In vitro vascular effects induced by different diesel exhaust ultrafine particles (DEP)

The mechanisms leading to cardiovascular effects induced by DEP are still under investigation. The release of mediators from exposed lung cells can contribute to endothelial activation and in vitro cell systems were here used to investigate the effects of three different particles: two standard reference DEP (1650b, 2975) and DEP sampled from a Euro4 vehicle run over a chassis dyno. BEAS cells were exposed to 5ug/cm2 DEP for 20 h and oxidative stress (HMOX1) and the release of cellular mediators (IL6, IL6R, VEGF) were investigated. BEAS supernatants were used for 24 h as conditioned media for the treatment of HPMECST1.6R lung microvascular endothelial cells. Endothelial activation markers ICAM1 and VCAM1 were finally analyzed. Moreover a 3Din vitro alveolar-blood barrier (ABB) was used: epithelial cells were treated with DEP and the release of inflammatory mediators from the endothelial compartment was investigated. In the conditioned media model DEP Euro4, which has the major amount of PAHs, was able to induce oxidative stress, IL6 and IL6R release in BEAS cells and consequent endothelial dysfunction, as evidenced by the increased expression of ICAM1and VCAM1 in HPMECST1.6R. These results were confirmed by the experiments on the ABB. SMR1650b and 2975 did not induce significant biological effects in both in vitro models. These outcomes evidence that vascular effects induced by DEP may derive from the inflammatory response of the lung epithelial cells and are modulated by particles’ physicochemical properties, with PAHs-enriched particles being more reactive. Acknowledgment: Cariplo Foundation (2013-1038); MAECI (ID PGR00786)