Nobiletin Alleviates Ferroptosis-Associated Renal Injury, Inflammation, and Fibrosis in a Unilateral Ureteral Obstruction Mouse Model

Crocin-I mitigates diquat-induced pulmonary fibrosis via activation of the SIRT3/FOXO3a pathway

BACKGROUND

Diquat (DQ) is a potent herbicide known for its significant toxicity to humans and animals, often resulting in severe pulmonary fibrosis, a serious and potentially life-threatening complication of DQ poisoning. Currently, there are no effective pharmacological treatments for this condition. Crocin-I, a primary bioactive component derived from crocin, possesses notable antioxidant and anti-inflammatory properties; however, its potential to inhibit DQ-induced pulmonary fibrosis has not been fully explored. This study aimed to elucidate the underlying mechanisms and therapeutic effects of crocin-I on DQ-induced pulmonary fibrosis.

METHODS

C57BL/6 mice exposed to DQ served as a model of pulmonary fibrosis. Pathological characteristics were assessed with hematoxylin and eosin staining, and collagen deposition was measured using Masson's trichrome staining. The expression of epithelial-mesenchymal transition markers was measured using Western blotting and quantitative real-time polymerase chain reaction. Additionally, proteins associated with the SIRT3/FOXO3a signaling pathway were analyzed through Western blotting and quantitative real-time polymerase chain reaction.

RESULTS

Administration of crocin-I at a dosage of 40 mg/kg significantly reduced pulmonary fibrosis, as indicated by decreased collagen deposition. Furthermore, treatment with crocin-I enhanced the expression of SIRT3 and FOXO3a, leading to altered levels of EMT-associated markers, specifically decreased E-cadherin and increased vimentin and α-SMA.

CONCLUSION

These findings suggest that crocin-I activates the SIRT3/FOXO3a pathway and alleviates DQ-induced pulmonary fibrosis, highlighting its potential as a therapeutic agent for lung injury and paving the way for further research into its clinical applications.

Renal fibrosis progression following partial unilateral ureteral obstruction: mechanisms and therapeutic insights

Ureteral obstruction, a common clinical condition, is associated with various renal disorders affecting all age groups and can lead to permanent renal damage. In Partial unilateral ureteral obstruction (PUUO), increased ureteral pressure, and decreased glomerular filtration rate (GFR) in the affected kidney cause cellular and molecular abnormalities, which ultimately lead to renal fibrosis if untreated. While removing the obstruction (RUUO) is essential to prevent long-term damage, additional therapeutic approaches may be necessary to fully restore kidney function. The PUUO model is used to induce renal fibrosis, primarily characterized by tubular injury resulting from obstructed urine flow. PUUO in rodents can simulate human chronic obstructive nephropathy at an accelerated rate. Although alleviating the obstruction can reduce immediate symptoms, it is often insufficient to reverse established fibrosis, emphasizing the need for adjunctive therapies. The renal response to RUUO depends on factors like the obstruction's duration and severity, as well as the contralateral kidney's functional state.

Ferroptosis in organ fibrosis: Mechanisms and therapeutic approaches

Ferroptosis, a form of iron-dependent regulated cell death, has emerged as a critical mechanism in the pathogenesis of organ fibrosis. This review aims to provide an overview of the molecular mechanisms underlying ferroptosis and its contribution to fibrosis in various organs, including the liver, lung, heart, and kidneys. We explore how dysregulated iron metabolism, lipid peroxidation, and oxidative stress contribute to ferroptosis and subsequent tissue damage, promoting the progression of fibrosis. In addition, we highlight the complex interplay between ferroptosis and other cellular processes such as apoptosis, necrosis, and inflammation in the fibrotic microenvironment. Furthermore, this review discusses current therapeutic strategies targeting ferroptosis, including iron chelation, antioxidants, and modulators of lipid peroxidation. We also examine ongoing clinical and preclinical studies aimed at translating these findings into viable treatments for fibrotic diseases. Understanding the role of ferroptosis in organ fibrosis offers novel therapeutic opportunities, with the potential to mitigate disease progression and improve patient outcomes.

Fucoxanthin Ameliorates Kidney Injury by CCl4-Induced via Inhibiting Oxidative Stress, Suppressing Ferroptosis, and Modulating Gut Microbiota

Chemical-induced kidney injury represents a substantial health risk, with ferroptosis, a type of cell death caused by lipid peroxidation, playing a role in numerous kidney ailments. Fucoxanthin (Fx), a natural carotenoid known for its antioxidant capabilities, has shown promise in alleviating renal injury, but its exact mechanisms are yet to be fully understood. Carbon tetrachloride (CCl4) is recognized as a powerful nephrotoxic substance, and this study explores the therapeutic effects of Fx on oxidative stress, ferroptosis and intestinal microbiota in mouse kidneys subjected to CCl4 exposure. The mice were randomly assigned to control, model, colchicine groups (0.1 mg/kg/d), and Fx (50, 100 mg/kg/d) group and underwent related treatments for 4 weeks. Then, we evaluated their renal function, histological alterations in the kidneys, colon, and jejunum, and the levels of related proteins (i.e., Nrf2, GPX4, SLC7A11, HO-1, TFR1, NQO1, GCLM, FTL). Additionally, their gut microbiota was analyzed using 16S rRNA gene sequencing. The results showed that compared to the CCl4 group, Fx treatment led to lower serum creatinine and blood urea nitrogen levels, reduced malondialdehyde activity in kidneys and intestinal tissues, and increased activity of antioxidant enzymes. Fx also reduced dysbiosis and enhanced the diversity of intestinal flora. In summary, Fx reduced oxidative stress and ferroptosis and partially restored intestinal bacteria, thus improving CCl4-induced renal damage in mice. These results suggest Fx as a potential therapeutic option for kidney injuries related to oxidative stress. Further research is needed to clarify its precise mechanisms and potential clinical implications.

Protective Effects of Tormentic Acid on Unilateral Ureteral Obstruction-Induced Renal Injury, Inflammation, and Fibrosis: A Comprehensive Approach to Reducing Oxidative Stress, Apoptosis, and Ferroptosis

Chronic kidney disease (CKD) progresses through mechanisms involving inflammation, fibrosis, and oxidative stress, leading to the gradual structural and functional deterioration of the kidneys. Tormentic acid (TA), a triterpenoid compound with known anti-inflammatory and antioxidant properties, shows significant potential in counteracting these pathological processes. This study explored the protective role of TA in a unilateral ureteral obstruction (UUO)-induced CKD model. Mice received TA through intraperitoneal injections at a dosage of 5 mg/kg per day for 8 consecutive days, commencing a day before the UUO procedure. The TA treatment significantly improved both structural and functional kidney injury. It suppressed cytokine expression and reduced immune cell infiltration, inhibited the activation of the mitogen-activated protein kinase cascade, and alleviated endoplasmic reticulum stress. Moreover, TA displayed potent anti-fibrotic effects by reversing epithelial-to-mesenchymal transition and inhibiting Smad2/3 activation, reducing extracellular matrix deposition. TA also mitigated oxidative stress by attenuating lipid peroxidation and boosting antioxidant defenses. Additionally, it inhibited apoptosis and ferroptosis by reducing oxidative stress and modulating key cell death markers. Collectively, these findings indicate that TA provides comprehensive renoprotection in the UUO model by effectively targeting inflammation, fibrosis, oxidative stress, and tubular cell death in CKD progression.

Deciphering ferroptosis in critical care: mechanisms, consequences, and therapeutic opportunities

Ischemia-reperfusion injuries (IRI) across various organs and tissues, along with sepsis, significantly contribute to the progression of critical illnesses. These conditions disrupt the balance of inflammatory mediators and signaling pathways, resulting in impaired physiological functions in human tissues and organs. Ferroptosis, a distinct form of programmed cell death, plays a pivotal role in regulating tissue damage and modulating inflammatory responses, thereby influencing the onset and progression of severe illnesses. Recent studies highlight that pharmacological agents targeting ferroptosis-related proteins can effectively mitigate oxidative stress caused by IRI in multiple organs, alleviating associated symptoms. This manuscript delves into the mechanisms and signaling pathways underlying ferroptosis, its role in critical illnesses, and its therapeutic potential in mitigating disease progression. We aim to offer a novel perspective for advancing clinical treatments for critical illnesses.

Metal-Dependent Cell Death in Renal Fibrosis: Now and in the Future

Renal fibrosis is a common final pathway underlying nearly almost all progressive kidney diseases. Metal ions are essential trace elements in organisms and are involved in important physiological activities. However, aberrations in intracellular metal ion metabolism may disrupt homeostasis, causing cell death and increasing susceptibility to various diseases. Accumulating evidence suggests a complex association between metal-dependent cell death and renal fibrosis. In this article, we provide a comprehensive overview of the specific molecular mechanisms of metal-dependent cell death and their crosstalk, up-to-date evidence supporting their role in renal fibrosis, therapeutic targeting strategies, and research needs, aiming to offer a rationale for future clinical treatment of renal fibrosis.

Screening of active components in Astragalus mongholicus Bunge and Panax notoginseng formula for anti-fibrosis in CKD: nobiletin inhibits Lgals1/PI3K/AKT signaling to improve renal fibrosis

The Astragalus mongholicus Bunge and Panax notoginseng formula (A&P) has been clinically shown to effectively slow down the progression of chronic kidney disease (CKD) and has demonstrated significant anti-fibrosis effects in experimental CKD model. However, the specific active ingredients and underlying mechanism are still unclear. The active ingredients of A&P were analyzed by Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-HR-MS). A mouse model of CKD was constructed by 5/6 nephrectomy. Renal function was assessed by creatinine and urea nitrogen. Real-time PCR and Western Blot were performed to detect the mRNA and protein changes in kidney and cells. An in vitro fibrotic cell model was constructed by TGF-β induction in TCMK-1 cells. The results showed that thirteen active ingredients of A&P were identified by UPLC-HR-MS, nine of which were identified by analysis with standards, among which the relative percentage of NOB was high. We found that NOB treatment significantly improved renal function, pathological damage and reduced the expression level of fibrotic factors in CKD mice. The results also demonstrated that Lgals1 was overexpressed in the interstitial kidney of CKD mice, and NOB treatment significantly reduced its expression level, while inhibiting PI3K and AKT phosphorylation. Interestingly, overexpression of Lgals1 significantly increased fibrosis in TCMK1 cells and upregulated the activity of PI3K and AKT, which were strongly inhibited by NOB treatment. NOB is one of the main active components of A&P. The molecular mechanism by which NOB ameliorates renal fibrosis in CKD may be through the inhibition of Lgals1/PI3K/AKT signaling pathway.

Phytochemical Compounds as Promising Therapeutics for Intestinal Fibrosis in Inflammatory Bowel Disease: A Critical Review

BACKGROUND/OBJECTIVE

Intestinal fibrosis, a prominent consequence of inflammatory bowel disease (IBD), presents considerable difficulty owing to the absence of licensed antifibrotic therapies. This review assesses the therapeutic potential of phytochemicals as alternate methods for controlling intestinal fibrosis. Phytochemicals, bioactive molecules originating from plants, exhibit potential antifibrotic, anti-inflammatory, and antioxidant activities, targeting pathways associated with inflammation and fibrosis. Compounds such as Asperuloside, Berberine, and olive phenols have demonstrated potential in preclinical models by regulating critical signaling pathways, including TGF-β/Smad and NFκB, which are integral to advancing fibrosis.

RESULTS

The main findings suggest that these phytochemicals significantly reduce fibrotic markers, collagen deposition, and inflammation in various experimental models of IBD. These phytochemicals may function as supplementary medicines to standard treatments, perhaps enhancing patient outcomes while mitigating the adverse effects of prolonged immunosuppressive usage. Nonetheless, additional clinical trials are necessary to validate their safety, effectiveness, and bioavailability in human subjects.

CONCLUSIONS

Therefore, investigating phytochemicals may lead to crucial advances in the formulation of innovative treatment approaches for fibrosis associated with IBD, offering a promising avenue for future therapeutic development.

Repair and regeneration: ferroptosis in the process of remodeling and fibrosis in impaired organs

As common clinical-pathological processes, wound healing and tissue remodelling following injury or stimulation are essential topics in medical research. Promoting the effective healing of prolonged wounds, improving tissue repair and regeneration, and preventing fibrosis are important and challenging issues in clinical practice. Ferroptosis, which is characterized by iron overload and lipid peroxidation, is a nontraditional form of regulated cell death. Emerging evidence indicates that dysregulated metabolic pathways and impaired iron homeostasis play important roles in various healing and regeneration processes via ferroptosis. Thus, we review the intrinsic mechanisms of tissue repair and remodeling via ferroptosis in different organs and systems under various conditions, including the inflammatory response in skin wounds, remodeling of joints and cartilage, and fibrosis in multiple organs. Additionally, we summarize the common underlying mechanisms, key molecules, and targeted drugs for ferroptosis in repair and regeneration. Finally, we discuss the potential of therapeutic agents, small molecules, and novel materials emerging for targeting ferroptosis to promote wound healing and tissue repair and attenuate fibrosis.

The significance of ferroptosis in renal diseases and its therapeutic potential

Kidney diseases are significant global public health concern, with increasing prevalence and substantial economic impact. Developing novel therapeutic approaches are essential for delaying disease progression and improving patient quality of life. Cell death signifying the termination of cellular life, could facilitate appropriate bodily development and internal homeostasis. Recently, regulated cell death (RCD) forms such as ferroptosis, characterized by iron-dependent lipid peroxidation, has garnered attention in diverse renal diseases and other pathological conditions. This review offers a comprehensive examination of ferroptosis, encompassing an analysis of the involvement of iron and lipid metabolism, the System Xc - /glutathione/glutathione peroxidase 4 signaling, and additional associated pathways. Meanwhile, the review delves into the potential of targeting ferroptosis as a therapeutic approach in the management of acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy, and renal tumors. Furthermore, it emphasizes the significance of ferroptosis in the transition from AKI to CKD and further accentuates the potential for repurposing drug and utilizing traditional medicine in targeting ferroptosis-related pathways for clinical applications. The integrated review provides valuable insights into the role of ferroptosis in kidney diseases and highlights the potential for targeting ferroptosis as a therapeutic strategy.

Wogonin ameliorates ER stress-associated inflammatory response, apoptotic death and renal fibrosis in a unilateral ureteral obstruction mouse model

Wogonin, a vital bioactive compound extracted from the medicinal plant, Scutellaria baicalensis, has been wildly used for its potential in mitigating the progression of chronic diseases. Chronic kidney disease (CKD) represents a significant global health challenge due to its high prevalence, morbidity and mortality rates, and associated complications. This study aimed to assess the potential of wogonin in attenuating renal fibrosis and to elucidate the underlying molecular mechanisms using a unilateral ureteral obstruction (UUO) mouse model as a CKD mimic. Male mice, 8 weeks old, underwent orally administrated of either 50 mg/kg/day of wogonin or positive control of 5 mg/kg/day candesartan following UUO surgery. NRK52E cells were exposed to tumor growth factors-beta (TGF-β) to evaluate the anti-fibrotic effects of wogonin. The results demonstrated that wogonin treatment effectively attenuated TGF-β-induced fibrosis markers in NRK-52E cells. Additionally, administration of wogonin significantly improved histopathological alterations and downregulated the expression of pro-fibrotic factors (Fibronectin, α-smooth muscle actin, Collagen IV, E-cadherin, and TGF-β), oxidative stress markers (Catalase, superoxide dismutase 2, NADPH oxidase 4, and thioredoxin reductase 1), inflammatory molecules (Cyclooxygenase-2 and TNF-α), and the infiltration of neutrophils and macrophages in UUO mice. Furthermore, wogonin treatment mitigated endoplasmic reticulum (ER) stress-associated molecular markers (GRP78, GRP94, ATF4, CHOP, and the caspase cascade) and suppressed apoptosis. The findings indicate that wogonin treatment ameliorates key fibrotic aspects of CKD by attenuating ER stress-related apoptosis, inflammation, and oxidative stress, suggesting its potential as a future therapeutic target.

A Deep Insight into Ferroptosis in Renal Disease: Facts and Perspectives

Background

Ferroptosis, a newly recognized form of programmed cell death, is distinguished by its reliance on reactive oxygen species and iron-mediated lipid peroxidation, setting it apart from established types like apoptosis, cell necrosis, and autophagy. Recent studies suggest its role in exacerbating or mitigating diseases by influencing metabolic and signaling pathways in conditions such as tumors and ischemic organ damage. Evidence also links ferroptosis to various kidney diseases, prompting a review of its research status and potential breakthroughs in understanding and treating these conditions.

Summary

In acute kidney disease (AKI), ferroptosis has been confirmed in animal kidneys after being induced by various factors such as renal ischemia-reperfusion and cisplatin, and glutathione peroxidase 4 (GPX4) is linked with AKI. Ferroptosis is associated with renal fibrosis in chronic kidney disease (CKD), TGF-β1 being crucial in this regard. In diabetic nephropathy (DN), high SLC7A11 and low nuclear receptor coactivator 4 (NCOA4) expressions are linked to disease progression. For polycystic kidney disease (PKD), ferroptosis promotes the disease by regulating ferroptosis in kidney tissue. Renal cell carcinoma (RCC) and lupus nephritis (LN) also have links to ferroptosis, with mtDNA and iron accumulation causing RCC and oxidative stress causing LN.

Key Messages

Ferroptosis is a newly identified form of programmed cell death that is associated with various diseases. It targets metabolic and signaling pathways and has been linked to kidney diseases such as AKI, CKD, PKD, DN, LN, and clear cell RCC. Understanding its role in these diseases could lead to breakthroughs in their pathogenesis, etiology, and treatment.

Altenusin, a fungal metabolite, alleviates TGF-β1-induced EMT in renal proximal tubular cells and renal fibrosis in unilateral ureteral obstruction

Renal fibrosis is a pathological feature of chronic kidney disease (CKD), progressing toward end-stage kidney disease (ESKD). The aim of this study is to investigate the therapeutic potential of altenusin, a farnesoid X receptor (FXR) agonist derived from fungi, on renal fibrosis. The effect of altenusin was determined (i) in vitro using the transforming growth factor β1 (TGF-β1)-induced epithelial to mesenchymal transition (EMT) of human renal proximal tubular cells and (ii) in vivo using mouse unilateral ureteral obstruction (UUO). The findings revealed that incubation of 10 ng/ml TGF-β1 promotes morphological change in RPTEC/TERT1 cells, a human renal proximal tubular cell line, from epithelial to fibroblast-like cells. TGF-β1 markedly increased EMT markers namely α-smooth muscle actin (α-SMA), fibronectin, and matrix metalloproteinase 9 (MMP-9), while decreased the epithelial marker E-cadherin. Co-incubation TGF-β1 with altenusin preserved the epithelial characteristics of the renal epithelial cells by antagonizing TGF-β/Smad signaling pathway, specifically a decreased phosphorylation of Smad2/3 with an increased level of Smad7. Interestingly, the antagonizing effect of altenusin does not require FXR activation. Moreover, altenusin could reverse TGF-β1-induced fibroblast-like cells to epithelial-like cells. Treatment on UUO mice with 30 mg/kg altenusin significantly reduced the expression of α-SMA, fibronectin, and collagen type 1A1 (COL1A1). The reduction in the renal fibrosis markers is correlated with the decreased phosphorylation of Smad2/3 levels but does not improve E-cadherin protein expression. Collectively, altenusin reduces EMT in human renal proximal tubular cells and renal fibrosis by antagonizing the TGF-β/Smad signaling pathway.

Ferroptosis in organ fibrosis: From mechanisms to therapeutic medicines

Fibrosis occurs in many organs, and its sustained progress can lead to organ destruction and malfunction. Although numerous studies on organ fibrosis have been carried out, its underlying mechanism is largely unknown, and no ideal treatment is currently available. Ferroptosis is an iron-dependent process of programmed cell death that is characterized by lipid peroxidation. In the past decade, a growing body of evidence demonstrated the association between ferroptosis and fibrotic diseases, while targeting ferroptosis may serve as a potential therapeutic strategy. This review highlights recent advances in the crosstalk between ferroptosis and organ fibrosis, and discusses ferroptosis-targeted therapeutic approaches against fibrosis that are currently being explored.

NOBILETIN AMELIORATES HEATSTROKE-INDUCED ACUTE LUNG INJURY BY INHIBITING FERROPTOSIS VIA P53/SLC7A11 PATHWAY

ABSTRACT

The molecular mechanism for nobiletin's protective effect against heatstroke-induced acute lung injury (HS-ALI) remains largely unknown. Previous research has demonstrated that ferroptosis is an important pathogenic event in HS-ALI. Nobiletin is a natural polymethoxylated flavonoid. Herein, we investigated the potential contribution of nobiletin to HS-ALI by inhibiting ferroptosis. Heat stress was used to induce HS-ALI in mice, and mouse lung epithelial-12 (MLE-12) cells were stimulated by heat stress in vitro . Nobiletin was administrated by gavage for 2 h before HS induction. Biochemical kits, immunofluorescence staining, and western blotting were performed on the markers of ferroptosis. Our results showed that nobiletin administration significantly attenuated HS-induced lung injury and ferroptosis. Moreover, nobiletin pretreatment significantly reversed HS-induced p53 upregulation in vivo and in vitro . Pretreatment with a p53 agonist, tenovin-6, partly abolished the protective effect of nobiletin in mice with HS-ALI. Meanwhile, p53 knockdown significantly increased GPX4 and SLC7A11 expression levels compared with the HS group in HS-induced MLE-12 cells. Subsequently, nobiletin ameliorated HS-induced MLE-12 cells ferroptosis by activating the SLC7A11/GPX4 pathway, whereas p53 overexpression effectively abolished the protective effect of nobiletin. Taken together, our findings reveal that nobiletin attenuates HS-ALI by inhibiting ferroptosis through the p53/SLC7A11 pathway, indicating it to be a potential therapeutic agent for HS-ALI prevention and treatment.

Reduction of Th2 inflammation and fibrosis in eosinophilic esophagitis in a murine model by citri reticulatae pericarpium

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammation and subepithelial fibrosis play major roles in the early pathology of eosinophilic esophagitis (EoE). However, there are currently no pharmacotherapeutic interventions that directly target eosinophilic esophagitis. Citri Reticulatae Pericarpium (CRP, known as Chen-Pi) is one of most frequently used qi-regulating drugs in Chinese medicine and nutrition. CRP is rich with flavonones and polymethoxy flavones, both of which exhibit superior anti-inflammatory, anti-allergic and anti-fibrosis effects. This study is to investigate intervention effect of CRP on EoE, to identify its active compounds and to explore its underlying mechanisms.

METHODS

The CRP extract was obtained by liquid-liquid extraction with 70% ethanol, and its main components were identified by HPLC and TLC chromatography as hesperidin, nobiletin, tangeretin, and narirutin in turn. Furthermore, we evaluated its effect and underlying mechanisms in an PN (Peanut protein extract)-sensitized murine model of food allergy induced EoE.

RESULTS

CRP treatment attenuated EoE model mice symptomatology, blocked hypothermia, reduced the production of PN-specific IgE and IgG1 and TH2 cytokines (interleukin (IL)-4 and IL-5), and increased the level of anti-inflammatory cytokines IL-10 and interferon (IFN)-γ. CRP treatment also significantly alleviated the pathological damage and reduced fibrosis in inflamed tissues like esophagus, lung, and intestine. These results were strongly associated with reducing the expression of p-p38 mitogen-activated protein kinase (MAPK), transforming growth factor beta1 (TGF-β1) and p-Smad 3 proteins.

CONCLUSION

CRP extract markedly inhibited TH2 immune response and attenuated subepithelial fibrosis with a dose-dependent manner through down-regulating MAPK/TGF-β signaling pathway. It is suggested that CRP extract might serve as a potential therapy for food allergy-induced EoE like disease.

Low intensity pulsed ultrasound ameliorates Adriamycin-induced chronic renal injury by inhibiting ferroptosis

OBJECTIVE

It is very important to develop a new therapeutic strategy to cope with the increasing morbidity and mortality of chronic kidney disease (CKD). As a kind of physical therapy, low intensity pulsed ultrasound (LIPUS) has remarkable anti-inflammatory and repair-promoting effects and is expected to become a new therapeutic method for CKD. This study aims to clarify the treatment effect of LIPUS on CKD-related renal inflammation and fibrosis, and to further explore the potential signal network of LIPUS treatment for ameliorating chronic renal injury.

METHODS

A rat model simulating the progress of CKD was established by twice tail-vein injection of Adriamycin (ADR). Under anesthesia, bilateral kidneys of CKD rats were continuously stimulated by LIPUS for four weeks. The parameters of LIPUS were 1.0 MHz, 60 mW/cm2, 50% duty cycle and 20 min/d.

RESULTS

LIPUS treatment effectively inhibited ADR-induced renal inflammation and fibrosis, and improved CKD-related to oxidative stress and ferroptosis. In addition, the therapeutic effect of LIPUS is closely related to the regulation of TGF-β1/Smad and Nrf2/keap1/HO-1 signalling pathways.

DISCUSSION

This study provides a new direction for further mechanism research and lays an important foundation for clinical trials.

Vitexin attenuates chronic kidney disease by inhibiting renal tubular epithelial cell ferroptosis via NRF2 activation

BACKGROUND

Chronic kidney disease (CKD) involves a variety of pathological processes, and ferroptosis plays a vital role in CKD progression. Targeting ferroptosis is a promising strategy for the treatment of CKD. However, inhibitors of ferroptosis have not been used in the clinical treatment of CKD. Vitexin is a natural flavonoid with many biological activities and protective effects against various diseases. However, whether vitexin can prevent the progression of CKD is not known.

METHODS

In vivo, the effect of vitexin on CKD was evaluated by using mouse models of unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion (UIR). Western blotting, Sirius red staining and transmission electron microscopy were used to analyze renal tubular injury, interstitial fibrosis, and inflammation in the kidneys of UUO and UIR mice. In vitro, CCK8 assays and lipid peroxidation assays were performed to analyze cell viability and lipid peroxidation in human renal tubular epithelial cells (HK2 cells) induced by erastin. The activation of renal fibroblasts (NRK-49 F cells) was also analyzed. Additionally, an in-silico protein-drug docking model and coimmunoprecipitation were performed to determine the direct substrate of vitexin.

RESULTS

In vivo, vitexin treatment significantly ameliorated renal tubular injury, interstitial fibrosis, and inflammation in the kidneys of UUO and UIR mice. Additionally, our results showed that vitexin significantly attenuated UUO- and UIR-induced ferroptosis in renal tubular epithelial cells by upregulating glutathione peroxidase 4 (GPX4) protein levels and inhibiting lipid peroxidation in mouse kidneys. In vitro, treatment with vitexin inhibited erastin-induced ferroptosis in HK2 cells. Moreover, vitexin inhibited the expression of collagen I and α-SMA (alpha-smooth muscle actin) in NRK-49 F cells induced by the supernatant of erastin-treated HK2 cells. Mechanistically, our results suggested that vitexin could activate the NRF2/heme oxygenase-1 (HO-1) pathway by inhibiting the KEAP1- and ubiquitination-mediated degradation of NRF2, thereby increasing the expression of GPX4, and further inhibiting lipid peroxidation and ferroptosis. Additionally, knockout of NRF2 greatly inhibited the antiferroptotic effects of vitexin.

CONCLUSIONS

Taken together, our results indicate that vitexin can protect against renal tubular epithelial cell ferroptosis in CKD by activating the KEAP1/NRF2/HO-1 pathway and is a promising drug to treat CKD.

Emerging significance and therapeutic targets of ferroptosis: a potential avenue for human kidney diseases

Kidney diseases remain one of the leading causes of human death and have placed a heavy burden on the medical system. Regulated cell death contributes to the pathology of a plethora of renal diseases. Recently, with in-depth studies into kidney diseases and cell death, a new iron-dependent cell death modality, known as ferroptosis, has been identified and has attracted considerable attention among researchers in the pathogenesis of kidney diseases and therapeutics to treat them. The majority of studies suggest that ferroptosis plays an important role in the pathologies of multiple kidney diseases, such as acute kidney injury (AKI), chronic kidney disease, and renal cell carcinoma. In this review, we summarize recently identified regulatory molecular mechanisms of ferroptosis, discuss ferroptosis pathways and mechanisms of action in various kidney diseases, and describe the protective effect of ferroptosis inhibitors against kidney diseases, especially AKI. By summarizing the prominent roles of ferroptosis in different kidney diseases and the progress made in studying ferroptosis, we provide new directions and strategies for future research on kidney diseases. In summary, ferroptotic factors are potential targets for therapeutic intervention to alleviate different kidney diseases, and targeting them may lead to new treatments for patients with kidney diseases.

Nobiletin protects against ferroptosis to alleviate sepsis-associated acute liver injury by modulating the gut microbiota

Nobiletin (NOB), a plant-based polymethoxyflavone, is a promising protective agent against sepsis; yet the mechanisms were not fully elucidated. The gut microbiota is found to be strongly associated with sepsis-associated acute liver injury (SALI). Here, our study aimed to evaluate the protective effect of NOB on SALI and explore the underlying molecular mechanisms. Cecal ligation and puncture (CLP) was used to induce SALI in mice. NOB was administered by gavage for 7 days before CLP induction. The 16S rRNA gene sequencing and fecal microbiota transplantation (FMT) were performed to verify the function of the gut microbiota. The markers of ferroptosis, inflammation, gut microbiota composition, and liver injury were determined. NOB administration significantly alleviated hepatic ferroptosis and inflammation in septic mice. Meanwhile, NOB upregulated the expression levels of nuclear factor E2-related factor 2 (Nrf2) and its downstream protein heme oxygenase-1 (HO-1). The protective effect of NOB administration against ferroptosis in SALI mice was reversed by the Nrf2 inhibitor ML385. Additionally, increased abundances of Ligilactobacillus, Akkermansia, and Lactobacillus, and decreased abundances of Dubosiella and Bacteroides in the gut were observed under NOB administration, suggesting that NOB might modulate the gut microbiota composition of septic mice. Furthermore, gut microbiota ablation by antibiotic treatment partly reversed the protective effects of NOB on sepsis. FMT also confirmed that NOB inhibited ferroptosis and activated Nrf2 signalling in SALI mice by modulating the gut microbiota. These results revealed that, by modulating the gut microbiota, NOB attenuated ferroptosis in septic liver injury through upregulating Nrf2-Gpx4. Our findings provide novel insights into microbiome-based therapeutic approaches for sepsis.

The Road from AKI to CKD: Molecular Mechanisms and Therapeutic Targets of Ferroptosis

Acute kidney injury (AKI) is a prevalent pathological condition that is characterized by a precipitous decline in renal function. In recent years, a growing body of studies have demonstrated that renal maladaptation following AKI results in chronic kidney disease (CKD). Therefore, targeting the transition of AKI to CKD displays excellent therapeutic potential. However, the mechanism of AKI to CKD is mediated by multifactor, and there is still a lack of effective treatments. Ferroptosis, a novel nonapoptotic form of cell death, is believed to have a role in the AKI to CKD progression. In this study, we retrospectively examined the history and characteristics of ferroptosis, summarized ferroptosis's research progress in AKI and CKD, and discussed how ferroptosis participates in regulating the pathological mechanism in the progression of AKI to CKD. Furthermore, we highlighted the limitations of present research and projected the future evolution of ferroptosis. We hope this work will provide clues for further studies of ferroptosis in AKI to CKD and contribute to the study of effective therapeutic targets to prevent the progression of kidney diseases.

Ferroptosis in diabetic nephropathy: Mechanisms and therapeutic implications

Diabetic Nephropathy (DN), the most common complication in diabetes mellitus, has been affecting the lives of people diabetic for a long time. Numerous studies have demonstrated the unbreakable connection between ferroptosis and kidney cell damage. Ferroptosis is a type of iron-dependent, non-apoptotic, regulated cell death, characterized by the buildup of intracellular lipid peroxides to lethal levels. Although the role of programmed cell deaths like apoptosis, autophagy, and necroptosis in the pathogenesis of DN has been demonstrated, the implication of ferroptosis in DN was least interrogated. Hence, the main aim of this review was to discuss the current understanding of ferroptosis focusing on its potential mechanisms, its involvement in DN, and emerging therapeutic opportunities.

Natural Flavonoids and Ferroptosis: Potential Therapeutic Opportunities for Human Diseases

Flavonoids are a class of bioactive phytochemicals containing a core 2-phenylchromone skeleton and are widely found in fruits, vegetables, and herbs. Such natural compounds have gained significant attention due to their various health benefits. Ferroptosis is a recently discovered unique iron-dependent mode of cell death. Unlike traditional regulated cell death (RCD), ferroptosis is associated with excessive lipid peroxidation on cellular membranes. Accumulating evidence suggests that this form of RCD is involved in a variety of physiological and pathological processes. Notably, multiple flavonoids have been shown to be effective in preventing and treating diverse human diseases by regulating ferroptosis. In this review, we introduce the key molecular mechanisms of ferroptosis, including iron metabolism, lipid metabolism, and several major antioxidant systems. Additionally, we summarize the promising flavonoids targeting ferroptosis, which provides novel ideas for the management of diseases such as cancer, acute liver injury, neurodegenerative diseases, and ischemia/reperfusion (I/R) injury.

Formononetin ameliorates ferroptosis-associated fibrosis in renal tubular epithelial cells and in mice with chronic kidney disease by suppressing the Smad3/ATF3/SLC7A11 signaling

AIMS

Chronic kidney disease (CKD) is characterized by interstitial fibrosis, while limited treatment drugs are available. Ferroptosis is a newly identified process that can trigger tubular atrophy and fibrosis. The aim of this study is to investigate the effects of formononetin (FN), a bioflavonoid, on ferroptosis and renal fibrosis.

MAIN METHODS

In vivo experiments, unilateral ureteral obstruction (UUO)- and folic acid (FA, 250 mg/kg)-induced CKD models were constructed in C57BL/6 mice of 6-8 weeks old, followed by the administration with 40 mg/kg/day FN by gavage. For in vitro experiments, ferroptosis was induced with RSL3 or erastin in primary mouse renal tubular epithelial cells (TECs), followed by the addition of indicated concentrations of FN. Then, the levels of ferroptosis and fibrosis were analyzed. The translocation of Smad3, ATF3, and Nrf2 from the cytoplasm to the nucleus was checked by western blotting. The interaction of Smad3 and ATF3 was detected by Co-immunoprecipitation.

KEY FINDINGS

FN dramatically ameliorated tubular injury along with reduced expression of the profibrotic genes including α-SMA, Col1a1, and fibronectin in both two CKD mouse models and RSL3/erastin-treated TECs. Furthermore, FN administration also significantly suppressed ferroptosis, as evidenced by increased expression of SLC7A11 and GPX4, and decreased levels of 4-HNE. In mechanism, FN disrupted the interaction between Smad3 and ATF3, resulting in the blocking of their translocation from the cytoplasm to the nucleus. In addition, FN also promoted the separation of the Nrf2/Keap1 complex and enhanced Nrf2 nuclear accumulation.

SIGNIFICANCE

FN alleviates CKD by impeding ferroptosis-associated fibrosis by suppressing the Smad3/ATF3/SLC7A11 signaling and could serve as a candidate therapeutic drug for CKD.

Inhibitory Effects of Nobiletin on Voltage-Gated Na+ Channel in Rat Ventricular Myocytes Based on Electrophysiological Analysis and Molecular Docking Method

Nobiletin (NOB) has attracted much attention owing to its outstanding bioactivities. This study aimed to investigate its anti-arrhythmic effect through electrophysiological and molecular docking studies. We assessed the anti-arrhythmic effects of NOB using aconitine-induced ventricular arrhythmia in a rat model and the electrophysiological effects of NOB on rat cardiomyocytes utilizing whole-cell patch-clamp techniques. Moreover, we investigated the binding characters of NOB with rNav1.5, rNav1.5/QQQ, and hNa_V1.5 via docking analysis, comparing them with amiodarone and aconitine. NOB pretreatment delayed susceptibility to ventricular premature and ventricular tachycardia and decreased the incidence of fatal ventricular fibrillation. Whole-cell patch-clamp assays demonstrated that the peak current density of the voltage-gated Na⁺ channel current was reversibly reduced by NOB in a concentration-dependent manner. The steady-state activation and recovery curves were shifted in the positive direction along the voltage axis, and the steady-state inactivation curve was shifted in the negative direction along the voltage axis, as shown by gating kinetics. The molecular docking study showed NOB formed a π-π stacking interaction with rNav1.5 and rNav1.5/QQQ upon Phe-1762, which is the homolog to Phe-1760 in hNa_V1.5 and plays an important role in antiarrhythmic action This study reveals that NOB may act as a class I sodium channel anti-arrhythmia agent.

Ferroptosis and renal fibrosis: A new target for the future (Review)

Ferroptosis is a type of non-apoptotic controlled cell death triggered by oxidative stress and iron-dependent lipid peroxidation. Ferroptosis is regulated by signalling pathways that are associated with metabolism, including glutathione peroxidase 4 dysfunction, the cystine/glutamate antiporter system, lipid peroxidation and inadequate iron metabolism. Ferroptosis is associated with renal fibrosis; however, further research is required to understand the specific molecular mechanisms involved. The present review aimed to discuss the known molecular mechanisms of ferroptosis and outline the biological reactions that occur during renal fibrosis that may be associated with ferroptosis. Further investigation into the association between ferroptosis and renal fibrosis may lead to the development of novel treatment methods.

Sulforaphane Protects against Unilateral Ureteral Obstruction-Induced Renal Damage in Rats by Alleviating Mitochondrial and Lipid Metabolism Impairment

Unilateral ureteral obstruction (UUO) is an animal rodent model that allows the study of obstructive nephropathy in an accelerated manner. During UUO, tubular damage is induced, and alterations such as oxidative stress, inflammation, lipid metabolism, and mitochondrial impairment favor fibrosis development, leading to chronic kidney disease progression. Sulforaphane (SFN), an isothiocyanate derived from green cruciferous vegetables, might improve mitochondrial functions and lipid metabolism; however, its role in UUO has been poorly explored. Therefore, we aimed to determine the protective effect of SFN related to mitochondria and lipid metabolism in UUO. Our results showed that in UUO SFN decreased renal damage, attributed to increased mitochondrial biogenesis. We showed that SFN augmented peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) and nuclear respiratory factor 1 (NRF1). The increase in biogenesis augmented the mitochondrial mass marker voltage-dependent anion channel (VDAC) and improved mitochondrial structure, as well as complex III (CIII), aconitase 2 (ACO2) and citrate synthase activities in UUO. In addition, lipid metabolism was improved, observed by the downregulation of cluster of differentiation 36 (CD36), sterol regulatory-element binding protein 1 (SREBP1), fatty acid synthase (FASN), and diacylglycerol O-acyltransferase 1 (DGAT1), which reduces triglyceride (TG) accumulation. Finally, restoring the mitochondrial structure reduced excessive fission by decreasing the fission protein dynamin-related protein-1 (DRP1). Autophagy flux was further restored by reducing beclin and sequestosome (p62) and increasing B-cell lymphoma 2 (Bcl2) and the ratio of microtubule-associated proteins 1A/1B light chain 3 II and I (LC3II/LC3I). These results reveal that SFN confers protection against UUO-induced kidney injury by targeting mitochondrial biogenesis, which also improves lipid metabolism.

Potential Therapeutic Strategies for Renal Fibrosis: Cordyceps and Related Products

At present, there is no effective drug for the treatment of renal fibrosis; in particular, a safe and effective treatment for renal fibrosis should be established. Cordyceps has several medical effects, including immunoregulatory, antitumor, anti-inflammatory, and antioxidant effects, and may prevent kidney, liver, and heart diseases. Cordyceps has also been reported to be effective in the treatment of renal fibrosis. In this paper, we review the potential mechanisms of Cordyceps against renal fibrosis, focusing on the effects of Cordyceps on inflammation, oxidative stress, apoptosis, regulation of autophagy, reduction of extracellular matrix deposition, and fibroblast activation. We also discuss relevant published clinical trials and meta-analyses. Available clinical studies support the possibility that Cordyceps and related products provide benefits to patients with chronic kidney diseases as adjuvants to conventional drugs. However, the existing clinical studies are limited by low quality and significant heterogeneity. The use of Cordyceps and related products may be a potential strategy for the treatment of renal fibrosis. Randomized controlled trial studies with good methodological quality, favorable experimental design, and large sample size are needed to evaluate the efficacy and safety of Cordyceps.

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.

Role of Ferroptosis in Fibrotic Diseases

Ferroptosis is a unique and pervasive form of regulated cell death driven by iron-dependent phospholipid peroxidation. It results from disturbed cellular metabolism and imbalanced redox homeostasis and is regulated by various cellular metabolic pathways. Recent preclinical studies have revealed that ferroptosis may be an attractive therapeutic target in fibrotic diseases, such as liver fibrosis, pulmonary fibrosis, kidney fibrosis, and myocardial fibrosis. This review summarizes the latest knowledge on the regulatory mechanism of ferroptosis and its roles in fibrotic diseases. These updates may provide a novel perspective for the treatment of fibrotic diseases as well as future research.