Lihua Ren

Silica nanoparticles induce reversible damage of spermatogenic cells via RIPK1 signal pathways in C57 mice.

The reproductive toxicity of silica nanoparticles (SiNPs) is well known, but the underlying mechanism is still not clear. To investigate the toxic mechanism of SiNPs on spermatogenic cells, 60 C57 male mice were randomly and equally divided into three groups (the control group, the saline control group, and the SiNPs group) with two observed time points (45 days and 75 days). The mice in the SiNPs group were administered with SiNPs 2 mg/kg diluted in normal saline, and the mice of the saline control group were given equivoluminal normal saline by tracheal perfusion every 3 days for 45 days (in total 15 times). The control group mice were bred without treatment. In each group, a half number of the mice were sacrificed on the 45th day after the first dose, and the remaining half were sacrificed on the 75th day. The results showed that SiNPs increased the malformation of sperms and decreased the motility and concentration of sperms in epididymis on the 45th day after the first dose. SiNPs induced oxidative stress in testis and led to apoptosis and necroptosis of the spermatogenic cells. Furthermore, SiNPs increased the expression of Fas/FasL/RIPK1/FADD/caspase-8/caspase-3 and RIPK3/MLKL on the 45th day after the first dose. However, compared with the saline control group, the index of sperms and the expression of Fas/FasL/RIPK1/FADD/caspase-8/caspase-3/RIPK3/MLKL showed no significant changes in the SiNPs group on the 75th day after the first dose. These data suggested that SiNPs could induce apoptosis and necroptosis in the spermatogenic cells by activating the RIPK1 pathway resulting from oxidative stress in male mice. SiNPs-induced damage recovered on the 75th day after the first dose, which suggested that SiNPs-induced toxicity is reversible.

Endosulfan induces cell dysfunction through cycle arrest resulting from DNA damage and DNA damage response signaling pathways

Our previous study showed that endosulfan increases the risk of cardiovascular disease. To identify toxic mechanism of endosulfan, we conducted an animal study for which 32 male Wistar rats were randomly and equally divided into four groups: Control group (corn oil only) and three treatment groups (1, 5 and 10mgkg-1·d-1). The results showed that exposure to endosulfan resulted in injury of cardiac tissue with impaired mitochondria integrity and elevated 8-OHdG expression in myocardial cells. Moreover, endosulfan increased the expressions of Fas, FasL, Caspase-8, Cleaved Caspase-8, Caspase-3 and Cleaved Caspase-3 in cardiac tissue. In vitro, human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of endosulfan (1, 6 and 12μgmL-1) for 24h. An inhibitor for Ataxia Telangiectasia Mutated Protein (ATM) (Ku-55933, 10μM) was added in 12μgmL-1 group for 2h before exposure to endosulfan. Results showed that endosulfan induced DNA damage and activated DNA damage response signaling pathway (ATM/Chk2 and ATR/Chk1) and consequent cell cycle checkpoint. Furthermore, endosulfan promoted the cell apoptosis through death receptor pathway resulting from oxidative stress. The results provide a new insight for mechanism of endosulfan-induced cardiovascular toxicity which will be helpful in future prevention of cardiovascular diseases induced by endosulfan.

Metabolic impact induced by total, water soluble and insoluble components of PM 2.5 acute exposure in mice

Fine particulate matter (PM2.5) has been listed as an important environmental risk factor for human health. However, the systemic biological effects on metabolic responses induced by PM2.5 and its components were poorly understood. This study was aimed to evaluate the toxicity of different components of PM2.5 at molecular level via metabolomics approach. In the present study, we adopted a 1H NMR-based metabolomics approach to evaluate metabolic profiles in mice after acute exposure to Total-PM2.5, water soluble components of PM2.5 (WS-PM2.5) and water insoluble components of PM2.5 (WIS-PM2.5). First, we characterized the morphological features and chemical composition of PM2.5. Then, the metabolites changes of serum and urine in mice were systematically analyzed using 800 MHz 1H NMR techniques in combination with multivariate statistical analysis. Total-PM2.5 exposure affected metabolites mainly involved in amino acid metabolism, protein biosynthesis, energy metabolism and metabolism of cofactors and vitamins. WS-PM2.5 exposure influenced lipid metabolism and carbohydrate metabolism. WIS-PM2.5 exposure mainly perturbed amino acid metabolism and energy metabolism. The results suggested that acute exposure to the Total-PM2.5, WS-PM2.5 and WIS-PM2.5 in mice exhibited marked systemic metabolic changes. In addition, the insoluble fraction of PM2.5 contributed greatly to the toxicity of PM2.5.

Silica nanoparticles induce abnormal mitosis and apoptosis via PKC-δ mediated negative signaling pathway in GC-2 cells of mice

The potential health hazards of silica nanoparticles (SiNPs) have attracted more and more attentions. Researches had shown that SiNPs could damage seminiferous epithelium and reduce the quantity and quality of sperms, however the specific mechanism of male reproductive toxicity induced by SiNPs still unclear. So we designed to investigate the mechanism of SiNPs on male mice using spermatocyte lines (GC-2spd cells) after exposure to SiNPs (6.25, 12.5, 25 and 50 μg/mL) for 24 h. The present study showed that SiNPs entered GC-2 cells and mainly localized in the cytoplasm and lysosome. And internalized SiNPs damaged mitochondria structures. As a result, SiNPs not only induced a dose-dependent reduction in cell viability, but also increased the LDH release and apoptosis rate in GC-2 cells. Furthermore, SiNPs induced DNA strand breaks and abnormal mitosis, and arrested GC-2 cells at the G0/G1 phase. Besides, SiNPs could simultaneously activate both PKC-mediated negative signaling pathway (PKC-δ/p53/p21cip1) and positive signaling pathway (PKC-α/MAPK). However, the lower expressions of cyclin E and cyclin-dependent kinases 2 (CDK2) indicated that PKC-δ signaling pathway played a major role in cell cycle process. These results suggested internalized SiNPs in GC-2 cells induced DNA strand breaks and activated PKC-mediated signaling pathway. While the activation of PKC-δ signaling pathway led to cell cycle arrest and apoptosis, thereby resulting in abnormal mitosis. The present study may provide a new evidence to elucidate the toxic mechanisms of male reproductive system, and will be beneficial for safety assessment of SiNPs products.