Inhibition of TAK1 aggravates airway inflammation by increasing RIPK1 activity and promoting macrophage death in a mouse model of toluene diisocyanate-induced asthma / 南方医科大学学报

OBJECTIVE@#To explore the effect of transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) on toluene diisocyanate (TDI)-induced allergic airway inflammation in mice.@*METHODS@#Thirty-two mice were randomly divided into AOO group, AOO+5Z-7-Oxozeaenol group, TDI group, and TDI+5Z-7-Oxozeaenol group. Another 32 mice were randomly divided into AOO group, TDI group, TDI +5Z-7-Oxozeaenol group, and TDI +5Z-7-Oxozeaenol + Necrostatin-1 group. TAK1 inhibitor (5Z-7-Oxozeaenol, 5 mg/kg) and/or RIPK1 inhibitor (Necrostatin-1, 5 mg/kg) were used before each challenge. Airway responsiveness, airway inflammation and airway remodeling were assessed after the treatments. We also examined the effect of TDI-human serum albumin (TDI-HSA) conjugate combined with TAK1 inhibitor on the viability of mouse mononuclear macrophages (RAW264.7) using CCK8 assay. The expressions of TAK1, mitogen-activated protein kinase (MAPK) and receptor interacting serine/threonine protease 1 (RIPK1) signal pathway in the treated cells were detected with Western blotting. The effects of RIPK1 inhibitor on the viability of RAW264.7 cells and airway inflammation of the mouse models of TDI-induced asthma were evaluated.@*RESULTS@#TAK1 inhibitor aggravated TDI-induced airway inflammation, airway hyper responsiveness and airway remodeling in the mouse models (P < 0.05). Treatment with TAK1 inhibitor significantly decreased the viability of RAW264.7 cells, which was further decreased by co-treatment with TDI-HSA (P < 0.05). TAK1 inhibitor significantly decreased the level of TAK1 phosphorylation and activation of MAPK signal pathway induced by TDI-HSA (P < 0.05). Co-treatment with TAK1 inhibitor and TDI-HSA obviously increased the level of RIPK1 phosphorylation and caused persistent activation of caspase 8 (P < 0.05). RIPK1 inhibitor significantly inhibited the reduction of cell viability caused by TAK1 inhibitor and TDI-HSA (P < 0.05) and alleviated the aggravation of airway inflammation induced by TAK1 inhibitors in TDI-induced mouse models (P < 0.05).@*CONCLUSION@#Inhibition of TAK1 aggravates TDI-induced airway inflammation and hyperresponsiveness and may increase the death of macrophages by enhancing the activity of RIPK1 and causing persistent activation of caspase 8.

Serum Periostin Levels: A Potential Serologic Marker for Toluene Diisocyanate-Induced Occupational Asthma

PURPOSE: Toluene diisocyanate (TDI) is a leading cause of occupational asthma (OA). Periostin is a matricellular protein implicated in type 2 immunity-driven asthma. Its pathogenic role in TDI-OA has not been completely elucidated. The present study was performed to investigate the role of periostin in TDI-OA. MATERIALS AND METHODS: Serum periostin levels were measured in subjects with TDI-OA, asymptomatic TDI-exposure controls (AECs), non-occupational asthmatics (NAs), and unexposed normal controls (NCs). To understand the mechanism by which TDI induces periostin production, primary small airway epithelial cells (SAECs) were cultured under stimulation of TDI and neutrophils from asthmatic patients. RESULTS: Fifty-three subjects with TDI-OA, 71 AECs, 67 NAs, and 83 NCs were enrolled. Serum periostin levels were significantly higher in TDI-OA subjects than in AECs (p=0.001), NAs (p < 0.001), and NCs (p < 0.001). In TDI-exposed subjects (TDI-OA and AEC), the PC20 methacholine levels were significantly lower in subjects with a higher periostin level than in those with a lower periostin level. TDI exposure did not increase periostin production directly by SAECs; however, periostin production increased significantly after co-culture with TDI and neutrophils, which was suppressed by an antioxidant. In addition, increased release of TGF-β1 was noted from SAECs when exposed to TDI and neutrophils, which was also suppressed by an antioxidant. CONCLUSION: These results suggest that an increased periostin level may contribute to the progression of airway inflammation to remodeling in TDI-exposed workers. A high serum periostin level is a potential serologic marker of the phenotype of TDI-OA.

Evaluation of chemical-specific IgG antibodies in male workers from a urethane foam factory

BACKGROUND@#Plastic resins are complex chemicals that contain toluene diisocyanate (TDI) and/or trimellitic anhydride (TMA), which cause occupational allergies (OA), including respiratory allergies. Serum IgGs against TDI and TMA have been suggested as potential markers of the exposure status and as exploring cause of OA. Although TDI-specific IgG has been examined for suspected OA, TMA-specific IgG is not commonly evaluated in a urethane foam factory. This study therefore investigated both TDI- and TMA-specific IgGs in suspected OA patients and to evaluate the usefulness of the measurement of multiple chemical-specific IgG measurement for practical monitoring.@*METHODS@#Blood samples were collected from two male workers who developed respiratory allergies supposedly caused by occupational exposure to TDI and/or TMA for the presence of TDI- and TMA-specific IgGs. In addition, blood samples from 75 male workers from a urethane foam factory, along with 87 male control subjects, were collected in 2014 and tested for the same IgGs in 2014. The presence and levels of TDI- and TMA-specific serum IgGs were measured using dot blot assays.@*RESULTS@#We found that controls had mean concentrations of TDI- and TMA-specific IgGs of 0.98 and 2.10 μg/mL, respectively. In the two workers with respiratory allergies, the TDI-specific IgG concentrations were 15.6 and 9.51 μg/mL, and TMA-specific IgG concentrations were 4.56 and 14.4 μg/mL, which are clearly higher than those in controls. Mean concentrations of TDI- and TMA-specific IgGs in the factory workers were 1.89 and 2.41 μg/mL, respectively, and are significantly higher than those of the controls (P < 0.001 and P < 0.026 for TDI- and TMA-specific IgGs, respectively).@*CONCLUSION@#The workers suspected of OA showed an evidently high level of TDI- and TMA-specific IgG, and these levels in workers at the urethane foam factory were also significantly higher than those in controls. In conclusion, the measurement of TDI- and TMA-specific IgG among workers using plastic resins is helpful to monitor their exposure status.

Epithelial folliculin is involved in airway inflammation in workers exposed to toluene diisocyanate

Toluene diisocyanate (TDI) exposure can directly activate and damage airway epithelium. Folliculin (FLCN) is a protein expressed by human airway epithelial cells (HAECs) to maintain airway epithelial integrity and survival. This study investigated the involvement of FLCN in the pathogenesis of TDI-induced occupational asthma (OA). Enzyme-linked immunosorbent assay was used to measure serum levels of FLCN in TDI-exposed subjects (93 TDI-OA patients and 119 asymptomatic exposed controls (AEC)), 200 non-occupational asthma (NOA) patients and 71 unexposed healthy normal controls (NCs). Significantly more subjects in the TDI-OA and AEC groups had high serum levels of FLCN compared to those in the NOA group (P=0.002 and P=0.001, respectively), all of which were higher than the NC group (all P<0.001). The serum level of FLCN was positively correlated with TDI exposure duration (r=0.251, P=0.027), but was negatively correlated with asthma duration of TDI-OA patients (r=−0.329, P=0.029). TDI-exposed subjects with high FLCN levels had higher serum levels of total IgE than those with lower levels. The effects of TDI exposure on FLCN production was investigated by treating HAECs (A549 cells) with TDI-human serum albumin conjugate, which showed increased expression and release of FLCN and interleukin-8 from HAECs. Co-culture with peripheral blood neutrophils also induced FLCN expression and release from HAECs. In conclusion, TDI exposure and TDI-induced neutrophil recruitment into the airways can activate and stimulate HAECs to produce FLCN, which could be involved in airway inflammation in workers exposed to TDI.

Toluene diisocyanate exposure induces airway inflammation of bronchial epithelial cells via the activation of transient receptor potential melastatin 8

Toluene diisocyanate (TDI) is the most important cause of occupational asthma (OA), and various pathogenic mechanisms have been suggested. Of these mechanisms, neurogenic inflammation is an important inducer of airway inflammation. Transient receptor potential melastatin 8 (TRPM8) is a well-established cold-sensing cation channel that is expressed in both neuronal cells and bronchial epithelial cells. A recent genome-wide association study of TDI-exposed workers found a significant association between the phenotype of TDI-induced OA and the single-nucleotide polymorphism rs10803666, which has been mapped to the TRPM8 gene. We hypothesized that TRPM8 located in airway epithelial cells may be involved in the pathogenic mechanisms of TDI-induced OA and investigated its role. Bronchial epithelial cells were treated with TDI in a dose- and time-dependent manner. The expression levels of TRPM8 mRNA and protein were determined by quantitative real-time polymerase chain reaction and western blotting. TDI-induced morphological changes in the cells were evaluated by immunocytochemistry. Alterations in the transcripts of inflammatory cytokines were examined in accordance with TRPM8 activation by TDI. TRPM8 expression at both the mRNA and protein levels was enhanced by TDI in airway epithelial cells. TRPM8 activation by TDI led to significant increases in the mRNA of interleukin (IL)-4, IL-13, IL-25 and IL-33. The increased expression of the cytokine genes by TDI was partly attenuated after treatment with a TRPM8 antagonist. TDI exposure induces increased expression of TRPM8 mRNA in airway epithelial cells coupled with enhanced expression of inflammatory cytokines, suggesting a novel role of TRPM8 in the pathogenesis of TDI-induced OA.

Effect of occupational exposure to toluene diisocyanate on workers' health / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of occupational exposure to toluene diisocyanate (TDI) on the workers' health.</p><p><b>METHODS</b>A total of 76 workers exposed to TDI (exposure group) and 64 management staff members (control group) were selected from a factory as the study subjects. Area sampling was performed for the place with exposure to TDI according to the method in GBZ 159-2004 Specifications of air sampling for hazardous substances monitoring in the workplace, and gas chromatography was applied to measure the concentration of TDI in workplace air. The workers' personal information was collected with questionnaire, pulmonary ventilation function was determined with a portable spirometer, hematological parameters were analyzed by automatic blood analyzer and blood chemistry analyzer, and the indicators of oxidative damage and energy metabolism were measured by the reagent kit provided by Nanjing Jiancheng Bioengineering Institute. SPSS 17 software was applied for statistical analysis.</p><p><b>RESULTS</b>The exposure group had significantly lower forced vital capacity (FVC), forced expiratory volume in 1 second(FEV1.0), and FEV1.0/FVC ratio than the control group (P <0.05). Compared with the control group, the exposure group had significantly higher red blood cell count, platelet distribution width, mean platelet volume, lymphocyte count, and neutrophil count(P<0.01), and significantly lower activities of lactate dehydrogenase(LDH), superoxide dismutase, and succinodehydrogenase (SDH)(P <0.01). In the exposure group, the length of exposure was negatively correlated with the activities of SDH and LDH in the serum (r=-0.319, P <0.05; r=-0.239, P <0.05), and the length of exposure was not found to be correlated with the activity of SOD and pulmonary function indices.</p><p><b>CONCLUSION</b>TDI can induce inflammatory response and lung ventilation function impairment in workers exposed to TDI, as well as oxidative stress and imbalance of energy metabolism. Therefore, it can cause damage to workers' health, and protective measures should be enhanced.</p>

Effect of Ipomea carnea Jacq. flowers on hematological changes in toluene diisocyanate-induced inflammation in Wistar rats / 中国天然药物

AIM@#To investigate the active chloroform fraction of the ethanol extract of Ipomoea carnea flowers on hematological changes in toluene diisocyanate-induced inflammation in Wistar rats.@*METHOD@#Except for the control group, all of the rats were sensitized with intranasal application of 5 μL of 10% toluene diisocyanate (TDI) for 7 days. One week after second sensitization, all of the rats were provoked with 5 μL of 5% TDI to induce airway hypersensitivity. After the last challenge, blood and bronchoalvelor lavage (BAL) fluid were collected and subjected to total and differential leucocytes count. Flash chromatography was performed on the most active chloroform fraction to isolate an individual component.@*RESULTS@#Treatment with the ethanolic extract and its chloroform fraction at an oral dose of 200 mg·kg⁻¹ showed a significant decrease in circulating neutrophil and eosinophil in blood and BAL as compared with standard dexamethasone (DEXA). The structure of the compound obtained from chloroform fraction of Ipomea carnea was elucidated as stigmast-5, 22-dien-3β-ol on the basis of spectral data analysis.@*CONCLUSION@#The chloroform fraction was found to be more effective to suppress airway hyper reactivity symptoms, and decreased count of both total and differential inflammatory cells.

IL-4 and IL-5 Secretions Predominate in the Airways of Wistar Rats Exposed to Toluene Diisocyanate Vapor / 예방의학회지

OBJECTIVES: We established a Wistar rat model of asthma caused by toluene diisocyanate (TDI) exposure, and investigated the relationship between TDI exposure concentrations and respiratory hypersensitivity, airway inflammation, and cytokine secretions in animals, to better understand the mechanism of TDI induced occupational asthma. METHODS: Wistar rats were exposed to two different concentrations of TDI vapor four hours a day for five consecutive days. Bronchoalveolar lavage (BAL) was performed, and differential leucocytes from the BAL fluid were analyzed. Lung histopathological examination was carried out to investigate the inflammatory status in the airways. Production of cytokines interleukin (IL)-4 and IL-5 productions in the BAL fluid in vivo was determined with enzyme-linked immunosorbent assay kits. RESULTS: The TDI-exposed rats exhibited greater airway hypersensitivity symptoms than the control rats. The BAL differential cell count and lung histopathological examination demonstrated that inflammation reactions were present in both the central and peripheral airways, characterized with marked infiltration of eosinophils in the TDI-exposed rats. The cytokine assay showed that IL-4 and IL-5 were predominantly produced in the BAL fluid in vivo. CONCLUSIONS: These findings imply that TDI exposure concentrations may greatly affect the occurrence and extent of inflammatory events and that Th2 type cytokines may play an important role in the immunopathogenesis of TDI-induced occupational respiratory hypersensitivity.

Effect of toluene diisocyanate on lung function of workers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of long-term exposure to toluene diisocyanate (TDI) on the lung function of TDI-exposed workers.</p><p><b>METHODS</b>A factory was selected for this occupational epidemiological investigation. The workers who were exposed to TDI and had complete physical examination records in recent 3 years were the exposed group (n = 45), while the company's administrative staff, logistics staff, and other non-TDI-exposed workers who had complete physical examination records in recent 3 years were the control group (n = 47). The two groups were compared in terms of lung function indices.</p><p><b>RESULTS</b>Compared with the control group, the 2009 exposure group had significantly lower forced expiratory volume in one second (FEV1.0), FEV1.0/forced vital capacity (FVC), and maximal expiratory flow at 25% of FVC (MEF25) (P < 0.05), the 2010 exposure group had significantly lower FEV1.0, FEV1.0/FVC,maximum voluntary ventilation (MVV), and maximal expiratory flow at 50% of FVC (MEF50) (P < 0.05), and the 2011 exposure group had significantly lower FEV1.0, FEV1.0/FVC, peak expiratory flow (PEF), MEF25, and MEF50 (P < 0.05).</p><p><b>CONCLUSION</b>Long-term exposure to TDI can lead to certain impairment of lung function in workers, which may be reflected by decreased lung function indices such as vital capacity, FVC, FEV1.0, FEV1.0/FVC, PEF, and MVV.</p>

Role of vitamin D-binding protein in isocyanate-induced occupational asthma

The development of a serological marker for early diagnosis of isocyanate-induced occupational asthma (isocyanate-OA) may improve clinical outcome. Our previous proteomic study found that expression of vitamin D-binding protein (VDBP) was upregulated in the patients with isocyanate-OA. In the present study, we evaluated the clinical relevance of VDBP as a serological marker in screening for isocyanate-OA among exposed workers and its role in the pathogenesis of isocyanate-OA. Three study groups including 61 patients with isocyanate-OA (group I), 180 asymptomatic exposed controls (AECs, group II), 58 unexposed healthy controls (NCs, group III) were enrolled in this study. The baseline serum VDBP level was significantly higher in group I compared with groups II and III. The sensitivity and specificity for predicting the phenotype of isocyanate-OA with VDBP were 69% and 81%, respectively. The group I subjects with high VDBP (> or = 311 microg/ml) had significantly lower PC20 methacholine levels than did subjects with low VDBP. The in vitro studies showed that TDI suppressed the uptake of VDBP into RLE-6TN cells, which was mediated by the downregulation of megalin, an endocytic receptor of the 25-hydroxycholecalciferol-VDBP complex. Furthermore, toluene diisocyanate (TDI) increased VEGF production and secretion from this epithelial cells by suppression of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] production. The findings of this study suggest that the serum VDBP level may be used as a serological marker for the detection of isocyanate-OA among workers exposed to isocyanate. The TDI-induced VEGF production/secretion was reversed by 1,25(OH)2D3 treatment, which may provide a potential therapeutic strategy for patients with isocyanate-OA.

Mesenchymal Stem Cell Transfer Suppresses Airway Remodeling in a Toluene Diisocyanate-Induced Murine Asthma Model

PURPOSE: Severe asthma is characterized by high medication requirements to maintain good disease control or by persistent symptoms despite high medication use. The transfer of bone marrow-derived mesenchymal stem cells (BMDMSCs) to the injured lungs is a possible treatment for severe asthma. This study investigated the therapeutic effects of BMDMSCs in airway remodeling and inflammation in an experimental toluene diisocyanate (TDI)-induced asthma animal model of severe asthma. METHODS: BMDMSCs were transferred into rats after TDI inhalation. Bronchoalveolar lavage (BAL) cell profiles, histological changes including an inflammatory index and goblet cell hyperplasia, and the airway response to methacholine using plethysmography were analyzed. Smooth muscle actin (SMA) and proliferating cell nuclear antigen (PCNA) protein expression were observed in lung tissue using immunohistochemical staining. The collagen content was measured in lung tissue sections and lung extracts using Masson's trichrome staining and an immunoassay kit. RESULTS: The numbers of inflammatory cells in BAL fluid, histological inflammatory index, airway response to methacholine, number of goblet cells, and amount of collagen were increased in TDI-treated rats compared with sham rats (P=0.05-0.002). BMDMSC transfer significantly reduced the TDI-induced increase in the inflammatory index and numbers of eosinophils and neutrophils in BAL fluid to levels seen in sham-treated rats (P<0.05). BMDMSC transfer significantly reduced the number of goblet cells, collagen deposition, and immune staining for SMA and PCNA with concomitant normalization of the airway response to methacholine. CONCLUSIONS: The systemic transfer of BMDMSCs effectively reduced experimental TDI-induced airway inflammation and remodeling and airway hyperreactivity.

Biomarkers Predicting Isocyanate-Induced Asthma

Three diisocyanates can cause occupational asthma (OA): toluene diisocyanate (TDI), 4,4 diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HDI). We analyzed potential biomarkers of isocyanate-induced OA, based on investigated immunologic, genetic, neurogenic, and protein markers, because there is no serological testing method. The prevalence of serum IgG to cytokeratin (CK)18 and CK19 in TDI-OA was significantly higher than in controls, although the prevalence of these antibodies was too low for them to be used as biomarkers. Another candidate biomarker was serum IgG to tissue transglutaminase (tTG), because the prevalence of serum specific IgG to tTG was significantly higher in patients with TDI-OA than in controls. The human leukocyte antigen (HLA) DRB1*1501-DQB1*0602-DPB1*0501 haplotype may be used as a genetic marker for TDI-OA in Koreans via enhanced specific IgE sensitization in exposed subjects. The genetic polymorphisms of catenin alpha 3, alpha-T catenin (CTNNA3) were significantly associated with TDI-OA. Additionally, examining the neurokinin 2 receptor (NK2R) 7853G>A and 11424 G>A polymorphisms, the NK2R 7853GG genotype had higher serum vascular endothelial growth factor (VEGF) levels than the GA or AA genotypes among Korean workers exposed to TDI. To identify new serologic markers using a proteomic approach, differentially expressed proteins between subjects with MDI-OA and asymptomatic exposed controls in a Korean population showed that the optimal serum cutoff levels were 69.8 ng/mL for ferritin and 2.5 microg/mL for transferrin. When these two parameters were combined, the sensitivity was 71.4% and the specificity was 85.7%. The serum cytokine matrix metalloproteinase-9 (MMP-9) level is a useful biomarker for identifying cases of TDI-OA among exposed workers. Despite these possible biomarkers, more effort should be focused on developing early diagnostic biomarkers using a comprehensive approach based on the pathogenic mechanisms of isocyanate-induced OA.

Effect of toluene diisocyanate on reactive oxygen species production and permeability of human bronchial epithelial cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of toluene diisocyanate (TDI) on the production of reactive oxygen species (ROS) and the permeability of human bronchial epithelial (HBE) cells.</p><p><b>METHODS</b>TDI-human serum albumin (TDI-HSA) conjugate was prepared using a modified Son's method. MTT assay was used to assess HBE cell viability after exposure to different concentrations of TDI-HSA. The level of intracellular ROS of HBE cells was detected by flow cytometry with an oxidation-sensitive fluorescent probe 2',7'-dichlorofluorescein diacetate (DCFH-DA) uploading, and the permeability of cell monolayer was assessed by detecting the transepithelial electrical resistance (TEER).</p><p><b>RESULTS</b>The exposure to 120 µg/ml TDI-HSA did not obviously affect the cell viability. Compared with the control group, the intracellular fluorescent intensity increased significantly in the cells exposed to 20, 60, and 100 µg/ml TDI-HSA (P<0.05). The intracellular ROS production increased significantly after 100 µg/ml TDI-HSA treatment (P<0.05), but the increment in ROS production was significantly suppressed by pretreatment of the cells with N-acetylcysteine (NAC) (P<0.05), which also enhanced the TEER decreased by TDI-HSA treatment (P<0.05).</p><p><b>CONCLUSIONS</b>TDI enhances the permeability of HBE cell monolayer partially through a ROS-mediated pathway, suggesting the importance of oxidative stress in TDI-induced pulmonary diseases.</p>

Probable Role of Beta 2-Adrenergic Receptor Gene Haplotype in Toluene Diisocyanate-Induced Asthma

PURPOSE: A genetic polymorphism of the beta 2-adrenergic receptor is a major factor associated with the asthmatic phenotype. The association of this polymorphism with toluene diisocyanate (TDI)-induced asthma has not been investigated. We examined 103 TDI-induced asthma patients (TDI-OA), 60 asymptomatic exposed controls (AEC), and 263 unexposed healthy controls (NC) in order to identify beta 2-adrenergic receptor gene (ADRB2) polymorphisms and the possible association with TDI-induced asthma. METHODS: Single nucleotide polymorphisms (SNPs) of ADRB2 were genotyped by direct sequencing. Serum-specific IgE and IgG levels were measured using an enzyme-linked immunosorbent assay. Phenotypes and clinical patient parameters were compared. RESULTS: SNPs were identified (-47 T>C, -20 T>C, Arg16Gly A>G, Gln27Glu C>G, Leu134Leu G>A, Arg175Arg C>A) during ADRB2 screening (from -231 to 793 bp). No significant differences in allelic and genotypic frequencies were noted for any of the six ADRB2 SNPs. The Arg16Gly A>G, Leu134Leu G>A, and Arg175Arg C>A SNPs and haplotype 1 [TTACGC] were significantly associated with specific IgE antibodies to the TDI-human serum albumin (HSA) conjugate in TDI-exposed subjects (P<0.05). Exposed workers with the ADRB2 ht1/ht1 homozygote had a significantly higher TDI-HSA conjugate-specific IgE sensitization rate than did those with the null ht1 haplotype (odds ratio, 15.40; 95% confidence interval, 1.81-131.06). CONCLUSIONS: ADRB2 polymorphisms may affect IgE-specific sensitization to TDI-HSA conjugate in TDI-exposed workers.

Toluene diisocyanate increases vascular endothelial growth factor expression in human bronchial epithelial cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of toluene diisocyanate (TDI) on the expression of vascular endothelial growth factor (VEGF) in human bronchial epithelial (HBE) cells.</p><p><b>METHODS</b>TDI-human serum albumin (TDI- HSA) conjugate was prepared using a modified Son's method. MTT assay was used to examine the viability of HBE135-E6E7 cells cultured in serum-free medium after treatment with HSA or TDI-HSA at different concentrations. VEGF mRNA expression of the HBE cells treated with HSA or TDI-HSA at 10, 20, 30 and 40 microg/ ml, respectively, was detected using semi-quantitative RT-PCR.</p><p><b>RESULTS</b>Treatment with 40 microg/ml HSA and 40 microg/ml TDI-HSA did not result in significant changes in the viability of HBE135-E6E7 cells. RT-PCR revealed the constitutive expression of two VEGF isoforms, namely VEGF189 and VEGF165, in cultured HBE135-E6E7 cells. After exposure to TDI-HSA at the different concentrations (except for 10 microg/ml), a significant increase occurred in both VEGF189 and VEGF165 mRNA expressions in HBE135-E6E7 cells as compared with the expressions in the control group and the HSA-treated cells (P<0.05), and significant dose dependence was noted in the effect of TDI-HSA (P<0.05). No significant difference was found in the expressions between the control cells and the HAS-treated cells (P>0.05).</p><p><b>CONCLUSION</b>TDI induces significant increase in VEGF expression in HBE cells, and VEGF overexpression may play an important role in the pathogenesis of TDI-induced asthma.</p>

Cytokeratin Autoantibodies: Useful Serologic Markers for Toluene Diisocyanate-Induced Asthma

To evaluate the clinical significance of autoantibodies to three major epithelial cytokeratins (CK) -- CK8, CK18, and CK19 -- we compared 66 patients with toluene diisocyanate (TDI)-induced asthma (group I) with three control groups: 169 asymptomatic exposed subjects (group II), 64 patients with allergic asthma (group III), and 123 unexposed healthy subjects (group IV). Serum IgG, specific for human recombinant CKs, were measured by ELISA (enzyme linked immunosorbent assay), and ELISA inhibition tests were performed. The existence of these antibodies was confirmed by IgG immunoblot analysis. Anti-TDI-HSA (human serum albumin) IgE and IgG antibodies were measured by ELISA in the same set of the patients. The prevalence of CK8, CK18, and CK19 auotantibodies in group I was significantly higher than in the other three groups. Results of the ELISA inhibition test showed significant inhibition with the addition of three CKs in a dose-dependent manner. No significant association was found between CK autoantibodies and the prevalence of anti- TDI-HSA IgG and IgE antibodies. These results suggest that autoantibodies to CK18 and CK19 can be used as serologic markers for identifying patients with TDI-induced asthma among exposed workers.

Influence of Xinqin tablets on guinea-pig nasal hypersensitivity / 中国中药杂志

<p><b>OBJECTIVE</b>To study the influence of Xinqin tablets on guinea-pig nasal hypersensitivity.</p><p><b>METHOD</b>2,4-Toluene Diisocyanate (TDI) was selected as antigen and used in nose to establish guinea-pig allergic rhinitis. The effects of Xinqin tablets on symptoms of nasal hypersensitivity in guinea-pigs, histamine content of nasal mucosa and activity of nitric oxide synthase (NOS) were examined.</p><p><b>RESULT</b>Xinqin tablets could significantly relieve the pathological symptoms of nasal hypersensitivity in guinea-pig, reduce histamine content of nasal mucosa and inhibit the activity of nitric oxide synthase.</p><p><b>CONCLUSION</b>Xinqin tablets have significant effect on nasal hypersensitivity, and prevent the occurrence of allergic rhinitis.</p>

Prevalence of Occupational Asthma in TDI-Exposed Workers / 대한산업의학회지

OBJECTIVES: This study was carried out to estimate the prevalence of isocyanate-induced occupational asthma in toluene diisocyanate (TDI) exposed workers. METHODS: We examined 170 workers who had been directly exposed to TDI through a medical questionnaire, physical examination, and pulmonary function test. Based on screening examination, workers with suspected occupational asthma were selected for further evaluation such as methacholine and TDI challenge tests. RESULTS: Eleven (6.9%) among 170 workers complained of symptoms of occupational asthma, and 7 among these 11 symptomatic workers showed positive responses to the methacholine challenge test (4.1%). One spray painter was confirmed as having the TDI induced occupational asthma following a positive response to TDI challenge test. CONCLUSIONS: The prevalence of TDI-induced asthma was at 0.58% was lower than that for former studies (2-20%). Improved workplace environment, lower level of TDI exposure compared to the past, and the healthy workers effect may have contributed to this low rate of asthma prevalence in workers with TDI exposure.

Acute and Chronic Changes of Vascular Endothelial Growth Factor (VEGF)in Induced Sputum of Toluene Diisocyanate (TDI)-induced Asthma Patients

Vascular endothelial growth factor (VEGF) is a multi-functional cytokine involved in inflammation, repair and angiogenesis in asthmatic airway. This study aimed to evaluate the role of VEGF in immediate bronchoconstriction induced by TDI inhalation, and in chronic TDI-asthma patients. 11 newly diagnosed TDI-asthma patients (group I), 12 chronic TDI-asthma patients with persistent asthma symptoms followed for >4 yr and 15 unexposed healthy controls were enrolled. In group I, induced sputum and serum were collected before and 7 hr after placebo- and TDI-bronchoprovocation test (BPT). In group II, induced sputum and serum were collected every 2 yr. VEGF levels were measured by ELISA. There were no significant differences in sputum and serum VEGF levels between patients and controls. Before and after placebo and TDI-BPT, no significant changes were noted in sputum and serum VEGF levels of group I. In group II patients, sputum VEGF showed variable changes at 1-yr, then decreased significantly at 2-yr (p<0.05), while serum VEGF showed variable changes at 2-yr, which decreased significantly at 4-yr (p<0.05). These results suggest that VEGF may play a minor role in immediate bronchoconstriction after TDI-BPT. In chronic TDI-asthma, VEGF may be involved to 2 yr after the diagnosis and the contribution may decrease after then.

Effect and mechanism of bishudiwan(BSDW) against allergy / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the effect and mechanism of BSDW on the model of allergic rhinitis and the model of guinea pigs by histamine shocking in guinea pigs.</p><p><b>METHOD</b>Using the model of allergic rhinitis in guinea pigs caused by 10% TDI, we observed the effect of BSDW on physiological and pathological symptoms of allergic rhinitis in guinea pigs, the effect of the levels of serum IgE and serum and nasal histamine. Using the model of guinea pigs by histamine shocking, we observed the effect of BSDW on physiological symptoms in guinea pigs.</p><p><b>RESULT</b>BSDW significantly relieved the pathological symptoms of allergic rhinitis in guinea pigs, alleviated the hyperplasia of columnar epithelium, decreased the number of monocyte and eosinocyte compared with the model group. It also reduced the levels of serum IgE, and decreased the release of serum and nasal histamine. BSDW significantly prolonged the occurent time of gasping, eclampsia and death caused by shock, reduced the times of gasping in the model of guinea pigs by histamine shocking.</p><p><b>CONCLUSION</b>BSDW has significant effect against allergy. The mechanism relates to its effects of decreasing the levels of serum IgE and inhibiting the release of serum and nasal histamine.</p>