Titanium dioxide nanoparticles oral exposure induce osteoblast apoptosis, inhibit osteogenic ability and increase lipogenesis in mouse.

Titanium dioxide nanoparticles (TiO2-NPs) are widely used in food, paint, coating, cosmetic, and composite orthodontic material. As a common food additive, TiO2-NPs can accumulate in various organs of human body, but the effect and underlying mechanism of bone remain unclear. Here mice were exposed to TiO2-NPs by oral gavage, and histological staining of femoral sections showed that TiO2-NPs reduced bone formation and enhanced osteoclast activity and lipogenesis, contributing to decreased trabecula bone. Transmission electron microscope (TEM) as well as biochemical and flow cytometry analysis of osteoblast exhibited that TiO2-NPs accumulated in osteoblast cytoplasm and impaired mitochondria ultrastructure with increased reactive oxygen species (ROS) and lipid hyperoxide, resulting in osteoblast apoptosis. In terms of mechanism, TiO2-NPs treatment inhibited expression of AKT and then increased pro-apoptotic protein Bax expression which was failure to form heterodimers with decreased anti-apoptotic Bcl-2, activating downstream Caspase-9 and Caspase-3 and inducing apoptosis. Additionally, TiO2-NPs suppressed Wnt3a level and then activated anti-Glycogen synthesis kinase (GSK-3ß) phosphorylation, and ultimately resulted in degradation of ß-catenin which down-regulated Runt-related transcription factor 2 (Runx2) and Osterix, inhibiting expression of osteogenic related proteins. Together, these results revealed that exposure of TiO2-NPs induced apoptosis and inhibited osteoblast differentiation through suppressing PI3K/AKT and Wnt/ß-catenin signaling pathways, resulting in reduction of trabecula bone.

Molecular mechanism of nanoparticulate TiO2 induction of axonal development inhibition in rat primary cultured hippocampal neurons.

Numerous studies have demonstrated the in vitro and in vivo neurotoxicity of nanoparticulate titanium dioxide (nano-TiO2 ), a mass-produced material for a large number of commercial and industrial applications. The mechanism of nano-TiO2 -induced inhibition of axonal development, however, is still unclear. In our study, primary cultured hippocampal neurons of 24-hour-old fetal Sprague-Dawley rats were exposed to 5, 15, or 30 µg/mL nano-TiO2 for 6, 12, and 24 hours, and the toxic effects of nano-TiO2 exposure on the axons development were detected and its molecular mechanism investigated. Nano-TiO2 accumulated in hippocampal neurons and inhibited the development of axons as nano-TiO2 concentrations increased. Increasing time in culture resulted in decreasing axon length by 32.5%, 36.6%, and 53.8% at 6 hours, by 49.4%, 53.8%, and 69.5% at 12 hours, and by 44.5%, 58.2%, and 63.6% at 24 hours, for 5, 15, and 30 µg/mL nano-TiO2 , respectively. Furthermore, nano-TiO2 downregulated expression of Netrin-1, growth-associated protein-43, and Neuropilin-1, and promoted an increase of semaphorin type 3A and Nogo-A. These studies suggest that nano-TiO2 inhibited axonal development in rat primary cultured hippocampal neurons and this phenomenon is related to changes in the expression of axon growth-related factors.

Endoplasmic reticulum stress induced LOX-1+ CD15+ polymorphonuclear myeloid-derived suppressor cells in hepatocellular carcinoma.

A recent study indicated that Lectin-type oxidized LDL receptor-1 (LOX-1) was a distinct surface marker for human polymorphisms myeloid-derived suppressor cells (PMN-MDSC). The present study was aimed to investigate the existence LOX-1 PMN-MDSC in hepatocellular carcinoma (HCC) patients. One hundred and twenty-seven HCC patients, 10 patients with mild active chronic hepatitis B, 10 liver cirrhosis due to hepatitis B, 10 liver dysplastic node with hepatitis B and 50 health control were included. LOX-1+  CD15+ PMN-MDSC were significantly elevated in HCC patients compared with healthy control and patients with benign diseases. LOX-1+  CD15+ PMN-MDSC in circulation were positively associated with those in HCC tissues. LOX-1+  CD15+ PMN-MDSCs significantly reduced proliferation and IFN-γ production of T cells with a dosage dependent manner with LOX-1-  CD15+ PMNs reached negative results. The suppression on T cell proliferation and IFN-γ production was reversed by ROS inhibitor and Arginase inhibitor. ROS level and activity of arginase of LOX-1 + CD15+ PMN were higher in LOX-1+  CD15+ PMN-MDSCs than LOX-1-  CD15+ PMNs, as well as the expression of the NADPH oxidase NOX2 and arginase I. RNA sequence revealed that LOX-1+ CD15+ PMN-MDSCs displayed significantly higher expression of spliced X-box -binding protein 1 (sXBP1), an endoplasmic reticulum (ER) stress marker. ER stress inducer induced LOX-1 expression and suppressive function for CD15+ PMN from health donor. For HCC patients, LOX-1+  CD15+ PMN-MDSCs were positively related to overall survival. Above all, LOX-1+  CD15+ PMN-MDSC were elevated in HCC patients and suppressed T cell proliferation through ROS/Arg I pathway induced by ER stress. They presented positive association with the prognosis of HCC patients.

ISOLATION, IDENTIFICATION, AND GENOME ANALYSIS OF LUNG PATHOGENIC KLEBSIELLA PNEUMONIAE (LPKP) IN FOREST MUSK DEER.

Klebsiella pneumoniae is an important pathogen commonly associated with opportunistic infections. In this study, lung pathogenic K. pneumoniae (LPKP) was isolated and identified from suppurative pneumoniae in forest musk deer by conventional methods and by 16S ribosomal RNA sequence analysis. Median lethal dose and histopathologic analysis were used to demonstrate pathogenicity of the organism in mice. Furthermore, a draft genome of LPKP was sequenced, and its virulence genes were detected. One hundred and twenty-two virulence genes encoded determinant of capsule polysaccharide (CPS), lipopolysaccharide, fimbriae, outer membrane proteins, iron acquisition, and urease. In particular, 20 CPS-related genes were highly conserved in LPKP, K. pneumoniae U, K. pneumoniae NTUH-KP35, and K. pneumoniae KP-1. All of the strains were identified as capsular type K54. This is the first report of capsular type K54 K. pneumoniae causing suppurative pneumonia in an animal. The results of this study provided the basis for understanding the pathogenicity of LPKP and laid a foundation for the development of vaccines for the capsular type K54 K. pneumoniae disease.

Comparison of five models for end-stage liver disease in predicting the survival rate of patients with advanced hepatocellular carcinoma.

Prognosis of patients with advanced hepatocellular carcinoma (HCC) is under expectation. Life expectancy more than 3 months is one inclusion criteria for molecular targeted drugs in clinical trials. The main purpose of this research is to compare Model for End-Stage Liver Disease (MELD) and four MELD-based prognostic models in predicting the survival rate of advanced HCC patients. One hundred eighty-three patients with advanced HCC who were not amendable to standard anti-tumor therapy were retrospectively analyzed. Data were collected to classify patients according to MELD, Model for End-Stage Liver Disease with the incorporation of serum sodium (MELD-NA), Model for End-Stage Liver Disease to ascites and sodium (MELD-AS), integrated Model for End-Stage Liver Disease (iMELD), and Model for End-Stage Liver Disease to sodium (MESO) scores at diagnosis. 1-, 3-, and 6-month survivals were the end points used in the analysis. When predicting 1-month survival, MELD-AS, MELD, and MESO were the top 3 ranking staging systems. When predicting 3-month survival, area under the receiver operating characteristic curve (AUC) of MELD-AS is significantly higher than that of the other models (P < 0.05). When predicting 6-month survival, AUCs of MELD-AS and MELD-NA are significantly higher than those of the other models (P < 0.05). Cutoff point of MELD-AS is 23.11 with 40.5 % sensitivity and 93.8 % specificity at 1 month, 9.5 with 76.9 % sensitivity and 59.5 % specificity at 3 months, and 18.5 with 27.0 % sensitivity and 89.1 % specificity at 6 months. MELD-based scores of death group are significantly higher than those of survivors within 1 and 3 months (P < 0.001). Independent prognostic factors identified by multivariate analysis included persistent ascites, serum sodium, and thrombosis. MELD-AS is the best model in the prediction of short and intermediate survival among the five models for end-stage liver disease analyzed for Chinese advanced HCC patients.

Alanine aminotransferase to hemoglobin ratio is an indicator for disease progression for hepatocellular carcinoma patients receiving transcatheter arterial chemoembolization.

The prognosis of hepatocellular carcinoma (HCC) patients receiving transcatheter arterial chemoembolization (TACE) is far from being identified. The present study aimed to assess the role of blood cell counts, routine liver function tests, and alanine aminotransferase to hemoglobin ratio (AHR) in predicting the progression-free survival (PFS) of these patients. A total of 243 HCC patients receiving TACE were analyzed retrospectively. Cancer of the Liver Italian Program (CLIP) score system was indentified to be the best score system for this patient subgroup according to the Akaike information criterion (AIC) index and linear trend χ (2). Then, prognostic value of parameters was determined by integration into the CLIP score system. As a result, AHR was confirmed to be an independent predictor for the PFS of HCC patients receiving TACE (p = 0.001) with the other parameters failing to reach statistical significance. Moreover, AHR improved the performance of CLIP by adjusting into it, thus improving its discriminatory ability. AHR defined ≤0.4583 as low level and >0.4583 as high level. And, patients were also dichotomized into two groups accordingly. HCC patients receiving TACE with low AHR presented higher 1 year DCR (41.9 vs 18.1 %) compared with patients with high AHR levels. Furthermore, AHR level was associated with prognostic factors such as lower ALP, total bilirubin, and portal vein thrombosis. In summary, the present study firstly indentified AHR as an independent prognostic factor in HCC patients receiving TACE. The subgroup of HCC patients with lower AHR presented preferable disease control and were the idealistic candidates for TACE.

TiO2 nanoparticle-induced neurotoxicity may be involved in dysfunction of glutamate metabolism and its receptor expression in mice.

Titanium dioxide nanoparticles (TiO2 NPs) have been used in environmental management, food, medicine, and industry. But TiO2 NPs have been demonstrated to cross the blood-brain barrier and store up in the brain organization, leading to glutamate-mediated neurotoxicity. However, the neurotoxicity in the brain is not well understood. In this study, mice were exposed to 1.25, 2.5, or 5 mg/kg body weight TiO2 NPs for 9 months, and the glutamate-glutamine cyclic pathway and expressions of glutamate receptors associated with the hippocampal neurotoxicity were investigated. Our findings showed elevations of glutamate release and phosphate-activated glutaminase activity, and reductions in glutamine and glutamine synthetase in the hippocampus following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly inhibited the expression of N-methyl-d-aspartate receptor subunits (including NR1, NR2A, and NR2B) and metabotropic glutamate receptor 2 in mouse hippocampus. These findings suggest that the imbalance of glutamate metabolism triggered inhibitions of glutamate receptor expression in the TiO2 NP-exposed hippocampus. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 655-662, 2016.

Platelet-to-lymphocyte ratio acts as a prognostic factor for patients with advanced hepatocellular carcinoma.

The platelet count, as an inflammation marker, is involved in the progress of tumor invasion. However, the prognostic value of platelet counts and the platelet-to-lymphocyte ratio (PLR) has not been investigated in patients with advanced hepatocellular carcinoma (HCC). This study aimed to determine the prognostic value of platelet counts and PLR in HCC patients. A total of 243 ethnic Chinese advanced HCC patients from two major hospitals, not receiving systemic sorafenib, were analyzed retrospectively. The prognostic value of differential blood cell counts and PLR for overall survival (OS) was determined by integrating the Cancer of the Liver Italian Program (CLIP) score system and model for end-stage liver disease by using a stepwise model of multivariate Cox regression. The Kaplan-Meier method and receiver operating characteristic (ROC) curves were utilized accordingly. PLR was confirmed to be an independent predictor for OS (p < 0.01), while the remaining parameters had no predictive value. Then, advanced HCC patients were dichotomized into two groups based on the PLR value (≤111.23 or >111.23), according to ROC analysis. Patients with a high PLR had a lower 3-month survival rate (37.6 vs. 57.6%) compared with patients with a low PLR. PLR was associated with aggressive malignant behavior, characterized by distant metastasis and portal vein thrombosis. Additionally, PLR was not associated with the CLIP score and Child-Pugh grade. PLR was identified as an independent prognostic factor for advanced HCC patients not receiving systemic sorafenib; the predictive ability of PLR partially relies on its association with the aggressive nature of HCC.

Autophagic LC3B overexpression correlates with malignant progression and predicts a poor prognosis in hepatocellular carcinoma.

Autophagy is a process that involves lysosomal degradations of cellular organelles and closely related to tumor occurrence and progression. However, its importance in hepatocellular carcinoma (HCC) was still controversial. Therefore, this study is aimed to address the clinicopathologic effect of microtubule-associated protein 1 light chain 3B (LC3B) and Beclin-1, as autophagic markers, in HCC patients. Tissue microarray-based immunohistochemistry was used to examine the expression of LC3B and another autophagy key regulator (Beclin-1) in 156 operable HCC patients. Kaplan-Meier analysis, chi-square test, and Spearman's correlation analysis were used to analyze correlation of LC3B and Beclin-1 and their influence on clinical characteristics and prognosis. We found that the expression level of LC3B was significantly associated with vascular invasion (P = 0.008), lymph node metastasis (P < 0.001), and Beclin-1 expression level (P < 0.001). However, LC3B was not related to other clinicopathological features, including hepatitis B virus infection, liver cirrhosis, tumor number, tumor size, pathology grade, and tumor-node-metastasis (TNM) stage. Besides, correlation between the expression of Beclin-1 and clinicopathological features were not identified. Survival analysis showed that patients with high LC3B expression had a poorer 5-year overall survival (OS) rate than those with low LC3B expression (high vs. low: 79.5 % vs. 20.5 %, P = 0.026). And high LC3B expression tended to be related with shorter progression-free survival (PFS) (P = 0.074), whereas the expression level of Beclin-1 did not show statistically significant association with OS or PFS. Further multivariate analysis revealed that lymph node metastasis (P = 0.047) and LC3B expression level (P = 0.047) were independent factors to predict the prognosis of OS in all patients. Our study demonstrated that high expression of LC3B, correlated with vascular invasion and lymph node metastasis, might be a novel prognostic biomarker and would be a potential therapy target for HCC, especially in operable patients.

Neutrophil-to-lymphocyte ratio acts as a prognostic factor for patients with advanced hepatocellular carcinoma.

Few studies investigated the prognosis of patients with advanced hepatocellular carcinoma (aHCC). This study was aimed to determine the prognostic value of differential blood cell counts including blood white cells, neutrophil, lymphocyte, neutrophil-lymphocyte ratio (NLR), and platelet in patients with aHCC. A total of 205 ethnic Chinese aHCC patients receiving non-systematic sorafenib were analyzed retrospectively. The prognostic value of differential blood cell counts and NLR for overall survival (OS) was determined by integration into Cancer of the Liver Italian Program (CLIP) score system using backward elimination model of multivariate Cox regression. As a result, NLR was confirmed to be an independent predictor for OS (p = 0.001) with the rest parameters presented negative results. Then, aHCC patients were dichotomized into two groups according to NLR values ≤ 2.43 or >2.43. Patients with low NLR presented lower CLIP score and higher 6-month survival rate (56.1 vs 25.9%) compared with patients with high NLR level. Besides, low NLR level was associated with favorable prognostic factors such as lower α-fetoprotein, alkaline phosphatase, and total bilirubin, as well as decreased incidence of ascites, portal vein thrombosis, and metastasis. Besides, low NLR level was associated less white cells and neutrophil granulocytes, as well as more lymphocyte. In summary, the present study firstly indentified NLR as an independent prognostic factor in aHCC patients receiving no systematic sorafenib.

Kidney injury and alterations of inflammatory cytokine expressions in mice following long-term exposure to cerium chloride.

It has been demonstrated that the organic damages of animals can be caused by exposure to lanthanide oxides or compounds. However, the molecular mechanism of CeCl3 -induced kidney injury remains unclear. In this study, the mechanism of nephric damage in mice induced by an intragastric administration of CeCl3 was investigated. The results showed that Ce(3+) was accumulated in the kidney, which in turn led to oxidative stress, severe nephric inflammation, and dysfunction in mice. Furthermore, CeCl3 activated nucleic factor κB, which in turn increased the expression levels of tumor necrosis factor α, macrophage migration inhibitory factor, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-18, interleukin-1ß, cross-reaction protein, transforming growth factor-ß, interferon-γ, and CYP1A1, while suppressed heat shock protein 70 expression. These findings implied that Ce(3+) -induced kidney injury of mice might be associated with oxidative stress, alteration of inflammatory cytokine expression, and reduction of detoxification of CeCl3 .

An optimized antiviral modification strategy for prevention of hepatitis B reactivation in patients undergoing prophylactic lamivudine and chemotherapy: a pilot study.

In patients receiving prophylactic lamivudine (LAM) and chemotherapy, hepatitis B virus (HBV) reactivation cannot be eliminated without knowing the latent causes and optimal management. In our previous study, virus breakthrough and relapse were highly suspected as potential virologic causes for HBV reactivation. Therefore, we reviewed 24 previous studies and 447 patients who underwent chemotherapy and prophylactic LAM, with an incidence of 7.2 % HBV reactivation. Virus breakthrough and relapse were seldom investigated in these studies. In addition, 72 patients that underwent prophylactic LAM and chemotherapy at our centers were also analyzed. Among them, eight patients developed virus breakthrough, with another nine developing virus relapse after discontinuation of LAM. Eight patients received antiviral modification, which included administration of adefovir for patients with virus breakthrough or resumption of LAM for patients with virus relapse and none of them developed HBV reactivation. In contrast, of the nine patients who did not receive antiviral modification, six developed HBV reactivation and two died. In conclusion, this study demonstrated that virus breakthrough and relapse were the critical causative factors of HBV reactivation in patients receiving chemotherapy and prophylactic LAM. An optimized antiviral modification strategy could effectively prevent HBV reactivation in patients with virus breakthrough or relapse.

Molecular cloning, prokaryotic expression and its application potential evaluation of interferon (IFN)-ω of forest musk deer.

Forest musk deer (Moschus berezovskii) are currently a threatened species under conservation, and the development of captive populations is restricted by health problems. To evaluate the application potential of interferon (IFN)-ω in the prevention and control of forest musk deer disease, 5 forest musk deer IFN-ω (fmdIFNω) gene sequences were successfully obtained by homologous cloning method for the first time. FmdIFNω5 was selected and recombinant fmdIFNω protein (rIFNω) was successfully expressed by pGEX-6P-1 plasmid and E. coli expression system. The obtained protein was used to stimulate forest musk deer lung fibroblasts cells FMD-C1 to determine its regulatory effect on interferon-stimulated genes (ISGs). In addition, an indirect ELISA method based on anti-rIFNω serum was established to detect endogenous IFN-ω levels in 8 forest musk deer. The results showed that there were 18 amino acid differences among the 5 fmdIFNω subtypes, all of which had the basic structure to exert the activity of type I IFN and were close to Cervus elaphus IFN-ω in the phylogenetic tree. The protein expressed was 48 kDa, and the transcription levels of all ISGs were increased in FMD-C1 cells stimulated by rIFNω, and the amount of transcription accumulation was time-dependent. Meanwhile, Anti-rIFNω serum of mice could react with both rIFNω and forest musk deer serum, and the OD450nm value of forest musk deer serum with the most obvious symptoms was the highest, suggesting that the level of natural IFN-ω in different forest musk deer could be monitored by the rIFNω-based ELISA method. These results indicate that fmdIFNω has the potential as an antiviral drug and an early indication of innate immunity, which is of great significance for the prevention and control of forest musk deer diseases.

Isolation and bioinformatics analysis of the NADC30_Like CJS01 strain of the porcine reproductive and respiratory syndrome virus.

In this study, lung tissue was collected from nursery piglets suspected of being infected with porcine reproductive and respiratory syndrome virus (PRRSV) in a large­scale pig farm in Sichuan, China. Polymerase chain reaction (PCR) and reverse transcription quantitative­polymerase chain reaction (RT­qPCR) methods were used to ensure that no other pathogens were present. Virus isolation was also carried out where the presence of PRRSV was determined by indirect immunoinfluscent assay (IFA). Compared with the common PRRSV strain, the isolate did not produce evident Cytopathic effect (CPE) in the early stage of isolation. CPE was found in the late stage, and the titer was 104.17 TCID50/0.1 mL. The strain was named CJS01. Bioinformatics analysis showed that it was a NADC30­Like strain. The virus load was determined by measuring the nucleic acid load during the proliferation of the strain on Marc­145 cells. The strain showed good adaptability on cells, and the virus proliferated on cells for 84 hr when the highest nucleic acid load was achieved. By recombinant analysis of ORF3~7 genes and prediction of its epitope, it was found that CJS01 strain might interfere with the immunesystem of the infected animals.

Nano-TiO2 Reduces Testosterone Production in Primary Cultured Leydig Cells from Rat Testis Through the Cyclic Adenosine Phosphate/Cyclic Guanosine Phosphate/Epidermal Growth Factor Receptor/Matrix Metalloproteinase Signaling Pathway.

Nano-titanium dioxide (nano-TiO2) has been shown to inhibit testosterone synthesis in male mice or rats; however, the mechanisms underlying these effects have yet to be elucidated. In this study, we investigated whether the inhibition of testosterone synthesis by nano-TiO2 on Leydig cells (LCs) was related to the dysfunction of the cAMP/CGMP/EGFR/MMP signaling pathway in primary cultures of LCs prepared from rat testis exposed to nano-TiO2. We found that the early apoptotic rate of LCs increased by 4.34 and 4.94 times, respectively, after exposure to 20 g/mL and 40 g/mL nano-TiO2 ; we also found that NO increased by 1.1 and 2.86 times, respectively. ROS increased by times of 0.71, 3.15 and 3.43; RNS increased by 0.62, 1.34 and 1.14 times; and SOD activity decreased by 18.3%, 28.16%, and 67.6%, respectively, when the concentration of nano-TiO2 was 10, 20 and 40 g/mL. These results indicated that nano-TiO2 treatment resulted caused damage to the LCs, including an imbalance of oxidation and antioxidation. Following nano-TiO2 treatment, the cAMP content had decreased by 48%, 48% and 47.6%; cGMP content had decreased by 18.7%, 52.2% and 56.7%; the levels of ATP in the LCs had decreased by 15.15%, 45.75% and 66.67%; the expression of HCGR protein had decreased by 26.7%, 45.07% and 74.64%; the expression of LHR protein had decreased by 18.3%, 28.16% and 67.6%; and the levels of T had decreased by 34.48%, 46.62% and 44.12%. Collectively, our results indicated that the inhibition of testosterone production by nano-TiO2 is related to the dysfunction of the cAMP/CGMP/EGFR/MMP signaling pathway.

Titanium Dioxide Inhibits Hippocampal Neuronal Synapse Growth Through the Brain-Derived Neurotrophic Factor-Tyrosine Kinase Receptor B Signaling Pathway.

Nanoparticulate titanium dioxide (nano-TiO2) is a commonly used nanoparticle material and has been widely used in the fields of medicine, cosmetics, construction, and environmental protection. Numerous studies have demonstrated that nano-TiO2 has toxic effects on neuronal development, which lead to defects in learning and memory functions. However, it is still unclear whether nano-TiO2 inhibits the development of synapse and the underlying molecular mechanism is still unknown. In this study, nano-TiO2 was administered to rat primary hippocampal neurons for 24 h to investigate the underlying molecular mechanisms behind the inhibition of neuronal synaptic development by nano-TiO2. We used hippocampal neurons as a model to study the effect of nano-TiO2 on synaptic development. Our results demonstrated that dendritic development that represented synaptic plasticity in hippocampal neurons was significantly inhibited in a concentration-dependent manner after exposure to nano-TiO2 for 24 h. Experiments with varying concentrations of nano-TiO2 (5, 15, and 30 g/mL) indicated that the apoptotic rate of hippocampal neurons increased, development of neuronal synapses were inhibited, and synaptic densities decreased by 24.29%, 54.29%, and 72.86%, respectively, in post-treatment with nano-TiO2. Furthermore, the results indicated that the expressions of Synapsin I (SYN I) and postsynaptic density 95 (PSD95) in neuron synapse were also significantly inhibited, particularly SYN I decreased by 18.43%, 37.2%, and 51.6%, and PSD95 decreased by 16.02%, 24.06%, and 38.74% after treatment with varying concentrations of nano-TiO2, respectively. In addition, experiments to assess the BDNF-TrkB signaling pathway indicated that nano-TiO2 inhibited the expressions of key proteins in the downstream MEK/ERK and PI3K/Akt signaling pathways by inhibiting the expression of BDNF. With concentrations of nano-TiO2 at 5, 15, and 30 µg/mL, the expression of BDNF decreased by 22.64%, 33.3%, and 53.58% compared with the control group. Further, the expression ratios of downstream key proteins p-CREB/CREB decreased by 3.03%, 18.11%, and 30.57%; p-ERK1/2/ERK1/2 ratios decreased by 19.11%, 28.82%, and 58.09%, and p-Akt1/Akt1 ratios decreased by 1.92%, 27.79%, and 41.33%, respectively. These results demonstrated that nano-TiO2 inhibited the normal function of the BDNF-TrkB signaling pathway, which is closely related to neuronal synapse. Thus, it can be hypothesized that the inhibition of neuronal synaptic growth by nano-TiO2 may be related to the inhibition of BDNF-TrkB signaling pathway.

Liver Inflammation and Fibrosis Induced by Long-Term Exposure to Nano Titanium Dioxide (TiO2) Nanoparticles in Mice and Its Molecular Mechanism.

Titanium dioxide (TiO2) and nano-sized titanium dioxide (nano-TiO2), which are used in food production, may be harmful to the body. Long-term exposure to nano-TiO2 can lead to hepatic injury; however, the effect of nano-TiO2 on liver fibrosis and the underlying mechanism remain unclear. The TGF-ß/Smad/MAPK/Wnt signaling pathway is important for tissue fibrosis. In this study, mice were fed nano-TiO2 (2.5, 5, and 10 mg/kg body weight) for nine consecutive months to investigate its effect on liver fibrosis. Nano-TiO2 induced hepatic inflammatory cell infiltration and hepatic fibrosis and upregulated the expression of HIF-1α (+75-fold to +2.38-fold), Wnt3 (+12% to +135%), Wnt4 (1.33-fold to 6-fold), NF-κB (+3.13% to +34.38%), TGF-ß1 (+1307-fold to +1.85-fold), TGF-ß1R (+0.8-fold to 1.33-fold), Smad-2 (+0.58-fold to +1.58-fold), ILK (+0.43-fold to +1.19-fold), ECM (+1.82-fold to 2.36-fold), calpain 2 (+0.11-fold to +0.78-fold), α-SMA (+0.63-fold to +1.56-fold), c-Myc (+0.27-fold to +0.46-fold), and collagen I (+8% to +36%), and increased the phosphorylation level of p38MAPK (+66.67% to +153.33%) in inflammatory and fibrotic liver tissues, whereas it downregulated cyclin D (-6.25% to -43.75%) and decreased the phosphorylation levels of GSK-3ß (-3.12% to -46.88%) and ß-catenin (-19.57% to -45.65%). These results indicate that hepatic fibrosis induced by nano-TiO2 is mediated by the TGF-ß/Smads/MAPK/Wnt signaling pathway. This study provides insight into the mechanism underlying hepatic toxicity induced by nano-TiO2 .

Nanostructured Titanium Dioxide (TiO2) Reduces Sperm Concentration Involving Disorder of Meiosis and Signal Pathway.

Nano-titanium dioxide (nano-TiO2) has been widely used in food and cosmetic industries, and the medical sector. However, nano-TiO2 is potentially toxic to the reproductive system. Previous research has shown that nano-TiO2 can reduce sperm concentration but do not yet known whether this effect occurs because of dysfunctional meiosis in spermatogenic cells. In the present paper, we demonstrate that Nano-TiO2 can penetrate through the blood-testis barrier of a mouse model and enter the testicular tissue, thus causing damage to the testis and epididymis. This reduced the number of developing sperm; we demonstrated that the mechanism underlying this effect was the inhibition or destruction of meiosis in spermatogenic cells, particularly during meiosis I. We also found that the inhibition of meiosis I caused by nano-TiO2 exposure was related to dysfunctional meiosis and that the abnormal expression of meiosis-related factors. Therefore, our data demonstrate that nano-TiO2 reduces sperm concentration by disrupting meiosis and related signaling pathways.