Cytotoxicity induced by fine particulate matter (PM2.5) via mitochondria-mediated apoptosis pathway in rat alveolar macrophages

Although positive associations exist between ambient particulate matter (PM_2.5; diameter ≤ 2.5 μm) and the morbidity and mortality rates for respiratory diseases, the biological mechanisms of the reported health effects are unclear. Considering that alveolar macrophages (AM) are the main cells responsible for phagocytic clearance of xenobiotic particles that reach the airspaces of the lungs, the purpose of this study was to investigate whether PM_2.5 induced AM apoptosis, and investigate its possible mechanisms. Freshly isolated AM from Wistar rats were treated with extracted PM_2.5 at concentrations of 33, 100, or 300 μg/mL for 4 h; thereafter, the cytotoxic effects were evaluated. The results demonstrated that PM_2.5 induced cytotoxicity by decreasing cell viability and increasing lactate dehydrogenase (LDH) levels in AMs. The levels of reactive oxygen species (ROS) and intracellular calcium cations (Ca²⁺) markedly increased in higher PM_2.5 concentration groups. Additionally, the apoptotic ratio increased, and the apoptosis-related proteins BCL2-associated X (Bax), caspase-3, and caspase-9 were upregulated, whereas B cell lymphoma-2 (Bcl-2) protein levels were downregulated following PM_2.5 exposure. Cumulative findings showed that PM_2.5 induced apoptosis in AMs through a mitochondrial-mediated pathway, which indicated that PM_2.5 plays a significant role in lung injury diseases.

Ginsenoside Rb 1: A novel therapeutic agent in Staphylococcusaureus-induced Acute Lung Injury with special reference to Oxidative stress and Apoptosis

Acute lung injury (ALI) is considered as an uncontrolled inflammatory response that can leads to acute respiratory distress syndrome (ARDS), which limits the therapeutic strategies. Ginsenosides Rb1 (Rb1), an active ingredient obtained from Panax ginseng, possesses a broad range of pharmacological and medicinal properties, comprising the anti-inflammatory, anti-oxidant, and anti-tumor activities. Therefore, the purpose of the present study was to investigate the protective effects of Rb1 against S. aureus-induced (ALI) through regulation of Nuclear factor erythroid 2-related factor 2 (Nrf2) and mitochondrial-mediated apoptotic pathways in mice (in-vivo), and RAW264.7 cells (in-vitro). For that purpose, forty Kunming mice were randomly assigned into four treatment groups; (1) Control group (phosphate buffer saline (PBS); (2) S. aureus group; (3) S. aureus + Rb1 (20 mg/kg) group; and (4) Rb1 (20 mg/kg) group. The 20 μg/mL dose of Rb1 was used in RAW264.7 cells. In the present study, we found that Rb1 treatment reduced ALI-induced oxidative stress via suppressing the accumulation of malondialdehyde (MDA) and myeloperoxidase (MPO) and increase the antioxidant enzyme activities of superoxidase dismutase 1 (SOD1), Catalase (CAT), and glutathione peroxidase 1 (Gpx1). Similarly, Rb1 markedly increased messenger RNA (mRNA) expression of antioxidant genes (SOD1, CAT and Gpx1) in comparison with ALI group. The histopathological results showed that Rb1 treatment ameliorated ALI-induced hemorrhages, hyperemia, perivascular edema and neutrophilic infiltration in the lungs of mice. Furthermore, Rb1 enhanced the antioxidant defense system through activating the Nrf2 signaling pathway. Our findings showed that Rb1 treated group significantly up-regulated mRNA and protein expression of Nrf2 and its downstream associated genes down-regulated by ALI in vivo and in vitro. Moreover, ALI significantly increased the both mRNA and protein expression of mitochondrial-apoptosis-related genes (Bax, caspase-3, caspase-9, cytochrome c and p53), while decreased the Bcl-2. In addition, Rb1 therapy significantly reversed the mRNA and protein expression of these mitochondrial-apoptosis-related genes, as compared to the ALI group in vivo and in vitro. Taken together, Rb1 alleviates ALI-induced oxidative injury and apoptosis by modulating the Nrf2 and mitochondrial signaling pathways in the lungs of mice.

Cytotoxicity induced by fine particulate matter (PM2.5) via mitochondria-mediated apoptosis pathway in human cardiomyocytes

Although the strongly causal associations were between fine particulate matter (PM_2.5) and cardiovascular disease, the toxic effect and potential mechanism of PM_2.5 on heart was poorly understood. Thus, the aim of this study was to evaluate the cardiac toxicity of PM_2.5 exposure on human cardiomyocytes (AC16). The cell viability was decreased while the LDH release was increased in a dose-dependent way after AC16 exposed to PM_2.5. The reactive oxygen species (ROS) generation and production of malondialdehyde (MDA) were increased followed by the decreasing in superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). The damage of mitochondria was observed by ultra-structural analysis and MMP measurement. The apoptotic rate of AC16 were markedly elevated which was triggered by PM_2.5. In addition, the proteins involved in mitochondria- mediated apoptosis pathway were measured. The protein levels of Caspase-3, Caspase-9 and Bax were up-regulated while the anti-apoptotic protein, Bcl-2 was down-regulated after AC16 exposed to PM_2.5. In summary, our results demonstrated that mitochondria-mediated apoptosis pathway played a critical role in PM_2.5-induced myocardial cytotoxicity in AC16, which suggested that PM_2.5 may contribute to cardiac dysfunction.

Pseudolaric acid B inhibits gastric cancer cell metastasis in vitro and in haematogenous dissemination model through PI3K/AKT, ERK1/2 and mitochondria-mediated apoptosis pathways

Pseudolaric acid B (PAB) is the major bioactive constituent in the root bark of Pseudolarix kaempferi and has been reported to have cytotoxicity against tumor cells. Our in vivo experiments showed that PAB could inhibit gastric cancer cell lung metastasis in a nude mouse haematogenous dissemination model. To evaluate the anti-metastasis mechanism of PAB in gastric cancer cells, cytological experiments were performed. The results showed that PAB could inhibit the adhesion ability to matrigel, migration, invasion and colony formation ability of BGC-823 and MKN-45 cells. Western blot further confirmed that the inhibitory effects of PAB on anti-metastasis may involve regulating the expression of the metastasis-related proteins MMP-9, HIF-1α, VEGF, VEGFR2, E-Cadherin and Ezrin. We obtained further proof that PAB which could be used as a multi-targeted agent to inhibit the PI3K/AKT, ERK1/2 and mitochondria-mediated apoptosis pathways and consequently suppress tumor growth and metastasis. Our experiments suggest that PAB-induced effects may have novel therapeutic applications for the treatment of gastric cancer.