If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Tick protein keeps tabs on inflammation

Researchers use a protein derived from tick salivary glands to image inflammatory molecules that promote atherosclerosis

by Alla Katsnelson, special to C&EN
March 26, 2020 | A version of this story appeared in Volume 98, Issue 12


Photograph of a tick on a white background.
Credit: Bioconj. Chem.
Ticks produce a protein that binds to inflammatory molecules to tamp down the inflammatory response of their host during a tick bite.

A protein derived from the salivary glands of ticks homes in on immune molecules called chemokines that promote atherosclerosis, a new study shows (Bioconj. Chem.2020, DOI: 10.1021/acs.bioconjchem.0c00095). By attaching a fluorescent marker to a synthetic version of the protein, called Evasin-3, researchers were able to visualize inflammation on tissue inside arteries.

“I was very intrigued that we could use nature for imaging human diseases,” says study leader Ingrid Dijkgraaf, a biochemist at the Cardiovascular Research Institute of Maastricht University.

In atherosclerosis, fatty acids glom on to the artery wall, activating a rush of immune response, including chemokines. Imaging techniques such as ultrasound or positron emission tomography (PET) can visualize the fatty plaques themselves, but not the inflammatory processes that make them dangerous. That capability would help clinicians differentiate between disease-causing plaques, which can rupture and cause a blood clot, and those that accumulate normally in the course of aging, Dijkgraaf explains.

Schematic showing how a fluorescent-labeled tick protein can bind to inflammatory molecules in plaques in a blood vessel wall and fluoresce.
Credit: Bioconj. Chem.
Tick proteins (red) bound to a fluorescence marker (green) bind to a marker of inflammation (blue) within lipids (gray) in a blood vessel wall.

The researchers conscripted Evasin-3 for the job because this tick protein naturally binds to chemokines to suppress the host immune system. They chemically synthesized a version of the protein in which a carbohydrate group was replaced with a green fluorescent marker. When they delivered an inflammation-triggering lipid to an intact section of a mouse carotid artery along with the fluorescent tick protein, the tissue turned green, lighting up the accumulation of chemokines on the scene. “If there’s a high expression of these chemokines, we see our protein accumulating there,” Dijkgraaf says.

The researchers next plan to test the approach in a mouse model of atherosclerosis. They also plan to replace the fluorescent marker, which cannot be visualized deep in tissue, with a radioactive label that can be used for PET imaging in humans.



This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.