Nuclear Lipid Signaling: Novel Role of Eicosanoids

Lymphocyte GH-axis hormones in immunity

The production and utilization of common ligands and their receptors by cells of the immune and neuroendocrine systems constitutes a biochemical information circuit between and within the immune and neuroendocrine systems. The sharing of ligands and receptors allows the immune system to serve as the sixth sense notifying the nervous system of the presence of foreign entities. Within this framework, it is also clear that immune cell functions can be altered by neuroendocrine hormones and that cells of the immune system have the ability to produce neuroendocrine hormones. This review summarizes a part of this knowledge with particular emphasis on growth hormone (GH). The past two decades have uncovered a lot of detail about the actions of GH, acting through its receptor, at the molecular and cellular level and its influence on the immune system. The production and action of immune cell-derived GH is less well developed although its important role in immunity is also slowly emerging. Here we discuss the production of GH, GH-releasing hormone (GHRH) and insulin-like growth factor-1 (IGF-1) and their cognate receptors on cells of the immune system and their influence via endocrine/autocrine/paracrine and intracrine pathways on immune function. The intracellular mechanisms of action of immune cell-derived GH are still largely unexplored, and it is anticipated that further work in this particular area will establish an important role for this source of GH in normal physiology and in pathologic situations.

Hypercytolipidemia-induced nuclear lipoapoptosis: cytochemical analysis and integrated review of hypogonadal, diabetes-obesity syndrome-induced female reproductive axis disruption

Expression of the diabetes (db/db) mutation (i.e., leptin receptor defect) in C57BL/KsJ mice results in the functional suppression of the female pituitary-gonadal axis accompanied by premature utero-ovarian lipocytoatrophy. The current studies define the cytostructural, metabolic and endocrine disturbances associated with hypercytolipidemia and coincident nuclear lipoapoptosis following expression of the db/db-mutation. Adult, female C57BL/KsJ control (+/+ and +/? genotypes) and db/db mutant littermates were monitored for systemic alterations in blood glucose, insulin, luteinizing hormone (LH) and 17-B-estradiol (E2) concentrations associated with db/db-enhanced cytolipid depositions and TUNEL-labeled 3'-DNA fragmentation indexed nuclear lipoapoptosis. Obesity, hyperglycemia and hyperinsulinemia, in addition to depressed LH and E2 concentrations, characterized all db/db-mutants relative to control indices. Structural and cytochemical analysis of basophilic gonadotroph cells, ovarian follicular granulosa cells and uterine endometrial epithelial layers indicated that db/db mutants demonstrated prominent hypercytolipidemia relative to control cytoarchitecture profiles. Vasolipidemia and interstitial cytoadiposity were prominent in all db/db tissue compartments. In each affected cell type within the db/db pituitary-reproductive tract axis, hypercytolipidemia was localized with pronounced nuclear lipo-infiltration and 3'-DNA TUNEL-labeled fragmentation. These data indicate that coincident cytostructural, endocrine and metabolic disturbances associated with hypogonadal pituitary-reproductive tract hypercytolipidemia are functional manifestations of the expressed diabetes-obesity syndrome in db/db-mutants. The progressive vaso-, interstitial-, and cyto-lipidemic alterations in cytoarchitecture correlated with the coincident nuclear lipoapoptotic dissolution and pronounced organo-involution, alterations which contributed to the functional disruption of the pituitary-hypogonadal axis in C57BL/KsJ-db/db mice.

Metabolomics with LC-QTOF-MS permits the prediction of disease stage in aortic abdominal aneurysm based on plasma metabolic fingerprint

Abdominal aortic aneurysm (AAA) is a permanent and localized aortic dilation, defined as aortic diameter ≥3 cm. It is an asymptomatic but potentially fatal condition because progressive enlargement of the abdominal aorta is spontaneously evolving towards rupture.

Biomarkers may help to explain pathological processes of AAA expansion, and allow us to find novel therapeutic strategies or to determine the efficiency of current therapies. Metabolomics seems to be a good approach to find biomarkers of AAA. In this study, plasma samples of patients with large AAA, small AAA, and controls were fingerprinted with LC-QTOF-MS. Statistical analysis was used to compare metabolic fingerprints and select metabolites that showed a significant change. Results presented here reveal that LC-QTOF-MS based fingerprinting of plasma from AAA patients is a very good technique to distinguish small AAA, large AAA, and controls. With the use of validated PLS-DA models it was possible to classify patients according to the disease stage and predict properly the stage of additional AAA patients. Identified metabolites indicate a role for sphingolipids, lysophospholipids, cholesterol metabolites, and acylcarnitines in the development and progression of AAA. Moreover, guanidinosuccinic acid, which mimics nitric oxide in terms of its vasodilatory action, was found as a strong marker of large AAA.

A novel nuclear signaling pathway for thromboxane A2 receptors in oligodendrocytes: evidence for signaling compartmentalization during differentiation

The present study investigated G protein expression, localization, and functional coupling to thromboxane A(2) receptors (TPRs) during oligodendrocyte (OLG) development. It was found that as OLGs mature, the expression levels of G(q) increase while those of G(13) decrease. In contrast, the expression levels of G(s), G(o), and G(i) do not change significantly. Localization studies revealed that G(q), G(13), and G(i) are present only in the extranuclear compartment, whereas G(s) and G(o) are found in both the extranuclear and the nuclear compartments. Purification of TPR-G protein complexes demonstrated that TPRs couple to both G(q) and G(13) in the extranuclear compartment but only to G(s) in the nuclear compartment. Furthermore, functional analysis revealed that stimulation of nuclear TPR in OLGs stimulates CREB phosphorylation and myelin basic protein transcription and increases survival. Collectively, these results demonstrate that (i) OLGs selectively modulate the expression of certain G proteins during development, (ii) G proteins are differentially localized in OLGs leading to subcellular compartmentalization, (iii) TPRs couple to G(q) and G(13) in the extranuclear compartment and to G(s) only in the nucleus, (iv) mature OLGs have a functional nuclear TPR-G(s) signaling pathway, and (v) nuclear TPR signaling can stimulate CREB phosphorylation and myelin gene transcription and increase cell survival. These findings represent a novel paradigm for selective modulation of G protein-coupled receptor-G protein signaling during cell development.

Drosophila Pxt: a cyclooxygenase-like facilitator of follicle maturation

Prostaglandins are local transient hormones that mediate a wide variety of biological events, including reproduction. The study of prostaglandin biology in a genetically tractable invertebrate model organism has been limited by the lack of clearly identified prostaglandin-mediated biological processes and prostaglandin metabolic genes, particularly analogs of cyclooxygenase (COX), the rate-limiting step in vertebrate prostaglandin synthesis. Here, we present pharmacological data that Drosophila ovarian follicle maturation requires COX-like activity and genetic evidence that this activity is supplied in vivo by the Drosophila peroxidase Pxt. pxt mutant females are sterile, and maturing follicles show defects in actin filament formation, nurse cell membrane stability and border cell migration. Maturation of pxt follicles in vitro is stimulated by prostaglandin treatment and fertility is restored in vivo to pxt mutants by expressing mammalian Cox1 protein. Our experiments suggest that prostaglandins promote Drosophila follicle maturation, in part by modulating the actin cytoskeleton, and establish Drosophila oogenesis as a model for understanding these critical biological regulators.

3D-QSAR study of microsomal prostaglandin E2 synthase (mPGES-1) inhibitors

Microsomal prostaglandin E(2) synthase (mPGES-1) has been identified recently as a novel target for treating pain and inflammation. The aim of this study is to understand the binding affinities of reported inhibitors for mPGES-1 and further to design potential new mPGES-1 inhibitors. 3D-QSAR-CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) - techniques were employed on a series of indole derivatives that act as selective mPGES-1 inhibitors. The lowest energy conformer of the most active compound obtained from systematic conformational search was used as a template for the alignment of 32 compounds. The models obtained were used to predict the activities of the test set of eight compounds, and the predicted values were in good agreement with the experimental results. The 3D-QSAR models derived from the training set of 24 compounds were all statistically significant (CoMFA; q (2) = 0.89, r (2) = 0.95, [Formula: see text], [Formula: see text] and CoMSIA; q (2) = 0.84, r (2) = 0.93, [Formula: see text], [Formula: see text]). Contour plots generated for the CoMFA and CoMSIA models reveal useful clues for improving the activity of mPGES-1 inhibitors. In particular, substitutions of an electronegative fluorine atom or a bulky hydrophilic phenoxy group at the meta or para positions of the biphenyl rings might improve inhibitory activity. A plausible binding mode between the ligands and mPGES-1 is also proposed.

Homeostatic restitution of cell membranes. Nuclear membrane lipid biogenesis and transport of protein from cytosol to intranuclear spaces

Our studies on homeostatic restitution of cellular and subcellular membranes showed that vesicular intracellular transport is engaged in systematic and coordinated replacement of lipids and proteins in the membranes of the secretory, non-dividing epithelial cells (Slomiany et al., J. Physiol. Pharmacol. 2004; 55: 837-860). In this report, we present evidence on the homeostatic restitution of lipids in the biomembranes that constitute nuclear envelopes. We investigated nuclear membranes lipid synthesis by employing purified intact nuclei (IN), the outer nuclear membrane (ONM), the inner nuclear membrane (INM) and the cell cytosol (CC). In contrast to Endoplasmic Reticulum (ER) which in the presence of CC generates new biomembrane that forms ER vesicles transporting ER products to Golgi, the IN, ONM and INM are not producing transport vesicles. Instead, the newly synthesized lipids remain in the nuclear membranes. The membranes (INM, ONM) of IN incubated with CC become enriched with newly synthesized phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylinositol phosphates (PIPs) and phosphatidic acid (PA). The incubation of separated ONM and INM with CC also enriched the membranes with IN specific lipids identified above. Moreover, the incubation of IN or its membranes with CC afforded retention of numerous CC proteins on the nuclear membrane. Here, we concentrated on 30kDa CC protein that displayed affinity to nuclear membrane PIP2. The 30kDa CC protein bound to PIP2 of IN, INM, and ONM. With IN, initially the PIP2-30kDa CC protein complex was detected on ONM, after 30-120 min of incubation, was found on INM and in nuclear contents. At the same time when the 30 kDa protein was released from INM and found in nuclear contents, the PIP2 of INM and ONM became undetectable, while the lipid extract from the membrane displaced from IN contained labeled PI only. Since ONM is an uninterrupted continuum of ER and INM, we speculate that the synthesis of the lipids in the ER, in the region adjacent to nucleus, is defining nuclear outer and inner biomembrane composition, is responsible for transport of the cytosolic protein into the nucleus and, replenishment of ER membrane used for vesicular transport.

Prostaglandin D2 induces programmed cell death in Trypanosoma brucei bloodstream form

African trypanosomes produce some prostanoids, especially PGD2, PGE2 and PGF2alpha (Kubata et al. 2000, J. Exp. Med. 192: 1327-1338), probably to interfere with the host's physiological response. However, addition of prostaglandin D2 (but not PGE2 or PGF2alpha) to cultured bloodstream form trypanosomes led also to a significant inhibition of cell growth. Based on morphological alterations and specific staining methods using vital dyes, necrosis and autophagy were excluded. Here, we report that in bloodstream form trypanosomes PGD2 induces an apoptosis-like programmed cell death, which includes maintenance of plasma membrane integrity, phosphatidylserine exposure, loss of mitochondrial membrane potential, nuclear chromatin condensation and DNA degradation. The use of caspase inhibitors cannot prevent the cell death, indicating that the process is caspase-independent. Based on these results, we suggest that PGD2-induced programmed cell death is part of the population density regulation as observed in infected animals.

Gonadal steroid modulation of the diabetes (db/db) mutation-induced hyperlipometabolic, hypogonadal syndrome: Restoration of female reproductive tract cytochemical and structural indices

The gonadal steroids, 17-B-estradiol (E2) and progesterone (P), are recognized to stimulate cellular gluco- and lipo-metabolic compensatory cascades which counteract the deleterious influences of the diabetes (db/db) mutation (i.e., leptin membrane receptor defect) which promotes a progressive, hypercytolipidemia-induced premature involution of the female reproductive tract (FRT). The current studies define the therapeutic efficacy of E2 (1 microg/3.5 days) and P (1 mg/3.5 days) treatments (HRx) on utero-ovarian structural and cytochemical (gluco-/lipo-metabolic) maintenance, and the prevention of premature nuclear apoptosis and cytostructural disruption, following the expression of progressive db/db-induced hypercytolipidemia. Control (normal: +/+ and +/?) and diabetes (db/db) genotype groups of 8-week-old (i.e., overt phase of the db/db-hypogonadal syndrome) C57BL/KsJ mice were prepared for high resolution (HRLM) cytochemical and transmission electron (TEM) microscopic analysis of cytolipidemia and nuclear apoptosis (TUNEL-labeled 3'-DNA fragmentation) indices from uterine and ovarian secondary (early antral) follicular tissue samples. Compared to HRx controls, the db/db mutation induced a dramatic increase in cytolipid vacuole volume and density within all ovarian follicular granulosa cells (GC) and uterine endometrial epithelial (UEE) layers. The co-localization of nuclear apoptotic 3'-DNA fragments within identified hyperlipidemic granulosa cells was coincident with the cytochemical and ultrastructural identification of lipid penetration through the nuclear envelope in db/db mutants. P-HRx moderated the severity of db/db-induced GC and UEE hypercytolipidemia, reducing the cytodensity of lipid vacuole accumulations and maintaining cytoplasmic organelle structure, organization, and nuclear membrane integrity. In contrast, E2-HRx resulted in a dramatic reduction in db/db cytolipidemia in both ovarian GC and UEE tissue compartments. Following E2-HRx, UEE cells demonstrated non-pycnotic nuclear profiles, reduced nuclear apoptosis TUNEL-labeling, increased cytoplasmic organelle density profiles and a pronounced cytoplasmic cisternal expansion indicative of active cellular nutrient/metabolite trafficking. Ovarian follicular GC populations demonstrated minimal cytolipidemia, a restored cytoarchitecture with prominent organelle compartments and reduced TUNEL-indexed nuclear lipoapoptosis. These results are the first cytochemical and ultrastructural indications that P- and E2-HRx compensate for the genetic db/db mutation-induced metabolic disturbances, which promote utero-ovarian hypercytolipidemia and the coincident nuclear lipoapoptosis culminating in the expressed diabetes hypogonadal syndrome. The capability of P-HRx to moderate the severity of utero-ovarian involution in db/db mutants, and of E2-HRx to restore and maintain viable GC and UEE cyto-chemical and -structural indices under normoglycemic conditions, suggests that chronic, low-dose cyclic P- and E2-HRx stimulate cellular gluco- and lipo-metabolic cascades which compensate for the lack of leptin signaling in these single-gene, obese-Type II diabetic mutants. The compensatory endometabolic maintenance of utero-ovarian cellular and nuclear architecture suggests that the gluco- and lipo-metabolic disregulation may be therapeutically prevented or reversed, restoring reproductive tract cytointegrity and function, reducing the manifestation of hypogonadal reproductive sterility and db/db compromise of the female reproductive tract.

Targeted lipidomics: fatty acid amides and pain modulation

Mass spectrometric approaches to the identification and quantification of lipid signalling molecules are reviewed. Fatty acid amides are an important new class of lipid signalling molecules which include oleamide, the endocannabinoid anandamide, the endovanilloid/endocannabinoid N-arachidonoyldopamine (NADA) and the endovanilloid N-oleoyldopamine (OLDA) among many others. This diverse group of endogenous compounds comprises combinations of acyl backbones coupled by an amide bond to any of a variety of different small polar molecules such as ethanolamine, various amino acids, and catecholamines. Many fatty acid amides appear to play a role in pain and inflammation. Targeted lipidomics of fatty acid amides aims to identify new members of this diverse class of compounds, of which only a few representative molecules have been characterized to date. This effort has been made feasible by advances in chromatography and mass spectrometry, which permits: (1) identification of compounds present in complex mixtures, (2) astronomical increases in sensitivity due to miniaturization of HPLC components, and (3) novel scanning modes that permit the identification of compounds exhibiting similar structural components. Insofar as lipid signalling molecules such as prostanoids, leukotrienes and endocannabinoids operate via G-protein coupled receptors (GPCR), it appears likely that many of the numerous lipids awaiting identification may serve as ligands for any of the greater than 150 orphan GPCRs.

An automated multistep high-throughput screening assay for the identification of lead inhibitors of the inducible enzyme mPGES-1

Prostaglandin E2 synthase (mPGES-1), the enzyme which catalyzes the synthesis of PGE2, is induced during the inflammatory response. For this reason, mPGES-1 could be a potential therapeutic target. A high-throughput screening assay was developed to identify potential inhibitors of mPGES-1. The assay consisted of a 30-s mPGES-1 enzymatic reaction followed by the detection of PGE2 by enzyme immunoassay (EIA). The enzymatic reaction was performed in a batch mode because the instability of the substrate (10 min) limited the number of plates assayed within a working day. The detection of the product by EIA was performed on 3 instruments requiring 14 different steps for complete automation. The authors describe here the optimization and implementation of a 2-part assay on a Thermo CRS robotic system. More than 315,000 compounds were tested, and a hit rate of 0.84% was obtained for this assay. Although the entire assay required multiple steps, the assay was successfully miniaturized and automated for a high-throughput screening campaign.

Ovarian follicular lipoapoptosis: structural, cytochemical and metabolic basis of reproductive tract atrophy following expression of the hypogonadal diabetes (db/db) syndrome

The diabetes (db/db) mutation (i.e., leptin membrane receptor defect) promotes a progressive, hypercytolipidemia within ovarian follicular granulosa, thecal and interstitial layers of C57BL/KsJ mice which manifests an infertile, acyclic hypogonadal syndrome. The current studies focus on the structural, cytochemical and gluco-/lipo-metabolic changes which induce cellular lipoapoptosis and the resulting cytostructural disruption of db/db follicular populations, relative to littermate control indices, following the expression of progressive ovarian hypercytolipidemia. Control (normal: +/+ and +/?) and diabetes (db/db) genotype groups were prepared for high resolution light microscopic (HRLM) analysis of cytolipidemia and nuclear apoptosis (TUNEL-labeled 3'-DNA fragmentation) indices and compared to the transmission electron (TEM) microscopic analysis of ovarian follicular samples collected from 8-16-week-old groups. Compared to controls, the db/db mutation induced a dramatic increase in cytolipid vacuole volume and density within all ovarian follicular layers. TEM analysis revealed that the lipid vacuoles initially aggregated along the inner membrane compartments of affected thecal and granulosa cells in response to the interstitial and vaso-lipidemic-hyperglycemic conditions which characterized the ovarian microenvironment of db/db follicles. Progressive cytoplasmic movement of lipid pools into the perinuclear compartment of affected granulosa cells induced nuclear isolation from cytoplasmic organelles that were displaced towards peripheral intracellular compartments. Cytochemical analysis of lipid vacuole accumulations indicated attraction towards, and incorporation within, the nuclear envelope of hyperlipidemic cells. Co-localization of nuclear apoptotic 3'-DNA fragments within identified hyperlipidemic granulosa cells was coincident with the cytochemical and ultrastructural identification of lipid penetration through the nuclear envelope in db/db mutants. These results are the first cytochemical evidence that the lipometabolic disturbances in db/db mutants, which promote hypercytolipidemia-induced premature ovarian involution, are coincident with lipoapoptosis-induced nuclear dissolution within follicular granulosa layers. The lipidemia-induced alterations in cellular and nuclear architecture suggests that the disturbances in glucose and lipid metabolic cascade activities in diabetes (db/db) mutants disrupts follicular cytointegrity, culminating in nuclear disregulation (as indicated by lipoapoptosis) which results in premature reproductive tract organo-involution and manifest reproductive sterility.

Minoxidil: mechanisms of action on hair growth

We have known for over 30 years that minoxidil stimulates hair growth, yet our understanding of its mechanism of action on the hair follicle is very limited. In animal studies, topical minoxidil shortens telogen, causing premature entry of resting hair follicles into anagen, and it probably has a similar action in humans. Minoxidil may also cause prolongation of anagen and increases hair follicle size. Orally administered minoxidil lowers blood pressure by relaxing vascular smooth muscle through the action of its sulphated metabolite, minoxidil sulphate, as an opener of sarcolemmal KATP channels. There is some evidence that the stimulatory effect of minoxidil on hair growth is also due to the opening of potassium channels by minoxidil sulphate, but this idea has been difficult to prove and to date there has been no clear demonstration that KATP channels are expressed in the hair follicle. A number of in vitro effects of minoxidil have been described in monocultures of various skin and hair follicle cell types including stimulation of cell proliferation, inhibition of collagen synthesis, and stimulation of vascular endothelial growth factor and prostaglandin synthesis. Some or all of these effects may be relevant to hair growth, but the application of results obtained in cell culture studies to the complex biology of the hair follicle is uncertain. In this article we review the current state of knowledge on the mode of action of minoxidil on hair growth and indicate lines of future research.

Nuclear prostaglandin receptors: role in pregnancy and parturition?

The key regulatory role of prostanoids [prostaglandins (PGs) and thromboxanes (TXs)] in the maintenance of pregnancy and initiation of parturition has been established. However, our understanding of how these events are fine-tuned by the recruitment of specific signaling pathways remains unclear. Whereas, initial thoughts were that PGs were lipophilic and would easily cross cell membranes without specific receptors or transport processes, it has since been realized that PG signaling occurs via specific cell surface G-protein coupled receptors (GPCRs) coupled to classical adenylate cyclase or inositol phosphate signaling pathways. Furthermore, specific PG transporters have been identified and cloned adding a further level of complexity to the regulation of paracrine action of these potent bioactive molecules. It is now apparent that PGs also activate nuclear receptors, opening the possibility of novel intracrine signaling mechanisms. The existence of intracrine signaling pathways is further supported by accumulating evidence linking the perinuclear localization of PG synthesizing enzymes with intracellular PG synthesis. This review will focus on the evidence for a role of nuclear actions of PGs in the regulation of pregnancy and parturition.

Prostaglandin synthases: recent developments and a novel hypothesis

Cells are continuously exposed to cues, which signal cell survival or death. Fine-tuning of these conflicting signals is essential for tissue development and homeostasis, and defective pathways are linked to many disease processes, especially cancer. It is well established that prostaglandins (PGs), as signalling molecules, are important regulators of cell proliferation, differentiation and apoptosis. PG production has been a focus of many researchers interested in the mechanisms of parturition. Previously, investigators have focussed on the committed step of PG biosynthesis, the conversion by prostaglandin H synthase (PGHS; also termed cyclo-oxygenase, COX) of arachidonic acid (AA) (substrate) to PGH2, the common precursor for biosynthesis of the various prostanoids. However, recently the genes encoding the terminal synthase enzymes involved in converting PGH2 to each of the bioactive PGs, including the major uterotonic PGs, PGE2 (PGE synthase) and PGF2alpha (PGF synthase), have been cloned and characterized. This review highlights how the regulation of the expression and balance of key enzymes can produce, from a single precursor, prostanoids with varied and often opposing effects.

Eosinophils and cysteinyl leukotrienes

Eosinophils are the main source of the cysteinyl leukotrienes, LTC(4)/D(4)/E(4), which are lipid mediators that play major roles in the pathogenesis of asthma and other forms of allergic inflammation. Here, we review the mechanisms governing eosinophil LTC(4) synthesis, focusing on the distinct intracellular domains that regulate eicosanoid formation and function within eosinophils. Cysteinyl leukotrienes exert their actions by engaging specific receptors. As recently shown, eosinophils express CysLT1 and CysLT2, the only cloned receptors for cysteinyl leukotrienes. Therefore, here we also present some of the new findings regarding the paracrine/autocrine activation of these CysLT receptors on eosinophils, and discuss some data on novel intracrine effects of LTC(4) triggered by a putative third CysLT receptor expressed intracellularly within eosinophils.

Activation of cytosolic phospholipase A2 in human T-lymphocytes involves inhibitor-kappaB and mitogen-activated protein kinases

The group IV 85 kDa cytosolic phospholipase A(2) regulates many aspects of innate immunity. However, the function of this enzyme in T-cells remains controversial. We show here that human peripheral blood lymphocytes and Jurkat cells express cytosolic phospholipase A(2) and produce prostaglandin A(2) and leukotriene B(4). Selective inhibitors of this enzyme suppressed Ca(2+)-ionophore-, mitogen- and T-cell receptor-mediated expression of interleukin-2 at the level of transcription from the promoter. Activation of mitogen-activated protein kinases (MAPK), degradation of inhibitor-kappaBalpha and transactivation by nuclear factor-kappaB (NFkappaB) were impaired as was the antigen-, lectin- and interleukin-2-driven proliferation of T-cells in vitro. Ligands of peroxisome proliferator-activated receptor-gamma (PPARgamma) induced rapid phosphorylation of MAPK in human monocytic but not in Jurkat cells. These data indicated that in T-cells, eicosanoids generated upon signal-activated cytosolic phospholipase A(2) promote NFkappaB-dependent interleukin-2 transcription via a PPARgamma-independent mechanism involving the MAPK-pathway.

Lipopolysaccharide-induced leukocyte lipid body formation in vivo: innate immunity elicited intracellular Loci involved in eicosanoid metabolism

Lipid bodies are rapidly inducible, specialized cytoplasmic domains for eicosanoid-forming enzyme localization, which we hypothesize to have specific roles in enhanced inflammatory mediator production during pathological conditions, including sepsis. However, little is known about the origins, composition, or functions of lipid bodies in vivo. We show that lipid body numbers were increased in leukocytes from septic patients in comparison with healthy subjects. Analogously, the intrathoracic administration of LPS into mice induced a dose- and time-dependent increase in lipid body numbers. Pretreatment with anti-CD14 or anti-CD11b/CD18 mAb drastically inhibited LPS-induced lipid body formation. Moreover, LPS failed to form lipid bodies in C3H/HeJ (TLR4 mutated) mice, demonstrating a requisite role for LPS receptors in lipid body formation. LPS-induced lipid body formation was also inhibited by the platelet-activating factor-receptor antagonists, suggesting a role for endogenous platelet-activating factor. The eicosanoid-forming enzymes, 5-lipoxygenase and cyclooxygenase-2, were immunolocalized within experimentally induced (LPS in mice) or naturally occurring (septic patients) lipid bodies. The proinflammatory cytokine involved in the pathogenesis of sepsis, TNF-alpha, was also shown to colocalize within lipid bodies. Prior stimulation of leukocytes to form lipid bodies enhanced the capacity of leukocytes to produce leukotriene B(4) and PGE(2). In conclusion, our studies indicate that lipid bodies formed after LPS stimulation and sepsis are sites for eicosanoid-forming enzymes and cytokine localization and may develop and function as structurally distinct, intracellular sites for paracrine eicosanoid synthesis during inflammatory conditions.

Endocannabinoids and cannabinoid receptor genetics

This review presents the remarkable advances that have been achieved in marijuana (cannabinoid) research, with the discovery of specific receptors and the existence of naturally occurring cannabis-like substances in the human body and brain. The last decade has seen more rapid progress in marijuana research than any time in the thousands of years that marijuana has been used by humans, particularly in cannabinoid genomics. The cDNA and genomic sequences encoding G protein-coupled cannabinoid receptors (Cnrs) from several species have now been cloned. Endogenous cannabinoids (endocannabinoids), synthetic and hydrolyzing enzymes and transporters that define neurochemically-specific cannabinoid brain pathways have been identified. Endocannabinoid lipid signaling molecules alter activity at G protein-coupled receptors (GPCR) and possibly at anandamide-gated ion channels, such as vanilloid receptors. Availability of increasingly-specific CB1 and CB2 Cnr antagonists and of CB1 and CB2 Cnr knockout mice have increased our understanding of these cannabinoid systems and provides tantalizing evidence for even more G protein-coupled Cnrs. Initial studies of the Cnr gene structure, regulation and polymorphisms whet our appetite for more information about these interesting genes, their variants and roles in vulnerabilities to addictions and other neuropsychiatric disorders. Behavioral studies of cannabinoids document the complex interactions between rewarding and aversive effects of these drugs. Pursuing cannabinoid-related molecular, pharmacological and behavioral leads will add greatly to our understanding of endogenous brain neuromodulator systems, abused substances and potential therapeutics. This review of CB1 and CB2 Cnr genes in human and animal brain and their neurobiological effects provide a basis for many of these studies. Therefore, understanding the physiological cannabinoid control system in the human body and brain will contribute to elucidating this natural regulatory mechanism in health and disease.

The cellular biology of eosinophil eicosanoid formation and function

Eosinophils are capable of generating eicosanoid derivatives of arachidonic acid by means of cyclooxygenase and the 5- and 15-lipoxygenase (LO) pathways. Moreover, eosinophils, because of their expression of leukotriene (LT) C(4) synthase, are a major source of 5-LO-derived cysteinyl LTs, which are potent paracrine mediators of bronchial obstruction and inflammation pertinent to asthma. The regulation of eicosanoid formation within eosinophils involves activation of key enzymes at specific intracellular sites. Calcium ionophore-elicited translocation of 5-LO to the membranes of the nuclear envelope is associated with LTC(4) formation. In addition, lipid bodies, the formation of which is initiated by specific receptor-mediated signaling pathways, are sites of cyclooxygenase- and LO-pathway eicosanoid formation. Newly formed LTC(4) can be immunolocalized at perinuclear membranes in ionophore-activated eosinophils and at lipid bodies in CCR3 agonist (eg, eotaxin) chemokine-stimulated eosinophils. The local generation of eicosanoids at distinct sites within eosinophils may be important for the roles of these eicosanoids, both as paracrine mediators pertinent to inflammation and as intracrine signal-transducing mediators that help regulate cellular responses of eosinophils.