Allergic reactions can be triggered by a wide range of substances.
One type of allergy causes your eyes to itch while another one causes your body to break out in hives. Some allergic reactions are localized while others cause inflammation across your body.
Some people may have a strong reaction to a small amount of an allergen, while others need a larger amount to experience a reaction. The allergic reaction may be immediate or delayed. What causes this delay?
Allergens can affect the body differently, and the symptoms can vary.
To understand allergies better, you first need to know how allergies develop. In this article, we shall discuss:
- Development of Allergic Reactions
- Development of Food Allergies
- Development of Respiratory Allergies
- Development of Skin Allergies
Development of Allergic Reactions
First of all, I’d like to point out that this article discusses how allergies develop. If your query is regarding what triggers allergies, I recommend reading the article in the link below.
Now, let’s get back to our topic.
Allergies can develop through different pathways. Why or how is a certain substance causing an allergy? Is it because your gut microbiome is not balanced? Do you have a leaky gut? Or is it something else?
Immediate or delayed allergic reactions
How quickly the allergic reaction occurs depends on whether the immune response is IgE-mediated or not.
Allergies can be categorized as either IgE-mediated or non-IgE mediated, depending on the type of immune response that is triggered by the allergen. IgE-mediated allergic reactions are immediate whereas non-IgE mediated take up to 48 hours or more to develop.
What is IgE? Immunoglobulin E (IgE) antibodies are allergen-specific antibodies. This means that each IgE antibody is designed to recognize and bind to a specific allergen, such as pollen, pet dander, or certain food proteins. IgE-mediated allergies refer to an allergic reaction that involves the production of IgE antibodies by the immune system.
Instant reactions from IgE-mediated allergies
In IgE-mediated food allergies, the immune system produces an abnormal amount of IgE antibodies in response to a particular food allergen.
These antibodies then bind to mast cells and basophils, which are types of immune cells, and release histamine and other inflammatory chemicals when the allergen is encountered. This type of allergic reaction typically occurs within minutes to a few hours of exposure to the allergen, and it can cause symptoms such as hives, swelling, itching, and anaphylaxis.
Delayed reactions from non-IgE-mediated food allergies
Non-IgE-mediated food allergies, on the other hand, involve different components of the immune system and can have delayed onset symptoms.
In these types of allergies, the immune system produces other types of immune cells like T cells that may take longer to cause symptoms than IgE-mediated allergies. Symptoms may include gastrointestinal distress, such as vomiting or diarrhea, and can take several hours or days to develop.
Mixed-type allergies: There are also mixed-type allergies that have components of both IgE-mediated and non-IgE-mediated mechanisms.
Localized reactions or systemic inflammation
An allergic reaction may be localized to just one part of your system/body. At other times, the reaction spreads throughout your body causing systemic inflammation. For example, an insect bit on your hand may cause swelling on your hand, around the bite site. But sometimes, this can cause your whole body to break out into rashes.
Inflammation is a general response by the body’s immune system to injury, infection, or irritation. When the immune system detects an allergen in the body, it launches an attack that leads to inflammation throughout the body. This inflammation can manifest as a range of symptoms, including hives, swelling, gastrointestinal distress, and respiratory problems. These may be mild, moderate, or severe.
Systemic inflammation is a complex process that involves the release of various cytokines and other immune system molecules that promote inflammation and activate immune cells. Cytokines are small proteins produced and released by your immune system in response to a variety of stimuli, such as infections, allergens, etc.
In the case of food allergies, the immune system mistakenly identifies food proteins as harmful and triggers an immune response, which can lead to the release of these inflammatory molecules.
2. Development of Food Allergies
Food allergies occur when the immune system overreacts to a particular protein in food and produces an allergic response. The immune system mistakes the protein for a harmful substance and produces an immune response. This can range from mild symptoms such as hives and itching to severe and life-threatening symptoms such as anaphylaxis.
Gut microbiome and food allergies
There is growing evidence to suggest that the gut microbiome, which is the collection of microorganisms that live in the human digestive tract, plays an important role in the development of food allergies.
One theory is that an imbalance in the gut microbiome, known as dysbiosis, can lead to a weakened gut barrier function, which may allow food allergens to pass through the intestinal wall and trigger an immune response.
The trillions of microbes that live in us (our gut microbiota) help suppress immune responses to food by stimulating the TLR4 receptor. This TLR4 receptor sits in the membranes of the immune cells and helps recognize the microbes if damaged can cause allergic reactions (1).
In our gut, the microbes that colonize there release more regulatory T-cells, a type of cell that negates or lowers immune responses. These act as gut barriers. If your gut microbiome dwindles due to antibiotics or anything, it may break this delicate balance increasing the episode of food allergies.
Leaky gut and food allergies
The intestinal tract is considered to be a barrier to food allergens. The leaky gut syndrome is a condition in which the lining of the intestines becomes more permeable than normal, allowing larger particles, such as undigested food proteins or toxins, to pass through into the bloodstream. This can trigger an immune response, as the body recognizes these particles as foreign and potentially harmful.
Some researchers have suggested that this immune system response may lead to the development of food allergies, as the immune system mistakenly identifies certain food proteins as harmful (2), (3). A leaky gut can also trigger autoimmune diseases such as inflammatory bowel disease, celiac disease, autoimmune hepatitis, type 1 diabetes, and systemic lupus erythematosus (SLE).
Tight junction permeability and food allergies
This is similar to the leaky gut issue mentioned above where the leak happens due to damage in the mucus layer that covers the intestinal lining. Here the focus is on leaks happening at tight junctions.
Tight junctions are structures in the intestinal lining that act as barriers between the inside of the gut and the rest of the body. They prevent large molecules, such as undigested food particles and harmful pathogens, from passing through the intestinal wall and entering the bloodstream (4).
In people with food allergies, there is growing evidence to suggest that tight junctions in the intestinal lining may be compromised, allowing food allergens to pass through the gut barrier and trigger an immune response.
Tight junctions consist of multiple proteins as a functional complex. Certain allergens can trigger a mechanism that jeopardizes tight junction permeability rendering intestinal barrier damage and consequently food allergy. Studies have shown that allergen-induced abnormal expression of proteins in tight junctions can also lead to inflammatory bowel disease, chylous diarrhea, and celiac disease.
3. Development of Respiratory Allergies
Respiratory allergies are also known as allergic respiratory diseases. These conditions affect the respiratory system and are caused by an allergic reaction. The most common types of respiratory allergies are allergic rhinitis (hay fever), allergic asthma, and allergic bronchitis.
Lung microbiome and respiratory allergies
The lung microbiome consists of the microorganisms that live in the respiratory tract. Our lungs are colonized by a diverse community of microorganisms that can affect the immune response and overall health of the lungs. Changes in the lung microbiome may contribute to the development of respiratory allergies.
Exposure to certain environmental factors, such as pollution and cigarette smoke, can alter the lung microbiome and increase the risk of respiratory allergies. These factors can also lead to an increase in inflammation in the respiratory tract, which can exacerbate existing allergies or trigger the development of new ones.
The gut microbiome can also influence the health of the lung microbiome. Changes in the gut microbiome, such as those caused by the use of antibiotics or a diet low in fiber, can disrupt the balance of microorganisms in the gut and affect the composition of the lung microbiome. Any factor compromising this microbiota compromises this balance and weakens the immune system and respiratory allergies (5).
Leaky gut and respiratory allergies
A leaky gut may be linked to the development of respiratory allergies. While the primary site of leakage in the gut is through the tight junctions between the epithelial cells that line the small intestine, a leaky gut can also lead to the release of bacterial toxins and other molecules into the bloodstream, which can trigger an immune response and lead to inflammation in other parts of the body, including the respiratory tract.
A leaky gut has been linked to a number of respiratory conditions, including asthma and allergic rhinitis (6). In these conditions, it is thought that the inflammation caused by the release of toxins and other molecules from the gut can lead to increased sensitivity to environmental allergens and trigger an allergic response.
4. Development of Skin Allergies
Skin acts as a primary barrier to millions of external pathogens (disease-causing organisms). Therefore this barrier function is of utmost importance for maintaining skin homeostasis.
Any damage to this barrier allows pathogens/allergens to penetrate the skin. This leads to the development of allergic skin diseases such as atopic dermatitis (eczema), allergic contact dermatitis, urticaria (hives), and angioedema.
Skin microbiome and cutaneous allergy
Our skin acts as a physical barrier that prevents the invasion of harmful bacteria (7), (8). Skin is home to millions of friendly microorganisms called the skin microbiome that keeps our skin healthy and in good condition.
A disruption in the microbiome can create inflammation, irritation, dry and itchy skin, and cutaneous allergy such as urticaria, contact dermatitis, etc.
Leaky gut and skin allergy
We already know that a leaky gut can lead to respiratory and food allergies. But now studies have concluded that leaky gut can also lead to skin allergies such as acne, atopic dermatitis, and psoriasis (9), (10).
Frequently Asked Questions (FAQs) on the Development of Allergies
What is the difference between antigen and allergen?
An antigen is any substance that the immune system recognizes as foreign and potentially harmful. Allergens are antigens that trigger an abnormal or exaggerated immune response, leading to an allergic reaction.
What are Anti-Allergen Antibodies: Immunoglobulin E (IgE)
Immunoglobulin E (IgE) is a type of antibody that is produced by the immune system in response to certain allergens or antigens. It plays a crucial role in the body’s defense against parasites and allergens.
When the body is exposed to an allergen, such as pollen or food proteins, specialized immune cells called B cells are activated to produce IgE antibodies specific to that allergen. These IgE antibodies then bind to mast cells and basophils, which are immune cells located throughout the body, particularly in tissues exposed to the environment such as the skin, respiratory tract, and gastrointestinal tract.
Upon re-exposure to the same allergen, the allergen binds to the IgE antibodies on the surface of mast cells and basophils, triggering these cells to release a variety of chemicals, such as histamine, that cause the symptoms of an allergic reaction. These symptoms can include itching, swelling, rash, hives, and, in severe cases, anaphylaxis.
While IgE-mediated reactions are important for the body’s defense against parasites and other pathogens, they can also cause allergies and asthma when the immune system overreacts to harmless substances. Testing for IgE antibodies can be helpful in diagnosing allergies and determining the specific allergens causing an allergic reaction.
Leaky gut syndrome: where does it actually leak? Only the tight junctions?
A leaky gut and compromised tight junctions can lead to food allergies. While the primary site of leakage in the gut is through the tight junctions between the epithelial cells that line the small intestine, there are other areas where the gut may leak as well.
In addition to the tight junctions, the gut barrier is also supported by other components, including the mucus layer that covers the intestinal lining and the immune cells that are present in the gut. Damage or disruption to any of these components can contribute to increased intestinal permeability and the development of a leaky gut.
An unbalanced microbiome and a leaky gut seem to be major triggers in the development of allergies.
Your immune system plays a key role in the development of allergies. It can mistakenly identify harmless substances as dangerous, leading to an immune response that causes uncomfortable symptoms.
However, genetics, environmental factors, and lifestyle choices can also influence the development of allergies. Therefore, it’s essential to take proactive steps to avoid allergens and maintain a healthy lifestyle. This can include eating a balanced diet, exercising regularly, getting enough sleep, and reducing stress.
While there is no cure for allergies, there are many treatments available that can help manage symptoms and improve quality of life.
So, don’t suffer in silence! Take action today to manage your allergies and feel your best. With the right approach, you can minimize your symptoms and enjoy a healthier, happier life.
Read more: Treatment of allergies