Amorphous silica nanoparticles cause abnormal cytokinesis and multinucleation through dysfunction of the centralspindlin complex and microfilaments.

BACKGROUND: With the large-scale production and application of amorphous silica nanoparticles (aSiNPs), its adverse health effects are more worthy of our attention. Our previous research has demonstrated for the first time that aSiNPs induced cytokinesis failure, which resulted in abnormally high incidences of multinucleation in vitro, but the underlying mechanisms remain unclear. Therefore, the purpose of this study was firstly to explore whether aSiNPs induced multinucleation in vivo, and secondly to investigate the underlying mechanism of how aSiNPs caused abnormal cytokinesis and multinucleation. METHODS: Male ICR mice with intratracheal instillation of aSiNPs were used as an experimental model in vivo. Human hepatic cell line (L-02) was introduced for further mechanism study in vitro. RESULTS: In vivo, histopathological results showed that the rate of multinucleation was significantly increased in the liver and lung tissue after aSiNPs treatment. In vitro, immunofluorescence results manifested that aSiNPs directly caused microfilaments aggregation. Following mechanism studies indicated that aSiNPs increased ROS levels. The accumulation of ROS further inhibited the PI3k 110ß/Aurora B pathway, leading to a decrease in the expression of centralspindlin subunits MKLP1 and CYK4 as well as downstream cytokines regulation related proteins Ect2, Cep55, CHMP2A and RhoA. Meanwhile, the particles caused abnormal co-localization of the key mitotic regulatory kinase Aurora B and the centralspindlin complex by inhibiting the PI3k 110ß/Aurora B pathway. PI3K activator IGF increased the phosphorylation level of Aurora B and improved the relative ratio of the centralspindlin cluster. And ROS inhibitors NAC reduced the ratio of multinucleation, alleviated the PI3k 110ß/Aurora B pathway inhibition, and then increased the expression of MKLP1, CYK4 and cytokinesis-related proteins, whilst NAC restored the clustering of the centralspindlin. CONCLUSION: This study demonstrated that aSiNPs led to multinucleation formation both in vivo and in vitro. ASiNPs exposure caused microfilaments aggregation and inhibited the PI3k 110ß/Aurora B pathway through excessive ROS, which then hindered the centralspindlin cluster as well as restrained the expression of centralspindlin subunits and cytokinesis-related proteins, which ultimately resulted in cytokinesis failure and the formation of multinucleation.

Four different frailty models predict health outcomes in older patients with stable chronic obstructive pulmonary disease.

BACKGROUND: Frail patients with chronic obstructive pulmonary disease (COPD) face a higher risk of adverse outcomes, but there is no clear consensus on which frailty measures are most suitable for COPD patients. Herein we evaluated the ability of frailty measurements in predicting 1-year acute exacerbation, hospitalization, and mortality in older patients with COPD. METHODS: A total of 302 patients [median age: 86 years (IQR: 80-90), 22.2% female] were admitted to the Department of Geriatric Medicine were prospectively enrolled in this study. Frailty status was assessed using the Fried Frailty Phenotype (FFP), Clinical Frailty Scale (CFS), Frailty Index of Accumulative Deficits (FI-CD), and Short Physical Performance Battery (SPPB). Cox proportional hazard regression and Poisson regression were used to evaluating the association of the adverse outcomes with frailty as assessed using the four instruments. The discrimination accuracy of these tools in predicting the 1-year all-cause mortality was also compared. RESULTS: Prevalence of frailty ranged from 51% (using FFP) to 64.2% (using CFS). The four frail instruments were associated with 1-year mortality. After an average follow-up time of 2.18 years (IQR: 1.56-2.62 years), frailty as defined by four instruments (except for FI-CD), was associated with death [FFP: Hazard ratio (HR) = 3.11, 95% confidence interval (CI) 1.30-7.44; CFS: HR = 3.68, 95% CI 1.03-13.16; SPPB: HR = 3.74, 95% CI 1.39-10.06). Frailty was also associated with acute exacerbation (using FFP) and hospitalization (using FFP, CFS, and FI-CD). Frail showed a moderate predictive ability [area under the curve ranging (AUC) 0.70-0.80] and a high negative predictive value (0.98-0.99) for 1-year mortality. CONCLUSIONS: With the four different frailty assessment tools, frailty was associated with poor prognosis in older patients with stable COPD. The FFP, CFS, FI-CD, and SPPB instruments showed similar performance in predicting 1-year mortality.

The implication of cigarette smoking and cessation on macrophage cholesterol efflux in coronary artery disease patients.

We investigated ATP-binding cassette transporters A1/G1 expression and function in mediating cholesterol efflux by examining the macrophages of cigarette-smoking patients with coronary artery disease (CAD) before and after smoking abstinence. Peripheral blood monocyte cells were collected from nonsmokers (n = 17), non-CAD (NCAD) smokers (n = 35), and CAD smokers (n = 32) before and after 3 months of smoking cessation. We found that the ABCA1 expression level was lower in macrophages from NCAD and CAD smokers than from nonsmokers at baseline. The ABCA1 function of mediating cholesterol efflux was reduced in NCAD and CAD smokers as compared with nonsmokers. After 3 months of smoking cessation, ABCA1 expression and function were improved in CAD smokers. However, ABCG1 expression and function did not change after smoking cessation. Furthermore, ABCA1 expression was inhibited by tar in human acute monocytic leukemia cell line THP-1-derived macrophages through the inhibition of liver X receptors. Nicotine and carbon monoxide did not inhibit ABCA1 expression. Our results indicate that chronic cigarette smoking impaired ABCA1-mediated cholesterol efflux in macrophages and that tobacco abstinence reversed the function and expression of ABCA1, especially in CAD patients. It was tobacco tar, rather than nicotine or carbon monoxide, that played a major role in the tobacco-induced disturbance of cellular cholesterol homeostasis.

Impact of Frailty on the Risk of Exacerbations and All-Cause Mortality in Elderly Patients with Stable Chronic Obstructive Pulmonary Disease.

RATIONALE: For the high prevalence of frail in patients with chronic obstructive pulmonary disease (COPD), further study should explore an in-depth understanding of the relationship between frailty and prognosis of COPD. OBJECTIVE: To determine the correlation between frailty and risk of acute exacerbation, hospitalizations, and mortality in older patients with stable COPD. PARTICIPANTS AND METHODS: Consecutive older adults (≥65) diagnosed with stable COPD from January 2018 to July 2019, with an average follow-up of 546 days (N = 309). Frailty was defined by the Fried frailty phenotype. Poisson regression was performed to assess the influence of frailty on the incidence of acute exacerbations of COPD (AECOPD) and all-cause hospitalizations in a year. Cox regression was performed to evaluate the effect of frailty on all-cause mortality in patients with stable COPD. RESULTS: The prevalence of frailty was 49.8%. The most common phenotypic characteristics were weakness (99.4%) followed by slowness (92.9%). After adjustment, frailty increased the incidence of AECOPD (IRR = 1.75, 95% CI: 1.09-2.82) and all-cause hospitalizations (IRR = 1.39, 95% CI 1.04-1.87) within a year. Slowness was associated with AECOPD (IRR = 1.77, 95% CI: 1.03-3.03), and weakness was associated with increased all-cause hospitalizations (IRR = 1.53, 95% CI: 1.04-2.25). The all-cause mortality risk was more than twofold higher in frail patients (HR = 2.54, 95% CI: 1.01-6.36) than non-frail patients. Low physical activity (HR = 2.66, 95% CI: 1.17-6.05) and weight loss (HR = 2.15, 95% CI: 1.02-4.51) were significantly associated with increased all-cause mortality in patients with COPD. CONCLUSION: Frailty increased the incidence of acute exacerbation and hospitalization, as well as increased mortality in older patients with stable COPD. This knowledge will help physicians identify high-risk groups with COPD and frailty who may benefit from targeted interventions to prevent disease progression.

Ghrelin inhibit cell apoptosis in pancreatic beta cell line HIT-T15 via mitogen-activated protein kinase/phosphoinositide 3-kinase pathways.

Ghrelin stimulates growth hormone (GH) release and induces positive energy balances. Previous studies have reported that ghrelin inhibits apoptosis in several cell types but the precise underlying protective mechanisms in pancreatic beta cells are poorly understood. Therefore, we investigated which pathway was related with its anti-apoptotic effect in pancreatic beta cells. Exposure of HIT-T15 cells to ghrelin caused a rapid activation of MAPKs and Akt. Chemical inhibitors of MAPK and PI3K blocked the anti-apoptotic of ghrelin. Ghrelin also stimulated the mitochondrial pathways of apoptosis and it showed increased Bcl-2, decreased Bax, prevention cytochrome c release and inhibition of caspase-3 activation in pancreatic beta cell line HIT-T15. Our findings suggest that ghrelin may act as a survival factor that inhibits the apoptotics pathways, and the MAPKs, AKT pathways could be key roles in the apoptosis of pancreatic beta cells.

Characterization of fluorescent NBD­cholesterol efflux in THP­1­derived macrophages.

Macrophage cholesterol efflux is important in maintaining cellular lipid homeostasis and preventing the formation of lipid­laden foam cells. Although radioactive [3H]­cholesterol is widely used as a tracer in cholesterol efflux assays, the lengthy and labor­intensive assay procedure, and the radioactivity disposal procedure limit the use of this assay for high­throughput screening. In the present study, a novel procedure using fluorescent N­(7­nitrobenz­2­oxa­1,3­diazol­4­yl)amino)­23,24­bisnor­5­xholen­3ß­ol (NBD)­cholesterol was developed as a substitute for [3H]­cholesterol for the measurement of cholesterol efflux in THP­1­derived macrophages. NBD­cholesterol uptake and metabolism in the THP­1 cells were characterized using fluorescent microscopy and spectrophotometry. NBD­cholesterol distributed rapidly into the cell organelles, with the exception of the nucleus. The uptake of NBD­cholesterol in the THP­1 macrophages was concentration­ and time­dependent, and reached a plateau following 4 h incubation. The present study subsequently investigated whether NBD­cholesterol efflux was correlated with [3H]­cholesterol efflux in THP­1 derived macrophages and in human peripheral blood mononuclear cells (PBMCs). The results demonstrated that the percentage of efflux of NBD­cholesterol in the THP­1 cells was significantly correlated with that of [3H]­cholesterol, at various concentrations of HDL or apoA­1 as lipid acceptors (R2=0.876 for HDL; R2=0.837 for apoA­1; P<0.001). In the PBMCs, NBD­cholesterol efflux also correlated significantly with [3H]­cholesterol efflux (R2=0.887 for HDL; R2=0.872 for apoA­1; P<0.001). Furthermore, NBD­cholesterol efflux in the THP­1 cells exhibited a similar trend to that obseved in the PBMCs. In conclusion, the results of the present study suggested that fluorescent NBD­cholesterol can be used as a sensitive and specific probe in cholesterol efflux assays in THP­1­derived macrophages.

Mechanical strain-induced c-fos expression in pulmonary epithelial cell line A549.

Pulmonary epithelial cells are exposed to mechanical strain during physiological breathing and mechanical ventilation. It was not clear which style was more related with cell mechanotransduction. c-fos is known to be a component of a transcription factor, activator protein-1, which is induced by oxidative stress. The regulatory pathways involved in the rapid response of the AP-1 transcription factor, c-fos, to mechanical load in the human pulmonary epithelial cell line A549 were investigated using a four-point bending model. In an effort to better understand what processes are involved in mechanotransduction, we have examined whether and how soon c-fos induction occurs in human A549 shortly after the application of the different mechanical strains stimuli.