Arachidonic acid in cell signaling

Arachidonic acid metabolism as a novel pathogenic factor in gastrointestinal cancers

Gastrointestinal (GI) cancers are a major global health burden, representing 20% of all cancer diagnoses and 22.5% of global cancer-related deaths. Their aggressive nature and resistance to treatment pose a significant challenge, with late-stage survival rates below 15% at five years. Therefore, there is an urgent need to delve deeper into the mechanisms of gastrointestinal cancer progression and optimize treatment strategies. Increasing evidence highlights the active involvement of abnormal arachidonic acid (AA) metabolism in various cancers. AA is a fatty acid mainly metabolized into diverse bioactive compounds by three enzymes: cyclooxygenase, lipoxygenase, and cytochrome P450 enzymes. Abnormal AA metabolism and altered levels of its metabolites may play a pivotal role in the development of GI cancers. However, the underlying mechanisms remain unclear. This review highlights a unique perspective by focusing on the abnormal metabolism of AA and its involvement in GI cancers. We summarize the latest advancements in understanding AA metabolism in GI cancers, outlining changes in AA levels and their potential role in liver, colorectal, pancreatic, esophageal, gastric, and gallbladder cancers. Moreover, we also explore the potential of targeting abnormal AA metabolism for future therapies, considering the current need to explore AA metabolism in GI cancers and outlining promising avenues for further research. Ultimately, such investigations aim to improve treatment options for patients with GI cancers and pave the way for better cancer management in this area.

Experimental investigation and molecular simulations of quinone related compounds as COX/LOX inhibitors

Quinone-containing compounds have risen as promising anti-inflammatory targets; however, very little research has been directed to investigate their potentials. Accordingly, the current study aimed to design and synthesize group of quinones bearing different substituents to investigate the effect of these functionalities on the anti-inflammatory activities of this important scaffold. The choice of these substituents was carefully done, varying from a directly attached heterocyclic ring to different aromatic moieties linked through a nitrogen spacer. Both in vitro and in vivo anti-inflammatory activities of the synthesized compounds were assessed relative to the positive standards: celecoxib and indomethacin. The in vitro enzymatic and transcription inhibitory actions of all the synthesized compounds were tested against cyclooxygenase-2 (COX-2), cyclooxygenase-1 (COX-1), and 5-lipoxygenase (LOX) and the in vivo gene expression of Interleukin-1, interleukin 10, and Tumor Necrosis Factor-α (TNF-α) were determined. The IC50 against COX-1 and COX-2 enzymes obtained by the immunoassay test revealed promising activities of sixteen compounds with selectivity indices higher than 100-fold COX-2 selectivity. Out of those, four compounds revealed selectivity indices comparable to celecoxib as a reference drug. Furthermore, all the tested compounds inhibited LOX with an IC50 in the range of 1.59-3.11 µM superior to that of the reference drug used; zileuton (IC50 = 3.50 µM). Consequently, these results highlight the promising LOX inhibitory activity of the tested compounds. The obtained in vivo paw edema results showed high inhibitory percentage for the compounds 9a, 9b, and 11a with the significant lower TNF-α relative mRNA expression for compounds 5a, 5d, 9a, 9b, 12d, and 12e. Finally, in silico docking of the most active compounds (5b, 5d, 9a, 9b) against COX2 enzymes presented an acceptable justification of the obtained in vitro inhibitory activities. As a conclusion, Compounds 5b, 5d, 9a, 9b, and 11b showed promising results and thus deserves further investigation.

Targeting Dysregulated Lipid Metabolism in Cancer with Pharmacological Inhibitors

Metabolic plasticity is recognised as a hallmark of cancer cells, enabling adaptation to microenvironmental changes throughout tumour progression. A dysregulated lipid metabolism plays a pivotal role in promoting oncogenesis. Oncogenic signalling pathways, such as PI3K/AKT/mTOR, JAK/STAT, Hippo, and NF-kB, intersect with the lipid metabolism to drive tumour progression. Furthermore, altered lipid signalling in the tumour microenvironment contributes to immune dysfunction, exacerbating oncogenesis. This review examines the role of lipid metabolism in tumour initiation, invasion, metastasis, and cancer stem cell maintenance. We highlight cybernetic networks in lipid metabolism to uncover avenues for cancer diagnostics, prognostics, and therapeutics.

The Conventional and Breakthrough Tool for the Study of L-Glutamate Transporters

In our recent report, we clarified the direct interaction between the excitatory amino acid transporter (EAAT) 1/2 and polyunsaturated fatty acids (PUFAs) by applying electrophysiological and molecular biological techniques to Xenopus oocytes. Xenopus oocytes have a long history of use in the scientific field, but they are still attractive experimental systems for neuropharmacological studies. We will therefore summarize the pharmacological significance, advantages (especially in the study of EAAT2), and experimental techniques that can be applied to Xenopus oocytes; our new findings concerning L-glutamate (L-Glu) transporters and PUFAs; and the significant outcomes of our data. The data obtained from electrophysiological and molecular biological studies of Xenopus oocytes have provided us with further important questions, such as whether or not some PUFAs can modulate EAATs as allosteric modulators and to what extent docosahexaenoic acid (DHA) affects neurotransmission and thereby affects brain functions. Xenopus oocytes have great advantages in the studies about the interactions between molecules and functional proteins, especially in the case when the expression levels of the proteins are small in cell culture systems without transfections. These are also proper to study the mechanisms underlying the interactions. Based on the data collected in Xenopus oocyte experiments, we can proceed to the next step, i.e., the physiological roles of the compounds and their significances. In the case of EAAT2, the effects on the neurotransmission should be examined by electrophysiological approach using acute brain slices. For new drug development, pharmacokinetics pharmacodynamics (PKPD) data and blood brain barrier (BBB) penetration data are also necessary. In order not to miss the promising candidate compounds at the primary stages of drug development, we should reconsider using Xenopus oocytes in the early phase of drug development.

Interface between Resolvins and Efferocytosis in Health and Disease

Acute inflammation resolution acts as a vital process for active host response, tissue support, and homeostasis maintenance, during which resolvin D (RvD) and E (RvE) as mediators derived from omega-3 polyunsaturated fatty acids display specific and stereoselective anti-inflammations like restricting neutrophil infiltration and pro-resolving activities. On the other side of the coin, potent macrophage-mediated apoptotic cell clearance, namely efferocytosis, is essential for successful inflammation resolution. Further studies mentioned a linkage between efferocytosis and resolvins. For instance, resolvin D1 (RvD1), which is endogenously formed from docosahexaenoic acid within the inflammation resolution, thereby provoking efferocytosis. There is still limited information regarding the mechanism of action of RvD1-related efferocytosis enhancement at the molecular level. The current review article was conducted to explore recent data on how the efferocytosis process and resolvins relate to each other during the inflammation resolution in illness and health. Understanding different aspects of this connection sheds light on new curative approaches for medical conditions caused by defective efferocytosis and disrupted inflammation resolution.

Metabolomics unveils the exacerbating role of arachidonic acid metabolism in atherosclerosis

Atherosclerosis is a complex vascular disorder characterized by the deposition of lipids, inflammatory cascades, and plaque formation in arterial walls. A thorough understanding of its causes and progression is necessary to develop effective diagnostic and therapeutic strategies. Recent breakthroughs in metabolomics have provided valuable insights into the molecular mechanisms and genetic factors involved in atherosclerosis, leading to innovative approaches for preventing and treating the disease. In our study, we analyzed clinical serum samples from both atherosclerosis patients and animal models using laser desorption ionization mass spectrometry. By employing methods such as orthogonal partial least-squares discrimination analysis (OPLS-DA), heatmaps, and volcano plots, we can accurately classify atherosclerosis (AUC = 0.892) and identify key molecules associated with the disease. Specifically, we observed elevated levels of arachidonic acid and its metabolite, leukotriene B4, in atherosclerosis. By inhibiting arachidonic acid and monitoring its downstream metabolites, we discovered the crucial role of this metabolic pathway in regulating atherosclerosis. Metabolomic research provides detailed insights into the metabolic networks involved in atherosclerosis development and reveals the close connection between abnormal metabolism and the disease. These studies offer new possibilities for precise diagnosis, treatment, and monitoring of disease progression, as well as evaluating the effectiveness of therapeutic interventions.

Integrative analyses of transcriptomes and metabolomes provide insight into salinity adaption in Bangia (Rhodaphyta)

The salinity of the external environment poses a serious threat to most land plants. Although seaweeds can adapt to this, intertidal species are subject to wide fluctuations in salinity, including hypo- and hyper-saline conditions. The red algal genus Bangiales is a typical example; it is one of the oldest eukaryotes with sexual reproduction and has successfully adapted to both marine and freshwater environments. However, there is a dearth of research focused on elucidating the mechanism by which marine Bangia (Bangia fuscopurpurea) adapts to hypo-salinity, as well as the mechanism by which freshwater Bangia (Bangia atropurpurea) adapts to hyper-salinity. The objective of this study is to employ third-generation full-length transcriptome data and untargeted metabolome data, to provide insights into the salinity adaptation mechanism of as well as the evolutionary relationship between both Bangia species. B. fuscopurpurea and B. atropurpurea exhibited 9112 and 8772 differentially expressed genes (DEGs), respectively, during various periods of hyper-saline condition. These genes were primarily enriched in secondary metabolites and energy-related metabolic pathways. Additionally, B. fuscopurpurea displayed 16,285 DEGs during different periods of hypo-saline condition, which were mainly enriched in metabolic pathways related to ion transport and membrane proteins. In the hyper- and hypo-saline adapt response processes of B. fuscopurpurea, a total of 303 transcription factors were identified, which belonged to 26 families. Among these, 85 and 142 differential transcription factors were identified, respectively, mainly belonging to the C2H2 and MYB family. Similarly, in the response process of B. atropurpurea to hyper-saline condition, a total of 317 transcription factors were identified, mainly belonging to 17 families. Among these, 121 differential transcription factors were identified, mainly belonging to the C2H2 and bZIP family. Furthermore, a correlation analysis was conducted to examine the relationship between the transcriptional and metabolic levels of both species under saline adaptation. The findings demonstrated that Bangia exhibits intricate adaptations to salinity, which involve swift regulation of its photosynthetic processes, alternations in membrane contents, and a robust anti-oxidation system to mitigate the effects of excess redox energy during exposure to varying salinity. Notably, the unsaturated fat and glutathione metabolic pathways were found to be significantly enriched in this context.

Trans-anethole pretreatment ameliorates hepatic ischemia-reperfusion injury via regulation of soluble epoxide hydrolase

Hepatic ischemia reperfusion injury (IRI) is a risk factor for early graft nonfunction and graft rejection after liver transplantation (LT). The process of liver IRI involves inflammatory response, oxidative stress, apoptosis and other pathophysiological processes. So far, there is still a lack of effective drugs to ameliorate liver IRI. Trans-anethole (TA) is an aromatic compound. Many medications as well as natural foods contain TA. TA has multiple effects such as anti-inflammation, anti-oxidative stress and anti-apoptosis. However, the mechanism of TA pretreatment in liver IRI is unclear. The mice hepatic IRI model was constructed after gavage pretreatment with TA (10 mg/kg, 20 mg/kg, 40 mg/kg) for 7 consecutive days. Our study confirmed that TA pretreatment significantly improve liver function and reduce serum AST, ALT in hepatic IRI. HE staining showed that TA pretreatment alleviated liver injury. Meanwhile, TA (20 mg/kg) pretreatment attenuated hepatocyte apoptosis in hepatic IRI. In addition, TA (20 mg/kg) pretreatment reduced the inflammatory factors TNF-α, IL-6 and infiltration of CD11b positive cells in liver tissues during hepatic IRI in mice. TA pretreatment also alleviated oxidative stress in mice hepatic IRI. Our study further indicated that TA pretreatment attenuated mice hepatic IRI through inhibiting NLRP3 inflammasome activation via regulation of soluble epoxide hydrolase (sEH). This study provides a novel and effective potential drug with few side effects for easing liver IRI.

Over-production of exopolysaccharide by Lacticaseibacillus rhamnosus CNCM I-3690 strain cutbacks its beneficial effect on the host

Most lactobacilli produce extracellular polysaccharides that are considered to contribute to the probiotic effect of many strains. Lacticaseibacillus rhamnosus CNCM I-3690 is an anti-inflammatory strain able to counterbalance gut barrier dysfunction. In this study ten spontaneous variants of CNCM I-3690 with different EPS-production were generated and characterized by their ropy phenotype, the quantification of the secreted EPS and genetic analysis. Amongst them, two were further analysed in vitro and in vivo: an EPS over-producer (7292) and a low-producer derivative of 7292 (7358, with similar EPS levels than the wild type (WT) strain). Our results showed that 7292 does not have anti-inflammatory profile in vitro, and lost the capacity to adhere to the colonic epithelial cells as well as the protective effect on the permeability. Finally, 7292 lost the protective effects of the WT strain in a murine model of gut dysfunction. Notably, strain 7292 was unable to stimulate goblet cell mucus production and colonic IL-10 production, all key features for the beneficial effect of the WT strain. Furthermore, transcriptome analysis of colonic samples from 7292-treated mice showed a down-regulation of anti-inflammatory genes. Altogether, our results point out that the increase of EPS production in CNCM I-3690 impairs its protective effects and highlight the importance of the correct EPS synthesis for the beneficial effects of this strain.

Effect of arachidonic and docosahexaenoic acid supplementation on respiratory outcomes and neonatal morbidities in preterm infants

BACKGROUND & AIMS

Studies have suggested that supplementation with docosahexaenoic acid (DHA) to preterm infants might be associated with an increased risk of bronchopulmonary dysplasia (BPD). Our aim was to investigate the effect of enteral supplementation with arachidonic acid (ARA) and DHA on short-term respiratory outcomes and neonatal morbidities in very preterm infants.

METHODS

This is a secondary analysis of data from the ImNuT (Immature, Nutrition Therapy) study, a randomized double blind clinical trial. Infants with gestational age less than 29 weeks were randomized to receive a daily enteral supplement with ARA 100 mg/kg and DHA 50 mg/kg (intervention) or medium chain triglycerides (MCT) oil (control), from second day of life to 36 weeks postmenstrual age. Study outcomes included duration of respiratory support, incidence of BPD and other major morbidities associated with preterm birth.

RESULTS

120 infants with mean (SD) gestational age 26.4 (1.7) weeks were randomized and allocated to either the intervention or control group. Supplementation with ARA and DHA led to a significant reduction in number of days with respiratory support (mean (95% CI) 63.4 (56.6-71.3) vs 80.6 (72.4-88.8); p = 0.03) and a lower oxygen demand (FiO₂) (mean (95% CI) 0.26 (0.25-0.28) vs 0.29 (0.27-0.30); p = 0.03) compared to control treatment. There were no clinically important differences in incidence of BPD and other major morbidities between the treatment groups.

CONCLUSIONS

Supplementation with ARA and DHA to preterm infants was safe and might have a beneficial effect on respiratory outcomes.

CLINICAL TRIAL REGISTRATION

The trial has been registered in www.

CLINICALTRIALS

gov, ID: NCT03555019.

Structure-guided approach on the role of substitution on amide-linked bipyrazoles and its effect on their anti-inflammatory activity

A structure-guided modelling approach using COX-2 as a template was used to investigate the effect of replacing the chloro atom located at the chlorophenyl ring of amide-linked bipyrazole moieties, aiming at attaining better anti-inflammatory effect with a good safety profile. Bromo, fluoro, nitro, and methyl groups were revealed to be ideal candidates. Consequently, new bipyrazole derivatives were synthesised. The in vitro inhibitory COX-1/COX-2 activity of the synthesised compounds exhibited promising selectivity. The fluoro and methyl derivatives were the most active candidates. The in vivo formalin-induced paw edoema model confirmed the anti-inflammatory activity of the synthesised compounds. All the tested derivatives had a good ulcerogenic safety profile except for the methyl substituted compound. In silico molecular dynamics simulations of the fluoro and methyl poses complexed with COX-2 for 50 ns indicated stable binding to COX-2. Generally, our approach delivers a fruitful matrix for the development of further amide-linked bipyrazole anti-inflammatory candidates.

Glutathione and Glutaredoxin in Redox Regulation and Cell Signaling of the Lens

The ocular lens has a very high content of the antioxidant glutathione (GSH) and the enzymes that can recycle its oxidized form, glutathione disulfide (GSSG), for further use. It can be synthesized in the lens and, in part, transported from the neighboring anterior aqueous humor and posterior vitreous body. GSH is known to protect the thiols of the structural lens crystallin proteins from oxidation by reactive oxygen species (ROS) so the lens can maintain its transparency for proper visual function. Age-related lens opacity or senile cataract is the major visual impairment in the general population, and its cause is closely associated with aging and a constant exposure to environmental oxidative stress, such as ultraviolet light and the metabolic end product, H2O2. The mechanism for senile cataractogenesis has been hypothesized as the results of oxidation-induced protein-thiol mixed disulfide formation, such as protein-S-S-glutathione and protein-S-S-cysteine mixed disulfides, which if not reduced in time, can change the protein conformation to allow cascading modifications of various kinds leading to protein-protein aggregation and insolubilization. The consequence of such changes in lens structural proteins is lens opacity. Besides GSH, the lens has several antioxidation defense enzymes that can repair oxidation damage. One of the specific redox regulating enzymes that has been recently identified is thioltransferase (glutaredoxin 1), which works in concert with GSH, to reduce the oxidative stress as well as to regulate thiol/disulfide redox balance by preventing protein-thiol mixed disulfide accumulation in the lens. This oxidation-resistant and inducible enzyme has multiple physiological functions. In addition to protecting structural proteins and metabolic enzymes, it is able to regulate the redox signaling of the cells during growth factor-stimulated cell proliferation and other cellular functions. This review article focuses on describing the redox regulating functions of GSH and the thioltransferase enzyme in the ocular lens.

Rac1 regulates lipid droplets formation, nanomechanical, and nanostructural changes induced by TNF in vascular endothelium in the isolated murine aorta

Endothelial inflammation is recognized as a critical condition in the development of cardiovascular diseases. TNF-induced inflammation of endothelial cells is linked to the formation of lipid droplets, augmented cortical stiffness, and nanostructural endothelial plasma membrane remodelling, but the insight into the mechanism linking these responses is missing. In the present work, we determined the formation of lipid droplets (LDs), nanomechanical, and nanostructural responses in the model of TNF-activated vascular inflammation in the isolated murine aorta using Raman spectroscopy, fluorescence imaging, atomic force microscopy (AFM), and scanning electron microscopy (SEM). We analysed the possible role of Rac1, a major regulator of cytoskeletal organization, in TNF-induced vascular inflammation. We demonstrated that the formation of LDs, polymerization of F-actin, alterations in cortical stiffness, and nanostructural protuberances in endothelial plasma membrane were mediated by the Rac1. In particular, we revealed a significant role for Rac1 in the regulation of the formation of highly unsaturated LDs formed in response to TNF. Inhibition of Rac1 also downregulated the overexpression of ICAM-1 induced by TNF, supporting the role of Rac1 in vascular inflammation. Altogether, our results demonstrate that LDs formation, an integral component of vascular inflammation, is activated by Rac1 that also regulates nanomechanical and nanostructural alterations linked to vascular inflammation.

Annexin A Protein Family in Atherosclerosis

Atherosclerosis, a silent chronic vascular pathology, is the cause of the majority of cardiovascular ischaemic events. Atherosclerosis is characterized by a series of deleterious changes in cellularity, including endothelial dysfunction, transmigration of circulating inflammatory cells into the arterial wall, pro-inflammatory cytokines production, lipid accumulation in the intima, vascular local inflammatory response, atherosclerosis-related cells apoptosis and autophagy. Proteins of Annexin A (AnxA) family, the well-known Ca²⁺ phospholipid-binding protein, have many functions in regulating inflammation-related enzymes and cell signaling transduction, thus influencing cell adhesion, migration, differentiation, proliferation and apoptosis. There is now accumulating evidence that some members of the AnxA family, such as AnxA1, AnxA2, AnxA5 and AnxA7, play major roles in the development of atherosclerosis. This article discusses the major roles of AnxA1, AnxA2, AnxA5 and AnxA7, and the multifaceted mechanisms of the main biological process in which they are involved in atherosclerosis. Considering these evidences, it has been proposed that AnxA are drivers- and not merely participator- on the road to atherosclerosis, thus the progression of atherosclerosis may be prevented by targeting the expression or function of the AnxA family proteins.

Isomeric lipid signatures reveal compartmentalized fatty acid metabolism in cancer

The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics.

Arachidonic acid drives adaptive responses to chemotherapy-induced stress in malignant mesothelioma

Background High resistance to therapy and poor prognosis characterizes malignant pleural mesothelioma (MPM). In fact, the current lines of treatment, based on platinum and pemetrexed, have limited impact on the survival of MPM patients. Adaptive response to therapy-induced stress involves complex rearrangements of the MPM secretome, mediated by the acquisition of a senescence-associated-secretory-phenotype (SASP). This fuels the emergence of chemoresistant cell subpopulations, with specific gene expression traits and protumorigenic features. The SASP-driven rearrangement of MPM secretome takes days to weeks to occur. Thus, we have searched for early mediators of such adaptive process and focused on metabolites differentially released in mesothelioma vs mesothelial cell culture media, after treatment with pemetrexed.

METHODS

Mass spectrometry-based (LC/MS and GC/MS) identification of extracellular metabolites and unbiased statistical analysis were performed on the spent media of mesothelial and mesothelioma cell lines, at steady state and after a pulse with pharmacologically relevant doses of the drug. ELISA based evaluation of arachidonic acid (AA) levels and enzyme inhibition assays were used to explore the role of cPLA2 in AA release and that of LOX/COX-mediated processing of AA. QRT-PCR, flow cytometry analysis of ALDH expressing cells and 3D spheroid growth assays were employed to assess the role of AA at mediating chemoresistance features of MPM. ELISA based detection of p65 and IkBalpha were used to interrogate the NFkB pathway activation in AA-treated cells.

RESULTS

We first validated what is known or expected from the mechanism of action of the antifolate. Further, we found increased levels of PUFAs and, more specifically, arachidonic acid (AA), in the transformed cell lines treated with pemetrexed. We showed that pharmacologically relevant doses of AA tightly recapitulated the rearrangement of cell subpopulations and the gene expression changes happening in pemetrexed -treated cultures and related to chemoresistance. Further, we showed that release of AA following pemetrexed treatment was due to cPLA2 and that AA signaling impinged on NFkB activation and largely affected anchorage-independent, 3D growth and the resistance of the MPM 3D cultures to the drug.

CONCLUSIONS

AA is an early mediator of the adaptive response to pem in chemoresistant MPM and, possibly, other malignancies.

The dietary arachidonic acid improved growth and immunity of honey bee (Apis mellifera ligustica)

Honeybees cannot synthesize arachidonic acid (ARA) themselves, only obtain it from food. Most pollen is deficient or contains a small amount of ARA. The necessity of supplementary ARA in bees' diet has not been studied. The objective of this study was to investigate the effects of dietary ARA levels on the growth and immunity of Apis mellifera ligustica. A total of 25 honeybee colonies were randomly assigned to five dietary groups which were fed basic diets supplemented with 0, 2, 4, 6, and 8% of ARA. The diet with 4% ARA improved the body weight of newly emerged worker bees compared with the control group. Supplement of ARA in honeybee diets changed the fatty acid composition of honeybee body. SFA and MUFA contents of bees' body declined, and PUFA content rised in the ARA group. Compared with the control group, the supplement of ARA in honeybee diets increased the contents of ARA, C22:6n-3 (DHA) and C18:3n-6 in bees' body significantly, but decreased the contents of C16:1 and C18:3n-3. The diet supplied with 4% ARA reduced the mortality rate of honeybee infected with Escherichia coli. The activity of immune enzymes (phenoloxidase, antitrypsin, and lysozyme) and the mRNA expression levels of immune genes (defensin-2, toll, myd88, and dorsal) were improved by ARA diets to varying degrees depending on the ARA levels, especially 4% ARA. These results suggested that dietary ARA could improve the growth, survival, and immune functions of honeybees. Supplement of ARA in bees' diet would be valuable for the fitness of honeybees.

A Metabolomics Investigation of the Metabolic Changes of Raji B Lymphoma Cells Undergoing Apoptosis Induced by Zinc Ions

Zinc plays a pivotal role in the function of cells and can induce apoptosis in various cancer cells, including Raji B lymphoma. However, the metabolic mechanism of Zn-induced apoptosis in Raji cells has not been explored. In this study, we performed global metabolic profiling using UPLC−Orbitrap−MS to assess the apoptosis of Raji cells induced by Zn ions released from ZnO nanorods. Multivariate analysis and database searches identified altered metabolites. Furthermore, the differences in the phosphorylation of 1380 proteins were also evaluated by Full Moon kinase array to discover the protein associated Zn−induced apoptosis. From the results, a prominent increase in glycerophosphocholine and fatty acids was observed after Zn ion treatment, but only arachidonic acid was shown to induce apoptosis. The kinase array revealed that the phosphorylation of p53, GTPase activation protein, CaMK2a, PPAR−γ, and PLA−2 was changed. From the pathway analysis, metabolic changes showed earlier onset than protein signaling, which were related to choline metabolism. LC−MS analysis was used to quantify the intracellular choline concentration, which decreased after Zn treatment, which may be related to the choline consumption required to produce choline-containing metabolites. Overall, we found that choline metabolism plays an important role in Zn-induced Raji cell apoptosis.

Regulation of Tissue Inflammation by 12-Lipoxygenases

Lipoxygenases (LOXs) are lipid metabolizing enzymes that catalyze the di-oxygenation of polyunsaturated fatty acids to generate active eicosanoid products. 12-lipoxygenases (12-LOXs) primarily oxygenate the 12th carbon of its substrates. Many studies have demonstrated that 12-LOXs and their eicosanoid metabolite 12-hydroxyeicosatetraenoate (12-HETE), have significant pathological implications in inflammatory diseases. Increased level of 12-LOX activity promotes stress (both oxidative and endoplasmic reticulum)-mediated inflammation, leading to damage in these tissues. 12-LOXs are also associated with enhanced cellular migration of immune cells-a characteristic of several metabolic and autoimmune disorders. Genetic depletion or pharmacological inhibition of the enzyme in animal models of various diseases has shown to be protective against disease development and/or progression in animal models in the setting of diabetes, pulmonary, cardiovascular, and metabolic disease, suggesting a translational potential of targeting the enzyme for the treatment of several disorders. In this article, we review the role of 12-LOXs in the pathogenesis of several diseases in which chronic inflammation plays an underlying role.

Use of metabolomics to identify strategies to improve and prolong ex vivo lung perfusion for lung transplants

BACKGROUND

Normothermic ex vivo lung perfusion (EVLP) allows for functional assessment of donor lungs; thus has increased the use of marginal lungs for transplantation. To extend EVLP for advanced organ reconditioning and regenerative interventions, cellular metabolic changes need to be understood. We sought to comprehensively characterize the dynamic metabolic changes of the lungs during EVLP, and to identify strategies to improve EVLP.

METHODS

Human donor lungs (n = 50) were assessed under a 4-hour Toronto EVLP protocol. EVLP perfusate was sampled at first (EVLP-1h) and fourth hour (EVLP-4h) of perfusion and were submitted for mass spectrometry-based untargeted metabolic profiling. Differentially expressed metabolites between the 2 timepoints were identified and analyzed from the samples of lungs transplanted post-EVLP (n = 42) to determine the underlying molecular mechanisms.

RESULTS

Of the total 312 detected metabolites, 84 were up-regulated and 103 were down-regulated at EVLP-4h relative to 1h (FDR adjusted p < .05, fold change ≥ |1.1|). At EVLP-4h, markedly decreased energy substrates were observed, accompanied by the increase in fatty acid β-oxidation. Concurrently, accumulation of amino acids and nucleic acids was evident, indicative of increased protein and nucleotide catabolism. The uniform decrease in free lysophospholipids and polyunsaturated fatty acids at EVLP-4h suggests cell membrane remodeling.

CONCLUSIONS

Untargeted metabolomics revealed signs of energy substrate consumption and metabolic by-product accumulation under current EVLP protocols. Strategies to supplement nutrients and to maintain homeostasis will be vital in improving the current clinical practice and prolonging organ perfusion for therapeutic application to further enhance donor lung utilization.

Exposure to bisphenol analogues interrupts growth, proliferation, and fatty acid compositions of protozoa Tetrahymena thermophila

A number of bisphenol A (BPA) analogues are increasingly used as its industrial alternatives. However, their effects on aquatic organisms at both individual and population levels have not been well understood. In this study, effects of five bisphenol analogues (i.e., BPA, BPAF, BPB, BPE and BPS) were investigated by using the unicellular eukaryote Tetrahymena thermophila as a model organism. All of them inhibited individual growth and population proliferation at a concentration of 2.6 μM or 13.0 μM during the 60-h exposure period, with the population suppression capacify ranked as: BPB > BPA ≈ BPAF > BPE > BPS. These analogues also exhibited chemical-specific disruption of fatty acid profiles in single-cell eukaryotes and the transcriptional levels of enzymes involved in fatty acid metabolism/biosynthesis. For example, exposure to BPA and BPE significantly increased the ratio of saturated fatty acids to unsaturated fatty acids, contrary to the desaturation effects exhibited by BPAF and BPB. Overall, our results clearly indicated that these bisphenol analogues could pose chemical-specific effects on low-trophic level aquatic organisms, particularly disruption of endogenous metabolic balances. Selected analogues (i.e., BPB and BPAF) could result in effects similar to or even greater than that of BPA.

Moderate High Caloric Maternal Diet Impacts Dam Breast Milk Metabotype and Offspring Lipidome in a Sex-Specific Manner

Lactation is a critical period during which maternal sub- or over-nutrition affect milk composition and offspring development that can have lasting health effects. The consequences of moderate high-fat, high-simple carbohydrate diet (WD) consumption by rat dams, during gestation and lactation, on milk composition and offspring blood lipidome and its growth, at weaning, were investigated by using a comprehensive lipidomic study on mass-spectrometric platform combined to targeted fatty- and free amino-acids analysis. This holistic approach allowed clear-cut differences in mature milk-lipidomic signature according to maternal diet with a similar content of protein, lactose and leptin. The lower WD-milk content in total fat and triglycerides (TGs), particularly in TGs-with saturated medium-chain, and higher levels in both sphingolipid (SL) and TG species with unsaturated long-chain were associated to a specific offspring blood-lipidome with decreased levels in TGs-containing saturated fatty acid (FA). The sexual-dimorphism in the FA-distribution in TG (higher TGs-rich in oleic and linoleic acids, specifically in males) and SL species (increased levels in very long-chain ceramides, specifically in females) could be associated with some differences that we observed between males and females like a higher total body weight gain in females and an increased preference for fatty taste in males upon weaning.

Physicochemical Properties and Liposomal Formulations of Hydrolysate Fractions of Four Sea Cucumbers (Holothuroidea: Echinodermata) from the Northwestern Algerian Coast

To promote the nutritional and pharmacological values of four sea cucumber species (Holothuria poli, H. tubulosa, H. arguinensis, and H. sanctori), harvested from the Algerian coast, we aimed to study their proximate composition, fatty acid profile and angiotensin-converting enzyme (ACE) inhibitory activity. Their phospholipids were also used to elaborate nanoliposomes and to encapsulate peptides obtained from the same source. After the physico-chemical characterization of nanoliposomes and peptides, in vitro analyses were realized. The four holothurian species showed a high amount of protein (49.26-69.34%), and an impressive lipid profile of 27 fatty acids, mainly composed of polar fatty acids (91.16-93.85%), with a high polyunsaturated fatty acids (PUFA) content (50.90-71.80%), particularly eicosapentaenoic acid (EPA) (5.07-8.76%) and docosahexaenoic acid (DHA) (4.86-7.25%). A high phospholipids amount was also found (55.20-69.85%), mainly composed of phosphatidylcholine (PC) (51.48-58.56%). Their peptide fractions exhibited a high ACE inhibitory activity (IC50 0.30 to 0.51 mg/mL). The results also showed that the nanoliposomes do not induce cytotoxicity and cell death in human MSCs and no perturbation of proliferation for all the times and the tested concentrations, as well as the combined nanoliposomes and hydrolysates (HTS) at a concentration of 0.1 mg/mL. All four sea cucumbers show potential as a new source for omega-3, omega-6, and bioactive peptides.

Morin hydrate inhibits platelet activation and clot retraction by regulating integrin αIIbβ3, TXA2, and cAMP levels

Morin hydrate is an active constituent of Morus alba L, Prunus dulcis, and Cudrania tricuspidata and has been reported to inhibit platelet activation in vivo and in vitro, but no reports have been issued on its regulation of α_IIbβ₃, a platelet-specific integrin and thromboxane A₂ (TXA₂), positive feedback molecule. In this study, we investigated the anti-platelet activity of morin hydrate in collagen- and thrombin-induced human platelets and attempted to identify the mechanism responsible for integrin α_IIbβ₃ activation and TXA₂ generation. Our results demonstrated that morin hydrate (25-100 μM) inhibited collagen- and thrombin-induced platelet aggregation, granule secretion (P-selectin expression, ATP, and serotonin release), calcium mobilization, TXA₂ production, integrin α_IIbβ₃ activation, and clot retraction. Additionally, morin hydrate attenuated the phosphorylations of phospholipase C_γ2 (PLC_γ2), cytosolic phospholipase A₂ (cPLA₂), phosphoinositide 3-kinase (PI3K), Akt, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK), and enhanced the phosphorylations of inositol trisphosphate receptor (IP₃ receptor) and cyclic adenosine monophosphate (cAMP) generation. However, it had no effect on the coagulation pathway. Taken together, these observations indicate morin hydrate inhibits platelet-mediated thrombosis by down-regulating TXA₂ production and integrin α_IIbβ₃ activation, and by upregulating cAMP generation, and thus, inhibits clot retraction. These results suggest morin hydrate may have therapeutic potential as a treatment for platelet-activation-related diseases.

Associated Bacteria Affect Sexual Reproduction by Altering Gene Expression and Metabolic Processes in a Biofilm Inhabiting Diatom

Diatoms are unicellular algae with a fundamental role in global biogeochemical cycles as major primary producers at the base of aquatic food webs. In recent years, chemical communication between diatoms and associated bacteria has emerged as a key factor in diatom ecology, spurred by conceptual and technological advancements to study the mechanisms underlying these interactions. Here, we use a combination of physiological, transcriptomic, and metabolomic approaches to study the influence of naturally co-existing bacteria, Maribacter sp. and Roseovarius sp., on the sexual reproduction of the biofilm inhabiting marine pennate diatom Seminavis robusta. While Maribacter sp. severely reduces the reproductive success of S. robusta cultures, Roseovarius sp. slightly enhances it. Contrary to our expectation, we demonstrate that the effect of the bacterial exudates is not caused by altered cell-cycle regulation prior to the switch to meiosis. Instead, Maribacter sp. exudates cause a reduced production of diproline, the sexual attraction pheromone of S. robusta. Transcriptomic analyses show that this is likely an indirect consequence of altered intracellular metabolic fluxes in the diatom, especially those related to amino acid biosynthesis, oxidative stress response, and biosynthesis of defense molecules. This study provides the first insights into the influence of bacteria on diatom sexual reproduction and adds a new dimension to the complexity of a still understudied phenomenon in natural diatom populations.

The potential probiotic Lactobacillus rhamnosus CNCM I-3690 strain protects the intestinal barrier by stimulating both mucus production and cytoprotective response

The gut barrier plays an important role in human health. When barrier function is impaired, altered permeability and barrier dysfunction can occur, leading to inflammatory bowel diseases, irritable bowel syndrome or obesity. Several bacteria, including pathogens and commensals, have been found to directly or indirectly modulate intestinal barrier function. The use of probiotic strains could be an important landmark in the management of gut dysfunction with a clear impact on the general population. Previously, we found that Lactobacillus rhamnosus CNCM I-3690 can protect intestinal barrier functions in mice inflammation model. Here, we investigated its mechanism of action. Our results show that CNCM I-3690 can (i) physically maintain modulated goblet cells and the mucus layer and (ii) counteract changes in local and systemic lymphocytes. Furthermore, mice colonic transcriptome analysis revealed that CNCM I-3690 enhances the expression of genes related to healthy gut permeability: motility and absorption, cell proliferation; and protective functions by inhibiting endogenous proteases. Finally, SpaFED pili are clearly important effectors since an L. rhamnosus ΔspaF mutant failed to provide the same benefits as the wild type strain. Taken together, our data suggest that CNCM I-3690 restores impaired intestinal barrier functions via anti-inflammatory and cytoprotective responses.

Phospholipase A2 is involved in galactosylsphingosine-induced astrocyte toxicity, neuronal damage and demyelination

Krabbe disease is a fatal rare inherited lipid storage disorder affecting 1:100,000 births. This illness is caused by mutations in the galc gene encoding for the enzyme galactosylceramidase (GALC). Dysfunction of GALC has been linked to the toxic build-up of the galactolipid, galactosylsphingosine (psychosine), which induces cell death of oligodendrocytes. Previous studies show that phospholipase A2 (PLA2) may play a role in psychosine induce cell death. Here, we demonstrate that non-selective inhibition of cPLA2/sPLA2 and selective inhibition of cPLA2, but not sPLA2, also attenuates psychosine-induced cell death of human astrocytes. This study shows that extracellular calcium is required for psychosine induced cell death, but intracellular calcium release, reactive oxygen species or release of soluble factors are not involved. These findings suggest a cell autonomous effect, at least in human astrocytes. Supporting a role for PLA2 in psychosine-induced cell death of oligodendrocytes and astrocytes, the results show inhibition of PLA2 attenuates psychosine-induced decrease in the expression of astrocyte marker vimentin as well as myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and the neuronal marker SMI-32 in organotypic slice cultures. These findings provide further mechanistic details of psychosine-induced death of glia and suggest a role for PLA2 in the process. This work also supports the proposal that novel drugs for Krabbe disease may require testing on astrocytes as well as oligodendrocytes for more holistic prediction of pre-clinical and clinical efficacy.

Omega-3 polyunsaturated fatty acids and cancer: lessons learned from clinical trials

Over the past decades, extensive studies have addressed the therapeutic effects of omega-3 polyunsaturated fatty acids (omega-3 FAs) against different human diseases such as cardiovascular and neurodegenerative diseases, cancer, etc. A growing body of scientific research shows the pharmacokinetic information and safety of these natural occurring substances. Moreover, during recent years, a plethora of studies has demonstrated that omega-3 FAs possess therapeutic role against certain types of cancer. It is also known that omega-3 FAs can improve efficacy and tolerability of chemotherapy. Previous reports showed that suppression of nuclear factor-κB, activation of AMPK/SIRT1, modulation of cyclooxygenase (COX) activity, and up-regulation of novel anti-inflammatory lipid mediators such as protectins, maresins, and resolvins, are the main mechanisms of antineoplastic effect of omega-3 FAs. In this review, we have collected the available clinical data on the therapeutic role of omega-3 FAs against breast cancer, colorectal cancer, leukemia, gastric cancer, pancreatic cancer, esophageal cancer, prostate cancer, lung cancer, head and neck cancer, as well as cancer cachexia. We also discussed the chemistry, dietary source, and bioavailability of omega-3 FAs, and the potential molecular mechanisms of anticancer and adverse effects.

Metabolomics and transcriptomics identify pathway differences between visceral and subcutaneous adipose tissue in colorectal cancer patients: the ColoCare study

BACKGROUND

Metabolic and transcriptomic differences between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) compartments, particularly in the context of obesity, may play a role in colorectal carcinogenesis. We investigated the differential functions of their metabolic compositions.

OBJECTIVES

Biochemical differences between adipose tissues (VAT compared with SAT) in patients with colorectal carcinoma (CRC) were investigated by using mass spectrometry metabolomics and gene expression profiling. Metabolite compositions were compared between VAT, SAT, and serum metabolites. The relation between patients' tumor stage and metabolic profiles was assessed.

DESIGN

Presurgery blood and paired VAT and SAT samples during tumor surgery were obtained from 59 CRC patients (tumor stages I-IV) of the ColoCare cohort. Gas chromatography time-of-flight mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry were used to measure 1065 metabolites in adipose tissue (333 identified compounds) and 1810 metabolites in serum (467 identified compounds). Adipose tissue gene expression was measured by using Illumina's HumanHT-12 Expression BeadChips.

RESULTS

Compared with SAT, VAT displayed elevated markers of inflammatory lipid metabolism, free arachidonic acid, phospholipases (PLA2G10), and prostaglandin synthesis-related enzymes (PTGD/PTGS2S). Plasmalogen concentrations were lower in VAT than in SAT, which was supported by lower gene expression of FAR1, the rate-limiting enzyme for ether-lipid synthesis in VAT. Serum sphingomyelin concentrations were inversely correlated (P = 0.0001) with SAT adipose triglycerides. Logistic regression identified lipids in patients' adipose tissues, which were associated with CRC tumor stage.

CONCLUSIONS

As one of the first studies, we comprehensively assessed differences in metabolic, lipidomic, and transcriptomic profiles between paired human VAT and SAT and their association with CRC tumor stage. We identified markers of inflammation in VAT, which supports prior evidence regarding the role of visceral adiposity and cancer.

The development of an ELISA for group IVA phospholipase A2 in human red blood cells

An immunoassay for IVA phospholipase A2 in human red blood cells is described. The assay is a non-competitive sandwich assay in which increasing amounts of the measured protein produce increased luminescence. The antibodies used in the assay are directed against two unique epitopes of the molecule, which sequentially trap and detect the protein. The standard curve covers the range 0.7ng to 23ng/mL (0.07 to 2.3ng/well). The intra-assay and inter-assay coefficients of variation were 9% and 12%, respectively. Evidence is presented that the assay is specific for the alpha paralog of IV PLA2. The assay allows simple and rapid quantification of IVAPLA2 in red blood cell lysates and other biological fluids.

Somatic mutations in arachidonic acid metabolism pathway genes enhance oral cancer post-treatment disease-free survival

The arachidonic acid metabolism (AAM) pathway promotes tumour progression. Chemical inhibitors of AAM pathway prolong post-treatment survival of cancer patients. Here we test whether non-synonymous somatic mutations in genes of this pathway, acting as natural inhibitors, increase post-treatment survival. We identify loss-of-function somatic mutations in 15 (18%) of 84 treatment-naïve oral cancer patients by whole-exome sequencing, which we map to genes of AAM pathway. Patients (n = 53) who survived ≥ 12 months after surgery without recurrence have significantly (P = 0.007) higher proportion (26% versus 3%) of mutations than those who did not (n = 31). Patients with mutations have a significantly (P = 0.003) longer median disease-free survival (24 months) than those without (13 months). Compared with the presence of a mutation, absence of any mutation increases the hazard ratio for death (11.3) significantly (P = 0.018). The inferences are strengthened when we pool our data with The Cancer Genome Atlas (TCGA) data. In patients with AAM pathway mutations, some downstream pathways, such as the PI3K-Akt pathway, are downregulated.

Significance of arachidonic acid in ocular infections and inflammation

Innate immune responses in the cornea mainly play an important role to mobilize multiple interrelated pathways of corneal lipid, which involve in inflammatory corneal diseases. Signaling lipid mediators derived from arachidonic acid (AA) control cell proliferation, apoptosis, metabolism, and migration, are known as eicosanoids, phosphoinositides, sphingolipids, and fatty acids. Emerging evidences have highlighted the implication of lipid mediators in both injury and repair mechanisms in the cornea. Recently, the role of AA and its metabolites to induce proinflammatory mediators and inflammatory cell infiltration in the pathogen-infected cornea and to cause severe keratitis have been revealed. In this review, we focus on the novel roles of AA downstream signaling in the corneal inflammatory diseases and also the biological relevance of AA signaling in the therapeutic strategies for targeting sight-threatening diseases.

Pomegranate and its components as alternative treatment for prostate cancer

Prostate cancer is the second leading cause of cancer deaths in men in the United States. There is a major need for less toxic but yet effective therapies to treat prostate cancer. Pomegranate fruit from the tree Punica granatum has been used for centuries for medicinal purposes and is described as “nature’s power fruit”. Recent research has shown that pomegranate juice (PJ) and/or pomegranate extracts (PE) significantly inhibit the growth of prostate cancer cells in culture. In preclinical murine models, PJ and/or PE inhibit growth and angiogenesis of prostate tumors. More recently, we have shown that three components of PJ, luteolin, ellagic acid and punicic acid together, have similar inhibitory effects on prostate cancer growth, angiogenesis and metastasis. Results from clinical trials are also promising. PJ and/or PE significantly prolonged the prostate specific antigen (PSA) doubling time in patients with prostate cancer. In this review we discuss data on the effects of PJ and PE on prostate cancer. We also discuss the effects of specific components of the pomegranate fruit and how they have been used to study the mechanisms involved in prostate cancer progression and their potential to be used in deterring prostate cancer metastasis.

Production of structured triacylglycerols from microalgae

Structured triacylglycerols (TAGs) were isolated from nine cultivated strains of microalgae belonging to different taxonomic groups, i.e. Audouinella eugena, Balbiania investiens, Myrmecia bisecta, Nannochloropsis limnetica, Palmodictyon varium, Phaeodactylum tricornutum, Pseudochantransia sp., Thorea ramosissima, and Trachydiscus minutus. They were separated and isolated by means of NARP-LC/MS-APCI and chiral LC and the positional isomers and enantiomers of TAGs with two polyunsaturated, i.e. arachidonic (A) and eicosapentaenoic (E) acids and one saturated, i.e. palmitic acid (P) were identified. Algae that produce eicosapentaenoic acid were found to biosynthesize more asymmetrical TAGs, i.e. PPE or PEE, whereas algae which produced arachidonic acid give rise to symmetrical TAGs, i.e. PAP or APA, irrespective of their taxonomical classification. Nitrogen and phosphorus starvation consistently reversed the ratio of asymmetrical and symmetrical TAGs.

Simultaneous tissue profiling of eicosanoid and endocannabinoid lipid families in a rat model of osteoarthritis

We describe a novel LC method for the simultaneous and quantitative profiling of 43 oxylipins including eicosanoids, endocannabinoids, and structurally related bioactive lipids with modified acyl groups. The LC-MS/MS method uses switching at a defined time between negative and positive electrospray ionization modes to achieve optimal detection sensitivity for all the lipids. The validated method is linear over a range of 0.01–5 nmol/g (0.1–50 nmol/g for 2-arachidonoyl glycerol) with intra- and interday precision and accuracy between 1.38 and 26.76% and 85.22 and 114.3%, respectively. The method successfully quantified bioactive lipids in different tissue types in the rat, including spinal cord, dorsal root ganglia (DRGs), knee joint, brain, and plasma. Distinct regional differences in the pattern of lipid measured between tissue types were observed using principle component analysis. The method was applied to analyze tissue samples from an established preclinical rat model of osteoarthritis (OA) pain and showed that levels of 12-hydroxyeicosatetraenoic acid were significantly increased in the OA rat knee joint compared with controls, and that 15-hydroxyeicosatetraenoic acid was significantly increased in the DRGs in the model of OA compared with controls. The developed LC-MS/MS method has the potential to provide detailed pathway profiling in tissues and biofluids where the disruption of bioactive oxylipins may be involved in disease states.

Phospholipase D1 increases Bcl-2 expression during neuronal differentiation of rat neural stem cells

We studied the possible role of phospholipase D1 (PLD1) in the neuronal differentiation, including neurite formation of neural stem cells. PLD1 protein and PLD activity increased during neuronal differentiation. Bcl-2 also increased. Downregulation of PLD1 by transfection with PLD1 siRNA or a dominant-negative form of PLD1 (DN-PLD1) inhibited both neurite outgrowth and Bcl-2 expression. PLD activity was dramatically reduced by a PLCγ (phospholipase Cγ) inhibitor (U73122), a Ca(2+)chelator (BAPTA-AM), and a PKCα (protein kinase Cα) inhibitor (RO320432). Furthermore, treatment with arachidonic acid (AA) which is generated by the action of PLA2 (phospholipase A2) on phosphatidic acid (a PLD1 product), increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, indicating that PLA2 is involved in the differentiation process resulting from PLD1 activation. PGE2 (prostaglandin E2), a cyclooxygenase product of AA, also increased during neuronal differentiation. Moreover, treatment with PGE2 increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, and this effect was inhibited by a PKA inhibitor (Rp-cAMP). As expected, inhibition of p38 MAPK resulted in loss of CREB activity, and when CREB activity was blocked with CREB siRNA, Bcl-2 production also decreased. We also showed that the EP4 receptor was required for the PKA/p38MAPK/CREB/Bcl-2 pathway. Taken together, these observations indicate that PLD1 is activated by PLCγ/PKCα signaling and stimulate Bcl-2 expression through PLA2/Cox2/EP4/PKA/p38MAPK/CREB during neuronal differentiation of rat neural stem cells.

Metabolomics analysis of collagen-induced arthritis in rats and interventional effects of oral tolerance

A serum metabolomics method based on rapid resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (RRLC-Q-TOF-MS) was performed for a holistic evaluation of the metabolic changes of collagen-induced arthritis (CIA) in rats and to assess the interventional effects of type II collagen (CII) in this model. Partial least-squares-discriminant analysis (PLS-DA) was employed to study the metabolic profiling of CIA rats and control rats. Ten metabolites, namely, 12(S)-HHTrE, 12(S)-HEPE, PGE2, TXB2, 12(S)-HETE, LysoPE(16:0), PE(O-18:0/0:0), Lyso-PE(18:2), Lyso-PE(20:4), and Lyso-PC(22:5) were identified as differential metabolites associated with the pathogenesis of CIA. These results suggested that dysregulation of the arachidonic acid (AA) and phospholipid metabolic networks is involved in the pathomechanism of CIA. Differential metabolomics and histopathological analyses demonstrated that CII inhibits the progress of arthritis. Furthermore, the therapeutic effects of CII on CIA may involve regulation of the disordered AA and phospholipid metabolic networks. This metabolomics study provides new insights into the pathogenesis of arthritis and, furthermore, indicates the potential mechanism underlying the significantly increased prevalence of metabolic syndrome, defined as a clustering of cardiovascular disease (CVD) risk factors, in arthritis patients.

Arachidonic acid promotes migration and invasion through a PI3K/Akt-dependent pathway in MDA-MB-231 breast cancer cells

Arachidonic acid (AA) is a common dietary n-6 cis polyunsaturated fatty acid that under physiological conditions is present in an esterified form in cell membrane phospholipids, however it might be present in the extracellular microenvironment. AA and its metabolites mediate FAK activation, adhesion and migration in MDA-MB-231 breast cancer cells. However, it remains to be investigated whether AA promotes invasion and the signal transduction pathways involved in migration and invasion. Here, we demonstrate that AA induces Akt2 activation and invasion in MDA-MB-231 cells. Akt2 activation requires the activity of Src, EGFR, and PIK3, whereas migration and invasion require Akt, PI3K, EGFR and metalloproteinases activity. Moreover, AA also induces NFκB-DNA binding activity through a PI3K and Akt-dependent pathway. Our findings demonstrate, for the first time, that Akt/PI3K and EGFR pathways mediate migration and invasion induced by AA in MDA-MB-231 breast cancer cells.

Bile acids increase alveolar epithelial permeability via mitogen-activated protein kinase, cytosolic phospholipase A2 , cyclooxygenase-2, prostaglandin E2 and junctional proteins

BACKGROUND AND OBJECTIVE

Bile acid (BA) aspiration is associated with various lung diseases. It was hypothesized that BA may induce changes in alveolar epithelium permeability and contribute to the pathogenesis of lung injury.

METHODS

Human alveolar epithelial cells were grown in monolayer and stimulated with a major component of BA, chenodeoxycholic acid (CDCA). Transepithelial electrical resistance (TER) and paracellular fluxes were measured to assess permeability alteration. Prostaglandin E2 ( PGE2 ) production was measured, and its effect on TER and junctional proteins (JP) was also examined. Reverse transcription polymerase chain reaction and Western blots were used to investigate the expression of messenger RNA and JP.

RESULTS

CDCA induced significant p38 and c-Jun N-terminal kinase (JNK) phosphorylation, cytosolic phospholipase A2 (cPLA2 ) and cyclooxygenase-2 (COX-2) messenger RNA expression, PGE2 production, TER reduction and decay of JP (including occludin, zonula occludens-1 (ZO-1) and E-cadherin, in which ZO-1 had maximal change). CDCA also increased paracellular fluxes, which was abolished by dexamethasone. Both CDCA and PGE2 contributed to TER reduction in an identical trend and a dose-response manner. PGE2 also reduced ZO-1 expression, which was similar to that observed by CDCA stimulation. Pretreatment with inhibitors of p38 (SB203580), JNK (SP600125), cPLA2 (mepacrine) and COX-2 (NS398) as well as dexamethasone reversed the CDCA-induced PGE2 production, TER reduction and decay of ZO-1.

CONCLUSIONS

The increase in alveolar permeability was associated with decay of JP. BA may induce permeability alteration through the upregulation of mitogen-activated protein kinase, cPLA2 , COX-2, PGE2 and JP, which may contribute to the pathogenesis of BA-associated lung injury.

Modulation of T-type calcium channels by bioactive lipids

T-type calcium channels (T-channels/CaV3) have unique biophysical properties allowing a calcium influx at resting membrane potential of most cells. T-channels are ubiquitously expressed in many tissues and contribute to low-threshold spikes and burst firing in central neurons as well as to pacemaker activities in cardiac cells. They also emerged as potential targets to treat cancer and hypertension. Regulation of these channels appears complex, and several studies have indicated that CaV3.1, CaV3.2, and CaV3.3 currents are directly inhibited by multiple endogenous lipids independently of membrane receptors or intracellular pathways. These bioactive lipids include arachidonic acid and ω3 poly-unsaturated fatty acids; the endocannabinoid anandamide and other N-acylethanolamides; the lipoamino-acids and lipo-neurotransmitters; the P450 epoxygenase metabolite 5,6-epoxyeicosatrienoic acid; as well as similar molecules with 18-22 carbons in the alkyl chain. In this review, we summarize evidence for direct effects of these signaling molecules, the molecular mechanisms underlying the current inhibition, and the involved chemical features. The impact of this modulation in physiology and pathophysiology is discussed with a special emphasis on pain aspects and vasodilation. Overall, these data clearly indicate that T-current inhibition is an important mechanism by which bioactive lipids mediate their physiological functions.

Correlation between platelet and brain PLA(2) activity

The phospholipase A2 (PLA2) enzymes have been implicated in several neuropsychiatry disorders and activity alterations have been described in brain and platelet. Since brain tissue is not readily available for the measurement of PLA2 activity, it would be of interest to test directly whether PLA2 activities in both tissues are correlated. We performed this task assessing PLA2 activity in platelets and hippocampus collected simultaneously from 19 patients undergoing temporal lobectomy for treatment of refractory epilepsy. Our findings suggest that total PLA2 activity in platelets may reflect the total activity of the enzyme in the brain (rs=0.59, p=0.008). However in our sample no correlations were found between the subgroups of the enzyme in brain and in platelets. This lack of correlations may be due to different effects of drug treatment on the PLA2 subtypes. In face of the difficulty to obtain brain tissues from living patients, further studies with larger drug-free samples are warranted to clarify whether the use of platelets is a reliable strategy to reflect the subtypes of PLA2 activity in the brain.

Critical appraisal of the potential use of cannabinoids in cancer management

Cannabinoids have been attracting a great deal of interest as potential anticancer agents. Originally derived from the plant Cannabis sativa, there are now a number of endo-, phyto- and synthetic cannabinoids available. This review summarizes the key literature to date around the actions, antitumor activity, and mechanisms of action for this broad range of compounds. Cannabinoids are largely defined by an ability to activate the cannabinoid receptors – CB₁ or CB₂. The action of the cannabinoids is very dependent on the exact ligand tested, the dose, and the duration of exposure. Some cannabinoids, synthetic or plant-derived, show potential as therapeutic agents, and evidence across a range of cancers and evidence in vitro and in vivo is starting to be accumulated. Studies have now been conducted in a wide range of cell lines, including glioma, breast, prostate, endothelial, liver, and lung. This work is complemented by an increasing body of evidence from in vivo models. However, many of these results remain contradictory, an issue that is not currently able to be resolved through current knowledge of mechanisms of action. While there is a developing understanding of potential mechanisms of action, with the extracellular signal-regulated kinase pathway emerging as a critical signaling juncture in combination with an important role for ceramide and lipid signaling, the relative importance of each pathway is yet to be determined. The interplay between the intracellular pathways of autophagy versus apoptosis is a recent development that is discussed. Overall, there is still a great deal of conflicting evidence around the future utility of the cannabinoids, natural or synthetic, as therapeutic agents.

Role of arachidonic acid metabolism in Stat5 activation induced by oleic acid in MDA-MB-231 breast cancer cells

Epidemiological studies and animal models suggest an association between high levels of dietary fat intake and an increased risk of breast cancer. In breast cancer cells, the free fatty acid oleic acid (OLA) induces proliferation, migration, invasion and an increase of MMP-9 secretion. However, the role of OLA on Stat5 activation and the participation of COX-2 and LOXs activity in Stat5 activation induced by OLA remain to be investigated. We demonstrate here that stimulation of MDA-MB-231 breast cancer cells with 100 μM OLA induces Stat5 phosphorylation at Tyr-694 and an increase of Stat5-DNA complex formation. The Stat5 DNA-binding activity requires COX-2, LOXs, metalloproteinases and Src activities. In addition, OLA induces cell migration through a Stat5-dependent pathway. In summary, our findings establish that OLA induces cell migration through a Stat5-dependent pathway and that Stat5 activation requires AA metabolites in MDA-MB-231 breast cancer cells.

Arachidonic acid induces an increase of β-1,4-galactosyltransferase I expression in MDA-MB-231 breast cancer cells

Arachidonic acid (AA) is a common dietary n-6 cis polyunsaturated fatty acid that under physiological conditions is present in an esterified form in cell membrane phospholipids, and it might be present in the extracellular microenvironment. AA and its metabolites are implicated in FAK activation and cell migration in MDA-MB-231 breast cancer cells, and an epithelial-to-mesenchymal-like transition process in mammary non-tumorigenic epithelial cells MCF10A. During malignant transformation is present an altered expression of glycosiltransferases, which promote changes on the glycosilation of cell-surface proteins. The β-1,4-galactosyltransferase I (GalT I) is an enzyme that participates in a variety of biological functions including cell growth, migration, and spreading. However, the participation of AA in the regulation of GalT I expression and the role of this enzyme in the cell adhesion process in breast cancer cells remains to be investigated. In the present study, we demonstrate that AA induces an increase of GalT I expression through a PLA2α, Src, ERK1/2, and LOXs activities-dependent pathway in MDA-MB-231 breast cancer cells. Moreover, MDA-MB-231 cells adhere to laminin via GalT I expression and pretreatment of cells with AA induces an increase of cell adhesion to laminin. In conclusion, our findings demonstrate, for the first time, that AA promotes an increase of GalT I expression through an AA metabolism, Src and ERK1/2 activities-dependent pathway, and that GalT I plays a pivotal role in cell adhesion to laminin in MDA-MB-231 breast cancer cells.

Platelet biomarkers in Alzheimer’s disease

The search for diagnostic and prognostic markers in Alzheimer’s disease (AD) has been an area of active research in the last decades. Biochemical markers are correlates of intracerebral changes that can be identified in biological fluids, namely: peripheral blood (total blood, red and white blood cells, platelets, plasma and serum), saliva, urine and cerebrospinal fluid. An important feature of a biomarker is that it can be measured objectively and evaluated as (1) an indicator of disease mechanisms (markers of core pathogenic processes or the expression of downstream effects of these processes), or (2) biochemical responses to pharmacological or therapeutic intervention, which can be indicative of disease modification. Platelets have been used in neuropharmacological models since the mid-fifties, as they share several homeostatic functions with neurons, such as accumulation and release of neurotransmitters, responsiveness to variations in calcium concentration, and expression of membrane-bound compounds. Recent studies have shown that platelets also express several components related to the pathogenesis of AD, in particular to the amyloid cascade and the regulation of oxidative stress: thus they can be used in the search for biomarkers of the disease process. For instance, platelets are the most important source of circulating forms of the amyloid precursor protein and other important proteins such as Tau and glycogen synthase kinase-3B. Moreover, platelets express enzymes involved in membrane homeostasis (e.g., phospholipase A₂), and markers of the inflammatory process and oxidative stress. In this review we summarize the available literature and discuss evidence concerning the potential use of platelet markers in AD.