A compound called inosine, made by three gut bacterial species in particular, can help the immune system T-cells directly attack cancer tumours and improve LD-1 immunotherapy, according to researchers at the Snyder Institute Microbiome Center, a part of the University of Calgary Medical Center.
Dr. Kathy McCoy, PhD, a leading expert on the body’s relationship with the microbiome says that scientists need to better understand the role bacteria play in regulating the immune system. McCoy’s team have now shown exactly how certain bacteria enhance the ability of T-cells to attack and destroy cancer cells.
Three bacteria were essential, and they all produce a specific compound called inosine. Inosine, or Hypoxanthine Riboside or Hypoxanthosine. is a nucleoside helping to build DNA and RNA. It is a precursor to adenosine which is essential in metabolism and energy production in the body.
Inosine increases uric acid, a powerful antioxidant in the blood plasma inhibiting free-radicals.
Inosine is produced by your gut bacteria from certain foods and the body produces the amounts it needs as required. It is involved with the nervous system, insulin regulation and protein synthesis.
The researchers worked with mice and Colorectal cancer but checked their findings in melanoma and bladder cancer. And then checked their findings in humans too. Same result. A full scale human study is now planned but researchers already know that humans have the same inosine-producing bacteria.
Of particular interest was the ability to make immunotherapy drugs work better. The PD-1 drugs like Nivolumab and Pembrolizumab, unblock immune system T-cells so that they can attack a cancer. These three bacteria, and their compound inosine, directly interact with T-cells then improve the performance immunotherapy and effectiveness of immunotherapy.
Chris Woollams, former Oxford University Biochemist said, “We have extensive research showing that people with cancer have lost gut bacteria. When we do Personal Prescriptions for people, we always increase the volume and diversity of the microbiome so that we increase the immune system response. It’s common sense that you would want it as strong as possible to attack the cancer. This is an excellent study revealing a new compound for our anti-cancer armoury and yet another study that shows improving the microbiome improves immunotherapy effectiveness”.
The three bacteria in question were Bifidobacterium pseudolongum, Lactobacillus johnsonii, and Olsenella species. This was the first time that inosine had been shown to significantly improve the attack on tumours, and enhance the efficacy of immune checkpoint inhibitors.
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Reference
- https://news.ucalgary.ca/news/ucalgary-researchers-discover-microbiomes-role-attacking-cancerous-tumours