Effect of prenatal exposure to combined immunosuppressive agrochemicals in a mouse model of allergic airway inflammation.

The aim of this study is to identify the combined effect of multiple chemicals to the development of allergy. In this study, the effect of prenatal exposure to an organochlorine agent methoxychlor (MXC) and/or an organophosphate agent parathion (PARA) on trimellitic anhydride-induced allergic airway inflammation was examined in mice. Eosinophil infiltration in the bronchoalveolar lavage fluid (BALF) was significantly enhanced by MXC + PARA exposure compared to that of the control, MXC, and PARA groups. In the hilar lymph node, only slight increases in B-cell infiltration, as well as IL-6 and IL-9 secretions were observed in MXC + PARA group, and no effect was observed in the individual treatment groups. Our findings imply that prenatal exposure to some combinations of multiple chemicals may exacerbate the allergic inflammatory responses including eosinophils and cytokine production.

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.

The utility of monitoring trimellitic anhydride (TMA)-specific IgG to predict IgE-mediated sensitization in an immunosurveillance program.

BACKGROUND: Workplace exposure to trimellitic anhydride (TMA) can elicit TMA-specific IgE (sIgE), which may lead to occupational asthma (OA). An occupational immunosurveillance program (OISP) has been implemented to monitor TMA exposure and immunologic outcomes. The purpose of this study was to determine whether TMA-specific IgG (sIgG) responses can discriminate between TMA-exposed workers with and without sIgE responses. METHODS: Serum TMA-specific antibody (IgG, IgG4, and IgE) levels were estimated longitudinally (years 2006 to 2014) in TMA-exposed workers recruited in low, medium, and high exposure areas. sIgG and sIgE titers plotted against exposure duration were compared between workers with (a) sIgG only and (b) with sIgG who developed sIgE. RESULTS: Among 92 TMA-exposed workers continuously monitored for sIgG and sIgE, 38 developed sIgG; 11 developed a sIgE response 342.38 ± 186.03 days posthire and were removed from exposure. The average detection time of sIgG in removed workers (159 ± 92 days) was significantly shorter than for actively exposed workers with only sIgG (346 ± 187 days). Workers with earlier sIgG responses of higher titer (mean value 42.25 µg/mL) compared to delayed responders with lower sIgG titers (mean value 14.79 µg/mL) more frequently developed sIgE responses. Hierarchical clustering showed the initial magnitude and exposure time required for detectable sIgG production discriminated between workers with only sIgG from workers who subsequently produced sIgE. CONCLUSIONS: This study demonstrates the utility of longitudinally monitoring TMA-specific antibodies in an OISP as exposed workers with early sIgG responses and of higher magnitude are more likely to develop TMA sIgE sensitization.

Detection of respiratory allergies caused by environmental chemical allergen via measures of hyper-activation and degranulation of mast cells in lungs of NC/Nga mice.

Respiratory allergy triggered by exposure to environmental chemical allergen is a serious problem in many Asian countries and has the potential to cause severe health problems. Here, we aimed to elucidate the pathogenic mechanisms of this disease and develop an in vivo detection method for respiratory allergy induced by environmental chemical allergen. Both BALB/c and NC/Nga mice were sensitized topically for 3 weeks and were then subjected to inhalation challenge with pulverized trimellitic anhydride into particles measuring 2-µm in diameter. On the day after the final challenge, all mice were sacrificed, and IgE levels, immunocyte counts, and cytokine levels in the serum, hilar lymph nodes, and bronchoalveolar lavage fluid were measured. We also monitored the expression of genes encoding pro-inflammatory cytokines in the lung. We found that all endpoints were significantly increased in mice of both strains subjected to trimellitic anhydride inhalation as compared with the respective control groups. However, worsening of respiratory status was noted only in NC/Nga mice. Interestingly, type 2 helper T-cell reactions were significantly increased in BALB/c mice compared with that in NC/Nga mice. In contrast, the number of mast cells, levels of mast cell-related cytokine/chemokines, and production of histamine in NC/Nga mice were significantly higher than those in BALB/c mice. Thus, environmental chemical allergen induced respiratory allergy in NC/Nga mice in terms of functional and inflammatory symptoms. Furthermore, mast cells may be involved in the aggravation of airway allergic symptoms induced by environmental chemical allergens.

Phthalic anhydride: Illustrating a conundrum in chemical allergy.

Although a substantial number of chemicals has the ability to bind covalently to proteins and thereby, given sufficient exposure, induce a state of sensitization, only a small minority appear to be able to cause allergic hypersensitivity of the respiratory tract; the great majority being exclusively skin sensitizers. The key mechanistic drivers for the differentiation between skin and respiratory sensitization are already well characterized at the cellular/cytokine level. However, at both the chemical level and in terms of predictive toxicology, matters are much less clear. In the present article, phthalic anhydride is used as an exemplar, since it displays a particularly differentiated profile as a chemical allergen. Whereas most respiratory sensitizers are known also to give rise to delayed skin reactions, evidence for phthalic anhydride suggests that it only causes immediate type allergy. Chemically, phthalic anhydride can be presumed to react similar to other respiratory sensitizing anhydrides; in predictive tests for skin sensitization, phthalic anhydride is clearly positive, a property it has in common with all other chemical respiratory allergens. Thus, in the context of interpreting predictive toxicology tests for skin sensitization, the inference is that negative results demonstrate an absence of both skin- and respiratory-sensitizing capacity.

Eosinophil-dependent skin innervation and itching following contact toxicant exposure in mice.

BACKGROUND: Contact toxicant reactions are accompanied by localized skin inflammation and concomitant increases in site-specific itch responses. The role(s) of eosinophils in these reactions is poorly understood. However, previous studies have suggested that localized eosinophil-nerve interactions at sites of inflammation significantly alter tissue innervation. OBJECTIVE: To define a potential mechanistic link between eosinophils and neurosensory responses in the skin leading to itching. METHODS: BALB/cJ mice were exposed to different contact toxicants, identifying trimellitic anhydride (TMA) for further study on the basis of inducing a robust eosinophilia accompanied by degranulation. Subsequent studies using TMA were performed with wild type versus eosinophil-deficient PHIL mice, assessing edematous responses and remodeling events such as sensory nerve innervation of the skin and induced pathophysiological responses (ie, itching). RESULTS: Exposure to TMA, but not dinitrofluorobenzene, resulted in a robust eosinophil skin infiltrate accompanied by significant levels of degranulation. Follow-up studies using TMA with wild type versus eosinophil-deficient PHIL mice showed that the induced edematous responses and histopathology were, in part, causatively linked with the presence of eosinophils. Significantly, these data also demonstrated that eosinophil-mediated events correlated with a significant increase in substance P content of the cutaneous nerves and an accompanying increase in itching, both of which were abolished in the absence of eosinophils. CONCLUSIONS: Eosinophil-mediated events following TMA contact toxicant reactions increase skin sensory nerve substance P and, in turn, increase itching responses. Thus, eosinophil-nerve interactions provide a potential mechanistic link between eosinophil-mediated events and neurosensory responses following exposure to some contact toxicants.

Inhaled multiwalled carbon nanotubes modulate the immune response of trimellitic anhydride-induced chemical respiratory allergy in brown Norway rats.

The interaction between exposure to nanomaterials and existing inflammatory conditions has not been fully established. Multiwalled carbon nanotubes (MWCNT; Nanocyl NC 7000 CAS no. 7782-42-5; count median diameter in atmosphere 61 ± 5 nm) were tested by inhalation in high Immunoglobulin E (IgE)-responding Brown Norway (BN) rats with trimellitic anhydride (TMA)-induced respiratory allergy. The rats were exposed 2 days/week over a 3.5-week period to a low (11 mg/m(3)) or a high (22 mg/m(3)) concentration of MWCNT. Nonallergic animals exposed to MWCNT and unexposed allergic and nonallergic rats served as controls. At the end of the exposure period, the allergic animals were rechallenged with TMA. Histopathological examination of the respiratory tract showed agglomerated/aggregated MWCNT in the lungs and in the lung-draining lymph nodes. Frustrated phagocytosis was observed as incomplete uptake of MWCNT by the alveolar macrophages and clustering of cells around MWCNT. Large MWCNT agglomerates/aggregates were found in granulomas in the allergic rats, suggesting decreased macrophage clearance in allergic rats. In allergic rats, MWCNT exposure decreased serum IgE levels and the number of lymphocytes in bronchoalveolar lavage. In conclusion, MWCNT did not aggravate the acute allergic reaction but modulated the allergy-associated immune response.

Effect of simultaneous exposure to mixture of two skin sensitizers on skin sensitization response in guinea pigs and mice.

Skin sensitization resulting in allergic contact dermatitis is a common occupational health issue. In this study, the effect of mixing two skin sensitizers on the skin sensitization response was investigated. Skin sensitizers are generally classified into T helper type 1 (Th1) or T helper type 2 (Th2), depending on the induced cytokine profile. Dinitrochlorobenzene (DNCB) and oxazolone (Oxa) are Th1 skin sensitizers and phthalic anhydride (PA) and toluene diisocyanate (TDI) are Th2 skin sensitizers. We investigated the effect on skin sensitization response to mixtures of three pairs of these sensitizers: DNCB and Oxa, DNCB and PA, and PA and TDI, using guinea pig maximization test and mouse ear swelling test. In guinea pigs sensitized with the mixture of DNCB and Oxa or PA and TDI, there were changes of skin sensitization response to DNCB and Oxa, and that to PA. On the other hand, there was no mixture effect in guinea pigs sensitized with the mixture of DNCB and PA. The skin sensitization responses were decreased in mice sensitized with the mixtures of DNCB and Oxa or PA and TDI, whereas the mixture effect was not observed in mice sensitized with the mixture of DNCB and PA. The present findings revealed that mixture effect on the skin sensitization response was observed after simultaneous exposure to two skin sensitizers, and the effect was determined by combinations of mixed skin sensitizers.

Integrated testing and assessment approaches for skin sensitization: a commentary.

A Bayesian integrated testing strategy (ITS) approach, aiming to assess skin sensitization potency, has been presented, in which data from various types of in vitro assays are integrated and assessed in combination for their ability to predict in vivo skin sensitization data. Here we discuss this approach and compare it to our quantitative mechanistic modeling (QMM) approach based on physical organic chemistry. The main findings of the Bayesian study are consistent with our chemistry-based approach and our previously published assessment of the key determinants of sensitization potency, in particular the relatively high predictive value found for chemical reactivity data and the relatively low predictive value for bioavailability parameters. As it stands at present the Bayesian approach does not utilize the full range of predictive capability that is already available, and aims only to assign potency categories rather than numerical potency values per se. In contrast, for many chemicals the QMM approach can already provide numerical potency predictions. However, the Bayesian approach may have potential for those chemicals where a chemistry modeling approach cannot provide a complete answer (e.g. pro-electrophiles whose in cutaneo activation cannot currently be modeled confidently). Nonetheless, our main message is of the importance of leveraging chemistry insights and read-across approaches to the fullest extent possible.

Identification of contact and respiratory sensitizers according to IL-4 receptor α expression and IL-2 production.

Identification of allergenic chemicals is an important occupational safety issue. While several methods exist to identify contact sensitizers, there is currently no validated model to predict the potential of chemicals to act as respiratory sensitizers. Previously, we reported that cytometry analysis of the local immune responses induced in mice dermally exposed to the respiratory sensitizer trimellitic anhydride (TMA 10%) and contact sensitizer dinitrochlorobenzene (DNCB 1%) could identify divergent expression of several immune parameters. The present study confirms, first, that IgE-positive B cells, MHC class II molecules, interleukin (IL)-2, IL-4 and IL-4Rα can differentiate the allergic reactions caused by high doses of strong respiratory (TMA, phthalic anhydride and toluene diisocyanate) and contact sensitizers (DNCB, dinitrofluorobenzene and oxazolone). The second part of the study was designed to test the robustness of these markers when classing the weakly immunogenic chemicals most often encountered. Six respiratory allergens, including TMA (2.5%), five contact allergens, including DNCB (0.25%), and two irritants were compared at doses of equivalent immunogenicity. The results indicated that IL-4Rα and IL-2 can be reliably used to discriminate sensitizers. Respiratory sensitizers induced markedly higher IL-4Rα levels than contact allergens, while irritants had no effect on this parameter. Inversely, contact allergens tended to induce higher percentages of IL-2⁺CD8⁺ cells than respiratory allergens. In contrast, the markers MHC-II, IgE and IL-4 were not able to classify chemicals with low immunogenic potential. In conclusion, IL-4Rα and IL-2 have the potential to be used in classifying a variety of chemical allergens.

Is trimellitic anhydride skin testing a sufficient screening tool for selectively identifying TMA-exposed workers with TMA-specific serum IgE antibodies?

OBJECTIVE: Trimellitic anhydride (TMA) can elicit specific IgE-mediated immune responses leading to asthma. This single-blinded study investigated the ability of TMA skin testing to identify workers with TMA-serum specific IgE antibodies. METHODS: Forty TMA-exposed workers who were previously screened for the presence of TMA-IgG and/or IgE serum specific antibodies were skin tested to a TMA-human serum albumin reagent by nurses blinded to their antibody responses. RESULTS: Findings from skin-prick tests were positive in 8 of 11 workers with TMA-serum specific IgE antibodies. Intracutaneous testing, performed only on skin prick testing-negative workers, was positive in two additional workers with TMA-serum specific IgE antibodies. A significant correlation was found between serum and skin test dilutions eliciting positive responses (ρ = 0.87, P < 0.05; n = 11). CONCLUSIONS: TMA skin testing provides an alternative and potentially more practical method for monitoring TMA-exposed workers for developing IgE sensitization.

Smad3 regulates dermal cytokine and chemokine expression and specific antibody production in murine responses to a respiratory chemical sensitizer.

BACKGROUND: The cytokine transforming growth factor-beta(TGF-beta) has important regulatory roles in the immune system. To investigate the role of intact TGF-beta signaling during the contact hypersensitivity (CHS) response to a respiratory allergen, we exposed Smad3-/- mice to topical trimellitic anhydride (TMA). METHODS: CHS was induced by topical application of TMA. The swelling of the TMA-exposed ears was analyzed, and lymph node, ear tissue and skin biopsies were collected for RNA isolation, histology and histochemical analyses. Lymph node cell proliferation was measured and blood samples were collected for analysis of TMA-specific immunoglobulin. RESULTS: Topical TMA exposure resulted in increased mRNA expression of proinflammatory and suppressive cytokines (IL-1beta, TNF-alpha, IL-6, IFN-gamma, IL-4, IL-10, IL-17, IL-23, TGF-beta), chemokines (CXCL9, CXCL10, CCL24) and chemokine receptors (CCR7, CCR8, CXCR2), increased numbers of CD3+ T cells in ear tissue, and lymphadenopathy in the Smad3-/- mice. The IL-10 result was confirmed at the protein level by immunohistochemistry. However, the ear-swelling response and infiltration of eosinophils, F4/80+ cells, CD11c+ cells and mast cells were similar in the Smad3-/- mice compared to their wild-type (WT) siblings. While TMA-specific IgE was induced equally in the WT and Smad3-/- mice, the concentration of TMA-specific IgG2a was significantly lower in the Smad3-/- mice. CONCLUSIONS: The Smad3 molecule contributes significantly to the regulation of the cytokine and chemokine network during the CHS response to TMA. The lack of Smad3 resulted in a potent Th2 shift, confirmed by strongly impaired IgG2a levels.

Use of long term dermal sensitization followed by intratracheal challenge method to identify low-dose chemical-induced respiratory allergic responses in mice.

The inhalation of many types of chemicals, including pesticides, perfumes, and other low-molecular weight chemicals, is a leading cause of allergic respiratory diseases. We attempted to develop a new test protocol to detect environmental chemical-related respiratory hypersensitivity at low and weakly immunogenic doses. We used long-term dermal sensitization followed by a low-dose intratracheal challenge to evaluate sensitization by the well-known respiratory sensitizers trimellitic anhydride (TMA) and toluene diisocyanate (TDI) and the contact sensitizer 2,4-dinitrochlorobenzene (DNCB). After topically sensitizing BALB/c mice (9 times in 3 weeks) and challenging them intratracheally with TMA, TDI, or DNCB, we assayed differential cell counts and chemokine levels in bronchoalveolar lavage fluid (BALF); lymphocyte counts, surface antigen expression of B cells, and local cytokine production in lung-associated lymph nodes (LNs); and antigen-specific IgE levels in serum and BALF. TMA induced marked increases in antigen-specific IgE levels in both serum and BALF, proliferation of eosinophils and chemokines (MCP-1, eotaxin, and MIP-1beta) in BALF, and proliferation of Th2 cytokines (interleukin (IL)-4, IL-10, and IL-13) in restimulated LN cells. TDI induced marked increases in levels of cytokines (IL-4, IL-10, IL-13, and IFN-gamma) produced by restimulated LN cells. In contrast, DNCB treatment yielded, at most, small, nonsignificant increases in all parameters. Our protocol thus detected respiratory allergic responses to low-molecular weight chemicals and may be useful for detecting environmental chemical-related respiratory allergy.

Detection of low-level environmental chemical allergy by a long-term sensitization method.

Multiple chemical sensitivity (MCS) is characterized by various signs, including neurological disorders and allergy. Exposure may occur through a major event, such as a chemical spill, or from long-term contact with chemicals at low levels. We are interested in the allergenicity of MCS and the detection of low-level chemical-related hypersensitivity. We used long-term sensitization followed by low-dose challenge to evaluate sensitization by well-known Th2 type sensitizers (trimellitic anhydride (TMA) and toluene diisocyanate (TDI)) and a Th1 type sensitizer (2,4-dinitrochlorobenzene (DNCB)). After topically sensitizing BALB/c mice (9 times in 3 weeks) and challenging them with TMA, TDI or DNCB, we assayed their auricular lymph nodes (LNs) for number of lymphocytes, surface antigen expression of B cells, and local cytokine production, and measured antigen-specific serum IgE levels. TMA and TDI induced marked increases in levels of antigen-specific serum IgE and of Th2 cytokines (IL-4, IL-5, IL-10, and IL-13) produced by ex vivo restimulated lymph node cells. DNCB induced a marked increase in Th1 cytokine (IL-2, IFN-gamma, and TNF-alpha) levels, but antigen-specific serum IgE levels were not elevated. All chemicals induced significant increases in number of lymphocytes and surface antigen expression of B cells. Our mouse model enabled the identification and characterization of chemical-related allergic reactions at low levels. This long-term sensitization method would be useful for detecting environmental chemical-related hypersensitivity.

Dendritic cells from control but not atopic donors respond to contact and respiratory sensitizer treatment in vitro with differential cytokine production and altered stimulatory capacity.

BACKGROUND: Chemical haptens induce both contact and allergic respiratory disease with dendritic cells (DCs) controlling and directing immune responses in vivo. Contact and respiratory haptens may promote differential cytokine production yet distinguishing these effects in vitro remains difficult due to human donor variability. Objective We sought to determine the effect of atopic status on the ability of DC to respond to contact and respiratory sensitizer treatment in vitro as DC from atopic donors are believed to promote Th2-type responses. METHODS: Enriched DC from control or atopic donors were treated for 4 h with levels of the contact sensitizer 2,4-dinitrochlorobenzene (DNCB) or the respiratory sensitizer trimellitic anhydride (TMA) that did not reduce cell viability. A sensitive intracellular detection technique was used to measure cytokine production, while T cell responses were assessed in a mixed leucocyte reaction. RESULTS: DC from control, non-atopic, donors produced cytokines differentially in response to sensitizer treatment; DNCB treatment significantly increased the production of Th1 cytokines IL-12 and IFN-gamma while TMA induced the production of IL-13. Control donor DC treated with TMA stimulated less in a mixed leucocyte reaction than untreated cells with any response reduced further by blocking IL-13 in culture. However, DC from atopic donors showed no significant alteration in either cytokine production or T cell stimulatory capacity after sensitizer treatment. CONCLUSION: Haptens modulate DC by changing the production of cytokines that may play a role in T cell stimulation and subsequent polarization of the immune response. DC from atopic donors were unresponsive to chemical sensitizer treatment, and may be deficient in inducing divergent T cell responses.

Effects of a diphtheria-tetanus-acellular pertussis vaccine on immune responses in murine local lymph node and lung allergy models.

We have previously shown that in mice, diphtheria-tetanus-acellular pertussis (DTaP) vaccination before Bordetella pertussis infection resulted in, besides effective clearance, immediate hypersensitivity (lung eosinophilia, increased total serum immunoglobulin E [IgE], and increased ex vivo Th2 cytokine production by cells from the bronchial lymph nodes). To better appreciate the extent of these findings, we measured DTaP vaccination effects in the local lymph node assay (LLNA) and an ovalbumin (OVA) lung allergy model. In the LLNA, mice were vaccinated or adjuvant treated before being sensitized with trimellitic anhydride (TMA; inducing a Th2-directed response) and dinitrochlorobenzene (DNCB; inducing a Th1-directed response). Compared to the adjuvant-treated controls, the vaccinated mice showed a decreased response to TMA and (to a much lesser extent) an increased response to DNCB. The decreased response to TMA coincided with increased transforming growth factor beta levels. With the exception of filamentous hemagglutinin, all vaccine constituents contributed to the decreased response to TMA. In the lung allergy model, sensitization induced OVA-specific IgE, lung pathology (peribronchiolitis, perivasculitis, and hypertrophy of the bronchiolar mucus cells) and increased the number of eosinophils, lymphocytes, and neutrophils in the bronchoalveolar lavage fluid. Vaccination failed to modulate these parameters. In conclusion, although DTaP vaccination may affect the LLNA response, we found no evidence of an effect on lung allergy.

Airway responses in Brown Norway rats following inhalation sensitization and challenge with trimellitic anhydride.

Trimellitic anhydride (TMA) is a cause of asthma in man. Dose-dependent TMA-specific IgE, histopathology, and airway responses after sensitization by inhalation were examined in the Brown Norway rat. Rats were exposed to 0.04, 0.4, 4, or 40 mg/m3 TMA aerosol for 10 min, once a week, over 10 weeks. All lower exposures were, subsequently, rechallenged to 40 mg/m3 TMA aerosol. All rats received a sham exposure 1 week prior to the first TMA exposure. Following the sham exposure and weekly after each TMA exposure, TMA-specific IgE and both early-phase airway response (EAR) and late-phase airway response (LAR) were measured using enhanced pause (Penh). All rats sensitized by 40 mg/m3 TMA developed specific IgE, EAR, and LAR to one or more of the challenges to 40 mg/m3 TMA. TMA of 4 mg/m3 induced a much lower, but stable, specific IgE response. EAR and LAR were observed only after a 40 mg/m3 TMA rechallenge in this group, but it was much larger than that observed in the 40 mg/m3 TMA-sensitized and challenged group. Exposure-dependent histopathological changes noted included eosinophilic granulomatous interstitial pneumonia, perivascular eosinophil infiltrates, bronchial-associated lymphoid tissue hyperplasia, and peribronchiolar plasma cell infiltrates.

Ocular and airway symptoms related to organic acid anhydride exposure--a prospective study.

BACKGROUND: Organic acid anhydrides (OAA) are used as hardeners in epoxy resin systems. They are powerful sensitizers giving frequent rhinitis and asthma in exposed workers. Incidence of symptoms is unknown. Here we present the first prospective study on the associations between OAA exposure, symptoms, and effects of confounding factors. METHODS: All new employees in three plants handling OAA were followed for up to 8.5 years. Before the employment, a questionnaire reporting about symptoms of eyes and airways, smoking habits, and atopy was answered. The subjects were asked at regular medical examinations about work tasks and work-related symptoms. Serum was analysed for specific OAA antibodies. RESULTS: Mean exposures varied between 6 and 39 microg/m3. The incidence for work-related symptoms of the eyes, nose, pharynx, and lower airways was 91, 64, 46, and 31 per 1000 years of exposure, respectively. Symptoms were found frequently, even at mean exposure level at <10 microg/m3. Smoking and atopy increased the risk of symptoms. Immunoglobulin (Ig)E sensitized workers had a significant increased risk for symptoms of the eyes and pharynx and for running nose/sneezing. CONCLUSIONS: Organic acid anhydrides exposure is associated with frequent ocular and airway symptoms even at mean exposure levels at <10 microg/m3. There is an important need for establishment of an occupational threshold limit. A limit value of below 5 microg/m3 is proposed.

Alveolar macrophages suppress non-specific inflammation caused by inhalation challenge with trimellitic anhydride conjugated to albumin.

Occupational exposure to low molecular weight chemicals, like trimellitic anhydride (TMA), can result in occupational asthma. Alveolar macrophages (AMs) are among the first cells to encounter these inhaled compounds and were previously shown to affect TMA-induced asthma-like symptoms in the Brown Norway rat (Valstar et al., Toxicol. Appl. Pharmacology 211:20-29, 2006). TMA is a hapten that will bind to endogenous proteins upon entrance of the body. Therefore, in the present study we determined if TMA conjugated to albumin is able to induce asthma-like symptoms and if these are affected by AM depletion. Female Brown Norway rats were sensitized by dermal application of TMA or received vehicle alone on days 0 and 7. One day prior to the inhalation challenge the rats were treated intratracheally with either empty liposomes or liposomes containing clodronate (dichloromethylene diphosphonate) to specifically deplete the lungs of AMs. On day 21, all groups of rats were challenged by inhalation of TMA-BSA. Breathing frequency, tidal volume, and minute ventilation were measured before, during, within 1 h, and 24 h after challenge and the gross respiratory rate score was determined during challenge. Total and TMA-specific IgE levels were determined in serum and lung lavage fluid and parameters of inflammation and tissue damage were assessed in lung lavage fluid and/or lung tissue 24 h after challenge. Sensitization with TMA had no effect on the lung function before challenge, but TMA-BSA challenge resulted in an early asthmatic response as compared to the non-sensitized rats, irrespective of AM depletion. AM depletion had no effect on the sensitization-induced serum and lung lavage fluid IgE levels. TMA-BSA inhalation did not induce airway inflammation and tissue damage irrespective of sensitization, unless AM were depleted. Data indicate that AMs inhibit immunologically non-specific damage and inflammatory cell influx into the lungs as caused by TMA-BSA inhalation. Since effects of inhalation challenge with TMA-BSA are partly different from those of TMA, challenge with the latter is to be preferred for hazard identification.