Metabolic syndrome enhances endoplasmic reticulum, oxidative stress and leukocyte-endothelium interactions in PCOS

Multi-system reproductive metabolic disorder: significance for the pathogenesis and therapy of polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS), a multisystem disease, is a major reason for female infertility around the world. It is no longer considered simply as a disease of ovary. Now researchers growing awareness of the multisystem features of this disease. PCOS has a higher relationship with metabolic disturbance and hypothalamic-pituitary-ovarian axis (HPOA) function disorders. This syndrome results in hyperandrogenemia (HA), hyperinsulinemia/insulin resistance (IR), increased estrone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) ratio imbalance, infertility, cardiovascular diseases, endometrial dysfunction, obesity, and including a litany of other health issues. Furthermore, PCOS has been garnered in recent times. Interventions like metformin, orlistat, hormonal contraceptives, GLP1 agonists, and VitD have been applied to ameliorate or reverse the pathological characterization of PCOS. Moreover, drug-combined therapy of PCOS is superior to single drug administration. This review will focus on the recent progress in pathogenesis and therapy of PCOS.

PGC-1α protects against oxidized low-density lipoprotein and luteinizing hormone-induced granulosa cells injury through ROS-p38 pathway

Obese women with polycystic ovary syndrome (PCOS) often suffer from ovulation failure, which may be driven by granulosa cells (GCs) injury caused by increased levels of circulating oxidized low-density lipoprotein (ox-LDL) and luteinizing hormone (LH). PGC-1α may play an important role in this pathophysiological processes. However, the effect and the potential mechanism of PGC-1α on GCs injury evoked by obese PCOS is fully unclear. To investigate the protective effect and the potential mechanism of PGC-1α on GCs injury evoked by ox-LDL + LH stimulation. Patients with PCOS and women of normal reproductive age who undergoing egg retrievals and consenting for this research were collected. Those women were divided into normal-weight non-PCOS group, obese non-PCOS group, normal-weight PCOS group and obese PCOS group according to the body mass index (BMI) and PCOS diagnosis. Follicular fluid was collected and primary GCs were isolated. The levels of LH and ox-LDL in follicular fluid in the four groups were measured. And, the expressions of PGC-1α, cell apoptosis and ROS generation in primary GCs in the four groups were evaluated. After GCs from women of normal reproductive age at normal-weight pre-treated with adenovirus encoding PGC-1α (Ad-PGC-1α) prior to ox-LDL + LH treatment in vitro, the cell viability, apoptosis, apoptosis-related proteins expressions and ROS generation were evaluated by CCK-8 assay, AnnexinV/PI double staining, Western blot and H₂DCF-DA staining, respectively. The expression of PGC-1α was significantly decreased, whereas the cell apoptosis and ROS generation were significantly increased in GCs of PCOS group, especially obese PCOS group. Our data also revealed that over-expression of PGC-1α in GCs from women of normal reproductive age at normal-weight markedly inhibited cell injury, ROS generation and p38 activation, accompanied by increased Bcl-2 expression, decreased Bax and cleaved caspase-3 expressions induced by ox-LDL + LH stimulation. Ox-LDL + LH-induced cell apoptosis was abrogated by attenuation of ROS generation or p38 activation. Attenuation of ROS generation reversed ox-LDL + LH-induced p38 activation, however, p38 inhibitors had an effect on ROS generation. Our findings suggested that PGC-1α protected against ox-LDL + LH-induced GCs injury through inhibiting cell apoptosis. And, the mechanism may be related to the inhibition of ROS-initiated p38 pathway. Our data indicated that PGC-1α may be a potential therapeutic target for obese PCOS.

Oxidative stress and biochemical markers in prenatally androgenized sheep after neonatal treatment with GnRH agonist

Background

Disruption of the balance between the production of ROS and their removal through enzymatic and non-enzymatic (antioxidant) processes has been proposed as a new mechanism in the pathology of polycystic ovary syndrome (PCOS). Evidence from animal models of PCOS (prenatally androgenized sheep) has suggested that treatment with insulin sensitizers, but not antiandrogens, can reduce increases in ROS.

Materials and methods

In the present study, we investigated the effects of neonatal treatment with a gonadotropin-releasing hormone (GnRH) agonist (leuprolide acetate) on prenatally androgenized sheep with testosterone propionate to determine its impact on oxidative stress molecules (ferric reducing antioxidant power [FRAP], advanced oxidation protein product [AOPP], nitric oxide [NOx], albumin) at 8, 12, and 18 months of age.

Results

Androgenized ewes (but not leuprolide-treated ewes) showed reduced total cholesterol levels associated with a decrease in the ratio of visceral to subcutaneous adiposity (adjusted to abdominal area) as determined by computed tomography. In androgenized ewes at 12 months of age, an increase in subcutaneous fat and relative decrease in the visceral fat compartment did not affect the expression of REDOX markers. At 18 months of age, however, the levels of NOx metabolites decreased in androgenized animals, but remained close to normal in ewes subjected to neonatal treatment with leuprolide acetate. Other oxidative stress parameters (FRAP, AOPP, albumin) did not vary among groups.

Conclusion

Our results demonstrate that the GnRH agonist leuprolide (as a single dose after birth) had weak effects on markers of the oxidative stress balance.

Differential Expression Patterns of Glycolytic Enzymes and Mitochondria-Dependent Apoptosis in PCOS Patients with Endometrial Hyperplasia, an Early Hallmark of Endometrial Cancer, In Vivo and the Impact of Metformin In Vitro

The underlying mechanisms of polycystic ovarian syndrome (PCOS)-induced endometrial dysfunction are not fully understood, and although accumulating evidence shows that the use of metformin has beneficial effects in PCOS patients, the precise regulatory mechanisms of metformin on endometrial function under PCOS conditions have only been partially explored. To address these clinical challenges, this study aimed to assess the protein expression patterns of glycolytic enzymes, estrogen receptor (ER), and androgen receptor (AR) along with differences in mitochondria-dependent apoptosis in PCOS patients with and without endometrial hyperplasia in vivo and to investigate the effects of metformin in PCOS patients with endometrial hyperplasia in vitro. Here, we showed that compared to non-PCOS patients and PCOS patients without hyperplasia, the endometria from PCOS patients with hyperplasia had a distinct protein expression pattern of glycolytic enzymes, including pyruvate kinase isozyme M2 isoform (PKM2) and pyruvate dehydrogenase (PDH), and mitochondrial transcription factor A (TFAM). In PCOS patients with endometrial hyperplasia, increased glandular epithelial cell secretion and infiltrated stromal cells in the glands were associated with decreased PDH immunoreactivity in the epithelial cells. Using endometrial tissues from PCOS patients with hyperplasia, we found that in response to metformin treatment in vitro, hexokinase 2 (HK2) expression was decreased, whereas phosphofructokinase (PFK), PKM2, and lactate dehydrogenase A (LDHA) expression was increased compared to controls. Although there was no change in PDH expression, metformin treatment increased the expression of TFAM and cleaved caspase-3. Moreover, our in vivo study showed that while endometrial ERβ expression was no different between non-PCOS and PCOS patients regardless of whether or not hyperplasia was present, ERα and AR protein expression was gradually increased in women with PCOS following the onset of endometrial hyperplasia. Our in vitro study showed that treatment with metformin inhibited ERα expression without affecting ERβ expression. Our findings suggest that decreased glycolysis and increased mitochondrial activity might contribute to the onset of ERα-dependent endometrial hyperplasia and that metformin might directly reverse impaired glycolysis and normalize mitochondrial function in PCOS patients with endometrial hyperplasia.

Elevation of isoprostanes in polycystic ovary syndrome and its relationship with cardiovascular risk factors

PURPOSE

To evaluate the plasma level of 8-isoprostanes in women with polycystic ovary syndrome. To also investigate whether there is a relationship between 8-isoprostanes and several cardiovascular risk factors.

METHODS

A total of 125 women with polycystic ovary syndrome and 169 healthy women were enrolled in this case-control study. 8-Isoprostanes and different parameters were measured in all subjects. Patients were evaluated for the presence of polycystic ovary syndrome according to the Rotterdam Consensus Conference criteria.

RESULTS

8-Isoprostanes levels were significantly higher in patients with polycystic ovary syndrome (138.4 ± 104.1 pg/mL) compared with control group (68.6 ± 34.3 pg/mL) (p < 0.001). The mean of triglycerides, lipid accumulation product, C-reactive protein, homocysteine, insulin, and homeostatic model assessment for insulin resistance were significantly higher in polycystic ovary syndrome patients with high 8-isoprostanes than those with normal 8-isoprostanes (p < 0.05). The Pearson correlation analyses showed that 8-isoprostanes levels in polycystic ovary syndrome group had a positive correlation with waist circumference, triglycerides, low-density lipoprotein cholesterol, apolipoprotein B, homocysteine, insulin, homeostatic model assessment for insulin resistance.

CONCLUSIONS

Patients with polycystic ovary syndrome have higher 8-isoprostanes levels and it is associated with several cardiovascular risk factors.

Glucose-regulated protein 78 in the aqueous humor in diabetic macular edema patients

In this study, we explored the presence and elevation of glucose-regulated protein 78 (GRP78) in aqueous humor of patients with diabetic macular edema (DME).After comparing DME patients with the controls, we analyzed GRP78 and vascular endothelial growth factor (VEGF) levels in DME patients. We examined factors associated with GRP78 levels in DME patients.GRP78 was detected in aqueous humor with elevated levels in DME patients. Stepwise backward regression analysis showed that GRP78 levels were associated with the VEGF levels and the duration of diabetes (P < .001 and P = .002, respectively). However, no statistical significance was observed between GRP78 levels and the decrease in CST following 3 monthly anti-VEGF treatments in univariate regression analysis (P = .695).We showed that GRP78 is elevated in DME patients. In addition, there is a correlation between GRP78 and VEGF levels in aqueous humor. However, GRP78 levels were not associated with the responsiveness of anti-VEGF in DME patients.

Polycystic ovarian syndrome (PCOS): Long-term metabolic consequences

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women during their reproductive ages, associated with a plethora of cardiometabolic consequences, with obesity, insulin resistance and hyperandrogenemia playing a major role in the degree of such manifestations. These consequences include increased risk of glucose intolerance and diabetes mellitus (both type 2 and gestational), atherogenic dyslipidemia, systemic inflammation, non-alcoholic fatty liver disease, hypertension and coagulation disorders. Whether this cluster of metabolic abnormalities is also translated in increased cardiovascular disease (CVD) morbidity and mortality in later life, remains to be established. Data so far based on markers of subclinical atherosclerosis as well as retrospective and prospective cohort studies indicate a possible increased CVD risk, mainly for coronary heart disease. Future studies are needed to further elucidate this issue.

Do inositol supplements enhance phosphatidylinositol supply and thus support endoplasmic reticulum function?

This review attempts to explain why consuming extra myoinositol (Ins), an essential component of membrane phospholipids, is often beneficial for patients with conditions characterised by insulin resistance, non-alcoholic fatty liver disease and endoplasmic reticulum (ER) stress. For decades we assumed that most human diets provide an adequate Ins supply, but newer evidence suggests that increasing Ins intake ameliorates several disorders, including polycystic ovary syndrome, gestational diabetes, metabolic syndrome, poor sperm development and retinopathy of prematurity. Proposed explanations often suggest functional enhancement of minor facets of Ins Biology such as insulin signalling through putative inositol-containing 'mediators', but offer no explanation for this selectivity. It is more likely that eating extra Ins corrects a deficiency of an abundant Ins-containing cell constituent, probably phosphatidylinositol (PtdIns). Much of a cell's PtdIns is in ER membranes, and an increase in ER membrane synthesis, enhancing the ER's functional capacity, is often an important part of cell responses to ER stress. This review: (a) reinterprets historical information on Ins deficiency as describing a set of events involving a failure of cells adequately to adapt to ER stress; (b) proposes that in the conditions that respond to dietary Ins there is an overstretching of Ins reserves that limits the stressed ER's ability to make the 'extra' PtdIns needed for ER membrane expansion; and (c) suggests that eating Ins supplements increases the Ins supply to Ins-deficient and ER-stressed cells, allowing them to make more PtdIns and to expand the ER membrane system and sustain ER functions.

Advanced glycation end products-induced insulin resistance involves repression of skeletal muscle GLUT4 expression

Little is known about advanced glycation end products (AGEs) participation in glucose homeostasis, a process in which skeletal muscle glucose transporter GLUT4 (Scl2a4 gene) plays a key role. This study investigated (1) the in vivo and in vitro effects of AGEs on Slc2a4/GLUT4 expression in skeletal muscle of healthy rats, and (2) the potential involvement of endoplasmic reticulum and inflammatory stress in the observed regulations. For in vivo analysis, rats were treated with advanced glycated rat albumin (AGE-albumin) for 12 weeks; for in vitro analysis, soleus muscles from normal rats were incubated with bovine AGE-albumin for 2.5 to 7.5 hours. In vivo, AGE-albumin induced whole-body insulin resistance; decreased (~30%) Slc2a4 mRNA and GLUT4 protein content; and increased (~30%) the nuclear content of nuclear factor NF-kappa-B p50 subunit (NFKB1), and cellular content of 78 kDa glucose-regulated protein (GRP78). In vitro, incubation with AGE-albumin decreased (~50%) the Slc2a4/GLUT4 content; and increased cellular content of GRP78/94, phosphorylated-IKK-alpha/beta, nuclear content of NFKB1 and RELA, and the nuclear protein binding into Slc2a4 promoter NFKB-binding site. The data reveal that AGEs impair glucose homeostasis in non-diabetic states of increased AGEs concentration; an effect that involves activation of endoplasmic reticulum- and inflammatory-stress and repression of Slc2a4/GLUT4 expression.

Oxidative stress and metabolic markers in pre- and postnatal polycystic ovary syndrome rat protocols

Background

Several studies have described an enhanced inflammatory status and oxidative stress balance disruption in women with polycystic ovary syndrome (PCOS). However, there is scarce information about redox markers in the blood of androgenized animal models. Here, we evaluated the serum/plasma oxidative stress marker and metabolic parameter characteristics of prenatal (PreN) and postnatal (PostN) androgenized rat models of PCOS.

Materials and methods

For PreN androgenization (n=8), 2.5 mg of testosterone propionate was subcutaneously administered to dams at embryonic days 16, 17, and 18, whereas PostN androgenization (n=7) was accomplished by subcutaneously injecting 1.25 mg of testosterone propionate to animals at PostN day 5. A unique control group (n=8) was constituted for comparison.

Results

Our results indicate that PostN group rats exhibited particular modifications in the oxidative stress marker, an increased plasma ferric-reducing ability of plasma, and an increased antioxidant capacity reflected by higher albumin serum levels. PostN animals also presented increased total cholesterol and triglyceride-glucose levels, suggesting severe metabolic disarrangement.

Conclusion

Study findings indicate that changes in oxidative stress could be promoted by testosterone propionate exposure after birth, which is likely associated with anovulation and/or lipid disarrangement.

Cardiovascular disease in a nationwide population of Danish women with polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is associated with obesity and low grade inflammation and the risk for cardiovascular disease (CVD) could be increased in PCOS.

Methods

National register-based study including women with PCOS and no previous diagnosis of CVD, hypertension, or dyslipidemia. PCOS Denmark (N = 18,112) included women with PCOS in the Danish National Patient Register. PCOS Odense University Hospital (OUH, N = 1165) was an embedded cohort including premenopausal women with PCOS and clinical and biochemical examination. Three age-matched controls were included per patient in PCOS Denmark (N = 52,769). The main study outcome was CVD events including hypertension and dyslipidemia defined according to nationwide in- and outpatient hospital contact diagnosis codes and/or inferred from filled medicine prescriptions.

Results

The age at inclusion was median (quartiles) 29 (23–35) years and follow up was 11.1 (6.9–16.0) years. The Hazard ratio (95% CI) for development of CVD in PCOS Denmark was 1.7 (1.7; 1.8) (P < 0.001) and the total event rate of CVD was 22.6 per 1000 patient years in PCOS Denmark vs. 13.2 per 1000 patient years in controls (P < 0.001). The median age at diagnosis of CVD was 35 (28–42) years in PCOS Denmark vs. 36 (30–43) years in controls (P < 0.001). Obesity, diabetes, and infertility, and previous use of oral contraceptives were associated with increased risk of development of CVD in PCOS Denmark (P < 0.001). Women in PCOS OUH resembled women in PCOS Denmark regarding risk of CVD. Age, BMI, blood pressure, lipid status, and glycemic status predicted development of CVD in PCOS OUH.

Conclusion

The event rate of CVD including hypertension and dyslipidemia was higher in PCOS compared to controls. The risk of developing CVD must be considered even in young women with PCOS.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0680-5) contains supplementary material, which is available to authorized users.

The Polycystic Ovary Syndrome and the Metabolic Syndrome: A Possible Chronobiotic-Cytoprotective Adjuvant Therapy

Polycystic ovary syndrome is a highly frequent reproductive-endocrine disorder affecting up to 8-10% of women worldwide at reproductive age. Although its etiology is not fully understood, evidence suggests that insulin resistance, with or without compensatory hyperinsulinemia, and hyperandrogenism are very common features of the polycystic ovary syndrome phenotype. Dysfunctional white adipose tissue has been identified as a major contributing factor for insulin resistance in polycystic ovary syndrome. Environmental (e.g., chronodisruption) and genetic/epigenetic factors may also play relevant roles in syndrome development. Overweight and/or obesity are very common in women with polycystic ovary syndrome, thus suggesting that some polycystic ovary syndrome and metabolic syndrome female phenotypes share common characteristics. Sleep disturbances have been reported to double in women with PCOS and obstructive sleep apnea is a common feature in polycystic ovary syndrome patients. Maturation of the luteinizing hormone-releasing hormone secretion pattern in girls in puberty is closely related to changes in the sleep-wake cycle and could have relevance in the pathogenesis of polycystic ovary syndrome. This review article focuses on two main issues in the polycystic ovary syndrome-metabolic syndrome phenotype development: (a) the impact of androgen excess on white adipose tissue function and (b) the possible efficacy of adjuvant melatonin therapy to improve the chronobiologic profile in polycystic ovary syndrome-metabolic syndrome individuals. Genetic variants in melatonin receptor have been linked to increased risk of developing polycystic ovary syndrome, to impairments in insulin secretion, and to increased fasting glucose levels. Melatonin therapy may protect against several metabolic syndrome comorbidities in polycystic ovary syndrome and could be applied from the initial phases of patients' treatment.

Effect of Two Different Doses of Vitamin D Supplementation on Metabolic Profiles of Insulin-Resistant Patients with Polycystic Ovary Syndrome

This study was carried out to evaluate the effects of vitamin D supplementation on the metabolic profiles of insulin-resistant subjects with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was conducted on 90 insulin-resistant women with PCOS. Participants were randomly assigned to three groups to intake either 4000 IU of vitamin D or 1000 IU of vitamin D or placebo (n = 30 each group) daily for 12 weeks. Vitamin D supplementation (4000 IU), compared with vitamin D (1000 IU) and placebo, led to significant reductions in total testosterone (-0.2 ± 0.2 vs. -0.1 ± 0.6 and +0.1 ± 0.2 ng/mL, respectively, p = 0.02), free androgen index (FAI) (-0.06 ± 0.12 vs. -0.02 ± 0.12 and +0.004 ± 0.04, respectively, p = 0.04), hirsutism (-1.1 ± 1.1 vs. -0.8 ± 1.2 and -0.1 ± 0.4, respectively, p = 0.001) and high-sensitivity C-reactive protein (hs-CRP) (-0.7 ± 1.4 vs. -0.5 ± 0.9 and +0.5 ± 2.4 mg/L, respectively, p = 0.01). In addition, we found significant elevations in mean change of sex hormone-binding globulin (SHBG) (+19.1 ± 23.0 vs. +4.5 ± 11.0 and +0.7 ± 10.4 nmol/L, respectively, p < 0.001) and total antioxidant capacity (TAC) (+130 ± 144 vs. +33 ± 126 and -36 ± 104 mmol/L, respectively, p < 0.001) in the high-dose vitamin D group compared with low-dose vitamin D and placebo groups. Overall, high-dose vitamin D administration for 12 weeks to insulin-resistant women with PCOS had beneficial effects on total testosterone, SHBG, FAI, serum hs-CRP and plasma TAC levels compared with low-dose vitamin D and placebo groups.

Macrophage functions in lean and obese adipose tissue

Interactions between macrophages and adipocytes influence both metabolism and inflammation. Obesity-induced changes to macrophages and adipocytes lead to chronic inflammation and insulin resistance. This paper reviews the various functions of macrophages in lean and obese adipose tissue and how obesity alters adipose tissue macrophage phenotypes. Metabolic disease and insulin resistance shift the balance between numerous pro- and anti-inflammatory regulators of macrophages and create a feed-forward loop of increasing inflammatory macrophage activation and worsening adipocyte dysfunction. This ultimately leads to adipose tissue fibrosis and diabetes. The molecular mechanisms underlying these processes have therapeutic implications for obesity, metabolic syndrome, and diabetes.