Multitarget molecule, PTUPB, to treat diabetic nephropathy in rats

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

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

Corn silk polysaccharides attenuate diabetic nephropathy through restoration of the gut microbial ecosystem and metabolic homeostasis

Introduction

The pathogenesis of diabetic nephropathy (DN) is complex, inflammation is the central link among the inducing factors in the existing research, and the gutkidney axis could scientifically explain the reasons for the accumulation of chronic low-grade inflammation. As both a medicine and food, corn silk contains abundant polysaccharides. Historical studies and modern research have both confirmed its intervention effect on diabetes and DN, but the mechanism of action is unclear.

Methods

In this study, a DN rat model was generated, and the therapeutic effect of corn silk polysaccharides (CSPs) was evaluated based on behavioral, histopathological and biochemical indicators. We attempted to fully understand the interactions between CSPs, the gut microbiota and the host at the systemic level from a gut microbiota metabolomics perspective to fundamentally elucidate the mechanisms of action that can be used to intervene in DN.

Results

Research has found that the metabolic pathways with a strong correlation with CSPs were initially identified as glycerophosphate, fatty acid, bile acid, tyrosine, tryptophan and phenylalanine metabolism and involved Firmicutes, Bacteroides, Lachnospiraceae-NK4A136- group and Dubosiella, suggesting that the effect of CSPs on improving DN is related to changes in metabolite profiles and gut microbiota characteristics.

Discussion

CSPs could be harnessed to treat the abnormal metabolism of endogenous substances such as bile acids and uremic toxins caused by changes in gut microbiota, thus alleviating kidney damage caused by inflammation. In view of its natural abundance, corn silk is safe and nontoxic and can be used for the prevention and treatment of diabetes and DN.

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.

Dual sEH/COX-2 Inhibition Using PTUPB-A Promising Approach to Antiangiogenesis-Induced Nephrotoxicity

Kidney injury from antiangiogenic chemotherapy is a significant clinical challenge, and we currently lack the ability to effectively treat it with pharmacological agents. Thus, we set out to investigate whether simultaneous soluble epoxide hydrolase (sEH) and cyclooxygenase-2 (COX-2) inhibition using a dual sEH/COX-2 inhibitor PTUPB could be an effective strategy for treating antiangiogenic therapy-induced kidney damage. We used a multikinase inhibitor, sorafenib, which is known to cause serious renal side effects. The drug was administered to male Sprague-Dawley rats that were on a high-salt diet. Sorafenib was administered over the course of 56 days. The study included three experimental groups; 1) control group (naïve rats), 2) sorafenib group [rats treated with sorafenib only (20 mg/kg/day p.o.)], and 3) sorafenib + PTUPB group (rats treated with sorafenib only for the initial 28 days and subsequently coadministered PTUPB (10 mg/kg/day i.p.) from days 28 through 56). Blood pressure was measured every 2 weeks. After 28 days, sorafenib-treated rats developed hypertension (161 ± 4 mmHg). Over the remainder of the study, sorafenib treatment resulted in a further elevation in blood pressure through day 56 (200 ± 7 mmHg). PTUPB treatment attenuated the sorafenib-induced blood pressure elevation and by day 56, blood pressure was 159 ± 4 mmHg. Urine was collected every 2 weeks for biochemical analysis. After 28 days, sorafenib rats developed pronounced proteinuria (9.7 ± 0.2 P/C), which intensified significantly (35.8 ± 3.5 P/C) by the end of day 56 compared with control (2.6 ± 0.4 P/C). PTUPB mitigated sorafenib-induced proteinuria, and by day 56, it reduced proteinuria by 73%. Plasma and kidney tissues were collected on day 56. Kidney histopathology revealed intratubular cast formation, interstitial fibrosis, glomerular injury, and glomerular nephrin loss at day 56 in sorafenib-treated rats. PTUPB treatment reduced histological features by 30%-70% compared with the sorafenib-treated group and restored glomerular nephrin levels. Furthermore, PTUPB also acted on the glomerular permeability barrier by decreasing angiotensin-II-induced glomerular permeability to albumin. Finally, PTUPB improved in vitro the viability of human mesangial cells. Collectively, our data demonstrate the potential of using PTUPB or dual sEH/COX-2 inhibition as a therapeutic strategy against sorafenib-induced glomerular nephrotoxicity.