Microbiologists compared the intratumoral recruitment of bacteria in thousands of tissue samples that belong to seven different types of tumor. In each of these microbiome, most often bacteria were found within the tumor cells. The composition of bacteria was different not only depending on where the tumor grew, but also from the properties of the tumors — for example, whether it is from hormones and responding to immunotherapy. Perhaps one day this knowledge can be used to treat tumours through its bacteria — similar to how doctors are trying to treat patients through their gut microbes. Work published in the journal Science.
Contrary to early ideas, the human body, there is virtually no sterile parts. Through the skin, blood, intestinal wall and other mucous membranes, the bacteria get to the other parts of the body. And they are not always there to microorganisms is often credited with a role in the development of tumors. And to act they can indirectly (for example, when gut microbes affect the carcinogenesis in other parts of the body) and directly (for example, the microbiome of tumor of the breast).
To understand how bacteria are associated with carcinogenesis and how they can help clinicians in the management of the tumor, a team of researchers under the leadership of Ravida Straussman (Ravid Straussman) from Basmanovskoye Institute for science in Israel decided to compile a collective portrait of intratumoral bacteria from different human organs. The scientists collected 1010 tissue samples from tumors of the breast, lung, ovary, bone and pancreas, as well as melanoma and glioblastoma (a tumor of the supporting cells of the nervous tissue in the brain).
The researchers immediately noticed that intratumoral bacteria can be quite a bit, so they developed a complex system of controls, not that their measure is the result of contamination of the sample. In addition to experimental samples, they took a total of 516 samples of healthy tissue, including adjacent to the tumor, 643 negative control is a sterile solution, which has passed through all laboratory procedures, and 168 controls from a clinic — pieces of wax, with which the clinics were treated the same as if it were real fabric. Finally, traces of bacteria in the samples was also determined in several ways: we estimated the concentration of bacterial DNA, RNA, and lipopolysaccharide and lipoteichoic acid components of the cell wall, which does not happen in animals.
In the first phase of work was that the bacteria found in tumors unevenly — for example, only 14.3 percent of melanomas, but more than 60 percent of the tumors of the breast and pancreas, and even bone, which is not in contact with the mucous membrane. Upon closer examination it was found that bacteria are most often found inside the cells, both cancerous and immune. Lipopolysaccharide often found in the cytoplasm of tumor cells, and lipoteichoic acid in macrophages. In the second fact, however, it is not surprising macrophages work as a garbage men in any inflamed tissue, therefore, and then engulf bacteria, and those sometimes turn out to be persistent and continue to live inside of them.
Then the authors have otsenival ribosomal RNA of the bacteria to evaluate the species diversity. In the first phase in all samples, they found a total of 9190 bacteria, but after applying the filters that weed out contamination in the laboratory and clinic, as well as the exclusion of widespread species there are only 528 kinds of bacteria that are found only in a specific tumor and its adjacent tissue. Among them, the most diverse was the microbiome of breast cancer, there is a total of found one hundred and fifty different types of bacteria, and each sample — on average 16.4 per view. In second place — the lung tumor (if you count the total number of births) and the bones (if you measure by the average number of different species in the sample), last — melanoma. In the case of the record — breast cancer — pathological samples were found to be carriers of a more diverse microbiome than fragments of healthy tissue.