Epoxyeicosatrienoic acids: formation, metabolism and potential role in tissue physiology and pathophysiology

Genetic variants in epoxyeicosatrienoic acid processing and degradation pathways are associated with gestational diabetes mellitus

AIM

To explore the genetic effects of CYP2C8, CYP2C9, CYP2J2, and EPHX2, the key genes involved in epoxyeicosatrienoic acid processing and degradation pathways in gestational diabetes mellitus (GDM) and metabolic traits in Chinese pregnant women.

METHODS

A total of 2548 unrelated pregnant women were included, of which 938 had GDM and 1610 were considered as controls. Common variants were genotyped using the Infinium Asian Screening Array. Association studies of single nucleotide polymorphisms (SNPs) with GDM and related traits were performed using logistic regression and multivariable linear regression analyses. A genetic risk score (GRS) model based on 12 independent target SNPs associated with GDM was constructed. Logistic regression was used to estimate odds ratios and 95% confidence intervals, adjusting for potential confounders including age, pre-pregnancy body mass index, history of polycystic ovarian syndrome, history of GDM, and family history of diabetes, with GRS entered both as a continuous variable and categorized groups. The relationship between GRS and quantitative traits was also evaluated.

RESULTS

The 12 SNPs in CYP2C8, CYP2C9, CYP2J2, and EPHX2 were significantly associated with GDM after adjusting for covariates (all P < 0.05). The GRS generated from these SNPs significantly correlated with GDM. Furthermore, a significant interaction between CYP2J2 and CYP2C8 in GDM (P_Interaction = 0.014, OR_Interaction= 0.61, 95%CI 0.41-0.90) was observed.

CONCLUSION

We found significant associations between GDM susceptibility and 12 SNPs of the four genes involved in epoxyeicosatrienoic acid processing and degradation pathways in a Chinese population. Subjects with a higher GRS showed higher GDM susceptibility with higher fasting plasma glucose and area under the curve of glucose and poorer β-cell function.

Regulation of inflammation in cancer by dietary eicosanoids

BACKGROUND

Cancer is a major burden of disease worldwide and increasing evidence shows that inflammation contributes to cancer development and progression. Eicosanoids are derived from dietary polyunsaturated fatty acids, such as arachidonic acid (AA), and are mainly produced by a series of enzymatic pathways that include cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P-450 epoxygenase (CYP). Eicosanoids consist of at least several hundred individual molecules and play important roles in the inflammatory response and inflammation-related cancers.

SCOPE AND APPROACH

Dietary sources of AA and biosynthesis of eicosanoids from AA through different metabolic pathways are summarized. The bioactivities of eicosanoids and their potential molecular mechanisms on inflammation and cancer are revealed. Additionally, current challenges and limitations in eicosanoid research on inflammation-related cancer are discussed.

KEY FINDINGS AND CONCLUSIONS

Dietary AA generates a large variety of eicosanoids, including prostaglandins, thromboxane A2, leukotrienes, cysteinyl leukotrienes, lipoxins, hydroxyeicosatetraenoic acids (HETEs), and epoxyeicosatrienoic acids (EETs). Eicosanoids exert different bioactivities and mechanisms involved in the inflammation and related cancer developments. A deeper understanding of eicosanoid biology may be advantageous in cancer treatment and help to define cellular targets for further therapeutic development.

Effects of genetic polymorphisms of CYP2J2, CYP2C9, CYP2C19, CYP4F2, CYP4F3 and CYP4A11 enzymes in preeclampsia and gestational hypertension

INTRODUCTION

The aim of this study was to investigate the effects of cytochrome P450 (CYP) 2J2, CYP2C9, CYP2C19 and CYP4F2, CYP4F3 and CYP4A11 genetic polymorphisms in preeclampsia and gestational hypertension (GHT) patients in a sample of Turkish population.

MATERIALS-METHODS

Patients (n = 168; 110 GHT and 58 preeclampsia) and healthy pregnant women (n = 155, controls) participated in the study. For genotyping, polymerase chain reaction (PCR) and restriction analysis (RFLP) were used. Substance levels were measured using LC-MS.

RESULTS

Plasma DHET levels in GHT and preeclampsia patients were significantly lower than those in the control group (62.7%, 66.3% vs.100.0%, respectively, p < 0.0001). An increase in CYP2J2*7 allele frequency was observed in the preeclampsia group, as compared to GHT group (12.1% vs. 4.5%; odds ratio, O.R. = 2.88, p < 0.01). The frequencies of CYP2C19*2 and*17 alleles were higher in GHT group as compared to the control group (17.7% vs. 11.6%, O.R. = 1.99, p < 0.01; and 28.6% vs.18.4%, O.R. = 2.03, p < 0.01, respectively). An increased frequency of CYP4F3 rs3794987 G allele was found in GHT group as compared to the control group (48.0% vs. 38.0%; O.R. = 1.53, p < 0.01).

DISCUSSION

DHET plasma levels were significantly reduced in hypertensive pregnant groups as compared to the control group. The allele frequency distributions for CYP2J2*7, CYP2C19 *2, *17 and CYP4F3 rs3794987 were significantly different in hypertensive pregnant patients as compared to the healthy control subjects. Our results may suggest that investigated genetic polymorphisms may be useful in diagnosis and clinical management of GHT and preeclampsia patients.

Synthesis, In Vitro Profiling, and In Vivo Evaluation of Benzohomoadamantane-Based Ureas for Visceral Pain: A New Indication for Soluble Epoxide Hydrolase Inhibitors

The soluble epoxide hydrolase (sEH) has been suggested as a pharmacological target for the treatment of several diseases, including pain-related disorders. Herein, we report further medicinal chemistry around new benzohomoadamantane-based sEH inhibitors (sEHI) in order to improve the drug metabolism and pharmacokinetics properties of a previous hit. After an extensive in vitro screening cascade, molecular modeling, and in vivo pharmacokinetics studies, two candidates were evaluated in vivo in a murine model of capsaicin-induced allodynia. The two compounds showed an anti-allodynic effect in a dose-dependent manner. Moreover, the most potent compound presented robust analgesic efficacy in the cyclophosphamide-induced murine model of cystitis, a well-established model of visceral pain. Overall, these results suggest painful bladder syndrome as a new possible indication for sEHI, opening a new range of applications for them in the visceral pain field.

Plasma epoxyeicosatrienoic acids and diabetes-related cardiovascular disease: The cardiovascular health study

Background

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid that may impact atherosclerosis, and animal experimental studies suggest EETs protect cardiac function. Plasma EETs are mostly esterified to phospholipids and part of an active pool. To address the limited information about EETs and CVD in humans, we conducted a prospective study of total plasma EETs (free + esterified) and diabetes-related CVD in the Cardiovascular Health Study (CHS).

Methods

We measured 4 EET species and their metabolites, dihydroxyepoxyeicosatrienoic acids (DHETs), in plasma samples from 892 CHS participants with type 2 diabetes. We determined the association of EETs and DHETs with incident myocardial infarction (MI) and ischemic stroke using Cox regression.

Findings

During follow-up (median 7.5 years), we identified 150 MI and 134 ischemic strokes. In primary, multivariable analyses, elevated levels of each EET species were associated with non-significant lower risk of incident MI (for example, hazard ratio for 1 SD higher 14,15-EET: 0.86, 95% CI: 0.72–1.02; p=0.08). The EETs-MI associations became significant in analyses further adjusted for DHETs (hazard ratio for 1 SD higher 14,15-EET adjusted for 14,15-DHET: 0.76, 95% CI: 0.63–0.91; p=0.004). Elevated EET levels were associated with higher risk of ischemic stroke in primary but not secondary analyses. Three DHET species were associated with higher risk of ischemic stroke in all analyses.

Interpretation

Findings from this prospective study complement the extensive studies in animal models showing EETs protect cardiac function and provide new information in humans. Replication is needed to confirm the associations.

Funding

US National Institutes of Health.

Synthesis and biological evaluation of new series of benzamide derivatives containing urea moiety as sEH inhibitors

The pharmacological inhibition of soluble epoxide hydrolase (sEH) was shown to reduce inflammation and pain. Herein, we described a series of newly synthesized sEH inhibitors with the trident-shaped skeleton. Intensive structural modifications led to the identification of compound B15 as a potent sEH inhibitor with an IC₅₀ value of 0.03 ± 0.01 nM. Furthermore, compound B15 showed satisfactory metabolic stability in human liver microsomes with a half-time of 197 min. In carrageenan-induced inflammatory pain rat model, compound B15 exhibited a better therapeutic effect compared to t-AUCB and Celecoxib, which demonstrated the proof of potential as anti-inflammatory agents for pain relief.

Structure-guided discovery of potent and oral soluble epoxide hydrolase inhibitors for the treatment of neuropathic pain

Soluble epoxide hydrolase (sEH) is related to arachidonic acid cascade and is over-expressed in a variety of diseases, making sEH an attractive target for the treatment of pain as well as inflammatory-related diseases. A new series of memantyl urea derivatives as potent sEH inhibitors was obtained using our previous reported compound 4 as lead compound. A preferential modification of piperidinyl to 3-carbamoyl piperidinyl was identified for this series via structure-based rational drug design. Compound A20 exhibited moderate percentage plasma protein binding (88.6%) and better metabolic stability in vitro. After oral administration, the bioavailability of A20 was 28.6%. Acute toxicity test showed that A20 was well tolerated and there was no adverse event encountered at dose of 6.0 g/kg. Inhibitor A20 also displayed robust analgesic effect in vivo and dose-dependently attenuated neuropathic pain in rat model induced by spared nerve injury, which was better than gabapentin and sEH inhibitor (±)-EC-5026. In one word, the oral administration of A20 significantly alleviated pain and improved the health status of the rats, demonstrating that A20 was a promising candidate to be further evaluated for the treatment of neuropathic pain.

2-(Piperidin-4-yl)acetamides as Potent Inhibitors of Soluble Epoxide Hydrolase with Anti-Inflammatory Activity

The pharmacological inhibition of soluble epoxide hydrolase (sEH) has been suggested as a potential therapy for the treatment of pain and inflammatory diseases through the stabilization of endogenous epoxyeicosatrienoic acids. Numerous potent sEH inhibitors (sEHI) have been developed, however many contain highly lipophilic substituents limiting their availability. Recently, a new series of benzohomoadamantane-based ureas endowed with potent inhibitory activity for the human and murine sEH was reported. However, their very low microsomal stability prevented further development. Herein, a new series of benzohomoadamantane-based amides were synthetized, fully characterized, and evaluated as sEHI. Most of these amides were endowed with excellent inhibitory potencies. A selected compound displayed anti-inflammatory effects with higher effectiveness than the reference sEHI, TPPU.

Variability of CYP2C8 Polymorphisms in Three Jordanian Populations: Circassians, Chechens and Jordanian-Arabs

CYP2C8 is a member of Cytochrome P450 enzymes system. It plays an important role in metabolizing a wide range of exogenous and endogenous compounds. CYP2C8 is involved in the metabolism of more than 100 drugs, typical substrates include: anticancer agents, antidiabetic agents, antimalarial agents, lipid lowering drugs and many others that constitute 20% of clinically prescribed drugs. Genetic variations of CYP2C8 have been reported with different frequencies in different populations. These genetic polymorphisms can lead to differences in the efficacy and safety of different types of medications metabolized by CYP2C8. The aim of this study was to investigate the allele frequencies of CYP2C8*3 (rs10509681 and rs11572080) and CYP2C8*4 (rs1058930) polymorphisms in three populations living in Jordan; Circassians and Chechens and Jordanian-Arabs and compare those frequencies with other populations. A total of 200 healthy Jordanians, 93 Circassians and 88 Chechens were included in this study. Genotyping of CYP2C8*3 and CYP2C8*4 polymorphisms was done by using polymerase chain reaction (PCR) followed by Restriction Fragment Length Polymorphism (RFLP). Using the Chi-square test, we found that the prevalence of CYP2C8*3 and *4 among the three populations were significantly different. Moreover, the mutant allele CYP2C8*3 (416A) was only detected in the Jordanian-Arab population with an allele frequency of 0.082, while the mutant allele CYP2C8*4 (792G) was detected with frequencies of 0.065, 0.122, 0.017 in Jordanian-Arabs, Circassians and Chechens, respectively. As our results show, CYP2C8*3 was undetectable in our Circassians and Chechens samples, on the other hand, Circassians had the highest allele frequency of CYP2C8*4 compared to Chechens and Jordanian-Arabs. These genetic variations of the gene encoding the CYP2C8 drug metabolizing enzymes can lead to clinical differences in drug metabolism and ultimately variations in drug effectiveness and toxicities. This study provides evidence for the importance of personalized medicine in these populations and can be the foundation for future clinical studies.

Role of eicosanoids in liver repair, regeneration and cancer

Eicosanoids are lipid signaling molecules derived from the oxidation of ω-6 fatty acids, usually arachidonic acid. There are three major pathways, including the cyclooxygenase (COX), lipoxygenase (LOX), and P450 cytochrome epoxygenase (CYP) pathway. Prostanoids, which include prostaglandins (PG) and thromboxanes (Tx), are formed via the COX pathway, leukotrienes (LT) and lipoxins (LX) by the action of 5-LOX, and hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) by CYP. Although eicosanoids are usually associated with pro-inflammatory responses, non-classic eicosanoids, as LX, have anti-inflammatory and pro-resolving properties. Eicosanoids like PGE₂, LTB₄ and EETs have been involved in promoting liver regeneration after partial hepatectomy. PGE₂ and LTB₄ have also been reported to participate in the regenerative phase after ischemia and reperfusion (I/R), while cysteinyl leukotrienes (Cys-LT) contribute to the inflammatory process associated with I/R and are also involved in liver fibrosis and cirrhosis. However, LX, another product of 5-LOX, have the opposite effect, acting as pro-resolving mediators in these pathologies. In liver cancer, most studies show that eicosanoids, with the exception of LX, promote the proliferation of hepatocellular carcinoma cells and favor metastasis. This review summarizes the synthesis of different eicosanoids in the liver and discusses key findings from basic research linking eicosanoids to liver repair, regeneration and cancer and the impact of targeting eicosanoid cascade. In addition, studies in patients are presented that explore the potential use of eicosanoids as biomarkers and show correlations between eicosanoid production and the course and prognosis of liver disease.

From the Design to the In Vivo Evaluation of Benzohomoadamantane-Derived Soluble Epoxide Hydrolase Inhibitors for the Treatment of Acute Pancreatitis

The pharmacological inhibition of soluble epoxide hydrolase (sEH) is efficient for the treatment of inflammatory and pain-related diseases. Numerous potent sEH inhibitors (sEHIs) present adamantyl or phenyl moieties, such as the clinical candidates AR9281 or EC5026. Herein, in a new series of sEHIs, these hydrophobic moieties have been merged in a benzohomoadamantane scaffold. Most of the new sEHIs have excellent inhibitory activities against sEH. Molecular dynamics simulations suggested that the addition of an aromatic ring into the adamantane scaffold produced conformational rearrangements in the enzyme to stabilize the aromatic ring of the benzohomoadamantane core. A screening cascade permitted us to select a candidate for an in vivo efficacy study in a murine model of cerulein-induced acute pancreatitis. The administration of 22 improved the health status of the animals and reduced pancreatic damage, demonstrating that the benzohomoadamantane unit is a promising scaffold for the design of novel sEHIs.

Plasma epoxyeicosatrienoic acids and dihydroxyeicosatrieonic acids, insulin, glucose and risk of diabetes: The strong heart study

BACKGROUND

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid with multiple biological functions. Rodent experiments suggest EETs play a role in insulin sensitivity and diabetes, but evidence in humans is limited. To address this knowledge gap, we conducted a case-cohort study in the Strong Heart Family Study, a prospective cohort among American Indians.

METHODS

We measured 4 EET species and 4 species of corresponding downstream metabolites, dihydroxyeicosatrieonic acids (DHETs), in plasma samples from 1161 participants, including 310 with type 2 diabetes. We estimated the associations of total (esterified and free) EETs and DHETs with incident diabetes risk, adjusting for known risk factors. We also examined cross-sectional associations with plasma fasting insulin and glucose in the case-cohort and in 271 participants without diabetes from the older Strong Heart Study cohort, and meta-analyzed the results from the 2 cohorts.

FINDINGS

We observed no significant association of total EET or DHET levels with incident diabetes. In addition, plasma EETs were not associated with plasma insulin or plasma glucose. However, higher plasma 14,15-DHET was associated with lower plasma insulin and lower plasma glucose.

INTERPRETATION

In this first prospective study of EETs and diabetes, we found no evidence for a role of total plasma EETs in diabetes. The novel associations of 14,15-DHET with insulin and glucose warrant replication and exploration of possible mechanisms.

FUNDING

US National Institutes of Health.

Changes in erythrocyte membrane epoxyeicosatrienoic, dihydroxyeicosatrienoic, and hydroxyeicosatetraenoic acids during pregnancy

AIMS

Pregnancy is associated with numerous changes in physiological and metabolic processes to ensure successful progression to full term. One such change is the alteration of arachidonic acid (AA) metabolism and formation of eicosanoids. This study explores the changes in AA metabolites formed through the cytochrome P450 mediated pathway to epoxyeicosatrienoic (EET), dihydroxyeicosatrienoic (DHET), and hydroxyeicosatetraenoic (HETE) acids which have been implicated in blood pressure regulation and inflammatory responses that are important for a healthy pregnancy.

MAIN METHODS

The study determines circulating levels of EETs, DHETs and HETEs extracted from erythrocyte membranes and measured by mass spectroscopy during the progression of a normal pregnancy. Blood samples, from 25 women, were collected at three time points including 25-28 weeks gestation, 28-32 weeks gestation, and the non-pregnant control at 3-4 months postpartum.

KEY FINDINGS

Results demonstrate that healthy pregnancy is associated with significant increases in 8,9-DHET, 11,12-DHET and 14,15-DHET and a decrease in trans 8,9-EET during 28-32 weeks gestation compared to 3-4 months postpartum. These differences are likely due to several mechanisms including an increase in soluble epoxide hydrolase activity, a decrease in glutathione conjugation, and altered cytochrome P450 enzyme expression and/or activity that occurs during pregnancy.

SIGNIFICANCE

Metabolism of AA through the cytochrome P450 pathway generates physiologically important eicosanoids that could play an important role in the progression of a healthy pregnancy. Establishing the changes that occur during normal pregnancy may, in the future, help in early detection of pregnancy complications including preeclampsia.

Investigation of the content differences of arachidonic acid metabolites in a mouse model of breast cancer by using LC-MS/MS

Arachidonic acid (AA) is closely associated with breast cancer. In addition to the two metabolic pathways regulated by cyclooxygenase and lipoxygenase, AA has a third metabolic pathway through which cytochrome P450 (CYP) enzymes produce hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs). The targeted CYP-mediated pathway of AA can not only kill cancer cells but also inhibit the interstitial microenvironment around a tumor. Therefore, it makes sense to identify potential biomarkers from the AA metabolome for the diagnosis and treatment of breast cancer. This study established a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of AA and its main metabolites, EETs and HETEs, in MMTV-PyMT mice, a spontaneous breast cancer mouse model. The results showed that there were significant differences in the concentrations of AA, 12-HETE, 19-HETE and 8,9-EET in plasma and tumor tissues between normal and MMTV-PyMT mice. Therefore, the eicosanoids mentioned above may be used as new biomarkers for breast cancer diagnosis. This study provides a new perspective for the recognition and diagnosis of breast cancer.

2-Oxaadamant-1-yl Ureas as Soluble Epoxide Hydrolase Inhibitors: In Vivo Evaluation in a Murine Model of Acute Pancreatitis

In vivo pharmacological inhibition of soluble epoxide hydrolase (sEH) reduces inflammatory diseases, including acute pancreatitis (AP). Adamantyl ureas are very potent sEH inhibitors, but the lipophilicity and metabolism of the adamantane group compromise their overall usefulness. Herein, we report that the replacement of a methylene unit of the adamantane group by an oxygen atom increases the solubility, permeability, and stability of three series of urea-based sEH inhibitors. Most of these oxa-analogues are nanomolar inhibitors of both the human and murine sEH. Molecular dynamics simulations rationalize the molecular basis for their activity and suggest that the presence of the oxygen atom on the adamantane scaffold results in active site rearrangements to establish a weak hydrogen bond. The 2-oxaadamantane 22, which has a good solubility, microsomal stability, and selectivity for sEH, was selected for further in vitro and in vivo studies in models of cerulein-induced AP. Both in prophylactic and treatment studies, 22 diminished the overexpression of inflammatory and endoplasmic reticulum stress markers induced by cerulein and reduced the pancreatic damage.

Higher Epoxyeicosatrienoic Acids in Cardiomyocytes-Specific CYP2J2 Transgenic Mice Are Associated with Improved Myocardial Remodeling

Elevated cis-epoxyeicosatrienoic acids (EETs) are known to be cardioprotective during ischemia-reperfusion injury in cardiomyocyte-specific overexpressing cytochrome P450 2J2 (CYP2J2) transgenic (Tr) mice. Using the same Tr mice, we measured changes in cardiac and erythrocyte membranes EETs following myocardial infarction (MI) to determine if they can serve as reporters for cardiac events. Cardiac function was also assessed in Tr vs. wild-type (WT) mice in correlation with EET changes two weeks following MI. Tr mice (N = 25, 16 female, nine male) had significantly higher cardiac cis- and trans-EETs compared to their WT counterparts (N = 25, 18 female, seven male). Total cardiac cis-EETs in Tr mice were positively correlated with total cis-EETs in erythrocyte membrane, but there was no correlation with trans-EETs or in WT mice. Following MI, cis- and trans-EETs were elevated in the erythrocyte membrane and cardiac tissue in Tr mice, accounting for the improved cardiac outcomes observed. Tr mice showed significantly better myocardial remodeling following MI, evidenced by higher % fractional shortening, smaller infarct size, lower reactive oxygen species (ROS) formation, reduced fibrosis and apoptosis, and lower pulmonary edema. A positive correlation between total cardiac cis-EETs and total erythrocyte membrane cis-EETs in a Tr mouse model suggests that erythrocyte cis-EETs may be used as predictive markers for cardiac events. All cis-EET regioisomers displayed similar trends following acute MI; however, the magnitude of change for each regioisomer was markedly different, warranting measurement of each individually.

CYP2J2 Modulates Diverse Transcriptional Programs in Adult Human Cardiomyocytes

CYP2J2, a member of the Cytochrome P450 family of enzymes, is the most abundant epoxygenase in the heart and has multifunctional properties including bioactivation of arachidonic acid to epoxyeicosatrienoic acids, which, in turn, have been implicated in mediating several cardiovascular conditions. Using a proteomic approach, we found that CYP2J2 expression is lower in cardiac tissue from patients with cardiomyopathy compared to controls. In order to better elucidate the complex role played by CYP2J2 in cardiac cells, we performed targeted silencing of CYP2J2 expression in human adult ventricular cardiomyocytes and interrogated whole genome transcriptional responses. We found that knockdown of CYP2J2 elicits widespread alterations in gene expression of ventricular cardiomyocytes and leads to the activation of a diverse repertoire of programs, including those involved in ion channel signaling, development, extracellular matrix, and metabolism. Several members of the differentially up-regulated ion channel module have well-known pathogenetic roles in cardiac dysrhythmias. By leveraging causal network and upstream regulator analysis, we identified several candidate drivers of the observed transcriptional response to CYP2J2 silencing; these master regulators have been implicated in aberrant cardiac remodeling, heart failure, and myocyte injury and repair. Collectively, our study demonstrates that CYP2J2 plays a central and multifaceted role in cardiomyocyte homeostasis and provides a framework for identifying critical regulators and pathways influenced by this gene in cardiovascular health and disease.

Development and validation of a rapid, specific and sensitive LC-MS/MS bioanalytical method for eicosanoid quantification - assessment of arachidonic acid metabolic pathway activity in hypertensive rats

Lipid mediators such as eicosanoids maintain various physiological processes, and their alterations are involved in the development of numerous cardiovascular diseases. Therefore, the reliable assessment of their profile could be helpful in diagnosis as well as in eicosanoid biomarker-based treatment. Hence, the presented study aimed to develop and validate a new rapid, specific and sensitive LC-MS/MS method for quantification of arachidonic acid-derived eicosanoids in plasma, including lipid mediators generated via COX-, LOX- and CYP450-dependent pathways. The developed method features high sensitivity because the lower limit of quantification ranged from 0.05 to 0.50 ng mL^-1 as well as the accuracy and precision estimated within 88.88-111.25% and 1.03-11.82%, respectively. An application of a simple and fast liquid-liquid extraction procedure for sample cleaning resulted in a highly satisfactory recovery of the analytes (>88.30%). Additionally, the method was validated using artificial plasma, an approach that enabled the elimination of the matrix effect caused by an endogenous concentration of studied lipid mediators. Importantly, the presented LC-MS/MS method allowed for simultaneous quantitative and qualitative [quan/qual] analysis of the selected eicosanoids, leading to an additional improvement of the method specificity. Moreover, the validated method was successfully applied for eicosanoid profiling in rat, mouse and human plasma samples, clearly demonstrating the heterogeneity of the profile of studied lipid mediators in those species.

CYP-derived eicosanoids: Implications for rheumatoid arthritis

Today the role of cytochrome P450 metabolites in inflammatory rheumatic disease, such as rheumatoid arthritis (RA) is still poorly understood. In this review we survey the current knowledge on cytochrome P450 metabolites in rheumatoid arthritis. The balance between CYP epoxygenase- and CYP ω- hydroxylase is correlated to the regulation of NF-κB. In RA patients synovial fluid there are higher levels of IL-6, which suppresses activities of CYP enzymes, such as CYP3A, CYP2C19, CYP2C9, and CYP1A2. EETs have anti-inflammatory effects, probably attributed to the PPARγ activation. EETs inhibit bone resorption and osteoclastogenesis, and can be considered as an innovative therapeutic strategy for rheumatoid arthritis. In reference to the CYP ɷ-hydroxylase pathway, 20-HETE is a pro-inflammatory mediator. While there is scarce information on the role of 20-HETE inhibitors and its antagonists in rheumatoid arthritis, the elevation of EETs levels by sEH inhibitors is a promising therapeutic strategy for rheumatoid arthritis patients. In addition, hybrid compounds, such as sEH inhibitors/FLAP inhibitors, or sEHI combined with NSAIDs/COXIBs are also important therapeutic target. However, studies investigating the effects of inflammation and rheumatic disease on CYP-mediated eicosanoid metabolism are necessary. Obtaining a better understanding of the complex role of CYP-derived eicosanoids in inflammatory rheumatic disease, such as rheumatoid arthritis will provide valuable insight for basic and clinical researchers investigation.

Eicosanoids derived from cytochrome P450 pathway of arachidonic acid and inflammatory shock

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Septic shock, the most common form of vasodilatory shock, is a subset of sepsis in which circulatory and cellular/metabolic abnormalities are severe enough to increase mortality. Inflammatory shock constitutes the hallmark of sepsis, but also a final common pathway of any form of severe long-term tissue hypoperfusion. The pathogenesis of inflammatory shock seems to be due to circulating substances released by pathogens (e.g., bacterial endotoxins) and host immuno-inflammatory responses (e.g., changes in the production of histamine, bradykinin, serotonin, nitric oxide [NO], reactive nitrogen and oxygen species, and arachidonic acid [AA]-derived eicosanoids mainly through NO synthase, cyclooxygenase, and cytochrome P450 [CYP] pathways, and proinflammatory cytokine formation). Therefore, refractory hypotension to vasoconstrictors with end-organ hypoperfusion is a life threatening feature of inflammatory shock. This review summarizes the current knowledge regarding the role of eicosanoids derived from CYP pathway of AA in animal models of inflammatory shock syndromes with an emphasis on septic shock in addition to potential therapeutic strategies targeting specific CYP isoforms responsible for proinflammatory/anti-inflammatory mediator production.

Integrated omics-based pathway analyses uncover CYP epoxygenase-associated networks as theranostic targets for metastatic triple negative breast cancer

Background

Current prognostic tools and targeted therapeutic approaches have limited value for metastatic triple negative breast cancer (TNBC). Building upon current knowledge, we hypothesized that epoxyeicosatrienoic acids (EETs) and related CYP450 epoxygenases may have differential roles in breast cancer signaling, and better understanding of which may uncover potential directions for molecular stratification and personalized therapy for TNBC patients.

Methods

We analyzed the oxylipin metabolome of paired tumors and adjacent normal mammary tissues from patients with pathologically confirmed breast cancer (N = 62). We used multivariate statistical analysis to identify important metabolite contributors and to determine the predictive power of tumor tissue metabolite clustering. In vitro functional assays using a panel of breast cancer cell lines were carried out to further confirm the crucial roles of endogenous and exogenous EETs in the metastasis transformation of TNBC cells. Deregulation of associated downstream signaling networks associated with EETs/CYPs was established using transcriptomics datasets from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC). Comparative TNBC proteomics using the same tissue specimens subjected to oxylipin metabolomics analysis was used as validation set.

Results

Metabolite-by-metabolite comparison, tumor immunoreactivity, and gene expression analyses showed that CYP epoxygenases and arachidonic acid-epoxygenation products, EET metabolites, are strongly associated with TNBC metastasis. Notably, all the 4 EET isomers (5,6-, 8,9-, 11,12-, and 14,15-EET) was observed to profoundly drive the metastasis transformation of mesenchymal-like TNBC cells among the TNBC (basal- and mesenchymal-like), HER2-overexpressing and luminal breast cancer cell lines examined. Our pathway analysis revealed that, in hormone-positive breast cancer subtype, CYP epoxygenase overexpression is more related to immune cell-associated signaling, while EET-mediated Myc, Ras, MAPK, EGFR, HIF-1α, and NOD1/2 signaling are the molecular vulnerabilities of metastatic CYP epoxygenase-overexpressing TNBC tumors.

Conclusions

This study suggests that categorizing breast tumors according to their EET metabolite ratio classifiers and CYP epoxygenase profiles may be useful for prognostic and therapeutic assessment. Modulation of CYP epoxygenase and EET-mediated signaling networks may offer an effective approach for personalized treatment of breast cancer, and may be an effective intervention option for metastatic TNBC patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1187-y) contains supplementary material, which is available to authorized users.

Dronedarone-Induced Cardiac Mitochondrial Dysfunction and Its Mitigation by Epoxyeicosatrienoic Acids

Dronedarone and amiodarone are structurally similar antiarrhythmic drugs. Dronedarone worsens cardiac adverse effects with unknown causes while amiodarone has no cardiac adversity. Dronedarone induces preclinical mitochondrial toxicity in rat liver and exhibits clinical hepatotoxicity. Here, we further investigated the relative potential of the antiarrhythmic drugs in causing mitochondrial injury in cardiomyocytes. Differentiated rat H9c2 cardiomyocytes were treated with dronedarone, amiodarone, and their respective metabolites namely N-desbutyldronedarone (NDBD) and N-desethylamiodarone (NDEA). Intracellular ATP content, mitochondrial membrane potential (Δψm), and inhibition of carnitine palmitoyltransferase I (CPT1) activity and arachidonic acid (AA) metabolism were measured in H9c2 cells. Inhibition of electron transport chain (ETC) activities and uncoupling of ETC were further studied in isolated rat heart mitochondria. Dronedarone, amiodarone, NDBD and NDEA decreased intracellular ATP content significantly (IC50 = 0.49, 1.84, 1.07, and 0.63 µM, respectively) and dissipated Δψm potently (IC50 = 0.5, 2.94, 12.8, and 7.38 µM, respectively). Dronedarone, NDBD, and NDEA weakly inhibited CPT1 activity while amiodarone (IC50 > 100 µM) yielded negligible inhibition. Only dronedarone inhibited AA metabolism to its regioisomeric epoxyeicosatrienoic acids (EETs) consistently and potently. NADH-supplemented ETC activity was inhibited by dronedarone, amiodarone, NDBD and NDEA (IC50 = 3.07, 5.24, 11.94, and 16.16 µM, respectively). Cytotoxicity, ATP decrease and Δψm disruption were ameliorated via exogenous pre-treatment of H9c2 cells with 11, 12-EET and 14, 15-EET. Our study confirmed that dronedarone causes mitochondrial injury in cardiomyocytes by perturbing Δψm, inhibiting mitochondrial complex I, uncoupling ETC and dysregulating AA-EET metabolism. We postulate that cardiac mitochondrial injury is one potential contributing factor to dronedarone-induced cardiac failure exacerbation.

A sensitive and improved throughput UPLC-MS/MS quantitation method of total cytochrome P450 mediated arachidonic acid metabolites that can separate regio-isomers and cis/trans-EETs from human plasma

A method for the detection and quantification of hydroxyl and epoxy arachidonic acid (AA) metabolites in human plasma was developed using liquid-liquid extraction, phospholipid saponification followed by derivatization of the acid moiety and liquid chromatographic tandem mass spectrometric detection. Derivatization with a pyridinium analog allowed for detection in the positive ion mode, greatly improving sensitivity and the stability of the more labile AA metabolites. The entire method utilizes a 96-well plate format, increasing sample throughput, and was optimized to measure 5-, 8-, 9-, 11-, 12-, 15-, 19-, and 20- hydroxyeicosatetraenoic acid (HETE), 5,6-, 8,9-, 11,12-, and 14,15- dihydroxyeicosatrienoic acid (DHET), and the regio- and cis-/ trans- isomers of 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid (EET). The method was validated for its applicability over the FA concentration range found in human plasma. Using 100 μL aliquots of pooled human plasma, EET levels, particularly 5,6-EET, were observed to be higher than previously reported, with measured concentrations of 23.6 ng/ml for 5,6-EET, 5.6 ng/mL for 5,6-trans-EET, 8.0 ng/mL for 8,9-EET, 1.9 ng/mL for 8,9-trans-EET, 8.8 ng/mL for 11,12-EET, 3.4 ng/mL for 11,12-trans-EET, 10.7 ng/mL for 14,15-EET, and 1.7 ng/mL 14,15-trans- EET. This method is suitable for large population studies to elucidate the complex interactions between the eicosanoids and various disease states and may be used for quantitation of a wide variety of fattyacids beyond eicosanoids from small volumes of human plasma.

Regulation of CYP2J2 and EET Levels in Cardiac Disease and Diabetes

Cytochrome P450 2J2 (CYP2J2) is a known arachidonic acid (AA) epoxygenase that mediates the formation of four bioactive regioisomers of cis-epoxyeicosatrienoic acids (EETs). Although its expression in the liver is low, CYP2J2 is mainly observed in extrahepatic tissues, including the small intestine, pancreas, lung, and heart. Changes in CYP2J2 levels or activity by xenobiotics, disease states, or polymorphisms are proposed to lead to various organ dysfunctions. Several studies have investigated the regulation of CYP2J2 and EET formation in various cell lines and have demonstrated that such regulation is tissue-dependent. In addition, studies linking CYP2J2 polymorphisms to the risk of developing cardiovascular disease (CVD) yielded contradictory results. This review will focus on the mechanisms of regulation of CYP2J2 by inducers, inhibitors, and oxidative stress modeling certain disease states in various cell lines and tissues. The implication of CYP2J2 expression, polymorphisms, activity and, as a result, EET levels in the pathophysiology of diabetes and CVD will also be discussed.

An Integrated Lipidomics and Phenotype Study Reveals Protective Effect and Biochemical Mechanism of Traditionally Used Alisma orientale Juzepzuk in Chronic Kidney Disease

Alisma orientale Juzepzuk (AO) is widely used for various diuretic and nephropathic treatments in traditional Chinese medicines (TCM). In a clinical setting, AO is used as both a lipid-lowering and tubular interstitial fibrosis agent. However, the mechanisms of AO for the treatment of renal interstitial fibrosis and abnormal lipid metabolism are not well-understood. In this study, pharmacological and UPLC-HDMS-based lipidomic approaches were employed to investigate the lipid-lowering and tubular interstitial fibrosis effect of AO on rats with adenine-induced chronic kidney disease (CKD). Rats with CKD showed increased serum levels of creatinine and urea, tubular damage, and tubular interstitial fibrosis. Moreover, multiple lipid species were identified in CKD rats. Among these lipids, polyunsaturated fatty acid, eicosapentaenoic acid, 8,9-epoxyeicosatrienoic acid, and docosahexaenoic acid levels were significantly decreased in CKD rats compared to control rats. In CKD rats, up-regulation of the NF-κB pathway may impair polyunsaturated fatty acid metabolism, causing renal fibrosis. In addition, CKD rats showed significantly decreased diglyceride levels and increased triglyceride levels compared to the control group. Pathway over-representation analysis demonstrated that 30 metabolic pathways were associated with lipid species. AO treatment suppressed up-regulation of inflammation, and partly restored the deregulation of polyunsaturated fatty acids and glycerolipids metabolism. Our results indicated that AO treatment attenuated renal fibrosis by down-regulating inflammation, and mitigating lipid metabolism in CKD rats. In conclusion, this study has identified the therapeutic lipid-lowering and anti-fibrosis effects of AO on CKD.

Enzymatic and free radical formation of cis- and trans- epoxyeicosatrienoic acids in vitro and in vivo

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid (AA) oxidation that have important cardioprotective and signaling properties. AA is an ω-6 polyunsaturated fatty acid (PUFA) that is prone to autoxidation. Although hydroperoxides and isoprostanes are major autoxidation products of AA, EETs are also formed from the largely overlooked peroxyl radical addition mechanism. While autoxidation yields both cis- and trans-EETs, cytochrome P450 (CYP) epoxygenases have been shown to exclusively catalyze the formation of all regioisomer cis-EETs, on each of the double bonds. In plasma and red blood cell (RBC) membranes, cis- and trans-EETs have been observed, and both have multiple physiological functions. We developed a sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay that separates cis- and trans- isomers of EETs and applied it to determine the relative distribution of cis- vs. trans-EETs in reaction mixtures of AA subjected to free radical oxidation in benzene and liposomes in vitro. We also determined the in vivo distribution of EETs in several tissues, including human and mouse heart, and RBC membranes. We then measured EET levels in heart and RBC of young mice compared to old. Formation of EETs in free radical reactions of AA in benzene and in liposomes exhibited time- and AA concentration-dependent increase and trans-EET levels were higher than cis-EETs under both conditions. In contrast, cis-EET levels were overall higher in biological samples. In general, trans-EETs increased with mouse age more than cis-EETs. We propose a mechanism for the non-enzymatic formation of cis- and trans-EETs involving addition of the peroxyl radical to one of AA's double bonds followed by bond rotation and intramolecular homolytic substitution (S_Hi). Enzymatic formation of cis-EETs by cytochrome P450 most likely occurs via a one-step concerted mechanism that does not allow bond rotation. The ability to accurately measure circulating EETs resulting from autoxidation or enzymatic reactions in plasma and RBC membranes will allow for future studies investigating how these important signaling lipids correlate with heart disease outcomes.

Altered Protein Expression of Cardiac CYP2J and Hepatic CYP2C, CYP4A, and CYP4F in a Mouse Model of Type II Diabetes-A Link in the Onset and Development of Cardiovascular Disease?

Arachidonic acid can be metabolized by cytochrome P450 (CYP450) enzymes in a tissue- and cell-specific manner to generate vasoactive products such as epoxyeicosatrienoic acids (EETs-cardioprotective) and hydroxyeicosatetraenoic acids (HETEs-cardiotoxic). Type II diabetes is a well-recognized risk factor for developing cardiovascular disease. A mouse model of Type II diabetes (C57BLKS/J-db/db) was used. After sacrifice, livers and hearts were collected, washed, and snap frozen. Total proteins were extracted. Western blots were performed to assess cardiac CYP2J and hepatic CYP2C, CYP4A, and CYP4F protein expression, respectively. Significant decreases in relative protein expression of cardiac CYP2J and hepatic CYP2C were observed in Type II diabetes animals compared to controls (CYP2J: 0.80 ± 0.03 vs. 1.05 ± 0.06, n = 20, p < 0.001); (CYP2C: 1.56 ± 0.17 vs. 2.21 ± 0.19, n = 19, p < 0.01). In contrast, significant increases in relative protein expression of both hepatic CYP4A and CYP4F were noted in Type II diabetes mice compared to controls (CYP4A: 1.06 ± 0.09 vs. 0.18 ± 0.01, n = 19, p < 0.001); (CYP4F: 2.53 ± 0.22 vs. 1.10 ± 0.07, n = 19, p < 0.001). These alterations induced by Type II diabetes in the endogenous pathway (CYP450) of arachidonic acid metabolism may increase the risk for cardiovascular disease by disrupting the fine equilibrium between cardioprotective (CYP2J/CYP2C-generated) and cardiotoxic (CYP4A/CYP4F-generated) metabolites of arachidonic acid.

Beyond detoxification: a role for mouse mEH in the hepatic metabolism of endogenous lipids

Microsomal and soluble epoxide hydrolase (mEH and sEH) fulfill apparently distinct roles: Whereas mEH detoxifies xenobiotics, sEH hydrolyzes fatty acid (FA) signaling molecules and is thus implicated in a variety of physiological functions. These epoxy FAs comprise epoxyeicosatrienoic acids (EETs) and epoxy-octadecenoic acids (EpOMEs), which are formed by CYP epoxygenases from arachidonic acid (AA) and linoleic acid, respectively, and then are hydrolyzed to their respective diols, the so-called DHETs and DiHOMEs. Although EETs and EpOMEs are also substrates for mEH, its role in lipid signaling is considered minor due to lower abundance and activity relative to sEH. Surprisingly, we found that in plasma from mEH KO mice, hydrolysis rates for 8,9-EET and 9,10-EpOME were reduced by 50% compared to WT plasma. This strongly suggests that mEH contributes substantially to the turnover of these FA epoxides—despite kinetic parameters being in favor of sEH. Given the crucial role of liver in controlling plasma diol levels, we next studied the capacity of sEH and mEH KO liver microsomes to synthesize DHETs with varying concentrations of AA (1–30 μM) and NADPH. mEH-generated DHET levels were similar to the ones generated by sEH, when AA concentrations were low (1 μM) or epoxygenase activity was curbed by modulating NADPH. With increasing AA concentrations sEH became more dominant and with 30 μM AA produced twice the level of DHETs compared to mEH. Immunohistochemistry of C57BL/6 liver slices further revealed that mEH expression was more widespread than sEH expression. mEH immunoreactivity was detected in hepatocytes, Kupffer cells, endothelial cells, and bile duct epithelial cells, while sEH immunoreactivity was confined to hepatocytes and bile duct epithelial cells. Finally, transcriptome analysis of WT, mEH KO, and sEH KO liver was carried out to discern transcriptional changes associated with the loss of EH genes along the CYP-epoxygenase–EH axis. We found several prominent dysregulations occurring in a parallel manner in both KO livers: (a) gene expression of Ephx1 (encoding for mEH protein) was increased 1.35-fold in sEH KO, while expression of Ephx2 (encoding for sEH protein) was increased 1.4-fold in mEH KO liver; (b) Cyp2c genes, encoding for the predominant epoxygenases in mouse liver, were mostly dysregulated in the same manner in both sEH and mEH KO mice, showing that loss of either EH has a similar impact. Taken together, mEH appears to play a leading role in the hydrolysis of 8,9-EET and 9,10-EpOME and also contributes to the hydrolysis of other FA epoxides. It probably profits from its high affinity for FA epoxides under non-saturating conditions and its close physical proximity to CYP epoxygenases, and compensates its lower abundance by a more widespread expression, being the only EH present in several sEH-lacking cell types.

CYP2C19 variants and epoxyeicosatrienoic acids in patients with microvascular angina

BACKGROUND

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the impact of CYP2C19 polymorphisms and EETs on the patients with microvascular angina (MVA) caused by coronary microvascular dysfunction.

METHODS AND RESULTS

We examined CYP2C19 genotypes in patients with MVA (n = 81). MVA was defined as absence of coronary artery stenosis and epicardial spasms, and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. In MVA, the patients with CYP2C19 PM were 34.6% and high sense C-reactive protein (hs-CRP) levels in CYP2C19 PM were significantly higher than that of non-PM group (0.165 ± 0.116 vs. 0.097 ± 0.113 mg/dL, P = 0.026). Moreover, DHET levels in CYP2C19 PM were significantly lower than that of non-PM (10.4 ± 4.58 vs. 15.6 ± 11.1 ng/mL, P = 0.003 (11,12-DHET); 12.1 ± 3.79 vs. 17.3 ± 6.49 ng/mL, P = 0.019 (14,15-DHET)).

CONCLUSIONS

The decline of EET owing to CYP2C19 variants may affects coronary microvascular dysfunction via chronic inflammation.

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.

Long-chain acyl-CoA synthetase isoforms differ in preferences for eicosanoid species and long-chain fatty acids

Because the signaling eicosanoids, epoxyeicosatrienoic acids (EETs) and HETEs, are esterified to membrane phospholipids, we asked which long-chain acyl-CoA synthetase (ACSL) isoforms would activate these molecules and whether the apparent FA substrate preferences of each ACSL isoform might differ depending on whether it was assayed in mammalian cell membranes or as a purified bacterial recombinant protein. We found that all five ACSL isoforms were able to use EETs and HETEs as substrates and showed by LC-MS/MS that ACSLs produce EET-CoAs. We found differences in substrate preference between ACS assays performed in COS7 cell membranes and recombinant purified proteins. Similarly, preferences and Michaelis-Menten kinetics for long-chain FAs were distinctive. Substrate preferences identified for the purified ACSLs did not correspond to those observed in ACSL-deficient mouse models. Taken together, these data support the concept that each ACSL isoform exhibits a distinct substrate preference, but apparent substrate specificities depend upon multiple factors including membrane character, coactivators, inhibitors, protein interactions, and posttranslational modification.

Association of CYP2C19 variants and epoxyeicosatrienoic acids on patients with microvascular angina

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the association of CYP2C19 polymorphisms and EETs on microvascular angina (MVA) caused by coronary microvascular dysfunction. We examined CYP2C19 genotypes in patients with MVA ( n = 71) and healthy subjects as control ( n = 71). MVA was defined as the absence of coronary artery stenosis and epicardial spasms and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. MVA group showed significantly higher CYP2C19 PM incidence (35% vs. 16%; P = 0.007) and high sense C-reactive protein (hs-CRP) levels (0.127 ± 0.142 vs. 0.086 ± 0.097 mg/dl; P = 0.043) than those of controls. Moreover, in MVA group, hs-CRP levels in CYP2C19 PM were significantly higher than that of non-PM (0.180 ± 0.107 vs. 0.106 ± 0.149 mg/dl, P = 0.045). Multivariate analysis indicated that smoking, hypertension, high hs-CRP, and CYP2C19 PM are predictive factors for MVA. In MVA group, DHET levels for CYP2C19 PM were significantly lower than that of non-PM [10.9 ± 1.64 vs. 14.2 ± 5.39 ng/ml, P = 0.019 (11,12-DHET); 15.2 ± 4.39 vs. 17.9 ± 4.73 ng/ml, P = 0.025 (14,15-DHET)]. CYP2C19 variants are associated with MVA. The decline of EET-based defensive mechanisms owing to CYP2C19 variants may affect coronary microvascular dysfunction.

CYPC19*17 POLYMORPHISM AS A RISK-FACTOR FOR NSAIDS-INDUCED ULCERS

The new risk-factors for peptic ulcers induced by the use of nonsteroidal antiinflammatory drugs, such as polymorphism of different isoenzymes of cytochrome P450 were considered in the article. The aim of the research was to study different genetic polymorphism of several ferments CYP2C9 and CYP2C19 in inclination to NSAIDS-gastropathies by the way of estimation the risk of appearance of Helicobacter pylori (HP)-positive or Hp-negative NSAIDS- induced peptic ulcers, complicated or not with upper gastrointestinal bleeding. 124 persons were examined (76 men, 48 women in the age of 56,2+/–9,1 years) with Hp-positive or Hp-negative NSAIDS-induced peptic ulcers, that were performed genotyping of isoferments of cytochrome system (CYP2C9, CYP2C19). Based on investigations of 5 different isoenzymes (CYP 2C9*2, CYP 2C9*3, CYP 2C19*2, CYP 2C19*3 and CYP 2C19*17). It was founded that peptic ulcers are strictly associated only with CYP 2C19*17-genotype, possibly due to its involvement in arachidonic acid metabolism and gastroprotection. Thus, polymorphism CYP 2C19*17 can be considered as one of the risk factors for NSAID-gastropathy though the future researches are needed.

Cytochrome P450 ω-Hydroxylases in Inflammation and Cancer

Cytochrome P450-dependent ω-hydroxylation is a prototypic metabolic reaction of CYP4 family members that is important for the elimination and bioactivation of not only therapeutic drugs, but also endogenous compounds, principally fatty acids. Eicosanoids, derived from arachidonic acid, are key substrates in the latter category. Human CYP4 enzymes, mainly CYP4A11, CYP4F2, and CYP4F3B, hydroxylate arachidonic acid at the omega position to form 20-HETE, which has important effects in tumor progression and on angiogenesis and blood pressure regulation in the vasculature and kidney. CYP4F3A in myeloid tissue catalyzes the ω-hydroxylation of leukotriene B4 to 20-hydroxy leukotriene B4, an inactivation process that is critical for the regulation of the inflammatory response. Here, we review the enzymology, tissue distribution, and substrate selectivity of human CYP4 ω-hydroxylases and their roles as catalysts for the formation and termination of the biological effects of key eicosanoid metabolites in inflammation and cancer progression.

In vitro inhibitory effects of ethanol extract of Danshen (Salvia miltiorrhiza) and its components on the catalytic activity of soluble epoxide hydrolase

BACKGROUND

Soluble epoxide hydrolase (sEH) has been demonstrated to be a key enzyme involved in the pathologic development of several cardiovascular diseases and inflammation, and inhibition of sEH is therefore very helpful or crucial for the treatment of ischemia-reperfusion injury, cardiac hypertrophy, hypertension and inflammation. Danshen, the dried root of Salvia miltiorrhiza (Fam. Labiatae), has been used for the treatment of cardiovascular and cerebrovascular diseases in China and other countries for hundreds of years. Recent studies indicated that Danshen and its preparations also have potential for the management of inflammation. However, little information is available about the possibility of Danshen and its components on sEH inhibition.

PURPOSE AND METHODS

Danshen extracts and its constituents were tested for sEH inhibition using its physiological substrate, 8,9-EET, based on a LC-MS/MS assay in this study.

RESULTS

Among the tested 15 compounds, tanshinone IIA and cryptotanshinone were found to be the potent (Ki = 0.87 μM) and medium (Ki = 6.7 μM) mixed-type inhibitors of sEH, respectively. Salvianolic acid C (Ki = 8.6 μM) was proved to be a moderate noncompetitive sEH inhibitor. In consistent with the inhibition results of the pure compounds, the 75% ethanol extract of Danshen (EE, IC50 = 86.5 μg/ml) which contained more tanshinone IIA and cryptotanshinone exhibited more potent inhibition on sEH than the water extract (WE, IC50 > 200 μg/ml) or 1 M NaHCO3 (BE, IC50 > 200 μg/ml) extract.

CONCLUSION

These data indicated that using the ethanol fraction of Danshen and increasing the amounts of tanshinone IIA, cryptotanshinone and salvianolic acid C, especially the contents of tanshinone IIA in Danshen extract or preparations to enhance the inhibitory effects on sEH might be efficient ways to improve its cardiovascular protective and anti-inflammatory effects, and that herbal medicines could be an untapped reservoir for sEH-inhibition agents and developing sEH inhibitors from the cardiovascular protective and anti-inflammatory herbs is a promising approach.

Alterations in cytochrome P450-derived arachidonic acid metabolism during pressure overload-induced cardiac hypertrophy

Cardiac hypertrophy is a major risk factor for many serious heart diseases. Recent data demonstrated the role of cytochrome P450 (CYP)-derived arachidonic acid (AA) metabolites in cardiovascular pathophysiology. In the current study our aim was to determine the aberrations in CYP-mediated AA metabolism in the heart during cardiac hypertrophy. Pressure overload cardiac hypertrophy was induced in Sprague Dawley rats using the descending aortic constriction procedure. Five weeks post-surgery, the cardiac levels of AA metabolites were determined in hypertrophied and normal hearts. In addition, the formation rate of AA metabolites, as well as, CYP expression in cardiac microsomal fraction was also determined. AA metabolites were measured by liquid chromatography-electrospray ionization-mass spectroscopy, whereas, the expression of CYPs was determined by Western blot analysis. Non-parametric analysis was performed to examine the association between metabolites formation and CYP expressions. Our results showed that 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs), and 5-, 12-, 15-, and 20-hydroxyeicosatetraenoic acids (HETEs) levels were increased, whereas, 19-HETE formation was decreased in hypertrophied hearts. The increase in EETs was linked to CYP2B2. On the other hand, CYP1B1 and CYP2J3 were involved in mid-chain HETE metabolism, whereas, CYP4A2/3 inhibition was involved in the decrease in 19-HETE formation in hypertrophied hearts. In conclusion, CYP1B1 played cardiotoxic role, whereas, CYP2B2, CYP2J3 and CYP4A2/3 played cardioprotective roles during pressure overload-induced cardiac hypertrophy. These CYP can be valid targets for the development of drugs to treat and prevent cardiac hypertrophy and heart failure.

Epoxyeicosanoids promote organ and tissue regeneration

Epoxyeicosatrienoic acids (EETs), lipid mediators produced by cytochrome P450 epoxygenases, regulate inflammation, angiogenesis, and vascular tone. Despite pleiotropic effects on cells, the role of these epoxyeicosanoids in normal organ and tissue regeneration remains unknown. EETs are produced predominantly in the endothelium. Normal organ and tissue regeneration require an active paracrine role of the microvascular endothelium, which in turn depends on angiogenic growth factors. Thus, we hypothesize that endothelial cells stimulate organ and tissue regeneration via production of bioactive EETs. To determine whether endothelial-derived EETs affect physiologic tissue growth in vivo, we used genetic and pharmacological tools to manipulate endogenous EET levels. We show that endothelial-derived EETs play a critical role in accelerating tissue growth in vivo, including liver regeneration, kidney compensatory growth, lung compensatory growth, wound healing, corneal neovascularization, and retinal vascularization. Administration of synthetic EETs recapitulated these results, whereas lowering EET levels, either genetically or pharmacologically, delayed tissue regeneration, demonstrating that pharmacological modulation of EETs can affect normal organ and tissue growth. We also show that soluble epoxide hydrolase inhibitors, which elevate endogenous EET levels, promote liver and lung regeneration. Thus, our observations indicate a central role for EETs in organ and tissue regeneration and their contribution to tissue homeostasis.

Radiosensitivity of human prostate cancer cells can be modulated by inhibition of 12-lipoxygenase

Nearly 30% of prostate cancer (PCa) patients treated with potentially curative doses relapse at the sites of irradiation. How some tumor cells acquire radioresistance is poorly understood. The platelet-type 12-lipoxygenases (12-LOX)-mediated arachidonic acid metabolism is important in PCa progression. Here we show that 12-LOX confers radioresistance upon PCa cells. Treatment with 12-LOX inhibitors baicalein or BMD122 sensitizes PCa cells to radiation, without radiosensitizing normal cells. 12-LOX inhibitors and radiation, when combined, have super additive or synergistic inhibitory effects on the colony formation of both androgen-dependent LNCaP and androgen-independent PC-3 PCa cells. In vivo, the combination therapy significantly reduced tumor growth.

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.

Upregulation of soluble epoxide hydrolase in proximal tubular cells mediated proteinuria-induced renal damage

Epoxyeicosatrienoic acids, hydrolyzed by soluble epoxide hydrolase (sEH), have multiple biological functions, including the regulation of vascular tone, renal tubular transport, and being anti-inflammatory. Inhibitors of sEH have been demonstrated to be antihypertensive and renal protective. To elucidate the role of sEH in glomerulonephritis, we first determined the expression of sEH in human kidney by examining biopsies from 153 patients with a variety of glomerulonephritis, including minimal-change, membranous, and IgA nephropathy. Immunohistochemical staining of frozen kidney biopsy samples revealed sEH preferentially expressed in the renal proximal tubular cells, and its expression increased in all patients with glomerulonephritis. The level of sEH in the cortex was positively correlated with proteinuria and negatively with serum albumin level. To investigate the role of sEH in proteinuria-induced renal damage, we incubated purified urine protein from patients with rat renal proximal tubular epithelial cells in vitro. The level of sEH was elevated, as were monocyte chemoattractant protein 1 and the process of tubular epithelial-to-mesenchymal transition, characterized with increased α-smooth muscle actin (α-SMA) and decreased E-cadherin. These effects were attenuated by administration of a potent sEH inhibitor and mimicked with adenovirus-mediated sEH overexpression. In adriamycin-induced nephropathic mice, sEH inhibitor did not ameliorate proteinuria or level of serum albumin but reduced the long-term elevated serum creatinine level, interstitial inflammation, fibrosis, and α-SMA expression. Thus upregulation of sEH in proximal tubular cells in chronic proteinuric kidney diseases may mediate proteinuria-induced renal damage; sEH inhibition by increasing renal eicosanoid levels could prevent the progression of chronic proteinuric kidney diseases.