Alzheimer’s disease and its treatment Flashcards
Dementia?
A syndrome
Usually of a chronic or progressive nature.
Deterioration in cognitive function- ie the ability for process thought.
What does dementia effect?
Affects memory
Thinking
Orientation
Comprehension
Learning capacity
Lanaguage etc
Consciousness is not effected
What percentage is dementia surferrers caused by alzheimers?
60-70%
Mixed dementia?
Mixture of different types of dementia
What are the numbers of dementia sufferers expected to do every 25 years
Numbers expected to double
AD brain?
Brain has shrunk
Extracellular plaques and intracellular neurofibrillary tangles
Name the 6 important stages of the history of AD research?
- Chloinergic hypothesis
- Discovery of amyloid and tau.
- Oxidative damage.
- Genetic mutations
- Importance of inflammation
- Immunotherapy (antibodies against amyloid)
What happens to an Alzheimers brain?
Severe cell loss.
Spreads from hippocampus right through into the cerebellum and into the spinal cord.
Damge to proteins and protein accumulations
Damage to lipids and inflammation
Late onset alzheimers?
>95% of dementia cases.
>65 yo.
Genetic link with APOE
Early onset Alzheimers disease?
5% of AD cases
Present in >65 yo.
Genetic link with APP, PSEN1, PSEN2
Apolipoprotein E (ApoE)
Major component of very low-density lipoproteins.
Remove excess cholesterol from the blood and carry it to the liver.
Most abundantly produced apoprotein
ApoE role?
Cholesterol and lipid delivery to neurones
Cholesterol transport to the blood to the liver for processing.
What secretes ApoE?
Secreted by glial cells in nascent high-density lipoproteins-like particles.
They contain phospholipids and cholesterol
What is the ApoE concentration in cerebrospinal fluid?
5 µg/ml
ApoE receptors?
LDLR (low desity lipoprotein receptor)
LRP1 (LDLR-related protein)
Undergo endocytosis to transport ligands from the cell surface to intracellular compartments.
ApoE is?
How many forms of it?
glycoprotein
3 common forms (each differ from each other by 1/2 AAs)
ApoE2
ApoE3
ApoE4
ApoE4
Risk of AD is high with one allelle and must greater with two alleles.
60% are ApoE carriers.
Reduces the age of this onset disease.
More extensive plaques and tangles.
Higher CSF concentration of soluble Abeta.
ApoE effects on amyloid?
ApoE contains paritcles sequester Aβ that modulates the cellular uptake of the complex by receptor-mediated endocyotsis.
Modulate Aβ removal from the brain by systemic circulation (transport across the blood-brain barrier)
ApoE facilitates the binding and internalisation of Aβ or its clearance
Targeting ApoE?
Name the 5 Therapeutic approaches
- Conversion of ApoE4 to ApoE3.
- Increase the lipidation.
- Interference interaction between ApoE4 and amyloid beta (Aβ).
- Reversal of the effects of ApoE4.
- Gene transfer
What does ApoE3 and ApoE4 do?
AS1
TREM2?
Triggering receptor expressed on myeloid cells 2.
increaase chance of AD by 3 fold
Rare
Found in microglia.
Related to parkinson’s
PLD3?
little known on function.
Overexpression leads to reduction in Aβ levels
Name the 3 dominatly inherited mutations involved in amyloid processing?
- β-amyloid precusor protein
- PSEN1
- PSEN2
β-amyloid precursor protein (APP)?
Alternatively spliced to produce 3 transcripts
APP695, APP751, APP770
Proteolytic processing of APP leads to production of rfragments and the amyloidogenic pathways.
PSEN1/2?
PSEN1: Located at chromosome 14
PSEN2: located at chromosome 1
PSEN1/2 are important for the γ-secretase complex.
This cleaves APP into Aβ fragments
3 main pathways causing AD?
- The immune system and inflammatory response
- Cholesterol and lipid metabolism
- Endosomal vesicle recycling
What are the 5 major hypotheses that causes AD?
- Cholinergic and glutamatergic
- Amyloid and Tau
- Oxidative stress
- Inflammation
- New targets