Health: Stress may contribute to flare-ups of Crohn’s disease by weakening the innate immune system

Is stress to blame for Crohn’s disease? Anxiety hormones impede the body’s ability to fight off bad gut bacteria by disabling immune cells and causing the inflammatory disease, study suggests

  • Experts from Canada’s McMaster University experimented with mice models
  • They found that certain stress hormones suppressed the innate immune system
  • This can cause the gut’s protective lining to break down and cease to function
  • Such a vulnerability allows bacteria linked to Crohn’s, like E. coli, to take hold

Psychological stress may contribute to flare-ups of Crohn’s disease by impeding the body’s ability to fight off bad gut bacteria like E. coli, a study has suggested.

Crohn’s disease is a long-term condition which can cause inflammation, scarring and ulcers within the body’s digestive tract — most often in the small or large intestine.

It is a debilitating gut condition that affects around 115,000 people in the United Kingdom and almost 3 million globally. 

Working with mice, researchers from McMaster University in Ontario Canada found that stress hormones could suppress the rodents’ innate immune system.

This left them vulnerable to a family of invasive bacteria — ‘Enterobacteriaceae’ — whose members, especially E. coli, have previously been linked to Crohn’s disease.

Psychological stress may contribute to flare-ups of Crohn's disease by impeding the body's ability to fight off bad gut bacteria like E. coli, a study has suggested (stock image)

Psychological stress may contribute to flare-ups of Crohn’s disease by impeding the body’s ability to fight off bad gut bacteria like E. coli, a study has suggested (stock image)

‘The main takeaway is that psychological stress impedes the body’s ability to fight off gut bacteria that may be implicated in Crohn’s disease,’ said paper author and biochemist Brian Coombes of McMaster University.

‘Innate immunity is designed to protect us from microbes that do not belong in the gut, like harmful bacteria,’ he explained.

‘When our innate immune system functions properly, it prevents harmful bacteria from colonising us, but when it breaks down, it leaves an opening for pathogens to colonise locations they normally cannot and cause illness.’

Key to the body’s innate immunity, the team explained, is the correct functioning and maintenance of the gut’s protective lining of epithelial cells.

This barrier relies on molecular signals from immune cells in order to secrete mucus, repair the cell wall and keep out harmful microbes. 

When the innate immune system is suppressed — such as by stress hormones — the the epithelial cellular wall can break down, allowing microbes like E. coli to invade the gut and trigger Crohn’s disease flare-ups.

Symptoms of the inflammatory condition are known to include abdominal pain, blood and mucus in one’s faeces, diarrhoea, fatigue and weight loss.

In their experiments, the team found that blocking the production of stress hormones in their mice models worked to restore proper function to both the immune system and the epithelial cells.

The researchers cautioned that, while their research may eventually pave the way to new treatments for Crohn’s disease, the findings are presently only in the pre-clinical stage — and there is much more work to be done.

‘The more we know about what triggers Crohn’s disease, the closer we come to new treatments and potentially even disease prevention,’ Professor Coombes said.

The full findings of the study were published in the journal Nature Communications.


Crohn’s disease is a long-term condition that causes inflammation of the lining of the digestive system.

Inflammation most commonly occurs in the last section of the small or large intestine but it can affect any part of the digestive system. 

Common symptoms can include:

  • diarrhoea
  • abdominal pain
  • fatigue (extreme tiredness)
  • unintended weight loss
  • blood and mucus in your faeces (stools)

Remission occurs when people with the disease go long periods of time without symptoms however these periods can be followed by flare ups of symptoms.  

Why it happens

The exact cause of Crohn’s disease is unknown. However, research suggests a combination of factors may be responsible. These include:

genetics – genes you inherit from your parents may increase your risk of developing Crohn’s disease

the immune system – the inflammation may be caused by a problem with the immune system that causes it to attack healthy bacteria in the gut

previous infection – a previous infection may trigger an abnormal response from the immune system

smoking – smokers with Crohn’s disease usually have more severe symptoms than non-smokers

environmental factors – Crohn’s disease is most common in westernised countries such as the UK, and least common in poorer parts of the world such as Africa, which suggests the environment has a part to play 

Source: NHS 

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