{L-End}Objective To investigate the effect and mechanism of low dose metformin in delaying pulmonary fibrosis in silicosis mice. {L-End}Methods The specific pathogen free C57BL/6 male mice were randomly divided into four groups,with six mice in each group. Mice in the silicosis model group and the metformin intervention group were given 20 μL of a mass concentration of 250 g/L silica suspension, and mice in the blank control group and the drug control group were given 20 μL of 0.9% sodium chloride solution, using tracheal exposure method. After 72.0 hours of dust exposure, the mice of drug control group and metformin intervention group were intraperitoneally injected with metformin at a dose of 65 mg/kg body mass, while the mice in the blank control group and the silicosis model group were given 0.9% sodium chloride solution at the same volume, once every other day for 28 days. After the treatment, histopathological change of the lungs was observed, lung organ coefficient was calculated, degree of pulmonary fibrosis was evaluated with Ashcroft score, and mRNA expression of fibronectin (Fn)1 and collagen typeⅠ(COLⅠ) alpha 1 (Col1a1) in lung tissues were detected by real-time fluorescence quantitative polymerase chain reaction. The relative expression of FN and COLⅠ in lung tissues was determined by Western blot. {L-End}Results The results of histopathological examination of the lungs showed that there were no inflammation and fibrosis in the lungs of mice in the blank control group and the drug control group; mice in silicosis model group had inflammation and fibrosis in lung; the degree of lung inflammation and fibrosis was reduced in the mice of metformin intervention group compared with the silicosis model group. The lung organ coefficient, Ashcroft score, the relative expression of Fn1 and Col1a1 mRNA, the relative expression of FN and COLⅠprotein in lung tissues increased in silicosis model group (all P<0.05), compared with those in both blank control group and drug control group. The indexes above decreased of mice in the metformin intervention group than those in the silicosis model group (all P<0.05). {L-End}Conclusion Low-dose metformin can delay the progression of pulmonary fibrosis in silicosis mice. The mechanism may be related to metformin's improving excessive deposition of extracellular matrix induced by silica.

Objective: To investigate the role of surfactant associated protein-A (SP-A) in the development and progression of silicosis, and its mechanism. Methods: Homozygous and heterozygous mice of SP-A knockout of specific pathogen free (SPF) grade were selected for mating, and mice with SP-A^-/- genotype were selected for subsequent experiments. SP-A wild-type (SP-A^+/+) and SP-A^-/- mice were divided into SP-A^+/+ control group, SP-A^-/- control group, SP-A^+/+ silicosis group and SP-A^-/- silicosis group with six mice in each group by random number table method. Mice in both silicosis groups were given 20.0 μL 250 g/L silica suspension by tracheal exposure, and mice in both control groups were injected with 0.9% sodium chloride solution at the same volume. On the 28th day after modeling, mice were sacrificed. Lung tissues were used for lung histopathology examination. The apoptosis of alveolar type Ⅱ epithelial cells of mice was detected by TUNEL method. The mRNA expression of B-lymphoblastoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), cysteinyl aspartate specific proteinase (Caspase)-3 and Caspase-9 in lung tissues of mice was detected by quantitative real-time polymerase chain reaction. Results: The histopathological result of mice showed that thickened alveolar septum, scattered silicon nodule and collagen fiber formation were observed in the mice lungs of SP-A^+/+ silicosis group, and a large number of inflammatory cells were observed in silicosis nodule, after exposure to silica dust. SP-A^-/- silicosis group resulted in a more severe pulmonary inflammation and interstitial fibrosis compared to SP-A^+/+ silicosis group. The apoptosis of alveolar type Ⅱ epithelial cells and the mRNA relative expression levels of Bax, Caspase-3 and Caspase-9 in lung tissues of mice in each silicosis groups were increased compared with their control groups (all P<0.05). The above four indexes of mice in SP-A^-/- silicosis group were higher than those in SP-A^+/+ silicosis group (all P<0.05). There was no significant difference in the expression of Bcl-2 mRNA in lung tissues of these four groups (P>0.05). Conclusion: Knockout of SP-A can aggravate inflammation and pulmonary fibrosis in silicosis model mice, and promote apoptosis of alveolar type Ⅱ epithelial cells. The mechanism may be related to the Bcl-2/Bax/Caspase-3 signaling pathway which affects the apoptosis of mitochondrial pathway.

Early diagnosis of pulmonary diseases is of great significance for their prevention and treatment. Serum Krebs von den Lungen-6 (KL-6) assay can reflect the damage degree of alveolar epithelium and stromal tissue, and is simple, non-invasive and low-cost. Pervious study showed that the serum KL-6 level was higher in patients with various interstitial lung diseases (e.g. idiopathic pulmonary fibrosis and connective tissue disease, primary Sjögren's syndrome, rheumatoid arthritis, idiopathic inflammatory myopathy and systemic sclerosis combined with interstitial lung disease), non-small cell lung cancer, various pneumonias and chronic obstructive pulmonary disease compared to healthy controls. Therefore, serum KL-6 has good sensitivity and specificity for the early diagnosis of these diseases. Occupational pneumoconiosis is an interstitial lung disease with a well-established etiology. Pervious study has shown that serum KL-6 level was higher in patients with occupational silicosis, occupational asbestosis, and dust-exposed workers compared to healthy controls. However, due to the limited sample size and the inconsistent findings on different studies, further research is needed to study the role of serum KL-6 in the early diagnosis of pneumoconiosis. Future studies should increase the sample size, improve the detection methods for serum KL-6, explore its feasibility as an early diagnostic biomarker for occupational pulmonary diseases, and investigate the efficacy andvalue of its combined application with other biomarkers in the early diagnosis of various pulmonary diseases, including occupational lung diseases, to fully exploit its predictive role in pulmonary diseases.

Objective To explore the beneficial effects and mechanisms of neutrophil elastase (NE) and myeloperoxidase (MPO) on lead-induced hepatic inflammation in mice. Methods The specific pathogen free male C57BL/6 mice were randomly divided into four groups： control group, lead-exposed group, NE inhibitor group, and MPO inhibitor group, with three mice in each group. The mice in lead-exposed group, NE inhibitor group, and MPO inhibitor group were intraperitoneally injected with a dose of 10 mg/kg body mass of lead acetate solution, while the mice of control group received an equal volume of 0.9% saline three times per week for four weeks. In the last seven days, mice in both inhibitor groups were intraperitoneally injected with a dose of 40 mg/kg NE inhibitor sivelestat sodium or MPO inhibitor 4-aminobenzoic acid hydrazide (4-ABAH) once per day. Mouse body weight and liver histopathological changes were observed. The mRNA expression of genes associated with inflammation, such as tumor necrosis factor-α (Tnfa), interleukin-1β (Il1b), interleukin-6 (Il6), and nucleotide-binding oligomerization domain-like receptor protein 3(Nlrp3), apoptosis-associated speck-like protein (Asc) and cysteinyl aspartate specific proteinase (Caspase1) in the mouse liver tissues was detected by real-time quantitative polymerase chain reaction. The protein expression of NLRP3, ASC, and CASPASE-1 was detected using Western blotting. Results The activities of mice in all four groups were generally normal, and there was no significant difference in body weight (P>0.05). The results of hematoxylin-eosin staining showed that the cell size of hepatocytes varied in the lead-exposed mice, with indistinct cell boundaries, indicating early inflammatory responses in liver tissues. After intervention with NE or MPO inhibitors, the early inflammatory responses improved in the liver tissues of the mice in both inhibitor groups, with a better improvement observed in MPO inhibitor group compared with the NE inhibitor group. The mRNA expression of Tnfa, Il1b, Il6, Nlrp3, Asc, and Caspase1, as well as the protein expression of ASC, and CASPASE-1 in the livers of mice in the lead-exposed group was higher compared with those in the control group (all P<0.05). Compared with the lead-exposed group, the relative mRNA expression of Tnfa, Il1b, Il6, Nlrp3 and Asc was decreased in the liver tissues of mice in the NE inhibitor group (all P<0.05), while the relative expression of mRNA of Tnfa, Il1b, Il6, Caspase1 and the protein expression of ASC and CASPASE-1 were decreased in the liver tissues of mice in the MPO inhibitor group (all P<0.05). Conclusion Lead induce hepatic inflammation in mice by activating NLRP3 inflammasome. The inhibition of NE or MPO improve the lead-induced hepatic inflammatory responses in mice by alleviating NLRP3 inflammasome activation.

Objective To detect and analyze the susceptibility genes of methyl acetate poisoning in patients by whole exome sequencing. Methods Two patients with occupational acute severe methyl acetate poisoning and their first-degree relatives who work in the same occupation and position with similar working hours were selected as the research subjects by judgment sampling method. Peripheral blood was collected for whole exome sequencing. The sequencing data was compared with the public genome database to screen the mutation sites and find out the gene sites related to methyl acetate poisoning. The suspected pathogenic mutation genes were annotated and interpreted. Results The results of whole exome sequencing showed that there were 40 differential genes between the patients with methyl acetate poisoning and their first-degree relatives, including 80 single nucleotide polymorphisms and eight Indel with specific marker sequence index. Among these, the genes with strong correlation were carboxyesterase 1 (CES1) and mucin (MUC) 5B. The CES1 gene loci c.248C>T (p.Ser83Leu) heterozygous mutations, MUC5B gene loci c.6635C>T (p.Thr2212Met) and c.7685C>T (p.Thr2562Met) heterozygous mutations in patients with methyl acetate poisoning were detected. They were missense mutations. By constructing a protein-protein interaction network, a total of 11 pairs of interactions with high levels of evidence were identified, involving genes such as lysine methyltransferase 2C, HECT and RLD domains containing E3 ubiquitin protein ligase 2, neutrophil cytoplasmic factor 1, nicotinamide adenine dinucleotide phosphate oxidase 3, C-terminal binding protein 2, zinc finger protein 717, FSHD region gene 2 family member C, FSHD region gene 1, MUC4, MUC6, MUC5B, and MUC12. Conclusion The polymorphism of CES1 and MUC5B genes may be related to the occurrence and development of methyl acetate poisoning in patients.

Objective To analyze the occupational health status of radiation workers in Guangdong Province. Methods A total of 8 913 radiation workers who underwent occupational medical examination (OME) in Guangdong Province Hospital for Occupational Disease Prevention and Treatment in 2020 were selected as the exposure group, and 2 024 non-radiological workers who underwent health examination in the same hospital in the same period of time were selected as the control group using convenient sampling method. The study analyzed the prevalence of abnormalities in thyroid, eye lens, blood pressure, complete blood count and micronucleus in individuals of the two groups. Results The abnormal rates of eye lens, blood pressure and complete blood count in the radiation workers in the exposure group were higher than those in the control group (23.3% vs 8.0%, 18.6% vs 9.0%, 18.1% vs 8.5%, all P<0.01). However, there was no significant difference in the abnormal rates of thyroid and micronucleus in workers between these two groups (12.8% vs 11.5%, 0.1% vs 0.0%, all P>0.05). The abnormal rates of thyroid, eye lens and blood pressure in radiation workers increased with the exposure period of radiation (all P<0.05). Conclusion Long-term exposure to low-dose ionizing radiation have certain effects on the thyroid, eye lens, and blood pressure of radiation workers, with a time-effect relationship of years of radiation work.