Neutrophils found to be helpful, not harmful, after injury

October 6, 2017 by Bob Yirka report
Dynamic behavior of neutrophils inside sterile injury lesions. (A) Representative images of rapid accumulation of neutrophils in response to focal hepatic injury. Dashed lines highlight injury borders. Scale bars, 230 μm. (B) Representative images of collapsed vessels (arrows) inside the injury area. Scale bar, 10 μm. (C) Quantification of blood vessel diameters inside the injury lesion and in the healthy area (outside injury). Data pooled from three independent experiments. (D) Representative image of neutrophils inside the focal lesion at 12 hours post injury. Higher magnification of the indicated area (white dashed line box) is shown on the right. Scale bar, 30 μm. ****P < 0.0001 [analysis of variance (ANOVA) with Bonferroni’s post hoc test]. Credit: (c) Science (2017). DOI: 10.1126/science.aam9690

(Medical Xpress)—An international team of researchers has found that neutrophils play an important role in wound cleanup rather than causing unnecessary inflammation. In their paper published in the journal Science, the group describes studying the activities of neutrophils in real time with injured mice. Hannah Garner and Karin de Visser with the Netherlands Cancer Institute offer a Perspective piece on the work done by the team in the same journal issue.

For some time, medical researchers have known that offer benefits in responding to injury, but they also believed that neutrophils were detrimental in some patients—immune cells were thought to contribute to unnecessary inflammation, making it more difficult for patients to recover from injuries. As a result, researchers have sought to reduce the actions of neutrophils to speed recovery in traumatized patients. Now, it appears such work may actually have been in vain, as this new effort shows that rather than causing problems, neutrophils actually only help in wound repair.

To learn about the true role of neutrophils as the body reacts to injury, the researchers inflicted burn injuries on test mice and then watched what happened using intravital imaging. They found that rather than causing unnecessary inflammation, the cells initially took apart blood vessels that had collapsed. Several hours later, they were seen picking up damaged DNA fragments. Furthermore, all of the cells moved out and away from the site of the injury within 14 to 16 hours. The team also observed that when they killed the neutrophils, the site of injury contained more debris than sites that with active neutrophils. The researchers continued monitoring the neutrophils and found that a day after an injury had occurred, most of the had migrated to bone marrow and were in the process of apoptosis—those few that had not migrated to bone marrow were found in the lungs, but were not causing any problems.

With these new findings, as Garner and de Visser note, more research will likely be conducted regarding the role that neutrophils play in repair and suggest that they might lead researchers to new ways of improving treatment of injured patients.

Explore further: Team discovers how to train damaging inflammatory cells to promote repair after stroke

More information: Jing Wang et al. Visualizing the function and fate of neutrophils in sterile injury and repair, Science (2017). DOI: 10.1126/science.aam9690

Abstract
Neutrophils have been implicated as harmful cells in a variety of inappropriate inflammatory conditions where they injure the host, leading to the death of the neutrophils and their subsequent phagocytosis by monocytes and macrophages. Here we show that in a fully repairing sterile thermal hepatic injury, neutrophils also penetrate the injury site and perform the critical tasks of dismantling injured vessels and creating channels for new vascular regrowth. Upon completion of these tasks, they neither die at the injury site nor are phagocytosed. Instead, many of these neutrophils reenter the vasculature and have a preprogrammed journey that entails a sojourn in the lungs to up-regulate CXCR4 (C-X-C motif chemokine receptor 4) before entering the bone marrow, where they undergo apoptosis.

Related Stories

Team discovers how to train damaging inflammatory cells to promote repair after stroke

September 19, 2017
White blood cells called neutrophils are like soldiers in your body that form in the bone marrow and at the first sign of microbial attack, head for the site of injury just as fast as they can to neutralize invading bacteria ...

Immune study points to new ways to treat lung disease

August 14, 2017
Fresh insight into how the immune system keeps itself in check could lead to new ways of fighting chronic lung disease.

Immune cells interact in surprising ways when responding to skin injuries

June 10, 2015
When skin is injured or exposed to a pathogen attack, the body's immune system responds rapidly. But the exact skin-cell-based mechanisms behind these responses remain unclear. Now, A*STAR researchers have uncovered how skin-localized ...

Heart-resident macrophages call in neutrophils following ischemic injury

August 4, 2016
Tissue injury, such as occurs in response to a lack of oxygen, promotes an influx of immune cells to the site of damage. After an ischemic injury to the heart, such as occurs after a heart attack or heart transplant, these ...

Study identifies gene—and drug target—involved in inflammation after injury

June 21, 2017
During a stroke or organ transplant, patients can suffer an injury due to lack of blood supply to vital organs. The injury—known as ischemia reperfusion—can cause damage to tissues. But a new Yale-led study has identified ...

Rogue blood cells may contribute to post-surgery organ damage

June 26, 2011
A study from scientists at Queen Mary, University of London, sheds new light on why people who experience serious trauma or go through major surgery, can suffer organ damage in parts of the body which are seemingly unconnected ...

Recommended for you

Tracing cell death pathway points to drug targets for brain damage, kidney injury, asthma

October 19, 2017
University of Pittsburgh scientists are unlocking the complexities of a recently discovered cell death process that plays a key role in health and disease, and new findings link their discovery to asthma, kidney injury and ...

Scientists find where HIV 'hides' to evade detection by the immune system

October 19, 2017
In a decades-long game of hide and seek, scientists from Sydney's Westmead Institute for Medical Research have confirmed for the very first time the specific immune memory T-cells where infectious HIV 'hides' in the human ...

Researchers release the brakes on the immune system

October 18, 2017
Many tumors possess mechanisms to avoid destruction by the immune system. For instance, they misuse the natural "brakes" in the immune defense mechanism that normally prevent an excessive immune response. Researchers at the ...

Gene transcription in virus-specific CD8 T cells differentiates chronic from resolving HCV

October 17, 2017
Massachusetts General Hospital (MGH) investigators have identified differences in gene transcription within key immune cells that may distinguish those individuals infected with the hepatitis C virus (HCV) who develop chronic ...

How cytoplasmic DNA triggers inflammation in human cells

October 17, 2017
A team led by LMU's Veit Hornung has elucidated the mechanism by which human cells induce inflammation upon detection of cytoplasmic DNA. Notably, the signal network involved differs from that used in the same context in ...

Early trials show potential for treating hay fever with grass protein fragments

October 13, 2017
Protein fragments taken from grass can help protect hay fever patients from allergic reactions to pollen grains.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.