Motor neurones disease

Question 1

What is spinal muscular atrophy ?

Answer 1

loss of lower motor neurones in SC and brainstem

Question 2

What are the symptoms of spinal muscular atrophy ?

Answer 2

muscle weakness

atrophy and premature death

Question 3

What is the underlying genetic cause of spinal muscular atrophy ?

Answer 3

due to deletion/mutation of SMN1 gene

Question 4

How is the clinical severity of spinal muscular atrophy determined?

Answer 4

by the copy number of SMN2 gene

Question 5

What is the SMN protein essential for ?

Answer 5

essential for axonal and dendritic development and maintenance of motor neurones
- leading genetic cause of infant mortality

Question 6

What are the features of ALS?

Answer 6

degeneration of both upper and lower motor neurones
muscle weakness
loss of voluntary movement- eye, bladder and bowel movement normally maintained
maintain cognitive function
death often occurs after few years due to respiratory failure
- very selective loss of motor neurones, UMN= corticospinal neurones and LMN= within ventral horn - not the same amount of loss in every individual

Question 7

How do patients with ALS often end up communicating ?

Answer 7

by the use of their eyes

Question 8

What happens to sympathetic activity in ALS patients and why is this thought to occur?

Answer 8

activity is increase but the IML neurones are decreased

• causes a loss of autonomic function
• thought it could be due to change in baroreceptive activity

Question 9

How did they record the sympathetic activity?

Answer 9

insert electrodes into sympathetic nerves in the leg region to carry out recordings
- there is a decline in sympathetic neurones in both T2 and T9 of ALS patients

Question 10

What is the incidence of ALS?

Answer 10

1-2/100,000 people- people dont survive long (3-5 years)

Question 11

What is the prevalence of ALS?

Answer 11

4-6/100,000 people

Question 12

What is the average age of onset?

Answer 12

about 55 years old

Question 13

Which gender is more susceptible to ALS and is it hereditary?

Answer 13

men
- only 10% of cases are familial, the rest are sporadic
this makes it difficult to study

Question 14

What is a key common mutation in familial ALS?

Answer 14

mutations in SOD1 gene account for 20% therefore only 2% of all cases

Question 15

What is another mutation that occurs in ALS?

Answer 15

mutations in the TARDP gene encoding a DNA binding protein TDP-43

Question 16

What can increase risk of ALS?

Answer 16

high levels of activity

Question 17

What are the cascade of events leading to neuronal death ?

Answer 17

SOD1= altered axonal transport therefore stopping transport of proteins, enzymes for neurotransmitters and neuropeptides which are critical
- increased calcium leading to activation of apoptotic pathways to cause cell death
increase in glutamate leads to excitotoxicity

Question 18

How can astrocytes contribute to motoneurone death ?

Answer 18

astrocytes can express mutant SOD1 and when this was tested with cultured motoneurones it caused motoneurons death
- only caused death of motoneurones not GABAergic neurones

Question 19

What is the onset and death rate in animal models of ALS?

Answer 19

onset is about 90 days and death is at about 120 days

Question 20

What does the C83G mutation that is present in human demonstrate in animal models ?

Answer 20

it can separate central and peripheral effects

changes in weight and grip test are shown in homozygote animals with reductions in both weight and grip

Question 21

What are the issues with TDP-43 animal models?

Answer 21

not actually mimicking the effects of ALS
not mimicking muscle weakness
therefore we need more appropriate models to model ALS

Question 22

What is a potentially new model that could be used in ALS?

Answer 22

zebrafish model- can see through the young so you can determine if they are developing properly

Question 23

What neurones are affected in ALS?

Answer 23

not all motonuerones are affected to the same degree
- oculomotor neurones and those in the onuf’s nucleus are less susceptible to damage than ventral horn neurones

• facial nucleus is affected- neurones are reduced and those that are present are unhealthy

Question 24

What might correlate with the degree of suscpetiblity of moto neurones to death ?

Answer 24

may correlate with the expression of GluR2

• glutamate receptors lacking the GluR2 subunit are more permeable to calcium therefore an increase in glutamate is crucial
• because abberant editing of the subunit may also increase calcium permeability and cause cell death
• editing efficiency of GluR2 subunit is compromised

Question 25

What was seen in purkinje cells from controls and ALS patients?

Answer 25

looked at % of editing of GluR2 subunit | - the editing efficiency isn't generally affected

Question 26

What transporter is reduced in ALS?

Answer 26

the EAAT2 glial glutamate transporter protein | - this transporter mops up excess glutamate to remove it and prevent is causing excitotoxicity

Question 27

What is interesting about EAAT2 expression and the neurones lost in ALS?

Answer 27

the neurones that are less susceptible to damage have lower EAAT2 in control situation and therefore may normally have lower glutamatergic innervation which may help to protect them

Question 28

What is the expression of EAAT2 like in SOD1 mutant mice ?

Answer 28

EAAT2 in VH of SOD1 mutant mice are not significantly different from controls - species differences SOD1 mutant mice= not good model - vary in patients

Question 29

What other factor may the degree of susceptibility correlate with ?

Answer 29

correlate with the presence of calcium buffering proteins - from post mortem examinations of ALS patients, the pyramidal cells in the motor cortex have low levels of calbindin while those in the sensory cortex have higher levels - these reductions in calcium binding proteins are seen in presympatomatic transgenic mice

Question 30

What is calbindin?

Answer 30

it is a calcium buffer= brown reaction product | - VH motoneurones dont have calbindin

Question 31

What is the mechanism behind excitotoxic neuronal death ?

Answer 31

increased glutamate is due to change in AMPAR and there is no buffer

Question 32

What is the current treatment for ALS and is it effective?

Answer 32

riluzole from italian patients it demonstrated limited success in another study 58% of patients in placebo were still alive whereas 74% in riluzole group were still alive high doses of vitamin e with riluzole dont seem to significantly improve the situation

Question 33

What is needed for ALS treatment?

Answer 33

disease modifying drugs not just ones that relieve symptoms

Question 34

Why might calcium buffering proteins being introduced into motoneurones be beneficial ?

Answer 34

it could reduce the excitotoxic response - parvalbumin immunoreactivoty in VH of control and PV overexpressing mice were compared- cross breeding SOD1 mutant mice with parvalbumin over-expressing mice the number of motoneurons surviving increase while onset of disease and death were delayed

Question 35

Why is blocking calcium channels not always effective?

Answer 35

parvalbumin to motoenurones - mutant SOD1 motoneurone inclusion were reduced with voltage gated calcium channel blocker, lomerizine - but in TDP-43 mutants there was no change in the amount of inclusions

Question 36

What could dictate the efficacy of drugs ?

Answer 36

differing underlyng mechanism in the familial forms

Question 37

What effect does lomerizine have on mutant SOD1?

Answer 37

- strong mitochondrial phenotype - increased mitochondrial and cytosolic calcium concentration - formation of cytoplasmic inclusions and motor neuron death which can be blocked by lomerizine

Question 38

Is lomerizine effective against mutant FUS or TDP-43?

Answer 38

this form has a milder mitochondrial phenotype normal mitochondiral and cytosolic calcium accuulation in the cytoplasm and formation of inclusion leading to disrupted RNA metabolism that cant be blocked by lomerizine

Question 39

What have clinical trials using BDNF shown?

Answer 39

shown that BDNF given intrathecally can be tolerated but over the last 10 years in which ALS patients have been injected with neurotrophic factors there have been no improvements

Question 40

What can GDNF do ?

Answer 40

it may protect facial motoneurons but not VH motoenurones

Question 41

What happened when GDNF or BDNF are injected into muscles of mice?

Answer 41

taken up into VH motoneurons and it led to increased survival time indicating that neurotrophic factors could be beneficial

Question 42

What happens to heat shock proteins ?

Answer 42

they are unregulated in patients with ALS and in SOD1 mutant mice

Question 43

What do heat shock proteins normally act as?

Answer 43

act as cytoprotectants

Question 44

What might the heat shock proteins do in ALS?

Answer 44

they may be unable to counteract the chronic stressful environment so enhancing them may help to alleviate symptoms - in clincal trials there was no significant benefit

Question 45

What is antimoclomol and what effect did it have ?

Answer 45

it is a drug acting ro increase heat shock response - treated SOD1 mutant mice with it - improved movement and muscles - but giving a drug before symptomatic effects have occurred is not beneficial for mimicking ALS in patients however when they gave the drug 33 days after the survival is just as good indicating the drug is effective !

Question 46

What is different in the EU compared to US about drug licensing ?

Answer 46

in the eu there are special regulatory mechanism that allow marketing of unlicensed drug fulfilling certain criteria: - meet a significant unmet medical need (preferably life threatening or significantly disabling)

Question 47

What is coyote trying to achieve?

Answer 47

trying to pursue a dual track clinical development of CP-102 for ALS in the EU and then in the US - Evidence for product safety - evidence supporting product efficacy is the proposed indication they have started regulatory approval processes in the eu with the goal of commencing an open label trial of 20 ALS patients in Q3 in 2014. following completion of the trial, coyote would start generally distributing CP-102 to ALS patients in EU under the named patient program

Question 48

What is CP-102(CNS-102 for ALS)?

Answer 48

it is an orally bioavailable small molecule inducer of heat shock protein gene expression

Question 49

What did CP-102 do in pre-clinical animal trials ?

Answer 49

in pre-clinical animal models of neurodegenerative disease it significantly improve animals behaviours and protected neurones from damage compared to controls it was proven safe and well tolerated in these preliminary trials

Question 50

What was the trial using dexprampexole?

Answer 50

it is a mitochondrial modulator - 300mg dose was much much better for survival - 101 in trial, 18 withdrew and 12 patients died during the 40 weeks - 3 died before receiving drug at 16 weeks in - 7 of the 48 on 50mg doses died while only 2 of the 44 on 300mg dose died - improved survival and motor function

Question 51

Why are clinical trials for ALS so difficult to do ?

Answer 51

they are difficult to carry out because the patients already have such short life expectancies

Question 52

What did coenzyme 10 do ?

Answer 52

it combats oxidative stress, however it was not useful in people with ALS, even at high doses

Question 53

Why are mitochondrial modulators not that effective?

Answer 53

they have no effect on top-43 or sod1 model and they may not be useful in familial forms