One of the questions researchers are asking about the microbiome – the number of bacteria that live in the gut – is how it can affect the immune system. A team of researchers from Monash University Central Clinical School in Melbourne, Australia, wanted to answer that question, and in the process discovered two molecules that the scientists believe could be new treatment strategies. offered for asthma.
One of the molecules, L-tyrosine, is sold over the counter as a dietary supplement. Therefore, the researchers plan to quickly run to clinical trials. If it worked, they believe it could also be used to treat upper respiratory distress syndrome (ARDS) in COVID-19 patients, they reported in the journal Nature Immunology.
The researchers began by transferring gut bacteria from an immunocompromised mouse model to normal mice and monitoring the animals’ immune systems. They were surprised to find that the gut bacteria exhibited an improved metabolism of L-tyrosine, which resulted in the production of a byproduct called p-cresol sulfate (PCS).
They went on to give L-tyrosine or PCS to mice and found that the body products protected the animals from lung inflammation. “PCS travels all the way from the gut, to the lungs, and works on epithelial cells lining the airways to prevent an allergic response,” said lead author and professor Monash , Benjamin Marsland, Ph.D., in a statement.
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In addition to testing L-tyrosine and PCS in mouse asthma models, the Australian team tested them in animal models of ARDS, a lung disorder common in severe cases of COVID-19. They noticed a defensive effect there as well, they said.
Several research teams are pursuing modern immune targets in lung disease. The Mayo Clinic team, for example, reported in November that they had found a link between proliferation of CD8 + T memory cells living in tissue and persistent lung inflammation – a finding they believe could identifying new treatments for viral pneumonia, including that induced by COVID -19.
In terms of the microbiome, it has spurred research across a range of diseases including cancer, inflammatory bowel disease and obesity. Last year, researchers from the universities of Edinburgh and Dundee reported that the probillic Bacillus subtilis had an over-the-counter protective effect in preclinical models of Parkinson’s disease.
The next step for the Monash University team is to design a clinical trial of L-tyrosine in patients with asthma. PCS contains known toxins in humans, so the researchers are developing a form of the molecule that protects against lung inflammation without causing side effects. They believe the drug will be delivered directly to the lungs in an inhaled form, they said.