Updated: October 2024
Asthma, air pollution and public health issues
Asthma results from a combination of a genetic predisposition to allergy, also known as atopy, and contributing environmental factors, including pollution. Children are increasingly affected, and adults more generally. Recent national surveys show an asthma prevalence of over 10% in children aged ten and over, and a current asthma prevalence of 6 to 7% in adults. In adults, asthma can be allergic or non-allergic, whereas in children, allergic asthma is predominant. Children currently affected by asthma have a higher risk of developing asthma in adulthood and experiencing more severe forms of the disease.
An individual is exposed to the environment from conception, at birth, throughout their entire life. We are therefore faced with a continuum of exposure to pollutants.
How can we better diagnose asthma and adapt therapies?
The research work carried out at the Pasteur Institute of Lille by the Dr. Patricia De Nadai His team's research focuses on two main areas: severe asthma on the one hand, and the impact of micropollutants and pollution in general on the disease on the other. Their research targets the respiratory system, in collaboration with other laboratories working on the digestive system, which plays a crucial role in the development of the immune system. This allows them to collect samples to study the changes that exposure to ultrafine particles can cause in the intestines.
The goal of researchers at the Pasteur Institute of Lille is to identify new biomarkers to improve diagnosis and tailor therapies. By working closely with physicians and researchers at the Lille University Hospital, particularly the pulmonologists who are integral members of the research team, the team is able to conduct translational research and thus improve patient care. It should be noted that several therapies are available for allergic asthma, including biotherapies (antibodies that neutralize allergy mediators), but the medical profession alone decides which therapy will be administered.
To learn more: “A team from Lille finds a way to control dust mite asthma"
- Outdoor pollutionOutdoor pollution, caused by sources such as exhaust fumes, urban heating, industry, and agriculture, is composed of highly complex aerosols. These aerosols also vary depending on the type of pollution, the season, the time of day, and the type of fuel, making their study extremely complex. Currently, teams at the Pasteur Institute in Lille are investigating susceptibilities related to respiratory conditions. For example, a person with asthma will be more sensitive to pollution because, in addition to an underlying inflammatory condition, the elimination of particles from the bronchial tree takes longer, resulting in prolonged exposure.
- Indoor pollutionWe spend approximately 80% of our time indoors, at home and/or in the office, in the car, which are places that are just as exposed to outdoor pollution as indoor pollution. Indeed, many Volatile Organic Compounds (VOCs), such as formaldehyde or benzene, are components of glues used in certain furniture, or carpets and insulating foams… Admittedly, the quantities are not large, but we are then subjected to continuous exposure; this is called chronic exposure. Researchers are trying to better understand the effects of indoor pollution.
Environmental exposure and lifestyle
A collaboration with the toxicology laboratory The University of Lille's research provides access to particle samples collected from the environment, primarily composed of carbon particles from industrial and road pollution. Despite the pulmonary clearance mechanism*, these particles, due to their extremely small size, can penetrate deep into the lungs, landing in the alveoli where gas exchange occurs, and ultimately entering the bloodstream. Studies have shown that these particles can be passed from mother to child via the placenta, and that in utero exposure to cigarette smoke promotes the development of respiratory illnesses, particularly asthma, and that this can be passed down to offspring for two or three generations. This potentially involves epigenetic mechanisms (which do not alter the DNA sequence but modify its reading) that lead to the transmission of gene malfunctions. The work conducted by the teams at the Pasteur Institute of Lille aims to demonstrate that the same phenomenon can occur with ultrafine particles in the environment.
Allergies therefore have a genetic component, and we now know that there are genes associated with the risk of developing an allergy, particularly asthma. These are combinations of susceptibility genes. The factors involved in the development of the disease are environmental exposure (exposome) and lifestyle. Asthma is therefore a disease that is strongly influenced by the environmentThus, genetic sequences will be more favorable to the development of the pathology, but the pathology will develop because the environment is favorable to it.
* In the respiratory tract, the mucus layer sequesters inhaled agents and progresses, thanks to the ciliary beating of the underlying cells, towards the glottis. The mucus is continuously swallowed or expectorated, which defines the mechanism of pulmonary clearance.
Should you air out your house every day?
Although studies primarily focus on outdoor air and the impact of micropollutants, there is also published data on indoor air quality, including particulate matter, solvents, and aerosols. These studies primarily examine patients with respiratory conditions, and to a lesser extent the general population, as vulnerable individuals are likely to experience the most significant and immediate health impacts of pollution.
Patricia De Nadai confirms that we need to ventilate our homes and refresh the air to address the increasing concentration of indoor pollutants. But this must be done at the time of day when pollutant levels are lowest, very early in the morning, before traffic starts. Ventilating homes is also essential to combat exposure to allergens. The most common allergy is that caused by dust mites, which thrive in high temperatures and humidity levels. A lack of ventilation in homes will promote these temperature and humidity conditions, increasing the dust mite population and, consequently, the allergen levels.
Dust mite asthma is very common and affects more than half of patients.
What is the impact of climate change on the production of allergenic pollen?
A research project receiving funding from theNational Research Agency (ANR) aims to study the impact of climate change on the production of allergenic pollen, in collaboration with plant biologists, physical chemists, and immunologists.
Climate change is influencing the emergence and proliferation of certain plants. Ragweed, for example, a grass normally confined to southern France and eastern Europe, is migrating northward. Teams at the Pasteur Institute in Lille are evaluating, in this project, the proliferation capacity of plants and the pollen production of allergenic grasses under atmospheric conditions similar to those modeled for 2050. From a human health perspective, the teams are assessing the effect of this pollen on the immune cells of healthy individuals and allergy sufferers. The aim is to understand the environmental changes linked to climate change, to anticipate an increase in sensitization to these allergens and therefore a rise in the number of patients requiring hospitalization, and to alert the authorities.
What are the effects of air pollution on health?
Air pollution affects virtually everyone. It is estimated that nearly 7 million deaths are associated with outdoor and indoor air pollution, representing approximately 12% of all deaths worldwide. Air pollution can impact everything and everyone. The WHO estimates that 36% of lung cancers are linked to pollution. 35% of COPD, 34% stroke, 27% heart diseaseEven more frightening, today the WHO states that 90% of the urban population does not breathe clean air.
Environmental pollution (fine particulate matter, carbon monoxide, sulfur dioxide, nitrogen oxides, ozone, benzene, hydrocarbons, and heavy metals) is estimated to cause 3,7 million premature deaths worldwide. It is the leading cause of cancer death (28%), accounting for 31,000 deaths per year in France (and increasing among women). An increase in cancer incidence is projected by 2030 (+45% to 190%). Regional mortality rates (world-standardized) for lung cancer between 2004 and 2008 ranged from 36,6 per 100,000 in Midi-Pyrénées to 57,3 per 100,000 in Nord-Pas-de-Calais.
This pollution is produced by factories, motor vehicles, agriculture, and natural phenomena (fires, pollen(volcanic activity, etc.) has a direct impact on respiratory and cardiovascular health. Particle size is linked to their toxic potential. Pollutants induce the production of profibrotic molecules responsible for peribronchial fibrosis, and metalloproteinases responsible for emphysema.
Diesel represents a determining factor in the increase in prevalence and morbidity of allergic diseases by acting not only on pre-established allergic responses but also on their genesis.
Pollution peaks increase mortality among patients with chronic cardiorespiratory conditions, increase emergency room visits and hospital admissions for respiratory and cardiovascular reasons in patients with chronic respiratory failure, asthma, COPD, etc., and are associated with decreased lung function in children. Children are particularly vulnerable to pollution. Pregnant women must also protect themselves to protect their children (many pollutants are present in cord blood).
Indoor air pollution also has a significant impact on people with asthma or sensitivities. Allergens in our homes are everywhere: plants, bedding, carpets, damp areas… We often hear about mold, dust mites, pollen, cleaning products, tobacco smoke, air fresheners… The importance of ventilating your home cannot be overstated; it's a crucial practice that is still too rarely followed. Staying well-informed is also essential: knowing the peak pollen seasons in your area, reading household product labels… to avoid mistakes or risky practices!
A researcher's journey
Patricia De Nadaï, a breath of hope in the fight against asthma
Patricia de Nadaï is a lecturer at the Faculty of Medicine in Lille and is part of Anne Tsicopoulos' research team on pulmonary immunity.
From a very young age, she knew she wanted to study biology, teach it, and do research. To become a researcher, she was told that her academic path required attending prestigious engineering schools. Undeterred, she pursued the university route, which she considered far more educational.
When asked to choose a laboratory, and given the choice between Marseille, Toulouse, and Lille, she opted for the capital of the Hauts-de-France region. Primarily because of the research topics of Anne Tsicopoulos's laboratory. She explains: “Although I had studied molecular biology and genetics more extensively, it was the work carried out on allergic asthma that motivated my choice. ‘How to inhibit cells so that the patient gets better?’ is a very concrete subject. We are fortunate to work with patients. I didn’t know the Pasteur Institute in Lille at all. The excellence of the research carried out there appealed to me.”
Within the team, our work focuses on allergic asthma, and more specifically on its severe forms. "because that's where there are the fewest treatment options for patients"“How does asthma start? Why? How can we help the patient?” says Patricia de Nadaï. These are all questions she tries to answer.
“We are interested in the effect of nanoparticles on the onset or worsening of asthma. The goal is to find a way to counteract them within the immune system. We will never be able to prevent nanoparticles from being present in the atmosphere or on lung tissue, but we can try to minimize their effects.”, explains Patricia de Nadaï.
At the Pasteur Institute in Lille, she considers herself lucky. She concludes: “Here, we have the advantage of benefiting from numerous technical platforms. We have access to different technologies and we exchange a lot of information between research teams. All of this is only made possible with the support of donors.”
