Undercovering link between cardiovascular disease and sleep apnoea

With an increasing number of people losing their lives to heart disease each year, researchers from the Kolling Institute have launched a first of its kind study using MRI technology to broaden scientific understanding of the link between cardiovascular disease and sleep apnoea.

The new study follows latest figures showing cardiovascular disease is the leading cause of death worldwide, killing one Australian every 12 minutes.

This makes the research important and timely, especially given that obstructive sleep apnoea is also increasing and now affects around one billion people. Known as the silent killer, this chronic disease causes low oxygen levels, sleep disturbance and dangerous pressure inside the chest.

Meet the team searching for answers

Royal North Shore Hospital respiratory and sleep medicine specialist Professor Peter Cistulli will lead the study, collaborating with RNSH Head of Respiratory and Sleep Medicine Dr Ben Harris, and Kolling Institute researchers Professor Martin Ugander and Dr Rebecca Kozor, who are experts in cardiac imaging.

The team behind the new study
Meet the team: Nina Sarkissian, Prof Martin Ugander, Prof Peter Cistulli, Dr Ben Harris and Dr Rebecca Kozor

Professor Cistulli said obstructive sleep apnoea has been linked to the development of cardiovascular disease, including hypertension, heart attack, atrial fibrillation and stroke – but there have been no randomised controlled trials confirming a causal link between the two.

“We hope our project will provide definitive evidence of the relationship between sleep apnoea and cardiovascular disease, closing our existing gaps in knowledge and informing future treatment approaches,” he said.

Nina Sarkissian, Director of Research Development for the Sleep Research Group across the Charles Perkins Centre and Royal North Shore Hospital, plays a key role in developing such cross-disciplinary collaborative research programs.

She said “Our CardioSleep Program will be unique, uniting three major disciplines of cardiology, respiratory and sleep medicine, and radiology to develop a precision medicine approach. This will help define which patients are at greatest risk and require personalised treatment.”

“We would like to see this valuable research program drive a new approach, and one which will dramatically reduce the number of people who lose their lives prematurely with a combination of sleep apnoea and cardiovascular disease.”

Nina Sarkissian

The project has been made possible following funding from the Ramsay Research Grant Program.

Blood test measures healthy aging in humans

SAHMRI researchers are the first in the world to develop a ground-breaking new blood test to measure autophagy, the body’s process of recycling unwanted or damaged cells to stay healthy.

The research study, which sheds light on autophagy in humans like never before, has been published in the journal Autophagy.

A peek into biological aging

Dr Tim Sargeant, Neurobiologist at the South Australian Health and Medical Research Institute (SAHMRI), said the effectiveness of autophagy in an individual is the strongest indicator of how well they will age.

“Previous studies have shown that the better autophagy is, the less prone the individual will be to cancer and chronic disease.”

“We think the higher you score on this blood test, the longer you’re likely to live and live well.”

Dr Sargeant

Researchers are confident autophagy holds the key to improving outcomes for those with incurable neurological diseases like dementia by signalling risk factors for the condition earlier.

“If we can learn more about what causes the process of autophagy to stop and start, we can work towards creating life-changing interventions.”

Findings significant in other health fields

Dr Tim Sargeant
Dr Tim Sargeant

The research development is also greatly significant to the future of nutrition and dieting.

It’s widely held that factors such as food and fasting influence autophagy in the body, but science hasn’t been able to prove it in humans, until now. 

“This will lead to us being able to point definitively to what kind of fasting is most effective for people and exactly how much exercise they need to do to increase their autophagy,” explained Dr Sargeant.

“In our view, this is the new frontier of health research and our blood test is really the first step that opens the door to a new world.” 

How the test works

The test involves taking a person’s blood and splitting it into two tubes.

The chemical chloroquine is then added to one of the tubes to stop the autophagy process and by comparing this to the other sample, it’s possible to gage how efficiently autophagy is working.

The test is currently in the early stages of development and requires further investigation into its viability for use with patients.

Researchers are optimistic that autophagy measurement will eventually be included in the standard health check-up, like blood pressure and cholesterol tests.

“Our aim is for the blood test to provide clinicians with a baseline from which to experiment with preventative strategies to increase autophagy in their patients; including everything from lifestyle adjustments to drugs.”

The research was carried out in partnership with collaborators at SAHMRI and the University of Adelaide.

The team are currently undertaking investigations that focus on using the test to measure autophagy in those living with a wide range of diseases, with the aim of understanding how this impacts the disease process.

Chance meeting leads to research breakthrough

When WEHI clinician-researcher Dr Charlotte Slade met Cynthia Agius, neither knew it would lead to a research breakthrough and a lasting friendship.

Charlotte

I met Cynthia 10 years ago when I was an immunology and allergy registrar at the Royal Melbourne Hospital. I was struck by what an upbeat person she was, despite having to come into hospital regularly. She was always friendly and grateful to the hospital staff for the care she received. Throughout everything, she has remained positive.

Cynthia has CVID or common variable immune deficiency. It is a condition that impairs the immune system. People with CVID are more susceptible to infection and can develop autoimmune and inflammatory diseases. Meeting Cynthia, and others like her, made me want to learn more about what caused the disorder.

I recruited Cynthia to our research study at WEHI in 2014. I was curious to find out why some patients with CVID developed more severe disease, while others did not. I had a strong suspicion Cynthia’s condition was genetic. Her mother also had CVID and we found that many of her mother’s relatives also had the condition.

“Through our research at WEHI, we discovered that Cynthia’s condition was caused by a mutation in a gene called NFKB1. Pinpointing the exact cause of her condition and being able to explain that to her family was rewarding.”

Charlotte Slade

We screened her children to see if they had inherited the mutated gene and learned that one of her children, a daughter, had inherited the gene, as well as her five-year-old granddaughter.

L to R: Photo of Dr Charlotte Slade (Postgraduate Student; Immunogenetics Research Team; Immunology Division) and patient Cynthia Agius.

Working with Cynthia and her family has taught me a lot about the types of conditions gene mutations can cause. The information about the mutated NFKB1 gene and the ability to screen for it will help people to make better informed choices about their life.

Having a relationship with Cynthia has spurred me on to find answers that might be beneficial for her treatment, or for her children and grandchildren. When you have a personal relationship with your patients, you can’t help going that extra mile for them.

Cynthia

I was diagnosed with CVID 23 years ago. Not long after, my mother was also diagnosed. We didn’t realise it at the time, but many of her 18 brothers and sisters in the Netherlands, and some of their children, also had the condition.

I’d had a lot of infections, but they were always put down to other things. I was getting sinus and chest infections and was in hospital three times a year with pneumonia. Nobody was able to pinpoint the cause. It was not until they realised my immunoglobulin (Ig) levels had dropped to zero that I was sent to see an immunologist and put on monthly infusions of antibody treatments.

Charlotte was one of the registrars at the immunology clinic and we bonded instantly. A few years later, Charlotte asked me to be part of some research she was doing at WEHI. I was honoured to be involved.

Finding out that my CVID was caused by a genetic mutation was a relief in some ways. I am glad that my children were able to be screened. My daughter was diagnosed at a younger age than me, so hopefully she will be better able to better manage her condition.

“It was a breakthrough that Charlotte discovered the mutant gene in our family. Having this information can help patients and doctors make better informed decisions about treatments.”

Cynthia Agius

I have gone through a lot with this condition, but I hope this makes things easier for other families like mine.

Charlotte is a beautiful, caring person. She is more than just a doctor; she has become a friend. We have a special bond that I think will last for many years to come.