Influence of air pollution on airway inflammation and disease activity in childhood-systemic lupus erythematosus

Abstract

Exposure to fine particles may trigger pulmonary inflammation/systemic inflammation. The objective of this study was to investigate the association between daily individual exposure to air pollutants and airway inflammation and disease activity in childhood-onset systemic lupus erythematosus (cSLE) patients. A longitudinal panel study was carried out in 108 consecutive appointments with cSLE patients without respiratory diseases. Over four consecutive weeks, daily individual measures of nitrogen dioxide (NO₂), fine particulate matter (PM_2.5), ambient temperature, and humidity were obtained. This cycle was repeated every 2.5 months along 1 year, and cytokines of exhaled breath condensate-EBC [interleukins (IL) 6, 8, 17 and tumoral necrose factor-α (TNF-α)], fractional exhaled NO (FeNO), and disease activity parameters were collected weekly. Specific generalized estimation equation models were used to assess the impact of these pollutants on the risk of Systemic Lupus Erythematous Disease Activity Index 2000 (SLEDAI-2K) ≥ 8, EBC cytokines, and FeNO, considering the fixed effects for repetitive measurements. The models were adjusted for inflammatory indicators, body mass index, infections, medication, and weather variables. An IQR increase in PM_2.5 4-day moving average (18.12 μg/m³) was associated with an increase of 0.05 pg/ml (95% CI 0.01; 0.09, p = 0.03) and 0.04 pg/ml (95% CI 0.02; 0.06, p = 0.01) in IL-17 and TNF-α EBC levels, respectively. Additionally, a short-term effect on FeNO was observed: the PM_2.5 3-day moving average was associated with a 0.75 ppb increase (95% CI 0.38; 1.29, p = 0.03) in FeNO. Also, an increase of 1.47 (95% CI 1.10; 1.84) in the risk of SLEDAI-2K ≥ 8 was associated with PM_2.5 7-day moving average. Exposure to inhalable fine particles increases airway inflammation/pulmonary and then systemic inflammation in cSLE patients.