Epoxyeicosatrienoic Acids and Fibrosis: Recent Insights for the Novel Therapeutic Strategies.

Organ fibrosis often ends in eventual organ failure and leads to high mortality. Although researchers have identified many effector cells and molecular pathways, there are few effective therapies for fibrosis to date and the underlying mechanism needs to be examined and defined further. Epoxyeicosatrienoic acids (EETs) are endogenous lipid metabolites of arachidonic acid (ARA) synthesized by cytochrome P450 (CYP) epoxygenases. EETs are rapidly metabolized primarily via the soluble epoxide hydrolase (sEH) pathway. The sEH pathway produces dihydroxyeicosatrienoic acids (DHETs), which have lower activity. Stabilized or increased EETs levels exert several protective effects, including pro-angiogenesis, anti-inflammation, anti-apoptosis, and anti-senescence. Currently, intensive investigations are being carried out on their anti-fibrotic effects in the kidney, heart, lung, and liver. The present review provides an update on how the stabilized or increased production of EETs is a reasonable theoretical basis for fibrosis treatment.

Epoxyeicosatrienoic acids: Emerging therapeutic agents for central post-stroke pain.

Central post-stroke pain (CPSP) is chronic neuropathic pain due to a lesion or dysfunction of the central nervous system following cerebrovascular insult. This syndrome is characterized by chronic somatosensory abnormalities including spontaneous pain, hyperalgesia and allodynia, which localize to body areas corresponding to the injured brain region. However, despite its potential to impair activities of daily life and cause mood disorders after stroke, it is probably the least recognized complication of stroke. All currently approved treatments for CPSP have limited efficacy but troublesome side effects. The detailed mechanism underlying CPSP is still under investigation; however, its diverse clinical features indicate excessive central neuronal excitability, which is attributed to loss of inhibition and excessive neuroinflammation. Recently, exogenous epoxyeicosatrienoic acids (EETs) have been used to attenuate the mechanical allodynia in CPSP rats and proven to provide a quicker onset and superior pain relief compared to the current first line drug gabapentin. This anti-nociceptive effect is mediated by reserving the normal thalamic inhibition state through neurosteroid-GABA signaling. Moreover, mounting evidence has revealed that EETs exert anti-inflammatory effects by inhibiting the expression of vascular adhesion molecules, activating NFκB, inflammatory cytokines secretion and COX-2 gene induction. The present review focuses on the extensive evidence supporting the potential of EETs to be a multi-functional therapeutic approach for CPSP. Additionally, the role of EETs in the crosstalk between anti-CPSP and the comorbid mood disorder is reviewed herein.

[Investigation on silymarin impact on lipopolysaccharide induced inflammation model based on arachidonic acid metabolism pathway].

The objective of this research is to investigate the suppressive effect of silymarin on vitro cell culture model of inflammatory macrophage RAW264.7 induced by Kdo2-Lipid A, and explore its mechanism based on cell metabonomics. Ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was used in the cell metabonomic assay to quantitative analysis of metabolites related to eicosanoids pathway. Then chemometric approaches such as principal component analysis were used to process the metabolic data. Within the established method, a total of 59 eicosanoids standards (containing 15 deuterated internal standards) were simultaneously separated in a single 5 min run, and the analytical method is proved to be rapid, sensitive and accurate. Whereafter, the metabolites with VIP> 1 and P value< 0.05 were considered as biomarkers. 12-OxoLeukotriene B4 (12-OxoLTB4) was eventually identified as metabolic biomarkers of silymarin treatment group in this research, and according to the related inflammatory pathways, we speculated silymarin has anti-inflammatory activities by inhibiting the 5-lipoxygenase (5-LOX) activity and blocking lipid peroxidation in 5-LOX metabolic pathways to reduce the formation of peroxides and oxygen free radicals. This study provide a novel approach to the mechanism research on the silymarin treatment on RAW264.7 cells based on cell metabonomics.

N-Acyl ethanolamide and eicosanoid involvement in irritant dermatitis.

BACKGROUND: Sodium lauryl sulfate (SLS) and ultraviolet radiation (UVR) are two commonly encountered cutaneous inflammatory stimuli. Differing histopathological and clinical features implicate involvement of alternative inflammatory pathways; bioactive lipid mediators (eicosanoids, endocannabinoids and sphingolipids) are likely candidates for regulation of the divergent inflammatory responses. OBJECTIVES: To assess comprehensively bioactive lipid involvement in SLS- and UVR-induced inflammatory responses, to provide a better understanding of bioactive lipid mediator pathways in irritant inflammation. METHODS: Buttock skin from 10 healthy volunteers was treated with two minimal erythema doses of UVR (275-380 nm, peak 305 nm) or an SLS dose optimized for each individual, to produce a comparable, moderate erythema. Punch biopsies were taken 24 h postchallenge and from untreated skin, and separated into dermis and epidermis. Lipids [including 15 prostanoids, 15 hydroxy fatty acids (HFAs), nine endocannabinoids and related N-acyl ethanolamides (NAE), and 21 sphingolipids] were extracted and quantified using liquid chromatography-tandem mass spectrometry. RESULTS: Increased epidermal NAE and HFA expression was observed in response to SLS but not UVR-induced low-level inflammation. Significant changes following SLS treatment included augmented levels of NAE, possessing proinflammatory and some reported anti-inflammatory properties, with 3·7-fold (P = 0·02) and threefold (P = 0·01) increased expression of palmitoyl and stearoyl ethanolamides, respectively, in addition to 1·9-fold (P = 0·02) increased expression of 12-hydroxyeicosatetraenoic acid. CONCLUSIONS: The differential bioactive lipid upregulation implicates their involvement in skin irritant responses, potentially reflecting roles in inflammatory cell recruitment and subsequent resolution of inflammation, giving scope for new treatment approaches to irritant dermatitis.

Eicosanoid regulation of pulmonary innate immunity post-hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is a therapeutic option for a number of malignant and inherited disorders. However, the efficacy of this therapy is limited by a number of serious infectious and noninfectious complications. Pulmonary infections represent a significant cause of morbidity and mortality post-HSCT and can occur both pre- and post-hematopoietic reconstitution. Susceptibility to Gram-negative bacterial infections despite full hematopoietic engraftment suggests that innate immunity remains impaired months to years post-HSCT. This review will describe the process and complications of HSCT and will summarize what is known about innate immune reconstitution post-HSCT. Data from the literature as well as our own laboratory will be presented to suggest that an eicosanoid imbalance characterized by over-production of prostaglandins and under-production of leukotrienes leads to impaired lung phagocyte function post-HSCT. Of therapeutic interest, strategies which limit production of prostaglandins can improve pulmonary host defense in animal HSCT models, which suggests that this may also be beneficial for human HSCT recipients.

Effects of ghrelin on anorexia in tumor-bearing mice with eicosanoid-related cachexia.

Ghrelin is a novel brain-gut peptide that stimulates food intake and may secondarily increase body weight via a growth hormone secretagogue receptor (GHS-R). Tumor-bearing mice (MCG101), characterized by anorexia, fat loss and muscle wasting due to increased concentration of PGE2 and proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha), were provided ghrelin i.p. at a low (20 microg/day) and high dose (40 microg/day) to examine the ability of ghrelin to counteract tumor-induced anorexia. Immunohistochemical staining and Western blot analyses were used to identify GHS-R expression in the brain as well as its relationship to NPY expression in hypothalamic neurons. GHS-R mRNA in hypothalamus and ghrelin mRNA in gastric fundus were quantified by RT-PCR. Body composition was determined by carcass extractions. GHS-R expression in hypothalamus and plasma ghrelin levels were significantly increased in freely-fed tumor-bearing mice, while gastric fundus expression of ghrelin was unaltered compared to non-tumor-bearing mice (controls). Ghrelin treatment increased food intake, body weight and whole body fat at both low and high doses of ghrelin in normal controls, while tumor-bearing mice showed improved intake and body composition at the high dose of ghrelin only. Exogenous ghrelin normalized the GHS-R expression in hypothalamus from tumor-bearing mice without alterations in the gastric fundus expression of ghrelin. Tumor growth was not altered by exogenous ghrelin. Our results indicate that MCG 101-bearing mice became ghrelin resistant despite upregulation of hypothalamic GHS-R expression, which confirms similar indirect observations in cancer patients. Thus, other factors downstream of the ghrelin-GHS-R system appear to be more important than ghrelin to explain cancer-induced anorexia.

Enteral nutrition in Crohn's disease: fat in the formula.

Enteral nutrition is effective in inducing remission in active Crohn's disease. Speculation on the underlying mechanism of action has moved away from the presentation of nitrogen and towards the fat content of the various enteral feeds. Evidence is accumulating that additional long-chain triglyceride in such feeds impairs the response rate in active Crohn's disease, whereas no deleterious effects of additional medium-chain triglyceride have been identified. It has been proposed that long-chain triglycerides composed from n-6 fatty acids may be the most harmful, since such fatty acids are substrates for inflammatory eicosanoid production. However, recent studies comparing different enteral feeds are not consistent in identifying which additional fatty acids impair response rates to the greatest extent. Despite meta-analyses concluding that polymeric diets (typically containing large amounts of fat) are as effective as elemental diets, it would seem sensible to use enteral feeds with minimal fat content when treating active Crohn's disease.

Endothelin-1--induced enhancement of coronary smooth muscle contraction via MAPK-dependent and MAPK-independent [Ca(2+)](i) sensitization pathways.

Endothelin-1 (ET-1) has been implicated in coronary vasospasm by enhancing coronary vasoconstriction to vasoactive eicosanoids, and a role for protein kinase C (PKC) activation has been suggested. However, the cellular mechanisms downstream from PKC activation are unclear. We investigated whether physiological concentrations of ET-1 enhance coronary smooth muscle contraction by activating a PKC-mediated signaling pathway involving tyrosine phosphorylation and activation of mitogen-activated protein kinase (MAPK). Cell contraction was measured in smooth muscle cells isolated from porcine coronary artery, [Ca(2+)](i) was measured in fura-2 loaded cells, and tissue fractions were examined for reactivity with anti-phosphotyrosine (P-Tyr) and anti-MAPK antibodies using immunoprecipitation and immunoblot analysis. In Hanks' solution (1 mmol/L Ca(2+)), ET-1 (10 pmol/L) did not increase basal [Ca(2+)](i) (81 +/- 2 nmol/L) but caused cell contraction (10%) that was inhibited by calphostin C (10(-6) mol/L), inhibitor of PKC, tyrphostin (10(-6) mol/L), inhibitor of tyrosine kinase, and PD098059 (10(-6) mol/L), inhibitor of MAPK kinase. The vasoactive eicosanoid prostaglandin F(2alpha) (PGF(2alpha); 10(-7) mol/L) caused increases in cell contraction (11%) and [Ca(2+)](i) (122 +/- 9 nmol/L) that were inhibited by the Ca(2+) channel blocker verapamil (10(-6) mol/L) but not by calphostin C, tyrphostin, or PD098059. Pretreatment with ET-1 for 10 minutes enhanced cell contraction to PGF(2alpha) (33%) with no additional increase in [Ca(2+)](i) (124 +/- 10 nmol/L). Activation of PKC by phorbol 12-myristate 13-acetate (PMA; 10(-7) mol/L) caused cell contraction and enhanced PGF(2alpha) contraction (32%) with no additional increase in [Ca(2+)](i) (126 +/- 9 nmol/L). The ET-1-- and PMA-induced enhancement of PGF(2alpha) contraction was abolished by verapamil or calphostin C but not by tyrphostin or PD098059. ET-1 and PMA caused significant increases in tyrosine phosphorylation of MAPK that were inhibited by calphostin C, tyrphostin, and PD098059. PGF(2alpha) did not cause any additional increases in tyrosine phosphorylation of MAPK in tissues untreated or pretreated with ET-1 or PMA. Thus, physiological concentrations of ET-1 activate a Ca(2+)-independent PKC-mediated signaling pathway that involves tyrosine phosphorylation and activation of MAPK. The enhancement of PGF(2alpha)-induced coronary smooth muscle contraction by ET-1 involves additional activation of a Ca(2+)-sensitive PKC-mediated pathway but not tyrosine phosphorylation or activation of MAPK. The MAPK-dependent and MAPK-independent signaling pathways represent possible cellular mechanisms by which ET-1 could enhance coronary vasoconstriction to vasoactive eicosanoids in coronary vasospasm.

Sepsis: citoquinas, radicales libres y óxido nítrico / Sepsis: cytokine, free radicals and nitric oxide

La sepsis y sus complicaciones, el shock séptico y el síndrome de disfunción orgánica múltiple (MODS - multiple organ dysfunction syndrome) mantienen desde hace años el triste privilegio de ser las primeras causas de muerte en las salas de terapia intensiva y postquirúrgica; el aumento de su incidencia está en relación con el desarrollo de procedimientos más invasivos, los tratamientos inmunosupresores, la quimioterapia, la mayor edad de los enfermos, los síndromes de inmunodeficiencia y las floras hospitalarias multirresistentes. Se estima en 400.000 el número de pacientes afectados anualmente en los Estados Unidos y, a pesar de sofisticados y extremadamente caros procedimientos de sostén vital y de los antibióticos, la mortalidad no ha disminuido en los últimos años. Probablemente, esta detención en el progreso terapéutico, se deba a la extrema complejidad de los mecanismos patogénicos en juego y a lo incompleto de su conocimiento y comprensión. El problema de las infecciones graves y de la sepsis (del griego putrefacción), es antiguo y acompaña al hombre desde sus orígenes remotos, como ejemplo de lo cual, basta recordar la peste, la fiebre tifoidea, la gangrena, la peritonitis y las infecciones puerperales. En realidad se trata de un enfrentamiento ancestral entre bacterias y organismos superiores, en el que, desafortunadamente, a menudo triunfan las primeras

Sepsis: citoquinas, radicales libres y óxido nítrico / Sepsis: cytokine, free radicals and nitric oxide

La sepsis y sus complicaciones, el shock séptico y el síndrome de disfunción orgánica múltiple (MODS - multiple organ dysfunction syndrome) mantienen desde hace años el triste privilegio de ser las primeras causas de muerte en las salas de terapia intensiva y postquirúrgica; el aumento de su incidencia está en relación con el desarrollo de procedimientos más invasivos, los tratamientos inmunosupresores, la quimioterapia, la mayor edad de los enfermos, los síndromes de inmunodeficiencia y las floras hospitalarias multirresistentes. Se estima en 400.000 el número de pacientes afectados anualmente en los Estados Unidos y, a pesar de sofisticados y extremadamente caros procedimientos de sostén vital y de los antibióticos, la mortalidad no ha disminuido en los últimos años. Probablemente, esta detención en el progreso terapéutico, se deba a la extrema complejidad de los mecanismos patogénicos en juego y a lo incompleto de su conocimiento y comprensión. El problema de las infecciones graves y de la sepsis (del griego putrefacción), es antiguo y acompaña al hombre desde sus orígenes remotos, como ejemplo de lo cual, basta recordar la peste, la fiebre tifoidea, la gangrena, la peritonitis y las infecciones puerperales. En realidad se trata de un enfrentamiento ancestral entre bacterias y organismos superiores, en el que, desafortunadamente, a menudo triunfan las primeras (AU)