Does Type 2 Inflammation Trigger Allergic Diseases?

Allergic diseases are increasingly becoming a worldwide epidemic. As medical research progresses, there is evidence that many allergic diseases such as asthma, atopic dermatitis (AD), and allergic rhinitis may be the result of an overstimulated type 2 immune reaction known as type 2 inflammation.

What is type 2 inflammation? 

The type 2 immune response is the part of the immune system that protects the body against parasites and functions as a wound repair mechanism. In some people, this type 2 immune function may become overactive for several reasons. This can include genetic factors, environmental triggers (allergens), or specific types of infections. The result of these triggers is an upregulation of the type 2 response and an “abnormal” type 2 inflammatory response.

This can explain why some allergic conditions run in families, and why some people suffer from more than one allergic disease (1).

How common are type 2 inflammatory diseases and what is their impact on health and well-being?  

Asthma

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Asthma, an inflammatory disease of the lower airways, is triggered by allergens, pollutants, as well as exercise. It is one of the most common chronic conditions in the world, affecting as many as one in 13 people.

People with asthma may suffer periodic symptoms of chest tightness, coughing, wheezing, shortness of breath, as well as phlegm production. Many cases of childhood asthma have been associated with allergies, and this association remains in adulthood. 

Uncontrolled asthma can have a negative impact on productivity and quality of life, with 30–50% of asthma patients experiencing anxiety and depression. Patients with more severe and uncontrolled asthma are more likely to be depressed.

Eosinophilic oesophagitis

EoE is an allergic condition of the oesophagus, the organ which connects the throat to the stomach. It is also known as “asthma of the oesophagus” because it shares many symptoms of asthma. 

The most common symptom of EoE is difficulty in swallowing food. People with other allergic conditions such as allergic rhinitis, asthma as well as AD have a higher risk of developing EoE, but genetic and environmental risk factors also play a role.

Atopic Dermatitis

AD, also known as atopic eczema, is an inflammatory skin disorder. Symptoms include a visible skin rash, as well as intense itching, and inflammation. Besides the itch, people with uncontrolled AD suffer from:

• bleeding skin
• loss of sleep
• lack of concentration
• impaired school-work productivity

AD affects 15-20% of children and 1-5% of adults in developed countries. There is a considerable impact of AD on quality of life, especially in severe cases. AD also has a greater negative effect on the mental health of patients compared with other chronic conditions. These effects can extend to a patient’s family.

What is the impact of excessive type 2 inflammation on developing multiple allergic diseases? 

A person who already suffers from one allergic disease may well suffer from other allergic diseases. This is because of the underlying type 2 inflammation pathophysiology that connects these conditions. For example, people with CRS are more likely to have asthma. In fact, as many as half of people with asthma have CRS. Also, the more severe and long-standing the CRS, the more likely it is that the person will develop asthma.

People with severe asthma are more likely to suffer from CRSwNP, and AERD. This is a result of aspirin sensitivity and is more likely to develop in these individuals. Severe asthmatics double the risk of developing AERD. Additionally, patients with AERD are more likely to suffer from allergies in general.

AD has also been associated with many allergic diseases that seem to influence one another. AD patients have displayed a higher likelihood of having

• asthma
• hay fever
• food allergy
• anxiety
• depression
• autoimmune disease

These associations are significant in mild and moderate disease, with even stronger effects in severe AD.

Want to know more?

At the recently held World Allergy Congress, scientists revealed that they had discovered a method to reduce allergy sensitivity.

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References

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13. https://www.dovepress.com/aspirin-exacerbated-respiratory-disease-pathophysiological-insights-an-peer-reviewed-article-JAA

14. https://pubmed.ncbi.nlm.nih.gov/30092266/

15. http://ginasthma.org/download/832/

16. https://www.immunopaedia.org.za/breaking-news/2017-articles/helminth-protection-by-innate-type-2-immunity/

17. https://www.aafa.org/asthma-facts/#:~:text=According%20to%20the%20Centers%20for,in%2013%20people%20have%20asthma.&text=More%20than%2025%20million%20Americans,age%2C%20sex%20and%20racial%20groups.