Pro-inflammatory properties of cadmium

Cadmium is a toxic and carcinogenic heavy metal that nowadays constitutes a serious environmental health problem. The aim of this study is to review the effects of cadmium on selected inflammatory mediators and markers, such as NF-kappa B and AP-1 transcription factors, IL-6, TNF-alpha, IL-1 beta cytokines, IL-8 or MIP-2 chemokine, MPO, iNOS, MMPs and COX-2 enzymes, PGE(2) (product of COX-2 enzyme), ICAM-1, VCAM-1 and PECAM-1 adhesion molecules, and CRP. The research strategy identified articles available in Medline, published between 1998 and 2012; we included both in vivo and in vitro studies carried out on humans and rodents. Most of the reviewed research findings suggest that cadmium in micromolar concentrations (especially in the 1-10 mu M range) causes up-regulation of the mediators and markers of inflammation, and appears to have pro-inflammatory properties. However, it is worth mentioning that a contradictory or even opposite hypothesis exists, which suggests cadmium to be an anti-inflammatory factor. Further research including detailed histological analyses should solve this discrepancy. Nevertheless, it appears that the main reason for these contradictory findings is the experimental setup: different biological systems analyzed and different doses of cadmium applied.