Transient receptor potential vanilloid (TRPV) channels are polymodal detectors of multiple environmental factors, including temperature, pH, and pressure. Inflammatory mediators enhance TRPV function through multiple signaling pathways. The lipoxygenase and epoxygenase products of arachidonic acid (AA) metabolism have been shown to directly activate TRPV1 and TRPV4, respectively. TRPV3 is a thermosensitive channel with an intermediate temperature threshold of 31-39 degrees C. We have previously shown that TRPV3 is activated by 2-aminoethoxydiphenyl borate (2APB). Here we show that AA and other unsaturated fatty acids directly potentiate 2APB-induced responses of TRPV3 expressed in HEK293 cells, Xenopus oocytes, and mouse keratinocytes. The AA-induced potentiation is observed in intracellular Ca2+ measurement, whole-cell and two-electrode voltage clamp studies, as well as single channel recordings of excised inside-out and outside-out patches. The fatty acid-induced potentiation is not blocked by inhibitors of protein kinase C and thus differs from that induced by the kinase. The potentiation does not require AA metabolism but is rather mimicked by non-metabolizable analogs of AA. These results suggest a novel mechanism regulating the TRPV3 response to inflammation, which differs from TRPV1 and TRPV4, and involves a direct action of free fatty acids on the channel.

Some dietary factors could inhibit lead toxicity. The aim of this study was to evaluate the effect of dietary compounds rich in unsaturated fatty acids (FA) on blood lead level, lipid metabolism, and vascular reactivity in rats. Serum metallothionein and organs' lead level were evaluated with the aim of assessing the possible mechanism of unsaturated FA impact on blood lead level. For three months, male Wistar rats that were receiving drinking water with (100 ppm Pb) or without lead acetate were supplemented per os daily with virgin olive oil or linseed oil (0.2 mL/kg b.w.) or egg derived lecithin fraction: "super lecithin" (50 g/kg b.w.). Mesenteric artery was stimulated ex vivo by norepinephrine (NE) administered at six different doses. Lecithin supplementation slightly reduced pressor responses of artery to NE. Lead administered to rats attenuated the beneficial effect of unsaturated FA on lipid metabolism and vascular reactivity to adrenergic stimulation. On the other hand, the super lecithin and linseed oil that were characterized by low omega-6 to omega-3 ratio (about 1) reduced the blood lead concentration. This effect was observed in lead poisoned rats (p < 0.0001) and also in rats nonpoisoned with lead (p < 0.05).

In experimental models, hypothalamic inflammation is an early and determining factor in the installation and progression of obesity. Pharmacological and gene-based approaches have proven efficient in restraining inflammation and correcting the obese phenotypes. However, the role of nutrients in the modulation of hypothalamic inflammation is unknown.

Polyunsaturated fatty acids are oxidized by non‑enzymatic or enzymatic reactions. The oxidized products are multifunctional. In this study, we investigated how oxidized fatty acids inhibit cell proliferation in cultured cells. We used polyunsaturated and saturated fatty acids, docosahexaenoic acid (DHA; 22:6), eicosapentaenoic acid (EPA; 20:5), linoleic acid (LA; 18:2), and palmitic acid (16:0). Oxidized fatty acids were produced by autoxidation of fatty acids for 2 days in the presence of a gas mixture (20% O2 and 80% N2). We found that oxidized polyunsaturated fatty acids (OxDHA, OxEPA and OxLA) inhibited cell proliferation much more effectively compared with un‑oxidized fatty acids (DHA, EPA and LA, respectively) in THP‑1 (a human monocytic leukemia cell line) and DLD‑1 (a human colorectal cancer cell line) cells. In particular, OxDHA markedly inhibited cell proliferation. DHA has the largest number of double bonds and is most susceptible to oxidation among the fatty acids. OxDHA has the largest number of highly active oxidized products. Therefore, the oxidative levels of fatty acids are associated with the anti‑proliferative activity. Moreover, caspase‑3/7 was activated in the cells treated with OxDHA, but not in those treated with DHA. A pan‑caspase inhibitor (zVAD‑fmk) reduced the cell death induced by OxDHA. These results indicated that oxidized products from polyunsaturated fatty acids induced apoptosis in cultured cells. Collectively, the switch between cell survival and cell death may be regulated by the activity and/or number of oxidized products from polyunsaturated fatty acids.

Supplemented fatty acids can incorporate into cardiolipin (CL) and affect its remodeling. The change in CL species may alter the mitochondrial membrane composition, potentially disturbing the mitochondrial structure and function during inflammation.

1. Whole-cell recordings from cultured rat hippocampal neurons, from freshly dissociated dorsal root ganglion (DRG) neurons and from human embryonic kidney (HEK) 293 cells expressing the glutamate receptor GluR6 subunit were used to study the modulation of kainate receptor channels by long chain fatty acids. 2. In all three cell types, application of cis-unsaturated fatty acids caused a dose-dependent reduction in whole-cell currents evoked by kainate. Docosahexaenoic acid (DHA), arachidonic acid (AA), linolenic acid and linoleic acid all produced substantial inhibition at a concentration of 50 microM, whereas inhibition by linolenelaidic acid and linolelaidic acid was significantly weaker. Fully saturated fatty acids were essentially inactive. 3. With continuous exposure to active fatty acids, the peak current elicited by kainate declined over a time course of several minutes to reach a steady-state level less than 50 % of the initial amplitude. Recovery was slow in control solution, but was speeded up by exposure to bovine serum albumin (0.5 mg ml-1), a protein that binds fatty acids with submicromolar affinity. The inhibition in neurons was half-maximal with 5-15 microM AA or DHA, but potency was at least 10-fold greater at GluR6 in HEK 293 cells. 4. Inhibition by AA or DHA was unaffected by extracellular nordihydroguaiaretic acid (10 microM), indomethacin (10 microM), 17-octadecynoic acid (30 microM) or 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine dihydrochloride (H-7; 10 microM). Furthermore, inclusion of H-7 (100 microM), BAPTA (10 mM), AA (50 microM), antioxidants, or the protein kinase C inhibitor PKC19-36 (20 microM) in the internal solution had little effect on whole-cell currents and did not prevent inhibition of currents by extracellular application of AA or DHA. 5. We conclude that the inhibition produced by cis-unsaturated fatty acids does not require conversion to oxidized metabolites or activation of PKC. Instead, active compounds may interact directly with an extracellular, or intramembraneous, site on kainate receptors.

Obesity is not a homogeneous condition across individuals since about 25-40% of obese individuals can maintain healthy status with no apparent signs of metabolic complications. The simple anthropometric measure of body mass index does not always reflect the biological effects of excessive body fat on health, thus additional molecular characterizations of obese phenotypes are needed to assess the risk of developing subsequent metabolic conditions at an individual level.

Chromatin and metabolic states both influence lifespan, but how they interact in lifespan regulation is largely unknown. The COMPASS chromatin complex, which trimethylates lysine 4 on histone H3 (H3K4me3), regulates lifespan in Caenorhabditis elegans. However, the mechanism by which H3K4me3 modifiers affect longevity, and whether this mechanism involves metabolic changes, remain unclear. Here we show that a deficiency in H3K4me3 methyltransferase, which extends lifespan, promotes fat accumulation in worms with a specific enrichment of mono-unsaturated fatty acids (MUFAs). This fat metabolism switch in H3K4me3 methyltransferase-deficient worms is mediated at least in part by the downregulation of germline targets, including S6 kinase, and by the activation of an intestinal transcriptional network that upregulates delta-9 fatty acid desaturases. Notably, the accumulation of MUFAs is necessary for the lifespan extension of H3K4me3 methyltransferase-deficient worms, and dietary MUFAs are sufficient to extend lifespan. Given the conservation of lipid metabolism, dietary or endogenous MUFAs could extend lifespan and healthspan in other species, including mammals.

Polyunsaturated fatty acids (PUFA) are reported to exert prophylactic and acute therapeutic effects in diseases linked to endothelial dysfunction. In the present study, the consequences of a PUFA enrichment of endothelial cells (cell line TIME) on cell viability, expression of the cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), granulocyte-macrophage colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein 1 (MCP-1), synthesis of the adhesion molecules intercellular adhesion molecule 1 (ICAM-1) and vascular adhesion molecule 1 (VCAM-1), and production of the coagulation factors plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF), and tissue factor (TF) was analyzed in parallel. PUFA of both the n3 and the n6 family were investigated in a physiologically relevant concentration of 15 µM, and experiments were performed in both the presence and the absence of the pro-inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ). Supplementation of the culture medium with particular fatty acids was found to have a promoting effect on cellular production of the cytokines IL-6, IL-8, GM-CSF, and MCP-1. Further on, PUFA treatment in the absence of a stimulant diminished the percentage of endothelial cells positive for ICAM-1, and adversely affected the stimulation-induced upregulation of VCAM-1. Cell viability and production of coagulation factors were not or only marginally affected by supplemented fatty acids. Altogether, the data indicate that PUFA of either family are only partially able to counterbalance the destructive consequences of an endothelial dysfunction.

Increased metabolism is a requirement for tumor cell proliferation. To understand the dependence of tumor cells on fatty acid metabolism, we evaluated various nodes of the fatty acid synthesis pathway. Using RNAi we have demonstrated that depletion of fatty-acid synthesis pathway enzymes SCD1, FASN, or ACC1 in HCT116 colon cancer cells results in cytotoxicity that is reversible by addition of exogenous fatty acids. This conditional phenotype is most pronounced when SCD1 is depleted. We used this fatty-acid rescue strategy to characterize several small-molecule inhibitors of fatty acid synthesis, including identification of TOFA as a potent SCD1 inhibitor, representing a previously undescribed activity for this compound. Reference FASN and ACC inhibitors show cytotoxicity that is less pronounced than that of TOFA, and fatty-acid rescue profiles consistent with their proposed enzyme targets. Two reference SCD1 inhibitors show low-nanomolar cytotoxicity that is offset by at least two orders of magnitude by exogenous oleate. One of these inhibitors slows growth of HCT116 xenograft tumors. Our data outline an effective strategy for interrogation of on-mechanism potency and pathway-node-specificity of fatty acid synthesis inhibitors, establish an unambiguous link between fatty acid synthesis and cancer cell survival, and point toward SCD1 as a key target in this pathway.

Obesity and metabolic syndrome are associated with cognitive decline and dementia. Palmitic acid (PA) is increased in the cerebrospinal fluid of obese patients with cognitive impairment. This study was therefore designed to examine fatty acid (FA) lipotoxicity in BV2 microglia cells. We found that PA induced time- and dose-dependent decrease in cell viability and increase in cell death without affecting the cell cycle profile and that PA lipotoxicity did not depend on cell surface free fatty acid receptors but rather on FA uptake. Treatment with sulfosuccinimidyl oleate (SSO), an irreversible inhibitor of fatty acid translocase CD36, significantly inhibited FA uptake in BSA- and PA-treated cells and blocked PA-induced decrease in cell viability. Inhibition of ER stress or treatment with N-acetylcysteine was not able to rescue PA lipotoxicity. Our study also showed that unsaturated fatty acids (UFAs), such as linoleic acid (LA), oleic acid (OA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA), were not lipotoxic but instead protected microglia against PA-induced decrease in cell viability. Co-treatment of PA with LA, OA, and DHA significantly inhibited FA uptake in PA-treated cells. All UFAs tested induced the incorporation of FAs into and the amount of neutral lipids, while PA did not significantly affect the amount of neutral lipids compared with BSA control.

Furan fatty acids (FuFAs) are valuable minor fatty acids, which are known for their excellent radical scavenging properties. Typically, the furan moiety is embedded in an otherwise saturated carboxyalkyl chain. Occasionally, these classic FuFAs are accompanied by low amounts of unsaturated furan fatty acids (uFuFAs), which additionally feature one double bond in conjugation with the furan moiety. A recent study produced evidence for the occurrence of two pairs of E-/Z-uFuFA isomers structurally related to saturated uFuFAs. Here, we present a strategy that allowed such trace compounds to be enriched to a level suited for structure determination by NMR. Given the low amounts and the varied abundance ratio of the four uFuFA isomers, the isolation of individual compounds was not pursued. Instead, the entire isomer mixture was enriched to an amount and purity suitable for structure investigation with contemporary NMR methods. Specifically, lipid extracted from 150 g latex, the richest known source of FuFAs, was subsequently fractionated by countercurrent chromatography (CCC), silver ion, and silica gel column chromatography. Analysis of the resulting mixture of four uFuFAs isomers (2.4 mg in an abundance ratio of 56:23:11:9) by different NMR techniques including PSYCHE verified that the structures of the two most abundant isomers were E-9-(3-methyl-5-pentylfuran-2-yl)non-8-enoic acid and E-9-(3-methyl-5-pent-1-enylfuran-2-yl)nonanoic acid. Additionally, we introduced a computer-based method to generate an averaged chromatogram from freely selectable GC/MS runs of CCC fractions without the necessity of pooling aliquots. This method was found to be suitable to simplify subsequent enrichment steps.

The aim of this study was to evaluate the effects of various combinations of tropical grass-legume species in rations on the biohydrogenation (BH) activity of unsaturated fatty acids (FAs), C18:0 composition, and fermentation profile in an in vitro rumen system.

In this study, we aimed to develop natural and/or functional materials with antioxidant and anti-inflammatory effects. We obtained extracts from natural plants through an oil and hot-water extraction process and prepared an extract composite of an effective unsaturated fatty acid complex (EUFOC). Furthermore, the antioxidant effect of the extract complex was evaluated, and the anti-inflammatory effect was explored by assessing its inhibitory effect on nitric oxide production through its HA-promoting effect. We conducted a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay to evaluate the cell viability of the EUFOC, and the results showed that EUFOC was not cytotoxic at the test concentrations. In addition, it showed no endogenous cytotoxicity in HaCaT (human keratinocyte) cells. The EUFOC showed excellent 1,1-diphenyl-2-picrylhydrazyl- and superoxide-scavenging abilities. Moreover, it exerted an inhibitory effect on NO production at concentrations that did not inhibit cell viability. The secretion of all the cytokines was increased by lipopolysaccharide (LPS) treatment; however, this was inhibited by the EUFOC in a concentration-dependent manner. In addition, hyaluronic acid content was markedly increased by the EUFOC in a dose-dependent manner. These results suggest that the EUFOC has excellent anti-inflammatory and antioxidant properties, and hence, it can be used as a functional material in various fields.

Infections involving biofilms are difficult to treat due to increased resistances against antibiotics and the immune system. Hence, there is an urgent demand for novel drugs against biofilm infections. During our search for novel biofilm inhibitors from fungi, we isolated linoleic acid from the ascomycete Hypoxylon fragiforme which showed biofilm inhibition of several bacteria at sub-MIC concentrations. Many fatty acids possess antimicrobial activities, but their minimum inhibitory concentrations (MIC) are high and reports on biofilm interferences are scarce. We demonstrated that not only linoleic acid but several unsaturated long-chain fatty acids inhibited biofilms at sub-MIC concentrations. The antibiofilm activity exerted by long-chain fatty acids was mainly against Gram-positive bacteria, especially against Staphylococcus aureus. Micrographs of treated S. aureus biofilms revealed a reduction in the extracellular polymeric substances, pointing to a possible mode of action of fatty acids on S. aureus biofilms. The fatty acids had a strong species specificity. Poly-unsaturated fatty acids had higher activities than saturated ones, but no obvious rule could be found for the optimal length and desaturation for maximal activity. As free fatty acids are non-toxic and ubiquitous in food, they may offer a novel tool, especially in combination with antibiotics, for the control of biofilm infections.

Fatty acids are an important source of energy and a key component of phospholipids in membranes and organelles. Saturated fatty acids (SFAs) are converted into unsaturated fatty acids (UFAs) by stearoyl Co-A desaturase (SCD), an enzyme active in cancer. Here, we studied how the dynamics between SFAs and UFAs regulated by SCD impacts ovarian cancer cell survival and tumor progression. SCD depletion or inhibition caused lower levels of UFAs vs. SFAs and altered fatty acyl chain plasticity, as demonstrated by lipidomics and stimulated Raman scattering (SRS) microscopy. Further, increased levels of SFAs resulting from SCD knockdown triggered endoplasmic reticulum (ER) stress response with brisk activation of IRE1α/XBP1 and PERK/eIF2α/ATF4 axes. Disorganized ER membrane was visualized by electron microscopy and SRS imaging in ovarian cancer cells in which SCD was knocked down. The induction of long-term mild ER stress or short-time severe ER stress by the increased levels of SFAs and loss of UFAs led to cell death. However, ER stress and apoptosis could be readily rescued by supplementation with UFAs and reequilibration of SFA/UFA levels. The effects of SCD knockdown or inhibition observed in vitro translated into suppression of intraperitoneal tumor growth in ovarian cancer xenograft models. Furthermore, a combined intervention using an SCD inhibitor and an SFA-enriched diet initiated ER stress in tumors growing in vivo and potently blocked their dissemination. In all, our data support SCD as a key regulator of the cancer cell fate under metabolic stress and point to treatment strategies targeting the lipid balance.

Highly unsaturated fatty acids (HUFAs) are fatty acids with more than three double bonds in the molecule. Mammalian testes contain very high levels of omega-6 HUFAs compared with other tissues. However, the metabolic and biological significance of these HUFAs in the mammalian testis is poorly understood. Here we show that Leydig cells vigorously synthesize omega-6 HUFAs to facilitate male sex hormone production. In the testis, FADS2 (Fatty acid desaturase 2), the rate-limiting enzyme for HUFA biosynthesis, is highly expressed in Leydig cells. In this study, pharmacological and genetic inhibition of FADS2 drastically reduces the production of omega-6 HUFAs and male steroid hormones in Leydig cells; this reduction is significantly rescued by supplementation with omega-6 HUFAs. Mechanistically, hormone-sensitive lipase (HSL; also called LIPE), a lipase that supplies free cholesterol for steroid hormone production, preferentially hydrolyzes HUFA-containing cholesteryl esters as substrates. Taken together, our results demonstrate that Leydig cells highly express FADS2 to facilitate male steroid hormone production by accumulating omega-6 HUFA-containing cholesteryl esters, which serve as preferred substrates for HSL. These findings unveil a previously unrecognized importance of omega-6 HUFAs in the mammalian male reproductive system.

It is well established that Staphylococcus aureus can incorporate exogenous straight-chain unsaturated fatty acids (SCUFAs) into membrane phospho- and glyco-lipids from various sources in supplemented culture media, and when growing in vivo in an infection. Given the enhancement of membrane fluidity when oleic acid (C18:1Δ9) is incorporated into lipids, we were prompted to examine the effect of medium supplementation with C18:1Δ9 on growth at low temperatures. C18:1Δ9 supported the growth of a cold-sensitive, branched-chain fatty acid (BCFA)-deficient mutant at 12°C. Interestingly, we found similar results in the BCFA-sufficient parental strain. We show that incorporation of C18:1Δ9 and its elongation product C20:1Δ9 into membrane lipids was required for growth stimulation and relied on a functional FakAB incorporation system. Lipidomics analysis of the phosphatidylglycerol (PG) and diglycosyldiacylglycerol (DGDG) lipid classes revealed major impacts of C18:1Δ9 and temperature on lipid species. Growth at 12°C in the presence of C18:1Δ9 also led to increased production of the carotenoid pigment staphyloxanthin; however, this was not an obligatory requirement for cold adaptation. Enhancement of growth by C18:1Δ9 is an example of homeoviscous adaptation to low temperatures utilizing an exogenous fatty acid. This may be significant in the growth of S. aureus at low temperatures in foods that commonly contain C18:1Δ9 and other SCUFAs in various forms.

Binding of 18-carbon unsaturated oleic and linoleic acid to lactoglobulin, the milk protein, has been studied for the first time by isothermal titration calorimetry (ITC) and X-ray crystallography. Crystal structures determined to resolution 2.10 Å have revealed presence of single fatty acid molecule bound in β-barrel, the primary binding site, with carboxyl group hydrogen bonded to Glu62. The aliphatic chain of both ligands is in almost linear conformation and their interactions with the protein are similar to observed in structure of lactoglobulin with stearic acid. The ITC experiments showed that binding of unsaturated fatty acids to LGB is spontaneous and exothermic. The stoichiometry of binding is lower than 1.0, association constant is 9.7 × 10(5)M(-1) and 9.0 × 10(5)M(-1) for oleic and linoleic acid, respectively. Solvent relief seems to be the major contributor to entropic changes upon fatty acid binding to lactoglobulin.

Elevated plasma concentrations of saturated free fatty acids (SFAs) are involved in pancreatic β-cell dysfunction and apoptosis, referred to as lipotoxicity. However, in contrast to apoptosis, the involvement of ferroptosis, as a distinct type of oxidative regulated cell death in β-cell lipotoxicity remains elusive. Therefore, the aim of this study was to determine the effects of various free fatty acids on ferroptosis induction in rat insulin-producing β-cells. Herein, rat insulin-producing β-cells underwent lipid peroxidation in the presence of long-chain SFAs and ω-6-polyunsaturated fatty acids (PUFAs), but only the latter induced ferroptosis. On the other hand, the ω-3-PUFA α-linolenate did not induce ferroptosis but sensitized insulin-producing β-cells to SFA-mediated lipid peroxidation. While the monounsaturated fatty acid oleate, overexpression of glutathione peroxidase 4, and the specific ferroptosis inhibitor ferrostatin-1 significantly abrogated lipid peroxidation, neither glutathione peroxidase 4 nor ferrostatin-1 affected palmitate-mediated toxicity. Site-specific expression of catalase in cytosol, mitochondria, and ER attenuated lipid peroxidation, indicating the contribution of metabolically generated H2O2 from all three subcellular compartments. These observations suggest that only ω-6-PUFAs reach the thresholds of lipid peroxidation required for ferroptosis, whereas SFAs favour apoptosis in β-cells. Hence, avoiding an excessive dietary intake of ω-6-PUFAs might be a crucial prerequisite for prevention of reactive oxygen species-mediated ferroptosis in insulin-producing cells.