Parkinson's disease

Question 1

gene therapy approaches to PD

Answer 1

1. Restoring dopaminergic signalling
2. Compensating for loss of dopamine
3. Rescuing the neurodegenerative process
   a. Broad approaches
   b. Precision approaches for genetic subgroups

Question 2

three enzymes needed to make dopamine

Answer 2

1. GCH1
2. Tyrosine hydroxylase (TH)
3. AADC

Question 2

restoring dopamine signalling - in PD

Answer 2

Levodopa – is an amino acid, derived from tyrosine.

To make dopamine from tyrosine, various enzymes are needed, that are coded for in dopaminergic nerve cells. Including tyrosin hydroxylase, and a co-factor called tetrahydrobiopterin, and you need GCH1 for this to.

Once L-dopa is made (or given), it gets converted to dopamine by AADC.

Question 3

enzyme needed to convert levodopa into dopamine

Answer 3

1. AADC

Question 4

AAV + Adenovirus + lentivirus - transduction efficacy and integration

Answer 4

AAV: moderate, non-integrating
Adenovirus: high, non-integrating
Lentivirus: moderate, integrating

Question 5

AAV + Adenovirus + lentivirus - expression, immunogenicity

Answer 5

AAV: transient or stable, very low
Adenovirus: transient, high
Lentivirus: stable, low

Question 6

AAV-hAADC

Answer 6

transfected with AADC, when you give levodopa transfers into dopamine.

Question 7

what is prosavin:

Answer 7

• A lentiviral vector-based gene therapy for PD. Shown to increase dopamine concentrations.
• This improvement was thought to be moderate.

Question 8

Axon lenti PD

Answer 8

OXB102 - modified lentiviral vector
- evidence that it improves dopamine synthesis

Question 9

STN-GAD

Answer 9

Subthalamic nucleus is normally excitatory, so by making it inhibitory…

Glutamate is very structurally similar to GABA (ex > in) – you can change it with a substance called GAD.
- Normally, the STN contains predominantly glutamatergic neurons. glutamate decarboxylase (GAD) converts glutamate to GABA.
- Hence expression of GAD in the STN was proposed to transform the glu neurons to GABAergic neurons and convert STN output from excitatory to inhibitory.
- To achieve this an AAV vector carrying the GAD gene was engineered.

Question 10

GDNF in PD

Answer 10

glial cell line-derived neurotrophic factor potentially as a neuroprotective agent in PD.

• GDNF protein results were mixed.
• OR have a viral vector which encourages GDNF expression > this was found to have much better

Question 11

two types of neurosurgical delivery techniques in PD

Answer 11

1. Transfrontal approach
   - multiple trajectories
   - maximal target coverage 30-40%
2. Parietooccipital approach
   - single trajectory
   average target coverage 50-80%

Question 12

Precision therapy in PD

Answer 12

• Link between GCase and alpha-Syn.
• LoF.
• Glucocerebrosidase and alpha-syn form a bidirectional pathogenic loop in Synucleinopathies.
• Using a drug called ambroxol (which is a cough syrup) but is a helpful chaperone for GCase trafficking to ER to Golgi and protects its function.
• After six months, there is an increase in GCase protein, irrespective of whether you have a GBA1 mutation or not.

Question 13

LRRK

Answer 13

Mutation causes a GoF toxicity.
- How can we inhibit?
- Peripheral side effects that can affect lung and kidney function.

ASOs: target RNA, multiple effects in cytoplasm and in the nuclease during mRNA transcription and translation.

Question 14

how do temporarily open the BBB

Answer 14

focused ultrasound opens the BBB.