Polyunsaturated fatty acids alter the formation of lipid droplets and eicosanoid production in Leishmania promastigotes

BACKGROUND The knowledge about eicosanoid metabolism and lipid droplet (LD) formation in the Leishmania is very limited and new approaches are needed to identify which bioactive molecules are produced of them. OBJECTIVES Herein, we compared LDs and eicosanoids biogenesis in distinct Leishmania species which are etiologic agents of different clinical forms of leishmaniasis. METHODS For this, promastigotes of Leishmania amazonensis, L. braziliensis and L. infantum were stimulated with polyunsaturated fatty acids (PUFA) and LD and eicosanoid production was evaluated. We also compared mutations in structural models of human-like cyclooxygenase-2 (GP63) and prostaglandin F synthase (PGFS) proteins, as well as the levels of these enzymes in parasite cell extracts. FINDINGS PUFAs modulate the LD formation in L. braziliensis and L. infantum. Leishmania spp with equivalent tissue tropism had same protein mutations in GP63 and PGFS. No differences in GP63 production were observed among Leishmania spp, however PGFS production increased during the parasite differentiation. Stimulation with arachidonic acid resulted in elevated production of hydroxyeicosatetraenoic acids compared to prostaglandins. MAIN CONCLUSIONS Our data suggest LD formation and eicosanoid production are distinctly modulated by PUFAS dependent of Leishmania species. In addition, eicosanoid-enzyme mutations are more similar between Leishmania species with same host tropism.

Lipid droplets of protozoan parasites: survival and pathogenicity

Lipid droplets (LDs; lipid bodies) are intracellular sites of lipid storage and metabolism present in all cell types. Eukaryotic LDs are involved in eicosanoid production during several inflammatory conditions, including infection by protozoan parasites. In parasites, LDs play a role in the acquisition of cholesterol and other neutral lipids from the host. The number of LDs increases during parasite differentiation, and the biogenesis of these organelles use specific signaling pathways involving protein kinases. In addition, LDs are important in cellular protection against lipotoxicity. Recently, these organelles have been implicated in eicosanoid and specialised lipid metabolism. In this article, we revise the main functions of protozoan parasite LDs and discuss future directions in the comprehension of these organelles in the context of pathogen virulence.

Metabolic Syndrome: Modification of the Fatty Acid Composition and Glucose-insulin Homeostasis.

Objective: Metabolic syndrome is a widespread disease associated with cardiovascular pathologies and diabetes mellitus. The underlying mechanisms for development of the metabolic syndrome are currently being intensively discussed. Contradictory data regarding the role of lipid metabolism disorders in trigger mechanisms of metabolic syndrome necessitate thorough analysis of the content of fatty acids in plasma and blood cells. The aim of our study was to examine the content of free and esterified fatty acids and the levels of eicosanoids in metabolic syndrome with various insulin resistance. We evaluate the role of fatty acids and their metabolites in the development of metabolic syndrome. Study Design: Cross-sectional study. Place and Duration of Study: Vladivostok Branch of Far Eastern Scientific Center of Physiology and Pathology of Respiration – Research Institute of Medical Climatology and Rehabilitation Treatment, Russia, 2012-2013. Materials/Methods: The study involved three groups of volunteers: 15 persons without components of the metabolic syndrome, 30 patients with metabolic syndrome and the normal insulin level, 31 patients with metabolic syndrome and diagnosed insulin resistance. We examined the levels of fasting glucose and glucose content after 2 hours of per oral glucose load, insulin, total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, eicosanoids. The content of fatty acids in plasma and erythrocytes was analyzed by gas chromatography. Statistica software was used for data analysis. Results: We detect reciprocal changes in the content of plasma and erythrocytes fatty acids in metabolic syndrome with and without insulin resistance. Such fatty acids as 18:2n-6, 18:3n-3 are accumulating in plasma, while 18:2n-6, 18:3n-3, 20:4n-6 in erythrocytes are in deficiency. The levels of eicosanoids in metabolic syndrome are elevated. Conclusion: Our results determined the role of fatty acids and their metabolites in the development of the metabolic syndrome. We propose the concept of metabolic syndrome according to which the trigger for the development of the metabolic syndrome is the modification of the fatty acid composition of blood cells as the result of disorders in their receptor-mediated transport.

Anopheles gambiae eicosanoids modulate Plasmodium berghei survival from oocyst to salivary gland invasion

Eicosanoids affect the immunity of several pathogen/insect models, but their role on the Anopheles gambiae response to Plasmodium is still unknown. Plasmodium berghei-infected mosquitoes were injected with an eicosanoid biosynthesis inhibitor, indomethacin (IN), or a substrate, arachidonic acid (AA), at day 7 or day 12 post-infection (p.i.). Salivary gland invasion was evaluated by sporozoite counts at day 21 p.i. IN promoted infection upon sporozoite release from oocysts, but inhibited infection when sporozoites were still maturing within the oocysts, as observed by a reduction in the number of sporozoites reaching the salivary glands. AA treatment had the opposite effect. We show for the first time that An. gambiae can modulate parasite survival through eicosanoids by exerting an antagonistic or agonistic effect on the parasite, depending on its stage of development.

Britanin Suppresses IgE/Ag-Induced Mast Cell Activation by Inhibiting the Syk Pathway

The aim of this study was to determine whether britanin, isolated from the flowers of Inula japonica (Inulae Flos), modulates the generation of allergic inflammatory mediators in activated mast cells. To understand the biological activity of britanin, the authors investigated its effects on the generation of prostaglandin D2 (PGD2), leukotriene C4 (LTC4), and degranulation in IgE/Ag-induced bone marrow-derived mast cells (BMMCs). Britanin dose dependently inhibited degranulation and the generations of PGD2 and LTC4 in BMMCs. Biochemical analyses of IgE/Ag-mediated signaling pathways demonstrated that britanin suppressed the phosphorylation of Syk kinase and multiple downstream signaling processes, including phospholipase Cgamma1 (PLCgamma1)-mediated calcium influx, the activation of mitogen-activated protein kinases (MAPKs; extracellular signal-regulated kinase 1/2, c-Jun NH2-terminal kinase and p38), and the nuclear factor-kappaB (NF-kappaB) pathway. Taken together, the findings of this study suggest britanin suppresses degranulation and eicosanoid generation by inhibiting the Syk-dependent pathway and britanin might be useful for the treatment of allergic inflammatory diseases.

Effect of Different Amount of Dietary n-3 PUFA on Colon Carcinogenesis in DMH-treated Rats

The objective of the study was to observe the effect of n-3 PUFA on cell proliferation and apoptosis by determining mRNA and protein of COX-2 and eicosanoid product and the mRNA and protein of Bu and Bcl-2 related to apoptosis in colon carcinogenesis of 1,2- dimethylhydrazine (DMH)-treated rats. Ninety male Sprague Dawley rats weighing about 170g were divided into 3 groups, control and n-3 PUFA supplemented groups (FO group: 6.2 mmoles n-3 PUFA; 2FO group: 12.4 mmoles n-3 PUFA) and fed experimental diet for 14 weeks. All rats were intramuscularly injected with DMH 15 mg/kg twice a week for 6 weeks to deliver total dose of 180 mg/kg body weight. Compared with the control group, 6.2 mmoles n-3 PUFA significantly reduced the levels of mRNA and protein expression of COX-2 and 2-series eicosanoids (TXB2 and PGE2 and decreased cell proliferation in colonic mucosa. However, high levels of n-3 PUFA supplementation significantly increased the levels of mRNA and protein expression of COX-2, TXB2 and PGE2. and increased cell proliferation which was similar level to that of control group. Compared with the control group, n-3 PUFA, regardless of the amount, significantly increased apoptotic index in colonic mucosa. Western blot and RT-PCR analyses showed that the levels of mRNA and protein expression of Bax were significantly increased by 6.2 mmoles n-3 PUFA, but decreased by 12.4 mmoles n-3 PUFA. The analyses also showed the levels of mRNA and protein expression of Bcl-2 were significantly reduced by 6.2 mmoles n-3 PUFA, but increased by 12.4 mmoles n-3 PUFA. The ratio of Bcl-2/Bax in mRNA and protein was significantly reduced by 6.2 mmoles n-3 PUFA but increased by 12.4 mmoles n-3 PUFA. Overall, these results indicate that n-3 PUFA could be effective in preventing colon carcinogenesis by reducing cell proliferation with lower level of COX-2 and 2-series eicosanoid, and increasing apoptosis by inducing pro-apoptotic gene, Bax and inhibiting anti-apoptotic gene, Bcl-2 in the colonic mucosa of DMH-treated rats. However, high level of n-3 PUFA supplementation could stimulate colon carcinogenesis by increasing cell proliferation and inhibiting apoptosis.

Effect of Dietary CLA Isomers on Apoptosis and Cell Proliferation in Colonic Mucosa of DMH-Treated Rats

The study was designed to compare the anti-carcinogenic effect of conjugated linoleic acid (CLA) isomers on colon carcinogenesis in 1,2-dimethylhydrazine (DMH)-treated rats by determining the levels of apoptosis, cell proliferation, eicosanoids and 1,2-diacylglycerol (DAG) in colonic mucosa. Sixty male Sprague Dawley rats were randomly divided into 3 groups depending on the types of CLA isomers, i.e. BT group (no CLA contained), CLA-C group (cis-9, trans11 isomer contained), and CLA- T group (trans-10, cis-12 isomer contained). The experimental diet was composed of protein at 20%, carbohydrate at 56.2%, and fat at 14.5% including 0.8% CLA isomers by weight. The experimental diet was fed for 14 weeks with the initiation of intramuscular injection of DMH, which was injected twice a week for 6 weeks to give total dose of l80mg per kg body weight. Two CLA isomers (c9t11 and t10c12) significantly increased the relative percentage of apoptosis but reduced cell proliferation in mucosal cell and also the levels of PGE2, TXB2, and DAG in colonic mucosa. However, there was no significant differences in anti-carcinogenic effect between c9t11 isomer and t10c12 isomer. Overall, colon carcinogenesis could be significantly inhibited by CLA isomers by increasing apoptosis and reducing cell proliferation, the levels of eicosanoids and DAG in colonic mucosa.

Effects of Cyclooxygenase and Lipoxygenase Inhibitors on the Proliferation of Colon Cancer Cells and Their Production of Eicosanoids / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Epidemiological and laboratory studies suggest that nonsteroidal antiinflammatory drugs (NSAIDs) reduce the risk of colon cancer and that the inhibition of colon cancer is mediated through modulation of eicosanoid production. The present study examined the effect of cyclooxygenase (COX) and lipoxygenase (LOX) inhibitors on colon cancer cell growth and prostaglandin E(2) (PGE(2)) or leukotriene B(4) (LTB(4)) secretion by these cells. MATERIALS AND METHODS: The human colon adenocarcinoma cell lines, Caco-2 and HT-29 cells, were cultured in serum-free medium with various concentrations of indomethacin, piroxicam or esculetin in the presence of 0.15nM or 10nM linoleic acid. Cell number was estimated by MTT assay and PGE(2) and LTB(4) were analyzed by enzyme immunoassay. RESULTS: The NSAIDs inhibited cell proliferation in a concentration-dependent manner. However, the potency and efficacy of each drug varied in the two cell lines. In Caco-2 cells, the effect of esculetin was higher than that of indomethacin, and piroxicam had no effect. In HT-29 cells, only indomethacin significantly inhibited cell proliferation. All three agents inhibited PGE(2) secretion in a dose-dependent manner; the effect of indomethacin was highest and that of esculetin lowest. The secretion of LTB4 was increased by indomethacin and piroxicam but decreased by esculetin. The effects of these drugs on cell proliferation and eicosanoid secretion were not influenced by linoleic acid concentrations in the culture media. Neither exogenous PGE2 nor LTB4 affected cell proliferation. The results of Pearson correlation analyses revealed that changes in cell proliferation were somewhat related to both concentrations of NSAIDs in the culture medium and production of PGE(2) and LTB(4). CONCLUSION: The present data suggests that the anti-proliferative effect of NSAIDs may not be entirely attributed to changes in the production of PGE2 and/or LTB4 in the two colon cancer cell lines. These NSAIDs may inhibit cell proliferation largely independent of their ability to modulate eicosanoid synthesis.

The Signaling Pathway of G-protein Rac and Eicosanoid Synthesis by Titanium Particles / 대한정형외과학회잡지

PURPOSE: In order to understand the intracellular signaling pathway involving the c-fos gene expression that is caused by Titanium-particles, we analyzed the involvement of Rac, cytosolic phospholipase A2, and eicosanoids (e.g. leukotriene B4 and prostaglandin E2) as well as c-fos. MATERIALS AND METHODS: We tested whether or not Titanium-particles activate a c-fos serum response element in Rat-2 fibroblasts. To measure the activity of the c-fos serum response element, we analyzed the serum response element using a luciferase reporter system. The luciferase activity was measured using a scintillation spectrophotometer. Next, we analyzed the involvement of Rac and the eicosanoid synthesis mechanisms which are downstream mediators of Rac in the c-fos serum response element activation cascade. RESULTS: Titanium-particles cause an activation of the c-fos serum response element and this activation was selectively repressed by RacN17 and by pretreatment of the inhibitors of cytosolic phospholipase A2, cyclooxygenase or 5-lipoxygenase. Eicosanoid synthesis was increased in a Rac-dependent manner in response to the presence of Titanium- particles. CONCLUSION: 'Rac, a member of G-protein, which is involved in the eicosanoid synthesis' may play a critical role in the Titanium-induced signaling cascade. Thus, we speculated that the 'Rac-cytosolic phospholipase A2-eicosanoids-c-fos cascade' may be a possible mechanism that produces eicosanoid synthesis caused by Titanium-particles in the periprosthetic osteolytic process.

Changes in the Levels of Eicosanoids and Isoprostane (8-iso-PGF2alpha) in the Newborn Rat Brain after Hypoxic-Ischemic Injury

PURPOSE: The changes in the levels of eicosanoids and isoprostane (8-iso-PGF2alpha) were investigated in brain tissue of 7 day-old rats after hypoxic-ischemic (HI) injury. METHODS: The 7 day-old newborn rats underwent right unilateral common carotid artery ligation followed by exposure to hypoxia with 8% oxygen for 150 minutes. There after, the pups were decapitated during reoxygenation 21% period of 0, 1, 6, 24, and 72 hours and their cerebral hemisheres were dissected through sagittal plane. Ipsilateral and contralateral cerebral hemesheres to common carotid artery ligation were used to determine the water content for estimation of severity of brain edema (n=5) and to measure the levels of eicosanoid and isoprostane (n=7). The levels of 6-keto-PGF1alpha, TXB2, and PGE2 were measured by RP-HPLC (reversed-phase high-performance liquid chromatography) and the levels of isoprostane (8-iso-PGF2alpha) were measured by enzyme immunoassay. The changes of eicosanoid and isoprostane levels during reoxygenation period were observed and comparisons between ipsilateral and contralateral hemispheres were done. RESULTS: The edema of ipsilateral cerebral hemesheres to common carotid artery ligation was more severe than that of contralateral cerebral hemisheres (P<0.05). The levels of 6-keto-PGF1alpha, TXB2, and PGE2 were found to increase during the early period of reoxygenation after HI insult, peak at 1 hour, and then decrease to the control levels at 72 hour (P<0.05). But, the levels of 8-iso-PGF2alpha did not significantly increase during the period of reoxygenation. The levels of 6-keto-PGF1alpha, TXB2, and PGE2 of ipsilateral hemispheres had a tendency to be higher than those of contralateral hemispheres during the initial 6 hour reoxygenation period, but the levels of 8-iso-PGF2alpha of ipsilateral hemispheres were significantly higher than those of contralateral hemispheres during the relatively later reoxygenation period (P<0.05). CONCLUSION: Reoxygenation after hypoxic-ischemic injury increased the levels of 6-keto-PGF1alpha, TXB2, and PGE2 in 7 day-old rat brain during the early period of reoxygenation, but the levels of isoprostane (8-iso-PGF2alpha) were not significantly increased during the reoxygenation period after HI injury.

Simultaneous HPLC analysis of arachidonic acid metabolites in biological samples with simple solid phase extraction

A reversed-phase high-performance liquid chromatography (RP-HPLC) has been developed to analyze the metabolites of arachidonic acid based on the specificities of ultraviolet absorption of these various metabolites and is sensitive to the nanogram level. This procedure makes it possible to extract complex mixtures of eicosanoids efficiently with a single step and to analyze them simultaneously by RP-HPLC from biological samples using octadesylsilyl silica extraction column and PGB2 as an internal standard. The cyclooxygenase, products (prostaglandin (PG)D2, PGE1, PGE2, PGF1alpha, PGF2alpha, 6-keto-PGF1alpha, and thromboxane B2 (TXB2)) and lipid peroxidation product, isoprostanes, of arachidonic acid were monitored by one isocratic HPLC system at 195 nm wavelength. The lipoxygenase products (leukotriene(LT)B4, LTC4, LTD4, and 5-hydroxyeicosatetraenoic acid (5-HETE), 12-HETE, 15-HETE) were measured by another isocratic HPLC system at 280 nm for LTs and 235 nm for HETEs. This method provides a simple and reliable way to extract and assess quantitatively the final arachidonic acid metabolites.