Liver cancer and microflora
Employees of the Center for Cancer Research at the National Cancer Institute, part of the National Institutes of Health group, have proven the existence of a link between bacteria in the intestines of mice and antitumor immune mechanisms in the liver.
To find out whether conditionally pathogenic gut bacteria affect the development of tumors in the liver, Tim Greten and his group conducted a series of experiments on mice. They used three models of liver cancer and found that depletion of intestinal bacteria with a mixture of antibiotics reduced the incidence and size of tumors and reduced the number of metastases.
As it turned out during a detailed analysis, the introduction of antibiotics increased the number of natural T-killer lymphocytes in the liver of mice, which have cytotoxicity against tumor cells. Further experiments proved that the slowing of tumor growth in the liver was associated with this type of lymphocytes.
The accumulation of natural T-killers in the liver led to an increase in the synthesis of CXCL16 protein in endotheliocytes – cells lining the inner wall of blood vessels. The researchers found that bile acids can also control the expression of the CXCL16 protein. The introduction of bile acids into the mouse body affects the number of T-killers and, thereby, the rate of progression of liver cancer.
Bile acids are formed in the liver, they break down fats coming from food. The researchers found that one of the representatives of the intestinal microflora – clostridium C.scindens – is involved in the metabolism of fatty acids. The products of this interaction are a signal regulating the synthesis of the CXCL16 protein in the endotheliocytes of the liver vessels, which affects the number of natural T-killers and the rate of tumor growth.
The novelty of this study is that it describes not only the relationship of intestinal flora with the growth of neoplasms, but also the full mechanism of how bacteria affect the immune response in the liver. These results are preliminary. If they are confirmed, they can be used as a justification for the development of new antitumor drugs aimed at conditionally pathogenic bacteria in the intestine.
Article by C. Ma et al. Gut microbiome–mediated bile acid metabolism regulates liver cancer via NKT cells is published in the journal Science.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru Based on NIH materials: NIH study finds gut microbiome can control antitumor immune function in liver.