The current concept of the relationship between macroorganism and gut microbiota is undeniable. The composition of the microbiota is primarily influenced by environmental factors, genetic and immune factors of the host organism.
Intestinal dysbiosis can lead to the predominance of certain types of bacteria that promote the activation of allergic and autoimmune mechanisms, the development of malignant tumors due to chronic inflammation or local immunosuppression.
In the era of immuno-oncology, the role of the gut microbiota in shaping the response to immunotherapy of autoimmune diseases and malignant neoplasms is of great interest to the medical community.
Considering that the composition of the intestinal microbiota is individual for each person, its study is necessary for the formation of a diagnosis of autoimmune disease and oncology.
The microbiome of the gastrointestinal tract in the view of modern science is considered as a set of various microorganisms, quantitatively and qualitatively differing in each person and playing a significant role in the biochemical, metabolic and immune response of the body, as well as representing a nonspecific barrier against exogenous factors of aggression.
Environmental conditions in the colon contribute to the normal functioning of microorganisms, and the number of 36000 species of bacteria reaches peak values - 1010-1013 CFU / ml (1011 bacteria per gram of intestinal contents)]. Anaerobic bacteria predominate over aerobes in a 1000: 1 ratio
Based on data from scientific studies of the general population in America (clinical study HMP) and in Europe (clinical study MetaHIT), it was shown that the dominant types of microorganisms in the microbiota are Bacteroidetes and Firmicutes
The colonization of the gastrointestinal tract with microorganisms begins immediately after birth, or rather, already when the fetus passes through the birth canal of the mother. The method of delivery in this case turns out to be a very important factor that determines the receipt of the primary microbiota in newborns.
Intestinal dysbiosis, as a manifestation of an imbalance in the bacterial ecosystem, leads to the prevalence of the number of certain types of bacteria over others. And this contributes to the activation of the mechanisms of carcinogenesis and autoaggression.
With the beginning of the development of methods of immunotherapy in recent years, the topic of the role of the intestinal microbiota in the formation of the immune response in oncology and autoimmune diseases has also been considered.
The results of a sufficiently large number of studies show that when bacterial samples from donors are introduced into the body of patients suffering from oncological and autoimmune diseases, the growth of their own microflora in patients is stimulated, an increase in its diversity, which in turn increases the body's ability to exercise control over the immune system, mechanisms carcinogenesis.
This provides a basis for further study of the relationship between immunotherapeutic methods of treating autoimmune diseases and neoplasms and the value of the composition of the intestinal microflora.
Some researchers say that the intestinal microbiota affects tumor growth and, consequently, the life expectancy of patients by affecting the processes of molecular oxidative stress and systemic toxicity of peripheral leukocytes], which leads to a decrease in the activity of the processes of systemic inflammation, which plays a major role in the development of autoimmune diseases and malignant neoplasms.
The opinion about which types of bacteria can mediate the best response to antitumor immunotherapy has not yet become unified.
There is evidence that the most pronounced effectiveness of immunomodulation for patients in whom the predominance of bacteria of the genus Ruminococcaceae is found . However, researchers from other large laboratories report that the relative prevalence of Clostridiales] increases the effectiveness of the treatment of autoimmune diseases. There is also evidence that patients with a predominance of Faecalibacterium significantly increase the rate of progression-free survival (PFS) in oncology.
It is believed that the effectiveness of immunomodulatory therapy is interrelated with the presence of various representatives of the genus Bacteroidales in the intestinal normobiota. Several scientific studies have found that an increase in the number of bacteria of the genus Bifidobacterium in the intestinal microbiome forms a T-cell antitumor response. It was also shown that the prevalence of the genus Bifidobacterium may cause an increase in the activity of antitumor immunity.
An analysis of a number of foreign studies has shown that there is strong evidence of the presence of changes in the treatment of autoimmune diseases and tumors at the level of normalization of microorganisms using immunomodulatory therapy.
From the foregoing, we can conclude that the most pronounced effect of immunotherapy for malignant tumors and autoimmune diseases can be expected in patients with a wider representation of microorganisms in the intestinal microbiome.
Considering that the composition of the intestinal microbiota is individual for each individual person, we can say that the need to study it corresponds to the principles of personalized and modern medicine.