Pulmonary disease in workers exposed to papain: clinico-physiological and immunological studies

Plant and Arthropod IgE-Binding Papain-like Cysteine Proteases: Multiple Contributions to Allergenicity

Papain-like cysteine proteases are widespread and can be detected in all domains of life. They share structural and enzymatic properties with the group's namesake member, papain. They show a broad range of protein substrates and are involved in several biological processes. These proteases are widely exploited for food, pharmaceutical, chemical and cosmetic biotechnological applications. However, some of them are known to cause allergic reactions. In this context, the objective of this review is to report an overview of some general properties of papain-like cysteine proteases and to highlight their contributions to allergy reactions observed in humans. For instance, the literature shows that their proteolytic activity can cause an increase in tissue permeability, which favours the crossing of allergens through the skin, intestinal and respiratory barriers. The observation that allergy to PLCPs is mostly detected for inhaled proteins is in line with the reports describing mite homologs, such as Der p 1 and Der f 1, as major allergens showing a frequent correlation between sensitisation and clinical allergic reactions. In contrast, the plant food homologs are often digested in the gastrointestinal tract. Therefore, they only rarely can cause allergic reactions in humans. Accordingly, they are reported mainly as a cause of occupational diseases.

Comparative Analysis of the Immune Response and the Clinical Allergic Reaction to Papain-like Cysteine Proteases from Fig, Kiwifruit, Papaya, Pineapple and Mites in an Italian Population

Several plant papain-like cysteine proteases are exploited by the food, cosmetic, pharmaceutical and textile industries. However, some of these enzymes can cause allergic reactions. In this context, we investigated the frequency of sensitization and allergic reactions to some fruit and/or latex cysteine proteases, which are used as additives by the food industry to improve and modify the quality of their products. The FABER test was used to analyse the patients' sensitization towards five plants and, for comparison, two homologous mite cysteine proteases. In an Italian population of 341 allergic patients, 133 (39%) had IgE specific for at least one of the seven cysteine proteases under investigation. Most of the patients were IgE positive for Der p 1 and/or Der f 1 (96.38%) reported a clinical history suggestive of respiratory allergy to mites, whereas none of the subjects sensitized to the homologs from papaya, pineapple and fig reported allergy symptoms following ingestion of these foods. Only one patient referred symptoms from ingesting kiwifruit. Therefore, the obtained results showed that sensitization to the fruit enzymes was only rarely concomitant with allergic reactions. These observations, together with the literature reports, suggest that the allergy to plant papain-like cysteine proteases might mainly be an occupational disease.

Papain Induced Occupational Asthma with Kiwi and Fig Allergy

Papain is a proteolytic enzyme which is widely used in food industry, pharmaceuticals, and cosmetics. Occupational and non-occupational papain allergies have previously been documented; however, there are limited publications about papain allergy with its relative fruit allergy. Here, we present a case of occupational, IgE-mediated papain allergy with kiwi fruit and fig fruit allergy. A 53-year-old man suffered from rhinitis for several years, with the onset of his symptoms coinciding with the time he started to work at a sausage processing plant where papain is often used as a meat tenderizer. He began to experience symptoms of chest tightness, shortness of breath and wheezing shortly after starting work 5 years ago. Furthermore, he experienced several episodes of oral itching, and tongue and oropharyngeal angioedema after injestion of kiwi fruit and fig fruit. The patient had a lifelong history of allergic conjunctivitis, allergic rhinitis, and childhood asthma. Specific IgE was positive to kiwi fruit, papain and chymopapain (2.95 kUA/L, >100 kUA/L, and 95.0 kUA/L, respectively). Similar bands at 10-15 kDa in blotting with papain and kiwi fruit extracts were found. This patient showed a potential association between papain allergy and sensitization to kiwi fruit. We also reviewed 13 patients with papain allergy published in the literature, with 85% (11/13) of the patients sensitized through the respiratory tract, and 40% (4/11) having atopy. Further studies should focus on the determination of cross-reactive allergens between papain and its fruit relatives, and the prevalence of food allergy in patients with papain allergy should be investigated in a relatively large cohort.

Proteinases as molecular adjuvants in allergic airway disease

BACKGROUND

Asthma and related respiratory tract allergic diseases are among the most common chronic diseases of adults and children. Despite their importance, disease course cannot be predicted and treatment remains non-specific and potentially hazardous, with no means for cure. Improved clinical management of asthma will require an improved understanding of the fundamental factors that initiate allergic inflammation, especially T helper type 2 (T(H)2) cell induction.

SCOPE OF REVIEW

In this review, we explore the Proteinase Hypothesis of allergic airway disease, considering specifically how organismal proteinases contribute to the expression of allergic disease and potentially important proteinase signaling pathways.

MAJOR CONCLUSIONS

Proteinases from diverse sources (bacteria, fungi, plants) may cause occupational asthma by acting as immune adjuvant factors that specifically elicit T(H)2 cell-dependent allergic inflammation. However, more conventional allergic airway diseases (asthma, allergic sinusitis) are more likely to arise from contained fungal or viral infections of the airway in which proteinases are produced and serve as major virulence factors. Proteinases may elicit allergic disease by disrupting numerous cellular proteins, potentially including Toll like receptor (TLR) 4, but critical proteinase-activated signaling pathways remain largely unknown.

GENERAL SIGNIFICANCE

Clarification of how proteinases cause allergic disease, specifically confirming an infectious basis for airway proteinase exposure, will likely radically advance how asthma and related respiratory tract disorders are diagnosed and treated. This article is part of a Special Issue entitled Biochemistry of Asthma.

[Occupational rhinitis]

INTRODUCTION

Rhinitis is one of the most common occupational diseases. It is often neglected by those affected because it causes little disability. It is poorly understood by doctors who have insufficient experience of occupational diseases and their causes. However it is often the first manifestation of a respiratory disorder that may cause physical complications and socio-economic disability.

BACKGROUND

Numerous diverse agents are potential causes of rhinitis. The diagnosis of occupational rhinitis should be considered when sneezing, rhinorrhoea or nasal obstruction are associated with work. The causal agent can be identified by ta-king a careful history. When the mechanism of the disease is immunologic the suspected antigen can be confirmed by skin testing, specific IgE or nasal provocation. The respiratory disorder of which rhinitis is the first manifestation may progress to asthma if the exposure continues. The prevention of occupational rhinitis depends on the reduction of exposure to allergens and/or irritants. When it has developed removal of the causative agent is essential to prevent progression to asthma.

Personal Dust Exposures at a Food Processing Facility

A field study was performed to quantify personal dust exposures at a food processing facility. A review of the literature shows very little exposure information in the food processing industry. The processing area consisted of a series of four rooms, connected by a closed-loop ventilation system, housed within a larger warehouse-type facility. Workers were exposed to various fruit and vegetable dusts during the grinding, sieving, mixing and packaging of freeze-dried or air-dried products. Eight two-hour periods were monitored over two days. Personal total suspended particulate samples were collected on 37 mm PVC filters with 5 microm pore size according to National Institute for Occupational Safety and Health (NIOSH) Method 0500. The filters were analyzed gravimetrically. The two-hour task sampling personal dust exposures ranged from 0.33-103 mg/m3. For each worker, an eight-hour time weighted average (TWA) concentration was calculated, and these ranged from 3.08-59.8 mg/m3. Although there are no directly appropriate occupational exposure limits that may be used for comparison, we selected the Threshold Limit Value (TLV) for particulates not otherwise classified (PNOC) of 10 mg/m3 for inhalable particles. Neglecting the respiratory protection used, five out of eight of the worker time-weighted averages exceeded the TLV. It should be noted that the TLV is based on the inhalable fraction and in this study total suspended particulate was measured; additionally, the TLV is applicable for dusts that are insoluble or poorly soluble, and have low toxicity, which may have limited protective ability in this case due to the irritant nature of certain dusts (e.g., jalapeno peppers, aloe vera). Sieving resulted in significantly higher exposure than grinding and blending. Measuring area concentrations alone in this environment is not a sufficient method of estimating personal exposures due to work practices for some operations.

Suggestions for the Assessment of the Allergenic Potential of Genetically Modified Organisms

The prevalence of allergic diseases has been increasing continuously and, accordingly, there is a great desire to evaluate the allergenic potential of components in our daily environment (e.g., food). Although there is almost no scientific evidence that genetically modified organisms (GMOs) exhibit increased allergenicity compared with the corresponding wild type significant concerns have been raised regarding this matter. In principle, it is possible that the allergenic potential of GMOs may be increased due to the introduction of potential foreign allergens, to potentially upregulated expression of allergenic components caused by the modification of the wild type organism or to different means of exposure. According to the current practice, the proteins to be introduced into a GMO are evaluated for their physiochemical properties, sequence homology with known allergens and occasionally regarding their allergenic activity. We discuss why these current rules and procedures cannot predict or exclude the allergenicity of a given GMO with certainty. As an alternative we suggest to improve the current evaluation by an experimental comparison of the wild-type organism with the whole GMO regarding their potential to elicit reactions in allergic individuals and to induce de novo sensitizations. We also recommend that the suggested assessment procedures be equally applied to GMOs as well as to natural cultivars in order to establish effective measures for allergy prevention.

Respiratory findings in pharmaceutical workers

BACKGROUND

Pharmaceutical workers may be at risk for the development of respiratory problems as a result of their work environment.

METHODS

This study investigated 163 female and 35 male workers, employed in a pharmaceutical plant processing different types of medication, primarily antibiotics, in order to characterize the risk of this environment. Chronic respiratory symptoms were recorded by using the British Medical Research Council questionnaire. Acute symptoms, which developed during the work shift, were also recorded. Ventilatory capacity was measured by recording maximum expiratory flow-volume (MEFV) curves on which FVC, FEV1, FEF50, and FEF25 were measured. Controls (113) were selected from a food packing facility.

RESULTS

A significantly higher prevalence of chronic respiratory symptoms was recorded among workers (compared to controls), the highest being for sinusitis, nasal catarrh, and dyspnea. There was also a high prevalence of acute symptoms recorded during the workshift. Odds ratio showed that the most significant risk factors for these respiratory findings were smoking and length of time worked in the pharmaceutical industry, particularly in men. Pulmonary function testing demonstrated significantly decreased measured values in comparison to predicted European pulmonary function measurements (P < 0.01). This was particularly pronounced for FEF50 and FEF25, suggesting obstructive changes in smaller airways.

CONCLUSIONS

Our data suggest that workers employed in the pharmaceutical industry may develop respiratory symptoms accompanied by ventilatory impairment.

Multiple IgE-mediated sensitizations to enzymes after occupational exposure: evaluation by skin prick test, RAST, and immunoblot

We investigated 10 sensitized and 10 nonsensitized workers from a pharmaceutic factory who had been exposed to powdered trypsin, chymotrypsin, bromelain, papain, amylase, and lipase. Ten nonallergic subjects served as a control group. Titrated skin prick tests (SPT), RAST, and immunoblot studies were performed with all six enzymes. SPT reactivity revealed multiple sensitizations to proteolytic enzymes, i.e., papain (specifically sensitized/total number of sensitizations: 9/10), trypsin (8/10), chymotrypsin (8/10), and bromelain (7/10) and appeared to be more frequent and more pronounced than sensitizations to amylase (3/10) or lipase (3/10). The low molecular weight of proteolytic enzymes (20-30 kDa) and their biologic activity might facilitate mucosal penetration more easily and thus-compared to amylase and lipase-permit an immune response and induction of allergic hypersensitivity. Immunoblot studies demonstrated IgG-binding bands in both SPT-positive and -negative workers, indicating exposure to the enzymes, but not in 10 unexposed control subjects. IgE-binding bands of the enzymes were detected only in workers with a positive SPT reaction and/or a positive RAST result. IgG bands were more frequent and the IgG/IgE ratio was increased in workers without allergic complaints compared to symptomatic workers. This might indicate that high levels of specific IgG antibodies to enzymes are associated with an immune response lacking allergic manifestations in spite of IgE-mediated sensitizations to the enzymes. Atopic subjects were at greater risk of developing IgE-mediated sensitization (7/10) and allergic symptoms to enzymes (5/7). However, even without risk of atopy, IgE-mediated hypersensitivity occurred in a few subjects (3/13) exposed to enzymes by inhalation for prolonged periods of time.

Association of IgE antibodies to sodium aurothiomalate and adverse reactions to chrysotherapy for rheumatoid arthritis

The relationship between adverse reactions to chrysotherapy and specific IgE antibodies to sodium aurothiomalate (auIgE) was studied in 67 patients with rheumatoid arthritis (62) or psoriatic arthritis (5). Thirty patients (45 percent) had such antibodies versus none of the 27 control patients. Of the 34 patients in whom reactions to chrysotherapy developed, 23 (68 percent) had auIgE versus 7 (21 percent) without reactions (p less than 0.001). Mucocutaneous lesions were significantly associated with auIgE (p less than 0.001). All five patients with thrombocytopenia, but only one of five with the nephrotic syndrome, had auIgE. The patients with IgE response had higher total serum IgE levels (p less than 0.005), were more likely to be atopic (four to one), and had more recently received chrysotherapy (mean 2.8 +/- 1.95 years versus 7.0 +/- 5.75 years, p less than 0.001) than those without response, but did not differ by either the gold product or the total dose used. Chrysotherapy is associated with the production of specific IgE antibodies to a gold salt, and some mucocutaneous and hematologic reactions may be immunologically mediated.

Clinical symptoms and results of skin test, RAST and bronchial provocation test in thirty-three papain workers: evidence for strong immunogenic potency and clinically relevant 'proteolytic effects of airborne papain'

Seventeen out of thirty-three workers who have been exposed to airborne papain at their place of work regularly developed asthmatic symptoms such as shortness of breath, wheezing, coughing, sneezing, rhinorrhea and conjunctival irritation upon contact with this proteolytic enzyme. Investigations by RAST, skin test and bronchial provocation test proved IgE-mediated hypersensitivity to papain in fourteen symptomatic workers. Ten of these were in a screening investigation involving twenty-nine of the thirty-three workers; i.e. the incidence of IgE-mediated sensitization was 34.5% of this group. Bronchial provocation of as little as 0.001--0.5 mg of papain was shown to elicit immediate or dual asthmatic reactions in all eight tested workers with RAST values greater than 3 u/ml. On the other hand, inhalation of 0.5 mg of papain did not cause any remarkable change in non-exposed asthmatics. Occupation-related blood-stained nasal secretions and/or cutaneous flare reactions in all four heavily-exposed papain workers, of whom three had negative skin test and RAST results, suggest a direct effect of the proteolytically active enzyme on human tissue. There was a significant elevation (P less than 0.001) of serum trypsin inhibitory capacity in papain workers which seems to depend on the degree of exposure. No significant differences between symptomatic and asymptomatic workers in alpha 1-antitrypsin (Pi) phenotype subtypes were found.