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The halogenated solvent trichloroethylene (TCE) has had many uses in medicine, construction, consumer products, and the military. Many of these uses have been discontinued or restricted due to its toxicity, which affects multiple target organs and includes both acute, high-dose toxicity and chronic, low-dose toxicity that also encompass several cancers. US and international agencies have conducted risk and hazard assessments for TCE, with comprehensive publications coming out in the last 10-15 years. Accordingly, the focus of this article is to review recently published data since that time (i.e., 2014) that clarify unsettled questions or provide additional insights into the metabolism and mechanisms of toxicity of TCE in several target organs. Besides metabolism, the review focuses on the kidneys, liver, immune system, nervous system, cardiovascular and pulmonary systems, the search for biomarkers, and recent analyses of human cancer risk and incidence from TCE exposure.
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The tripeptide glutathione (GSH) possesses two key structural features, namely the nucleophilic sulfur and the γ-glutamyl isopeptide bond. The former allows GSH to serve as a critical antioxidant and anti-electrophile. The latter allows GSH to translocate throughout the systemic circulation without being degraded. The kidneys exhibit several unique processes for handling GSH. This includes the extraction of 80% of plasma GSH, in part by glomerular filtration but mostly by transport across the basolateral plasma membrane. Studies on the protective effect of exogenous GSH are summarized, showing the different inherent susceptibility of proximal tubular and distal tubular cells and the impact on pathological or disease states, including hypoxia, diabetic nephropathy, and compensatory renal growth associated with uninephrectomy. Studies on mitochondrial GSH transport show the coordination between the citric acid cycle and oxidative phosphorylation in generating driving forces for both plasma membrane and mitochondrial carriers. The strong protective effects of increasing expression and activity of these carriers against oxidants and mitochondrial toxicants are summarized. Although GSH plays a cytoprotective role in most situations, two distinct exceptions to this are presented. In contrast to expectations, overexpression of the mitochondrial 2-oxoglutarate carrier markedly increased cell death from exposure to the nephrotoxic chemotherapeutic drug cisplatin (CDDP). Another key example of GSH serving a bioactivation role in the kidneys, rather than a detoxification role, is the metabolism of halogenated alkenes such as trichloroethylene (TCE). Although considerable research has gone into this topic, unanswered questions and emerging topics remain and are discussed.
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Autoimmune diseases are multifactorial and include environmental as well as genetic drivers. Although much progress has been made in understanding the nature of genetic underpinnings of autoimmune disease, by comparison much less is understood regarding how environmental factors interact with genetics in the development of autoimmunity and autoimmune disease. In this report, we utilize the (NZB X NZW) F1 mouse model of Systemic Lupus Erythematosus (SLE). Mercury is a xenobiotic that is environmentally ubiquitous and is epidemiologically linked with the development of autoimmunity. Among other attributes of human SLE, (NZB X NZW) F1 mice spontaneously develop autoimmune-mediated kidney disease. It has been previously shown that if (NZB X NZW) F1 mice are exposed to inorganic mercury (Hg2+), the development of autoimmunity, including autoimmune kidney pathology, is accelerated. We now show that in these mice the development of kidney disease is correlated with a decreased percentage of marginal zone (MZ) B cells in the spleen. In Hg2+-intoxicated mice, kidney disease is significantly augmented, and matched by a greater decrease in MZ B cell splenic percentages than found in control mice. In Hg2+- intoxicated mice, the decrease in MZ B cells appears to be linked to aberrant B Cell Receptor (BCR) signal strength in transitory 2 (T2) B cells, developmental precursors of MZ B cells.
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Trichloroethylene (TCE) is a known human carcinogen with toxicity attributed to its metabolism. S-(1,2-Dichlorovinyl)-L-cysteine (DCVC) is a metabolite of TCE formed downstream in TCE glutathione (GSH) conjugation and is upstream of several toxic metabolites. Despite knowledge that DCVC stimulates reactive oxygen species (ROS) generation and apoptosis in placental cells, the extent to which these outcomes are attributable to DCVC metabolism is unknown. The current study used N-acetyl-L-cysteine (NAC) at 5 mM and aminooxyacetic acid (AOAA) at 1 mM as pharmacological modifiers of DCVC metabolism to investigate DCVC toxicity at concentrations of 5-50 µM in the human placental trophoblast BeWo cell model capable of forskolin-stimulated syncytialization. Exposures of unsyncytialized BeWo cells, BeWo cells undergoing syncytialization, and syncytialized BeWo cells were studied. NAC pre/co-treatment with DCVC either failed to inhibit or exacerbated DCVC-induced H2O2 abundance, PRDX2 mRNA expression, and BCL2 mRNA expression. Although NAC increased mRNA expression of CYP3A4, which would be consistent with increased generation of the toxic metabolite N-acetyl-DCVC sulfoxide (NAcDCVCS), a CYP3A4 inhibitor ketoconazole did not significantly alter BeWo cell responses. Moreover, AOAA failed to inhibit cysteine conjugate ß-lyase (CCBL), which bioactivates DCVC, and did not affect the percentage of nuclei condensed or fragmented, a measure of apoptosis, in all BeWo cell models. However, syncytialized cells had higher CCBL activity compared to unsyncytialized cells, suggesting that the former may be more sensitive to DCVC toxicity. Together, although neither NAC nor AOAA mitigated DCVC toxicity, differences in CCBL activity and potentially CYP3A4 expression dictated the differential toxicity derived from DCVC.
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Acetilcisteína , Tricloroetileno , Humanos , Feminino , Gravidez , Acetilcisteína/farmacologia , Acetilcisteína/metabolismo , Cisteína , Tricloroetileno/toxicidade , Tricloroetileno/metabolismo , Placenta/metabolismo , Ácido Amino-Oxiacético/metabolismo , Ácido Amino-Oxiacético/farmacologia , Trofoblastos/metabolismo , Citocromo P-450 CYP3A/metabolismo , Peróxido de Hidrogênio/metabolismo , RNA Mensageiro/metabolismoRESUMO
Biomarkers, defined as molecules in biological samples that are used as indicators of organ function, can assess exposure to potentially injurious chemicals, effects on organ function, or susceptibility to organ functional decline. The kidneys are frequently exposed to many drugs and chemicals and loss of kidney function is a frequent consequence of diseases such as diabetes. This review summarizes findings reported in 2021 and early-2022 from clinical and experimental animal studies on biomarkers, focusing on five topics: 1) Progression and severity of diabetic kidney disease; 2) acute kidney injury (AKI) and chronic kidney disease (CKD) severity and prognosis; 3) progression of AKI to CKD; 4) renal cell carcinoma (RCC) severity and prognosis; and 5) detection of exposure to environmental chemicals and nephrotoxic drugs.
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In previous studies, we identified the two principal transporters that mediate the uptake of glutathione (GSH) from cytoplasm into the mitochondrial matrix of rat kidney proximal tubular cells. We hypothesized that genetic modulation of transporter expression could markedly alter susceptibility of renal proximal tubular cells to a broad array of oxidants and mitochondrial toxicants. Indeed, we previously showed that overexpression of either of these transporters resulted in diminished susceptibility to several chemicals. In the present work, we investigated the influence of overexpression of the mitochondrial 2-oxoglutarate carrier (OGC) in NRK-52E cells on the cytotoxicity of the antineoplastic drug cisplatin. In contrast to previous results showing that overexpression of the mitochondrial OGC provided substantial protection of NRK-52E cells from injury due to several toxicants, we found a remarkable enhancement of cellular injury from exposure to cisplatin as compared to wild-type NRK-52E cells. Despite the oxidative stress that cisplatin is known to cause in the renal proximal tubule, the increased concentrations of mitochondrial GSH associated with OGC overexpression likely resulted in increased delivery of cisplatin to molecular targets and increased cellular injury rather than the typical protection observed in the previous work.
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Cisplatino/farmacologia , Glutationa/metabolismo , Túbulos Renais Proximais/efeitos dos fármacos , Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Transporte Biológico/efeitos dos fármacos , Linhagem Celular , Túbulos Renais Proximais/metabolismo , Mitocôndrias/metabolismo , Oxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , RatosRESUMO
Mitochondria are well-known to function as the primary sites of ATP synthesis in most mammalian cells, including the renal proximal tubule. Other functions have also been associated with different mitochondrial activities, including the regulation of redox status and the initiation of mitophagy and apoptosis. Mechanisms for the membrane transport of glutathione (GSH) and various GSH-derived metabolites across the mitochondrial inner membrane of renal proximal tubular cells are critical determinants of these functions and may serve as pharmacological targets for potential therapeutic approaches. Specific interactions of reactive intermediates, derived from drug metabolism, with molecular components in mitochondria have been identified as early steps in diverse forms of chemically-induced nephrotoxicity. Applying this key observation, we developed a novel hypothesis regarding the identification of early, sensitive, and specific biomarkers of exposure to nephrotoxicants. The underlying concept is that upon exposure to a diverse array of environmental contaminants, as well as therapeutic drugs whose efficacy is limited by nephrotoxicity, renal mitochondria will release both high- and low-molecular-weight components into the urine or the extracellular medium in an in vitro model. The detection of these components may then serve as indicators of exposure before irreversible renal injury has occurred.
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Nefropatias/induzido quimicamente , Mitocôndrias/metabolismo , Animais , Biomarcadores/urina , Poluentes Ambientais/toxicidade , Humanos , Nefropatias/metabolismo , Nefropatias/urina , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/metabolismo , Mitocôndrias/efeitos dos fármacos , Oxidantes/toxicidadeRESUMO
Exposure to the industrial solvent trichloroethylene (TCE) has been associated with adverse pregnancy outcomes in humans and decreased fetal weight in rats. TCE kidney toxicity can occur through formation of reactive metabolites via its glutathione (GSH) conjugation metabolic pathway, largely unstudied in the context of pregnancy. To investigate the contribution of the GSH conjugation pathway and oxidative stress to TCE toxicity during pregnancy, we exposed rats orally to 480 mg TCE/kg/day from gestational day (GD) 6 to GD 16 with and without N-acetyl-L-cysteine (NAC) at 200 mg/kg/day or aminooxyacetic acid (AOAA) at 20 mg/kg/day as pre/co-treatments from GD 5-16. NAC is a reactive oxygen species scavenger that modifies the GSH conjugation pathway, and AOAA is an inhibitor of cysteine conjugate ß-lyase (CCBL) in the GSH conjugation pathway. TCE decreased fetal weight, and this was prevented by AOAA but not NAC pre/co-treatment to TCE. Although AOAA inhibited CCBL activity in maternal kidney, it did not inhibit CCBL activity in maternal liver and placenta, suggesting that AOAA prevention of TCE-induced decreased fetal weight was due to CCBL activity inhibition in the kidneys but not liver or placenta. Unexpectedly, NAC pre/co-treatment with TCE, relative to TCE treatment alone, altered placental morphology consistent with delayed developmental phenotype. Immunohistochemical staining revealed that the decidua basale, relative to basal and labyrinth zones, expressed the highest abundance of CCBL1, flavin-containing monooxygenase 3, and cleaved caspase-3. Together, the findings show the differential effects of NAC and AOAA on TCE-induced pregnancy outcomes are likely attributable to TCE metabolism modulation.
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Acetilcisteína/farmacologia , Ácido Amino-Oxiacético/farmacologia , Reprodução/efeitos dos fármacos , Tricloroetileno/toxicidade , Animais , Inibidores Enzimáticos/farmacologia , Feminino , Sequestradores de Radicais Livres/farmacologia , Glutationa/metabolismo , Masculino , Estresse Oxidativo/efeitos dos fármacos , Placenta/efeitos dos fármacos , Gravidez , Resultado da Gravidez , Ratos , Ratos Wistar , Solventes/metabolismo , Solventes/toxicidade , Tricloroetileno/metabolismoRESUMO
Trichloroethylene (TCE) is an industrial solvent and a common environmental contaminant detected in thousands of hazardous waste sites. Risk of exposure is a concern for workers in occupations that use TCE as well as for residents who live near industries that use TCE or who live near TCE-contaminated sites. Although renal, hepatic and carcinogenic effects of TCE have been documented, less is known about TCE impacts on reproductive functions despite epidemiology reports associating maternal TCE exposure with adverse pregnancy outcomes. Toxicological evidence suggests that the placenta mediates at least some of the adverse pregnancy outcomes associated with TCE exposure. Toxicology studies show that the TCE metabolite, S-(1,2-dichlorovinyl)-l-cysteine (DCVC) generates toxic effects such as mitochondrial dysfunction, apoptosis, oxidative stress, and release of prostaglandins and pro-inflammatory cytokines in placental cell lines. Each of these mechanisms of toxicity have significant implications for placental functions and, thus, ultimately the health of mother and developing child. Despite these findings there remain significant gaps in our knowledge about effects of TCE on the placenta, including effects on specific placental cell types and functions as well as sex differences in response to TCE exposure. Due to the critical role that the placenta plays in pregnancy, future research addressing some of these knowledge gaps could lead to significant gains in public health.
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Placenta/efeitos dos fármacos , Tricloroetileno/toxicidade , Criança , Cisteína , Feminino , Humanos , Masculino , Estresse Oxidativo , Gravidez , SolventesRESUMO
Next-generation sequencing (NGS) of amplicons is used in a wide variety of contexts. In many cases, NGS amplicon sequencing remains overly expensive and inflexible, with library preparation strategies relying upon the fusion of locus-specific primers to full-length adapter sequences with a single identifying sequence or ligating adapters onto PCR products. In Adapterama I, we presented universal stubs and primers to produce thousands of unique index combinations and a modifiable system for incorporating them into Illumina libraries. Here, we describe multiple ways to use the Adapterama system and other approaches for amplicon sequencing on Illumina instruments. In the variant we use most frequently for large-scale projects, we fuse partial adapter sequences (TruSeq or Nextera) onto the 5' end of locus-specific PCR primers with variable-length tag sequences between the adapter and locus-specific sequences. These fusion primers can be used combinatorially to amplify samples within a 96-well plate (8 forward primers + 12 reverse primers yield 8 × 12 = 96 combinations), and the resulting amplicons can be pooled. The initial PCR products then serve as template for a second round of PCR with dual-indexed iTru or iNext primers (also used combinatorially) to make full-length libraries. The resulting quadruple-indexed amplicons have diversity at most base positions and can be pooled with any standard Illumina library for sequencing. The number of sequencing reads from the amplicon pools can be adjusted, facilitating deep sequencing when required or reducing sequencing costs per sample to an economically trivial amount when deep coverage is not needed. We demonstrate the utility and versatility of our approaches with results from six projects using different implementations of our protocols. Thus, we show that these methods facilitate amplicon library construction for Illumina instruments at reduced cost with increased flexibility. A simple web page to design fusion primers compatible with iTru primers is available at: http://baddna.uga.edu/tools-taggi.html. A fast and easy to use program to demultiplex amplicon pools with internal indexes is available at: https://github.com/lefeverde/Mr_Demuxy.
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The kidneys are a frequent target organ for toxicity from exposures to various environmental chemicals and agents. To understand the risk to human health from such exposures, it is important to consider both the underlying chemical and pathologic mechanisms and factors that may modify susceptibility to injury. Choices of exemplary environmental agents to review are based on those with selective effects on the kidneys and for which significant amounts of mechanistic and human data are available. These include the heavy metals cadmium and arsenic, fluoride, the organic solvents trichloroethylene and perchloroethylene, drinking water disinfection by-products haloacids, food and herbal drug contaminants aristolochic acid and melamine, and heat stress. Some common mechanistic features of all these diverse exposures are highlighted, and include oxidative stress and mitochondrial damage. Two major genetic factors that are discussed include genetic polymorphisms in plasma membrane transporters that catalyze uptake and accumulation or efflux and elimination of environmental chemicals, and genetic polymorphisms in bioactivation enzymes that generate toxic and reactive metabolites. Identification of methods to prevent environmental toxicant-associated kidney damage and understanding the genetic factors that influence kidney function and the kidney's response to exposures can be applied to refine risk assessments.
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Injúria Renal Aguda/induzido quimicamente , Metais Pesados/efeitos adversos , Insuficiência Renal Crônica/induzido quimicamente , Solventes/efeitos adversos , Ativação Metabólica/genética , Injúria Renal Aguda/genética , Ácidos Aristolóquicos/efeitos adversos , Arsênio/efeitos adversos , Cádmio/efeitos adversos , Contaminação de Medicamentos , Fluoretos/efeitos adversos , Contaminação de Alimentos , Humanos , Necrose do Córtex Renal , Proteínas de Membrana Transportadoras/genética , Estresse Oxidativo , Preparações de Plantas , Insuficiência Renal Crônica/genética , Tetracloroetileno/efeitos adversos , Triazinas/efeitos adversos , Tricloroetileno/efeitos adversosRESUMO
Bromate (BrO3-) is a water disinfection byproduct (DBP) previously shown to induce nephrotoxicity in vitro and in vivo. We recently showed that inhibitors of DNA methyltransferase 5-aza-2'-deoxycytidine (5-Aza) and histone deacetylase trichostatin A (TSA) increased BrO3- nephrotoxicity whereas altering the expression of the cyclin-dependent kinase inhibitor p21. Human embryonic kidney cells (HEK293) and normal rat kidney (NRK) cells were sub-chronically exposed to BrO3- or epigenetic inhibitors for 18 days, followed by 9 days of withdrawal. DNA methylation was studied using a modification of bisulfite amplicon sequencing called targeted gene bisulfite sequencing. Basal promoter methylation in the human p21 promoter region was substantially lower than that of the rat DNA. Furthermore, 5-Aza decreased DNA methylation in HEK293 cells at the sis-inducible element at 3 distinct CpG sites located at 691, 855, and 895 bp upstream of transcription start site (TSS). 5-Aza also decreased methylation at the rat p21 promoter about 250 bp upstream of the p21 TSS. In contrast, sub-chronic BrO3- exposure failed to alter methylation in human or rat renal cells. BrO3- exposure altered histone acetylation in NRK cells at the p21 TSS, but not in HEK293 cells. Interestingly, changes in DNA methylation induced by 5-Aza persisted after its removal; however, TSA- and BrO3--induced histone hyperacetylation returned to basal levels after 3 days of withdrawal. These data demonstrate novel sites within the p21 gene that are epigenetically regulated and further show that significant differences exist in the epigenetic landscape between rat and human p21, especially with regards to toxicant-induced changes in histone acetylation.
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Bromatos/toxicidade , Inibidor de Quinase Dependente de Ciclina p21/genética , Metilação de DNA/efeitos dos fármacos , Desinfetantes/toxicidade , Histonas/metabolismo , Rim/efeitos dos fármacos , Acetilação , Técnicas de Cultura de Células , DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , Decitabina/farmacologia , Células HEK293 , Histona Desacetilases/metabolismo , Humanos , Ácidos Hidroxâmicos/farmacologia , Rim/metabolismoRESUMO
Although epidemiology studies have associated maternal trichloroethylene (TCE) exposure with decreased birth weight and preterm birth, mechanistic explanations for these associations are currently lacking. We hypothesized that TCE targets the placenta with adverse consequences for pregnancy outcomes. Pregnant Wistar rats were exposed orally to vehicle or 480 mg TCE/kg body weight from gestational days (gd) 6-16, and tissues were collected on gd 16. Exposure to TCE significantly decreased average fetal weight without reducing maternal weight. In placenta, TCE significantly increased 8-hydroxy-deoxyguanosine, global 5-hydroxymethylcytosine, and mRNA expression of Tet3, which codes for an enzyme involved in 5-hydroxymethylcytosine formation. Furthermore, glutathione S-transferase activity and immunohistochemical staining were increased in placentas of TCE-exposed rats. The present study provides the first evidence that TCE increases markers of oxidative stress in placenta in a fetal growth restriction rat model, providing new insight into the placenta as a potentially relevant target for TCE-induced adverse pregnancy outcomes.
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Peso Fetal/efeitos dos fármacos , Placenta/efeitos dos fármacos , Solventes/toxicidade , Tricloroetileno/toxicidade , 5-Metilcitosina/análogos & derivados , 5-Metilcitosina/metabolismo , 8-Hidroxi-2'-Desoxiguanosina , Animais , Biomarcadores/metabolismo , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Dioxigenases/genética , Feminino , Troca Materno-Fetal , Estresse Oxidativo/efeitos dos fármacos , Placenta/metabolismo , Gravidez , Ratos WistarRESUMO
The role of plasma membrane transporters in the nephrotoxicity of two antiretroviral drugs, cidofovir and tenofovir, was studied in primary cultures of human proximal tubular (hPT) cells. Cells were grown on Transwell filter inserts to maintain epithelial polarity and access to either the apical or basolateral plasma membrane. The function of relevant membrane transporters, organic anion transporter 1 and 3 (OAT1/3), P-glycoprotein (multidrug resistance protein-1; P-gp or MDR1), and organic cation transporter 2 (OCT2), was validated by measurements of apical-to-basolateral and basolateral-to-apical fluxes of furosemide, digoxin, and metformin, respectively. Acute cytotoxicity of cidofovir (0, 10, 50, 150, or 300⯵M) in the absence or presence of 500⯵M probenecid, tenofovir disoproxil fumarate (0, 20, 90, 180, or 360⯵M) in the absence or presence of 500⯵M probenecid, or cisplatin (0, 20, 90, 180, or 360⯵M) as a positive control in the absence or presence of 500⯵M cimetidine, was assessed after 4-h incubations by determinations of release of lactate dehydrogenase (LDH), γ-glutamyltransferase (GGT), N-acetyl-ß-d-glucosaminidase (NAG), or Kidney Injury Molecule-1 (KIM-1). Cell death generally agreed with each of the four biomarkers, was generally greater when cidofovir or tenofovir was added to the upper compartment, and was markedly diminished in the presence of the appropriate transport inhibitor. Additionally, the extent of cytotoxicity caused by the two antiviral drugs was similar to that caused by cisplatin. The results demonstrate the importance of plasma membrane transport of antiviral drugs to elicit cytotoxicity in the hPT cell.
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Antivirais/metabolismo , Antivirais/toxicidade , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/metabolismo , Transportador 2 de Cátion Orgânico/metabolismo , Idoso , Células Cultivadas , Citotoxinas/metabolismo , Citotoxinas/toxicidade , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Resistance to the last-resort antibiotic colistin is now widespread and new therapeutics are urgently required. We report the first in toto chemical synthesis and pre-clinical evaluation of octapeptins, a class of lipopeptides structurally related to colistin. The octapeptin biosynthetic cluster consisted of three non-ribosomal peptide synthetases (OctA, OctB, and OctC) that produced an amphiphilic antibiotic, octapeptin C4, which was shown to bind to and depolarize membranes. While active against multi-drug resistant (MDR) strains in vitro, octapeptin C4 displayed poor in vivo efficacy, most likely due to high plasma protein binding. Nuclear magnetic resonance solution structures, empirical structure-activity and structure-toxicity models were used to design synthetic octapeptins active against MDR and extensively drug-resistant (XDR) bacteria. The scaffold was then subtly altered to reduce plasma protein binding, while maintaining activity against MDR and XDR bacteria. In vivo efficacy was demonstrated in a murine bacteremia model with a colistin-resistant P. aeruginosa clinical isolate.
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Antibacterianos/química , Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Lipopeptídeos/química , Lipopeptídeos/farmacologia , Animais , Antibacterianos/efeitos adversos , Antibacterianos/uso terapêutico , Modelos Animais de Doenças , Farmacorresistência Bacteriana , Feminino , Humanos , Lipopeptídeos/efeitos adversos , Lipopeptídeos/uso terapêutico , Camundongos , Modelos Moleculares , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/efeitos dos fármacosRESUMO
Trichloroethylene (TCE) is a persistent environmental contaminant proposed to contribute to autoimmune disease. Experimental studies in lupus-prone MRL+/+ mice have suggested that TCE exposure can trigger autoimmune hepatitis. The vast majority of studies examining the connection between TCE and autoimmunity utilize this model, and the impact of TCE exposure in other established models of autoimmune liver disease is not known. We tested the hypothesis that TCE exposure exacerbates experimental hepatic autoimmunity in dominant negative transforming growth factor beta receptor type II (dnTGFBRII) mice, which develop serological and histological features resembling human primary biliary cholangitis. Female 8-week-old wild-type and dnTGFBRII mice were exposed to TCE (0.5 mg/ml) or vehicle (1% ethoxylated castor oil) in the drinking water for 12 or 22 weeks. Liver histopathology in 20- and 30-week-old wild-type mice was unremarkable irrespective of treatment. Mild portal inflammation was observed in vehicle-exposed 20-week-old dnTGFBRII mice and was not exacerbated by TCE exposure. Vehicle-exposed 30-week-old dnTGFBRII mice developed anti-mitochondrial antibodies, marked hepatic inflammation with necrosis, and hepatic accumulation of both B and T lymphocytes. To our surprise, TCE exposure dramatically reduced hepatic parenchymal inflammation and injury in 30-week-old dnTGFBRII mice, reflected by changes in hepatic proinflammatory gene expression, serum chemistry, and histopathology. Interestingly, TCE did not affect hepatic B cell accumulation or induction of the anti-inflammatory cytokine IL10. These data indicate that TCE exposure reduces autoimmune liver injury in female dnTGFBRII mice and suggests that the precise effect of environmental chemicals in autoimmunity depends on the experimental model.
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Doença Hepática Induzida por Substâncias e Drogas/imunologia , Colangite/imunologia , Modelos Animais de Doenças , Hepatite Autoimune/imunologia , Tricloroetileno/toxicidade , Animais , Autoanticorpos/sangue , Doença Hepática Induzida por Substâncias e Drogas/genética , Doença Hepática Induzida por Substâncias e Drogas/patologia , Colangite/genética , Colangite/patologia , Feminino , Interação Gene-Ambiente , Hepatite Autoimune/genética , Hepatite Autoimune/patologia , Masculino , Camundongos Transgênicos , Proteínas Serina-Treonina Quinases/genética , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/genéticaRESUMO
Trichloroethylene (TCE) is a common environmental pollutant associated with adverse reproductive outcomes in humans. TCE intoxication occurs primarily through its biotransformation to bioactive metabolites, including S-(1,2-dichlorovinyl)-l-cysteine (DCVC). TCE induces oxidative stress and inflammation in the liver and kidney. Although the placenta is capable of xenobiotic metabolism and oxidative stress and inflammation in placenta have been associated with adverse pregnancy outcomes, TCE toxicity in the placenta remains poorly understood. We determined the effects of DCVC by using the human extravillous trophoblast cell line HTR-8/SVneo. Exposure to 10 and 20 µM DCVC for 10 h increased reactive oxygen species (ROS) as measured by carboxydichlorofluorescein fluorescence. Moreover, 10 and 20 µM DCVC increased mRNA expression and release of interleukin-6 (IL-6) after 24-h exposure, and these responses were inhibited by the cysteine conjugate beta-lyase inhibitor aminooxyacetic acid and by treatments with antioxidants (alpha-tocopherol and deferoxamine), suggesting that DCVC-stimulated IL-6 release in HTR-8/SVneo cells is dependent on beta-lyase metabolic activation and increased generation of ROS. HTR-8/SVneo cells exhibited decreased mitochondrial membrane potential at 5, 10, and 20 µM DCVC at 5, 10, and 24 h, showing that DCVC induces mitochondrial dysfunction in HTR-8/Svneo cells. The present study demonstrates that DCVC stimulated ROS generation in the human placental cell line HTR-8/SVneo and provides new evidence of mechanistic linkage between DCVC-stimulated ROS and increase in proinflammatory cytokine IL-6. Because abnormal activation of cytokines can disrupt trophoblast functions necessary for placental development and successful pregnancy, follow-up investigations relating these findings to physiologic outcomes are warranted.