Occupational trichloroethylene exposure as a cause of idiosyncratic generalized skin disorders and accompanying hepatitis similar to drug hypersensitivities

Autophagy dysregulation in trichloroethene-mediated inflammation and autoimmune response

Trichloroethene (TCE), an organic solvent extensively used for degreasing metals, can cause inflammatory autoimmune disorders [i.e., systemic lupus erythematosus (SLE) and autoimmune hepatitis] from both environmental and occupational exposure. Autophagy has emerged as a pivotal pathogenic factor in various autoimmune diseases. However, role of autophagy dysregulation in TCE-mediated autoimmunity is largely unknown. Here, we investigate whether autophagy dysregulation contributes to pathogenesis of TCE-mediated autoimmune responses. Using our established mouse model, we observed TCE-treated mice had elevated MDA-protein adducts, microtubule-associated protein light chain 3 conversion (LC3-II/LC3-I), beclin-1, phosphorylation of AMP-activated protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) phosphorylation in the livers of MRL+ /+ mice. Suppression of oxidative stress with antioxidant N-acetylcysteine (NAC) effectively blocked TCE-mediated induction of autophagy markers. On the other hand, pharmacological autophagy induction with rapamycin significantly reduced TCE-mediated hepatic inflammation (NLRP3, ASC, Caspase1 and IL1-β mRNA levels), systemic cytokines (IL-12 and IL-17) and autoimmune responses (ANA and anti-dsDNA levels). Taken together, these results suggest that autophagy plays a protective role against TCE-mediated hepatic inflammation and autoimmunity in MRL+ /+ mice. These novel findings on the regulation of autophagy could help in designing therapeutic strategies for chemical exposure-mediated autoimmune responses.

Application of multiple occupational health risk assessment models in occupation health risk prediction of trichloroethylene in the electroplating and electronics industries

Objectives. This study assessed the occupational health risks of work group exposure to trichloroethylene (TCE) in the electroplating and electronics industries in China. Methods. The UK Control of Substances Hazardous to Health (COSHH) Essential, the US Environmental Protection Agency (EPA) and the Singapore and the Chinese semiquantitative risk assessment models were used to assess the risks of TCE. Twenty degreasing groups and 14 cleaning groups were recruited in the companies selected. Results. The concentrations of TCE in 66.7% of the cleaning groups and 35.0% of the degreasing groups exceeded the permissible concentration time-weighted average (PC-TWA) in China, and the concentrations of TCE in 100.0% of the cleaning groups and 70.0% of the degreasing groups exceeded the permissible concentration short-term exposure limit (PC-STEL) in China. Over 60.0% of the work groups were evaluated at high risk and over half of the work groups were evaluated at high cancer risk by the risk assessment models. Conclusion. Most work groups exposed to TCE in the electroplating and electronics industries in China are at high risk. The cleaning groups may have a higher risk for TCE exposure. The Chinese exposure index method and the synthesis index method are more practical than the other methods.

Oral ingestion of the environmental toxicant trichloroethylene in rats induces alterations in the gut microbiome: Relevance to idiopathic Parkinson's disease

Microbial alterations within the gut microbiome appear to be a common feature of individuals with Parkinson's disease (PD), providing further evidence for the role of the gut-brain axis in PD development. As a major site of contact with the environment, questions have emerged surrounding the cause and effect of alterations to the gut microbiome by environmental contaminants associated with PD risk, such as pesticides, metals, and organic solvents. Recent data from our lab shows that ingestion of the industrial byproduct and environmental pollutant trichloroethylene (TCE) induces key Parkinsonian pathology within aged rats, including the degeneration of dopaminergic neurons, α-synuclein accumulation, neuroinflammation, and endolysosomal deficits. As TCE is the most common organic contaminant within drinking water, we postulated that ingestion of TCE associated with PD-related neurodegeneration may alter the gut microbiome to a similar extent as observed in persons with PD. To assess this, we collected fecal samples from adult rats treated with 200 mg/kg TCE over 6 weeks via oral gavage - the dose that produced nigrostriatal neurodegeneration - and analyzed the gut microbiome via whole genome shotgun sequencing. Our results showed changes in gut microorganisms reflective of the microbial signatures observed in individuals with idiopathic PD, such as decreased abundance of short-chain fatty acid producing Blautia and elevated lactic-acid producing Bifidobacteria, as well as genera who contain species previously reported as opportunistic pathogens such as Clostridium. From these experimental data, we postulate that TCE exposure within contaminated drinking water could induce alterations of the gut microbiome that contributes to chronic disease risk, including idiopathic PD.

Increased serum anti-CYP2E1 IgG autoantibody levels may be involved in the pathogenesis of occupational trichloroethylene hypersensitivity syndrome: a case-control study

Occupational exposure to trichloroethylene (TCE) causes a systemic skin disorder with hepatitis known as TCE hypersensitivity syndrome (TCE-HS). Human Leukocyte Antigen (HLA)-B*13:01 is its susceptibility factor; however, the immunological pathogenesis of TCE-HS remains unknown. We herein examined the hypothesis that autoantibodies to CYP2E1 are primarily involved in TCE-HS. A case–control study of 80 TCE-HS patients, 186 TCE-tolerant controls (TCE-TC), and 71 TCE-nonexposed controls (TCE-nonEC) was conducted to measure their serum anti-CYP2E1 antibody (IgG) levels. The effects of TCE exposure indices, such as 8-h time-weighted-average (TWA) airborne concentrations, urinary metabolite concentrations, and TCE usage duration; sex; smoking and drinking habits; and alanine aminotransferase (ALT) levels on the antibody levels were also analyzed in the two control groups. There were significant differences in anti-CYP2E1 antibody levels among the three groups: TCE-TC > TCE-HS patients > TCE-nonEC. Antibody levels were not different between HLA-B*13:01 carriers and noncarriers in TCE-HS patients and TCE-TC. The serum CYP2E1 measurement suggested increased immunocomplex levels only in patients with TCE-HS. Multiple regression analysis for the two control groups showed that the antibody levels were significantly higher by the TCE exposure. Women had higher antibody levels than men; however, smoking, drinking, and ALT levels did not affect the anti-CYP2E1 antibody levels. Anti-CYP2E1 antibodies were elevated at concentrations lower than the TWA concentration of 2.5 ppm for TCE exposure. Since HLA-B*13:01 polymorphism was not involved in the autoantibody levels, the possible mechanism underlying the pathogenesis of TCE-HS is that TCE exposure induces anti-CYP2E1 autoantibody production, and HLA-B*13:01 is involved in the development of TCE-HS.

Serum levels of miR-21-5p and miR-339-5p associate with occupational trichloroethylene hypersensitivity syndrome

Background

Trichloroethylene (TCE) hypersensitivity syndrome (THS) is a dose-independent and potentially life-threatening disease. In this study, we sought to identify THS-related miRNAs and evaluate its potential clinical value.

Methods

Serum samples of five patients and five matched TCE contacts were used for screening differential miRNAs. Another 34 patients and 34 matched TCE contacts were used for verifying significantly differential miRNAs with SYBR™ Green PCR and MGB PCR. The diagnostic model based on these miRNAs was established via the support vector machine (SVM) algorithm. Correlation between differential miRNAs and liver function was analyzed via the Spearman correlation test.

Results

A total of 69 miRNAs was found to be differentially expressed. MiR-21-5p and miR-339-5p were verified to have significant higher expressions in patients. The sensitivity, specificity and accuracy of disease model were 100, 75 and 86%, respectively. The two miRNAs showed significant correlations with liver function.

Conclusion

These findings suggested that miRNAs profiles in serum of THS patients had changed significantly, and miR-21-5p and miR-339-5p were associated with THS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12995-021-00308-0.

Dynamic analysis of peripheral blood TCR β-chain CDR3 repertoire in occupational medicamentosa-like dermatitis due to trichloroethylene

Previously, we had cross-sectionally explored the characteristics of T cell receptor (TCR) repertoires from occupational medicamentosa-like dermatitis due to trichloroethylene (OMDT) patients, now we further analyzed the dynamic features of OMDT TCR repertoires. Peripheral blood TCR β-chain complementarity-determining region 3 (CDR3) genes were detected with the high throughput sequencing in 24 OMDT cases in their acute, chronic and recovery stages, respectively, and in 24 trichloroethylene-exposed healthy controls. The TCR repertoire diversity, TRBV/TRBD/TRBJ gene usage and combination, frequencies of CDR3 nucleotide (nt) and amino acid (aa) sequences in the cases in different stages and in the controls were analyzed. TRBV6-4 and TRBV7-9 frequencies significantly differed between the cases and controls (both P < 6.1 × 10-4). TRBV6-4 combination with TRBJ2-1, TRBJ2-2, TRBJ2-3, and TRBJ2-6, and TRBV7-9 combination with TRBJ2-1 were associated with the stage by OMDT severity (all P < 0.001). Ten CDR3-nt and 7 CDR3-aa sequences in TRBV7-9-TRBJ2-1 combination and 1 CDR3-nt and 1 CDR3-aa sequences in TRBV6-4-TRBJ2-1 combination were identified as associated with the severity of OMDT (all P < 0.001). We revealed further how TCR repertoires vary with the severity in the development of OMDT, and severity-related TCRs may provide important therapeutic targets for OMDT in clinical practice.

High S100A2 expression in keratinocytes in patients with drug eruption

Telaprevir used as a protease inhibitor against hepatitis C virus is frequently associated with cutaneous adverse reactions. To explore a histological biomarker of cutaneous adverse events induced by telaprevir, we systematically searched for genes that were dysregulated by telaprevir in normal human epidermal keratinocytes (NHEKs). Microarray analysis and real-time polymerase chain reaction (PCR) revealed the significant increase in the expression of S100 calcium-binding protein A2 (S100A2) gene following treatment of NHEKs with telaprevir. Immunohistochemical analysis demonstrated that the expression of S100A2 was dominant in the spinous layer of the epidermis in patients with telaprevir-mediated severe-type drug eruptions and limited to the basal layer of the epidermis in healthy subjects. Furthermore, S100A2 expression increased after treatment with trichloroethylene and other medications, and the degree of S100A2 expression correlated with the severity of cutaneous adverse events. S100A2 expression also significantly increased in the skin of patients with atopic dermatitis and psoriasis. Taken together, S100A2 is highly expressed in the epidermis under inflammatory conditions and drug eruptions and may serve as a marker for keratinocyte damage in response to any inflammatory or toxic condition.

Increased risk of occupational trichloroethylene hypersensitivity syndrome at exposure levels higher than 15 mg/L of urinary trichloroacetic acid, regardless of whether the patients had the HLA-B*13:01 allele

Occupational trichloroethylene (TCE) exposure can cause hypersensitivity syndrome (TCE-HS). The human leukocyte antigen (HLA)-B*13:01 is reportedly an important allele involved in TCE-HS onset. However, the threshold exposure level causing TCE-HS in relation to HLA-B*13:01 remains unknown. We conducted a case-control study comprising 37 TCE-HS patients and 97 age- and sex-matched TCE-tolerant controls from the Han Chinese population. Urine and blood of patients were collected on the first day of hospitalization, and those of controls were collected at the end of their shifts. Urinary trichloroacetic acid (TCA) was measured as an exposure marker, and end-of-shift levels in the patients were estimated using the biological half-life of 83.7 h. HLA-B genotype was identified using DNA from blood. Crude odds ratios (ORs) for TCE-HS in the groups with urinary TCA concentration >15 mg/L to ≤50 mg/L and of >50 mg/L were 21.9 [95% confidence interval (CI) 4.2-114.1] and 27.6 (6.1-125.8), respectively, when the group with urinary TCA ≤15 mg/L was used as a reference. The frequency of HLA-B*13:01, the most common allele in the patients, was 62.2% (23/37), which was significantly higher than 17.5% (17/97) in the TCE-tolerant controls, with a crude OR of 8.4 (3.1-22.6). The mutually-adjusted ORs for urinary TCA >15 to ≤50 mg/L, >50 mg/L, and for HLA-B*13:01 were 33.4 (4.1-270.8), 34.0 (5.3-217.1), and 11.0 (2.4-50.7), respectively. In conclusion, reduction of TCE exposure to ≤15 mg/L is required for TCE-HS prevention because urinary TCA concentration >15 mg/L showed increased risk of TCE-HS, regardless of whether the patients had the HLA-B*13:01 allele.

Intracellular complement activation in podocytes aggravates immune kidney injury in trichloroethylene-sensitized mice

Trichloroethylene (TCE) as a common organic solvent in industrial production can cause occupational medicamentosa-like dermatitis (OMDT) in some exposed workers. In addition to systemic skin damage, OMDT is also accompanied by severe kidney injury. Our previous studies show that complement (C) plays an important role in immune kidney injury caused by TCE. Specifically, C3 is mainly deposited on glomeruli. Recent studies have found that intracellular complement can be activated by cathepsin L (CTSL) and exert a series of biological effects. The purpose of this study was to explore where C3 on glomeruli comes from and what role it plays. A BALB/c mouse model of skin sensitization induced by TCE in the presence or absence of CTSL inhibitor (CTSLi,10 mg/kg). In TCE sensitization-positive mice, C3 was mainly expressed on podocytes and the expression of CTSL significantly increased in podocytes. Kidney function test and related indicators showed abnormal glomerular filtration and transmission electron microscopy revealed ultrastructure damage to podocytes. These lesions were alleviated in TCE/CTSLi positive mice. These results provide the first evidence that in TCE-induced immune kidney injury, intracellular complement in podocytes can be over-activated by CTSL and aggravates podocytes injury, thereby damaging glomerular filtration function. Intracellular complement activation and cathepsin L in podocytes may be a potential target for treating immune kidney injury induced by TCE.

Sex-Dependent Effects on Liver Inflammation and Gut Microbial Dysbiosis After Continuous Developmental Exposure to Trichloroethylene in Autoimmune-Prone Mice

Trichloroethylene (TCE) is a common environmental toxicant linked with hypersensitivity and autoimmune responses in humans and animal models. While autoimmune diseases are more common in females, mechanisms behind this disparity are not clear. Recent evidence suggests that autoimmunity may be increasing in males, and occupational studies have shown that TCE-mediated hypersensitivity responses occur just as often in males. Previous experimental studies in autoimmune-prone MRL^+/+ mice have focused on responses in females. However, it is important to include both males and females in order to better understand sex-disparity in autoimmune disease. In addition, because of an alarming increase in autoimmunity in adolescents, developmental and/or early life exposures to immune-enhancing environmental pollutants should also be considered. Using MRL^+/+ mice, we hypothesized that TCE would alter markers related to autoimmunity to a greater degree in female mice relative to male mice, and that TCE would enhance these effects. Mice were continuously exposed to either TCE or vehicle beginning at gestation, continuing during lactation, and directly in the drinking water. Both male and female offspring were evaluated at 7 weeks of age. Sex-specific effects were evident. Female mice were more likely than males to show enhanced CD4⁺ T cell cytokine responses (e.g., IL-4 and IFN-γ). Although none of the animals developed pathological or serological signs of autoimmune hepatitis-like disease, TCE-exposed female mice were more likely than males in either group to express higher levels of biomarkers in the liver related to regeneration/repair and proliferation. Levels of bacterial populations in the intestinal ileum were also altered by TCE exposure and were more prominent in females as compared to males. Thus, our expectations were correct in that young adult female mice developmentally exposed to TCE were more likely to exhibit alterations in immunological and gut/liver endpoints compared to male mice.

Utility evaluation of HLA-B*13:01 screening in preventing trichloroethylene-induced hypersensitivity syndrome in a prospective cohort study

OBJECTIVES

Trichloroethylene (TCE) -induced hypersensitivity syndrome (TIHS) is a potentially life-threatening disease. Several genetic susceptibility biomarkers have been found to be associated with TIHS, and this systematic prospective study has been conducted to evaluate the utility of these genetic susceptibility biomarkers in preventing the disease.

METHODS

The newly hired TCE-exposed workers were recruited from March 2009 to October 2010. HLA-B*13:01 genotyping and 3-month follow-up procedure were conducted. All workers were monitored for adverse reaction by telephone interview every week. The workers with early symptoms of TIHS were asked to go to the hospital immediately for further examination, diagnosis and treatment. The medical expense record data of patients with TIHS were collected for cost-effectiveness analysis in 2018.

RESULTS

Among 1651 workers, 158 (9.57%) were found to carry the HLA-B*13:01 allele and 16 (0.97%) were diagnosed with TIHS. HLA-B*13:01 allele was significantly associated with an increased TIHS risk (relative risk=28.4, 95% CI 9.2 to 86.8). As a risk predictor of TIHS, HLA-B*13:01 testing had a sensitivity of 75%, a specificity of 91.1% and an area under curve of 0.83 (95% CI 0.705 to 0.955), the positive and negative predictive values were 7.6% and 99.7%, respectively. The incidence of TIHS was significantly decreased in HLA-B*13:01 non-carriers (0.27%) compared with all workers (0.97%, p=0.014). Cost-effectiveness analysis showed that HLA-B*13:01 screening could produce an economic saving of $4604 per TIHS avoided.

CONCLUSIONS

Prospective HLA-B*13:01 screening may significantly reduce the incidence of TIHS and could be a cost effective option for preventing the disease in TCE-exposed workers.

Inflammatory kidney injury in trichloroethylene hypersensitivity syndrome mice: Possible role of C3a receptor in the accumulation of Th17 phenotype

Trichloroethylene (TCE) is a common organic solvent which can cause TCE hypersensitivity syndrome (THS) in exposure workers. THS is an adverse skin disorder with severe inflammatory kidney damage. Complement C3a receptor (C3aR) acts as a specific receptor for the key complement cleavage product C3a and involves multiple inflammatory responses, but the role of C3aR in TCE induced kidney inflammatory injury remains unknown. In this study, BALB/c mouse model of skin sensitization induced by TCE was set up in the presence or absence of C3aR antagonist (C3aRA). Kidney pathology and renal function, expression of inflammatory mediators and C3aR, changes in Th17 cell numbers, and activation of signal transducer and activator of transcription 3 (STAT3) in the kidney were examined. TCE sensitization produced histopathological and functional damage to the kidney, accompanied by increased levels of interleukin (IL-) 1β, IL-6, and IL-23. Local accumulation of Th17 cells and enhanced phosphorylation of STAT3 were also seen in the impaired kidney in TCE sensitization-positive mice. C3aR was mainly located in the impaired glomerulus and upregulated in TCE sensitization-positive mice. C3aRA pretreatment alleviated the structural and functional kidney damage and the inflammatory cytokine and Th17 responses by TCE sensitization, and specifically reduced the phosphorylation of STAT3. Together, our results demonstrate that C3aR signaling promotes the inflammatory responses and regulates the accumulation of Th17 phenotype via phosphorylation of STAT3 in TCE sensitization induced inflammatory kidney damage. C3aR may serve as a potential therapeutic target in TCE sensitization mediated kidney injury.

EASL Clinical Practice Guideline: Occupational liver diseases

A variety of chemicals have been linked to occupational liver diseases, including several solvents and mixtures thereof, pesticides, and metals. Workplace exposures have been associated with virtually the entire spectrum of acute and chronic liver diseases. However, their prevalence is inadequately quantified and their epidemiology limited. Occupational liver diseases may result from high accidental or from prolonged lower level exposures. Whereas the former is uncommon and easily recognised, the latter are relatively more frequent but often overlooked because they may display normal values of conventional markers, have an insidious onset and be asymptomatic or be obfuscated and confounded by concurrent conditions. In addition, specific tests of toxicity are not available, histopathology may not be revealing and the assessment of internal dose of chemicals is usually not decisive. Given these circumstances, the diagnosis of these liver disorders is challenging, one of exclusion and often requires an interdisciplinary approach. These recommendations offer a classification of the type of liver injuries associated with occupational exposures - based in part on the criteria for drug-induced liver injury - a grading of their severity, and the diagnostic and preventive criteria for chemically induced occupational liver disease.

A pilot study to assess peripheral blood TCR β-chain CDR3 repertoire in occupational medicamentosa-like dermatitis due to trichloroethylene using high-throughput sequencing

We exploratively characterized T cell receptor (TCR) repertoires from occupational medicamentosa-like dermatitis due to trichloroethylene (OMDT) patients to better understand the underlying pathological mechanism. We used a combination of multiplex-PCR, Illumina sequencing and IMGT/High V-QUEST to analyze the characteristics and polymorphisms of the TCR β-chain complementarity-determining region 3 (CDR3) gene in 10 OMDT cases and 10 trichloroethylene-exposed healthy tolerant controls. Compared with the tolerant controls, OMDT cases showed no significant difference in TCR repertoire diversity including repertoire breadth, highly expanded clone, and CDR3 length distribution. However, we observed several differences in TRBV/TRBJ usage and combination between the two groups, as well as some shared and unique T cell clones in the cases. The pilot study delineated some features of TCR repertoire in OMDT patients that warrant further investigation.

Complement regulatory protein CD59a plays a protective role in immune liver injury of trichloroethylene-sensitized BALB/c mice

Trichloroethylene (TCE) is a major occupational and environmental chemical compound which causes occupational dermatitis medicamentosa-like of TCE with severe liver damage. Our previous studies showed that complement activation was a newly recognized mechanism for TCE-induced liver damage. The objective of this study was to explore the role of the key complement regulatory protein, CD59a, in TCE-induced immune liver injury. We firstly evaluated the changes of CD59a expression in liver tissue and then investigated if the changes were associated with membrane attack complex (MAC) formation, nuclear factor kappa B (NF-κB) activation and liver damage in BALB/c mice model of TCE-induced skin sensitization in the absence or presence of soluble recombinant rat CD59-Cys. The results showed that low expression of CD59a accompanied by MAC deposition in the liver of TCE-sensitized BALB/c mice, which was consistent in time. In addition, activation of NF-κB pathway, upregulation of inflammatory cytokine and liver damage also occured. Additional experiment showed that recombinant rat sCD59-Cys alleviated inflammation and liver damage in TCE-sensitized BALB/c mice. Moreover, recombinant rat sCD59-Cys reduced MAC formation and inhibited NF-κB activation measured by P-IκBα and nuclear NF-κB p65 in the liver of TCE-sensitized BALB/c mice. In conclusion, recombinant rat sCD59-Cys plays a protective role in immune liver injury of TCE-sensitized BALB/c mice.

Joint association of carrying HLA-B*13:01 gene and human herpesvirus-6 with occupational trichloroethylene hypersensitivity syndrome

PURPOSE

Occupational trichloroethylene hypersensitivity syndrome (OTHS) clinically manifests as generalized severe rash resembling drug-induced hypersensitivity syndrome (DIHS) and afflicts predominantly HLA-B*13:01 gene carriers after their exposure to trichloroethylene. Meanwhile, OTHS may also be associated with human herpesvirus such as herpesvirus-6 (HHV6) and cytomegalovirus (HCMV) reported to participate in the pathology of DIHS. This study explored the association of carrying HHV6 and HCMV, and the joint association of carrying HLA-B*13:01 and HHV6 and HCMV with OTHS.

METHODS

We recruited 30 OTHS patients and 40 trichloroethylene-exposed healthy workers as cases and controls, respectively. HLA-B*13:01 was genotyped and HHV6 and HCMV DNA were detected in the DNA extracted from whole-blood sample of each participant with PCR techniques. Positive rates of HLA-B*13:01 gene and HHV6 and HCMV DNA and their association with OTHS were then analyzed.

RESULTS

The OTHS cases showed significantly higher positive rates of HLA-B*13:01 gene and HHV6 DNA, but not HCMV DNA, than the controls (83.3% vs. 25.0% and 56.7% vs. 10.0%, respectively, both P < 0.001). Positive rate of HHV6 DNA was significantly higher in HLA-B*13:01 carriers than in non-carriers in the cases (68.0% vs. 0, P = 0.005), but not in the controls. Carrying HLA-B*13:01 and HHV6 had an interactive effect on OTHS (OR = 91.80, P < 0.001).

CONCLUSIONS

Carrying HLA-B*13:01 and HHV6 may be associated with OTHS; furthermore, carrying HLA-B*13:01 and HHV6 may be jointly associated with OTHS.

Exposure reconstruction of trichloroethylene among patients with occupational trichloroethylene hypersensitivity syndrome

Occupational trichloroethylene (TCE) exposure can induce life-threatening generalized dermatitis accompanied by hepatitis: TCE hypersensitivity syndrome (HS). Since the patients' exposure levels have not been fully clarified, this study estimated end-of-shift urinary concentrations of trichloroacetic acid (TCA) and their lower limit below which the disease occurrence was rare. TCA concentration was measured in 78 TCE HS patients whose urine was collected at admission between 2nd and 14th d after their last shift. Then a linear regression model was used to calculate the mean TCA concentration with 95% confidence interval (95% CI) and 95% prediction interval (95% PI) in the end-of-shift urine. The estimated mean concentration was 83 (95% CI, 49-140) mg/l with 95% PI 9.6-720 mg/l. TCA concentrations were also measured in the end-of-shift urine of 38 healthy workers involved in the same job as were the patients. The geometric mean and its 95% CI were 127 mg/l and 16-984 mg/l, respectively. The exposure levels in HS patients might have thus overlapped with those in workers without HS. Accordingly, it was suggested that HS occurred in the environment where the workers were exposed to the TCE concentration corresponding to the urinary TCA concentration as low as 10 mg/l.

Viral mimic polyinosine-polycytidylic acid potentiates liver injury in trichloroethylene-sensitized mice - Viral-chemical interaction as a novel mechanism

Occupational trichloroethylene (TCE) exposure can induce hypersensitivity dermatitis and severe liver injury. Recently, several clinical investigations indicate that viral infection, such as human herpesvirus-6, is associated with hepatic dysfunction in patients with TCE-related generalized skin disorders. However, whether viral infection potentiates TCE-induced liver injury remains unknown. This study aimed to explore the contribution of viral infection to the development of TCE-sensitization-induced liver injury in BALB/c mice. Female BALB/c mice were randomly assigned into four groups: solvent control group (n = 20), TCE group (n = 80), poly(I:C) group (n = 20) and combination of TCE and poly(I:C) (poly(I:C)+TCE) group (n = 80). Poly(I:C) (50 μg) was i.p. administrated. TCE and poly(I:C)+TCE groups were further divided into sensitization and non-sensitization subgroup. Complement 3 and C3a protein levels, and complement factors were measured. Combination treatment significantly enhanced TCE-induced liver injury, decreased complement 3, but increased C3a in serum and liver tissues in sensitization group. These changes were not correlated with the hepatic complement 3 transcription. Moreover, combination treatment specifically promoted complement factor B, but not factor D and factor H expressions. These data provide first evidence that poly(I:C) potentiates liver injury in BALB/c mouse model of TCE-sensitization. Upregulated C3a and factor B contributes to the poly(I:C) action in TCE-induced liver injury. This new mode of action may explain increased risk of chemical-sensitization induced tissue damage by viral infection.

Trichloroethylene Hypersensitivity Syndrome: Should Be Considered When Diagnosing DRESS Syndrome

Trichloroethylene (TCE) is an organic solvent that is used for degreasing and removing impurities from metal parts. However, this solvent's characteristics and hypersensitivity can produce clinical patterns and laboratory data that mimic drug rash with eosinophilia and systemic symptoms (DRESS) syndrome. Thus, exposure confirmation is critical to making an accurate diagnosis. This is a case of TCE-induced hypersensitivity syndrome (TCE HS) in a 24-year-old Indonesian man who was working in an electro-plating business. He was admitted to a referral hospital after one month of working, and exhibited a fever with skin symptoms. He was administered immunosuppressive therapy based on an assumed diagnosis of DRESS syndrome, although he subsequently experienced cardiac arrest and did not respond to resuscitation. An investigation into his disease history confirmed that he was prescribed medications one week before he developed the skin disease, and had been periodically exposed to TCE for the previous 4 weeks. Based on these findings, it was believed that his clinical course was caused by TCE HS, rather than DRESS syndrome.

Toxicological effects of trichloroethylene exposure on immune disorders

Trichloroethylene (TCE) is one of the most common ground water contaminants in USA. Even though recent regulation mandates restricted utilization of TCE, its use is not completely prohibited, especially in industrial and manufacturing processes. The risk of TCE on human health is an ongoing field of study and its implications on certain diseases such as cancer has been recognized and well-documented. However, the link between TCE and immune disorders is still an under-studied area. Studies on the risk of TCE on the immune system is usually focused on certain immune class disorders, but consensus on the impact of TCE on the immune system has not been established. This review presents representative work that investigates the effect of TCE on immune disorders and highlights future opportunities. We attempt to provide a broader perspective of the risks of TCE on the immune system and human health.

Target Organ Metabolism, Toxicity, and Mechanisms of Trichloroethylene and Perchloroethylene: Key Similarities, Differences, and Data Gaps

Trichloroethylene (TCE) and perchloroethylene or tetrachloroethylene (PCE) are high-production volume chemicals with numerous industrial applications. As a consequence of their widespread use, these chemicals are ubiquitous environmental contaminants to which the general population is commonly exposed. It is widely assumed that TCE and PCE are toxicologically similar; both are simple olefins with three (TCE) or four (PCE) chlorines. Nonetheless, despite decades of research on the adverse health effects of TCE or PCE, few studies have directly compared these two toxicants. Although the metabolic pathways are qualitatively similar, quantitative differences in the flux and yield of metabolites exist. Recent human health assessments have uncovered some overlap in target organs that are affected by exposure to TCE or PCE, and divergent species- and sex-specificity with regard to cancer and noncancer hazards. The objective of this minireview is to highlight key similarities, differences, and data gaps in target organ metabolism and mechanism of toxicity. The main anticipated outcome of this review is to encourage research to 1) directly compare the responses to TCE and PCE using more sensitive biochemical techniques and robust statistical comparisons; 2) more closely examine interindividual variability in the relationship between toxicokinetics and toxicodynamics for TCE and PCE; 3) elucidate the effect of coexposure to these two toxicants; and 4) explore new mechanisms for target organ toxicity associated with TCE and/or PCE exposure.

Follow-up assessment of two cases of trichloroethylene hypersensitivity syndrome: A case report

The present study aimed to explore the stability, curability and sequelae of cases of Trichloroethylene (TCE) Hypersensitivity Syndrome (THS), and to investigate the causal allergens of THS. Two cases of THS were followed-up in the current study; both cases were healing following glucocorticoid therapy and were discharged >10 weeks prior to follow-up. A questionnaire investigation, health examination and patch test were performed. Allergens of TCE and its metabolites, including chloral hydrate, trichloroethanol (TCOH) and trichloroacetic acid, were applied in the patch test; 4 controls were included. The two subjects were experiencing itching, pigmentation and xerosis of the skin, and had abnormal results in the ophthalmology Schirmer I test and tear break-up time. The body temperature, liver function, superficial lymph nodes, blood, urine routine and autoimmune antibodies of two subjects were shown to be normal, and no new rashes had appeared. All mass concentration of chloral hydrate and TCOH were positive; 5.0% trichloroacetic acid was weakly positive, 0.5% trichloroacetic acid and all mass concentration of TCE were negative. All patch tests were negative in the 4 control subjects. The results suggest that THS was stable following treatment with glucocorticoid therapy. Dry eye syndrome may continue as a sequelae of THS. The patch test demonstrated that the mechanism underlying THS is delayed-type hypersensitivity induced by TCE. In addition, as the hypersensitivity state in a THS rehabilitee could be sustained over a long period of time, it suggests that the metabolites of TCE, not TCE itself, are responsible for THS. Therefore, patients with THS should avoid contact with TCE and its metabolites, and avoid using hypnotic and anticonvulsive drugs containing chloral hydra as the primary ingredient.

Trichloroethylene-induced hypersensitivity dermatitis was associated with hepatic metabolic enzyme genes and immune-related genes

Trichloroethylene (TCE) is one of the common organic solvents that has been widely used in cleaning or degreasing of metal and electronic products. However, hundreds of cases of hypersensitivity dermatitis have occurred after the workers were occupationally exposed to TCE in China over the past decade. The purpose of this study was to investigate mRNA expression of hepatic metabolic enzyme genes, immune-related genes, apoptosis genes and oncogenes in patients with hypersensitivity dermatitis induced by trichloroethylene. 12 typical patients with TCE-induced hypersensitivity dermatitis were investigated as the study cases, peripheral blood samples were taken from patients and control, and real-time fluorescence PCR assay was applied for detection of mRNA expression of hepatic metabolic enzyme genes, immune-related genes, apoptosis genes and oncogenes. It was found that the relative levels of mRNA expression of CYP1A2, CYP2E1, CYP3A4 and CYP2C9 increased by 723%, 318%, 385% and 216%, respectively, when compared with control (p < 0.01 or p < 0.05); Foxp3, GATA3 and CTLA4 mRNA expression increased by 104%, 106% and 253%, respectively, in TCE patients when compared with control (p < 0.01); T-bet expression decreased by 44% when compared with control (p < 0.01); these findings indicate that some immune-related genes and hepatic metabolic enzyme genes might play an important role in the process of trichloroethylene-induced hypersensitivity dermatitis.

Trichloroethylene and Its Oxidative Metabolites Enhance the Activated State and Th1 Cytokine Gene Expression in Jurkat Cells

Trichloroethylene (TCE) is an occupational and ubiquitous environmental contaminant, and TCE exposure will increase the risk of autoimmune diseases and allergic diseases. T cells play an important role in the pathogenesis of TCE-related immune disorders, but the effect of TCE and its oxidative metabolites, trichloroacetic acid (TCA) and dichloroacetic acid (DCA), on the activation of human T cells is still unknown. In this study, Jurkat cells were pre-treated with TCE, TCA and DCA overnight and then stimulated with phorbol 12-myristate 13-acetate and ionomycin for another 4, 8 and 24 hours. IL-2 secretion was detected by ELISA; the expressions of CD25 and CD69 were tested by flow cytometry; and IFN-γ and IL-2 mRNA expression levels were investigated by real-time PCR. The results showed that TCE and its oxidative metabolites, TCA and DCA, significantly enhanced IL-2 releasing and the expression of T cell activation markers, CD25 and CD69. Consistent with this result, these compounds markedly up-regulated the expression levels of IFN-γ and IL-2 mRNA. Collectively, these findings suggest that TCE and its metabolites, TCA and DCA, might enhance the activation of T cells and disrupt various activities of peripheral T cells.

Performance of genetic risk factors in prediction of trichloroethylene induced hypersensitivity syndrome

Trichloroethylene induced hypersensitivity syndrome is dose-independent and potentially life threatening disease, which has become one of the serious occupational health issues and requires intensive treatment. To discover the genetic risk factors and evaluate the performance of risk prediction model for the disease, we conducted genomewide association study and replication study with total of 174 cases and 1761 trichloroethylene-tolerant controls. Fifty seven SNPs that exceeded the threshold for genome-wide significance (P < 5 × 10(-8)) were screened to relate with the disease, among which two independent SNPs were identified, that is rs2857281 at MICA (odds ratio, 11.92; P meta = 1.33 × 10(-37)) and rs2523557 between HLA-B and MICA (odds ratio, 7.33; P meta = 8.79 × 10(-35)). The genetic risk score with these two SNPs explains at least 20.9% of the disease variance and up to 32.5-fold variation in inter-individual risk. Combining of two SNPs as predictors for the disease would have accuracy of 80.73%, the area under receiver operator characteristic curves (AUC) scores was 0.82 with sensitivity of 74% and specificity of 85%, which was considered to have excellent discrimination for the disease, and could be considered for translational application for screening employees before exposure.

Trichloroethylene Hypersensitivity Syndrome Is Potentially Mediated through Its Metabolite Chloral Hydrate

Background

We documented previously the entity of trichloroethylene (TCE) hypersensitivity syndrome (THS) in occupational workers.

Objectives

To identify the culprit causative compound, determine the type of hypersensitivity of THS, and establish a screening test for subjects at risk of THS.

Methods

TCE and its main metabolites chloral hydrate (CH), trichloroethanol (TCOH) and trichloroacetic acid (TCA) were used as allergens at different concentrations in skin patch tests. The study included 19 case subjects diagnosed with occupational THS, 22 control healthy workers exposed to TCE (exposure >12 weeks), and 20 validation new workers exposed to TCE for <12 weeks free of THS. All subjects were followed-up for 12 weeks after the patch test.

Results

The highest patch test positive rate in subjects with THS was for CH, followed by TCOH, TCA and TCE. The CH patch test positive rate was 100% irrespective of CH concentrations (15%, 10% and 5%). The TCOH patch test positive rate was concentration-dependent (89.5%, 73.7% and 52.6% for 5%, 0.5% and 0.05%, respectively). Lower patch test positive rates were noted for TCA and TCE. All patch tests (including four allergens) were all negative in each of the 22 control subjects. None of the subjects of the validation group had a positive 15% CH patch test.

Conclusions

Chloral hydrate seems to be the culprit causative compound of THS and type IV seems to be the major type of hypersensitivity of THS. The CH patch test could be potentially useful for screening workers at risk of THS.

Occupational health risks among trichloroethylene-exposed workers in a clock manufacturing factory

Trichloroethylene (TCE) is an important volatile organic compound once widely used in industry throughout the world. Occupational exposure to TCE can cause a number of health hazards such as allergic reactions and genetic damage. The purpose of this study was to evaluate occupational exposure to TCE, by analysis of the air in the breathing zone and of urine from workers employed in a clock manufacturing factory. A subjective symptom survey was conducted by using a self-administered questionnaire to evaluate the health hazards. Micronucleus (MN) frequency, based on the cytokinesis-block micronucleus assay (CBMN) in peripheral blood lymphocytes, (PBLs) was used as a biomarker for chromosome damage. A total of 244 participants, including 171 workers occupationally exposed to TCE and 73 non-exposed control employees, working mainly in office jobs in the same factory, were enrolled in this study. Analyses of airborne TCE concentrations in the workplace, and of urinary trichloroacetic acid (TCA) of the workers and controls, were performed by Gas Chromatography-Electron Capture Detector (GC-ECD) using the modified headspace technique. The average concentration of TCE in the workplace breathing zone was 27.83 ± 6.02 ppm. The average level of urinary TCA of the exposed workers and controls was 14.84 ± 1.62, 2.95 ± 0.28 mg/L. The frequency of MN/1000BN was 7.029 ± 0.39, significantly higher than for those in the control group (3.57 ± 0.31, p = 0.001). According to multiple linear regression analysis, the results indicated that urinary TCA levels correlated with the increased MN in exposed workers (r = 0.285, p < 0.001). The prevalence rate of subjective symptoms in the exposed group was 9.61-11.76 times higher than the rate of the non-exposed group (p < 0.001). It was found that skin (29.6%) and respiratory symptoms (21.1%) were the most frequent among the exposed workers.

In conclusion, these results indicate that increased micronucleus frequency is associated with occupational trichloroethylene exposure. The use of TCE in the factory is threatening workers’ health.

A case of occupational hypersensitivity pneumonitis associated with trichloroethylene

Trichloroethylene (TCE) is a toxic chemical commonly used as a degreasing agent, and it is usually found in a colorless or blue liquid form. TCE has a sweet, chloroform-like odor, and this volatile chlorinated organic chemical can cause toxic hepatitis, neurophysiological disorders, skin disorders, and hypersensitivity syndromes. However, the hypersensitivity pneumonitis (HP) attributed to TCE has rarely been reported. We hereby describe a case of HP associated with TCE in a 29-year-old man who was employed as a lead welder at a computer repair center. He was installing the capacitors on computer chip boards and had been wiped down with TCE. He was admitted to our hospital with complaints of dry coughs, night sweats, and weight losses for the past two months. HP due to TCE exposure was being suspected due to his occupational history, and the results of a video-associated thoracoscopic biopsy confirmed the suspicions. Symptoms have resolved after the steroid pulse therapy and his occupational change. TCE should be taken into consideration as a potential trigger of HP. Early recognition and avoidance of the TCE exposure in the future is important for the treatment of TCE induced HP.

Complement Activation and Liver Impairment in Trichloroethylene-Sensitized BALB/c Mice

Our recent studies have shown that trichloroethylene (TCE) was able to induce multisystem injuries in the form of occupational medicamentosa-like dermatitis, including skin, kidney, and liver damages. However, the role of complement activation in the immune-mediated liver injury is not known. This study examined the role of complement activation in the liver injury in a mouse model of TCE-induced sensitization. Treatment of female BALB/c mice with TCE under specific dosing protocols resulted in skin inflammation and sensitization. Skin edema and erythema occurred in TCE-sensitized groups. Trichloroethylene sensitization produced liver histopathological lesions, increased serum alanine aminotransferase, aspartate transaminase activities, and the relative liver weight. The concentrations of serum complement components C3a-desArg, C5a-desArg, and C5b-9 were significantly increased in 24-hour, 48-hour, and 72-hour sensitization-positive groups treated with TCE and peaked in the 72-hour sensitization-positive group. Depositions of C3a, C5a, and C5b-9 into the liver tissue were also revealed by immunohistochemistry. Immunofluorescence further verified high C5b-9 expression in 24-hour, 48-hour, and 72-hour sensitization-positive groups in response to TCE treatment. Reverse transcription–polymerase chain reaction detected C3 messenger RNA expression in the liver, and this was significantly increased in 24-hour and 48-hour sensitization-positive groups with a transient reduction at 72 hours. These results provide the first experimental evidence that complement activation may play a key role in the generation and progression of immune-mediated hepatic injury by exposure to TCE.

Sex differences in metabolism of trichloroethylene and trichloroethanol in guinea pigs

OBJECTIVES

Trichloroethylene (TRI) has the potential to cause generalized dermatitis complicated with hepatitis. The guinea pig maximization test (GPMT) also suggests that both TRI and its metabolite trichloroethanol (TCE) exhibit immunogenicity and possible sex differences in guinea pigs. However, TRI and TCE metabolisms in guinea pigs have not been elucidated in detail. The first issue to clarify may be the sex differences in relation to the immunogenicity.

METHODS

We collected urine from Hartley male and female guinea pigs 24 hours after intracutaneous injection of TRI, TCE or trichloroacetic acid (TCA) during a GPMT and measured the urinary metabolites by gas chromatography-mass spectrometry.

RESULTS

After TRI treatment, the amount of TCA was significantly greater in females than males, while there was no sex difference in the total amount (TCA + TCE). TCA was only detected in urine after TCA treatment. Interestingly, not only TCE but also TCA was detected in urine of both sexes after TCE treatment, and the amount of TCA was also greater in females than males. An additional experiment showed that TCE treatment did not result in the detection of urinary TCA in cytochrome P450 (CYP)2E1-null mice TCEbut did in wild-type mice, suggesting the involvement of CYP2E1 in the metabolism from TCE to TCA. The constitutive expression of CYP2E1 in the liver of guinea pigs was greater in females than males.

CONCLUSIONS

The sex difference in urinary TCA excretion after TRI and TCE treatments may be due to variation of the constitutive expression of CYP2E1.

Identification of serum biomarkers for occupational medicamentosa-like dermatitis induced by trichloroethylene using mass spectrometry

Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is an autoimmune disease and it has become a serious occupational health hazard. In the present study, we collected fasting blood samples from patients with OMLDT (n=18) and healthy volunteers (n=33) to explore serum peptidome patterns. Peptides in sera were purified using weak cation exchange magnetic beads (MB-WCX), and analyzed by matrix-assisted laser desorption ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) and ClinProTools bioinformatics software. The intensities of thirty protein/peptide peaks were significantly different between the healthy control and OMLDT patients. A pattern of three peaks (m/z 2106.3, 2134.5, and 3263.67) was selected for supervised neural network (SNN) model building to separate the OMLDT patients from the healthy controls with a sensitivity of 95.5% and a specificity of 73.8%. Furthermore, two peptide peaks of m/z 4091.61 and 4281.69 were identified as fragments of ATP-binding cassette transporter family A member 12 (ABCA12), and cationic trypsinogen (PRRS1), respectively. Our findings not only show that specific proteomic fingerprints in the sera of OMLDT patients can be served as a differentiated tool of OMLDT patients with high sensitivity and high specificity, but also reveal the novel correlation between OMLDT with ABC transports and PRRS1, which will be of potential value for clinical and mechanistic studies of OMLDT.

Trichloroethylene: Mechanistic, epidemiologic and other supporting evidence of carcinogenic hazard

The chlorinated solvent trichloroethylene (TCE) is a ubiquitous environmental pollutant. The carcinogenic hazard of TCE was the subject of a 2012 evaluation by a Working Group of the International Agency for Research on Cancer (IARC). Information on exposures, relevant data from epidemiologic studies, bioassays in experimental animals, and toxicity and mechanism of action studies was used to conclude that TCE is carcinogenic to humans (Group 1). This article summarizes the key evidence forming the scientific bases for the IARC classification. Exposure to TCE from environmental sources (including hazardous waste sites and contaminated water) is common throughout the world. While workplace use of TCE has been declining, occupational exposures remain of concern, especially in developing countries. The strongest human evidence is from studies of occupational TCE exposure and kidney cancer. Positive, although less consistent, associations were reported for liver cancer and non-Hodgkin lymphoma. TCE is carcinogenic at multiple sites in multiple species and strains of experimental animals. The mechanistic evidence includes extensive data on the toxicokinetics and genotoxicity of TCE and its metabolites. Together, available evidence provided a cohesive database supporting the human cancer hazard of TCE, particularly in the kidney. For other target sites of carcinogenicity, mechanistic and other data were found to be more limited. Important sources of susceptibility to TCE toxicity and carcinogenicity were also reviewed by the Working Group. In all, consideration of the multiple evidence streams presented herein informed the IARC conclusions regarding the carcinogenicity of TCE.

Human health effects of trichloroethylene: key findings and scientific issues

BACKGROUND

In support of the Integrated Risk Information System (IRIS), the U.S. Environmental Protection Agency (EPA) completed a toxicological review of trichloroethylene (TCE) in September 2011, which was the result of an effort spanning > 20 years.

OBJECTIVES

We summarized the key findings and scientific issues regarding the human health effects of TCE in the U.S. EPA's toxicological review.

METHODS

In this assessment we synthesized and characterized thousands of epidemiologic, experimental animal, and mechanistic studies, and addressed several key scientific issues through modeling of TCE toxicokinetics, meta-analyses of epidemiologic studies, and analyses of mechanistic data.

DISCUSSION

Toxicokinetic modeling aided in characterizing the toxicological role of the complex metabolism and multiple metabolites of TCE. Meta-analyses of the epidemiologic data strongly supported the conclusions that TCE causes kidney cancer in humans and that TCE may also cause liver cancer and non-Hodgkin lymphoma. Mechanistic analyses support a key role for mutagenicity in TCE-induced kidney carcinogenicity. Recent evidence from studies in both humans and experimental animals point to the involvement of TCE exposure in autoimmune disease and hypersensitivity. Recent avian and in vitro mechanistic studies provided biological plausibility that TCE plays a role in developmental cardiac toxicity, the subject of substantial debate due to mixed results from epidemiologic and rodent studies.

CONCLUSIONS

TCE is carcinogenic to humans by all routes of exposure and poses a potential human health hazard for noncancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing embryo/fetus.

Altered expression of hepatic metabolic enzyme and apoptosis-related gene transcripts in human hepatocytes treated with trichloroethylene

Trichloroethylene (TCE) is a common organic solvent that has been widely used in industrial applications. Hundred cases of allergic reactions occurred after the workers were occupationally exposed to TCE in China in the past decade, but the underlying effector mechanisms of TCE remain unclear. The purpose of the present study is to examine the alteration of hepatic metabolic enzyme gene and apoptosis-related gene messenger RNA (mRNA) expression in L02 human hepatocytes (L02 cells) after treatment with TCE. L02 cells were cultured either with various doses of TCE (0.25, 0.5, 1.0 and 2.0 mmol/L) for 24 h or with a single dose of TCE (1.0 mmol/L) for different time intervals, whereas samples treated with dimethyl sulfoxide served as control. Quantitative real-time polymerase chain reaction analysis was performed to detect the mRNA expression of hepatic metabolic enzyme genes ( CYP1A2, CYP3A4 and CYP2E1) and apoptosis-related genes ( BAX and BAD). It was found that the transcript levels of hepatic metabolic enzyme genes and apoptosis genes including BAX and BAD were significantly increased after TCE treatment at various doses for 24 h when compared with controls. Additionally, when the cells were treated with a single dose of TCE (1.0 mmol/L) for different periods of time (3, 6, 12 and 24 h), the mRNA expression of these genes also increased significantly compared with control ( p < 0.05 or p < 0.01). The conclusion of the study is that TCE could induce alteration of mRNA expression of hepatic metabolic enzyme genes and apoptosis genes, which might be implicated in the effector mechanisms of TCE cytotoxicity in vivo.

Trichloroethylene hypersensitivity syndrome: a disease of fatal outcome

Trichloroethylene is commonly used as an industrial solvent and degreasing agent. The clinical features of acute and chronic intoxication with trichloroethylene are well-known and have been described in many reports, but hypersensitivity syndrome caused by trichloroethylene is rarely encountered. For managing patients with trichloroethylene hypersensitivity syndrome, avoiding trichloroethylene and initiating glucocorticoid have been generally accepted. Generally, glucocorticoid had been tapered as trichloroethylene hypersensitivity syndrome had ameliorated. However, we encountered a typical case of trichloroethylene hypersensitivity syndrome refractory to high dose glucocorticoid treatment. A 54-year-old Korean man developed jaundice, fever, red sore eyes, and generalized erythematous maculopapular rashes. A detailed history revealed occupational exposure to trichloroethylene. After starting intravenous methylprednisolone, his clinical condition improved remarkably, but we could not reduce prednisolone because his liver enzyme and total bilirubin began to rise within 2 days after reducing prednisolone under 60 mg/day. We recommended an extended admission for complete recovery, but the patient decided to leave the hospital against medical advice. The patient visited the emergency department due to pneumonia and developed asystole, which did not respond to resuscitation.

Hypersensitivity syndrome due to trichloroethylene exposure: a severe generalized skin reaction resembling drug-induced hypersensitivity syndrome

The number of patients suffering from trichloroethylene (TCE)-related severe skin disorders with liver dysfunction has been increasing in developing countries in Asia, especially since the mid-1990s. In Japan, five cases of this disease have been reported, but none since the 1990s. However, two additional cases were recently observed in Tokyo. The published work and our investigation indicated that oxidative metabolites of TCE, which might include trichloroacetylated-protein adducts, could induce a generalized skin eruption. Furthermore, human leukocyte antigen (HLA)-B*1301 and HLA-B*44 were identified as markers of individual susceptibility to TCE-induced hypersensitivity syndrome (HS). Moreover, polymorphism of aldehyde dehydrogenase (ALDH), the major enzyme in TCE metabolism, appeared to be associated with TCE-induced HS. Interestingly, this disorder is quite similar to drug-induced hypersensitivity syndrome (DIHS), also referred to as drug rash with eosinophilia and systemic symptoms (DRESS), from the perspective of the onset of the reaction after exposure to TCE/drugs, clinical manifestations, blood examination and period of virus reactivation. This article reviews the similarity between TCE-related HS and DIHS/DRESS.

Hazardous organic compounds in groundwater near Tehran automobile industry

Potential of groundwater contamination by trichloroethylene (TCE) and other volatile organic compounds VOCs near car industry was conducted in this study. TCE, PCE, toluene, xylene, dichloromethane, cyclohexane, n-hexane and n-pentane were detected in all groundwaters. Mean TCE levels in groundwater ranged from 124.37 to 1,035.9 μg L⁻¹ with maximum level of 1,345.7 μg L⁻¹. Due to the data obtained from conventional wastewater treatment in car factory the TCE removal efficiency was only 24 percent which necessitates the TCE removal by advanced treatment processes before the use of well water.

Differential response to trichloroethylene-induced hepatosteatosis in wild-type and PPARalpha-humanized mice

BACKGROUND

Trichloroacetic acid, an oxidative metabolite of trichloroethylene (TRI), is a ligand of the peroxisome proliferator-activated receptor alpha (PPAR) alpha, which is involved in lipid homeostasis and anti-inflammation.

OBJECTIVE

We examined the role of mouse and human PPARalpha in TRI-induced hepatic steatosis and toxicity.

METHODS

Male wild-type (mPPARalpha), Pparalpha-null, and humanized PPARalpha (hPPARalpha) mice on an Sv/129 background were exposed via inhalation to 0, 1,000, and 2,000 ppm TRI for 8 hr/day for 7 days. We assessed TRI-induced steatosis or hepatic damage through biochemical and histopathological measurements.

RESULTS

Plasma alanine aminotransferase and aspartate aminotransferase activities increased in all mouse lines after exposure to 1,000 and 2,000 ppm TRI. Exposure induced hepatocyte necrosis and inflammatory cells in all mouse lines, but hepatic lipid accumulation was observed only in Pparalpha-null and hPPARalpha mice. No differences were observed in TRI-mediated induction of hepatic PPARalpha target genes except for a few genes that differed between mPPARalpha and hPPARalpha mice. However, TRI significantly increased expression of triglyceride (TG)-synthesizing enzymes, diacyl-glicerol acyltransferases, and PPARgamma in Pparalpha-null and hPPARalpha mice, which may account for the increased TG in their livers. TRI exposure elevated nuclear factor-kappa B (NFkappaB) p52 mRNA and protein in all mice regardless of PPARalpha genotype.

CONCLUSIONS

NFkappaB-p52 is a candidate molecular marker for inflammation caused by TRI, and PPARalpha may be involved in TRI-induced hepatosteatosis. However, human PPARalpha may afford only weak protection against TRI-mediated effects compared with mouse PPARalpha.