Probiotics coated in nanoparticles can relieve symptoms of inflammatory bowel disease (IBD) in mice. The findings suggest the probiotic 鈥� a bacterium 鈥� could be taken orally to treat the condition in people, if shown to be safe and effective.
IBD covers a group of conditions that can involve stomach pains, diarrhoea, weight loss and fatigue caused by the immune system mistakenly attacking the gut. There is no cure for IBD and treatments are aimed at relieving symptoms by reducing inflammation.
鈥淭he current treatment approach is to use different drugs for different stages of disease, which is very complicated and not working very well,鈥� says at the University of Wisconsin-Madison. 鈥淲e envision this probiotic could be an alternative, simpler treatment for all stages of inflammatory bowel disease because it targets fundamental aspects of the condition.鈥�
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In IBD, gut inflammation is partly driven by relatively high levels of harmful bacteria and low amounts of beneficial bacteria. Previous studies have found that the Escherichia coli strain Nissle 1917 鈥� which is sometimes found in the gut 鈥� is a probiotic because it increases the number of beneficial bacteria and reduces levels of harmful bacteria in the gut, but its effects are limited because it passes through the body relatively quickly.
To improve how long the probiotic is retained in the gut, Hu and his colleagues have previously coated the bacterium in a polymer made of tannic acid. This helps it stick to the gut wall, improving its therapeutic effect.
Now, the researchers have designed nanoparticles that can be attached to that tannic acid coat. The idea is that when the loaded-up bacteria enter the gut, the nanoparticles are released and bond with molecules called reactive oxygen species that, as their name implies, easily react with other molecules. This would reduce the damage the molecules can cause in the gut.
鈥淚t鈥檚 a combination approach, the bacterium improves the balance of gut bacteria and the nanoparticles scavenge the reactive oxygen species at the same time,鈥� says Hu.
To test the loaded-up probiotic, the researchers first induced inflammatory bowel disease-like symptoms in 18 mice by feeding them a chemical called dextran sulphate sodium for a week.
Then, once symptoms were established, they treated the mice for four days. Six got the coated probiotic with the nanoparticles, six had the coated probiotic minus nanoparticles and six got no probiotic at all.
Mice given the probiotic with nanoparticles lost less than 5 per cent of their weight, on average, after four days of treatment. Mice fed the coated probiotic lost about 7 per cent of their weight over the same time period, and mice getting no probiotic lost some 12 per cent of their body weight.
Colon shrinkage can result from gut damage and inflammation, so Hu鈥檚 team also measured the colon length of the mice after four days of treatment. The colons of mice treated with the nanoparticle-bearing probiotic were more than 65 millimetres long. Those of mice given just the coated probiotic were around 60 millimetres long, and they were roughly 50 millimetres long for mice not fed any probiotic.
This supports the idea that the nanoparticles was treating the disease, says Hu.
鈥淲e need to test the nanoparticle-coated probiotic in large animals and then humans, but it looks very promising,鈥� says Hu. 鈥淚f it works in people, I could imagine people could orally take a capsule containing the probiotic, which is stable at room temperature.鈥�
However, the probiotic might need to be taken continuously to relieve IBD symptoms long-term, he says.
鈥淚 believe there is real potential in this approach,鈥� says at Ege University in Turkey. 鈥淚 would love to see the results of this approach for different types of inflammatory bowel disease and long-term therapeutic effects.鈥�
Science Advances
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