Synaptic elimination and the complement system in Alzheimer’s disease
40
7
FUTURE PERSPECTIVES
Most scientific work increases our knowledge about the world, but perhaps
even more it makes us realise the limitations of our knowledge. The work
presented here is not different as it awakes at least as many questions as it
provides answers for. Below I will suggest some potential future directions
for those with interest and recourses.
In paper I we identify an increased risk for AD in subjects with the 82S
variant of RAGE. We speculate that the 82S variant of RAGE might be more
effective in mediating the LTP-inhibiting action of Aβ. This could be tested
by constructing transgenic mice that carry this variant only and evaluate how
they respond to Aβ. Additional gene association studies could also be made
to further tie the LTP-inhibiting effect of Aβ seen in animal studies to actual
AD patients. Interesting candidate genes would be those encoding key LTP
proteins, e.g. the NMDAR, protein kinase C, CAMK II.
In paper II we show that C3 is involved in elimination of synapses in
the hippocampus of mice. The natural course of direction here, would be to
directly investigate the involvement of the complement system in AD
pathophysiology, e.g. if C3 KO mice are protected from Aβ-induced synapse
elimination. Constructing a double transgenic mouse, deficient in C3, and
carrying human APP with a FAD mutation would be a promising approach.
Although we concluded that none of the investigated complement
proteins were suitable CSF biomarkers for AD in paper III, the CSF levels of
several complement proteins remain unknown. A thorough investigation of
complement levels, including the activation products, is definitely warranted.
In paper IV we failed to detect any associations of the investigated
complement genes, most likely due to the small effect size of most
susceptibility genes for SAD. An interesting question is how many risk
alleles a person can have, but not develop AD. Are the risks additive or do
they work in synergy? Perhaps different forms of AD can be distinguished by
specific sets of susceptibility genes. To test this holistic hypothesis a very
large material would be necessary, since most susceptibility genes are quite
uncommon. A way to reduce the sample size, however, would perhaps be to
only include patients with known family history.
Be that as it may, the answer to the puzzle of AD will most likely be
centred on synaptic function, and include the terms age and genetics.
Synaptic elimination and the complement system in Alzheimer’s disease
42
ACKNOWLEDGEMENT
The work on this thesis was made at the Department of Psychiatry and
Neurochemistry, as well as the Department of Physiology at the institute of
Neuroscience and Physiology, Sahlgrenska Academy at the University of
Gothenburg. I would like to thank all who have made this possible, in
particularly:
Henrik Zetterberg – my main supervisor. Your enthusiasm, optimism and
ability to get things done is absolutely astonishing. Without you there would
be no thesis. Claiming victory in advance!
Eric Hanse – my main co-supervisor, but as the years have passed I have
come to regard you more as friend. I have literally put my life in your hands.
As a scientist and teacher you set a great example, and I am really thankful
for everything!
Pontus Wasling – my co-supervisor. When things weren’t really working
out, you were the first to acknowledge it, and you showed some much
appreciated supervising skills. Thanks!
Big thanks to everyone at the third floor and to all my collaborators!
I especially need to thank: My – supervisor, colleague, friend. You taught me
the craft of patch-clamping, filled me up with wine, let me sleep on your
couch when I lost my keys etc. etc. A good friend made of the right stuff to
become a good supervisor! Jocke – my main field-recording fellow. Sharing,
angst burgers, beer, running, etc. Ilse – thanks for sharing your room,
conversations about food, gardening and other non-work related things. Elin
– my partner in doctoral angst. Andreas – realising my dreams of the
thunder-honey effect, hang in there! Marta – all those hours in that cold
room, thanks for persevering! Malin – my genetics sensei. Thank you!
Finally I want to thank my family and friends for making my life easy and
pleasant when not at work. A little extra emphasis on: Mamma, Morfar,
Ellinor, Tina, Martin and Henke.
43
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