Nicotine-degrading bacteria can save humans from smoking-related diseases

Despite being well aware of the severe health issues linked with smoking, most individuals who smoke cannot quit it. Do you know why this happens and what makes people addicted to smoking? Well, it is not the smoke rings but nicotine — the chemical that gives tobacco products the ability to give a user an instant adrenaline kick. Over time, nicotine also accumulates inside the body leading to problems ranging from hair loss to liver ailments and heart attacks.

However, a team of international researchers has now figured out a way to deal with this addictive chemical. They have discovered that the bacteria species Bacteroides xylanisolvens (also found in the human gut) has the power to degrade nicotine that gets accumulated inside an organism's gut. The researchers tested the bacteria in a mouse model where it was also able to restrict the growth of fatty liver disease, a condition that occurs due to smoking.

These findings hint towards a possibility that maybe in the future, the bacteria could be employed to reduce the progression of smoking-related diseases in humans.

Here is how the bacteria break down nicotine

During smoking, nicotine is absorbed by the lungs, and later it is metabolized or processed by the liver. The chemical adversely affects the liver by releasing toxins and causing inflammation. Some previous studies have confirmed that it also leads to liver injuries, triggers the formation of excessive connective tissues and red blood cells, and increases the risk of diseases like blood cancer and non-alcoholic fatty liver disease (NAFLD) in humans.

The researchers examined nicotine accumulation in the stool and serum samples of two groups. The first group included 30 individuals who were regular smokers, and the second group incorporated the same number of non-smokers. They observed a high concentration of addictive chemicals inside the samples that were taken from smokers.

Then the researchers performed a similar experiment with mice. They exposed one group of mice to nicotine and compared nicotine levels in their serum and stool samples with another group of normal mice. Again, nicotine levels were found to be higher in mouse models that were exposed to nicotine.

The authors suggest that high amounts of nicotine in mice's bodies also made them more likely to develop NAFLD. They further studied the accumulation of nicotine in two sub-groups of mice (both were exposed to nicotine) — one group of mice had microorganisms inside their gut, and another group of mice contained no microorganisms in their gut.

When nicotine levels were compared between the two, mice in the former group were found to have lower amounts of the addictive chemical. These results indicated that gut microorganism somehow reduces nicotine concentration in mice. Since the gut of the mouse models comprised a variety of microorganisms, the researchers had to screen their whole gut microbiota to identify the one that contained genes for nicotine-degrading enzymes.

The screening tests revealed that members of the species Bacteroides xylanisolvens broke down nicotine in mice and reduced its accumulation inside the gut. Moreover, the bacteria could also restrict the progression of NAFLD in the animal. The authors wrote in their paper, “We performed whole-genome sequencing of B. xylanisolvens and examined the biosynthetic gene responsible for the catabolism of nicotine in B. xylanisolvens.”

They further added, “in summary, the results show that nicotine accumulates in the intestine during various routes of nicotine administration, and B. xylanisolvens has the ability to degrade nicotine.”

What do these results mean?

People don’t realize this, but the fact is that smoking is among the biggest health hazards humanity is facing today. Smoking and the consumption of tobacco-related products are responsible for over eight million deaths every year across the globe. In the form of the bacterium Bacteroides xylanisolvens, the authors have discovered a novel solution to the tobacco (nicotine) problem.

Overcoming tobacco addiction is never easy; depending on a person's condition, it may take a lot of time and effort. So while a patient works on it, if the doctors can save him from the health risks linked to nicotine accumulation in the body by using bacteria, this would be a miracle. Therefore, if successful in humans, this approach could entirely change how we treat patients suffering from diseases associated with tobacco addiction.

However, the researchers admit that a lot needs to be done before we can adopt this anti-nicotine strategy for humans.

The study is published in the journal Nature.