Targeting Oxidative Stress Involved in Endometriosis and Its Pain.

Endometriosis is a common gynecological disorder seen in women and is characterized by chronic pelvic pain and infertility. This disorder is becoming more prevalent with increased morbidity. The etiology of endometriosis remains to be fully elucidated, which will lead to improved therapeutic options. In this review, we will evaluate the biochemical mechanisms leading to oxidative stress and their implication in the pathophysiology of endometriosis, as well as potential treatments that target these processes. A comprehensive exploration of previous research revealed that endometriosis is associated with elevated reactive oxygen species and oxidation products, decreased antioxidants and detoxification enzymes, and dysregulated iron metabolism. High levels of oxidative stress contributed to inflammation, extracellular matrix degradation, angiogenesis, and cell proliferation, which may explain its role in endometriosis. Endometriosis-associated pain was attributed to neurogenic inflammation and a feed-forward mechanism involving macrophages, pro-inflammatory cytokines, and pain-inducing prostaglandins. N-acetylcysteine, curcumin, melatonin, and combined vitamin C and E supplementation displayed promising results for the treatment of endometriosis, but further research is needed for their use in this population.

Omega 3 rich diet modulates energy metabolism via GPR120-Nrf2 crosstalk in a novel antioxidant mouse model.

With obesity rates reaching epidemic proportions, more studies concentrated on reducing the risk and treating this epidemic are vital. Redox stress is an important metabolic regulator involved in the pathophysiology of cardiovascular disease, Type 2 diabetes, and obesity. Oxygen and nitrogen-derived free radicals alter glucose and lipid homeostasis in key metabolic tissues, leading to increases in risk of developing metabolic syndrome. Oxidants derived from dietary fat differ in their metabolic regulation, with numerous studies showing benefits from a high omega 3 rich diet compared to the frequently consumed "western diet" rich in saturated fat. Omega 3 (OM3) fatty acids improve lipid profile, lower inflammation, and ameliorate insulin resistance, possibly through maintaining redox homeostasis. This study is based on the hypothesis that altering endogenous antioxidant production and/or increasing OM3 rich diet consumption will improve energy metabolism and maintain insulin sensitivity. We tested the comparative metabolic effects of a diet rich in saturated fat (HFD) and an omega 3-enriched diet (OM3) in the newly developed 'stress-less' mice model that overexpresses the endogenous antioxidant catalase. Eight weeks of dietary intervention showed that mice overexpressing endogenous catalase compared to their wild-type controls when fed an OM3 enriched diet, in contrast to HFD, activated GPR120-Nrf2 cross-talk to maintain balanced energy metabolism, normal circadian rhythm, and insulin sensitivity. These findings suggest that redox regulation of GPR120/FFAR4 might be an important target in reducing risk of metabolic syndrome and associated diseases.

Myeloperoxidase as a Potential Target in Women With Endometriosis Undergoing IVF.

As infertility is intimately associated with endometriosis, the levels of myeloperoxidase (MPO), a leukocyte enzyme and an oxidative stress marker, were determined in a case-control prospective study of 68 women with and without endometriosis undergoing in vitro fertilization in the outpatient fertility center within a tertiary care academic medical center. Measured values included plasma and follicular fluid (FF) concentrations of MPO, plasma estradiol, as well as oocyte quality, fertilization, implantation, and pregnancy rates in these women. In FF (mean ± standard error of mean [SEM]), the MPO concentrations (ng/mL) for controls were 4.3 ± 0.37, mild endometriosis (stages I-II) 3.9 ± 0.17, and moderate/severe endometriosis (stages III-IV) 16.6 ± 12.5 ( P < 0.0143). In FF, among patients supplemented with vitamins E and C, the MPO levels decreased significantly only in moderate/severe endometriosis from 25.3 ± 22.0 ng/mL to 4.9 ± 1.61 ng/mL, respectively. Plasma levels of MPO between groups did not change. Outcome data revealed a trend toward decreased percentage of mature oocytes, implantation rate, and clinical pregnancy rate with severity of endometriosis and MPO levels. Myeloperoxidase may be a potential oxidative stress target for endometriosis-associated infertility.

Oxidation-sensitive nociception involved in endometriosis-associated pain.

Endometriosis is a disease characterized by the growth of endometrial tissue outside the uterus and is associated with chronic pelvic pain. Peritoneal fluid (PF) of women with endometriosis is a dynamic milieu and is rich in inflammatory markers, pain-inducing prostaglandins prostaglandin E2 and prostaglandin F2α, and lipid peroxides; and the endometriotic tissue is innervated with nociceptors. Our clinical study showed that the abundance of oxidatively modified lipoproteins in the PF of women with endometriosis and the ability of antioxidant supplementation to alleviate endometriosis-associated pain. We hypothesized that oxidatively modified lipoproteins present in the PF are the major source of nociceptive molecules that play a key role in endometriosis-associated pain. In this study, PF obtained from women with endometriosis or control women were used for (1) the detection of lipoprotein-derived oxidation-sensitive pain molecules, (2) the ability of such molecules to induce nociception, and (3) the ability of antioxidants to suppress this nociception. LC-MS/MS showed the generation of eicosanoids by oxidized-lipoproteins to be similar to that seen in the PF. Oxidatively modified lipoproteins induced hypothermia (intracerebroventricular) in CD-1 mice and nociception in the Hargreaves paw withdrawal latency assay in Sprague-Dawley rats. Antioxidants, vitamin E and N-acetylcysteine, and the nonsteroidal anti-inflammatory drug indomethacin suppressed the pain-inducing ability of oxidatively modified lipoproteins. Treatment of human endometrial cells with oxidatively modified lipoproteins or PF from women with endometriosis showed upregulation of similar genes belonging to opioid and inflammatory pathways. Our finding that oxidatively modified lipoproteins can induce nociception has a broader impact not only on the treatment of endometriosis-associated pain but also on other diseases associated with chronic pain.

Antioxidant supplementation reduces endometriosis-related pelvic pain in humans.

We previously suggested that women with endometriosis have increased oxidative stress in the peritoneal cavity. To assess whether antioxidant supplementation would ameliorate endometriosis-associated symptoms, we performed a randomized, placebo-controlled trial of antioxidant vitamins (vitamins E and C) in women with pelvic pain and endometriosis. Fifty-nine women, ages 19 to 41 years, with pelvic pain and history of endometriosis or infertility were recruited for this study. Patients were randomly assigned to 2 groups: vitamin E (1200 IU) and vitamin C (1000 mg) combination or placebo daily for 8 weeks before surgery. Pain scales were administered at baseline and biweekly. Inflammatory markers were measured in the peritoneal fluid obtained from both groups of patients at the end of therapy. Our results indicated that after treatment with antioxidants, chronic pain ("everyday pain") improved in 43% of patients in the antioxidant treatment group (P = 0.0055) compared with the placebo group. In the same group, dysmenorrhea ("pain associated with menstruation") and dyspareunia ("pain with sex") decreased in 37% and 24% patients, respectively. In the placebo group, dysmenorrhea-associated pain decreased in 4 patients and no change was seen in chronic pain or dyspareunia. There was a significant decrease in peritoneal fluid inflammatory markers, regulated upon activation, normal T-cell expressed and secreted (P ≤ 0.002), interleukin-6 (P ≤ 0.056), and monocyte chemotactic protein-1 (P ≤ 0.016) after antioxidant therapy compared with patients not taking antioxidants. The results of this clinical trial show that administration of antioxidants reduces chronic pelvic pain in women with endometriosis and inflammatory markers in the peritoneal fluid.

The aporphine alkaloid boldine induces adiponectin expression and regulation in 3T3-L1 cells.

Adiponectin is an adipokine secreted by differentiated adipocytes. Clinical studies suggest a negative correlation between oxidative stress and adiponectin levels in patients with metabolic syndrome or cardiovascular disease. Natural compounds that can prevent oxidative stress mediated inhibition of adiponectin may be potentially therapeutic. Boldine, an aporphine alkaloid abundant in the medicinal plant Peumus boldus, is a powerful antioxidant. The current study demonstrates the effects of boldine on the expression of adiponectin and its regulators, CCAAT/enhancer binding protein-alpha (C/EBPalpha) and peroxisome proliferator-activated receptor (PPAR)-gamma, in 3T3-L1 cells. Differentiated 3T3-L1 adipocytes were exposed to either hydrogen peroxide (H(2)O(2)) (100 microM) or tumor necrosis factor-alpha (TNFalpha) (1 ng/mL) for 24 hours in the presence or absence of increasing concentrations of boldine (5-100 microM). Quantitative polymerase chain reaction showed that both the oxidants decreased the mRNA levels of adiponectin, PPARgamma, and C/EBPalpha to half of the control levels. Boldine, at all concentrations, counteracted the inhibitory effect of H(2)O(2) or TNFalpha and increased the expression of adiponectin and its regulators. The effect of boldine on adiponectin expression was biphasic, with the lower concentrations (5-25 microM) having a larger inductive effect compared to higher concentrations (50-100 microM). Boldine treatment alone in the absence of H(2)O(2) or TNFalpha was also able to induce adiponectin at the inductive phase of adipogenesis. Peroxisome proliferator response element-luciferase promoter transactivity analysis showed that boldine interacts with the PPAR response element and could potentially modulate PPAR responsive genes. Our results indicate that boldine is able to modulate the expression of adiponectin and its regulators in 3T3-L1 cells and has the potential to be beneficial in obesity-related cardiovascular disease.

Dietary oxidized linoleic acid lowers triglycerides via APOA5/APOClll dependent mechanisms.

Previously we have shown that intestinal cells efficiently take up oxidized fatty acids (OxFAs) and that atherosclerosis is increased when animals are fed a high cholesterol diet in the presence of oxidized linoleic acid. Interestingly, we found that in the absence of dietary cholesterol, the oxidized fatty acid fed low-density lipoprotein (LDL) receptor negative mice appeared to have lower plasma triglyceride (TG) levels as compared to animals fed oleic acid. In the present study, we fed C57BL6 mice a normal mice diet supplemented with oleic acid or oxidized linoleic acid (at 18 mg/animal/day) for 2 weeks. After the mice were sacrificed, we measured the plasma lipids and collected livers for the isolation of RNA. The results showed that while there were no significant changes in the levels of total cholesterol and high-density lipoprotein cholesterol (HDLc), there was a significant decrease (41.14%) in the levels of plasma TG in the mice that were fed oxidized fatty acids. The decreases in plasma TG levels were accompanied by significant increases (P<0.001) in the expressions of APOA5 and acetyl-CoA oxidase genes as well as a significant (P<0.04) decrease in APOClll gene expression. Oxidized lipids have been suggested to be ligands for peroxisome proliferator-activated receptor (PPAR*). However, there were no increases in the mRNA or protein levels of PPAR* in the oxidized linoleic acid fed animals. These results suggest that oxidized fatty acids may act through an APOA5/APOClll mechanism that contributes to lowering of TG levels other than PPAR* induction.

Inhibition of atherosclerosis in low-density lipoprotein receptor-negative mice by sesame oil.

Diet has profound effects on the development of atherosclerosis. Fatty acid composition, antioxidants, and other components such as lignans have major effects on the atherosclerotic process. Sesame oil has both mono- and polyunsaturated fatty acid constituents in equal proportions. In addition, it also has high levels of numerous antioxidants and inducers of peroxisome proliferator-activated receptor. The objective of this study was to determine the anti-atherosclerotic effects of sesame oil. In this study, male low-density lipoprotein (LDL) receptor (LDLR) -/- mice were fed atherogenic diet or atherogenic diet reformulated with the same level of sesame oil (sesame oil diet). Plasma lipids and atherosclerotic lesions were quantified after 3 months of feeding. Sesame oil-containing diet significantly reduced the atherosclerotic lesion formation and plasma cholesterol, triglyceride, and LDL cholesterol levels in LDLR -/- mice. These findings suggest that sesame oil could inhibit atherosclerosis lesion formation effectively, perhaps because of the synergistic actions of fatty acid and nonsaponifiable components.

Profiling of human cytokines in healthy individuals with vitamin E supplementation by antibody array.

Previously, we demonstrated that vitamin E supplementation decreases autoantibodies to oxidized lipid-protein complexes (J. Med. Food 1 (2000) 247). Utilizing an in vitro modeling system, we also demonstrated that vitamin E blocks the tumor promotion process in liver epithelial cells (Carcinogenesis 20 (1999) 485 and Mol. Carcinog. 30 (2001) 209). To investigate the molecular mechanisms of vitamin E function, we developed a human cytokine array system that is capable of detecting the expression of 35 cytokines simultaneously. Using this new technology, we analyzed the potential vitamin E-regulated cytokines in vitamin E supplementation individuals. The cytokine arrays showed that expression of several cytokines, particularly monocyte chemoattractant protein-1 (MCP-1), was profoundly reduced in vitamin E supplementation individuals. Moreover, addition of vitamin E to several cultured cells significantly down-regulated the expression of MCP-1. Our results suggested that MCP-1 may be one of the most important targets of antioxidant vitamin E. To the best of our knowledge, this is the first report describing the down-regulation of MCP-1 in vitamin E supplementation in vivo.