Fighting Brain pollution
Every year, about 200,000 people in Germany develop Alzheimer's disease, a condition that is as of yet incurable. Scientists from all over the world are searching for the causes in order to decipher the disease and develop effective drugs. One of them is Annette Limke. She has a doctorate in biology and is investigating the effects of ultra-fine particulate on the risk of Alzheimer's disease. An interview with the 32-year-old about exhaust fumes, the goal of her research project and her love of nature.
Did you always want to be a scientist?
No, I took biology as an A-level subject at school but my interests were varied. So I also could have well imagined becoming a sports teacher, but in the end, I decided on biology.
So why did you become an Alzheimer's researcher?
Because I want to contribute to the prevention and cure of neurodegenerative diseases such as Alzheimer's dementia, Parkinson's disease or Huntington's disease. I feel very privileged when I sit at my microscope in the lab and help to identify potential environmental risk factors such as exhaust gases from traffic, industry and households. And thus, track down their mechanisms for the development of amyloid diseases such as Alzheimer's. In this disease, more and more nerve cells gradually die. Those affected therefore suffer from memory loss and disorientation.
As a student, you lived with your husband in the neighbourhood of Corneliusstraße - one of the streets in Düsseldorf with the highest levels of particulate matter. Was that the reason why you moved to Solingen?
The location in the middle of the city with the tram stop virtually on the doorstep is great. If it weren't for the permanently bad air. Every time after a trip to the countryside or after a holiday, we found it particularly annoying.
The object of her research is transparent, only one millimetre in size and barely visible to the naked eye: the nematode C. elegans. Stained green are dopaminergic neurons that are involved in the worm's movement.
Polluted air - exhaust fumes from traffic, industry and households - makes people ill, as many studies have shown. Can you explain your research approach?
There is increasing evidence that tiny particles from car traffic - so-called nanoparticles - not only have a negative effect on the respiratory tract, but also on the brain. Cognitive deficits have been demonstrated in people living near busy roads. In densely populated areas with particularly polluted air, nanoparticles from car exhaust gases have been detected in the brain. In order to determine the air pollutants that could promote Alzheimer's, I conduct experiments on the one-millimetre small, transparent nematode Caenorhabditis elegans and expose it to various ultra-fine particles.
Why of all things is this tiny worm suitable for your project?
It has exactly 302 nerve cells, it can apparently learn and its genes are between 60 and 80 percent similar to those of humans.
What have you found out so far in the series of experiments?
These worms normally live for a maximum of three weeks. They can crawl, swim and orient themselves. However, under the influence of, for example, tiny particles, such as those found in the abrasion of car tyres, the worm ages prematurely. And: it loses its cognitive abilities, seems to forget what it has learned - which shows parallels to Alzheimer's disease. You belong to a six-member research group led by Professor Anna von Mikecz, who has been studying the effect of nanoparticles on humans for years. Because they are so small, nanoparticles can cross the blood-brain barrier and reach the central nervous system. With what consequences?
Biologist Annette Limke at her workplace. The microscope is one of her most important research utensils.
They can penetrate any tissue in the body - including the brain. We suspect that nanoparticles contribute to protein molecules clumping together there. This is a process that causes diseases such as Alzheimer's dementia. I am also investigating precisely these abnormal protein accumulations in nematodes and have so far been able to prove that particles of tyre abrasion cause nerve cells to die and promote the protein deposits typical of Alzheimer's disease. To simulate realistic conditions, the exposure to pollutants is subliminal and chronic over the entire life of the adult worm. The young, middle-aged and old nematodes are then examined for typical disease symptoms (beta-amyloid deposits, neuronal cell death and behavioural defects).
What is the goal of your research?
To gain new insights that make both the connections of disease development and new ways of prevention transparent. The ability of nanoparticles to cross the blood-brain barrier can also be used therapeutically - for example for drugs. With the help of my project, a test is to be developed that identifies the mode of action of the harmful substances and thus enables the development of Alzheimer's drugs.
The whole thing sounds time-consuming and very challenging. Is having patience one of the most important requirements in your job?
Indeed. Research means that when one answer is found, five new questions arise at once. Some test systems cannot be established as quickly as one would like. A healthy frustration tolerance helps here.
With the help of the fluorescence microscope, abnormal protein accumulations and the death of nerve cells in the worm can be observed.
What helps in such cases?
Just the fact that Alzheimer's research is relevant to humanity - we all belong to the risk group. That's why I hope that in ten years we will be able to offer many affected people various therapeutic approaches that will significantly improve their quality of life and that of their relatives.
How important are awards such as the Kurt Kaufmann Prize of the Alzheimer Research Initiative (AFI), which is worth 10,000 euros, for your studies?
Personally, the AFI funding enables me to intensify research into Alzheimer's risk factors in an innovative model organism. The funds can be used to pay for animal husbandry costs and laboratory materials such as micro-particles and chemicals.
“One crucial preventive option is to improve air quality in urban areas, for example by drastically reducing traffic-related emissions and maintaining and caring for green spaces in the city.”
Can prevention reduce the risk of developing dementia like Alzheimer's? What measures can be taken to minimise the risk of Alzheimer's disease?
One crucial preventive option is to improve air quality in urban areas, for example by drastically reducing traffic-related emissions and maintaining and caring for green spaces in the city. Other measures, such as a rapid coal phase-out and reducing emissions from agriculture, could improve air quality.
Has your lifestyle changed?
Definitely. I go through life with open eyes; I am more aware of nature. I do a lot of sport and now live with my husband, not in the middle of the countryside, but at least in an area with less traffic and a 30 km/h zone. •
Annette Limke
• Born in Poland in 1988, grew up in Dortmund, Bachelor's and Master's degree in biology at Heinrich Heine University.
• Beginning of 2021: Dissertation on the topic of "Chronic effects of nanoparticles on ageing processes, signalling pathways and neurodegeneration "passed magna cum laude.
• Since 2012, the research assistant has been conducting research at the Düsseldorf IUF - Leibniz Institute for Environmental Medicine Research - and was awarded the Kurt Kaufmann Prize of the non-profit Alzheimer Research Initiative (AFI).
Interview Dagmar Haas-Pilwat
Pictures Melanie Zanin