Microbiome of the Nerves in Endometriosis and Irritable Bowel Syndrome: Evidence from Stress Neurobiologist John Cryan

The tissues are black, red, and white-hot. They grow throughout the body, from the lower body to the organs such as the uterus and peritoneum.

The pain in the endometriosis can be removed once detected. But for up to half of people who opt for this, the pain returns or persists so intensely that they need surgery again within five years. “As surgeons and doctors, we want to remove lesions. Amira says that people’s pain remains more often than we like to report.

The pain experienced by people with endometriosis is not indicative of the number of lesions present and is vastly different between individuals. For some, the pain worsens during their period; for others, it lasts all month long. It can manifest as a throbbing pain that spreads through the body and can be felt all the way down to the bone.

This persistence of pain after the original stimuli have subsided or been removed is a key feature of many kinds of chronic pain. In some whole-body pain conditions, such as fibromyalgia, there is no clear cause. A desperate search for relief has been prompted by something tripping the pain system.

Cryan says human trials have shown that there is a light but significant analgesic effect on the pain in Irritable bowel syndrome. The evidence suggests the microbiome is playing a key role in pain. It is even possible that gut bacteria influence not only how neurons transmit pain, but also how those acute pain signals turn chronic.

Despite decades of work probing the connections between gut bacteria and visceral pain in IBS, “it’s been a slow evolution” to recognize the gut microbiome’s role, says stress neurobiologist John Cryan at University College Cork in Ireland.

The gut microbiome might have an effect on the perception of pain. Cryan says that his studies show that brain regions involved in pain-related emotional and cognitive functions, such as the anterior cingulate cortex, change with alterations in the gut microbiome. He believes that signals from the microbiome can affect how pain is perceived in the brain. We are only scratching the surface.

Maddern studies nerve pathways in visceral pain. She was shocked when she learned that there was little known about how to treat pain and how to prevent it. In the past few years, scientists have begun modelling the pain of endometriosis and similar conditions in animal models. The pain of endometriosis has not been emphasized in most of the research, instead focusing on what causes the disease and how it grows.

Starting in 2020, 72 people with endometriosis randomly received either low-dose metronidazole or a placebo for two weeks. The two groups didn’t show differences in pain for six weeks after the surgery. Participants in the trial will report their pain problems six months after surgery and every five years, which is relevant to chronic pain.

In a 2023 study, the team found that people with fibromyalgia also had lower levels of specific bile acids in their blood compared with healthy controls15. People with Fibromyalgia tend to have less bile acids produced by gutbacteria. There is a possibility that some of the bile acids bind to nerves in the spine that help suppress pain. Without them, pain might flare unchecked. The levels of bile acids were found to correlate with pain in Fibromyalgia.

An Algorithmic Perspective on Pain Management in the Twenty-First Century: The Case of Male Mice in the Pacira Biosciences Inc.

A lot of people try to control physical pain. The global over-the-counter analgesics market was estimated to be worth just over US$28 billion in 2022 and it is expected to grow to almost $41 billion by 2032. At the same time, the massive overconsumption of pain-management opioid drugs, which can be addictive, continues to shatter lives.

We are pleased to acknowledge the financial support of Pacira Biosciences Inc. in producing this Outlook. Nature retains sole responsibility for all editorial content.

The pursuit of precision is made harder due to the fact that pain is different for everyone. Sex and gender accounts for the difference in how sensitive women are to pain. They are more likely to have their pain ignored by health-care providers, and studies of pain using mostly male mice help perpetuate inequity.