Requirement of JNK-Mediated Phosphorylation for Translocation of Group IVA Phospholipase A2 to Phagosomes in Human Macrophages

Producción CientíficaEicosanoids are a broad family of lipids that play a critical role in host defense against bacterial and fungal infections. The first enzyme in the metabolic pathway for the generation of eicosanoids is group IVA phospholipase A(2), also known as cytosolic phospholipase A(2)alpha (cPLA(2)alpha). During phagocytosis, cPLA(2)alpha has been found to translocate to the phagosome, although the molecular mechanism involved in such a translocation has not been elucidated. By using enhanced GFP-tagged proteins we show in this work that a nonphosphorylatable cPLA(2)alpha mutant (S505A) does not translocate to the phagosomes, but a mutant that mimics phosphorylation on Ser(505) (S505E) does it so readily. During phagocytosis, endogenous cPLA(2)alpha is phosphorylated at Ser(505), and inhibitors of JNK, but not of other related kinases such as p38 or the extracellular-regulated kinases 1 and 2, completely block such a phosphorylation. Inhibition of JNK activity also inhibits the translocation of cPLA(2)alpha to phagosomal membranes, as well as arachidonic acid release to the extracellular medium. Moreover, the S505E mutant makes the enzyme refractory to JNK inhibition, translocating normally to phagosomal membranes. Collectively, these data support a key role for JNK-mediated cPLA(2)alpha phosphorylation at Ser(505) in the sequence of events leading to translocation and activation of the enzyme to phagosomal membranes in human macrophage

Lipin-1 integrates lipid synthesis with proinflammatory responses during TLR activation in macrophages

Lipin-1 is a Mg2+-dependent phosphatidic acid phosphatase involved in the de novo synthesis of phospholipids and triglycerides. Using macrophages from lipin-1-deficient animals and human macrophages deficient in the enzyme, we show in this work that this phosphatase acts as a proinflammatory mediator during TLR signaling and during the development of in vivo inflammatory processes. After TLR4 stimulation lipin-1-deficient macrophages showed a decreased production of diacylglycerol and activation of MAPKs and AP-1. Consequently, the generation of proinflammatory cytokines like IL-6, IL-12, IL-23, or enzymes like inducible NO synthase and cyclooxygenase 2, was reduced. In addition, animals lacking lipin-1 had a faster recovery from endotoxin administration concomitant with a reduced production of harmful molecules in spleen and liver. These findings demonstrate an unanticipated role for lipin-1 as a mediator of macrophage proinflammatory activation and support a critical link between lipid biosynthesis and systemic inflammatory responses.This work was supported by the Spanish Ministry of Science and Innovation (Grants SAF2007-60055, SAF2010-18831, and BFU2010-18826) and the Regional Government of Castile and Leon (Grants BIO39/VA04/10 and CSI168A12-1). L.P. and G.L. were supported by predoctoral fellowships from the Spanish Ministry of Science and Innovation (Plan de Formación de Personal Investigador and Plan de Formación de Profesorado Universitario programs). M.V. was supported by a predoctoral fellowship from the Regional Government of Castile and Leon. E.E. was supported by a predoctoral fellowship from the Spanish National Research Council (Junta de Ampliación de Estudios Program). C.G. was supported by a predoctoral fellowship from the University of Valladolid.Peer Reviewe

Lipin-2 reduces proinflammatory signaling induced by saturated fatty acids in macrophages

Lipin-2 is a member of the lipin family of enzymes, which are key effectors in the biosynthesis of lipids. Mutations in the humanlipin-2 gene are associated with inflammatory-based disorders; however, the role of lipin-2 in cells of the immune system remains obscure. In this study, we have investigated the role of lipin-2 in the proinflammatory action of saturated fatty acids in murine and human macrophages. Depletion of lipin-2 promotes the increased expression of the proinflammatory genes Il6, Ccl2, and Tnfα, which depends on the overstimulation of the JNK1/c-Jun pathway by saturated fatty acids. In contrast, overexpression of lipin-2 reduces the release of proinflammatory factors. Metabolically, the absence of lipin-2 reduces the cellular content of triacylglycerol in saturated fatty acid-overloaded macrophages. Collectively, these studies demonstrate a protective role for lipin-2 in proinflammatory signaling mediated by saturated fatty acids that occurs concomitant with an enhanced cellular capacity for triacylglycerol synthesis. The data provide new insights into the role of lipin-2 in human and murine macrophage biology and may open new avenues for controlling the fatty acid-related low grade inflammation that constitutes the sine qua non of obesity and associated metabolic disorders. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.This work was supported in part by Spanish Ministry of Science and Innovation Grants SAF2010-18831 and BFU2010-18826 and Regional Government of Castile and Leon Grant BIO39/VA04/10. Supported by a predoctoral fellowship from the Regional Government of Castile and Leon, Spain. Supported by a predoctoral fellowship from the Spanish National Research Council (Junta de Ampliación de Estudios Program). Supported by a predoctoral fellowship from the Spanish Ministry of Science and Innovation.Peer Reviewe

Epidemiology of the Microsporidium Nosema ceranae in Four Mediterranean Countries

Nosema ceranae is a highly prevalent intracellular parasite of honey bees’ midgut worldwide. This Microsporidium was monitored during a long-term study to evaluate the infection at apiary and intra-colony levels in six apiaries in four Mediterranean countries (France, Israel, Portugal, and Spain). Parameters on colony strength, honey production, beekeeping management, and climate were also recorded. Except for São Miguel (Azores, Portugal), all apiaries were positive for N. ceranae, with the lowest prevalence in mainland France and the highest intra-colony infection in Israel. A negative correlation between intra-colony infection and colony strength was observed in Spain and mainland Portugal. In these two apiaries, the queen replacement also influenced the infection levels. The highest colony losses occurred in mainland France and Spain, although they did not correlate with the Nosema infection levels, as parasitism was low in France and high in Spain. These results suggest that both the effects and the level of N. ceranae infection depends on location and beekeeping conditions. Further studies on host-parasite coevolution, and perhaps the interactions with other pathogens and the role of honey bee genetics, could assist in understanding the difference between nosemosis disease and infection, to develop appropriate strategies for its control

Creación de la Historioteca Veterinaria: píldoras de conocimiento sobre historia de la veterinaria

Proyecto de Innovación Educativo 341 curso 20-21 Creación de la Historioteca Veterinaria: píldoras de conocimiento sobre historia de la veterinaria

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Lipin-1 is essential for the inflammatory response of murine macrophages to bacterial lipopolysaccharide

Resumen del póster presentado al Fourth European Workshop on Lipid Mediators celebrado en Paris (Francia) del 27 al 28 de septiembre de 2012.Lipin-1 is a member of the phosphatidic acid phosphatases family of enzymes (PAP-1), which dephosphorylates phosphatidic acid (PA) to generate diacylglycerol (DAG). Mice lacking Lipin1, named fld (fatty liver dystrophy) are known to exhibit changes in lipid storage but up to date, there are no studies about lipid alterations in the macrophages of these animals. TLR4-stimulation of bone marrow derived macrophages from wt mice resulted in an increase of the total content of DAG at 5 min, reaching a maximum at 20 min, however in fld cells DAG levels were significantly lower. Despite this difference, the fatty acid composition of DAG for both groups was the same, with saturated fatty acids like myristic (14:0), palmitic (16:0) and stearic (18:0) being the major constituents. After exposure to LPS, PA levels increased in wt cells reaching the plateau at 10 min, but this was decreased in fld cells. In both cases, there were no differences in the PA profile. The following PA species were found by using LC/MS: PA(16:0/18:2), PA(16:0/18:1), PA(16:0/18:0), PA(O-18:0/18:2), PA(O-18:0/18:1), PA(O-18:0/18:0), PA (18:0/18:1) and PA (18:0/18:0). Because both DAG and PA have essential signaling roles in macrophage function, we studied the signaling consequences of the lack of lipin-1 during LPS stimulation. Activation of the ERKs p42/p44 and JNK was diminished in fld macrophages, as also was the activation of the transcription factors NFκB and AP-1. We also found differences in the relative mRNA expression of some important cytokines such as Il6, Il12p40 and proinflammatory enzymes such as Nos2 and Cox2. All together, these results suggest a proinflammatory role for lipin-1 that is due to the generation of signaling lipids.Peer reviewe

Stimulated occurrence and biological activity of palmitoleic acid and its isomers in metabolic diseases

Resumen del trabajo presentado presentado al CIBERDEM Annual Meeting, celebrado en Cerdanyola del Vallès, Barcelona (España) del 11 al 13 de mayo de 2016.Atherosclerosis, a major cause for cardiovascular disease, can be initiated by the increased activation of endothelial cells lining the inside of the blood vessels. This activation may obey to multiple causes, such as diabetes or hyperlipidemia, and results in the endothelial cells releasing a variety of products with inflammatory potential that may attract monocytes and favor their infiltration into the subendothelial space. We have recently shown that human monocytes respond to free arachidonic acid, a well-defined secretory product of activated endothelial cells, by activating the de novo pathway of fatty acid biosynthesis, resulting in the formation of neutral lipids and the acquisition of a foamy phenotye due to the accumulation of cytoplasmic lipid droplets. In this work we describe that the neutral lipids of foamy monocytes are selectively enriched in a rather uncommon fatty acid, cis-7-hexadecenoic acid (16:n-9), a positional isomer of the more frequently described palmitoleic acid, which is strikingly absent from lipid droplets. Experiments addressing the biological role for 16:1n-9 indicate that this fatty acid prevents the inflammatory response of human monocytes and murine macrophages to bacterial lipopolysaccharide both in vitro and in vivo. Collectively, our results provide evidence that a previously unrecognized fatty acid, 16:1n-9, possesses anti-inflammatory activity that is comparable to that of omega-3 fatty acids and is clearly distinguishable from the effects of palmitoleic acid. Moreover, the selective accumulation in the neutral lipids of phagocytic cells of a rather uncommon fatty acid, reveals an early phenotypic change that may provide a biomarker of proatherogenicity, and a potential target for intervention in the early stages of cardiovascular disease.Peer reviewe