Smoking may up inflammatory bowel disease risk

Are you a chain smokerIJ Beware, smoking cigarettes can have a direct effect on your intestines, leading to the risk of developing Crohn's disease -- a chronic inflammatory bowel disease that affects the lining of the digestive tract -- warned a study.

The findings showed that inflammation in the lungs caused by smoking affects the intestines as the "airways and the intestinal system have a lot in common".

"Crohn's disease is more likely to occur in people with airway diseases, suggesting that inflammation in the lungs is linked with inflammation in the gut," said Hyunsu Bae from the Kyung Hee University in Seoul, South Korea. 

Smoking also increases the levels of CD4+ T cells -- a type of white blood cell -- which were releasing a pro-inflammatory protein called interferon-gamma.

These white blood cells activated by cigarette smoke in the lungs, travel to the colon to cause colitis -- an inflammation of the colon resembling Crohn's disease.

"Our results suggest that cigarette smoking activates specific white blood cells in the lung, which might later move to the colon, triggering bowel inflammation," explained Jinju Kim from the varsity.

"Smokers, especially those who also have bowel disease, should reduce their smoking."

For the study, published in the journal Frontiers in Immunology, the team exposed mice to smoke from twenty cigarettes a day, six days a week, for a few weeks. The researchers then examined the presence of inflammation in the mice's lungs and colons.

Compared with mice exposed to clean air, mice exposed to cigarette smoke showed significant inflammation in their lungs. 

The researchers also found increased levels of mucus and inflammation in the colon, and blood in the faeces of the smoke-exposed mice.