Mushroom worker's lung caused by spores of Hypsizigus marmoreus (Bunashimeji): elevated serum surfactant protein D levels

A case of bunashimeji mushroom‐induced hypersensitivity pneumonitis diagnosed by inhalational provocation test in a hospital room

A 66‐year‐old woman was admitted to our hospital with a 2‐month history of dry cough and exertional dyspnea. She had worked as a mushroom farmer and had been exposed to mushroom for more than 40 years. The patient showed elevated levels of KL‐6 (2966 U/mL) and surfactant protein D (410 ng/mL), and computed tomography of the chest revealed ground‐glass opacities and fine nodular shadows in both lungs, suggesting mushroom‐induced hypersensitivity pneumonitis. Pulmonary function testing revealed decreases in forced vital capacity (78% of predicted) and carbon monoxide diffusing capacity (67% of predicted). The inhalational provocation test was positive for bunashimeji mushrooms. Precipitating antibody was only identified for spores or bodies of bunashimeji mushrooms, and lymphocyte stimulation testing with spores or bodies of bunashimeji mushrooms also yielded positive results. Bunashimeji mushroom‐induced hypersensitivity pneumonitis was therefore diagnosed. Radiological findings and pulmonary function were improved by corticosteroid therapy and the patient has since remained healthy with allergen avoidance.

Diagnosis of Fibrotic Hypersensitivity Pneumonitis: Is There a Role for Biomarkers?

Hypersensitivity pneumonitis is a complex interstitial lung syndrome and is associated with significant morbimortality, particularly for fibrotic disease. This condition is characterized by sensitization to a specific antigen, whose early identification is associated with improved outcomes. Biomarkers measure objectively biologic processes and may support clinical decisions. These tools evolved to play a crucial role in the diagnosis and management of a wide range of human diseases. This is not the case, however, with hypersensitivity pneumonitis, where there is still great room for research in the path to find consensual diagnostic biomarkers. Gaps in the current evidence include lack of validation, validation against healthy controls alone, small sampling and heterogeneity in diagnostic and classification criteria. Furthermore, discriminatory accuracy is currently limited by overlapping mechanisms of inflammation, damage and fibrogenesis between ILDs. Still, biomarkers such as BAL lymphocyte counts and specific serum IgGs made their way into clinical guidelines, while others including KL-6, SP-D, YKL-40 and apolipoproteins have shown promising results in leading centers and have potential to translate into daily practice. As research proceeds, it is expected that the emergence of novel categories of biomarkers will offer new and thriving tools that could complement those currently available.

Transcription Factor HSF1 Suppresses the Expression of Surfactant Protein D in Cells Infected with Aspergillus fumigatus

Aspergillosis is a life-threatening disease in patients with compromised immune systems. The process of fungal invasion is an important step during host cell infection. We investigated the transcription factor and promoter region of SFTPD, which is activated during the infection process in conidia-treated cells. To investigate the promoter activity of SFTPD in fungal-infected cells, we cloned various lengths of the promoter region (−1000 to +1) of SFTPD and examined its activity in A549 cells treated with Aspergillus fumigatus conidia. We determined the location within the promoter region of SFTPD that exhibits a response to conidia infection. AliBaba 2.1 software was used to predict the transcription factor involved as well as the binding sites in the SFTPD promoter region. The results of a decoy assay show that the HSF1 transcription factor is sufficient to decrease the SFTPD expression. Using chromatin immunoprecipitation, we confirmed that HSF1 directly binds to the selected sequence, which is located in the response region (−142 to −134 bp). These findings suggest that inhibiting the binding of HSF1 to the promoter region of SFTPD is an important step to prevent conidia infection.

Exposure assessment in hypersensitivity pneumonitis: a comprehensive review and proposed screening questionnaire

Hypersensitivity pneumonitis is an immune-mediated inflammatory lung disease characterised by the inhalation of environmental antigens leading to acute and chronic lung injury. Along with suggestive clinical and radiological findings, history and timing of suspected antigen exposure are important elements for diagnostic confidence. Unfortunately, many diagnoses remain tentative and based on vague and imprecise environmental or material exposure histories. To date, there has not been a comprehensive report highlighting the frequency and type of environmental exposure that might lead to or support a more systematic approach to antigen identification. We performed a comprehensive literature review to identify and classify causative antigens and their associated environmental contexts or source materials, with emphasis on the extent of the supportive literature for each exposure type. Eligible publications were those that reported unique inciting antigens and their respective environments or contexts. A clinical questionnaire was then proposed based on this review to better support diagnosis of hypersensitivity pneumonitis when antigen testing or other clinical and radiological variables are inconclusive or incomplete.

Surfactant Protein D in Respiratory and Non-Respiratory Diseases

Surfactant protein D (SP-D) is a multimeric collectin that is involved in innate immune defense and expressed in pulmonary, as well as non-pulmonary, epithelia. SP-D exerts antimicrobial effects and dampens inflammation through direct microbial interactions and modulation of host cell responses via a series of cellular receptors. However, low protein concentrations, genetic variation, biochemical modification, and proteolytic breakdown can induce decomposition of multimeric SP-D into low-molecular weight forms, which may induce pro-inflammatory SP-D signaling. Multimeric SP-D can decompose into trimeric SP-D, and this process, and total SP-D levels, are partly determined by variation within the SP-D gene, SFTPD. SP-D has been implicated in the development of respiratory diseases including respiratory distress syndrome, bronchopulmonary dysplasia, allergic asthma, and chronic obstructive pulmonary disease. Disease-induced breakdown or modifications of SP-D facilitate its systemic leakage from the lung, and circulatory SP-D is a promising biomarker for lung injury. Moreover, studies in preclinical animal models have demonstrated that local pulmonary treatment with recombinant SP-D is beneficial in these diseases. In recent years, SP-D has been shown to exert antimicrobial and anti-inflammatory effects in various non-pulmonary organs and to have effects on lipid metabolism and pro-inflammatory effects in vessel walls, which enhance the risk of atherosclerosis. A common SFTPD polymorphism is associated with atherosclerosis and diabetes, and SP-D has been associated with metabolic disorders because of its effects in the endothelium and adipocytes and its obesity-dampening properties. This review summarizes and discusses the reported genetic associations of SP-D with disease and the clinical utility of circulating SP-D for respiratory disease prognosis. Moreover, basic research on the mechanistic links between SP-D and respiratory, cardiovascular, and metabolic diseases is summarized. Perspectives on the development of SP-D therapy are addressed.

Construction of a genetic linkage map based on amplified fragment length polymorphism markers and development of sequence-tagged site markers for marker-assisted selection of the sporeless trait in the oyster mushroom (Pleurotus eryngii)

A large number of spores from fruiting bodies can lead to allergic reactions and other problems during the cultivation of edible mushrooms, including Pleurotus eryngii (DC.) Quél. A cultivar harboring a sporulation-deficient (sporeless) mutation would be useful for preventing these problems, but traditional breeding requires extensive time and labor. In this study, using a sporeless P. eryngii strain, we constructed a genetic linkage map to introduce a molecular breeding program like marker-assisted selection. Based on the segregation of 294 amplified fragment length polymorphism markers, two mating type factors, and the sporeless trait, the linkage map consisted of 11 linkage groups with a total length of 837.2 centimorgans (cM). The gene region responsible for the sporeless trait was located in linkage group IX with 32 amplified fragment length polymorphism markers and the B mating type factor. We also identified eight markers closely linked (within 1.2 cM) to the sporeless locus using bulked-segregant analysis-based amplified fragment length polymorphism. One such amplified fragment length polymorphism marker was converted into two sequence-tagged site markers, SD488-I and SD488-II. Using 14 wild isolates, sequence-tagged site analysis indicated the potential usefulness of the combination of two sequence-tagged site markers in cross-breeding of the sporeless strain. It also suggested that a map constructed for P. eryngii has adequate accuracy for marker-assisted selection.

Hypersensitivity pneumonitis caused by Penicillium citrinum, not Enoki spores

BACKGROUND

Flammulina velutipes is called the Enoki mushroom in Japanese and is cultivated indoors. Mushroom workers face occupational exposure to a tremendous number of fungi and organic antigens capable of causing hypersensitivity pneumonitis (HP). One worker employed at an Enoki farm developed HP due to Penicillium citrinum. This study investigated new cases of HP among the workers cultivating Enoki.

METHODS

Serum Krebs von der Lungen-6 (KL-6), surfactant protein (SP)-A and SP-D were measured. Lymphocyte stimulation tests (LST) and double immunodiffusion tests (DIT) were performed to identify P. citrinum. Workers showing high levels of KL-6, SP-A, or SP-D and a high LST value or positive DIT were identified and then were further examined by chest computed tomography, bronchoalveolar lavage and transbronchial lung biopsy. The initial patient and new HP patients were defined as the HP group and the other participants were defined as the non-HP group.

RESULTS

Forty-eight Enoki workers participated in the study. Four of nine workers who met the criteria for further examinations were diagnosed as having HP due to P. citrinum. In comparison between non-HP group and HP group, KL-6, SP-D and LST values were significantly higher in HP group. There was a strong correlation between KL-6 and SP-D. DIT had high sensitivity and high specificity.

CONCLUSIONS

KL-6, SP-D, LST, and DIT were useful for detecting HP patients. KL-6 was the most useful predictor of HP in this study. DIT was useful not only as a predictor of HP but also as a detector of the causative antigen.

Mushroom worker's lung: organic dust exposure in the spawning shed

Two people employed for several years in the spawning shed of a mushroom farm developed mushroom worker's lung. The first patient presented in respiratory failure, with radiological features characteristic of hypersensitivity pneumonitis. The condition of the second patient was subacute on presentation, with a computed tomography (CT) scan showing ground-glass opacities. With absence from the workplace and no steroid therapy, the symptoms of both patients subsided and the results of lung function tests and CT scans improved markedly.

Surfactant protein A and surfactant protein D variation in pulmonary disease

Surfactant proteins A (SP-A) and D (SP-D) have been implicated in pulmonary innate immunity. The proteins are host defense lectins, belonging to the collectin family which also includes mannan-binding lectin (MBL). SP-A and SP-D are pattern-recognition molecules with the lectin domains binding preferentially to sugars on a broad spectrum of pathogen surfaces and thereby facilitating immune functions including viral neutralization, clearance of bacteria, fungi and apoptotic and necrotic cells, modulation of allergic reactions, and resolution of inflammation. SP-A and SP-D can interact with receptor molecules present on immune cells leading to enhanced microbial clearance and modulation of inflammation. SP-A and SP-D also modulate the functions of cells of the adaptive immune system including dendritic cells and T cells. Studies on SP-A and SP-D polymorphisms and protein levels in bronchoalveolar lavage and blood have indicated associations with a multitude of pulmonary inflammatory diseases. In addition, accumulating evidence in mouse models of infection and inflammation indicates that recombinant forms of the surfactant proteins are biologically active in vivo and may have therapeutic potential in controlling pulmonary inflammatory disease. The presence of the surfactant collectins, especially SP-D, in non-pulmonary tissues, such as the gastrointestinal tract and genital organs, suggest additional actions located to other mucosal surfaces. The aim of this review is to summarize studies on genetic polymorphisms, structural variants, and serum levels of human SP-A and SP-D and their associations with human pulmonary disease.

Susceptibility of mice genetically deficient in the surfactant protein (SP)-A or SP-D gene to pulmonary hypersensitivity induced by antigens and allergens of Aspergillus fumigatus

Lung surfactant protein A (SP-A) and D (SP-D) are innate immune molecules which are known to interact with allergens and immune cells and modulate cytokine and chemokine profiles during host hypersensitivity response. We have previously shown therapeutic effects of SP-A and SP-D using a murine model of lung hypersensitivity to Aspergillus fumigatus (Afu) allergens. In this study, we have examined the susceptibility of SP-A (AKO) or SP-D gene-deficient (DKO) mice to the Afu allergen challenge, as compared with the wild-type mice. Both AKO and DKO mice exhibited intrinsic hypereosinophilia and several-fold increase in levels of IL-5 and IL-13, and lowering of IFN-gamma to IL-4 ratio in the lungs, suggesting a Th2 bias of immune response. This Th2 bias was reversible by treating AKO or DKO mice with SP-A or SP-D, respectively. The AKO and DKO mice showed distinct immune responses to Afu sensitization. DKO mice were found more susceptible than wild-type mice to pulmonary hypersensitivity induced by Afu allergens. AKO mice were found to be nearly resistant to Afu sensitization. Intranasal treatment with SP-D or rhSP-D (a recombinant fragment of human SP-D containing trimeric C-type lectin domains) was effective in rescuing the Afu-sensitized DKO mice, while SP-A-treated Afu-sensitized AKO mice showed several-fold elevated levels of IL-13 and IL-5, resulting in increased pulmonary eosinophilia and damaged lung tissue. These data reaffirm an important role for SP-A and SP-D in offering resistance to pulmonary allergenic challenge.

Hypersensitivity Pneumonitis due to Bunashimeji Mushrooms in the Mushroom Industry

BACKGROUND

Detection of hypersensitivity pneumonitis (HP) in employees involved in the Bunashimeji mushroom industry is difficult. The level of precipitating antibody is not related with the prediction of progression and resolution of HP. The aims of this study were to examine the actual prevalence of HP in the Bunashimeji industry and the clinical differences among selected employees.

METHODS

One hundred and fourteen employees worked in Bunashimeji enterprises. These subjects were divided into the following subgroups: office workers, pickers/packers with mask and pickers/packers without mask. We measured serum Krebs von der Lungen-6 (KL-6), surfactant protein (SP)-A and SP-D, and examined the stimulation index (SI) due to Bunashimeji spores. Chest high-resolution computed tomography (HRCT), pulmonary function tests and bronchoalveolar lavage (BAL) were performed for select employees who showed positive SI values (>200%) to examine the clinical differences.

RESULTS

The proportion of respiratory symptoms was significantly higher in the pickers/packers than that in the office workers. The picker/packer group had high serum KL-6 concentrations and SI compared with the office worker group. Thirty select employees were divided into the following three subgroups: HP, select employees without HP, and SI <400% and KL-6 <500 U/ml , using high SI levels (>400%) and positive serum KL-6 concentration (>500 U/ml). Four exhibited ground glass opacities with centrilobular fine nodules on HRCT, and 8 had high numbers of lymphocytes in the BAL fluid. The BAL findings and serum KL-6 concentrations showed significant differences among the three groups.

CONCLUSIONS

Four employees were evaluated as having HP. Serum KL-6 and SP-D may be related to the resolution of HP in addition to SI and chest HRCT.

HLA class II DPB1, DQA1, DQB1, and DRB1 genotypic associations with occupational allergic cough to Bunashimeji mushroom

We previously reported that two-third of workers in a Bunashimeji mushroom (Hypsizigus marmoreus) farm complained of respiratory allergic symptoms, but one-third workers did not suffer from such symptoms even when working for a long period. CD4+ T-helper (Th) cells increased, and Th2/Th1 ratio increased in the allergic workers. To address these immunological backgrounds, we have investigated whether there is any relationship between mushroom allergy and human leukocyte antigen (HLA) class II alleles of DPB1, DQA1, DQB1, and DRB1 by using the polymerase chain reaction-restriction fragment length polymorphism (RFLP) and sequencing-based typing methods. We observed that the allele frequencies of DQA1*0103, DQB1*0601, and DRB1*0803 were significantly higher in the workers having no allergic symptoms than allergic workers (DQA1*0103: 57 vs 25%, DQB1*0601: 49 vs 14%, and DRB1*0803: 29 vs 0%). However, this phenomenon was not seen in workers producing another kind of mushroom, Honshimeji (Lyophyllum aggregatum). The HLA-DRB1*0803 allele alone, the DRB1*0803, DQA1*0103, DQB1*0601 haplotype, or both were negatively associated with allergy to Bunashimeji, and these alleles might be involved in the prevention of Bunashimeji mushroom-specific respiratory allergy.

Hypersensitivity Pneumonitis Associated with Mushroom Worker’s Lung: An Update on the Clinical Significance of the Importation of Exotic Mushroom Varieties

Hypersensitivity pneumonitis remains an important industrial disease in mushroom workers. It has a significant morbidity, and early diagnosis and removal from exposure to the antigen are critically important in its management. Recently, several new allergens have been described, particularly those from mushroom species originating in the Far East, which are of clinical significance to workers occupationally exposed to such allergens in cultivation, picking, and packing of commercial mushroom crops. Importing of exotic mushrooms including Shiitake is common in EU countries, and some of the exotic species of mushrooms are cultivated for local markets. This practice may contribute to an increase in clinical cases of mushroom hypersensitivity pneumonitis. This update reviews the recent literature and examines changing trends of mushroom worker's lung, with increased movement of commercial product and labour markets worldwide.

Successful treatment of hypersensitivity pneumonitis caused by Grifola frondosa (Maitake) mushroom using a HFA-BDP extra-fine aerosol

We successfully treated a patient with occupational hypersensitivity pneumonitis (HP) caused by Grifola frondosa (Maitake) mushroom spore with an extra-fine aerosol corticosteroid; beclomethasone dipropionate (BDP) dissolved in hydrofluoroalkane-134a (HFA). A 49-year-old woman developed respiratory symptoms 3 months after beginning work on a mushroom farm. She was diagnosed as HP based on radiological and serological findings. Oral prednisolone therapy improved her HP and she returned to the same farm. Her HP relapsed after 5 months, and daily 400 microg of HFA-BDP was administered with gradual improvement. An extra-fine particle inhaled corticosteroid might reach appropriate alveoli to be effective therapy for mild HP.

Altered surfactant protein A gene expression and protein metabolism associated with repeat exposure to inhaled endotoxin

Chronically inhaled endotoxin, which is ubiquitous in many occupational and domestic environments, can adversely affect the respiratory system resulting in an inflammatory response and decreased lung function. Surfactant-associated protein A (SP-A) is part of the lung innate immune system and may attenuate the inflammatory response in various types of lung injury. Using a murine model to mimic occupational exposures to endotoxin, we hypothesized that SP-A gene expression and protein would be elevated in response to repeat exposure to inhaled grain dust and to purified lipopolysaccharide (LPS). Our results demonstrate that repeat exposure to inhaled endotoxin, either in the form of grain dust or purified LPS, results in increased whole lung SP-A gene expression and type II alveolar epithelial cell hyperplasia, whereas SP-A protein levels in lung lavage fluid are decreased. Furthermore, these alterations in SP-A gene activity and protein metabolism are dependent on an intact endotoxin signaling system.

Protective effects of a recombinant fragment of human surfactant protein D in a murine model of pulmonary hypersensitivity induced by dust mite allergens

Lung surfactant protein D (SP-D) is a carbohydrate pattern recognition immune molecule. It can interact with a range of pathogens, stimulate immune cells and manipulate cytokine profiles during host's immune response. SP-D has also been shown to interact, via its carbohydrate recognition domains, with glycoprotein allergens of house dust mite (Dermatophagoides pteronyssinus, Derp), inhibiting specific IgE isolated from mite-sensitive asthmatic patients from binding these allergens, and blocking subsequent histamine release from sensitized basophils. In the present study, we have examined the protection offered by various doses of intranasal administration of a recombinant fragment of human SP-D (rhSP-D) in a murine model of pulmonary hypersensitivity to Derp allergens which showed characteristic high levels of specific IgE antibodies, peripheral blood eosinophilia, pulmonary infiltrates and a Th2 cytokine response. Treatment of Derp mice with rhSP-D led to significant reduction in Derp-specific IgE levels, blood eosinophilia and pulmonary cellular infiltration. The levels of IL-4 and IL-5 were decreased, while those of IL-12 and IFN-gamma were raised in the supernatant of the cultured splenocytes, indicating a Th2 to Th1 polarization. These results suggest that SP-D has a protective role in the modulation of allergic sensitization and in the development of allergic reactions to Derp allergens and highlight potential of the rhSP-D as a therapeutic for pulmonary hypersensitivity.

Clinical and radiologic manifestations of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is an inflammatory interstitial lung disease caused by recurring exposure to a variety of occupational and environmental antigens. It features widely variable clinical, radiologic, and histopathologic findings. Because the clinical findings of HP mimic multiple other diseases, a high degree of clinical suspicion and a thorough occupational and environmental history are essential for accurate diagnosis. There is no single pathognomonic feature for HP; rather, diagnosis relies on a constellation of clinical, radiologic, and pathologic findings. The radiologic manifestations, particularly the high-resolution computed tomography (HRCT) pattern, provide important clues and frequently point clinicians towards the correct diagnosis. The HRCT findings in HP may include ground-glass opacification, centrilobular nodules, air trapping (mosaic pattern), fibrosis, emphysema, or more frequently a combination of these. The combination of a mosaic pattern with ground-glass opacification and centrilobular nodules is particularly suggestive of the diagnosis. The best long-term prognosis is achieved with early diagnosis and removal from exposure.

Workplace-related chronic cough on a mushroom farm

BACKGROUND

Mushroom spores have frequently been associated with respiratory allergy. The aims of this study were to elucidate the incidence and causes of chronic cough in a mushroom farm.

METHODS

Participants were 69 mushroom workers who produce Hypsizigus marmoreus (Bunashimeji) and 35 control subjects. We excluded six workers because they had had asthma or allergic rhinitis before working. Participants completed a cross-sectional health survey 2 years after starting work at the mushroom farm.

RESULTS

The mean airborne endotoxin levels in the harvesting and packing rooms were approximately 60-fold higher than those in the offices. Of 63 workers, 42 workers (67%) reported chronic cough after working on this farm, 19 workers had no cough, while 2 workers had hypersensitivity pneumonitis develop to the spore, which has been previously reported by us. Of the 42 workers with cough, 6 workers had organic dust toxic syndrome (ODTS), 18 workers had postnasal drip syndrome, 15 workers had cough variant asthma, and 3 workers had eosinophilic bronchitis. Seventy-one percent of the workers noticed the cough in the first 3 months, and the mean latent period in ODTS workers was the shortest. The cough had a trend to improve or disappear after weekend holidays. Bronchial hyperresponsiveness but not FEV(1)/FVC% in the 42 workers with cough was significantly (p < 0.001) increased as compared with the control subjects.

CONCLUSIONS

Working on a mushroom farm carries a significant risk for chronic cough from inhalation of mushroom spores, and we suggest that elevated airborne endotoxin on this farm is the cause.

Occupational reactions to foods

The spectrum of occupational diseases most commonly seen in the food industry includes occupational asthma, rhinitis, conjunctivitis, dermatitis, and hypersensitivity pneumonitis. Occupational asthma represents between 3% and 20% of all asthma cases and is the most common form of occupational lung disease. Occupational skin diseases may represent between 10% and 15% of all occupational diseases, and they have significant economic impact. Hypersensitivity pneumonitis affects the food industry, with farmer's lung representing a common form of the disease. Each of these diseases may have serious and potentially irreversible effects on the health of a farmer, food processor, or food preparer, even after removal of the offending exposure.

Three-year follow-up study of allergy in workers in a mushroom factory

Exposure to mushroom spores may cause many respiratory allergic diseases, however, there has been no serial study in a mushroom factory to address this problem. The aim of this study was to investigate the serial changes in respiratory allergy and the incidence of hypersensitivity pneumonitis (HP) in mushroom workers. A 3-year follow-up study, beginning in June 1996, was conducted in a newly operating mushroom factory in which one kind of mushroom is produced: Hypsizigus marmoreus (Bunashimeji). Allergic symptoms, chest roentgenogram, serum precipitins to the spores and soluble adhesion molecules in sera were evaluated once a year in 60 workers and 20 controls. Three out of the 60 subjects were diagnosed as having HP caused by inhalation ofthe mushroom spore and they were therefore excluded from this study, and the 57 non-HP subjects were evaluated. In this study 24 workers quit because of intolerable cough, runny nose, wheezing, sputum, fever elevation and/or shortness of breath at their place of work. During each year of this study as many as 70-80% of employees suffered some ofthe above symptoms, cough being the most frequent, and positive rate of serum precipitins to the spore revealed 30% in 1996, 93% in 1997 and 94% in 1998. From the June 1996 examination until the following May, serum soluble intercellular adhesion molecule-1 levels of the 15 workers who quit during that period were significantly higher than those in the 42 workers still employed in 1997 (P < 0.05). Workers in Bunashimeji mushroom factories might be at critical risk of developing respiratory allergy. In our 3-year study over 90% workers were sensitized to the spore, 40% quit because of the symptoms and 5% developed HP. It was suggested that workers should be counselled about the risk of mushroom allergy and precautionary measures should be taken to prevent its occurrence.