Polycyclic aromatic hydrocarbons exposure associated with increased risk of psoriasis

Psoriasis is considered to be multifactorial, with both genetic and environmental factors contributing to its development. Polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment, originating from sources such as cigarette smoke, exhaust emissions, grilled foods, smoked foods and urban air. Researchs have established a link between PAHs exposure and autoimmune disorders; however, specific effects of PAHs on psoriasis remain underexplored. This study aims to evaluate the correlation between PAHs exposure and susceptibility to psoriasis. We analysed eight monohydroxy PAHs (1-Hydroxynaphthalene (1-NAP), 2-Hydroxynaphthalene (2-NAP), 3-Hydroxyfluorene (3-FLU), 2-Hydroxyfluorene (2-FLU), 1-Hydroxyphenanthrene (1-PHE), 1-Hydroxypyrene (1-PYR), 2-Hydroxyphenanthrene (2-PHE) and 3-Hydroxyphenanthrene (3-PHE)) in 5996 participants from the National Health and Nutrition Examination Survey (NHANES). We employed multivariate logistic regression, trend analysis, weighted quantile sum (WQS) regression and restricted cubic spline (RCS) analysis to investigate the relationship between PAHs exposure and psoriasis risk. Multivariate logistic regression and trend analysis revealed that monohydroxy PAHs, including 2-NAP, 3-FLU, 2-FLU and the mixture of 2-PHE and 3-PHE, are associated with an increased risk of psoriasis. Additionally, WQS regression showed a significant positive correlation between combined exposure to monohydroxy PAHs and psoriasis risk, with the mixture of 2-PHE and 3-PHE (47.3%) being the most influential factor. RCS regression further corroborated these findings. Specifically, 2-FLU can increase the expression of psoriasis-related inflammatory factors in HaCaT cells. In conclusion, PAHs exposure increases the risk of developing psoriasis. Efforts to reduce PAHs levels in the environment and minimise exposure are crucial for public health strategies aimed at preventing psoriasis.