Effects of diesel exhaust particles on coagulation

We read with great interest the recent study by Smyth et al., which claimed that diesel exhaust particles (DEP) instilled through the airway induce adverse effects such as inflammation, oxidative damage, and coagulopathy (Smyth et al., 2017). In their study, with regard to the impairments in coagulation, the authors only referred to the promoting effects of DEP on platelet aggregation. However, particulate matters including nanoparticles have been widely shown to have adverse effects on coagulatory systems other than platelet activation by our group and others. We previously studied the effects of inhaled DEP and their components, in the presence or absence of bacterial endotoxin, on several coagulatory and fibrolytic parameters in mice (Inoue et al., 2006). In our study, we observed that a single pulmonary exposure to DEP (8 mg·kg⁻¹) significantly increased the serum level of fibrinogen (4.261 ± 0.248 g·L⁻¹; unpublished data), which is involved in fibrin (clot) formation, as compared to that of vehicle (3.356 ± 0.110 g·L⁻¹). Interestingly, the carbonaceous nuclei of DEP obtained after extraction with dichloromethane (CH₂Cl₂: referred to as ‘washed DEP’ 4 mg·kg⁻¹) further increased the level of fibrinogen (4.883 ± 0.371 g·L⁻¹) in the same experiment (Inoue et al., 2006), suggesting that the organic chemical component in DEP extracted with CH₂Cl₂ (referred to as ‘DEP‐OC’) includes elements that have the potential to suppress the synthesis of fibrinogen. Therefore, it should be noted that the role each individual DEP component plays in the regulation of the coagulation system and resultant vascular thrombotic events induced by DEP is complicated.

Conflict of interest

The authors declare no conflicts of interest.

Inoue, K. , and Takano, H. (2017) Effects of diesel exhaust particles on coagulation. British Journal of Pharmacology, 174: 4199. doi: 10.1111/bph.13991.