Prevalence and Risk Factors for Farmer’s Lung in Greenhouse Farmers: An Epidemiological Study of 5,880 Farmers from Northeast China

Chronic Occupational Mold Exposure Drives Expansion of Aspergillus-Reactive Type 1 and Type 2 T-Helper Cell Responses

Occupational mold exposure can lead to Aspergillus-associated allergic diseases including asthma and hypersensitivity pneumonitis. Elevated IL-17 levels or disbalanced T-helper (Th) cell expansion were previously linked to Aspergillus-associated allergic diseases, whereas alterations to the Th cell repertoire in healthy occupationally exposed subjects are scarcely studied. Therefore, we employed functional immunoassays to compare Th cell responses to A. fumigatus antigens in organic farmers, a cohort frequently exposed to environmental molds, and non-occupationally exposed controls. Organic farmers harbored significantly higher A. fumigatus-specific Th-cell frequencies than controls, with comparable expansion of Th1- and Th2-cell frequencies but only slightly elevated Th17-cell frequencies. Accordingly, Aspergillus antigen-induced Th1 and Th2 cytokine levels were strongly elevated, whereas induction of IL-17A was minimal. Additionally, increased levels of some innate immune cell-derived cytokines were found in samples from organic farmers. Antigen-induced cytokine release combined with Aspergillus-specific Th-cell frequencies resulted in high classification accuracy between organic farmers and controls. Aspf22, CatB, and CipC elicited the strongest differences in Th1 and Th2 responses between the two cohorts, suggesting these antigens as potential candidates for future bio-effect monitoring approaches. Overall, we found that occupationally exposed agricultural workers display a largely balanced co-expansion of Th1 and Th2 immunity with only minor changes in Th17 responses.

Chronic hypersensitivity pneumonitis in the southeastern United States: an assessment of how clinicians reached the diagnosis

Background

Chronic hypersensitivity pneumonitis (cHP) is a disease caused by exposure to inhaled environmental antigens. Diagnosis of cHP is influenced by the awareness of the disease prevalence, which varies significantly in different regions, and how clinicians utilize relevant clinical information. We conducted a retrospective study to evaluate how clinicians in the Southeast United States, where the climate is humid favoring mold growth, diagnosed cHP using items identified in the international modified Delphi survey of experts, i.e., environmental exposure, CT imaging and lung pathology,

Methods

We searched Duke University Medical Center database for patients over the age of 18 with a diagnosis of cHP (ICD-9 code: 495) between Jan. 1, 2008 to Dec. 31, 2013 using a query tool, Duke Enterprise Data Unified Content Explorer (DEDUCE).

Results

Five hundred patients were identified and 261 patients had cHP confirmed in clinic notes by a pulmonologist or an allergist. About half of the patients lived in the Research Triangle area where our medical center is located, giving an estimated prevalence rate of 6.5 per 100,000 persons. An exposure source was mentioned in 69.3% of the patient. The most common exposure sources were environmental molds (43.1%) and birds (26.0%). We used Venn diagram to evaluate how the patients met the three most common cHP diagnostic criteria: evidence of environmental exposures (history or precipitin) (E), chest CT imaging (C) and pathology from lung biopsies (P). Eighteen patients (6.9%) met none of three criteria. Of the remaining 243 patients, 135 patients (55.6%) had one (E 35.0%, C 3.3%, P 17.3%), 81 patients (33.3%) had two (E + C 12.3%, E + P 17.3%, C + P 4.9%), and 27 patients (11.1%) had all three criteria (E + C + P). Overall, 49.4% of patients had pathology from lung biopsy compared to 31.6% with CT scan.

Conclusions

Environmental mold was the most common exposure for cHP in the Southeast United States. Lung pathology was available in more than half of cHP cases in our tertiary care center, perhaps reflecting the complexity of referrals. Differences in exposure sources and referral patterns should be considered in devising future diagnostic pathways or guidelines for cHP.

Clinical characteristics and outcomes of hypersensitivity pneumonitis: a population-based study in China

Backgrounds:

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) that develops in response to the inhalation of various antigens. The clinical pathologies are very complex and undetermined. The clinical features and outcomes of HP have not been fully elucidated. The aim of this study was to analyze the incidence, clinical features, and outcomes of HP patients and construct a simple clinical model for diagnosing chronic HP (CHP).

Methods:

The cohort study included 101 patients with HP admitted to the Nanjing Drum Tower Hospital from January 2009 to December 2017. The patients were categorized into acute HP (AHP, n = 72) and CHP (n = 29) groups according to the updated international criteria. The clinical, imaging, treatment, and follow-up data were retrospectively reviewed. All patients were followed up until December 31, 2017. Statistical analysis was performed, and a clinical scoring system for CHP was constructed by SPSS 20.0 software.

Results:

The incidence of HP was 2.4% in ILD inpatients in our center. Patients in the CHP group were older (t = −2.212, P = 0.029), had more smokers (χ² = 8.428, P = 0.004), and longer duration of symptoms (t = −4.852, P < 0.001) than those in the AHP group. Weight loss, crackles, digital clubbing, and cyanosis were more common in the CHP group than those in the AHP group (χ² = 5.862, P < 0.001; χ² = 8.997, P = 0.003; χ² = 11.939, P = 0.001; and χ² = 4.025, P = 0.045, respectively). On chest high-resolution computed tomography (HRCT), reticular patterns, traction bronchiectasis, and accompanying honeycombing were more common in CHP cases than those in AHP cases (χ² = 101.000, P < 0.001; χ² = 32.048, P < 0.001; and χ² = 36.568, P < 0.001, respectively). The clinical scoring system for CHP was established based on the clinical variables (age [A], duration of symptoms [D], smoking history [S], unidentified exposure [U], and chest HRCT [C]; ADSUC) (area under the curve 0.935, 95% confidence interval: 0.883–0.987, P < 0.001). Eleven patients (15.3%) in the AHP group developed CHP, and unidentified exposure was an independent risk factor for the progression of disease (P = 0.038). The survival of patients with CHP, smoking history, unidentified antigens and fibrosis on Chest HRCT were significantly worse (P = 0.011, P = 0.001, P = 0.005, and P = 0.011, respectively) by Kaplan-Meier analysis. Cox multivariate regression analysis revealed that unidentified exposure and total lung volume (TLC pred%) were independent prognostic predictors for HP patients (P = 0.017 and P = 0.017, respectively).

Conclusions:

The clinical features and outcomes of the CHP patients differ from those of the AHP patients. ADSUC is a simple and feasible clinical model for CHP. Unidentified exposure is an independent risk factor for the progression of AHP to CHP. Unidentified exposure and a low baseline TLC pred% are independent predictors for survival in HP patients.

Association between greenhouse working exposure and bronchial asthma: A pilot, cross-sectional survey of 5,420 greenhouse farmers from northeast China

Long-term exposure to greenhouse environments exposes greenhouse workers to inhalation of antigens that can cause respiratory diseases. This study was conducted to investigate the prevalence and potential risk factors for bronchial asthma among the Chinese greenhouse workers based on questionnaire and spirometry data. This was an observational cross-sectional study, performed via stratified-cluster-random sampling. It was conducted in Liaoning Province from the northeast of People's Republic of China, using a population-based sample of 5,880 workers at 835 plastic film greenhouses. All subjects were interviewed using a standardized questionnaire and underwent pulmonary function tests. Multiple logistic regression analysis was conducted to assess associations between self-reported factors of greenhouse worker exposure and bronchial asthma and to identify potential risk factors for this disease. A total of 5,420 questionnaires were completed. The overall prevalence of asthma in greenhouse workers was 19.2% (1040/5420). Multiple logistic regression analysis revealed that the use of multiple pesticides (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.03-1.49), bad odors in the greenhouse (OR = 1.26, 95% CI = 1.07-1.49), and report of the onset of cough when entering the greenhouse (OR = 1.25, 95% CI = 1.09-1.44) were associated with the development of asthma. In contrast, a higher body mass index (BMI >18.5 kg/m^2, OR = 0.93, 95% CI = 0.90-0.95), planting flowers (OR = 0.92, 95% CI = 0.87-0.98), open sidewall to outside (natural ventilation) for at least 30 min per event (OR = 0.82, 95% CI = 0.69-0.96), living in greenhouse (OR = 0.85, 95% CI = 0.73-0.99), and experiencing cough before 14 years old (OR = 0.61, 95% CI = 0.43-0.84) were protective factors to the presentation of asthma among greenhouse workers. Our results suggest that asthma is a major public health problem among Chinese greenhouse workers and more attention should be devoted to preventive measures and management of this disease.

Evaluation of Aspergillus and Mucorales specific T-cells and peripheral blood mononuclear cell cytokine signatures as biomarkers of environmental mold exposure

Mold specific T-cells have been described as a supportive biomarker to monitor invasive mycoses and mold exposure. This study comparatively evaluated frequencies and cytokine profiles of Aspergillus fumigatus and Mucorales reactive T-cells depending on environmental mold exposure. Peripheral blood mononuclear cells (PBMCs) obtained from 35 healthy donors were stimulated with mycelial lysates of A. fumigatus and three human pathogenic Mucorales species. CD154⁺ specific T-cells were quantified by flow cytometry. In a second cohort of 20 additional donors, flow cytometry was complemented by 13-plex cytokine assays. Mold exposure of the subjects was determined using a previously established questionnaire. Highly exposed subjects exhibited significantly greater CD154⁺A. fumigatus and Mucorales specific naïve and memory T-helper cell frequencies. Significant correlation (r = 0.48 - 0.79) was found between A. fumigatus and Mucorales specific T-cell numbers. Logistic regression analyses revealed that combined analysis of mold specific T-cell frequencies and selected cytokine markers (A. fumigatus: IL-5 and TNF-α, R. arrhizus: IL-17A and IL-13) significantly improves classification performance, resulting in 75-90 % predictive power using 10-fold cross-validation. In conclusion, mold specific T-cell frequencies and their cytokine signatures offer promising potential in the assessment of environmental mold exposure. The cytokines identified in this pilot study should be validated in the clinical setting, e. g. in patients with hypersensitivity pneumonitis.

Hypersensitivity pneumonitis: Antigen diversity and disease implications

Hypersensitivity pneumonitis (HP) is an immune-mediated syndrome triggered by inhalation of a wide variety of allergens, to which an individual has previously been sensitized. More than 200 agents responsible for the disease have already been identified; however, HP occurs only in a small number of individuals exposed to causal antigens. The present report provides an overview of the role of antigen role in HP, highlighting its diversity, research methods, and prevention strategies, as well as the impact on disease prognosis following elimination of antigen. HP is an underdiagnosed disease and, therefore, it is difficult to accurately estimate its incidence. Triggering antigens can be divided into six broad categories: bacteria, fungi, mycobacteria, animal and plant proteins, chemicals, and metals, represented by disease prototypes. The identification of causal antigen is a major challenge; it is impossible to obtain in about 30-60% of cases. The acute form of HP, with early detection and immediate eviction of causal antigen, tends to have an excellent prognosis. In the chronic form, partial recovery of disease is still possible; however, some cases tend to progress to fibrosis, even after removal from exposure. In conclusion, HP diagnosis should be based on a proactive search for potential antigen sources, although their identification is hampered by the lack of standardized methods of demonstrating the specific antigen sensitization. Antigen avoidance is a critical determinant in disease prognosis.

Positive Rates and Factors Associated with Abnormal Lung Function of Greenhouse Workers in China: A Cross-Sectional Study

Since the number of greenhouse workers are increasing in China, this observational cross-sectional study was designed to evaluate lung function and discuss the potential risk factors, to provide evidence in the surveillance of greenhouse workers' health. 678 greenhouse workers in Gansu Province, China were enrolled. A questionnaire which included demographic and occupational information was used. Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and FEV₁:FVC ratios (FEV₁/FVC), maximal expiratory flow after 50% of the FVC has not been exhaled (MEF₅₀), maximal expiratory flow after 25% of the FVC has not been exhaled (MEF₂₅) and maximal mid-expiratory flow curve (MMEF) were measured as lung function indicators. The mean values and standard deviations (SDs) of VC% predicted, FVC% predicted, FEV₁% predicted and FEV₁/FVC ratio were 106.07 ± 13.36, 107.60 ± 13.95, 97.19 ± 14.80 and 89.76 ± 10.78 respectively. The positive rates of above four and abnormal lung ventilation function were 2.9%, 2.8%, 11.2%, 4.6% and 6.5% respectively. Gender, age, BMI and number of greenhouses owned were influence factors of lung ventilation function (p < 0.05). The mean values and SDs of MEF₅₀% predicted, MEF₂₅% predicted and MMEF% predicted were 69.63 ± 24.95, 54.04 ± 24.94 and 66.81 ± 24.53. The positive rates of above three and abnormal small airway function were 45.0%, 72.1%, 47.2% and 49.4% respectively. Age, education and number of greenhouses owned were influence factors for small airway function (p < 0.05). Working in a greenhouse might influence lung function of the workers. Small airway function indicators could be used as priority indicators for the surveillance of greenhouse workers' health.

Pulmonary health effects of agriculture

PURPOSE OF REVIEW

Occupational exposures in the agricultural industry are associated with numerous lung diseases, including chronic obstructive pulmonary disease, asthma, hypersensitivity pneumonitis, lung cancer, and interstitial lung diseases. Efforts are ongoing to ascertain contributing factors to these negative respiratory outcomes and improve monitoring of environmental factors leading to disease. In this review, recently published studies investigating the deleterious effects of occupational exposures in the agricultural industry are discussed.

RECENT FINDINGS

Occupational exposures to numerous agricultural environment aerosols, including pesticides, fungi, and bacteria are associated with impaired respiratory function and disease. Increases in certain farming practices, including mushroom and greenhouse farming, present new occupational exposure concerns. Improved detection methods may provide opportunities to better monitor safe exposure levels to known lung irritants.

SUMMARY

In the agricultural industry, occupational exposures to organic and inorganic aerosols lead to increased risk for lung disease among workers. Increased awareness of respiratory risks and improved monitoring of agricultural environments are necessary to limit pulmonary health risks to exposed populations.

Prevalence and risk factors for COPD in greenhouse farmers: a large, cross-sectional survey of 5,880 farmers from northeast China

Background

COPD is one of the most common chronic diseases, and more and more farmers who were frequently exposed to greenhouse environments were diagnosed with COPD. However, little information is available on the prevalence of COPD among the greenhouse farmers. This study was conducted to assess the prevalence of COPD and investigate the potential risk factors for COPD among the Chinese greenhouse farmers.

Methods

Cross-sectional studies involving a sample of greenhouse farmers living in northeast China were performed via stratified-cluster-random sampling. All subjects were interviewed using a uniform questionnaire and underwent pulmonary function tests between 2006 and 2009, based on the diagnostic criteria of the Global Initiative for Chronic Obstructive Lung Disease. Multiple logistic regression analysis was conducted to examine the risk factors for COPD.

Results

Of the 5,880 greenhouse farmers from northeast China who were originally selected for this study, 5,420 questionnaires were completed. The overall prevalence of COPD in greenhouse farmers was 17.5%. The COPD prevalence was significantly higher in elderly subjects (≥50 years), current smokers, in those with lower body mass index (≤18.5 kg/m²) and less education, in those who were exposed to mushroom, flowers and poultry, and in those living in mountain and coastal region. Multiple logistic regression analysis revealed that age over 50 years old (odds ratio [OR]=298.69, 95% confidence interval [CI]=121.57–733.84), smoking (OR=2.18, 95% CI=1.84–2.59), planting mushroom and flowers (OR=1.46 and 1.53, 95% CI=1.13–1.87 and 1.24–1.95), and living in mountain and coastal region (OR=1.68 and 1.35, 95% CI=1.37–2.06 and 1.10–1.65) were associated with the development of COPD among greenhouse farmers.

Conclusion

In northeast China, COPD is highly prevalent among greenhouse farmers, and advanced age, smoking, planting mushroom, and flowers, as well as living in mountain and coastal regions, are potential risk factors for this disease.