Potential Neuroprotective Effects of Dietary Omega-3 Fatty Acids on Stress in Alzheimer's Disease

BACKGROUND

A large number of individual potentially modifiable factors are associated with risk for Alzheimer's disease (AD). However, less is known about the interactions between the individual factors.

METHODS

In order to begin to examine the relationship between a pair of factors, we performed a pilot study, surveying patients with AD and controls for stress exposure and dietary omega-3 fatty acid intake to explore their relationship for risk of AD.

RESULTS

For individuals with the greatest stress exposure, omega-3 fatty acid intake was significantly greater in healthy controls than in AD patients. There was no difference among those with low stress exposure.

CONCLUSIONS

These initial results begin to suggest that omega-3 fatty acids may mitigate AD risk in the setting of greater stress exposure. This will need to be examined with larger populations and other pairs of risk factors to better understand these important relationships. Examining how individual risk factors interact will ultimately be important for learning how to optimally decrease the risk of AD.

Docosahexaenoic Acid (DHA) Supplementation Alters Phospholipid Species and Lipid Peroxidation Products in Adult Mouse Brain, Heart, and Plasma

The abundance of docosahexaenoic acid (DHA) in phospholipids in the brain and retina has generated interest to search for its role in mediating neurological functions. Besides the source of many oxylipins with pro-resolving properties, DHA also undergoes peroxidation, producing 4-hydroxyhexenal (4-HHE), although its function remains elusive. Despite wide dietary consumption, whether supplementation of DHA may alter the peroxidation products and their relationship to phospholipid species in brain and other body organs have not been explored sufficiently. In this study, adult mice were administered a control or DHA-enriched diet for 3 weeks, and phospholipid species and peroxidation products were examined in brain, heart, and plasma. Results demonstrated that this dietary regimen increased (n-3) and decreased (n-6) species to different extent in all major phospholipid classes (PC, dPE, PE-pl, PI and PS) examined. Besides changes in phospholipid species, DHA-enriched diet also showed substantial increases in 4-HHE in brain, heart, and plasma. Among different brain regions, the hippocampus responded to the DHA-enriched diet showing significant increase in 4-HHE. Considering the pro- and anti-inflammatory pathways mediated by the (n-6) and (n-3) polyunsaturated fatty acids, unveiling the ability for DHA-enriched diet to alter phospholipid species and lipid peroxidation products in the brain and in different body organs may be an important step forward towards understanding the mechanism(s) for this (n-3) fatty acid on health and diseases.

Maternal DHA supplementation influences sex-specific disruption of placental gene expression following early prenatal stress

Early life adversity is widely recognized as a key risk factor for early developmental perturbations and contributes to the presentation of neuropsychiatric disorders in adulthood. Neurodevelopmental disorders exhibit a strong sex bias in susceptibility, presentation, onset, and severity, although the underlying mechanisms conferring vulnerability are not well understood. Environmental perturbations during pregnancy, such as malnutrition or stress, have been associated with sex-specific reprogramming that contribute to increased disease risk in adulthood, whereby stress and nutritional insufficiency may be additive and further exacerbate poor offspring outcomes. To determine whether maternal supplementation of docosahexanoic acid (DHA) exerts an effect on offspring outcome following exposure to early prenatal stress (EPS), dams were fed a purified 10:1 omega-6/omega-3 diet supplemented with either 1.0% preformed DHA/kg feed weight (DHA-enriched) or no additional DHA (denoted as the control diet, CTL). Dams were administered chronic variable stress during the first week of pregnancy (embryonic day, E0.5–7.5), and developmental milestones were assessed at E 12.5. Exposure to early prenatal stress (EPS) decreased placenta and embryo weight in males, but not females, exposed to the CTL diet. DHA enrichment reversed the sex-specific decrease in placenta and embryo weight following EPS. Early prenatal exposure upregulated expression of genes associated with oxygen and nutrient transport, including hypoxia inducible factor 3α (HIF3α), peroxisome proliferator-activated receptor alpha (PPARα), and insulin-like growth binding factor 1 (IGFBP1), in the placenta of CTL diet males exposed to EPS. DHA enrichment in EPS-exposed animals abrogated the male-specific upregulation of PPARα, HIF3α, and IGFBP1. Taken together, these studies suggest that maternal dietary DHA enrichment may buffer against maternal stress programming of sex-specific outcomes during early development.

Quantitative Proteomics Reveals Docosahexaenoic Acid-Mediated Neuroprotective Effects in Lipopolysaccharide-Stimulated Microglial Cells

The high levels of docosahexaenoic acid (DHA) in cell membranes within the brain have led to a number of studies exploring its function. These studies have shown that DHA can reduce inflammatory responses in microglial cells. However, the method of action is poorly understood. Here, we report the effects of DHA on microglial cells stimulated with lipopolysaccharides (LPSs). Data were acquired using the parallel accumulation serial fragmentation method in a hybrid trapped ion mobility-quadrupole time-of-flight mass spectrometer. Over 2800 proteins are identified using label-free quantitative proteomics. Cells exposed to LPSs and/or DHA resulted in changes in cell morphology and expression of 49 proteins with differential abundance (greater than 1.5-fold change). The data provide details about pathways that are influenced in this system including the nuclear factor κ-light-chain-enhancer of the activated B cells (NF-κB) pathway. Western blots and enzyme-linked immunosorbent assay studies are used to help confirm the proteomic results. The MS data are available at ProteomeXchange.

Effects of ERβ and ERα on OVX-induced changes in adiposity and insulin resistance

Loss of ovarian hormones leads to increased adiposity and insulin resistance (IR), increasing the risk for cardiovascular and metabolic diseases. The purpose of this study was to investigate whether the molecular mechanism behind the adverse systemic and adipose tissue-specific metabolic effects of ovariectomy requires loss of signaling through estrogen receptor alpha (ERα) or estrogen receptor β (ERβ). We examined ovariectomized (OVX) and ovary-intactwild-type (WT), ERα-null (αKO), and ERβ-null (βKO) female mice (age ~49 weeks; n = 7-12/group). All mice were fed a phytoestrogen-free diet (<15 mg/kg) and either remained ovary-intact (INT) or were OVX and followed for 12 weeks. Body composition, energy expenditure, glucose tolerance, and adipose tissue gene and protein expression were analyzed. INT αKO were ~25% fatter with reduced energy expenditure compared to age-matched INT WT controls and βKO mice (all P < 0.001). Following OVX, αKO mice did not increase adiposity or experience a further increase in IR, unlike WT and βKO, suggesting that loss of signaling through ERα mediates OVX-induced metabolic dysfunction. In fact, OVX in αKO mice (i.e., signaling through ERβ in the absence of ERα) resulted in reduced adiposity, adipocyte size, and IR (P < 0.05 for all). βKO mice responded adversely to OVX in terms of increased adiposity and development of IR. Together, these findings challenge the paradigm that ERα mediates metabolic protection over ERβ in all settings. These findings lead us to suggest that, following ovarian hormone loss, ERβ may mediate protective metabolic benefits.

Yin-Yang Mechanisms Regulating Lipid Peroxidation of Docosahexaenoic Acid and Arachidonic Acid in the Central Nervous System

Phospholipids in the central nervous system (CNS) are rich in polyunsaturated fatty acids (PUFAs), particularly arachidonic acid (ARA) and docosahexaenoic acid (DHA). Besides providing physical properties to cell membranes, these PUFAs are metabolically active and undergo turnover through the “deacylation-reacylation (Land's) cycle”. Recent studies suggest a Yin-Yang mechanism for metabolism of ARA and DHA, largely due to different phospholipases A₂ (PLA₂s) mediating their release. ARA and DHA are substrates of cyclooxygenases and lipoxygenases resulting in an array of lipid mediators, which are pro-inflammatory and pro-resolving. The PUFAs are susceptible to peroxidation by oxygen free radicals, resulting in the production of 4-hydroxynonenal (4-HNE) from ARA and 4-hydroxyhexenal (4-HHE) from DHA. These alkenal electrophiles are reactive and capable of forming adducts with proteins, phospholipids and nucleic acids. The perceived cytotoxic and hormetic effects of these hydroxyl-alkenals have impacted cell signaling pathways, glucose metabolism and mitochondrial functions in chronic and inflammatory diseases. Due to the high levels of DHA and ARA in brain phospholipids, this review is aimed at providing information on the Yin-Yang mechanisms for regulating these PUFAs and their lipid peroxidation products in the CNS, and implications of their roles in neurological disorders.

Beta 3 Adrenergic Receptor Activation Rescues Metabolic Dysfunction in Female Estrogen Receptor Alpha-Null Mice

Metabolic disease risk escalates following menopause. The mechanism is not fully known, but likely involves reduced signaling through estrogen receptor alpha (ERα), which is highly expressed in brown and white adipose tissue (BAT and WAT).

Objective: Test the hypothesis that uncoupling protein (UCP1) activation mitigates metabolic dysfunction caused by loss of signaling through ERα.

Methods: At 8 weeks of age, female ERα knock out (KO) and wild-type mice were housed at 28°C and fed a Western-style high-fat, high sucrose diet (HFD) or a normal low-fat chow diet (NC) for 10 weeks. During the final 2 weeks, they received daily injections of CL 316,256 (CL), a selective β3 adrenergic agonist, or vehicle control (CTRL), creating eight groups: WT-CTRL, WT-CL, KO-CTRL, and KO-CL on HFD or NC; n = 4–10/group.

Results: ERαKO demonstrated exacerbated HFD-induced adiposity gain (P < 0.001) and insulin resistance (P = 0.006). CL treatment improved insulin sensitivity (P < 0.05) and normalized ERαKO-induced adiposity increase (P < 0.05). In both genotypes, CL increased resting energy expenditure (P < 0.05) and induced WAT beiging indicated by increased UCP1 protein in both perigonadal (PGAT) and subcutaneous (SQAT) depots. These effects were attenuated under HFD conditions (P < 0.05). In KO, CL reduced HFD energy consumption compared to CTRL (P < 0.05). Remarkably, CL increased WAT ERβ protein levels of both WT and KO (P < 0.001), revealing CL-mediated changes in estrogen signaling may have protective metabolic effects.

Conclusion: CL completely restored metabolic dysfunction in ERαKO mice. Thus, UCP1 may be a therapeutic target for treating metabolic dysfunction following loss of estrogen receptor signaling.

Docosahexaenoic acid (DHA): An essential nutrient and a nutraceutical for brain health and diseases

Docosahexaenoic acid (DHA), a polyunsaturated fatty acid (PUFA) enriched in phospholipids in the brain and retina, is known to play multi-functional roles in brain health and diseases. While arachidonic acid (AA) is released from membrane phospholipids by cytosolic phospholipase A₂ (cPLA₂), DHA is linked to action of the Ca²⁺-independent iPLA2. DHA undergoes enzymatic conversion by 15-lipoxygenase (Alox 15) to form oxylipins including resolvins and neuroprotectins, which are powerful lipid mediators. DHA can also undergo non-enzymatic conversion by reacting with oxygen free radicals (ROS), which cause the production of 4-hydoxyhexenal (4-HHE), an aldehyde derivative which can form adducts with DNA, proteins and lipids. In studies with both animal models and humans, there is evidence that inadequate intake of maternal n-3 PUFA may lead to aberrant development and function of the central nervous system (CNS). What is less certain is whether consumption of n-3 PUFA is important in maintaining brain health throughout one's life span. Evidence mostly from non-human studies suggests that DHA intake above normal nutritional requirements might modify the risk/course of a number of diseases of the brain. This concept has fueled much of the present interest in DHA research, in particular, in attempts to delineate mechanisms whereby DHA may serve as a nutraceutical and confer neuroprotective effects. Current studies have revealed ability for the oxylipins to regulation of cell redox homeostasis through the Nuclear factor (erythroid-derived 2)-like 2/Antioxidant response element (Nrf2/ARE) anti-oxidant pathway, and impact signaling pathways associated with neurotransmitters, and modulation of neuronal functions involving brain-derived neurotropic factor (BDNF). This review is aimed at describing recent studies elaborating these mechanisms with special regard to aging and Alzheimer's disease, autism spectrum disorder, schizophrenia, traumatic brain injury, and stroke.

Unveiling anti-oxidative and anti-inflammatory effects of docosahexaenoic acid and its lipid peroxidation product on lipopolysaccharide-stimulated BV-2 microglial cells

BACKGROUND

Phospholipids in the central nervous system are enriched in n-3 and n-6 polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA) and arachidonic acid (ARA). These PUFA can undergo enzymatic reactions to produce lipid mediators, as well as reaction with oxygen free radicals to produce 4-hydroxyhexenal (4-HHE) from DHA and 4-hydroxynonenal (4-HNE) from ARA. Recent studies demonstrated pleiotropic properties of these peroxidation products through interaction with oxidative and anti-oxidant response pathways. In this study, BV-2 microglial cells were used to investigate ability for DHA, 4-HHE, and 4-HNE to stimulate the anti-oxidant stress responses involving the nuclear factor erythroid-2-related factor 2 (Nrf2) pathway and synthesis of heme oxygenase (HO-1), as well as to mitigate lipopolysaccharide (LPS)-induced nitric oxide (NO), reactive oxygen species (ROS), and cytosolic phospholipase A₂ (cPLA₂). In addition, LC-MS/MS analysis was carried out to examine effects of exogenous DHA and LPS stimulation on endogenous 4-HHE and 4-HNE levels in BV-2 microglial cells.

METHODS

Effects of DHA, 4-HHE, and 4-HNE on LPS-induced NO production was determined using the Griess reagent. LPS-induced ROS production was measured using CM-H₂DCFDA. Western blots were used to analyze expression of p-cPLA₂, Nrf2, and HO-1. Cell viability and cytotoxicity were measured using the WST-1 assay, and cell protein concentrations were measured using the BCA protein assay kit. An ultra-high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to determine levels of free 4-HHE and 4-HNE in cells.

RESULTS

DHA (12.5-100 μM), 4-HHE (1.25-10 μM), and 4-HNE (1.25-10 μM) dose dependently suppressed LPS-induced production of NO, ROS, and as p-cPLA₂ in BV-2 microglial cells. With the same concentrations, these compounds could enhance Nrf2 and HO-1 expression in these cells. Based on the estimated IC₅₀ values, 4-HHE and 4-HNE were five- to tenfold more potent than DHA in inhibiting LPS-induced NO, ROS, and p-cPLA₂. LC-MS/MS analysis indicated ability for DHA (10-50 μM) to increase levels of 4-HHE and attenuate levels of 4-HNE in BV-2 microglial cells. Stimulation of cells with LPS caused an increase in 4-HNE which could be abrogated by cPLA₂ inhibitor. In contrast, bromoenol lactone (BEL), a specific inhibitor for the Ca²⁺-independent phospholipase A₂ (iPLA₂), could only partially suppress levels of 4-HHE induced by DHA or DHA + LPS.

CONCLUSIONS

This study demonstrated the ability of DHA and its lipid peroxidation products, namely, 4-HHE and 4-HNE at 1.25-10 μM, to enhance Nrf2/HO-1 and mitigate LPS-induced NO, ROS, and p-cPLA₂ in BV-2 microglial cells. In addition, LC-MS/MS analysis of the levels of 4-HHE and 4-HNE in microglial cells demonstrates that increases in production of 4-HHE from DHA and 4-HNE from LPS are mediated by different mechanisms.

Minimum Selenium Requirements Increase When Repleting Second-Generation Selenium-Deficient Rats but Are Not Further Altered by Vitamin E Deficiency

Second-generation selenium-deficient weanling rats fed graded levels of dietary Se were used (a) to study the impact of initial Se deficiency on dietary Se requirements; (b) to determine if further decreases in selenoperoxidase expression, especially glutathione peroxidase 4 (Gpx4), affect growth or gross disease; and (c) to examine the impact of vitamin E deficiency on biochemical and molecular biomarkers of Se status. Rats were fed a vitamin E-deficient and Se-deficient crystalline amino acid diet (3 ng Se/g diet) or that diet supplemented with 100 μg/g all-rac-α-tocopheryl acetate and/or 0, 0.02, 0.05, 0.075, 0.1, or 0.2 μg Se/g diet as Na₂SeO₃ for 28 days. Se-supplemented rats grew 6.91 g/day as compared to 2.17 and 3.87 g/day for vitamin E-deficient/Se-deficient and vitamin E-supplemented/Se-deficient groups, respectively. In Se-deficient rats, liver Se, plasma Gpx3, red blood cell Gpx1, liver Gpx1 and Gpx4 activities, and liver Gpx1 mRNA levels decreased to <1, <1, 21, 1.6, 49, and 11 %, respectively, of levels in rats fed 0.2 μg Se/g diet. For all biomarkers, ANOVA indicated significant effects of dietary Se, but no significant effects of vitamin E or vitamin E × Se interaction, showing that vitamin E deficiency, even in severely Se-deficient rat pups, does not result in compensatory changes in these biochemical and molecular biomarkers of selenoprotein expression. Se requirements determined in this study, however, were >50 % higher than in previous studies that started with Se-adequate rats, demonstrating that dietary Se requirements determined using initially Se-deficient animals can result in overestimation of Se requirements.

Fish oil supplementation benefits the murine host during the acute phase of a parasitic infection from Trypanosoma cruzi

Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) are known to modulate a variety of immune cell functions. On occasion, this has led to diminished host resistance to certain viral and bacterial infections. Little is known about the impact of n-3 PUFA on host resistance to parasitic infection, however, based on results from a small study conducted more than two decades ago, we hypothesized that providing mice LC n-3 PUFA will diminish host resistance to Trypanosoma cruzi, the parasitic pathogen responsible for Chagas disease. To investigate this, C57BL/6 mice were supplemented by gavage (0.6% v/w) with phosphate-buffered saline, corn oil (CO), or menhaden fish oil (FO, a fat source rich in LC n-3 PUFA) for 15 days prior to T cruzi (Y strain) challenge and throughout the acute phase of infection. FO supplementation was associated with a transient 2-fold greater peak of blood parasitemia at 7 days postinfection (dpi), whereas subsequent cardiac parasitemia was ~60% lower at 12 dpi. FO treatment also ameliorated the leukopenia and thrombocytopenia observed in the early stages of a T cruzi infection. FO supplementation reduced circulating and cardiac nitric oxide at 7 and 12 dpi, respectively. FO supplementation altered ex vivo prostaglandin E₂ and cytokine and chemokine production by splenocytes isolated from uninfected and infected mice. Overall, our results suggest that oral administration of LC n-3 PUFA from FO can have beneficial effects on the host in the early course of a T cruzi infection.

An Investigation into the Immunomodulatory Activities of Sutherlandia frutescens in Healthy Mice

Sutherlandia frutescens is a medicinal plant that has been traditionally used in southern Africa for cancers, infections, and inflammatory conditions. We recently published experiments demonstrating that an aqueous extract of S. frutescens possessed potent immune-stimulatory activity. This work was carried out with murine macrophages, an immune cell type that plays a pivotal role in host defense from infection and in shaping host inflammatory and immune responses. Here, we conducted a series of follow-up experiments to explore the impact of consuming S. frutescens on host response to bacterial challenge using healthy mice. We found that feeding mice a diet containing S. frutescens failed to significantly alter host response to systemic infection by either a gram-positive or gram-negative bacterium (i.e., L. monocytogenes and E. coli, respectively). In contrast to the in vitro observations, we found no evidence that S. frutescens consumption stimulated in vivo inflammatory responses; instead, consumption of S. frutescens tended to diminish in vivo inflammatory responses. Several possible reasons for this are discussed.

Creating the Future of Evidence-Based Nutrition Recommendations: Case Studies from Lipid Research

Strategic translational research is designed to address research gaps that answer specific guidance questions. It provides translational value with respect to nutrition guidance and regulatory and public policy. The relevance and the quality of evidence both matter in translational research. For example, design decisions regarding population, intervention, comparator, and outcome criteria affect whether or not high-quality studies are considered relevant to specific guidance questions and are therefore included as evidence within the context of systematic review frameworks used by authoritative food and health organizations. The process used in systematic reviews, developed by the USDA for its Nutrition Evidence Library, is described. An eating pattern and cardiovascular disease (CVD) evidence review is provided as an example, and factors that differentiated the studies considered relevant and included in that evidence base from those that were excluded are noted. Case studies on ω-3 (n-3) fatty acids (FAs) and industrial trans-FAs illustrate key factors vital to relevance and translational impact, including choice of a relevant population (e.g., healthy, at risk, or diseased subjects; general population or high-performance soldiers); dose and form of the intervention (e.g., food or supplement); use of relevant comparators (e.g., technically feasible and realistic); and measures for both exposure and outcomes (e.g., inflammatory markers or CVD endpoints). Specific recommendations are provided to help increase the impact of nutrition research on future dietary guidance, policy, and regulatory issues, particularly in the area of lipids.

Withania somnifera and Its Withanolides Attenuate Oxidative and Inflammatory Responses and Up-Regulate Antioxidant Responses in BV-2 Microglial Cells

Withania somnifera (L.) Dunal, commonly known as Ashwagandha, has been used in Ayurvedic medicine for promoting health and quality of life. Recent clinical trials together with experimental studies indicated significant neuroprotective effects of Ashwagandha and its constituents. This study is aimed to investigate anti-inflammatory and anti-oxidative properties of this botanical and its two withanolide constituents, namely, Withaferin A and Withanolide A, using the murine immortalized BV-2 microglial cells. Ashwagandha extracts not only effectively inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) and reactive oxygen species (ROS) production in BV-2 cells, but also stimulates the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway, leading to induction of heme oxygenase-1 (HO-1), both in the presence and absence of LPS. Although the withanolides were also capable of inhibiting LPS-induced NO production and stimulating Nrf2/HO-1 pathway, Withaferin A was tenfold more effective than Withanolide A. In serum-free culture, LPS can also induce production of long thin processes (filopodia) between 4 and 8 h in BV-2 cells. This morphological change was significantly suppressed by Ashwagandha and both withanolides at concentrations for suppressing LPS-induced NO production. Taken together, these results suggest an immunomodulatory role for Ashwagandha and its withanolides, and their ability to suppress oxidative and inflammatory responses in microglial cells by simultaneously down-regulating the NF-kB and upregulating the Nrf2 pathways.

Phytochemicals and botanical extracts regulate NF-κB and Nrf2/ARE reporter activities in DI TNC1 astrocytes

The increase in oxidative stress and inflammatory responses associated with neurodegenerative diseases has drawn considerable attention towards understanding the transcriptional signaling pathways involving NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) and Nrf2 (Nuclear Factor Erythroid 2-like 2). Our recent studies with immortalized murine microglial cells (BV-2) demonstrated effects of botanical polyphenols to inhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) and enhance Nrf2-mediated antioxidant responses (Sun et al., 2015). In this study, an immortalized rat astrocyte (DI TNC1) cell line expressing a luciferase reporter driven by the NF-κB or the Nrf2/Antioxidant Response Element (ARE) promoter was used to assess regulation of these two pathways by phytochemicals such as quercetin, rutin, cyanidin, cyanidin-3-O-glucoside, as well as botanical extracts from Withania somnifera (Ashwagandha), Sutherlandia frutescens (Sutherlandia) and Euterpe oleracea (Açaí). Quercetin effectively inhibited LPS-induced NF-κB reporter activity and stimulated Nrf2/ARE reporter activity in DI TNC1 astrocytes. Cyanidin and the glycosides showed similar effects but only at much higher concentrations. All three botanical extracts effectively inhibited LPS-induced NF-κB reporter activity. These extracts were capable of enhancing ARE activity by themselves and further enhanced ARE activity in the presence of LPS. Quercetin and botanical extracts induced Nrf2 and HO-1 protein expression. Interestingly, Ashwagandha extract was more active in inducing Nrf2 and HO-1 expression in DI TNC1 astrocytes as compared to Sutherlandia and Açaí extracts. In summary, this study demonstrated NF-kB and Nrf2/ARE promoter activities in DI TNC1 astrocytes, and further showed differences in ability for specific botanical polyphenols and extracts to down-regulate LPS-induced NF-kB and up-regulate the NRF2/ARE activities in these cells.

Unveiling the anti-inflammatory activity of Sutherlandia frutescens using murine macrophages

Sutherlandia frutescens is a botanical widely used in southern Africa for treatment of inflammatory and other conditions. Previously, an ethanolic extract of S. frutescens (SFE) has been shown to inhibit the production of reactive oxygen species (ROS) and nitric oxide (NO) by murine neurons and a microglia cell line (BV-2 cells). In this study we sought to confirm the anti-inflammatory activities of SFE on a widely used murine macrophage cell line (i.e., RAW 264.7 cells) and primary mouse macrophages. Furthermore, experiments were conducted to investigate the anti-inflammatory activity of the flavonol and cycloartanol glycosides found in high quantities in S. frutescens. While the SFE exhibited anti-inflammatory activities upon murine macrophages similar to that reported with the microglia cell line, this effect does not appear to be mediated by sutherlandiosides or sutherlandins. In contrast, chlorophyll in our extracts appeared to be partly responsible for some of the activity observed in our macrophage-dependent screening assay.

Inhibition of Gli/hedgehog signaling in prostate cancer cells by "cancer bush" Sutherlandia frutescens extract

Sutherlandia frutescens is a medicinal plant, traditionally used to treat various types of human diseases, including cancer. Previous studies of several botanicals link suppression of prostate cancer growth with inhibition of the Gli/hedgehog (Gli/Hh) signaling pathway. Here we hypothesized the anti-cancer effect of S. frutescens was linked to its inhibition of the Gli/Hh signaling in prostate cancer. We found a dose- and time-dependent growth inhibition in human prostate cancer cells, PC3 and LNCaP, and mouse prostate cancer cell, TRAMP-C2, treated with S. frutescens methanol extract (SLE). We also observed a dose-dependent inhibition of the Gli-reporter activity in Shh Light II and TRAMP-C2QGli cells treated with SLE. In addition, SLE can inhibit Gli/Hh signaling by blocking Gli1 and Ptched1 gene expression in the presence of a Gli/Hh signaling agonist (SAG). A diet supplemented with S. frutescens suppressed the formation of poorly differentiated carcinoma in prostates of TRAMP mice. Finally, we found Sutherlandioside D was the most potent compound in the crude extract that could suppress Gli-reporter in Shh Light II cells. Together, this suggests that the S. frutescens extract may exert anti-cancer effect by targeting Gli/Hh signaling, and Sutherlandioside D is one of the active compounds.

High-Fat Diet Alters Serum Fatty Acid Profiles in Obesity Prone Rats: Implications for In Vitro Studies

High-fat diets (HFD) are commonly used in rodents to induce obesity, increase serum fatty acids and induce lipotoxicity in various organs. In vitro studies commonly utilize individual free fatty acids (FFA) to study lipid exposure in an effort to model what is occurring in vivo; however, these approaches are not physiological as tissues are exposed to multiple fatty acids in vivo. Here we characterize circulating lipids in obesity-prone rats fed an HFD in both fasted and fed states with the goal of developing physiologically relevant fatty acid mixtures for subsequent in vitro studies. Rats were fed an HFD (60% kcal fat) or a control diet (10% kcal fat) for 3 weeks; liver tissue and both portal and systemic blood were collected. Fatty acid profiles and absolute concentrations of triglycerides (TAG) and FFA in the serum and TAG, diacylglycerol (DAG) and phospholipids in the liver were measured. Surprisingly, both systemic and portal serum TAG were ~40% lower in HFD-fed compared to controls. Overall, compared to the control diet, HFD feeding consistently induced an increase in the proportion of circulating polyunsaturated fatty acids (PUFA) with a concomitant decline in monounsaturated fatty acids (MUFA) and saturated fatty acids (SFA) in both serum TAG and FFA. The elevations of PUFA were mostly attributed to increases in n-6 PUFA, linoleic acid and arachidonic acid. In conclusion, fatty acid mixtures enriched with linoleic and arachidonic acid in addition to SFA and MUFA should be utilized for in vitro studies attempting to model lipid exposures that occur during in vivo HFD conditions.

Immuno-stimulatory activity of a polysaccharide-enriched fraction of Sutherlandia frutescens occurs by the toll-like receptor-4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Sutherlandia frutescens (L.) R. Br. is an indigenous plant of southern Africa that has been traditionally used for various cancers, infections, and inflammatory conditions.

AIM OF THE STUDY

Our aim was to investigate the potential immuno-stimulatory activity of a polysaccharide-enriched fraction (SFPS) from a decoction of S. frutescens.

MATERIALS AND METHODS

RAW 264.7 cells (a murine macrophage cell line) were used to determine the activities of SFPS on macrophage function. The production of reactive oxygen species (ROS), nitric oxide (NO), and inflammatory cytokines were evaluated in the cells treated with or without SFPS. CLI-095, a toll-like receptor (TLR) 4-specific inhibitor, was used to identify whether or not SFPS exerts its effects through TLR4. An antagonist of endotoxin, polymyxin B, was used to evaluate whether endotoxin present in SFPS contributed to its immune-stimulatory activity.

RESULTS

SFPS exhibited potent immune-stimulatory activity by macrophages. The production of ROS, NO, and tumor necrosis factor (TNF-α) were increased upon exposure to SFPS in a dose-dependent manner. All of these activities were completely blocked by co-treatment with CLI-095, but only partially diminished by polymyxin B.

CONCLUSION

We demonstrate for the first time potent immune-stimulatory activity in a decoction prepared from S. frutescens. We believe that this immune stimulatory activity is due, in part, to the action of polysaccharides present in the decoction that acts by way of TLR4 receptors and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. These findings provide a plausible mechanism through which we can understand some of the medicinal properties of S. frutescens.

The science of fatty acids and inflammation

Inflammation is believed to play a central role in many of the chronic diseases that characterize modern society. In the past decade, our understanding of how dietary fats affect our immune system and subsequently our inflammatory status has grown considerably. There are compelling data showing that high-fat meals promote endotoxin [e.g., lipopolysaccharide (LPS)] translocation into the bloodstream, stimulating innate immune cells and leading to a transient postprandial inflammatory response. The nature of this effect is influenced by the amount and type of fat consumed. The role of various dietary constituents, including fats, on gut microflora and subsequent health outcomes in the host is another exciting and novel area of inquiry. The impact of specific fatty acids on inflammation may be central to how dietary fats affect health. Three key fatty acid-inflammation interactions are briefly described. First, the evidence suggests that saturated fatty acids induce inflammation in part by mimicking the actions of LPS. Second, the often-repeated claim that dietary linoleic acid promotes inflammation was not supported in a recent systematic review of the evidence. Third, an explanation is offered for why omega-3 (n-3) polyunsaturated fatty acids are so much less anti-inflammatory in humans than in mice. The article closes with a cautionary tale from the genomic literature that illustrates why extrapolating the results from inflammation studies in mice to humans is problematic.

Inhibition of microglial activation by elderberry extracts and its phenolic components

AIMS

Elderberry (Sambucus spp.) is one of the oldest medicinal plants noted for its cardiovascular, anti-inflammatory, and immune-stimulatory properties. In this study, we investigated the anti-inflammatory and anti-oxidant effects of the American elderberry (Sambucus nigra subsp. canadensis) pomace as well as some of the anthocyanins (cyanidin chloride and cyanidin 3-O-glucoside) and flavonols (quercetin and rutin) in bv-2 mouse microglial cells.

MAIN METHODS

The bv-2 cells were pretreated with elderberry pomace (extracted with ethanol or ethyl acetate) or its anthocyanins and flavonols and stimulated by either lipopolysaccharide (LPS) or interferon-γ (IFNγ). Reactive oxygen species (ROS) and nitric oxide (NO) production (indicating oxidative stress and inflammatory response) were measured using the ROS detection reagent DCF-DA and the Griess reaction, respectively.

KEY FINDINGS

Analysis of total monomeric anthocyanin (as cyanidin 3-O-glucoside equivalents) indicated five-fold higher amount in the freeze-dried ethanol extract as compared to that of the oven-dried extract; anthocyanin was not detected in the ethyl acetate extracts. Elderberry ethanol extracts (freeze-dried or oven-dried) showed higher anti-oxidant activities and better ability to inhibit LPS or IFNγ-induced NO production as compared with the ethyl acetate extracts. The phenolic compounds strongly inhibited LPS or IFNγ-induced ROS production, but except for quercetin, they were relatively poor in inhibiting NO production.

SIGNIFICANCE

These results demonstrated differences in anti-oxidative and anti-inflammatory effects of elderberry extracts depending on solvents used. Results further identified quercetin as the most active component in suppressing oxidative stress and inflammatory responses on microglial cells.

Determination of Anthocyanins and Total Polyphenols in a Variety of Elderberry Juices by UPLC-MS/MS and Other Methods

Elderberry (Sambucus spp.) juice contains a variety of polyphenols, mostly anthocyanins. In order to understand the variation of polyphenol levels by genotype, various elderberry juice samples were analyzed for total phenolics (TP), total monomeric anthocyanins (TMA) and individual anthocyanin content. The Folin-Ciocalteu total phenolic method and pH differential method were used to measure the TP and TMA content, respectively. The TP and TMA concentrations of elderberry were found to vary greatly among different genotypes. TMA content varied from 2.1% for 'Sperandio' to 60.6% for the 'Bob Gordon' cultivar. In addition, ultra-performance liquid chromatography with triple quadrupole mass spectrometry was used to separate and detect individual anthocyanins from samples prepared by solid phase extraction. Multiple-reaction-monitoring was used to process data for the reduction of false positives, maximizing selectivity, and reliable quantification. The quantitative performance of the method was validated, and a detection limit of 0.3 ng·ml^-1 for cyanidin 3-O-glucoside was determined. This newly developed method may serve to characterize and profile various anthocyanins in elderberry juices for quality control, assessment of dietary intake, and anthocyanin-based biomedical studies.

Effects of Elderberry Juice from Different Genotypes on Oxidative and Inflammatory Responses in Microglial Cells

Many species of berries are nutritious food and offer health benefits. However, among the different types of berries, information on health effects of American elderberries (Sambucus nigra subsp. canadensis) has been lacking and little is known about whether elderberry consumption can confer neuroprotective effects on the central nervous system. Microglial cells constitute a unique class of immune cells and exhibit characteristic properties to carry out multifunctional duties in the brain. Activation of microglial cells has been implicated in brain injury and in many types of neurodegenerative diseases. Our recent studies demonstrated the ability for endotoxin (lipopolysaccharide, LPS) and interferon gamma (IFNγ) to induce reactive oxygen species (ROS) and nitric oxide (NO) in murine microglial cells (BV-2) through activating NADPH oxidase and the MAPK pathways. In this study, BV-2 microglial cells were used to examine effects of elderberry juice obtained from different genotypes on oxidative and inflammatory responses induced by LPS and IFNγ. Results show that 'Wyldewood' extract demonstrated antioxidant properties by inhibiting IFNγ-induced ROS production and p-ERK1/2 expression. On the other hand, most juice extracts exerted small effects on LPS-induced NO production and some extracts showed an increase in NO production upon stimulation with IFNγ. The disparity of responses on ROS and NO production from different extracts suggests possible presence of unknown endogenous factor(s) in the extract in promoting the IFNγ-induced iNOS synthesis pathway.

Proteomic analysis of the effects of aged garlic extract and its FruArg component on lipopolysaccharide-induced neuroinflammatory response in microglial cells

Aged garlic extract (AGE) is widely used as a dietary supplement, and is claimed to promote human health through anti-oxidant/anti-inflammatory activities with hypolipidemic, antiplatelet and neuroprotective effects. Prior studies of AGE have mainly focused on its organosulfur compounds, with little attention paid to its carbohydrate derivatives, such as N-α-(1-deoxy-D-fructos-1-yl)-L-arginine (FruArg). The goal of this study is to investigate actions of AGE and FruArg on antioxidative and neuroinflammatory responses in lipopolysaccharide (LPS)-activated murine BV-2 microglial cells using a proteomic approach. Our data show that both AGE and FruArg can significantly inhibit LPS-induced nitric oxide (NO) production in BV-2 cells. Quantitative proteomic analysis by combining two dimensional differential in-gel electrophoresis (2D-DIGE) with mass spectrometry revealed that expressions of 26 proteins were significantly altered upon LPS exposure, while levels of 20 and 21 proteins exhibited significant changes in response to AGE and FruArg treatments, respectively, in LPS-stimulated BV-2 cells. Notably, approximate 78% of the proteins responding to AGE and FruArg treatments are in common, suggesting that FruArg is a major active component of AGE. MULTICOM-PDCN and Ingenuity Pathway Analyses indicate that the proteins differentially affected by treatment with AGE and FruArg are involved in inflammatory responses and the Nrf2-mediated oxidative stress response. Collectively, these results suggest that AGE and FruArg attenuate neuroinflammatory responses and promote resilience in LPS-activated BV-2 cells by suppressing NO production and by regulating expression of multiple protein targets associated with oxidative stress.

Dietary Sutherlandia and elderberry mitigate cerebral ischemia-induced neuronal damage and attenuate p47phox and phospho-ERK1/2 expression in microglial cells

Sutherlandia (Sutherlandia frutescens) and elderberry (Sambucus spp.) are used to promote health and for treatment of a number of ailments. Although studies with cultured cells have demonstrated antioxidative and anti-inflammatory properties of these botanicals, little is known about their ability to mitigate brain injury. In this study, C57BL/6 J male mice were fed AIN93G diets without or with Sutherlandia or American elderberry for 2 months prior to a 30-min global cerebral ischemia induced by occlusion of the bilateral common carotid arteries (BCCAs), followed by reperfusion for 3 days. Accelerating rotarod assessment at 24 h after BCCA occlusion showed amelioration of sensorimotor impairment in the mice fed the supplemented diets as compared with the ischemic mice fed the control diet. Quantitative digital pathology assessment of brain slides stained with cresyl violet at 3 days after ischemia/reperfusion (I/R) revealed significant reduction in neuronal cell death in both dietary groups. Immunohistochemical staining for ionized calcium-binding adapter molecule-1 demonstrated pronounced activation of microglia in the hippocampus and striatum in the ischemic brains 3 days after I/R, and microglial activation was significantly reduced in animals fed supplemented diets. Mitigation of microglial activation by the supplements was further supported by the decrease in expression of p47phox, a cytosolic subunit of NADPH oxidase, and phospho-ERK1/2, a mitogen-activated protein kinase known to mediate a number of cytoplasmic processes including oxidative stress and neuroinflammatory responses. These results demonstrate neuroprotective effect of Sutherlandia and American elderberry botanicals against oxidative and inflammatory responses to cerebral I/R.

Dissociable effects of dorsal and ventral hippocampal DHA content on spatial learning and anxiety-like behavior

Chronic deficiency of dietary docosahexaenoic acid (DHA) during critical developmental windows results in severe deficits in spatial learning, anxiety and hippocampal neuroplasticity that parallel a variety of neuropsychiatric disorders. However, little is known regarding the influence of long-term, multigenerational exposure to dietary DHA enrichment on these same traits. To characterize the potential benefits of multigenerational DHA enrichment, mice were fed a purified 10:1 omega-6/omega-3 diet supplemented with either 0.1% preformed DHA/kg feed weight or 1.0% preformed DHA/kg feed weight through three generations. General locomotor activity, spatial learning, and anxiety-like behavior were assessed in adult male offspring of the third generation. Following behavioral assessments, ventral and dorsal hippocampus was collected for DHA and arachidonic acid (AA) analysis. Animals consuming the 0.1% and 1.0% DHA diet did not differ from control animals for locomotor activity or on performance during acquisition learning, but made fewer errors and showed more stable across-day performance during reversal learning on the spatial task and showed less anxiety-like behavior. Consumption of the DHA-enriched diets increased DHA content in the ventral and dorsal hippocampus in a region-specific manner. DHA content in the dorsal hippocampus predicted performance on the reversal training task. DHA content in the ventral hippocampus was correlated with anxiety-like behavior, but AA content in the dorsal hippocampus was a stronger predictor of this behavior. These results suggest that long-term, multigenerational DHA administration improves performance on some aspects of complex spatial learning, decreases anxiety-like behavior, and that modulation of DHA content in sub-regions of the hippocampus predicts which behaviors are likely to be affected.

Sutherlandia frutescens ethanol extracts inhibit oxidative stress and inflammatory responses in neurons and microglial cells

Sutherlandia frutescens (L.) R.Br. (SF) is a medicinal plant indigenous to southern Africa and used in folk and contemporary remedies for stress, chronic diseases, cancer, and HIV/AIDS. While previous studies have focused on physiological effects of SF on cellular and systemic abnormalities associated with these diseases, little is known about its effects in the brain and immune cells in the central nervous system. Results of this study indicate that ethanol extracts of SF (SF-E) suppress NMDA-induced reactive oxygen species (ROS) production in neurons, and LPS- and IFNγ-induced ROS and nitric oxide (NO) production in microglial cells. SF-E’s action on microglial cells appears to be mediated through inhibition of the IFNγ-induced p-ERK1/2 signaling pathway which is central to regulating a number of intracellular metabolic processes including enhancing STAT1α phosphorylation and filopodia formation. The involvement of SF in these pathways suggests the potential for novel therapeutics for stress and prevention, and/or treatment of HIV/AIDS as well as other inflammatory diseases in the brain.

Linoleic acid, vegetable oils & inflammation

Should we listen to warnings that linoleic acid (LA) promotes inflammation and that Americans would be healthier if they restricted their intake of LA (i.e., vegetable oils)? A recently published systematic review of 15 clinical trials failed to find any support for the "diet LA causes inflammation hypothesis." These findings support current recommendations that a diet with 5 to 10 energy percentage from polyunsaturated fatty acids, such as LA, is healthful and appropriate for most Americans.

Abstract 1520: Simvastatin alters oxysterol profiles in TRAMP mice

Due to mounting epidemiological data evidence, we sought to determine if simvastatin, the most widely used cholesterol lowering medication, could alter prostate cancer incidence in the TRAMP mouse model of prostate cancer. We hypothesized that simvastatin would inhibit advanced prostate cancer formation. Two separate studies were performed using high doses of simvastatin (up to 0.050% w/w) or simvastatin plus genistein in a high fat Western diet. While prostate cancer incidence was only moderately reduced, surprising changes in the serum oxysterol profiles of the TRAMP mice were detected. Oxysterols, oxygenated derivatives of cholesterol, have recently been shown to influence human diseases, and here we suggest that five oxysterols may play a role in prostate cancer progression. Ten mice were chosen from each treatment group, and their serum oxysterol profiles were analyzed by LC-MS-MS. The oxysterol that was most responsive to treatment was 24(S)-hydroxycholesterol, reducing significantly in all treatment groups. 24(S)-OHC was reduced from the control at 20 ng/mL to 10 ng/mL with statin treatment (p-value &lt;0.001). 27-hydroxycholesterol was also reduced in the 0.044% simvastatin w/w dose to 10 ng/mL from 16 ng/mL in the control diet (p-value = 0.025). 5,6-dihydroxycholesterol responded to the 0.044% simvastatin diet lowering to 10 ng/mL as compared to the control of 18 ng/mL (p-value = 0.0002). 4-beta-hydroxycholesterol only responded to a combination of 0.050% simvastatin and 400 mg/kg genistein treatment, lowering from the control of 605 ng/mL down to 340 ng/mL with combination treatment (p-value &lt;0.0001). Lastly 7-keto-cholesterol was reduced by the 0.044% simvastatin treatment, lowering to 44 ng/mL from the control of 67 ng/mL (p-value = 0.004). Future studies will determine how these oxysterols can influence signaling pathways that can affect prostate cancer progression. In summary, we have found an off target effect of simvastatin treatment in TRAMP mice. Although serum cholesterol parameters remain statistically similar, with no observable changes in LDL, HDL, triglycerides, or total cholesterol, serum oxysterol profiles were changed significantly with simvastatin treatment. Potentially one of the pharmacological mechanisms for the beneficial effects of statin treatment on cancer outcomes is not due to their cholesterol lowering abilities, but instead may hinge on their capacity to change the concentration of oxysterols in vivo.

Citation Format: Sara K. Drenkhahn, Glenn A. Jackson, Nicholas J.E. Starkey, Yufei Li, Roxanne E. Gelven, Charles E. Wiedmeyer, Jim D. Browning, Kevin L. Fritsche, Cynthia L. Besch-Williford, Dennis B. Lubahn. Simvastatin alters oxysterol profiles in TRAMP mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1520. doi:10.1158/1538-7445.AM2013-1520

Comparison of inferred fractions of n-3 and n-6 polyunsaturated fatty acids in feral domestic cat diets with those in commercial feline extruded diets

OBJECTIVE

To compare presumed fatty acid content in natural diets of feral domestic cats (inferred from body fat polyunsatrated fatty acids content) with polyunsaturated fatty acid content of commercial feline extruded diets.

SAMPLE

Subcutaneous and intra-abdominal adipose tissue samples (approx 1 g) from previously frozen cadavers of 7 adult feral domestic cats trapped in habitats remote from human activity and triplicate samples (200 g each) of 7 commercial extruded diets representing 68% of market share obtained from retail stores.

PROCEDURES

Lipid, triacylglycerol, and phospholipid fractions in adipose tissue samples and ether extracts of diet samples were determined by gas chromatography of methyl esters. Triacylglycerol and phospholipid fractions in the adipose tissue were isolated by thin-layer chromatography. Diet samples were also analyzed for proximate contents.

RESULTS

For the adipose tissue samples, with few exceptions, fatty acids fractions varied only moderately with lipid fraction and site from which tissue samples were obtained. Linoleic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic acid fractions were 15.0% to 28.2%, 4.5% to 18.7%, 0.9% to 5.0%, < 0.1% to 0.2%, and 0.6% to 1.7%, respectively. As inferred from the adipose findings, dietary fractions of docosahexaenoic and α-linolenic acid were significantly greater than those in the commercial feline diets, but those for linoleic and eicosapentaenoic acids were not significantly different.

CONCLUSIONS AND CLINICAL RELEVANCE

The fatty acid content of commercial extruded feline diets differed from the inferred content of natural feral cat diets, in which dietary n-3 and possibly n-6 polyunsaturated fatty acids were more abundant. The impact of this difference on the health of pet cats is not known.

Sterculic oil, a natural inhibitor of SCD1, improves the metabolic state of obese OLETF rats

OBJECTIVE

Abnormal lipid metabolism and excess accumulation of lipid in non-adipose tissues are defining characteristics of obesity and its comorbidities. Expression and/or activity of stearoyl-CoA desaturase-1 (SCD1), a major regulator of lipid metabolism, is increased with obesity and the reduction/ablation of this enzyme is associated with an improved metabolic profile. Sterculic oil (SO), obtained from the seeds of the Sterculia feotida tree, contains a high concentration of cyclopropenoic fatty acids which are known inhibitors of SCD1. The purpose of this study was to determine the effects of SO supplementation on the development of obesity and insulin resistance in hyperphagic, obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats.

DESIGN & METHODS

Rats received either an AIN-93G diet (control) or an AIN-93G diet containing 0.5% SO for 10 weeks.

RESULTS

SO did not alter body weight or body composition. Importantly, the desaturase indices, a proxy for the activity of SCD1, were reduced in the liver and adipose tissue of SO supplemented animals. This reduction in SCD1 activity was associated with a reduction in fasting blood glucose concentrations and improved glucose tolerance. In addition, SO reduced intra-abdominal fat mass and adipocyte size and resulted in a ∼3-fold increase in GLUT1 gene expression in intra-abdominal fat. Liver triglyceride content and lipogenic gene expression were reduced by SO. Consistent with an improved metabolic phenotype, SO also improved plasma cholesterol, LDL-cholesterol, and triglyceride concentrations.

CONCLUSION

Overall, our data demonstrate an improved metabolic phenotype with SO supplementation and suggest further studies are required to better understand the therapeutic potential of SO.

Magnolia polyphenols attenuate oxidative and inflammatory responses in neurons and microglial cells

Background

The bark of magnolia has been used in Oriental medicine to treat a variety of remedies, including some neurological disorders. Magnolol (Mag) and honokiol (Hon) are isomers of polyphenolic compounds from the bark of Magnolia officinalis, and have been identified as major active components exhibiting anti-oxidative, anti-inflammatory, and neuroprotective effects. In this study, we investigate the ability of these isomers to suppress oxidative stress in neurons stimulated by the ionotropic glutamate receptor agonist N-methyl-D-aspartate (NMDA) and oxidative and inflammatory responses in microglial cells activated by interferon-γ (IFNγ) and lipopolysaccharide (LPS). We also attempt to elucidate the mechanism and signaling pathways involved in cytokine-induced production of reactive oxygen species (ROS) in microglial cells.

Methods

Dihydroethidium (DHE) was used to assay superoxide production in neurons, while CM-H2DCF-DA was used to test for ROS production in murine (BV-2) and rat (HAPI) immortalized microglial cells. NADPH oxidase inhibitors (for example, diphenyleneiodonium (DPI), AEBSF, and apocynin) and immunocytochemistry targeting p47phox and gp91phox were used to assess the involvement of NADPH oxidase. Western blotting was used to assess iNOS and ERK1/2 expression, and the Griess reaction protocol was employed to determine nitric oxide (NO) concentration.

Results

Exposure of Hon and Mag (1–10 μM) to neurons for 24 h did not alter neuronal viability, but both compounds (10 μM) inhibited NMDA-stimulated superoxide production, a pathway known to involve NADPH oxidase. In microglial cells, Hon and Mag inhibited IFNγ±LPS-induced iNOS expression, NO, and ROS production. Studies with inhibitors and immunocytochemical assay further demonstrated the important role of IFNγ activating the NADPH oxidase through the p-ERK-dependent pathway. Hon and, to a lesser extent, Mag inhibited IFNγ-induced p-ERK1/2 and its downstream pathway for ROS and NO production.

Conclusion

This study highlights the important role of NADPH oxidase in mediating oxidative stress in neurons and microglial cells and has unveiled the role of IFNγ in stimulating the MAPK/ERK1/2 signaling pathway for activation of NADPH oxidase in microglial cells. Hon and Mag offer anti-oxidative or anti-inflammatory effects, at least in part, through suppressing IFNγ-induced p-ERK1/2 and its downstream pathway.

Sterculic Oil, a Natural SCD1 Inhibitor, Improves Glucose Tolerance in Obese ob/ob Mice

Obesity and its metabolic complications are associated with increased expression/activity of stearoyl-CoA desaturase-1 (SCD1), a major regulator of lipid metabolism. Reduction or ablation of this enzyme is associated with an improved metabolic profile and has gained attention as a target for pharmaceutical development. Sterculic oil (SO) is a known inhibitor of SCD1 and may provide a natural approach for treating obesity and/or insulin resistance. The purpose of this study was to evaluate the effects of SO consumption in leptin-deficient ob/ob mice, a model of obesity and insulin resistance. Five-week-old male mice received either an AIN-93G (control) or an AIN-93G diet containing 0.5% SO. After 9 weeks, SO supplementation did not alter food intake or body weight; however, the desaturase indices, a proxy of SCD1 activity, were reduced in liver and adipose tissue of SO-supplemented animals. This reduction was associated with improved glucose and insulin tolerance and attenuated hepatic inflammation in obese ob/ob mice, while no appreciable changes were observed in lean control mice receiving SO. Future studies are needed to better understand the mechanism(s) by which SO is functioning to improve glucose metabolism and to further explore the nutraceutical potential and health implications of SO supplementation.

PGC-1α overexpression results in increased hepatic fatty acid oxidation with reduced triacylglycerol accumulation and secretion

Studies have shown that decreased mitochondrial content and function are associated with hepatic steatosis. We examined whether peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) overexpression and a subsequent increase in mitochondrial content and function in rat primary hepatocytes (in vitro) and Sprague-Dawley rats (in vivo) would comprehensively alter mitochondrial lipid metabolism, including complete (CO(2)) and incomplete (acid-soluble metabolites) fatty acid oxidation (FAO), tricarboxylic acid cycle flux, and triacylglycerol (TAG) storage and export. PGC-1α overexpression in primary hepatocytes produced an increase in markers of mitochondrial content and function (citrate synthase, mitochondrial DNA, and electron transport system complex proteins) and an increase in FAO, which was accompanied by reduced TAG storage and TAG secretion compared with control. Also, the PGC-1α-overexpressing hepatocytes were protected from excess TAG accumulation following overnight lipid treatment. PGC-1α overexpression in hepatocytes lowered expression of genes critical to VLDL assembly and secretion (apolipoprotein B and microsomal triglyceride transfer protein). Adenoviral transduction of rats with PGC-1α resulted in a liver-specific increase in PGC-1α expression and produced an in vivo liver phenotype of increased FAO via increased mitochondrial function that also resulted in reduced hepatic TAG storage and decreased plasma TAG levels. In conclusion, overexpression of hepatic PGC-1α and subsequent increases in FAO through elevated mitochondrial content and/or function result in reduced TAG storage and secretion in the in vitro and in vivo milieu.

Aggressive prostate cancer is prevented in ERαKO mice and stimulated in ERβKO TRAMP mice

Previous evidence suggests soy genistein may be protective against prostate cancer, but whether this protection involves an estrogen receptor (ER)-dependent mechanism is unknown. To test the hypothesis that phytoestrogens may act through ERα or ERβ to play a protective role against prostate cancer, we bred transgenic mice lacking functional ERα or ERβ with transgenic adenocarcinoma of mouse prostate (TRAMP) mice. Dietary genistein reduced the incidence of cancer in ER wild-type (WT)/transgenic adenocarcinoma of mouse prostate mice but not in ERα knockout (KO) or ERβKO mice. Cancer incidence was 70% in ERWT mice fed the control diet compared with 47% in ERWT mice fed low-dose genistein (300 mg/kg) and 32% on the high-dose genistein (750 mg/kg). Surprisingly, genistein only affected the well differentiated carcinoma (WDC) incidence but had no effect on poorly differentiated carcinoma (PDC). No dietary effects have been observed in either of the ERKO animals. We observed a very strong genotypic influence on PDC incidence, a protective effect in ERαKO (only 5% developed PDC), compared with 19% in the ERWT, and an increase in the incidence of PDC in ERβKO mice to 41%. Interestingly, immunohistochemical analysis showed ERα expression changing from nonnuclear in WDC to nuclear in PDC, with little change in ERβ location or expression. In conclusion, genistein is able to inhibit WDC in the presence of both ERs, but the effect of estrogen signaling on PDC is dominant over any dietary treatment, suggesting that improved differential targeting of ERα vs. ERβ would result in prevention of advanced prostate cancer.

Dietary fish oil substitution alters the eicosanoid profile in ankle joints of mice during Lyme infection

Dietary ingestion of (n-3) PUFA alters the production of eicosanoids and can suppress chronic inflammatory and autoimmune diseases. The extent of changes in eicosanoid production during an infection of mice fed a diet high in (n-3) PUFA, however, has not, to our knowledge, been reported. We fed mice a diet containing either 18% by weight soybean oil (SO) or a mixture with fish oil (FO), FO:SO (4:1 ratio), for 2 wk and then infected them with Borrelia burgdorferi. We used an MS-based lipidomics approach and quantified changes in eicosanoid production during Lyme arthritis development over 21 d. B. burgdorferi infection induced a robust production of prostanoids, mono-hydroxylated metabolites, and epoxide-containing metabolites, with 103 eicosanoids detected of the 139 monitored. In addition to temporal and compositional changes in the eicosanoid profile, dietary FO substitution increased the accumulation of 15-deoxy PGJ(2), an antiinflammatory metabolite derived from arachidonic acid. Chiral analysis of the mono-hydroxylated metabolites revealed they were generated from primarily nonenzymatic mechanisms. Although dietary FO substitution reduced the production of inflammatory (n-6) fatty acid-derived eicosanoids, no change in the host inflammatory response or development of disease was detected.

Abstract 4221: Inhibition of hedgehog signaling by extracts of sutherlandia

Many botanical compounds that have been proposed to prevent cancer may potentially work via inhibition of the hedgehog-signaling pathway. Here we investigated the potential of Sutherlandia frutescens (also called “cancer bush” in South Africa) to prevent and/or treat prostate cancer. We hypothesize that the anti-cancer effects of Sutherlandia are due to its inhibition of hedgehog-signaling pathway activity. To determine hedgehog pathway inhibitory activity, we treated Shh light II cells with multiple doses of a methanol extraction of Sutherlandia and measured Gli1 reporter activities.

Results: We found that a methanol extract of Sutherlandia was able to inhibit hedgehog pathway activity in a dose-dependent manner as monitored by Gli reporter assay (IC50=1:4000). Moreover, the Sutherlandia extract can inhibit the growth of human prostate cancer cells PC3 and LNCaP with IC50 of 1:400 and 1:1500 fold dilutions, respectively. At these same extract dilutions normal prostate cancer cell growth was not inhibited. Our data indicate that Sutherlandia contains potent anti-cancer botanicals that have hedgehog inhibitory activity.

Conclusion: Our results suggest that this plant offers a potentially cheap and effective alternative for hedgehog-driven cancer therapies. Additionally, Sutherlandia may yield novel targets that potentially could lead to a second generation hedgehog inhibitor, as resistance has been found to the first generation drugs currently in clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4221. doi:10.1158/1538-7445.AM2011-4221

Abstract 2399: Simvastatin inhibits advanced prostate cancer in TRAMP mice

Controversial literature suggests the potential off-label benefit of statins in the prevention of breast and prostate cancers. As millions of Americans are currently taking statins to lower cholesterol and prevent heart disease, we wanted to test if simvastatin could inhibit prostate carcinogenesis in the TRAMP (TRansgenic Adenocarcinoma of the Mouse Prostate) model. We hypothesized that simvastatin would inhibit the most aggressive form of cancer in the model, poorly differentiated carcinoma (PDC), similar to what has been seen in epidemiological studies. Mice were fed a Western Diet to mimic the high-fat diet common among men in the United States (n=25 per group). Two additional groups were fed the Western diet supplemented with either 0.025% or 0.050% w/w simvastatin. The control mice on the Western diet had an increase of PDC when compared to a low-fat AIN93 casein based diet (48% vs. 32%). While the 0.025% simvastatin Western diet reduced PDC incidence from 48% to 38%, the 0.050% simvastatin Western diet drastically reduced PDC incidence from 48% to 16% when compared to Western controls (p=0.0153 by Chi square analysis). Changes in serum profiles analyzing total cholesterol, LDL, HDL, and triglycerides did not correlate to the reduction in PDC incidence. In conclusion, our results show that simvastatin can reduce the most aggressive stage of prostate cancer in the TRAMP model and supports the observation that simvastatin reduces the risk of developing advanced prostate cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2399. doi:10.1158/1538-7445.AM2011-2399

Abstract 5705: Inhibition of hedgehog-signaling by extracts of the Sutherlandia and elderberry

Many botanical compounds, which have been proposed to prevent cancer, may potentially work via inhibition of the hedgehog-signaling pathway. Here we investigated the potential of Sutherlandia and elderberry to prevent and/or treat prostate cancer by inhibition of the hedgehog-signaling pathway. To determine hedgehog pathway inhibitory activity, we treated Shh light II cells with multiple doses of Sutherlandia extract or elderberry extract, in a Gli1 reporter assay to determine the extracts'effects on Gli1 concentration. The Sutherlandia extract was prepared by methanol extraction of Sutherlandia frutescens, while the elderberry extract was prepared by ethanol extraction of Sambucus nigra berries. We hypothesized that the compounds canavanine, from Sutherlandia, and cyanidin-3-glucoside, from elderberry, were the active compounds able to inhibit hedgehog signaling.

Results: We found that a 1:2000 dilution of Sutherlandia extract and a 1:100 dilution of elderberry extract are able to inhibit hedgehog pathway activity by 99% and 94%, respectively, as monitored by Gli reporter assay. Moreover, cyanidin-3- glucoside (5uM, 10uM and 50uM) can inhibit hedgehog activity by 44%,62% and 81% respectively, and canavanine (1uM and 10uM) can inhibit hedgehog activity by 5% and 15% respectively. These data indicate that, while these two compounds are weak hedgehog inhibitor compounds, they are unlikely to be the major active hedgehog inhibitory compounds in Sutherlandia and elderberry.

Conclusion: Our results suggest that these two plants offer a potentially cheap and effective alternative to cyclopamine for cancer therapies. Additionally, these plants may yield novel targets that potentially could lead to a second generation hedgehog inhibitor, if resistance is found to the first generation drugs currently in clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5705.

Too much linoleic acid promotes inflammation-doesn't it?

Controversy exists over how much linoleic acid (LA) should be consumed in a healthy diet. Some claim that high LA intake promotes inflammation through accumulation of tissue arachidonic acid (AA) and subsequent production of pro-inflammatory lipid mediators. Here the author reviews the current available evidence from human studies that address this issue. The data indicate that high LA in the diet or circulation is not associated with higher in vivo or ex vivo pro-inflammatory responses. Surprisingly, several studies showed that those individuals consuming the highest level of LA had the lowest inflammatory status. Recent findings suggest that LA and AA are involved in both pro- and anti-inflammatory signaling pathways. Thus, within the ranges of intake that are achievable for most human populations, the evidence do not support reducing LA intake below current consumption levels.

Fatty acid-mediated inhibition of IL-12 production by murine macrophages is independent of PPARγ

Our laboratory has reported thatn-3 PUFA can reduce host resistance toListeriainfection, in part, by impairingin vivoIL-12 biosynthesis. Recently, PUFA were shown to be ligands for PPAR, a novel family of nuclear receptors with three isoforms: PPARα, PPARδ/β and PPARγ. PPARγ is expressed in immune cells, such as T cells and macrophages. Two PPARγ agonists, 15-deoxy-Δ12,14-prostaglandin (PG) J2and rosiglitazone, have been shown to have immunomodulatory activityin vitro, including inhibiting IL-12 biosynthesis. We hypothesized thatn-3 PUFA inhibit IL-12 production through activating PPARγ. We used thioglycolate-elicited mouse peritoneal macrophages to study the effect of various fatty acids and their oxidized metabolites onin vitroIL-12 production. Our present results demonstrate that bothn-3 andn-6 PUFA can reducein vitroIL-12 biosynthesis, though less potently than 15-deoxy-PGJ2and rosiglitazone. GW9662, a PPARγ antagonist, reversed the inhibitory effect of rosiglitazone, but not that of PUFA. Our present findings suggest that fatty acid-mediated inhibition of IL-12 production is independent of PPARγ.

Stat1 deficiency exacerbates carditis but not arthritis during experimental lyme borreliosis

Activation of the transcription factor Stat1 by interferon-gamma (IFN-gamma) is an important step in the development of antimicrobial effector mechanisms against many bacterial pathogens. Susceptibility to murine Lyme arthritis has been correlated with the production of several proinflammatory cytokines, especially IFN-gamma. To determine the role of IFN-mediated effector mechanisms in the development of Lyme borreliosis, we infected Stat1-deficient mice on both resistant (DBA), and susceptible (C3H) genetic backgrounds. Arthritis in Stat1(/) mice was similar to that of wild-type controls in both mouse strains. Spirochete loads in tissues were also unchanged in Stat1(/) mice. C3H Stat1(/) mice exhibited increased inflammation in the heart, whereas carditis was unchanged in DBA Stat1(/) mice. These results demonstrate that inhibition of macrophage activation and responses to IFN-gamma-mediated signaling do not alter the arthritis resistance or susceptibility phenotype; however, they do affect the severity of carditis in susceptible mouse strains.

n-3 PUFA fail to affect in vivo, antigen-driven CD8+T-cell proliferation in the spleen of naïve mice

One of the most frequently reported immunomodulatory actions of n-3 PUFA is their ability to diminish in vitro lymphocyte proliferation. The purpose of this study was to determine if n-3 PUFA intake affects the kinetics or magnitude of the antigen-driven expansion of CD8(+)T-lymphocytes in vivo. In this study we utilized a well-characterized model of T-cell immunity (i.e. infection with the intracellular bacterium, Listeria monocytogenes). Weanling BALB/c mice were fed one of two experimental diets that differed solely in fat source. Our control diet contained lard (180 g/kg) and was devoid of long-chain n-3 PUFA. The experimental diet contained 150 g/kg menhaden fish oil and 30 g/kg corn oil, thus providing approximately 8 % of energy from long-chain n-3 PUFA. After 4 weeks, mice were infected intravenously with 10(6) colony-forming units of actA-deficient L. monocytogenes. Clonal expansion of antigen-specific CD8(+)T-cells in the spleen was measured at 5, 7, 9 and 14 d post-challenge using a class I MHC tetramer loaded with the immunodominant peptide from this pathogen (i.e. K(d):LLO91-99). We report that feeding mice a diet rich in n-3 fatty acids did not significantly impact either the kinetics or magnitude of in vivo, antigen-driven expansion of CD8(+)T-cells. Furthermore, contraction of this T-cell population was not affected by n-3 PUFA treatment. To our knowledge this is the first time MHC tetramers have been used to investigate the influence of n-3 PUFA on in vivo CD8(+)T-cell proliferation.