Nav: Home

Scientists determine the structure of a lipid that keeps our tears clear

August 07, 2018

As anyone who has experienced an annoying alternation between dry and watery eyes can confirm, tears alone aren't enough to keep the eye from drying out. A microscopically thin film of oils known as the tear film lipid layer is key to preventing the tear film from evaporating. In this month's issue of the Journal of Lipid Research, a group of Australian researchers report the structure of a key long-chain lipid in the tear film lipid layer. Their finding may be used to improve treatments for dry eye.

Although the long-chain lipids in question make up just 5% of the tear film lipid layer, they play an important role in vision. Without them, earlier studies showed, the lipid layer would resemble an oil slick atop a puddle. "This clearly wouldn't be satisfactory for you to look through," said Stephen Blanksby, a professor at the Queensland University of Technology who led the research team in this study. He saw the Langmuir trough research, carried out by others, as a prompt to determine the precise structure of the ultra-long-chain lipids of the eye.

The tear film lipid layer comes from meibum, secreted from the lower eyelid. Scientists can collect meibum samples from brave volunteers by running a small spatula gently over their lower lids, but it is difficult to obtain enough for conventional assays like NMR.

Complicating matters, the team needed to differentiate between isomers. They knew long lipid was made of two fatty acids, but not whether they were joined end-to-end or branched, a question conventional mass spectrometry couldn't answer.

Fortunately, Blanksby and colleague Todd Mitchell of the University of Wollongong have spent the last decade fine-tuning mass spectrometric techniques to characterize lipids. "We were able to bring a unique toolbox to bear," said Blanksby. "Some of these techniques may not exist outside Todd's and my laboratory."

By incorporating established approaches, such as ozonolysis, into a mass spectrometry workflow, the team determined that the most abundant of the ultra-long lipids is joined end-to-end, and pinpointed each of its double bonds. The mass spectrometers handed off the structure to chemist colleagues led by Michael Kelso, who developed a method to synthesize it.

The team is now working with industry partner Allergan, which co-funded the research with the Australian Research Council, on incorporating the new synthetic long-chain lipid as a component of drops for dry eye. While our knowledge of the lipid layer has expanded, according to Blanksby many eye drops still use mineral oil. "This type of work provides a framework to produce a product that mimics, and is based on, the actual components that are present in human tears," he said. He hopes that by creating a better match to the real tear film, blurriness and other side effects of using eye drops can be alleviated.
-end-
About the Journal of Lipid Research:

The Journal of Lipid Research (JLR) is the most-cited journal devoted to lipids in the world. For over 50 years, it has focused on the science of lipids in health and disease. The JLR aims to be on the forefront of the emerging areas of genomics, proteomics, and lipidomics as they relate to lipid metabolism and function. For more information about JLR, visit http://www.jlr.org.

American Society for Biochemistry and Molecular Biology

Related Research Articles:

More Research News and Research Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Sound And Silence
Sound surrounds us, from cacophony even to silence. But depending on how we hear, the world can be a different auditory experience for each of us. This hour, TED speakers explore the science of sound. Guests on the show include NPR All Things Considered host Mary Louise Kelly, neuroscientist Jim Hudspeth, writer Rebecca Knill, and sound designer Dallas Taylor.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

Kittens Kick The Giggly Blue Robot All Summer
With the recent passing of Ruth Bader Ginsburg, there's been a lot of debate about how much power the Supreme Court should really have. We think of the Supreme Court justices as all-powerful beings, issuing momentous rulings from on high. But they haven't always been so, you know, supreme. On this episode, we go all the way back to the case that, in a lot of ways, started it all.  Support Radiolab by becoming a member today at Radiolab.org/donate.