Inhaled polystyrene microplastics impaired lung function through pulmonary flora/TLR4-mediated iron homeostasis imbalance.

Microplastics (MPs) have been found in the air, human nasal cavity, and lung, suggesting that the respiratory tract is one of the important exposure routes for MPs. The lung is a direct target organ for injury from inhaled MPs, but data on lung injury from longer-term exposure to environmental doses of MPs are limited, and the mechanisms remain unclear. Here, C57BL/6 J mice were treated with 5 µm polystyrene (PS)-MPs by intratracheal instillation (0.6, 3, and 15 mg/kg) for 60 days to establish MPs exposure model. We found that PS-MPs lead to increased collagen fibers and decreased lung barrier permeability and lung function in lung tissue. Mechanistically, the abundance of gram-negative bacteria in the pulmonary flora increased after inhalation of PS-MPs, causing lipopolysaccharide (LPS) release. The expression of Toll-like receptor 4 (TLR4), the key receptor of LPS, was increased, and ferroptosis occurred in lung tissue cells. Further in vitro intervention experiments were performed, pulmonary flora/TLR4-induced imbalance of lung iron homeostasis is an important mechanism of PS-MPs-induced lung injury. Our study provides new evidence for lung injury caused by environmental doses of MPs and strategies to prevent it through longer-term dynamic observation.

Cuproptosis is involved in decabromodiphenyl ether-induced ovarian dysfunction and the protective effect of melatonin.

Decabromodiphenyl ether (BDE-209) has been universally detected in environmental media and animals, but its damage to ovarian function and mechanism is still unclear, and melatonin has been shown to improve mammalian ovarian function. This study aimed to investigate the toxic effects of BDE-209 on the ovary and tried to improve ovarian function with melatonin. Herein, BDE-209 was administered orally to female SD rats for 60 days. Enzyme-linked immunosorbent assay, HE staining, transcriptome analysis, qPCR and immunohistochemical staining were used to explore and verify the potential mechanism. We found that BDE-209 exposure had effects on the ovary, as shown by abnormal changes in the estrous cycle, hormone levels and ovarian reserve function in rats, while increasing the proportion of collagen fibres in ovarian tissue. In terms of mechanism, cuproptosis, a form of cell death, was identified to play a crucial role in BDE-209-induced ovarian dysfunction, with the phenotype manifested as copper salt accumulation in ovary, downregulation of glutathione pathway metabolism and copper transfer molecule (ATP7A/B), and upregulation of FDX1, lipoic acid pathway (LIAS, LIPT1), pyruvate dehydrogenase complex components (DLAT, PDHB, PDHA1), and copper transfer molecule (SLC31A1). Furthermore, possible interventions were explored. Notably, a supplement with melatonin has a repair effect on the damage to ovarian function by reversing the gene expression of cuproptosis-involved molecules. Overall, this study revealed that cuproptosis is involved in BDE-209-induced ovarian damage and the beneficial effect of melatonin on ovarian copper damage, providing evidence for the prevention and control of female reproductive damage induced by BDE-209.

Gut microbiota-palmitoleic acid-interleukin-5 axis orchestrates benzene-induced hematopoietic toxicity.

Due to the annual increase in its production and consumption in occupational environments, the adverse blood outcomes caused by benzene are of concern. However, the mechanism of benzene-induced hematopoietic damage remains elusive. Here, we report that benzene exposure causes hematopoietic damage in a dose-dependent manner and is associated with disturbances in gut microbiota-long chain fatty acids (LCFAs)-inflammation axis. C57BL/6J mice exposed to benzene for 45 days were found to have a significant reduction in whole blood cells and the suppression of hematopoiesis, an increase in Bacteroides acidifaciens and a decrease in Lactobacillus murinus. Recipient mice transplanted with fecal microbiota from benzene-exposed mice showed potential for hematopoietic disruption, LCFAs, and interleukin-5 (IL-5) elevation. Abnormally elevated plasma LCFAs, especially palmitoleic acid (POA) exacerbated benzene-induced immune-inflammation and hematopoietic damage via carnitine palmitoyltransferase 2 (CPT2)-mediated disorder of fatty acid oxidation. Notably, oral administration of probiotics protects the mice against benzene-induced hematopoietic toxicity. In summary, our data reveal that the gut microbiota-POA-IL-5 axis is engaged in benzene-induced hematopoietic damage. Probiotics might be a promising candidate to prevent hematopoietic abnormalities from benzene exposure.

Probiotics ameliorate benzene-induced systemic inflammation and hematopoietic toxicity by inhibiting Bacteroidaceae-mediated ferroptosis.

The intestinal microbiota is associated with the development of benzene-induced hematopoietic toxicity. Modulation of intestinal homeostasis by probiotic supplementation has been considered an effective strategy to prevent adverse health effects. However, the role and mechanism of probiotics in benzene-induced hematopoietic toxicity are unclear. After 45 days of exposure, benzene caused bone marrow hematopoietic toxicity in mice. Furthermore, we found that benzene altered the intestinal barrier in mice, leading to an increase in the abundance of Bacteroidaceae and the activation of systemic inflammation. Interestingly, Fe2+ accumulation, lipid peroxidation, and differential expression of ferroptosis proteins were observed in the intestinal tissues of benzene-exposed mice. After fecal microbiota transplantation, stool microbes from benzene-exposed mice led to the development of intestinal ferroptosis in recipient mice. In particular, oral probiotics significantly reversed elevated Bacteroidaceae and intestinal ferroptosis, ultimately improving benzene-induced hematopoietic damage. We further used the benzene metabolite 1,4-BQ to treat human normal colonic epithelial cells (NCM460) and intervened with the ferroptosis inhibitor liproxstatin-1 (Lip-1) to validate the relationship between intestinal ferroptosis and inflammation. The results showed that 1,4-BQ treatment resulted in increased intracellular ROS levels and abnormal expression of ferroptosis proteins and the inflammatory factors IL-5 and IL-13. However, the use of Lip-1 significantly inhibited oxidative stress, ferroptosis, and inflammation in NCM460 cells. This result suggested that ferroptosis might be involved in benzene-induced hematopoietic toxicity by mediating Th2-type systemic inflammation. Overall, these findings revealed a role for Bacteroidaceae-intestinal ferroptosis-inflammation in benzene-induced hematopoietic toxicity and highlighted that probiotics could be a promising strategy to prevent adverse hematologic outcomes.

The gut-brain axis involved in polystyrene nanoplastics-induced neurotoxicity via reprogramming the circadian rhythm-related pathways.

The production of plastic is still increasing globally, which has led to an increasing number of plastic particles in the environment. Nanoplastics (NPs) can penetrate the blood-brain barrier and induce neurotoxicity, but in-depth mechanism and effective protection strategies are lacking. Here, C57BL/6 J mice were treated with 60 µg polystyrene NPs (PS-NPs, 80 nm) by intragastric administration for 42 days to establish NPs exposure model. We found that 80 nm PS-NPs could reach and cause neuronal damage in the hippocampus, and alter the expression of neuroplasticity-related molecules (5-HT, AChE, GABA, BDNF and CREB), and even affect the learning and memory ability of mice. Mechanistically, combined with the results of hippocampus transcriptome, gut microbiota 16 s ribosomal RNA and plasma metabolomics, we found that the gut-brain axis mediated circadian rhythm related pathways were involved in the neurotoxicity of NPs, especially Camk2g, Adcyap1 and Per1 may be the key genes. Both melatonin and probiotic can significantly reduce intestinal injury and restore the expression of circadian rhythm-related genes and neuroplasticity molecules, and the intervention effect of melatonin is more effective. Collectively, the results strongly suggest the gut-brain axis mediated hippocampal circadian rhythm changes involved in the neurotoxicity of PS-NPs. Melatonin or probiotics supplementation may have the application value in the prevention of neurotoxicity of PS-NPs.

[Effects of fine particulate matter on cognitive function and gut microbiota in adult male mice].

OBJECTIVE: To study the effects of fine particulate matter(PM_(2.5))exposure to cognitive function and intestinal flora abundance and diversity in adult male mice. METHODS: The SPF grade male C57 BL/6 J mice with 8 weeks old were randomly divided into control group(NS group), PM_(2.5) exposure group(PM_(2.5) group), probiotic group(VSL#3 group) and PM_(2.5) + VSL#3 group(PMV group), with 8 mice in each group. The PM_(2.5) group and PMV group mice were exposed to PM_(2.5) using animal exposure system equipped with real-time PM_(2.5) concentration, and concentrated 6 times the outdoor PM_(2.5) concentration, 8 h every day, 5 d every week for 4 weeks. The VSL#3 group and PMV group mice were given VSL#3, 0.5 mL, 2×10~9 CFU/mL. After four weeks of exposure, feces from mice were collected for 16 s rRNA high-throughput sequencing, and the cognitive function was evaluated using Morris water maze and object recognition experiments. RESULTS: The escape latency of PM_(2.5) group in four-day training [(54.99±6.77) s, (41.21±9.98) s, (36.27±13.11) s, (30.01±14.80) s] were higher than that of NS group [(32.19±4.59) s, (20.50±6.77) s, (19.93±7.30) s, (16.94±9.91) s], and the difference were statistically significant(P<0.05). The escape latency of PMV group on the first and second day of training [(39.02±6.23) s, (28.83±9.53) s] were lower than that of PM_(2.5) group(P<0.05). The target quadrant residence time of mice in PM_(2.5) group [(18.30± 8.88) s] was lower than that in NS group and PMV group [(30.53±9.10) s, (30.00±10.61) s]. Compared with NS group(6.09±0.40), the shannon index of PM_(2.5) group and PMV group(5.05±0.65 and 5.46±0.52) were significantly reduced(P<0.05). The target quadrant time was positively correlated with the relative abundance of Actinomyces(r=0.576, P<0.05), and the recognition index was positively correlated with the relative abundance of Firmicutes(r=0.612, P<0.05). CONCLUSION: PM_(2.5) could lead to cognitive dysfunction in mice, which is related to diversity and abundance of the intestinal flora. Probiotic can improve cognitive function.

[Renal damage of indium sulfate on rats].

OBJECTIVE: To study the renal damage of indium sulfate. METHODS: 32 healthy Wistar rats were randomly and equally divided into 3 dose groups( 52. 3 mg/kg、104. 6 mg/kg 261. 4 mg/kg) and one negative control group. Indium sulfate were orally given once a day successively 5 days a week for 8 weeks. Each group of rats was collected24 hour urine after the end of the posion. We tested the content of Cr, BUN, T-AOC, ALB in serum and the GSH activity in kidney by kids and detected the ß2-MG content in serum and urine by ELISA test. Inductively coupled plasma mass spectrometry( ICP-MS)method was used to detect the content of indium in whole blood, urine and kidney tissue of rats. Hematoxylin and eosin( H&E) staining was used to detect histological changes. RESULTS: During the experiment, all the rats were normal in activities, feed and drinking water, and they developed stably. In the period of seventh weeks and eighth weeks, the body weight of rats in high dose group was significantly lower than the control group( P <0. 05). Compared with the control group[( 1. 27 ± 0. 55), ( 0. 40 ± 0. 01) and( 0. 30 ±0. 06) µg/L], 3 dose group of indium in blood[( 44. 10 ± 23. 10), ( 52. 08 ± 21. 03) and( 67. 42 ± 45. 98) µg/L], urine[( 0. 72 ± 0. 13), ( 2. 75 ± 0. 15) and( 4. 31 ± 0. 33)µg/L]and kidney [( 1. 36 ± 0. 83), ( 1. 52 ± 0. 49) and( 2. 87 ± 0. 20) µg/L] were significantly increased( P < 0. 05). The level of Cr in serum in the high dose group were significantly higher than that in the control group [( 66. 06 ± 18. 62) and( 46. 53 ± 7. 95)µmol/L, P < 0. 05], the serum BUN content[( 3. 98 ± 0. 82) and( 4. 09 ± 0. 71) mmol/L] in the high dose group and middle dose group were significantly lower than the control group [( 4. 77 ± 0. 49) mmol/L, P < 0. 05]. Compared with the control group, 3 dose group of the ß2-MG in serum and urine were significantly increased( P < 0. 05), and the level of T-AOC[( 4. 87 ± 2. 36), ( 4. 50 ± 2. 33) and( 4. 00 ± 3. 29) U/m L] in serum and GSH[( 6. 41 ± 1. 86), ( 5. 06 ± 2. 09) and( 2. 77 ± 2. 64) µmol/( g prot) ] in renal tissue were significantly decreased[( 15. 20 ± 5. 43) U/m L and( 14. 74 ± 6. 47) µmol/( g prot), P < 0. 05]. Compared with the control group, the middle and high dose exposure group had significant inflammatory pathological changes, mainly manifested as glomerular swelling, renal tubular structure abnormalities and inflammatory cell infiltration. CONCLUSION: Indium sulfate can cause the accumulation of indium in the kidney, oxidative damage, pathological changes and dysfunction in the kidney of rats.

[Genotoxic damage induced by indium chloride on rat].

OBJECTIVE: To investigate the genotoxic effect of indium chloride using the in vivo bone marrow micronucleus test, and to provide scientific basis for the evaluation of the toxicity of indium compounds. METHODS: Thirty two healthy male adult SPF Wistar rats were selected and randomly divided into four groups( control group, 0. 065, 0. 65, 1. 3 mg/kg group). Rats were treated with indium chloride using non exposed endotracheal injection method. Hematoxylin and eosin( H&E) staining was used to detect histological changes. Oxidative stress status relative to lung damage in rats was evaluated by detecting superoxide dismutase( SOD) and maleic dialdehyde( MDA) activities. The frequency of micronuclei was determined at the end of each culture period. Inductively coupled plasma mass spectrometry( ICP-MS) method was used to detect the content of indium in whole blood and lung tissue of rats. RESULTS: The content of indium in whole blood and lung tissue of rats and the micronucleus rate in rats exposed to indium chloridewere significantly higher than those in the control group( P < 0. 01). The MDA content in the lung tissue of rats in middle and high dose group was significantly increased( P <0. 05), while SOD level was significantly lower than that in control group( P < 0. 05);Pathological changes of lung tissue showed that after exposure to indium chloride, inflammatory cell exudation was present in the alveolar cavity and surrounding areas of the trachea were apparent. Alveolar lumen was filled with intraalveolar proteinaceous material. CONCLUSION: Indium chloride exposure will cause the accumulation of indium in blood and lung, bone marrow micronucleus rate increased, occurrence of oxidative damage and pathological changes.