In a recent study published in JAMA Network Openresearchers investigated the relationship between long-term exposure to air pollution and the development of psoriasis, and how genetic susceptibility may influence this relationship and psoriasis risk.
Their findings show that prolonged exposure to various air pollutants significantly increases the likelihood of developing psoriasis, especially in genetically predisposed individuals.
Study: Air pollution exposure, genetic susceptibility and risk of psoriasis in the United Kingdom. Image credit: Ternavskaia Olga Alibec / Shutterstock
Record
Psoriasis is a common skin disease that causes persistent redness, itching and discomfort. It is an auto-inflammatory disease, meaning it is caused by immune reactions.
Since psoriasis is chronic, it can lead to significant physical and financial burdens and may be associated with other health problems, such as cardiovascular disease and arthritis. Although there is no cure, treatments aim to manage symptoms, but often come with side effects and high costs.
The incidence of psoriasis is increasing, especially in well-resourced countries, making it a growing public health concern. Previous studies have shown a link between short-term air pollution and increased psoriasis-related hospital visits in countries such as China, South Korea and Italy.
However, there is limited evidence on the long-term effects of air pollution and its interaction with genetic factors on psoriasis risk.
About the study
Researchers investigated the link between exposure to various air pollutants over an extended period and the onset of psoriasis using data from the UK Biobank, an extensive database of more than 500,000 people aged 37 to 73, focusing on how genetic susceptibility may influence this risk.
The study included subjects without psoriasis at baseline and excluded those who were missing, resulting in 474,055 participants for analysis.
Air pollution data, specifically for fine particles with a diameter of less than 2.5 micrometers (PM2.5), particles with a diameter of less than 10 micrometers (PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOX), collected by the UK Department for Environment, Food and Rural Affairs and matched to participants’ residential history.
Genetic risk was assessed using polygenic risk scores (PRS), which combine the results of several small genetic variants to estimate a person’s likelihood of developing psoriasis. Cases of psoriasis that developed during the study were identified through medical records and self-reports.
The researchers used statistical models that allowed for time-varying changes to assess the relationship between air pollution, genetic risk, and the development of psoriasis. They adjusted for factors such as age, sex, ethnicity, lifestyle and medical history. The models considered air pollutant levels both as continuous measures and divided them into four groups based on exposure levels. They looked at how genetic risk and air pollution together affected the risk of psoriasis.
To ensure that the results were reliable, the researchers conducted additional analyzes to check for hidden influencing factors, further focusing on participants who had lived at the same address throughout the study.
Foundings
The participants, who were 57 years old on average, participated in the study for almost 12 years. During this time, 4,031 new cases of psoriasis were identified. People who developed psoriasis were generally more likely to have a higher body mass index (BMI), hypertension, high cholesterol, diabetes, be male and smoke while also being less physically active.
The researchers found that higher levels of air pollutants were associated with an increased risk of psoriasis. The risk was highest for those living in areas with the highest levels of these pollutants. For example, people in the most polluted areas for PM2.5 they had double the risk compared to those in the less polluted areas.
In addition, genetic factors also played an important role. Participants with PRS, indicating a greater genetic predisposition, were more likely to develop psoriasis. The combined effect of high genetic risk and high exposure to air pollution significantly increased the likelihood of psoriasis, with the highest risks seen in individuals with high genetic predisposition and high exposure to pollutants.
conclusions
Researchers have found that long-term exposure to air pollution and genetic predisposition significantly increase the risk of developing psoriasis. This association suggests that both environmental factors and genetics play critical roles in the onset of this skin condition. Previous research focused primarily on short-term effects, while this study provided a comprehensive long-term analysis.
Strengths of the study include the large sample size and the use of detailed genetic data, which allow robust conclusions to be drawn. However, limitations include potential selection bias, the focus on a predominantly White European population, and the inability to account for indoor or workplace air pollution. The observational nature of the study means that causal inferences must be made with caution.
Future research should investigate these associations in more diverse populations and include detailed individual exposure assessments. The findings highlight the need for targeted interventions to reduce exposure to air pollution, especially for individuals at high genetic risk, for potential psoriasis prevention.
