Differential Effects of sEH Inhibitors on the Proliferation and Migration of Vascular Smooth Muscle Cells

Restoration of ARA metabolic disorders in vascular smooth muscle cells alleviates intimal hyperplasia

Intimal hyperplasia (IH) is an innegligible issue for patients undergoing interventional therapy. The proliferation and migration of vascular smooth muscle cells (VSMCs) induced by platelet-derived growth factor-BB (PDGF-BB) are critical events in the development of IH. While the exact mechanism and effective target for IH needs further investigation. Metabolic disorders of arachidonic acid (ARA) are involved in the occurrence and progression of various diseases. In this study, we found that the expressions of soluble epoxide hydrolase (sEH) and cyclooxygenase-2 (COX-2) were significantly increased in the VSMCs during balloon injury-induced IH. Then, we employed a COX-2/sEH dual inhibitor PTUPB to increase the concentration of epoxyeicosatrienoic acids (EETs) while prevent the release of pro-inflammatory prostaglandins. Results showed that PTUPB treatment significantly reduced neointimal thickening induced by balloon injury in rats in vivo and inhibited PDGF-BB-induced proliferation and migration of VSMCs in vitro. Our results showed that PTUPB may reverse the phenotypic transition of VSMCs by inhibiting Pttg1 expression. In conclusion, we found that the dysfunction of ARA metabolism in VSMCs contributes to IH, and the COX-2/sEH dual inhibitor PTUPB attenuates IH progression by reversing the phenotypic switch in VSMC through the Sirt1/Pttg1 pathway.

COX-2/sEH Dual Inhibitor PTUPB Attenuates Epithelial-Mesenchymal Transformation of Alveolar Epithelial Cells via Nrf2-Mediated Inhibition of TGF-β1/Smad Signaling

Background

Arachidonic acid (ARA) metabolites are involved in the pathogenesis of epithelial-mesenchymal transformation (EMT). However, the role of ARA metabolism in the progression of EMT during pulmonary fibrosis (PF) has not been fully elucidated. The purpose of this study was to investigate the role of cytochrome P450 oxidase (CYP)/soluble epoxide hydrolase (sEH) and cyclooxygenase-2 (COX-2) metabolic disorders of ARA in EMT during PF.

Methods

A signal intratracheal injection of bleomycin (BLM) was given to induce PF in C57BL/6 J mice. A COX-2/sEH dual inhibitor PTUPB was used to establish the function of CYPs/COX-2 dysregulation to EMT in PF mice. In vitro experiments, murine alveolar epithelial cells (MLE12) and human alveolar epithelial cells (A549) were used to explore the roles and mechanisms of PTUPB on transforming growth factor (TGF)-β1-induced EMT.

Results

PTUPB treatment reversed the increase of mesenchymal marker molecule α-smooth muscle actin (α-SMA) and the loss of epithelial marker molecule E-cadherin in lung tissue of PF mice. In vitro, COX-2 and sEH protein levels were increased in TGF-β1-treated alveolar epithelial cells (AECs). PTUPB decreased the expression of α-SMA and restored the expression of E-cadherin in TGF-β1-treated AECs, accompanied by reduced migration and collagen synthesis. Moreover, PTUPB attenuated TGF-β1-Smad2/3 pathway activation in AECs via Nrf2 antioxidant cascade.

Conclusion

PTUPB inhibits EMT in AECs via Nrf2-mediated inhibition of the TGF-β1-Smad2/3 pathway, which holds great promise for the clinical treatment of PF.

Multitarget molecule, PTUPB, to treat diabetic nephropathy in rats

BACKGROUND AND PURPOSE

Diabetic nephropathy is a common complications related to high morbidity and mortality in type 2 diabetes. We investigated the action of the dual modulator, PTUPB, a soluble epoxide hydrolase and cyclooxygenase-2 inhibitor against diabetic nephropathy.

EXPERIMENTAL APPROACH

Sixteen-week-old type 2 diabetic and proteinuric obese ZSF1 rats were treated with vehicle, PTUPB or enalapril for 8 weeks. Measurements were made of epoxyeicosatrienoic acids, thromboxane B2 (TBX2 ) and prostaglandin E2 (PGE2 ) in the kidney of these and lean ZSF1 rats along with their blood pressure.

KEY RESULT

Obese ZSF1 rats were diabetic with fivefold higher fasting blood glucose levels and markedly higher HbA1c levels compared with lean ZSF1 rats. PTUPB nor enalapril reduced fasting blood glucose or HbA1c but alleviated the development of diabetic nephropathy. In PTUPB-treated obese ZSF1 rats, glomerular nephrin expression was preserved. Enalapril also alleviated diabetic nephropathy. Diabetic renal injury in obese ZSF1 rats was accompanied by renal inflammation with six to sevenfold higher urinary MCP-1 (CCR2) level and renal infiltration of CD-68 positive cells. PTUPB and enalapril significantly reduced urinary MCP-1 levels and renal mRNA expression of cytokines. Both PTUPB and enalapril lowered blood pressure. PTUPB but not enalapril decreased hyperlipidaemia and liver injury in obese ZSF1 rats.

CONCLUSION AND IMPLICATIONS

Overall, the dual modulator PTUPB does not treat hyperglycaemia but can effectively alleviate hypertension, diabetic nephropathy, hyperlipidaemia and liver injury in type 2 diabetic rats. Our data further demonstrate that the renal actions of PTUPB are comparable with a current standard diabetic nephropathy treatment.

Deletion of soluble epoxide hydrolase suppressed chronic kidney disease-related vascular calcification by restoring Sirtuin 3 expression

Vascular calcification is common in chronic kidney disease (CKD) and contributes to cardiovascular disease (CVD) without any effective therapies available up to date. The expression of soluble epoxide hydrolase (sEH) is different in patients with and without vascular calcification. The present study investigates the role of sEH as a potential mediator of vascular calcification in CKD. Both Ephx2^−/− and wild-type (WT) mice fed with high adenine and phosphate (AP) diet were used to explore the vascular calcification in CKD. Compared with WT, deletion of sEH inhibited vascular calcification induced by AP. sEH deletion also abolished high phosphorus (Pi)-induced phenotypic transition of vascular smooth muscle cells (VSMCs) independent of its epoxyeicosatrienoic acids (EETs) hydrolysis. Further gene expression analysis identified the potential role of Sirtuin 3 (Sirt3) in the sEH-regulated VSMC calcification. Under high Pi treatment, sEH interacted with Sirt3, which might destabilize Sirt3 and accelerate the degradation of Sirt3. Deletion of sEH may preserve the expression of Sirt3, and thus maintain the mitochondrial adenosine triphosphate (ATP) synthesis and morphology, significantly suppressing VSMC calcification. Our data supported that sEH deletion inhibited vascular calcification and indicated a promising target of sEH inhibition in vascular calcification prevention.

A COX-2/sEH dual inhibitor PTUPB alleviates lipopolysaccharide-induced acute lung injury in mice by inhibiting NLRP3 inflammasome activation

Rationale: Dysregulation of arachidonic acid (ARA) metabolism results in inflammation; however, its role in acute lung injury (ALI) remains elusive. In this study, we addressed the role of dysregulated ARA metabolism in cytochromes P450 (CYPs) /cyclooxygenase-2 (COX-2) pathways in the pathogenesis of lipopolysaccharide (LPS)-induced ALI in mice. Methods: The metabolism of CYPs/COX-2-derived ARA in the lungs of LPS-induced ALI was investigated in C57BL/6 mice. The COX-2/sEH dual inhibitor PTUPB was used to establish the function of CYPs/COX-2 dysregulation in ALI. Primary murine macrophages were used to evaluate the underlying mechanism of PTUPB involved in the activation of NLRP3 inflammasome in vitro. Results: Dysregulation of CYPs/COX-2 metabolism of ARA occurred in the lungs and in primary macrophages under the LPS challenge. Decrease mRNA expression of Cyp2j9, Cyp2j6, and Cyp2j5 was observed, which metabolize ARA into epoxyeicosatrienoic acids (EETs). The expressions of COX-2 and soluble epoxide hydrolase (sEH), on the other hand, was significantly upregulated. Pre-treatment with the dual COX-2 and sEH inhibitor, PTUPB, attenuated the pathological injury of lung tissues and reduced the infiltration of inflammatory cells. Furthermore, PTUPB decreased the pro-inflammatory factors, oxidative stress, and activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in LPS-induced ALI mice. PTUPB pre-treatment remarkably reduced the activation of macrophages and NLRP3 inflammasome in vitro. Significantly, both preventive and therapeutic treatment with PTUPB improved the survival rate of mice receiving a lethal dose of LPS. Conclusion: The dysregulation of CYPs/COX-2 metabolized ARA contributes to the uncontrolled inflammatory response in ALI. The dual COX-2 and sEH inhibitor PTUPB exerts anti-inflammatory effects in treating ALI by inhibiting the NLRP3 inflammasome activation.

Soluble epoxide hydrolase inhibitor protects against blood-brain barrier dysfunction in a mouse model of type 2 diabetes via the AMPK/HO-1 pathway

Diabetes mellitus is a metabolic disorder that can lead to blood-brain barrier (BBB) disruption and cognitive decline. However, the mechanisms of BBB breakdown in diabetes are still unclear. Soluble epoxide hydrolase (sEH) is an enzyme that degrades epoxyeicosatrienoic acids (EETs), which have multiple protective effects on vascular structure and functions. In the current study, we showed increased vascular permeability of the BBB, which was accompanied by upregulation of sEH and downregulation of 14,15-EET. Moreover, the sEH inhibitor t-AUCB restored diabetic BBB integrity in vivo, and 14,15-EET prevented ROS accumulation and MEC injury in vitro. t-AUCB or 14,15-EET treatment provoked AMPK/HO-1 activation under diabetic conditions in vivo and in vitro. Thus, we suggest that decreased EET degradation by sEH inhibition might be a potential therapeutic approach to attenuate the progression of BBB injury in diabetic mice via AMPK/HO-1 pathway activation.

Vascular Protection of TPE-CA on Hyperhomocysteinemia-induced Vascular Endothelial Dysfunction through AA Metabolism Modulated CYPs Pathway

A high concentration of homocysteine (Hcy) in plasma induces vascular endothelial dysfunction, and it may ultimately accelerate the development of cardiovascular diseases (CVDs). Although several B vitamins have been clinically applied for hyperhomocysteinemia (HHcy) treatment, the outcomes are not satisfied due to their limited therapeutic mechanism. Hence, in order to improve the curative effect, development of new effective therapeutic strategies should be put on the agenda. Total phenolic extracts of Citrus aurantium L. (TPE-CA) is a naturally obtained phenolic mixture, mainly containing flavones, flavanones and their glycosyl derivatives, flavonols, polymethoxyflavones and coumarins. Previous reports indicated that bioactive phenolic compounds possessed potent vascular protective effects and regarded as a protective agent against CVDs. Intriguingly, the exact mechanism underlying the suppressed effects of TPE-CA on HHcy could assist in revealing their therapy on CVDs. Here, the multi-targeted synergistic mechanism of TPE-CA on HHcy-induced vascular endothelial dysfunction was uncovered in a deduced manner. TPE-CA treatment exhibited an obvious superiority than that of B vitamins treatment. Network pharmacology was employed to identify the interrelationships among compounds, potential targets and putative pathways. Further experimental validation suggested that the treatment of TPE-CA for HHcy could not only effectively reduce the Hcy level in plasma through up-regulating transsulfuration pathway in Hcy metabolism, but also restore the HHcy-induced vascular endothelial dysfunction by activating cytochrome P450 enzymes (CYPs) epoxygenase signal cascades and inhibiting CYPs hydroxylase signal cascades in arachidonic acid (AA) metabolism.

Angiogenesis and vascular stability in eicosanoids and cancer

Angiogenesis and inflammation are hallmarks of cancer. Arachidonic acid and other polyunsaturated fatty acids (PUFAs) are primarily metabolized by three distinct enzymatic systems initiated by cyclooxygenases, lipoxygenases, and cytochrome P450 enzymes (CYP) to generate bioactive eicosanoids, including prostanoids, leukotrienes, hydroxyeicosatetraenoic acids, and epoxyeicosatrienoic acids. As some of the PUFA metabolites playing essential roles in inflammatory processes, these pathways have been widely studied as therapeutic targets of inflammation. Because of their anti-inflammatory effects, these pathways were also proposed as anti-cancer targets. However, although the eicosanoids were linked to endothelial cell proliferation and angiogenesis almost two decades ago, it is only recently PUFA metabolites, especially those generated by CYP enzymes and the soluble epoxide hydrolase (sEH), have been recognized as important signaling mediators in physiological and pathological angiogenesis. Despite the fact that tumor growth and invasion are heavily dependent on inner-tumor angiogenesis and influenced by vascular stability, the role played by PUFA metabolites in tumor angiogenesis and vessel integrity has been largely overlooked. This review highlights current knowledge on the function of PUFA metabolites generated by the CYP/sEH pathway in angiogenesis and vascular stability as well as their potential involvement in cancer development.

Soluble epoxide hydrolase inhibition enhances anti-inflammatory and antioxidative processes, modulates microglia polarization, and promotes recovery after ischemic stroke

BACKGROUND

Ischemic stroke triggers inflammatory responses and oxidative stress in the brain, and microglia polarization affects the degree of neuroinflammation. It has been reported that the inhibition of soluble epoxide hydrolase (sEH) activity protects brain tissue. However, the anti-inflammatory and antioxidative effects of sEH inhibition in the ischemic brain are not fully understood. This study aimed to investigate the effects of a selective sEH inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), after ischemic stroke.

METHODS

Adult male rats with middle cerebral artery occlusion (MCAO) were administered with AUDA or a vehicle. Behavioral outcome, infarct volume, microglia polarization, and gene expression were assessed.

RESULTS

Rats treated with AUDA showed better behavioral outcomes and smaller infarct volumes after MCAO. After AUDA treatment, a reduction of M1 microglia and an increase of M2 microglia occurred at the ischemic cortex of rats. Additionally, there was an increase in the mRNA expressions of antioxidant enzymes and anti-inflammatory interleukin-10, and pro-inflammatory mediators were decreased after AUDA administration. Heme oxygenase-1 was mainly expressed by neurons, and AUDA was found to improve the survival of neurons.

CONCLUSION

The results of this study provided novel and significant insights into how AUDA can improve outcomes and modulate inflammation and oxidative stress after ischemic stroke.

Prospective for cytochrome P450 epoxygenase cardiovascular and renal therapeutics

Therapeutics for arachidonic acid pathways began with the development of non-steroidal anti-inflammatory drugs that inhibit cyclooxygenase (COX). The enzymatic pathways and arachidonic acid metabolites and respective receptors have been successfully targeted and therapeutics developed for pain, inflammation, pulmonary and cardiovascular diseases. These drugs target the COX and lipoxygenase pathways but not the third branch for arachidonic acid metabolism, the cytochrome P450 (CYP) pathway. Small molecule compounds targeting enzymes and CYP epoxy-fatty acid metabolites have evolved rapidly over the last two decades. These therapeutics have primarily focused on inhibiting soluble epoxide hydrolase (sEH) or agonist mimetics for epoxyeicosatrienoic acids (EET). Based on preclinical animal model studies and human studies, major therapeutic indications for these sEH inhibitors and EET mimics/analogs are renal and cardiovascular diseases. Novel small molecules that inhibit sEH have advanced to human clinical trials and demonstrate promise for cardiovascular diseases. Challenges remain for sEH inhibitor and EET analog drug development; however, there is a high likelihood that a drug that acts on this third branch of arachidonic acid metabolism will be utilized to treat a cardiovascular or kidney disease in the next decade.