Journal News

JLR: Finding the structure of a lipid that keeps our tears clear

Laurel Oldach
Sept. 1, 2018

Because humans evolved from the sea, we carry a little of it with us to stay alive. Salt water makes up the cytoplasm in our cells, the plasma in our blood and the tears in our eyes.

This image by first author Sarah Hancock shows an iris surrounded by the lipid she and colleagues in the Blanksby and Mitchell labs characterized by mass spectronomy.Journal of Lipid Research

But water alone isn’t enough to keep the eye from drying out. A microscopically thin film of oils known as the lipid layer protects the tear film from evaporating. In the August issue of the Journal of Lipid Research, a group of Australian researchers reports the structure of a key long-chain lipid in this layer. Their finding may be used to improve treatments for dry eye.

Although the long-chain lipids in question make up just 5 percent 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.

Blanksby saw the earlier research in Langmuir troughs 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 by 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 nuclear magnetic resonance spectroscopy.

Complicating matters, the team needed to differentiate between isomers. They knew the long lipids were 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 they pinpointed each of its double bonds. The mass spectrometrists handed off the structure to chemist colleagues led by Michael Kelso, who developed a method to synthesize it.

The team now is working with industry partner Allergan, which cofunded 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.

Blanksby hopes that by creating a better match to the real tear film, blurriness and other side effects of using eye drops can be alleviated.

Enjoy reading ASBMB Today?

Become a member to receive the print edition four times a year and the digital edition monthly.

Learn more
Laurel Oldach

Laurel Oldach is a former science writer for the ASBMB.

Get the latest from ASBMB Today

Enter your email address, and we’ll send you a weekly email with recent articles, interviews and more.

Latest in Science

Science highlights or most popular articles

Spider-like proteins spin defenses to control immunity
News

Spider-like proteins spin defenses to control immunity

Oct. 17, 2025

Researchers from Utrecht University discovered two distinct binding modes of a spider-shaped immune inhibitor found in serum.

A biological camera: How AI is transforming retinal imaging
Feature

A biological camera: How AI is transforming retinal imaging

Oct. 15, 2025

AI is helping clinicians see a more detailed view into the eye, allowing them to detect diabetic retinopathy earlier and expand access through tele-ophthalmology. These advances could help millions see a clearer future.

AI in the lab: The power of smarter questions
Essay

AI in the lab: The power of smarter questions

Oct. 14, 2025

An assistant professor discusses AI's evolution from a buzzword to a trusted research partner. It helps streamline reviews, troubleshoot code, save time and spark ideas, but its success relies on combining AI with expertise and critical thinking.

Training AI to uncover novel antimicrobials
Feature

Training AI to uncover novel antimicrobials

Oct. 9, 2025

Antibiotic resistance kills millions, but César de la Fuente’s lab is fighting back. By pairing AI with human insight, researchers are uncovering hidden antimicrobial peptides across the tree of life with a 93% success rate against deadly pathogens.

AI-designed biomarker improves malaria diagnostics
Journal News

AI-designed biomarker improves malaria diagnostics

Oct. 8, 2025

Researchers from the University of Melbourne engineered Plasmodium vivax diagnostic protein with enhanced yield and stability while preserving antibody-binding, paving the way for more reliable malaria testing.

Matrix metalloproteinase inhibitor reduces cancer invasion
Journal News

Matrix metalloproteinase inhibitor reduces cancer invasion

Oct. 8, 2025

Scientists at the Mayo Clinic engineered a TIMP-1 protein variant that selectively inhibits MMP-9 and reduces invasion of triple-negative breast cancer cells, offering a promising tool for targeted cancer research.