Prolyl hydroxylase inhibitor desidustat protects against acute and chronic kidney injury by reducing inflammatory cytokines and oxidative stress

G protein-coupled estrogen receptor selective agonist, G1, improves the molecular and biochemical markers in a cisplatin mouse model of CKD

Multiple cycles of cisplatin result in a permanent loss of kidney function with severe and life-limited chronic kidney disease (CKD) after successful cisplatin therapy. Recently, studies have showed that the activation of G-protein coupled estrogen receptor (GPER) could protect against kidney disease. This study aimed to test the potential of the G1 compound, a GPER selective agonist, to prevent CKD development after cisplatin therapy. Male C57BL/6 mice were exposed to 2 cycles of 2.5 mg/kg cisplatin in a regimen miming clinical exposure (1 injection daily for 5 days, followed by a 16-day recovery period between cycles). G1 (50 or 100 μg/kg) was administered daily for 6 weeks. G1 dose-dependently improved kidney function biomarkers (serum creatinine, creatinine clearance, and protein excretion) and histopathological changes compared to the cisplatin-treated group. Collagen 3 expression was dose-dependently decreased in G1-treated groups that was parallel to the reduction of fibrosis in Masson's trichrome-stained sections. G1 administration also increased total antioxidant capacity (TAC) and nuclear factor erythroid 2-related factor 2 (Nrf2) and reduced the level of malondialdehyde and the proinflammatory cytokine, tumor necrosis factor-α. In addition, G1 downregulated the expression of inflammasome NLRP3 and nuclear factor kappa B p65 (NF-κB p65) in a dose-dependent manner. In conclusion, these data suggest that G1 could be a new therapeutic tool for CKD prevention post cisplatin therapy. These effects might be mediated through the activation of Nrf2 and the inhibition of NF-κB/NLRP3 signaling.

HIF-PHD inhibitor desidustat ameliorates iron deficiency anemia

Iron deficiency anemia is caused by many pathological conditions like chronic kidney disease (CKD), inflammation, malnutrition and gastrointestinal abnormality. Current treatments that are erythropoiesis stimulating agents (ESAs) and iron supplementation are inadequate and often lead to tolerance and/or toxicity. Desidustat, a prolyl hydroxylase (PHD) inhibitor, is clinically used for the treatment of anemia with CKD. In this study, we investigated the effect of desidustat on iron deficiency anemia (IDA). IDA was induced in C57BL6/J mice by iron deficient diet feeding. These mice were then treated with desidustat (15 mg/kg, PO) and FeSO4 (20 mg/kg) for five weeks and effect of the treatment on hematology, iron homeostasis, and bone marrow histology was observed. Effect of desidustat on iron metabolism in inflammation (LPS)-induced iron deficiency was also assessed. Both, Desidustat and FeSO4, increased MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), hemoglobin, and HCT (hematocrit) in blood and increased iron in serum, liver, and spleen. Desidustat increased MCHC (mean corpuscular hemoglobin concentration) while FeSO4 treatment did not alter it. FeSO4 treatment significantly increased iron deposition in liver, and spleen, while desidustat increased iron in circulation and demonstrated efficient iron utilization. Desidustat increased iron absorption, serum iron and decreased hepcidin without altering tissue iron, while FeSO4 increased serum and tissue iron by increasing hepcidin in LPS-induced iron deficiency. Desidustat increased erythroid population, especially iron-dependent polychromatic normoblasts and orthochromatic normoblasts, while FeSO4 did not improve cell architecture. PHD inhibition by desidustat improved iron utilization in iron deficiency anemia, by efficient erythropoiesis.

Tubular Endogenous Erythropoietin Protects Renal Function against Ischemic Reperfusion Injury

Many large-scale studies show that exogenous erythropoietin, erythropoiesis-stimulating agents, lack any renoprotective effects. We investigated the effects of endogenous erythropoietin on renal function in kidney ischemic reperfusion injury (IRI) using the prolyl hydroxylase domain (PHD) inhibitor, Roxadustat (ROX). Four h of hypoxia (7% O2) and 4 h treatment by ROX prior to IRI did not improve renal function. In contrast, 24-72 h pretreatment by ROX significantly improved the decline of renal function caused by IRI. Hypoxia and 4 h ROX increased interstitial cells-derived Epo production by 75- and 6-fold, respectively, before IRI, and worked similarly to exogenous Epo. ROX treatment for 24-72 h increased Epo production during IRI by 9-fold. Immunohistochemistry revealed that 24 h ROX treatment induced Epo production in proximal and distal tubules and worked similarly to endogenous Epo. Our data show that tubular endogenous Epo production induced by 24-72 h ROX treatment results in renoprotection but peritubular exogenous Epo production by interstitial cells induced by hypoxia and 4 h ROX treatment did not. Stimulation of tubular, but not peritubular, Epo production may link to renoprotection.

Progress in the Detection of Erythropoietin in Blood, Urine, and Tissue

Detection of erythropoietin (Epo) was difficult until a method was developed by the World Anti-Doping Agency (WADA). WADA recommended the Western blot technique using isoelectric focusing (IEF)-PAGE to show that natural Epo and injected erythropoiesis-stimulating agents (ESAs) appear in different pH areas. Next, they used sodium N-lauroylsarcosinate (SAR)-PAGE for better differentiation of pegylated proteins, such as epoetin β pegol. Although WADA has recommended the use of pre-purification of samples, we developed a simple Western blotting method without pre-purification of samples. Instead of pre-purification, we used deglycosylation of samples before SDS-PAGE. The double detection of glycosylated and deglycosylated Epo bands increases the reliability of the detection of Epo protein. All of the endogenous Epo and exogenous ESAs shift to 22 kDa, except for Peg-bound epoetin β pegol. All endogenous Epo and exogenous ESAs were detected as 22 kDa deglycosylated Epo by liquid chromatography/mass spectrum (LC/MS) analysis. The most important factor for the detection of Epo is the selection of the antibody against Epo. WADA recommended clone AE7A5, and we used sc-9620. Both antibodies are useful for the detection of Epo protein by Western blotting.

Prolyl hydroxylase inhibitor desidustat improves anemia in erythropoietin hyporesponsive state

Many anemic chronic kidney disease (CKD) patients are refractory to erythropoietin (EPO) effects due to inflammation, deranged iron utilization, and generation of EPO antibodies. This work assessed the effect of desidustat, an inhibitor of hypoxia inducible factor (HIF) prolyl hydroxylase (PHD), on EPO-refractory renal anemia. Sprague Dawley rats were made anemic by cisplatin (5 ​mg/kg, IP, single dose) and turpentine oil (5 ​mL/kg, SC, once a week). These rats were given recombinant human EPO (rhEPO, 1 ​μg/kg) and desidustat (15 or 30 ​mg/kg) for eight weeks. Separately, rhEPO (1–5 ​μg/kg) was given to anemic rats to sustain the normal hemoglobin levels and desidustat (15 ​mg/kg) for eight weeks. In another experiment, the anemic rats were treated rhEPO (5 ​μg/kg) for two weeks and then desidustat (15 ​mg/kg) for the next two weeks. Dosing of rhEPO was thrice a week, and for desidustat, it was on alternate days. Desidustat inhibited EPO-resistance caused by rhEPO treatment, decreased hepcidin, IL-6, IL-1β, and increased iron and liver ferroportin. Desidustat reduced EPO requirement and anti-EPO antibodies. Desidustat also maintained normal hemoglobin levels after cessation of rhEPO treatment. Thus, novel prolyl hydroxylase inhibitor desidustat can treat EPO resistance via improved iron utilization and decreased inflammation.

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Prolyl hydroxylase inhibitor desidustat reduces rhEPO requirement in anemia.

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Desidustat maintains normal haemoglobin after discontinuation of rhEPO treatment.

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The drug increases erythropoiesis by increasing endogenous EPO and reducing EPO-resistance.

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It also enhances erythroid maturation by suppressing hepcidin-ferroportin axis.

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Desidustat improves EPO-sensitivity by decreasing IL-6, IL-1β, and anti-EPO antibodies.

Effects of Roxadustat on Erythropoietin Production in the Rat Body

Anemia is a major complication of chronic renal failure. To treat this anemia, prolylhydroxylase domain enzyme (PHD) inhibitors as well as erythropoiesis-stimulating agents (ESAs) have been used. Although PHD inhibitors rapidly stimulate erythropoietin (Epo) production, the precise sites of Epo production following the administration of these drugs have not been identified. We developed a novel method for the detection of the Epo protein that employs deglycosylation-coupled Western blotting. With protein deglycosylation, tissue Epo contents can be quantified over an extremely wide range. Using this method, we examined the effects of the PHD inhibitor, Roxadustat (ROX), and severe hypoxia on Epo production in various tissues in rats. We observed that ROX increased Epo mRNA expression in both the kidneys and liver. However, Epo protein was detected in the kidneys but not in the liver. Epo protein was also detected in the salivary glands, spleen, epididymis and ovaries. However, both PHD inhibitors (ROX) and severe hypoxia increased the Epo protein abundance only in the kidneys. These data show that, while Epo is produced in many tissues, PHD inhibitors as well as severe hypoxia regulate Epo production only in the kidneys.