Vol. 70, Iss. 10, October 2013
Alteration of Th1/Th2/Th17 cytokine profile and humoral immune responses associated with chromate exposure
Riassunto
Background The role of chromate exposure in the deregulation of total lymphocyte and other immune factors is largely unclear.
Objectives We aimed to examine alteration of the Th1/Th2/Th17 cytokine profile and humoral indicators caused by occupational chromate exposure.
Methods A cross-sectional study was conducted in two similar workshops (groups 1 and 2) with 106 male occupational workers and 50 matched local controls. Environmental and biological exposures were assessed by measuring chromium concentrations in workplace air, and in whole blood and urine samples of the workers. Cytokines in serum (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, IL-17A) were determined by CBA assay, while immunoglobin (IgA, IgM, IgG, IgE) and complement (C3, C4) were evaluated by immunonephelometric and ELISA methods. Micronucleus analysis was also used to explore the relationship between genotoxicity and immunotoxicity.
Results Compared with the control group, environmental chromate exposure in groups 1 and 2 was much higher, and the mean values of IL-6, IL-10, IFN-γ, IL-17A and IFN-γ/IL-4 were significantly decreased in group 1. In group 2, IgA and IgG levels were reduced, while C3 and C4 were increased. Levels of IFN-γ, IgG and IgA were all inversely associated with whole blood chromium, while C3 and C4 were positively associated with whole blood chromium (p<0.05). Both IL-10 and IL-17A were inversely associated with urine chromium. Correlations were also found between IL-10, IL-17A and micronucleus (r=−0.329, r=−0.312, respectively).
Conclusions Occupational exposure to chromate could downregulate the cellular and humoral factors of the immune system.
Commento
La tossicità dei cromati, sia a dosi elevate che moderate, è nota da tempo in letteratura. Sulla base delle evidenze sperimentali ed epidemiologiche alcuni di questi composti (cromo VI) sono stati classificati dalla IARC come cancerogeni per l’uomo di gruppo 1 e numerosi studi hanno correlato la loro esposizione con lo sviluppo di aberrazioni cromosomiche, mutazioni genetiche, apoptosi e danni ossidativi al DNA.
Negli ultimi anni, inoltre, numerosi studi in tossicologicologia ed epidemiologia industriale si stanno focalizzando sugli effetti a basse dosi di questi elementi. Questa tendenza riflette non solo l'uso diffuso del cromo per svariati scopi industriali (galvanica, saldatura ad arco, produzione ed utilizzi di tinture, pesticidi, cemento di portland, ecc..) ma anche l'assenza di controlli sull'esposizione effettiva dei lavoratori in molte realtà lavorative.
Il presente studio è stato realizzato in Cina da 4 gruppi di ricerca in Medicina del Lavoro, ed ha dimostrato lo sviluppo di significativi effetti immunoppressivi, sia dell’immunità sia umorale che cellulo-mediata, in due gruppi di lavoratori professionalmente esposti ai cromati.