Salt-sensitive hypertension after reversal of unilateral ureteral obstruction.

The incidence of ureter obstruction is increasing and patients recovering from this kidney injury often progress to chronic kidney injury. There is evidence that a long-term consequence of recovery from ureter obstruction is an increased risk for salt-sensitive hypertension. A reversal unilateral ureteral obstruction (RUUO) model was used to study long-term kidney injury and salt-sensitive hypertension. In this model, we removed the ureteral obstruction at day 10 in mice. Mice were divided into four groups: (1) normal salt diet, (2) high salt diet, (3) RUUO normal salt diet, and (4) RUUO high salt diet. At day 10, the mice were fed a normal or high salt diet for 4 weeks. Blood pressure was measured, and urine and kidney tissue collected. There was a progressive increase in blood pressure in the RUUO high salt diet group. RUUO high salt group had decreased sodium excretion and glomerular injury. Renal epithelial cell injury was evident in RUUO normal and high salt mice as assessed by neutrophil gelatinase-associated lipocalin (NGAL). Kidney inflammation in the RUUO high salt group involved an increase in F4/80 positive macrophages; however, CD3+ positive T cells were not changed. Importantly, RUUO normal and high salt mice had decreased vascular density. RUUO was also associated with renal fibrosis that was further elevated in RUUO mice fed a high salt diet. Overall, these findings demonstrate long-term renal tubular injury, inflammation, decreased vascular density, and renal fibrosis following reversal of unilateral ureter obstruction that could contribute to impaired sodium excretion and salt-sensitive hypertension.

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.

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.

A SORAFENIB INDUCED MODEL OF GLOMERULAR KIDNEY DISEASE.

Glomerular injury and proteinuria are important pathophysiological features of chronic kidney disease. In the present study, we provide data on a glomerular injury model that was developed using the cancer chemotherapy drug sorafenib. Sorafenib is a tyrosine kinase inhibitor that acts via the vascular endothelial growth factor (VEGF) signaling pathway and is widely used to treat a variety of cancers. On the other hand, sorafenib causes serious renal side effects in patients including the development of chronic kidney disease. The current study aimed to utilize the nephrotoxic property of sorafenib to develop a rat model for chronic kidney disease. We demonstrate that rats administered sorafenib for 8 weeks along with a high salt diet (8% NaCl enriched) develop hypertension (80mmHg higher systolic blood pressure), proteinuria (75% higher), and 4-fold higher glomerular injury compared to vehicle-treated normal control rat. Sorafenib induced glomerular injury was associated with decreased (20-80% lower) renal mRNA expression of key glomerular structural proteins such as nephrin, podocin, synaptopodin, and podoplanin compared to vehicle-treated normal control rat. Renal cortical endothelial-to-mesenchymal transition (EndoMT) was activated in the sorafenib induced glomerular injury model. In the sorafenib treated rats, the renal EndoMT was evident with 20% lower mRNA expression of an endothelial marker WT-1 and 2 to 3-fold higher expression of mesenchymal markers Col III, FSP-1, α-SMA, and vimentin. In conclusion, we developed a rat pre-clinical chronic kidney disease model that manifest glomerular injury. We further demonstrate that the glomerular injury in this model is associated with decreased renal mRNA expression of key glomerular structural proteins and an activated kidney EndoMT.

Dual soluble epoxide hydrolase inhibitor/PPAR-γ agonist attenuates renal fibrosis.

Renal fibrosis is a contributor to chronic kidney disease and an important predictor of long-term prognosis. We developed a dual soluble epoxide hydrolase inhibitor-PPAR-γ agonist (sEHi/PPAR-γ), RB394, and investigated its ability to attenuate renal fibrosis in a mouse unilateral ureteral obstruction (UUO) model. RB394 efficacy was compared to an sEH inhibitor (sEHi), a PPAR-γ agonist rosiglitazone (Rosi), or their combination (sEHi + Rosi). All interventional treatments were administrated in drinking water 3 days after UUO induction surgery and continued for 7 days. UUO mice developed renal fibrosis with higher collagen formation and RB394 significantly attenuated fibrosis (P < 0.05). Renal expression of α-smooth muscle actin (α-SMA) was elevated in UUO mice and all treatments except sEHi significantly attenuated renal α-SMA expression. Renal mRNA expression fibrotic and fibrosis regulators were higher in UUO mice and RB394 and sEHi + Rosi treatments attenuated their expression. Renal inflammation was evident in UUO mice with increased infiltration of CD45 and F4/80 positive cells. RB394 and sEHi + Rosi treatments attenuated renal inflammation in UUO mice. UUO mice had renal tubular and vascular injury. Renal tubular and vascular injuries were attenuated to a greater extent by RB394 and sEHi + Rosi than sEHi or Rosi treatment alone. Renal mRNA expression of oxidative stress markers were significantly higher in UUO mice (P < 0.05). RB394 and sEHi + Rosi attenuated expression of oxidative stress markers to a greater extent than other interventional treatments (P < 0.05). These findings demonstrate that RB394 can attenuate renal fibrosis by reducing renal inflammation, oxidative stress, tubular injury, and vascular injury. In conclusion, RB394 demonstrates exciting potential as a therapeutic for renal fibrosis and chronic kidney disease.

Epoxy Fatty Acids: From Salt Regulation to Kidney and Cardiovascular Therapeutics: 2019 Lewis K. Dahl Memorial Lecture.

Epoxyeicosatrienoic acids (EETs) are epoxy fatty acids that have biological actions that are essential for maintaining water and electrolyte homeostasis. An inability to increase EETs in response to a high-salt diet results in salt-sensitive hypertension. Vasodilation, inhibition of epithelial sodium channel, and inhibition of inflammation are the major EET actions that are beneficial to the heart, resistance arteries, and kidneys. Genetic and pharmacological means to elevate EETs demonstrated antihypertensive, anti-inflammatory, and organ protective actions. Therapeutic approaches to increase EETs were then developed for cardiovascular diseases. sEH (soluble epoxide hydrolase) inhibitors were developed and progressed to clinical trials for hypertension, diabetes mellitus, and other diseases. EET analogs were another therapeutic approach taken and these drugs are entering the early phases of clinical development. Even with the promise for these therapeutic approaches, there are still several challenges, unexplored areas, and opportunities for epoxy fatty acids.

THE EFFECT OF COMPOUND DM509 ON KIDNEY FIBROSIS IN THE CONDITIONS OF THE EXPERIMENTAL MODEL.

Renal fibrosis is a critical event in the progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD). Unfortunately, there are few options to target renal fibrosis in order to develop novel anti-fibrotic agents that could prevent CKD progression to ESRD. We evaluated the efficacy of a novel dual-acting molecule, DM509, in preventing renal fibrosis using the unilateral ureteral obstruction (UUO) renal fibrosis mouse model. DM509 acts simultaneously as a farnesoid X receptor agonist (FXRA) and a soluble epoxide hydrolase inhibitor (sEHi). In this study, groups of 8-12 weeks old C57BL/6J male mice went through either UUO or sham surgery (n=6/group). Mice were pre-treated with DM509 (10mg/kg/d) or vehicle administered in drinking water one day prior to the UUO surgery. Sham, vehicle and DM509 treatments continued until day 10 and blood and kidney tissue were collected for biochemical, histological, and gene expression analysis at the end of the treatment protocol. The UUO group exhibited kidney dysfunction with elevated blood urea nitrogen (BUN) compared to the sham group (63±7 vs. 34±6 mg/dL). DM509 treatment prevented renal dysfunction as evident from 36% lower BUN level in the DM509 treated UUO mice compared to UUO mice treated with vehicle. Vehicle treated UUO mice demonstrated renal fibrosis with elevated kidney hydroxyproline content (213±11 vs. 49±9 µg/mg protein) and kidney collagen positive area (13±2% vs. 1.1±0.1%) compared to the sham group. We found that DM509 treatment prevented renal fibrosis and DM509 treated mice had 34-66% lower levels of kidney hydroxyproline and collagen positive renal area compared to vehicle-treated UUO mice. In conclusion, our data provide evidence that the novel dual-acting FXRA and a sEHi, DM509, prevented renal dysfunction and renal fibrosis in UUO mouse model.