Non-linear model analysis of the relationship between cholinesterase activity in rats exposed to 2, 2-dichlorovinyl dimethylphosphate (dichlorvos) and its metabolite concentrations in urine

Mass spectrometry detection of organophosphorus pesticide adducts on butyrylcholinesterase and albumin

This study established a method to prepare and detect OPs adducts on butyrylcholinesterase (BChE) and human serum albumin (HSA). OPs (methyl paraoxon, ethyl paraoxon, methyl parathion, parathion) were incubated with BChE or HSA in vitro, and the adducts of OPs-BChE or OPs-HSA were prepared and qualitatively analyzed by ultra-performance liquid chromatography data-dependent high-resolution tandem mass spectrometry (UPLC-ddHRMS/MS). The amounts of BChE and HSA in the incubating systems were varied and the resulting amounts of the adducts were determined using linear regression. OPs-BChE in the blood were isolated by immunomagnetic separation (IMS), and then digested into the OPs-nonapeptide adduct by pepsin. The proteins in the remaining blood plasma were precipitated and digested by pronase to OPs-tyrosines(OPs-Tyr), which were quantified by UPLC-ddHRMS/MS. 4 OPs-nonapeptides and 4 OPs-Tyr adducts were obtained through the process above. The relative mass deviation of incubated adducts between the actual and theoretical exact masses was less than 10 ppm, and further confirmed by fragmentation mass spectra analysis. Calibration curves were linear for all adducts with a coefficient of determination value (R2) ≥0.995. The limits of detection (LOD) and limits of quantification (LOQ) for adducts detected by MS ranged from 0.05 to 1.0 ng/mL, and from 0.1 to 2.0 ng/mL, respectively. The recovery percentages for adducts ranged from 76.1 % to 107.1 %, matrix effects ranged from 83.4 % to 102.1 %. The inter-day and intra-day precision were 6.1-10.1 % and 6.9-12.9 % for adducts. This study provides a new reference method for the detection of organophosphorus pesticide poisoning. In addition, two blood samples with organophosphorus poisoning were tested by the designed method, and the corresponding adducts were detected in both samples.

Potential Common Mechanisms of Cytotoxicity Induced by Organophosphorus Pesticides via NLRP3 Inflammasome Activation

The Multi-Threat Medical Countermeasure (MTMC) technique is crucial for developing common biochemical signaling pathways, molecular mediators, and cellular processes. This study revealed that the Nod-like receptor 3 (NLRP3) inflammasome pathway may be a significant contributor to the cytotoxicity induced by various organophosphorus pesticides (OPPs). The study demonstrated that exposure to six different types of OPPs (paraoxon, dichlorvos, fenthion, dipterex, dibrom, and dimethoate) led to significant cytotoxicity in BV2 cells, which was accompanied by increased expression of NLRP3 inflammasome complexes (NLRP3, ASC, Caspase-1) and downstream inflammatory cytokines (IL-1β, IL-18), in which the order of cytotoxicity was dichlorvos > dipterex > dibrom > paraoxon > fenthion > dimethoate, based on the IC50 values of 274, 410, 551, 585, 2,158, and 1,527,566 μM, respectively. The findings suggest that targeting the NLRP3 inflammasome pathway could be a potential approach for developing broad-spectrum antitoxic drugs to combat multi-OPPs-induced toxicity. Moreover, inhibition of NLRP3 efficiently protected the cells against cytotoxicity induced by these six OPPs, and the expression of NLRP3, ASC, Caspase-1, IL-1β, and IL-18 decreased accordingly. The order of NLRP3 affinity for OPPs was dimethoate > paraoxon > dichlorvos > dibrom > (fenthion and dipterex) based on K D values of 89.8, 325, 1,460, and 2,690 μM, respectively. Furthermore, the common molecular mechanism of NLRP3-OPPs was clarified by the presence of toxicity effector groups (benzene ring, nitrogen/oxygen-containing functional group); =O, -O-, or =S (active) groups; and combination residues (Gly271, Asp272). This finding provided valuable insights into exploring the common mechanisms of multiple threats and developing effective therapeutic strategies to prevent OPPs poisoning.