTNTFFKPPCVNVFRCGG CCNEESLICMNTSTSYISKQLFEISVPLTSVPELVPVKVANHTGCKCL PTAPRHPYSIIRRSIQIPEEDRCSHSKKLCPIDMLWDSNKCKCVLQEE NPLAGTEDHSHLQEPALCGPHMMFDEDRCECVCKTPCPKDLIQHPKNC SCFECKESLETCCQKHKLFHPDTCSCEDRCPFHTRPCASGKTACAKHC RFPKEKRAAQGPHSRKNP

[0153] Interleukin 8 (IL-8)

[0154] Interleukin 8 (IL-8) is a chemokine that is produced by macrophages, epithelial cells, airway smooth muscle cells and endothelial cells. IL-8 binds to a number of cell-surface receptors, including CXCR1 and CXCR2, and is an important mediator of the innate immune response.

[0155] IL-8 is also known as chemokine (C-X-C motif) ligand 8 (CXCL8).

[0156] In one embodiment, the IL-8 is human IL-8.

[0157] An example amino acid sequence of IL-8 is the sequence deposited under NCBI Accession No. NP_000575.1.

[0158] A further example amino acid sequence of IL-8 is:

TABLE-US-00017 (SEQIDNO:36) MTSKLAVALLAAFLISAALCEGAVLPRSAKELRCQCIKTYSKPFHPKF IKELRVIESGPHCANTEIIVKLSDGRELCLDPKENWVQRVVEKFLKRA ENS

[0159] IL-8 may be processed into a mature form, for example by cleavage of a signal peptide. Thus, a further example amino acid sequence of IL-8 is:

TABLE-US-00018 (SEQIDNO:37) AVLPRSAKELRCQCIKTYSKPFHPKFIKELRVIESGPHCANTEIIVKL SDGRELCLDPKENWVQRVVEKFLKRAENS

[0160] Determining Biomarker Levels

[0161] The level of the individual biomarker species in the sample may be measured or determined by any suitable method known in the art. For example, mass spectrometry (MS), antibody-based detection methods (e.g. enzyme-linked immunosorbent assay, ELISA), non-antibody protein scaffold-based methods (e.g. fibronectin scaffolds), radioimmunoassays (RIA) or aptamer-based methods may be used. Other spectroscopic methods, chromatographic methods, labelling techniques or quantitative chemical methods may also be used.

[0162] In one embodiment, the level of the one or more biomarkers may be determined via binding to one or more antibodies that are specific to the one or more biomarkers. Suitable antibodies are known or may be generated using known techniques.

[0163] Suitable methods for detecting antibody levels include, but are not limited to, immunoassays, such as enzyme-linked immunosorbent assays (ELISAs), radioimmunoassays, Western blotting and immunoprecipitation.

[0164] Preferably, the level of the one or more biomarkers is determined using a sandwich immunoassay.

[0165] The antibody may be, for example, a monoclonal antibody, polyclonal antibody, multispecific antibody (e.g. bispecific antibody) or fragment thereof provided that it specifically binds to the biomarker being detected. Antibodies may be obtained by standard techniques comprising immunising an animal with a target antigen and isolating the antibody from serum. Monoclonal antibodies may be made by the hybridoma method first described by Kohler et al. (Kohler et al. (1975) Nature 256: 495) or may be made by recombinant DNA methods (e.g. disclosed in U.S. Pat. No. 4,816,567). Monoclonal antibodies may also be isolated from phage antibody libraries using the techniques described in Clackson et al. (Clackson et al. (1991) Nature 352: 624-628) and Marks et al. (Marks et al. (1991) J. Mol. Biol. 222: 581-597), for example. The antibody may also be a chimeric or humanised antibody.

[0166] In one embodiment, the level of the one or more biomarkers may be determined by staining the sample with a reagent that labels one or more of the biomarkers. Staining is typically a histological method, which renders the biomarker detectable, for example by microscopic techniques, such as those using visible or fluorescent light.

[0167] In one embodiment, the biomarker is detected in the sample by immunohistochemistry (IHC). In IHC, the biomarker may be detected by an antibody that binds specifically to one or more of the biomarkers.

[0168] Two general methods of antibody-based detection (including for IHC-based methods) are available: direct and indirect assays. According to the first assay, binding of antibody to the target antigen is determined directly. This direct assay uses a labelled reagent, such as a fluorescent tag or an enzyme-labelled primary antibody, which can be visualised without further antibody interaction.

[0169] In a typical indirect assay, unconjugated primary antibody binds to the antigen and then a labelled secondary antibody binds to the primary antibody. Where the secondary antibody is conjugated to an enzymatic label, a chromogenic or fluorogenic substrate is added to provide visualisation of the antigen. Signal amplification occurs because several secondary antibodies may react with different epitopes on the primary antibody.

[0170] The primary and/or secondary antibody used may be labelled with a detectable moiety. Numerous labels are available, including radioisotopes, colloidal gold particles, fluorescent labels and various enzyme-substrate labels. Fluorescent labels include, but are not limited to, rare earth chelates (europium chelates), Texas Red, rhodamine, fluorescein, dansyl, Lissamine, umbelliferone, phycocrytherin and phycocyanin, and/or derivatives of any one or more of the above. The fluorescent labels can be conjugated to the antibody using known techniques.

[0171] Various enzyme-substrate labels are available (e.g. disclosed in U.S. Pat. No. 4,275,149). The enzyme generally catalyses a chemical alteration of the chromogenic substrate that can be detected microscopically, for example under visible light. For example, the enzyme may catalyse a colour change in a substrate, or may alter the fluorescence or chemiluminescence of the substrate. Examples of enzymatic labels include luciferases (e.g. firefly luciferase and bacterial luciferase; e.g. disclosed in U.S. Pat. No. 4,737,456), luciferin, 2,3-dihydrophthalazinediones, malate dehydrogenase, urease, peroxidase such as horseradish peroxidase (HRPO), alkaline phosphatase, beta-galactosidase, glucoamylase, lysozyme, saccharide oxidases (e.g. glucose oxidase, galactose oxidase and glucose-6-phosphate dehydrogenase), heterocyclic oxidases (e.g. uricase and xanthine oxidase), lactoperoxidase, microperoxidase, and the like. Techniques for conjugating enzymes to antibodies are well known.

[0172] Typically IHC methods may comprise a step of detecting stained regions within an image. Pixels in the image corresponding to staining associated with the biomarker may be identified by colour transformation methods, for example as disclosed in U.S. Pat. Nos. 6,553,135 and 6,404,916. In such methods, stained objects of interest may be identified by recognising the distinctive colour associated with the stain. The method may comprise transforming pixels of the image to a different colour space and applying a threshold value to suppress background staining.

[0173] For example, a ratio of two of the RGB signal values may be formed to provide a means for discriminating colour information. A particular stain may be discriminated from background by the presence of a minimum value for a particular signal ratio. For example, pixels corresponding to a predominantly red stain may be identified by a ratio of red divided by blue (RIB) which is greater than a minimum value.

[0174] Kong et al. (Kong et al. (2013) Am. J. Clin. Nutr. 98: 1385-94) describes the use of the avidin-biotin-peroxidase method and two independent investigators counting the number of positively stained cells.

[0175] Detection using aptamers may comprise the following steps: [0176] aptamers that specifically recognise the biomarker may be synthesised using standard nucleic acid synthesis techniques or selected from a large random sequence pool, for example using the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technique; [0177] aptamers are mixed with the samples so that aptamer-protein complexes are formed; [0178] non-specific complexes are separated; [0179] bound aptamers are removed from their target proteins; [0180] aptamers are collected and measured, for example using microarrays or mass spectrometry techniques.

[0181] Aptamers can be single stranded DNA or RNA sequences that fold into a unique 3D structure having a combination of stems, loops, quadruplexes, pseudoknots, bulges or hairpins. The molecular recognition of aptamers results from intermolecular interactions, such as the stacking of aromatic rings, electrostatic and van der Waals interactions, or hydrogen bonding with a target compound. In addition, the specific interaction between an aptamer and its target is complemented through an induced fit mechanism, which requires the aptamer to adopt a unique folded structure to its target. Aptamers can be modified to be linked with labelling molecules such as dyes or immobilised on the surface of beads or substrates for different applications.

[0182] Samples

[0183] The invention comprises a step of determining the level of one or more biomarkers in one or more samples obtained from a subject.

[0184] Preferably, the sample is cerebrospinal fluid (CSF) sample or a sample derived from blood.

[0185] The sample derived from blood may contain a blood fraction or may be whole blood. Preferably, the sample derived from blood is a plasma or serum sample, most preferably a serum sample.

[0186] Techniques for collecting samples from a subject are well known in the art.

[0187] Subject

[0188] The subjects disclosed herein are preferably mammals, particularly preferably humans. Both human and veterinary applications are within the scope of the invention.

[0189] The subject may be, for example, an ageing human subject, such as a human over the age of 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 years old. Preferably, the subject is a human over the age of 55 years old. For veterinary applications, the age of the animal would be scaled from the human situation using the average lifespan for calibration.

[0190] Method of Treatment

[0191] It is to be appreciated that all references herein to treatment include curative, palliative and prophylactic treatment; although in the context of the invention references to preventing are more commonly associated with prophylactic treatment. Treatment may also include arresting progression in the severity of a disease.

[0192] Dietary Intervention

[0193] The term dietary intervention refers to an external factor applied to a subject which causes a change in the subject's diet.

[0194] In one embodiment, the dietary intervention is a diet supplemented with vitamins and/or minerals, preferably vitamin B.

[0195] In another embodiment, the dietary intervention is a diet supplemented with omega-3 fatty acids.

[0196] In one embodiment, the dietary intervention comprises increasing vitamin B intake by the subject, preferably by administering a vitamin B supplement.

[0197] In another embodiment, the dietary intervention comprises increasing omega-3 fatty acid intake by the subject, preferably by administering an omega-3 fatty acid supplement.

[0198] The vitamin B may be, for example, vitamin B12, vitamin B6 and/or folic acid.

[0199] The omega-3 fatty acid may be, for example, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), preferably EPA.

[0200] The diet may be one which is adjusted to the starting body weight of the subject.

[0201] The dietary intervention may comprise administration of at least one diet product. The diet product may be a meal replacement product or a supplement product. The diet product may include food products, drinks, pet food products, food supplements, nutraceuticals, food additives or nutritional formulae.

EXAMPLES

Example 1

[0202] Materials and Methods

[0203] Subject Population

[0204] 120 community-dwelling adults aged 55 years or older (48 of them having no cognitive impairment, 72 with cognitive impairment (mild cognitive impairment (MCI), n=63; and mild dementia, n=9) were enrolled in this study. The clinical evaluation included a neurological and general examination and extensive neuropsychological evaluation. Subjects with neurological or psychiatric diseases or with a severe or unstable medical illness were excluded. Along with the clinical examination, the Hospital Anxiety and Depression (HAD) scale was administered (Zigmond & Snaith, Acta Psychiatr. Scand. 1983, 67 (6), 361-370).

[0205] The study participants with MCI and the participants with mild dementia have been recruited among outpatients with cognitive impairment referred to the Memory Clinics, Departments of Psychiatry, and the Leenaards Memory Center, Department of Clinical Neurosciences, University Hospitals of Lausanne for investigation of their cognitive complaints. The diagnosis of MCI or of mild dementia was based on neuropsychological and clinical evaluation, and made by a consensus conference of psychiatrists and/or neurologists, and neuropsychologists prior to the inclusion in the study. For instance, MCI criteria required memory impairment (<1.5 SD below the age, gender and education adjusted mean on the Buschke Double Memory Test verbal memory score) (Buschke, Sliwinski, Kuslansky, & Lipton, Neurology 1997, 48 (4), 989-997), and/or impairment in another cognitive domain such as executive tasks, and a Clinical Dementia Rating (CDR) (Morris, Neurology 1993, 43 (11), 2412-2414) equal to 0.5.

[0206] Probable Alzheimer's dementia was defined according to the clinical diagnostic criteria from the National Institute on Aging and Alzheimer's Association and DSM-IV criteria for dementia of the Alzheimer type (American-Psychiatric-Association). Participants in this group have a CDR of 1.0. The participants without cognitive impairment (n=48) had no history or evidence of cognitive decline, and a CDR score of 0. They are community-dwelling volunteers recruited by advertisement or among the spouses of memory clinic patients.

[0207] Neuropsychological and Functional Assessments

[0208] The neuropsychological assessment includes measures of memory and other major cognitive domains such as language, attention and executive functioning. This assessment consists of the Mini Mental State Examination (Folstein M F et al. 1975, J. Psychiatr. Res 12, 189-198), the Buschke Double Memory Test (Buschke H et al. 1997, Neurology, 48, 989-997) the digit span forward and backward (Wisdom N M et al. 2012, Arch Clin Neuropsychology 27, 389-397), the Stroop Test (Stroop J R 1935, J. of Expt. Psychology 18, 643-662), the letter fluency task (Cardebat D et al. 1990, Acta Neurol Belg 90, 207-217), and the Trail Making Tests A and B (Reitan R M 1955, J. Consult Psycho) 19, 393-394). The functional assessment includes the ADL and instrumental ADL (IADL) (Lawton M P et al. 1969, Gerontologist 9, 179-186). as well as the CDR (Morris J C 1993, Neurology, 43, 2412-2414). The neuropsychological test battery, ADL and IADL, and the CDR were used to verify inclusion and exclusion criteria.

[0209] Additional Assessment

[0210] The brief clinical form of the Neuropsychiatric Inventory (Kaufer, D. I. et al. (2000) J. Neuropsychiatry Clin. Neurosci. 12: 233-9) was administrated to assess neuropsychiatric symptoms in all participants. The Cumulative illness rating scale-geriatrics (Miller M D et al. 1992, Psychiatry Res 41, 237-248) was used to measure the participants individual chronic medical illness burden.

[0211] Cerebrospinal Fluid (CSF) and Blood Collection and Handling

[0212] Venous and lumbar punctures were performed between 8:30 and 9:30 am in the Memory centres after an overnight fast. Blood was drawn into EDTA containing vacutainers (Sarstedt, Germany) and spun down to permit aliquots of supernatant (plasma and serum) for the analysis. Lumbar puncture and spinal fluid collection was performed on subjects in sitting or lying position with a 22G atraumatical spinal needle to capture 10-12 mL of CSF into polypropylene tubes. CSF cell count and protein quantification were performed in 2-3 mL and the remaining CSF was centrifuged, aliquoted, snap-frozen and stored at 80 C. until assay.

[0213] Neuroinflammatory Biomarker Analysis

[0214] A sandwich immunoassay (Meso Scale Discovery (MSD), Rockville, Md., USA) quantified 37 analytes (IFN-gamma, IL-1B, IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, TNFa, IL-1a, IL-5, IL-7, IL-12123p40, IL-15, IL-16, IL-17A, TNF-, VEGFA, Eotaxin, MIP-1B, Eotaxin-3, TARC, IP-10, MIP-1a, MCP-1, MDC, MCP-4, VEGF-C, VEGF-D, Tie-2, Flt-1, PIGF, bFGF, SAA, CRP, VCAM-1, ICAM-1) in CSF and serum.

[0215] Samples were measured following the manufacturer's instructions. Briefly, the 96-well plates pre-coated with capture antibodies were blocked with 5% MSD Blocker A Solution. Calibrator dilutions were prepared and samples were diluted as recommended for each kit with MSD Diluents. Samples and calibrators were then added to the plates and incubated at room temperature with shaking for 2 h. Plates were washed three times with a home-prepared solution of 10 phosphate-buffered saline (PBS), pH 7.4 (Corning, Manassas, Va., USA)-Tween 20 (Fisher Scientific, Pittsburgh, Pa., USA). Detection antibodies were mixed with MSD Diluents as indicated in the protocols of each kit and incubated at room temperature with shaking for 1-2 h. Plates were washed three times with the PBS-Tween 20 solution. MSD Read buffer was added and plates were read on an MSD instrument (SECTOR Imager 6000 reader). Data were generated and interpolated using MSD Discovery Workbench software.

[0216] APOE Genotyping

[0217] Leukocyte genomic DNA was isolated from 9 mL EDTA blood with the Qiagen blood isolation kit (Qiagen, Hilden, Germany) and the APOE genotype was determined.

[0218] Ethical Approvals for Human Research

[0219] The study was approved by the CHUV (Centre Hospitalier Universitaire Vaudois) Lausanne hospital ethics committee and the Canton of Vaud, Switzerland, Commission Cantonale d'thique de la recherche sur l'tre humain (CER-VD). Written informed consent was obtained from all study participants.

[0220] Statistical AnalysisPre-Analytical Quality Control of Biomarker Data

[0221] Biomarker data was quality-controlled prior to hypothesis testing by first excluding those with more than 5% missing data. The remaining missing data (<5%) was imputed by randomly drawing a measure between the observed range of biomarker values. Biomarker data was then log-transformed to approach a Gaussian distribution, and standardised prior to final hypothesis testing.

[0222] Statistical AnalysisReference Model

[0223] The association of BBB impairment with demographic variables (age, gender) and candidate Alzheimer's disease biological parameters (presence of ApoEe4 allele, CDR, education, CSF abeta.sub.1-42, phospho-tau181 and total tau (t-tau)) was analysed using logistic regression models. The performance of the obtained classifier was assessed by measuring (i) its area under the Receiver Operating Characteristic (ROC) curve and its 95% confidence interval (using a bootstrap approach with 1000 iterations) and (ii) its accuracy (cumulated proportion of true-positives and true-negatives in the obtained 22 confusion matrix).

[0224] BBB impairment was defined as CSF-to-serum ratio of albumin greater than 9.0.

[0225] Statistical AnalysisBest Model

[0226] Least absolute shrinkage and selection operator (LASSO) logistic regression was used to select relevant biomarker features and build a predictive model of BBB impairment. All biomarker variables were included in the model, together with the variables used in the Reference model (age, gender, presence of ApoEe4 allele, CDR, education, CSF abeta.sub.1-42, phospho-tau181 and total tau (t-tau)). These reference variables were included as non-penalised variables to ensure they were not filtered out by the LASSO selection process and to permit comparability with the reference model. A 10-fold cross-validation process was performed for each LASSO analysis using the glmnet package which permits estimation of the 95% confidence interval for the misclassification error for each value of the regularisation parameter. The LASSO analysis was repeated 100 times. The model that minimised the cross-validated misclassification error across the 100 runs was selected. Its performance was assessed by ROC area under the curve (AUC) estimation and compared with the Reference model.

[0227] Results and Discussion

[0228] Baseline characteristics are shown in Table 1. 118 subjects passed pre-analytical quality control for missing data, of which 13.5% (n=16) met the criteria for blood-brain barrier (BBB) impairment. There were no significant differences between age, education, MMSE, HAD scale, CDR, presence of ApoEe4 allele, CSF abeta.sub.1-42, CSF t-tau and CSF phospho-tau181 between subjects with and without BBB impairment. However, there were more men with BBB impairment. Consistent with the literature, subjects with CDR 0.5/1 compared to CDR 0 had significantly higher albumin ratio verifying the functional significance of BBB function.

TABLE-US-00019 TABLE 1 Clinical and demographic characteristics of the older adult population.sup.1 All BBB intact BBB impairment (n = 118) (n = 102) (n = 16) Age, y, mean (SD) 70.2 (7.8) 69.8 (7.7) 72.8 (8.2) Gender, n (%) of Males 42 (35.59%) 32 (31.37%) 10 (62.50%) ApoE4 carrier, n (%) 37 (31.36%) 32 (31.37%) 5 (31.25%) Education, y, mean (SD) 12.4 (2.6) 12.5 (2.7) 11.9 (2.1) MMSE scale, mean (SD) 26.9 (3.1) 27.3 (2.9) 24.8 (3.4) CDR = 0, n (%).sup.2 48/118 (40.68%) 45/102 (44.12%) 3/16 (18.75%) Diabetes, n (%) 11 (9.48%) 9 (9.00%) 2 (12.50%) Hypertension, n (%) 41 (35.34%) 35 (35.00%) 6 (37.50%) CSF Albumin ratio, mean (SD) 6.1 (2.4) 5.4 (1.5) 10.7 (1.5) CSF abeta.sub.1-42 (pg/mL), mean (SD) 841.5 (262.9) 836.0 (250.1) 876.6 (341.1) CSF t-tau (pg/mL), mean (SD) 369.5 (280.1) 356.2 (268.9) 454.4 (340.5) CSF phospho-tau (pg/mL), mean 61.9 (35.5) 61.5 (36.8) 64.0 (26.3) (SD) CSF sICAM-1 (pg/mL), mean (SD) 2400.5 (671.4) 2259.4 (577.5) 3291.0 (531.9) CSF VEGF (pg/mL), mean (SD) 4.2 (1.0) 4.1 (0.9) 5.1 (0.9) CSF IL-8 (pg/mL), mean (SD) 41.8 (14.8) 40.7 (14.7) 49.1 (13.7) CSF SAA (pg/mL), mean (SD) 1963.2 (5800.1) 1231.3 (1382.3) 6582.8 (14867.7) CSF MDC (pg/mL), mean (SD) 33.3 (21.6) 32.5 (22.1) 38.0 (17.5) .sup.1Mean and standard deviation (SD) unless denotation states otherwise, MMSE, Mini Mental State Examination; HAD, Hospital Anxiety and Depression Scale; CDR, Clinical Dementia Rating; APOE4, apolipoprotein E epsilon 4; .sup.2CDR scores include 0 (n = 48), 0.5 (n = 61) and 1 (n = 9)

[0229] CSF Biomarkers for Classification of BBB Impairment

[0230] FIG. 1 illustrates the Reference and Best model ROC curves calculated for prediction of BBB impairment. The Reference model included age, gender, education, CDR, presence of ApoEe4 allele and CSF levels of abeta42, t-tau, and phospho-tau181 yielding a ROCAUC=0.80 and diagnostic accuracy for BBB impairment of 87.3%. The addition of the CSF neuroinflammatory biomarkers identified improved ROC AUC to 0.95 and the accuracy to 92.3%, with a Best model that included gender and 5 CSF biomarkers (sICAM-1, VEGF, IL-8, SAA, and MDC). The mean concentration differences between each of these 5 CSF biomarkers is illustrated in Table 1.

[0231] The five CSF biomarkers that best classify BBB impairment: CSF sICAM-1, VEGF, IL-8, SAA and MDC were all higher in individuals with BBB impairment.

[0232] Serum Biomarkers for Classification of BBB Impairment

[0233] We observed a significant correlation in the concentrations of SAA measured both in CSF and serum in the cohort under study (FIG. 2). This observation suggested that, in humans, the determination of SAA concentration in serum might be a surrogate of SAA concentration in CSF. Sampling human serum and determining SAA concentrations in serum could offer a much less invasive alternative to SAA determinations in CSF.

[0234] All publications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described methods of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention, which are obvious to those skilled in biochemistry and biotechnology or related fields, are intended to be within the scope of the following claims.