Air pollution doesn’t help rhinitis

Clogged, runny nose, sneezing … Rhinitis, a mild and very common cold, is however accompanied by multiple inconveniences and a certain tiredness which slows down daily tasks. Researchers have concentrated their research on a possible association between the degree of air pollution and the severity of rhinitis in adults in the long term?

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Often considered mild, rhinitis can significantly affect quality of life and reduce academic or professional performance. It is manifested by sneezing, a nose blocked or leaking or itching, regardless of cold. of the symptoms which can alter the sleep, mood … The disease can be allergic or associated withasthma, but it can also be independent of the two. According to epidemiological studies and depending on the country, between 20 to 50% of individuals are prone to rhinitis.

Objectives and methods

Find out more about the long-term impact of pollution atmospheric research on this disease, two Inserm teams (Paul Brousse hospital in Villejuif and Institute for research in health, environment and work) studied their association. For this, the researchers used data from two cohorts intended for the study of respiratory diseases, so as to have well-documented information relating to rhinitis. This is theEpidemiological study of genetic and environmental factors of asthma (EGEA), a French cohort including asthmatic subjects, their families and witnesses from the general population, andEuropean Community Respiratory Health Survey (ECRHS), A European cohort of 28 countries, made up of young adults from the general population. In total, this work included 1,408 adults, aged 52 on average, living in 17 European cities, who reported having had rhinitis in the past twelve months (between 2011 and 2013).

A score associated with the severity of rhinitis was defined for each participant, between 0 to 12 depending on the intensity of the discomfort to carry out their daily activities caused by the symptoms: mild (0-2), slightly severe (3 -4), moderately severe (5-6) and very severe from 7. The median severity score observed was 4. In parallel, the authors used the pollution levels at the participants’ places of residence, obtained thanks to to the Escape project (European Study of Cohorts for Air Pollution Effects). In this study, the rates ofnitrogen (NO₂), of fine particles diameter less than 10 and less than 2.5 µm (PM₁₀ and PM_2.5), as well as the density and importance of traffic automotive have been modeled in several European cities.

Does high urban pollution cause more severe symptoms?

Statistical analysis shows a significant association between long-term pollution and severity of rhinitis. But several details are necessary. With the fine particles PM₁₀ and PM_2.5, there is a “dose effect”: the higher the concentration of particles, the more the severity of rhinitis increases. On the other hand, no association was found between car traffic and severity of the rhinitis, while it is a strong emitter of fine particles. A contradiction which could be explained by a methodological problem of collecting traffic data. Finally, there is also a significant association between NO concentration₂ and severity of rhinitis. This association is not “dose-dependent”, but the individuals most exposed to this pollution have on average more severe rhinitis than those who are less.

Another important nuance, these associations are stronger in people with non-allergic rhinitis and non-asthmatic and decrease strongly in case of allergic rhinitis orasthma. ” However, these results should be interpreted with caution given the small numbers in the latter two categories. However, these different types of rhinitis have different pathophysiological mechanisms: it is not so surprising that the results diverge depending on the presence ofasthma or allergic sensitivity. The effects of pollution on respiratory health could interfere with one type of rhinitis and not another “, considers Bénédicte Jacquemin, responsible for this work at the Institute for Research in Health, Environment and Work of Rennes.

What is the link between urban pollution and the increase in allergies?

Caroline Lepage article, published on February 11, 2005

In recent years, the number of people with asthma andallergies keeps increasing. Not easy to understand the cause of such a phenomenon, however, for doctors, the relationship between allergies and pollution seemed obvious. A recent study brings new elements to the investigation …

The allergy comes from the body’s response to the presence ofallergens, also called antigens, considered as foreign bodies. our antibody, or immunoglobulins E (IgE) specialized in allergic reactions and produced by lymphocytes B, hunt them down relentlessly. These protein allergens can come from all sides: trophallergens come from food, via the digestive tract (eggs, dairy products, fruits, vegetables, shellfish, etc.), pneumallergens are carried by the respiratory tract (pollen Plant, mites, pollutants present in theair, etc.), but allergens are also present in drugs, or venoms.

Allergens and pollution go hand in hand!

During a first contact with the allergen (so-called sensitization phase), the body identifies it and remembers its structure (which, moreover, is often very close to one allergen in another in plants). An army of IgE is already on war, ready to fight during a future invasion … The allergen re-enters the body and its contact with IgE triggers the release of a massive dose ofhistamine which goes to the organs expressing the symptoms of allergy (the eyes, nose, skin, lungs, etc.) : this is how asthma, urticaria, eczema, swelling of the eyes and digestive reactions also appear suddenly!

A study published by Ulrich Pöschl, chemist at the Technical University of Munich in Germany, in the journal Environmental Science and Technology picks up the fruit previous work that clearly linked air pollution from gas traffic exhaust and progression of allergies. Pöschl managed to identify a suspect: the nitration of allergens! His hypothesis? Automobile exhaust fumes would protein potentially more powerful allergens in the air, which increases the number of allergies in urban areas!

Tyrosine in the dock

Indeed, exhaust fumes release nitrogen dioxide (NO2) into theatmosphere. However, it had already been shown that proteins (in other words allergens), once nitrated, bind antibodies more strongly. The Pöschl team first collected urban dust samples, observing up to 0.1% of nitrated proteins there. Then, she studied the case of allergenic proteins of birch pollen voluntarily placed at a very busy street intersection (therefore particularly polluted by NO2 from exhaust gases) in Munich for a few days. The nitration phenomenon was even more significant since the nitrate protein level then rose to 10%!

The air polluted by NO2 reacts with the tyrosine – an amino acid – which enters into the composition of proteins present in the atmosphere, transforming it into nitrotyrosine. Birch pollen protein has, for example, 7 tyrosine residues. As a result, it is easily modified by traffic smoke. It turns out that this allergen nitrotyrosine, once in the body, would be a strong signal of attraction for antibodies, resulting in an amplified allergic reaction. According to the German chemist, nitration could stimulate the power of allergens present in the air, or even make allergens of proteins which are not a priori. Obviously, city dwellers are then more exposed to the risk of developing allergies. The only solution: to go live in the countryside … or finally, effectively reduce emissions exhaust gas!