Monday, 09 November 2020

Type 2 inflammation – understanding the connection between allergic diseases

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Johannesburg, 9 November, 2020 – Allergic diseases are increasingly becoming a worldwide epidemic.1c 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.1aa,16 In some people, this type 2 immune function may become overactive for several reasons: 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.1a This can explain why some allergic conditions run in families, and why some people suffer from more than one allergic disease.3a

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


Asthma, an inflammatory disease of the lower airways, is triggered by allergens, pollutants and exercise.15 It is one of the most common chronic conditions in the world, affecting as many as one in 13 people.4a,17

People with asthma may suffer periodic symptoms of chest tightness, coughing, wheezing, shortness of breath and phlegm production.,5c Many cases of childhood asthma have been associated with allergy, and this association remains into adulthood. 6e

Uncontrolled asthma has a negative impact on productivity and quality of life, with 30–50% of asthma patients experiencing anxiety and depression.4a,7a Patients with more severe and uncontrolled asthma are more likely to be depressed.5a 

Eosinophilic oesophagitis

EoE is an allergic condition of the oesophagus, the organ which connects the throat to the stomach.8a It is also known as “asthma of the oesophagus” because it shares many symptoms of asthma.8a

The most common symptom of EoE is difficulty in swallowing food.8j People with other allergic conditions such as allergic rhinitis, asthma and AD have a higher risk of developing EoE, but genetic and environmental risk factors also play a role.8d  

Chronic Rhinosinusitis:

CRS is a common inflammatory disease of the nasal sinus cavities, with symptoms that include a blocked nose, a runny nose, facial pain and loss of sense of smell.2a,6a

The longer the duration of CRS nasal symptoms, the higher the incidence of nasal polyps with a characteristic complete loss of sense of smell.9x 

Atopic Dermatitis:

 AD, also known as atopic eczema, is an inflammatory skin disorder with symptoms of a visible skin rash, intense itching and inflammation.10b

Besides the itch, people with uncontrolled AD suffer from bleeding skin, loss of sleep, lack of concentration, and impaired school-work productivity.10e,12a

AD affects 15-20% of children and 1-5% of adults in developed countries.12a There is a considerable impact of AD on quality of life, especially in severe cases.12a AD also has a greater negative effect on the mental health of patients compared with other chronic conditions such as diabetes and hypertension, and these effects can extend to a patient’s family.10c  

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 because of the underlying type 2 inflammation pathophysiology that connects these conditions. As an example, people with CRS are more likely to have asthma and as many as half of people with asthma have CRS.6a, 6d,9e

Also, the more severe and long-standing the CRS, the more likely it is that the person will develop asthma.2cPeople with severe asthma are more likely to suffer from CRSwNP, and AERD as a result of aspirin sensitivity is more likely to develop in these individuals.5a,6d,9e

Severe asthmatics have double the risk of developing AERD,2e,13b,13d while patients with AERD are more likely to suffer from allergies in general.2g AD has also been associated with many allergic diseases that seem to influence one another, with AD patients showing a higher likelihood of having asthma, hay fever, food allergy, anxiety and depression, and autoimmune disease.14a These associations are significant in mild and moderate disease, with even stronger effects in severe AD.14a 

What to do if you are struggling with symptom control for an allergic disease? 

It is recommended that you visit your local clinic or book an appointment with a doctor if you think you may be suffering from any of the allergic diseases that have been described above. It is also recommended that you consult with a specialist doctor if you are struggling to manage the symptoms of a diagnosed allergic disease. 

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Published in Health and Medicine