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Carbon black nanoparticles (CBNPs) have been demonstrated to induce DNA damage in epithelial cells. However, the potential of the damage to initiate carcinogenesis and the underlying mechanism remain poorly understood. Therefore, we constructed an in vitro model of malignant transformation of human bronchial epithelial cells (16HBE-T) by treating 40 µg/mL CBNPs for 120 passages. We observed tumor-like transformation and sustained DNA damage. Using transcriptome sequencing and RIP-seq, we identified the overexpression of the critical DNA mismatch repair genes MutS homolog 2 (MSH2) and its related circular RNA, circ_0025373, in the 16HBE-T cells. Mechanistically, circ_0025373 was found to inhibit DNA damage by binding to MSH2, thereby modifying its expression and influencing its nuclear and cytoplasmic distribution, which lead to inhibition of CBNP-induced malignant transformation of human bronchial epithelial cells. Our findings provide novel evidence on the carcinogenicity of CBNPs, and offer biological insights into the potential epigenetic regulation and potential therapeutic targets for lung carcinogenesis.

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The air fryer utilizes heated air rather than hot oil to achieve frying, eliminating the need for cooking oil, rendering it a healthier cooking method than traditional frying and baking. However, there is limited evidence supporting that the air fryer could effectively reduce the level of food-derived carcinogen. In this study, we compared the concentration of Benzo[a]pyrene (BaP), a typical carcinogen, in beef patties cooked using an air fryer and an oven, under different cooking conditions, including temperatures (140 °C, 160 °C, 180 °C, and 200 °C), times (9, 14, and 19 min), and oil added or not. The adjusted linear regression analysis revealed that the BaP concentration in beef cooked in the air fryer was 22.667 (95% CI: 15.984, 29.349) ng/kg lower than that in beef cooked in the oven. Regarding the air fryer, the BaP concentration in beef cooked without oil brushing was below the detection limit, and it was significantly lower than in beef cooked with oil brushing (p < 0.001). Therefore, cooking beef in the air fryer can effectively reduce BaP concentration, particularly due to the advantage of oil-free cooking, suggesting that the air fryer represents a superior option for individuals preparing meat at high temperatures.

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Microplastics (MPs) have received a lot of attention and have been detected in multiple environmental matrices as a new environmental hazard, but studies on human internal exposure to MPs are limited. Here, we collected lung tissue samples from 12 nonsmoking patients to evaluate the characteristics of MPs in human lung tissues using an Agilent 8700 laser infrared imaging spectrometer and scanning electron microscopy. We detected 108 MPs covering 12 types in the lung tissue samples, with a median concentration of 2.19 particles/g. Most of the MPs (88.89%) were sized between 20 to 100 µm. Polypropylene accounts for 34.26% of the MPs in the lung tissues, followed by polyethylene terephthalate (21.30%) and polystyrene (8.33%). Compared with males and those living far from a major road (≥300 m), females and those living near the main road (<300 m) had higher levels of MPs in lung tissues, which positively correlated with platelet (PLT), thrombocytocrit, fibrinogen (FIB), and negatively related with direct bilirubin (DB). These findings help confirm the presence in the respiratory system and suggest the potential sources and health effects of inhaled MPs.

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To investigate the relation of smoking and microplastic inhalation, we conducted a prospective study combining population-based and experimental work. Bronchoalveolar lavage fluid (BALF) samples from 17 smokers and 15 nonsmokers were collected in Zhuhai City, China. We simulated an active smoking model to explore the contribution of smoking to inhaled microplastics. The characteristics of microplastics in BALF samples and cigarette smoke were determined using laser direct infrared spectroscopy. We compared the differences between smokers and nonsmokers as well as between cigarette smoke and control groups. Microplastics were identified positive in all BALF samples. Smokers had higher concentrations of total microplastics (25.86 particles/g), polyurethane (11.34 particles/g), and silicone (1.15 particles/g) than nonsmokers. In the cigarette smoking simulation model, higher concentrations of total microplastics (9.99 particles/L), polyurethane (4.66 particles/L), and silicone (2.78 particles/L) were present in the cigarette smoke than those in the control group. We confirmed and extended the evidence on the presence of microplastics in the lower respiratory tract. These findings also provide new evidence on the relation between cigarette smoking and microplastic inhalation.

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Microplastics (MPs) are abundant in air, but evidence of their deposition in the respiratory tract is limited. We conducted a prospective case series to investigate the deposition of microplastics in bronchoalveolar lavage fluid (BALF) and determine the internal dose of MPs via inhalation. Eighteen never-smokers aged 32-74 years who underwent fiberoptic bronchoscopy with BALF were recruited from Zhuhai, China. Control samples were obtained by performing the same procedure using isotonic saline instead of BALF. Laser direct infrared spectroscopy combined with scanning electron microscopy detected the presence and characteristics of MPs and quantitatively analyzed the microplastic in BALF and control samples. Concentrations of total and specific MPs in BALF and control samples were compared using the Wilcox test. Thirteen types of MPs were observed in 18 BALF samples. Polyethylene (PE, 86.1%) was the most abundant in BALF, followed by poly(ethylene terephthalate) (PET, 7.5%) and polypropylene (PP, 1.9%). Compared with the control samples, BALF had significantly higher concentrations of PE (median [IQR] of BALF: 0.38 [8.05] N/g), PET (0.26 [0.54] N/g), polyurethane (0.16 [0.24] N/g), PP (0.16 [0.11] N/g), and total MPs (0.91 [6.58] N/g). The presence of MPs in BALF provides novel evidence that MPs penetrate deep into the respiratory tract.

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Inhalation of carbon black nanoparticles (CBNPs) can impair lung tissue and cause DNA damage, but the epigenetic mechanism responsible for these effects is still unclear. We explored the role of circular RNAs (circRNAs) in DNA damage induced by CBNPs in the lung. Human bronchial epithelial cell lines (16HBE and BEAS-2B) were treated with 0, 5, 10, 20, 40, or 80 µg/ml CBNPs for 24, 48, and 72 h, and BALB/c mice were exposed to 8 and 80 µg/d CBNPs for 14 days to establish in vitro and vivo models of CBNP exposure, respectively. We found that CBNPs caused DNA double-strand breaks in the lung. Using high-throughput sequencing and quantitative real-time PCR to identify CBNP-related circRNAs, we identified a novel circRNA (circ_0089282) that was overexpressed in the CBNP-exposed group. We used gain-/loss-of-function approaches, RNA pulldown assays, and silver staining to explore the regulatory function of circ_0089282 and its interactions with targeted proteins. We found that circ_0089282 interference could increase CBNP-induced DNA damage, whereas overexpression resulted in the opposite. Circ_0089282 could directly bind to the fused in sarcoma (FUS) protein and positively regulate downstream DNA repair protein DNA ligase 4 (LIG4) through FUS. This regulatory effect of circRNA on DNA damage via promotion of LIG4 illustrated the interactions between genetics and epigenetics in toxicology.

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Mesoporous silica nanoparticles (MSNs) are widely used in many biomedical applications and clinical fields. However, the applications of MSNs are limited by their severe toxicity. Apigenin (AG) has demonstrated pharmacological effects with low toxicity. The aim of this study was to clarify the role of AG in the progression of MSNs-induced renal injury. BALB/c mice and NRK-52E cells were exposed to MSNs with or without AG. AG protected mice and NRK-52E cells from the MSNs-induced pathological variations in renal tissues and decreased cell viability. AG significantly reduced the levels of serum blood urea nitrogen (BUN) and serum creatinine (Scr), upregulated the levels of superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT), and improved the pathological changes of the kidney in MSNs-treated mice. The protective effects of AG were associated with its ability to increase the levels of antioxidants, reduce the accumulation of ROS, and inhibit the expression of the inflammatory mediators (TNF-α, IL-6). In addition, AG treatment upregulated the activity of FOXO3a, increased the level of IkBα, and reduced the nuclear translocation of NF-κB, which ultimately alleviated MSNs-induced inflammation. Nuclear FOXO3a translocation also triggered antioxidant gene transcription and protected nephrocyte from oxidative damage. However, knockdown of FOXO3a significantly blocked the protective effects of AG. These findings suggested that AG could be a promising therapeutic strategy for MSNs-induced nephrotoxicity, and this protective effect might be related to the suppression of oxidative stress and inflammation via the FOXO3a/NF-κB pathway.

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