Fluorine impairs carboxylesterase 1-mediated hydrolysis of T-2 toxin and increases its chondrocyte toxicity

Abstract

BackgroundT-2 toxin is recognized as one of the high-risk environmental factors for etiology and pathogenesis of Kashin-Beck disease (KBD). Previous evidence indicates decreased serum fluorine level in KBD patients. However, whether fluoride could regulate carboxylesterase 1 (CES1)-mediated T-2 toxin hydrolysis and alter its chondrocyte toxicity remains largely unknown.MethodsIn this study, in vitro hydrolytic kinetics were explored using recombinant human CES1. HPLC-MS/MS was used to quantitative determination of hydrolytic metabolites of T-2 toxin. HepG2 cells were treated with different concentration of sodium fluoride (NaF). qRT-PCR and western blot analysis were used to compare the mRNA and protein expression levels of CES1. C28/I2 cells were treated with T-2 toxin, HT-2 toxin, and neosolaniol (NEO), and then cell viability was determined by MTT assay, cell apoptosis was determined by Annexin V-FITC/PI, Hoechst 33258 staining, and cleaved caspase-3, and cell cycle was monitored by flow cytometry assay, CKD4 and CDK6.ResultsWe identified that recombinant human CES1 was involved in T-2 toxin hydrolysis to generate HT-2 toxin, but not NEO, and NaF repressed the formation of HT-2 toxin. Both mRNA and protein expression of CES1 were significantly down-regulated in a dose-dependent manner after NaF treatment in HepG2 cells. Moreover, we evaluated the chondrocyte toxicity of T-2 toxin and its hydrolytic metabolites. Results showed that T-2 toxin induced strongest cell apoptosis, followed by HT-2 toxin and NEO. The decreased the proportion of cells in G0/G1 phase was observed with the descending order of T-2 toxin, HT-2 toxin, and NEO.ConclusionsThis study reveals that CES1 is responsible for the hydrolysis of T-2 toxin, and that fluoride impairs CES1-mediated T-2 toxin detoxification to increase its chondrocyte toxicity. This study provides novel insight into understanding the relationship between fluoride and T-2 toxin in the etiology of KBD.

Use of in vitro ADME methods to identify suitable analogs of homosalate and octisalate for use in a read‐across safety assessment

“…1110370) was from Xenotech, United States. Test chemicals (100 μM) were incubated in a total volume of 1.2 ml in 96‐well microtubes (ABgene®, Thermo Fisher Scientific, Illkirch Cedex, France) under three conditions: (1) with liver S9 and cofactors; (2) with heat‐inactivated liver S9 plus 100 mM NaF (an inhibitor of carboxylesterase‐1 [CES1] mediated hydrolysis; Jia et al, 2022) and no cofactors and (3) with cofactors but no liver S9. Heat‐inactivated liver S9 was prepared by boiling for 10 min at 100°C.…”

“…plus 100 mM NaF (an inhibitor of carboxylesterase-1 [CES1] mediated hydrolysis;Jia et al, 2022) and no cofactors and (3) with cofactors but no liver S9. Heat-inactivated liver S9 was prepared by boiling for 10 min at 100 C. The final concentrations of cofactors in sodium phosphate buffer (0.1 M, pH 7.4 with 5 mM MgCl 2 , 0.01% pluronic acid) were 150 μM NADPH, 100 μM acetyl-CoA, 1,000 μM reduced glutathione, 2,000 μM UDP-glucuronic acid, 150 μM adenosine 3 0phosphate 5 0 phosphosulfate, 150 μM NAD, and 1,500 μM SAM.…”

Expression Profiles of Long Non-Coding RNAs in the Articular Cartilage of Rats Exposed to T-2 Toxin

“…Autophagy can be divided into four processes: (1) the activation of autophagy: the ATG1/ULK1-containing complex is involved in this process; (2) autophagosome formation: PI3K-ATG14, ATG18, and the ATG5-ATG12-ATG16L1 complex is involved in autophagosome expansion and maturation as well as in ATG3, ATG4, and ATG7-mediated lipidation of LC3; (3) the transport and fusion of autophagosomes with lysosomes; (4) degradation and recycling: hydrolases degrade the autophagosome, release degradation products into the cytosol, and then recycle them [ 9 ]. T-2 toxin is widely recognized as an important etiology of the Kashin–Beck disease (KBD) [ 10 , 11 ]. It is characterized by deep necrosis of the epiphysis plate and articular cartilage with a higher rate of disability, which greatly burdens the diseased person’s family and society [ 12 , 13 ].…”