Triad role of hepcidin, ferroportin, and Nrf2 in cardiac iron metabolism: From health to disease

Canagliflozin and iron metabolism in the CREDENCE trial

BACKGROUND

Studies in patients with heart failure have indicated that sodium-glucose cotransporter 2 (SGLT2) inhibitors increase iron use and enhance erythropoiesis. In this post hoc analysis of the Canagliflozin and Renal Endpoints in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE) trial, we evaluated the effects of canagliflozin on iron metabolism in patients with chronic kidney disease (CKD) and whether the effects of canagliflozin on hemoglobin and cardiorenal outcomes were modified by iron deficiency.

METHODS

We measured serum iron, total iron binding capacity (TIBC), transferrin saturation (TSAT) and ferritin at baseline and 12 months. The effects of canagliflozin, relative to placebo, on iron markers were assessed with analysis of covariance. Interactions between baseline iron deficiency, defined as TSAT <20%, and the effects of canagliflozin on hemoglobin and cardiorenal outcomes were evaluated with mixed effect models and Cox regression models, respectively.

RESULTS

Of 4401 participants randomized in CREDENCE, 2416 (54.9%) had iron markers measured at baseline, of whom 924 (38.2%) were iron deficient. Canagliflozin, compared with placebo, increased TIBC by 2.1% [95% confidence interval (CI) 0.4, 3.8; P = .014] and decreased ferritin by 11.5% (95% CI 7.1, 15.7; P < .001) with no clear effect on serum iron or TSAT. Canagliflozin increased hemoglobin over the trial duration by 7.3 g/L (95% CI 6.2, 8.5; P < .001) and 6.7 g/L (95% CI 5.2, 8.2; P < .001) in patients with and without iron deficiency, respectively (P for interaction = .38). The relative effect of canagliflozin on the primary outcome of doubling of serum creatinine, kidney failure or death due to cardiovascular disease or kidney failure (hazard ratio 0.70, 95% CI 0.56, 0.87) was consistent regardless of iron deficiency (P for interaction = .83), as were effects on other cardiovascular and mortality outcomes (all P for interactions ≥0.10).

CONCLUSION

Iron deficiency is highly prevalent in patients with type 2 diabetes and CKD. Canagliflozin increased TIBC and decreased ferritin in patients with type 2 diabetes and CKD, suggesting increased iron utilization, and improved hemoglobin levels and clinical outcomes regardless of iron deficiency.

Early detection of anthracycline-induced cardiotoxicity

Although anthracyclines are important anticancer agents, their use is limited due to various adverse effects, particularly cardiac toxicity. Mechanisms underlying anthracycline-induced cardiotoxicity (AIC) are complex. Given the irreplaceable role of anthracyclines in treatment of malignancies and other serious diseases, early monitoring of AIC is paramount. In recent years, multiple studies have investigated various biomarkers for early detection of AIC. Currently, the two most common are cardiac troponin and B-type natriuretic peptide. In addition, a range of other molecules, including RNAs, myeloperoxidase (MPO), C-reactive protein (CRP), various genes, and others, also play roles in AIC prediction. Unfortunately, current research indicates a need to validate their sensitivity and specificity of these biomarkers especially in large study populations. In this review, we summarize the mechanisms and potential biomarkers of AIC, although some remain preliminary.

Ferroptosis in diabetic cardiomyopathy: from its mechanisms to therapeutic strategies

Diabetic cardiomyopathy (DCM) is defined as structural and functional cardiac abnormalities in diabetes, and cardiomyocyte death is the terminal event of DCM. Ferroptosis is iron-dependent oxidative cell death. Evidence has indicated that iron overload and ferroptosis play important roles in the pathogenesis of DCM. Mitochondria, an important organelle in iron homeostasis and ROS production, play a crucial role in cardiomyocyte ferroptosis in diabetes. Studies have shown some anti-diabetic medicines, plant extracts, and ferroptosis inhibitors might improve DCM by alleviating ferroptosis. In this review, we systematically reviewed the evidence of ferroptosis in DCM. Anti-ferroptosis might be a promising therapeutic strategy for the treatment of DCM.

Nrf2 mediated signaling axis in heart failure: Potential pharmacological receptor

Heart failure (HF) has emerged as the most pressing health concerns globally, and extant clinical therapies are accompanied by side effects and patients have a high burden of financial. The protein products of nuclear factor erythroid 2-related factor 2 (Nrf2) target genes have a variety of cardioprotective effects, including antioxidant, metabolic functions and anti-inflammatory. By evaluating established preclinical and clinical research in HF to date, we explored the potential of Nrf2 to exert unique cardioprotective functions as a novel therapeutic receptor for HF. In this review, we generalize the progression, structure, and function of Nrf2 research in the cardiovascular system. The mechanism of action of Nrf2 involved in HF as well as agonists of Nrf2 in natural compounds are summarized. Additionally, we discuss the challenges and implications for future clinical translation and application of pharmacology targeting Nrf2. It's critical to developing new drugs for HF.

Protective Role of Dioscin against Doxorubicin-Induced Chronic Cardiotoxicity: Insights from Nrf2-GPX4 Axis-Mediated Cardiac Ferroptosis

Recent evidence suggests that ferroptosis, an iron-facilitated cell death with excessive lipid peroxidation, is a critical mechanism underlying doxorubicin (DOX)-induced cardiotoxicity (DIC). Although dioscin has been reported to improve acute DIC, direct evidence is lacking to clarify the role of dioscin in chronic DIC and its potential mechanism in cardiac ferroptosis. In this study, we used chronic DIC rat models and H9c2 cells to investigate the potential of dioscin to mitigate DIC by inhibiting ferroptosis. Our results suggest that dioscin significantly improves chronic DIC-induced cardiac dysfunction. Meanwhile, it significantly inhibited DOX-induced ferroptosis by reducing Fe2+ and lipid peroxidation accumulation, maintaining mitochondrial integrity, increasing glutathione peroxidase 4 (GPX4) expression, and decreasing acyl-CoA synthetase long-chain family 4 (ACSL4) expression. Through transcriptomic analysis and subsequent validation, we found that the anti-ferroptotic effects of dioscin are achieved by regulating the nuclear factor-erythroid 2-related factor 2 (Nrf2)/GPX4 axis and Nrf2 downstream iron metabolism genes. Dioscin further downregulates nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) and upregulates expression of frataxin (FXN) and ATP-binding cassette B8 (ABCB8) to limit mitochondrial Fe2+ and lipid peroxide accumulation. However, Nrf2 inhibition diminishes the anti-ferroptotic effects of dioscin, leading to decreased GPX4 expression and increased lipid peroxidation. This study is a compelling demonstration that dioscin can effectively reduce DIC by inhibiting ferroptosis, which is dependent on the Nrf2/GPX4 pathway modulation.

What is the impact of ferroptosis on diabetic cardiomyopathy: a systematic review

Iron overload increases the production of harmful reactive oxygen species in the Fenton reaction, which causes oxidative stress in the body and lipid peroxidation in the cell membrane, and eventually leads to ferroptosis. Diabetes is associated with increased intracellular oxidative stress, inflammation, autophagy, microRNA alterations, and advanced glycation end products (AGEs), which cause cardiac remodeling and cardiac diastolic contractile dysfunction, leading to the development of diabetic cardiomyopathy (DCM). While these factors are also closely associated with ferroptosis, more and more studies have shown that iron-mediated ferroptosis is an important causative factor in DCM. In order to gain fresh insights into the functions of ferroptosis in DCM, this review methodically summarizes the traits and mechanisms connected with ferroptosis and DCM.

The possible role of nuclear factor erythroid-2-related factor 2 activators in the management of Covid-19

COVID-19 is caused by a novel SARS-CoV-2 leading to pulmonary and extra-pulmonary manifestations due to oxidative stress (OS) development and hyperinflammation. COVID-19 is primarily asymptomatic though it may cause acute lung injury (ALI), acute respiratory distress syndrome (ARDS), systemic inflammation, and thrombotic events in severe cases. SARS-CoV-2-induced OS triggers the activation of different signaling pathways, which counterbalances this complication. One of these pathways is nuclear factor erythroid 2-related factor 2 (Nrf2), which induces a series of cellular interactions to mitigate SARS-CoV-2-mediated viral toxicity and OS-induced cellular injury. Nrf2 pathway inhibits the expression of pro-inflammatory cytokines and the development of cytokine storm in COVID-19. Therefore, Nrf2 activators may play an essential role in reducing SARS-CoV-2 infection-induced inflammation by suppressing NLRP3 inflammasome in COVID-19. Furthermore, Nrf2 activators can attenuate endothelial dysfunction (ED), renin-angiotensin system (RAS) dysregulation, immune thrombosis, and coagulopathy. Thus this mini-review tries to clarify the possible role of the Nrf2 activators in the management of COVID-19. Nrf2 activators could be an effective therapeutic strategy in the management of Covid-19. Preclinical and clinical studies are recommended in this regard.

Nanoparticles drug delivery for 5-aminolevulinic acid (5-ALA) in photodynamic therapy (PDT) for multiple cancer treatment: a critical review on biosynthesis, detection, and therapeutic applications

Photodynamic therapy (PDT) is a promising cancer treatment that kills cancer cells selectively by stimulating reactive oxygen species generation with photosensitizers exposed to specific light wavelengths. 5-aminolevulinic acid (5-ALA) is a widely used photosensitizer. However, its limited tumour penetration and targeting reduce its therapeutic efficacy. Scholars have investigated nano-delivery techniques to improve 5-ALA administration and efficacy in PDT. This review summarises recent advances in biological host biosynthetic pathways and regulatory mechanisms for 5-ALA production. The review also highlights the potential therapeutic efficacy of various 5-ALA nano-delivery modalities, such as nanoparticles, liposomes, and gels, in treating various cancers. Although promising, 5-ALA nano-delivery methods face challenges that could impair targeting and efficacy. To determine their safety and biocompatibility, extensive preclinical and clinical studies are required. This study highlights the potential of 5-ALA-NDSs to improve PDT for cancer treatment, as well as the need for additional research to overcome barriers and improve medical outcomes.

Djulis Hull Enhances the Efficacy of Ferric Citrate Supplementation via Restoring Normal Iron Efflux through the IL-6-Hepcidin-Ferroportin Pathway in High-Fat-Diet-Induced Obese Rats

Obesity-related functional iron disorder remains a major nutritional challenge. We evaluated the effects of djulis hull (DH) on iron metabolism in 50% high-fat-diet-induced obese rats supplemented with ferric citrate (2 g iron/kg diet) for 12 weeks. DH supplementation (5, 10, 15% dry weight/kg diet) significantly increased serum and hepatic iron but decreased appetite hormones, body weight, hepcidin, and liver inflammation (all p < 0.05). The Spearman correlation showed that appetite hormones were negatively associated with iron but positively correlated with liver hepcidin (all p < 0.05). A Western blot analysis showed that DH significantly downregulated hepatic hepcidin through the IL-6-JAK-STAT3 and enhanced ferroportin (Fpn) via the Keap1-Nrf2 and PHD2-HIF-2α. An in vitro study revealed that major bioactive compounds of DH, hexacosanol, and squalene suppressed LPS-induced IL-6 and hepcidin but enhanced Fpn expression in activated THP-1 cells. In conclusion, DH may exert nutraceutical properties for the treatment of functional iron disorder and restoration of iron efflux may have beneficial effects on weight control.

Empagliflozin effects on iron metabolism as a possible mechanism for improved clinical outcomes in non-diabetic patients with systolic heart failure

Sodium-glucose co-transporter-2 (SGLT2) inhibitors improve clinical outcomes in patients with heart failure (HF), but mechanisms of action are incompletely understood. In the EMPA-TROPISM trial, empagliflozin reversed cardiac remodeling and increased physical capacity in stable non-diabetic patients with systolic HF. Here we explore, post hoc, whether treatment effects in this cohort, comprising patients who had a high prevalence of iron deficiency, were related to iron metabolism. Myocardial iron content estimated by cardiac magnetic resonance T2* quantification increased after initiation of empagliflozin but not placebo (treatment effect: P = 0.01). T2* changes significantly correlated with changes in left ventricular volumes, mass and ejection fraction, peak oxygen consumption and 6-minute walking distance; concomitant changes in red blood cell indices were consistent with augmented hematopoiesis. Exploratory causal mediation analysis findings indicated that changes in myocardial iron content after treatment with empagliflozin may be an important mechanism to explain its beneficial clinical effects in patients with HF.ClinicalTrials.gov: NCT03485222 .

Nrf2 attenuates methamphetamine-induced myocardial injury by regulating oxidative stress and apoptosis in mice

OBJECTIVES

Methamphetamine (MA) abuse is a serious social problem worldwide. Cardiovascular complications were the second leading cause of death among MA abusers. We aimed to clarify the effects of MA on myocardial injury, oxidative stress, and apoptosis in myocardial cells and to explore the potential mechanism of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) in MA-induced oxidative stress and apoptosis.

METHODS

An acute cardiac toxicity model of MA was established by intraperitoneal injection of MA (2 mg/kg) for 5 days. Nrf2 activation (by sulforaphane (SFN) 1 h before MA injection) and Nrf2 gene knockout were performed to explore the regulatory effects of Nrf2 on cardiac toxicity.

RESULTS

The protein expressions of Nrf2 (p < .001) and heme oxygenase-1 (HO-1) were increased (p < .01), suggesting that MA activated the Nrf2/HO-1 pathway. In the MA group, cardiac injury score (p < .001) and cardiac troponin I (cTnI) protein expression increased (p < .01). Malondialdehyde (MDA) content increased (p < .001), superoxide dismutase (SOD) activity decreased (p < .05). Protein expressions of Caspase-3 (p < .001) and Bax (p < .001) increased, and Bcl-2 decreased (p < .001) as well. These changes were reversed by activation of Nrf2 but became more pronounced after Nrf2 knockout, suggested that the activation and knockout of Nrf2 attenuated and aggravated MA-induced myocardial injury, oxidative stress and apoptosis in myocardial cells, respectively.

CONCLUSIONS

MA administration induced myocardial injury, oxidative stress, and apoptosis in mice. Nrf2 attenuated MA-induced myocardial injury by regulating oxidative stress and apoptosis, thus playing a protective role.