New study finds smoking causes inflammation in the bowel, resulting in ailments such as Crohn’s disease

The health care industry has long established that smoking may exacerbate the risk of developing Crohn’s disease, but the mechanism behind the connection has remained unclear within the scientific community. However, a recent animal study in Frontiers in Immunology may provide a better overview about the role of smoking on disease onset.

A team of researchers at the Kyung Hee University in Seoul, South Korea, has examined the effects of tobacco smoke on mice models as part of the study. The experts have exposed the animals to 20 cigarettes daily, six days per week, for a few weeks. The scientists have also assessed the onset of inflammation in the mice’s lungs and bowels following exposure.

“The airways and the intestinal system have a lot in common. Interestingly, in traditional Korean medicine, a connection between the lung and the large intestine has long been emphasized. Crohn’s disease is more likely to occur in people with airway diseases, suggesting inflammation in the lungs is linked with inflammation in the gut,” lead researcher Professor Hyunsu Bae has told Daily Mail online.

The result have shown that mice exposed to tobacco smoke developed significant lung inflammation compared with mice exposed to clean air. The research team has also observed that the affected mice developed a type of colitis that resembles Crohn’s disease. In addition, the scientists observed increased levels of mucus and inflammation in the colons of mice exposed to tobacco smoke. The research team has also noted the presence of blood in the fecal samples of the affected animals.

Furthermore, the research team noted that mice exposed to tobacco smoke have higher levels of a type of white blood cell that releases a pro-inflammatory protein known as interferon-gamma. An experiment on mice with lower levels of the white blood cell has shown that the animals did not develop colitis after being exposed to tobacco smoke. This suggests that the white blood cell is responsible for the onset of colitis following tobacco exposure, the researchers have concluded.

“Our results suggest cigarette smoking activates specific white blood cells in the lung, which might later move to the colon, triggering bowel inflammation. Smokers, especially those who also have bowel disease, should reduce their smoking,” co-author Professor Jinju Kim adds in a Daily Mirror article.

Study ties smoking to Crohn’s disease relapse

A study published last year also revealed that smoking not only worsens Crohn’s disease status, but also leads to disease relapse among patients. The researchers have pooled data from  573 patients as part of the study. The patients were divided into four groups: nonsmokers, former smokers, continuing smokers, and those who recently quit smoking. (Related: Reverse damage from smoking just by quitting: The body has a remarkable ability to heal itself.)

The research team observed that continuing smokers have shown earlier relapse and higher relapse incidence than nonsmokers. Likewise, the experts have found that former smokers and patients who recently quit smoking have exhibited a similar relapse incidence as those of nonsmokers.

“Currently, CD patients are still unaware of the risk related to their smoking habit. Even when the awareness is higher, very few smokers with CD are properly offered smoking cessation therapy. Importantly, with no education and in the absence of smoking cessation strategies, very few CD patients quit spontaneously. Recent prospective studies have demonstrated that high smoking cessation rates (ranging from 12 percent to 37 percent at one year) are possible, and these patients should be effectively informed of the risk and offered educational and therapeutic support to quit or decrease their tobacco consumption,” the research team has reported on the IBD News Today website.

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