Microbiota How intestinal bacteria affect diseases
After a short break in connection with the May holidays, we continue a series of articles about the intestinal microbiota. Atlas and I have already told how the microbiota works and what bacteria live in the intestines of Russians . Today we share information about how some diseases are closely related to the health of the intestines.
Illustration by Rentonorama
The customs of maintaining cleanliness of the body and the house existed almost at all times (the exception is the Middle Ages, but we remember what the insanitary conditions of that era resulted in). And it was not accidental. In many cultures, the concept of physical purity is associated with health and beauty, although the existence of microorganisms was found only in the 17th century, and the word Bacterium appeared in the 19th century. It seems that people intuitively understood that a person needs to maintain cleanliness, they simply did not know what mechanism was behind this.
Today we know that you need to wash your hands before eating to get rid of pathogens and reduce the likelihood of disease. We take a shower, brush our teeth, wash dishes, floors — all in order to avoid the harmful effects of bacteria, whether it is an unpleasant smell or the development of an infection.
')
But not so long ago it turned out that excessive cleanliness also harms: the immune system weakens if it encounters different types of bacteria less often, and hot water destroys the protective fat layer of the skin and its microbiome, which makes it worse in its functions. Scientists have concluded that bacteria are an important part of our life. They support the functions of our organs, but at the same time they can do harm.
There is now enough research to assess how the intestinal microbiota is associated with type 2 diabetes, atherosclerosis, obesity, ulcerative colitis, and Crohn's disease. We will tell about them now.
Obesity is a condition in which the amount of adipose tissue in the body exceeds the norm. Estimate the amount of excess weight on a person’s body mass index. A sign of excess weight - index 25, and obesity - 30. You can check your BMI using a calculator . BMI is not for everyone. For example, with a muscular physique, it will also be high, therefore, in order to evaluate the full picture, they can additionally measure the waist.
Obesity can lead to metabolic syndrome, atherosclerosis, type 2 diabetes, high blood pressure, certain types of cancer, and other dangerous diseases and conditions. The main reason for weight gain is the consumption of calories that are not consumed by the body, but are stored in the form of adipose tissue.
Microbiota is involved in the metabolism of substances. It turned out from several observations. First, the microbiota of thin people is different from obese people. Secondly, if the microbiota of a thick mouse is transplanted into another, which has grown in a sterile environment without bacteria, the second will begin to rapidly gain weight. Also, if you transplant a full human microbiota with a sterile mouse, it will also gain weight.
There is evidence that a diet high in carbohydrates contributes to the development of this type of microbiome, in which the body gets more energy from food, which increases the risk of obesity and metabolic disorders. The bacteria of the Firmicutes division probably help us in this.
They break down dietary fiber and extract more energy from food than others, which may increase the risk of obesity. But, as we wrote in the previous article, the research gives mixed results. Sometimes people with obesity have higher representation of another department that is associated with the western type of food.
It is assumed that with high-fat diets, bacterial cells disintegrate and a large amount of lipopolysaccharides (the remains of dead bacteria) get into the bloodstream, which leads to weak inflammation and increases the risk of obesity .
A study involving twins showed that a less diverse microbiome is associated with weight gain, and vice versa, the diverse composition of bacteria reduces the likelihood of obesity. At the same time, the variety positively correlated with the consumption of fiber in the diet.
There are also a few bacteria that protect people from obesity - Akkermansia muciniphila and Christensenella. We wrote about the first one in the last article , and the second is interesting because of all other genera, it is most often inherited.
Today, to combat obesity and overweight, the patient may be offered a microbiota transplant. Basically, this procedure is done in foreign clinics, since in Russia it is still being carried out in an experimental mode.
Type 2 diabetes is a chronic disease in which the body cannot cope with incoming glucose. When glucose enters the bloodstream, the hormone insulin helps to transfer it into the cells, and stores the rest in the form of glycogen. In type 2 diabetes mellitus, insulin resistance develops: the body stops responding and glucose does not reach the cells, but remains in the bloodstream.
Excessive glucose in the blood can cause damage to nerves, kidneys, eyes, high blood pressure, atherosclerosis, and other diseases of the heart and blood vessels. One of the main factors in the development of type 2 diabetes is obesity. The abdominal fat cells are supposed to release pro-inflammatory substances, due to which the body becomes less sensitive to insulin.
According to research , the microbiota of people with type 2 diabetes contains a lower representation of the genera of the Firmicutes division. This department is just the main fiber processing and production of butyric acid. Also in the microbiota of people with type 2 diabetes, more pathogenic and conditionally pathogenic microorganisms have been found, such as Bacteroides caccae, Clostridium hathewayi, Clostridium ramosum, Clostridium symbiosum, Eggerthella lenta and Escherichia coli (E. coli).
Interestingly, not all types of fiber reduce the risk of type 2 diabetes. A meta-analysis of 9 large studies showed that the risk was 33% lower for those who were on the exact whole-grain diet. For those who consumed mainly vegetables and fruits, the risk did not change.
Fruits and vegetables contain mostly water-soluble fiber, while cereals are insoluble. Explain why it is insoluble fiber reduces the risk of diabetes. Perhaps this is due to the fact that vegetables and fruits contain much more simple sugars than cereals.
There is another interesting assumption. Several studies have shown a positive association between a protein diet and the risk of developing type 2 diabetes. Scientists have suggested that insoluble fiber may affect the body's absorption of protein. And it seems so. A study on people with obesity with the measurement of various biomarkers in feces and urine showed that animal protein is worse absorbed in the small intestine when cereal fibers are added to the diet.
Atherosclerosis is a condition in which cholesterol deposits form in the vessels. These plaques interfere with the normal flow of blood to the brain and heart, which can lead to coronary heart disease and stroke.
One of the main causes of atherosclerosis - high levels of cholesterol and triglycerides in the blood, which leads to a diet rich in saturated fats. Microbiota can affect the levels of these substances, thereby increasing or decreasing the risk of atherosclerosis.
The mechanisms, again, are unclear (you probably realized that the weakest point of research is to find a causal relationship), but there are some interesting assumptions. Some bacteria can synthesize bile acids that are absorbed by the intestines and through receptors affect the metabolism of glucose and fat.
A comparison of the microbiome of healthy people and people with atherosclerosis showed that the former have higher representations of the bacteria Roseburia and Eubacterium (for more information on bacteria, see the previous article ), and the representation of Collinsella is lower. Also, according to research, the bacterium Akkermansia muciniphila improves the barrier function of the intestines and affects the protection against atherosclerosis.
Another study notes that people with atherosclerosis have higher pathogenic bacteria such as Escherichia coli, Klebsiella spp and Enterobacter aerogenes. Ruminococcus gnavus, a bacterium that is associated with intestinal inflammation and low diversity of microbiota, was also higher among the group of people with atherosclerosis. It is noted that the microbiota of people with atherosclerosis is less balanced and diverse in comparison with a healthy group.
Inflammatory bowel disease (IBD) - chronic inflammation of the gastrointestinal tract, which include Crohn's disease and ulcerative colitis. In these diseases, immune cells attack healthy intestinal tissues, which leads to inflammation, bleeding and ulceration. Irritable bowel syndrome does not belong to this group of diseases.
The main difference between diseases is that ulcerative colitis develops only in the intestine, whereas Crohn's disease can manifest itself in any organ of the gastrointestinal tract. Inflammatory bowel diseases can lead to other dangerous conditions, such as colon cancer.
Intestinal bacteria produce metabolites that are involved in immune responses and the formation of the environment. For example, butyric acid can regulate cells of T-killer immunity and trigger the antibacterial functions of macrophages, which protects against the formation of ulcers. According to studies , stool specimens from patients with IBD contained less butyric acid, and the microbiota had fewer bacteria that produce it.
Scientists also note that in people with IBD, the representativeness of the bacteria Roseburia hominis, Dorea formicigenerans and Ruminococcus obeum is less, and in general their microbiota are less diverse in comparison with the healthy population. In the intestines of people with IBD, there is an excess of bile acids that are involved in the immune response of the body. However, a less diverse microbiota cannot produce a sufficient amount of many other important metabolites. This may be one of the reasons why immune cells begin to destroy the healthy tissues of the body.
For the treatment of ulcerative colitis and Crohn's disease, probiotic bacteria can be used that maintain the balance of the microbiota, strengthen the protective functions of the mucous layer and slow down the death of intestinal cells. Also, the use of microbiota transplants for the treatment of inflammatory bowel diseases is being actively studied.
In the next article we will explain in more detail how to take care of the bacteria: what to feed them with, what to protect against and why go in for sports.
Illustration by Rentonorama
Bacteria around us
The customs of maintaining cleanliness of the body and the house existed almost at all times (the exception is the Middle Ages, but we remember what the insanitary conditions of that era resulted in). And it was not accidental. In many cultures, the concept of physical purity is associated with health and beauty, although the existence of microorganisms was found only in the 17th century, and the word Bacterium appeared in the 19th century. It seems that people intuitively understood that a person needs to maintain cleanliness, they simply did not know what mechanism was behind this.
Today we know that you need to wash your hands before eating to get rid of pathogens and reduce the likelihood of disease. We take a shower, brush our teeth, wash dishes, floors — all in order to avoid the harmful effects of bacteria, whether it is an unpleasant smell or the development of an infection.
')
But not so long ago it turned out that excessive cleanliness also harms: the immune system weakens if it encounters different types of bacteria less often, and hot water destroys the protective fat layer of the skin and its microbiome, which makes it worse in its functions. Scientists have concluded that bacteria are an important part of our life. They support the functions of our organs, but at the same time they can do harm.
There is now enough research to assess how the intestinal microbiota is associated with type 2 diabetes, atherosclerosis, obesity, ulcerative colitis, and Crohn's disease. We will tell about them now.
Obesity
Obesity is a condition in which the amount of adipose tissue in the body exceeds the norm. Estimate the amount of excess weight on a person’s body mass index. A sign of excess weight - index 25, and obesity - 30. You can check your BMI using a calculator . BMI is not for everyone. For example, with a muscular physique, it will also be high, therefore, in order to evaluate the full picture, they can additionally measure the waist.
Obesity can lead to metabolic syndrome, atherosclerosis, type 2 diabetes, high blood pressure, certain types of cancer, and other dangerous diseases and conditions. The main reason for weight gain is the consumption of calories that are not consumed by the body, but are stored in the form of adipose tissue.
Microbiota is involved in the metabolism of substances. It turned out from several observations. First, the microbiota of thin people is different from obese people. Secondly, if the microbiota of a thick mouse is transplanted into another, which has grown in a sterile environment without bacteria, the second will begin to rapidly gain weight. Also, if you transplant a full human microbiota with a sterile mouse, it will also gain weight.
There is evidence that a diet high in carbohydrates contributes to the development of this type of microbiome, in which the body gets more energy from food, which increases the risk of obesity and metabolic disorders. The bacteria of the Firmicutes division probably help us in this.
They break down dietary fiber and extract more energy from food than others, which may increase the risk of obesity. But, as we wrote in the previous article, the research gives mixed results. Sometimes people with obesity have higher representation of another department that is associated with the western type of food.
It is assumed that with high-fat diets, bacterial cells disintegrate and a large amount of lipopolysaccharides (the remains of dead bacteria) get into the bloodstream, which leads to weak inflammation and increases the risk of obesity .
A study involving twins showed that a less diverse microbiome is associated with weight gain, and vice versa, the diverse composition of bacteria reduces the likelihood of obesity. At the same time, the variety positively correlated with the consumption of fiber in the diet.
There are also a few bacteria that protect people from obesity - Akkermansia muciniphila and Christensenella. We wrote about the first one in the last article , and the second is interesting because of all other genera, it is most often inherited.
Today, to combat obesity and overweight, the patient may be offered a microbiota transplant. Basically, this procedure is done in foreign clinics, since in Russia it is still being carried out in an experimental mode.
Type 2 diabetes
Type 2 diabetes is a chronic disease in which the body cannot cope with incoming glucose. When glucose enters the bloodstream, the hormone insulin helps to transfer it into the cells, and stores the rest in the form of glycogen. In type 2 diabetes mellitus, insulin resistance develops: the body stops responding and glucose does not reach the cells, but remains in the bloodstream.
Excessive glucose in the blood can cause damage to nerves, kidneys, eyes, high blood pressure, atherosclerosis, and other diseases of the heart and blood vessels. One of the main factors in the development of type 2 diabetes is obesity. The abdominal fat cells are supposed to release pro-inflammatory substances, due to which the body becomes less sensitive to insulin.
According to research , the microbiota of people with type 2 diabetes contains a lower representation of the genera of the Firmicutes division. This department is just the main fiber processing and production of butyric acid. Also in the microbiota of people with type 2 diabetes, more pathogenic and conditionally pathogenic microorganisms have been found, such as Bacteroides caccae, Clostridium hathewayi, Clostridium ramosum, Clostridium symbiosum, Eggerthella lenta and Escherichia coli (E. coli).
Interestingly, not all types of fiber reduce the risk of type 2 diabetes. A meta-analysis of 9 large studies showed that the risk was 33% lower for those who were on the exact whole-grain diet. For those who consumed mainly vegetables and fruits, the risk did not change.
Fruits and vegetables contain mostly water-soluble fiber, while cereals are insoluble. Explain why it is insoluble fiber reduces the risk of diabetes. Perhaps this is due to the fact that vegetables and fruits contain much more simple sugars than cereals.
There is another interesting assumption. Several studies have shown a positive association between a protein diet and the risk of developing type 2 diabetes. Scientists have suggested that insoluble fiber may affect the body's absorption of protein. And it seems so. A study on people with obesity with the measurement of various biomarkers in feces and urine showed that animal protein is worse absorbed in the small intestine when cereal fibers are added to the diet.
Atherosclerosis
Atherosclerosis is a condition in which cholesterol deposits form in the vessels. These plaques interfere with the normal flow of blood to the brain and heart, which can lead to coronary heart disease and stroke.
One of the main causes of atherosclerosis - high levels of cholesterol and triglycerides in the blood, which leads to a diet rich in saturated fats. Microbiota can affect the levels of these substances, thereby increasing or decreasing the risk of atherosclerosis.
The mechanisms, again, are unclear (you probably realized that the weakest point of research is to find a causal relationship), but there are some interesting assumptions. Some bacteria can synthesize bile acids that are absorbed by the intestines and through receptors affect the metabolism of glucose and fat.
A comparison of the microbiome of healthy people and people with atherosclerosis showed that the former have higher representations of the bacteria Roseburia and Eubacterium (for more information on bacteria, see the previous article ), and the representation of Collinsella is lower. Also, according to research, the bacterium Akkermansia muciniphila improves the barrier function of the intestines and affects the protection against atherosclerosis.
Another study notes that people with atherosclerosis have higher pathogenic bacteria such as Escherichia coli, Klebsiella spp and Enterobacter aerogenes. Ruminococcus gnavus, a bacterium that is associated with intestinal inflammation and low diversity of microbiota, was also higher among the group of people with atherosclerosis. It is noted that the microbiota of people with atherosclerosis is less balanced and diverse in comparison with a healthy group.
Inflammatory bowel disease
Inflammatory bowel disease (IBD) - chronic inflammation of the gastrointestinal tract, which include Crohn's disease and ulcerative colitis. In these diseases, immune cells attack healthy intestinal tissues, which leads to inflammation, bleeding and ulceration. Irritable bowel syndrome does not belong to this group of diseases.
The main difference between diseases is that ulcerative colitis develops only in the intestine, whereas Crohn's disease can manifest itself in any organ of the gastrointestinal tract. Inflammatory bowel diseases can lead to other dangerous conditions, such as colon cancer.
Intestinal bacteria produce metabolites that are involved in immune responses and the formation of the environment. For example, butyric acid can regulate cells of T-killer immunity and trigger the antibacterial functions of macrophages, which protects against the formation of ulcers. According to studies , stool specimens from patients with IBD contained less butyric acid, and the microbiota had fewer bacteria that produce it.
Scientists also note that in people with IBD, the representativeness of the bacteria Roseburia hominis, Dorea formicigenerans and Ruminococcus obeum is less, and in general their microbiota are less diverse in comparison with the healthy population. In the intestines of people with IBD, there is an excess of bile acids that are involved in the immune response of the body. However, a less diverse microbiota cannot produce a sufficient amount of many other important metabolites. This may be one of the reasons why immune cells begin to destroy the healthy tissues of the body.
For the treatment of ulcerative colitis and Crohn's disease, probiotic bacteria can be used that maintain the balance of the microbiota, strengthen the protective functions of the mucous layer and slow down the death of intestinal cells. Also, the use of microbiota transplants for the treatment of inflammatory bowel diseases is being actively studied.
In the next article we will explain in more detail how to take care of the bacteria: what to feed them with, what to protect against and why go in for sports.
Source: https://habr.com/ru/post/452800/
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