Unknown microbiome: Our bacteria determine health and disease

Unknown microbiome: Our bacteria determine health and disease

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The role of microorganisms in humans has so far been largely underestimated

There is a powerful and invisible kingdom that has so far largely reigned in the human body and decides on health and illness. We are talking about the human microbiome, i.e. the total number of microorganisms that settle in a human. These billions of micro-organisms support, maintain and influence health to a far greater extent than previously thought, as the largest study on the topic so far shows.

In the "NIH Human Microbiome Project (HMP)", international scientists have been studying the relationship between human microorganisms and health for over ten years. The researchers uncovered numerous interactions and showed that disorders in the microbiome are associated with hundreds of diseases such as cancer, autoimmune diseases and heart diseases. The latest findings of the group were recently presented in the renowned journal "Nature".

Inventory in human body weight

“We had an inventory of the microbial species in the human body,” reports Lita Proctor, the HMP program director. The microbes in the body interact with each other as well as with the host. In this system, everyone can influence everyone. The researchers recorded such interactions in the project. Using three examples, the team shows how pathological processes occur when the composition of the microorganisms is out of balance.

Premature birth due to the lack of bacteria in the vaginal tract

The research group was able to show for the first time that a healthy vaginal microbiome of a pregnant woman is closely linked to the healthy birth of an infant. They compared the vaginal microbiome in uncomplicated pregnancies with that in premature babies and found that women who had given birth prematurely had a significantly lower number of the bacteria Lactobacillus crispatus. This bacterium is an ordinary inhabitant of the vaginal tract and is considered to be non-pathogenic (not causing the disease).

New biomarker for premature babies

However, it was surprising that the number of bacteria returned to normal a few months after premature birth. Researchers do not yet know why this microbe disappears from the vagina in the early days of pregnancy. Nevertheless, this finding could serve to determine the risk of premature birth. "Examining the composition of a woman's microbial community at the beginning of pregnancy can be useful in predicting the risk of preterm delivery," explains Professor Gregory Buck, a senior researcher in the study.

How inflammatory bowel diseases are related to bacteria

The causes of inflammatory bowel disease such as Crohn's disease and ulcerative colitis are still largely unknown. Now the HMP research team found clear evidence that an unbalanced intestinal flora could be the cause. They examined the composition of the intestinal flora in those with Crohn's disease and ulcerative colitis in different phases of the disease. In many cases, the composition of the intestinal flora of those affected changed completely within a few weeks. The researchers could not see such a drastic change in healthy people. It was shown that the bacteria Faecalibacterium prausnitzii and Roseburia hominis are reduced in inflammatory bowel diseases and instead bacteria of the type Escherichia coli are more common.

Important anti-inflammatory signaling molecules were lost

According to the researchers, the change in the intestinal flora led to a significant reduction in the butyrate level. Butyrate is a product of the intestinal bacteria, which reduces inflammation and strengthens the intestinal mucosa. The bacteria F. prausnitzii and R. hominis are considered the largest producers of these signaling molecules. The loss of these bacteria can therefore be a cause of chronic intestinal inflammation.

Link between diabetes and intestinal flora discovered

Type 2 diabetes has become one of the most important common diseases. In the United States, ten percent of the adult population now suffer. Another 30 percent are in a prediabetic state with elevated blood sugar levels. Around 70 percent of prediabetics develop type 2 diabetes during their lifetime. But how does the disease progress? The human microbiome also plays an important role in this aspect.

How an imbalance in the microbiome can lead to diabetes

Healthy and prediabetic people were examined in the study over a period of four years. The intestinal and nasal microbiome of the participants was documented at regular intervals. The first finding was that the intestinal bacteria of healthy participants differ from those with prediabetis. In addition, the researchers also see a connection between the changed intestinal flora and a poorer immune system, which prediabetic patients showed.

Which came first - the chicken or the egg?

The microbiome is a young field of research. All the issues found must be examined in more detail in further studies. However, it is clear that there is a clear connection between the composition of the microbiome and the occurrence of various diseases. "We do not yet know whether a change in a microbial community leads to a disease or whether a microbial community changes in response to the development of a disease," the research team said in a press release on the study results. This will now be clarified in upcoming studies. (vb)

Author and source information

Video: The Microbiome Revolution in Health u0026 Disease with Larry Smarr u0026 Rob Knight (August 2022).