Air Pollution and Genetics Conspire to Raise Psoriasis Risk

TOPLINE:

Long-term exposure to air pollution is associated with an increased risk for psoriasis. Genetic susceptibility and air pollution interact to significantly heighten the risk of developing psoriasis. 

METHODOLOGY:

• This prospective study included 474,055 individuals from the UK Biobank who were psoriasis free at baseline and had available data on air pollution exposure.
• Exposures to nitrogen dioxide (NO₂), nitrogen oxides (NO_x), fine particulate matter (PM_2.5), and particulate matter (PM₁₀) were derived using data from the Department for Environment, Food and Rural Affairs and averaged annually for individual participants.
• Levels of each pollutant were stratified into quartiles.
• Time-varying Cox proportional hazards models were used to evaluate the associations among air pollutants, genetic risk categories, and the combined exposures with incident psoriasis.
• Genetic analyses were restricted to White participants, who were categorised as having low, intermediate, or high genetic risk levels.

TAKEAWAY:

• Over a median follow-up period of 11.91 years, 4031 new psoriasis cases were identified.
• Long-term exposure to PM_2.5, PM₁₀, NO₂, and NO_x was positively associated with an increased risk for psoriasis, with hazard ratios (HRs) per interquartile range increase of 1.41, 1.47, 1.28, and 1.19, respectively (all P < .001).
• Individuals in the highest quartile of air pollution exposure had multivariable-adjusted HRs of 2.01 for PM_2.5, 2.21 for PM₁₀, 1.64 for NO₂, and 1.34 for NO_x compared with those in the lowest quartile (all P < .001).
• A significant interaction was observed between air pollution and genetic predisposition, with the highest risk for psoriasis in individuals with the highest quartile of air pollution exposure and high genetic risk (eg, PM2.5: HR, 4.11; P < .001).

IN PRACTICE:

The study findings "suggest possible avenues for risk assessment and early intervention strategies in high-risk populations that may lead to more effective preventive measures for psoriasis," the authors wrote.

SOURCE:

The study was led by Junhui Wu, PhD, School of Nursing, Peking University, Beijing, China. It appeared in JAMA Network Open on July 16, 2024. 

LIMITATIONS:

The study's limitations included a potential selection bias due to the rapid recruitment of volunteers, the predominance of White European participants limiting generalisability, and the lack of data on indoor air pollution and individual behaviours beyond smoking.

DISCLOSURES:

The study was supported by grants from the China Postdoctoral Science Foundation. The authors reported no conflicts of interest. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.