| Objective: Formaldehyde(HCHO) is an important chemical raw material, widely used in the plastics industry, such as synthetic fibers, MDF industry, leather industry and medicine, fuel and other industries. Formaldehyde is an environmental allergens. In recent years, epidemiological studies on formaldehyde and asthma found that exposure to formaldehyde may induce asthma or aggravate asthma symptoms. In 2013, formaldehyde has been included China’s "diagnosis of occupational asthma" standard occupational allergen list. But now formaldehyde-induced asthma mechanism is unclear. The nature of asthma is a chronic airway inflammation, which is involved by mast cells, eosinophils, T lymphocytes and other cells. A number of inflammatory cytokines must be involved in inflammation. In this study, rats were exposed to formaldehyde, the detect serum concentrations of various cytokines to observe changes of cytokines, suggesting possible mechanisms of formaldehyde-induced asthma. In addition,by measuring lung function of workers and detect serum concentrations of cytokines, explore the feasibility of peripheral serum cytokine concentrations as early biomarkers of formaldehyde-induced asthma.Methods:The Wistar rats were randomly divided into four groups, namely the control group, low dose group, middle dose group and high-dose groups, N = 11. Each group inhale formadehyde for 4 hours per day for 10 days. Seal exposure cabinet, power on, and turn on magnetic stirrer to accelerate formaldehyde volatile. After 15 minutes, turn on the fan. Detect the concentration of formaldehyde in the exposure chamber and compute the averaged concentration of formaldehyde. The control group received no treatment, normal feeding. During the experiment, the general situation of rats were observed after exposure every day, every other day the rats were weighed and the data were recorded. Weigh rat lung and rat body, and compute the weight ratio of the lung and body. The pathological changes of the lung tissue of rats were observed, the concentration of IL-3, IL-4, IL-5, IL-6, IL- 8, IL-10, IL-12 IL-13, TNF-α, GM-CSF and IgE in serum and bronchoalveolar lavage fluid were measured.In the city of Shandong province, 211 workers were selected from three MDF manufacturing enterprises by cluster random sampling method. According to occupational health epidemiology, basic information of workers, individual protection, the symtoms after exposuring formaldehyde, the history of occupational exposure, alcohol, tobacco, Health / diseases, family, symptoms and the aware of formaldehyde hazards were gathered by unified trained investigators using self-designed occupational health survey. Measured each subject’s lung function and the concentrations of IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, TNF-α, GM-CSF, Ig E in serum.Results:ANOVA showed that the difference between groups of rat lung weight ratio was statistically significant(P<0.05), but Dunnett,s test results showed that compared with the control group, only the low-dose rat lung weight ratio is larger, and the difference was statistically significance(P<0.05). Rat serum cytokines, only IL-3, IL-4, IL-5, IL-10 and IgE have differences between the groups. By Dunnett,s test, compared with the control group, found that only IL-3 and IL-5 of low-dose group were higher, and the difference was statistically significant(P<0.05), the IL-10 level of low-dose group was lower, and the difference was statistically significant(P<0.05), higher IgE levels of high dose group, and the difference was statistically significant(P<0.05). Lavage fluid of rats, IL-6, IL-10, TNF-α and between GM-CSF group differences exist. Using Dunnett,s test showed that: Compared with the control group, the IL-6 level of low-dose group rats, alveolar lavage fluid decreased, and the difference was statistically significant(P<0.05); the IL-10 level of lavage fluid in rats showing increasing trend after the first drop, the IL-10 concentration of moderate dose groupe was lower than the control group, and the difference was statistically significant(P<0.05), the IL 10-concentration of high dose group was higher than control group, the difference was statistically significant(P<0.05); the TNF-α concentration of alveolar lavage fluid showed an increasing trend, TNF-α of the high dose group was higher than the control group, the difference was statistically significant(P<0.05); compared with the control group, the GM-CSF concentration of alveolar lavage fluid of low dose group was higher, and the difference was statistically significant(P<0.05).The concentration of formaldehyde in the air test results showed that the concentration of formaldehyde in workplace air was 1.00 ± 0.66 mg / m3, the highest concentration of test points was 3.09 mg / m3, the lowest concentration was 0.33 mg / m3. In addition to warehouse and the duty room of glue, the other location formaldehyde concentrations exceeding the maximum allowable concentration of the state. The exposed group of eye irritation, tearing, cough, sputum, throat pain, respiratory dry and headache, dizziness occurrence rate was higher population, the difference was statistically significant(P<0.05). The exposed group of the concentration of serum IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, TNF-α, GM-CSF, IgE had no difference with the control group. FVC(FVC) of the exposed group was lower than the control group, and the difference was statistically significant(P<0.05).Conclusion:Inhaling different concentrations of formaldehyde had different damage on rat lung tissue. Inhalation of low doses of formaldehyde main cause pulmonary edema in rats, Th2 cells secrete cytokines increase and significant inflammatory response; inhalation high doses of formaldehyde mainly caused small lung bronchi and alveolar structural damage, although all accompanied by inflammation, but the main participation inflammatory mediators are different with low dose group.Cross-sectional study found that long-term inhalation of formaldehyde can be reduced FVC of workers, indicating that change is a sensitive indicator of lung function of lung injury. although the status of studies have found concentrations of serum cytokines of workers who occupational exposure to formaldehyde without asthma unchanged, but after formaldehyde exposure, rats had asthma and the change cytokine concentrations in serum and bronchoalveolar lavage fluid obviously, a comprehensive analysis of cytokines may be considered indicators of asthma sense. |
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