Upregulation Of Heme Oxygenase-1 Research Articles

Self-catalyzed nitric oxide nanocomplexes induce ferroptosis for cancer immunotherapy

Ferroptosis, triggered by membrane lipid peroxidation (LPO) and diminished antioxidants, can be induced by intracellular iron (II, Fe2+). However, the role of nitric oxide (NO) in causing Fe2+ overload for ferroptosis remains uncertain. This study reveals that NO can stimulate endogenous Fe2+ release by upregulating heme oxygenase 1 (HMOX1) expression. Here, ferritin heavy chain (FHC) siRNA and hyaluronic acid (HA)-modified Arg-stabilized zinc peroxide (AZOSH), a non-ferrous-based nanoagent, is synthesized to trigger ferroptosis by inducing intracellular Fe2+ overload. AZOSH, a self-catalyzed NO nanocomplex, effectively generates NO through a reaction of self-supplied Arginine (Arg) and hydrogen peroxide (H2O2), which promotes glutathione (GSH) consumption to downregulate glutathione peroxidase 4 (GPX4) expression and produces peroxynitrite (ONOO−) to enhance LPO. Meanwhile, NO promotes endo/lysosomal escape of siRNA by damaging membrane structures. Moreover, AZOSH significantly triggers Fe2+ overload through the synergistic effects of NO-activated HMOX1 expression and FHC siRNA-mediated ferritin sequestration. Additionally, the released Zn2+ from AZOSH induces oxidative stress by inhibiting mitochondrial function, further promoting ferroptosis. Consequently, AZOSH-mediated ferroptosis exhibits a strong cellular immunogenic response for T-cell activation and infiltration. Importantly, the integration of AZOSH with an anti-PD-1 antibody results in notable antitumor efficacy in vivo. Therefore, this study provides a novel concept of NO-induced ferroptosis, highlighting its role in enhancing PD-1-based immunotherapeutic efficacy.

Designing Nano-Hemin for Ferroptosis-Mediated Cell Death via Enzymatic Hemin Digestion.

Hemin is a protoporphyrin complex of ferric ion which catalyzes H2O2 degradation and produces reactive oxygen species (ROS). This ROS generation property induces oxidative stress to hemin-exposed cells that can lead to various situations such as intracellular Fenton reaction, ferroptosis, or autophagy. Therapeutic performance of hemin is hindered due to low bioavailability of the active monomeric form with an intact ROS generation property. Here, we demonstrate a colloidal nanoparticle form of hemin (nano-hemin) with a high ROS generation property and high cell uptake property. We have shown that nano-hemin produces ROS inside a cell that upregulate heme oxygenase-1 in order to metabolize hemin. This leads to the ferroptosis-mediated cell death. Furthermore, we show that the ROS generation property of nano-hemin can be modulated to control hemin cytotoxicity for either ferroptosis or autophagy. Our findings suggest that nano-hemin can be designed with modular cytotoxicity for different therapeutic applications.

Demyelination in cuprizone mice is ameliorated by calycosin mediated through astrocyte Nrf2 signaling pathway

Oxidative stress plays a pivotal role in multiple sclerosis (MS), triggering demyelination predominantly through excessive peroxide production and the depletion of antioxidants. The accumulation of oxidative damage can be caused by dysregulation of astrocytes, which are the brain's main regulators of oxidative homeostasis. Calycosin, an essential bioactive component extracted from Astragalus, is recognized for its neuroprotective properties. Although recent research has highlighted calycosin's neuroprotective capabilities, its role in demyelinating conditions like MS remains unclear. In this work, we examined the possible molecular mechanism of calycosin's neuroprotective effect on cuprizone (CPZ)-induced demylination in mice. According to our research, calycosin successfully reduced demyelination and behavioral dysfuction in CPZ mice. Calycosin also decreased the production of oxidative stress and enhanced the expression of antioxidants in CPZ mice and in astrocytes induced by hydrogen peroxide (H2O2). Furthermore, both in vivo and in vitro experiments demonstrated that calycosin promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) along with the upregulation of heme oxygenase 1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1), and superoxide dismutase (SOD). Importantly, the application of all-trans retinoic acid (ATRA), a specific inhibitor of Nrf2, effectively reversed the myelin-protective and antioxidant effects conferred by calycosin. This study suggested that calycosin might exert neuroprotection by inhibiting oxidative stress and reducing demyelination via the activation of astrocyte Nrf2 signaling. These findings indicated that calycosin might be a potential candidate for treating MS.

Acupoint Autohemotherapy Alleviates Airway Inflammation in Asthmatic Rats via Upregulating Expression of Hemeoxygenase-1.

Acupoint autohemotherapy (AA), a therapeutic technique involving the subcutaneous injection of autologous blood into acupoints, has been empirically validated as safe and effective for treating asthma by alleviating symptoms and decreasing acute attacks, though its mechanism is not well understood. The role of heme oxygenase-1 (HO-1) in AA-induced suppression of asthmatic airway inflammation is examined. Twenty rats were assigned randomly to four groups, namely the Control, OVA, OVA + AA, and (OVA + Snpp) + AA. Rats in the OVA + AA and (OVA + Snpp) + AA received autologous blood injections into acupoints (BL13 and BL23) following OVA challenge. Rats in the (OVA + Snpp) + AA were concurrently subjected to intraperitoneal injections of Snpp, a inhibitor of HO-1. Airway inflammation was evaluated through HE staining, while the concentrations of cytokines in BALF were quantified using ELISA. The mRNA and protein levels of RORγt (Th17-specific transcription factor), Foxp3 (Treg-specific transcription factor), and HO-1 in lung tissue were assessed through qRT-PCR and WB. HE staining indicated that airway inflammation was alleviated in the OVA + AA. The OVA + AA displayed significantly lower counts of total cells and eosinophils in the BALF compared to both the OVA and (OVA + Snpp) + AA. The ELISA demonstrated a significant decrease in levels of pro-inflamatory cytokines (IL-4, IL-17A), and an increase in levels of anti-inflamatory cytokines (IFN-γ, IL-10), in the OVA + AA when compared to both OVA and (OVA + Snpp) + AA. The qRT-PCR and WB analyses revealed an upregulation of HO-1 and Foxp3 expression, and a downregulation of RORγt expression, in the OVA + AA when compared to OVA and (OVA + Snpp) + AA. The involvement of HO-1 in the underlying mechanism responsible for the anti-inflammatory effects of AA is evident.

Mevastatin-Induced HO-1 Expression in Cardiac Fibroblasts: A Strategy to Combat Cardiovascular Inflammation and Fibrosis.

Mevastatin (MVS) is known for its anti-inflammatory effects, potentially achieved by upregulating heme oxygenase-1 (HO-1), an enzyme involved in cytoprotection against oxidative injury. Nonetheless, the specific processes by which MVS stimulates HO-1 expression in human cardiac fibroblasts (HCFs) are not yet fully understood. In this study, we found that MVS treatment increased HO-1 mRNA and protein levels in HCFs. This induction was inhibited by pretreatment with specific inhibitors of p38 MAPK, JNK1/2, and FoxO1, and by siRNAs targeting NOX2, p47phox, p38, JNK1, FoxO1, Keap1, and Nrf2. MVS also triggered ROS generation and activated JNK1/2 and p38 MAPK, both attenuated by NADPH oxidase or ROS inhibitors. Additionally, MVS promoted the phosphorylation of FoxO1 and Nrf2, which was suppressed by p38 MAPK or JNK1/2 inhibitor. Furthermore, MVS inhibited TNF-α-induced NF-κB activation and vascular cell adhesion molecule-1 (VCAM-1) expression via the HO-1/CO pathway in HCFs. In summary, the induction of HO-1 expression in HCFs by MVS is mediated through two primary signaling pathways: NADPH oxidase/ROS/p38 MAPK, and JNK1/2/FoxO1 and Nrf2. This research illuminates the underlying processes through which MVS exerts its anti-inflammatory effects by modulating HO-1 in cardiac fibroblasts.

Carbon monoxide as a negative feedback mechanism on HIF-1α in the progression of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) encompasses various chronic liver conditions, yet lacks approved drugs. Hypoxia-inducible factor-1α (HIF-1α) is pivotal in MAFLD development. Our prior research highlighted the efficacy of the nano-designed carbon monoxide (CO) donor, targeting HIF-1α in a mouse hepatic steatosis model. Given heme oxygenase-1 (HO-1, a major downstream molecule of HIF-1α) as the primary source of intrinsic CO, we hypothesized that upregulation of HO-1/CO, responsive to HIF-1α, forms a negative feedback loop regulating MAFLD progression. In this study, we explored the potential negative feedback mechanism of CO on HIF-1α and its downstream effects on MAFLD advancement. HIF-1α emerges early in hepatic steatosis induced by a high-fat (HF) diet, triggering increased HO-1 and inflammation. SMA/CORM2 effectively suppresses HIF-1α and steatosis progression when administered within the initial week of HF diet initiation but loses impact later. In adipose tissues, concurrent metabolic dysfunction and inflammation with HIF-1α activation suggest adipose tissue expansion initiates HF-induced steatosis, triggering hypoxia and liver inflammation. Notably, in an in vitro study using mouse hepatocytes treated with fatty acids, downregulating HO-1 intensified HIF-1α induction at moderate fatty acid concentrations. However, this effect diminished at high concentrations. These results suggest the HIF-1α–HO–1-CO axis as a feedback loop under physiological and mild pathological conditions. Excessive HIF-1α upregulation in pathological conditions overwhelms the CO feedback loop. Additional CO application effectively suppresses HIF-1α and disease progression, indicating potential application for MAFLD control.

Cancer cell membrane-camouflaged curcumin nanoparticles trigger ferroptosis for accurate gastric cancer therapy

Curcumin (CUR) is a hydrophobic polyphenol with considerable antitumor efficiency, but its clinical application is limited because of its poor solubility and low stability in aqueous solution and lack of targeting in vivo. Herein, we fabricated a tumor-targeting drug delivery system by loading CUR and cloaking homologous cancer cell membrane (CM) onto mesoporous silica NPs (MSN-CUR@CM). Characterization analysis showed that MSN-CUR@CM with a size of approximately 70 nm showed high water solubility and biocompatibility. Besides, MSN-CUR@CM exhibited tumor-targeting and excellent anti-gastric cancer efficiency both in vitro and in vivo owing to the cellular self-recognition of CM. In the established xenograft tumor nude mouse model, it was still significantly drug accumulated at the tumor site 72 h post administration. In addition, the mean tumor volume and weight of the MSN-CUR@CM group were was 3.97 and 7.47 times smaller than those of the CUR group. Ferroptosis, a type of non-apoptotic regulated cell death accompanied by iron-dependent lipid peroxidation, was triggered by MSN-CUR@CM. Further analysis demonstrated that MSN-CUR@CUR upregulated heme oxygenase (HO)-1 levels whereas it downregulated the expression of glutathione peroxidase 4 (GPX4) in SGC7901 cells in vitro, indicating that the canonical and noncanonical ferroptosis pathways were regulated by MSN-CUR@CM. In conclusion, our study demonstrated that MSN-CUR@CM with high water solubility, biocompatibility, and tumor-targeting properties inhibited gastric cancer both in vitro and in vivo by triggering ferroptosis and provided an admirable cancer therapy efficacy.

Sulfiredoxin-1 accelerates erastin-induced ferroptosis in HT-22 hippocampal neurons by driving heme Oxygenase-1 activation

Ferroptosis, a recently identified non-apoptotic form of cell death, is strongly associated with neurological diseases and has emerged as a potential therapeutic target. Nevertheless, the fundamental mechanisms are still predominantly unidentified. In the current investigation, sulfiredoxin-1 (SRXN1) has been identified as a crucial regulator that enhances the susceptibility to ferroptosis in HT-22 mouse hippocampal cells treated with erastin. Utilizing TMT-based proteomics, a significant increase in SRXN1 expression was observed in erastin-exposed HT-22 cells. Efficient amelioration of erastin-induced ferroptosis was achieved via the knockdown of SRXN1, which resulted in the reduction of intracellular Fe2+ levels and reactive oxygen species (ROS) in HT-22 cells. Notably, the activation of Heme Oxygenase-1 (HO-1) was found to be crucial for inducing SRXN1 expression in HT-22 cells upon treatment with erastin. SRXN1 increased intracellular ROS and Fe2+ levels by activating HO-1 expression, which promoted erastin-induced ferroptosis in HT-22 cells. Inhibiting SRXN1 or HO-1 alleviated erastin-induced autophagy in HT-22 cells. Additionally, upregulation of SRXN1 or HO-1 increased the susceptibility of HT-22 cells to ferroptosis, a process that was counteracted by the autophagy inhibitor 3-Methyladenine (3-MA). These results indicate that SRXN1 is a key regulator of ferroptosis, activating the HO-1 protein through cellular redox regulation, ferrous iron accumulation, and autophagy in HT-22 cells. These findings elucidate a novel molecular mechanism of erastin-induced ferroptosis sensitivity and suggest that SRXN1-HO-1-autophagy-dependent ferroptosis serves as a promising treatment approach for neurodegenerative diseases.

The Metabolite of γ-Tocopherol, 2,7,8-Trimethyl-2-(2′-Carboxyethyl)-6-Hydroxychroman, Exerts Intracellular Antioxidant Activity via Up-Regulation of Heme Oxygenase-1 in Hepatocytes

γ-Tocopherol (γT) is the major form of vitamin E contained in plants and seed oils. Although it is readily metabolized in the liver, the function of the metabolites is not fully understood. This study investigated the antioxidant activities of the γT metabolite 2,7,8-trimethyl-2-(2′-carboxyethyl)-6-hydroxychroman (γCEHC) in comparison to its parent compound. The pretreatment of mouse hepatoma Hepa1c1c7 cells with γCEHC showed a cytoprotective effect on the hydrogen peroxide-induced cytotoxicity to a lesser extent than that of γT. A mechanistic investigation revealed that both γ-CEHC and γT significantly up-regulated the gene and protein expressions of heme oxygenase-1 (HO-1) via the promotion of the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Furthermore, the combination of γCEHC and γT significantly increased the gene and protein levels of HO-1 and the nuclear translocation of Nrf2, suggesting that it was an additive effect. Tin protoporphyrin IX (SnPP), a representative HO-1 inhibitor, significantly impaired the cytoprotection of γCEHC and γT against the hydrogen peroxide-induced cytotoxicity. These results suggested that not only γT but also its metabolite, γCEHC, are a promising cytoprotective factor against oxidative stress-induced cytotoxicity and that the cytoprotective effect is attributable to the cooperation of both compounds.

Abstract Tu132: Estrogen modulation of ethanol-evoked cardiac oxidative stress and dysfunction: Role of circadian clock period-2 and ferroptosis in estrogen deficient rats

Background: Alcohol triggers exacerbated cardiovascular effects in females, compared to males, in estrogen (E2) dependent manner. E2 provides cardiac protection in premenopausal women and models of menopause, yet the interplay between the circadian clock proteins and E2 in the female heart, particularly in the presence of ethanol (EtOH) remains unclear. Aim: This study aims to determine if the suppression of the circadian clock protein Period 2 (Per2) and associated redox enzymes contribute to E2-mediated exacerbation of the EtOH-induced cardiac ferroptosis, and dysfunction. Methods: Two groups of female Sprague-Dawley rats (n=6-8) were subjected to bilateral ovariectomy (OVX) and fed with EtOH (5% in liquid diet) in the presence of E2 or its vehicle for 8 weeks. Measurements of cardiac function using radiotelemetry and echocardiography along with ex vivo biochemical/molecular studies. Results: Compared to vehicle treated OVX+EtOH group, the E2-treated OVX+EtOH group exhibited: (1) reduced (p<0.05) body weight gain and fat mass; (2) higher (p<0.05) telemetry-measured blood pressure and heart rate; (3) reductions (p<0.05) in echocardiography derived contractility indices, ejection fraction and fractional shortening. In the same group, ex vivo molecular analysis demonstrated: (1) lower cardiac Per2 and suppressed (p<0.05) redox enzymes; (2) increased (p<0.05) ROS level and glutathione depletion (p<0.05), leading to the degradation of glutathione peroxidase 4 (GPX4); (3) heme oxygenase-1 upregulation leading to iron overload (p<0.05). These ferroptosis-related effects resulted in increased lipid peroxidation (p<0.05) compared to findings in OVX+EtOH rats in the absence of E2. Conclusion: This study is the first to suggest that abrogation of the E2-mediated Per2 upregulation unraveled cardiac ferroptosis and contributes to the detrimental cardiac effects of ethanol in E2-replete rats. These novel findings underscore the potential risk for myocardial ferroptosis and dysfunction in menopausal women who are consuming ethanol while on E2 replacement therapy.

Gut-derived wild blueberry phenolic acid metabolites modulate extrinsic cutaneous damage.

As the first line of defense, the skin is equipped with various physiological mechanisms positioned to prevent incoming oxidative damage from numerous environmental insults. With persistent exposure to the environment, understanding ways to augment the skin defenses is paramount in protecting from premature aging. In this study, we investigated the ability of five dietary phenolic metabolites, typically found in the bloodstream after wild blueberry consumption, to successfully defend the skin from UV light exposure in a novel ex vivo co-culture model of human skin explants and primary endothelial cells. Skin explants, placed in transwell inserts, were exposed to UV, and subsequently co-cultured with endothelial cells. When the endothelial cells had been pretreated with the bioactive metabolites at physiological concentrations (hippuric acid 3000 nM, isoferulic acid 1000 nM, salicylic acid 130 nM, benzoic acid 900 nM, α-hydroxyhippuric acid 400 nM) cutaneous damage was prevented on the co-cultured with UV-challenged skin explants. Co-culture with non-pretreated endothelial cells did not protect skin explants. Specifically, the pretreatment was able to reduce skin lipid peroxidation (measured as 4-hydroxynonenal protein adducts), and pro-inflammatory enzymes such as cyclooxygenase 2 (COX-2) and NADPH oxidase 4 (NOX-4). Furthermore, pretreatment with the metabolites prevented UV-induced release of inflammatory cytokines such as IL-1β and IL-8 as well as nitric oxides (NO) levels. In addition, the metabolites showed an impressive ability to prevent the loss of cutaneous structural proteins including involucrin and collagen type 1. Of note, endothelial cells cultured with UV exposed skin explants exhibited increased oxidative stress demonstrated by heme oxygenase-1 (HO-1) up-regulation which was significantly prevented in the metabolite treated models. These findings highlight the ability of dietary polyphenolic metabolites to improve cutaneous defenses against extrinsic stressors.

Emodin alleviates intestinal ischemia–reperfusion injury through antioxidant stress, anti-inflammatory responses and anti-apoptosis effects via Akt-mediated HO-1 upregulation

BackgroundIntestinal ischemia–reperfusion (I/R) injury is a severe vascular emergency. Previous research indicated the protective effects of Emodin on I/R injury. Our study aims to explore the effect of Emodin on intestinal I/R (II/R) injury and elucidate the underlying mechanisms.MethodsC57BL/6 mice and Caco-2 cells were used for in vivo and in vitro studies. We established an animal model of II/R injury by temporarily occluding superior mesenteric artery. We constructed an oxygen–glucose deprivation/reoxygenation (OGD/R) cell model using a hypoxia-reoxygenation incubator. Different doses of Emodin were explored to determine the optimal therapeutic dose. Additionally, inhibitors targeting the protein kinase B (Akt) or Heme oxygenase-1 (HO-1) were administered to investigate their potential protective mechanisms.ResultsOur results demonstrated that in animal experiments, Emodin mitigated barrier disruption, minimized inflammation, reduced oxidative stress, and inhibited apoptosis. When Akt or HO-1 was inhibited, the protective effect of Emodin was eliminated. Inhibiting Akt also reduced the level of HO-1. In cell experiments, Emodin reduced inflammation and apoptosis in the OGD/R cell model. Additionally, when Akt or HO-1 was inhibited, the protective effect of Emodin was weakened.ConclusionsOur findings suggest that Emodin may protect the intestine against II/R injury through the Akt/HO-1 signaling pathway.

Mild hypothermia protects against radiation-induced intestinal injury in mice via upregulation of heme oxygenase-1

Radiation can cause life-threatening intestinal damage, whether intentional or unintentional. The present study investigated the effects of mild hypothermia on radiation-induced intestinal injury and survival. For 1 h before and after a lethal dose of whole-body irradiation (13 Gy), mice were either maintained at normothermia (37 °C) or exposed to mild hypothermia (32 °C). The survival of the mice was monitored for 30 days, and the morphological changes in the intestine and the cytokine levels in the serum of the irradiated mice at normothermia or hypothermia were assessed by histological examination at 12 h, 3.5 days, and 5 days after irradiation. Hypothermia delayed the death of the mice and attenuated the damage to the intestine. Hypothermia reduced apoptosis in the jejunum 12 h after irradiation exposure and restored crypt number, villi length, and epithelial length of the jejunum after 3.5 days. Mild hypothermia also reduced serum levels of proinflammatory cytokines after radiation exposure. Furthermore, heme oxygenase-1 (HO-1) was specifically upregulated in the mouse intestine by hypothermia. The HO-1 inhibitor Sn(IV) protoporphyrin IX dichloride partially reversed the effect mild hypothermia had on HO-1. These results suggest that hypothermia is a protective factor against radiation-induced intestinal damage and can, therefore, be effectively used as a radioprotective condition. In summary, mild hypothermia reduced cell death and inflammation in radiation-induced intestinal injury, partly through the regulation of HO-1.

Effects of chlorogenic acid on productive and reproductive performances, egg quality, antioxidant functions, and intestinal microenvironment in aged breeder laying hens

This study investigated the effects of dietary chlorogenic acid (CGA) on the productive and reproductive performance, egg quality, antioxidant function, and intestinal microenvironment of laying hens. Thus, 162 healthy Hy-Line Brown breeding hens (63 weeks old) were randomly allocated to 3 groups, each receiving a basal diet plus supplementation: 0, 250, and 500 mg/kg CGA, respectively. Per the in vitro test, CGA had obvious inhibitory effects on Salmonella enteritis and avian pathogenic Escherichia coli and strong free radical scavenging ability. Per the breeder laying hen experiment, the CGA diets had no significant influence on egg production or reproductive performance (P < 0.05). Nevertheless, compared with the control diet, 250 mg/kg CGA significantly increased eggshell thickness, egg weight, yolk color, and Haugh unit (P < 0.05). Compared with the control diet and 500 mg/kg CGA, 250 mg/kg CGA significantly (P < 0.05) elevated antioxidant capacity by reducing serum malondialdehyde content, upregulating heme oxygenase-1, and downregulating heat shock proteins mRNA levels in the ileum. Compared with the control diet and 500 mg/kg CGA, 250 mg/kg CGA (P < 0.05) enhanced intestinal barrier function, shown by the upregulation of ileal Occludin and Mucin-2 mRNA levels; furthermore, 250 mg/kg CGA (P < 0.05) increased anti-apoptotic capacity by increasing B-cell leukemia/lymphoma 2 gene expression and downregulated Bcl2 Associated X mRNA levels in the liver and ileum of late breeder laying hens (P < 0.05). Lastly, 250 mg/kg CGA (P < 0.05) increased cecal g_CHKCI001 and short-chain fatty acid-producing bacteria g_Prevotellaceae UCG-001, positively related to gut health, and in the cecum, 500 mg/kg CGA significantly (P < 0.05) increased g_Shuttleworthia abundance, negatively related to gut health. Our findings suggest that dietary inclusion of 250 mg/kg CGA promotes egg quality, intestinal microbial composition, gut barrier integrity, and the antioxidant capacity of aged breeder laying hens.

Mesenchymal Stem Cell-Derived Exosomes Mitigate Acute Murine Liver Injury via Ets-1 and Heme Oxygenase-1 Up-regulation.

Mesenchymal stem cells (MSCs)-derived exosomes have been previously demonstrated to promote tissue regeneration in various animal disease models. This study investigated the protective effect of exosome treatment in carbon tetrachloride (CCl4)-induced acute liver injury and delineated possible underlying mechanism. Exosomes collected from conditioned media of previously characterized human umbilical cord-derived MSCs were intravenously administered into male CD-1 mice with CCl4-induced acute liver injury. Biochemical, histological and molecular parameters were used to evaluate the severity of liver injury. A rat hepatocyte cell line, Clone-9, was used to validate the molecular changes by exosome treatment. Exosome treatment significantly suppressed plasma levels of AST, ALT, and pro-inflammatory cytokines, including IL-6 and TNF-α, in the mice with CCl4-induced acute liver injury. Histological morphometry revealed a significant reduction in the necropoptic area in the injured livers following exosome therapy. Consistently, western blot analysis indicated marked elevations in hepatic expression of PCNA, c-Met, Ets-1, and HO-1 proteins after exosome treatment. Besides, the phosphorylation level of signaling mediator JNK was significantly increased, and that of p38 was restored by exosome therapy. Immunohistochemistry double staining confirmed nuclear Ets-1 expression and cytoplasmic localization of c-Met and HO-1 proteins. In vitro studies demonstrated that exosome treatment increased the proliferation of Clone-9 hepatocytes and protected them from CCl4-induced cytotoxicity. Kinase inhibition experiment indicated that the exosome-driven hepatoprotection might be mediated through the JNK pathway. Exosome therapy activates the JNK signaling activation pathway as well as up-regulates Ets-1 and HO-1 expression, thereby protecting hepatocytes against hepatotoxin-induced cell death.

Inhibitory effect of all-trans retinoic acid on ferroptosis in BeWo cells mediated by the upregulation of heme Oxygenase-1

IntroductionThis study aimed to explore the association between ferroptosis, a newly identified type of cell death, and the role of retinoic acid in developing pregnancy complications. Therefore, the effects of all-trans retinoic acid (ATRA) on ferroptosis susceptibility in BeWo cells were assessed to understand abnormal placental development. MethodsBeWo cells were used as surrogates for cytotrophoblasts. The effect of ATRA on ferroptosis sensitivity was assessed on BeWo cells pretreated with ATRA or dimethyl sulfoxide (DMSO; control), following which the LDH-releasing assay was performed. The effects of ATRA pretreatment on the antioxidant defense system (including glutathione [GSH], mitochondrial membrane potential, and heme oxygenase-1 [HMOX1]) in BeWo cells were assessed using assay kits, RT-qPCR, and HMOX1 immunostaining. To evaluate the effect of ATRA on BeWo cells, HMOX1 was silenced in BeWo cells using shRNA. ResultsATRA pretreatment increased ferroptosis resistance in BeWo cells. Although with pretreatment, qPCR indicated upregulation of HMOX1, no significant change was observed in the GSH levels or mitochondrial membrane potential. This was corroborated by intensified immunostaining for heme oxygenase-1 protein (HO-1). Notably, the protective effect of ATRA against ferroptosis was negated when HO-1 was inhibited. Although HMOX1-silenced BeWo cells exhibited heightened ferroptosis sensitivity compared with controls, ATRA pretreatment counteracted ferroptosis in these cells. DiscussionATRA pretreatment promotes BeWo cell viability by suppressing ferroptosis and upregulating HMOX1 and this can be used as a potential therapeutic strategy for addressing placental complications associated with ferroptosis.

Associations of dietary fructose with survival of patients (pts) with metastatic cancer of the urothelium (UC) and renal cell carcinoma (RCC) on immune checkpoint blockade (ICB).

4571 Background: The gut microbiome is a modifiable determinant of ICB efficacy. Dietary fiber is associated with longer progression-free survival (PFS) on ICB in melanoma and UC, putatively via effects on the gut microbiome. Other dietary factors may also impact ICB efficacy. Fructose promotes adverse health effects and induces ICB resistance in pre-clinical models via upregulation of the antiapoptotic enzyme heme oxygenase-1. Thus, we set out to explore effects of fructose intake on ICB efficacy. Methods: In a retrospective analysis of a prospectively collected cohort, we leveraged dietary data collected with the validated Harvard Willett Food Frequency Questionnaire from pts with advanced UC and RCC initiating ICB at Memorial Sloan Kettering to assess for associations between baseline dietary fructose and PFS and overall survival (OS). Tumor mutational burden (TMB) was estimated via MSK-IMPACT. Associations of fructose with clinical outcomes were evaluated using univariate (UV) and multivariable (MV) Cox proportional hazards regression. Fructose was normalized via log transformation and treated as a continuous variable. MV models adjusted for fiber intake and prior ICB exposure. UC models adjusted for TMB and Bellmunt risk score and RCC models for histology and IMDC score. Results: From 2/2021-6/2022, 88 eligible pts enrolled. Median follow-up was 10.2 and 17.0 months among pts with UC (n = 40) and RCC (n = 48), respectively; 32 RCC pts (67%) were IMDC intermediate/poor risk and 21 UC pts (52%) had visceral metastases. High fructose and fiber intake correlated (rho 0.66). Among UC pts, higher fructose was associated with shorter PFS after adjusting for covariables (Table). In the MV model, high fiber was associated with longer PFS (HR 0.2, 95% CI 0.07-0.62, p = .004). Among RCC pts, fructose was not associated with PFS. Fructose was associated with OS in the RCC UV model, but this association was not statistically significant in the MV model (Table). In an exploratory model for PFS pooling all pts, a test for interaction between fructose intake and disease type (UC vs RCC) showed p = .01. Conclusions: Dietary fructose is associated with shorter PFS in UC pts treated with ICB, but not RCC pts. Discrepant results between UC and RCC require further study and may be attributable to differences in therapy or cancer biology. Our findings provide insights into potentially beneficial dietary interventions. Efforts to characterize effects of fructose on the gut microbiome are ongoing. [Table: see text]

#1914 Comprehensive single-cell sequencing and lipidomics identify diverse injury states and cholesterol dynamics of the PTs in AKI-to-CKD transition

Abstract Background and Aims The underlying cellular events and metabolic dysfunction of acute kidney injury (AKI) transformed to chronic kidney disease (CKD) is still largely unclear. Previous studies have suggested lipids and metabolites have a profound impact on acute and chronic inflammation. One of the main sites of renal lipid accumulation is the proximal tubule cells (PTs). Here we demonstrated the injury states and cholesterol dynamics of PTs and its potential function in AKI to CKD in unilateral ischemia-reperfusion injury (UIR) mice model. Method We employed single-cell combinatorial indexing lipidomics to analyze 15 mouse kidneys from a mouse model of failed repaired UIR at five time points. We identified cell types through unsupervised clustering analysis. Differential gene expression, enrichment analysis and main function scoring were applied to define functional heterogeneity and injury states of PTs. Next, pseudotime analysis of differentiation transitions was performed to create the diverse PT lineages. Finally, using SCENIC analysis, we identified the key transcription factors that drive the differentiation of PTs. Results We identified 13 main cell clusters and the dynamic changes in the process of AKI to CKD transition were analysed. A remarkable decrease in PTs after injury at day 1 followed with a recovery at day 3 post AKI were observed. Spatiotemporal profiling of the main cell types showed that the most injured areas in the acute stages of kidney injury are primarily concentrated in the outer stripe, specifically the region where the proximal straight tubules (PSTs) are located. In order to gain a higher resolution of the dynamics of PST subtypes during AKI to CKD, we performed sub-clustering analysis specifically on PSTs, partitioning them into 10 subclusters. Single-cell analysis identified maladaptive PSTs (PST-5) with the highest apoptosis and ferroptosis scores. Notably, pseudotime analysis revealed that PST-5 differentiated from PST-4, which has the highest lipid metabolism score. Indeed, among all the cells in the kidney, the PTs exhibited the most active metabolic reprogramming due to their differentiation and redifferentiation early after AKI. Lipid omics profiling reveals an abnormal elevation of the cholesterol metabolites 27-hydroxycholesterol (27-OH) and 25-hydroxycholesterol (25-OH) following AKI. Interestingly, the PST-4-specific expression of Cyp7b1 served as a key enzyme regulating the concentration of 27-OH. This gene has been found to be significantly absent after AKI. Moreover, the binding of 27HC, a natural ligand, to endogenous estrogen receptor alpha (ERα) leads to the upregulation of heme oxygenase 1 (Hmox1), thereby promoting ferroptosis. Finally, SCENIC analysis revealed that Cyp7b1-mediated accumulation of 27-HC is dependent on the transcription factor Atf3. Conclusion Our results indicate that Cyp7b1 deficiency confers ferroptosis, which are primarily dependent on the upregulation of cellular cholesterol homeostasis and 27-HC secretion, leading to the progression of AKI. These findings suggest that the Cyp7b1/Hmox1/Atf3/27-HC axis may serve as a potential therapeutic target for preventing the development of CKD.

Cyclophosphamide induces ovarian granulosa cell ferroptosis via a mechanism associated with HO-1 and ROS-mediated mitochondrial dysfunction

Abnormal granulosa cell (GC) death contributes to cyclophosphamide (CTX) induced primary ovarian insufficiency (POI). To investigate the contribution of GCs to POI, gene profiles of GCs exposed to CTX were assessed using RNA-Seq and bioinformatics analysis. The results showed the differentially expressed genes (DEGs) were enriched in the ferroptosis-related pathway, which is correlated with upregulated heme oxygenase 1 (HO-1) and downregulated glutathione peroxidase-4 (GPX4). Using CTX-induced cell culture (COV434 and KGN cells), the levels of iron, reactive oxygen species (ROS), lipid peroxide, mitochondrial superoxide, mitochondrial morphology and mitochondrial membrane potential (MMP) were detected by DCFDA, MitoSOX, C11-BODIPY, MitoTracker, Nonylacridine Orange (NAO), JC-1 and transmission electron microscopy respectively. The results showed iron overload and disrupted ROS, including cytoROS, mtROS and lipROS homeostasis, were associated with upregulation of HO-1 and could induce ferroptosis via mitochondrial dysfunction in CTX-induced GCs. Moreover, HO-1 inhibition could suppress ferroptosis induced GPX4 depletion. This implies a role for ROS in CTX-induced ferroptosis and highlights the effect of HO-1 modulators in improving CTX-induced ovarian damage, which may provide a theoretical basis for preventing or restoring GC and ovarian function in patients with POI.

PPARγ Antagonists Exhibit Antitumor Effects by Regulating Ferroptosis and Disulfidptosis.

Oral squamous cell carcinoma (OSCC) stands as a prevalent subtype of head and neck squamous cell carcinoma, leading to disease recurrence and low survival rates. PPARγ, a ligand-dependent nuclear transcription factor, holds significance in tumor development. However, the role of PPARγ in the development of OSCC has not been fully elucidated. Through transcriptome sequencing analysis, we discovered a notable enrichment of ferroptosis-related molecules upon treatment with PPARγ antagonist. We subsequently confirmed the occurrence of ferroptosis through transmission electron microscopy, iron detection, etc. Notably, ferroptosis inhibitors could not completely rescue the cell death caused by PPARγ inhibitors, and the rescue effect was the greatest when disulfidptosis and ferroptosis inhibitors coexisted. We confirmed that the disulfidptosis phenotype indeed existed. Mechanistically, through qPCR and Western blotting, we observed that the inhibition of PPARγ resulted in the upregulation of heme oxygenase 1 (HMOX1), thereby promoting ferroptosis, while solute carrier family 7 member 11 (SLC7A11) was also upregulated to promote disulfidptosis in OSCC. Finally, a flow cytometry analysis of flight and multiplex immunohistochemical staining was used to characterize the immune status of PPARγ antagonist-treated OSCC tissues in a mouse tongue orthotopic transplantation tumor model, and the results showed that the inhibition of PPARγ led to ferroptosis and disulfidptosis, promoted the aggregation of cDCs and CD8+ T cells, and inhibited the progression of OSCC. Overall, our findings reveal that PPARγ plays a key role in regulating cell death in OSCC and that targeting PPARγ may be a potential therapeutic approach for OSCC.