ALS

Question 1

What is Amyotrophic Lateral Sclerosis?

Answer 1

Degeneration of UMNs and LMNs
Low excitable, fast-fatiguable fibres degenerate first

M>F
Age of onset 55
10% Familial
Sx: Muscle weakness, loss of voluntary movement
- Maintained cognitive function, bladder/bowel function

Question 2

SOD1 mutations in ALS

Answer 2

Superoxide Dismutase 1 gene

• Toxic gain of function causes increased reactive oxygen species (hydrogen peroxidase) leading to neuronal death
• Lower levels of Excitatory Amino Acid Transporter 2 (EAAT2)
• Increased synaptic glutamate levels –> Ca2+ influx, and excitotoxicity

Question 3

SOD1 animal models- most common

Answer 3

SOD1G93A: most common, onset at 90d/death at 120d
SOD1D83G: may be more representative

Question 4

SOD1 example model

Nagai 2007

Answer 4

Growing primary spinal/Embryonic SC-derived MNs on SOD1-mutated astrocytes kills MNs, reducing axonal length and cell body diameter

• Release of astrocytic neurotoxic factors
• Myocytes, microglia and fibroblasts had no effect

Only affected MNs, with no effect on GABAergic/DRG neurons

Question 5

Issues with SOD1 models

Answer 5

No development of Fronto-Temporal Dementia OR Substantial cortical MN degeneration (seen in humans)
Mutations are needed in both neurons and glia
Lack of correlation between human/animal studies

Question 6

Minocycline treatment for ALS in SOD1 model

Answer 6

Demonstrated increased survival in SOD1 mouse models
BUT
Phase 3 RCT: Minocycline is determined harmful
- AEs more common in treatment group
- ALSFRS-R score deteriorated more quickly

Question 7

TDP43 models of ALS

Answer 7

Mutations in the TARDP gene

- Aberrant RNA metabolism, leading to nuclear inclusions formation

Question 8

Issues with TDP43 models

Answer 8

• M/F survival differences: may be underlied by myenteric plexus cell death
• Lack of symptomatic differences (grip strength, wire hanging) between males and females
• Differences in toxicity between WT/mutant overexpression
• Many animals die of other causes
• Needed in glia; neuronal-specific overexpression produces a rapidly progressive phenotype
• Astrocyte knockdown drives mass neuronal loss
• TDP43 inclusions are most abundant in oligodendrocytes in humans

Question 9

VCP Mutant Models

Answer 9

VCP R155H Knock-in

• Develop ALS and Fronto-temporal dementia
• Cytoplasmic TDP43 accumulation in the SC
• Progressive muscle weakness

Question 10

GluR2 expression in ALS

Answer 10

ALS MNs have reduced editing efficiency of GluRs vs. Purkinje cell controls
- absence of GluR2 subunit increases Ca2+ permeability –> excitotoxicity

Question 11

Calcium buffering proteins in ALS

Answer 11

Remove excess intracellular calcium

- Are reduced in ALS/ SOD1 cell models

Question 12

Gold standard ALS treatment

Answer 12

Riluzole

Improves long-term survival with early administration

Question 13

Calcium binding proteins treatment for ALS

Answer 13

Cross-breeding SOD1 mutants with Parvalbumin o/e mice

• Increases neuronal survival and overall progress
• Human application

Question 14

Calcium channel blockers treatment for ALS

Answer 14

e.g. Lomerizine

Efficacious at increasing MN survival in SOD1 model only

Question 15

Neurotrophic factor treatment for ALS

Answer 15

Intrathecal GDNF/BDNF improves relative survival

• Clinical usage- no sig. benefits
• May differentially affect motoneurones

Question 16

Heat Shock Response Manipulation

Arimoclomol

Answer 16

ALS patients have an upregulated heat shock response

Arimoclomol enhances neuroprotective effects by prolonging Hsf-1 activation
Increases expression of HSP70/90- reduces heat shock protein aggregation
-Treatment presymptomatically (AND symptomatically) improved motor neuron survival and increased hind limb muscle function

2018 DB RCT showed Arimoclomol was safe and well tolerated in SOD1 ALS patients, reducing ALSFRS-R score

Question 17

iPSCs for ALS treatment- studies for

Answer 17

Kondo 2014: Glial-rich progenitors

• Increased pAKT activation and signalling
• Improved motor scores
• Surival higher in males
• BUT most cells differentiated into GFAP+ astrocytes

Clinical trials promising but multiple injection sites needed

Xu 2011: Intraspinal transplantation of rodent glial-restricted progenitors

• Promoted MN projection
• Delayed respiratory function
• Extended disease progression

Question 18

iPSCs for ALS treatment- evidence against

Answer 18

ICV injections of MSCs
- Protects motor neurons, activating p-AKT signalling. switch from pro to anti-inflammatory pathways

• Does not delay disease onset or increase neuronal survival/grip strength

Question 19

Insulin-Like Growth Factor 2 in specific ALS patients

Answer 19

iPSCs derived from ALS patients with specific mutations of motoneurons
ILGF2 is expressed at higher levels in less vulnerable neurons
-Vardenafil (increases IGF2 expression) differentially affects ALS patients depending upon their mutation status

Question 20

Targetting endogenous SCs in ALS

Answer 20

Nicotine treatment enhances oligodendrocyte proliferation in an MS model
-Reduced GFAP+ cells and inflammation

Question 21

Autonomic deficits in ALS

Sympathetic nerve activity/ BRS

Answer 21

Increased MSNA but lower IML neuron numbers

Increased BRS may be compensatory