16,16-Dimethyl PGE2 and fatty acids protect hepatocytes against CCl4-induced damage

Summary 16,16-Dimethyl PGE₂ (dmPGE₂) has previously been shown to protect the in vivo rat liver against CCl₄-induced damage. These studies were undertaken to determine if this protection could be demonstrated in vitro where factors of absorption, secretion, and blood flow are not present. Primary hepatocyte cultures were established by perfusing rat liver with collagenase. Hepatocytes were plated at a density of 2×10⁴ cells/cm, allowed 90 min to attach, then stabilized in L15 medium for 18 h. Hepatocytes were then challenged with CCl₄ with concomitant exposure to 10⁻⁹ to 10⁻⁵ M dmPGE₂, stearic acid, oleic acid, or ethanol vehicle (0.00001 to 0.1%). After 1 h, challenge was aspirated and cells were stained with 0.04% trypan blue to determine viability. Hepatocytes in the vehicle groups took up more trypan when exposed to CCl₄ than those treated with dmPGE₂, stearic acid, or oleic acid at concentrations of 10⁻⁹ to 10⁻⁷ M. At 0.1% ethanol vehicle protected as well as all other treatments. Protection against CCl₄ by dmPGE₂, stearic, and oleic acids as well as high concentrations of ethanol may occur by altering the metabolism of CCl₄.     

Omega-3 and omega-6 fatty acid concentrations in red blood cell membranes relate to schizotypal traits in healthy adults

Reduced omega-3 and omega-6 fatty acids in red blood cell (RBC) membranes are often found in patients with schizophrenia. Here we investigated whether membrane concentrations of these fatty acids might vary as a function of schizotypal traits in non-psychotic individuals. Twenty-five healthy adults completed the O-LIFE schizotypal trait inventory and fatty acid composition of their venous blood samples was analysed via gas-liquid chromatography. Correlations between schizotypy measures and RBC fatty acids were examined and comparisons made between groups high and low on fatty acid measures and schizotypy scores. The omega-6 fatty acids arachidonic, adrenic and docosapentaenoic acid were directly related to positive schizotypal trait measures, as were most omega-3 fatty acids, but none were related to a negative, withdrawn form of schizotypy. Our findings of high RBC concentrations of omega-3 and omega-6 fatty acids in healthy adults with positive schizotypal traits clearly contrast with the low levels often found in schizophrenia, but are quite consistent with evidence that omega-3 fatty acids (notably EPA) can be useful in the treatment of schizophrenic illness.     

Prostaglandin E2 produced by inducible COX-2 and mPGES-1 promoting cancer cell proliferation in vitro and in vivo

Aim

Many cancers originate and flourish in a prolonged inflammatory environment. Our aim is to understand the mechanisms of how the pathway of prostaglandin E₂ (PGE₂) biosynthesis and signaling can promote cancer growth in inflammatory environment at cellular and animal model levels.

Main methods

In this study, a chronic inflammation pathway was mimicked with a stable cell line that over-expressed a novel human enzyme consisting of cyclooxygenase isoform-2 (COX-2) linked to microsomal (PGE₂ synthase-1 (mPGES-1)) for the overproduction of pathogenic PGE₂. This PGE₂-producing cell line was co-cultured and co-implanted with three human cancer cell lines including prostate, lung, and colon cancers in vitro and in vivo, respectively.

Key findings

Increases in cell doubling rates for the three cancer cell types in the presence of the PGE₂-producing cell line were clearly observed. In addition, one of the four human PGE₂ subtype receptors, EP₁, was used as a model to identify PGE₂-signaling involved in promoting the cancer cell growth. This finding was further proven in vivo by co-implanting the PGE₂-producing cells line and the EP₁-positive cancer cells into the immune deficient mice, after that, it was observed that the PGE₂-producing cells promoted all three types of cancer formation in the mice.

Significance

This study clearly demonstrated that the human COX-2 linked to mPGES-1 is a pathway that, when mediated by the EP, is linked to promoting cancer growth in a chronic inflammatory environment. The identified pathway could be used as a novel target for developing and advancing anti-inflammation and anti-cancer interventions.     

Production of docosahexaenoic acid byThraustochytrium roseum

Summary When threeThraustochytrium stains were cultivated in liquid media containing 2.5% starch and 0.2% yeast extract, initial pH 6.0, with shaking under fluorescent light for five days at 25°C, similar biomass yields were observed (9.7–10.3 g L^–1). Contents of docosahexaenoic acid (DHA) in biomass varied: 0.15, 3.55 and 6.40% w/w forT. striatum ATCC 24473,T. aureum ATCC 34304 andT. roseum ATCC 28210, respectively. In further studies,T. roseum produced a maximum titer of 0.85 g of DHA per liter of culture broth. The DHA content of total lipids ranged from 46–49% w/w.     

Optimisation of culture conditions for production of eicosapentaenoic acid byMortierella elongate NRRL 5513

Summary WhenMortierella elongata NRRL 5513 was cultured in shake flasks at 25°C, mycelial growth reached a stationary phase at 48 h but maximum eicosapentaenoic acid (EPA) production was observed at 6 days. When incubated at 11°C, EPA production also continued to rise during the stationary phase of growth, reaching a maximum after 10 days. An initial culture pH of 6.1 was found to be optimum for EPA production. The effect of temperature on EPA production was dependent on medium constituents. In glucose and linseed oil supplemented media, optimum temperature for EPA production was 11 and 15°C respectively. A maximum EPA yield of 0.61 g/l was obtained in linseed oil (2%), yeast extract (0.5%) supplemented basal medium. Maximum EPA content as a percentage of lipids (15.12%) was observed when the latter medium was supplemented with 0.25% urea.     

H2O2 resistance is linked to the degree of fatty acid unsaturation in Streptomyces coelicolor A3(2)

In Streptomyces coelicolor A3(2), as the content of palmitoleic acid increased with decreasing growth temperature, H₂O₂ resistance decreased. Production of thiobarbituric acid-reactive substances upon H₂O₂ treatment was increased by supplementing unsaturated fatty acids. Therefore, the content of palmitoleic acid is a determining factor for the survival of Streptomyces coelicolor A3(2) subjected to H₂O₂ stress.     

Prostaglandin E2 increases the calcium concentration in rat brown adipocytes and their consumption of oxygen

Effects of prostaglandin E₂ (PGE₁) were examined on the oxygen consumption and intracellular calcium concentration of rat brown adipose tissue (BAT). PGE₂ 0.1 nM-1 μM increased oxygen consumption of the tissue blocks of BAT, with a maximum 2–13 min after PGE2 administration. PGE₂ was most effective at 1 and 10 nM, and the oxygen consumption was elevated for over 40 min. Pretreatment of BAT with indomethacin, a prostaglandin synthesis inhibitor, did not affect the increase in oxygen consumption induced by noradrenaline. PGE₂ at 1–10 nM gradually increased the intracellular calcium concentration of freshly dispersed single brown adipocytes by 3–4 times in 30 min. PGE₂ also increased the intracellular calcium concentration of brown adipocytes in calcium-free medium. These results raise the possibility that PGE₂ and noradrenaline affect heat genesis and metabolism of BAT independently.     

Human EP3(I) prostanoid receptor induces VEGF and VEGF receptor-1 mRNA expression

A critical event in tumor development is the formation of new blood vessels to provide oxygen, nutrients and growth factors to the rapidly growing cancer cells. This process of angiogenesis is complex, however, it is well established that vascular endothelial growth factor (VEGF)-mediated signaling is an important early event. Knockout mice studies have implicated the EP3 receptor in tumor development and angiogenesis; however, the signaling mechanism involved with this effect is unclear. We now show that stimulation of the EP3_I isoform of the human EP3 receptor with prostaglandin E₂ increases the mRNA expression of both VEGF and its cognate receptor VEGF receptor-1 (VEGFR-1). These inductions by the EP3_I receptor involve the sequential activation of phosphatidylinositol 3-kinase and the extracellular signal-regulated kinases. Up-regulation of VEGF and VEGFR-1 mRNA by the human EP3_I receptor has not been previously reported and further strengthen the role of this receptor in tumor-associated angiogenesis.     

Chemoprotective effect of omega-3 fatty acids on thioacetamide induced hepatic fibrosis in male rats

The current study was designed to investigate the possible protective effect of omega-3 fatty acids from fish oil on hepatic fibrosis induced by thioacetamide (TAA) in male rats. The experimental animals were divided into four groups. The first group was received saline solution and served as control. The second group was given 250 mg/kg body weight of TAA. The third group was treated with omega-3 fatty acids and TAA. The fourth group was given saline solution and supplemented with omega-3 fatty acids. Treatment of rats with TAA for three and six weeks resulted in a significant decrease in body weight gain, while the value of liver/body weight ratio was statistically increased. Furthermore, the levels of serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase and total bilirubin were significantly increased. After three weeks of exposure to only TAA, liver sections showed an abnormal morphology characterized by noticeable fibrosis with the extracellular matrix collagen contents and damage of liver cells’ structure. Liver sections from rats treated with only TAA for six weeks revealed an obvious increase in extracellular matrix collagen content and bridging fibrosis. Treating TAA-intoxicated rats with omega-3 fatty acids significantly attenuated the severe physiological and histopathological changes. Finally, the present investigation suggests that omega-3 fatty acids could act against hepatic fibrosis induced by TAA due to its antioxidant properties, thus supporting its use in hepatic fibrosis therapy.     

Omega-3 fatty acids in cancer, the protectors of good and the killers of evil?

Omega-3 fatty acids have been implicated in cancer prevention and treatment. Conventional chemotherapeutics are considered “double-edged swords”, as they kill the cancer cells but also strike the healthy cells causing severe morbidity and sometimes also mortality. Could omega-3 fatty acids in this setting work as a “sword and shield” instead, by being cytotoxic to cancer cells, but at the same time protect healthy cells from these deleterious effects? In addition, may our current diet with decreased omega-3/omega-6 ratio contribute to the increased cancer incidence, and could an omega-3 enriched diet be used as a preventive measure against cancer?Here, we seek answers to these questions by reviewing the effects of omega-3 fatty acids, particularly DHA, on various cancers with emphasis on a cancer of neural origin, neuroblastoma. Results from preventive and therapeutic animal as well as human studies together with mechanisms behind the observed toxicity are summarized.     

Environmental factors and membrane polyunsaturated fatty acids in schizophrenia

There is accumulating evidence of reductions in red blood cell membrane essential fatty acids in patients with schizophrenia. The mechanisms that may underlie these reductions have yet to be determined. It is possible that the observed membrane fatty acid deficits are associated with the development of schizophrenia. Alternatively, the membrane fatty acid deficits may be due to environmental factors, such as smoking and variations in diet, which may not be associated specifically with the pathophysiology of schizophrenia. Patients with schizophrenia smoke cigarettes at very high rates. Cigarette smoke contains many pro-oxidants that contribute directly to oxidative stress. Polyunsaturated fatty acids (PUFAs) are very susceptible to oxidative effects of free radicals. Thus, smoke-induced oxidative stress could plausibly account for reductions in membrane fatty acid in schizophrenia. Recent studies provide conflicting evidence for smoking effects on membrane fatty acid deficits. Likewise, the effects of diet on membrane PUFAs in schizophrenia are not entirely clear. Essential PUFAs need to be consumed in diet. Thus, differences in membrane PUFAs observed between patients and control subjects may be due to dietary variation. Few studies that have examined dietary effects differ in their interpretation of the effects of diet on membrane PUFAs. Thus, the jury is still out whether smoking or dietary effects are the primary causes of membrane PUFA deficits in patients with schizophrenia. Future studies will need to systematically examine the potential effects of smoking and diet, as well as other environmental factors such exercise, to definitively establish whether or not PUFA abnormalities are inherent to schizophrenia.     

Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells

Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D₃ (1,25(OH)₂D₃) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)₂D₃, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)₂D₃ mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)₂D₃ induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)₂D₃ induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)₂D₃ induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50–70%, respectively. In addition, the 1,25(OH)₂D₃ induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)₂D₃ stimulated VDR protein expression and 1,25(OH)₂D₃ mediated actions in human osteoblast cells.     

Identification and functional characterisation of genes encoding the omega-3 polyunsaturated fatty acid biosynthetic pathway from the coccolithophore Emiliania huxleyi

The Prymnesiophyceae coccolithophore Emiliania huxleyi is one of the most abundant alga in our oceans and therefore plays a central role in marine foodwebs. E. huxleyi is notable for the synthesis and accumulation of the omega-3 long chain polyunsaturated fatty acid docosahexaenoic acid (DHA; 22:6Δ^{4,7,10,13,16,19}, n − 3) which is accumulated in fish oils and known to have health-beneficial properties to humans, preventing cardiovascular disease and related pathologies. Here we describe the identification and functional characterisation of the five E. huxleyi genes which direct the synthesis of docosahexaenoic acid in this alga. Surprisingly, E. huxleyi does not use the conventional Δ6-pathway, instead using the alternative Δ8-desaturation route which has previously only been observed in a few unrelated microorganisms. Given that E. huxleyi accumulates significant levels of the Δ6-desaturated fatty acid stearidonic acid (18:4Δ^6,9,12,15, n − 3), we infer that the biosynthesis of DHA is likely to be metabolically compartmentalised from the synthesis of stearidonic acid.     

Fatty acid profiles among the Inuit of Nunavik: Current status and temporal change

The Inuit undergo substantial changes in their lifestyle, but few data exist on how these changes occur in biomarkers, such as polyunsaturated fatty acids (PUFAs). Here, we report data from a cross-sectional survey conducted in 2004 among 861 representative Nunavik Inuit adults, in whom FAs were measured in red blood cells (RBCs). FAs were also measured in plasma phospholipids (n=452) to assess temporal trend by comparing plasma PUFAs measured in 1992. Food intakes were estimated using a validated food frequency questionnaire. In 2004, marine food intake was 84±4 g/d (±SEM). Adjusted-mean of RBC omega-3 was significantly higher, and omega-6 lower, in older age groups (P_trend<0.001). In 2004, plasma omega-3 was 25% lower, while omega-6 was 9% higher, compared to 1992. Our study revealed that Nunavik Inuit adults still have high RBC omega-3, but show signs of nutritional transition – as indicated by lower omega-3 and higher trans-fats in RBCs of young compared to older.     

Fatty acid oxidation and myocardial phospholipase A2 activity

Summary Cis-unsaturated fatty acids, but not saturated fatty acids, inhibited phospholipase A₂ activity (PLA₂) in vitro, and may function as endogenous suppressors of lipolysis. To probe the possible role of lipid peroxidation in the regulation of myocardial lipid catabolism, a neutral-active and Ca²⁺-dependent PLA₂ was extracted from rat heart and was partially purified by sulfopropyl cation exchange chromatography. Myocardial PLA, activity was inhibited in a dose-dependent manner by oleic, linoleic, linolenic, and arachidonic acids; the IC₅₀ for arachidonic acid was approx 65 M. Palmitic acid was not inhibitory. When arachidonic acid was incubated at 37°C, exposed to air, there was a time- and pH-dependent peroxidation of the arachidonic acid as monitored by turbidity, thiobarbituric acid reactivity, and thin layer chromatography. Peroxidation was increased as the pH was lowered from 7.5 to 4.5, and was accompanied by a decrease in PLA₂ inhibitory potency. Thus, arachidonate incubated for 24 hours at pH's 4.5, 6.0 and 7.5 lost 84%, 32%, and 20% respectively, of its inhibitory potency. Therefore, in vitro acidosis promotes the oxidation of cis-unsaturated fatty acids and relieves their inhibitory or suppressive activity toward PLA₂s. Increased lipid peroxidation of unesterified unsaturated fatty acids during acidosis may therefore promote lipolysis observed during myocardial ischemia and reperfusion injury.     

Omega-3 fatty acids are related to abnormal emotion processing in adolescent boys with attention deficit hyperactivity disorder

BackgroundIn addition to the core symptoms, attention deficit hyperactivity disorder (ADHD) is associated with poor emotion regulation. There is some evidence that children and young adults with ADHD have lower omega-3 levels and that supplementation with omega-3 can improve both ADHD and affective symptoms. We therefore investigated differences between ADHD and non-ADHD children in omega-3/6 fatty acid plasma levels and the relationship between those indices and emotion-elicited event-related potentials (ERPs).MethodsChildren/adolescents with (n=31) and without ADHD (n=32) were compared in their plasma omega-3/6 indices and corresponding ERPs during an emotion processing task.ResultsChildren with ADHD had lower mean omega-3/6 and ERP abnormalities in emotion processing, independent of emotional valence relative to control children. ERP abnormalities were significantly associated with lower omega-3 levels in the ADHD group.ConclusionsThe findings reveal for the first time that lower omega-3 fatty acids are associated with impaired emotion processing in ADHD children.