School attendance and daily respiratory symptoms in children: influence of moisture damage.

We investigated the effect of weekends and school holidays on the daily frequency and severity of respiratory and other symptoms among children attending schools with (index) or without (reference) moisture damage in Spain, the Netherlands, and Finland. Throughout 1 year, parents of 419 children with a respiratory condition attending index (n=15) or reference (n=10) primary schools completed three symptom diaries. We assessed associations between lower respiratory tract, upper respiratory tract or allergy, and other symptom scores and school day, weekend, or summer holiday using mixed regression models stratified by country and moisture damage. We evaluated interactions between moisture damage and type of day. We combined country-specific estimates (incidence rate ratios [IRRs] and 95% confidence interval [CI]) in meta-analyses. Symptom scores were lower during weekends and holiday. Lower respiratory tract symptoms were statistically significantly less common during holiday with strongest effect in index schools (IRR=0.7; CI=0.6-0.8). Reporting of other symptoms was more reduced during holiday in index (IRR=0.6; CI=0.4-0.9) than in reference (IRR=0.95; CI=0.8-1.2) schools (interaction P<.01). In conclusion, symptoms were less frequent and/or severe during summer holiday and weekends. This pattern was stronger among children attending moisture-damaged schools, suggesting potential improvement in moisture damage-related symptoms during school breaks.

Contact dermatitis in the construction industry: the role of filaggrin loss-of-function mutations.

BACKGROUND: A high prevalence of contact dermatitis (CD) and respiratory symptoms has been observed in the construction industry, probably due to widespread exposure to irritants and allergens. It is unknown whether carriers of loss-of-function mutations in the gene encoding filaggrin (FLG), a known risk gene for eczema and asthma, are at increased risk. OBJECTIVES: To investigate associations of FLG mutations with CD and respiratory symptoms in Dutch construction workers. METHODS: A questionnaire including items on dermal and respiratory symptoms such as wheeze, shortness of breath and asthma was administered to construction workers. Total and specific serum IgE was analysed by enzyme immunoassays. Four FLG loss-of-function mutations were genotyped. CD was diagnosed by a team of a dermatologist and a clinical occupational medicine specialist using photographs of the subjects' hands and self-reported questionnaire data. RESULTS: Of the 506 participating workers, 6·3% carried at least one FLG mutation. Mild CD was diagnosed by the specialists in 34·0%, and severe CD in an additional 24·3%. CD was considered work related in 282 of 295 subjects (95·6%). Carriers of FLG variants had an increased risk of CD compared with subjects carrying wild-type alleles [mild CD: odds ratio (OR) 5·71, 95% confidence interval (CI) 1·63-20·06; severe CD: OR 8·26, 95% CI 2·32-29·39]. FLG variants and the presence of CD were not associated with respiratory symptoms and atopy. CONCLUSIONS: Contact dermatitis prevalence in construction workers is high. FLG loss-of-function mutations increase the risk of CD even further. FLG mutations were not associated with respiratory symptoms or atopy.

Allergic sensitization is associated with inadequate antioxidant responses in mice and men.

BACKGROUND: Allergies arise from aberrant Th2 responses to allergens. The processes involved in the genesis of allergic sensitization remain elusive. Some allergens such as derived from house dust mites have proteolytic activity which can induce oxidative stress in vivo. A reduced capacity of the host to control oxidative stress might prime for allergic sensitization. METHODS: Two different strains of mice were compared for their antioxidant and immune response to HDM. Protease activity of the HDM extract was reduced to investigate its role in oxidative stress induction in the airways and whether this induction could determine allergic sensitization and inflammation. The role of oxidative stress in allergic sensitization was also investigated in humans. An occupational cohort of animal workers was followed for the development of sensitization to rodent urinary proteins. Levels of oxidative stress in serum and antioxidant responses by PBMCs were determined. RESULTS: Susceptibility to allergic sensitization to mite allergens in mice was highly dependent on host genetic background and was associated with oxidative stress in the lungs before allergen exposure and poor antioxidant response after allergen exposure. Reduction in mite protease activity limited its capacity to induce oxidative stress and allergic inflammation in mice. We showed that also in human subjects, oxidative stress before allergen exposure and poor antioxidant responses were associated with predisposition to occupational allergy. CONCLUSION: Our study indicates that oxidative stress condition before allergen exposure due to an inadequate antioxidant response may prime for allergic Th2 responses.

Endotoxin levels in settled airborne dust in European schools: the HITEA school study.

Indoor exposure to microbial agents is known to influence respiratory health. Besides home exposure, exposure in schools can affect respiratory health. In this study, we measured endotoxin in settled dust in primary schools in three European countries from three different geographical regions with different climates. Our aim was to characterize endotoxin levels in primary schools and evaluate associations with potential determinants. Endotoxin levels were repeatedly assessed in 23 schools in Spain (n = 7), the Netherlands (n = 10), and Finland (n = 6) using electrostatic dustfall collectors. In total, 645 measurements were taken in 237 classrooms. Endotoxin levels differed significantly between countries; Dutch schools had the highest levels, while Finnish schools showed the lowest levels. In each country, differences in endotoxin levels were observed between schools and over the sampling periods. Estimates improved after adjustment for sampling period. Factors affecting endotoxin levels in a school differed per country. In general, endotoxin levels were higher in lower grades and in classrooms with higher occupancy. School endotoxin levels may contribute significantly to total endotoxin exposure in children and teachers. As the correlation between the repeated measurements is reasonable, single endotoxin measurements form a reasonable basis for estimating annual endotoxin levels in schools.

Occurrence of moisture problems in schools in three countries from different climatic regions of Europe based on questionnaires and building inspections - the HITEA study.

UNLABELLED: The aim of this study was to assess occurrence of dampness and mold in school buildings in three European countries (the Netherlands, Spain, and Finland), representing different climatic regions. An assessment was performed utilizing both questionnaires and on-site building investigations, and the agreement between these two methods was evaluated for validation purposes. On the basis of questionnaire data from a representative sample of schools, different types of moisture problems were reported in 24-47% of all school buildings at the time of the study. Most commonly reported was dampness in the Netherlands, moisture/water damage in Spain, and mold odor in Finland. Subsequently, 20-24 schools per country were selected for on-site inspections by trained staff. The overall agreement between the questionnaire and inspection data was good (kappa-value 0.62), however, with large differences (0.39-0.91) between countries. Extrapolating from the inspection data, the minimum estimates for prevalence of moisture problems in school buildings are 20% in the Netherlands, 41% in Spain, and 24% in Finland. In conclusion, moisture problems (such as moisture damage, dampness, and mold) are relatively common in schools. The occurrence and severity may vary across geographical areas, which can be partly explained by building characteristics. PRACTICAL IMPLICATIONS: On the basis of this study, the prevalence of verified moisture problems in school buildings was highest in Spain, but lower and similar in Finland and the Netherlands. Questionnaire-based surveys can be used to assess moisture problems in school buildings, but because of large variation in agreement with inspection data, the questionnaire needs to be validated by on-site inspections in a subsample of the surveyed buildings.

IgG4 antibodies against rodents in laboratory animal workers do not protect against allergic sensitization.

BACKGROUND: The modified Th2 response, defined as an IgG4 response in the absence of IgE, is suggested to protect against the development of allergic sensitization. However, studies suggesting this protective effect all had a cross-sectional design, making it impossible to study the development of both responses. AIM OF THE STUDY: We aimed to study the dynamics in IgG4 antibodies in relation to allergic sensitization in an occupational cohort of starting laboratory animal workers. Moreover, we studied the relation between exposure, antibody responses, atopy and self reported allergic symptoms. METHODS: A total of 110 starting animal workers were followed for 2 years. IgG4 antibodies against rats and mice were assessed. Workers were tested for allergic sensitization and exposure to animal allergens was estimated. Symptom status was assessed using questionnaires. RESULTS: Rat and mouse specific IgG4 antibodies were present before the development of allergy and did not significantly change over time. Allergic sensitization was related to exposure and atopic status but high levels of IgG4 showed no protective effect. In contrary, workers that developed mouse specific sensitization during follow up had higher levels of mouse specific IgG4. Symptoms were related to allergic sensitization and IgG4 levels did not influence that relationship. CONCLUSIONS: IgG4 antibodies are present before IgE antibodies develop and IgG4 levels are stable over time. In our occupational cohort, the modified Th2 response had no protective effect on development of sensitization or allergic symptoms.

Effectiveness of pulmonary rehabilitation at high-altitude compared to sea-level in adults with severe refractory asthma.

BACKGROUND: Beneficial effects of pulmonary rehabilitation at high-altitude (HAPR) in patients with severe refractory asthma have been reported earlier, but evidence for the effectiveness is limited. AIM: To investigate the effectiveness of high-altitude pulmonary rehabilitation to comparable treatment at sea-level (LAPR) on patient outcome parameters. METHODS: Adults with severe refractory asthma living in The Netherlands were included. Treatment consisted of a 12-week personalized multidisciplinary rehabilitation program either at high-altitude (Davos Switzerland) (n = 93) or in a tertiary lung center at sea-level in The Netherlands (n = 45). At baseline, after treatment, and during 12 months follow-up asthma related quality of life (AQLQ), asthma control (ACQ), pulmonary function and OCS-dose were assessed. Patients could not be randomized resulting in different asthma populations. Groups were compared using linear regression analysis (ANCOVA) adjusted for baseline values, in addition to age, atopy, smoking history, BMI and gender. RESULTS: After treatment, and at 12 months follow-up, improved AQLQ(0.92,p < 0.001 and 0.82,p = 0.001, respectively), ACQ(-0.87,p < 0.001 and -0.69,p = 0.008, respectively) and lower maintenance OCS dose (Unadjusted linear regression analysis-5.29 mg, p = 0.003 and Crude Odds Ratio-1.67, p = 0.003, respectively) were observed in the HAPR-group compared to the LAPR group. Patients receiving HAPR also had less asthma exacerbations (≥1 exacerbation: 20% vs 60%,p < 0.001) and showed improvement in lung function (%predFEV1 3.4%,p = 0.014) compared to the LAPR group, but at 12 months no differences between groups were observed. CONCLUSION: HAPR resulted in a larger improvement in patient outcome parameters compared to LAPR, on the long run the improvement in patient reported symptoms and lower maintenance OCS-dose persists. Underlying factors that explain this observed effect need to be investigated.

Ex vivo cytokine release reflects sensitivity to occupational endotoxin exposure.

Not everyone exposed to endotoxin develops respiratory symptoms, even at very high exposure levels. The aim was to investigate whether ex vivo lipopolysaccharide (LPS)-induced cytokine release may be predictive of individual sensitivity to occupational endotoxin exposure. In 412 agricultural workers, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-10 release was measured in supernatants from LPS-stimulated whole blood, lung function was measured, and respiratory symptoms were assessed by questionnaire. For each cytokine, the population was dichotomised into low and high responders according to median cytokine concentrations. Endotoxin exposure levels were determined based on 249 personal exposure measurements. High IL-10 responders had a higher prevalence of airway symptoms than low IL-10 responders (odds ratios between 2.03 and 5.10; p<0.05). TNF-alpha response was positively, but not significantly, associated with symptoms, whereas no relationship was found between IL-1beta response and symptoms. For all three cytokines, subjects with above-median responses showed significant positive dose-response relationships between endotoxin exposure and asthma symptoms, and significant associations between endotoxin exposure and a lower forced expiratory volume in 1 s (p<0.05). In contrast, exposure-response relationships were weak and statistically nonsignificant for low responders. The ex vivo inflammatory response to LPS reflects, to a large extent, whether individuals are susceptible to adverse respiratory effects induced by high occupational endotoxin exposure.

Stability of individual LPS-induced ex vivo cytokine release in a whole blood assay over a five-year interval.

OBJECTIVE: In epidemiological and clinical studies, whole blood assay (WBA) has been used as a measure to characterize inter-individual differences in the cytokine response of individuals exposed to inflammatory agents, such as endotoxins. Several short-time repeatability studies have shown stable cytokine levels in individuals over periods of days, weeks or months, but little is known about the long-term stability of cytokine reactivity. METHODS: We studied cytokine response levels in LPS-stimulated whole blood in a cohort of 193 farmers and agricultural industry workers at two time points with a five-year interval. RESULTS: IL-10 and IL-1ß responses measured with a five-year time interval showed a weak positive correlation (r = 0.22 and 0.27, respectively), whereas no correlation was observed for TNFα (r = 0.06). Cytokine reactivity measured repeatedly at the same time point showed high correlations (IL-10 r = 0.80, IL-1ß r = 0.53 and TNFα r = 0.74), suggesting that the observed weak correlations over time are reflective of actual variations in cytokine reactivity over time. CONCLUSIONS: Repeatability of ex vivo cytokine reactivity showed to be differential for the measured cytokines, being more stable for IL-10 and IL-1ß than for TNFα. However, in general, repeatability of ex vivo cytokine reactivity was weak, reflecting that cytokine reactivity can mostly be explained by (short term) intra-individual (immunological) or time varying environmental factors and less by genetic or other time-invariant factors. Therefore, WBA should be regarded as a viable tool to study relationships with current health status and exposure, and only partially as a predictor for a future response.

Immunoglobulin E and G4 antibody responses in occupational airway exposure to bovine and porcine plasma proteins.

BACKGROUND: Production of both antigen-specific immunoglobulin (Ig)E and IgG4 antibodies is dependent on stimulation of B cells by T helper 2 cell-derived cytokines. However, there is controversy as to their interaction. In this study, we investigated the interdependency of IgE and IgG4 antibody responses to a relatively high range of airway exposure to animal-derived proteins in an occupational setting. Moreover, associations with self-reported airway symptoms and bronchial hyperresponsiveness were established. METHODS: In a cross-sectional design, employees of an animal plasma spray-drying factory were questioned about airway symptoms, exposure was measured with personal sampling technique, and serology was performed. In a selection of subjects from this population, serology was repeated 15 months later, and bronchial hyperresponsiveness was measured. RESULTS: IgE and IgG4 antibodies were detected in 17 and 57% of all employees and were both associated with degree of exposure. Only IgE antibodies showed an independent association with self-reported airway symptoms and bronchial hyperresponsiveness. The presence of IgE antibodies was limited to employees with high levels of IgG4. Employees with IgE and symptoms appeared to have less IgG4 than asymptomatic IgE-positive individuals. The level of specific IgG4 antibodies was stable over a 15-month period. CONCLUSIONS: In high-range airway exposure, development of IgE and IgG4 antibodies depended on the level of exposure. The threshold for development of IgG4 antibodies appeared to be less than that for IgE antibodies, and IgG4 antibodies may protect against the development of symptoms.

Mouse allergen-specific immunoglobulin G4 and risk of mouse skin test sensitivity.

BACKGROUND: High serum levels of cat-specific IgG and IgG4 are associated with protection against allergic sensitization to cat, but whether this association applies to other animal allergens remains unclear. OBJECTIVE: To determine if high levels of mouse-specific IgG and IgG4 are associated with a decreased risk of mouse skin test sensitivity. METHODS: Two hundred and sixty workers of a mouse facility underwent skin prick testing and completed a questionnaire. Serum levels of mouse-specific IgG and IgG4 were quantified by solid-phase antigen binding assays. Room air samples were collected and airborne Mus m 1 was quantified by ELISA. RESULTS: Forty-nine participants had a positive skin prick test to mouse. Mouse-specific IgG was detected in 219 (84%) participants and IgG4 was detected in 72 (28%) participants. A detectable mouse-specific IgG4 level was associated with an increased risk of mouse skin test sensitivity (odds ratios (OR) 6.4, 95% confidence intervals (CI) 3.3-12.4). Mouse-specific IgG and IgG4 were both positively correlated with mouse allergen exposure (r(s)=0.31, P=0.0001, and r(s)=0.27, P=0.0006, respectively). The odds of skin test sensitivity peaked at moderate levels of IgG4, but decreased at the highest levels of mouse-specific IgG4. In contrast, the odds of skin test sensitivity increased monotonically with IgG levels. CONCLUSIONS: A detectable level of mouse-specific IgG4 is associated with an increased risk of skin test sensitivity to mouse. However, the highest IgG4 levels appear to be associated with an attenuated risk of mouse skin test sensitivity, suggesting that induction of high levels of IgG4 through natural exposure may protect against the development of allergic sensitization.

Mouse allergen-specific immunoglobulin G and immunoglobulin G4 and allergic symptoms in immunoglobulin E-sensitized laboratory animal workers.

BACKGROUND: High levels of allergen-specific IgG have been associated with clinical efficacy in immunotherapy studies, but whether this antibody isotype is associated with clinical tolerance in the setting of environmental exposure remains unclear. OBJECTIVE: To determine if mouse allergen-specific IgG (mIgG) and IgG4 (mIgG4) levels are associated with mouse-related symptoms among IgE-sensitized laboratory workers. METHODS: Fifty-eight workers with either skin test or serologic evidence of IgE-mediated mouse sensitization were studied. Symptom data were obtained by a questionnaire. Serum levels of mouse-specific IgG, IgG4, and IgE were quantified by a solid-phase antigen-binding assay (IgG) and RAST (IgG4 and IgE), and the relationships between mouse-specific serologic responses and mouse-related symptoms were analysed. RESULTS: Twenty-three (39.7%) participants reported mouse-related symptoms. Mouse-specific IgG and IgG4 levels were not associated with mouse-related symptoms among the study population as a whole. Among the 29 (50%) participants with detectable mouse-specific IgE (mIgE), higher mouse-specific IgG and IgG4 levels were associated with a decreased risk of symptoms, after adjusting for mIgE level (odds ratio (OR) 0.3, 95% confidence interval (CI): 0.1-1.4, and OR 0.3, 95% CI: 0.04-2.6, respectively). Higher levels of mIgG and mIgG4 remained associated with a decreased risk of symptoms after additional adjustment for sex and handling of mice (OR 0.1, 95% CI: 0.02-0.7, and OR 0.2, 95% CI: 0.02-2.1, respectively). Higher mIgG : IgE and mIgG4 : IgE ratios were also associated with a decreased risk of symptoms after adjusting for these confounders (OR 0.1, 95% CI: 0.02-0.7, and OR 0.2, 95% CI: 0.02-0.92, respectively). CONCLUSION: Among workers with detectable mIgE, higher mIgG and mIgG4 levels are associated with a decreased risk of mouse-related symptoms. High serum levels of mIgG or mIgG4 may be markers for clinical tolerance among laboratory mouse workers with detectable mIgE, but these findings need to be confirmed in larger, prospective studies.

Serum surfactant protein D is elevated in allergic patients.

BACKGROUND: There is evidence that surfactant protein (SP)-D is important in the innate, as well as in the adaptive pulmonary immune response. Serum concentrations of SP-D have been proposed as parameter of the integrity of the blood-airspace barrier in interstitial lung diseases. We hypothesized that serum SP-D concentrations are affected in allergic patients and correlate with changes in allergic airway inflammation. OBJECTIVE: To determine levels of serum SP-D in allergic patients compared with non-allergic controls. Furthermore, to investigate associations between serum SP-D concentrations on the one hand and changes in commonly used markers of bronchial inflammation in allergic airways disease on the other hand. MATERIALS AND METHODS: Fifty allergic patients were studied and bronchial allergen challenge was used as a model to increase bronchial allergic inflammation in these patients. Serum SP-D concentrations, inflammatory parameters in induced sputum and bronchial hyper-responsiveness (BHR) were determined before and after allergen challenge. Twenty-five non-allergic volunteers served as controls. RESULTS: Baseline serum SP-D was significantly higher in allergic patients as compared with controls (mean serum SP-D concentration (95% confidence interval): 62.7 (55.5, 70.0) in allergic patients vs. 49.5 (36.7, 62.3) ng/mL in non-allergic controls, P=0.006). In addition, baseline serum SP-D appeared to be an independent predictor for the magnitude of the late asthmatic response after allergen challenge. Furthermore, serum SP-D was predictive for the sputum eosinophil cationic protein concentration after allergen challenge. CONCLUSION: We propose that serum SP-D concentrations are associated with allergic bronchial inflammation and may give additional information, beside BHR and sputum eosinophils, about the degree of bronchial inflammation in allergic patients.