The European Food Safety Authority (EFSA) has established a tolerable daily intake (TDI) of 1 mg/kg bw/d for the plasticizer DINCH (Cyclohexane-1,2-dicarboxylic acid diisononyl ester). To characterize the maximum internal doses resulting from a single dosing and to assess species differences relevant for extrapolating rat toxicokinetics to humans, concentration-time profiles of DINCH and its metabolites (specific monoesters: MINCH, OH-MINCH, oxo-MINCH, cx-MINCH; non-specific metabolite: CHDA) were quantified in the blood of male Wistar rats and male human volunteers. Urinary excretion of metabolites was additionally evaluated for humans. Single oral doses of ring-deuterated DINCH were administered (rats: 1 or 40 mg/kg bw; humans: 1 mg/kg bw). In rats, gastrointestinal absorption exhibited saturation, as a 40-fold increase in administered dose resulted in only ∼25-fold increases in Cmax and AUC. Across species, the hierarchy of Cmax in blood was consistent: DINCH > CHDA > cx-MINCH > MINCH > OH-MINCH > oxo-MINCH. Notably, Cmax values for DINCH and MINCH in blood after a 1 mg/kg bw (1.74 µM and 0.10 µM) dose in humans were like those observed in rats following a 40-fold higher dose (4.4 µM and 0.11 µM). Corresponding AUC∞ values showed the same pattern, indicating greater systemic availability of DINCH in humans, although this is partly counter balanced by plasma protein binding. In humans, approximately 50% of MINCH and 70–80% of the other monoester metabolites were glucuronidated, whereas these metabolites remained unconjugated in rats. CHDA was unconjugated in both species. Overall, the data highlight both shared and species-specific features of DINCH metabolism in rats and humans.
Our previous study in vitro has shown that targeting transcription factor Snail might be a strategy for the treatment of silicosis. In this study, we evaluated the feasibility of the strategy in vivo. Here we used CBG transgenic mice which could be used to track and isolate alveolar epithelial type II cells (AT II cells) to confirm that 2.5 mg silica could induce epithelial-mesenchymal transition (EMT) in AT II cells in vivo. Based on the results that 2.5 mg silica induced a rapid elevation of Snail in the lungs of mice and the optimal injection dose and stable expression time of adeno-associated virus (AAV) 9 vectors, we finally decided to inject AAV9-mediated Snail knockdown at 1.0 × 1011 vg/mouse 1 week before silica instillation to inhibit the levels of Snail increased by silica. The results showed that Snail-shRNA in AAV9 prevented silica-induced EMT in AT II cells in CBG transgenic mice and inhibited EMT and pulmonary fibrosis induced by silica in wild-type mice. Quantitative proteomic analysis combined with dbEMT database mapping further indicated that Snail knockdown suppressed silica-induced EMT and fibrosis through a Fibronectin (FN1)-centered interaction network involving proMMP8 activation and JUN kinase signaling. These findings suggested that Snail could be used as a target for the treatment of pulmonary fibrosis in the future.
The recent use of a Novichok nerve agent for an assassination attempt on Alexei Navalny underlined the importance of identifying effective countermeasures. The immediate decontamination is essential to reduce the penetration of the chemical agent into the systemic circulation. Only limited data are available about the decontamination of Novichok nerve agents on the skin. In this study, we used an in vitro model of human skin to determine the efficacy of decontaminants to remove the agent A-234. The skin was exposed towards A-234 and after 5 min or 30 min the decontamination was initiated by applying different decontamination protocols (Reactive Skin Decontamination Lotion (RSDL), the potassium salt of the acetohydroxamic acid (AHAK), sodium hypochlorite (NaOCl) 2%, soapy water 2% and tap water). Then, the amount of penetrated A-234 was calculated using an acetylcholinesterase inhibition assay. The early decontamination with AHAK was most effective resulting in a complete decontamination, i.e. 0% residual A-234. In contrast, soapy water, tap water, RSDL and NaOCl showed a lower decontamination efficacy and the penetrated amount of A-234 was reduced by 89% (soapy water, tap water), 91% (RSDL) and 95% (NaOCl). The delayed decontamination after 30 min also revealed a complete decontamination of A-234 by using AHAK and an inadequate decontamination using soapy water, tap water, RSDL and NaOCl. In conclusion, the results underline that the decontamination of the Novichok agent A-234 was similar to the V-series nerve agent VX. The relatively new AHAK was a promising decontaminant and deserves further investigation.
