JUN 27, 2018 10:28 AM PDT

Immune Cells Responsible for Chemo-induced Diarrhea

WRITTEN BY: Kara Marker

While studying specific immune cells in the context of chronic itching in the skin, two Washington University School of Medicine scientists discovered that the immune system, rather than the nervous system, is responsible for the uncomfortable and sometimes severe diarrhea that accompanies chemotherapy.

Macrophages trigger smooth muscle contractions in the GI tract. Credit: Center for the Study of Itch

With the results from their new study, these scientists hope that they can develop new ways to treat diarrhea, both in chemotherapy patients and people with diarrhea as a result of gastrointestinal (GI) tract disease.

Diarrhea as a result of chemotherapy is extremely common, afflicting up to 80 percent of chemo patients. In general, diarrhea is a results of abnormal contractions during food digestion in the smooth muscle tissue lining the GI tract. At its worst, diarrhea can be life-threatening or cause cancer patients to quit receiving chemo treatments. People with irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) experience similar diarrhea.

"Diarrhea is a common side effect of chemotherapy that, in severe cases, can lead to death or to patients having to stop lifesaving treatment because often there are no effective therapies to control the diarrhea," explained co-senior investigator Hongzhen Hu, PhD. "This research provides a new avenue to explore in developing drugs to stop such diarrhea."

For a while, scientists thought that nerve cells in the intestines were responsible for chemo-induced diarrhea. But it might actually instead be immune cells called macrophages that are triggering intestinal contractions - the nervous system doesn’t seem to be involved at all.

There are more macrophages in the GI tract than anywhere else in the body. Macrophages are phagocytic cells, which means they engulf dead and dying cells and pathogens and digest them. This process of phagocytosis is an important part of the immune response to infection, cancer, and inflammation.

Researchers discovered that surface receptor TRPV4 on macrophages. The receptor was previously thought to be associated with nerve cells. With TRPV4’s association with GI contractions, the nervous system had been implicated in causing diarrhea.

"We found that the macrophages themselves trigger muscle contractions in the gut without any involvement from neurons," Hu said. "The pathway works in an entirely different way from what we had expected."

The present study was published in the journal Immunity.

Sources: Chemocare, Washington University School of Medicine

About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog: ScienceKara.com.
You May Also Like
OCT 09, 2018
Immunology
OCT 09, 2018
Allergen Labeling
Are the regulations for packaged foods strong enough? A recent investigation suggests allergens are not properly identified on food packaging...
OCT 30, 2018
Drug Discovery
OCT 30, 2018
Re-sensitizing Drug-resistant Human Tumor Cells
Understanding how cancer cells avoid death despite their DNA being damaged will create new strategies to enhance cancer cell killing through chemotherapy t...
NOV 13, 2018
Immunology
NOV 13, 2018
Yin & Yang: The Duality of Cancer-Associated Fibroblasts in Pancreatic Cancer
Pancreatic Cancer is a devastating disease. Fifty-five thousand new patients were diagnosed this year in the United States (1). It is painful and usua...
NOV 20, 2018
Immunology
NOV 20, 2018
Mutations Mutations Which Ones Do We Want?
A team at UCSF makes use of new SLICE tool to generate mutations that reveal specific genetic functions....
NOV 30, 2018
Microbiology
NOV 30, 2018
C-Section Deliveries Disrupt the Transmission of Microbes From Mom to Baby
From our earliest days, bacteria exert a powerful influence on many aspects of our health....
DEC 20, 2018
Health & Medicine
DEC 20, 2018
Common Medication Regimens for Sarcoidosis
Sarcoidosis is a granulomatous disease that most commonly affects the lungs, but any organ system can be involved. It is most often found and diagnosed in...
Loading Comments...