Cesium exposure and pulmonary function decline: Potential mediating role of oxidative stress in chronic obstructive pulmonary disease patients

Cesium (Cs) is one of alkali metals. Persistent low-dose Cs exposure damages pulmonary function in the general population. However, the associations between Cs exposure and pulmonary function alternation are inconsistent in chronic obstructive pulmonary disease (COPD) patients. Thus, the goal of this study was to estimate the association between blood Cs concentration and pulmonary function alternation and the potential role of oxidative stress in this association. Serum 8-iso-prostaglandin F2α (8-iso-PGF2α) and blood Cs were measured. A generalized additive model and smoothed curve fitting found a non-linear relationship between blood Cs concentration and pulmonary function in COPD patients. Under the inflection point of blood Cs, per 1-unit increase of blood Cs was related with reductions of 0.592 L (95% CI: −1.181, −0.004) in FVC and 32.479% (95% CI: −55.278, −9.680) in predicted FEV1% with adjustment for confounding variables. Smoking status aggravated Cs-caused pulmonary function reduction in COPD patients. Sensitivity analyses hinted that our results remained robust. Moreover, a negatively linear correlation (β = 0.232; 95% CI: 0.105, 0.359) between blood Cs within a certain range and serum 8-iso-PGF2α was observed. Further investigation elucidated serum 8-iso-PGF2α was inversely correlated with pulmonary function parameters in COPD patients. Additionally, mediation analysis suggested that 8-iso-PGF2α mediated 6.70% and 8.36% of the associations between blood Cs with the reductions of FEV1 and predicted FEV1%, respectively. Consequently, blood Cs was inversely associated with pulmonary function parameters, but positively related with serum 8-iso-PGF2α. Oxidative stress may exert an important role in mediating Cs exposure-associated pulmonary function reduction in COPD patients.