Immune cells known as macrophages linked to growth of lymph vessels in eyes, scientists discover

September 01, 2005

Scientists at Schepens Eye Research Institute have discovered that a particular immune cell contributes to the growth of new lymph vessels, which aid in healing. This cell, known as a macrophage, is called in by the body during the wound healing process. The discovery of this new role for the macrophage, published in the September 2005 Journal of Clinical Investigation, may ultimately inspire innovative treatments for blinding eye disease, as well as for other diseases, such as cancer, that rely on the lymph vessels to spread abnormal cells throughout the body.

"This is a very significant finding," according to Joan Stein-Streilein, PhD, and Patricia A. D'Amore, PhD, senior authors of the study, Senior Scientists at SERI and members of the Departments of Medicine and Ophthalmology at Harvard Medical School, respectively. "It unlocks a whole new dimension in our understanding of these important cells."

The body uses lymph vessels to bring immune cells to an injured organ to carry away debris and fluid to aid healing. Lymph vessels can play a different kind of role in cancer, offering tumor cells a pathway for spreading to other body parts, in a process known as metastasis.

Macrophages are large white blood cells called in during wound healing to ingest foreign invaders such as bacteria. They can also present pieces of those intruders to the immune system to jump-start the immune response. Produced in the bone marrow, they can be found in almost all tissues of the body. Unlike many other parts of the body, the clear outer layer of the eye, known as the cornea, does not normally have lymph vessels, except when injury causes lymph vessels to sprout from the edge of the cornea to help heal the wound.

Dr. Kazuichi Maruyama, a post-doctoral fellow in D'Amore's and Stein-Streilein's laboratories at SERI, began to suspect a new connection between macrophages and lymph vessels while studying corneal transplants in mice. He became aware of lymph vessels that seemed to be forming "in place," away from those produced at the edge of the cornea. He also noticed that these lymph vessels disappeared after the wounds were healed. Because the cell structure of the new vessels resembled that of macrophages, he began to believe there might be a relationship.

In the JCI study, he tested this idea by placing sutures in the corneas of two groups of mice to create injuries that would induce a healing response. Then he gave one group of mice a drug to cause macrophages to commit suicide. When he examined the eyes of both groups, he found those given the drug did not grow as many lymph vessels as the control group without the drug.

The implications of this link between macrophages and lymph vessels are far-reaching, according to Stein-Streilein, D'Amore, and Maruyama.

D'Amore and Stein-Streilein believe that harnessing this newly found ability of the macrophages could lead to the creation of new drugs or therapies for eye disease. For instance, inducing new "temporary" lymph vessels in retinas could aid in treating diabetic retinopathy by removing fluids leaking from abnormal blood vessels. It is this leaking fluid, characteristic of diabetic retinopathy that can permanently damage the retina and vision.

Maruyama speculates that the involvement of macrophages in forming lymph vessels may be universal and may also be involved in spreading cancer. If that were the case, blocking macrophages from helping to grow lymph vessels could inhibit the spread of tumors.

The team is now researching the same process in skin wounds and cancer.
-end-
Schepens Eye Research Institute, and affiliate of Harvard Medical School, is the largest independent eye research institute in the world.

Schepens Eye Research Institute

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.