Cytochrome P450 epoxygenase CYP2J2 attenuates nephropathy in streptozotocin-induced diabetic mice

Oxidative Stress: A Culprit in the Progression of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the principal culprit behind chronic kidney disease (CKD), ultimately developing end-stage renal disease (ESRD) and necessitating costly dialysis or kidney transplantation. The limited therapeutic efficiency among individuals with DKD is a result of our finite understanding of its pathogenesis. DKD is the result of complex interactions between various factors. Oxidative stress is a fundamental factor that can establish a link between hyperglycemia and the vascular complications frequently encountered in diabetes, particularly DKD. It is crucial to recognize the essential and integral role of oxidative stress in the development of diabetic vascular complications, particularly DKD. Hyperglycemia is the primary culprit that can trigger an upsurge in the production of reactive oxygen species (ROS), ultimately sparking oxidative stress. The main endogenous sources of ROS include mitochondrial ROS production, NADPH oxidases (Nox), uncoupled endothelial nitric oxide synthase (eNOS), xanthine oxidase (XO), cytochrome P450 (CYP450), and lipoxygenase. Under persistent high glucose levels, immune cells, the complement system, advanced glycation end products (AGEs), protein kinase C (PKC), polyol pathway, and the hexosamine pathway are activated. Consequently, the oxidant-antioxidant balance within the body is disrupted, which triggers a series of reactions in various downstream pathways, including phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), transforming growth factor beta/p38-mitogen-activated protein kinase (TGF-β/p38-MAPK), nuclear factor kappa B (NF-κB), adenosine monophosphate-activated protein kinase (AMPK), and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling. The disease might persist even if strict glucose control is achieved, which can be attributed to epigenetic modifications. The treatment of DKD remains an unresolved issue. Therefore, reducing ROS is an intriguing therapeutic target. The clinical trials have shown that bardoxolone methyl, a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, blood glucose-lowering drugs, such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists can effectively slow down the progression of DKD by reducing oxidative stress. Other antioxidants, including vitamins, lipoic acid, Nox inhibitors, epigenetic regulators, and complement inhibitors, present a promising therapeutic option for the treatment of DKD. In this review, we conduct a thorough assessment of both preclinical studies and current findings from clinical studies that focus on targeted interventions aimed at manipulating these pathways. We aim to provide a comprehensive overview of the current state of research in this area and identify key areas for future exploration.

Mechanism of Cornus Officinalis in Treating Diabetic Kidney Disease Based on Network Pharmacology

Diabetic kidney disease (DKD), one of the most important diabetic complications, is a great clinical challenge. It still lacks proper therapeutic strategies without side effects due to the complex pathological mechanisms. Cornus officinalis (CO) is a common traditional Chinese medicine, which has been used in the treatment of DKD and takes beneficial effects in therapy. However, the mechanism of CO in treating DKD is not clear yet. In this study, network pharmacology was applied to illustrate the potential mechanism of CO and the interaction between targets of CO and targets of disease. First, the active ingredients of CO and related targets were screened from the online database. Second, the intersection network between CO and disease was constructed, and protein–protein interaction analysis was done. Third, GO and KEGG analysis were employed to figure out the key targets of CO. Finally, molecular docking was carried out in the software SYBYL to verify the effectiveness of the ingredients and targets selected. According to GO and KEGG analysis, drug metabolism-cytochrome P450, sphingolipid signaling pathway, HIF-1 signaling pathway, TGF-beta signaling pathway, cGMP-PKG signaling pathway, estrogen signaling pathway, and TNF signaling pathway were most closely related to the pathogenesis of DKD. Moreover, NOS3, TNF, ROCK1, PPARG, KDR, and HIF1A were identified as key targets in regulating the occurrence and development of the disease. This study provides evidence to elucidate the mechanism of CO comprehensively and systematically and lays the foundation for further research on CO.

CYP450 Epoxygenase Metabolites, Epoxyeicosatrienoic Acids, as Novel Anti-Inflammatory Mediators

Inflammation plays a crucial role in the initiation and development of a wide range of systemic illnesses. Epoxyeicosatrienoic acids (EETs) are derived from arachidonic acid (AA) metabolized by CYP450 epoxygenase (CYP450) and are subsequently hydrolyzed by soluble epoxide hydrolase (sEH) to dihydroxyeicosatrienoic acids (DHETs), which are merely biologically active. EETs possess a wide range of established protective effects on many systems of which anti-inflammatory actions have gained great interest. EETs attenuate vascular inflammation and remodeling by inhibiting activation of endothelial cells and reducing cross-talk between inflammatory cells and blood vessels. EETs also process direct and indirect anti-inflammatory properties in the myocardium and therefore alleviate inflammatory cardiomyopathy and cardiac remodeling. Moreover, emerging studies show the substantial roles of EETs in relieving inflammation under other pathophysiological environments, such as diabetes, sepsis, lung injuries, neurodegenerative disease, hepatic diseases, kidney injury, and arthritis. Furthermore, pharmacological manipulations of the AA-CYP450-EETs-sEH pathway have demonstrated a contribution to the alleviation of numerous inflammatory diseases, which highlight a therapeutic potential of drugs targeting this pathway. This review summarizes the progress of AA-CYP450-EETs-sEH pathway in regulation of inflammation under different pathological conditions and discusses the existing challenges and future direction of this research field.

Lentinan Protects against Nonalcoholic Fatty Liver Disease by Reducing Oxidative Stress and Apoptosis via the PPARα Pathway

Lentinan (LNT), a type of polysaccharide derived from Lentinus edodes, has manifested protective effects during liver injury and hepatocellular carcinoma, but little is known about its effects on nonalcoholic fatty liver disease (NAFLD). This study aimed to investigate whether LNT can affect the progression of NAFLD and the associated mechanisms. C57BL/6J mice were fed a normal chow diet or a high-fat diet (HFD) with or without LNT (6 mg/kg/d). AML12 cells were exposed to 200 μM palmitate acid (PA) with or without LNT (5 μg/mL). After 21 wk of the high-fat diet, LNT significantly decreased plasma triglyceride levels and liver lipid accumulation, reduced excessive reactive oxygen species production, and subsequently attenuated hepatic apoptosis in NAFLD mice. These effects were associated with increased PPARα levels, a decreased Bax/Bcl-2 ratio, and enhancement of the antioxidant defense system in vivo. Similar effects were also observed in cultured cells. More importantly, these protective effects of LNT on palmitate acid-treated AML12 cells were almost abolished by PPARα knockdown. In conclusion, this study demonstrates that LNT may ameliorate hepatic steatosis and decrease oxidative stress and apoptosis by activating the PPARα pathway and is a potential drug target for NAFLD.

Increased lipoxygenase and decreased cytochrome P450s metabolites correlated with the incidence of diabetic nephropathy: Potential role of eicosanoids from metabolomics in type 2 diabetic patients

Diabetic nephropathy (DN) is the major cause of chronic kidney disease and end-stage renal disease. Previous studies have demonstrated that long-chain omega-3 polyunsaturated fatty acids (PUFAs) might have therapeutic potential in reducing proteinuria in DN. However, the local level of eicosanoids derived from PUFAs in the plasma of DN patients remains unclear. This work aims to study the eicosanoid profile difference in plasma of DN patients and type 2 diabetes (T2D) without DN. A total of 27 T2D patients with similar diabetic duration were recruited and divided into T2D+DN group and T2D+NDN (non-DN) group based on urinary albumin excretion (UAE) detection. Using LC-MS/MS-based metabolomics, DN patients showed increased level of lipoxygenase (LOX) metabolites (5-HETE and LTB4) and decreased levels of eicosanoids derived according to the cytochrome P450s (CYP450) metabolic pathway (5,6-DHET; 14,15-DHET and 9,10-diHOME). Receiver operating characteristics and logistic regression analysis revealed increased level LOX metabolites and decreased level of CYP450 metabolites were significantly correlated with the incidence of DN in T2D patients. LOX and CYP450 metabolites correlated with DN incidence in T2D patients, which might be treatment targets for DN in T2D patients.

Based on Network Pharmacology Tools to Investigate the Molecular Mechanism of Cordyceps sinensis on the Treatment of Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the most common complications of diabetes mellitus and is a major cause of end-stage kidney disease. Cordyceps sinensis (Cordyceps, Dong Chong Xia Cao) is a widely applied ingredient for treating patients with DN in China, while the molecular mechanisms remain unclear. This study is aimed at revealing the therapeutic mechanisms of Cordyceps in DN by undertaking a network pharmacology analysis.

MATERIALS AND METHODS

In this study, active ingredients and associated target proteins of Cordyceps sinensis were obtained via Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and Swiss Target Prediction platform, then reconfirmed by using PubChem databases. The collection of DN-related target genes was based on DisGeNET and GeneCards databases. A DN-Cordyceps common target interaction network was carried out via the STRING database, and the results were integrated and visualized by utilizing Cytoscape software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to determine the molecular mechanisms and therapeutic effects of Cordyceps on the treatment of DN.

RESULTS

Seven active ingredients were screened from Cordyceps, 293 putative target genes were identified, and 85 overlapping targets matched with DN were considered potential therapeutic targets, such as TNF, MAPK1, EGFR, ACE, and CASP3. The results of GO and KEGG analyses revealed that hub targets mainly participated in the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, PI3K-Akt signaling pathway, and IL-17 signaling pathway. These targets were correlated with inflammatory response, apoptosis, oxidative stress, insulin resistance, and other biological processes.

CONCLUSIONS

Our study showed that Cordyceps is characterized as multicomponent, multitarget, and multichannel. Cordyceps may play a crucial role in the treatment of DN by targeting TNF, MAPK1, EGFR, ACE, and CASP3 signaling and involved in the inflammatory response, apoptosis, oxidative stress, and insulin resistance.

Role of cytochrome P450-derived, polyunsaturated fatty acid mediators in diabetes and the metabolic syndrome

Over the last decade, cases of metabolic syndrome and type II diabetes have increased exponentially. Exercise and ω-3 polyunsaturated fatty acid (PUFA)-enriched diets are usually prescribed but no therapy is effectively able to restore the impaired glucose metabolism, hypertension, and atherogenic dyslipidemia encountered by diabetic patients. PUFAs are metabolized by different enzymes into bioactive metabolites with anti- or pro-inflammatory activity. One important class of PUFA metabolizing enzymes are the cytochrome P450 (CYP) enzymes that can generate a series of bioactive products, many of which have been attributed protective/anti-inflammatory and insulin-sensitizing effects in animal models. PUFA epoxides are, however, further metabolized by the soluble epoxide hydrolase (sEH) to fatty acid diols. The biological actions of the latter are less well understood but while low concentrations may be biologically important, higher concentrations of diols derived from linoleic acid and docosahexaenoic acid have been linked with inflammation. One potential application for sEH inhibitors is in the treatment of diabetic retinopathy where sEH expression and activity is elevated as are levels of a diol of docosahexaenoic acid that can induce the destabilization of the retina vasculature.

Activation of vitamin D receptor attenuates high glucose-induced cellular injury partially dependent on CYP2J5 in murine renal tubule epithelial cell

AIMS

Vitamin D and its receptor, vitamin D receptor (VDR), have renoprotection effect against diabetic nephropathy (DN). But the exact mechanism has not been fully elucidated. Epoxyeicosatrienoic acids (EETs) are cytochrome P450 (CYP) epoxygenase-derived metabolites of arachidonic acid, protecting against diabetes and DN. Herein, we hypothesized that activation of VDR attenuated high glucose-induced cellular injury in renal tubular epithelial cells partially through up-regulating CYP2J5 expression.

MAIN METHODS

Streptozotocin (STZ) was injected to induce diabetic in wild type and Vdr^-/- mice. The effects of VDR knockout and an activator of VDR, paricalcitol, on the renal injury were detected. In vitro, a murine kidney proximal tubule epithelial cell line BU.MPT induced by high glucose were treated with or without paricalcitol (30 mM) for 12 h or 24 h.

KEY FINDINGS

The expression of CYP2J5 was significantly decreased both in wild type and Vdr^-/- diabetic mice induced by STZ. The STZ-induced kidney architecture damage and apoptosis rate in Vdr^-/- mice were more severe. In vitro, high glucose treatment strongly reduced the CYP2J5 expression and the synthesis of 14,15-EET in BU.MPT cells. Supplement of 14,15-EET significantly reduced the lactate dehydrogenase (LDH) release induced by high glucose in BU.MPT cells. Furthermore, treatment with paricalcitol attenuated cellular injury and restored the expression of CYP2J5 reduced by high glucose in BU.MPT cells.

SIGNIFICANCE

We conclude that activation of VDR attenuates high glucose-induced cellular injury partially dependent on CYP2J5 in murine renal tubule epithelial cells and paricalcitol may represent a potential therapy for DN.

A Pilot Study towards the Impact of Type 2 Diabetes on the Expression and Activities of Drug Metabolizing Enzymes and Transporters in Human Duodenum

To characterize effects of type 2 diabetes (T2D) on mRNA expression levels for 10 Cytochromes P450 (CYP450s), two carboxylesterases, and three drug transporters (ABCB1, ABCG2, SLCO2B1) in human duodenal biopsies. To compare drug metabolizing enzyme activities of four CYP450 isoenzymes in duodenal biopsies from patients with or without T2D. mRNA levels were quantified (RT-qPCR) in human duodenal biopsies obtained from patients with (n = 20) or without (n = 16) T2D undergoing a scheduled gastro-intestinal endoscopy. CYP450 activities were determined following incubation of biopsy homogenates with probe substrates for CYP2B6 (bupropion), CYP2C9 (tolbutamide), CYP2J2 (ebastine), and CYP3A4/5 (midazolam). Covariables related to inflammation, T2D, demographic, and genetics were investigated. T2D had no major effects on mRNA levels of all enzymes and transporters assessed. Formation rates of metabolites (pmoles mg protein⁻¹ min⁻¹) determined by LC-MS/MS for CYP2C9 (0.48 ± 0.26 vs. 0.41 ± 0.12), CYP2J2 (2.16 ± 1.70 vs. 1.69 ± 0.93), and CYP3A (5.25 ± 3.72 vs. 5.02 ± 4.76) were not different between biopsies obtained from individuals with or without T2D (p > 0.05). No CYP2B6 specific activity was measured. TNF-α levels were higher in T2D patients but did not correlate with any changes in mRNA expression levels for drug metabolizing enzymes or transporters in the duodenum. T2D did not modulate expression or activity of tested drug metabolizing enzymes and transporters in the human duodenum. Previously reported changes in drug oral clearances in patients with T2D could be due to a tissue-specific disease modulation occurring in the liver and/or in other parts of the intestines.

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.

Association of EPHX2 R287Q Polymorphism with Diabetic Nephropathy in Chinese Type 2 Diabetic Patients

The aim of this study was to investigate the relationship between EPHX2 rs751141 (R287Q polymorphism) and diabetic nephropathy (DN) in Chinese type 2 diabetes (T2D). This case-control study explored the association between EPHX2 rs751141 and DN in a total of 870 Chinese T2D patients (406 T2D patients with DN and 464 T2D patients without DN). DNA was extracted from peripheral leukocytes of the patients and rs751141 was genotyped. The A allele frequency of rs751141 was significantly lower in DN patients (20.94%) compared with non-DN controls (27.8%) (P = 0.001), and the A allele of rs751141 was associated with a significantly lower risk of DN after adjustment for multiple covariates in the additive genetic model (OR = 0.68, 95% CI = 0.52-0.88, P = 0.004). Significant association between rs751141 and homocysteine (Hcy) level on the risk of DN was observed, indicating that in patients with the highest Hcy levels, the A allele showed marked association with lower risk of DN in all three genetic models. In conclusion, the A allele of exonic polymorphism in EPHX2 rs751141 is negatively associated with the incidence of DN in the Chinese T2D population, which could be modulated by Hcy level status.

Active maintenance of endothelial cells prevents kidney fibrosis

Background

Soluble epoxide hydrolase (sEH) expressed by endothelial cells catalyzes the metabolism of epoxyeicosatrienoic acids (EETs), which are vasoactive agents.

Methods

We used a unilateral ureteral obstruction mouse model of kidney fibrosis to determine whether inhibition of sEH activity reduces fibrosis, the final common pathway for chronic kidney disease.

Results

sEH activity was inhibited by continuous release of the inhibitor 12-(3-adamantan-1-ylureido)-dodecanoic acid (AUDA) for 1 or 2 weeks. Treatment with AUDA significantly ameliorated tubulointerstitial fibrosis by reducing fibroblast mobilization and enhancing endothelial cell activity. In an in vitro model of endothelial-to-mesenchymal transition (EndMT) using human vascular endothelial cells (HUVECs), AUDA prevented the morphologic changes associated with EndMT and reduced expression of fibroblast-specific protein 1. Furthermore, HUVECs activated by AUDA prevented the epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells in a co-culture system.

Conclusion

Our findings suggest that regulation of sEH is a potential target for therapies aimed at delaying the progression of kidney fibrosis by inhibiting EndMT and EMT.

Orally Active Epoxyeicosatrienoic Acid Analogs

Biologically active epoxyeicosatrienoic acid (EET) regioisomers are synthesized from arachidonic acid by cytochrome P450 epoxygenases of endothelial, myocardial, and renal tubular cells. EETs relax vascular smooth muscle and decrease inflammatory cell adhesion and cytokine release. Renal EETs promote sodium excretion and vasodilation to decrease hypertension. Cardiac EETs reduce infarct size after ischemia-reperfusion injury and decrease fibrosis and inflammation in heart failure. In diabetes, EETs improve insulin sensitivity, increase glucose tolerance, and reduce the renal injury. These actions of EETs emphasize their therapeutic potential. To minimize metabolic inactivation, 14,15-EET agonist analogs with stable epoxide bioisosteres and carboxyl surrogates were developed. In preclinical rat models, a subset of agonist analogs, termed EET-A, EET-B, and EET-C22, are orally active with good pharmacokinetic properties. These orally active EET agonists lower blood pressure and reduce cardiac and renal injury in spontaneous and angiotensin hypertension. Other beneficial cardiovascular actions include improved endothelial function and cardiac antiremodeling actions. In rats, EET analogs effectively combat acute and chronic kidney disease including drug- and radiation-induced kidney damage, hypertension and cardiorenal syndrome kidney damage, and metabolic syndrome and diabetes nephropathy. The compelling preclinical efficacy supports the prospect of advancing EET analogs to human clinical trials for kidney and cardiovascular diseases.

Expression of CYP4V2 in human THP1 macrophages and its transcriptional regulation by peroxisome proliferator-activated receptor gamma

Because macrophages respond to a variety of pathological and pharmacological reagents, understanding the role of P450s in macrophages is important for therapeutic intervention. There has been a lack of research on CYP4 in macrophages, but fatty acid accumulation and lipid trafficking in macrophages have been suggested to be a main cause of atherosclerosis. All human CYP4 genes (n=12) were screened in THP1 macrophages by gene-specific reverse transcriptase-polymerase chain reaction (RT-PCR). Only CYP4V2 exhibited strong expression of both mRNA and protein. Expression levels of both CYP4V2 mRNA and protein were significantly reduced after treatment with peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662. However, the expression levels of CYP4V2 were not changed by PPARα antagonist (GW6471) and liver X receptor alpha antagonist (22-S hydroxycholesterol). A metabolite of the CYP4V2 enzyme, 12-hydroxydodecanoic acid, was detected in THP1 macrophages, and this metabolite was significantly decreased after treatment with the PPARγ inhibitor GW9662 (>80% decreased, p<0.05). In summary, fatty acid metabolizing protein CYP4V2 was identified in human THP1 macrophages, and its expression was regulated by PPARγ. Further study is required to understand the role of CYP4V2 with regard to fat accumulation in the activated macrophage and atherosclerotic plaque development.

Effect of Cytochrome P450 Metabolites of Arachidonic Acid in Nephrology

Thirty-five years ago, a third pathway for the metabolism of arachidonic acid by cytochrome P450 enzymes emerged. Subsequent work revealed that 20-hydroxyeicosatetraenoic and epoxyeicosatrienoic acids formed by these pathways have essential roles in the regulation of renal tubular and vascular function. Sequence variants in the genes that produce 20-hydroxyeicosatetraenoic acid are associated with hypertension in humans, whereas the evidence supporting a role for variants in the genes that alter levels of epoxyeicosatrienoic acids is less convincing. Studies in animal models suggest that changes in the production of cytochrome P450 eicosanoids alter BP. However, the mechanisms involved remain controversial, especially for 20-hydroxyeicosatetraenoic acid, which has both vasoconstrictive and natriuretic actions. Epoxyeicosatrienoic acids are vasodilators with anti-inflammatory properties that oppose the development of hypertension and CKD; 20-hydroxyeicosatetraenoic acid levels are elevated after renal ischemia and may protect against injury. Levels of this eicosanoid are also elevated in polycystic kidney disease and may contribute to cyst formation. Our review summarizes the emerging evidence that cytochrome P450 eicosanoids have a role in the pathogenesis of hypertension, polycystic kidney disease, AKI, and CKD.

Transcriptional Profile of Kidney from Type 2 Diabetic db/db Mice

Diabetic nephropathy (DN), a common diabetic microvascular complication, is characterized by progressive glomerular sclerosis and tubulointerstitial fibrosis. However, the underlying mechanisms involved in DN remain to be elucidated. We explored changes in the transcriptional profile in spontaneous type 2 diabetic db/db mice by using the cDNA microarray. Compared with control db/m mice, the db/db mice exhibited marked increases in body weight, kidney weight, and urinary albumin excretion. Renal histological analysis revealed mesangial expansion and thickness of the basement membrane in the kidney of the db/db mice. A total of 355 differentially expressed genes (DEGs) were identified by microarray analysis. Pathway enrichment analysis suggested that biological oxidation, bile acid metabolism, and steroid hormone synthesis were the 3 major significant pathways. The top 10 hub genes were selected from the constructed PPI network of DEGs, including Ccnb2 and Nr1i2, which remained largely unclear in DN. We believe that our study can help elucidate the molecular mechanisms underlying DN.

The Role of Cytochrome P450 Epoxygenases, Soluble Epoxide Hydrolase, and Epoxyeicosatrienoic Acids in Metabolic Diseases

Metabolic diseases are associated with an increased risk of developing cardiovascular disease. The features comprising metabolic diseases include obesity, insulin resistance, hyperglycemia, hyperlipidemia, and hypertension. Recent evidence has emerged showcasing a role for cytochrome P450 epoxygenases, soluble epoxide hydrolase, and epoxyeicosatrienoic acids (EETs) in the development and progression of metabolic diseases. This review discusses the current knowledge related to the modulation of cytochrome P450 epoxygenases and soluble epoxide hydrolase to alter concentrations of biologically active EETs, resulting in effects on insulin resistance, lipid metabolism, obesity, and diabetes. Future areas of research to address current deficiencies in the understanding of these enzymes and their eicosanoid metabolites in various aspects of metabolic diseases are also discussed.

Soluble epoxide hydrolase inhibitor 1-trifluoromethoxyphenyl-3- (1-propionylpiperidin-4-yl) urea attenuates bleomycin-induced pulmonary fibrosis in mice

Epoxyeicosatrienoic acids (EETs), the metabolites of arachidonic acid derived from the cytochrome P450 (CYP450) epoxygenases, are mainly metabolized by soluble epoxide hydrolase (sEH) to their corresponding diols. EETs but not their diols, have anti-inflammatory properties and inhibition of sEH might provide protective effects against inflammatory fibrosis. We test the effects of a selected sEH inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), on bleomycin-induced pulmonary fibrosis (PF) in mice. A mouse model of PF was established by intratracheal injection of bleomycin and TPPU was administered for 21 days after bleomycin injection. We found TPPU treatment improved the body weight loss and survival rate of bleomycin-stimulated mice. Histological examination showed that TPPU treatment alleviated bleomycin-induced inflammation and maintained the alveolar structure of the pulmonary tissues. TPPU also decreased the bleomycin-induced deposition of collagen and the expression of procollagen I mRNA in lung tissues of mice. TPPU decreased the transforming growth factor-β1 (TGF-β1), interleukin-1β (IL-1β) and IL-6 levels in the serum of bleomycin-stimulated mice. Furthermore, TPPU inhibited the proliferation and collagen synthesis of mouse fibroblasts and partially reversed TGF-β1-induced α-smooth muscle actin expression. Our results indicate that the inhibition of sEH attenuates bleomycin-induced inflammation and collagen deposition and therefore prevents bleomycin-induced PF in a mouse model.

CYP2J2 overexpression ameliorates hyperlipidemia via increased fatty acid oxidation mediated by the AMPK pathway

OBJECTIVE

The study aims to investigate the effect of cytochrome P450 2J2 (CYP2J2) overexpression on hyperlipidemia in mice and further to explore its effect on fatty acid oxidation in vivo and in vitro.

METHODS

The effects and mechanisms of endothelial-specific CYP2J2 transgene (Tie2-CYP2J2-Tr) on lipid and fatty acid metabolism were investigated in high-fat diet (HFD) -treated mice. HepG2, LO2 cells, and HUVECs were exposed to 0.4 mM free fatty acid (FFA) for 24 h and used as a model to investigate the roles of CYP2J2 overexpression and epoxyeicosatrienoic acids (EETs) on fatty acid β-oxidation in vitro.

RESULTS

Tie2-CYP2J2-Tr mice had significantly lower plasma and liver triglycerides, lower liver cholesterol and fatty acids, and reduced HFD-induced lipid accumulation. CYP2J2 overexpression resulted in activation of the hepatic and endothelial AMPKα, increased ACC phosphorylation, and increased expression of CPT-1 and PPARα, which were all reduced by HFD treatment. In FFA-treated HepG2, LO2, and HUVECs, both CYP2J2 overexpression and EETs significantly decreased lipid accumulation and increased fatty acid oxidation via activating the AMPK and PPARα pathways.

CONCLUSIONS

Endothelial-specific CYP2J2 overexpression alleviates HFD-induced hyperlipidemia in vivo. CYP2J2 ameliorates FFA-induced dyslipidemia via increased fatty acid oxidation mediated by the AMPK and PPARα pathways.

Impact of soluble epoxide hydrolase inhibition on early kidney damage in hyperglycemic overweight mice

This study addressed the hypothesis that inhibition of the EETs degrading enzyme soluble epoxide hydrolase affords renal protection in the early stage of diabetic nephropathy. The renal effects of the sEH inhibitor t-AUCB (10mg/l in drinking water) were compared to those of the sulfonylurea glibenclamide (80mg/l), both administered for 8 weeks in FVB mice subjected to a high-fat diet (HFD, 60% fat) for 16 weeks. Mice on control chow diet (10% fat) and non-treated HFD mice served as controls. Compared with non-treated HFD mice, HFD mice treated with t-AUCB had a decreased EET degradation, as shown by their higher plasma EETs-to-DHETs ratio, and an increased EET production, as shown by the increase in EETs+DHETs levels, which was associated with induction of CYP450 epoxygenase expression. Both agents similarly reduced fasting glycemia but only t-AUCB prevented the increase in the urinary albumine-to-creatinine ratio in HFD mice. Histopathological analysis showed that t-AUCB reduced renal inflammation, which was associated with an increased mRNA expression of the NFκB inhibitor Iκ≡ and related decrease in MCP-1, COX2 and VCAM-1 expressions. Finally, there was a marginally significant increase in reactive oxygen species production in HFD mice, together with an enhanced NOX2 expression. Both agents did not modify these parameters but t-AUCB increased the expression of the antioxidant enzyme superoxide dismutase 1. These results demonstrate that, independently from its glucose-lowering effect, sEH inhibition prevents microalbuminuria and renal inflammation in overweight hyperglycemic mice, suggesting that this pharmacological strategy could be useful in the management of diabetic nephropathy.

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.

Hyperbaric oxygenation modulates vascular reactivity to angiotensin-(1-7) in diabetic rats: potential role of epoxyeicosatrienoic acids

Previously, a facilitating effect of hyperbaric oxygenation (HBO₂) on aortic ring responses to angiotensin-(1-7) in healthy rats was reported, with epoxyeicosatrienoic acids (EETs) possibly playing an important role. The aim of this study was to assess whether HBO₂ exerts similar effects in diabetic rats and to further explore the role of specific cytochrome P450 (CYP) enzymes in changes induced by HBO₂. Aortic relaxation to angiotensin-(1-7) was significantly higher in HBO₂ diabetic rats compared to control diabetic rats, while HBO₂ had no effect on angiotensin II contraction. N-methylsulphonyl-6-(2-propargyloxyphenyl/hexanamide inhibited the facilitation of angiotensin-(1-7) responses in HBO₂ rats, suggesting an important role of EETs in this modulation. mRNA expression of CYP2J3 and protein expression of CYP2C11 were significantly upregulated in HBO₂ diabetic rats, whereas CYP4A1, CYP4A2 and CYP4A3 mRNA and CYP2J3 protein expression was similar between groups. Mean arterial pressure, ferric reducing ability of plasma and Thiobarbituric Acid Reactive Substances levels and serum angiotensin-(1-7) concentrations were not significantly changed.

Cytochrome P450 eicosanoids in hypertension and renal disease

PURPOSE OF REVIEW

Cytochrome (CYP) P450 metabolites of arachidonic acid, 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) contribute to the regulation of renal tubular and vascular function. This review highlights the results of the recent genetic studies in humans and rodent models, indicating that these eicosanoids participate in the control of blood pressure (BP), chronic kidney disease (CKD), renal ischemia-reperfusion injury (IRI) and polycystic kidney disease (PKD).

RECENT FINDINGS

Endogenous 20-HETE has been reported to play an essential role in the myogenic and tubuloglomerular feedback responses in the afferent arteriole, and a deficiency of 20-HETE contributes to the development of hypertension and renal injury in Dahl S rats. Mutations in CYP4A11 and CYP4F2 have been linked to elevated BP in humans. EETs have been shown to regulate epithelial sodium channel in the collecting duct, lower BP and have renoprotective properties. 20-HETE also opposes the development of CKD and IRI, and may play a role in PKD.

SUMMARY

These studies indicate that CYP P450 metabolites of arachidonic acid play an important role in the control of BP, CKD, AKI and PKD. Drugs targeting these pathways could be useful in the treatment of IRI and CKD.

Transcriptome-based analysis of kidney gene expression changes associated with diabetes in OVE26 mice, in the presence and absence of losartan treatment

Diabetes is among the most common causes of end-stage renal disease, although its pathophysiology is incompletely understood. We performed next-generation sequencing-based transcriptome analysis of renal gene expression changes in the OVE26 murine model of diabetes (age 15 weeks), relative to non-diabetic control, in the presence and absence of short-term (seven-day) treatment with the angiotensin receptor blocker, losartan (n = 3-6 biological replicates per condition). We detected 1438 statistically significant changes in gene expression across conditions. Of the 638 genes dysregulated in diabetes relative to the non-diabetic state, >70% were downregulation events. Unbiased functional annotation of genes up- and down-regulated by diabetes strongly associated (p<1 × 10(-8)) with terms for oxidative stress and for endoplasmic reticulum stress/protein folding. Most of the individual gene products up- or down-regulated with diabetes were unaffected by losartan treatment; however, of the gene products dysregulated in diabetes and influenced by losartan treatment, the vast majority of changes were in the direction of amelioration rather than exacerbation of the diabetic dysregulation. This group of losartan-protected genes associated strongly with annotation terms for endoplasmic reticulum stress, heat shock proteins, and chaperone function, but not oxidative stress; therefore, the losartan-unaffected genes suggest avenues for additional therapeutic opportunity in diabetes. Interestingly, the gene product most highly upregulated by diabetes (>52-fold), encoded by the cationic amino acid transporter Slc7a12, and the gene product most highly downregulated by diabetes (>99%)--encoded by the "pseudogene" Gm6300--are adjacent in the murine genome, are members of the SLC7 gene family, and are likely paralogous. Therefore, diabetes activates a near-total genetic switch between these two paralogs. Other individual-level changes in gene expression are potentially relevant to diabetic pathophysiology, and novel pathways are suggested. Genes unaffected by diabetes alone but exhibiting increased renal expression with losartan produced a signature consistent with malignant potential.

Cytochrome P450 2J2: distribution, function, regulation, genetic polymorphisms and clinical significance

Cytochrome P450 2J2 (CYP2J2) is an enzyme mainly found in human extrahepatic tissues, with predominant expression in the cardiovascular systems and lower levels in the intestine, kidney, lung, pancreas, brain, liver, etc. During the past 15 years, CYP2J2 has attracted much attention for its epoxygenase activity in arachidonic acid (AA) metabolism. It converts AA to four epoxyeicosatrienoic acids (EETs) that have various biological effects, especially in the cardiovascular systems. In recent publications, CYP2J2 is shown highly expressed in various human tumor cells, and its EET metabolites are demonstrated to implicate in the pathologic development of human cancers. CYP2J2 is also a human CYP that involved in phase I xenobiotics metabolism. Antihistamine drugs and many other compounds were identified as the substrates of CYP2J2, and studies have demonstrated that these substrates have a broad structural diversity. CYP2J2 is found not readily induced by known P450 inducers; however, its expression could be regulated in some pathological conditions, might through the activator protein-1(AP-1), the AP-1-like element and microRNA let-7b. Several genetic mutations in the CYP2J2 gene have been identified in humans, and some of them have been shown to have potential associations with some diseases. With the increasing awareness of its roles in cancer disease and drug metabolism, studies about CYP2J2 are still going on, and various inhibitors of CYP2J2 have been determined. Further studies are needed to delineate the roles of CYP2J2 in disease pathology, drug development and clinical practice.

20-HETE and EETs in diabetic nephropathy: a novel mechanistic pathway

Diabetic nephropathy (DN), a major complication of diabetes, is characterized by hypertrophy, extracellular matrix accumulation, fibrosis and proteinuria leading to loss of renal function. Hypertrophy is a major factor inducing proximal tubular epithelial cells injury. However, the mechanisms leading to tubular injury is not well defined. In our study, we show that exposure of rats proximal tubular epithelial cells to high glucose (HG) resulted in increased extracellular matrix accumulation and hypertrophy. HG treatment increased ROS production and was associated with alteration in CYPs 4A and 2C11 expression concomitant with alteration in 20-HETE and EETs formation. HG-induced tubular injury were blocked by HET0016, an inhibitor of CYPs 4A. In contrast, inhibition of EETs promoted the effects of HG on cultured proximal tubular cells. Our results also show that alteration in CYPs 4A and 2C expression and 20HETE and EETs formation regulates the activation of the mTOR/p70S6Kinase pathway, known to play a major role in the development of DN. In conclusion, we show that hyperglycemia in diabetes has a significant effect on the expression of Arachidonic Acid (AA)-metabolizing CYPs, manifested by increased AA metabolism, and might thus alter kidney function through alteration of type and amount of AA metabolites.

CYP2J2 overexpression increases EETs and protects against angiotensin II-induced abdominal aortic aneurysm in mice

Cytochrome P450 epoxygenase 2J2 (CYP2J2) metabolizes arachidonic acids to form epoxyeicosatrienoic acids (EETs), which possess various beneficial effects on the cardiovascular system. However, whether increasing EETs production by CYP2J2 overexpression in vivo could prevent abdominal aortic aneurysm (AAA) remains unknown. Here we investigated the effects of recombinant adeno-associated virus (rAAV)-mediated CYP2J2 overexpression on angiotensin (Ang) II-induced AAA in apoE-deficient mice. rAAV-CYP2J2 delivery led to an abundant aortic CYP2J2 expression and increased EETs generation. It was shown that CYP2J2 overexpression attenuated matrix metalloproteinase expression and activity, elastin degradation, and AAA formation, which was associated with reduced aortic inflammation and macrophage infiltration. In cultured vascular smooth muscle cells (VSMCs), rAAV-mediated CYP2J2 overexpression and EETs markedly suppressed Ang II-induced inflammatory cytokine expression. Moreover, overexpressed CYP2J2 and EETs inhibited Ang II-induced macrophage migration in a VSMC-macrophage coculture system. We further indicated that these protective effects were mediated by peroxisome proliferator-activated receptor (PPAR)γ activation. Taken together, these results provide evidence that rAAV-mediated CYP2J2 overexpression prevents AAA development which is likely via PPARγ activation and anti-inflammatory action, suggesting that increasing EETs levels could be considered as a potential strategy to prevent and treat AAA.

Eicosanoids in metabolic syndrome

Chronic persistent inflammation plays a significant role in disease pathology of cancer, cardiovascular disease, and metabolic syndrome (MetS). MetS is a constellation of diseases that include obesity, diabetes, hypertension, dyslipidemia, hypertriglyceridemia, and hypercholesterolemia. Nonalcoholic fatty liver disease (NAFLD) is associated with many of the MetS diseases. These metabolic derangements trigger a persistent inflammatory cascade, which includes production of lipid autacoids (eicosanoids) that recruit immune cells to the site of injury and subsequent expression of cytokines and chemokines that amplify the inflammatory response. In acute inflammation, the transcellular synthesis of antiinflammatory eicosanoids resolve inflammation, while persistent activation of the autacoid-cytokine-chemokine cascade in metabolic disease leads to chronic inflammation and accompanying tissue pathology. Many drugs targeting the eicosanoid pathways have been shown to be effective in the treatment of MetS, suggesting a common linkage between inflammation, MetS and drug metabolism. The cross-talk between inflammation and MetS seems apparent because of the growing evidence linking immune cell activation and metabolic disorders such as insulin resistance, dyslipidemia, and hypertriglyceridemia. Thus modulation of lipid metabolism through either dietary adjustment or selective drugs may become a new paradigm in the treatment of metabolic disorders. This review focuses on the mechanisms linking eicosanoid metabolism to persistent inflammation and altered lipid and carbohydrate metabolism in MetS.

11,12-Epoxyeicosatrienoic acid inhibits free fatty acid-induced apoptosis of pancreatic β-cells through targeting nuclear ATF4 and ATF6

AIM: To investigate the effect of 11,12-epoxyeicosatrienoic acid (EET) on free fatty acid-induced cell apoptosis and translocation of activating transcription factor 4 (ATF4) and activating transcription factor 6 (ATF6) in primarily cultured murine pancreatic β-cells.

METHODS: Primary pancreatic β-cells were isolated from murine pancreas islets and cultured. After treatment with palmitic acid (400 μmol/L), pancreatic β-cells were incubated with 11,12-EET (100 nmol/L) for 24 h. Viability of primary pancreatic β-cells was examined by WST-1 colorimetric assay. Changes in mitochondrial membrane potential were evaluated to observe depolarization of cellular mitochondria by flow cytometry. Western blot was used to determine the protein expression of cytoplasmic and nuclear ATF4 and ATF6 to observe their translocation.

RESULTS: After treatment with palmitic acid and 11,12-EET for 24 h, viability of primary pancreatic β-cells was significantly increased (62.1% ± 7.3% vs 53.0% ± 6.1%, P < 0.05), and mitochondrial depolarization (23.6% ± 3.4% vs 35.2% ± 4.7%, P < 0.05) and apoptosis rate (24.5% ± 4.2% vs 40.1% ± 5.6%, P < 0.05) were markedly decreased compared to cells treated with palmitic acid alone. Palmitic acid significantly increased cytoplasmic but decreased nuclear protein levels of ATF4 and ATF6 in pancreatic β-cells.

CONCLUSION: 11,12-EET significantly inhibits FFA-induced apoptosis of pancreatic β-cells by inhibiting the translocation of ATF4 and ATF6.

Impact of genetic polymorphisms on tacrolimus pharmacokinetics and the clinical outcome of renal transplantation

We retrospectively examined the association of polymorphisms in the CYP3A, CYP2J2, CYP2C8, and ABCB1 genes with pharmacokinetic (PKs) and pharmacodynamic (PDs) parameters of tacrolimus in 103 renal transplant recipients for a period of 1 year. CYP3A5 expressers had lower predose concentrations (C(0) )/dose and higher dose requirements than nonexpressers throughout the study. Among CYP3A5*1 carriers, those also carrying the CYP3A4*1B allele showed the lowest C(0) /dose, as compared with CYP3A4*1/CYP3A5*3 carriers (54.28±26.45, 59.12±24.00, 62.43±41.12, and 57.01±17.34 vs. 112.37± 76.60, 123.21±59.57, 163.34±76.23, and 183.07±107.82 at 1 week, 1 month, 5 months, and 1 year after transplantation). In addition, CYP3A4*1B/CYP3A5*1 carriers showed significantly lower dose-corrected exposure than CYP3A4*1/CYP3A5*1 carriers 1 year after transplantation (57.01±17.34 vs. 100.09±24.78; P=0.016). Only the ABCB1 TGC (3435-2677-1236) haplotype showed a consistent association with PDs (nephrotoxicity; OR=4.73; CI: 1.3-16.7; P=0.02). Our findings indicate that the CYP3A4*1B-CYP3A5*1 haplotype may have a more profound impact in tacrolimus PKs than the CYP3A5*1 allele. This study does not support a critical role of the CYP450 or ABCB1 single nucleotide polymorphisms in the occurrence of toxicity or acute rejection in renal transplant recipients treated with tacrolimus.