Investigating the effects of cooling on neurons | The Icelandic Health Science Institute

6. June 2023

"In medicine, cooling therapy is used as a neuroprotective treatment for serious conditions, e.g. following birth asphyxia or cardiac arrest. Cooling seems to protect neurons from damage that would otherwise have occurred after restricted blood flow, but the process behind this effect is poorly understood," explains Salvör Rafnsdóttir, medical doctor and PhD student. She is currently working on a study investigating which of the body's mechanisms and genes are activated when cells are cooled to 32°C. Salvör and her team have also identified a promising drug that seems to activate the body's cooling response without actually cooling. This discovery recently earned the team first prize in the 2023 University of Iceland Science and Innovation Competition.

Salvör completed her medical degree at the University of Iceland. The research experience she acquired as a student and her interest in disease progression and genetics led her to the University of Iceland Biomedical Centre, home to basic research into a wide range of diseases and processes in the body. She is now working towards her PhD at the laboratory of Hans Tómas Björnsson, professor at the Faculty of Medicine.

"I am extremely interested in linking basic research, including animal research and cell research, with medical innovations. This area of medicine is known as translational medicine. The goal of translational medicine is to convert research findings into benefits for patients as quickly as possible. Scientists research diseases or clinical conditions in cells or animals, hoping to identify new mechanisms that can be targeted or drugs that can activate known mechanisms or genes. These discoveries can push the boundaries of existing treatments or find new drugs, which means improved treatment for patients," explains Salvör, who was introduced to basic research early in her medical degree.

Inspired by summer jobs in the lab
"I spent the summers after my first two years of medicine working in Professor Jón Jóhannes Jónsson's laboratory and I found that I enjoyed lab research. When it was time for me to decide on a third-year research project, I got in touch with the doctor and research scientist Hans Tómas Björnsson, who then had a lab at Johns Hopkins University in the US. I was very keen to experience working in a lab that was part of a large international hospital. I was lucky enough to be offered a position and he gave me a choice of several projects. In the end, I decided to look at epigenetics and cooling," says Salvör.

It was this work that inspired her current PhD project. "When Hans Tómas came home and moved part of his lab back to Iceland, I was just finishing my medical degree and he offered me a position as a PhD student. I had been thinking about my old BS research project and was interested in exploring that further, so I agreed," says Salvör. Other staff and students at Hans Tómas' lab at the University of Iceland and Johns Hopkins University are also involved in the project, which is a collaboration with deCODE genetics.

Hans Tómas Björnsson's Research team: Kijin Jang PhD student, Juan Ouyang PhD student, Meghna Vinod technician, Tinna Reynisdóttir PhD student, Katrín Möller Postdoc, Sara Þöll Halldórsdóttir PhD student, Agnes Ulfig Postdoc, Arnhildur Tómasdóttir technician, Hans Tómas Björnsson Professor, Kaan Okay PhD student and Jóhann Örn Thorarensen Master's student. Missing on the photo are Kimberley Jade Anderson Laboratory Manager, Salvör Rafnsdóttir PhD student, Laufey Halla Atladóttir Medical student, Katrínu Wang Medical student and Valdimar Sveinsson Medical student.

Looking for genes that affect cooling
The hypothesis for the project is that activating cooling mechanisms in the cells delivers the benefits of cooling therapy, i.e. neuroprotection, but Salvör explains that, unlike heat generation mechanisms, cooling mechanisms are rather ill defined.
"To find answers to our research questions, we are using two kinds of methodology, both based around cell cultures. Firstly, we screen cells for mutations using the CRISPR-Cas9 tool, which gives us information about how other genes affect the key genes in the cooling response. This experiment is like performing 100,000 experiments, in which we deactivate one gene in each cell and do that for all known genes in the human genome. Next, we pick out the cells where activation of cooling mechanisms was changed and find out which gene was deactivated. We then confirm the effect with further experiments. We hope that this will enable us to identify which genes are involved in cooling, either activating or inhibiting the process. Secondly, we have screened almost 2,000 drugs and identified a drug that seems to activate the body's cooling mechanisms," explains Salvör.

The team is also using mutation screening to identify the genes that control cooling stimuli in mice. "We are screening to test whether mouse pups who have more mutations in their genomes than normal mice exhibit an abnormal baseline temperature with and without an environmental cooling stimulus. Next, we sequence the mice in order to identify likely mutations that cause an abnormal baseline temperature or an abnormal response to cooling stimuli," says Salvör.

A drug that could prevent nerve damage
The findings of the first part of the PhD project suggest that the drug Entacapone could potentially activate the body's cooling mechanisms to some extent. "We also found that the gene SMYD5 seems to inhibit cooling mechanisms at a normal temperature, but when we cool the cells, this effect seems to disappear. This gene could therefore be a new target for measuring activation of cooling mechanisms. We have applied for patents for these two discoveries and we have also published a preprint on bioRxiv about our findings,“ says Salvör. She and her colleagues plan to submit the paper to a peer-reviewed journal in the next few days. "We have found some genes that seem to cause abnormal base temperatures and abnormal responses to environmental cooling stimuli, but we are still working on the findings of this part of the project."

According to Salvör, studies like this could deliver huge benefits for people with nerve damage, at risk of nerve damage or living with chronic neuropathic pain. "If cooling reduces nerve damage by activating the body's natural cooling mechanisms and it is the changes to gene expression themselves that reduce nerve damage, it would be extremely helpful to understand and be able to activate this system. This could lead to further drug development for people with nerve damage, at risk of nerve damage or living with chronic neuropathic pain," she explains.

By developing drugs like this, it may be possible to manage neuroprotection more effectively and hopefully with fewer side effects. "Cooling therapy is challenging to manage and is therefore only used in the most serious cases. With a drug treatment, we could potentially control the dose more effectively. Then we could use the treatment for patients with less severe symptoms or those who have experienced side effects from cooling therapy. Hopefully a drug treatment would be easier to administer and could be given to patients outside ICUs, thereby benefiting a larger group," concludes Salvör.