Occupational Allergic Sensitization Among Workers Processing King Crab (Paralithodes camtschaticus) and Edible Crab (Cancer pagurus) in Norway and Identification of Novel Putative Allergenic Proteins

Introduction: Asthma and allergy occur frequently among seafood processing workers, with the highest prevalence seen in the crustacean processing industry. In this study we established for the first time the prevalence of allergic sensitization in the Norwegian king- and edible crab processing industry and characterized the IgE-reactive proteins.

Materials and Methods: Two populations of crab processing workers participated; 119 king crab and 65 edible crab workers. The investigation included information on work tasks and health through a detailed questionnaire. Allergic sensitization was investigated by crab-specific IgE quantification and skin prick tests (SPT) to four in-house prepared crab extracts; raw meat, cooked meat, raw intestines and raw shell. Allergen-specific IgE binding patterns were analyzed by IgE immunoblotting to the four allergen extracts using worker serum samples. Total proteins in crab SPT extracts and immunoblot-based IgE binding proteins were identified by mass spectrometric analysis.

Results: Positive SPTs were established in 17.5% of king- and 18.1% of edible crab workers, while elevated IgE to crab were demonstrated in 8.9% of king- and 12.2% of edible crab processing workers. There was no significant difference between the king and edible crab workers with respect to self-reported respiratory symptoms, elevated specific IgE to crab or SPT results. Individual workers exhibited differential IgE binding patterns to different crab extracts, with most frequent binding to tropomyosin and arginine kinase and two novel IgE binding proteins, hemocyanin and enolase, identified as king- and edible crab allergens.

Conclusions: Occupational exposure to king- and edible crabs may frequently cause IgE mediated allergic sensitization. Future investigations addressing the diagnostic value of crab allergens including tropomyosin and arginine kinase and the less well-known IgE-binding proteins hemocyanin and enolase in a component-resolved diagnostic approach to crab allergy should be encouraged.

Food processing and occupational respiratory allergy- An EAACI position paper

Occupational exposure to foods is responsible for up to 25% of cases of occupational asthma and rhinitis. Animal and vegetable high-molecular-weight proteins present in aerosolized foods during food processing, additives, preservatives, antioxidants, and food contaminants are the main inhalant allergen sources. Most agents typically cause IgE-mediated allergic reactions, causing a distinct form of food allergy (Class 3 food allergy). The allergenicity of a food protein, allergen exposure levels, and atopy are important risk factors. Diagnosis relies on a thorough medical and occupational history, functional assessment, assessment of sensitization, including component-resolved diagnostics where appropriate, and in selected cases specific inhalation tests. Exposure assessment, including allergen determination, is a cornerstone for establishing preventive measures. Management includes allergen exposure avoidance or reduction (second best option), pharmacological treatment, assessment of impairment, and worker's compensation. Further studies are needed to identify and characterize major food allergens and define occupational exposure limits, evaluate the relative contribution of respiratory versus cutaneous sensitization to food antigens, evaluate the role of raw versus cooked food in influencing risk, and define the absolute or relative contraindication of patients with ingestion-related food allergy, pollinosis, or oral allergy syndrome continuing to work with exposure to aerosolized food allergens.

Lung function and prevalence of respiratory symptoms in Norwegian crab processing workers

Background: Seafood processing workers have an increased risk of developing occupational asthma. This has not been studied among Norwegian crab processing workers, nor has the respiratory health of exposed workers been compared to a control group.

Objectives: Assessing the impact of working in the crab processing industry on workers’ respiratory health.

Design: A cross-sectional study of the respiratory health in two types of crab processing workers compared to a control group.

Methods: The study included 148 king crab (Paralithodes camtschaticus) workers, 70 edible crab (Cancer pagurus) workers and 215 controls. Workers answered a questionnaire and performed spirometry measurements. χ² and Fishers exact tests were performed on self-reported respiratory symptoms. Regression analyses and t-tests were used to assess lung function values.

Results: Self-reported respiratory symptoms were higher among crab processing workers compared to controls, and higher among king crab workers compared to edible crab workers. There was no significant difference between crab processing workers and controls in lung function measurements. Self-reported doctor-diagnosed asthma prevalence was highest in the control group.

Conclusions: Increased respiratory symptoms reported by crab processing workers were not reflected in impaired lung function values or asthma diagnose. We suggest a healthy worker effect among crab processing workers in Norway.

Characterization and pro-inflammatory responses of spore and hyphae samples from various mold species

Mold particles from Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum have been linked to respiratory-related diseases. We characterized X-ray-inactivated spores and hyphae fragments from these species by number of particles, morphology, and mycotoxin, β-glucan and protease content/activity. The pro-inflammatory properties of mold particles were examined in human bronchial epithelial cells (BEAS-2B) and THP-1 monocytes and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. Spores from P. chrysogenum and S. chartarum contained some hyphae fragments, whereas the other preparations contained either spores or hyphae. Each mold species produced mainly one gelatin-degrading protease that was either of the metallo- or serine type, while one remains unclassified. Mycotoxin levels were generally low. Detectable levels of β-glucans were found mainly in hyphae particle preparations. PMA-differentiated THP-1 macrophages were by far the most sensitive model with effects in the order of 10 ng/cm² . Hyphae preparations of A. fumigatus and P. chrysogenum were more potent than respective spore preparations, whereas the opposite seems to be true for A. versicolor and S. chartarum. Hyphae fragments of A. fumigatus, P. chrysogenum, and A. versicolor enhanced the release of metalloprotease (proMMP-9) most markedly. In conclusion, species, growth stage, and characteristics are all important factors for pro-inflammatory potential.

Mixed exposure to bacterial lipopolysaccharide and seafood proteases augments inflammatory signalling in an airway epithelial cell model (A549)

Seafood industry workers exhibit increased prevalence of respiratory symptoms due to exposure to bioaerosols containing a mixture of bioactive agents. In this study, a human pulmonary epithelial cell model (A549) was exposed to mixtures of bacterial lipopolysaccharide (LPS) and protease-activated receptor-2 (PAR-2) agonists H-Ser-Leu-Ile-Gly-Lys-Val-NH₂ (SLIGKV-NH₂), purified salmon ( Salmo salar) trypsin or purified king crab ( Paralithodes camtschaticus) trypsin. The inflammatory response was measured based on nuclear factor-kappa B (NF-κB) activation of transcription in a luciferase reporter gene assay and interleukin 8 (IL-8) secretion in an enzyme-linked immunosorbent assay. We observed that mixtures of SLIGKV-NH₂ or trypsins with LPS augmented the activation of NF-κB and secretion of IL-8. The effect on IL-8 secretion was synergistic when both trypsins and LPS were used in the lower concentration range. The results demonstrate that exposure to mixtures of agents that are relevant to seafood industry workplaces may lead to increased inflammatory signalling compared with exposure to the individual agents alone. Furthermore, the results indicate that synergism may occur with the combined exposure to seafood trypsins and LPS and is most likely to occur when exposure to either agent is low.

Differences in PAR-2 activating potential by king crab (Paralithodes camtschaticus), salmon (Salmo salar), and bovine (Bos taurus) trypsin

BACKGROUND

Salmon trypsin is shown to increase secretion of the pro-inflammatory cytokine interleukin (IL)-8 from human airway epithelial cells through activation of PAR-2. Secretion of IL-8 induced by king crab trypsin is observed in a different concentration range compared to salmon trypsin, and seems to be only partially related to PAR-2 activation. This report aim to identify differences in the molecular structure of king crab trypsin (Paralithodes camtschaticus) compared to salmon (Salmo salar) and bovine trypsin (Bos taurus) that might influence the ability to activate protease-activated receptor-2 (PAR-2).

RESULTS

During purification king crab trypsin displayed stronger binding capacity to the anionic column used in fast protein liquid chromatography compared to fish trypsins, and was identified as a slightly bigger molecule. Measurements of enzymatic activity yielded no obvious differences between the trypsins tested. Molecular modelling showed that king crab trypsin has a large area with strong negative electrostatic potential compared to the smaller negative areas in bovine and salmon trypsins. Bovine and salmon trypsins also displayed areas with strong positive electrostatic potential, a feature lacking in the king crab trypsin. Furthermore we have identified 3 divergent positions (Asp196, Arg244, and Tyr247) located near the substrate binding pocket of king crab trypsin that might affect the binding and cleavage of PAR-2.

CONCLUSION

These preliminary results indicate that electrostatic interactions could be of importance in binding, cleavage and subsequent activation of PAR-2.

Feeling cold at work increases the risk of symptoms from muscles, skin, and airways in seafood industry workers

BACKGROUND

Norwegian workers in seafood industry plants are exposed to a cold and often wet environment.

METHODS

1,767 seafood industry workers participated in a questionnaire study. Seventeen plants were visited for thermal measurements.

RESULTS

15.9% of industrial workers and 1.7% of administrative workers reported that they often felt cold at work. Mean finger temperatures after 1 hr work varied between 16 and 22 degrees C. Foot temperature dropped from morning measurement until lunch time in 85% of the measurements. Industrial workers who reported that they often felt cold, had significantly increased prevalence of symptoms from muscles, skin, and airways while working, compared to workers who reported that they never felt cold at work.

CONCLUSIONS

Moderate cooling, caused by a cold indoor working environment, may increase muscle-, airway-, and skin symptoms. The prevalence of feeling cold may be a useful exposure estimate in moderate cold exposure situations.

Quartz exposure in the slate industry in northern Norway

In this study we have measured exposure levels to quartz in different parts of the slate industry in Alta, Northern Norway. Full shift personal samples were collected from the breathing zones of outdoor and indoor workers in the slate quarries and a slate factory. The quartz content of respirable dust was between 7 and 41%. The slate factory had the lower quartz levels although 41% of total and 73% of respirable samples were above the Norwegian TLV for quartz. The average concentration of total quartz in the slate factory was 0.27 mg/m3 and the average concentration of respirable quartz was 0.12 mg/m3. Outdoor in the quarries the average levels of quartz were 0.58 and 0.13 mg/m3 for total and respirable quartz, respectively. From the beginning of the last decade most of the quarry-workers have built quarry halls to protect themselves against a cold winter climate. Inside in these quarry halls the average levels were 1.74 mg/m3 total quartz and 0.46 mg/m3 respirable quartz. Assessment of historical exposure showed that 32 of totally 45 quarry workers with available exposure history had a lifetime inhaled quartz dose of more than 10 g. There is reason to fear that silicosis will be an increasing problem among quarry workers if efforts to reduce quartz exposure are not put into effect.

Effects of cAMP and cGMP elevating agents on HL-60 cell differentiation

Previous studies have demonstrated low percentage of HL-60 cell differentiation with theophylline. The present study demonstrate that millimolar concentrations of the non-selective phosphodiesterase inhibitors theophylline, caffeine and isobutyl-methylxanthine all inhibit growth, induce substantial differentiation and elevation of both cAMP and cGMP in HL-60 cells. Selective inhibition of cAMP hydrolysis by Ro20-1724 was without effect. The guanylate cyclase stimulator sodium nitroprusside, which increased cGMP only poorly and also increased cAMP, produced growth inhibition but no differentiation. We put forward the hypothesis that elevation of both cAMP and cGMP above a critical level is necessary for significant cyclic nucleotide induced HL-60 cell differentiation.

Epinephrine induces beta-adrenergic desensitization and differentiation of HL-60 cells

The HL-60 cell line was cultured in a serum-free medium and exposed to various concentrations of EPI. The effects on cell growth, differentiation and beta-adrenergic response were followed during the culture period of 72 h. Short-term exposure (3 min) to EPI (1 nM-1 mM) in the presence of theophylline (4 mM) caused a dose-dependent increase of cAMP levels with a maximum of 1500% above basal levels. When the cells were exposed to EPI (1 nM-10 microM) for 72 h, a dose-dependent increase of cAMP levels with a maximum of 60% above basal levels. Sustained exposure to EPI generated a dose-dependent desensitization of the beta-adrenergic signal system. After EPI treatment for 72 h, IPR (10 microM for 3 min) in the presence of theophylline (4 mM) increased cAMP-levels by only 80% above baseline level (cAMP levels after maintained exposure to EPI), compared to 1080% above unstimulated level in control cells. The alpha-adrenergic receptor blocker PHENT (10 microM) did not affect baseline cAMP level or IPR-dependent cAMP response, but a mixture of EPI and PHENT increased the response to IPR. The HL-60 cell growth was not influenced by EPI. However, after repeated exposure to EPI for 72 h a concentration-dependent increase of HL-60 differentiation was demonstrated. Differentiation was not influenced by PHENT. These results suggest a differentiation induction due to a beta-adrenergic-induced cAMP elevation.

Elevation of cyclic AMP levels in HL-60 cells accumulated in G1 or G2 by transmethylation inhibitors

Effects of the transmethylation inhibitors 3-deazaadenosine (c3Ado) and 3-deaza-(+/-)-aristeromycin (c3Ari) on cell cycle and cyclic AMP (cAMP) concentrations in human promyelocytic leukemia cells (HL-60) were studied by flow cytometry and radioimmunoassay techniques. Previously described cell cycle accumulations, after incubation with drugs (25 microM) for two cell doublings (36 hr), were localized to G1 and G2 after incubation with c3Ado and c3Ari, respectively. cAMP levels were elevated in cells treated with c3Ado (35%) and c3Ari (92%) for 36 hr. Addition of the phosphodiesterase (PDE) inhibitor theophylline, increased cAMP levels further, while cAMP responsiveness to the beta-adrenergic stimulator isoproterenol was attenuated after c3Ado and c3Ari incubation. Homocysteine thiolactone (Hcy) alone reduced cell growth slightly (5%) and increased cAMP levels (17%). Hcy increased the growth inhibitory effects of c3Ado, while no modulating effect was seen in combination with c3Ari, nor did Hcy counteract the effects on the cell cycle perturbations. The results suggest that c3Ado- and c3Ari-induced cell cycle accumulation is, at least in part, mediated through cAMP elevation, possibly due to PDE inhibition secondary to S-adenosyl-homocysteine hydrolase inhibition and S-adenosyl-homocysteine build-up.

Physiological cyclic AMP stimulation and oncogene mRNA levels in HL-60 cells

Altered gene expression of the proto-oncogenes c-fos and c-myc is associated with differentiation of the human promyelocytic leukemia (HL-60) cells. We studied changes of cyclic AMP levels and c-fos and c-myc mRNA levels after stimulation with theophylline and theophylline plus isoproterenol. Reduced c-fos and c-myc mRNA levels were detected, but the reduction could not, however, be related to the observed alternations in cyclic AMP concentrations. Expression of c-jun and c-Ha-ras was not affected under these conditions.

Growth, differentiation and the beta-adrenergic signal system of HL-60 cells. Characterization in a medium with insulin as the only added protein

The purpose of the present investigation was to define experimental conditions for studies on growth, differentiation and the beta-adrenergic signal system of HL-60 cells. The cell medium was completely devoid of added proteins and hormones other than insulin. The HL-60 cell was able to grow and differentiate in this medium. The spontaneous differentiation along the granulocytic pathway after 72 hr, as assessed by the Nitro Blue tetrazolium test, increased by 400% compared to the serum supplemented medium, but the response to 1 microM retinoic acid was equal in the two media. Induction of monocytic differentiation by 0.16 microM phorbol-13-acetate-12-myristate, as determined by surface adherence after 24 hr, was lower in the absence than in the presence of serum. cAMP levels were elevated in response to (-)-isoproterenol. The EC50 was 0.36 +/- 0.01 microM (mean +/- SE, N = 3). The beta-adrenergic ligand 3H-CGP 12177 was specifically bound to 1 single class of binding sites (Kd: 0.15 +/- 0.04 nM, Bmax: 2220 +/- 150, mean +/- SE, N = 3). These data are comparable to our previously reported findings in serum supplemented medium. The present data show that HL-60 cells are able to grow and differentiate in the absence of serum proteins and hormones other than insulin. Under the present experimental conditions, these cells possessed functional beta-adrenergic receptors.

The human promyelocytic leukemia cell (HL-60 cell) beta-adrenergic receptor

We have characterized the beta-adrenergic receptor binding site and the beta-adrenergic cAMP response of the HL-60 cell. The hydrophilic ligand [3H]-(-)-CGP-12177 was specifically and reversibly bound to one single class of binding sites (Kd 220 pM and Bmax 1,970 sites/cell). The adrenergic agonists inhibited the specific radioligand binding. The order of potency was isoproterenol greater than epinephrine greater than norepinephrine. The beta-2 selective antagonist ICI 118551 had a binding affinity 3 orders of potency higher than the beta-1 selective antagonist, atenolol. The adrenergic agonists elevated the cAMP accumulation in a concentration-dependent mode. The order of potency was isoproterenol greater than epinephrine greater than norepinephrine. Both the binding and the functional studies revealed stereospecificity and reversibility. The present data show that HL-60 cells possess beta-2 adrenergic receptors functionally coupled to adenylate cyclase.