Endometriosis: The Role of Iron Overload and Ferroptosis

Screening for ferroptosis genes related to endometrial carcinoma and predicting of targeted drugs based on bioinformatics

Endometrial carcinoma is one of most common malignant tumors in women, and ferroptosis is closely related to the development and treatment of endometrial carcinoma. The aim of this study was to screen ferroptosis-related genes associated with endometrial carcinoma and predict targeted drugs through bioinformatics. 761 differentially expressed genes were obtained by the dataset GSE63678 from the GEO database, and most of the genes were enriched in the KEGG_CELL_CYCLE and KEGG_OOCYTE_MEIOSIS signaling pathways. 22 ferroptosis-differentially expressed genes were obtained by intersection with the FerrDb database. These genes were involved in biological processes including macromolecular complex assembly and others, and involved in signal pathways including glutathione metabolism, p53 signaling pathway and others. CDKN2A, IDH1, NRAS, TFRC and GOT1 were obtained as hub genes by PPI network analysis. GEPIA showed that CDKN2A, IDH1, NRAS and TFRC were significantly expressed in endometrial carcinoma. Immunohistochemical results showed that CDKN2A, NRAS and TFRC were significantly expressed in endometrial carcinoma clinical tissue samples. The ROC constructed by TCGA database showed that CDKN2A, NRAS and TFRC had significant value in the diagnosis of endometrial carcinoma, and all had prognostic efficacy. 136,572-09-3 BOSS and others were identified as potential targeted drugs for endometrial carcinoma targeting ferroptosis. Our study has shown that ferroptosis-related genes CDKN2A, NRAS and TFRC are diagnostic markers of endometrial carcinoma, and 136,572-09-3 BOSS, methyprylon BOSS, daunorubicin CTD 00005752, nitroglycerin BOSS and dUTP BOSS, IRON BOSS, Imatinib mesylate BOSS, 2-Butanone BOSS, water BOSS, and L-thyroxine BOSS may be potential therapeutic drugs.

Creatine Promotes Endometriosis by Inducing Ferroptosis Resistance via Suppression of PrP

Endometriosis, a chronic inflammatory disease, significantly impairs the quality of life of women in their reproductive years; however, its pathogenesis remains poorly understood. The accumulation of retrograde menstruation and recurrent bleeding fosters a high-iron environment in ectopic lesions, triggering ferroptosis in ectopic endometrial stromal cells (EESCs), thereby hindering the establishment of endometriosis. However, abnormal EESCs demonstrate resistance to ferroptosis in high-iron environments, promoting the progression of this disease. Here, novel findings on the accumulation of creatine, derived from endogenous synthesis, in both peritoneal fluid and EESCs of patients with endometriosis are presented. Creatine supplementation reduces cellular iron concentrations, mitigating oxidative stress and lipid peroxidation, thereby enhancing cell viability and preventing ferroptosis under high-iron conditions. Utilizing the drug affinity-responsive target stabilization (DARTS) assay, prion protein (PrP) as a potential creatine-sensing protein is identified. Mechanistically, creatine binds to the active site of PrP, inhibits the conversion of trivalent iron to divalent iron, and decreases iron uptake, promoting the tolerance of EESCs to ferroptosis. This interaction contributes to the development of endometriosis. The novel association between creatine and ferroptosis provides valuable insights into the role of creatine in endometriosis progression and highlights its potential as a therapeutic target for endometriosis.

Identification of programmed cell death-related genes and diagnostic biomarkers in endometriosis using a machine learning and Mendelian randomization approach

Background

Endometriosis (EM) is a prevalent gynecological disorder frequently associated with irregular menstruation and infertility. Programmed cell death (PCD) is pivotal in the pathophysiological mechanisms underlying EM. Despite this, the precise pathogenesis of EM remains poorly understood, leading to diagnostic delays. Consequently, identifying biomarkers associated with PCD is critical for advancing the diagnosis and treatment of EM.

Methods

This study used datasets from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs) following preprocessing. By cross-referencing these DEGs with genes associated with PCD, differentially expressed PCD-related genes (DPGs) were identified. Enrichment analyses for KEGG and GO pathways were conducted on these DPGs. Additionally, Mendelian randomization and machine learning techniques were applied to identify biomarkers strongly associated with EM.

Results

The study identified three pivotal biomarkers: TNFSF12, AP3M1, and PDK2, and established a diagnostic model for EM based on these genes. The results revealed a marked upregulation of TNFSF12 and PDK2 in EM samples, coupled with a significant downregulation of AP3M1. Single-cell analysis further underscored the potential of TNFSF12, AP3M1, and PDK2 as biomarkers for EM. Additionally, molecular docking studies demonstrated that these genes exhibit significant binding affinities with drugs currently utilized in clinical practice.

Conclusion

This study systematically elucidated the molecular characteristics of PCD in EM and identified TNFSF12, AP3M1, and PDK2 as key biomarkers. These findings provide new directions for the early diagnosis and personalized treatment of EM.

PDLIM3 knockdown promotes ferroptosis in endometriosis progression via inducing Gli1 degradation and blocking Hedgehog signaling pathway

AIMS

Current evidence suggests that there is no completely effective method for endometriosis (EMS) without trauma due to diverse adverse effects. Reliable evidence illustrates that inhibiting ferroptosis is a potential strategy for EMS. We sufficiently verified that the expression of endogenous protein PDZ and LIM domain 3 (PDLIM3) was significantly increased in EMS.

METHODS

PDLIM3 knockdown reduced primary ectopic endometrial stromal cells' (EESCs) viability and migration, and elevated ferroptosis signaling indicators including Fe2+, malondialdehyde (MDA), and reactive oxygen species (ROS) in EESCs.

RESULTS

Mechanistic studies revealed that inhibition of PDLIM3 accelerated glioma-associated oncogene-1 (Gli1) degradation and further deactivated Hedgehog signaling. Gli1 inhibitor, GANT61, abrogated the impact of PDLIM3 deletion on EESC growth, migration, and ferroptosis. In vivo experiments suggested that PDLIM3 reduction repressed the growth of endometrial lesions. Likewise, repression of PDLIM3 promoted ferroptosis and attenuated Hedgehog signaling in endometrial lesions.

CONCLUSIONS

Collectively, silencing of PDLIM3 facilitates ferroptosis in EMS by inducing Gli1 degradation and blocking Hedgehog signaling. It may provide an alternative strategy for developing therapeutic agents of EMS in the future.

Assessment of the Ferroptosis Regulators: Glutathione Peroxidase 4, Acyl-Coenzyme A Synthetase Long-Chain Family Member 4, and Transferrin Receptor 1 in Patient-Derived Endometriosis Tissue

Ferroptosis, an iron-dependent form of non-apoptotic cell death, plays a pivotal role in various diseases and is gaining considerable attention in the realm of endometriosis. Considering the classical pathomechanism theories, we hypothesized that ferroptosis, potentially driven by increased iron content at ectopic sites, may contribute to the progression of endometriosis. This retrospective case-control study provides a comprehensive immunohistochemical assessment of the expression and tissue distribution of established ferroptosis markers: GPX4, ACSL4, and TfR1 in endometriosis patients. The case group consisted of 38 women with laparoscopically and histologically confirmed endometriosis and the control group consisted of 18 women with other gynecological conditions. Our study revealed a significant downregulation of GPX4 in stromal cells of endometriosis patients (M = 59.7% ± 42.4 versus 90.0% ± 17.5 in the control group, t (54) = -2.90, p = 0.005). This finding aligned with slightly, but not significantly, higher iron levels detected in the blood of endometriosis patients, using hemoglobin as an indirect predictor (Hb 12.8 (12.2-13.5) g/dL versus 12.5 (12.2-13.4) g/dL in the control group; t (54) = -0.897, p = 0.374). Interestingly, there was no concurrent upregulation of TfR1 (M = 0.7 ± 1.2 versus 0.2 ± 0.4 for EM, t (54) = 2.552, p = 0.014), responsible for iron uptake into cells. Our empirical findings provide support for the involvement of ferroptosis in the context of endometriosis. However, variances in expression patterns within stromal and epithelial cellular subsets call for further in-depth investigations.

Is retrograde menstruation a universal, recurrent, physiological phenomenon? A systematic review of the evidence in humans and non-human primates

STUDY QUESTION

What are the quantitative, qualitative, and temporal patterns of retrograde mentruation?

SUMMARY ANSWER

The extreme quantitative and qualitative heterogeneity of the available studies prevents the definitive conclusion that retrograde menstruation is a universal and consistent phenomenon during the reproductive period.

WHAT IS KNOWN ALREADY

Retrograde menstruation has been defined as a universal, physiological phenomenon that occurs similarly in about 90% of menstruators during the reproductive period. However, uncertainties still exist in terms of the event frequency, total amount, and cellular composition of retrograde menstruation and the differences between individuals with versus those without endometriosis.

STUDY DESIGN SIZE DURATION

Two systematic reviews were performed, one for human studies, and one for non-human primate studies. We retrieved studies from the PubMed and Embase databases published between 1 January 1980 and 1 November 2023. Studies published in the English language were included and identified using a combination of MeSH terms. References from relevant publications were systematically screened and further articles were identified using PubMed's 'similar articles' and 'cited by' functions.

PARTICIPANTS/MATERIALS SETTING METHODS

Results were reported in accordance with the PRISMA guidelines. Studies that did not report original data or provided a review of the field were excluded. Bias analysis was completed for each included human study by using the Newcastle-Ottawa scoring system.

MAIN RESULTS AND THE ROLE OF CHANCE

Fifteen studies were finally included in the human systematic review, mostly with limited sample sizes. The macroscopic visualization of blood in PF during menses was reported with a frequency ranging from 9% to 100%. A prevalence of endometrial cells detected in peritoneal fluid ranging from 8% to 75% was reported in the various studies. Controversial findings were reported in relation to patients with endometriosis. Retrograde menstruation has been evaluated cross-sectionally on single occasions, and no information is available on the course of the phenomenon within an entire cycle and between subsequent cycles. Two studies were included in the non-human primate systematic review; one of them showed that retrograde menstruation was observed more frequently in baboons with naturally occurring endometriosis (83%) than in those with a normal pelvis (51%).

LIMITATIONS REASONS FOR CAUTION

In humans, peritoneal fluid has often been collected at different cycle phases and not systematically during menstruation. The indication for laparoscopy was not always clear for all participants. A wide variety of methods were used to detect endometrial cells, including cytological staining, cell block analysis, immunocytochemistry, and various methods of cell culture.

WIDER IMPLICATION OF THE FINDINGS

The idea that almost all women experience retrograde menstruation regularly and similarly during their reproductive life is currently unsubstantiated. It is an academic notion accepted uncritically. Development of endometriosis may derive from differences in the frequency or severity of the event.

STUDY FUNDING/COMPETING INTERESTS

The review was partially funded by Italian Ministry of Health-Current Research IRCCS. P.Vi. serves as co-editor in Chief of Journal of Endometriosis and Uterine Disorders. E.S. serves as Editor in Chief of Human Reproduction Open and discloses research grants from Ferring, Ibsa, Gedeon Richter, and Theramex, and honoraria from Ibsa and Gedeon Richter. P.Ve. serves as Associate Editor for Human Reproduction Open; is a member of the Editorial Board of the Journal of Obstetrics and Gynaecology Canada, of the Italian Journal of Obstetrics and Gynaecology, and of the International Editorial Board of Acta Obstetricia et Gynecologica Scandinavica; has received royalties from Wolters Kluwer for chapters on endometriosis management in the clinical decision support resource UpToDate; and maintains both a public and private gynecological practice. All other authors declare they have no conflict of interest.

REGISTRATION NUMBER

N/A.

Reflections on the complex mechanisms of endometriosis from the perspective of ferroptosis

Ferroptosis is a novel type of iron-dependent programmed cell death characterised by intracellular iron overload, increased lipid peroxidation and abnormal accumulation of reactive oxygen species.It has been implicated in the progression of several diseases including cancer, ischaemia-reperfusion injury, neurodegenerative diseases and liver disease. The etiology of endometriosis (EMS) is still unclear and is associated with multiple factors, often accompanied by various forms of cell death and a complex microenvironment. In recent decades, the role of non-traditional forms of cell death, represented by ferroptosis, in endometriosis has come to the attention of researchers. This article reviews the transitional role of iron homeostasis in the development of ferroptosis, the characteristics and regulatory mechanisms of ferroptosis, and focuses on summarising the links between iron death and various pathogenic mechanisms of EMS, including oxidative stress, dysregulation of lipid metabolism, inflammation, autophagy and epithelial-mesenchymal transition. The possible applications of ferroptosis in the treatment of EMS, future research directions and current issues are discussed with the aim of providing new ideas for further understanding of EMS.

Iron overload increases the sensitivity of endometriosis stromal cells to ferroptosis via a PRC2-independent function of EZH2

Given the high concentration of iron in the micro-environment of ovarian endometriosis, it is plausible to hypothesize that ectopic endometrial cells may be more susceptible to undergoing ferroptosis. Manipulation of ferroptosis has been explored as a potential therapeutic strategy to treat related diseases. In this study, we examined the impact on ectopic endometrial stromal cells (EESCs) of iron overload and an inducer of ferroptosis. We found that the iron concentration in the ovarian endometriosis was much higher than control samples. Treatment of cultured EESCs with ferric ammonium citrate (FAC) increase the sensitivity to undergo ferroptosis. By analyzing the RNA-seq results, it was discovered that zeste 2 polycomb repressive complex 2 subunit (EZH2) was significantly downregulated in ferroptosis induced EESCs. Moreover, overexpression of EZH2 effectively prevented the induction of ferroptosis. In addition, the activity or expression of EZH2 is directly and specifically inhibited by the methyltransferase inhibitor GSK343, which raises the sensitivity of stromal cells to ferroptosis. Taken together, our findings revealed that EZH2 act as a suppressor in the induced cell ferroptosis through a PRC2-independent methyltransferase mechanism. Therefore, blocking EZH2 expression and inducing ferroptosis may be effective treatment approaches for ovarian endometriosis.

Effects of chronic low-level lead (Pb) exposure on cognitive function and hippocampal neuronal ferroptosis: An integrative approach using bioinformatics analysis, machine learning, and experimental validation

Lead (Pb), a pervasive and ancient toxic heavy metal, continues to pose significant neurological health risks, particularly in regions such as Southeast Asia. While previous research has primarily focused on the adverse effects of acute, high-level lead exposure on neurological systems, studies on the impacts of chronic, low-level exposure are less extensive, especially regarding the precise mechanisms linking ferroptosis - a novel type of neuron cell death - with cognitive impairment. This study aims to explore the potential effects of chronic low-level lead exposure on cognitive function and hippocampal neuronal ferroptosis. This research represents the first comprehensive investigation into the impact of chronic low-level lead exposure on hippocampal neuronal ferroptosis, spanning clinical settings, bioinformatic analyses, and experimental validation. Our findings reveal significant alterations in the expression of genes associated with iron metabolism and Nrf2-dependent ferroptosis following lead exposure, as evidenced by comparing gene expression in the peripheral blood of lead-acid battery workers and workers without lead exposure. Furthermore, our in vitro and in vivo experimental results strongly suggest that lead exposure may precipitate cognitive dysfunction and induce hippocampal neuronal ferroptosis. In conclusion, our study indicates that chronic low-level lead exposure may activate microglia, leading to the promotion of ferroptosis in hippocampal neurons.

Ferroptosis and oxidative stress in endometriosis: A systematic review of the literature

BACKGROUND

Endometriosis (EMT) a common gynecological condition in women, an inflammatory disease characterized by the presence of endometrial tissue on organs and tissues in the pelvis, and is mainly associated with chronic pelvic pain and infertility. As the etiology has not been fully elucidated, current treatment is limited to surgery, hormones and painkillers, with more side effects and difficulty in achieving long-term relief. Oxidative stress manifests itself as an overproduction of reactive oxygen species, which has an integral impact in the pathology of female reproductive disorders. In this review, we evaluate the mechanisms of iron overload-induced oxidative stress and ferroptosis in EMT and their pathophysiological implications.

METHODS

Because the etiology has not been fully elucidated, current treatments are limited to surgery, hormones, and painkillers, which have many side effects and are difficult to achieve long-term relief.

RESULTS

We interpreted that antioxidants as well as ferroptosis inducers show promising results in the treatment of EMT, but their application in this population needs to be further investigated.

CONCLUSION

In combination with the interpretation of previous studies, it was shown that iron overload is present in the peritoneal fluid, endometriotic lesions, peritoneum and macrophages in the abdominal cavity. However, the programmed cellular ferroptosis associated with iron overload is resisted by endometriotic foci, which is critical to the pathophysiology of EMT with local iron overload and inflammation.

Resveratrol protected against the development of endometriosis by promoting ferroptosis through miR-21-3p/p53/SLC7A11 signaling pathway

Resveratrol is involved in regulating ferroptosis, but its role in Endometriosis (EMS) is not clear. In this study, we aim to investigate the effect of ferroptosis and resveratrol intervention in the pathogenesis of EMS cyst. Cell proliferation, migration, and oxidative stress level were analyzed. The interaction of miR-21-3p and p53 was analyzed by dual luciferase assay. The interaction between p53 and SLC7A11 were analyzed by chromatin immunoprecipitation (CHIP). The miR-21-3p, GPX4, ACSL4, FTH1, p53, SLC7A11, Ptgs2 and Chac1 expression were analyzed by RT-qPCR or Western blot. The Fe3+ deposition and miR-21-3p, GPX4, FTH1 and SLC7A11 expressions were increased, and ACSL4, p53, Ptgs2 and Chac1 expression were decreased in EMS patients. Resveratrol inhibited migration, induced Ptgs2 and Chac1 expression in EESCs. Overexpression of miR-21-3p inhibited p53, Ptgs2 and Chac1 expression, and promoted SLC7A11 expression, which was reversed by resveratrol. miR-21-3p bound to p53, which interacted with SLC7A11. Resveratrol promoted Ptgs2 and Chac1 expression in the sh-p53 EESCs. Resveratrol reduced miR-21-3p and SLC7A11 expressions, and increased p53, Ptgs2 and Chac1 expressions, and Fe3+ deposition in the lesion tissues of EMS mice, which were reversed by miR-21-3p mimics. Resveratrol activated p53/SLC7A11 pathway by down-regulating miR-21-3p to promote ferroptosis and prevent the development of EMS.

Proposal for targeted, neo-evolutionary-oriented secondary prevention of early-onset endometriosis and adenomyosis. Part II: medical interventions

According to consistent epidemiological data, the slope of the incidence curve of endometriosis rises rapidly and sharply around the age of 25 years. The delay in diagnosis is generally reported to be between 5 and 8 years in adult women, but it appears to be over 10 years in adolescents. If this is true, the actual onset of endometriosis in many young women would be chronologically placed in the early postmenarchal years. Ovulation and menstruation are inflammatory events that, when occurring repeatedly for years, may theoretically favour the early development of endometriosis and adenomyosis. Moreover, repeated acute dysmenorrhoea episodes after menarche may not only be an indicator of ensuing endometriosis or adenomyosis, but may also promote the transition from acute to chronic pelvic pain through central sensitization mechanisms, as well as the onset of chronic overlapping pain conditions. Therefore, secondary prevention aimed at reducing suffering, limiting lesion progression, and preserving future reproductive potential should be focused on the age group that could benefit most from the intervention, i.e. severely symptomatic adolescents. Early-onset endometriosis and adenomyosis should be promptly suspected even when physical and ultrasound findings are negative, and long-term ovulatory suppression may be established until conception seeking. As nowadays this could mean using hormonal therapies for several years, drug safety evaluation is crucial. In adolescents without recognized major contraindications to oestrogens, the use of very low-dose combined oral contraceptives is associated with a marginal increase in the individual absolute risk of thromboembolic events. Oral contraceptives containing oestradiol instead of ethinyl oestradiol may further limit such risk. Oral, subcutaneous, and intramuscular progestogens do not increase the thromboembolic risk, but may interfere with attainment of peak bone mass in young women. Levonorgestrel-releasing intra-uterine devices may be a safe alternative for adolescents, as amenorrhoea is frequently induced without suppression of the ovarian activity. With regard to oncological risk, the net effect of long-term oestrogen-progestogen combinations use is a small reduction in overall cancer risk. Whether surgery should be considered the first-line approach in young women with chronic pelvic pain symptoms seems questionable. Especially when large endometriomas or infiltrating lesions are not detected at pelvic imaging, laparoscopy should be reserved to adolescents who refuse hormonal treatments or in whom first-line medications are not effective, not tolerated, or contraindicated. Diagnostic and therapeutic algorithms, including self-reported outcome measures, for young individuals with a clinical suspicion of early-onset endometriosis or adenomyosis are proposed.

Proposal for targeted, neo-evolutionary-oriented, secondary prevention of early-onset endometriosis and adenomyosis. Part I: pathogenic aspects

The potential for repeated ovulation and menstruation is thought to have provided a Darwinian advantage during the Palaeolithic. Reproductive conditions remained relatively stable until the pre-industrial era, characterized by late menarche, very young age at first birth, multiple pregnancies, and prolonged periods of lactational amenorrhoea. For hundreds of thousands of years, menstruators experienced few ovulatory cycles, even though they were genetically adapted to ovulate and menstruate every month. In the post-industrial era, the age at menarche gradually declined, the age at first birth progressively increased, and breastfeeding became optional and often of short duration. This created a mismatch between genetic adaptation and socio-environmental evolution, so that what was initially a probable reproductive advantage subsequently contributed to increased susceptibility to diseases associated with lifetime oestrogen exposure, such as ovarian, endometrial and breast cancer and, hypothetically, also those associated with the number of ovulatory menstruations, such as endometriosis and adenomyosis. The incidence of endometriosis shows a steep and progressive increase around the age of 25 years, but given the consistently reported delay in diagnosis, the actual incidence curve should be shifted to the left, supporting the possibility that the disease has its roots in adolescence. This raises the question of whether, from an evolutionary point of view, anovulation and amenorrhoea should not still be considered the physiological state, especially in the postmenarchal period. However, an increase in the frequency of endometriosis in recent decades has not been demonstrated, although this deserves further epidemiological investigation. In addition, as endometriosis occurs in a minority of individuals exposed to retrograde menstruation, other important pathogenic factors should be scrutinised. Research should be resumed to explore in more detail the transtubal reflux of not only blood, but also endometrial cells, and whether they are systematically present in the peritoneal fluid after menstruation. If repetitive ovulatory menstruation during the early reproductive years is shown to increase the risk of endometriosis and adenomyosis development and progression in susceptible individuals, hormonal interventions could be used as secondary prevention in symptomatic adolescents.

Endometrial stromal cell autophagy-dependent ferroptosis caused by iron overload in ovarian endometriosis is inhibited by the ATF4-xCT pathway

Ferroptosis is an iron-dependent programmed cell death process characterized by the accumulation of lethal oxidative damage. Localized iron overload is a unique clinical phenomenon in ovarian endometriosis (EM). However, the role and mechanism of ferroptosis in the course of ovarian EM remain unclear. Traditionally, autophagy promotes cell survival. However, a growing body of research suggests that autophagy promotes ferroptosis under certain conditions. This study aimed to clarify the status of ferroptosis in ovarian EM and explore the mechanism(s) by which iron overload causes ferroptosis and ectopic endometrial resistance to ferroptosis in human. The results showed increased levels of iron and reactive oxygen species in ectopic endometrial stromal cells (ESCs). Some ferroptosis and autophagy proteins in the ectopic tissues differed from those in the eutopic endometrium. In vitro, iron overload caused decreased cellular activity, increased lipid peroxidation levels, and mitochondrial morphological changes, whereas ferroptosis inhibitors alleviated these phenomena, illustrating activated ferroptosis. Iron overload increased autophagy, and ferroptosis caused by iron overload was inhibited by autophagy inhibitors, indicating that ferroptosis caused by iron overload was autophagy-dependent. We also confirmed the effect of iron overload and autophagy on lesion growth in vivo by constructing a mouse EM model; the results were consistent with those of the in vitro experiments of human tissue and endometrial stomal cells. However, ectopic lesions in patients can resist ferroptosis caused by iron overload, which can promote cystine/glutamate transporter hyperexpression by highly expressing activating transcription factor 4 (ATF4). In summary, local iron overload in ovarian EM can activate autophagy-related ferroptosis in ESCs, and ectopic lesions grow in a high-iron environment via ATF4-xCT while resisting ferroptosis. The effects of iron overload on other cells in the EM environment require further study. This study deepens our understanding of the role of ferroptosis in ovarian EM.

Chronic low-grade inflammation and ovarian dysfunction in women with polycystic ovarian syndrome, endometriosis, and aging

The ovarian microenvironment is critical for follicular development and oocyte maturation. Maternal conditions, including polycystic ovary syndrome (PCOS), endometriosis, and aging, may compromise the ovarian microenvironment, follicular development, and oocyte quality. Chronic low-grade inflammation can induce oxidative stress and tissue fibrosis in the ovary. In PCOS, endometriosis, and aging, pro-inflammatory cytokine levels are often elevated in follicular fluids. In women with obesity and PCOS, hyperandrogenemia and insulin resistance induce ovarian chronic low-grade inflammation, thereby disrupting follicular development by increasing oxidative stress. In endometriosis, ovarian endometrioma-derived iron overload can induce chronic inflammation and oxidative stress, leading to ovarian ferroptosis and fibrosis. In inflammatory aging (inflammaging), senescent cells may secrete senescence-associated secretory phenotype factors, causing chronic inflammation and oxidative stress in the ovary. Therefore, controlling chronic low-grade inflammation and fibrosis in the ovary would present a novel therapeutic strategy for improving the follicular microenvironment and minimizing ovarian dysfunction.

Unraveling the Clinical Relevance of Ferroptosis-Related Genes in Human Ovarian Aging

Ferroptosis, a recently discovered form of cell death, has been implicated in various diseases. However, the genetic relationship between ferroptosis and ovarian aging has not been thoroughly investigated through informatics analysis. In this study, we conducted bioinformatics analysis using ovarian aging and ferroptosis datasets to identify potential ferroptosis-related genes using R software. The expression levels of these genes at different ages were analyzed using the GTEx public database. To validate these findings at the genetic level, we performed clinical infertility biopsies. Bioinformatics analysis of a mouse ovary dataset revealed significantly higher expression of Tfrc, Ncoa4, and Slc3a2 in the aging group compared to the young group, while Gpx4 showed the opposite pattern. Consistent results were observed in biopsies from clinically aged infertile patients. This study is the first to identify a ferroptosis-related gene associated with ovarian aging, highlighting its potential as a diagnostic biomarker.

Ferroportin expression and regulation in human placenta/fetal membranes: Implications for ferroptosis and adverse pregnancy outcomes

Iron overload is associated with pregnancy complications. Ferroportin (FPN) is the only known iron exporter in mammalian cells. We hypothesize that FPN is functionally important in ferrotopsis, a process of iron-dependent non-apoptotic programmed cell death, and may have a critical role to play in pregnancy success. We investigated the expression of FPN in placenta/fetal membranes by immunohistochemistry in tissues collected from pregnancies with/without preeclampsia (PE) and spontaneous preterm birth (SPTB). FPN was highly expressed in both trophoblasts and decidual cells found in placenta/fetal membranes. Staining was significantly reduced in fetal membranes from SPTB versus healthy pregnancies (P = 0.046). FPN expression in immortalized human endometrial stromal cells (HESC) increased with in vitro decidualization induction using 1 μM of medroxyprogesterone acetate and 0.5 mM of dibutyryl-cAMP. In addition, both HESC cells and immortalized extravillous trophoblast SW71 cells with FPN knockdown showed significant sensitivity to ferroptosis inducer, erastin (P < 0.001 and P = 0.009, respectively). The survival of both HESC and SW71 cells was not negatively affected by iron supplementation with ferric ammonium citrate in the medium. However, SW71 cells were more sensitive than HESC cells to physiologic iron in the presence of a non-lethal dose of erastin (P < 0.001). Taken together, our data demonstrating increased sensitivity of FPN knockdown HESC and SW71 cells to erastin and increased sensitivity of trophoblasts to iron overload under ferroptotic stress support the hypothesis that FPN protects against ferroptosis during pregnancy.

Autophagy-dependent ferroptosis is involved in the development of endometriosis

OBJECTIVE

Endometriosis (EMS) is an estrogen-dependent condition with unclear pathogenesis. Recent findings suggest implicate autophagy and ferroptosis in EMS development.

METHODS

We assessed autophagy and ferroptosis proteins in EMS patients using immunohistochemistry and western blot and established an EMS rat model through allograft endometrial transplantation, confirmed via hematoxylin and eosin staining and epithelial-mesenchymal transition -related proteins. Primary EMS cells were isolated from the model rats and cultured under five conditions: control, EMS, EMS with Rapamycin (autophagy inducer), EMS with si-Atg5 (autophagy inhibitor), and EMS with si-Atg5 plus Erastin (ferroptosis inducer). We evaluated cell viability, iron content, oxidative stress, and mitochondrial morphologyin EMS cells, and detected autophagy and ferroptosis proteins through immunofluorescence, western blot, and monodansylcadaverine staining.

RESULTS

Autophagy proteins Beclin1 and LC3 were highly expressed, whereas p62, glutathione peroxidase 4, and p53 were lowly expressed in EMS patients. Rapamycin decreased cell viability but increased iron content, reactive oxygen species, lipid peroxide production, the number of ferroptotic mitochondria, and the expression of autophagy proteins in EMS cells, while si-Atg5 showed opposite effects. Additionally, Erastin reversed the impact of si-Atg5 on EMS cells.

CONCLUSION

Our findings suggest that autophagy-dependent ferroptosis plays a role in EMS progression.

Integrating ferroptosis-related genes (FRGs) and prognostic models to enhance UCEC outcome prediction and therapeutic insights

Ferroptosis is closely associated with uterine corpus endometrial carcinoma (UCEC) development. This project aimed to identify new potential biomarkers to predict the prognosis of UCEC. In this work, UCEC transcriptome data along with clinical information was retrieved from the TCGA database including a total of 382 FRGs. We performed univariate Cox regression analysis to evaluate ferroptosis-related genes (FRGs) for prognostic significance. The genes with prognostic significance were then analyzed using LASSO-Cox to construct a prognosis model. The model genes were further characterized through various proteomic analyses and expression detection in clinical samples. A multivariate Cox regression model was constructed containing four FRGs (CDKN1A, CDKN2A, CEBPG, NOS2). Among four FRGs, higher expressions of CDKN2A, CEBPG, and NOS2 were associated with poorer overall survival probability, while higher expression of CDKN1A was associated with better overall survival probability. The area under the receiver operating characteristic curve of the risk model was 0.617, 0.688, and 0.693 for 1 year, 3 years, and 5 years, respectively. Moreover, proteomic analysis showed that the protein expression of CDKN1A, CDKN2A, and CEBPG was higher in tumor tissues than that in normal tissues. Higher protein expression of CDKN1A and CDKN2A predicted poorer survival probability. Besides, CDKN1A protein had an interaction relationship with CDKN2A protein or NOS2 protein. In clinical samples, all four FRGs were upregulated in UCEC tissues, regardless of gene expression or protein expression. Our four FRGs risk model provides new insights for predicting the prognosis of UCEC patients.

Emerging roles and therapeutic potentials of ferroptosis: from the perspective of 11 human body organ systems

Since ferroptosis was first described as an iron-dependent cell death pattern in 2012, there has been increasing interest in ferroptosis research. In view of the immense potential of ferroptosis in treatment efficacy and its rapid development in recent years, it is essential to track and summarize the latest research in this field. However, few writers have been able to draw on any systematic investigation into this field based on human body organ systems. Hence, in this review, we provide a comprehensive description of the latest progress in unveiling the roles and functions, as well as the therapeutic potential of ferroptosis, in treating diseases from the aspects of 11 human body organ systems (including the nervous system, respiratory system, digestive system, urinary system, reproductive system, integumentary system, skeletal system, immune system, cardiovascular system, muscular system, and endocrine system) in the hope of providing references for further understanding the pathogenesis of related diseases and bringing an innovative train of thought for reformative clinical treatment.

Characterization of a fluorescence imaging probe that exploits metabolic dependency of ovarian clear cell carcinoma

The purpose of this study is to clarify the metabolic dependence of ovarian clear cell carcinoma (CCC) by comparing normal tissues and to examine the applicability of fluorescence imaging probe to exploit these metabolic differences. Enhanced glutathione synthesis was supported by the increased uptake of related metabolites and elevated expression levels of genes. Accumulation of intracellular iron and lipid peroxide, induction of cell death by inhibition of the glutathione synthesis pathway indicated that ferroptosis was induced. The activation of γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), a fluorescent imaging probe that recognizes γ-glutamyl transferase, which is essential for the synthesis of glutathione, was investigated in fresh-frozen surgical specimens. gGlu-HMRG detected extremely strong fluorescent signals in the tumor lesions of CCC patients, compared to normal ovaries or endometrium. These results revealed that CCC occurs in the stressful and unique environment of free radical-rich endometrioma, and that glutathione metabolism is enhanced as an adaptation to oxidative stress. Furthermore, a modality that exploits these metabolic differences would be useful for distinguishing between CCC and normal tissues.

Spermidine suppresses oxidative stress and ferroptosis by Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway to alleviate ovarian damage

AIMS

Oxidative stress is considered to be one of the culprits of ovarian dysfunction. Spermidine (SPD) is a natural aliphatic polyamine that is widely present in living organisms and has been shown to exert preventive effects on various ageing-related diseases. This study seeks to investigate the potential preventive and protective effects of SPD on ovarian oxidative damage.

MAIN METHODS

Ovarian oxidative stress model in C57BL/6 mice was established by 3-nitropropionic acid. Female mice were administrated 10 mg/kg or 15 mg/kg SPD. The estrous cycle, serum hormone levels and mating test were measured to evaluate ovarian function. Follicle counts and AMH levels to assess ovarian reserve. Masson's trichrome to assess ovarian fibrosis. TUNEL analysis to evaluate follicular granulosa cells (GCs) apoptosis. Oxidative stress and autophagy indicators (Nrf2, HO-1, GPX4, LC3B, P62) were measured in vivo and in vitro. RNA-sequencing was performed on SPD-treated GC to study the effects of SPD on Akt and FHC/ACSL4 signaling.

KEY FINDINGS

SPD supplementation improved ovarian endocrine function and reproductive capacity in oxidative stress mice. SPD regularized the estrous cycle and alleviated oxidative stress. Furthermore, SPD increased the ovarian reserve, reducing GC apoptosis by activating the Nrf2/HO-1/GPX4 pathway. RNA-sequencing showed that SPD induced 230 genes changes in porcine GC, which were mainly involved in oocyte meiosis, arginine biosynthesis and glutathione metabolism pathways. SPD attenuated H2O2-induced ferroptosis by regulating Akt/FHC/ACSL4 signaling.

SIGNIFICANCE

SPD alleviates oxidative stress and ferroptosis by regulating the Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway, which may be a novel potential strategy to protect ovarian oxidative damage.

Iron deposition in ovarian endometriosis evaluated by magnetic resonance imaging R2* correlates with ovarian function

RESEARCH QUESTION

Does iron overload in patients with endometriosis affect ovarian function? Can a method be developed to visually reflect this?

DESIGN

Magnetic resonance imaging (MRI) R2* was used to evaluate the correlation between iron deposition of ovarian and anti-Müllerian hormone (AMH) in patients with endometriosis. All patients underwent T2* MRI scanning. Serum AMH levels were measured preoperatively. The area of focal iron deposition, iron content of the cystic fluid and AMH levels between the endometriosis and control groups were compared using non-parametric tests. The effects of iron overload on AMH secretion in mouse ovarian granulosa cells were investigated by adding different concentrations of ferric citrate to the medium.

RESULTS

A significant difference was found between endometriosis and control groups in area of iron deposition (P < 0.0001), cystic fluid iron content (P < 0.0001), R2* of lesions (P < 0.0001) and R2* of the cystic fluid (P < 0.0001). Negative correlations were found between serum AMH levels and R2* of cystic lesions in patients with endometriosis aged 18-35 years (rs = -0.6484, P < 0.0001), and between serum AMH levels and R2* of cystic fluid (rs = -0.5074, P = 0.0050). Transcription level (P < 0.0005) and secretion level (P < 0.005) of AMH significantly decreased with the increase in iron exposure.

CONCLUSION

Iron deposits can impair ovarian function, which is reflected in MRI R2*. Serum AMH levels and R2* of cystic lesions or fluid in patients aged 18-35 years had a negative correlation with endometriosis. R2* can be used to reflect the changes of ovarian function caused by iron deposition.

The role of iron in the pathogenesis of endometriosis: a systematic review

STUDY QUESTION

What is the role of iron in the pathophysiology of endometriosis?

SUMMARY ANSWER

Iron excess is demonstrated wherever endometriotic tissues are found and is associated with oxidative stress, an inflammatory micro-environment, and cell damage; the iron-mediated oxidative stress is independently linked to subfertility, symptom severity, and malignant transformation.

WHAT IS KNOWN ALREADY

Iron is found in excess in endometriotic tissues, and multiple mechanisms have been studied and posited to explain this. It is clear that iron excess plays a vital role in promoting oxidative stress and cell damage. The evidence base is large, but no comprehensive reviews exist to summarize our understanding and highlight the overarching themes to further our understanding and suggest future directions of study for the field.

STUDY DESIGN SIZE DURATION

This systematic review with a thematic analysis retrieved studies from the PubMed, Embase, Web of Science, and Cochrane Library databases and searches were conducted from inception through to August 2022. Human and animal studies published in the English language were included and identified using a combination of exploded MeSH terms ('Iron' and 'Endometriosis') and free-text search terms ('Iron', 'Ferric', 'Ferrous', 'Endometriosis', 'Endometrioma').

PARTICIPANTS/MATERIALS SETTING METHODS

This review was reported in accordance with the PRISMA guidelines. All studies reporting original data concerning the role of iron or iron complexes in the pathophysiology of endometriosis were included. Studies that did not report original data or provided a review of the field were excluded. Bias analysis was completed for each included study by using the Newcastle-Ottawa scoring system.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 776 records identified and these were screened down to 53 studies which met the eligibility criteria, including 6 animal and 47 human studies, with 3556 individual participants. Iron excess is demonstrated in various tissues and fluids, including ovarian endometriomas, ovarian follicles, ectopic endometriotic lesions, and peritoneal fluid. Markers of oxidative stress are strongly associated with high iron levels, and aberrant expression of iron-transport proteins has been demonstrated. Abnormal resistance to ferroptosis is likely. Iron-mediated oxidative stress is responsible for a pro-inflammatory micro-environment and is linked to subfertility, symptom severity, and, possibly, malignant transformation.

LIMITATIONS REASONS FOR CAUTION

A minority of the included studies were of objectively low quality with a high risk of bias and may lead to misleading conclusions. Additionally, multiple studies failed to appropriately characterize the included patients by known confounding variables, such as menstrual cycle phase, which may introduce bias to the findings.

WIDER IMPLICATIONS OF THE FINDINGS

Current literature depicts a central role of aberrant iron mechanics and subsequent oxidative stress in endometriosis. It is likely that iron excess is at least partly responsible for the persistence and proliferation of ectopic endometriotic lesions. As such, iron mechanics represent an attractive target for novel therapeutics, including iron chelators or effectors of the iron-oxidative stress pathway. There are significant gaps in our current understanding, and this review highlights and recommends several topics for further research. These include the role of iron chelation, resistance to ferroptosis, the relationship between iron excess and localized hypoxia, systemic iron pathophysiology in endometriosis, and the role of oxidative stress in malignant transformation.

STUDY FUNDING/COMPETING INTERESTS

J.W. and S.G.P. are supported by clinical fellowships at Liverpool University Hospital NHS Foundation trust. No additional funding was requested or required for the completion of this work. C.J.H. is supported by a Wellbeing of Women project grant (RG2137). D.K.H. is supported by a Wellbeing of Women project grant (RG2137) and an MRC clinical research training fellowship (MR/V007238/1). The authors have no conflicts of interest to declare.

REGISTRATION NUMBER

A protocol was prospectively registered with the PROSPERO database in August 2021 (CRD42021272818).

The Role of Ferroptosis in Placental-Related Diseases

Ferroptosis is a recently identified form of programmed cell death which is different from apoptosis, pyroptosis, necrosis, and autophagy. It is uniquely defined by redox-active iron-dependent hydroxy-peroxidation of polyunsaturated fatty acid (PUFA)-containing phospholipids and a loss of lipid peroxidation repair capacity. Ferroptosis has recently been implicated in multiple human diseases, such as tumors, ischemia-reperfusion injury, acute kidney injury, neurological diseases, and asthma among others. Intriguingly, ferroptosis is associated with placental physiology and trophoblast injury. Circumstances such as accumulation of lipid reactive oxygen species (ROS) due to hypoxia-reperfusion and anoxia-reoxygenation of trophoblast during placental development, the abundance of trophoblastic iron and PUFA, physiological uterine contractions, or pathological placental bed perfusion, cause placental trophoblasts' susceptibility to ferroptosis. Ferroptosis of trophoblast can cause placental dysfunction, which may be involved in the occurrence and development of placenta-related diseases such as gestational diabetes mellitus, preeclampsia, fetal growth restriction, preterm birth, and abortion. The regulatory mechanisms of trophoblastic ferroptosis still need to be explored further. Here, we summarize the latest progress in trophoblastic ferroptosis research on placental-related diseases, provide references for further understanding of its pathogenesis, and propose new strategies for the prevention and treatment of placental-related diseases.

Isoorientin reverses lung cancer drug resistance by promoting ferroptosis via the SIRT6/Nrf2/GPX4 signaling pathway

Cisplatin, or DDP, is a highly successful and well-known chemotherapy drug used to treat cancer. Acquired resistance to chemotherapy is a major clinical concern, yet the mechanisms of this resistance are still unknown. Ferroptosis is a type of cell death distinct from other forms, fueled by a buildup of iron-associated lipid reactive oxygen species (ROS). Gaining insight into the process of ferroptosis could lead to novel treatments for overcoming cancer resistance. In this study, the combination of isoorientin (IO) and DDP treatment resulted in a significant decrease in the viability of drug-resistant cells, a substantial increase in intracellular iron, malondialdehyde (MDA) and ROS concentrations, a notable decrease in glutathione concentration, and the occurrence of ferroptosis in cells, as revealed by in vitro and in vivo experiments. Additionally, there was a decrease in the expression of nuclear factor-erythroid factor 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), and sirtuin 6 (SIRT6) proteins, and an increase in cellular ferroptosis. Isoorientin acts as a mediator to regulate cellular ferroptosis and reverse drug resistance in lung cancer cells by controlling the SIRT6/Nrf2/GPX4 signaling pathway. The findings of this study suggest that IO can promote ferroptosis and reverse drug resistance in lung cancer through the SIRT6/Nrf2/GPX4 signaling pathway, thus offering a theoretical basis for its potential clinical application.

Identification of a Novel Cuproptosis-Related Gene Signature in Eutopic Endometrium of Women with Endometriosis

Endometriosis (EMs) is a life-long endocrine disorder and a common cause for female infertility and pelvic pain. The key characteristics of eutopic endometrium of EMs patients are high proliferative and migratory potentials. Cuproptosis is a recently identified copper- and-mitochondrial-dependent regulated cell death. Regretfully, its role in EMs remains unclear. In this study, Kyoto Encyclopedia of Genes and Genomes analyses of differentially expressed genes (DEGs) indicated strong activation of the PI3K-Akt-mTOR pathway and biological process analysis reported positive regulation of kinase activity. Next, we screened 11 cuproptosis-related DEGs and found all of them were downregulated in the EMs group, which indicated the suppression of cuproptosis in EMs. One key cuproptosis-related gene, PDHA1, was selected via support vector machine, random forest algorithm and lasso regularization to build a risk-scoring model, which was tested in both internal and external validations. In conclusion, the downregulation and kinase activity of PDHA1 may function with the PI3K-Akt-mTOR pathway in some way, which could suppress the cuproptosis level and account for the cancer-like pathology in EMs.

Current Understanding of and Future Directions for Endometriosis-Related Infertility Research with a Focus on Ferroptosis

BACKGROUND

To date, the development of therapy for endometriosis and disease-related infertility remains a major challenge. Iron overload caused by periodic bleeding is a hallmark of endometriosis. Ferroptosis is an iron- and lipid-reactive oxygen species-dependent type of programmed cell death that is distinct from apoptosis, necrosis, and autophagy. This review summarizes the current understanding of and future directions for the research and treatment of endometriosis and disease-related infertility, with the main focus on the molecular basis of ferroptosis in endometriotic and granulosa cells.

METHODS

Papers published between 2000 and 2022 in the PubMed and Google Scholar databases were included in this review.

RESULTS

Emerging evidence suggests that ferroptosis is closely linked to the pathophysiology of endometriosis. Endometriotic cells are characterized by ferroptosis resistance, whereas granulosa cells remain highly susceptible to ferroptosis, suggesting that the regulation of ferroptosis is utilized as an interventional target for research into the treatment of endometriosis and disease-related infertility. New therapeutic strategies are urgently needed to efficiently kill endometriotic cells while protecting granulosa cells.

CONCLUSIONS

An analysis of the ferroptosis pathway in in vitro, in vivo, and animal research enhances our understanding of the pathogenesis of this disease. Here, we discuss the role of ferroptosis modulators as a research approach and potential novel treatment for endometriosis and disease-related infertility.

A Lifelong Impact on Endometriosis: Pathophysiology and Pharmacological Treatment

Endometriosis is a chronic inflammatory disease associated with bothersome symptoms in premenopausal women and is complicated with long-term systemic impacts in the post-menopausal stage. It is generally defined by the presence of endometrial-like tissue outside the uterine cavity, which causes menstrual disorders, chronic pelvic pain, and infertility. Endometriotic lesions can also spread and grow in extra-pelvic sites; the chronic inflammatory status can cause systemic effects, including metabolic disorder, immune dysregulation, and cardiovascular diseases. The uncertain etiologies of endometriosis and their diverse presentations limit the treatment efficacy. High recurrence risk and intolerable side effects result in poor compliance. Current studies for endometriosis have paid attention to the advances in hormonal, neurological, and immunological approaches to the pathophysiology and their potential pharmacological intervention. Here we provide an overview of the lifelong impacts of endometriosis and summarize the updated consensus on therapeutic strategies.

Identification of iron metabolism-related predictive markers of endometriosis and endometriosis-relevant ovarian cancer

Endometriosis is associated with ovarian cancers, mainly endometrioid and clear-cell carcinomas. Iron metabolism has been shown to play a role in endometriosis. Therefore, it is vital to explore the relationship between iron metabolism and ovarian cancer and to identify novel markers for diagnostics and therapeutics. The endometriosis dataset GSE51981 and the ovarian cancer dataset GSE26712 were obtained from the gene expression omnibus database, and differentially expressed genes were identified. Iron metabolism genes were obtained from molecular signatures database, and hub genes from the 3 datasets were obtained. Seven hub genes were identified by bioinformatic analysis, and 3 hub genes (NCOA4, ETFDH, and TYW1) were further selected by logistic regression, which were verified in an independent endometriosis dataset (GSE25628) and ovarian cancer dataset (GSE14407), showing good predictive diagnostic value (area under the receiver operating characteristic curve of 0.88 and 0.9, respectively). Gene Ontology, gene set enrichment analysis, and immune infiltration analysis further confirmed the related functions, pathways, and immune relationship between iron metabolism and ovarian cancer. This study highlights the potential of targeting iron metabolism in the prevention of potential ovarian cancer and in the further exploration of endometriosis and endometriosis-relevant ovarian cancer therapeutics.

Association of iron metabolism markers, socioeconomic and lifestyle factors with endometriosis: A cross-sectional study

BACKGROUND

Evidence on the link between iron metabolism markers and endometriosis is limited. We aimed to investigate the associations of iron metabolism markers, including serum ferritin level and transferrin saturation, with endometriosis.

METHODS

This study involved 6551 participants from the National Health and Nutrition Examination Survey (NHANES). Univariable and multivariable logistic regression analyses were used to examine the linear relationships between iron metabolism markers and endometriosis. Furthermore, restricted cubic splines were used to identify the non-linear dose-response associations.

RESULTS

Univariable analysis showed that the factors associated with endometriosis included age, race, education level, and smoking status. In multivariable model, compared with lowest quartile, highest quartile of serum ferritin level was positively associated with endometriosis (OR: 2.11, 95% confidence intervals [CI]: 1.31, 3.40, P = 0.004), and third quartile of transferrin saturation positively associated with endometriosis (OR: 1.55, 95% CI: 1.05, 2.29, P = 0.033). The restricted cubic splines showed the non-linear (inverted U-shape) associations between serum ferritin level and transferrin saturation and endometriosis (all P for non-linear＜0.01), indicating that the ORs of endometriosis increased with serum ferritin level and transferrin saturation up to the turning point and thereafter the ORs of endometriosis did not significantly increase with the increasing serum ferritin and transferrin saturation.

CONCLUSIONS

Our findings suggests that serum ferritin level and transferrin saturation were positively associated with endometriosis. Serum ferritin and transferrin saturation may be an important marker for endometriosis. Future prospective and longitudinal studies are necessary to better understand these findings.

Regulatory mechanism and research progress of ferroptosis in obstetrical and gynecological diseases

Ferroptosis is a novel type of regulated cell death driven by iron-dependent lipid peroxidation, which is distinguished from traditional types of programmed cell death, such as apoptosis, proptosis and necrosis et al. Impaired iron homeostasis, lipid peroxidation and antioxidants depletion are three hallmarks of ferroptosis. Over the past years, emerging studies support the notion that ferroptosis might be involved in the pathology of obstetrical and gynecological diseases, including preeclampsia (PE), endometriosis (EMs) and polycystic ovarian syndrome (PCOS). In the PE condition, the high sensitivity of trophoblasts towards ferroptosis has been found to potentially link to inflammation, suboptimal vascular remodeling and aberrant hemodynamics, which are three prominent pathophysiological features of PE. As for EMs, compromised ferroptosis of endometrial cells was associated with the formation ectopic lesions, whereas in the nearby lesions, the presence of ferroptosis was suggested to promote the progression of EMs, contributing to the relative clinical manifestations. Ferroptosis has been implicated a crucial role in the initiation of ovarian follicular atresia, which might help to manage ovulation in PCOS patients. Taken together, this review explored the basis of ferroptosis mechanisms and comprehensively summarized the latest discovery of roles of ferroptosis on PE, EMs and PCOS, gaining a deeper insight into the pathogenesis of these obstetrical and gynecological diseases and investigation of novel therapeutic interventions.

Detention and mapping of iron and toxic environmental elements in human ovarian endometriosis: A suggested combined role

BACKGROUND

Endometriosis is a disease affecting 10-15 % of women worldwide, consisting in the ectopic growth of endometrial cells outside the uterine cavity. Whist the pathogenetic mechanisms of endometriosis remain elusive and contemplating even environmental causes, iron deposits are common in endometrial lesions, indicating an altered iron metabolism at this level. This study was undertaken to reveal a possible relationship between iron dysmetabolism and accumulation of environmental metals.

METHODS

By combining histological and histochemical analysis (H&E and Perl's staining) with μ- and nano- synchrotron-based (SR-based) X-ray Fluorescence (XRF) microscopy, we investigated the distribution of iron and other elements in the ovarian endometriomas of 12 endometriosis patients and in 7 healthy endometrium samples.

RESULTS

XRF microscopy expanded the findings obtained by Perl's staining, revealing with an exceptional sensitivity intracellular features of iron accumulation in the epithelial endometrium, stroma and macrophages of the endometriotic lesions. XRF evidenced that iron was specifically accumulated in multiple micro aggregates, reaching concentrations up to 10-20 % p/p. Moreover, by XRF analysis we revealed for the first time the retention of a number of exogenous and potentially toxic metals such as Pb, Br, Ti, Al Cr, Si and Rb partially or totally co-localizing with iron.

CONCLUSION

μXRF reveals accumulation and colocalization of iron and environmental metals in human ovarian endometriosis, suggesting a role in the pathogenesis of endometriosis.

The role of endoplasmic reticulum stress in endometriosis

Endometriosis is a chronic gynecologic disorder characterized by abnormal growth of endometrium-like tissues in the ectopic regions of the pelvic peritoneum. The pathophysiology of endometriosis is not completely understood; however, excessive endometrial cell proliferation together with resistance to apoptosis facilitates the migration, implantation, and survival of endometrial cells in the distant sites. Endoplasmic reticulum (ER) stress response (also called unfolded protein response) is a cellular defense mechanism triggered by ER stress. When severe enough, the so-called response initiates cell suicide, i.e., apoptosis. Therefore, therapeutic induction of ER stress in endometriotic cells could promote apoptosis and contribute to the management of disease. In this review, we discuss the pathogenic role of ER stress in endometriosis and the most recent findings regarding the induction of ER stress in connection with endometriosis.

Solute Carrier Family 7 Member 11 (SLC7A11) is a Potential Prognostic Biomarker in Uterine Corpus Endometrial Carcinoma

Background

Uterine corpus endometrial carcinoma (UCEC) is a common type of gynecological cancers, second only to cervical cancer in incidence. Thus, it is necessary to develop effective therapies and identify biomarkers for its prognosis. Solute carrier family 7 member 11 (SLC7A11) is well known for its role in maintaining the intracellular glutathione level and preventing oxidative-stress-induced cell death. However, the association between SLC7A11 expression and prognosis as well as the correlation between tumor-infiltrating immune cells (TIICs) and immunotherapy of UCEC has rarely been reported. This study aims to evaluate the prognostic significance and immune cell infiltration level of SLC7A11 in UCEC.

Methods

Bioinformatics analysis tools and databases, including R software, National Center for Biotechnology Information (NCBI), The Cancer Genome Atlas (TCGA), GEPIA2, Sangerbox, Kaplan-Meier (K-M) Plotter, TISIDB, and TIMER2, were utilized to measure the expression level and clarify the clinical significance of SLC7A11 in UCEC.

Results

SLC7A11 expression was dramatically up-regulated in UCEC patients and associated with prognosis. DNA methylation levels in the SLC7A11-promoter region were significantly higher in normal participants than in patients with UCEC. We also showed that SLC7A11 overexpression was associated with TIICs, immune checkpoint blockers (ICBs), and immunotherapy response in UCEC. The half-maximal inhibitory concentration (IC50) results obtained with the cohort from TCGA showed that Z-VAD-FMK (Caspase inhibitor), S-Triphenylmethyl-L-cysteine (S-Trityl-L-cysteine), and TAE684 (ALK inhibitor) had higher IC50 values in low-expression patient (p < 0.05).

Conclusion

SLC7A11 overexpression is associated with favorable prognosis of patients with UCEC and is associated with TIICs and the responses to immunotherapy.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

I Am the 1 in 10-What Should I Eat? A Research Review of Nutrition in Endometriosis

Endometriosis is a chronic, painful, estrogen-related inflammatory disease that affects approximately 10% of the female population. Endometriosis has a significant negative impact on quality of life. Nutrition may be involved in the development and severity of endometriosis. The purpose of this paper is to discuss in detail the nutritional recommendations for patients with endometriosis. This article discusses the importance of nutrients such as polyphenols, vitamins C, D and E, PUFAs, and iron in the development of endometriosis. Alternative diets, such as the Mediterranean, anti-inflammatory, vegetarian, low-nickel and low-FODMAP diets, have also been presented in the context of their potential beneficial effects on the course of endometriosis.

Protective effects of chicoric acid on LPS-induced endometritis in mice via inhibiting ferroptosis by Nrf2/HO-1 signal axis

Chicoric acid (CA), a natural phenolic acid extracted from Mediterranean vegetable chicory, has anti-oxidative effect. We aimed to investigate the effects of CA on endometritis and clarify the underlying mechanism. C57BL/6 mice were divided into five groups: control group, LPS group, and LPS + CA groups. All mice except control group were infused of LPS into the uterus. The mice of LPS + CA groups were intraperitoneally injected CA 1 h before LPS challenge. CA significantly alleviatedLPS-induced pathological damage, MPO activity, and inflammatory cytokine production. CA significantly suppressed ferroptosis in LPS-induced endometritis. CA also attenuated LPS-induced NF-κB activation. Furthermore, Nrf2 and HO-1 expression were increased by CA. Moreover, the inhibition of CA on LPS-induced endometritis and ferroptosis were markedly prevented in Nrf2 knockdown mice. In conclusion, the results suggested CA protected mice against LPS-induced endometritisthrough inhibiting ferroptosis via Nrf2/HO-1 signaling pathway.

Transition metallo-curcumin complexes: a new hope for endometriosis?

Endometriosis is a debilitating gynecological disorder in women of reproductive age. Laparoscopy, a minimally invasive surgical procedure, provides a definitive diagnosis of the disease. Current treatments, including hormonal therapy and pain medication, are often associated with undesirable side effects limiting their long-term usage. This calls for exploring newer diagnostic and therapeutic options with minimal side effects. Curcumin is an established anti-endometriotic agent with inherent fluorescent properties; however, poor bioavailability limits its clinical utility. To address this shortcoming, various transition metals were conjugated with curcumin to improve its stability, specificity and pharmacological properties. The chemical stability, hemocompatibility and ability of the synthesized metallo-curcumin complexes (MCCs) to ameliorate endometriotic lesions were investigated. While all of the MCCs exhibited low hemolytic activity, their chemical and biological activities were largely dependent on the nature of the metal ion conjugated to the curcumin molecule. Copper-curcumin and nickel-curcumin complexes demonstrated superior therapeutic efficacy evidenced by enhanced antioxidant activity, selective cytotoxicity and increased accumulation in endometriotic cells mediated by an energy-dependent active transport process.

MELTF Might Regulate Ferroptosis, Pyroptosis, and Autophagy in Platelet-Rich Plasma-Mediated Endometrial Epithelium Regeneration

The endometrial basal layer is essential for endometrial regeneration, whose disruption leads to thin endometrium or intrauterine adhesion (IUA) with an unsatisfactory prognosis. Emerging data indicate that platelet-rich plasma (PRP) can promote endometrial proliferation, but the mechanism by which PRP regulates endometrial regeneration remains unclear. Herein, we investigated the therapeutic effects and possible mechanisms of PRP on endometrial regeneration. IUA animal model was generated by sham, mechanically damaging endometrium with or without PRP for 10 days. The uterine section in the model group showed degenerative changes with a narrow endometrial lumen, atrophic columnar epithelium, decreased number of endometrial glands, decreased endometrial thickness, and increased collagen deposition. The above disruption could be ameliorated by the PRP. Transcriptome sequencing analysis displayed that the retinol metabolism pathway and extracellular matrix (ECM) receptor interaction pathway were up-regulated and enriched in differential expression genes (DEGs). Melanotransferrin (MELTF) was the key up-regulated gene in PRP-induced endometrial regeneration, which was verified in vivo and in vitro. Ferroptosis, autophagy, and pyroptosis were down-regulated in PRP-treated Ishikawa cells. Conclusively, PRP promotes endometrium regeneration by up-regulating the retinol metabolism and ECM receptor interaction pathway with MELTF. Meanwhile, PRP could also inhibit endometrial epithelial cell death by regulating ferroptosis, autophagy, and pyroptosis.

Effective prediction of potential ferroptosis critical genes in clinical colorectal cancer

Background

Colon cancer is common worldwide, with high morbidity and poor prognosis. Ferroptosis is a novel form of cell death driven by the accumulation of iron-dependent lipid peroxides, which differs from other programmed cell death mechanisms. Programmed cell death is a cancer hallmark, and ferroptosis is known to participate in various cancers, including colon cancer. Novel ferroptosis markers and targeted colon cancer therapies are urgently needed. To this end, we performed a preliminary exploration of ferroptosis-related genes in colon cancer to enable new treatment strategies.

Methods

Ferroptosis-related genes in colon cancer were obtained by data mining and screening for differentially expressed genes (DEGs) using bioinformatics analysis tools. We normalized the data across four independent datasets and a ferroptosis-specific database. Identified genes were validated by immunohistochemical analysis of pathological and healthy clinical samples.

Results

We identified DEGs in colon cancer that are involved in ferroptosis. Among these, five core genes were found: ELAVL1, GPX2, EPAS1, SLC7A5, and HMGB1. Bioinformatics analyses revealed that the expression of all five genes, except for EPAS1, was higher in tumor tissues than in healthy tissues.

Conclusions

The preliminary exploration of the five core genes revealed that they are differentially expressed in colon cancer, playing an essential role in ferroptosis. This study provides a foundation for subsequent research on ferroptosis in colon cancer.

The Relationship Between Ferroptosis and Diseases

Ferroptosis is an iron-dependent mode of cell death. It can occur through two major pathways, exogenous (or transporter-dependent) and endogenous (or enzyme-regulated) pathways are activated by biological or chemical inducers, and glutathione peroxidase activity is inhibited, which causes intracellular iron accumulation and lipid Peroxidation. Ferroptosis is closely related to the pathological process of many diseases. How to intervene in the occurrence and development of related diseases by regulating ferroptosis has become a hot research topic. At present, studies have shown that ferroptosis is found in common diseases such as tumors, inflammatory diseases, bacterial infections, pulmonary fibrosis, hepatitis, inflammatory bowel disease, neurodegenerative diseases, kidney injury, ischemia-reperfusion injury and skeletal muscle injury. This article reviews the characteristics and mechanism of ferroptosis, and summarizes how ferroptosis participates in the pathophysiological process in various systemic diseases of the body, which may provide new references for the treatment of clinical diseases in the future.

Ferroptosis induced by iron overload promotes fibrosis in ovarian endometriosis and is related to subpopulations of endometrial stromal cells

Endometriosis (EMs) is defined as the presence of tissue somewhat resembling endometrial glands and stroma outside the uterus; the retrograded endometrium grows in the peritoneal cavity and elicits fibrosis. Ferroptosis is a recently discovered form of programmed cell death, which is iron-dependent. The induction of ferroptosis has been found to participate in fibrosis. However, the relationship between EMs fibrosis and ferroptosis remains unknown. In this study, we confirmed that the iron content in ectopic stromal tissue in ovarian EMs is significantly increased. We explored the role of iron-induced ferroptosis in the pathogenesis of ovarian EMs fibrosis for the first time. We found that ferroptosis in ectopic tissues was significantly enhanced than that in eutopic tissues. Furthermore, we performed in vivo drug screening and found that ferroptosis induced by ferric ammonium citrate (FAC) could aggravate fibrosis. To clarify the mechanism of this process, the stromal composition of human uterine endometrium and endometrial tissue was characterized. Fibroblast-specific protein-1 was used for fibroblasts, smooth muscle actin alpha for myofibroblasts, and platelet-derived growth factor receptor beta (CD140b) for mesenchymal stromal cells (MSCs). The results demonstrated that the percentage of myofibroblasts was higher and the portion of MSCs was lower in ectopic endometrial stroma than those in eutopic endometrium. Moreover, the proportion of MSCs decreased significantly and the percentage of myofibroblasts increased considerably after FAC treatment in vitro. However, disruption of intracellular iron levels or ferroptosis via chelation of intracellular iron deferoxamine mesylate or ferroptosis inhibitor ferrostatin-1 could reverse this process, indicating that iron-induced ferroptosis plays a vital role in ovarian EMs fibrosis. Considering that iron accumulation can feed the Fenton reaction to generate unquenchable amounts of free radicals, causing ferroptosis and tissue damage and thereby contributing to fibrosis, we validated the underlying mechanism that excess iron can facilitate fibrotic responses. Collectively, these data provide evidence that supernumerary iron is a key regulator in promoting MSCs ferroptosis and inducing ovarian EMs fibrosis.

Potential clinical implications of iron metabolism in ovarian endometriosis

OBJECTIVE

The purpose of this study was to investigate iron metabolism indices in ovarian endometriosis (OEMs) and to demonstrate the potential clinical implications in the initiation and development of OEMs.

METHODS

Three datasets in Gene Expression Omnibus (GEO) database were selected to assess the expression levels of iron metabolites in endometrial tissues from patients with EMs and the health. To evaluate the differential expression of serum iron indices , hospitalized patients with OEMs and health examinees in Jilin University Second Hospital from November 2018 to December 2019 were recruited. Serum samples were obtained from 38 patients with OEMs and 36 health examinees. To compare the iron metabolism between peripheral circulation blood and local ectopic lesion, cyst fluid samples were obtained from 15 patients with ovarian chocolate cyst at the time of surgery. Iron metabolism indices include iron, transferrin (TF), ferritin, and unsaturated iron-binding capacity (UIBC)), which were measured by automatic biochemical analyzer.

RESULTS

The present study indicated the increased levels of the iron storage protein, ferritin, in the endometriotic tissues of patients with EMs. The expression of iron and ferritin in cyst fluid of patients with OEMs showed higher than that in serum, the results of TF and UIBC were opposite (P < 0.05). There was no statistical difference in the content of iron metabolites between patients with OEMs and the healthy examinees(P > 0.05).

CONCLUSION

The ovarian chocolate cyst fluid and endometriotic tissues in patients with OEMs could more directly reflect the pathological changes of local ectopic lesion, which usually manifested as high levels of free iron and/or iron deposits in the ectopic sites. The implications of our work suggest iron metabolites in the serum may have potentially limited value as circulating biomarkers for OEMs. The iron variation in local lesions may be not only regulated by liver that mainly manipulate the systematic iron homeostasis, but also be tuned by the iron regulatory protein (IRP)/ iron responsive element (IRE) system. In summary, the iron metabolites, especially the iron and ferritin in the cyst fluid and endometriotic tissues, are meaningful biomarkers involved in the process of pathophysiology and pathogenesis of OEMs.

Huayu Jiedu Fang Protects Ovarian Function in Mouse with Endometriosis Iron Overload by Inhibiting Ferroptosis

Endometriosis (EM) is a common chronic inflammatory disease in women. Sampson's retrograde menstruation theory is the most widely accepted theory of EM pathogenesis. The periodic bleeding of ectopic lesions is an important pathological feature of this disease, and the occurrence and progression of EM are closely associated with the iron overload caused by ectopic lesions. However, animal models that simulate menstrual-blood reflux and hemorrhage from EM lesions are lacking. In this study, we performed intraperitoneal injection of endometrial fragments and periodic intraperitoneal blood injection to simulate the real cause and disease state of EM and successfully constructed a mouse model of EM iron overload. Our research found that the number, size, and degree of adhesion of EM lesions in the iron-overload model mouse were significantly higher than those in the model mouse. Moreover, the iron concentration in the abdominal fluid and ovary significantly increased, and the level of malondialdehyde (MDA) in the ovary increased. Conversely, GPX4, GSH, and other anti-ferroptosis-related proteins were downregulated, proving the occurrence of ferroptosis. Huayu Jiedu Fang (HYJDF) is an empirical prescription for EM treatment. This study combined animal experiments, UHPLC-QE-MS analysis, and network pharmacology to analyze whether HYJDF can inhibit ferroptosis to slow down the progression of EM and protect ovarian function. Based on the constructed iron-overload model, HYJDF can reduce the volume of EM lesions and the degree of adhesion, downregulate the total iron concentration in the peritoneal fluid and ovary, upregulate GPX4 expression and GSSG in the ovary, downregulate the level of MDA in the ovary, and promote the development of follicles. We further confirmed that HYJDF can inhibit the progression of EM disease and improve the ovarian function of the model mouse by inhibiting ferroptosis. Finally, through UHPLC-QE-MS and network pharmacology analysis, the natural compounds in HYJDF were identified and verified and the regulatory effect of HYJDF on the EM ferroptosis pathway through the IL-6/hepcidin pathway was preliminarily elucidated.

Vegan nutrition: a preliminary guide for health professionals

Since the beginning of the 21st century, interest in vegan diets has been rapidly increasing in most countries. Misconceptions about vegan diets are widespread among the general population and health professionals. Vegan diets can be health-promoting and may offer certain important advantages compared to typical Western (and other mainstream) eating patterns. However, adequate dietary sources/supplements of nutrients of focus specific to vegan diets should be identified and communicated. Without supplements/fortified foods, severe vitamin B12 deficiency may occur. Other potential nutrients of focus are calcium, vitamin D, iodine, omega-3 fatty acids, iron, zinc, selenium, vitamin A, and protein. Ensuring adequate nutrient status is particularly important during pregnancy, lactation, infancy, and childhood. Health professionals are often expected to be able to provide advice on the topic of vegan nutrition, but a precise and practical vegan nutrition guide for health professionals is lacking. Consequently, it is important and urgent to provide such a set of dietary recommendations. It is the aim of this article to provide vegan nutrition guidelines, based on current evidence, which can easily be communicated to vegan patients/clients, with the goal of ensuring adequate nutrient status in vegans.

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.

Ferroptosis: Opportunities and Challenges in Treating Endometrial Cancer

Ferroptosis, a new way of cell death, is involved in many cancers. A growing number of studies have focused on the unique role of ferroptosis on endometrial cancer. In this study, we made a comprehensive review of the relevant articles published to get deep insights in the association of ferroptosis with endometrial cancer and to present a summary of the roles of different ferroptosis-associated genes. Accordingly, we made an evaluation of the relationships between the ferroptosis-associated genes and TNM stage, tumor grade, histological type, primary therapy outcome, invasion and recurrence of tumor, and accessing the different prognosis molecular typing based on ferroptosis-associated genes. In addition, we presented an introduction of the common drugs, which targeted ferroptosis in endometrial cancer. In so doing, we clarified the opportunities and challenges of ferroptosis activator application in treating endometrial cancer, with a view to provide a novel approach to the disease.

Ferroptosis as a mechanism of non-ferrous metal toxicity

Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.