Relationship between systemic inflammation and lung injury induced by chromate exposure: A cross–sectional study in workers

Hexavalent chromium [Cr(VI)] compounds, known as “Group I Human Carcinogen” and “Category I Respiratory Sensitizer”, posed great challenges to the respiratory system. A cross–sectional study was undertaken among chromate workers. Serum club cell protein 16 (CC16) and soluble urokinase–type plasminogen activator receptor (suPAR) were measured using ELISA. Thirteen macrophage–related mediators were tested using cytometric bead array. After controlling for sex, age, smoking status, drinking status and BMI, each increase of one–unit of Ln–transformed blood Cr was related to the increase of IL–1beta [Beta (95% CI), 7.22(1.14, 13.29)%, P = 0.021], IL–23 [8.5(1.15, 15.85)%, P = 0.021], IFN–gamma [3.14(0.15, 6.13)%, P = 0.040], and suPAR [9.31(2.5, 16.12) %, P = 0.008], as well as the increase of CC16 by 3.88(0.42, 7.34) % (P = 0.029). Moreover, these inflammatory mediators played an mediation role in the rise of CC16 caused by Cr(VI). The exposure–response curve analysis revealed a substantial nonlinear association of IFN–gamma and suPAR with CC16, thus the mediation effect of INF–gamma and suPAR required cautious interpretation. The positive connection between macrophage–related mediators was stronger in the high exposure group than in the low exposure group, suggesting that high concentration of chromate might promote a complex interplay within the immune system.