How gut bacteria affect immunity
Aswathi Pacha, APRIL 14, 2018 17:00 IST
Composition of the gut colony differed in TB patients
The abundance and type of bacteria in the intestine gets altered when infected with tuberculosis, a study by Indian researchers shows.
The team studied the gut bacteria of six patients diagnosed with TB and compared them with one healthy relative from each household. Despite the food consumed by the patients and healthy individuals remaining the same, there were significant differences in the type and abundance of gut bacteria.
The faecal samples of the two groups were examined at three different time points — immediately after TB diagnosis, one week after treatment and one month after treatment.
They found that Prevotella and Bifidobacterium were abundant in the healthy individuals. “These bacteria are important for normal digestion and metabolism of the body. You can find them in abundance in the Indian gut due to the carbohydrate-rich diet,” explains Dr. Richa Misra from Sri Venkateswara College, Delhi, one of the first authors of a paper published in Environmental Microbiology.
In TB patients, bacteria like Faecalibacterium, Roseburia, Eubacterium and Phascolarctobacterium were significantly higher.
“These bacteria are known to produce short-chain fatty acids like butyrate and propionate, which are important for our gut, but their increased abundance can also lead to anti-inflammatory response, altering the immunity of our body,” says Prof. Vineet K. Sharma at the Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal and one of the co-authors of the paper. “The high number of these bacteria can also alter the normal metabolism of our body and can even reduce the appetite.”
Tuberculosis is usually associated with low BMI and low cholesterol levels. As butyrate and propionate regulate appetite-regulatory gut hormones and cholesterol bio-synthesis, a balance of these microbes is critical. “This makes more studies on gut microbiome extremely crucial since upsurge in butyrate and propionate-producing bacteria may prove detrimental for host response in infectious disease such as TB,” adds Dr. Misra.
One month after treatment, the gut microbes did not return to their original abundance highlighting the requirement of the six-month-long TB regimen.
`Nonetheless, recovery in microbial pathways involved in amino acid and vitamin metabolism were observed by one month as indicated by the functional gene pool.
“We have planned to further carry out cause–effect study as we are still unsure if the TB infection is causing the change in gut bacteria or if it is the other way round,” adds Dr. Misra.
This novel study may help further in understanding how drugs alter the gut microbiome and if probiotics/prebiotics and nutritional supplements should be given along with certain prescribed drugs.
Reference
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