Microbiota: the key to the rise of allergies

For decades cases allergy – springs, foodskin…– increased sharply to such an extent that they began to be considered epidemic global in every sense. This striking phenomenon raises many questions: what are the risk factors for the disease? allergy?

Is the infection positive? pathogens prevent them? Do the chemical agents to which we are increasingly exposed every day have an impact? This genetics the culprit and should we resign?

Recent studies add factor more complex equation: microbiota. We will try to clarify all these issues.

hypothesis hygiene

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In 1989, epidemiologist David P. Strachan proposed the so-called “hypothesis hygiene” to explain the increase in the incidence of allergic diseases such as asthmahay fever and eczema.

After following 17,414 people until the age of 23, Strachan suggested that growing up in a family with several children living together reduces the likelihood of the disease allergy. Cause? height infections Crusades between brothers.

Then the idea arose that the reduction infections among residents of developed Western societies due to hygiene And medical advances It has also led to a decrease in type 1 immune responses, which protect us from pathogenic viruses and bacteria.

And this, in turn, carries a greater risk type 2 immune reactions uncontrolled; that is, allergic diseases. This last type of reaction protects us from parasitic helminths (worms), physical and chemical damage, poisons, etc.

Later studies confirmed this. hypothesis concluding that not all infections prevent allergy. The opposite may even happen: infections exposure to respiratory syncytial virus or rhinovirus early in life is associated with a greater likelihood of suffering asthma.

Importance of acquisition microbiome healthy in childhood

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It is currently believed that tolerance to allergens – that is, the absence of reactions of the immune system to elements that do not pose a danger to our body. health– depends on suitable microbial colonization and an immunostimulating environment from the first moments of life. Both are partially acquired from the mother.

In this case, the epithelium (skin, intestines, respiratory tract, etc.) receives appropriate stimuli (although chemical damage can disrupt this process) so as not to develop adaptive immune response against allergens.

On the one hand, this contributes toleranceand, on the other hand, maintain the physical integrity of said epithelium, thereby avoiding a harmful inflammatory response and increased risk infections.

In fact, it has been described that diaper rash lasting more than a month in infants is associated with allergy food.

As a result of this discovery, it has been suggested that the first exposure to foods that cause frequent allergic reactionsHow peanut, whether through ingestion. This will create tolerance, as if telling the immune system: “This is food, not a pathogen.”

On the contrary, the use moisturizing creams with food-borne ingredients such as peanut butter may contribute not only to skin irritation, but also to an allergic reaction.

Bacteria related to asthma

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If the situation is homeostatic (balance) between the immune system and microbiota in the first years of life we ​​might then encounter dysbiosis or microbiota pathogenic. To delve deeper into this connection, the risk of suffering from asthma and his relationship with microbiome.

In particular, the researchers studied the set of genes of bacteria present in feces pregnant women in the third trimester and in children aged three months to one year.

Well, the study authors found certain groups bacteria which actually differ between children with and without asthma.

In addition, they found that C-section reduces group presence Bacteroideswhich is associated with higher chances of contracting the disease among young children.

Mice cured by bacteriotherapy

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When allergy foodit has also been shown that microbiota Healthy cells induce tolerance to allergens, mainly by promoting the formation of regulatory T lymphocytes (inhibitors of the immune response).

A study conducted at Boston Children’s Hospital, led by doctors Rima Rashid and Talal Chatila, found dysbiosis in children with allergy food.

In addition, scientists introduced bacteria (bacteriotherapy) groups Clostridials And Bacteroidal mice sensitive to allergies to genetic change in the interleukin-4 receptor (a protein that plays a very important role in type 2 immune responses) and noticed that they improved.

This microbiota very relevant in development allergybut we must not forget about the genetic component.

In this sense, certain mutations genetics confirms this allergy they are the product of “exacerbated and decontextualized” type 2 immune responses.

sayings mutationswhich overactivate the STAT-6 transcription factor cause very serious allergic diseases characterized by atopic dermatitiselevated levels of immunoglobulin E (IgE) in the serum and high numbers of eosinophils (a type of immune system cell), as well as other types of developmental problems.

In conclusion, knowing genetics what is the basis allergy will allow the development of new drugs, such as interleukin-4 receptor blockers.

Also, find out how microbiota “rageThe ability to prevent these disproportionate immune system reactions could lead to the development of probiotic drugs that reduce them and prevent the most dangerous anaphylactic reactions.