Facts on fats

Docosahexaenoic Acid Inhibits Tumor Promoter-Induced Urokinase-Type Plasminogen Activator Receptor by Suppressing PKCδ- and MAPKs-Mediated Pathways in ECV304 Human Endothelial Cells

The overexpression of urokinase-type plasminogen activator receptor (uPAR) is associated with inflammation and virtually all human cancers. Despite the fact that docosahexaenoic acid (DHA) has been reported to possess anti-inflammatory and anti-tumor properties, the negative regulation of uPAR by DHA is still undefined. Here, we investigated the effect of DHA on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced uPAR expression and the underlying molecular mechanisms in ECV304 human endothelial cells. DHA concentration-dependently inhibited TPA-induced uPAR. Specific inhibitors and mutagenesis studies showed that PKCδ, JNK1/2, Erk1/2, NF-κB, and AP-1 were critical for TPA-induced uPAR expression. Application of DHA suppressed TPA-induced translocation of PKCδ, activation of the JNK1/2 and Erk1/2 signaling pathways, and subsequent AP-1 and NF-κB transactivation. In conclusion, these observations suggest a novel role for DHA in reducing uPAR expression and cell invasion by inhibition of PKCδ, JNK1/2, and Erk1/2, and the reduction of AP-1 and NF-κB activation in ECV304 human endothelial cells.

High-Cholesterol Diet Disrupts the Levels of Hormones Derived from Anterior Pituitary Basophilic Cells

Emerging evidence shows that elevated cholesterol levels are detrimental to health. However, it is unclear whether there is an association between cholesterol and the pituitary. We investigated the effects of a high-cholesterol diet on pituitary hormones using in vivo animal studies and an epidemiological study. In the animal experiments, rats were fed a high-cholesterol or control diet for 28 weeks. In rats fed the high-cholesterol diet, serum levels of thyroid-stimulating hormone (TSH; also known as thyrotrophin), luteinising hormone (LH) and follicle-stimulating hormone (FSH) produced by the basophilic cells of the anterior pituitary were elevated in a time-dependent manner. Among these hormones, TSH was the first to undergo a significant change, whereas adrenocorticotrophic hormone (ACTH), another hormone produced by basophilic cells, was not changed significantly. As the duration of cholesterol feeding increased, cholesterol deposition increased gradually in the pituitary. Histologically, basophilic cells, and especially thyrotrophs and gonadotrophs, showed an obvious increase in cell area, as well as a potential increase in their proportion of total pituitary cells. Expression of the β-subunit of TSH, FSH and LH, which controls hormone specificity and activity, exhibited a corresponding increase. In the epidemiological study, we found a similar elevation of serum TSH, LH and FSH and a decrease in ACTH in patients with hypercholesterolaemia. Significant positive correlations existed between serum total cholesterol and TSH, FSH or LH, even after adjusting for confounding factors. Taken together, the results of the present study suggest that the high-cholesterol diet affected the levels of hormones derived from anterior pituitary basophilic cells. This phenomenon might contribute to the pituitary functional disturbances described in hypercholesterolaemia.

Retina and omega-3

Over the last decade, several epidemiological studies based on food frequency questionnaires suggest that omega-3 polyunsaturated fatty acids could have a protective role in reducing the onset and progression of retinal diseases. The retina has a high concentration of omega-3, particularly DHA, which optimizes fluidity of photoreceptor membranes, retinal integrity, and visual function. Furthermore, many studies demonstrated that DHA has a protective, for example antiapoptotic, role in the retina. From a nutritional point of view, it is known that western populations, particularly aged individuals, have a higher than optimal omega-6/omega-3 ratio and should enrich their diet with more fish consumption or have DHA supplementation. This paper underscores the potential beneficial effect of omega-3 fatty acids on retinal diseases.

A high-fat/high-cholesterol diet inhibits growth of fetal hippocampal transplants via increased inflammation

A diet containing high levels of saturated fat and cholesterol is detrimental to many aspects of health and is known to lead to obesity, metabolic syndrome, heart disease, diabetes, and cancer. However, the effects of a diet rich in saturated fat and cholesterol on the brain are not currently well understood. In order to determine direct effects of a high saturated fat and cholesterol diet upon fetal hippocampal tissue, we transplanted hippocampal grafts from embryonic day 18 rats to the anterior eye chamber of 16-month-old host animals that were fed either a normal rat chow diet or a 10% hydrogenated coconut oil + 2% cholesterol diet (HFHC diet) for 8 weeks. One eye per rat received topical application of an IL-1 receptor antagonist (IL-1Ra, Kineret®) and the other served as a saline control. Results revealed that the HFHC diet led to a marked reduction in hippocampal transplant growth, and detrimental effects of the diet were alleviated by the IL-1 receptor antagonist IL-1Ra. Graft morphology demonstrated that the HFHC diet reduced organotypical development of the hippocampal neuronal cell layers, which was also alleviated by IL-1Ra. Finally, grafts were evaluated with markers for glucose transporter expression, astrocytes, and activated microglia. Our results demonstrate significant effects of the HFHC diet on hippocampal morphology, including elevated microglial activation and reduced neuronal development. IL-1Ra largely blocked the detrimental effects of this diet, suggesting a potential use for this agent in neurological disorders involving neuroinflammation.

Simple and objective method for routine detection of the macular pigment xanthophyll

A new simple method for two-dimensional determination of optical density of macular pigment xanthophyll (ODx) in clinical routine is based on a single blue-reflection fundus image. Individual different vignetting is corrected by a shading function. For its construction, nodes are automatically found in structureless image regions. The influence of stray light in elderly crystalline lenses is compensated by a correction function that depends on age. The reproducibility of parameters in a one-wavelength reflection method determined for three subjects (47, 61, and 78 years old) was: maxODx = 6.3%, meanODx = 4.6%, volume = 6%, and area = 6% already before stray-light correction. ODx was comparable in pseudophakic and in an eye with a crystalline lens of the same 11 subjects after stray-light correction. Significant correlation in ODx was found between the one-wavelength reflection method and the two-wavelength autofluorescence method for pseudophakic and cataract eyes of 19 patients suffering from dry age-related macular degeneration (AMD) (R(2) = 0.855). In pseudophakic eyes, maxODx was significantly lower for dry AMD (n = 45) (ODx = 0.491±0.102 ODU) than in eyes with healthy fundus (n = 22) (ODx = 0.615±0.103 ODU) (p = 0.000033). Also in eyes with crystalline lens, maxODx was lower in AMD (n = 125) (ODx = 0.610±0.093 ODU) than in healthy subjects (n = 45) (ODx = 0.674±0.098 ODU) (p = 0.00019). No dependence on age was found in the pseudophakic eyes both of healthy subjects and AMD patients.

Comparative effects of fatty acids on proinflammatory gene cyclooxygenase 2 and inducible nitric oxide synthase expression in retinal pigment epithelial cells

Dietary fat modification is a promising approach to prevent age-related macular degeneration (AMD). However, which types of fatty acids carry a greater risk for AMD remains unclear. In this study, we compared the effects of 18-carbon fatty acids with different degrees of unsaturation on the expression of the proinflammatory genes cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in human retinal pigment epithelium (RPE). Additionally, we investigated whether lutein could modulate these genes induced by fatty acids in RPE. Treatment with oleic acid, linoleic acid (LA), or linolenic acid increased the expression of iNOS and COX-2 genes and the production of prostaglandin E(2 )and nitric oxide (NO) in RPE, whereas the saturated fatty acid stearic acid had little effect on these genes. Of the fatty acids studied, LA had the greatest effects on the induction of these genes. Furthermore, LA also induced NF-kappaB transcriptional activation the most. Lutein inhibited LA-induced expression of COX-2 and iNOS in a dose-dependent manner. These data suggested that specific unsaturated fatty acids, particularly LA, can stimulate RPE cells to express proinflammatory genes, which may contribute to the pathogenesis of AMD. Lutein inhibited the expression of these genes induced by LA through blockade of NF-kappaB activation.

Vascular endothelial growth factor in eye disease

Collectively, angiogenic ocular conditions represent the leading cause of irreversible vision loss in developed countries. In the US, for example, retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration are the principal causes of blindness in the infant, working age and elderly populations, respectively. Evidence suggests that vascular endothelial growth factor (VEGF), a 40kDa dimeric glycoprotein, promotes angiogenesis in each of these conditions, making it a highly significant therapeutic target. However, VEGF is pleiotropic, affecting a broad spectrum of endothelial, neuronal and glial behaviors, and confounding the validity of anti-VEGF strategies, particularly under chronic disease conditions. In fact, among other functions VEGF can influence cell proliferation, cell migration, proteolysis, cell survival and vessel permeability in a wide variety of biological contexts. This article will describe the roles played by VEGF in the pathogenesis of retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration. The potential disadvantages of inhibiting VEGF will be discussed, as will the rationales for targeting other VEGF-related modulators of angiogenesis.