BACKGROUND: Organic chemicals have been known to cause allergic diseases such as bronchial asthma and hypersensitivity pneumonitis; however, the possibility that they do not cause irreversible pulmonary fibrosis has not been considered. Polyacrylic acid (PAA), an organic chemical, has caused irreversible progressive pulmonary fibrosis in exposed workers, indicating its potential to induce pulmonary inflammation and fibrosis. Although intratracheal instillation studies are commonly used for evaluating lung pathology, traditional methods face challenges with chemical substances, particularly nanoparticles, which tend to aggregate in suspension and prevent uniform pulmonary distribution. Such aggregation alters the qualitative and quantitative responses to lung injury, limiting accurate assessment of lung pathology. To overcome this limitation, we developed a 'molecular dispersion method' that uses pH modification to negative charges to PAA particles, maintaining their dispersion. Using this method, we investigated the effects of PAA on pulmonary inflammation and fibrosis in a rat model. METHODS: F344 rats were intratracheally instilled with PAA using molecular dispersion (0.1 mg/rat, 1.0 mg/rat), PAA without molecular dispersion (1.0 mg/rat), and normal saline (control group). Rats were sacrificed at 3 days, 1 week, 1 month, 3 months, and 6 months after exposure to examine inflammatory and fibrotic responses. RESULTS: PAA caused persistent increases in neutrophil influx in the bronchoalveolar lavage fluid (BALF) from 3 days to 1 month following instillation. In histopathological findings, the group with molecular dispersion had almost no inflammatory masses in the lung tissue compared to the group without molecular dispersion, and exhibited relatively uniform dispersion. CONCLUSION Intratracheal instillation of dispersed PAA induced neutrophil inflammation and fibrosis in the rat lung, suggesting that PAA might have pulmonary inflammogenicity and fibrogenicity. Intrapulmonary dispersion of PAA particles following intratracheal instillation studies using the molecular dispersion method was similar to that following inhalation studies.
Animals ; Rats, Inbred F344 ; Acrylic Resins/adverse effects* ; Rats ; Inhalation Exposure/adverse effects* ; Male ; Pulmonary Fibrosis/pathology* ; Pneumonia/pathology* ; Lung/pathology* ; Bronchoalveolar Lavage Fluid/cytology*

OBJECTIVES: To investigate the effect of Haematococcus pluvialis (HP) on bleomycin (BLM)-induced pulmonary fibrosis in mice and on TGF-β1-induced human fetal lung fibroblasts (HFL1). METHODS: Thirty male C57BL/6 mice were randomly divided into control group, BLM-induced pulmonary fibrosis model group, low- and high-dose HP treatment groups (3 and 21 mg/kg, respectively), and 300 mg/kg pirfenidone (positive control) group. The effects of drug treatment for 21 days were assessed by examining respiratory function, lung histopathology, and expression of fibrosis markers in the lung tissues of the mouse models. In TGF-β1-induced HFL1 cell cultures, the effects of treatment with 120, 180 and 240 μg/mL HP or 1.85 μg/mL pirfenidone for 48 h on expression levels of fibrosis markers were evaluated. Transcriptome analysis was carried out using the control cells and cells treated with TGF-β1 and 240 μg/mL HP. RESULTS: HP obviously alleviated BLM-induced lung function damage and fibrotic changes in mice, evidenced by improved respiratory function, lung tissue morphology and structure, inflammatory infiltration, and collagen deposition and reduced expressions of fibrotic proteins. HP at the high dose produced similar effect to PFD. In TGF-β1-induced HFL1 cells, treatment with 240 μg/mL HP significantly reduced the mRNA and protein expression levels of α-SMA and FN. Transcriptome analysis revealed that multiple key genes and pathways mediated the protective effect of HP against pulmonary fibrosis. CONCLUSIONS HP alleviates pulmonary fibrosis in both the mouse model and cell model, possibly as the result of the synergistic effects of its multiple active components.
Animals ; Pulmonary Fibrosis/chemically induced* ; Bleomycin/adverse effects* ; Mice, Inbred C57BL ; Male ; Mice ; Fibroblasts/drug effects* ; Lung/pathology* ; Transforming Growth Factor beta1/pharmacology* ; Myofibroblasts/drug effects* ; Humans ; Pyridones

OBJECTIVE: To investigate the intervention of melatonin (MT) in the expression of circadian genes in patients with pulmonary fibrosis and to analyze the mechanism by which it alleviates the progression of pulmonary fibrosis. METHODS: By utilizing the Gene Expression Omnibus (GEO) database, we identified differentially expressed circadian genes between patients with pulmonary fibrosis and controls. We analyzed the correlation between circadian genes and pulmonary function as well as genes related to pulmonary fibrosis. A bleomycin-induced mouse model of pulmonary fibrosis (BLM group) was constructed to observe the expression differences of PER2 and CRY2 by sequencing and immunohistochemical staining in the BLM group and after MT intervention (BLM+MT group). Hematoxylin and eosin (HE) staining and Masson staining were used to observe the effects of MT on fibrosis. We used Western blot to detect the expression of P-smad2/3 in lung epithelial cells induced by transforming growth factor β (TGF-β). Reverse transcription quantitative real-time PCR technology was employed to investigate the rhythmic expression changes of circadian genes in the control group, TGF-β group, and TGF-β+MT group. Finally, luzindole, a MT receptor antagonist, was used to intervene in TGF-β+MT group, and Western blot was used to explore the receptor dependence of MT in alleviating TGF-β-induced epithelial-mesenchymal transition. RESULTS: (1) Analysis of the GEO dataset (GSE) revealed a negative correlation between circadian genes PER2 and CRY2 and the expression of TGF-β, and a positive correlation with pulmonary function indicators in patients. (2) Transcriptome sequencing analysis of lung tissue in BLM group found that the expression of PER2 and CRY2 was significantly reduced compared with the normal group. Histopathological staining results showed that the lung tissue structure of the normal group was intact and clear, with thin alveolar septa; in the BLM group, there was a large increase in collagen fibers and disordered alveolar structure; compared with the BLM group, the BLM+MT group had reduced collagen fiber proliferation and inflammatory cell infiltration; the expression of PER2 and CRY2 in the BLM group was lower than in the normal group, and the expression in the BLM+MT group was increased compared with the BLM group. (3) In vitro lung epithelial cell experiments with TGF-β intervention showed that compared with the control group, the expression of P-smad2/3 increased in the TGF-β group, and MT intervention inhibited the inducing effect of TGF-β on P-smad2/3, while intervention with the MT receptor antagonist reversed this phenomenon. The results indicated that MT could inhibit the activation of the TGF-β pathway, and this process was dependent on MT receptors. (4) The 48-hour rhythm experiment in lung epithelial cells showed that the mRNA rhythm of PER2 and CRY2 in the TGF-β+MT group was close to 24 hours and showed a trend towards restoring the rhythm of the control group, while the addition of the MT receptor blocker tended to make the rhythm duration and amplitude of both groups approach that of the TGF-β group. CONCLUSION MT, by binding to its receptors, can restore the periodic expression of the circadian genes PER2 and CRY2, thereby inhibiting the activation of the TGF-β classical pathway and suppressing the pathological process of epithelial-mesenchymal transition in pulmonary fibrosis. This finding provides new molecular targets and potential therapeutic strategies for the treatment of pulmonary fibrosis.
Melatonin/pharmacology* ; Animals ; Mice ; Pulmonary Fibrosis/chemically induced* ; Bleomycin ; Humans ; Transforming Growth Factor beta/metabolism* ; Period Circadian Proteins/metabolism* ; Smad3 Protein/genetics* ; Disease Models, Animal ; Lung/pathology* ; Cryptochromes/metabolism* ; Smad2 Protein/genetics* ; Epithelial Cells/metabolism* ; Mice, Inbred C57BL

Pulmonary fibrosis is a severe lung interstitial disease characterized by the destruction of lung tissue structure, excessive activation and proliferation of fibroblasts, secretion and accumulation of a large amount of extracellular matrix (ECM), and impaired lung function. Due to the complexity of the disease, a suitable animal model to mimic human pulmonary fibrosis has not yet been established. Precision-cut lung slice (PCLS) has been a widely used in vitro method to study lung physiology and pathogenesis in recent years. This method is an in vitro culture technology at the level between organs and cells, because it can preserve the lung tissue structure and various types of airway cells in the lung tissue, simulate the in vivo lung environment, and conduct the observation of various interactions between cells and ECM. Therefore, PCLS can compensate for the limitations of other models such as cell culture. In order to explore the role of discoidin domain receptor 2 (DDR2) in pulmonary fibrosis, Ddr2^flox/flox mice were successfully constructed. The Cre-LoxP system and PCLS technology were used to verify the deletion or knockdown of DDR2 in mouse PCLS. Transforming growth factor β1 (TGF-β1) can induce fibrosis of mouse PCLS in vitro, which can simulate the in vivo environment of pulmonary fibrosis. In the DDR2 knock down-PCLS in vitro model, the expression of various fibrosis-related factors induced by TGF-β1 was significantly reduced, suggesting that knocking down DDR2 can inhibit the formation of pulmonary fibrosis. The results provide a new perspective for the clinical study of DDR2 as a therapeutic target in pulmonary fibrosis.
Animals ; Humans ; Mice ; Discoidin Domain Receptor 2/metabolism* ; Fibroblasts/pathology* ; Fibrosis ; Lung/pathology* ; Pulmonary Fibrosis/metabolism* ; Transforming Growth Factor beta1/metabolism*

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease, the cause is not yet clear. Pathological manifestations are abnormal repair changes resulting from sustained lung injury. Macrophages have been identified as playing a key role in IPF pathogenesis. In different local microenvironments, macrophages can exhibit either classically activated (M1) or alternately activated (M2) phenotypes. M1 plays a key role in promoting inflammatory response and is involved in the process of causing alveolar tissue injury. M2 is involved in wound healing and stopping lung inflammation. Previous studies have shown that activation of 5-hydroxytryptamine (5-HT) signaling is enhanced in pulmonary fibrosis and that 5-HT receptors play an important role in the observed pro-fibrotic effects. As a multifunctional signaling molecule, 5-HT is closely related to lung macrophage polarization, early lung tissue injury, abnormal proliferation and repair, and late extracellular matrix (ECM) deposition. This article reviewed the role of 5-HT and M2 macrophages in the pathogenesis of IPF and the possible regulatory mechanism of 5-HT, in order to provide a reference for further research.
Humans ; Serotonin ; Macrophages ; Lung Diseases, Interstitial/pathology* ; Lung/pathology* ; Idiopathic Pulmonary Fibrosis ; Fibrosis

Pulmonary fibrosis is end-stage of variety of heterogeneous interstitial lung disease, characterizedby excessive proliferation of fibroblasts and extracellular matrix deposition and destruction of lung parenchyma. Thyroid and lung are derived from the same endodermal cells, thyroid hormone affect the occurrence、development and prognosis of the chronic obstructive pulmonary disease, lung cancer and other lung diseases, This article reviews the role and mechanism of thyroid hormone in pulmonary fibrosis in order to provide new idea for the study of the role and mechanism of thyroid hormone in silicosis.
Humans ; Pulmonary Fibrosis/pathology* ; Lung/pathology* ; Silicosis ; Lung Diseases, Interstitial ; Fibroblasts ; Thyroid Hormones ; Fibrosis

Pulmonary fibrosis is the end-stage pathological change of lung diseases, which seriously affects the respiratory function of human body. A large number of studies at home and abroad have confirmed that epithelial-mesenchymal transition (EMT) is an important intermediate stage in the development of pulmonary fibrosis. Inhibition of multiple pathways upstream and downstream of EMT, such as the classical Smads pathway and non-Smads pathway of TGF-1 can effectively inhibit the process of EMT and alleviate pulmonary fibrosis. This article will review the main conclusions of the mechanism of action of EMT as a target to improve the pathology of pulmonary fibrosis so far, and provide a theoretical basis and research direction for further research and development of anti-pulmonary fibrosis drugs.
Humans ; Epithelial-Mesenchymal Transition/drug effects* ; Fibrosis/drug therapy* ; Pulmonary Fibrosis/pathology* ; Signal Transduction ; Transforming Growth Factor beta1/metabolism* ; Antifibrotic Agents/therapeutic use*

Humans ; Diagnosis, Differential ; Idiopathic Pulmonary Fibrosis/pathology* ; Lung/pathology*

Objective: JWH133, a cannabinoid type 2 receptor agonist, was tested for its ability to protect mice from bleomycin-induced pulmonary fibrosis. Methods: By using a random number generator, 24 C57BL/6J male mice were randomly divided into the control group, model group, JWH133 intervention group, and JWH133+a cannabinoid type-2 receptor antagonist (AM630) inhibitor group, with 6 mice in each group. A mouse pulmonary fibrosis model was established by tracheal instillation of bleomycin (5 mg/kg). Starting from the first day after modeling, the control group mice were intraperitoneally injected with 0.1 ml of 0.9% sodium chloride solution, and the model group mice were intraperitoneally injected with 0.1 ml of 0.9% sodium chloride solution. The JWH133 intervention group mice were intraperitoneally injected with 0.1 ml of JWH133 (2.5 mg/kg, dissolved in physiological saline), and the JWH133+AM630 antagonistic group mice were intraperitoneally injected with 0.1 ml of JWH133 (2.5 mg/kg) and AM630 (2.5 mg/kg). After 28 days, all mice were killed; the lung tissue was obtained, pathological changes were observed, and alveolar inflammation scores and Ashcroft scores were calculated. The content of type Ⅰ collagen in the lung tissue of the four groups of mice was measured using immunohistochemistry. The levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in the serum of the four groups of mice were measured using enzyme-linked immunosorbent assay (ELISA), and the content of hydroxyproline (HYP) in the lung tissue of the four groups of mice was measured. Western blotting was used to measure the protein expression levels of type Ⅲ collagen, α-smooth muscle actin (α-SMA), extracellular signal regulated kinase (ERK1/2), phosphorylated P-ERK1/2 (P-ERK1/2), and phosphorylated ribosome S6 kinase type 1 (P-p90RSK) in the lung tissue of mice in the four groups. Real-time quantitative polymerase chain reaction was used to measure the expression levels of collagen Ⅰ, collagen Ⅲ, and α-SMA mRNA in the lung tissue of the four groups of mice. Results: Compared with the control group, the pathological changes in the lung tissue of the model group mice worsened, with an increase in alveolar inflammation score (3.833±0.408 vs. 0.833±0.408, P<0.05), an increase in Ashcroft score (7.333±0.516 vs. 2.000±0.633, P<0.05), an increase in type Ⅰ collagen absorbance value (0.065±0.008 vs. 0.018±0.006, P<0.05), an increase in inflammatory cell infiltration, and an increase in hydroxyproline levels [(1.551±0.051) μg/mg vs. (0.974±0.060) μg/mg, P<0.05]. Compared with the model group, the JWH133 intervention group showed reduced pathological changes in lung tissue, decreased alveolar inflammation score (1.833±0.408, P<0.05), decreased Ashcroft score (4.167±0.753, P<0.05), decreased type Ⅰ collagen absorbance value (0.032±0.004, P<0.05), reduced inflammatory cell infiltration, and decreased hydroxyproline levels [(1.148±0.055) μg/mg, P<0.05]. Compared with the JWH133 intervention group, the JWH133+AM630 antagonistic group showed more severe pathological changes in the lung tissue of mice, increased alveolar inflammation score and Ashcroft score, increased type Ⅰ collagen absorbance value, increased inflammatory cell infiltration, and increased hydroxyproline levels. Compared with the control group, the expression of α-SMA, type Ⅲ collagen, P-ERK1/2, and P-p90RSK proteins in the lung tissue of the model group mice increased, while the expression of type Ⅰ collagen, type Ⅲ collagen, and α-SMA mRNA increased. Compared with the model group, the protein expression of α-SMA (relative expression 0.60±0.17 vs. 1.34±0.19, P<0.05), type Ⅲ collagen (relative expression 0.52±0.09 vs. 1.35±0.14, P<0.05), P-ERK1/2 (relative expression 0.32±0.11 vs. 1.14±0.14, P<0.05), and P-p90RSK (relative expression 0.43±0.14 vs. 1.15±0.07, P<0.05) decreased in the JWH133 intervention group. The type Ⅰ collagen mRNA (2.190±0.362 vs. 5.078±0.792, P<0.05), type Ⅲ collagen mRNA (1.750±0.290 vs. 4.935±0.456, P<0.05), and α-SMA mRNA (1.588±0.060 vs. 5.192±0.506, P<0.05) decreased. Compared with the JWH133 intervention group, the JWH133+AM630 antagonistic group increased the expression of α-SMA, type Ⅲ collagen, P-ERK1/2, and P-p90RSK protein in the lung tissue of mice, and increased the expression of type Ⅲ collagen and α-SMA mRNA. Conclusion: In mice with bleomycin-induced pulmonary fibrosis, the cannabinoid type-2 receptor agonist JWH133 inhibited inflammation and improved extracellular matrix deposition, which alleviated lung fibrosis. The underlying mechanism of action may be related to the activation of the ERK1/2-RSK1 signaling pathway.
Mice ; Male ; Animals ; Pulmonary Fibrosis/pathology* ; Cannabinoid Receptor Agonists/metabolism* ; Collagen Type I/pharmacology* ; Collagen Type III/pharmacology* ; Hydroxyproline/pharmacology* ; Sodium Chloride/metabolism* ; Mice, Inbred C57BL ; Lung/pathology* ; Cannabinoids/adverse effects* ; Bleomycin/metabolism* ; Collagen/metabolism* ; Inflammation/pathology* ; RNA, Messenger/metabolism*

Pneumoconiosis is characterized by chronic lung inflammation and fibrosis, and inflammation can promote pulmonary fibrosis, which in turn leads to pneumoconiosis. When a large shadow with a long diameter of not less than 2 cm and a short diameter of not less than 1 cm appears in the lung, it can be classified as stage Ⅲ pneumoconiosis. This paper reports a case of stage Ⅲ pneumoconiosis with a large shadow in the upper right lung accompanied by burr-like changes misdiagnosed as lung cancer by CT examination.When the large shadow lesions in patients with pneumoconiosis and lung cancer are difficult to distinguish on CT, an additional MRI examination, particularly T(2)W imaging sequence is useful sequence for identifying the two.
Humans ; Pneumoconiosis/pathology* ; Lung/pathology* ; Lung Neoplasms/pathology* ; Pulmonary Fibrosis/pathology* ; Diagnostic Errors