Inhibition of mitochondrial fission and protein kinase R improves progesterone in placental stress.

Placenta synthesizes hormones that play a vital role in adapting maternal physiology and supporting fetal growth. This study aimed to explore the link between progesterone, a key steroid hormone produced by placenta, and mitochondrial fission and protein kinase R through the use of chemical inhibition in trophoblasts subjected to endotoxin lipopolysaccharide and double-stranded RNA analog polyinosinic:polycytidylic acid stress. Expressions of protein kinase R, dynamin-related protein 1, mitochondrial fission protein 1, and heat shock protein 60 were determined by applying lipopolysaccharide and polyinosinic:polycytidylic acid to BeWo trophoblast cells. Next, cells were treated with protein kinase R inhibitor 2-aminopurine and mitochondrial division inhibitor 1 to examine changes in progesterone levels and expression levels of proteins and mRNAs involved in progesterone biosynthesis. Last, effect of 2-aminopurine on mitochondrial fission was determined by immunoblotting and quantitative PCR (qPCR). Mitochondrial structural changes were also examined by transmission electron microscopy. Lipopolysaccharide and polyinosinic:polycytidylic acid stimulation induced mitochondrial fission and activated protein kinase R but decreased heat shock protein 60 levels and progesterone synthesis. Chemical inhibition of mitochondrial fission elevated progesterone synthesis and protein and mRNA levels of genes involved in progesterone biosynthesis. Inhibition of protein kinase R with 2-aminopurine prevented lipopolysaccharide and polyinosinic:polycytidylic acid induced mitochondrial fission and increased progesterone biosynthesis. Use of chemical inhibitors to treat placental stress caused by pathogens has potential to stabilize the production of progesterone. The study reveals that inhibiting mitochondrial fragmentation and reducing activity of stress kinase protein kinase R in syncytiotrophoblasts leads to an increase in progesterone synthesis when exposed to lipopolysaccharide and polyinosinic:polycytidylic acid.

The role of protein kinase R in placental inflammation, mtUPR and apoptosis.

INTRODUCTION: Placental inflammation is implicated in the pathophysiology of many pregnancy complications, including fetal growth restriction, preeclampsia, gestational diabetes, and choriocarcinoma. Mitochondrial dysfunction, one of the outcomes of placental inflammation, is characterized by loss of membrane potential, accumulation of oxygen radicals, mitochondrial protein folding defects, and disturbances in mitochondrial dynamics. Protein kinase R (PKR) is stimulated by double-stranded RNA and bacterial endotoxins in the presence of pathogens and is a critical immune response enzyme. PKR is also correlated with the cell death response during endoplasmic reticulum stress. In this study, we aim to investigate the effects of PKR activity stimulated by lipopolysaccharide (LPS), and double-stranded RNA analog (Poly I:C) on mitochondrial unfolded protein response (mtUPR), mitochondrial membrane potential, apoptosis, and oxidative stress in placental trophoblasts. METHODS: We applied LPS and Poly I:C to BeWo cells to induce PKR activation. In addition, cells were treated with 2-aminopurine (2-AP) to inhibit the kinase activity of PKR. Protein levels of ATP-dependent Clp protease proteolytic subunit (CLPP) and heat shock protein 60 (HSP60) were determined after treatments. Apoptotic markers were detected by real-time PCR and flow cytometry. PKR-induced reactive oxygen radicals (ROS) accumulation and mitochondrial membrane potential change were assessed by flow cytometry. RESULTS: It was determined that PKR activation-induced apoptosis in BeWo cells by reducing the levels of mtUPR proteins (CLPP and HSP60) and caused a decrease in mitochondrial membrane potential. PKR inhibition was sufficient for decreases in apoptotic markers and caused a reduction in the ratio of depolarized and ROS (+) cells. DISCUSSION: Our results showed that LPS and Poly I:C administration stimulated PKR in BeWo cells in vitro. Furthermore, PKR activation is correlated with the levels of proteins involved in mitochondrial homeostasis and apoptosis. Our findings will contribute to understanding the role of PKR activation in placental inflammation and related diseases.

Chemical inhibition of mitochondrial fission improves insulin signaling and subdues hyperglycemia induced stress in placental trophoblast cells.

BACKGROUND: Gestational diabetes mellitus (GDM) is a metabolic complication that affects millions of pregnant women in the world. Placental tissue function is endangered by hyperglycemia during GDM, which is correlated to increased incidences of pregnancy complications. Recently we showed that due to a significant decrease in mitochondrial fusion, mitochondrial dynamics equilibrium is altered in placental tissues from GDM patients. Evidence for the role of reduced mitochondrial fusion in the disruption of mitochondrial function in placental cells is limited. METHODS AND RESULTS: Here we show that chemical inhibition of mitochondrial fission in cultured placental trophoblast cells leads to an increase in mitochondrial fusion and improves the physiological state of these cells and hence, their capacity to cope in a hyperglycemic environment. Specifically, mitochondrial fission inhibition led to a reduction in reactive oxygen species (ROS) generation, mitochondrial unfolded protein marker expressions, and mitochondrial depolarization. It supported the increase in mitochondrial antioxidant enzyme expressions as well. Mitochondrial fission inhibition also increases the placental cell insulin sensitivity during hyperglycemia. CONCLUSION: Our results suggest that mitochondrial fusion/fission equilibrium is critical for placental cell function and signify the therapeutic potential of small molecule inhibitors of fission during GDM.

The effect of gestational diabetes on the expression of mitochondrial fusion proteins in placental tissue.

INTRODUCTION: Gestational diabetes mellitus (GDM) poses a risk factor for fetal mortality and morbidity by directly affecting the placenta and fetus. Mitochondria are dynamic organelles that play a key role in energy production and conversion in placental tissue. Mitochondrial fusion and fission proteins are important in terms of providing mitochondrial dynamics, the adaptation of the cell to different conditions, and maintaining the metabolic stability of the cells. Although GDM shares many features with Type 2 diabetes mellitus (T2DM), different effects of these conditions on the mother and the child suggest that GDM may have specific pathological effects on placental cells. The aim of this study is to investigate the expression of mitochondrial dynamics, and mitochondrial protein folding markers in placentas from GDM patients and women with pre-existing diabetes mellitus. METHODS: Placentas were properly collected from women, who had pre-existing diabetes (Pre-DM), from women with gestational diabetes mellitus (GDM) and from healthy (non-diabetic) pregnant women. Levels of mitochondrial fusion markers were determined in these placentas by real time quantitative PCR and Western blot experiments. RESULTS: mRNA expressions and protein levels of mitochondrial fusion markers, mitofusin 1, mitofusin 2 (MFN1 and MFN2) and optical atrophy 1 (OPA1) proteins were found to be significantly lower in both Pre-DM placentas and those with GDM compared to healthy (non-diabetic) control group. Likewise, proteins involved in mitochondrial protein folding were also found to be significantly reduced compared to control group. DISCUSSION: Diabetes during pregnancy leads to processes that correlate with mitochondria dysfunction in placenta. Our results showed that mitochondrial fusion markers significantly decrease in placental tissue of women with GDM, compared to the healthy non-diabetic women. The decrease in mitochondrial fusion markers was more severe during GDM compared to the Pre-DM. Our results suggest that there may be differences in the pathophysiology of these conditions.

PKR inhibitors suppress endoplasmic reticulum stress and subdue glucolipotoxicity-mediated impairment of insulin secretion in pancreatic beta cells.

Type 2 diabetes mellitus is characterized by insulin resistance and hypersecretion of insulin from the pancreas to compensate for decreased insulin sensitivity in the peripheral tissues. In later stages of the disease insulin-secreting beta cell degeneration commences and patients require insulin replacement therapy in order to accomplish proper regulation of their blood glucose. Endoplasmic reticulum (ER) stress in the beta cells is one of the factors contributing to this detrimental effect. Protein kinase R (PKR) is a cellular stress kinase activated by ER stress and contributing to degeneration of pancreatic islets. In order to determine whether inhibition of PKR activation by specific small molecule inhibitors of PKR ameliorates pancreatic insulin secretion capacity, we treated beta cells with two imidazole/oxindole-derived inhibitors of PKR kinase, imoxin (C16) and 2-aminopurine (2-AP), in the presence of ER stress. Our results demonstrate that PKR inhibition suppresses tunicamycin-mediated ER stress without altering the insulin production capacity of the cells. Palmitic acid-mediated suppression of insulin secretion, however, was subdued significantly by PKR inhibitor treatment through an ER stress-related mechanism. We suggest that PKR inhibitor treatment may be used to increase the insulin secretion capacity of the pancreas in later stages of diabetes.

Naringenin Ameliorate Carbon Tetrachloride-Induced Hepatic Damage Through Inhibition of Endoplasmic Reticulum Stress and Autophagy in Rats.

Hepatic fibrosis emerges upon exposure of liver to various chemicals and if not treated, it develops various diseases such as cirrhosis and cancer. Carbon tetrachloride (CCl4) is a widely used toxin in animal models to develop hepatic fibrosis. Accumulation of unfolded proteins in cells causes stress in the endoplasmic reticulum (ER) and various mechanisms are involved in the cell to reduce the damage caused by these unfolding proteins. The most well known of these is the unfolded protein response. Further, autophagy works to remove these proteins if the damage cannot be repaired and is permanent. In our study, we investigated the effects of naringenin (NRG), a flavanon abundant in citrus fruits, on ER stress and autophagy in CCl4-injured rat liver. The animals were given 0.2 mL/kg of CCl4 for 10 days and treatment group was administered 100 mg/kg of NRG for 14 days. Histopathological examination was performed to show liver damage and to determine the therapeutic properties of the active substance. Transmission electron microscopy (TEM) analysis was carried out to establish cell level damage and effect of treatment. In addition, levels of ER stress and autophagy markers of liver were measured. According to our findings, TEM demonstrated positive effect of NRG and histological examinations reported ameliorative effects. In addition, NRG reduced levels of ER stress markers and inhibited autophagy significantly compared to CCl4-treated group. As a result, NRG significantly reduced damage in hepatocytes and provided a significant amelioration.

Propolis Protects Endotoxin Induced Acute Lung and Liver Inflammation Through Attenuating Inflammatory Responses and Oxidative Stress.

Propolis is a natural bee product, and it has many effects, including antioxidant, anti-inflammatory, antihepatotoxic, and anticancer activity. In this study, we aimed to explore the potential in vivo anti-inflammatory, antioxidant, and antiapoptotic properties of propolis extract on lipopolysaccharide (LPS)-induced inflammation in rats. Forty-two, 3- to 4-month-old male Sprague Dawley rats were used in six groups. LPS (1 mg/kg) was administered intraperitoneally to rats in inflammation, inflammation + propolis30, and inflammation+propolis90 groups. Thirty milligram/kilogram and 90 mg/kg of propolis were given orally 24 h after LPS injection. After the determination of the inflammation in lung and liver tissues by 18F-fluoro-deoxy-d-glucose-positron emission tomography (18FDG-PET), samples were collected. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), nitric oxide (NO), and DNA fragmentation were determined. The decrease of MDA levels in inflammation + propolis30 and inflammation + propolis90 groups was determined compared to the inflammation group in lung and liver tissues. The increase of SOD% inhibition in inflammation + propolis90 group was determined in liver, lung, and hemolysate compared to the inflammation group. Increased CAT activities in inflammation + propolis30 and inflammation + propolis90 groups were observed in liver tissue and hemolysate compared to inflammation group. In lung tissue, NO levels were lower in inflammation group compared to the control group, but DNA fragmentation levels were higher. 18F-FDG uptake of tissues in inflammation + propolis30 and inflammation + propolis90 groups was decreased compared to the inflammation group. In conclusion, the data of this study indicate that the propolis application may serve as a potential approach for treating inflammatory diseases through the effect of reducing inflammation and free oxygen radical production.

Posttreatment Effects of Olea Europaea L. Leaf Extract on Carbon Tetrachloride-Induced Liver Injury and Oxidative Stress in Rats.

The aim of this study is to examine the therapeutic effects of Olea europaea L. leaf extract on carbon tetrachloride (CCl4)-induced liver damage in rats. In the experiments, 3- to 4-month-old 28 male Sprague-Dawley rats were divided into four groups: control, O. europaea leaf extract, CCl4, and curative. The CCl4 and curative groups received CCl4 (0.2 mL/kg) intraperitoneally for 10 days to form hepatic injury. O. europaea (80 mg/kg) leaf extract was given orally to the curative group dissolved in distilled water the following 14 days. Hepatic and antioxidant enzyme levels, p53, caspase 3, lipid peroxidation marker malondialdehyde (MDA), and also DNA fragmentation levels were determined to establish oxidative stress in hepatic cell damage and its consequences. After formation of liver damage, oral administration of the O. europaea significantly reduced CCl4-induced elevations of serum alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase levels (P < .001), MDA levels of both blood (P < .001) and liver tissues (P < .001), DNA fragmentation (P < .001), p53 (P < .001), and caspase 3 (P < .001) levels of liver tissues. Also this administration in curative group significantly increased CCl4-induced reductions of superoxide dismutase (SOD) (P < .001) and catalase (CAT) (P < .001) activity of blood samples and decreased SOD (P < .001) and CAT (P < .05) activity observed in liver tissue curative groups compared with CCl4 curative group. In CCl4 group, liver tissue samples exhibited remarkable damage because of CCl4 and reduction of these damages were observed in the curative group. Our results showed that O. europaea leaf extract was effective in reducing hepatic damage caused by CCl4 by reducing lipid peroxidation, regulating antioxidant enzymes, and minimizing DNA damage.

The Anti-Inflammatory and Antioxidant Effects of Salvia officinalis on Lipopolysaccharide-Induced Inflammation in Rats.

Salvia officinalis, which has a high phenolic acid and flavonoid content, is a powerful antioxidant and anti-inflammatory herb. Inflammation plays an important role in the pathophysiology of many diseases and could cause damage by means of oxidative stress. The aim of this study was to investigate the anti-inflammatory and antioxidant activity of S. officinalis formed lipopolysaccharide (LPS)-induced experimental inflammation model. Four- to five-month-old 42 female Wistar albino rats were divided into six groups. Three groups were administered intraperitoneally 1 mg/kg LPS. Twenty-four hours after injection of LPS, 10 and 30 mg/kg S. officinalis extract were given orally to treatment groups. Pulmonary and hepatic 18F-fluoro-deoxy-D-glucose (18F-FDG) uptake was calculated to determine the status of inflammation by 18F-fluoro-deoxy-D-glucose-positron emission tomography (18FDG-PET) scan. Antioxidant enzyme activities and nitric oxide (NO) and malondialdehyde (MDA) levels were determined. Nuclear factor-kappa B (NF-κB) and tumor necrosis factor-alpha (TNF-α) levels were also detected in serum. As a result, lung and liver 18F-FDG uptake was found to be higher in the inflammation group than control group. MDA levels in erythrocyte and all tissue samples (liver, lung, and kidney) were found to be significantly higher compared to treatment groups. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase activities of the inflammation group in the liver, lung, kidney tissues, and erythrocyte SOD and CAT activities were determined to significantly lower than groups treated with S. officinalis. Increased NO, NF-κB, and TNF-α levels were found in the inflammation group. S. officinalis has been observed to have useful effects on LPS-induced inflammation and oxidative stress in rats.