Inhalation pharmacokinetics of 1,2-dichloroethane after different dietary pretreatments of male Sprague-Dawley rats

Liao

Sun

et al. 2017

Front. Cell. Neurosci.

2-Chloroethanol (2-CE) is one of the reactive metabolites of 1,2-DCE in vivo, which might contribute to brain edema formation induced by 1,2-dichloroethane (1,2-DCE) poisoning. Thus, the purpose of this study was to explore the roles of mitogen-activated protein kinase (MAPK) signal pathways in upregulation of matrix metalloproteinase-9 (MMP-9) in 2-CE exposed rat astrocytes. Expression of p38 MAPK (p38), extracellular signal regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK) and MMP-9 at both protein and gene levels in rat astrocytes were determined using western blot and real-time RT-PCR methods. The results showed that both protein and mRNA levels of MMP-9 in 2-CE exposed astrocytes significantly increased. Meanwhile, protein levels of phosphorylated p38 (p-p38), ERK1/2 (p-ERK1/2) and JNK1/2 (p-JNK1/2) in 2-CE exposed astrocytes also significantly increased. In addition, both protein and mRNA levels of MMP-9 significantly decreased in response to reduced protein levels of p-p38, p-ERK1/2 and p-JNK1/2 achieved by supplement with their specific inhibitors, indicating that activation of MAPK signal pathways might play an important role in upregulation of MMP-9 expression at the transcriptional level in 2-CE exposed astrocytes. Furthermore, since pretreatment of n-acetyl-l-cysteine (NAC), a powerful antioxidant amino acid, could attenuate the elevated levels of MMP-9, p-p38, p-ERK2 and p-JNK1/2 in 2-CE exposed astrocytes, activation of MAPK signal pathways in 2-CE exposed astrocytes could be mediated partially by reactive oxygen species (ROS), which was most likely generated in the metabolism of 2-CE.

Section: Introductionmentioning

confidence: 99%

Upregulation of Matrix Metalloproteinase-9 in Primary Cultured Rat Astrocytes Induced by 2-Chloroethanol Via MAPK Signal Pathways

Liao

Sun

et al. 2017

Front. Cell. Neurosci.

“…Although its expression in the brain is much lower than in the liver, the enzyme is highly concentrated and inducible in the cortical astrocytes [34][35][36][37]. It has been reported that CYP2E1 can convert 1,2-DCE into 2-CE, chloroacetaldehyde and chloroacetic acid [38][39][40][41]. Because of the high oxidase activity, CYP2E1-mediated metabolism of 1,2-DCE and its intermediates can lead to the generation of ROS, as a consequence induce oxidative damage in the brain [20,33] The present results revealed that CYP2E1 knockdown reversed 2-CE-induced augmentation of ROS production and A1s induction, suggesting that ROS production is involved in A1 activation.…”

Section: Discussionmentioning

confidence: 99%

A1 Reactive Astrocytes Activated by 2-chloroethanol Modulate M1 Microglia Polarization through Upregulating IL-1β and TNF-α

Sun

Tang

et al. 2021

Preprint

Background1,2-Dichloroethane (1,2-DCE) is a synthetic organic chemical that causes brain edema under subacute poisoning. Our previous studies indicated that the neuroinflammation could be induced due to activation of both astrocytes and microglia during the course of brain edema in 1,2-DCE intoxicated mice. However, the crosstalk between the two glial cells in 1,2-DCE-induced neuroinflammation is unclear. In the current studies, we hypothesized that astrocytes are the first responder to the effects of 1,2-DCE in the brain, as they adhere to the cerebral capillaries, and they are an essential component of the blood-brain barrier (BBB).MethodsWe used primary cultured rat astrocytes and microglia, as well as a highly aggressively proliferating immortalized (HAPI) microglia cell line to study the effects of astrocytes on microglia polarization following exposure to 2-CE. ResultsFindings from the present studies demonstrated that treatment of primary rat astrocytes with 2-chloroethanol (2-CE), the intermediate metabolite of 1,2-DCE in vivo, can stimulate the activation of A1 reactive astrocytes (A1s) through p38 mitogen-activated protein kinase (p38 MAPK)/ nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) signaling pathways by the reactive oxygen species (ROS) produced during 2-CE metabolism. A1s activated by 2-CE can upregulate the expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and inducible nitric oxide synthase (iNOS), and stimulate the M1 polarization of microglia through IL-1β and TNF-α released by 2-CE activated A1s. Microglia are less sensitive to 2-CE than astrocytes, since treatment of primary rat microglia with 30 mM 2-CE alone failed to activate them, though this dose of 2-CE can activate A1s and in turn stimulate M1 polarization of microglia through the factors released by A1s. ConclusionThe neuroinflammation induced by 1,2-DCE in the brain of mice is most probably triggered by the activation of astrocytes. The understanding of the multidimensional roles of reactive astrocytes may further the development of new treatment strategies in reducing neuroinflammation and brain edema following 1,2-DCE-induced toxic encephalopathy.

“…Previous studies have shown that 2-chloroethanol (2-CE), a metabolite of 1,2-DCE generated in vivo via microsomal CYP2E1, is more reactive than its parent molecule, and therefore might play an important role in the toxic effects of 1,2-DCE [ 4 , 5 , 6 ]. Our studies showed that matrix metalloproteinases-9 (MMP-9) was transcriptionally upregulated in 2-CE-treated astrocytes in vitro [ 7 ], as well as in the early phase of brain edema induced by subacute 1,2-DCE poisoning in mice [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

Association of NF-κB and AP-1 with MMP-9 Overexpression in 2-Chloroethanol Exposed Rat Astrocytes

Jin

Liao

et al. 2018

Cells

Subacute poisoning of 1,2-dichloroethane (1,2-DCE) has become a serious occupational problem in China, and brain edema is its main pathological consequence, but little is known about the underlying mechanisms. As the metabolite of 1,2-DCE, 2-chloroethanol (2-CE) is more reactive, and might play an important role in the toxic effects of 1,2-DCE. In our previous studies, we found that matrix metalloproteinases-9 (MMP-9) expression was enhanced in mouse brains upon treatment with 1,2-DCE, and in rat astrocytes exposed to 2-CE. In the present study, we analyzed the association of nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1) with MMP-9 overexpression in astrocytes treated with 2-CE. MMP-9, p65, c-Jun, and c-Fos were significantly upregulated by 2-CE treatment, which also enhanced phosphorylation of c-Jun, c-Fos and inhibitor of κBα (IκBα), and nuclear translocation of p65. Furthermore, inhibition of IκBα phosphorylation and AP-1 activity with the specific inhibitors could attenuate MMP-9 overexpression in the cells. On the other hand, inhibition of p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway suppressed the activation of both NF-κB and AP-1 in 2-CE-treated astrocytes. In conclusion, MMP-9 overexpression induced by 2-CE in astrocytes could be mediated at least in part through the p38 signaling pathway via activation of both NF-κB and AP-1. This study might provide novel clues for clarifying the mechanisms underlying 1,2-DCE associated cerebral edema.