Maternal nicotine exposure promotes hippocampal CeRNA-mediated excitotoxicity and social barriers in adolescent offspring mice.

Nicotine, an addictive component of cigarettes, causes cognitive defects, particularly when exposure occurs early in life. However, the exact mechanism through which nicotine causes toxicity and alters synaptic plasticity is still not fully understood. The aim of the current study is to examine how non-coding developmental regulatory RNA impacts the hippocampus of mice offspring whose mothers were exposed to nicotine. Female C57BL/6J mice were given nicotine water from one week before pregnancy until end of lactation. Hippocampal tissue from offspring at 20 days post-birth was used for LncRNA and mRNA microarray analysis. Differential expression of LncRNAs and mRNAs associated with neuronal development were screened and validated, and the CeRNA pathway mediating neuronal synaptic plasticity GM13530/miR-7119-3p/mef2c was predicted using LncBase Predicted v.2. Using protein immunoblotting, Golgi staining and behavioral tests, our findings revealed that nicotine exposure in offspring mice increased hippocampal NMDAR receptor, activated receptor-dependent calcium channels, enhanced the formation of NMDAR/nNOS/PSD95 ternary complexes, increased NO synthesis, mediated p38 activation, induced neuronal excitability toxicity. Furthermore, an epigenetic CeRNA regulatory mechanism was identified, which suppresses Mef2c-mediated synaptic plasticity and leads to modifications in the learning and social behavior of the offspring during adolescence. This study uncovers the way in which maternal nicotine exposure results in neurotoxicity in offspring.

Vitamin D3 reverses immune tolerance and enhances the cytotoxicity of effector T cells in coal pneumoconiosis.

Coal worker's pneumoconiosis (CWP) is a common occupational disease that coal miners are highly susceptible due to long-term exposure to coal dust particles (CDP). CWP can induce the accumulation of immune cells surrounding the bronchioles and alveoli in the lungs, resulting in pulmonary fibrosis and compromised immune function. Using single-cell RNA sequencing (scRNA-Seq), our previous studies disclose that CDP exposure triggers heterogeneity of transcriptional profiles in mouse pneumoconiosis, while Vitamin D3 (VitD3) supplementation reduces CDP-induced cytotoxicity; however, the mechanism by which how VitD3 regulates immune status in coal pneumoconiosis remains unclear. In this study, we elucidated the heterogeneity of pulmonary lymphocytes in mice exposed to CDP and demonstrated the therapeutic efficacy of VitD3 using scRNA-Seq dataset. The validation of key lymphocyte markers and their functional molecules was performed using immunofluorescence. The results demonstrated that VitD3 increased the number of naive T cells by modulating CD4 + T cell differentiation and decreased the number of Treg cells in CDP-exposed mice, thereby enhancing the cytotoxic activity of CD8 + effector T cells. These effects markedly alleviated lung fibrosis and symptoms. Taken together, the mechanism by which VitD3 regulates the functions of lymphocytes in CWP provides a new perspective for further research on the prevention and treatment of CWP.

Nicotine suppresses crystalline silica-induced astrocyte activation and neuronal death by inhibiting NF-κB in the mouse hippocampus.

AIMS: Exposure to crystalline silica (CS) in occupational settings induces chronic inflammation in the respiratory system and, potentially, the brain. Some workers are frequently concurrently exposed to both CS and nicotine. Here, we explored the impact of nicotine on CS-induced neuroinflammation in the mouse hippocampus. METHODS: In this study, we established double-exposed models of CS and nicotine in C57BL/6 mice. To assess depression-like behavior, experiments were conducted at 3, 6, and 9 weeks. Serum inflammatory factors were analyzed by ELISA. Hippocampus was collected for RNA sequencing analysis and examining the gene expression patterns linked to inflammation and cell death. Microglia and astrocyte activation and hippocampal neuronal death were assessed using immunohistochemistry and immunofluorescence staining. Western blotting was used to analyze the NF-κB expression level. RESULTS: Mice exposed to CS for 3 weeks showed signs of depression. This was accompanied by elevated IL-6 in blood, destruction of the blood-brain barrier, and activation of astrocytes caused by an increased NF-κB expression in the CA1 area of the hippocampus. The elevated levels of astrocyte-derived Lcn2 and upregulated genes related to inflammation led to higher neuronal mortality. Moreover, nicotine mitigated the NF-κB expression, astrocyte activation, and neuronal death, thereby ameliorating the associated symptoms. CONCLUSION: Silica exposure induces neuroinflammation and neuronal death in the mouse hippocampal CA1 region and depressive behavior. However, nicotine inhibits CS-induced neuroinflammation and neuronal apoptosis, alleviating depressive-like behaviors in mice.

Nicotine exposure exacerbates silica-induced pulmonary fibrosis via STAT3-BDNF-TrkB-mediated epithelial-mesenchymal transition in alveolar type II cells.

The addictive substance nicotine, found in cigarettes and some e-cigarettes, plays a vital role in pro-inflammatory and fibrotic processes. However, the part played by nicotine in the progression of silica-induced pulmonary fibrosis is poorly understood. We used mice exposed to both silica and nicotine to investigate whether nicotine synergizes with silica particles to worsen lung fibrosis. The results revealed that nicotine accelerated the development of pulmonary fibrosis in silica-injured mice by activating STAT3-BDNF-TrkB signalling. Mice with a history of exposure to nicotine showed an increase in Fgf7 expression and alveolar type II cell proliferation if they were also exposed to silica. However, newborn AT2 cells could not regenerate the alveolar structure and release pro-fibrotic factor IL-33. Moreover, activated TrkB induced the expression of p-AKT, which promotes the expression of epithelial-mesenchymal transcription factor Twist, but no Snail. In vitro assessment confirmed activation of the STAT3-BDNF-TrkB pathway in AT2 cells, exposed to nicotine plus silica. In addition, TrkB inhibitor K252a downregulated p-TrkB and the downstream p-AKT and restricted the epithelial-mesenchymal transition caused by nicotine plus silica. In conclusion, nicotine activates the STAT3-BDNF-TrkB pathway, which promotes epithelial-mesenchymal transition and exacerbates pulmonary fibrosis in mice with combined exposure to silica particles and nicotine.

Using Nicotine in A Silica-Exposed Mouse Model to Promote Lung Epithelial-Mesenchymal Transition.

Smoking and exposure to silica are common among occupational workers, and silica is more likely to injure the lungs of smokers than non-smokers. The role of nicotine, the primary addictive ingredient in cigarettes, in silicosis development is unclear. The mouse model employed in this study was simple and easily controlled, and it effectively simulated the effects of chronic nicotine ingestion and repeated exposure to silica on lung fibrosis through epithelial-mesenchymal transition in human beings. In addition, this model can help in the direct study of the effects of nicotine on silicosis while avoiding the effects of other components in cigarette smoke. After environmental adaptation, mice were injected subcutaneously with 0.25 mg/kg nicotine solution into the loose skin over the neck every morning and evening at 12 h intervals over 40 days. Additionally, crystalline silica powder (1-5 µm) was suspended in normal saline, diluted to a suspension of 20 mg/mL, and dispersed evenly using an ultrasonic water bath. The isoflurane-anesthetized mice inhaled 50 µL of this silica dust suspension through the nose and were awoken via chest massage. Silica exposure was administrated daily on days 5-19. The double-exposed mouse model was exposed to nicotine and then silica, which matches the exposure history of workers who are exposed to both harmful factors. In addition, nicotine promoted pulmonary fibrosis through epithelial-mesenchymal transformation (EMT) in mice. This animal model can be used to study the effects of multiple factors on the development of silicosis.

A Silicosis Mouse Model Established by Repeated Inhalation of Crystalline Silica Dust.

Silicosis can be caused by exposure to respiratory crystalline silica dust (CSD) in an industrial environment. The pathophysiology, screening, and treatment of silicosis in humans have all been extensively studied using the mouse silicosis model. By repeatedly making mice inhale CSD into their lungs, the mice can mimic the clinical symptoms of human silicosis. This methodology is practical and efficient in terms of time and output and does not cause mechanical injury to the upper respiratory tract due to surgery. Furthermore, this model can successfully mimic acute/chronic transformation process of silicosis. The main procedures were as follows. The sterilized 1-5 µm CSD powder was fully ground, suspended in saline, and dispersed in an ultrasonic water bath for 30 min. Mice under isoflurane-induced anesthesia switched from shallow rapid breathing to deep, slow aspiration for approximately 2 s. The mouse was placed in the palm of a hand, and the thumb tip gently touched the lip edge of the mouse's jaw to straighten the airway. After each exhalation, the mice breathed in the silica suspension drop by drop through one nostril, completing the process within 4-8 s. After the mice's breathing had stabilized, their chest was stroked and caressed to prevent the inhaled CSD from being coughed up. The mice were then returned to the cage. In conclusion, this model can quantify CSD along the typical physiological passage of tiny particles into the lung, from the upper respiratory tract to the terminal bronchioles and alveoli. It can also replicate the recurrent exposure of employees due to work. The model can be performed by one person and does not need expensive equipment. It conveniently and effectively simulates the disease features of human silicosis with high repeatability.

VX-765 attenuates silica-induced lung inflammatory injury and fibrosis by modulating alveolar macrophages pyroptosis in mice.

Silicosis is a diffuse fibrotic lung disease in which excessive inflammatory responses are triggered by silica exposure. Pyroptosis, a pro-inflammatory mode of programmed cell death, is mediated by gasdermin and may play a pivotal role in the development of silicosis. The caspase-1 inhibitor, VX-765, was used in vivo and in vitro to investigate the effects of silica-induced early inflammatory injury and later lung fibrosis. Our findings show that VX-765 reduces inflammatory lung injury by inhibiting silica-induced pyroptosis of alveolar macrophages in a silicosis mouse model. VX-765 limits the infiltration of inflammatory M1 alveolar macrophages, decreasing expression of inflammatory cytokines, including IL-1ß, TNF-α, IL-6, CCL2, and CCL3, and down-regulating endogenous DAMPs and inflammatory immune-related cell pattern recognition receptors TLR4 and NLRP3. Furthermore, VX-765 alleviates fibrosis by down-regulating α-smooth muscle actin (α-SMA), collagen, and fibronectin. In this study, we illustrate that Alveolar macrophages pyroptosis occur in the early stages of silicosis, and VX-765 can alleviate the development of silicosis by inhibiting the pyroptosis signaling pathway. These results may provide new insight into the prevention and treatment of early-stage silicosis.

C-X-C-Chemokine-Receptor-Type-4 Inhibitor AMD3100 Attenuates Pulmonary Inflammation and Fibrosis in Silicotic Mice.

Background: Silicosis is a severe pulmonary disease caused by inhaling dust containing crystalline silica. The progression of silicosis to pulmonary fibrosis is usually unavoidable. Recent studies have revealed positivity for the overexpression of C-X-C chemokine receptor type 4 (CXCR4) in pulmonary fibrosis and shown that the CXCR4 inhibitor AMD3100 attenuated pulmonary fibrosis after bleomycin challenge and paraquat exposure. However, it is unclear whether AMD3100 reduces crystalline silica-induced pulmonary fibrosis. Methods: C57BL/6 male mice were instilled intranasally with a single dose of crystalline silica (12 mg/60 µL) to establish an acute silicosis mouse model. Twelve hours later, the mice were injected intraperitoneally with 5 mg/kg AMD3100 or control solution. Then, the mice were weighed daily and sacrificed on day 7, 14, or 28 to collect lung tissue and peripheral blood. Western blotting was also applied to determine the level of CXCR4, while different histological techniques were used to assess pulmonary inflammation and fibrosis. In addition, the level of B cells in peripheral blood was measured by flow cytometry. Results: CXCR4 and its ligand CXCL12 were upregulated in the lung tissues of crystalline silica-exposed mice. Blocking CXCR4 with AMD3100 suppressed the upregulation of CXCR4/CXCL12, reduced the severity of lung injury, and prevented weight loss. It also inhibited neutrophil infiltration at inflammatory sites and neutrophil extracellular trap formation, as well as reduced B-lymphocyte aggregates in the lung. Additionally, it decreased the recruitment of circulating fibrocytes (CD45+collagen I+CXCR4+) to the lung and the deposition of collagen I and α-smooth muscle actin in lung tissue. AMD3100 also increased the level of B cells in peripheral blood, preventing circulating B cells from migrating to the injured lungs. Conclusion: Blocking CXCR4 with AMD3100 delays pulmonary inflammation and fibrosis in a silicosis mouse model, suggesting the potential of AMD3100 as a drug for treating silicosis.

Inflammation and fibrosis in the coal dust-exposed lung described by confocal Raman spectroscopy.

Background: Coal workers' pneumoconiosis (CWP) is an occupational disease that severely damages the life and health of miners. However, little is known about the molecular and cellular mechanisms changes associated with lung inflammation and fibrosis induced by coal dust. As a non-destructive technique for measuring biological tissue, confocal Raman spectroscopy provides accurate molecular fingerprints of label-free tissues and cells. Here, the progression of lung inflammation and fibrosis in a murine model of CWP was evaluated using confocal Raman spectroscopy. Methods: A mouse model of CWP was constructed and biochemical analysis in lungs exposed to coal dust after 1 month (CWP-1M) and 3 months (CWP-3M) vs control tissues (NS) were used by confocal Raman spectroscopy. H&E, immunohistochemical and collagen staining were used to evaluate the histopathology alterations in the lung tissues. Results: The CWP murine model was successfully constructed, and the mouse lung tissues showed progression of inflammation and fibrosis, accompanied by changes in NF-κB, p53, Bax, and Ki67. Meanwhile, significant differences in Raman bands were observed among the different groups, particularly changes at 1,248, 1,448, 1,572, and 746 cm-1. These changes were consistent with collagen, Ki67, and Bax levels in the CWP and NS groups. Conclusion: Confocal Raman spectroscopy represented a novel approach to the identification of the biochemical changes in CWP lungs and provides potential biomarkers of inflammation and fibrosis.

Label-free Raman spectroscopy characterizes signatures of inflammation and fibrosis in the silicosis.

Silicosis is an occupational disease that seriously damages the life and health of miners. Herein, we constructed a mouse model of silicosis and used label-free confocal Raman spectroscopy to analyze the biomolecular variations in lung fibrous nodules and inflammatory sites. The mice were exposed to silica particles for 1 month (SIL-1M group), 3 months (SIL-3M group), or no exposure (control tissues, NS). Raman spectra obtained from treated and untreated lung tissue were subjected to chemometric analysis to quantify biochemical composition differences in the silicosis. Simultaneously, immunohistochemistry and collagen staining were used to evaluate inflammation, fibrosis, and apoptosis. As a result, the SIL-1M and SIL-3M groups showed significant differences in cholesterol, lipids, amino acids, nucleic acids, and cytochrome C, and the collagen peaks at 1248 cm-1 and 1448 cm-1 were significantly higher than in the NS group. Notably, glycogen and phospholipid may be an inflammatory indicator consistent with NF-κB expression. In addition, significant differences in collagen and cytochrome C content in silicosis lung tissue were found using Raman spectroscopy and were verified by Masson's staining and Bax/Bcl-2 expression ratio. In summary, our findings provide a label-free technique to understand the biochemical changes in lung inflammatory and fibrosis microenvironment after exposure to silica particles and provide a valuable reference for studying the mechanism of silicosis.

Vitamin D3 suppresses astrocyte activation and ameliorates coal dust-induced mood disorders in mice.

BACKGROUND: Pneumoconiosis patients exhibit significantly more anxiety and depression than healthy individuals. However, the mechanism of coal dust-induced anxiety and depression remains unclear. METHODS: A pneumoconiosis mouse model with anxiety- and depression-like behaviors were established after 28 days of exposure to coal dust. Vitamin D3 treatment (1200 IU/kg/week) was administered intraperitoneally for 3 months starting from the first coal exposure. Tail suspension test (TST), open field test (OFT), and elevated plus-maze (EPM) test were used to assess anxiety- and depression-like behaviors. Theserum concentration of 25(OH)D3 and fibrillary acid protein (GFAP) expression were determined. In addition, the morphology and distribution of GFAP and neurogenic differentiation factor1 expression (NeuroD1) in different cerebral hippocampus were observed. RESULTS: In coal dust-exposed mice, immobility time decreased in OFT and increased in TST,and the frequency of entering the open arm decreased in the EPM compared with the control mice. Coal dust increased hippocampal GFAP expression and astrocyte activation and reduced neurogenic differentiation factor1 expression (NeuroD1). In addition, Vitamin D3 significantly alleviated anxiety- and depressive-like behaviors in TST and EPM test, decreased GFAP expression level, modified hippocampal astrocyte activation pattern, and advanced brain-derived neurotrophic factor (BDNF) distribution and expression in CA1 and CA3 of the hippocampus. CONCLUSIONS: Taken together, our results suggest that, by inhibiting the over-activation of astrocytes and increasing BDNF and neuron protection, vitamin D treatment ameliorates coal-dust-induced depressive and anxiety-like behavior, which is the first evidence that vitamin D may be a new approach for treating mood disorders caused by particulate matter.

Coal dust exposure triggers heterogeneity of transcriptional profiles in mouse pneumoconiosis and Vitamin D remedies.

BACKGROUND: Coal dust particles (CDP), an inevitable by-product of coal mining for the environment, mainly causes coal workers' pneumoconiosis (CWP). Long-term exposure to coal dust leads to a complex alternation of biological processes during regeneration and repair in the healing lung. However, the cellular and complete molecular changes associated with pulmonary homeostasis caused by respiratory coal dust particles remain unclear. METHODS: This study mainly investigated the pulmonary toxicity of respirable-sized CDP in mice using unbiased single-cell RNA sequencing. CDP (< 5 µm) collected from the coal mine was analyzed by Scanning Electron Microscope (SEM) and Mass Spectrometer. In addition, western blotting, Elisa, QPCR was used to detect gene expression at mRNA or protein levels. Pathological analysis including HE staining, Masson staining, immunohistochemistry, and immunofluorescence staining were performed to characterize the structure and functional alternation in the pneumoconiosis mouse and verify the reliability of single-cell sequencing results. RESULTS: SEM image and Mass Spectrometer analysis showed that coal dust particles generated during coal mine production have been crushed and screened with a diameter of less than 5 µm and contained less than 10% silica. Alveolar structure and pulmonary microenvironment were destroyed, inflammatory and death (apoptosis, autophagy, and necrosis) pathways were activated, leading to pneumoconiosis in post 9 months coal dust stimulation. A distinct abnormally increased alveolar type 2 epithelial cell (AT2) were classified with a highly active state but reduced the antimicrobial-related protein expression of LYZ and Chia1 after CDP exposure. Beclin1, LC3B, LAMP2, TGF-ß, and MLPH were up-regulated induced by CDP, promoting autophagy and pulmonary fibrosis. A new subset of macrophages with M2-type polarization double expressed MLPH + /CD206 + was found in mice having pneumoconiosis but markedly decreased after the Vitamin D treatment. Activated MLPH + /CD206 + M2 macrophages secreted TGF-ß1 and are sensitive to Vitamin D treatment. CONCLUSIONS: This is the first study to reconstruct the pathologic progression and transcriptome pattern of coal pneumoconiosis in mice. Coal dust had obvious toxic effects on lung epithelial cells and macrophages and eventually induced pulmonary fibrosis. CDP-induced M2-type macrophages could be inhibited by VD, which may be related to the alleviation of the pulmonary fibrosis process.

A suitable silicosis mouse model was constructed by repeated inhalation of silica dust via nose.

Silicosis as the serious occupational disease is highly necessary to construct a suitable mouse model for disclosing mechanism of occurrence and development in this disease. Here, the volume-effect relationship and volume-based survival curves in mice who inhaled silica suspension intranasally were analyzed. Notable, the optimal volume 80 µl repeated-inhalation by nose to silica suspension in the inbred mouse C57BL/6 J with the highest susceptibility to silicosis led to a great entrance into the lung and a high survival rate after instillation. After repeated-exposure to 20 mg/mL, 80 µl silica for 16 days and then fed without silica exposure until 31 days, weight of mice showed a trend of first decrease and then recover. Moreover, the degree of pulmonary inflammation and fibrosis in mice were analyzed by pathological and immunohistochemistry staining. Transforming growth factor-beta (TGF-ß), smooth muscle alpha-actin (α-SMA) and collagen type-I (collagen I, Col-I) were significantly increased in the silica-exposed mouse lung at post-exposure day 16 compared with the controls. Sirius red stain and Micro-CT analysis showed that lung fibrosis formed at post-exposure day 31. This study highlights the critical importance of perfusion volume and repeated nasal drops in inducing inflammatory response and pulmonary fibrosis in silicosis.