Antianemia Drug Roxadustat (FG-4592) Protects Against Doxorubicin-Induced Cardiotoxicity by Targeting Antiapoptotic and Antioxidative Pathways

Betaine alleviates doxorubicin-related cardiotoxicity via suppressing oxidative stress and inflammation via the NLRP3/SIRT1 pathway

Cardiotoxicity is one of the side effects of the anti-cancer drug doxorubicin (DOX) that limits its clinical application. Betaine (BT) is a natural agent with promising useful effects against inflammation and oxidative stress (OS). We assessed the effects of BT on DOX-induced cardiotoxicity in mice. Forty-two male NMRI mice were assigned to six groups: I: control; II: BT (200 mg/kg; orally, alone); III: DOX (2.5 mg/kg; six injections (ip)) for two weeks; IV, V, VI: BT (50 mg/kg, 100 mg/kg, and 200 mg/kg; orally, once a day for two weeks, respectively) plus DOX administration. The cardiac enzymes like cardiac troponin-I (cTn-I), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) were assessed in serum. Oxidative/inflammatory markers like nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), reduced glutathione level (GSH), and glutathione peroxidase (GPx) activities were determined in cardiac tissue. The expressions of NOD-like receptor protein 3 (NLRP3), caspase-1, interleukin (IL)-1β, and silent information regulator 1 (SIRT1) proteins were also evaluated in cardiac tissue. The results indicated that DOX significantly increased LDH, CK-MB, cTn-I, MDA, and NO levels and also the caspase-1, NLRP3, and IL-1β expression. Furthermore, DOX caused a significant reduction in the GSH levels and SOD, CAT, GPX activities, and the expression of SIRT1 protein in heart tissue. However, BT significantly improved all studied parameters. The findings were confirmed by histopathological assessments of the heart. BT can protect against DOX-induced cardiotoxicity by suppressing the activation of NLRP3 and OS by stimulating the SIRT1 pathway.

Cardioprotective potentials of myricetin on doxorubicin-induced cardiotoxicity based on biochemical and transcriptomic analysis

Doxorubicin (DOX) is a commonly used anthracycline in cancer chemotherapy. The clinical application of DOX is constrained by its cardiotoxicity. Myricetin (MYR) is a natural flavonoid widely present in many plants with antioxidant and anti-inflammatory properties. However, MYR's beneficial effects and mechanisms in alleviating DOX-induced cardiotoxicity (DIC) remain unknown. C57BL/6 mice were injected with 15 mg/kg of DOX to establish the DIC, and MYR solutions were administrated by gavage to investigate its cardioprotective potentials. Histopathological analysis, physiological indicators assessment, transcriptomics analysis, and RT-qPCR were used to elucidate the potential mechanism of MYR in DIC treatment. MYR reduced cardiac injury produced by DOX, decreased levels of cTnI, AST, LDH, and BNP, and improved myocardial injury and fibrosis. MYR effectively prevented DOX-induced oxidative stress, such as lowered MDA levels and elevated SOD, CAT, and GSH activities. MYR effectively suppressed NLRP3 and ASC gene expression levels to inhibit pyroptosis while regulating Caspase1 and Bax levels to reduce cardiac cell apoptosis. According to the transcriptomic analysis, glucose and fatty acid metabolism were associated with differential gene expression. KEGG pathway analysis revealed differential gene enrichment in PPAR and AMPK pathways, among others. Following validation, MYR was found to alleviate DIC by regulating glycolipid metabolism and AMPK pathway-related genes. Our findings demonstrated that MYR could mitigate DIC by regulating the processes of oxidative stress, apoptosis, and pyroptosis. MYR is critical in improving DOX-induced myocardial energy metabolism abnormalities mediated by the AMPK signaling pathway. In conclusion, MYR holds promise as a therapeutic strategy for DIC.

Exploring the mechanism of curcumin in the treatment of doxorubicin-induced cardiotoxicity based on network pharmacology and molecular docking technology

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents. However, the nonselective effect leads to serious cardiotoxicity risk in clinical use. Curcumin is a well-known dietary polyphenol that showed a protective effect against the cardiotoxic effect of DOX. This study aimed to assess the role of curcumin in protection against DOX-induced cardiotoxicity. Potential compound and disease targets were obtained from relevant databases, and common targets were screened. Protein-protein interaction (PPI) was used to predict the core targets. Gene ontology (GO) bioprocess analysis and Kyoto encyclopedia of genes and genome enrichment analysis enriched the possible biological processes (BP), cellular components, molecular function, and signaling pathways involved. Finally, the binding of curcumin to target proteins was evaluated through molecular docking. The docking score verified the reliability of the prediction results. In total, 205 curcumin and 700 disease targets were identified. A topological analysis of the PPI network revealed 10 core targets including TP53, tumor necrosis factor-alpha (TNF), AKT1, vascular endothelial growth factor A (VEGFA), prostaglandin-endoperoxide synthase 2 (PTGS2), signal transducer and activator of the transcription 3 (STAT3), HIF1A, MYC, epidermal growth factor receptor (EGFR), and CASP3 (Caspase-3). Furthermore, the enrichment analyses indicated that the effects of curcumin were mediated by genes related to oxidation, inflammation, toxification, cell proliferation, migration, apoptosis, wounding, metabolism, proteolysis, and the signaling pathway of calcium (Ca2+). Molecular docking showed that curcumin could bind with the target proteins with strong molecular force, exhibiting good docking activity. Curcumin has a multi-cardioprotective effect by modulating the core targets' expression in DOX-induced cardiotoxicity. This study elucidated the key target proteins and provided a theoretical basis for further exploring curcumin in the prevention and treatment of DOX-induced cardiotoxicity.

Roxadustat promotes hypoxia-inducible factor-1α/vascular endothelial growth factor signalling to enhance random skin flap survival in rats

Random skin flaps have limited clinical application as a broad surgical reconstruction treatment because of distal necrosis. The prolyl hydroxylase domain-containing protein inhibitor roxadustat (RXD) enhances angiogenesis and reduces oxidative stress and inflammation. This study explored the function of RXD in the survival of random skin flaps. Thirty-six male Sprague-Dawley rats were randomly divided into low-dose RXD group (L-RXD group, 10 mg/kg/2 day), high-dose RXD group (H-RXD group, 25 mg/kg/2 day), and control group (1 mL of solvent, 1:9 DMSO:corn oil). The proportion of surviving flaps was determined on day 7 after surgery. Angiogenesis was assessed by lead oxide/gelatin angiography, and microcirculation blood perfusion was evaluated by laser Doppler flow imaging. Specimens in zone II were obtained, and the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured as indicators of oxidative stress. Histopathological status was evaluated with haematoxylin and eosin staining. The levels of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and the inflammatory factors interleukin (IL)-1β, IL-6, and tumour necrosis factor-α (TNF-α) were detected by immunohistochemistry. RXD promoted flap survival and microcirculatory blood perfusion. Angiogenesis was detected distinctly in the experimental group. SOD activity increased and the MDA level decreased in the experimental group. Immunohistochemistry indicated that the expression levels of HIF-1α and VEGF were increased while the levels of IL-6, IL-1β, and TNF-α were decreased after RXD injection. RXD promoted random flap survival by reinforcing vascular hyperplasia and decreasing inflammation and ischaemia-reperfusion injury.

Effect of roxadustat on red blood cell lifespan in patients with long-term haemodialysis: a single-centre, prospective, single-arm study

Background

Reduced survival of red blood cells (RBCs) in patients with chronic kidney disease (CKD) is thought to contribute to renal anaemia. Although renal anaemia improved greatly because of the wide use of erythropoiesis-stimulating agents (ESAs) and the advancement of dialysis techniques, RBC longevity seems not to be obviously ameliorated.

Methods

In this single-centre, single-arm trial, patients who had been undergoing haemodialysis and ESA therapy with epoetin alfa for at least 12 weeks changed their anti-anaemia drugs from epoetin alfa to oral roxadustat three times per week for 24 weeks. The primary endpoint was the change in RBC lifespan from baseline at week 24. The change in the circulating percentage of eryptotic RBCs, RBC deformability and RBC oxygen transport ability were also assessed.

Results

A total of 27 patients were enrolled, with 26 completing the full course of intervention. At baseline, the average RBC lifespan was 60.1 days [standard deviation (SD) 14.4; n = 27]. At the end of the study period, 26 patients had an RBC lifespan measurement (83.9 days on average; SD 21.9). The RBC lifespan increased by 22.8 days on average [95% confidence interval (CI) 15.5-30.0, P < .001]. This equated to an average RBC lifespan increase of 39.2% (95% CI 27.8-50.6). The percentage of circulating eryptotic RBCs, erythrocyte filtration index and the pressure at which haemoglobin is 50% saturated decreased significantly from baseline to week 24 (1.39 ± 0.44% versus 0.89 ± 0.25%, P < .0001; 0.29 ± 0.12 versus 0.16 ± 0.08, P < .0001 and 32.54 ± 4.83 versus 28.40 ± 2.29, P < .001, respectively).

Conclusion

Roxadustat prolonged RBC lifespan in patients with long-term haemodialysis.

Prolonged hypoxia alleviates prolyl hydroxylation-mediated suppression of RIPK1 to promote necroptosis and inflammation

The prolyl hydroxylation of hypoxia-inducible factor 1α (HIF-1α) mediated by the EGLN-pVHL pathway represents a classic signalling mechanism that mediates cellular adaptation under hypoxia. Here we identify RIPK1, a known regulator of cell death mediated by tumour necrosis factor receptor 1 (TNFR1), as a target of EGLN1-pVHL. Prolyl hydroxylation of RIPK1 mediated by EGLN1 promotes the binding of RIPK1 with pVHL to suppress its activation under normoxic conditions. Prolonged hypoxia promotes the activation of RIPK1 kinase by modulating its proline hydroxylation, independent of the TNFα-TNFR1 pathway. As such, inhibiting proline hydroxylation of RIPK1 promotes RIPK1 activation to trigger cell death and inflammation. Hepatocyte-specific Vhl deficiency promoted RIPK1-dependent apoptosis to mediate liver pathology. Our findings illustrate a key role of the EGLN-pVHL pathway in suppressing RIPK1 activation under normoxic conditions to promote cell survival and a model by which hypoxia promotes RIPK1 activation through modulating its proline hydroxylation to mediate cell death and inflammation in human diseases, independent of TNFR1.

Association between Cardiovascular Response and Inflammatory Cytokines in Non-Small Cell Lung Cancer Patients

Cardiovascular disease is an essential comorbidity in patients with non-small cell lung cancer (NSCLC) and represents an independent risk factor for increased mortality. Therefore, careful monitoring of cardiovascular disease is crucial in the healthcare of NSCLC patients. Inflammatory factors have previously been associated with myocardial damage in NSCLC patients, but it remains unclear whether serum inflammatory factors can be utilized to assess the cardiovascular health status in NSCLC patients. A total of 118 NSCLC patients were enrolled in this cross-sectional study, and their baseline data were collected through a hospital electronic medical record system. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum levels of leukemia inhibitory factor (LIF), interleukin (IL)-18, IL-1β, transforming growth factor-β1 (TGF-β1), and connective tissue growth factor (CTGF). Statistical analysis was performed using the SPSS software. Multivariate and ordinal logistic regression models were constructed. The data revealed an increased serum level of LIF in the group using tyrosine kinase inhibitor (TKI)-targeted drugs compared to non-users (p < 0.001). Furthermore, serum TGF-β1 (area under the curve, AUC: 0.616) and cardiac troponin T (cTnT) (AUC: 0.720) levels were clinically evaluated and found to be correlated with pre-clinical cardiovascular injury in NSCLC patients. Notably, the serum levels of cTnT and TGF-β1 were found to indicate the extent of pre-clinical cardiovascular injury in NSCLC patients. In conclusion, the results suggest that serum LIF, as well as TGFβ1 together with cTnT, are potential serum biomarkers for the assessment of cardiovascular status in NSCLC patients. These findings offer novel insights into the assessment of cardiovascular health and underscore the importance of monitoring cardiovascular health in the management of NSCLC patients.

ILF3 prion-like domain regulates gene expression and fear memory under chronic stress

The prion-like domain (PrLD) is a class of intrinsically disordered regions. Although its propensity to form condensates has been studied in the context of neurodegenerative diseases, the physiological role of PrLD remains unclear. Here, we investigated the role of PrLD in the RNA-binding protein NFAR2, generated by a splicing variant of the Ilf3 gene. Removal of the PrLD in mice did not impair the function of NFAR2 required for survival, but did affect the responses to chronic water immersion and restraint stress (WIRS). The PrLD was required for WIRS-sensitive nuclear localization of NFAR2 and WIRS-induced changes in mRNA expression and translation in the amygdala, a fear-related brain region. Consistently, the PrLD conferred resistance to WIRS in fear-associated memory formation. Our study provides insights into the PrLD-dependent role of NFAR2 for chronic stress adaptation in the brain.

Roxadustat, a HIF-PHD inhibitor with exploitable potential on diabetes-related complications

Diabetes mellitus (DM) is a group of metabolic diseases caused by absolute or relative deficiency of insulin secretion and characterized by chronic hyperglycemia. Its complications affect almost every tissue of the body, usually leading to blindness, renal failure, amputation, etc. and in the final stage, it mostly develops into cardiac failure, which is the main reason why diabetes mellitus manifests itself as a high clinical lethality. The pathogenesis of diabetes mellitus and its complications involves various pathological processes including excessive production of mitochondrial reactive oxygen species (ROS) and metabolic imbalance. Hypoxia-inducible Factor (HIF) signaling pathway plays an important role in both of the above processes. Roxadustat is an activator of Hypoxia-inducible Factor-1α, which increases the transcriptional activity of Hypoxia-inducible Factor-1α by inhibiting hypoxia-inducible factor prolyl hydroxylase (HIF-PHD). Roxadustat showed regulatory effects on maintaining metabolic stability in the hypoxic state of the body by activating many downstream signaling pathways such as vascular endothelial growth factor (VEGF), glucose transporter protein-1 (GLUT1), lactate dehydrogenase (LDHA), etc. This review summarizes the current research findings of roxadustat on the diseases of cardiomyopathy, nephropathy, retinal damage and impaired wound healing, which also occur at different stages of diabetes and greatly contribute to the damage caused by diabetes to the organism. We attempts to uncover a more comprehensive picture of the therapeutic effects of roxadustat, and inform its expanding research about diabetic complications treatment.

Roxadustat alleviates nitroglycerin-induced migraine in mice by regulating HIF-1α/NF-κB/inflammation pathway

Sensitization of central pain and inflammatory pathways play essential roles in migraine, a primary neurobiological headache disorder. Since hypoxia-inducible factor-1α (HIF-1α) is implicated in neuroprotection and inflammation inhibition, herein we investigated the role of HIF-1α in migraine. A chronic migraine model was established in mice by repeated injection of nitroglycerin (10 mg/kg, i.p.) every other day for 5 total injections. In the prevention and acute experiments, roxadustat, a HIF-1α stabilizer, was orally administered starting before or after nitroglycerin injection, respectively. Pressure application measurement, and tail flick and light-aversive behaviour tests were performed to determine the pressure pain threshold, thermal nociceptive sensitivity and migraine-related light sensitivity. At the end of experiments, mouse serum samples and brain tissues were collected for analyses. We showed that roxadustat administration significantly attenuated nitroglycerin-induced basal hypersensitivity and acute hyperalgesia by improving central sensitization. Roxadustat administration also decreased inflammatory cytokine levels in serum and trigeminal nucleus caudalis (TNC) through NF-κB pathway. Consistent with the in vivo results showing that roxadustat inhibited microglia activation, roxadustat (2, 10, and 20 μM) dose-dependently reduced ROS generation and inflammation in LPS-stimulated BV-2 cells, a mouse microglia cell line, by inhibiting HIF-1α/NF-κB pathway. Taken together, this study demonstrates that roxadustat administration ameliorates migraine-like behaviours and inhibits central pain sensitization in nitroglycerin-injected mice, which is mainly mediated by HIF-1α/NF-κB/inflammation pathway, suggesting the potential of HIF-1α activators as therapeutics for migraine.

A Pharmacodynamic Evaluation of the Protective Effects of Roxadustat Against Hypoxic Injury at High Altitude

Purpose

To investigate roxadustat's preventive effects on hypoxia damage in the quick ascent to high altitude.

Methods

The roxadustat (7.8 mg/kg, 15.6 mg/kg, and 31.2 mg/kg) and control groups of BALB/C mice were distributed at random. To evaluate roxadustat's anti-hypoxic effectiveness at the recommended dose, an atmospheric pressure closed hypoxic experiment was used. Wistar rats were randomly assigned to groups that received normal oxygen, hypoxic, acetazolamide, or roxadustat in order to evaluate the protective effects against hypoxic damage. Animal blood was obtained for arterial blood-gas analysis, inflammatory factors, and the identification of oxidative stress indicators. Animal tissues were removed for pathological investigation.

Results

In each group, the mice's survival time was noticeably extended compared to the normal oxygen group. The medium dose had the best time extension rate at 19.05%. Blood SatO₂ and PaO₂ were significantly higher in the roxadustat group compared to the hypoxic group. Erythrocyte content, hemoglobin content, and hematocrit were also significantly higher. Plasma levels of IL-6, TNF-α, and IFN-γ were also significantly lower in the roxadustat group. Roxadustat can also improve the level of oxidative stress in the tissues of hypoxic rats. According to the results of HE staining, roxadustat could greatly lessen the harm done to rat heart, brain, lung, liver, and kidney tissue as a result of hypoxia.

Conclusion

Roxadustat can greatly reduce inflammation, oxidative stress, and tissue damage brought on by hypoxia, showing that it can significantly enhance the body's ability to adapt to high altitude exposure.

Novel function of Roxadustat (FG-4592) as an anti-shock drug in sepsis by regulating mitochondrial oxidative stress and energy metabolism

BACKGROUND

Septic shock is a serious clinical syndrome leading to high mortality. A new anti-anemia drug Roxadustat (FG-4592) protected against cardiac injury and hypertension. However, its effect and mechanism on shock and cardiac dysfunction induced by sepsis require to be investigated.

METHODS

C57BL/6j mice received FG-4592 (10 mg/kg/day) by i.p injection, followed by lipopolysaccharide (LPS) or cecal ligation and puncture (CLP) treatment. Mortality and shock status were monitored during the experiment. Cardiac function was assessed using echocardiography and serum lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) assay. TEM, COX-SDH staining and ATP production were used to evaluate mitochondrial function. A non-targeted metabolomic analysis was performed to evaluate the metabolic disorders.

RESULTS

Both pre- and post-treatment of FG-4592 could improve the survival rate in LPS- and CLP-induced sepsis mice with a better effect in pre-treated animals. Meanwhile, FG-4592 improved systolic blood pressure and body temperature drop in septic mice along with alleviated cardiac dysfunction (as shown by the restoration of decreased LVEF and LVFS and increased LDH and CK-MB) and inflammation. Interestingly, we observed that FG-4592 improved mitochondrial oxidative stress possibly by upregulating the anti-oxidative enzymes of SOD2 and HO-1. Furthermore, FG-4592 improved the energy supply and glycerophospholipid metabolism in cardiomyocytes, possibly through upregulating the HIF-1α-targeted genes of LDHA and PDK1 in glycolysis and CHK-α, respectively.

CONCLUSIONS

FG-4592 protected against mortality and shock in septic animals possibly by antagonizing mitochondrial oxidative stress and metabolic disorders.

GENERAL SIGNIFICANCE

This study provides a potential of FG-4592 as a novel drug for treating septic shock.

Roxadustat: Not just for anemia

Roxadustat is a recently approved hypoxia-inducible factor prolyl hydroxylase inhibitor that has demonstrated favorable safety and efficacy in the treatment of renal anemia. Recent studies found it also has potential for the treatment of other hypoxia-related diseases. Although clinical studies have not yet found significant adverse or off-target effects of roxadustat, clinicians must be vigilant about these possible effects. Hypoxia-inducible factor regulates the expression of many genes and physiological processes in response to a decreased level of oxygen, but its role in the pathogenesis of different diseases is complex and controversial. In addition to increasing the expression of hypoxia-inducible factor, roxadustat also has some effects that may be HIF-independent, indicating some potential off-target effects. This article reviews the pharmacological characteristics of roxadustat, its current status in the treatment of renal anemia, and its possible effects on other pathological mechanisms.

Roxadustat, a Hypoxia-Inducible Factor 1α Activator, Attenuates Both Long- and Short-Term Alcohol-Induced Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a worldwide healthcare problem featured by inflammation, reactive oxygen species (ROS), and lipid dysregulation. Roxadustat is used for chronic kidney disease anemia treatment. As a specific inhibitor of prolyl hydroxylase, it can maintain high levels of hypoxia-inducible factor 1α (HIF-1α), through which it can further influence many important pathways, including the three featured in ALD. However, its effects on ALD remain to be elucidated. In this study, we used chronic and acute ALD mouse models to investigate the protective effects of roxadustat in vivo. Our results showed that long- and short-term alcohol exposure caused rising activities of serum transaminases, liver lipid accumulation, and morphology changes, which were reversed by roxadustat. Roxadustat-reduced fatty liver was mainly contributed by the reducing sterol-responsive element-binding protein 1c (SREBP1c) pathway, and enhancing β-oxidation through inducing peroxisome proliferator-activated receptor α (PPARα) and carnitine palmitoyltransferase 1A (CPT1A) expression. Long-term alcohol treatment induced the infiltration of monocytes/macrophages to hepatocytes, as well as inflammatory cytokine expression, which were also blocked by roxadustat. Moreover, roxadustat attenuated alcohol caused ROS generation in the liver of those two mouse models mainly by reducing cytochrome P450 2E1 (CYP2E1) and enhancing superoxidase dismutase 1 (SOD1) expression. In vitro, we found roxadustat reduced inflammation and lipid accumulation mainly via HIF-1α regulation. Taken together, our study demonstrates that activation of HIF-1α can ameliorate ALD, which is contributed by reduced hepatic lipid synthesis, inflammation, and oxidative stress. This study suggested that roxadustat could be a potential drug for ALD treatment.

Dihydromyricetin protects against Doxorubicin-induced cardiotoxicity through activation of AMPK/mTOR pathway

BACKGROUND

Doxorubicin (DOX) is a highly effective broad-spectrum antitumor agent, but its clinical administration is limited by self-induced cardiotoxicity. Dihydromyricetin (DHM) is a flavonoid compound extracted from the Japanese raisin tree. Evidence that DHM has neovascular protective properties makes it a candidate for studying cardiotoxicity prevention strategy. However, it remains unknown if DHM can protect against cardiotoxicity caused by DOX.

PURPOSE

The present study was performed to evaluate the protective effect of DHM on DOX-induced cardiotoxicity in vivo and in vitro.

METHODS

C57BL/6 mice were intraperitoneally injected with DOX to construct cardiac injury model in vivo, and AC16 cells were exposed to DOX to induce cell injury in vitro. Left ventricular function of mice were detected by echocardiography, the apoptosis of mice cardiac tissue and AC16 cells were detected by TUNEL and Hoechst33342/PI double staining. The expression of apoptosis and autophagy related proteins were detected by western blotting, immunohistochemical staining and immunofluorescence staining.

RESULTS

Echocardiographic results showed that DOX-induced cardiotoxicity were significantly alleviated by DHM pretreatment. DOX induced cardiotoxicity of mice by inhibiting AMPK activation, increasing apoptosis and decreasing autophagy. However, under the same conditions, the heart tissue of DHM-pretreated mice showed increased autophagy and decreased apoptosis via activation AMPK/mTOR pathway. The same results were observed in vitro, and it was also found that DHM can inhibit the production of intracellular ROS in vitro.

CONCLUSION

DHM protects against cardiotoxicity by inhibiting apoptosis and oxidative stress and it can allevate theautophagy inhibition caused by DOX through AMPK/mTOR pathway. DHM preconditioning may be a breakthrough in protecting DOX-induced cardiotoxicity in the future clinical applications.

Clinical Potential of Hypoxia Inducible Factors Prolyl Hydroxylase Inhibitors in Treating Nonanemic Diseases

Hypoxia inducible factors (HIFs) and their regulatory hydroxylases the prolyl hydroxylase domain enzymes (PHDs) are the key mediators of the cellular response to hypoxia. HIFs are normally hydroxylated by PHDs and degraded, while under hypoxia, PHDs are suppressed, allowing HIF-α to accumulate and transactivate multiple target genes, including erythropoiesis, and genes participate in angiogenesis, iron metabolism, glycolysis, glucose transport, cell proliferation, survival, and so on. Aiming at stimulating HIFs, a group of small molecules antagonizing HIF-PHDs have been developed. Of these HIF-PHDs inhibitors (HIF-PHIs), roxadustat (FG-4592), daprodustat (GSK-1278863), vadadustat (AKB-6548), molidustat (BAY 85-3934) and enarodustat (JTZ-951) are approved for clinical usage or have progressed into clinical trials for chronic kidney disease (CKD) anemia treatment, based on their activation effect on erythropoiesis and iron metabolism. Since HIFs are involved in many physiological and pathological conditions, efforts have been made to extend the potential usage of HIF-PHIs beyond anemia. This paper reviewed the progress of preclinical and clinical research on clinically available HIF-PHIs in pathological conditions other than CKD anemia.

Calycosin Alleviates Doxorubicin-Induced Cardiotoxicity and Pyroptosis by Inhibiting NLRP3 Inflammasome Activation

Calycosin (CAL) is the main active component present in Astragalus and reportedly possesses diverse pharmacological properties. However, the cardioprotective effect and underlying mechanism of CAL against doxorubicin- (DOX-) induced cardiotoxicity need to be comprehensively examined. Herein, we aimed to investigate whether the cardioprotective effects of CAL are related to its antipyroptotic effect. A cardiatoxicity model was established by stimulating H9c2 cells and C57BL/6J mice using DOX. In vitro, CAL increased H9c2 cell viability and decreased DOX-induced pyroptosis via NLRP3, caspase-1, and gasdermin D signaling pathways in a dose-dependent manner. In vivo, CAL-DOX cotreatment effectively suppressed DOX-induced cytotoxicity as well as inflammatory and cardiomyocyte pyroptosis via the same molecular mechanism. Next, we used nigericin (Nig) and NLRP3 forced overexpression to determine whether CAL imparts antipyroptotic effects by inhibiting the NLRP3 inflammasome in vitro. Furthermore, CAL suppressed DOX-induced mitochondrial oxidative stress injury in H9c2 cells by decreasing the generation of reactive oxygen species and increasing mitochondrial membrane potential and adenosine triphosphate. Likewise, CAL attenuated the DOX-induced increase in malondialdehyde content and decreased superoxide dismutase and glutathione peroxidase activities in H9c2 cells. In vivo, CAL afforded a protective effect against DOX-induced cardiac injury by improving myocardial function, inhibiting brain natriuretic peptide, and improving the changes of the histological morphology of DOX-treated mice. Collectively, our findings confirmed that CAL alleviates DOX-induced cardiotoxicity and pyroptosis by inhibiting NLRP3 inflammasome activation in vivo and in vitro.

Palmatine attenuates the doxorubicin-induced inflammatory response, oxidative damage and cardiomyocyte apoptosis

BACKGROUND

As a natural isoquinoline alkaloid, palmatine (PLT) has been proven to play a protective role against a variety of cardiovascular diseases. However, little research on the effects of PLT on doxorubicin (DOX)-induced cardiotoxicity has been carried out. Thus, we investigated the potential functions of PLT in DOX-induced cardiotoxicity. In the present study, a single intraperitoneal injection of DOX (15 mg/kg) in mice was used to establish an acute cardiotoxicity model. Our study shows that PLT administration could reduce myocardial injury and improve cardiac dysfunction in DOX-treated mice. Further experiments showed that PLT administration suppressed the DOX-induced inflammatory response, oxidative damage and cardiomyocyte apoptosis in mice. Moreover, we found that the protective effect of PLT treatment was counteracted by sirtuin1 (Sirt1) knockdown. In summary, our study shows that PLT treatment can exert a protective effect against DOX-induced cardiotoxicity.

Hypoxia signaling and oxygen metabolism in cardio-oncology

Cardio-oncology is a rapidly growing field in cardiology that focuses on the management of cardiovascular toxicities associated with cancer-directed therapies. Tumor hypoxia is a central driver of pathologic tumor growth, metastasis, and chemo-resistance. In addition, conditions that mimic hypoxia (pseudo-hypoxia) play a causal role in the pathogenesis of numerous types of cancer, including renal cell carcinoma. Therefore, therapies targeted at hypoxia signaling pathways have emerged over the past several years. Though efficacious, these therapies are associated with significant cardiovascular toxicities, ranging from hypertension to cardiomyopathy. This review focuses on oxygen metabolism in tumorigenesis, the role of targeting hypoxia signaling in cancer therapy, and the relevance of oxygen metabolism in cardio-oncology. This review will specifically focus on hypoxia signaling mediated by hypoxia-inducible factors and the prolyl hydroxylase oxygen-sensing enzymes, the cardiovascular effects of specific cancer targeted therapies mediated on VEGF and HIF signaling, hypoxic signaling in cardiovascular disease, and the role of oxygen in anthracycline cardiotoxicity. The implications of these therapies on myocardial biology and cardiac function are discussed, underlining the fine balance of hypoxia signaling in cardiac homeostasis. Understanding these cardiovascular toxicities will be important to optimize treatment for cancer patients while mitigating potentially severe cardiovascular side effects.

Clinical Pharmacokinetics and Pharmacodynamics of Roxadustat

The pharmacokinetics of roxadustat are well characterized, with an apparent volume of distribution after oral administration of 22–57 L, apparent clearance of 1.2–2.65 L/h, and renal clearance of 0.030–0.026 L/h in healthy volunteers; the elimination half-life is 9.6–16 h. Plasma binding is 99% and the fraction eliminated by hemodialysis is 2.34%. As an interpretation of the pharmacodynamics of roxadustat, we proposed a concept with a hypothetical cascade of two subsequent effects, first on erythropoetin (EPO) and second on hemoglobin (delta Hb). The primary effect on EPO is observed within a few hours after roxadustat administration and can be modeled using the sigmoidal Hill equation. The concentration at half-maximum effect can be inferred at 10–36 µg/mL, the Hill coefficient at 3.3, and the effect bisection time at 10–17 h, corresponding to EPO half-life. The subsequent effect on hemoglobin (delta Hb) is observed after several weeks and can be interpreted as an irreversible, dose proportional, unsaturable effect, continuing in agreement with the lifespan of red blood cells of 63–112 days.

Red blood cell lifespan in long-term hemodialysis patients treated with roxadustat or recombinant human erythropoietin

Introduction

A significant decrease in red blood cell (RBC) survival has been observed in patients with renal failure, which is supposed to contribute to renal anemia. The aim of this observational study was to determine RBC survival in hemodialysis (HD) patients treated with roxadustat or recombinant human erythropoietin (rhuEPO) compared with healthy persons.

Methods

RBC lifespan was measured by Levitt’s CO breath test with newly developed automatic instrument ELS Tester.

Results

A total of 102 patients receiving long-term HD from two independent dialysis centers enrolled in the study, of whom 62 were treated with rhuEPO and 40 were on roxadustat therapy. A total of 25 healthy participants were recruited to match HD participants according to age and sex. Median RBC survival times in rhuEPO, roxadustat, and control groups were 65.0 (25th–75th percentile, 49.5–77.3), 75.5 (25th–75th percentile, 57.3–99.3), and 108.0 (25th–75th percentile, 89.0–141.5) d, respectively. Patients treated with roxadustat had significantly longer RBC survival time than patients treated with rhuEPO (p < .05). In multivariate analysis of factors affecting RBC lifespan in the whole HD patients, anemia treatment drugs (rhuEPO/roxadustat) and levels of hemoglobin were the significantly independent factors. RBC survival was not found to correlate with either weekly rhuEPO dosage (r = –0.087, p = .500) or weekly roxadustat dosage (r = −0.267, p = .110) in our cohort.

Conclusions

HD patients treated with roxadustat had significantly longer RBC survival time than patients treated with rhuEPO, large prospective studies with long-term follow-up are warranted to verify the results in future. Abbreviations RBC: red blood cell; HD: hemodialysis; rhu EPO: recombinant human erythropoietin; ESRD: end-stage renal disease; EPO: erythropoietin; ROS: reactive oxygen species; CKD: chronic kideny disease; ESAs: erythropoiesis-stimulating agents; HIF-PHD: hypoxia-inducible factor prolyl hydroxylase; CO: carbon monoxide; Hb: hemoglobin

Roxadustat (FG-4592) protects against ischaemia/reperfusion-induced acute kidney injury through inhibiting the mitochondrial damage pathway in mice

Ischaemia-reperfusion (I/R) is one of the main factors of acute kidney injury (AKI). mitochondrial damage pathway are important features of I/R induced-acute kidney injury (IRI-AKI). Hypoxia-inducible factor (HIF) expression in renal tubule segments is up-regulated during AKI. Herein, we investigated the role of FG-4592 in a mouse model of IRI-AKI to confirm whether FG-4592 is beneficial in AKI. We found that pretreatment with FG-4592 significantly ameliorated renal function and renal histological damage in mice after IRI. Furthermore, these results suggest that pretreatment with FG-4592 significantly reduced the tubular cells apoptosis (decreased TUNEL-positive cells, Bax, caspase12 levels), attenuated mitochondrial damage (increased ATPβ, PPARγ, mitochondrial DNA copy number, and decreased cytoplasmic cytochrome C), and alleviated DNA damage after IRI. In conclusion, pretreatment with FG-4592 may effectively prevent kidney from IRI possibly by via diminishing tubular cells injuries and protection of mitochondrial damage pathway. These results further validate that FG-4592 may be an effective drug in the clinical treatment of IRI-AKI.

Advances in Cardiotoxicity Induced by Altered Mitochondrial Dynamics and Mitophagy

Mitochondria are the most abundant organelles in cardiac cells, and are essential to maintain the normal cardiac function, which requires mitochondrial dynamics and mitophagy to ensure the stability of mitochondrial quantity and quality. When mitochondria are affected by continuous injury factors, the balance between mitochondrial dynamics and mitophagy is broken. Aging and damaged mitochondria cannot be completely removed in cardiac cells, resulting in energy supply disorder and accumulation of toxic substances in cardiac cells, resulting in cardiac damage and cardiotoxicity. This paper summarizes the specific underlying mechanisms by which various adverse factors interfere with mitochondrial dynamics and mitophagy to produce cardiotoxicity and emphasizes the crucial role of oxidative stress in mitophagy. This review aims to provide fresh ideas for the prevention and treatment of cardiotoxicity induced by altered mitochondrial dynamics and mitophagy.

Anti-anemia drug FG4592 retards the AKI-to-CKD transition by improving vascular regeneration and antioxidative capability

Acute kidney injury (AKI) is a known risk factor for the development of chronic kidney disease (CKD), with no satisfactory strategy to prevent the progression of AKI to CKD. Damage to the renal vascular system and subsequent hypoxia are common contributors to both AKI and CKD. Hypoxia-inducible factor (HIF) is reported to protect the kidney from acute ischemic damage and a novel HIF stabilizer, FG4592 (Roxadustat), has become available in the clinic as an anti-anemia drug. However, the role of FG4592 in the AKI-to-CKD transition remains elusive. In the present study, we investigated the role of FG4592 in the AKI-to-CKD transition induced by unilateral kidney ischemia-reperfusion (UIR). The results showed that FG4592, given to mice 3 days after UIR, markedly alleviated kidney fibrosis and enhanced renal vascular regeneration, possibly via activating the HIF-1α/vascular endothelial growth factor A (VEGFA)/VEGF receptor 1 (VEGFR1) signaling pathway and driving the expression of the endogenous antioxidant superoxide dismutase 2 (SOD2). In accordance with the improved renal vascular regeneration and redox balance, the metabolic disorders of the UIR mice kidneys were also attenuated by treatment with FG4592. However, the inflammatory response in the UIR kidneys was not affected significantly by FG4592. Importantly, in the kidneys of CKD patients, we also observed enhanced HIF-1α expression which was positively correlated with the renal levels of VEGFA and SOD2. Together, these findings demonstrated the therapeutic effect of the anti-anemia drug FG4592 in preventing the AKI-to-CKD transition related to ischemia and the redox imbalance.

SNX17 protects the heart from doxorubicin-induced cardiotoxicity by modulating LMOD2 degradation

Anthracyclines including doxorubicin (DOX) are still the most widely used and efficacious antitumor drugs, although their cardiotoxicity is a significant cause of heart failure. Despite considerable efforts being made to minimize anthracycline-induced cardiac adverse effects, little progress has been achieved. In this study, we aimed to explore the role and underlying mechanism of SNX17 in DOX-induced cardiotoxicity. We found that SNX17 was downregulated in cardiomyocytes treated with DOX both in vitro and in vivo. DOX treatment combined with SNX17 interference worsened the damage to neonatal rat ventricular myocytes (NRVMs). Furthermore, the rats with SNX17 deficiency manifested increased susceptibility to DOX-induced cardiotoxicity (myocardial damage and fibrosis, impaired contractility and cardiac death). Mechanistic investigation revealed that SNX17 interacted with leiomodin-2 (LMOD2), a key regulator of the thin filament length in muscles, via its C-TERM domain and SNX17 deficiency exacerbated DOX-induced cardiac systolic dysfunction by promoting aberrant LMOD2 degradation through lysosomal pathway. In conclusion, these findings highlight that SNX17 plays a protective role in DOX-induced cardiotoxicity, which provides an attractive target for the prevention and treatment of anthracycline induced cardiotoxicity.