Long-term administration of simvastatin reduces ventilator-induced lung injury and upregulates heme oxygenase 1 expression in a rat model

Expression of heme oxygenase-1 in type II pneumocytes protects against heatstroke-induced lung damage

Heatstroke (HS) is an acute clinical disease characterized by abnormal hyperthermia and multi-organ dysfunction. Heme oxygenase (HO)-1, also called heat shock protein (HSP)32, is induced by hyperthermia and also plays protective roles in many lung disease models. Based on this phenomenon, we investigated the protective role of endogenous HO-1 in heat-induced lung damage in rats. Male Sprague-Dawley (SD) rats were separated into three groups: (a) normothermic sham, (b) HS, and (c) SnPP (inhibitor of HO-1) pretreatment rats. In the HS group, rats were killed at various time points (1, 3, 6, and 12 h after heat exposure) in order to analyze messenger ribonucleic acid (mRNA) and protein levels. Lung sections were examined for tissue damage and localization of HO-1 using immunofluorescence double labeling. We found that HS induced lung pathology (congested and thickened lung septa). The level of HO-1 mRNA was increased at 1 h, and the protein level peaked at 6 h after heat exposure. Pretreatment with SnPP (tin-protoporphyrin IX, 30 mg/kg, intraperitoneal injection for 1 h before heat exposure) aggravated the lung damage. Furthermore, we demonstrated HO-1 expression in lung type II pneumocytes. Our results suggest that endogenous HO-1 is protective against HS-induced lung damage. Induction of HO-1 may be a potential therapeutic strategy for treating heat-related diseases.

Human Umbilical Cord Mesenchymal Stromal Cells Attenuate Systemic Sepsis in Part by Enhancing Peritoneal Macrophage Bacterial Killing via Heme Oxygenase-1 Induction in Rats

BACKGROUND

Mesenchymal stromal cells have therapeutic potential in sepsis, but the mechanism of action is unclear. We tested the effects, dose-response, and mechanisms of action of cryopreserved, xenogeneic-free human umbilical cord mesenchymal stromal cells in a rat model of fecal peritonitis, and examined the role of heme oxygenase-1 in protection.

METHODS

Separate in vivo experiments evaluated mesenchymal stromal cells in fecal sepsis, established dose response (2, 5, and 10 million cells/kg), and the role of heme oxygenase-1 in mediating human umbilical cord-derived mesenchymal stromal/stem cell effects. Ex vivo studies utilized pharmacologic blockers and small inhibitory RNAs to evaluate mechanisms of mesenchymal stromal cell enhanced function in (rodent, healthy and septic human) macrophages.

RESULTS

Human umbilical cord mesenchymal stromal cells reduced injury and increased survival (from 48%, 12 of 25 to 88%, 14 of 16, P = 0.0033) in fecal sepsis, with dose response studies demonstrating that 10 million cells/kg was the most effective dose. Mesenchymal stromal cells reduced bacterial load and peritoneal leukocyte infiltration (from 9.9 ± 3.1 × 10/ml to 6.2 ± 1.8 × 10/ml, N = 8 to 10 per group, P < 0.0001), and increased heme oxygenase-1 expression in peritoneal macrophages, liver, and spleen. Heme oxygenase-1 blockade abolished the effects of mesenchymal stromal cells (N = 7 or 8 per group). Mesenchymal stromal cells also increased heme oxygenase-1 expression in macrophages from healthy donors and septic patients. Direct ex vivo upregulation of macrophage heme oxygenase-1 enhanced macrophage function (phagocytosis, reactive oxygen species production, bacterial killing). Blockade of lipoxin A4 production in mesenchymal stromal cells, and of prostaglandin E2 synthesis in mesenchymal stromal cell/macrophage cocultures, prevented upregulation of heme oxygenase-1 in macrophages (from 9.6 ± 5.5-fold to 2.3 ± 1.3 and 2.4 ± 2.3 respectively, P = 0.004). Knockdown of heme oxygenase-1 production in macrophages ablated mesenchymal stromal cell enhancement of macrophage phagocytosis.

CONCLUSIONS

Human umbilical cord mesenchymal stromal cells attenuate systemic sepsis by enhancing peritoneal macrophage bacterial killing, mediated partly via upregulation of peritoneal macrophage heme oxygenase-1. Lipoxin A4 and prostaglandin E2 play key roles in the mesenchymal stromal cell and macrophage interaction.

Response of PXR signaling pathway to simvastatin exposure in mosquitofish (Gambusia affinis) and its histological changes

As a widely used lipid lowering agent, simvastatin recently has been frequently detected in aquatic environment and the potential adverse effects from simvastatin exposure to non-target organisms such as fish is worthy of more attention. The aim of this study was to reveal the responses of detoxification system in fish to simvastatin exposure. In this investigation a ubiquitous small freshwater fish, mosquito fish (Gambusia affinis), was employed as test organism, and the transcriptional expression of nucleus transcriptional factor pregnane X receptor (PXR) and its downstream genes, including P-glycoprotein (P-gp), cytochrome 3A (CYP3A), multidrug resistance protein 2 (MRP2), UDP-glucuronosyl transferase (UGT) in mosquito fish were investigated by qRT-PCR methods under the exposure of concentrations of simvastatin (0.5 μg L-1, 5 μg L-1, 50 μgL-1, 500 μg L-1) for 24 h, 72 h and 168 h. The related enzyme activity (Erythromycin-N-Demethylase, ERND), the protein expression of PXR and the histological changes of liver tissues in fish were also determined via west blotting and transmission electron microscope approaches in the same conditions. Results showed that the mRNA expression of PXR, CYP3A and P-gp showed significantly changes under simvastatin exposure, exhibiting an obvious time/dose-effect relationship with the prolong of exposure time. ERND activity also showed time-effect at 24 h, and western blotting showed PXR protein displaying a dose-effect relationship to some extent. Hepatocyte cellular of mosquito fish exposed to simvastatin (5 μg L-1, 168 h) exhibited obvious histological changes in form of swelling, incomplete fragmentary structure etc. Overall, simvastatin altered the expression of PXR signaling pathway and subsequently bring about changes in high-levels of mosquito fish.

Simvastatin Inhibits Activation of NADPH Oxidase/p38 MAPK Pathway and Enhances Expression of Antioxidant Protein in Parkinson Disease Models

Evidence suggests that oxidative stress is involved in the pathogenesis of Parkinson disease (PD). Simvastatin has been suggested to protect against oxidative stress in several diseases. However, the molecular mechanisms by which simvastatin protects against neuropathology and oxidative damage in PD are poorly elucidated. In this study, we aimed to investigate the potential neuroprotective effects of simvastatin owing to its anti-oxidative properties in 6-hydroxydopamine (6-OHDA)-treated SH-SY5Y cells and mice. The results of 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence and CCK-8 assay demonstrated that simvastatin reduced intracellular reactive oxygen species (ROS) levels and reversed apoptosis in 6-OHDA-treated SH-SY5Y cells. Mechanistic studies revealed that 6-OHDA-induced activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase/p38 mitogen-activated protein kinase (MAPK) pathway was inhibited and nuclear factor-κB (NF-κB) nuclear transcription decreased in SH-SY5Y cells after simvastatin treatment. Enhanced expression levels of superoxide dismutase (SOD), heme oxygenase-1 (HO-1), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and glutamate-cysteine ligase modifier subunit (GCLM) were observed after simvastatin treatment in 6-OHDA-treated SH-SY5Y cells. In vivo studies revealed that administration of simvastatin by gavage decreased limb-use asymmetry and apomorphine-induced rotations in 6-OHDA-lesioned mice. Simvastatin increased dopaminergic neurons and reduced protein tyrosine nitration and gliosis in the midbrain of PD mice. An inhibitory effect on activation of the NADPH oxidase/p38 MAPK was observed, and increased antioxidant protein expression in the midbrain were seen in the simvastatin plus 6-OHDA group compared with the 6-OHDA-lesioned group. Taken together, these results demonstrate that simvastatin might inhibit the activation of NADPH oxidase/p38 MAPK pathway, enhance antioxidant protein expression and protect against oxidative stress, thereby providing a novel antioxidant mechanism that has therapeutic validity.

Simvastatin Treatment Modulates Mechanically-Induced Injury and Inflammation in Respiratory Epithelial Cells

Mechanical forces in the respiratory system, including surface tension forces during airway reopening and high transmural pressures, can result in epithelial cell injury, barrier disruption and inflammation. In this study, we investigated if a clinically relevant pharmaceutical agent, Simvastatin, could mitigate mechanically induced injury and inflammation in respiratory epithelia. Pulmonary alveolar epithelial cells (A549) were exposed to either cyclic airway reopening forces or oscillatory transmural pressure in vitro and treated with a wide range of Simvastatin concentrations. Simvastatin induced reversible depolymerization of the actin cytoskeleton and a statistically significant reduction the cell's elastic modulus. However, Simvastatin treatment did not result in an appreciable change in the cell's viscoelastic properties. Simvastatin treated cells did exhibit a reduced height-to-width aspect ratio and these changes in cell morphology resulted in a significant decrease in epithelial cell injury during airway reopening. Interestingly, although very high concentrations (25-50 µM) of Simvastatin resulted in dramatically less IL-6 and IL-8 pro-inflammatory cytokine secretion, 2.5 µM Simvastatin did not reduce the total amount of pro-inflammatory cytokines secreted during mechanical stimulation. These results indicate that although Simvastatin treatment may be useful in reducing cell injury during airway reopening, elevated local concentrations of Simvastatin might be needed to reduce mechanically-induced injury and inflammation in respiratory epithelia.