VDR activation attenuate cisplatin induced AKI by inhibiting ferroptosis

The role of ferroptosis in the development of acute and chronic kidney diseases

Ferroptosis, a novel form of regulated cell death, is characterized by imbalance of intracellular iron and redox systems, resulting from overgeneration of toxic lipid peroxidation products. In recent years, the verified crucial role of ferroptosis has been widely concerned in rudimentary pathogenesis and development of various acute and chronic kidney disease (CKD), comprehending the potential patterns of cell death can afford more reliable bases and principles for treatment and prevention of renal disease. In this review, the regulatory mechanisms of ferroptosis were introduced and the important roles of ferroptosis in diverse renal diseases such as acute kidney injury, CKD, and renal fibrosis were outlined to illuminate the potential of restraining ferroptosis in treatment and prevention of kidney disease.

Honokiol Antagonizes Cadmium-Induced Nephrotoxicity in Quail by Alleviating Autophagy Dysfunction, Apoptosis and Mitochondrial UPR Inhibition with Its Antioxidant Properties

Japanese quail is a highly economically valuable bird due to its commercial production for meat and eggs. Although studies have reported Cadmium (Cd) is a ubiquitous heavy metal that can cause injury to various organs, the molecular mechanisms of Cd on quail kidney injury remain largely unknown. It has been reported that Honokiol (HKL), a highly functional antioxidant, can protect cells against oxidative stress effectively. This study was conducted to investigate the effects of Cd on quail kidneys injury and the protective effect of HKL on Cd-induced nephrotoxicity. A total of 40 Japanese quails were randomly divided into four groups: the control group, Cd treatment group, Co-treatment group and HKL treatment group. The results showed that Cd resulted in significant changes in growth performance, kidney histopathology and kidney biochemical status, antioxidant enzymes and oxidative stress parameters, and ultrastructure of renal tubular epithelial cells, compared with controls. Cd increased the expression of autophagy-related and apoptosis-related genes, but decreased expression of lysosomal function-related and UPR^mt-related genes. The co-treatment group ameliorated Cd-induced nephrotoxicity by alleviating oxidative stress, inhibiting apoptosis, repairing autophagy dysfunction and UPR^mt disorder. In conclusion, dietary supplementation of HKL showed beneficial effects on Japanese quail kidney injury caused by Cd.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

Regulation Networks of Non-Coding RNA-Associated ceRNAs in Cisplatin-Induced Acute Kidney Injury

Cisplatin is widely used as a chemotherapeutic drug to treat various solid tumors. However, it often induces severe side effects, including nephrotoxicity, which limits its application in clinical settings. Furthermore, the underlying mechanisms of action are unclear. Here, we applied whole-transcriptome RNA sequencing to a cisplatin-induced acute kidney injury (CP-AKI) mouse model to evaluate competing endogenous RNA (ceRNA) networks. We found 4460 mRNAs, 1851 long non-coding RNAs, 101 circular RNAs, and 102 microRNAs significantly differentially expressed between CP-AKI and control mice. We performed gene set enrichment analysis to reveal the biological functions of the mRNAs and constructed non-coding RNA-associated ceRNA networks in CP-AKI mice. Two ceRNA regulatory pathways, Lhx1os-203/mmu-miR-21a-3p/Slc7a13 and circular RNA_3907/mmu-miR-185-3p/Ptprn, were validated using quantitative real-time PCR. The protein–protein interaction network indicated that Il6, Cxcl1, Cxcl2, and Plk1 serve as hub genes and are highly connected with the inflammatory response or DNA damage. Transcription factors, such as Stat3, Cebpb, and Foxm1, regulate gene expression levels in CP-AKI. Our study provides insight into non-coding RNA-associated ceRNA networks and mRNAs in CP-AKI and identifies potential treatment targets.

Vitamin D3 attenuates cisplatin-induced intestinal injury by inhibiting ferroptosis, oxidative stress, and ROS-mediated excessive mitochondrial fission

Intestinal injury is one of the main side-effects of cisplatin (CP) chemotherapy, severely limiting the clinical application of CP. Vitamin D₃ is an essential nutrient for mammals and exists in a wide range of foods; it regulates immune function and reduces oxidative stress. However, the effect of vitamin D₃ on CP-induced intestinal injury is not elucidated. This is the first study to investigate the relationship between ferroptosis and the protective effect of vitamin D₃ on CP-induced intestinal injury. An animal model of CP-induced intestinal injury was established to evaluate the effect of vitamin D₃ on CP-induced intestinal injury and elucidate the underlying mechanisms. We found that vitamin D₃ alleviated intestinal barrier injury and the abnormal morphological structure in CP-induced intestinal injury mice. Vitamin D₃ suppressed oxidative stress by increasing the antioxidant capacity, inhibiting the accumulation of ROS and MDA, and reducing intestinal inflammatory responses. Vitamin D₃ also decreased excessive mitochondrial fission and increased mitochondrial ATPase activity by inhibiting ROS production, which further alleviated the accumulation of ROS. We also confirmed the involvement of ferroptosis in CP-induced intestinal injury in our animal model using ferrostatin-1 (Fer-1) intervention. Vitamin D₃ decreased iron accumulation and reversed GPX4 and DHODH down-regulation. In conclusion, vitamin D₃ protected against CP-induced intestinal injury by inhibiting ferroptosis and alleviating oxidative stress and ROS-mediated excessive mitochondrial fission, suggesting that it may be a novel and promising candidate to prevent CP-induced intestinal injury.

Autophagy promotes GSDME-mediated pyroptosis via intrinsic and extrinsic apoptotic pathways in cobalt chloride-induced hypoxia reoxygenation-acute kidney injury

Cobalt is a transition element that abundantly exists in the environment. Besides direct hypoxia stress, cobalt ions indirectly induce hypoxia-reoxygenation injury (HRI), the main cause of acute kidney injury (AKI), a life-threatening clinical syndrome characterized by the necrosis of the proximal tubular epithelial cells (PTECs) and inflammation. Pyroptosis, a type of inflammatory programmed cell death, might play an essential role in HRI-AKI. However, whether pyroptosis is involved in cobalt chloride (CoCl₂)-induced HRI-AKI remains unknown. Autophagy is a cellular biological process maintaining cell homeostasis that is involved in cell damage in AKI, yet the underlying regulatory mechanism of autophagy on pyroptosis has not been fully understood. In this study, the in vitro and in vivo models of CoCl₂-induced HRI-AKI were established with HK-2 cell line and C57BL/6J mouse. Pyroptosis-related markers were detected with western blotting and immunofluorescence assays, and results showed that gasdermin E (GSDME)-mediated pyroptosis was involved in the cell damage in HRI-AKI. Specific chemical inhibitors of caspase 3, caspase 8, and caspase 9 significantly inhibited GSDME-mediated pyroptosis, verifying that GSDME-mediated pyroptosis was induced via the activation of caspase 3/8/9. The western blotting and immunofluorescence assays were adopted to detect the accumulation of the autophagosomes, and results suggested that HRI increased the autophagic level. The effects of autophagy on apoptosis and pyroptosis were evaluated using lentivirus transfection assays to knock down autophagy-specific genes atg5 and fip200, and results demonstrated that autophagy induced GSDME-mediated pyroptosis via apoptotic pathways in HRI-AKI. Our results revealed the involvement of GSDME-mediated pyroptosis in CoCl₂-induced HRI-AKI and promoted the understanding of the regulatory mechanism of GSDME cleavage. Our study might provide a potential therapeutic target for HRI-AKI, and will be helpful for the risk evaluation of cobalt exposure.

UFL1 alleviates ER stress and apoptosis stimulated by LPS via blocking the ferroptosis pathway in human granulosa-like cells

Ubiquitin-like modifier 1 ligating enzyme 1 (UFL1) is a unique E3 ligase of the UFMylation system. Recent studies have shown that this enzyme plays a crucial role in the processes of endoplasmic reticulum stress (ER stress) and apoptosis. Lipopolysaccharide (LPS) can cause injury to ovarian granule cells and hinder follicular development by triggering ER stress and apoptosis. Our study aimed to investigate the mechanism by which UFL1 alleviates ER stress and apoptosis caused by LPS in human granulosa-like cells (KGNs). In this study, we found that the protein levels of UFL1 were increased obviously under LPS stimulation in KGNs and that ER stress and apoptosis were further aggravated when UFL1 was knocked down; in contrast, these events were rescued when UFL1 was overexpressed. Next, we showed that the levels of ferroptosis-related proteins were relatively altered, accompanied by the accumulation of reactive oxygen species (ROS) and Fe2+, following the inhibition of UFL1 expression. In contrast, the overexpression of UFL1 reversed the ferroptosis process by regulating the P53/SLC7A11 (solute carrier family 7, member 11, SLC7A11) system and autophagy in response to LPS stimulation. Furthermore, apoptosis and ER stress in KGNs are rescued by the administration of the ferroptosis inhibitor ferrostatin-1 (Fer-1). Collectively, our research demonstrated a new mechanism for UFL1 that can alleviate ER stress and apoptosis stimulated by LPS; this occurred via the regulation of the ferroptosis pathway in KGNs and may provide a new strategy for research in the field of reproduction.

Melatonin Alleviates Acute Kidney Injury by Inhibiting NRF2/Slc7a11 Axis-Mediated Ferroptosis

Acute kidney injury (AKI) is still a puzzling clinical problem; its pathophysiology is not completely understood. Up to now, an effective treatment for AKI is lacking. Ferroptosis is a novel form of regulated cell death characterized by the lethal accumulation of lipid hydroperoxides that are dependent on iron and reactive oxygen species and mitochondrial dysfunction. Recently, ferroptosis was shown to play a vital role in AKI such as ischemia-reperfusion kidney injury and folic acid-induced AKI. Melatonin (MT) is an antioxidant that regulates the sleep-wake cycle. While the therapeutic effect of melatonin on AKI has been reported, its mechanism for the treatment of renal ferroptosis remains unclear. We found that melatonin treatment significantly alleviated the serum biochemistry index and histopathological alterations in vivo AKI models induced by bilateral renal artery ischemia reperfusion and folic acid in mice. Ferroptosis induced by hypoxia and reoxygenation or erastin (Era) in mouse tubular epithelial cells (MTEC) was also rescued by melatonin treatment. RNA sequence analysis of ferroptosis-related genes showed that melatonin affects oxidative stress responses by inhibiting hypoxia and reoxygenation- (HR-) mediated downregulation of NRF2 and upregulation of Slc7a11 in MTEC. Specific knockdown of NRF2 increased the sensitivity of cells to ferroptosis, and melatonin failed to protect against ferroptosis in the HR condition. Together, our data indicate that melatonin prevents ferroptosis in AKI by acting on the NRF2/Slc7a11 axis.

Ferrostatin‑1 alleviates oxalate‑induced renal tubular epithelial cell injury, fibrosis and calcium oxalate stone formation by inhibiting ferroptosis

The present study aimed to evaluate the role and mechanism of ferrostatin-1 (Fer-1) in oxalate (Ox)-induced renal tubular epithelial cell injury, fibrosis, and calcium oxalate (CaOx) stone formation. A CaOx model in mice kidneys was established via intraperitoneal injection of 80 mg/kg glyoxylic acid for 14 days. The mice were randomly divided into three groups (n=6), namely, the control (Con), the CaOx group, and the CaOx + Fer-1 group. Cultured human renal tubular epithelial cells (HK-2 cells) were randomly divided into three groups (n=3), namely, the control (Con), the Ox group, and the Ox + Fer-1 group. The levels of heme oxygenase 1 (HO-1), superoxide dismutase 2 (SOD2), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11) were assessed by immunofluorescence and western blot analysis. Renal tubular injury and apoptosis were evaluated by H&E and TUNEL staining. Kidney interstitial fibrosis was evaluated by Masson and Sirius red staining, and the levels of E-cadherin, vimentin and α-SMA were detected by immunofluorescence or western blot analysis. Mitochondrial structure was observed using a transmission electron microscope. The levels of reactive oxygen species (ROS) were determined by flow cytometry and CaOx stone formation was evaluated by von Kossa staining. The results revealed that in comparison with the Con group, mitochondrial injury under glyoxylic acid treatment was observed by TEM. The expression of GPX4 and SLC7A11 in the CaOx and Ox groups was downregulated (P<0.05), whereas the expression of HO-1 and SOD2 was upregulated (P<0.05). Renal tissue damage, apoptosis of renal tubular epithelial cells, and interstitial fibrosis were increased in the CaOx and Ox groups (P<0.05). In comparison with the CaOx or Ox group, the expression of GPX4 and SLC7A11 in the CaOx + Fer-1 or Ox + Fer-1 group was upregulated (P<0.05), whereas that of HO-1 and SOD2 was downregulated (P<0.05). Renal tissue damage, apoptosis of renal tubular epithelial cells and interstitial fibrosis were decreased following Fer-1 treatment (P<0.05). The ROS level was also decreased following Fer-1 treatment. Moreover, CaOx stone formation was decreased in the CaOx + Fer-1 group (P<0.05). In conclusion, Fer-1 alleviated Ox-induced renal tubular epithelial cell injury, fibrosis, and CaOx stone formation by inhibiting ferroptosis.

Targeting Oxidative Stress Involved in Endometriosis and Its Pain

Endometriosis is a common gynecological disorder seen in women and is characterized by chronic pelvic pain and infertility. This disorder is becoming more prevalent with increased morbidity. The etiology of endometriosis remains to be fully elucidated, which will lead to improved therapeutic options. In this review, we will evaluate the biochemical mechanisms leading to oxidative stress and their implication in the pathophysiology of endometriosis, as well as potential treatments that target these processes. A comprehensive exploration of previous research revealed that endometriosis is associated with elevated reactive oxygen species and oxidation products, decreased antioxidants and detoxification enzymes, and dysregulated iron metabolism. High levels of oxidative stress contributed to inflammation, extracellular matrix degradation, angiogenesis, and cell proliferation, which may explain its role in endometriosis. Endometriosis-associated pain was attributed to neurogenic inflammation and a feed-forward mechanism involving macrophages, pro-inflammatory cytokines, and pain-inducing prostaglandins. N-acetylcysteine, curcumin, melatonin, and combined vitamin C and E supplementation displayed promising results for the treatment of endometriosis, but further research is needed for their use in this population.

Progress and Setbacks in Translating a Decade of Ferroptosis Research into Clinical Practice

Ten years after its initial description, ferroptosis has emerged as the most intensely studied entity among the non-apoptotic forms of regulated cell death. The molecular features of ferroptotic cell death and its functional role have been characterized in vitro and in an ever-growing number of animal studies, demonstrating that it exerts either highly detrimental or, depending on the context, occasionally beneficial effects on the organism. Consequently, two contrary therapeutic approaches are being explored to exploit our detailed understanding of this cell death pathway: the inhibition of ferroptosis to limit organ damage in disorders such as drug-induced toxicity or ischemia-reperfusion injury, and the induction of ferroptosis in cancer cells to ameliorate anti-tumor strategies. However, the path from basic science to clinical utility is rocky. Emphasizing ferroptosis inhibition, we review the success and failures thus far in the translational process from basic research in the laboratory to the treatment of patients.

MicroRNA-214-3p aggravates ferroptosis by targeting GPX4 in cisplatin-induced acute kidney injury

Acute kidney injury (AKI) induced by cisplatin (cis-AKI) involves indicators such as inflammation and oxidative stress (OS) in proximal tubules, although its underlying mechanisms remain largely unknown so far. Exploration of the molecular mechanisms underlying cisplatin-induced AKI is of great significance for AKI prevention and also for preventing its progression into chronic kidney disease (CKD) or end-stage renal disease (ESRD). OS and ferroptosis are mutually causal; they finally lead to the regulatory cell injury and death induced by the accumulation of reactive oxygen species (ROS). GPX4 is critical not only in OS, but studies established as the key regulator of ferroptosis. In this context, the present study focused on determining the biological function of miR-214-3p in the cisplatin-induced ferroptosis of tubular epithelial cell (TEC) and the underlying molecular mechanism. The relationship between TEC ferroptosis and cisplatin-induced AKI was investigated in vitro and in vivo. Ferrostatin-1(Fer-1), an inhibitor of ferroptosis, was observed to confer a protective effect against the renal tubular injury and renal failure induced by cisplatin. MicroRNAs (miRNAs) regulate the genes that have important functions in the development of cis-AKI. In the present study, GPX4 was predicted as a target of miR-214-3p. Moreover, inhibiting miR-214-3p enhanced the expressions of GPX4 and SLC7A11 while decreasing the ACSL4 expression. Furthermore, miR-214-3p down-regulation protected against TEC death and renal tubule damage both in vitro and in vivo. According to these findings, inhibiting miR-214-3p would alleviate TEC ferroptosis in cis-AKI via GPX4.

Entacapone alleviates acute kidney injury by inhibiting ferroptosis

Acute kidney injury (AKI) is a common clinical problem and an efficacious treatment is lacking. Ferroptosis, a newly discovered type of programmed cell death, has been reported to alleviate renal tubular injury in ischemia/reperfusion-induced acute kidney injury (I/R-AKI). Entacapone is a specific inhibitor of catechol-O-methyltransferase, which is used as an adjuvant drug against Parkinson's disease. We demonstrated that entacapone prevents renal I/R injury by inhibiting ferroptosis. Compared with a sham group, entacapone treatment mitigated I/R-induced pathological alterations, improved renal function, and inhibited ferroptosis. In HK-2 cells, entacapone treatment significantly reduced the lipid peroxidation and iron accumulation induced by the ferroptosis inducers erastin and RSL3, and significantly regulated expression of ferroptosis-related proteins. Entacapone upregulates p62 expression and affects the p62-KEAP1-NRF2 pathway, thereby upregulating nuclear translocation of NRF2. This action results in increased expression of the downstream SLC7A11, and significant suppression of oxidative stress and ferroptosis. Our results identify entacapone as a ferroptosis inhibitor that enhances antioxidant capacity. Entacapone may serve as a novel strategy to improve treatment of, and recovery from, I/R-AKI.

The Pathophysiology of Sepsis-Associated AKI

Sepsis-associated AKI is a life-threatening complication that is associated with high morbidity and mortality in patients who are critically ill. Although it is clear early supportive interventions in sepsis reduce mortality, it is less clear that they prevent or ameliorate sepsis-associated AKI. This is likely because specific mechanisms underlying AKI attributable to sepsis are not fully understood. Understanding these mechanisms will form the foundation for the development of strategies for early diagnosis and treatment of sepsis-associated AKI. Here, we summarize recent laboratory and clinical studies, focusing on critical factors in the pathophysiology of sepsis-associated AKI: microcirculatory dysfunction, inflammation, NOD-like receptor protein 3 inflammasome, microRNAs, extracellular vesicles, autophagy and efferocytosis, inflammatory reflex pathway, vitamin D, and metabolic reprogramming. Lastly, identifying these molecular targets and defining clinical subphenotypes will permit precision approaches in the prevention and treatment of sepsis-associated AKI.

Iron-Induced Hepatocarcinogenesis—Preventive Effects of Nutrients

The liver is a primary organ that stores body iron, and plays a central role in the regulation of iron homeostasis. Hepatic iron overload (HIO) is a prevalent feature among patients with chronic liver diseases (CLDs), including alcoholic/nonalcoholic liver diseases and hepatitis C. HIO is suggested to promote the progression toward hepatocellular carcinoma because of the pro-oxidant nature of iron. Iron metabolism is tightly regulated by various factors, such as hepcidin and ferroportin, in healthy individuals to protect the liver from such deteriorative effects. However, their intrinsic expressions or functions are frequently compromised in patients with HIO. Thus, various nutrients have been reported to regulate hepatic iron metabolism and protect the liver from iron-induced damage. These nutrients are beneficial in HIO-associated CLD treatment and eventually prevent iron-mediated hepatocarcinogenesis. This mini-review aimed to discuss the mechanisms and hepatocarcinogenic risk of HIO in patients with CLDs. Moreover, nutrients that hold the potential to prevent iron-induced hepatocarcinogenesis are summarized.

Ferroptosis and Its Role in Chronic Diseases

Ferroptosis, which has been widely associated with many diseases, is an iron-dependent regulated cell death characterized by intracellular lipid peroxide accumulation. It exhibits morphological, biochemical, and genetic characteristics that are unique in comparison to other types of cell death. The course of ferroptosis can be accurately regulated by the metabolism of iron, lipids, amino acids, and various signal pathways. In this review, we summarize the basic characteristics of ferroptosis, its regulation, as well as the relationship between ferroptosis and chronic diseases such as cancer, nervous system diseases, metabolic diseases, and inflammatory bowel diseases. Finally, we describe the regulatory effects of food-borne active ingredients on ferroptosis.

Dexmedetomidine Attenuates Ferroptosis-Mediated Renal Ischemia/Reperfusion Injury and Inflammation by Inhibiting ACSL4 via α2-AR

Ischemia-reperfusion (I/R) injury is a serious clinical pathology associated with acute kidney injury (AKI). Ferroptosis is non-apoptotic cell death that is known to contribute to renal I/R injury. Dexmedetomidine (Dex) has been shown to exert anti-inflammatory and organ protective effects. This study aimed to investigate the detailed molecular mechanism of Dex protects kidneys against I/R injury through inhibiting ferroptosis. We established the I/R-induced renal injury model in mice, and OGD/R induced HEK293T cells damage in vitro. RNA-seq analysis was performed for identifying the potential therapeutic targets. RNA-seq analysis for differentially expressed genes (DEGs) reported Acyl-CoA synthetase long-chain family member 4 (ACSL4) related to ferroptosis and inflammation in I/R mice renal, which was validated in rodent renal. Liproxstatin-1, the specific small-molecule inhibitor of ferroptosis, significantly attenuated ferroptosis-mediated renal I/R injury with decreased LPO, MDA, and LDH levels, and increased GSH level. Inhibiting the activity of ACSL4 by the Rosiglitazone (ROSI) resulted in the decreased ferroptosis and inflammation, as well as reduced renal tissue damage, with decreasing LPO, MDA and LDH level, increasing GSH level, reducing COX2 and increasing GPx4 protein expression, and suppressing the TNF-α mRNA and IL-6 mRNA levels. Dex as a α2-adrenergic receptor (α2-AR) agonist performed renal protective effects against I/R-induced injury. Our results also revealed that Dex administration mitigated tissue damage, inhibited ferroptosis, and downregulated inflammation response following renal I/R injury, which were associated with the suppression of ACSL4. In addition, ACSL4 overexpression abolishes Dex-mediated protective effects on OGD/R induced ferroptosis and inflammation in HEK293T cells, and promotion of ACSL4 expression by α2-AR inhibitor significantly reversed the effects on the protective role of Dex. This present study indicated that the Dex attenuates ferroptosis-mediated renal I/R injury and inflammation by inhibiting ACSL4 via α2-AR.

Crosstalk between ferroptosis and stress-Implications in cancer therapeutic responses

Ferroptosis is a newly discovered form of cell death that is characterized by the accumulation of iron-dependent lipid peroxidation. Research on ferroptosis has seen exponential growth over the past few years. Tumor cells are strongly dependent on iron for their growth, which makes them develop mechanisms to increase iron uptake and inhibit iron output, thereby completing iron accumulation. Ferroptosis can be induced or inhibited by various stresses through multiple mechanisms, making it stands at the crossroads of stresses related cancer cell fate determination. In this review, we give a brief summary of ferroptosis hallmarks and provide a systematic analysis of the current molecular mechanisms and regulatory networks of diverse stress conditions on ferroptosis. We also discuss the relationships between ferroptosis and cancer therapy responses to further understand potential targets and therapeutic strategies for cancer treatment.

HDM induce airway epithelial cell ferroptosis and promote inflammation by activating ferritinophagy in asthma

Asthma is a disease characterized by airway epithelial barrier destruction, chronic airway inflammation, and airway remodeling. Repeated damage to airway epithelial cells by allergens in the environment plays an important role in the pathophysiology of asthma. Ferroptosis is a novel form of regulated cell death mediated by lipid peroxidation in association with free iron-mediated Fenton reactions. In this study, we explored the contribution of ferroptosis to house dust mite (HDM)-induced asthma models. Our in vivo and in vitro models showed labile iron accumulation and enhanced lipid peroxidation with concomitant nonapoptotic cell death upon HDM exposure. Treatment with ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (Fer-1) illuminated the role of ferroptosis and related damage-associated molecular patterns in HDM-treated airway epithelial cells. Furthermore, DFO and Fer-1 reduced HDM-induced airway inflammation in model mice. Mechanistically, NCOA4-mediated ferritin-selective autophagy (ferritinophagy) was initiated during ferritin degradation in response to HDM exposure. Together, these data suggest that ferroptosis plays an important role in HDM-induced asthma and that ferroptosis may be a potential treatment target for HDM-induced asthma.

Preliminary study on 24p3 / neutrophil gelatinase-associated lipocalin (NGAL) ferroptosis inhibition in renal tubular epithelial cells

The 24p3/neutrophil gelatinase-associated lipocalin (NGAL) protein plays an important protective role in acute kidney injury (AKI), but the exact mechanism remains unclear. Therefore, we have made a preliminary exploration of its mechanism. The experimental group was formed by constructing and transfecting 24P3 overexpressed plasmid into renal tubular epithelial cells. Western Bolt was used to detect NGAL expression. Cell proliferation was detected by CCK8 kit, cell death was detected by Hoechst 33342 and PI kit, mitochondrial morphology was observed under light microscope, reactive oxygen species (ROS) content was detected by fluorescence probe, and iron level and glutathione peroxidase 4 (GPX4) activity were detected by kit. Furthermore, the mechanism of NGAL action was further demonstrated by adding ferrostein-1 (Fer-1), an ferroptosis inhibitor, and erastin (containing DMSO),an ferroptosis inductor. We found that ferroptosis-related indicators were lower in the NGAL overexpression group than in the control group. At the same time, we found that NGAL alleviated ferroptosis induced by erastin and coordinated with Fer-1 to alleviate ferroptosis. In conclusion, NGAL inhibits ferroptosis in renal tubular epithelial cells, which may be associated with the progression of AKI and may provide a new therapeutic target for the transition from acute kidney injury to chronic kidney injury.

Role of tRNA derived fragments in renal ischemia-reperfusion injury

Background

Ischemia–reperfusion injury (IRI) is one of the major causes of acute kidney injury (AKI). tRNA derived fragments (tRFs/tiRNAs) are groups of small noncoding RNAs derived from tRNAs. To date, the role of tRFs/tiRNAs in renal IRI has not been reported. Herein, we aimed to investigate the involvement of tRFs/tiRNAs in the occurrence and development of ischemia–reperfusion-induced AKI.

Methods

Moderate/severe renal IRI mouse models were established by bilateral renal pedicle clamping. The tRF/tiRNA profiles of healthy controls and moderate/severe IRI-stressed kidney tissues were sequenced by Illumina NextSeq 500. Candidate differentially expressed tiRNAs were further verified by RT-qPCR. Biological analysis was also performed.

Results

Overall, 152 tRFs/tiRNAs were differentially expressed in the moderate ischemic injury group compared with the normal control group (FC > 2, p < 0.05), of which 47 were upregulated and 105 were downregulated; in the severe ischemic injury group, 285 tRFs/tiRNAs were differentially expressed (FC > 2, p < 0.05), of which 157 were upregulated, and 128 were downregulated. RT-qPCR determination of eight abundantly expressed tiRNAs was consistent with the sequencing results. Gene Ontology analysis for target genes of the tRFs/tiRNAs showed that the most enriched cell components, molecular functions and biological processes were Golgi apparatus, cytoplasmic vesicles, protein binding, cellular protein localization and multicellular organism development. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these target genes were mainly involved in the natural killer cell mediated cytotoxicity pathway, citrate cycle, and regulation of actin cytoskeleton signaling pathway.

Conclusion

Our results indicated that tRFs/tiRNAs were involved in renal IRI. These tRFs/tiRNAs may be effective partly via regulation of renal immunity, inflammation and metabolism processes. Candidate genes, including tiRNA-Gly-GCC-003, tiRNA-Lys-CTT-003, and tiRNA-His-GTG-002, might be potential biomarkers and therapeutic targets of ischemia–reperfusion injury-induced acute kidney injury.

Several Alkaloids in Chinese Herbal Medicine Exert Protection in Acute Kidney Injury: Focus on Mechanism and Target Analysis

Objectives

Acute kidney injury (AKI) is a loose set of kidney diseases accompanied by a variety of syndromes, which is a serious threat to human life and health. Some alkaloids are derived from various Chinese herbs have been widely concerned in the improvement of AKI. This review provides the research progress of alkaloids in AKI experimental models and discusses the related molecular mechanisms. Key Findings. Alkaloids can protect AKI through various mechanisms including antioxidant stress, improvement of mitochondrial damage, reduction of cell death, induction of autophagy, and inhibition of inflammation. These mechanisms are mainly related to the activation of Nrf2/HO-1 signaling pathway, inhibition of ferroptosis and apoptosis, regulation of PINK1/Parkin pathway, inhibition of TLR4/NF-κB pathway and NLRP3 inflammatory bodies, upregulation of Klotho protein level and so on. In addition, there are a few alkaloids that have certain toxicity on the kidney.

Conclusion

Alkaloids have been shown to significantly improve AKI, but only in pharmacological studies. This paper summarizes the main experimental models currently used in AKI research and describes some representative alkaloids based on recent research. Their potential roles in the prevention and treatment of AKI through different mechanisms are highlighted.

Ferroptosis and Acute Kidney Injury (AKI): Molecular Mechanisms and Therapeutic Potentials

Acute kidney injury (AKI), a common and serious clinical kidney syndrome with high incidence and mortality, is caused by multiple pathogenic factors, such as ischemia, nephrotoxic drugs, oxidative stress, inflammation, and urinary tract obstruction. Cell death, which is divided into several types, is critical for normal growth and development and maintaining dynamic balance. Ferroptosis, an iron-dependent nonapoptotic type of cell death, is characterized by iron overload, reactive oxygen species accumulation, and lipid peroxidation. Recently, growing evidence demonstrated the important role of ferroptosis in the development of various kidney diseases, including renal clear cell carcinoma, diabetic nephropathy, and AKI. However, the exact mechanism of ferroptosis participating in the initiation and progression of AKI has not been fully revealed. Herein, we aim to systematically discuss the definition of ferroptosis, the associated mechanisms and key regulators, and pharmacological progress and summarize the most recent discoveries about the role and mechanism of ferroptosis in AKI development. We further conclude its potential therapeutic strategies in AKI.

Nigratine as dual inhibitor of necroptosis and ferroptosis regulated cell death

Nigratine (also known as 6E11), a flavanone derivative of a plant natural product, was characterized as highly specific non-ATP competitive inhibitor of RIPK1 kinase, one of the key components of necroptotic cell death signaling. We show here that nigratine inhibited both necroptosis (induced by Tumor Necrosis Factor-α) and ferroptosis (induced by the small molecules glutamate, erastin, RSL3 or cumene hydroperoxide) with EC50 in the µM range. Taken together, our data showed that nigratine is a dual inhibitor of necroptosis and ferroptosis cell death pathways. These findings open potential new therapeutic avenues for treating complex necrosis-related diseases.

Leonurine hydrochloride alleviates ferroptosis in cisplatin-induced acute kidney injury by activating the Nrf2 signaling pathway

BACKGROUND AND PURPOSE

Increasing evidence suggests that ferroptosis plays a key role in the pathophysiology of acute kidney injury (AKI) induced by cisplatin. The Nrf2 signaling pathway regulates oxidative stress and lipid peroxidation and positively regulates cisplatin-induced AKI (CI-AKI). However, its effect as well as an alkaloid compound leonurine hydrochloride (LH) on ferroptosis after CI-AKI remain unclear.

EXPERIMENTAL APPROACH

The anti-ferroptotic effects of Nrf2 and LH were assessed using a mouse model of cisplatin-induced AKI. In vitro, the potential effects of LH on erastin- and RSL3-induced HK-2 human PTEC ferroptosis were examined.

KEY RESULTS

As expected, Nrf2 deletion induced ferroptosis-related protein expression and iron accumulation in vivo, further aggravating CI-AKI. LH activated Nrf2 and prevented iron accumulation, lipid peroxidation and ferroptosis in vitro, while these effects were abolished in siNrf2-treated cells. Moreover, LH potently ameliorated cisplatin-induced renal damage, as indicated by the assessment of SCr, BUN, KIM-1, and NGAL. Importantly, LH activated the Nrf2 antioxidative signaling pathway and prohibited changes in ferroptosis-related morphological and biochemical indicators, such as the MDA level, SOD and GSH depletion and GPX4 and xCT downregulation, in CI-AKI. Moreover, Nrf2 KO mice were more susceptible to ferroptosis after CI-AKI than control mice, and the protective effects of LH on AKI and ferroptosis were largely abolished in Nrf2 KO mice.

CONCLUSION AND IMPLICATIONS

These data suggest that the renal protective effects of Nrf2 activation on CI-AKI are achieved at least partially by inhibiting lipid peroxide-mediated ferroptosis and highlight the potential of LH as a CI-AKI treatment.

Nucleic Acid Nanotechnology for Diagnostics and Therapeutics in Acute Kidney Injury

Acute kidney injury (AKI) has impacted a heavy burden on global healthcare system with a high morbidity and mortality in both hospitalized and critically ill patients. However, there are still some shortcomings in clinical approaches for the disease to date, appealing for an earlier recognition and specific intervention to improve long-term outcomes. In the past decades, owing to the predictable base-pairing rule and highly modifiable characteristics, nucleic acids have already become significant biomaterials for nanostructure and nanodevice fabrication, which is known as nucleic acid nanotechnology. In particular, its excellent programmability and biocompatibility have further promoted its intersection with medical challenges. Lately, there have been an influx of research connecting nucleic acid nanotechnology with the clinical needs for renal diseases, especially AKI. In this review, we begin with the diagnostics of AKI based on nucleic acid nanotechnology with a highlight on aptamer- and probe-functionalized detection. Then, recently developed nanoscale nucleic acid therapeutics towards AKI will be fully elucidated. Furthermore, the strengths and limitations will be summarized, envisioning a wiser and wider application of nucleic acid nanotechnology in the future of AKI.

Atorvastatin Induces Mitochondria-Dependent Ferroptosis via the Modulation of Nrf2-xCT/GPx4 Axis

As one of the cornerstones of clinical cardiovascular disease treatment, statins have an extensive range of applications. However, statins commonly used have side reactions, especially muscle-related symptoms (SAMS), such as muscle weakness, pain, cramps, and severe condition of rhabdomyolysis. This undesirable muscular effect is one of the chief reasons for statin non-adherence and/or discontinuation, contributing to adverse cardiovascular outcomes. Moreover, the underlying mechanism of muscle cell damage is still unclear. Here, we discovered that ferroptosis, a programmed iron-dependent cell death, serves as a mechanism in statin-induced myopathy. Among four candidates including atorvastatin, lovastatin, rosuvastatin, and pravastatin, only atorvastatin could lead to ferroptosis in human cardiomyocytes (HCM) and murine skeletal muscle cells (C2C12), instead of human umbilical vein endothelial cell (HUVEC). Atorvastatin inhibits HCM and C2C12 cell viability in a dose-dependent manner, accompanying with significant augmentation in intracellular iron ions, reactive oxygen species (ROS), and lipid peroxidation. A noteworthy investigation found that those alterations particularly occurred in mitochondria and resulted in mitochondrial dysfunction. Biomarkers of myocardial injury increase significantly during atorvastatin intervention. However, all of the aforementioned enhancement could be restrained by ferroptosis inhibitors. Mechanistically, GSH depletion and the decrease in nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPx4), and xCT cystine–glutamate antiporter (the main component is SLC7A11) are involved in atorvastatin-induced muscular cell ferroptosis and damage. The downregulation of GPx4 in mitochondria-mediated ferroptosis signaling may be the core of it. In conclusion, our findings explore an innovative underlying pathophysiological mechanism of atorvastatin-induced myopathy and highlight that targeting ferroptosis serves as a protective strategy for clinical application.

The Role of Ferroptosis in the Treatment and Drug Resistance of Hepatocellular Carcinoma

Cell death is a fundamental feature of multicellular organisms’ development and a key driver of degenerative diseases. Ferroptosis is a new regulatory cell death mediated by iron-dependent lipid peroxidation, which is different from apoptosis and necrosis in morphology, pathophysiology and mechanism. Recent studies have found that ferroptosis is involved in the development of many diseases including hepatocellular carcinoma (HCC). As further research progresses, specific mechanisms of ferroptosis in HCC are being revealed. In this review, we summarize these recent advances about the treatment of drug-resistance in HCC and the latest ferroptosis-related treatment for HCC.

The Role of Ferroptosis Signature in Overall Survival and Chemotherapy of Pancreatic Adenocarcinoma

Studies have shown that ferroptosis, an iron-dependent regulated cell death, is related to prognosis and chemotherapy, but the role of ferroptosis in pancreatic adenocarcinoma (PAAD) is still unclear. We aimed at constructing a ferroptosis-related gene (FRGs) model to predict the PAAD patients' overall survival (OS) and at exploring their values in chemotherapy. We downloaded the mRNA-sequencing data and corresponding clinical data of patients with PAAD from The Cancer Genome Atlas. Lasso-penalized Cox regression analysis was utilized to construct a prognostic risk model, including spermidine/spermine N1-acetyltransferase 1 (SAT1), SAT2, TFRC, SLC39A8, MAP1LC3A, ALOX15, and PROM2. Receiver operating characteristic curves were used to evaluate the prognostic model. International Cancer Genome Consortium cohorts were used to validate this model. Then, we used Genomics of Drug Sensitivity in Cancer and Gene Expression Omnibus databases to analyze the correlation between FRGs and drug sensitivity. Notably, SAT1 showed significant influence in cisplatin and gemcitabine resistance. Finally, in vitro experiments demonstrated that the combination of gemcitabine and cisplatin could induce ferroptosis in AsPC1 cells, probably through elevated SAT1 expression. Taken together, Our 7-gene signature has significant values in predicting the PAAD patients' OS, and it may help inform the clinical treatment of PAAD.

Nuclear receptors in renal health and disease

As a major social and economic burden for the healthcare system, kidney diseases contribute to the constant increase of worldwide deaths. A deeper understanding of the underlying mechanisms governing the etiology, development and progression of kidney diseases may help to identify potential therapeutic targets. As a superfamily of ligand-dependent transcription factors, nuclear receptors (NRs) are critical for the maintenance of normal renal function and their dysfunction is associated with a variety of kidney diseases. Increasing evidence suggests that ligands for NRs protect patients from renal ischemia/reperfusion (I/R) injury, drug-induced acute kidney injury (AKI), diabetic nephropathy (DN), renal fibrosis and kidney cancers. In the past decade, some breakthroughs have been made for the translation of NR ligands into clinical use. This review summarizes the current understanding of several important NRs in renal physiology and pathophysiology and discusses recent findings and applications of NR ligands in the management of kidney diseases.

Eriodictyol ameliorates cognitive dysfunction in APP/PS1 mice by inhibiting ferroptosis via vitamin D receptor-mediated Nrf2 activation

Background

Alzheimer’s disease (AD) is the most common type of neurodegenerative disease in the contemporary era, and it is still clinically incurable. Eriodictyol, a natural flavonoid compound that is mainly present in citrus fruits and some Chinese herbal medicines, has been reported to exert anti-inflammatory, antioxidant, anticancer and neuroprotective effects. However, few studies have examined the anti-AD effect and molecular mechanism of eriodictyol.

Methods

APP/PS1 mice were treated with eriodictyol and the cognitive function of mice was assessed using behavioral tests. The level of amyloid-β (Aβ) aggregation and hyperphosphorylation of Tau in the mouse brain were detected by preforming a histological analysis and Western blotting. HT-22 cells induced by amyloid-β peptide (1–42) (Aβ_1–42) oligomers were treated with eriodictyol, after which cell viability was determined and the production of p-Tau was tested using Western blotting. Then, the characteristics of ferroptosis, including iron aggregation, lipid peroxidation and the expression of glutathione peroxidase type 4 (GPX4), were determined both in vivo and in vitro using Fe straining, Western blotting and qPCR assays. Additionally, the expression level of vitamin D receptor (VDR) and the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway were tested using Western blotting and qPCR assays. Afterward, HT-22 cells with VDR knockout were used to explore the potential mechanisms, and the relationship between VDR and Nrf2 was further assessed by performing a coimmunoprecipitation assay and bioinformatics analysis.

Results

Eriodictyol obviously ameliorated cognitive deficits in APP/PS1 mice, and suppressed Aβ aggregation and Tau phosphorylation in the brains of APP/PS1 mice. Moreover, eriodictyol inhibited Tau hyperphosphorylation and neurotoxicity in HT-22 cells induced by Aβ_1–42 oligomer. Furthermore, eriodictyol exerted an antiferroptosis effect both in vivo and in vitro, and its mechanism may be associated with the activation of the Nrf2/HO-1 signaling pathway. Additionally, further experiments explained that the activation of Nrf2/HO-1 signaling pathway by eriodictyol treatment mediated by VDR.

Conclusions

Eriodictyol alleviated memory impairment and AD-like pathological changes by activating the Nrf2/HO-1 signaling pathway through a mechanism mediated by VDR, which provides a new possibility for the treatment of AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00442-3.

Polydatin Attenuates Cisplatin-Induced Acute Kidney Injury by Inhibiting Ferroptosis

Cisplatin is widely used in the treatment of solid tumors, but its application is greatly limited due to its nephrotoxicity; thus, there is still no effective medicine for the treatment of cisplatin-induced acute kidney injury (Cis-AKI). We previously identified that polydatin (PD) exerts nephroprotective effects by antioxidative stress in AKI models. Recent evidence suggests that oxidative stress-induced molecular events overlap with the process of ferroptosis and that there are common molecular targets, such as glutathione (GSH) depletion and lipid peroxidation. Nevertheless, whether the nephroprotective effect of PD is related to anti-ferroptosis remains unclear. In this study, the inhibitory effect of PD on ferroptosis was observed in both cisplatin-treated HK-2 cells (20 μM) in vitro and a Cis-AKI mouse model (20 mg/kg, intraperitoneally) in vivo, characterized by the reversion of excessive intracellular free iron accumulation and reactive oxygen species (ROS) generation, a decrease in malondialdehyde (MDA) content and GSH depletion, and an increase in glutathione peroxidase-4 (GPx4) activity. Remarkably, PD dose-dependently alleviated cell death induced by the system Xc⁻ inhibitor erastin (10 μM), and the effect of the 40 μM dose of PD was more obvious than that of ferrostatin-1 (1 μM) and deferoxamine (DFO, 100 μM), classical ferroptosis inhibitors. Our results provide insight into nephroprotection with PD in Cis-AKI by inhibiting ferroptosis via maintenance of the system Xc⁻-GSH-GPx4 axis and iron metabolism.

Abnormal Iron and Lipid Metabolism Mediated Ferroptosis in Kidney Diseases and Its Therapeutic Potential

Ferroptosis is a newly identified form of regulated cell death driven by iron-dependent phospholipid peroxidation and oxidative stress. Ferroptosis has distinct biological and morphology characteristics, such as shrunken mitochondria when compared to other known regulated cell deaths. The regulation of ferroptosis includes different molecular mechanisms and multiple cellular metabolic pathways, including glutathione/glutathione peroxidase 4(GPX4) signaling pathways, which are involved in the amino acid metabolism and the activation of GPX4; iron metabolic signaling pathways, which are involved in the regulation of iron import/export and the storage/release of intracellular iron through iron-regulatory proteins (IRPs), and lipid metabolic signaling pathways, which are involved in the metabolism of unsaturated fatty acids in cell membranes. Ferroptosis plays an essential role in the pathology of various kidneys diseases, including acute kidney injury (AKI), chronic kidney disease (CKD), autosomal dominant polycystic kidney disease (ADPKD), and renal cell carcinoma (RCC). Targeting ferroptosis with its inducers/initiators and inhibitors can modulate the progression of kidney diseases in animal models. In this review, we discuss the characteristics of ferroptosis and the ferroptosis-based mechanisms, highlighting the potential role of the main ferroptosis-associated metabolic pathways in the treatment and prevention of various kidney diseases.

ADAMTS-13-regulated nuclear factor E2-related factor 2 signaling inhibits ferroptosis to ameliorate cisplatin-induced acute kidney injuy

ADAMTS-13 plays an important role in acute kidney injury (AKI), but the mechanism of cisplatin (CP) induced AKI remains unclear. Ferroptosis is increased in CP-induced AKI, and ADAMTS13 levels are associated with ferritin expression. In this article, we will explore the relationship between the three. After CP induction, mice were given 0.1 and 0.3 nmol/kg ADAMTS-13, and then serum creatinine (Scr) and blood urea nitrogen (BUN) were detected by the kits. The pathological changes of renal tissue were observed by staining with HE and PAS staining, and Western blot detected the expressions of KIM1 and NGAL in renal tissu. Perl's staining detected iron deposition in renal tissues, the kits detected iron levels, and western blot detected the expression of ferroptosis related proteins. Then the mechanism was further explored by adding ferroptosis inhibitors Ferrostatin 1 (Fer-1) and iron supplements Fe. The expression of Nrf2 pathway related proteins were detected by Western blot. We found that ADAMTS13 alleviated CP-induced ferroptosis in AKI mice with renal function impairment and tubular damage. Fer-1partially reversed CP-induced AKI, and Fe exacerbated this effect. ADAMTS13 alleviated CP-induced inflammatory response and oxidative stress in AKI mice, during which the Nrf2 signaling pathway was abnormal. Overall, ADAMTS-13-regulated Nrf2 signaling inhibits ferroptosis to ameliorate CP-induced AKI.

Insight into the Double-Edged Role of Ferroptosis in Disease

Ferroptosis, a newly described type of iron-dependent programmed cell death that is distinct from apoptosis, necroptosis, and other types of cell death, is involved in lipid peroxidation (LP), reactive oxygen species (ROS) production, and mitochondrial dysfunction. Accumulating evidence has highlighted vital roles for ferroptosis in multiple diseases, including acute kidney injury, cancer, hepatic fibrosis, Parkinson's disease, and Alzheimer's disease. Therefore, ferroptosis has become one of the research hotspots for disease treatment and attracted extensive attention in recent years. This review mainly summarizes the relationship between ferroptosis and various diseases classified by the system, including the urinary system, digestive system, respiratory system, nervous system. In addition, the role and molecular mechanism of multiple inhibitors and inducers for ferroptosis are further elucidated. A deeper understanding of the relationship between ferroptosis and multiple diseases may provide new strategies for researching diseases and drug development based on ferroptosis.

Isoliquiritigenin attenuates septic acute kidney injury by regulating ferritinophagy-mediated ferroptosis

Defined differently from apoptosis, necrosis, and autophagy, ferroptosis has been implicated in acute kidney injury (AKI) such as ischemia-reperfusion injury induced AKI, folic acid caused AKI and cisplatin induced AKI. However, whether ferroptosis is involved in LPS induced AKI could be remaining unclear and there is still a lack of therapies associated with ferroptosis in LPS induced AKI without side effects. This study aimed to elucidate the role of isoliquiritigenin (ISL) in ferroptosis of LPS-induced AKI. We used LPS to induce renal tubular injury, followed by treatment with ISL both in vitro and in vivo. Human renal tubular HK2 cells were pretreated with 50 μM or 100 μM ISL for 5 h before stimulation with 2 μg/mL LPS. Mice were administered a single dose of either 50 mg/kg ISL orally or 5 mg/kg ferroptosis inhibitor ferrostatin-1 intraperitoneally before 10 mg/kg LPS injection. We found that LPS could induce mitochondria injury of renal tubular presented as the shape of mitochondria appeared smaller than normal with increased membrane density and are faction or destruction of mitochondrial crista through scanning electron microscope. Ferrostatin-1 significantly protected mice against renal dysfunction and renal tubular damage in LPS-induced AKI. ISL inhibited Fe²⁺ and lipid peroxidation accumulation in LPS-stimulated HK2 cells. It also increased the expression of GPX4 and xCT, reduced the expression of HMGB1 and NCOA4 then attenuated mitochondria injury in renal tubular following LPS stimulation. These results indicated the potential role of ISL against ferritinophagy-mediated ferroptosis in renal tubular following LPS stimulation.

Downregulation of Cx43 reduces cisplatin-induced acute renal injury by inhibiting ferroptosis

Ferroptosis is one of the main mechanisms involved in different forms of acute kidney injury (AKI), including cisplatin-induced AKI. However, it is not clear whether Cx43 has a regulatory effect on ferroptosis caused by cisplatin. In this study, we investigate the regulatory effects of Cx43 on cisplatin-induced ferroptosis and its mechanism. In vivo and in vitro studies showed that the expression level of Cx43 was significantly upregulated in the cisplatin-induced kidney injury model. In HK2 cells, cisplatin significantly induced ferroptosis. Adding shRNA-Cx43 and gap27 to the HK2 cells downregulated the expression of Cx43 and blocked the effects of cisplatin, resulting in a significantly improved survival rate of HK2 cells. Our primary data suggested that downregulating Cx43 not only inhibits ferroptosis, but also inhibits apoptosis. Through mechanistic studies, we confirmed that downregulating the expression of Cx43 by increasing SLC7A11 can increase the GSH content to inhibit cisplatin-induced ferroptosis. In vivo experiments showed that downregulation of Cx43 expression by gap27 reduced AKI in the animal model by inhibiting cisplatin-induced ferroptosis. Therefore, our results indicated that downregulation of Cx43 can inhibit ferroptosis by restoring the level of SLC7A11 in the system x_c‾ transporter and alleviate cisplatin-induced AKI.

Ferroptosis in cancer therapeutics: a materials chemistry perspective

Ferroptosis, distinct from apoptosis, is a regulated form of cell death caused by lipid peroxidation that has attracted extensive research interest since it was first defined in 2012. Over the past five years, an increasing number of studies have revealed the close relationship between ferroptosis and materials chemistry, in particular nanobiotechnology, and have concluded that nanotechnology-triggered ferroptosis is an efficient and promising antitumor strategy that provides an alternative therapeutic approach, especially for apoptosis-resistant tumors. In this review, we summarize recent advances in ferroptosis-induced tumor therapy at the intersection of materials chemistry, redox biology, and tumor biology. The biological features and molecular mechanisms of ferroptosis are first outlined, followed by a summary of the feasible strategies to induce ferroptosis using nanomaterials and the applications of ferroptosis in combined tumor therapy. Finally, the existing challenges and future development directions in this emerging field are discussed, with the aim of promoting the progress of ferroptosis-based oncotherapy in materials science and nanoscience and enriching the antitumor arsenal.

Nuclear Receptors and Transcription Factors in Obesity-Related Kidney Disease

Both obesity and chronic kidney disease are increasingly common causes of morbidity and mortality worldwide. Although obesity often co-exists with diabetes and hypertension, it has become clear over the past several decades that obesity is an independent cause of chronic kidney disease, termed obesity-related glomerulopathy. This review defines the attributes of obesity-related glomerulopathy and describes potential pharmacologic interventions. Interventions discussed include peroxisome proliferator-activated receptors, the farnesoid X receptor, the Takeda G-protein-coupled receptor 5, and the vitamin D receptor.

A Novel Ferroptosis-Related 4-Gene Prognostic Signature for Cholangiocarcinoma and Photodynamic Therapy

Cholangiocarcinoma is the second most common malignant tumor in the hepatobiliary system. Compared with data on hepatocellular carcinoma, fewer public data and prognostic-related studies on cholangiocarcinoma are available, and effective prognostic prediction methods for cholangiocarcinoma are lacking. In recent years, ferroptosis has become an important subject of tumor research. Some studies have indicated that ferroptosis plays an important role in hepatobiliary cancers. However, the prediction of the prognostic effect of ferroptosis in patients with cholangiocarcinoma has not been reported. In addition, many reports have described the ability of photodynamic therapy (PDT), a potential therapy for cholangiocarcinoma, to regulate ferroptosis by generating reactive oxygen species (ROS). By constructing ferroptosis scores, the prognoses of patients with cholangiocarcinoma can be effectively predicted, and potential gene targets can be discovered to further enhance the efficacy of PDT. In this study, gene expression profiles and clinical information (TCGA, E-MTAB-6389, and GSE107943) of patients with cholangiocarcinoma were collected and divided into training sets and validation sets. Then, a model of the ferroptosis gene signature was constructed using least absolute shrinkage and selection operator (LASSO)-penalized Cox regression analysis. Furthermore, through the analysis of RNA-seq data after PDT treatment of cholangiocarcinoma, PDT-sensitive genes were obtained and verified by immunohistochemistry staining and Western blot. The results of this study provide new insight for predicting the prognosis of cholangiocarcinoma and screening target genes that enhance the efficacy of PDT.

Long non-coding RNA MEG3 promotes cisplatin-induced nephrotoxicity through regulating AKT/TSC/mTOR-mediated autophagy

Cis-Diamminedichloroplatinum (II) (DDP)-induced nephrotoxicity (DDPIN) may cause irreversible renal injury associated with high morbidity and mortality. Current standard therapies have not achieved satisfactory clinical outcomes due to unclear molecular and cellular mechanisms. Therefore, exploring potential therapies on DDPIN represents an urgent medical need. Present study characterized the role of lncRNA maternally expressed gene 3 (lnc-MEG3) in the pathogenesis of DDPIN. In both in vitro and in murine models of DDP-induced nephrotoxicity, lnc-MEG3 exacerbated DDPIN by negatively regulating miRNA-126 subsequently causing a decreased AKT/TSC/mTOR-mediated autophagy. By silencing lnc-MEG3 or incorporating miRNA-126 mimetics, the proliferation and migration of DDP-treated cells were restored. In vivo, we identified Paeonol to alleviate DDPIN by the inhibition of lnc-MEG3. Taken together, lnc-MEG3 represents a novel therapeutic target for DDPIN and Paeonol may serve as a promising treatment by inhibiting lnc-MEG3 and its related signaling pathways.

1,25(OH)2D3 Inhibited Ferroptosis in Zebrafish Liver Cells (ZFL) by Regulating Keap1-Nrf2-GPx4 and NF-κB-hepcidin Axis

Ferroptosis is a kind of iron-dependent programed cell death. Vitamin D has been shown to be an antioxidant and a regulator of iron metabolism, but the relationship between vitamin D and ferroptosis is poorly studied in fish. This study used zebrafish liver cells (ZFL) to establish a ferroptosis model to explore the effect of 1,25(OH)2D3 on cell ferroptosis and its mechanism of action. The results showed that different incubation patterns of 1,25(OH)2D3 improved the survival rate of ZFL, mitigated mitochondrial damage, enhanced total glutathione peroxidase (GPx) activity, and reduced intracellular reactive oxygen species (ROS), lipid peroxidation (LPO), and malondialdehyde (MDA), as well as iron ion levels, with the best effect at 200 pM 1,25(OH)2D3 preincubation for 72 h. Preincubation of ZFL at 200 pM 1,25(OH)2D3 for 72 h downgraded keap1 and ptgs2 gene expression, increased nrf2, ho-1, fth1, gpx4a,b expression, and lowered the expression of the nf-κb p65,il-6,il-1β gene, thus reducing the expression of hamp1. The above results indicate that different incubation patterns of 1,25(OH)2D3 have protective effects on ferroptosis of ZFL induced by ferroptosis activator RSL3 and 1,25(OH)2D3 can inhibit ferroptosis of ZFL by regulating Keap1-Nrf2-GPx4 and NF-κB-hepcidin axis.

A-Lipoic Acid Alleviates Folic Acid-Induced Renal Damage Through Inhibition of Ferroptosis

Folic acid (FA)-induced acute kidney injury (AKI) is characterized by the disturbance of redox homeostasis, resulting in massive tubular necrosis and inflammation. Α-lipoic acid (LA), as an antioxidant, has been reported to play an important role in renal protection, but the underlying mechanism remains poorly explored. The aim of this study is to investigate the protective effect of LA on FA-induced renal damage. Our findings showed that LA could ameliorate renal dysfunction and histopathologic damage induced by FA overdose injection. Moreover, FA injection induced severe inflammation, indicated by increased release of pro-inflammatory cytokines tumor necrosis factor (TNF)-α and IL-1β, as well as infiltration of macrophage, which can be alleviated by LA supplementation. In addition, LA not only reduced the cellular iron overload by upregulating the expressions of Ferritin and ferroportin (FPN), but also mitigated reactive oxygen species (ROS) accumulation and lipid peroxidation by increasing the levels of antioxidant glutathione (GSH) and glutathione peroxidase-4 (GPX4). More importantly, we found that LA supplementation could reduce the number of Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive tubular cells caused by FA, indicating that the tubular cell death mediated by ferroptosis may be inhibited. Further study demonstrated that LA supplementation could reverse the decreased expression of cystine/glutamate antiporter xCT (SLC7A11), which mediated GSH synthesis. What is more, mechanistic study indicated that p53 activation was involved in the inhibitory effect of SLC7A11 induced by FA administration, which could be suppressed by LA supplementation. Taken together, our findings indicated that LA played the protective effect on FA-induced renal damage mainly by inhibiting ferroptosis.

Role of ferroptosis in cisplatin-induced acute nephrotoxicity in mice

BACKGROUND

Cisplatin is widely used as an antitumor drug for the treatment of solid tumors. However, its use has been limited owing to nephrotoxicity, a major side effect. The mechanism of cisplatin-induced nephrotoxicity (CIN) has long been investigated in order to develop preventive/therapeutic drugs. Ferroptosis is a newly identified form of non-apoptotic regulated cell death induced by iron-mediated lipid peroxidation and is involved in the pathophysiology of various diseases. In this study, we examined the role of ferroptosis in CIN.

METHODS

We evaluated the role of ferroptosis in CIN by in vivo experiments in a mouse model.

RESULTS

Cisplatin increased the protein expressions of transferrin receptor-1 and ferritin, and iron content in the kidney of mice. In addition, treatment with cisplatin augmented renal ferrous iron and hydroxyl radical levels with co-localization. Mice administered cisplatin demonstrated kidney injury, with renal dysfunction and increased inflammatory cytokine expression; these changes were ameliorated by Ferrostatin-1 (Fer-1), an inhibitor of ferroptosis. The expression of the ferroptosis markers, COX2 and 4-hydroxynonenal (4-HNE), increased with cisplatin administration, and decreased with the administration of Fer-1. By contrast, cisplatin-induced apoptosis and necroptosis were inhibited by treatment with Fer-1. Moreover, deferoxamine, an iron chelator, also inhibited CIN, with a decrease in the expression of COX-2 and 4-HNE.

CONCLUSION

Ferroptosis is involved in the pathogenesis of CIN and might be used as a new preventive target for CIN.

Cell Ferroptosis: New Mechanism and New Hope for Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a leading cause of inherited retinal degeneration, with more than 60 gene mutations. Despite the genetic heterogenicity, photoreceptor cell damage remains the hallmark of RP pathology. As a result, RP patients usually suffer from reduced night vision, loss of peripheral vision, decreased visual acuity, and impaired color perception. Although photoreceptor cell death is the primary outcome of RP, the underlying mechanisms are not completely elucidated. Ferroptosis is a novel programmed cell death, with characteristic iron overload and lipid peroxidation. Recent studies, using in vitro and in vivo RP models, discovered the involvement of ferroptosis-associated cell death, suggesting a possible new mechanism for RP pathogenesis. In this review, we discuss the association between ferroptosis and photoreceptor cell damage, and its implication in the pathogenesis of RP. We propose that ferroptotic cell death not only opens up a new research area in RP, but may also serve as a novel therapeutic target for RP.

Mitochondrial Redox Signaling and Oxidative Stress in Kidney Diseases

Mitochondria are essential organelles in physiology and kidney diseases, because they produce cellular energy required to perform their function. During mitochondrial metabolism, reactive oxygen species (ROS) are produced. ROS function as secondary messengers, inducing redox-sensitive post-translational modifications (PTM) in proteins and activating or deactivating different cell signaling pathways. However, in kidney diseases, ROS overproduction causes oxidative stress (OS), inducing mitochondrial dysfunction and altering its metabolism and dynamics. The latter processes are closely related to changes in the cell redox-sensitive signaling pathways, causing inflammation and apoptosis cell death. Although mitochondrial metabolism, ROS production, and OS have been studied in kidney diseases, the role of redox signaling pathways in mitochondria has not been addressed. This review focuses on altering the metabolism and dynamics of mitochondria through the dysregulation of redox-sensitive signaling pathways in kidney diseases.

Verification of ferroptosis and pyroptosis and identification of PTGS2 as the hub gene in human coronary artery atherosclerosis

Ferroptosis and pyroptosis have not been fully studied in atherosclerosis. We aimed to investigate the expression of ferroptosis-related and pyroptosis-related proteins in human coronary arteries and analyse correlation with severity of atherosclerosis and clarify the interactions between proteins and possible mechanisms of atherosclerosis. 40 human coronary artery specimens were employed. The atherosclerotic lesions were characterized by Haematoxylin and Eosin (H&E) staining. The expression of prostaglandin-endoperoxide synthase 2 (PTGS2), anti-acyl-CoA synthetase long-chain family member 4 (ACSL4), glutathione peroxidase 4 (GPX4), caspase-1, and NOD-like receptor protein 3 (NLRP3) were analysed by immunohistochemical assay. Correlations between expression of proteins and severity of atherosclerosis were assessed using Spearman correlation analysis. Bioinformatic and coexpression analyses were performed to study the possible pathways and interactions. In the present study, PTGS2, ACSL4, caspase-1, and NLRP3, were upregulated, while GPX4 was downregulated in the advanced stages of atherosclerosis. The severity of atherosclerosis was positively associated with the expression of PTGS2, ACSL4, caspase-1, and NLRP3 and negatively associated with the expression of GPX4. Biological processes of lipid metabolism and inflammation and C-type lectin receptor signaling pathway were enriched. The five proteins interacted with each other directly or indirectly and PTGS2 might be the hub gene of atherosclerosis. Ferroptosis and pyroptosis may regulate the occurrence and development of atherosclerosis. These findings may shed light on new ideas and potential targets for the prevention and treatment of coronary artery atherosclerosis and the proteins may be used as biomarkers for the severity of atherosclerosis.

Autophagy-dependent ferroptosis contributes to cisplatin-induced hearing loss

Cisplatin-induced hearing loss is a common side effect of cisplatin chemotherapy, for which clinical therapy remains unavailable. Apoptosis of hair cells is considered the primary cause of cisplatin-induced ototoxicity; however, inhibiting apoptosis can only partially restore cisplatin-induced hearing loss. Therefore, auditory cell death caused by cisplatin damage requires further study. Ferroptosis, a novel form of regulated cell death, has been shown to play a role in the mechanism of cisplatin toxicity. In this study, we observed proferroptotic alterations (lipid peroxidation and impaired antioxidant capacity) in the cochleae of C57BL/6 mice after cisplatin damage, verifying the induction of ferroptosis. Using the HEI-OC1 cell line, we observed that cisplatin induced proferroptotic alterations and activated ferritinophagy (specific autophagy pathway). Employing chloroquine, we confirmed that the blockage of autophagy remarkably alleviated cisplatin-induced ferroptosis in HEI-OC1 cells; therefore, the induction of ferroptosis in cisplatin-treated auditory cells was dependent on the activation of autophagy. In addition, the ferroptosis inhibitor ferrostatin-1 and iron chelator deferoxamine significantly attenuated cisplatin-induced cytotoxicity in HEI-OC1 cells and cochlear explants. Moreover, pharmacologically inhibiting ferroptosis using ferrostatin-1 significantly decreased the auditory cell loss and, notably, attenuated hearing loss in C57BL/6 mice after cisplatin damage. Collectively, these findings indicate that autophagy-dependent ferroptosis plays an integrated role in the mechanism of cisplatin-induced hearing loss.