EET displays anti-inflammatory effects in TNF-alpha stimulated human bronchi: putative role of CPI-17

CYP2J2-mediated metabolism of arachidonic acid in heart: A review of its kinetics, inhibition and role in heart rhythm control

Cytochrome P450 2 J2 (CYP2J2) is primarily expressed extrahepatically and is the predominant epoxygenase in human cardiac tissues. This highlights its key role in the metabolism of endogenous substrates. Significant scientific interest lies in cardiac CYP2J2 metabolism of arachidonic acid (AA), an omega-6 polyunsaturated fatty acid, to regioisomeric bioactive epoxyeicosatrienoic acid (EET) metabolites that show cardioprotective effects including regulation of cardiac electrophysiology. From an in vitro perspective, the accurate characterization of the kinetics of CYP2J2 metabolism of AA including its inhibition and inactivation by drugs could be useful in facilitating in vitro-in vivo extrapolations to predict drug-AA interactions in drug discovery and development. In this review, background information on the structure, regulation and expression of CYP2J2 in human heart is presented alongside AA and EETs as its endogenous substrate and metabolites. The in vitro and in vivo implications of the kinetics of this endogenous metabolic pathway as well as its perturbation via inhibition and inactivation by drugs are elaborated. Additionally, the role of CYP2J2-mediated metabolism of AA to EETs in cardiac electrophysiology will be expounded.

Regulation of soluble epoxide hydrolase in renal-associated diseases: insights from potential mechanisms to clinical researches

In recent years, numerous experimental studies have underscored the pivotal role of soluble epoxide hydrolase (sEH) in renal diseases, demonstrating the reno-protective effects of sEH inhibitors. The nexus between sEH and renal-associated diseases has garnered escalating attention. This review endeavors to elucidate the potential molecular mechanisms of sEH in renal diseases and emphasize the critical role of sEH inhibitors as a prospective treatment modality. Initially, we expound upon the correlation between sEH and Epoxyeicosatrienoic acids (EETs) and also addressing the impact of sEH on other epoxy fatty acids, delineate prevalent EPHX2 single nucleotide polymorphisms (SNPs) associated with renal diseases, and delve into sEH-mediated potential mechanisms, encompassing oxidative stress, inflammation, ER stress, and autophagy. Subsequently, we delineate clinical research pertaining to sEH inhibition or co-inhibition of sEH with other inhibitors for the regulation of renal-associated diseases, covering conditions such as acute kidney injury, chronic kidney diseases, diabetic nephropathy, and hypertension-induced renal injury. Our objective is to validate the potential role of sEH inhibitors in the treatment of renal injuries. We contend that a comprehensive comprehension of the salient attributes of sEH, coupled with insights from clinical experiments, provides invaluable guidance for clinicians and presents promising therapeutic avenues for patients suffering from renal diseases.

Lipidome modulation by dietary omega-3 polyunsaturated fatty acid supplementation or selective soluble epoxide hydrolase inhibition suppresses rough LPS-accelerated glomerulonephritis in lupus-prone mice

Introduction

Lipopolysaccharide (LPS)-accelerated autoimmune glomerulonephritis (GN) in NZBWF1 mice is a preclinical model potentially applicable for investigating lipidome-modulating interventions against lupus. LPS can be expressed as one of two chemotypes: smooth LPS (S-LPS) or rough LPS (R-LPS) which is devoid of O-antigen polysaccharide sidechain. Since these chemotypes differentially affect toll-like receptor 4 (TLR4)-mediated immune cell responses, these differences may influence GN induction.

Methods

We initially compared the effects of subchronic intraperitoneal (i.p.) injection for 5 wk with 1) Salmonella S-LPS, 2) Salmonella R-LPS, or 3) saline vehicle (VEH) (Study 1) in female NZBWF1 mice. Based on the efficacy of R-LPS in inducing GN, we next used it to compare the impact of two lipidome-modulating interventions, ω-3 polyunsaturated fatty acid (PUFA) supplementation and soluble epoxide hydrolase (sEH) inhibition, on GN (Study 2). Specifically, effects of consuming ω-3 docosahexaenoic acid (DHA) (10 g/kg diet) and/or the sEH inhibitor 1-(4-trifluoro-methoxy-phenyl)-3-(1-propionylpiperidin-4-yl) urea (TPPU) (22.5 mg/kg diet ≈ 3 mg/kg/day) on R-LPS triggering were compared.

Results

In Study 1, R-LPS induced robust elevations in blood urea nitrogen, proteinuria, and hematuria that were not evident in VEH- or S-LPS-treated mice. R-LPS-treated mice further exhibited kidney histopathology including robust hypertrophy, hyperplasia, thickened membranes, lymphocytic accumulation containing B and T cells, and glomerular IgG deposition consistent with GN that was not evident in VEH- or SLPS-treated groups. R-LPS but not S-LPS induced spleen enlargement with lymphoid hyperplasia and inflammatory cell recruitment in the liver. In Study 2, resultant blood fatty acid profiles and epoxy fatty acid concentrations reflected the anticipated DHA- and TPPU-mediated lipidome changes, respectively. The relative rank order of R-LPS-induced GN severity among groups fed experimental diets based on proteinuria, hematuria, histopathologic scoring, and glomerular IgG deposition was: VEH/CON< R-LPS/DHA ≈ R-LPS/TPPU<<< R-LPS/TPPU+DHA ≈ R-LPS/CON. In contrast, these interventions had modest-to- negligible effects on R-LPS-induced splenomegaly, plasma antibody responses, liver inflammation, and inflammation-associated kidney gene expression.

Discussion

We show for the first time that absence of O-antigenic polysaccharide in R-LPS is critical to accelerated GN in lupus-prone mice. Furthermore, intervention by lipidome modulation through DHA feeding or sEH inhibition suppressed R-LPS-induced GN; however, these ameliorative effects were greatly diminished upon combining the treatments.

Effect of inflammation on cytochrome P450-mediated arachidonic acid metabolism and the consequences on cardiac hypertrophy

The incidence of heart failure (HF) is generally preceded by cardiac hypertrophy (CH), which is the enlargement of cardiac myocytes in response to stress. During CH, the metabolism of arachidonic acid (AA), which is present in the cell membrane phospholipids, is modulated. Metabolism of AA gives rise to hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) via cytochrome P450 (CYP) ω-hydroxylases and CYP epoxygenases, respectively. A plethora of studies demonstrated the involvement of CYP-mediated AA metabolites in the pathogenesis of CH. Also, inflammation is known to be a characteristic hallmark of CH. In this review, our aim is to highlight the impact of inflammation on CYP-derived AA metabolites and CH. Inflammation is shown to modulate the expression of various CYP ω-hydroxylases and CYP epoxygenases and their respective metabolites in the heart. In general, HETEs such as 20-HETE and mid-chain HETEs are pro-inflammatory, while EETs are characterized by their anti-inflammatory and cardioprotective properties. Several mechanisms are implicated in inflammation-induced CH, including the modulation of NF-κB and MAPK. This review demonstrated the inflammatory modulation of cardiac CYPs and their metabolites in the context of CH and the anti-inflammatory strategies that can be employed in the treatment of CH and HF.

Soluble Epoxide Hydrolase as a Therapeutic Target for Neuropsychiatric Disorders

It has been found that soluble epoxide hydrolase (sEH; encoded by the EPHX2 gene) in the metabolism of polyunsaturated fatty acids (PUFAs) plays a key role in inflammation, which, in turn, plays a part in the pathogenesis of neuropsychiatric disorders. Meanwhile, epoxy fatty acids such as epoxyeicosatrienoic acids (EETs), epoxyeicosatetraenoic acids (EEQs), and epoxyeicosapentaenoic acids (EDPs) have been found to exert neuroprotective effects in animal models of neuropsychiatric disorders through potent anti-inflammatory actions. Soluble expoxide hydrolase, an enzyme present in all living organisms, metabolizes epoxy fatty acids into the corresponding dihydroxy fatty acids, which are less active than the precursors. In this regard, preclinical findings using sEH inhibitors or Ephx2 knock-out (KO) mice have indicated that the inhibition or deficiency of sEH can have beneficial effects in several models of neuropsychiatric disorders. Thus, this review discusses the current findings of the role of sEH in neuropsychiatric disorders, including depression, autism spectrum disorder (ASD), schizophrenia, Parkinson’s disease (PD), and stroke, as well as the potential mechanisms underlying the therapeutic effects of sEH inhibitors.

Discovery of memantyl urea derivatives as potent soluble epoxide hydrolase inhibitors against lipopolysaccharide-induced sepsis

Sepsis, a systemic inflammatory response, caused by pathogenic factors including microorganisms, has high mortality and limited therapeutic approaches. Herein, a new soluble epoxide hydrolase (sEH) inhibitor series comprising a phenyl ring connected to a memantyl moiety via a urea or amide linkage has been designed. A preferential urea pharmacophore that improved the binding properties of the compounds was identified for those series via biochemical assay in vitro and in vivo studies. Molecular docking displayed that 3,5-dimethyl on the adamantyl group in B401 could make van der Waals interactions with residues at a hydrophobic pocket of sEH active site, which might indirectly explain the subnanomolar level activities of memantyl urea derivatives in vitro better than AR-9281. Among them, compound B401 significantly improved the inhibition potency with human and murine sEH IC50 values as 0.4 nM and 0.5 nM, respectively. Although the median survival time of C57BL/6 mice in LPS-induced sepsis model was slightly increased, the survival rate did not reach significant efficacy. Based on safety profile, metabolic stability, pharmacokinetic and in vivo efficacy, B401 demonstrated the proof of potential for this class of memantyl urea-based sEH inhibitors as therapeutic agents in sepsis.

11,12 Epoxyeicosatrienoic Acid Rescues Deteriorated Wound Healing in Diabetes

Epoxyeicosatrienoic acids (EET) facilitate regeneration in different tissues, and their benefit in dermal wound healing has been proven under normal conditions. In this study, we investigated the effect of 11,12 EET on dermal wound healing in diabetes. We induced diabetes by i.p. injection of streptozotocin 2 weeks prior to wound creation on the dorsal side of the mouse ear. 11,12 EET was applied every second day on the wound, whereas the control groups received only solvent. Epithelialization was monitored every second day intravitally up to wound closure. Wounds were stained for VEGF, CD31, TGF-β, TNF-α, SDF-1α, NF-κB, and Ki-67, and fibroblasts were counted after hematoxylin-eosin stain on days 3, 6, 9, and 16 after wounding. After induction of diabetes, wounds closed on day 13.00 ± 2.20 standard deviation (SD). Local 11,12 ETT application improved wound closure significantly to day 8.40 ± 1.39 SD. EET treatment enhanced VEGF and CD31 expression in wounds on day 3. It also seemed to raise TNF-α level on all days investigated as well as TGF-β level on days 3 and 6. A decrease in NF-κB could be observed on days 9 and 16 after EET application. The latter findings were not significant. SDF-1α expression was not influenced by EET application, and Ki-67 was significantly less in the EET group on day 9 after EET application. The number of fibroblasts was significantly increased on day 9 after the 11,12 EET application. 11,12 EET improve deteriorated wound healing in diabetes by enhancing neoangiogenesis, especially in the early phase of wound healing. Furthermore, they contribute to the dissolution of the initial inflammatory reaction, allowing the crucial transition from the inflammatory to proliferative phase in wound healing.

The Role of Epoxyeicosatrienoic Acids in Cardiac Remodeling

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by cytochrome P450 (CYP) epoxygenases, which include four regioisomers: 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET. Each of them possesses beneficial effects against inflammation, fibrosis, and apoptosis, which could combat cardiovascular diseases. Numerous studies have demonstrated that elevation of EETs by overexpression of CYP2J2, inhibition of sEH, or treatment with EET analogs showed protective effects in various cardiovascular diseases, including hypertension, myocardial infarction, and heart failure. As is known to all, cardiac remodeling is the major pathogenesis of cardiovascular diseases. This review will begin with the introduction of EETs and their protective effects in cardiovascular diseases. In the following, the roles of EETs in cardiac remodeling, with a particular emphasis on myocardial hypertrophy, apoptosis, fibrosis, inflammation, and angiogenesis, will be summarized. Finally, it is suggested that upregulation of EETs is a potential therapeutic strategy for cardiovascular diseases. The EET-related drug development against cardiac remodeling is also discussed, including the overexpression of CYP2J2, inhibition of sEH, and the analogs of EET.

From Submerged Cultures to 3D Cell Culture Models: Evolution of Nasal Epithelial Cells in Asthma Research and Virus Infection

Understanding the response to viral infection in the context of respiratory diseases is of significant importance. Recently, there has been more focus on the role of the nasal epithelium in disease modeling. Here, we provide an overview of different submerged, organotypic 3D and spheroid cell culture models of nasal epithelial cells, which were used to study asthma and allergy with a special focus on virus infection. In detail, this review summarizes the importance, benefits, and disadvantages of patient-derived cell culture models of nasal- and bronchial epithelial cells, including a comparison of these cell culture models and a discussion on why investigators should consider using nasal epithelial cells in their research. Exposure experiments, simple virus transduction analyses as well as genetic studies can be performed in these models, which may provide first insights into the complexity of molecular signatures and may open new doors for drug discovery and biomarker research.

Clinical Relevance of the Anti-inflammatory Effects of Roflumilast on Human Bronchus: Potentiation by a Long-Acting Beta-2-Agonist

Background: Roflumilast is an option for treating patients with severe COPD and frequent exacerbations despite optimal therapy with inhaled drugs. The present study focused on whether the phosphodiesterase (PDE) 4 inhibitor roflumilast and its active metabolite roflumilast N-oxide affect the release of tumor necrosis factor (TNF)-α and chemokines by lipopolysaccharide (LPS)-stimulated human bronchial explants. We also investigated the interactions between roflumilast, roflumilast N-oxide and the β₂-agonist formoterol with regard to cytokine release by the bronchial preparations.

Methods: Bronchial explants from resected lungs were incubated with roflumilast, roflumilast N-oxide and/or formoterol and then stimulated with LPS. An ELISA was used to measure levels of TNF-α and chemokines in the culture supernatants.

Results: At a clinically relevant concentration (1 nM), roflumilast N-oxide and roflumilast consistently reduced the release of TNF-α, CCL2, CCL3, CCL4, CCL5 and CXCL9 (but not CXCL1, CXCL5, CXCL8 and IL-6) from human bronchial explants. Formoterol alone decreased the release of TNF-α, CCL2, and CCL3. The combination of formoterol with roflumilast (1 nM) was more potent than roflumilast alone for inhibiting the LPS-induced release of TNF-α, CCL2, CCL3, CCL4, and CXCL9 by the bronchial explants.

Conclusions: At a clinically relevant concentration, roflumilast N-oxide and its parent compound, roflumilast, reduced the LPS-induced production of TNF-α and chemokines involved in monocyte and T-cell recruitment but did not alter the release of chemokines involved in neutrophil recruitment. The combination of formoterol with roflumilast enhanced the individual drugs’ anti-inflammatory effects.

NCS 613, a Potent PDE4 Inhibitor, Displays Anti-Inflammatory and Anti-Proliferative Properties on A549 Lung Epithelial Cells and Human Lung Adenocarcinoma Explants

Chronic inflammation is a deleterious process occurring in several pulmonary diseases; it is a driving force promoting tumorigenesis. By regulating local cyclic nucleotide concentration, cyclic nucleotide phosphodiesterases (PDE) govern important biological processes, including inflammation and proliferation. The aim of this study was to investigate the anti-inflammatory and anti-proliferative effects of NCS 613, a specific PDE4 inhibitor, on TNFα-treated human lung adenocarcinoma cell line (A549) and on human lung adenocarcinoma explants. PDE4 isoforms and inflammatory pathways mediated by p38 MAPK, ERK1/2, and IκBα were analyzed by Western blot and immunostainings. Proliferation were performed using [³H]-thymidine incorporation under different experimental conditions. TNFα-stimulation increased p38 MAPK phosphorylation and NF-κB translocation into the nucleus, which was abolished by NCS 613 treatment. Concomitantly, NCS 613 restores IκBα detection level in human adenocarcinoma. An IC₅₀ value of 8.5 μM was determined for NCS 613 on anti-proliferative properties while ERK1/2 signaling was down-regulated in A549 cells and lung adenocarcinoma explants. These findings shed light on PDE4 signaling as a key regulator of chronic inflammation and cancer epithelial cell proliferation. It suggests that PDE4 inhibition by NCS 613 represent potential and interesting strategy for therapeutic intervention in tackling chronic inflammation and cell proliferation.

Soluble Epoxide Hydrolase Inhibition in Liver Diseases: A Review of Current Research and Knowledge Gaps

Emerging evidence suggests that soluble epoxide hydrolase (sEH) inhibition is a valuable therapeutic strategy for the treatment of numerous diseases, including those of the liver. sEH rapidly degrades cytochrome P450-produced epoxygenated lipids (epoxy-fatty acids), which are synthesized from omega-3 and omega-6 polyunsaturated fatty acids, that generally exert beneficial effects on several cellular processes. sEH hydrolysis of epoxy-fatty acids produces dihydroxy-fatty acids which are typically less biologically active than their parent epoxide. Efforts to develop sEH inhibitors have made available numerous compounds that show therapeutic efficacy and a wide margin of safety in a variety of different diseases, including non-alcoholic fatty liver disease, liver fibrosis, portal hypertension, and others. This review summarizes research efforts which characterize the applications, underlying effects, and molecular mechanisms of sEH inhibitors in these liver diseases and identifies gaps in knowledge for future research.

[Extracellular molecules controlling the contraction of airway smooth muscle and their potential contribution to bronchial hyperresponsiveness]

INTRODUCTION

A significant portion of symptoms in some lung diseases results from an excessive constriction of airways due to the contraction of smooth muscle and bronchial hyperresponsiveness. A better understanding of the extracellular molecules that control smooth muscle contractility is necessary to identify the underlying causes of the problem.

STATE OF KNOWLEDGE

Almost a hundred molecules, some of which newly identified, influence the contractility of airway smooth muscle. While some molecules activate the contraction, others activate the relaxation, thus acting directly as bronchoconstrictors and bronchodilators, respectively. Other molecules do not affect contraction directly but rather influence it indirectly by modifying the effect of bronchoconstrictors and bronchodilators. These are called bronchomodulators. Some of these bronchomodulators increase the contractile effect of bronchoconstrictors and could thus contribute to bronchial hyperresponsiveness.

PROSPECTS

Considering the high number of molecules potentially involved, as well as the level of functional overlap between some of them, identifying the extracellular molecules responsible for excessive airway constriction in a patient is a major contemporary challenge.

Role of epoxyeicosatrienoic acids in the lung

Epoxyeicosatrienoic acids (EETs) are synthetized from arachidonic acid by the action of members of the CYP2C and CYP2J subfamilies of cytochrome P450 (CYPs). The effects of EETs on cardiovascular function, the nervous system, the kidney and metabolic disease have been reviewed. In the lungs, the presence of these CYPs and EETs has been documented. In general, EETs play a beneficial role in this essential tissue. Among the most important effects of EETs in the lungs are the induction of vasorelaxation in the bronchi, the stimulation of Ca²⁺-activated K⁺ channels, the induction of vasoconstriction of pulmonary arteries, anti-inflammatory effects induced by asthma, and protection against infection or exposure to chemical substances such as cigarette smoke. EETs also participate in tissue regeneration, but on the downside, they are possibly involved in the progression of lung cancer. More research is necessary to design therapies with EETs for the treatment of lung disease.

ZDHXB-101 (3',5-Diallyl-2, 4'-dihydroxy-[1,1'-biphen-yl]-3,5'-dicarbaldehyde) protects against airway remodeling and hyperresponsiveness via inhibiting both the activation of the mitogen-activated protein kinase and the signal transducer and activator of transcription-3 signaling pathways

Airway remodeling consists of the structural changes of airway walls, which is often considered the result of longstanding airway inflammation, but it may be present to an equivalent degree in the airways of children with asthma, raising the need for early and specific therapeutic interventions. The arachidonic acid cytochrome P-450 (CYP) pathway has thus far received relatively little attention in its relation to asthma. In this study, we studied the inhibition of soluble epoxide hydrolase (sEH) on airway remodeling and hyperresponsiveness (AHR) in a chronic asthmatic model which long-term exposure to antigen over a period of 12 weeks. The expression of sEH and CYP2J2, the level of 14, 15-epoxyeicosatrienoic acids (EETs), airway remodeling, hyperresponsiveness and inflammation were analyzed to determine the inhibition of sEH. The intragastric administration of 3 or 10 mg/kg ZDHXB-101, which is a structural derivative of natural product honokiol and a novel soluble epoxide hydrolase (sEH) inhibitor, daily for 9 weeks significantly increased the level of 14, 15-EETs by inhibiting the expression of sEH and increasing the expression of CYP2J2 in lung tissues. ZDHXB-101 reduced the expression of remodeling-related markers such as interleukin (IL)-13, IL-17, MMP-9 N-cadherin, α-smooth muscle actin, S100A4, Twist, goblet cell metaplasia, and collagen deposition in the lung tissue or in bronchoalveolar lavage fluid. Moreover, ZDHXB-101 alleviated AHR, which is an indicator that is used to evaluate the airway remodeling function. The inhibitory effects of ZDHXB-101 were demonstrated to be related to its direct inhibition of the extracellular signal-regulated kinase (Erk1/2) phosphorylation, as well as inhibition of c-Jun N-terminal kinases (JNK) and the signal transducer and activator of transcription-3 (STAT3) signal transduction. These findings first revealed the anti-remodeling potential of ZDHXB-101 lead in chronic airway disease.

Time-resolved phosphoproteomic analysis elucidates hepatic 11,12-Epoxyeicosatrienoic acid signaling pathways

Epoxyeicosatrienoic acids (EETs) are potent lipid mediators with well-established effects in vascular tissues. Recent studies indicated an emerging role of these eicosanoids in metabolic diseases and the EET signaling pathway was shown to be involved in hepatic insulin sensitivity. However, compared to vascular tissues, there is only limited knowledge about the underlying signaling pathways in the liver. Therefore, we employed an LC-MS/MS-based time-resolved phosphoproteomics approach to characterize 11,12-EET-mediated signaling events in the liver cell line Hepa 1-6. 11,12-EET treatment resulted in the time-dependent regulation of phosphopeptides involved in processes as yet unknown to be affected by EETs, including RNA processing, splicing and translation regulation. Pathway analysis combined with western blot-based validation revealed enhanced AKT/mTOR/p70S6K signaling as demonstrated by increased acute phosphorylation of AKT (Ser473) and p70S6K (Thr389). In addition, 11,12-EET treatment led to differential regulation of phosphopeptides including important mediators of the DNA damage response and we observed a prolonged induction of the etoposide-induced DNA damage marker γH2AX in response to 11,12-EET. In summary, our findings extend current knowledge of 11,12-EET signaling events and emphasize the importance of the AKT/mTOR/p70S6K pathway in hepatic 11,12-EET signaling. Based on the results presented in this study, we furthermore propose a novel role of EET signaling in the regulation of the DNA damage response.

Oxidized Lipids in Persistent Pain States

Chemotherapy, nerve injuries, or diseases like multiple sclerosis can cause pathophysiological processes of persistent and neuropathic pain. Thereby, the activation threshold of ion channels is reduced in peripheral sensory neurons to normally noxious stimuli like heat, cold, acid, or mechanical due to sensitization processes. This leads to enhanced neuronal activity, which can result in mechanical allodynia, cold allodynia, thermal hyperalgesia, spontaneous pain, and may initiate persistent and neuropathic pain. The treatment options for persistent and neuropathic pain patients are limited; for about 50% of them, current medication is not efficient due to severe side effects or low response to the treatment. Therefore, it is of special interest to find additional treatment strategies. One approach is the control of neuronal sensitization processes. Herein, signaling lipids are crucial mediators and play an important role during the onset and maintenance of pain. As preclinical studies demonstrate, lipids may act as endogenous ligands or may sensitize transient receptor potential (TRP)-channels. Likewise, they can cause enhanced activity of sensory neurons by mechanisms involving G-protein coupled receptors and activation of intracellular protein kinases. In this regard, oxidized metabolites of the essential fatty acid linoleic acid, 9- and 13-hydroxyoctadecadienoic acid (HODE), their dihydroxy-metabolites (DiHOMEs), as well as epoxides of linoleic acid (EpOMEs) and of arachidonic acid (EETs), as well as lysophospholipids, sphingolipids, and specialized pro-resolving mediators (SPMs) have been reported to play distinct roles in pain transmission or inhibition. Here, we discuss the underlying molecular mechanisms of the oxidized linoleic acid metabolites and eicosanoids. Furthermore, we critically evaluate their role as potential targets for the development of novel analgesics and for the treatment of persistent or neuropathic pain.

Effect Of Dual sEH/COX-2 Inhibition on Allergen-Induced Airway Inflammation

Arachidonic acid metabolites resulting from the cyclooxygenase (COX), lipoxygenase, and cytochrome P450 oxidase enzymatic pathways play pro- and anti-inflammatory roles in allergic airway inflammation (AAI) and asthma. Expression of COX-2 and soluble epoxide hydrolase (sEH) are elevated in allergic airways and their enzymatic products (e.g., prostaglandins and diols of epoxyeicosatrienoic acids, respectively) have been shown to participate in the pathogenesis of AAI. Here, we evaluated the outcome of inhibiting the COX-2 and sEH enzymatic pathways with a novel dual inhibitor, PTUPB, in A. alternata-induced AAI. Allergen-challenged mice were administered with 10 or 30 mg/kg of PTUPB, celecoxib (selective COX-2 inhibitor), t-TUCB (selective sEH inhibitor) or vehicle daily by gavage and evaluated for various features of AAI. PTUPB and t-TUCB at 30 mg/kg, but not celecoxib, inhibited eosinophilic infiltration and significantly increased levels of anti-inflammatory EETs in the lung tissue of allergen-challenged mice. t-TUCB significantly inhibited allergen-induced IL-4 and IL-13, while a less pronounced reduction was noted with PTUPB and celecoxib. Additionally, t-TUCB markedly inhibited eotaxin-2, an eosinophil-specific chemokine, which was only marginally reduced by PTUPB and remained elevated in celecoxib-treated mice. PTUPB or t-TUCB administration reversed allergen-induced reduction in levels of various lipid mediators in the lungs, with only a minimal effect noted with celecoxib. Despite the anti-inflammatory effects, PTUPB or t-TUCB did not reduce allergen-induced airway hyperresponsiveness (AHR). However, development of structural changes in the allergic airways, such as mucus hypersecretion and smooth muscle hypertrophy, was significantly inhibited by both inhibitors. Celecoxib, on the other hand, inhibited only airway smooth muscle hypertrophy, but not mucus hypersecretion. In conclusion, dual inhibition of COX-2 and sEH offers no additional advantage relative to sEH inhibition alone in attenuating various features associated with A. alternata-induced AAI, while COX-2 inhibition exerts only moderate or no effect on several of these features. Dual sEH/COX-2 inhibition may be useful in treating conditions where eosinophilic inflammation co-exists with pain-associated inflammation.

Eicosanoid Profile of Influenza A Virus Infected Pigs

Respiratory tract infections caused by the Influenza A virus (IAV) are a worldwide problem for human and animal health. Within this study, we analyzed the impact of IAV infection on the immune-related lipidome (eicosanoids) of the pig as new infection model. For this purpose, we performed HPLC-MS/MS using dynamic multiple reaction monitoring and analyzed lung, spleen, blood plasma and bronchoalveolar lavages. IAV infection leads to collective changes in the levels of the analyzed hydroxyeicosatrienoic acids (HETEs), hydroxydocosahexaenoic acids (HDHAs) and epoxyeicosatrienoic acids (EETs), and moreover, unique eicosanoid changes in several sample types, even under mild infection conditions. In accordance with different mouse infection studies, we observed infection-related patterns for 12-HETE, 15-HETE and 17-HDHA, which seem to be common for IAV infection. Using a long-term approach of 21 days we established an experimental setup that can be used also for bacterial-viral coinfection experiments.

Augmented Pla2g4c/Ptgs2/Hpgds axis in bronchial smooth muscle tissues of experimental asthma

Rationale

Augmented smooth muscle contractility of the airways is one of the causes of airway hyperresponsiveness in asthmatics. However, the mechanism of the altered properties of airway smooth muscle cells is not well understood.

Objectives

To identify differentially expressed genes (DEGs) related to the bronchial smooth muscle (BSM) hyper-contractility in a murine asthma model.

Methods

The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Transcriptomic profiles were generated by microarray analysis of BSM tissues from the OA-challenged and control animals, and KEGG (Kyoto Encyclopedia of Genes and Genomes) Pathway Analysis was applied.

Measurements and main results

Tension study showed a BSM hyperresponsiveness to acetylcholine (ACh) in the OA-challenged mice. A total of 770 genes were differentially expressed between the OA-challenged and control animals. Pathway analysis showed a significant change in arachidonic acid (AA) metabolism pathway in BSM tissues of the OA-challenged mice. Validation of DEGs by quantitative RT-PCR showed a significant increase in PLA₂ group 4c (Pla2g4c)/COX-2 (Ptgs2)/PGD₂ synthase 2 (Hpgds) axis. PGD₂ level in bronchoalveolar fluids of the OA-challenged mice was significantly increased. A 24-h incubation of BSM tissues with PGD₂ caused a hyperresponsiveness to ACh in naive control mice.

Conclusions

AA metabolism is shifted towards PGD₂ production in BSM tissues of asthma. Increased PGD₂ level in the airways might be a cause of the BSM hyperresponsiveness in asthma.

Posttranslational regulation of CYP2J2 by nitric oxide

Nitric oxide (NO) is an essential signaling molecule in the body, regulating numerous biological processes. Beside its physiological roles, NO affects drug metabolism by modulating the activity and/or expression of cytochrome P450 enzymes. Previously, our lab showed that NO generation caused by inflammatory stimuli results in CYP2B6 degradation via the ubiquitin-proteasome pathway. In the current study, we tested the NO-mediated regulation of CYP2J2 that metabolizes arachidonic acids to bioactive epoxyeicosatrienoic acids, as well as therapeutic drugs such as astemizole and ebastine. To investigate the effects of NO on CYP2J2 expression and activity, Huh7 cells stably transduced with CYP2J2 with a C-terminal V5 tag were treated with dipropylenetriamine-NONOate (DPTA), a NO donor. The level of CYP2J2 proteins were decreased in a time- and concentration-dependent manner, and the activity was also rapidly inhibited. However, mRNA expression was not altered and the protein synthesis inhibitor cycloheximide did not attenuate DPTA-mediated downregulation of CYP2J2. Removal of DPTA from the culture media quickly restored the activity of remaining CYP2J2, and no further CYP2J2 degradation occurred. To determine the mechanism of CYP2J2 down-regulation by NO, cells were treated with DPTA in the presence or absence of protease inhibitors including proteasomal, lysosomal and calpain inhibitors. Remarkably, the down-regulation of CYP2J2 by NO was attenuated by calpeptin, a calpain inhibitor. However, other calpain inhibitors or calcium chelator show no inhibitory effects on the degradation. The proteasome inhibitor bortezomib showed small but significant restoration of CYP2J2 levels although stimulated ubiquitination of CYP2J2 was not detected. In conclusion, these data suggest that NO regulates CYP2J2 posttranslationally and NO-evoked CYP2J2 degradation undergoes ubiquitin-independent proteasomal degradation pathway unlike CYP2B6.

Metabolic/inflammatory/vascular comorbidity in psychiatric disorders; soluble epoxide hydrolase (sEH) as a possible new target

The common and severe psychiatric disorders, including major depressive disorder (MDD) and bipolar disorder (BD), are associated with inflammation, oxidative stress and changes in peripheral and brain lipid metabolism. Those pathways are implicated in the premature development of vascular and metabolic comorbidities, which account for considerable morbidity and mortality, including increased dementia risk. During endoplasmic reticulum stress, the soluble epoxide hydrolase (sEH) enzyme converts anti-inflammatory fatty acid epoxides generated by cytochrome p450 enzymes into their corresponding and generally less anti-inflammatory, or even pro-inflammatory, diols, slowing the resolution of inflammation. The sEH enzyme and its oxylipin products are elevated post-mortem in MDD, BD and schizophrenia. Preliminary clinical data suggest that oxylipins increase with symptoms in seasonal MDD and anorexia nervosa, requiring confirmation in larger studies and other cohorts. In rats, a soluble sEH inhibitor mitigated the development of depressive-like behaviors. We discuss sEH inhibitors under development for cardiovascular diseases, post-ischemic brain injury, neuropathic pain and diabetes, suggesting new possibilities to address the mood and cognitive symptoms of psychiatric disorders, and their most common comorbidities.

Human Pulmonary 3D Models For Translational Research

Lung diseases belong to the major causes of death worldwide. Recent innovative methodological developments now allow more and more for the use of primary human tissue and cells to model such diseases. In this regard, the review covers bronchial air-liquid interface cultures, precision cut lung slices as well as ex vivo cultures of explanted peripheral lung tissue and de-/re-cellularization models. Diseases such as asthma or infections are discussed and an outlook on further areas for development is given. Overall, the progress in ex vivo modeling by using primary human material could make translational research activities more efficient by simultaneously fostering the mechanistic understanding of human lung diseases while reducing animal usage in biomedical research.

Soluble epoxide hydrolase as a therapeutic target for pain, inflammatory and neurodegenerative diseases

Eicosanoids are biologically active lipid signaling molecules derived from polyunsaturated fatty acids. Many of the actions of eicosanoid metabolites formed by cyclooxygenase and lipoxygenase enzymes have been characterized, however, the epoxy-fatty acids (EpFAs) formed by cytochrome P450 enzymes are newly described by comparison. The EpFA metabolites modulate a diverse set of physiologic functions that include inflammation and nociception among others. Regulation of EpFAs occurs primarily via release, biosynthesis and enzymatic transformation by the soluble epoxide hydrolase (sEH). Targeting sEH with small molecule inhibitors has enabled observation of the biological activity of the EpFAs in vivo in animal models, greatly contributing to the overall understanding of their role in the inflammatory response. Their role in modulating inflammation has been demonstrated in disease models including cardiovascular pathology and inflammatory pain, but extends to neuroinflammation and neuroinflammatory disease. Moreover, while EpFAs demonstrate activity against inflammatory pain, interestingly, this action extends to blocking chronic neuropathic pain as well. This review outlines the role of modulating sEH and the biological action of EpFAs in models of pain and inflammatory diseases.

TNFα enhances force generation in airway smooth muscle

Airway inflammation is a hallmark of asthma, triggering airway smooth muscle (ASM) hyperreactivity and airway remodeling. TNFα increases both agonist-induced cytosolic Ca2+ concentration ([Ca2+]cyt) and force in ASM. The effects of TNFα on ASM force may also be due to an increase in Ca2+ sensitivity, cytoskeletal remodeling, and/or changes in contractile protein content. We hypothesized that 24 h of exposure to TNFα increases ASM force by changing actin and myosin heavy chain (MyHC) content and/or polymerization. Porcine ASM strips were permeabilized with 10% Triton X-100, and force was measured in response to increasing concentrations of Ca2+ (pCa 9.0 to 4.0) in control and TNFα-treated groups. Relative phosphorylation of the regulatory myosin light chain (p-MLC) and total actin, MLC, and MyHC concentrations were quantified at pCa 9.0, 6.1, and 4.0. Actin polymerization was quantified by the ratio of filamentous to globular actin at pCa 9.0 and 4.0. For determination of total cross-bridge formation, isometric ATP hydrolysis rate at pCa 4.0 was measured using an enzyme-coupled NADH-linked fluorometric technique. Exposure to TNFα significantly increased force across the range of Ca2+ activation but did not affect the intrinsic Ca2+ sensitivity of force generation. The TNFα-induced increase in ASM force was associated with an increase in total actin, MLC, and MyHC content, as well as an increase in actin polymerization and an increase in maximum isometric ATP hydrolysis rate. The results of this study support our hypothesis that TNFα increases force generation in ASM by increasing the number of contractile units (actin-myosin content) contributing to force generation.

Cigarette Smoke-Induced Pulmonary Inflammation and Autophagy Are Attenuated in Ephx2-Deficient Mice

Cigarette smoke (CS) increases the risk of chronic obstructive pulmonary disease (COPD) by causing inflammation, emphysema, and reduced lung function. Additionally, CS can induce autophagy which contributes to COPD. Arachidonic acid-derived epoxyeicosatrienoic acids (EETs) have promising anti-inflammatory properties that may protect the heart and liver by regulating autophagy. For this reason, the effect of decreased soluble epoxide hydrolase (sEH, Ephx2)-mediated EET hydrolysis on inflammation, emphysema, lung function, and autophagy was here studied in CS-induced COPD in vivo. Adult male wild-type (WT) C57BL/6J and Ephx2^−/− mice were exposed to air or CS for 12 weeks, and lung inflammatory responses, air space enlargement (emphysema), lung function, and autophagy were assessed. Lungs of Ephx2^−/− mice had a less pronounced inflammatory response and less autophagy with mild distal airspace enlargement accompanied by restored lung function and steady weight gain. These findings support the idea that Ephx2 may hold promise as a therapeutic target for COPD induced by CS, and it may be protective property by inhibiting autophagy.

Pseudomonas aeruginosa sabotages the generation of host proresolving lipid mediators

Recurrent Pseudomonas aeruginosa infections coupled with robust, damaging neutrophilic inflammation characterize the chronic lung disease cystic fibrosis (CF). The proresolving lipid mediator, 15-epi lipoxin A₄ (15-epi LXA₄), plays a critical role in limiting neutrophil activation and tissue inflammation, thus promoting the return to tissue homeostasis. Here, we show that a secreted P. aeruginosa epoxide hydrolase, cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), can disrupt 15-epi LXA₄ transcellular biosynthesis and function. In the airway, 15-epi LXA₄ production is stimulated by the epithelial-derived eicosanoid 14,15-epoxyeicosatrienoic acid (14,15-EET). Cif sabotages the production of 15-epi LXA₄ by rapidly hydrolyzing 14,15-EET into its cognate diol, eliminating a proresolving signal that potently suppresses IL-8-driven neutrophil transepithelial migration in vitro. Retrospective analyses of samples from patients with CF supported the translational relevance of these preclinical findings. Elevated levels of Cif in bronchoalveolar lavage fluid were correlated with lower levels of 15-epi LXA₄, increased IL-8 concentrations, and impaired lung function. Together, these findings provide structural, biochemical, and immunological evidence that the bacterial epoxide hydrolase Cif disrupts resolution pathways during bacterial lung infections. The data also suggest that Cif contributes to sustained pulmonary inflammation and associated loss of lung function in patients with CF.

14,15-Epoxyeicosatrienoic acid suppresses cigarette smoke condensate-induced inflammation in lung epithelial cells by inhibiting autophagy

Epoxyeicosatrienoic acids (EETs) are metabolic products of free arachidonic acid, which are produced through cytochrome P-450 (CYP) epoxygenases. EETs have anti-inflammatory, antiapoptotic, and antioxidative activities. However, the effect of EETs on cigarette smoke-induced lung inflammation is not clear. Autophagy is believed to be involved in the pathogenesis of chronic obstructive pulmonary disease. In addition, nuclear erythroid-related factor 2 (Nrf2), a transcription factor that regulates many antioxidant genes, is thought to regulate antioxidant defenses in several lung diseases. In addition, interaction between EETs, autophagy, and Nrf2 has been reported. The aim of this study was to explore the effect of 14,15-EET on cigarette smoke condensate (CSC)-induced inflammation in a human bronchial epithelial cell line (Beas-2B), and to determine whether the underlying mechanisms involved in the regulation of Nrf2 through inhibition of autophagy. Autophagy and expression of autophagy signaling pathway proteins (LC3B, p62, PI3K, Akt, p-Akt, and p-mTOR) and anti-inflammatory proteins (Nrf2 and HO-1) were assessed via Western blot analysis. Autophagosomes and autolysosomes were detected by adenoviral mRFP-GFP-LC3 transfection. Inflammatory factors (IL-6, IL-8, and MCP-1) were detected by ELISA. Lentiviral vectors carrying p62 short hairpin RNA were used to interfere with p62 expression to evaluate the effect of p62 on Nrf2 expression. Nrf2 expression was determined through immunocytochemistry. 14,15-EET treatment resulted in a significant reduction in IL-6, IL-8, and MCP-1 secretion, and increased accumulation of Nrf2 and expression of HO-1. In addition, 14,15-EET inhibited CSC-induced autophagy in Beas-2B cells. The mechanism of the anti-inflammatory effect of 14,15-EET involved inhibition of autophagy and an increase in p62 levels, followed by translocation of Nrf2 into the nucleus, which then upregulated expression of the antioxidant enzyme HO-1. 14,15-EET protects against CSC-induced lung inflammation by promoting accumulation of Nrf2 via inhibition of autophagy.

Ingestion of the epoxide hydrolase inhibitor AUDA modulates immune responses of the mosquito, Culex quinquefasciatus during blood feeding

Epoxide hydrolases (EHs) are enzymes that play roles in metabolizing xenobiotic epoxides from the environment, and in regulating lipid signaling molecules, such as juvenile hormones in insects and epoxy fatty acids in mammals. In this study we fed mosquitoes with an epoxide hydrolase inhibitor AUDA during artificial blood feeding, and we found the inhibitor increased the concentration of epoxy fatty acids in the midgut of female mosquitoes. We also observed ingestion of AUDA triggered early expression of defensin A, cecropin A and cecropin B2 at 6 h after blood feeding. The expression of cecropin B1 and gambicin were not changed more than two fold compared to controls. The changes in gene expression were transient possibly because more than 99% of the inhibitor was metabolized or excreted at 42 h after being ingested. The ingestion of AUDA also affected the growth of bacteria colonizing in the midgut, but did not affect mosquito longevity, fecundity and fertility in our laboratory conditions. When spiked into the blood, EpOMEs and DiHOMEs were as effective as the inhibitor AUDA in reducing the bacterial load in the midgut, while EETs rescued the effects of AUDA. Our data suggest that epoxy fatty acids from host blood are immune response regulators metabolized by epoxide hydrolases in the midgut of female mosquitoes, inhibition of which causes transient changes in immune responses, and affects growth of microbes in the midgut.

Effects of Cigarette Smoke, Cessation, and Switching to Two Heat-Not-Burn Tobacco Products on Lung Lipid Metabolism in C57BL/6 and Apoe-/- Mice-An Integrative Systems Toxicology Analysis

The impact of cigarette smoke (CS), a major cause of lung diseases, on the composition and metabolism of lung lipids is incompletely understood. Here, we integrated quantitative lipidomics and proteomics to investigate exposure effects on lung lipid metabolism in a C57BL/6 and an Apolipoprotein E-deficient (Apoe(-/-)) mouse study. In these studies, mice were exposed to high concentrations of 3R4F reference CS, aerosol from potential modified risk tobacco products (MRTPs) or filtered air (Sham) for up to 8 months. The 2 assessed MRTPs, the prototypical MRTP for C57BL/6 mice and the Tobacco Heating System 2.2 for Apoe(-/-) mice, utilize "heat-not-burn" technologies and were each matched in nicotine concentrations to the 3R4F CS. After 2 months of CS exposure, some groups were either switched to the MRTP or underwent cessation. In both mouse strains, CS strongly affected several categories of lung lipids and lipid-related proteins. Candidate surfactant lipids, surfactant proteins, and surfactant metabolizing proteins were increased. Inflammatory eicosanoids, their metabolic enzymes, and several ceramide classes were elevated. Overall, CS induced a coordinated lipid response controlled by transcription regulators such as SREBP proteins and supported by other metabolic adaptations. In contrast, most of these changes were absent in the mice exposed to the potential MRTPs, in the cessation group, and the switching group. Our findings demonstrate the complex biological response of the lungs to CS exposure and support the benefits of cessation or switching to a heat-not-burn product using a design such as those employed in this study.

Resolvin E1 normalizes contractility, Ca2+ sensitivity and smooth muscle cell migration rate in TNF-α- and IL-6-pretreated human pulmonary arteries

Pulmonary hypertension (PH) is a rare disease in which pathophysiology is characterized by an increase in proinflammatory mediators, chronic endothelial dysfunctions, and a high migration rate of smooth muscle cells (SMC). Over the course of the last decade, various treatments have been proposed to relax the pulmonary arteries, none of which have been effective in resolving PH. Our hypothesis is that artery-relaxing drugs are not the long-term solution, but rather the inhibition of tissue inflammation, which underlies human pulmonary artery (HPA) dysfunctions that lead to abnormal vasoconstriction. The goal of the present study was to assess the anti-inflammatory effects of resolvin E1 (RvE1) with concomitant effects on SMC migration and on HPA reactivity. The role and mode of action of RvE1 and its precursor, monoacylglyceride eicosapentaenoic acid were assessed on HPA under proinflammatory conditions, involving a combined pretreatment with 10 ng/ml TNF-α and 10 ng/ml IL-6. Our results show that TNF-α and IL-6 treatment induced hyperreactivity and Ca2+ hypersensitivity in response to pharmaco-mechanical stimuli, including 80 mM KCl, 1 μM phorbol 12–13-dibutyrate, and 30 nM U-46619. Furthermore, the proinflammatory treatment increased the migration rate of SMC isolated from HPA. The phosphorylation level of regulatory contractile proteins (CPI-17, MYPT-1), and proinflammatory signaling pathways (c-Fos, c-Jun, NF-κB) were also significantly increased compared with control conditions. Conversely, 300 nM RvE1 was able to normalize all of the above abnormal events triggered by proinflammation. In conclusion, RvE1 can resolve human arterial hyperreactivity via the resolution of inflammatory markers.

Epoxyeicosatrienoic acids attenuate cigarette smoke extract-induced interleukin-8 production in bronchial epithelial cells

In response to endothelial cell activation, arachidonic acid can be converted by cytochrome P450 (CYP) epoxygenases to epoxyeicosatrienoic acids (EETs), which have potent vasodilator and anti-inflammatory properties. In this study, we investigated the effects of exogenous EETs on cigarette smoke extract (CSE)-induced inflammation in human bronchial epithelial cells (NCI-H292). We found that CSE inhibited the expression of CYP2C8 and mildly stimulated the expression of epoxide hydrolase 2 (EPHX2) but did not change the expression of CYP2J2. Treatment with 11,12-EET or 14,15-EET attenuated the CSE-induced release of interleukin (IL)-8 by inhibiting the phosphorylation of p38 mitogen-activated protein kinases (MAPKs). Our results demonstrated that CSE may reduce the anti-inflammatory ability of epithelial cells themselves by lowering the EET level. EETs from pulmonary epithelial cells may play a critical protective role on epithelial cell injury.

CYP2J2 overexpression attenuates nonalcoholic fatty liver disease induced by high-fat diet in mice

Cytochrome P-450 epoxygenase-derived epoxyeicosatrienoic acids (EETs) exert diverse biological activities, which include potent vasodilatory, anti-inflammatory, antiapoptotic, and antioxidatant effects, and cardiovascular protection. Liver has abundant epoxygenase expression and high levels of EET production; however, the roles of epoxygenases in liver diseases remain to be elucidated. In this study, we investigated the protection against high-fat diet-induced nonalcoholic fatty liver disease (NAFLD) in mice with endothelial-specific CYP2J2 overexpression (Tie2-CYP2J2-Tr). After 24 wk of high-fat diet, Tie2-CYP2J2-Tr mice displayed attenuated NAFLD compared with controls. Tie2-CYP2J2-Tr mice showed significantly decreased plasma triglyceride levels and liver lipid accumulation, improved liver function, reduced inflammatory responses, and less increase in hepatic oxidative stress than wild-type control mice. These effects were associated with inhibition of NF-κB/JNK signaling pathway activation and enhancement of the antioxidant defense system in Tie2-CYP2J2-Tr mice in vivo. We also demonstrated that 14,15-EET treatment protected HepG2 cells against palmitic acid-induced inflammation and oxidative stress. 14,15-EET attenuated palmitic acid-induced changes in NF-κB/JNK signaling pathways, malondialdehyde generation, glutathione levels, reactive oxygen species production, and NADPH oxidase and antioxidant enzyme expression in HepG2 cells in vitro. Together, these results highlight a new role for CYP epoxygenase-derived EETs in lipotoxicity-related inflammation and oxidative stress and reveal a new molecular mechanism underlying EETs-mediated anti-inflammatory and antioxidant effects that could aid in the design of new therapies for the prevention and treatment of NAFLD.

Lipoxin generation is related to soluble epoxide hydrolase activity in severe asthma

RATIONALE

Severe asthma is characterized by airway inflammatory responses associated with aberrant metabolism of arachidonic acid. Lipoxins (LX) are arachidonate-derived pro-resolving mediators that are decreased in severe asthma, yet mechanisms for defective LX biosynthesis and a means to increase LXs in severe asthma remain to be established.

OBJECTIVES

To determine if oxidative stress and soluble epoxide hydrolase (sEH) activity are linked to decreased LX biosynthesis in severe asthma.

METHODS

Aliquots of blood, sputum, and bronchoalveolar lavage fluid were obtained from asthma subjects for mediator determination. Select samples were exposed to t-butyl-hydroperoxide or sEH inhibitor (sEHI) before activation. Peripheral blood leukocyte-platelet aggregates were monitored by flow cytometry, and bronchial contraction was determined with cytokine-treated human lung sections.

MEASUREMENTS AND MAIN RESULTS

8-Isoprostane levels in sputum supernatants were inversely related to LXA4 in severe asthma (r = -0.55; P = 0.03) and t-butyl-hydroperoxide decreased LXA4 and 15-epi-LXA4 biosynthesis by peripheral blood leukocytes. LXA4 and 15-epi-LXA4 levels were inversely related to sEH activity in sputum supernatants and sEHIs significantly increased 14,15-epoxy-eicosatrienoic acid and 15-epi-LXA4 generation by severe asthma whole blood and bronchoalveolar lavage fluid cells. The abundance of peripheral blood leukocyte-platelet aggregates was related to asthma severity. In a concentration-dependent manner, LXs significantly inhibited platelet-activating factor-induced increases in leukocyte-platelet aggregates (70.8% inhibition [LXA4 100 nM], 78.3% inhibition [15-epi-LXA4 100 nM]) and 15-epi-LXA4 markedly inhibited tumor necrosis factor-α-induced increases in bronchial contraction.

CONCLUSIONS

LX levels were decreased by oxidative stress and sEH activity. Inhibitors of sEH increased LXs that mediated antiphlogistic actions, suggesting a new therapeutic approach for severe asthma. Clinical trial registered with www.clinicaltrials.gov (NCT 00595114).

Resolvin D1 reverses reactivity and Ca2+ sensitivity induced by ET-1, TNF-α, and IL-6 in the human pulmonary artery

Pulmonary hypertension (PH) is a rare and progressive disease characterized by an inflammatory status and vessel wall remodeling, resulting in increased pulmonary artery resistance. During the last decade, treatments have been proposed; most of them target the endothelial pathways that stimulate smooth muscle cell relaxation. However, PH remains associated with significant morbidity. We hypothesized that inflammation plays a crucial role in the severity of the abnormal vasoconstriction in PH. The goal of this study was to assess the effects of resolvin D1 (RvD1), a potent anti-inflammatory agent, on the pharmacological reactivity of human pulmonary arteries (HPAs) via an in vitro model of induced hyperreactivity. The effects of RvD1 and monoacylglyceride compounds were measured on contractile activity and Ca(2+) sensitivity developed by HPAs that had been pretreated (or not) under proinflammatory conditions with either 10 ng/ml TNF-α or 10 ng/ml IL-6 or under hyperreactive conditions with 5 nM endothelin-1. The results demonstrated that, compared with controls, 24-h pretreatment with TNF-α, IL-6, or endothelin-1 increased reactivity and Ca(2+) sensitivity of HPAs as revealed by agonist challenges with 80 mM KCl, 1 μM serotonin (5-hydroxytryptamine), 30 nM U-46619, and 1 μM phorbol 12,13-dibutyrate. However, 300 nM RvD1 as well as 1 μM monoacylglyceride-docosapentaenoic acid monoglyceride strongly reversed the overresponsiveness induced by both proinflammatory and hyperreactive treatments. In pretreated pulmonary artery smooth muscle cells, Western blot analyses revealed that RvD1 treatment decreased the phosphorylation level of CPI-17 and expression of transmembrane protein member 16A while increasing the detection of G protein-coupled receptor 32. The present data demonstrate that RvD1, a trihydroxylated docosahexaenoic acid derivative, decreases induced overreactivity in HPAs via a reduction in CPI-17 phosphorylation and transmembrane protein member 16A expression.

ω-3 polyunsaturated fatty acids-derived lipid metabolites on angiogenesis, inflammation and cancer

Epidemiological and pre-clinical studies support the anti-tumor effects of ω-3 PUFAs; however, the results from human trials are mixed, making it difficult to provide dietary guidelines or recommendations of ω-3 PUFAs for disease prevention or treatment. Understanding the molecular mechanisms by which ω-3 PUFAs inhibit cancer could lead to better nutritional paradigms and human trials to clarify their health effects. The ω-3 PUFAs exert their biological activities mainly through the formation of bioactive lipid metabolites. Here we discuss the biology of cyclooxygenase, lipoxygenase and cytochrome P450 enzymes-derived ω-3-series lipid metabolites on angiogenesis, inflammation and cancer.

Application of fullerenes in nanomedicine: an update

Fullerenes are carbon spheres presently being pursued globally for a wide range of applications in nanomedicine. These molecules have unique electronic properties that make them attractive candidates for diagnostic, therapeutic and theranostic applications. Herein, the latest research is discussed on developing fullerene-based therapeutics as antioxidants for inflammatory diseases, their potential as antiviral/bacterial agents, utility as a drug delivery device and the promise of endohedral fullerenes as new MRI contrast agents. The recent discovery that certain fullerene derivatives can stabilize immune effector cells to prevent or inhibit the release of proinflammatory mediators makes them potential candidates for several diseases such as asthma, arthritis and multiple sclerosis. Gadolinium-containing endohedral fullerenes are being pursued as diagnostic MRI contrast agents for several diseases. Finally, a new class of fullerene-based theranostics has been developed, which combine therapeutic and diagnostic capabilities to specifically detect and kill cancer cells.

Stabilized epoxygenated fatty acids regulate inflammation, pain, angiogenesis and cancer

Epoxygenated fatty acids (EpFAs), which are lipid mediators produced by cytochrome P450 epoxygenases from polyunsaturated fatty acids, are important signaling molecules known to regulate various biological processes including inflammation, pain and angiogenesis. The EpFAs are further metabolized by soluble epoxide hydrolase (sEH) to form fatty acid diols which are usually less-active. Pharmacological inhibitors of sEH that stabilize endogenous EpFAs are being considered for human clinical uses. Here we review the biology of ω-3 and ω-6 EpFAs on inflammation, pain, angiogenesis and tumorigenesis.

Effect of cytochrome P-450 epoxygenase and hydroxylase metabolites on rat myometrium contractility in non-pregnancy, late pregnancy and late pregnancy under inflammatory conditions

AIM

The aim of the present experimental study was to assess the tocolytic effect of eicosanoids on myometrium from non-pregnant and pregnant rats with or without an induced inflammatory condition.

METHODS

Three hundred myometrial rings were obtained by median laparotomy from 50 Sprague-Dawley rats divided into three groups: (i) non-pregnant (n = 15); (ii) pregnant in absence (n = 20); or (iii) pregnant in presence (n = 15) of lipopolysaccharide treatment, timed at 22 days of pregnancy. Spontaneous contractile activities were compared by isometric tension measurements. The effects of epoxy- and hydroxyeicosanoids derived from arachidonic acid as well as specific enzyme inhibitors were assessed. Changes were expressed as percentage of basal activity by calculating the area under the curve as a function of drug concentration and compared to the effect of the vehicle.

RESULTS

A decrease in contractile activity ranging 10-25% was observed upon addition of epoxy- and hydroxyeicosanoids. Increasing epoxyeicosanoid bioavailability by inhibiting their degradation induced a tocolytic effect in the non-pregnant group (20%) and in inflammation-induced condition (40%). There was a significant difference in reactivity between groups and pregnancy condition. Semiquantification of metabolic enzymes that produce (cytochrome P-450 epoxygenase) and degrade (soluble epoxide hydrolase) epoxyeicosanoids by western blot analysis revealed that these enzymes were mainly detected in the non-pregnant group.

CONCLUSION

Eicosanoids can modify myometrial reactivity and their presence and effects are amplified in non-pregnant and in inflammation-induced condition. Our data suggest that in contrast to prostaglandins, epoxyeicosatrienoic acids are likely involved in the quiescence phase of parturition because they reduce the rhythmic contractile activity of uterine tissues in pregnant rats.

Lipidomic profiling of bioactive lipids by mass spectrometry during microbial infections

Bioactive lipid mediators play crucial roles in promoting the induction and resolution of inflammation. Eicosanoids and other related unsaturated fatty acids have long been known to induce inflammation. These signaling molecules can modulate the circulatory system and stimulate immune cell infiltration into the site of infection. Recently, DHA- and EPA-derived metabolites have been discovered to promote the resolution of inflammation, an active process. Not only do these molecules stop the further infiltration of immune cells, they prompt non-phlogistic phagocytosis of apoptotic neutrophils, stimulating the tissue to return to homeostasis. After the rapid release of lipid precursors from the plasma membrane upon stimulation, families of enzymes in a complex network metabolize them to produce a large array of lipid metabolites. With current advances in mass spectrometry, the entire lipidome can be accurately quantified to assess the immune response upon microbial infection. In this review, we discuss the various lipid metabolism pathways in the context of the immune response to microbial pathogens, as well as their complex network interactions. With the advancement of mass spectrometry, these approaches have also been used to characterize the lipid mediator response of macrophages and neutrophils upon immune stimulation in vitro. Lastly, we describe the recent efforts to apply systems biology approaches to dissect the role of lipid mediators during bacterial and viral infections in vivo.

Lipidomic profiling of influenza infection identifies mediators that induce and resolve inflammation

Bioactive lipid mediators play a crucial role in the induction and resolution of inflammation. To elucidate their involvement during influenza infection, liquid chromatography/mass spectrometry lipidomic profiling of 141 lipid species was performed on a mouse influenza model using two viruses of significantly different pathogenicity. Infection by the low-pathogenicity strain X31/H3N2 induced a proinflammatory response followed by a distinct anti-inflammatory response; infection by the high-pathogenicity strain PR8/H1N1 resulted in overlapping pro- and anti-inflammatory states. Integration of the large-scale lipid measurements with targeted gene expression data demonstrated that 5-lipoxygenase metabolites correlated with the pathogenic phase of the infection, whereas 12/15-lipoxygenase metabolites were associated with the resolution phase. Hydroxylated linoleic acid, specifically the ratio of 13- to 9-hydroxyoctadecadienoic acid, was identified as a potential biomarker for immune status during an active infection. Importantly, some of the findings from the animal model were recapitulated in studies of human nasopharyngeal lavages obtained during the 2009-2011 influenza seasons.

Relationship between bradykinin-induced relaxation and endogenous epoxyeicosanoid synthesis in human bronchi

Epoxyeicosanoids (EETs) are produced by cytochrome P-450 epoxygenase; however, it is not yet known what triggers their endogenous production in epithelial cells. The relaxing effects of bradykinin are known to be related to endogenous production of epithelial-derived hyperpolarizing factors (EpDHF). Because of their effects on membrane potential, EETs have been reported to be EpDHF candidates (Benoit C, Renaudon B, Salvail D, Rousseau E. Am J Physiol Lung Cell Mol Physiol 280: L965-L973, 2001.). Thus, we hypothesized that bradykinin (BK) may stimulate endogenous EET production in human bronchi. To test this hypothesis, the relaxing and hyperpolarizing effects of BK and 14,15-EET were quantified on human bronchi, as well as the effects of various enzymatic inhibitors on these actions. One micromolar BK or 1 μM 14,15-EET induced a 45% relaxation on the tension induced by 30 nM U-46619 [a thromboxane-prostanoid (TP)-receptor agonist]. These BK-relaxing effects were reduced by 42% upon addition of 10 nM iberiotoxin [a large-conductance Ca(2+)-sensitive K(+) (BK(Ca)) channel blocker], by 27% following addition of 3 μM 14,15-epoxyeicosa-5(Z)-enoic acid (an EET antagonist), and by 32% with 3 μM N-methanesulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH, an epoxygenase inhibitor). Hence, BK and 14,15-EET display net hyperpolarizing effects on airway smooth muscle cells that are related to the activation of BK(Ca) channels and ultimately yielding to relaxation. Data also indicate that 3 μM MS-PPOH reduced the hyperpolarizing effects of BK by 43%. Together, the present data support the current hypothesis suggesting a direct relationship between BK and the production of EET regioisomers. Because of its potent anti-inflammatory and relaxing properties, epoxyeicosanoid signaling may represent a promising target in asthma and chronic obstructive pulmonary disease.

Förster resonance energy transfer competitive displacement assay for human soluble epoxide hydrolase

The soluble epoxide hydrolase (sEH), responsible for the hydrolysis of various fatty acid epoxides to their corresponding 1,2-diols, is becoming an attractive pharmaceutical target. These fatty acid epoxides, particularly epoxyeicosatrienoic acids (EETs), play an important role in human homeostatic and inflammation processes. Therefore, inhibition of human sEH, which stabilizes EETs in vivo, brings several beneficial effects to human health. Although there are several catalytic assays available to determine the potency of sEH inhibitors, measuring the in vitro inhibition constant (K(i)) for these inhibitors using catalytic assay is laborious. In addition, k(off), which has been recently suggested to correlate better with the in vivo potency of inhibitors, has never been measured for sEH inhibitors. To better measure the potency of sEH inhibitors, a reporting ligand, 1-(adamantan-1-yl)-3-(1-(2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetyl) piperidin-4-yl)urea (ACPU), was designed and synthesized. With ACPU, we have developed a Förster resonance energy transfer (FRET)-based competitive displacement assay using intrinsic tryptophan fluorescence from sEH. In addition, the resulting assay allows us to measure the K(i) values of very potent compounds to the picomolar level and to obtain relative k(off) values of the inhibitors. This assay provides additional data to evaluate the potency of sEH inhibitors.

Asthmatic airway hyperresponsiveness: the ants in the tree

Airways from asthmatics have a propensity to narrow excessively in response to spasmogens (i.e., contractile agonists), a feature called airway hyperresponsiveness (AHR). AHR is an important contributor to asthma symptoms because the degree of responsiveness dictates the amount of airway narrowing that occurs in response to inflammation-derived spasmogens produced endogenously following exposure to environmental triggers, such as allergens, viruses, or pollutants. The smooth muscle encircling the airways is responsible for responsiveness because it constricts the airway lumen when commanded to contract by spasmogens. However, whether AHR seen in asthmatics is due to stronger muscle is equivocal. In this opinion article, I propose that environmental triggers and other inflammatory molecules released during asthma attacks contribute to AHR by increasing muscle force.

Impact of soluble epoxide hydrolase and epoxyeicosanoids on human health

The presence of epoxyeicosatrienoic acids (EETs) in tissues and their metabolism by soluble epoxide hydrolase (sEH) to 1,2-diols were first reported 30 years ago. However, appreciation of their importance in cell biology and physiology has greatly accelerated over the past decade with the discovery of metabolically stable inhibitors of sEH, the commercial availability of EETs, and the development of analytical methods for the quantification of EETs and their diols. Numerous roles of EETs in regulatory biology now are clear, and the value of sEH inhibition in various animal models of disease has been demonstrated. Here, we review these results and discuss how the pharmacological stabilization of EETs and other natural epoxy-fatty acids could lead to possible disease therapies.

Anti-inflammatory effects of epoxyeicosatrienoic acids

Epoxyeicosatrienoic acids (EETs) are generated by the activity of both selective and also more general cytochrome p450 (CYP) enzymes on arachidonic acid and inactivated largely by soluble epoxide hydrolase (sEH), which converts them to their corresponding dihydroxyeicosatrienoic acids (DHETs). EETs have been shown to have a diverse range of effects on the vasculature including relaxation of vascular tone, cellular proliferation, and angiogenesis as well as the migration of smooth muscle cells. This paper will highlight the growing evidence that EETs also mediate a number of anti-inflammatory effects in the cardiovascular system. In particular, numerous studies have demonstrated that potentiation of EET activity using different methods can inhibit inflammatory gene expression and signalling pathways in endothelial cells and monocytes and in models of cardiovascular diseases. The mechanisms by which EETs mediate their effects are largely unknown but may include direct binding to peroxisome proliferator-activated receptors (PPARs), G-protein coupled receptors (GPCRs), or transient receptor potential (TRP) channels, which initiate anti-inflammatory signalling cascades.