We already know that increased fat in the blood, often caused by obesity, isn't good news for our bodies. However, a new study identifies previously unknown dangers to our health that could be caused by higher levels of these blood fats.
The fats cause extra stress on muscle cells, causing damage to their structure and their function. What the latest research has discovered is that these stressed-out cells are also giving out a signal that can be passed on to other cells and cause more damage.
These signals take the form of molecules called ceramides. While their normal job is actually to reduce cell stress, in long-term metabolic diseases like type 2 diabetes, they can instead kill off cells and make the symptoms of the disease more severe.
Human muscle cells with nuclei in blue, and stress caused by ceramide signals in red. (Lee Roberts)
"Although this research is at an early stage, our discovery may form the basis of new therapies or therapeutic approaches to prevent the development of cardiovascular and metabolic diseases such as diabetes in people with elevated blood fats in obesity," says molecular physiologist Lee Roberts from the University of Leeds in the UK.
Using human skeletal muscle cells designed to mimic the cells of people with metabolic disease, the researchers were able to activate the ceramide signaling with the addition of a fatty acid known as palmitate.
When these cells were mixed with cells that hadn't been exposed to fats, they communicated with each other, transferring ceramides in packages called extracellular vesicles, which are naturally released from all cells. The same processes were observed in tests on mice and muscle cells taken from human volunteers.
While more research is required to understand what this newly identified wandering of ceramide means, we know that these molecules can be damaging to the body. The higher blood fats seem to make cells share out the stress with their neighbors.
Although the researchers acknowledge that there might be more as-yet-unknown factors at play, this messaging system is potentially one way in which people with obesity go on to develop further complications such as diabetes, through the stress sharing observed here.
The benefit of discovering this new transmission system is that it could give us a way to prevent these complications from developing, by somehow blocking the ceramides. For now though, that's a long way off, with more study needed before we can ascertain such treatments.
As the researchers note, rates of obesity have tripled since 1975, and the number of adults with obesity – each carrying higher levels of blood fats – is now 650 million people, according to the latest data from the World Health Organization (WHO).
"With obesity an ever-increasing epidemic, the burden of associated chronic disease such as type 2 diabetes necessitates new treatments," says Roberts.
"We hope the results of our research here open a new avenue for research to help address this growing concern."
The research has been published in Nature Communications.