Heterozygous Disruption of Beclin 1 Alleviates Zinc Oxide Nanoparticles-Induced Disturbance of Cholesterol Biosynthesis in Mouse Liver

Mechanistic insights into zinc oxide nanoparticles induced embryotoxicity via H3K9me3 modulation

The widespread application of nanoparticles (NPs) in various fields has raised health concerns, especially in reproductive health. Our research has shown zinc oxide nanoparticles (ZnONPs) exhibit the most significant toxicity to pre-implantation embryos in mice compared to other common NPs. In patients undergoing assisted reproduction technology (ART), a significant negative correlation was observed between Zn concentration and clinical outcomes. Therefore, this study explores the impact of ZnONPs exposure on pre-implantation embryonic development and its underlying mechanisms. We revealed that both in vivo and in vitro exposure to ZnONPs impairs pre-implantation embryonic development. Moreover, ZnONPs were found to reduce the pluripotency of mouse embryonic stem cells (mESCs), as evidenced by teratoma and diploid chimera assays. Employing multi-omics approaches, including RNA-Seq, CUT&Tag, and ATAC-seq, the embryotoxicity mechanisms of ZnONPs were elucidated. The findings indicate that ZnONPs elevate H3K9me3 levels, leading to increased heterochromatin and consequent inhibition of gene expression related to development and pluripotency. Notably, Chaetocin, a H3K9me3 inhibitor, sucessfully reversed the embryotoxicity effects induced by ZnONPs. Additionally, the direct interaction between ZnONPs and H3K9me3 was verified through pull-down and immunoprecipitation assays. Collectively, these findings offer new insights into the epigenetic mechanisms of ZnONPs toxicity, enhancing our understanding of their impact on human reproductive health.

Heterozygous disruption of beclin 1 alleviates neurotoxicity induced by sub-chronic exposure of arsenite in mice

Arsenite is a well-documented neurotoxicant that widely exists in the environment. However, the detailed mechanisms of arsenite neurotoxicity are not fully clarified. Autophagy has been reported to be involved in many neurological problems induced by arsenite. Since beclin 1 is an essential mediator of autophagy, we herein used both adult wild-type (beclin 1^+/+) and heterozygous disruption of beclin 1 (beclin 1^+/-) mice for chronic administration of 50 mg/L arsenite via drinking water for 3 months. Our results demonstrated that exposure of arsenite caused the working memory deficit, anxiety-like behavior and motor coordination disorder in beclin 1^+/+ mice, accompanied with pathological changes in morphology and electrophysiology in the cortical tissues. This treatment of arsenite significantly reduced the number of neuronal cells and induced microglia activation and synaptic transmission disorders in the wild-type mice as compared with vehicle controls. Intriguingly, by using beclin 1^+/- mice, we found that heterozygous disruption of beclin 1 profoundly attenuated these neurotoxic effects induced by arsenite, mainly manifested by improvements in the neurobehavioral impairments, abnormal electrophysiologic alterations as well as dysregulation of synaptic transmission. These findings together indicate that regulation of autophagy via beclin 1 would be a potential strategy for treatment against arsenite neurotoxicity.

Prognostic value of lipid profile in adult hemophagocytic lymphohistiocytosis

Background

Adult secondary hemophagocytic lymphohistiocytosis (sHLH) is a rare clinical syndrome with a high mortality rate. Currently, there are no feasible prognostic factors to clinically predict untreated sHLH patients' prognosis. Our objective was to characterize the lipid profile of adult sHLH patients and to determine the relationship with overall survival.

Methods

We retrospectively analyzed 247 patients with newly diagnosed sHLH from January 2017 to January 2022 according to the HLH-2004 criteria. Multivariate Cox regression analyses and restricted cubic splines were conducted to evaluate the prognostic value of the lipid profile.

Results

The median age of all patients was 52 years, and the commonest cause of sHLH in our cohort was malignancy. During a median follow-up of 88 (interquartile ranges, 22-490) days, 154 deaths occurred. The univariate analysis confirmed total cholesterol (TC) ≤ 3 mmol/L, triglycerides (TG) > 3.08 mmol/L, high-density lipoprotein cholesterol (HDL-c) ≤ 0.52 mmol/L, and low-density lipoprotein cholesterol (LDL-c) ≤ 2.17 mmol/L were associated with an inferior survival. In a multivariate model, HDL-c, hemoglobin, platelet, fibrinogen, and soluble interleukin-2 receptor were considered as independent factors. Additionally, the restricted cubic spline analyses indicated an inverse linear association between HDL-c and the risk of mortality in sHLH.

Conclusion

Lipid profiles, which were low-cost and readily available promising biomarkers, were strongly associated with the overall survival in adult sHLH patients.

Beclin1 Deficiency Suppresses Epileptic Seizures

Epilepsy is a common disease of the nervous system. Autophagy is a degradation process involved in epilepsy, and in turn, seizures can activate autophagy. Beclin1 plays a critical role in autophagy and participates in numerous physiological and pathological processes. However, the mechanism underlying the effect of Beclin1 on epilepsy remains unclear. In this study, we detected increased expression of Beclin1 in brain tissues from patients with temporal lobe epilepsy (TLE). Heterozygous disruption of beclin1 decreased susceptibility to epilepsy and suppressed seizure activity in two mouse epilepsy models. We further illustrated for the first time that heterozygous disruption of beclin1 suppresses excitatory synaptic transmission, which may be caused by a decreased dendritic spine density. These findings suggest for the first time that the regulation of Beclin1 may serve as a strategy for antiepileptic therapy. In addition, Beclin1 participates in synaptic transmission, and the development of dendritic spines may be a biological function of Beclin1 independent of its role in autophagy.

Acute lung inflammation induced by zinc oxide nanoparticles: Evolution and intervention via NRF2 activator

Zinc oxide nanoparticles (ZnONPs) are widely used worldwide. Human inhalation exposure to ZnONPs induces acute lung inflammation (ALI); however, the characteristics and therapeutic targets of ALI are unclear. In this study, female C57BL/6J mice were subjected to a single intratracheal instillation of 20 μg of ZnONPs. Increased lung malondialdehyde levels and decreased total antioxidant capacity at 6 h, as well as increased lactate dehydrogenase levels in bronchoalveolar lavage fluid (BALF) at 1 day (d) post treatment were observed. A significant inflammatory response was observed at 3 d and 7 d, as evidenced by increased leukocyte numbers and total protein concentration in BALF, and histological abnormalities. Pulmonary NRF2 signaling was significantly activated at 3 d post treatment. To investigate a protective role of NRF2 activator against ZnONP-induced ALI, the mice were intraperitoneally injected with 2-cyano-3,12-dioxooleana-1,9-dien-28-imidazolide (CDDO-Im) (2 mg/kg) 1 d before and 1 d after ZnONPs treatment. CDDO-Im significantly decreased leukocyte numbers and total protein concentration in BALF and pulmonary inflammatory gene expression, and ameliorated histopathological abnormalities induced by ZnONPs. Collectively, the present study indicates that ZnONPs exposure leads to oxidative stress, cell injury and inflammation in the lung successively. Moreover, the NRF2 activator protects against ZnONPs-induced ALI.

Downregulation of beclin 1 restores arsenite-induced impaired autophagic flux by improving the lysosomal function in the brain

Arsenite is a toxic metalloid that causes various adverse effects in the brain. However, the underlying mechanisms of arsenite-induced neurotoxicity remain poorly understood. In this study, both adult beclin 1^+/+ and beclin 1^+/- mice were employed to establish a model of chronic arsenite exposure by treating with arsenite via drinking water for 6 months. The results clearly demonstrated that exposure to arsenite profoundly caused damage to the cerebral cortex, induced autophagy and impaired autophagic flux in the cerebral cortex. Heterozygous disruption of beclin 1 in animals remarkably alleviated the neurotoxic effects of arsenite. To verify the results obtained in the animals, a permanent U251 cell line was used. After treating of cells with arsenite, similar phenomenon was also observed, showing the significant elevation in the expression levels of autophagy-related genes. Importantly, lysosomal dysfunction caused by arsenite was observed in vitro and in vivo. Either knockdown of beclin 1 in cells or heterozygous disruption of beclin 1 in animals remarkably alleviated the lysosomal dysfunction induced by arsenite. These findings indicate that downregulation of beclin 1 could restore arsenite-induced impaired autophagic flux possibly through improving lysosomal function, and correct that regulation of autophagy via beclin 1 would be an alternative approach for the treatment of arsenite neurotoxicity.

Stabilization of Nrf2 leading to HO-1 activation protects against zinc oxide nanoparticles-induced endothelial cell death

With the abundant production and wide application of zinc oxide nanoparticles (ZnONPs), the potential health risks of ZnONPs have raised serious concerns. Oxidative stress is recognized as the most important outcome of the toxicity induced by ZnONPs. The Nrf2-Keap1 system and its downstream antioxidative genes are the fundamental protective mechanisms for redox hemeostasis. However, the detailed mechanisms of Nrf2 activation in ZnONPs-treated endothelial cells and murine blood vessels have yet to be elucidated. Herein, we show that Nrf2 was activated and played a negative role in cell death induced by ZnONPs. Moreover, we demonstrate that HO-1 was the most extensively upregulated antioxidative gene-activated by Nrf2. Forced overexpression of HO-1, pharmacological activation of HO-1 with the agonists RTA-408 (omaveloxolone, an FDA-approved drug) and RTA-402 repressed cell death, and treatment with HO-1 antagonist SnPP exacerbated the cell death. Importantly, loss of HO-1 diminished the cytoprotective role induced by Nrf2 in ZnONPs-treated HUVEC cells, indicating that the Nrf2-HO-1 axis was the crucial regulatory mechanism for the antioxidative response in the context of ZnONPs-induced endothelial damage. Mechanistically, we demonstrate that the p62-Keap1 axis was not involved in the activation of Nrf2. Intriguingly, the degradation half-life of Nrf2 in HUVEC cells was increased from less than 1 h under quiescent conditions to approximately 6 h under ZnONPs treatment condition; moreover, ZnONPs treatment induced activation of Nrf2/HO-1 and accumulation of ubiquitin in the aorta ventralis of mouse, suggesting that the ubiquitin-proteasome system had been perturbed, which subsequently led to the stabilization of Nrf2 and activation of HO-1. This study might contribute to a better understanding of ZnONPs-associated toxicity.

LC3B in Malignant Cells Correlates With Immune Infiltrate in Hypopharyngeal Squamous Cell Carcinoma

The objective of this study was to investigate the between autophagy activity and local immune response in hypopharyngeal squamous cell carcinoma (HSCC). Herein, we observed the expression of autophagy marker microtubule-associated protein light chain 3B (MAP1LC3B), CD8 cytotoxic T lymphocytes (CTLs), CD39 (regulatory T cells Tregs) and CD163 (tumor-associated macrophages TAMs) in HSCC, and determined the prognostic roles of CD8⁺/CD39⁺ and CD8⁺/CD163⁺ in patients with HSCC. The expression of light chain 3B (LC3B) and CD8⁺/CD39⁺ was found to be significantly lower in HSCC tissues than in adjacent non-tumor mucosa tissue samples; LC3B expression was positively correlated with the infiltration rate of CD8⁺/CD39⁺ in HSCC. Further studies revealed that the ratio of CD8⁺/CD39⁺ immune cells was negatively correlated with tumor lymph node metastasis and TNM classification, while the ratio of CD8⁺/CD163⁺ immune cells was negatively correlated with TNM classification. Moreover, the expression of LC3B was analyzed and the patients were grouped according to their immune infiltration characteristics. The 5-year cumulative survival rates of LC3B⁺, CD8⁺/CD39⁺, and CD8⁺/CD163⁺ patients were significantly higher than those of other group patients. Collectively, our studies indicated that the expression of LC3B in HSCC was correlated with the infiltration ratio of immune cells, and a change in autophagy activity may affect the cellular immunity in HSCC. The ratios of tCD8⁺/CD39⁺ and tCD8⁺/CD163⁺ may serve as prognostic factors for HSCC.